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Ptbamnce/Al as a High-Efficiency Catalyst for Nox Storage and Reduction as a Function of Cycling Conditions Abstract The aim of the study was to present novel PtBaMnCe/Al material as the high-efficiency catalyst for NOx storage and reduction (NSR) application. In the first part of this paper, the performance of PtBaMnCe/Al catalyst on the NOx conversion to N2 was presented. Compared with traditional model PtBa/Al catalyst, the PtBaMnCe/Al catalyst exhibit at least 2 times higher in NOx conversion efficiency at 400 oC. More interesting, ammonia yield on PtBaMnCe/Al is limited to a very lower level (nil). With 6% H2 in the rich pulse, the 94% of NOx conversion to N2 can be obtained with PtBaMnCe/Al catalyst at 400 oC. The second part deals with sulfur resistance of PtBaMnCe/Al catalyst. Sulfur poisoning, regeneration of sulfated catalysts and NOx removal efficiency under rich/lean cycling conditions are studied. PtBaMnCe/Al is more sulfur resistant than PtBa/Al. However, the sulfur poisoning is irreversible and only 85% of the initial NOx conversion could be recovered after the regeneration treatment. Keywords: Emission Control; Lean Burn; NOx Storage and Reduction; Sulfur in Fuel; Lean/rich cycle Go to Introduction Lower CO2 emissions from automotive sources are necessary and lead to the development of diesel and lean-burn engines. However, exhaust gases from these engines contain NOx in excess of O2, which makes NOx reduction into N2 very difficult. One possible solution is the use of the NOx storage reduction (NSR) catalyst [ -3], working in transient periods: during the lean condition, NOx are firstly oxidized and stored as nitrites or nitrates on a basic material, usually barium oxide. Periodically, the catalyst is regenerated: the stored NOx NO2) are reduced in N2 during a short excursion in rich condition. Nevertheless, the major drawback of this system is the deactivation of the catalyst, mainly due to sulfur poisoning [2,3], and ammonia emission can be formed during the short excursion under rich conditions, especially when hydrogen is used as reducer [ -6]. In our previous study [5], ammonia intermediate pathway was clearly demonstrated for the reduction of the stored NOx with H2. It appears that, when hydrogen is missing in the rich pulses, that are fully converted, the ammonia selectivity tends to be nil because the produced NH3 can react with the remaining stored NOx. In opposition, if some hydrogen remains, the ammonia selectivity increases with the amount of excessive hydrogen. It induces that NOx reduction with H2 into ammonia is faster than the NOx selective catalytic reduction with ammonia. This is a fundamental result for our next step: catalyst modification for a better NOx conversion to N2. In the first part of this paper, our latest result in catalyst improvement with a multi-component PtBaMnCe/Al sample will be presented. In the second part of this paper, the impact of sulfur in gasoline on the performance of NSR catalyst will be discussed. Sulfur poisoning, regeneration of sulfated catalysts and NOx removal efficiency under rich/lean cycling conditions are studied [7]Go to Experimental Catalyst preparation The detailed preparation protocols are reported in our previous studies [8]. The reference catalyst contains 1 wt% Pt and 20 wt% BaO supported on alumina. Alumina powder (230 m2.g−1) was immersed in an ammonia solution and was firstly impregnated using a barium nitrate salt. After evaporation at 80 oC and drying at 120 oC, the obtained powder was treated at 700°C under synthetic dry air. Platinum was then impregnated using a Pt (NH3)2(NO2)2 aqueous solution. After drying, the catalyst was pre-treated at 700 oC for 4h under N2, and finally stabilized at 700 oC for 4h under a mixture containing 10% O2, 5% H2O in N2. The modified samples were prepared using the same protocol except that the nitrate salts of Mn(IV), and Ce (III) were simultaneously added with the barium salt. In this case, a part of alumina was replaced to assure the desired “additive/Ba” molar ratio. The catalysts containing both Mn and Ce were also prepared. In this case, Mn/Ba and Ce/Ba molar ratio are always 1. The Mn–Ce modified catalysts are noted PtBaMnCe/Al. Catalytic activity measurements: NOx conversion in cycling conditions Click here to view Large Table 1 Before measurement, the catalyst (60mg) was pre-treated in situ at 450 oC under 3% H2, 10% H2O, 10% CO2 and N2 for 15min. The sample was then cooled down to 400 oC under the same mixture. The NOx conversion was studied in cycling condition by alternatively switching between lean (60s) and rich (3s) conditions using electro-valves. The gas composition is described (Table 1). NO and NO2 were followed by chemiluminescence, N2O by specific FTIR, H2 by mass spectrometry. Before the analyzers, H2O was trapped in a condenser at 0 oC. The trapped water was analyzed by two different HPLCs for NH4+, NO2− and NO3-. NO2- and NO3− were added to the unconverted NOx. The N2 selectivity is calculated assuming no other N-compounds than NO, NO2, N2O, NH3. Go to Results and Discussions NOx storage-reduction efficiency of PtBaMnCeX/Al catalystThe influence of cerium-manganese addition on the NOx storage-reduction efficiency of PtBa/Al was studied at 400 oC using first 3% H2 in the rich pulses. For comparison, results obtained with the PtBa/Al reference catalyst are also reported in (Figures 1 & 2). At 400 oC with 3% H2 in the rich pulses, the hydrogen conversion reaches 100% with PtBaMnCe/Al catalyst (Table 2). Hence, the NOx conversion could be limited by the reducer amount. However, the NOx conversion to NH3 over this sample is higher than PtBa/Al catalylst. More interestingly, the ammonia selectivity becomes nil with PtBaMnCe/Al catalyst. Click here to view Large Table 2 Click here to view Large Image 1 Thus, with this condition with full H2 conversion, the in situ formed ammonia is able to react with the remaining stored NOx to produce N2. With 6% H2 in the rich pulses (Table 1), a significant NOx conversion improvement is observed with PtBaMnCe/ Al sample, from 70% to 94%. These values can be considered as optimal values since the NOx storage rates of this sample reach 96% (result not shown). For the reference catalyst, the increase of H2 content in the rich pulse only leads to an increase in NH3 selectivity. This study shows that PtBaMnCe/Al catalyst is very promising for NOx storage-reduction application. Most importantly, the NH3 yield is very low (nil) with this catalyst. Mn-Ce addition in NSR catalyst leads to the enhancement of the catalytic properties. It can be attributed to an improvement of the reaction between the ammonia formed in situ and the remaining stored NOx [6 ]. Click here to view Large Image 2 Impact of sulfur in gasoline on the performance of model NSR catalystIn this section, the impact of sulfur on the performance of model NSR catalyst is focused. Firstly, the NSR catalyst was sulfated before catalytic activity measurement in order to simulate the deposition of sulfur compound in gasoline onto the catalyst surface. And then, the regeneration of sulfated catalyst was studied. The sulfating treatment was performed at 300 oC with SO2 and corresponds to a 2.0 wt% S theoretical content if all the sulfur is stored on the catalyst. The regeneration of sulfated catalysts was carried out at 550 oC for 30min underrichconditions with a mixture containing 2.5% H2, 10% CO2, and 10% H2O in N2. SO2 poisoning and regenerationThe NOx conversion rate of the fresh, sulfated and after sulfur regeneration treatment of Pt20Ba/Al and Pt20BaMnCe1/ Al catalysts, measured at 400°C, are reported in Figure 1. After the sulfating treatment, the NOx storage-reduction capacities strongly decrease. For Pt20Ba/Al, a loss of 56% is observed. Mn-Ce doped sample is more resistant toward the poisoning treatment, with a loss of 41%. After the regeneration treatment, only 79% of the initial value is recovered over Pt20Ba/Al, indicating that an efficient regeneration of the NOx storage sites cannot obtain. This rate is slightly higher for Pt20BaMnCe/Al (85%) [9,10].The sulfated Pt20Ba/Al catalyst was characterized by H2- TPR (Figure 2). The sample was first in situ pretreated at 300 oC under pure oxygen. The reduction was carried out with 1% H2 from room temperature up to 800 oC. As described in [4], the TPR profile of the sulfated Pt/10Ba/Al catalyst exhibits two main peaks around 500 and 600 oC. The first one is attributed to the simultaneous reduction of aluminum sulfates and some well dispersed barium sulfates located in platinum proximity. The second peak, around 600 oC, is ascribed to the reduction of surface barium sulfates, and the observed shoulder near 750 oC corresponds to bulk barium sulfate reduction.Assuming a H2/SO42- ratio of 4 for the sulfate reduction (X-SO4+4H2-->X-S + 4H2O and/or X-SO4 + 4H2 -->X-O+H2S+3H2O), total sulfur content can be deduced from hydrogen consumption. After the sulfur regeneration, only 58% of the deposited sulfur is removed. Moreover, a stabilization of the remaining sulfates is observed. This result indicates that the sulfur poisoning is irreversible. In addition to a possible incomplete surface cleaning, the reducing treatment can induce some structural changes in the doped catalysts. Indeed, a slight deactivation of the PtBaMnCe/Al catalyst was also observed after the sulfur regeneration treatment without previous sulfating procedure. Go to Conclusion In the first part of this study, it was shown that Ce, Mn addition to PtBa/Al led to an improvement of the NOx reduction (conversion and selectivity). A near total NOx conversion to N2 can be observed at 400 oC with PtBaMnCe/Al. In the second part, the effect of sulfur in the gasoline on the catalyst performance was observed. The sulfur resistance of PtBaMnCe/Al catalyst is higher than reference PtBa/Al catalyst. Unfortunately, the NOx storage-reduction property cannot be fully recovered after the sulfur regeneration. These results clearly indicate that the lower sulfur level in fuels is indispensable for current and future emission control systems. 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Review on Gray Track Effects on Potassium Titanyl Phosphate Single Crystals Abstract Potassium titanyl phosphate (KTP) is an interesting crystal for many applications in nonlinear optics and electro-optics. Its large optical nonlinearity, damage resistance, wide acceptance angle, low insertion loss and thermally phase-matching properties make KTP crystal suitable for frequency doubling of infrared lasers. In addition, it is chemically inert and mechanically robust which are important in the construction of reliable devices suitable for industrial and medical applications. Though this crystal has enormous functional advantage, the charge defect known as gray tracking reduces its efficiency. This article aims to provide detail concept of gray tracking that mainly involves mechanism that lead to initiation of gray track, by laser and electric field. Discussed the dependency factors like wavelength, threshold, moisture, and repetition rate of laser, dopant addition, polarisation that influence the gray track to signify the effects of gray tracking in KTP and discoursed the measures to control and eliminate the gray tracking. Keywords: Second Harmonic Generation (SHG) Go to Introduction The contemporary trend in industrial and medical fields is to adopt solid state lasers with high average power, this requires technologies of higher harmonics generation with efficiency and stability, the efficiency of nonlinear crystal long-wavelength laser emissions to the visible and ultraviolet spectral ranges has led to a constant increasing use of these crystals. Among them KTP is one of the nonlinear crystal frequently opted for its excellent properties like a large nonlinear optical coefficient, wide acceptance angles, thermally stable phase-matching additionally to its attractive nonlinear optical characteristics, It is also utilized in electro-optic applications such as waveguide modulators and Puckers cells because of its large electro-optic coefficients and low dielectric constants, These high efficiency and stability is sufficient to fulfil the expectancy. However this crystal suffers from an important disadvantage, that is the formation of the colour centre called gray tracking. Gray tracking is a fatigue damage arises due to defect in crystal characterised by a coloured appearance in them which is commonly known as darkening that reduces the non-linear property of crystal through optical power losses(by absorption) that is said to be as chromic damage and so as lowering its performance in applications. Mostly flaws in crystal will decrease the efficiency of their property, here quoted some illustration to showcase effect in crystal due to this damage, Benoˆıt Boulanger [1], experiments show that gray tracking modifies the parametric gain and also many experiments proved that this damage lowers the SHG efficiency and causes astigmatism of the output laser beam and limits the overall lifetime of optical elements, So as if gray tracks once initiated, absorb a significant portion of the propagating beams causing optical power losses and continued operation often leads to catastrophic damage especially in KTP (KTiOPO4) [2,3]. The scope of this paper is concerned with propagating the overall knowledge of gray tracking including their mechanism and effects. To implicate the idea in simple terms let’s say that Ionizing radiation such as laser beam or x-rays is capable to produces electrons and holes that become separately trapped within the lattice of KTP thus forms colour centres. Thus classification is done based on two sources nothing but both the laser and electric-field which is its prime application, by inducing damage susceptibilities. Depend on the source they are named as photo chromic damage and electro chromic damage. This colouration phenomenon generally observed in KTP crystals during the second harmonic generation (SHG). Some possible mechanisms that lead to the formation of these electron-hole pairs during SHG are effects of sum-frequency generation, one-photon absorption and multi-photon absorption. However, the damage susceptibilities of the crystals also depend on the growth technique. Many different hypotheses have been presented to explain this phenomenon, which will be seen in following sessions. Mechanism Involved in Gray Tracking Formation Focus of many investigators is to recover the KTP from gray tracking to produce assured product for industrial use, To do so the core cause of gray track should be known, though various susceptibility is feasible, general believe is that defects that trap photo induced electron and holes is the primary engender, the defect mentioned is trapping sites, Optical absorption and electron paramagnetic resonance [EPR] studies can be opted to identify the trapping sites. Few investigators worked on in it namely Roelofs [4] described four distinct Ti3+ through EPR Spectral study in electrically induced or annealing in a hydrogen atmosphere in flux grown crystal, flowingly Andreev and Asimov found the same effect in X-ray irradiation at room temperature also Andreev [5] demonstrated the same using Laser beam. Likely the application themselves efficient to produce trapping sites. Elimination of these trapping sites considerably increases the gray track damage threshold. One can easily understand the mechanism with the description of X.B. Hua [6] as of the laser irradiated in KTP, some electron–hole pairs will be produced in the perfect lattice. Click here to view Large Image 1 Many of the electrons and holes will immediately recombine to restore the perfect lattice; but, a portion of the electrons and holes will migrate sufficiently far from each other and encounter a stabilizing entity, either a vacancy or an extrinsic impurity. Thus, a few of the electrons and holes will be stabilized at widely separated sites within the crystal and form the point defects (optical absorption centres) that contribute to the formation of a gray track [6]. Primal scholars [1,4,7] suggested that Ti3+ may cause optical damage but this didn’t give any direct relation to the cause of gray tracking, there after Scripsick MP et al.[8] have overcome above statement, by experimentally proving that Fe3+ traps holes and Ti3+ traps electron, Nizamutdinov et al. [9]. Experiments proved existence of EPR spectra Fe3+ in KTP for the first time following him Stenger et al. [10] and Gaite [11] distinguished four spectra of Fe3+ in flux grown KTP, latter studies suggested that Fe3+ occupy Ti(1) and Ti(2) sites depend on crystal and ENDOR(electron-nuclear double resonance) studies by Scrip sick suggested that oxygen vacancies are located adjacent to the Ti3+ centres also (Figures 1 & 2) [8] depict EPR results conformance with all these theory basis they forwarded to trapping sites identification in flux grown crystal and induced gray track through x-ray source where the effect was found at 500nm due to Fe3+ other negligible effect due to Fe2+or Fe4+also seen in (Figure 1) [8]. Click here to view Large Image 2 Click here to view Large Image 3 The gray track induction produced by x-ray source was used for investigation. The gray track didn’t last for more hours, they experienced recovery within 10hrs to the partial stage pre irradiated condition at room temperature, continuous monitoring of optical absorption at 500nm wavelength for 20hrs showed declination, A significant decay of the EPR spectra from the two Ti3+ centres and growth of the isolated Fe3+ centres is seen in (Figure 3) [8]. All these lead to the formulation concept. The optical absorption at 500 nm and the EPR signals from the Ti3+ and Fe3+ centres were monitored over a period of 20h at room temperature [8]. The chemical formulation representation given with respect to the above hypothesis on redistribution of charges is equation (1) Click here to view Large Image 4 There is an excellent correlation, as shown in (Figure 3), between the decay of the optical absorption and the decay of the two Ti3+ centres. Also, the growth of the EPR spectrum of the isolated Fe3+ centres coincides directly with the other decays. From these results, it is concluded that gray tracks are formed in KTP when isolated Fe3+ ions trap holes and Ti4+ ions (with an adjacent oxygen vacancy) trap electrons. But he nowhere addressed about the role of K+ (potassium) centres which is one of the major constituent in KTP crystal though he given chemical formation and decay formula he didn’t mention on the thermal effect and activation energy which is an important parameter while considering the combination and recombination but V. Mürk [12] model of two subsystem overcame previous statement on K+ ions and also given some acceptable reason for formation of these defects. From his experiments he conveyed the two subsystem based on natural KTP crystallographic structure one is the radiation-resistant oxide framework of TiOPO4, and the relatively mobile of the K+ captions located in the framework cavities as the energy needed for creation of a defect in the potassium sub lattice is very less say not greater than 1.4 eV, the local lattice vibration occurs when there is overheating which is much enough for non-radioactive TiO6 octahedral exactions develop a Freckle-defect pair, Ki+- V(K+) ,the micro volume containing Ki+- ion capture electron and form Ti3+ colour centres and holes outside this volume create various oxygen colour centres and thereby gray tracking emerges he also experiments on bleaching process which is of great use from the time of growth of crystal will be seen in detail in session of recovery from gray tracking later. Laser Induced Gray Track Laser is one of the prime application of KTP but this also remain a cause for gray tracking to make it simple the purpose of it’s make itself a inducer of its damage. In accordance with consideration of gray tracking as a multiphase damage there is said to be involvement of simultaneous exposure of multiple waves like, IR and visible rays. People considered gray tracking and its source cause as a mystery until mechanism of photo chromic damage as been explored, because they experienced gray track for variety of rays and situation for instance they observed gray track formation due to second harmonic generation [2,4,13,14] which is neither IR nor Visible Rays, even Blachman R proved it with UV radiation. Studying the effect caused by these sources may lead to some revelation of formation of gray track by laser i.e. in application. Gray tracking induced by a laser is classically studied on the basis of several types of experiments: Visual observation of the darkening. Observation of second-harmonic beam distortion during 1064-nm SHG [3,13]. Optical transmission coefficient measurement by the beam which creates the damage [5] or by a probe beam during laser exposure [3,13,15]. Optical transmission or absorption spectra [2,13,16- 18], Electron spin resonance (ESR) spectra [14,16] measured before and after laser irradiation. From these experimental studies, some properties of the laser-induced gray-tracking have been determined [3,13]: The gray tracking threshold (expressed as the laser peak intensity above which the damage is observed) is a decreasing exponential function of the Q-switch frequency [13] knowing the threshold will render a productive usage, limitation and maintenance of devices. This also help in knowing the concept that a laser beam with a polarization parallel to the polar axis of KTP, i.e., the binary axis creates more damage than a beam polarized orthogonally to the axis [2], [14] this information gives us a knowledge on positioning of Crystal. The time constant is dependent on the intensity of the laser beam as far the level of gray-tracking reaches the asymptotic value [14,15,17,18]. This gives the assumption about the intensity of laser and safe duration of its exposure to the crystal, thereby indicate the lifetime of crystal. So far the revelation of these properties will implicate their careful usage and limitation of device part but elucidating the mechanism of gray track will actually help in précising parameters from growth stage itself making it superefficient and increasing its lifetime in application. Laser beam radiation in KTP produces photo carriers in the volume of the beam. Then, the electrons and holes will drift apart and become trapped separately by the defects in the crystal by following the possible mechanism as mentioned before. The actual application of this crystal is to transmit secondary harmonic energy waves, today third harmonics is also being in existence effectively for use from the incidental fundamental waves, these waves are with adequate peak power intensity for respective applications this beyond certain limit (threshold) seem to cause the gray tracking, detail studies of these is as follows: Dependencies of Gray Tracking For any damage or growth process there are factors which influence them, these should be taken into consideration for successful product and for reduction of blunder, the various condition and dependent factors influencing the gray track is as follows. Wavelength and Threshold Experiments of Boulanger B [19] on KTP regarding the wavelength and intensity peak power and proved the dependency of gray tracking, He tried out with 1064nm, 532nm, 355nm where many focussing only on SHG of 532nm his team worked hardly on proving the influence of 355nm which they considered as a possible THG, went in vain because ultimately they ended up with result that neither 1064nm nor 355nm have no influence on inducing gray tracking in contrast to report of Blachman R [20] and in accordance with report of Loiacono GM [2] but their investigation on intensity peak power gave an important parameter for consideration i.e. the threshold value of intensity peak power 80MW/cm2 above which darkening of crystal start appearing. As a known fact electron excitation from the valence band to the conduction band action is responsible for any kind of reaction occurring say here as harmonic generation, there is need of energy for excitation and transmission Thus there is requirement of constant high power of laser that is also one of the inducing factor of damage that cause astigmatism of SHG efficiency and finally result in catastrophic damage so in below two subtopics dependencies of alternating solutions where discussed. Repetition Rate of Laser The alternative solution for the blame of constant high power that reduce the lifetime of crystal rapidly is providing them in pulse mode, that leads to another considerable factor repetition rate, It seem to decrease the threshold of gray tracking, previously the threshold value was mentioned as 80MW/cm2 which was under weak focussing whereas to the experimental evidence of Fève JP [21] that the gray-tracking peak power threshold strongly decreases when the repetition rate is increased: from 125MW/cm2 at 1kHz to 18MW/cm2 at 6.3kHz, and to a few MW/cm2 for frequencies greater than 10kHz. Therefore the threshold itself depends on frequency and focussing condition. These strong focussed crystal take lot time say more than a year to recover from the gray tracking. Qiuhui Zhang [22] also conducted studies on high repetition rate of laser in KTP and devised some useful model. As mentioned before once gray tracking started it continuously accumulates and ends at catastrophic damage. He devised a model on accumulation of gray tracking once it is started i.e. once colour centres formation initiated with according to the mechanism previously discussed, the bond breaks incessantly and absorption increases, the density of colour centres contribute to gray tracking centres, So there comes the relationship with variation in colour centres which is given by the number of colour centres Δn [23,24]. Click here to view Large Image 5 where D- is a constant of proportionality, F0 -the peak photon flux density of the incident, m- the order of multi-photon absorption, kB -the Boltzmann constant, T- the temperature, U0 -the initial activation energy of damage which is found to be 1-3eV for various materials, γ the material parameters, and σ =σT +σc the stress which includes thermal stress σT= Cα KFmo (C: a constant, a : the thermal expand coefficient, K: the bulk modulus of crystal) and the stress σc = Kncv (nc: the density of colour centres, v: the volume of each ion) induced by lattice expand owing to colour centres. This colour centres accounts primarily to gray tracking not the catastrophic damage, including gray tracking other factors (for e.g., thermal stress) that has been excluded from the equation may also add to the catastrophic damage. Including the above term with the nF- initial colour density (The density of absorption centre can also be estimated by Macula formula [25]), V- the volume of the focus region, is the change of colour centres after an infinite time, r is a constant describing the rate of relaxation, t is the time, It gives the density of gray tracking after each pulse as below Click here to view Large Image 6 After each irradiation there will be summation of density term with change in exponential term alone which is seen after 2nd irradiation, Click here to view Large Image 7 Similarly nth irradiation is given by, Click here to view Large Image 8 f is the repetitive rate of incident pulses, t the lasting time of irradiation. This iteration ends up i.e. the saturation of gray tracking occurs only if 0 U ≥γσ i.e. the stress induced by the expansion of colour centres is lesser than atom binding energy, this can be made as indication for the extent the crystal withstand before the entire damage, Using this one can simulate the gray tracking formation in crystal. Influence of Impurities Next alternative is adding impurities sometimes intentionally in name of do pant to enhance the property of material for instance: Ce improves the KTP transparency, trivalent metal cation are used to decrease the electrical conductivity along the c axis, Nb5+ shifts the second harmonic generation cut-off to shorter wavelengths, and also to reduce the required power and thus improving the threshold of gray tracking. C.Zaldo [26,27] one among major contributors involved in the do pant investigation, explored by incorporating different do pants like Zr, Er, Na, W, Ho, Nd, Nr, and dual composition (Wr:Rh) such different dopants of particular interest was tested UV, and x-ray irradiation but if doped samples does not meet the requirement say like inducing it by photons with energy lower than the KTP band gap [28] they also suffer from damage. He and his team experimented on both doped and undoes KTP and thermally bleached (It is a thermal treatment which involves heating the sample above the room temperature to reproduce the crystal to the state before irradiation) heating the crystal doped samples. They presented following information for us: The presence of impurities will induce two changes: Appearance of a band at about 488nm especially for high concentration of impurity Shift of Optical absorption edges which solely depend on concentration of impurities, they viewed that the shift is caused due to local lattice distribution and stress created by impurities. The growth sectors of 001 of KTP incorporate more impurities comparatively because this axis has structural channels which eases the ion exchange and impurity diffusion Damage induced in doped samples has higher thermal stability in comparison with undoped sample. They also tried the trapping efficiency of electron though they made a statement that it is very difficult because it differ for each impurity. They also devised a model for kinetic damage and erasure. With this as reference one can gain information and predict changes that could happen on addition of impurities, hence there would be some conceptual knowledge in prior and reduce the redundancies [29]. Depth The radiation damage depend on depth of impurities is tested with Li+, N+, Ar+, Er+, B+ and many, where each ion have their own effect means here the depth of affection layer with respect to the energy loss in nuclear or electron range in the complex structure of crystal consisting of covering layer, transition layer of amorphous cluster and buried amorphous layer respectively, Where comes the role of energy there comes the play of threshold, this discussion is also not a exempt to it, threshold value of the electronic energy deposition(natural energy that an ion posses in electron level) from the analysis of data seems to be 100eV/ ion/ Å. Each ion depend on their energy effectively take their place among the layered structure, Among others B+ seems to dwell deeper into the structure and Li+ was on superficial layer which again emphasis on the energy of ion [30]. Polarisation The study related to dependence of gray-track susceptibility with respect to polarization was conducted by Hua XB [6], they irradiated light in directions perpendicular and parallel to the polar axis of KTP crystals. He explains the lifetime of susceptibility incoherence with mechanism responsible for formation of gray tracking, the longer the lifetime of electrons and holes, the higher will be the crystals susceptibility to gray tracking. Though the source here is laser, involvement of electron and hole significantly affected by the electric field, as the topics were separated based on source you encounter this here. There are structural channels parallel to the polar z-axis through which the K+ ion can easily move under the influence of an electric field by a hopping mechanism, leading to a high ionic conductivity along this direction [31,32]. They focused only on role of holes to the orientation in parallel and perpendicular direction, when a light beam is propagated in a crystal, the optical frequency electric field would interact with the charges in the crystal. If the optical frequency electric field is parallel to the z-axis, the K ions will hop along the structural channel due to the high ionic electric conductivity in this direction. In this case, K vacancies do not localize at a definite position and will not serve as a stabilizing entity for the whole trap. In other words, the whole trap will become destabilized and have a short lifetime. As a result, the optical absorption centres will annihilate as soon as they are produced when the optical frequency electric field is parallel to the z-axis. In contrast, when the optical frequency electric field is perpendicular to the z-axis, the hole trap will be stabilized because the potassium vacancy can keep its position and provide a stabilizing force for the hole trap, i.e. the hole trap will have a long lifetime in this case [13]. To conclude the laser irradiation in the direction for which optical frequency, electric field will be in ||z polarization give a rare chance to gray tracking irrespective of exposure time. Control of Gray Tracking Formation in KTP Crystal Gray tracking formation before laser irradiation depend on growth technique and factors like environment, temperature, flux and impurities, To the fact ‘As stitch in time saves nine’ controlling at early stage in easy and deduce post work and also provide efficient result. Research by Perlov D [33] investigated temporal and spatial dimension of gray tracking for quantitative evaluation of KTP gray track susceptibility with respect to the factor, they reported the first experimental evidence of dependency on the material Curie temperature and electrical conductivity, and they observed the susceptibility of KTP could be significantly decreased by adjusting the growth parameters. For instance impurities included in crystal would originate the optical absorption where in case susceptibility also depend on absorption coefficient before laser irradiation this event add to the cause so that one can understand that crystal with many impurities indicated large susceptibility but exceptionally crystal with high concentration of hydroxyls had low susceptibility. This lead to the understanding the role of moisture in preventing gray tracking. Considering this concept Shinji Motokoshi [34,35] tried to improve the gray-tracking by controlling the hydroxyl concentration in KTP crystal using the thermal annealing process. It was found that large GTS (gray tracking susceptibility) in original crystal was improved by annealing in the air and that was almost returned to original value by annealing in vacuum. These results mean that the change of GTS was caused not only by an effect of the heating, but also by the transfer of molecules in the air such as oxygen and hydroxyl. However, it was previously reported that the annealing did not influence to the gray-tracking and the hydroxyl. The reason of difference with their data was due to the annealing conditions. The optimization of annealing conditions such as temperature, time, and environment had been investigated and a new approach proposed was thermal annealing pre-process. It was demonstrated that the graytracking formation and the hydroxyl concentration could be controlled by thermal annealing process before laser irradiation, the KTP crystal was decreased transmittance with the laser irradiation time before the annealing. In the case of the annealing in air, however, the decrease of transmittance was suppressed, and also the transmittance decreased again by annealing in the vacuum as mentioned before, As a result they understand that KTP crystal could include the hydroxyls in air by the annealing process. In this work, it was shown the dependence of gray-tracking susceptibility on preannealing conditions as atmosphere gases, temperature and humidity for KTP. The annealing was made with an electric oven at the temperature up to 1000 0C. The atmosphere in the oven was exchanged to air, nitrogen, oxygen, and vacuum (at 10-3 torr). The humidity in nitrogen gas was changed from 6 to 99% by control the flow rate both dry and wet gases. The annealing time in vacuum was 72 hours, and the others were 12 hours [34,35]. In comparison with no annealed sample, the samples annealed in air and N2-wet indicated decreased gray-tracking formation. The contrast occurred while annealing them in vacuum and dry gases. This cleared that gray-tracking formation could be controlled by humidity in gases but not the kind of gases. Thus one can understand the dependency and positive application of impurity well and thus efficient control is made easy. Elimination of Gray-Tracking Effects of KTiOPO4 Controlling make the KTP resistant to gray track to increase the life time of it in application, where elimination is the process done after the appearance of gray track to the extent until it meet the catastrophic damage for the purpose of reuse, Generally two methods are followed to eliminate the chromic damage which is explained in following sessions [36]. Thermal Annealing Thermal annealing is the general and simple, effective processes to retrieve the original state of crystal by eliminating the gray tracking, The temperature depend on density of gray tracking formed so the temperature differs in each crystal and approximating it prior is difficult, from our analysis of multiple data mostly KTP recovered from gray tracking was annealed about temperature above 150 °C. Strong Focussing Mechanism There was discussion on some dependencies previously there one could find the dependency and relation of radiation beam radius, focussing and power density in formation of gray tracking and among them respectively. Thus it is known that radius of beam and power density are inversely proportional, XIANG Zhen [30] proposed a system based on the above concept that eliminate the formed gray track. They thus made a setup as in below figure (Figures 4-6) where the radius of input beam is enlarged this technique resulted in decrease of power density so as decrease in conversion efficiency. Therefore it resulted in condition that one should compromise between conversion efficiency and deformation of gray tracking, when they went into detail analysis of any alternate way they found one thing in common that the increase in radius within the KTP only provided the required changes. So they adjusted the setup by adjusting the lens L2 of the focussing system thus the radius of incident beam on surface is small but in enlarges inside the crystal this provided the satisfactory result with un changed conversion efficiency and this idea of enlarging the beam only at output surface is strong focussing and both output and input is weak focussing. However effective may the strong focusing the large divergence in crystal may lead to phase mismatching, Luckily KTP has large acceptance angle that prevent this but careful choosing on focus ratio and the distance between the crystal and focussing system to be made to avoid discrepancies, else one may phase consequence like decrease in efficiency due to phase matching and appearance of gray track. Click here to view Large Image 9 Click here to view Large Image 10 Electrically Induced Gray Track Any material finally reaches the application status which involves electrical device and application of electric field, the application of an electric field leads to damage by electrolysis i.e. by electrical currents flowing through the crystal. For instance: For dc fields;0.4kV/cm along the polar axis, a grey colouration is observed and this is known as electric field induced gray tracks [31]. Furthermore, at ac fields of; 0.4 kV/cm and 1 Hz frequency, there is induced order-disorder phenomenon involving K+ ions have been observed. The schematic diagram of experimental set up electrically inducing of gray track shown [40]. The crystal structure of KTP (space group Pna21) consists of threedimensional network of TiO6 octahedral and PO4 tetrahedral [32]. There are structural channels parallel to the polar c axis through which the K+ ions can easily move under the influence of an electric field by a vacancy mechanism, (similar to one of two sub system modelled by Murk V [7] leading to a high ionic conductivity along this direction emphasized by Morris PA [33]. Gray tracks produced in KTiOPO4 (KTP) by applying a dc electric field have been studied through optical absorption, Raman scattering, and synchrotron x-ray topography. The study of the optical absorption and Raman scattering from the gray-tracked region suggests that their formation is accompanied by changes in the electronic levels of Ti4+ and also provided information on remnants strain of gray tracking [34-36]. Click here to view Large Image 11 Remnant Strain of Gray Tracking Raman spectra of KTP crystals containing gray tracks were obtained by passing the laser beam through the gray-track region. The x-ray topography of the gray-track region was recorded using the synchrotron radiation source operating at 2GeV with 250mA current. Satyanarayan MN [37] aim was to identify the localized structural changes or disorder that may occur along the grey tracks. In their observation they found gray colouration which obviously due to absorption but in region of 400-850nm to achieve their aim they should check the effects of absorption and Raman spectrum, all there reports were in comparison with the virgin and gray tracked crystal, so the resulted Raman intensity was reduced for gray tracked crystal than the virgin which is due absorption but the normalised intensity was greater for gray tracked crystal, so looked for other parameter influencing the Raman intensity. Such as that wavelength of incident radiation and the electronic energy level structure in the crystal seems to play a role, He found that for lower wavelength still lower comparative values were obtained than the previous which impose a direct relationship. If there is any structural change or disorder in the crystalline state then it gives rise to the new Raman lines and frequency shifts. The existing Raman lines might also split, if there is a localized disorder and translational symmetry is destroyed within the crystal. Here in their experimental research they didn’t find any such features, so they strongly believe and recommend that no major structural changes is happening to the crystal due to electrically induced gray track but this is not the only criteria to confirm it, further investigation with inclusion several condition is necessary to come to an conclusion. They also proposed a idea on comparing the structural damage due to both ac and dc field, where the work is not yet published, However from the so far investigation there is only revelation of electronic level changes which is relating to dc field. Nevertheless, the x-ray topography indicates that a remnant strain persists along the gray tracks [37]. Influence of water vapour in electrical damage The moisture influence was seen in recovering the gray tracking in crystal before applying it as a device, Here its influence in electro-optic device. The research work of Morris PA and Crawford MK investigation results indicate that the susceptibility of hydrothermal and flux grown KTP crystals to electric-field damage is increased when the atmosphere surrounding a device has a relatively high vapour pressure of water. Protons from the atmosphere migrate into the crystals due to the applied electric field and provide charge compensation for the Ti3+ defects responsible for damage in KTP [38]. Here they compare two growth technique one is hydrothermal and another is flux growth, among them flux grown is highly susceptible to the electric field damage. This is happening due to migration of Hydrogen from atmosphere to the crystal via cathode, some researchers also observed yellow colour induced at anode due to excess electron [38]. Morris PA [39] made significant contribution in investigating electro chromic damage of KTP by analysing many parameters like temperature, optical properties and also the possible potassium vacancy system at very early stage, among them most minute and significant is the relation of AC conductivity with the gray tracking [40-44]. The creation of damage is directly proportional to the average current which in turn proportional to the AC conductivity of crystal, the crystal’s conductivity might increases due to impurity addition. This damage leads off at cathode and migrates to anode until the entire crystal gets damaged. Go to Conclusion This article covers broad scope of gray-tracking, this even helps amateur to acquire knowledge on it because this explains the phenomenon of gray-tracking including its effects in product ,causes for formation, possible mechanism in crystal that employ gray-tracking such as laser induced ,electrically induced and defects due to its growth technique ,polarisation effects and influence of impurities and its depth and this mostly concentrate on KTP crystal which is a promising superior material for a variety of nonlinear optical and electro-optical applications. It also direct your way of search if interested in further investigation on gray tracking. For more Open Access Journals in Juniper Publishers please click on: https://juniperpublishers.com/ for more details click on the juniper publishers material science

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Motion via Art

Short Communication

Motion is one of the key topics in physics that is related to the change in position of an object with respect to time. It is typically described in terms of velocity, acceleration, displacement and time. Everything in the niverse moves. It might only be a small amount of movement and very slow, but movement does happen. Don’t forget that even if you appear to be standing still, the Earth is moving around the Sun, and the Sun is moving around our galaxy. The movement never stops. Motion is one part of what physicists call mechanics. Over the years, scientists have discovered several rules or laws that explain motion and the causes of changes in motion. It was Newton who said that the motion of objects could be fully described by only three laws that were also formulated by him in the 17th century. In the following the motion phenomenon will be described by art.

The first motion in the universe was that of light. This is mentioned in Genesis 1.3: And God said, “Let there be light, and there was light” that moved from its creation point throughout the entire space of the universe. Figure 1 entitled “The Creation Duel” demonstrates artistically the above phenomenon. Probably, the most widespread motion is related to the pupil of our eyes. Depending on the looking situation, motion of the pupils between five positions is possible as demonstrated in Figure 2. A very widespread situation is that of “no motion” as demonstrated in Figure 3 painted by Fernando Botero, a Colombian artist. In general there are five types of motion. “Linear motion” is that of moving along a straight line is demonstrated (Figure 4-6). Figure 4 is a sculpture made by the Swiss sculptor and painter Alberto Giacometti. Figure 5, demonstrating motion due to gravity, is an artwork made by Rene Magritte, Belgium Surrealist where the English photographer Eadweard J. Muybridge produced Figure 6. The picture installed at the center of the figure was painted by the Israeli artist Orly Lancet Joseph. Another kind of motion is “Reciprocating motion” that is moving backwards and forwards in a straight line as demonstrated in Figure 7. An additional kind of motion is “Rotary motion” in which there is turning round in a circle, such as a wheel turning Figure 8. This motion is demonstrated by the artwork of the Israeli artist David Gerstein. Figure 9 demonstrates “Oscillating motion” that is a swinging from side to side, like a pendulum in a clock. It was painted by Man Ray, an American artist. “Periodic or cyclic motion” that is any motion which repeats itself is demonstrated in Figure 10 painted by M.C.Escher, a Dutch graphic surrealist artist. An insight look at the artwork reveals endless stairs that are the main motif of it practically impossible. Figure 11, “Waterfall”, painted by Escher describes “Perpetual motion” characterized by a hypothetical machine that operate or produce useful work indefinitely. Here water is flowing upwards without investing any energy. And finally Figure 12 demonstrates an illusion of motion due to the continuous change in the size of the squares.

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Stabilization of Biological Samples in Inorganic Silica Matrices: An Opportunity to Significantly Enhance Infectious Disease Surveillance? Opinion Development of novel composite materials that stabilize bio-molecular components and living cells within the material matrix, without adversely altering their morphology or activity, continues to be an expanding and challenging field of research. This research is driven by the potential of imparting unique functionalities that are intrinsic to bio-molecules to the new hybrid material. These include selective catalysis of enzymes, specific recognition and binding of antibodies, storage of data by nucleic acids, high-yield production of difficult to synthesize molecules by metabolic pathways, and amplification of weak signals by many orders of magnitude by cell signaling cascades. Bio-functional materials with these properties would enable significant advances in applications from bio-catalysis, bioelectronics, controlled delivery of therapeutics, tissue engineering, medical diagnostics, advanced prosthetics, environmental and industrial process monitoring, early warning of warfare agents, to energy conversion [1]. Novel materials that stabilize bio-molecules and living cells may also meet a critical need for safe and secure preservation of virus, bacteria and emerging pathogens for disease surveillance. The recent outbreaks of Zika virus in Latin and South America, and Ebola in Western Africa, highlight the challenges associated with detecting and monitoring infectious agents in resource-limited regions. These challenges include a lack of skilled laboratory staff, the high cost of sophisticated molecular biotechnologies, poor infrastructure (including unreliable power and no cold-chain), limited access to reagents and materials, and the inability to transport samples long distances in a timely manner. Similar challenges are also experienced by far-forward military personal. Safe and secure collection and stabilization of clinical biological samples would allow for accurate identification of the biological, ensuring proper treatment is received for war fighters exposed to a potential infectious agent. Stabilization and evaluation of biological samples from a given region can also ensure that proper training and vaccinations (if available) are received for pathogens specific to the area prior to deploying forces. In the case of emerging or unknown infectious agents, stabilized clinical samples that allow for transportation from a resource limited region to a modern bio analytical laboratory, facilitating subsequent gold-standard genomic, transcriptomic, proteomic and culture assays, would prove in valuable. Development of a novel bio-molecule stabilization material would thus significantly enhance infectious disease surveillance, early detection, outbreak containment, prediction of emergence/re-emergence, and identification of new pathogenic agents. Extensive techniques have been developed for bio-molecule and living cell preservation. These generally rely on selective inactivation of sample constituents that degrade the target analyte, or the adsorption, covalent binding, or entrapment of the biological in polymeric materials. Successful strategies for DNA, RNA, protein and enzyme stabilization are widely reported; however, stabilization of living cells is significantly more challenging [2]. This is due to the more stringent requirements for the encapsulation matrix which must provide a functional bio/nano interface between the cells and the macro environment, protecting the cells from mechanical and chemical stresses, providing access to oxygen and nutrients, and allowing for the expulsion of metabolic wastes [3]. Further, methods used for stabilizing one class of bio-molecules (e.g., DNA and RNA) may be ineffective at stabilizing other classes (e.g., proteins and living cells). While methods exist for stabilizing particular classes of bio-molecules, development of a ‘universal’ bio-sample stabilization matrix that can simultaneously stabilize and preserve DNA, RNA, protein and living cells remains a significant challenge. Silica materials derived from the sol-gel processes may prove a means to meet this challenge. Advantages of silica for bio-entrapment include the ability of sol-gel based systems to retain water with negligible swelling or shrinkage, chemical and biological inertness, mechanical stability, controlled porosity, resistance to microbial attack, room temperature processing, optical transparency, and the ability to tailor the matrix to provide desired material and chemical properties [4]. Additionally, silica is an archetypical cell-protectant in nature. Diatoms, radiolarians, and sponges have evolved to fix silica onto their cell surfaces, forming exoskeletons that can provide mechanical protection without adversely affecting nutrient and waste exchange [5]. Inorganic silica-based materials have been used to encapsulate and stabilize a wide range of biological materials. Encapsulation of proteins and enzymes in silica sol-gel matrices, with improved stability and comparable activity to enzyme in solution, has been reported. The use of sol-gel films for DNA stabilization, including use for microarray applications and aptamer-based bio-detection, has also been reported [6]. We recently reported the extraction of RNA from cells stabilized in a silica thin film [7]. RNA was intact with little to no degradation and was used for quantitative RNA expression profiling via gene chip analysis to study cellular response under differing environmental conditions and stressors. Attempts to preserve living cells in inorganic silica materials began in the early 1990s with the pioneering work of Carturan, who encapsulated Saccharomyces cerevisiae in a tetra ethylortho silicate (TEOS) derived silica thin film [8]. Barriers encountered during sol-gel processing resulted in cytotoxicity and low viability. However, sol-gel processing issues can be addressed by reducing the contact time between cells and the sol-gel precursor solution, incorporating ameliorants (e.g., gelatin, polyvinyl alcohol, glycerol) into the silica gel, developing silicates with non-cytotoxic hydrolysis and condensation byproducts (e.g., poly (glyceryl) silicate), utilizing all aqueous precursors (e.g. colloidal silica), depositing silica thin films over cells via exposure to gas phase silica alkoxides, or stabilization of supra molecular assemblies and biological materials in silica thin films by chemical vapor deposition. By exploiting these advances, silica matrices effective at entrapping living cell have been reported [9]. Further, we recently showed that it is possible to remove and recover living cells encapsulated within silica monoliths, with subsequent replication and growth in liquid culture and on solid growth medium [10,11]. Despite these many successes, significant obstacles remain in developing a material capable a universally stabilizing all components of any biological sample. Stabilization and preservation of mixed, complex biological samples (i.e., blood, saliva, tissue, field samples) in silica matrices has yet to be reported. Further, extraction of a biological sample from a silica matrix such that the preserved sample is of high quality and compatible with gold-standard genomic, transcriptomic, proteomic, and culture assays remains a significant challenge. Finally, it is desirable that such chemistry be low cost, simple to use, and have a long shelf-life without refrigeration, facilitating use in low resource settings. Overcoming these obstacles may be possible employing a composite silica matrix. If successful, this novel material may revolutionize infectious disease surveillance, early detection of pathogenic agents, predicting re-emergence, outbreak containment, and identification of new or unknown infectious agents. Go to Acknowledgement Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, L.L.C., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DENA- 0003525. For more Open Access Journals in Juniper Publishers please click on: https://juniperpublishers.com/ for more details click on the juniper publishers material science

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Comparison of the Acute Erythropoietic Capacities of Erythropoietin and U-74389G Concerning Red Blood Cells Counts Abstract Aim: This study compared the erythropoietic capacities of erythropoietin (Epo) and antioxidant drug U-74389G based on 2 preliminary studies. The provided results at red blood cells counts augmentation were co-evaluated in a hypoxia reoxygenation protocol of an animal model. Materials and methods: Red blood cells (RBC) counts were evaluated at the 60th reoxygenation min (for groups A, C and E) and at the 120th reoxygenation min (for groups B, D and F) in 60 rats. Groups A and B received no drugs, rats from groups C and D were administered with Epo; whereas rats from groups E and F were administered with U-74389G. Results: The first preliminary study of Epo non significantly increased the RBC counts by 0.80%±0.01% (p-value=0.6446). The second preliminary study of U-74389G also non significantly rised the RBC counts by 1.05%±1.57% (P=0.4911). These 2 studies were co-evaluated since they came from the same experimental setting. The outcome of the co-evaluation was that U-74389G has 1.309673-fold erythropoietic potency than Epo (p-value=0.0000). Conclusion: The anti-oxidant capacities of U-74389G speed up the acute erythropoietic properties; presenting 1.309673-fold erythropoietic rise than epo (p-value=0.0000). Keywords: Hypoxia; Erythropoietin; U-74389G; Red blood cells counts; Reoxygenation Go to Introduction The acute erythropoietic capacity of U-74389G is also non significant (p-value=0.4911) [1]. U-74389G is a novel antioxidant factor. It implicates just only 255 known biomedical studies at present. 4.31% of these studies concern tissue hypoxia and reoxygenation (HR) experiments. The promising effect of U-74389G in tissue protection has been noted in these HR studies. U-74389G or also known as 21-[4-(2,6-di-1-pyrrolidinyl-4-pyrimidinyl)-1-piperazinyl]-pregna-1,4,9(11)-triene-3,20-dione maleate salt is an antioxidant which prevents both arachidonic acid-induced and iron-dependent lipid peroxidation. It protects against HR injury in animal heart, liver and kidney models. These membrane-associating antioxidants are particularly effective in preventing permeability changes in brain microvascular endothelial cells monolayers. Lazaroids, a novel series of glucocorticoid compounds 21-aminosteroids have the properties of free radical scavenging. U-74389G is one of the 132 similar lazaroid compounds. It has a molecular weight of 726.90406 g/mol; it has a selective action on vascular endothelium with vitamin E-like properties. However, the erythropoietic capacity of U-74389G gets more comprehensible whether is compared with the same capacity of a standard known drug. Such one of the most well studied drug; actually with original erythropoietic capacity (p-value=0.6446) is erythropoietin (Epo). Indeed, Epo implicates over 29,675 known biomedical studies at present. 10.47% at least of these studies concern tissue hypoxia and reoxygenation (HR)experiments. Certainly, the concept has been moved away from the original action of Epo in stem blood cells recovery. However, just few related reports were found, not covering completely the specific matter with antioxidant factors. The special aim of this experimental work was to compare the acute erythropoietic capacities of U-74389G and Epo on a rat model and mainly in an HR protocol. Their effects were tested by measuring the red blood cells (RBC) counts. Go to Materials and Methods Animal preparation The Vet licenses of the research were provided under 3693/12-11- 2010 & 14/10-1-2012 decisions. The granting company and the place of experiment are mentioned in related references [1,2]. Appropriate humanistic care was adopted for Albino female Wistar rats. 7 days pre-experimental normal housing included ad libitum diet in laboratory. Continuous intra-experimental general anesthesia, oxygen supply, electrocardiogram, acidometry and post-experimental euthanasia were provided. Rats 16–18 weeks old were randomly delivered to six (6) groups (n=10), using the following protocols of HR: Hypoxia for 45 min followed by reoxygenation for 60min (group A); hypoxia for 45min followed by reoxygenation for 120 min (group B); hypoxia for 45min followed by immediate Epo intravenous (IV) administration and reoxygenation for 60 min (group C); hypoxia for 45min followed by immediate Epo IV administration and reoxygenation for 120min (group D); hypoxia for 45min followed by immediate U-74389G intravenous (IV) administration and reoxygenation for 60 min (group E); hypoxia for 45min followed by immediate U-74389G IV administration and reoxygenation for 120min (group F). The dose height selection criteria of Epo and U-74389G were assessed at preliminary studies as 10mg/Kg body mass of animals for both drugs. Hypoxia was caused by laparotomic clamping inferior aorta over renal arteries with forceps for 45min. The clamp removal was restoring the inferior aorta patency and reoxygenation. After exclusion of the blood flow, the protocol of HR was applied, as described above for each experimental group. The drugs were administered at the time of reperfusion; through inferior vena cava catheter. The RBC counts were determined at 60thmin of reoxygenation (for A, C and E groups) and at 120thmin of reoxygenation (for B, D and F groups).The animals’ mass was not a confusing factor for RBC counts (p-value=0.5048). Statistical analysis Table 1 presents the (%) augmentation influence of Epo regarding reoxygenation time. Also, Table 2 presents the (%) augmentation influence of U-74389G regarding reoxygenation time. Chi-square tests were applied using the ratios which produced the (%) results per endpoint. The outcomes of chisquare tests are depicted at Table 3. The statistical analysis was performed by Stata 6.0 software [Stata 6.0, StataCorp LP, Texas, USA]. Click here to view Large Table 1 Click here to view Large Table 2 Click here to view Large Table 3 Go to Results The successive application of chi-square tests revealed that U-74389G favored erythropoiesis by 0.9610586-fold (0.958379- 0.9637456) than Epo at 1h, by 1.733395-fold (1.724921- 1.74191) at 1.5h, by 6.5196571-fold (6.4712605-6.568412) at 2h, by 1.039524-fold (1.037862-1.04119) without drugs and by 1.309673-fold (1.305082-1.314281) whether all variables have been considered (p-value=0.0000). Go to Discussion The unique available study investigating the rising effect of U-74389G on RBC counts was the preliminary one [1]. Although the most famous activities of neuroprotection and membranestabilization properties, it accumulates in the cell membrane, protecting vascular endothelium from peroxidative damage but hardly penetrates the blood-brain barrier. It elicits a beneficial effect in ototoxicity and Duchenne muscular dystrophy. It increases γGT, SOD, and GSH levels in oxygen-exposed cells. It treats septic states and acts as immunosuppressant in flap survival. It prevents the learning impairments, it delays the early synaptic transmission decay during hypoxia improving energetic state of neurons. It shows anti proliferative properties on brain cancer cells and is considered as a new promising anti inflammatory drug for the treatment of reperfusion syndrome in IR injuries.The same authors generally confirmed [2] the short-term or long-term erythropoietic effect of various Epo preparations in 9 IR laboratory or clinical biomedical studies on human individuals or animals tried to stimulate erythropoiesis as the speedy replacement of blood loss with endogenous red blood cells [3]. Denny ended [4] up that the hypoxia-inducible transcription factor (HIF) stimulates the production of Epo and ultimately RBC count. [5] Controlled the development of RBC count from committed progenitors, with the Epo-receptor (Epo-R) signaling network being the primary controlling molecular hub. Soliz. agreed that [6] Epo as a cytokine able to increase the production of RBC count upon conditions of reduced oxygen availability [7] to Epo-mediated elevation of RBC count through increased minute ventilation and tissue oxygenation. Guo [8] associated a greater increase in reticulocyte count with hepatic hepcidin mRNA expression down-regulation, with renal Epo mRNA expression up-regulation, increased Epo levels and erythrocytosis. [9] exemplified Epo as a plasma protein that can initiate the feedback production of new RBC. [10] demonstrated that stabilization of hypoxia inducible factor (HIF) can up-regulate Epo expression and in turn increase count of RBCs potentially exemplified the demethylation of the Epo enhancer region [11] as key regulator in the production of RBCs. [12] related the increase in plasma Epo with the nucleated RBCs (NRBC); but not with the ‘emergence time, the NRBC first appeared in the blood between 24 and 36h after any dose in neonates. [13] described human Epo as a 30.4k Da glycoprotein hormone composed of a single 165 amino acid residues chain to which four glycans are attached; being an essential factor for the viability and proliferation of erythrocytic progenitors. Jelkmann [14] calculated a delayed way, this is, a lag of 3-4 days for erythropoiesis-stimulating agents (ESAs) to act in inducing an increase in reticulocytes [15]. Significantly decreased erythropoiesis in Ret % by 41.66%, 7-10 day after HT which eliminated the major gene regulating Epo/ synthesis; the hypoxia- induced factor (HIF) expression [16] considered Epo as a key mediator in increasing the RBC count during hypoxia [17]. Revealed that decreased expression levels of hypoxia inducible factor 1 and its down-stream target genes Epo is responsible for the generation of senescent erythrocytes and RBC in chronodisrupted animals [18]. Indicated the activation of erythropoiesis during the first 7 days of hypoxia which induces an increase in peripheral RBC (polycythemia) caused by an increased Epo production. Kaliev [19]. Increased the RBC concentration indices in patients receiving Epo. [20] found that acute hypoxia stimulates large increases in serum Epo which induces formation of characteristic enlarged RBCs with maximum elevations 1month after onset [21] observed 1,000 fold increase in Epo mRNA and 2-3-fold increase in the reticulocytes at orally administered 30mg/kg of a small molecule inhibitor (PHI-1) of prolyl-hydroxylase-2 (PHD2) enzyme involved in regulating HIF- 1α levels in male BALB/c mice [22]. Up-regulated the hypoxic marker genes hypoxia inducible factor 1α, myoglobin 1, and Epo 2 significantly increasing the production of immature RBC in fish [23] led to increased Epo expression which activates production of RBC after hypoxia-inducible transcription factors stabilization. [24] caused hypoxia which increased Epo expression higher than 70% being responsible for regulating the RBC growth and development in C2C12 myoblasts, myotubes, and primary myoblasts in vitro than unexercised controls [25]. Found a dose-dependent increase in RBC count in rHuEPO200, rHuEPO400 and rHuEPO600 therapy groups whereas increase in reticulocyte count only in rHuEPO400 and rHuEPO600 therapy groups in male Wistar rats [26]. induced slowed maturation of RBC in the bone marrow inhibiting hepsidin production, after Epo release and erythropoiesis activation. [27] Repeated that the glycoprotein Epo promotes the production of RBCs. Urrutia AA [28]. determined that brain pericytes represent an up to 70% cellular source of Epo in the hypoxic brain of all Epo-expressing cells and thus an increased RBC production due to HIF-mediated induction of Epo in mice with genetic HIF activation [29]. Significantly correlated the Epo cord blood and NRBC with maternal BMI [30]. Accentuated the well-known role of Epo in RBC production. Haddad [31]. Examined the effect of intraperitoneal injections of 40 mg/kg of the lazaroid compound U-74389G every 12 hours, on acute otitis media in guinea pigs. Streptococcus pneumoniae organisms were inoculated into the right tympanic cavity; with the left ear served as a control [32]. According to above, Table 3 shows that U-74389G speeds up by 1.309673-fold (1.305082-1.314281) the erythropoietic potency than Epo (p-value=0.0000); a trend augmented along time, in Epo non-deficient rats. A meta-analysis of these ratios from the same experiment, for 2 other hematologic variables, provides comparable results (Table 4 & 5). Click here to view Large Table 4 Click here to view Large Table 5 Go to Conclusion The anti-oxidant capacities of U-74389G speed up by 1.309673-fold (1.305082-1.314281) the erythropoietic potency than Epo (p-value=0.0000) in Epo non-deficient rats (p-value=0.0000). This trend is enhanced along the short term time frame of the experiment. For more Open Access Journals in Juniper Publishers please click on: https://juniperpublishers.com/ for more details click on the juniper publishers material science

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Comparison of the Acute Erythropoietic Capacities of Erythropoietin and U-74389G Concerning Red Blood Cells Counts Abstract Aim: This study compared the erythropoietic capacities of erythropoietin (Epo) and antioxidant drug U-74389G based on 2 preliminary studies. The provided results at red blood cells counts augmentation were co-evaluated in a hypoxia reoxygenation protocol of an animal model. Materials and methods: Red blood cells (RBC) counts were evaluated at the 60th reoxygenation min (for groups A, C and E) and at the 120th reoxygenation min (for groups B, D and F) in 60 rats. Groups A and B received no drugs, rats from groups C and D were administered with Epo; whereas rats from groups E and F were administered with U-74389G. Results: The first preliminary study of Epo non significantly increased the RBC counts by 0.80%±0.01% (p-value=0.6446). The second preliminary study of U-74389G also non significantly rised the RBC counts by 1.05%±1.57% (P=0.4911). These 2 studies were co-evaluated since they came from the same experimental setting. The outcome of the co-evaluation was that U-74389G has 1.309673-fold erythropoietic potency than Epo (p-value=0.0000). Conclusion: The anti-oxidant capacities of U-74389G speed up the acute erythropoietic properties; presenting 1.309673-fold erythropoietic rise than epo (p-value=0.0000). Keywords: Hypoxia; Erythropoietin; U-74389G; Red blood cells counts; Reoxygenation Go to Introduction The acute erythropoietic capacity of U-74389G is also non significant (p-value=0.4911) [1]. U-74389G is a novel antioxidant factor. It implicates just only 255 known biomedical studies at present. 4.31% of these studies concern tissue hypoxia and reoxygenation (HR) experiments. The promising effect of U-74389G in tissue protection has been noted in these HR studies. U-74389G or also known as 21-[4-(2,6-di-1-pyrrolidinyl-4-pyrimidinyl)-1-piperazinyl]-pregna-1,4,9(11)-triene-3,20-dione maleate salt is an antioxidant which prevents both arachidonic acid-induced and iron-dependent lipid peroxidation. It protects against HR injury in animal heart, liver and kidney models. These membrane-associating antioxidants are particularly effective in preventing permeability changes in brain microvascular endothelial cells monolayers. Lazaroids, a novel series of glucocorticoid compounds 21-aminosteroids have the properties of free radical scavenging. U-74389G is one of the 132 similar lazaroid compounds. It has a molecular weight of 726.90406 g/mol; it has a selective action on vascular endothelium with vitamin E-like properties. However, the erythropoietic capacity of U-74389G gets more comprehensible whether is compared with the same capacity of a standard known drug. Such one of the most well studied drug; actually with original erythropoietic capacity (p-value=0.6446) is erythropoietin (Epo). Indeed, Epo implicates over 29,675 known biomedical studies at present. 10.47% at least of these studies concern tissue hypoxia and reoxygenation (HR)experiments. Certainly, the concept has been moved away from the original action of Epo in stem blood cells recovery. However, just few related reports were found, not covering completely the specific matter with antioxidant factors. The special aim of this experimental work was to compare the acute erythropoietic capacities of U-74389G and Epo on a rat model and mainly in an HR protocol. Their effects were tested by measuring the red blood cells (RBC) counts. Go to Materials and Methods Animal preparation The Vet licenses of the research were provided under 3693/12-11- 2010 & 14/10-1-2012 decisions. The granting company and the place of experiment are mentioned in related references [1,2]. Appropriate humanistic care was adopted for Albino female Wistar rats. 7 days pre-experimental normal housing included ad libitum diet in laboratory. Continuous intra-experimental general anesthesia, oxygen supply, electrocardiogram, acidometry and post-experimental euthanasia were provided. Rats 16–18 weeks old were randomly delivered to six (6) groups (n=10), using the following protocols of HR: Hypoxia for 45 min followed by reoxygenation for 60min (group A); hypoxia for 45min followed by reoxygenation for 120 min (group B); hypoxia for 45min followed by immediate Epo intravenous (IV) administration and reoxygenation for 60 min (group C); hypoxia for 45min followed by immediate Epo IV administration and reoxygenation for 120min (group D); hypoxia for 45min followed by immediate U-74389G intravenous (IV) administration and reoxygenation for 60 min (group E); hypoxia for 45min followed by immediate U-74389G IV administration and reoxygenation for 120min (group F). The dose height selection criteria of Epo and U-74389G were assessed at preliminary studies as 10mg/Kg body mass of animals for both drugs. Hypoxia was caused by laparotomic clamping inferior aorta over renal arteries with forceps for 45min. The clamp removal was restoring the inferior aorta patency and reoxygenation. After exclusion of the blood flow, the protocol of HR was applied, as described above for each experimental group. The drugs were administered at the time of reperfusion; through inferior vena cava catheter. The RBC counts were determined at 60thmin of reoxygenation (for A, C and E groups) and at 120thmin of reoxygenation (for B, D and F groups).The animals’ mass was not a confusing factor for RBC counts (p-value=0.5048). Statistical analysis Table 1 presents the (%) augmentation influence of Epo regarding reoxygenation time. Also, Table 2 presents the (%) augmentation influence of U-74389G regarding reoxygenation time. Chi-square tests were applied using the ratios which produced the (%) results per endpoint. The outcomes of chisquare tests are depicted at Table 3. The statistical analysis was performed by Stata 6.0 software [Stata 6.0, StataCorp LP, Texas, USA]. Click here to view Large Table 1 Click here to view Large Table 2 Click here to view Large Table 3 Go to Results The successive application of chi-square tests revealed that U-74389G favored erythropoiesis by 0.9610586-fold (0.958379- 0.9637456) than Epo at 1h, by 1.733395-fold (1.724921- 1.74191) at 1.5h, by 6.5196571-fold (6.4712605-6.568412) at 2h, by 1.039524-fold (1.037862-1.04119) without drugs and by 1.309673-fold (1.305082-1.314281) whether all variables have been considered (p-value=0.0000). Go to Discussion The unique available study investigating the rising effect of U-74389G on RBC counts was the preliminary one [1]. Although the most famous activities of neuroprotection and membranestabilization properties, it accumulates in the cell membrane, protecting vascular endothelium from peroxidative damage but hardly penetrates the blood-brain barrier. It elicits a beneficial effect in ototoxicity and Duchenne muscular dystrophy. It increases γGT, SOD, and GSH levels in oxygen-exposed cells. It treats septic states and acts as immunosuppressant in flap survival. It prevents the learning impairments, it delays the early synaptic transmission decay during hypoxia improving energetic state of neurons. It shows anti proliferative properties on brain cancer cells and is considered as a new promising anti inflammatory drug for the treatment of reperfusion syndrome in IR injuries. The same authors generally confirmed [2] the short-term or long-term erythropoietic effect of various Epo preparations in 9 IR laboratory or clinical biomedical studies on human individuals or animals tried to stimulate erythropoiesis as the speedy replacement of blood loss with endogenous red blood cells [3]. Denny ended [4] up that the hypoxia-inducible transcription factor (HIF) stimulates the production of Epo and ultimately RBC count. [5] Controlled the development of RBC count from committed progenitors, with the Epo-receptor (Epo-R) signaling network being the primary controlling molecular hub. Soliz. agreed that [6] Epo as a cytokine able to increase the production of RBC count upon conditions of reduced oxygen availability [7] to Epo-mediated elevation of RBC count through increased minute ventilation and tissue oxygenation. Guo [8] associated a greater increase in reticulocyte count with hepatic hepcidin mRNA expression down-regulation, with renal Epo mRNA expression up-regulation, increased Epo levels and erythrocytosis. [9] exemplified Epo as a plasma protein that can initiate the feedback production of new RBC. [10] demonstrated that stabilization of hypoxia inducible factor (HIF) can up-regulate Epo expression and in turn increase count of RBCs potentially exemplified the demethylation of the Epo enhancer region [11] as key regulator in the production of RBCs. [12] related the increase in plasma Epo with the nucleated RBCs (NRBC); but not with the ‘emergence time, the NRBC first appeared in the blood between 24 and 36h after any dose in neonates. [13] described human Epo as a 30.4k Da glycoprotein hormone composed of a single 165 amino acid residues chain to which four glycans are attached; being an essential factor for the viability and proliferation of erythrocytic progenitors. Jelkmann [14] calculated a delayed way, this is, a lag of 3-4 days for erythropoiesis-stimulating agents (ESAs) to act in inducing an increase in reticulocytes [15]. Significantly decreased erythropoiesis in Ret % by 41.66%, 7-10 day after HT which eliminated the major gene regulating Epo/ synthesis; the hypoxia- induced factor (HIF) expression [16] considered Epo as a key mediator in increasing the RBC count during hypoxia [17]. Revealed that decreased expression levels of hypoxia inducible factor 1 and its down-stream target genes Epo is responsible for the generation of senescent erythrocytes and RBC in chronodisrupted animals [18]. Indicated the activation of erythropoiesis during the first 7 days of hypoxia which induces an increase in peripheral RBC (polycythemia) caused by an increased Epo production. Kaliev [19]. Increased the RBC concentration indices in patients receiving Epo. [20] found that acute hypoxia stimulates large increases in serum Epo which induces formation of characteristic enlarged RBCs with maximum elevations 1month after onset [21] observed 1,000 fold increase in Epo mRNA and 2-3-fold increase in the reticulocytes at orally administered 30mg/kg of a small molecule inhibitor (PHI-1) of prolyl-hydroxylase-2 (PHD2) enzyme involved in regulating HIF- 1α levels in male BALB/c mice [22]. Up-regulated the hypoxic marker genes hypoxia inducible factor 1α, myoglobin 1, and Epo 2 significantly increasing the production of immature RBC in fish [23] led to increased Epo expression which activates production of RBC after hypoxia-inducible transcription factors stabilization. [24] caused hypoxia which increased Epo expression higher than 70% being responsible for regulating the RBC growth and development in C2C12 myoblasts, myotubes, and primary myoblasts in vitro than unexercised controls [25]. Found a dose-dependent increase in RBC count in rHuEPO200, rHuEPO400 and rHuEPO600 therapy groups whereas increase in reticulocyte count only in rHuEPO400 and rHuEPO600 therapy groups in male Wistar rats [26]. induced slowed maturation of RBC in the bone marrow inhibiting hepsidin production, after Epo release and erythropoiesis activation. [27] Repeated that the glycoprotein Epo promotes the production of RBCs. Urrutia AA [28]. determined that brain pericytes represent an up to 70% cellular source of Epo in the hypoxic brain of all Epo-expressing cells and thus an increased RBC production due to HIF-mediated induction of Epo in mice with genetic HIF activation [29]. Significantly correlated the Epo cord blood and NRBC with maternal BMI [30]. Accentuated the well-known role of Epo in RBC production. Haddad [31]. Examined the effect of intraperitoneal injections of 40 mg/kg of the lazaroid compound U-74389G every 12 hours, on acute otitis media in guinea pigs. Streptococcus pneumoniae organisms were inoculated into the right tympanic cavity; with the left ear served as a control [32]. According to above, Table 3 shows that U-74389G speeds up by 1.309673-fold (1.305082-1.314281) the erythropoietic potency than Epo (p-value=0.0000); a trend augmented along time, in Epo non-deficient rats. A meta-analysis of these ratios from the same experiment, for 2 other hematologic variables, provides comparable results (Table 4 & 5). Click here to view Large Table 4 Click here to view Large Table 5 Go to Conclusion The anti-oxidant capacities of U-74389G speed up by 1.309673-fold (1.305082-1.314281) the erythropoietic potency than Epo (p-value=0.0000) in Epo non-deficient rats (p-value=0.0000). This trend is enhanced along the short term time frame of the experiment. For more Open Access Journals in Juniper Publishers please click on: https://juniperpublishers.com/ for more details click on the juniper publishers material science

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A Combined Experimental and Theoretical Study on Vibrational Spectra of 2-Phenylcyclopropan-1-Amine Abstract In this work, a combined experimental and theoretical study on molecular structure, vibrational spectra and natural bond orbital (NBO) analysis of 2-phenylcyclopropan-1-amine (2PCP1A) have been reported. The optimized molecular structure, atomic charges, vibrational frequencies and natural bond orbital analysis of 2PCP1A have been studied by performing DFT/B3LYP/6-31G(d,p),6-311++G(2d,3p)and 6-31G(3df,3pd) levels of theory. The FT-IR, FT-Raman spectra were recorded in the region of 4000–400cm1 and 3500-100cm1 respectively. The harmonic vibrational frequencies were scaled and compared with experimental values. The observed and the calculated frequencies are found to be in good agreement. The UV–visible spectrum was also recorded and compared with the theoretical values. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Natural Population Analysis (NPA) was used for charge determination in the title molecule. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were investigated using theoretical calculations. Keywords: FTIR; FT-Raman; DFT; MEP; NBO; NLO Introduction 2-phenylcyclopropan-1-amine (2PCP1A) compound belongs to the class of organic compounds known as aralkylamines. These are alkylamines in which the alkyl group is substituted at one carbon atom by an aromatic hydrocarbyl group. This monoamine oxidase inhibitor is effective in the treatment of major depression, dysthymic disorder, and atypical depression. It also is useful in panic and phobic disorders. Phenycycloproane and its derivatives are studied by several authors. Influence of Reactant Polarity on the course of (4+2) Cycloadditions was investigated by Sustmann [1]. Density Functional Theory Study of the Cycloaddition Reaction of Furan Derivatives with Masked o-Benzoquinones is carried out by Domingo [2]. Resonance Raman studies of phenylcyclopropane radical cations are studied by Godbout [3]. Weak hydrogen bridges: a systematic theoretical study on the nature and strength of C--H...F--C interactions is done by Kryspin [4]. Lysine demethylase inhibitors for myeloproliferative or lymphoproliferative diseases or disorders are studied by Mathewet [5]. In the present work, harmonic-vibrational frequencies are calculated for 2-phenylcyclopropan-1-amine (2PCP1A) using B3LYP/6-31G(d,p), 6-311++G(2d,3p) and 6-31G(3df,3pd) methods. The calculated spectra of the compound are compared to that of experimentally observed FT-IR and FT-Raman spectra. The redistribution of electron density (ED) in various bonding and antibonding orbitals and E(2) energies have been calculated by natural bond orbital (NBO) analysis by DFT method to give clear evidence of stabilization originating from the hyper conjugation of various intramolecular interactions. The HOMO and LUMO analysis have been used to elucidate information regarding ionization potential (IP), electron affinity (EA), electronegativity (), electrophilicity index (), hardness () and chemical potential () are all correlated. These are all confirming the charge transfer within the molecule and also molecular electrostatic potential (MESP) shows the various electrophilic and nucleophilic region of the title molecule. Experimental The compound under investigation 2PCP1Awas purchased from Aldrich chemicals, USA. The FT-IR spectrum of 2PCP1A was recorded in the region 400-4000 cm1 on IFS 66 V spectrophotometer using KBr pellet technique as shown inFigure 1(b). The FT-Raman spectrum of 2PCP1A has been recorded using 1064 nm line of Nd: YAG laser as excitation wavelength in the region 3500-100cm1on a Thermo Electron Corporation model Nexus 670 spectrophotometer equipped with FT-Raman module accessory as shown in Figure 2(a). The ultraviolet absorption spectra of 2PCP1A were examined in the range 200–400 nm using SHIMADZU UV-1650 PC, UV–VIS recording spectrometer using water as solvent. Computational Details DFT method is very much useful for the Quantum mechanical calculations of energies, geometries and vibrational wave numbers of organic chemical system. The gradient corrected density functional theory (DFT) [6] with the three-parameter hybrid functional Becke3 (B3) [7,8] for the exchange part and the Lee-Yang-Parr (LYP) correlation functional [9], calculations have been carried out in the present investigation, using 6-31G(d.p), 6-311++G(2d,3p) and 6-31G(3df,3pd) basis sets with Gaussian-03 [10] program, invoking gradient geometry optimization [11]. All the parameters were allowed to relax and all the calculations converged to an optimized geometry which corresponds to true energy minima. The optimized structural parameters of 2PCP1A were used for harmonic vibrational frequency calculations resulting in IR and Raman frequencies. The vibrational assignments of the normal modes were made on the basis of the potential energy distribution (PED) calculated by using the VEDA 4 program [12]. Results and Discussion Molecular geometry The first task for the computational work is to determine the optimized geometries of the title compound. The optimized molecular structure of 2PCP1A with the numbering scheme of the atoms is shown in Figure 1(a). The optimized structural parameters such as bond length and bond angles are determined by B3LYP method with 6-31G(d,p),6-311++G(2d,3p) and 6-31G(3df,3pd) as basis sets. The geometry of the molecule is considered by possessing C1 point group symmetry. From the structural data given in Table 1, it is observed that the various benzene ring CC bond distances and the CH bond lengths of title compound are found to be almost the same at all levels of calculations. [Click here to view Large Figure 1] [Click here to view Large Table 1] Vibrational Assignments The molecule 2PCP1A belongs to C1 point group symmetry, and its 57 fundamentals are distributed amongst the symmetry species as, all these modes are found to be active both in the Raman scattering and infrared absorption. The detailed vibrational assignment of fundamental modes of 2PCP1A along with the calculated IR and Raman frequencies and normal mode descriptions (characterized by PED) are reported in Table 2. For visual comparison, the observed and calculated FT-IR and FT-Raman spectra of 2PCP1A at DFT–B3LYP method using 6-31G(d,p), 6-311++G(2d,3p) and 6-31G(3df,3pd) basis sets are shown in Figures 1(b) and 2(a) respectively. The main focus of the present investigation is the proper assignment of the experimental frequencies to the various vibrational modes of 2PCP1A in corroboration with the calculated harmonic vibrational frequencies at B3LYP level using the standard 6-31G(d,p),6-311++G(2d,3p) and 6-31G(3df,3pd) basis sets. Comparison of the frequencies calculated by DFT-B3LYP method with the experimental values reveals the overestimation of the calculated vibrational modes due to neglect of an harmonicity in real system. CH vibrations The aromatic structure shows the presence of CH stretching vibration in the region 3200–3000cm1 which is the characteristic region for the identification of CH stretching vibration [13]. In this region, the bands are not affected appreciably by the nature of the constituents. For our title molecule the bands corresponding to CH stretching vibrations at 3204,3185 and 3172cm1 by DFT methods show excellent agreement with the literature data and also with the band observed in the recorded FT-IR spectrum at 3172cm1 [14,15]. The PED corresponding to this vibration is pure mode of contributing more than 90% as shown in Table 2. Ring Vibrations. Many ring modes are affected by the substitutions in the ring of midodrine. The actual position of these modes are determined not so much by the natural of the substituents but by the form of substitution around the ring system [16]. In our present study the wave number computed 1663, 1662 and 1660cm1 by B3LYP methods are assigned to CC stretching vibrations for the title molecule shows good agreement with recorded spectra. The in-plane and out-of-plane bending vibration are computed by DFT/6-31G(d,p), 6-311++G(2d,3p) and 6-31G(3df,3pd) methods show good agreement with literature [18,19] and recorded spectral data. [Click here to view Large Table 2] [Click here to view Large Figure 2] NH2 Vibrations Primary aliphatic amides absorb in the region 3520-3320cm- 1 [17]. The position of absorption in this region depends upon the degree of hydrogen bonding and the physical state of the sample or the polarity of the solvent. The NH2 asymmetric and symmetric stretching modes are 3568, 3564cm-1 and 3488, 3484cm-1 by B3LYP basis sets, while the experimental values are 3568 and 3566cm-1 in FT-IR and FT-Raman spectrum respectively. They are presented in Table 2. The PED contributions are 100% for stretching mode. NBO Analysis Natural bond analysis gives the accurate possible natural Lewis structure picture of because all orbitals are mathematically chosen to include the highest possible percentage of the electron density. Interaction between both filled and virtual orbital spaces information correctly explained by the NBO analysis could enhance the analysis of intra- and intermolecular interactions. The second order Fock matrix was carried out to evaluate donor (i) and acceptor (j) i.e. donor level bonds to acceptor level bonds interaction in the NBO analysis [18]. The result of interaction is a loss of occupancy from the concentrations of electron NBO of the idealized Lewis structure into an empty non-Lewis orbital. For each donor(i) and acceptor(j), the stabilization energy E(2) associated with the delocalization ij is estimated a where qi is the donor orbital occupancy, εi and εj are diagonal elements and F (i, j) is the off diagonal NBO Fock matrix element. Natural bond orbital analysis is used for investigating charge transfer or conjugative interaction in the molecular systems. Some electron donor orbital, acceptor orbital and the interacting stabilization energy results from the second-order microdisturbance theory are reported [19,20]. The larger E(2) value the more intensive is the interaction between electron donors and acceptors, i.e. the more donation tendency from electron donors to electron acceptors and the greater the extent of conjugation of the whole system [21]. Delocalization of electron density between occupied Lewis-type (bond or lone pair) NBO orbitals and formally unoccupied (antibond or Rydgberg) non-Lewis NBO orbitals correspond to a stabilization donor– acceptor interaction. NBO analysis has been performed on the 2PCP1A molecule at the DFT levels in order to elucidate the intramolecular interaction within the molecule. The intramolecular interaction is formed by the orbital overlap between bonding BD(2)C5C6, BD(2)C9-C10 and antibonding BD*(2)C7-C8, BD*(2)C5-C6 orbital, which results in the intramolecular charge transfer causing stabilization of the system. The second-order perturbation theory of Fock matrix in the NBO analysis shows strong intramolecular hyperconjugative interactions and the results are shown in Table 3. The most important interactions observed are BD(2)C9C10BD*(2)C5-C6 and BD(2)C5-C6BD*(2)C7-C8 and the corresponding energies are 24.30 and 23.78kJ/mol respectively. This larger energy provides the stabilization to the molecular structure. Graphical representation NBO analysis is shown in Figure 2(b). [Click here to view Large Table 3] Molecular Electrostatic Potential (MEP) The MEP is a useful feature to study reactivity given that an approaching electrophile will be attracted to negative regions (where the electron distribution effect is dominant). The importance of MEP lies in the fact that it simultaneously displays molecular size, shape as well as positive, negative and neutral electrostatic potential regions in terms of color grading and is very useful in research of molecular structure with its physicochemical property relationship [22,23]. The resulting surface simultaneously displays molecular size, shape and electrostatic potential value. In the majority of the MEP, while the maximum negative region which preferred site for electrophilic attack indications as red color, the maximum positive region which preferred site for nucleophilic attack symptoms as blue color. The different values of the electrostatic potential at the surface are represented by different colors. Potential increases in the order red < orange < yellow < green < blue. In this study, the color code of the map is in the range between -0.01054a.u. (deepest red) and 0.01054a.u. (deepest blue) in the studied compound, where blue indicates the strongest attraction and red indicates the strongest repulsion. The MEPs of 2PCP1A molecule in 3D plots are represented in Figure 3(a). As can be seen from the MEP map shown in figure, although the regions having the negative potential are over the carbon and nitrogen (the electronegative atoms) and also the regions having the positive potential are over hydrogen atoms localized a maximum positive region. From these results, we can say that the ring, the nitrogen atom and all hydrogen atoms (especially H16 atom) indicate the strongest attraction and C3 and N4 atoms indicate the strongest repulsion. Molecular Orbitals Transport Properties The HOMO-LUMO gap results in a significant degree of electric excitation and charge transfer. In most cases, even in the absence of inversion symmetry, the strongest band in the Raman spectrum is weak in the IR spectrum and vice versa. Changes in the HOMO-LUMO gap by connecting with some noble metal or semiconductor or some other means result in the change of the charge transfer degree, intensity and position of the peak.The HOMO–LUMO gap estimated to be 6.04eV at the B3LYP/6- 31G(d,p) level and the frontier orbitals are illustrated in Figure 3(b).The experimental and theoretical UV–Vis spectra are shown in Figure 4(a). Theoretical and experimental maximum absorption wavelengths and excitation energy are collected in Table 3. The observed peaks were found at 225nm in the water phase. The calculated peaks were found at 227nm in the gas phase. The calculated peaks were thus 2nm higher than the observed peaks, and this error may have been caused by the error of PCM modeling. [Click here to view Large Figure 3] Natural Population Analysis The calculation of atomic charges plays an important role in the application of quantum mechanical calculations to molecular systems [24]. Our interest here is in the comparison of different methods to describe the electron distribution in 2PCP1A as broadly as possible, and assess the sensitivity of the calculated charges to changes in (i) the choice of the basis set and (ii) the choice of the quantum mechanical method. Mulliken charges, calculated by determining the electron population of each atom as defined in the basis functions. The Mulliken charges calculated at different levels basis sets are listed in Table 4. The corresponding Mulliken’s plot with B3LYP different basis sets are shown in Figure 4(b). [Click here to view Large Figure 4] [Click here to view Large Table 4] Global Reactivity and Charge Reactivity Descriptors The other electronic properties as the chemical potential (), electronegativity (), electrophilicity index () and chemical hardness () are given in Table 4. The, and are important tools to study the order of stability of molecular systems. Using HOMO and LUMO energies, the and have been calculated. The chemical hardness and the chemicalpotential are given by the following expression,(IA)/2, (IA)/2. The, which measures the stabilization energy, has been given by the following expression, in terms of electronic chemical potential and the chemical hardness: 2/2 electro negativity (),(IA)/2or where I and A are ionization potential and electron affinity of a molecular system [25-28].M presumably arises from adsorbed molecular water (Table 2). Thermodynamics Properties On the basis of vibrational analysis at B3LYP/6-31G(d,p), 6-311++G(2d,3p) and 6-31G(3df,3pd)levels and several thermodynamic parameters are calculated and are compared in Table 5. The zero point vibration energies (ZPVE) and the entropy, Svib (T) are calculated with B3LYP methods are to the extent of accuracy and the variations in ZPVEs seem to be insignificant. The dipole moment calculated using B3LYP/6- 31G(d,p), 6-311++G(2d,3p) and 6-31G(3df,3pd) basis sets are found. The total energies and the change in the total entropy of2PCP1A at room temperature are found to be marginal. [Click here to view Large Table 5] Conclusion A complete vibrational analysis of 2PCP1A was performed by B3LYP/6-31G(d,p), 6-311++G(2d,3p) and 6-31G(3df,3pd) basis sets. This study demonstrates that the DFT (B3LYP) calculations are powerful approach for understanding the vibrational spectra of the title molecule. FT-IR, FT-Raman and UV-spectral studies of 2PCP1A were carried out. The molecular structure analysis has been performed based on the quantum mechanical approach by DFT calculation. The vibrational modes are assigned on the basis of PED percentage. NBO analysis indicates the strong intramolecular hyperconjugative interaction within the molecule and stability of the molecule. Mulliken charges on 2PCP1A at different levels were calculated and the results discussed. HOMO, LUMO energies and HOMO-LUMO energy gap was also calculated. The maximum absorption peakmax in the UV-Vis spectrum has been observed at 304nm. The MEP map shows that the negative potential sites are on nitrogen and some of the carbon atoms as well as the positive potential sites are on the hydrogen and carbon atoms in the molecule. For more Open Access Journals in Juniper Publishers please click on: https://juniperpublishers.com/ for more details click on the juniper publishers material science

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4D Printing with Sequentially Controlled Morphing Abstract Sequentially controlled morphing (or folding/unfolding) has been a hot research topic for some years. With the additional feature of shape switching, 3D printing has been extended to 4D printing recently to significantly widen the potential application area. In technical terms, there are a few approaches to achieve 4D printing. In this paper, based the concept of multiple stable structure, we demonstrate how to achieve sequentially controlled morphing in 3D printed structures. We show that, the morphing sequence can be determined in the early design stage. Furthermore, utilizing the shape memory effect, we can even change the morphing sequence after the structure is 3D printed. Keywords: 4D printing; 3D printing; Reversible morphing; Sequential switching; Shape memory polymer Go to Introduction With the additional dimension of shape evolution against time, 3D printing has been extended into 4D printing, and the originally proposed concept of 4D printing and the underlying technologies to achieve 4D printing have been continuously modified [1-3]. One of the techniques currently under development is based the shape memory effect [4-6]. The shape memory effect refers to an interesting phenomenon that a piece of severely pre-deformed material recovers its original shape, but only at the presence of a right stimulus. Materials with such a capability are known as shape memory material [7-10]. Typical stimuli to trigger the shape memory effect include temperature (including both heating and cooling), chemical (including water and change in pH value) and light, etc [8-12]. Since most of polymers, including many conventional and newly available engineering polymers, are intrinsically have the heat/chemo-responsive shape memory effect [13], 3D printed polymeric items are inherently with the function of reconfiguration (morphing). In Figure 1, a piece of 3D printed (by Maker both) snake can be deformed easily at above its glass transition temperature (around 70 °C) into a shape. After cooling back to the room temperature (about 22 °C) and releasing the applied constraint, the temporary shape is largely maintained. Only upon heating to above the glass transition temperature again, the free-standing snake recovers its original shape. There are two processes involved in this cycle, one is to fix the temporary shape and is called programming, and the other is the recovery process. The material used for this snake is standard 1.75mm diameter poly (lactic acid) (PLA) filament. Since PLA is rather brittle at room temperature, the snake is relatively rigid and brittle and we cannot bend it too much at room temperature. Click here to view Large Figure 1 Same PLA filament is used to 3D print (Makerbot) a spiral spring as presented in Figure 2. The spring is able to be flattened after heating in hot water. Full shape recovery is observed when it is placed inside the hot water again. As compared with above mentioned snake, the flexibility of this spring is very much improved due to a kind of “structural design”. Hence, utilizing the heat-responsive shape memory effect, the same 3D printed spring may be programmed to instantly become an extension spring or a compression spring whenever needed, provided it is not over-heated to 95 °C or above. Over-heating of this PLA induces further crystallization. Consequently, the material becomes rigid at high temperatures as well and therefore it becomes difficult to effectively fix the temporary shape. Click here to view Large Figure 2 Above two examples clearly demonstrate the feasibility to have the morphing feature in 3D printed polymeric items. Despite of the achievement of morphing via the shape memory effect, programming is always required to fix the temporary shape before each cycle. This may not be convenient in some engineering applications. Sequentially controlled morphing (origami) is highly in demand in many applications, such as active assembly and disassembly, folding/unfolding of structures, and deployment and retraction of medical devices [14-19]. 3D printed sequential self-folding polymeric structures have been reported [5]. To avoid the un-convenience in programming and also high requirements in, e.g., design and 3D printing with multiple materials, for sequentially controlled morphing, we propose a simple way to achieve highly repeatable folding/unfolding using only one commercial filament. Essentially, this is an extension of the concept of bi-stable structures into multiple stable structures [2,20,21]. Since every individual shape is mechanically stable, upon loading/unloading, sequentially controlled morphing is guaranteed. Go to Flexible filament for 3D Printing Instead of using normal PLA filament in current 3D printing, which is brittle at room temperature, 1.75mm diameter Flexible filament from Shenzhen Esun Industrial Co. Ltd, China, was used for 3D printing via Makerbot. Differential scanning calorimetry test was conducted at a heating/cooling speed of 10 °C/min to identify its glass transition temperature as about 70 °C (Figure 3). The material does not have the crystallization problem (as that in normal PLA) even upon heating to 120 °C. Click here to view Large Figure 3 The stress vs. strain relationship at room temperature (about 22 °C) of the as-received filament was characterized by cyclic uniaxial tensile test to 5%, 10% and 15% strains in ascend order at a strain rate of10-3/s using an Instron 5569 with a load cell of 500N. The result is plotted in Figure 4. Herein, the stress and strain mentioned in this study are meant for engineering stress and engineering strain. The material is not fractured even being stretched to 15%, although significant residual strain is observed if it is over stretched. Based on the slope in the early unloading stage, the Young’s modulus (E) of the material can be determined as about 480MPa. A bi-stable structure was designed and 3D printed using this filament (Figure 5a). Upon compressing in the vertical direction, the as-printed shape switches to the other stable shape (Figure 5b). Subsequently, upon stretching in the vertical direction, the bi-stable structure switches back to the asprinted shape (Figure 5a). This reversible switching process can be repeated again and again as long as the involved maximum strain is well controlled in the design stage. Click here to view Large Figure 4 Click here to view Large Figure 5 Fundamentally, this type of structure is also known as a compliant structure, in which there is no conventional hinge at all, so that such a structure is just right for 3D printing. The shape memory effect and long-term stability of this material after 3D printing were investigated in this study. In Figure 6 (left), two identical Chinese words (meaning monkey) are 3D printed using this filament. The right piece is heated in boiling water and then its bottom part was bent to fix a temporary shape. Subsequently, there are left in air at room temperature for about two months. Unlike many currently used 3D printing materials, in particular those using UV light for curing, relaxation/creeping is virtually un-detectable in this material Figure 6 (middle). However, upon heating in hot water again, the programmed word returns back to its original shape Figure 6 (right). Thus, its excellent shape memory effect and long-term stability are confirmed. Click here to view Large Figure 6 Go to Design for Sequentially Reversible Multiple Stable Structures A commercial software, namely ABAQUS, is used for simulation via the finite element method (FEM) of the model with the potential for multiple stable shapes as shown in Figure 7a. The structure with a thickness of 10mmis supposed to be stretched (extension) and then compressed (compression) in the horizontal direction as indicated by two arrows. Essentially, there are three individual units from left to right in this structure. Each of them consists of an easy to buckle arch structure formed by two straight elements. The weakened end areas in each element serve as hinges. Due to symmetry, only half of the model as presented in Figure 7b (with major dimensions indicated) is used in current analysis. Click here to view Large Figure 7 It is obvious that with different geometrical dimensions, each unit may have a different buckling load, and thus to achieve sequentially controlled morphing in this multiple stable structure upon folding/unfolding. Figure 8a reveals the applied boundary conditions (in 3D) in the conducted simulation. The displacement at Ux=50 (as indicated) is controlled to simulate the process of extension/compression. Figure 8b shows the 2D mesh for FEM analysis. 8-noded hexahedral (brick) elements with reduced integration (C3D8R) are used to avoid the shear locking effect [22]. Click here to view Large Figure 8a Click here to view Large Figure 8 Since the actual filling ratio in later on 3D printing of the prototype is selected to be 70%, the Young’s modulus E used in current simulation is selected to be 350MPa and 0.35 is used for the Poisson ratio of this polymer for simplicity. The evolution in morphing of the model in cyclic extension/compression is captured by the FEM simulation. Figure 9 presents the shapes right before three sequential buckling events upon extension. Sequential buckling from the left unit toward the right unit is observed. The distributions of von Mises stress and the maximum principal strain around the hinges corresponding to the instants revealed in Figure 9 are plotted in Figure 10. The propagation of high stress and high strain from the pair of hinges in the left unit toward the pair of hinges in the right unit confirms the underlying mechanism behind sequential buckling from the left unit toward the right unit. Click here to view Large Figure 9 Click here to view Large Figure 10 Figure 11 reveals the force vs. displacement relationship in one full loading/unloading cycle. It is confirmed that upon extension, buckling starts from the left unit and propagates toward the right unit, while upon compression, buckling (opposite direction) follows exactly the same sequence as that in extension due to the difference in buckling load in each unit. A close-look reveals that the unit with a higher buckling load in extension requires a higher compression load for buckling as well, although the magnitude of buckling load in compression is less than that in extension for the same unit. Click here to view Large Figure 11 As demonstrated above, the FEM does provide a convenient approach to design a multiple stable structure with sequentially well controlled morphing function. Therefore, we can design different structures, which may be difficult to be fabricated using conventional manufacturing techniques, but can be 3D printed using a right material, with a prescribed folding/unfolding sequence required in a particular application. Go to 3D Printed Structures, Experimental Results and Comparison Using the 1.75mm diameter Flexible filament mentioned above, two prototypes with different configurations are 3D printed with 70% filling ratio using Makerbot. Subsequently, the prototypes were tested under cyclic loading/unloading (extension/compression) as they are initially designed for controlled sequential morphing using an Instron 5569 with a load cell of 500N at a speed of 1mm/s. In the experiments, the prototypes are placed vertically and fixed by top and bottom two clamps for extension/contraction along the vertical direction. In addition to record the applied force and corresponding displacement, a video camera is used to monitor the shape change in real time. The obtained force vs. displacement curves for Design I, which is the model for FEM simulation in Section 3, in four continuous cycles are plotted in Figure 12, together with photos (extracted from the video clip) right after each buckling event (the exact occasion is marked in the force vs. displacement curve, and since the corresponding force is zero, the free-standing structure is indeed mechanically stable). As we can see, in general, the resulted curves in all four cycles are well overlapped, which confirms high repeatability of the prototype upon mechanical cycling. Within a couple of limited areas, the curve of the 1st cycle is slightly away from the rest, which should be the result of additional initial boundary condition caused by the clampers. Click here to view Large Figure 12 The experimental result of the 4th cycle, which can be considered as a typical cycle, is compared with the simulation from (Figure 11) in Figure 13. Since buckling is a phenomenon of instability, the influence of imperfection (including those caused by 3D printing) could be significant. As such, it is very hard to precisely repeat the experimental result without a full consideration of these imperfections in simulation. Hence, according to Figure 13, we may say that our prediction (via FEM simulation) is able to catch not only the general trend, but also most of the major features observed in the experiments. Click here to view Large Figure 13 Figure14 presents the result of Design II, in which the sequence of buckling is initially designed as following: Click here to view Large Figure 14 Upon extension, the middle unit buckles first, then the left (bottom) unit buckles and finally buckling occurs in the right (top) unit. Upon compression, the left (bottom) unit buckles first, then the right (top) unit buckles and finally buckling occurs in the middle unit. So that this is different from the sequence of Design I, from the left (bottom) unit to the middle unit to the right (top) unit in both extension and compression. However, same as in Design I, good repeatability is observed, in particular in the last three cycles. Since the polymer used in current 3D printing has good heating-responsive shape memory effect, we heat the original shape of Design I to above its glass transition temperature and then extended the middle unit for buckling. After cooling back to room temperature, a modified Design I is resulted. Subsequently, we compress the middle unit for buckling again, so that the current shape of modified Design I looks to be identical to the original Design I, i.e., all units are in compacted state. Snapshot of one typical cyclic extension/compression test presented in Figure 15(a-f) reveals that the buckling sequence of the modified Design I is different from that of the original Design I, i.e., Click here to view Large Figure 15 Upon extension: the middle unit buckles first, then the left (bottom) unit and finally the right (top) unit. Upon compression: the left (bottom) unit buckles first, then the middle unit and finally the right (top) unit. In Figure 16, we compare typical force vs. displacement curves of the original Design I and modified Design I. Re-set the shape via the shape memory effect indeed changes the buckling force of the middle unit, and thus correspondingly, the buckling sequence is changed. The original buckling force for the middleunit is about 6N for extension, and 4N for compression. After modification, the buckling force for the middle unit is about 4N for extension, and 5N for compression. Click here to view Large Figure 16 Go to Conclusion In this paper, we demonstrate the feasibility to achieve sequentially controlled morphing in 3D printed multiple stable structures via two approaches, namely structural design and modification of the printed structure via the shape memory effect. Thus, different morphing or folding/unfolding sequence can be realized in the early design stage and/or later on after the structure is printed. Although the model investigated here is essentially 2D, which can be easily fabricated by many conventional manufacturing methods, such as injection molding, we believe that the basic concept proposed here can be extended to 3D structures, including those structures that are difficult to be fabricated by conventional manufacturing techniques. For more Open Access Journals in Juniper Publishers please click on: https://juniperpublishers.com/ for more details click on the juniper publishers material science

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New Cathode Material, Nd1.90Sr0.1Ni0.9Co0.1O4±Δ, for IT-Solid Oxide Fuel Cell Abstract The Oxygen Reduction Reaction (ORR) was studied on Nd1.90Sr0.1Ni0.9Co0.1O4±Δ nickeltaes as cathode material at high temperature, the citrate method was used for preparing the material. The study of Oxygen Reduction Reaction was carried out in air at various temperatures. Characterization by XRD and SEM were performed to analyze the crystallinity of the material. XPS analysis is used to evaluate the surface state of the material. Electrochemical studies were followed by impedance spectroscopy. The Nd1.90Sr0.1Ni0.9Co0.1O4±Δ cathode was deposited as a layer on a Gadolina Doped Ceria (GDC). At high temperature, a significant electrocatalytic activity is observed for the studied material that shows a relatively high electrocatalytic activity for O2 reduction. At high temperatures, the Nd1.90Sr0.1Ni0.9Co0.1O4±Δ material has best electrochemical properties, and the value of the activation energy is much lower compared to several materials synthesized and electrochemically characterized which indicates that Nd1.90Sr0.1Ni0.9Co0.1O4±Δ electrode is a promising cathode material for intermediate-temperature solid oxide fuel cell (IT-SOFC). Keywords: XPS analysis; MIEC; SOFC; Impedance spectroscopy; Electrocatalyst materials Go to Introduction In the second part of this work, increase the life time of solid oxide fuel cell (SOFC) need lower their operating temperature range of 800-1000 °C to 600-800 °C. This results in decreased electrochemical performance of SOFCs [1-5]. To remedy this, the research has been directed toward the development of new cathode materials called mixed conducting (ion and electron) symbolized MIEC. It’s a way to locate the reduction reaction of oxygen to the entire material, and significantly reduce the resistance and associated surges. K2NiF4-type materials such as neodymium nickelates Nd2NiO4, meet these criteria [6,7].A judicious doping with cerium, srtontium in neodym site and by cobalt or copper in nickel site of this new phase further enhances their electrochemical properties. However, it may in some cases lead to the formation of harmful secondary phases to the cathode/electrolyte interface [8,9].To remedy this, the research has been directed toward the development of new cathode materials called mixed conducting (ion and electron) symbolized MIEC. It’s a way to locate the reduction reaction of oxygen to the entire material, and significantly reduce the resistance and associated surges. K2NiF4-type materials such as neodymium nickelates Nd2NiO4, meet these criteria [6,7].A judicious doping with cerium, srtontium in neodym site and by cobalt or copper in nickel site of this new phase further enhances their electrochemical properties. However, it may in some cases lead to the formation of harmful secondary phases to the cathode/electrolyte interface [8,9]. Soori and Skinner have studied Nd2−xCexCuO4+δ (0≤x≤0.2) cathode interfaced with both GDC (Ce0.9Gd0.1O1.95) and LSGM(La0.9Sr0.1Ga0.8Mg0.2O3±δ) electrolytes [10]. The solid solubility limit of Ce in Nd2−xCexCuO4 has been reported to be at x=0.2 [10,11]. At this composition, the lowest value of activation energy (Ea=0.11eV) was measured over a temperature range of 500 to 700 °C [12]. In K2NiF4-type oxides, perovskite layer, ABO3, and rock salt layer, AO, are alternately stacked and they show oxygen excess composition because interstitial oxygen is formed in the rock salt layer [1,13,14]. The Nd2NiO4+δ and Nd1.8Sr0.2NiO4+δ materials, in high P(O2) atmosphere, show large oxygen excess composition, while Nd1.6Sr0.4NiO4+δ show almost stoichiometric oxygen composition. Space in the rock salt layer decreases as the calculated acceptor concentration, x+2δ, increases. This means that the interstitial oxygen formation is suppressed as the acceptor concentration increases. Similar tendency has been confirmed in oxygen nonstoichiometric behavior of Ni-based K2NiF4-type oxides [15]. Nd2NiO4+δ has been reported to exhibit promising electrocatalytic activity to oxygen reduction reaction when used as cathode for IT-SOFC [3,6]. The oxygen-diffusion coefficient of Nd2NiO4+δ is also much higher than that of La2NiO4+δ [6,16]. The Nd1.6Sr0.4NiO4 electrode gave a polarization resistance of 0.93 Ω.cm2 at 700 °C in air, which indicates that Nd2−xSrxNiO4 electrode is a promising cathode material for intermediate-temperature solid oxide fuel cell (IT-SOFC) [17]. In this work, we were interested to substitutions of small quantities of cobalt, less than 10%, in order to improve the cell performance by limiting the reactivity between cathode materials and electrolyte. Nd1.90Sr0.1Ni0.90Co0.1O4±δ powder are prepared, and the electrode were deposited by painting on the electrolyte substrate GDC in both faces. The microstructure and morphology of the samples were analyzed by X-ray diffraction and scanning electron microscopy. The electrochemical performance and a first approach of reaction mechanisms were determined by impedance spectroscopy. Go to Experimental The Nd1.90Sr0.1Ni0.90Co0.1O4±δ (NSNCO01) cathodes materials were prepared by Pichini process described by Mr. and FERKHI et. al [18,19], leads to the formation of particles with sufficiently fine size in order to increase the active surface of the material. The precursors used in the synthesis are; Nd(NO3)3.6H2O (99.0 % SIGMA- Aldrich), La2O3 (Biochem); Ni(NO3)2.6H2O (97,0 % SIGMAAldrich); Co(NO3)2.6 H2O 98,0 % SIGMA- Aldrich) and Sr(NO3)2 (Biochem). All precursors in a nitrate state are, first, dissolved in distilled water with appropriate amounts but the lanthanum oxide La2O3 are dissolved in nitric acid. The mixture of cations is under moderate stirring and a temperature between 75-80 °C. Then, citric acid (C6H8O7) is added in excess acting as a complexing agent. After evaporation of the solvent the solution begins to gel. The gel (viscous mixture) formed is dried at 120 °C and then treating at 174 °C leads to the obtaining of a foam which must be ground and calcined under various temperatures. In this work; electrochemical measurements at high temperatures were carried out on a symmetrical cell Nd1.90Sr0.1Ni0.90Co0.1O4±δ/GDC/ Nd1.90Sr0.1Ni0.90Co0.1O4±δ.Commercial Ce0.9Gd0.1O1.95 (GDC) oxide was used as electrolyte. For this, a pellet of diameter 10mm and a thickness of 1.14mm was prepared by uniaxial pressing under a pressure of 8 tons for 7min in a press “Specac”. This pellet was then sintered for 2 hours at 1400 °C to achieve a density of 95%. The ink consists of powder drop Nd1.90Sr0.1Ni0.9Co0.1O4±Δ and ethylene glycol (EG). The powder/EG ratio is one drop to 100mg powder. After mixed, the ink is applied as uniformly as possible on the GDC pellet symmetrically in both sides. Impedance measurements were performed using a configuration with two electrodes, the cell is then placed in a high temperature furnace. A frequency has been used as signal amplitude of 50mV imposed in a frequency range between 106Hz and 10-2. The X-ray diffraction spectra were obtained with a CuKα radiation (1.5406Å) of XPERT-PRO type diffractometer. The characteristics of the morphology and microstructure of powders were studied using an electron microscope type JEOL scanning/ EO version 1.07. XPS analyses were performed at the University of Namur, Belgium on a K-Alpha system (ThermoFisher Scientific), equipped with a monochromatic Al-Ka source (1486.6eV) and a hemispherical deflector analyzer working at constant pass energy. A 300μm diameter X-ray beam spot was used. Surface charging effects were avoided using an electron flood gun. The base pressure in the analyzer chamber was 2×10- 8Pa. Survey spectra were recorded with 200eV pass energy and, for high resolution spectra this energy was decreased to 30eV. The Thermo Scientific Advantage software (version 5.943) was used for collecting and processing the spectra. The binding energy shifts were calibrated relative to the adventitious carbon C 1s position fixed at 284.6eV and the BE accuracy was ±0.1eV . Go to Results and Discussion X-Ray diffraction analysis Diffraction patterns obtained at room temperature on the neodymium-based nickelates powder and lanthanum calcined at 1000 °C for 4h are shown in Figure 1. These diagrams show that the powders prepared is pure and well crystallized. The peaks were indexed using the JCPDS 21-1274 number and other work [2,17,20,21]. Click here to view Large Figure 1 NSNCO01 material was crystallizes in a tetragonal system with a group of spaces I4/mmm (high symmetry system) [17,21]. The refinement of the lattice parameters was performed and the results are; SG (space group): I4/mmm, a=b=3.8211, c=12.3488, α=β=γ 90 °V = 180.307 Å3and D=58.16nm. Morphological analysis From the results of the microstructure (Figure 2), it is observed that the materials are porous which improves its catalytic properties and the same electrocatalytic by increasing the surface area. The grains are forms spheroids with a grain size of about 0.5μm. The NSNCO01 material is more porous compared to Sr2MMoO6 (M=Fe and Co) double perovskites materials synthesized and studied previously [22]. Since the specific surface area, which depends on the porosity, double perovskites are of the order of 28 and 17.5m2/g respectively. Therefore, the NSNCO01 material can have a larger specific surface area by promoting, there after, the kinetics of the reduction reaction of oxygen. Click here to view Large Figure 2 XPS analysis The XPS general spectra for neodymium-based material is shown in Figure 3. It is obvious that all the elements that enter into the composition of the materials (including adventitious carbon) are present on the surface. The Figure 4 shows the oxygen peaks (O1s) after deconvolution. Five original peaks were distinguished with different binding energies. Click here to view Large Figure 3 Click here to view Large Figure 4 With regard to the oxygen region, it is well known the presence of various elements of different characters in the mixed metal oxides makes the bond between metal and oxygen not purely ionic. According to the classification established by T. L. Barr [23] we can say that NSNCO01 materials include O-Nd binding of high ionic character and O-Ni bond of normal ionic character. Therefore, the first has a lower binding energy than the second. Sr and Co doping elements in the sample are in very small quantities (Table 1) and belong to the previous two families, respectively. Therefore, their presence does not affect significantly on the energy of O-Nd and O-Ni bonds. Accordingly, the low energy component (a) and (b) at 527.53 and 528.61eV for NSNCO01 material stands for oxygen anions in neodymium oxides [23,24] and the component (c) at 530.17eV may denote the oxygen ions in nickel oxides [25]. The component (d) at 531.35eV can be ascribed to the metal hydroxyl groups because the rare earth oxides are very hygroscopic when exposed to atmospheric conditions [25,26]. The last component (e) at 533.30 eV with highest FWHM presumably arises from adsorbed molecular water (Table 2). Click here to view Large Table 1 Click here to view Large Table 2 The concentration ratio between Nd and Ni is a bit larger than the expected; so that we can say that the surfaces of both materials are slightly enriched in Nd. The Sr and Co incorporation does reduce this ratio (enrichment), because we measure that the (Nd+Sr)/(Ni+Co) ratio becomes close to the one before doping. From the Nd/Sr and Ni/Co values (16.66 and 1.51 respectively), the Sr and Co amounts on the surface are much greater than those of the theoretical stoichiometries. The ratio between the lattice ions and cations at the surface amounts (Olat /Σ cation) show that the surface of NSNCO01 material has a more anionic character. Finally, the XPS analyses tell us that the hydroxyls groups (or oxygen adsorbed in form of OH¯) percentage is 29.64%. This behavior may impact on the electrochemical properties of the materials (Table 3). Click here to view Large Table 3 Electrochemical characterization of NSNCO01 The amplitude test allowed knowing the regions of response of the electrolyte and the electrode. For this, the temperature is set by varying the amplitude (ΔE), two temperatures are chosen, 385 and 484 °C. The Nyquist diagrams stored in the frequency range 106 to 10-2Hz to different amplitude values, in air, are shown in Figure 5 & 6. Click here to view Large Figure 5 Click here to view Large Figure 6 Several contributions can be distinguished. Some of them can be attributed to the GDC electrolyte (high-frequency) response, while the low frequency phenomena reflect the interface process (electrolyte / electrode) and electrode detailed as follows [27]: At high-Frequency (HF): Two semicircles were distinguished; the first contribution, high lighting for frequencies above 105Hz, corresponding to the intra-granular conduction of ions O2- (contribution of “bulk”). While the second, located at frequencies between 105 and 102Hz, relative to the conduction related to grain boundaries (intergranular conduction) of the electrolyte. It may be noted that these contributions are clearly visible at low temperatures (Figure 5), where as at high temperatures (Figure 6), it becomes difficult to distinguish. At low frequency (BF): Two semicircles are distinguished (two contributions), the semicircle at medium frequency (MF) is relative to the ion transfer between the electrode (NSNCO01) and electrolyte (GDC), including the transfer of O2- species. The semicircle at low frequency (LF) would be associated with electrochemical phenomena at the interface of cathode material / oxygen gas (adsorption-desorption, dissociation, electrode reaction). These reactions can be decomposed in to the following steps (Eq.6-8). • Adsorption: O2 (gaz) ↔ O2 (ads) (Eq.6) • Dissociation: O2 (ads) ↔ 2O (ads) (Eq.7) • Reduction: O (ads) + 2e- ↔ O2¯ (insere) (Eq.8) The electrochemical performances of NSNCO01 were studied, the amplitude value (ΔE) was fixed at 50mV and changing the temperature, impedance spectra registered for a few values oftemperature (484-738 °C) in air, in the range of frequency 106 to 10-2Hz were plotted and shown in Figure 7. There is a very remarkable reduction in the resistance (R electrolyte and polarization resistance of electrode Rp) and therefore an increase in conductivity with increasing temperature. The kinetics of the phenomena associated with the electrodes and at the interface is thermally activated. Click here to view Large Figure 7 The electrochemical performance of the cell are measured by the following, based on resistors of different contributions to impedance measured patterns for different temperatures to 50mV (i≈0). From polarisation resistance of electrode (Rp), the surface resistance (ASR ohm.cm2) can be calculated. The Figure 8 shows the various resistances available on the impedance chart. ASR is calculated from the following equation: Click here to view Large Equation 1 Click here to view Large Figure 8 Surface of cathode, Rp: The polarization resistance associated with the LF and MF contributions. Figure 9 shows the thermal variations of ASRs plotted in the Arrhenius plot. The values of ASRs and activation energy (Ea) compared to other materials measured by other study were summarized in Table 3. Compared to all materials, the NSNCO01 electrode gave a polarization resistance (ASR) of 0.69 (Ω.cm2) at 700 °C in air and gave a low activation energy of, the order 0.88eV, which indicates that Nd1.90Sr0.1Ni0.9Co0.1O4±Δ electrode is a promising cathode material for intermediate-temperature solid oxide fuel cell (IT-SOFC). Click here to view Large Figure 9 Go to Conclusion All of the work has to propose a new cathode material, Nd1.90Sr0.1Ni0.9Co0.1O4±Δ, is a promising candidate as a cathode material for high temperature fuel cell (IT-SOFC). In the second part of this work, a electrochemical behavior carried by impedance spectroscopy at high temperature is performed on the material Nd1.90Sr0.1Ni0.9Co0.1O4±Δ. Resistance of surface polarization (ASR) was evaluated at 0.69 (Ω.cm2) at 700 °C which is much lower compared to ASR evaluated by some work done on other neodymium nickelates materials. In addition, the activation energy of our material is about 0.88eV, which is the lowest value compared with other materials studied to date. Which indicates that Nd1.90Sr0.1Ni0.9Co0.1O4±Δ electrode is a promising cathode material for intermediate-temperature solid oxide fuel cell (IT-SOFC). For more Open Access Journals in Juniper Publishers please click on: https://juniperpublishers.com/ for more details click on the juniper publishers material science

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SUITABILITY OF MAIZE COB ASH AS A PARTIAL CEMENT REPLACEMENT Abstract Cement is the most utilised construction material, and the second most consumed global commodity after water. Its demand has soared proportionately with the exponential rise in population to match required development. The heavily energy-intensive processes involved in its production contribute to about 7 to 10 per cent (%) of the total global emissions, with potentially adverse environmental implications and are expensive economically. These processes and those of concrete production consume heavily on natural resources such as sand, gravel, water, coal and crushed rock, the mining of which mars the environment. It is however possible, that energy and cost efficiency can be achieved by reducing on the amount of clinker, and in its place utilising Partial Cement Replacement (PCR) materials that require less process heating and emit fewer levels of carbon dioxide (CO2). This study investigated the ability of corncob ash to be used as a PCR, by testing for either pozzolanic or cementitious properties. Experiments were carried out by replacing cement by weight in concrete mixes with corncob ash at 5%, 7.5%, 10%, 15% and 20% steps at the point of need. The results were compared with a control specimen made with no cement replacement. Durability was tested using the sulfate elongation test. The highest compressive strength was observed at the 7.5% replacement. However, higher replacement levels also showed impressive strengths suitable for structural applications. The sulfate elongation test results showed good performance for all corn cob ash specimens in comparison to the control mix. These findings showed good reproducibility and highlight the potential of corncob ash as an effective pozzolan. Keywords: Corncob ash; Pozzolans; Cementitious materials; Maize cob ash; Partial cement replacements Go to Introduction Cement, a major constituent of concrete, is pivotal to development and is produced in virtually all countries. One ton of concrete on average is produced every year for every human being in the world. Cement is deemed to have a considerably high carbon footprint, contributing immensely to global anthropogenic CO2 [1-5]. Utilisation of Partial Cement Replacements (PCRs) reduces solid waste, cuts on greenhouse gas emissions and conserves existing natural resources, thereby enhancing sustainability as well as improving the properties of fresh and hardened concrete. This paper investigated the suitability of Corn Cob Ash (CCA) for use as a PCR in Africa, where it is available in abundance [6-10]. Go to Methods Cement was substituted with PCRs by weight in percentages of 0, 5, 7.5, 10, 15 and 20, with the 0% being the control specimen. For sulfate elongation tests, specimen prisms of 160 x 40 x 40 were cured for seven days before being immersed in 5% Na2SO4, 5% MgSO4 and 5% +5% Na2SO4 and MgSO4. Length change due to sulphates was measured to ASTM-C1012/C1012M (2013) at 133 days. All preparation and testing were done in accordance with BS EN 197-1:2000, BS EN 12390 series and ASTM C1012 [11-15]. Chemical analysis The sum of SiO2+Al2O3+Fe2O3 for the CCA sample used for this study was 54.1%, and therefore did not satisfy the pozzolanic recommendations of ASTM (2012) and BSI (2000a) of SiO2+Al2O3+Fe2O3 70%, but it did satisfy some requirements of both pozzolanic and cementitious materials. However, the method used to incinerate the CCA may have affected its chemical composition as the CCA used by other researchers achieved these values. Go to Results and Discussion Table 1 and Figure 1 show the compressive strengths achieved at different ages with different CCA replacements. The highest compressive strength for the population was found at 7.5%, with maximum stresses of 63.5Nmm-2 recorded at 91 days. Apart from the 20% replacement, all other replacements realised compressive strengths of above the 25N/mm-2 at 28 days. Compressive strength increased with curing age in line with literature, and at 91 days, all replacement levels showed impressive compressive strengths suitable for structural applications. CCA replaced specimens were darker in color and had a lower density than that of the control. The workability of the CCA replaced mixes increased with increased replacement.For the sulfate elongation tests, findings showed the change in lengths for all CCA samples were less than the control sample thus indicating improved sulphate resistance [15-20]. Click here to view Large Table 1 Click here to view Large Figure 1 Go to Conclusion CCA used for the study did not satisfy the minimum chemical composition requirements for pozzolanic materials of SiO2+Al2O3+F2O3≥70%, but it did satisfy some requirements of both pozzolanic and cementitious materials. Compressive strengths observed throughout all replacements were capable of structural applications. The compressive and sulfate resistance tests also showed good repeatability with previous studies, with strengths capable of structural applications observed over all replacements. These results show that CCA can be used as a partial cement replacement to mitigate on the cost of cement and its impacts on the environment whilst also improving sulphate resistance [21-30]. For more Open Access Journals in Juniper Publishers please click on: https://juniperpublishers.com/ for more details click on the juniper publishers material science

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Mycoplasma Pneumoniae Infection: A Case Requiring Follow-Up in Intensive Care Unit | Juniper Publishers

Juniper Publishers-Open Access Journal of Anesthesia & Intensive Care Medicine

Authored by Sema Avcı

Case Report

The community-acquired pneumonia due to Mycoplasma pneumoniae is usually mild. Severe life-threatening pneumonia is rare due to this kind of infection. Our case was a 50-year-old healthy male patient. Patient with bilateral pneumonia, acute respiratory failure and high fever was followed in the intensive care unit and noninvasive mechanical ventilation was performed. IFAT Mycoplasma species IgM 1/80 were positive. This case report shows that community acquired pneumonia with acute respiratory failure is not seen only elderly and immuncompromised patients. This kind of pneumonia may also seen in healthy adults.A 50-year-old man admitted to emergency room with high fever, cough, sputum, headache and dyspnea. The patient’s medical history and family history were unremarkable. Smoking status was active. On respiratory system examination, tuber sufl on the right middle zone, and inspiratory rales were revealed on the left lung middle side. The patient’s blood pressure was 80/40 mmHg, pulse was 105/beats per minute, fever was 390C, respiratory per minute was 34 and oxygen saturation on finger monitor was 74%. The patient with moderate general status was admitted to the intensive care unit.Laboratory examination: White blood cell 20.1(109/L), C-reactive protein: 37.9 mg/dL and sedimentation 95 mm/h. There was no growth in blood culture, urine culture and sputum culture. IFAT Chlamydiae: Negative. IFAT Mycoplasma IgM 1/10 (+), 1/20 (+), 1/40 (+), 1/80 (+). Electrocardiogram was sinus rhythm. Chest x-ray showed pneumonic consolidation with air bronchogram in bilateral middle and lower zones (Figure 1). Double antibiotic treatment was started. Non-invasive mechanical ventilation was performed for 3 days in intensive care unit. A significant improvement in chest x-rays taken on day 3 and 10 of treatment (Figures 2 & 3). The aim of this case report is to show the serious results of mycoplasma infection in a healthy individual.

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The Promise of Magnesium Based Materials in Electromagnetic Shielding Abstract Electromagnetic pollution is emerging as one of most dominant pollution in recent times largely due to the widespread use of electronics equipment ranging from the personal use, societal benefits to modern warfare. Also known as electromagnetic smog, this pollution is not only capable to disrupt the existing systems but can also affect the human health adversely. Accordingly, it is becoming important to progress in this area through developing and designing materials and promoting technologies that are superior to the one currently used for shielding electromagnetic waves. The aim of this paper is to introduce readers to electromagnetic radiation threats and the current materials science that is used to mitigate these effects. Go to Introduction Electro smog (e-smog) or electromagnetic pollution has increased tremendously in recent years due to ever increasing use of electronic gadgets. Accordingly, it is not surprising that electromagnetic pollution has emerged as fifth largest pollution after noise, water, air and solid waste pollutions [1]. For example, our exposure to electromagnetic radiation is millions of times more than 50 years ago putting us at a much higher health risk than our previous generations [2]. Shielding materials are thus required so that electromagnetic interference (EMI) is neither able to disrupt critical devices, equipment, and systems (such as medical, military and aerospace electronics) nor it is able to cause catastrophic health effects on users [3]. Go to Electromagnetic Wave And Spectrum An electromagnetic wave (radio waves, microwaves, infrared, ultraviolet, X-rays and gamma rays) consists of electric and magnetic components. These electric and magnetic fields are always in phase and at 90 degrees to each other (Figure 1) [4]. Electromagnetic waves can travel in vacuum and at the speed of light. A typical electromagnetic spectrum is shown in Figure 2 [4]. Electromagnetic radiation can broadly be categorized into two types: Click here to view Large Figure 1 Click here to view Large Figure 2 Ionizing radiation: Examples, far UV rays, x-rays and gamma rays (can damage DNAs). The photons of these rays have enough energy to break chemical bonds (Table 1) [5, 6]. Click here to view Large Table 1 Non-ionizing radiation: The photons do not have enough energy to ionize atoms or molecules. Such radiations are capable of heating living tissue through energy transfer by photons. Examples are visible light, infrared, microwaves, and radio waves. Go to Sources Of EM Radiation Major sources of electromagnetic radiations include [7]: a. Natural Sources: Electric storm (of frequency ~10MHz); solar radiations (of frequency~10MHz) b. Artificial Sources: Manmade sources. All electrical equipment radiate electromagnetic fields. Table 2 shows the sources of electromagnetic radiations and our susceptibility to their exposure irrespective of whether we are at home, in the office or in the city [5,8]. Click here to view Large Table 2 Go to Consequences Of Electromagnetic Interference (EMI) On systems and equipment functioning EMI, if not controlled can cause [9]: Disruption in railroad and mass transit system. Disruption in vehicular control system. Disruption in the functioning of medical equipment that includes life support devices, x-ray machines, electrical and electronic equipment in surgical units, patient telemetry and assistance. Compromises in military warfare. On health and living organisms The study of interactions between EM radiations with living organisms is known as Bio electro magnetics. Human beings usually operate at frequencies between 2-12Hz. Normal household current is 50-60 Hz and is thus incompatible and disruptive to body’s natural electric frequency regime, neural transmission system and its sensitive neuro-chemical equilibrium [10]. It is thus not surprising that exposure to electromagnetic radiations can lead to adverse health effects. Magnetic fields associated with electromagnetic radiations can induce electric currents in bio-systems including humans, animals, and plants leading to adverse effects on metabolism and hormone productions. This is because electromagnetic alternating fields are many times stronger than body currents and thus body fails at many times to trigger its own adequate compensation mechanisms leading to weakness, sickness, and diseases [3]. Some adverse health effects that are linked to exposure to electromagnetic radiation include [3,10]: Unusual neurological functions such as dementia, chronic fatigue, and fibromyalgia, Cancer including leukemia. Hypertension. Alzheimeir’s disease. Headaches. Parkinson’s disease. Cardiovascular problems (heart and blood vessels). Rheumatoid arthritis. Effect of eyes including cataracts. Metabolic changes in tissues. Changes in the immune system. Adverse effects on male (reduced sperm count and sexual drive) and female reproductive systems (such as disruption of the menstrual cycle). It has also been cited that exposure to electromagnetic radiations has a cumulative effect increasing over time and with dose [3,10,11]. Go to International Efforts In view of EM threat, many countries in the world including the European Union are taking initiatives to ensure protectionagainst the electromagnetic radiations from as early as 1989 (Electromagnetic Compatibility Directive-Council Directive 89/336/EEC) [7]. NATO recommends electromagnetic shielding for computers and keyboards to mitigate monitoring of keyboard emissions that can allow the passwords to be captured [12,13]. The World Health Organization (WHO) has classified radio frequency electromagnetic radiation as Group 2B - possibly carcinogenic [4,14]. This group contains possible carcinogens that have weaker evidence, at the same level as pickled vegetables and automobile exhaust. WHO also classified all UV frequencies as Group 1 carcinogens as they can directly or indirectly damage biological molecules. For example, ultraviolet radiation from sun exposure is the primary cause of skin cancer [4,15]. Sweden also, for example, lists electromagnetic field as Class 2 Carcinogens along with tobacco [16]. Besides several international authorities (such as International Commission on Non-ionizing Radiation) have also set safety limits for public and occupational EMF exposure to 50-60Hz [2]. Go to Shielding Against Electromagnetic Radiations Shielding against EM waves is done through the use of conductive enclosures known as Faraday cages. Such cages are conductive in nature and often used in cables, mobile phones, and microwaves. Figure 3 shows such a cage used in a mobile phone. Such shielding prevents the escape of any signal from inside to outside and also prevents any signal to pass from outside to inside [13,17,18]. Click here to view Large Figure 3 The mechanism includes cancelling the applied electric field and magnetic field by the conducting material that is used to avoid the leakage from inside to outside and outside to inside. Three mechanisms that attenuate electromagnetic waves are [19]: Absorption(A): Materials need high magnetic permeability. Reflection(R): Materials need high electrical conductivity. Multiple reflections(MR): Materials need a large surface or interface area. The losses irrespective of above mechanisms are expressed in dB. The shielding effectiveness (SE) is the cumulative effect of the losses due to above three mechanisms. SE = A + R + MR (1) Go to Materials Used And Selection Criteria The different materials used for electromagnetic shielding are listed in Table 3 along with their advantages/disadvantages. Click here to view Large Table 3 Table 3 indicates that metals and composites (metal based or plastic/ceramic based) can be used for electromagnetic shielding and their selection largely depends on [23]: End application. Cost factor. Performance level. Conductivity. Materials thickness. Corrosion. Application frequency. Among these materials, magnesium is a strong choice as it exhibits good electrical conductivity and is the lightest of all metals. That makes it a strong choice in portable electronic devices due to weight factor and in defense sector where polymer based materials may not qualify due to their poor thermal capabilities. Go to Introducing Magnesium Magnesium is the lightest metallic element that can be used in a wide spectrum of engineering applications spanning from electronics to automobile to sports sectors [1]. Its abundance in planet earth (6th most available in earth crust and 3rd most available in the hydrosphere, 4th most abundant cation in the human body) makes it an extremely cost-efficient material. Some of the advantages of magnesium include [20]: Low energy requirement in solidification based processing. Ease of processing using conventional solid state methods. Applicability of conventional plastic deformation processes to realize complex shapes. Ease of recycling. Superior specific mechanical properties. Good machinability. Go to Electromagnetic Shielding Capability Of Magnesium-Comparison Table 4 lists the electromagnetic shielding capabilities of magnesium, its alloys, and other materials. Table 4 clearly reveals the superiority of magnesium over that of aluminum. This is especially important as aluminum is currently most commonly used light weight material while magnesium is strongly emerging as its replacement due to its ability to provide additional ~33% weight saving at the component level. Magnesium like most other metals provides shielding primarily based on reflection mechanism. The weight saving benefit of magnesium extends over the full frequency spectrum [21]. For shielding based on absorption, die cast magnesium compares equally with aluminum in shielding effectiveness on an equal weight basis. It has been established that die cast magnesium alloy enclosures for EMI shielding are superior compared to both plastic and other metal housings [22]. An investigation into composites of magnesium also revealed that magnesium based syntactic composites provide similar shielding efficiency as that of aluminum composites while providing a much lighter weight (Table 4). The use of coated cenospheres in AZ91 matrix appeared to exhibit a less decline in SE with increasing frequency [23]. The use of reinforcement was attempted by researchers to add on the multiple reflection mechanisms in addition to reflection mechanism. The challenges include the formation of secondary phases and reduction in conductivity that adversely affect the reflection mechanism. Click here to view Large Table 4 Go to Concluding Remarks With a growing trend towards light weighting to reduce the fuel consumption and to enhance the human comfort (light weight laptops and portable devices), it is becoming important to design and use materials that are environment friendly and superior in performance when compared to conventional materials. Magnesium is a promising choice as it is the lightest metallic element and with inherently good electromagnetic shielding capabilities. However, the number of investigations done to improve the shielding effectiveness of magnesium is limited so far and much effort are required to develop magnesium based materials that are capable of invoking different mechanisms of shielding when in use. With sustained research efforts, shielding effectiveness of magnesium based materials can be raised to an excellent level which will assist in reducing electromagnetic pollution or smog and its adverse effects on living organisms including humans. For more Open Access Journals in Juniper Publishers please click on: https://juniperpublishers.com/ for more details click on the juniper publishers material science

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A Correlation between Localized States and Meyer-Neldel Relation in Crystallization Process of Amorphous Sete Films Abstract Electrical conductance is measured in amorphous SeTe films to investigate the crystallization mechanism in the system. The crystallization is found to occur at the sample-substrate interface. The Arrhenian temperature dependence of crystallization velocity estimates the activation energy. The Meyer-Neldel relation (MNR) has been observed in amorphous SeTe films through a correlation between pre-exponential of growth velocity and activation energy. The presence of localized states in amorphous chalcogenides and its relation to viscosity for controlling crystallization mechanism in films is discussed. PACS: 71.23.-k; 72.15.Cz; 73.61.Jc; 77.84.Bw Go to Introduction Crystallization in amorphous Se-Te binary and ternary alloys has been studied using various techniques such as Differential Scanning Calorimetry (DSC) [1], Differential Thermal Analysis (DTA) [2-3], Electron Microscopy [4-5] etc. The electrical conductivity has been previously used to determine the crystallization process in amorphous bulk alloys [6-7]. Since in chalcogenides, the conductivity of the amorphous state is lower than that of crystallized state, the electrical measurements are expected to be very sensitive to the phase changes in thin films in comparison with other conventional methods such as DSC or DTA [8]. This paper describes an attempt to deduce from the crystallization kinetics, the growth rate and activation energy when the crystallization is induced at the sample-substrate interface. Go to Experimental Details The Se: Te films were prepared by vacuum evaporation technique onto degassed glass substrates held at room temperature. The Te content of the prepared samples was 0, 10, 20 and 30 at. % of Se. The thickness was kept constant and was measured to be 750nm. The X-ray diffraction pattern showed that the samples were amorphous in nature. Before evaporation of the thin films, Indium electrodes of about 1mm thickness were deposited on the glass substrates. The contacts were found to be ohmic in the present voltage range of measurements. The electrical measurements were made by applying a voltage of 5V to the samples. The sample current was measured by measuring the potential drops across a resistance connected in series with the sample using a digital micro voltmeter (Systronics). The samples were annealed at various temperatures (333K - 348K), which were chosen to observe crystallization in appropriate crystallization velocities. A vacuum of 5*10-3 Torre was maintained during the entire procedure. Go to Results And Discussion When nuclei covers a surface of radius r and when r is large compared to the thickness of the layer, e , then the crystallization occurs similar to an epitaxial growth, the crystalline phase reaching the opposite surface of the layer at a time t=e/vc (vc is the growth rate) [9]. This is referred to as Surface Induced Crystallization (SIC). Such crystallization is actually polycrystalline It has been shown that at any given time t, the conductance of the layer can be written as Click here to view Large Equation 1 where σm is the conductivity of the partially crystallized layer during the annealing process and σa is the conductivity of theamorphous layer [10]. The crystallization velocity was obtained through the measurements of τ (time at which the linearity of Σ(t)/Σ(a) curve breaks off). The conductance variation during the isothermal annealing of amorphous films of Se:Te (Te = 0-30 at.% of Se) is shown in Figure 1. The crystallization time τ was obtained at each annealing temperature and corresponding growth rates vcwere calculated. Click here to view Large Figure 1 The crystallization process was seen to occur in three stages. During the first stage (0o), conductance increases quadratic ally with time as the fit of the data has predicted. It has been shown that the crystallization in a-Se: Te films occur in a twodimensional way at the interface [5]. Above two-dimensional crystallization leads to a quadratic variation of conductance with time [8]. During the second stage (toc). The crystallization velocity obtained using the above relation for Se80Te20 film as a function of temperature is shown in Figure 2. The behavior for all compositions is the same. Similar behavior was also observed in bulk glasses [6]. Finally, the conductance saturates for t >τ. The saturation of the conductance relation after time τ results from the crystallization of the rest of the amorphous domains in the thin films. This occurs as all the nucleation sites were exhausted and the growth of the crystallites stops, i.e., site saturation [10]. Click here to view Large Figure 2 The crystallization velocity obtained in the experiment was found to decrease continuously with increasing Te concentration at each of the annealing temperatures. As is evident from Figure 2, the crystallization velocities show a thermally activation behaviour with an Arrhenian dependence for each of the composition given by [11] Click here to view Large Equation 2 Figure 3 shows the dependence of the activation energy Ec of crystallization on the Te content. The pre-exponential of crystallization velocity also show same type of behavior. In the range x=0 to 20 at.% in Se: Te films, both Ec and vco decrease monotonically. The Te induced retardation was also observed in the melt quenched bulk glasses studied by us [6] and others [12]. With a further increase in Te, these quantities go through a minimum at 20 at.% Te. A similar compositional dependence of the activation energy of crystallization has been reported in melt quenched Se: Te bulk glasses by Ganaie et.al. [13]. Click here to view Large Figure 3 The minimum in Ec can be understood as follows. The cis- (ring segment) and trans- (helical chain segment) configurationsin amorphous Se differ only in the placement of the 5th neighbor atom for molecular bondings [14]. The placement of the likely atom depends on the competition between the intra-chain and inter-chain forces. It is expected that the number of cisconfiguration starts to decrease near this configuration with increasing Te content, because the intra-chain force of Te is weaker than that of Se. The intra-chain force decreases and the inter-chain force increases with the addition of Te atoms to a-Se. The minimum activation energy at the particular Te concentration is therefore, likely to be attributed to such an intermediate range structural modification. The increase of glass transition temperature with Te concentration also indicates increasing chain lengths of Se-Te [15] and hence to a more rigid network. Figure 4 shows the plot of the pre-exponential factor vco versus the activation energy Ec of the crystallization velocity in thin films. There is a very good correlation between the vco and Ec, often referred to as the Meyer-Neldel relation [16] and is described as Click here to view Large Figure 4 Click here to view Large Equation 3 Where vco is a constant with a value of about 1.8*10-3nm/s and Eco~0.0483eV as deduced from Fig.4. Here, the obtained value of Meyer-Neldel energy is 48.3meV, which is well within the range 25-100meV generally reported in semiconductors [17]. This energy corresponds to Meyer–Neldel temperature equal to 560K , that is within the reported range of temperatures 260-950K [ 18]. Assuming that the crystallization velocity in amorphous materials is inversely propotional to the viscosity of the melt η [12], which has a Vogel-Tammann-Fulcher type of behaviour [19], i.e., η=ηo exp (Eo / k (T-To)), where ηo, Eo and To are constants, then the crystallization velocity becomes Click here to view Large Equation 4 This equation is almost indistinguishable from Eqn. (2) in a narrow range of temperature except for the vicinity of To. Moreover, if we try to fit the Arrhenian dependence of vc in a temperature range T1 to T2 , we obtain [5] Click here to view Large Equation 5 Where Click here to view Large Equation 6 y1=a-b, y2= ln(a/b), y3=ln{(a - 1)/(b - 1)}, y4= (1/b)-(1/a), a= T2/To; b=T1/To. The estimated Eco value of 0.0325eV is obtained using T1=330K, T2=360K and To=303K. This is an indication that the crystallization velocity in a-Se:Te films can be considered to be controlled by the viscosity of the melt. The variation in Vicker’s hardness in chalcogenides around crystallization temperatures also allows us to correlate our results with viscosity [20]. The increase in glass transition temperature with Te concentration is a good indicator of the increase in viscosity with Te [21]. Although the Meyer-Neldel relation has been observed in various physical systems, there is still no satisfactory uniform explanation for its occurrence. Several mechanisms to explain the origin of MNR in semiconductors have been proposed. Jakson [22] argued that whenever a multiple trapping transport process is observed as a function of temperature, MNR should be followed. Abtew et al. [23] have performed a comparative study of MNR in crystalline Si and non hydrogenated amorphous silicon and claimed that MNR is present in amorphous silicon only. They suggested that the existence of localized state and the energyelectron lattice coupling for these states is an essential feature of MNR in silicon amorphous phase. Thus, MNR presence is closely connected to the presence of band tail of localized states which are generally assigned to the disorder in film network. In disordered semiconductors, three conduction mechanisms may occur: Hopping from one localized sates to another localized state. Carrier hopping from localized state to an available extended state. Carrier scattered from one extended state to am empty extended state. The first two conduction mechanisms require phonon assistance. Transition (i) and (ii) plays a role at low and moderate temperature. However the transition (iii) may be significant only in higher temperature. The conductivity in the films is governed by the multi-trapping process in band tail localized states and explains the MNR observation in films. The present system gives a wide band gap semiconductor with exponential localized tail states proposed by Roberts [24].Since the conduction mechanism in films involves localized states, the electronic transport is achieved through electrons trapping and detrapping by multi-phonon process with the contribution of many phonons. This conduction model was first suggested by Yelon and Movaghar to explain MNR in thermally activated conduction [25]. In localized states conduction, the activation energy of the transition from localized state with energy Ei to an empty localized state with energy Ej is given by [26]. Click here to view Large Equation 7 Where Er is the reorganization energy of the semiconductor random network for carrier hopping and is expressed as Click here to view Large Equation 8 Where ϵi and ϵj are the localization radii for the two localized states, R is the distance between the two localization centers [27], e is the elementary electric charge, ϵ0 is the vacuum dielectric constant, ϵop and ϵs are optical and static dielectric constants respectively. With increasing the disorder, the distance R increases and the film density decreases, consequently the film refractive index and optical dielectric constant are reduced [28,29] This leads to the increase of the two square brackets in Eq. (8) and then to the increase in the reorganization energy Er and consequently the reduction of the activation energy Ea. Go to Conclusion The conductance measurements carried out on SeTe glassy films between the glass transition and crystallization temperatures provides information about the crystallization mechanism in thin films. During the early times, the crystallization is due to nucleation and conductance varies quadratically with time. When the nucleation is completed, the conductance varies linearly and the process occurs as a result of growth of crystallites towards the surface. The addition of Te reduces the growth and activation energy show a minimum at x=0.6. Meyer Neldel relation is found to be obeyed in the present case through pre-exponential of velocity and activation energy. This can be assigned to an increase in localized states resulting in increase in viscosity of the specimen around Te 60 at%. For more Open Access Journals in Juniper Publishers please click on: https://juniperpublishers.com/ for more details click on the juniper publishers material science

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Preparation and Photocatalytic Activity of Co: La: Tio2 Nanocomposites for the Degradation of Methyl Blue in Visible Light Material Science-Juniper Publishers Abstract In this study, prepared the nano composites of Co: La:Tio2 by the wet chemical method. Synthesized Tio2 and Co:La:Tio2 were characterized by X-Ray Diffractometer, SEM,TEM, UV-vis, FT-IR, Band gap energy and BET. The Tio2 and Co:La:Tio2 were used as photocatalyst for the degradation of Methyl Blue. The XRD pattern confirmed the presence of anatase and rutile phase in the catalyst. The particle size was estimated by the Scherrer’s and found 68 and 32nm for Tio2 and Co: La: Tio2 respectively. The particle morphology of the photocatalysts was found in nanodiamension. The surface area of the photocatalysts were found 37.52 and 106.68m2/g for Tio2 and Co: La.Tio2 respectively. The band gap energy of Tio2 and Co: La.Tio2 were 3.2 and 3.0eV. The photo degradation of Methyl Blue has been found maximum at 5pH, 25ppm concentration of dye, 800mg/L amount of photo catalyst and 180min illumination of visible light. The photo degradation was following the first order kinetics. Keywords: Photodegradation; Photocatalyst; Photocatalysis; Methyl blue; Nanocomposite Go to Introduction Dyes are the most resistant compounds that are found in industrial waste water causing adverse environmental problems. Most of the dyes used in the pigmentation of textiles, leather, paper, ceramics, and food-processing are derived from azo dyes. Dyes are lost with waste water during synthesis and processing [1-5]. This represents a great hazard to human and environmental health due to the toxicity of azo dyes [6]. The treatment of such pollutants can be achieved by heterogeneous photo catalysis due to its efficiency and low cost as well as to the fact that it allows complete degradation of pollutants to carbon dioxide and inorganic acids [7-9]. Titanium dioxide Tio2 is a most important nanomaterial which has attracted a great attention due to its unique properties. Titanium dioxide Tio2 have excellent merits in solar energy transferring and photocatalysis of poison compounds in environment. The chemical inertness and the non-toxicity of Tio2 have also made it a superior photocatalyst [10-13]. Titania has a large band gap (3.20ev for anatase Tio2) and therefore, only a small fraction of solar light can be absorbed [14]. Many attempts have been made to sensitize titanium dioxide to the whole visible region, such as doping with transition metals [15-16], transition metal ions [17], non-metal atoms [18] and organic materials [19]. Introduction of dopant allows Titania to absorb in the visible region but this does not necessarily mean that the doped catalyst has a better photocatalytic activity (Figure 1). Click here to view Large Figure 1 In photocatalysis, light is absorbed by an adsorbed substrate. Today, semiconductors are usually selected as photocatalysts, because semiconductors have a narrow gap between the valence and conduction bands. In order for photocatalysis to proceed, the semiconductors need to absorbed energy equal to or more than its energy gap. When Tio2 is irradiated by UV light (400nm or less), electron is excited to generate electron (e_) hole (h+) pairs.This movement of electrons forms e-/h+ or negatively charged electron/positively charged whole pairs. The hole can oxidize donor molecules. In photo generated catalysis the Photocatalytic Activity (PCA) depends on the ability of the catalyst to create electron-hole pairs, which generate free radicals able to undergo secondary reactions [20-24]. Go to Methodology Synthesis of titania by wet chemical method Click here to view Large Equation 1 Synthesis of Co:La:Tio2 nanocomposite In this method, 10ml of TiCl4 solution (1000mg/l), 2ml of 0.1M Cobalt acetate, 1ml of 0.1M Lanthanum nitrate and NaOH solution (64.5g/l) was added drop wise to water with stirring. After the resulting solution reaches pH to 7, the slurry was filtered, and the filter cake of Tio2 was washed and redispersed in water to prepare 1M of Tio2 slurry. Resulting Tio2 slurry and an aqueous solution of HNO3 were refluxed at 95 °C for 2h, cooled to room temperature and neutralized with 28% of aqueous ammonia. Then, it was filtered, washed and calcined at 400 °C [25,26]. In this study, Co:La:Tio2 nanocomposites was prepared by solution impregnation method. In this method suitable quantity of prepared Tio2 (2g) was dispersed in alcoholic cobalt acetate 10% (w/v) and lanthanum nitrate 5% (w/v). The dispersion is agitated continuously for 4 hour at 80 °C temperature. After the treatment the residue was removed through filtration and was sintered for 4hour in presence of air at 600 °C by kipping it in a silica crucible inside the muffle furnace. After sintering and slow anilling to room temperature, content was taken out from furnace and was stored in air tight bottles and was used as photocatalyst [27]. Click here to view Large Equation 2 Characterization The physical properties of metal oxide semiconductor nanocomposites that may influence significantly their use as photocatalyst are dependent on nature of crystalline phase present. Thus, phase analysis is an important parameter for this study and the prepared samples were subjected to x-ray diffraction analysis on Powder X-Ray Diffractometer. The observed X-Ray diffractogram of samples were analyzed further to estimate average grain size in the sample by Scherrer’s calculation. Since the absorption of light by photocatalyst is the most crucial step in any photocatalysed reaction, and is decided primarily by the band gap energy of material. The morphology and size of the Titania particles were analyzed by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Photo-degradation of dyes In this study by the photo-catalytic degradation of Methyl Blue was investigated. A solution of dye in water: alcohol (10:1V/V) was prepared and in this solution a suitable quantity of photocatalyst (100 to 800mg/L) was dispersed. The dispersion was subjected to Visible light irradiation for varying duration and after desired irradiation the residual concentration of dye in the solution was determine spectrophotometrically by taken out suitable aliquot of dispersion and removal of photocatalyst by centrifugation. For quantitative estimation of dye concentration, initially calibration curve was obtained and it was utilized to measure the concentration in different sample aliquot obtained at different time. A quantitative estimation of dye concentration spectrometric observation when recorded only at the experimental determines λ max value which is 670nm [28-30]. Go to Results Phase identification by X-ray diffraction analysis The obtained X-Ray diffraction patterns of Titania and Co:La:Tio2 are shown in Figures 2a & 2b. The observed pattern of peaks, when compared with the standard JCPDS database, suggested that, in prepared Tio2 sample, major peaks at 2θ=25.5° 37.2, 48.3, and 54.4, which can be indexed to the (101), (004), (200), and (211) crystal facets of anatase Tio2 (JCPDS File number: 21-1272). Whereas major peaks at 2θ=26.9° and 28.2° indicate the presence of rutile phase which can indexed to the (110), (121), respectively. In case of Co:La:Tio2 sample, the observed XRD pattern indicates not only a change in the peak intensity, compared to Tio2, but even the absence of some originally observed Tio2 peaks [31]. This is, probably, due to the change in the crystallinity and grain fragmentation, when the samples were wet impregnated by cobalt and Lanthanum. Click here to view Large Figure 2 Determination of crystalline size of samples The Scherrer’s calculations were attempted to know the average size of particles/grains in the samples [32]. Although, Scherrer’s calculations are only approximate in nature, but definitely provide a first-hand idea of the Crystalline size of samples, which may be quite accurate, provided the size of crystal is below 100nm. The results of Scherrer’s calculations are presented in Table 1. The results suggest Crystal size in the samples lying in nm range. Click here to view Large Table 1 Scanning electron microscopy (SEM) The morphology of the samples was investigated by scanning electron microscopy and it resumes the most interesting outcomes. 3(a) and 3(b) clearly show that both the prepared samples are obtained in nanometric dimension. The doping of cobalt and lanthanum is indicating that the particle size reduce due the penetration of cobalt and lanthanum in the lattice of titanium dioxide [33] (Figure 3). Click here to view Large Figure 3 Transmission electron microscope (TEM) TEM images were clearly displayed the morphology and particle size of neat Tio2 and Cobalt and lanthanum doped Tio2. From the Figure 4 we find that Cobalt and lanthanum doped modified Tio2 change the size of neat Tio2 significantly, as shown in Figure 4(a) & (b). The sizes of both modified and neat Tio2 are mono disperse about 100-200nm. Moreover, the crystal lattice line can be clearly found in the TEM images. The aggregations of both kinds of particles are caused by high surface energy; however, the agglomeration of the modified one is alleviated obviously compared with that of the neat [34]. Click here to view Large Figure 4 Surface Area Analysis (BET) Figure 5 shown the BET and adsorption and desorption plot for the Tio2 and Co:La:Tio2. With the help of Figure 6 we can determine the specific surface area, pore volume and average pore size of the Tio2 and Co:La:Tio2 photocatalyst. Table 2 shown the physical properties of Tio2 and Co:La:Tio2. The Tio2 modified by Cobalt and Lanthanum are fragmentation to some extent during thermal treatment, leading to a marked increase of the BET surface areas and the average pore radius size and decreasing of the pore volume [35,36]. Click here to view Large Figure 5 Click here to view Large Figure 6 Click here to view Large Table 2 UV-Vis spectra Aqueous suspensions solution of the photocatalysts was used for the UV absorption studies. The absorption spectrum of Tio2 consists of a single broad intense absorption at 384nm due to the charge-transfer from the valence band to the conduction band [37]. The undoped Tio2 showed absorbance in the shorter wavelength region while Co:La:Tio2 result showed a broad peak at 425nm in the higher wavelength (Figure 7). The impregnation of Co and La ions into Tio2 could shift optical absorption edge from UV to visible range, but prominent change in Tio2 band gap was observed [38]. Click here to view Large Figure 7 Band gap energy determination The band gap of samples was calculated by extrapolation of the (αhv)2 versus hv plots, where α is the absorption coefficient and hv is the photon energy, hv=(1239/λ) eV. The value of hv extrapolated to α = 0 gives an absorption energy, which corresponds to a band gap (Eg). Figure 8 yields an Eg value of 3.2eV for Tio2 and 3.0 for Co:La:Tio2 [39]. The slight decrease in band gap energy in case of Co:La:Tio2, is due to formation of subband level between valence band and conduction band caused impregnation of Co+2 and La+3 in Tio2 host. Click here to view Large Figure 8 Photo-degradation of Dyes The photo-catalytic degradation of Methyl Blue in the presence of Tio2 and Co:La:Tio2 has been studied. The solution of dye was prepared in 10:1 (V/V) ratio of water and alcohol. The known amount of photocatalyst 800mg/L was dispersed in the dye solution. The reaction mixture was illuminated under visible light, while kept continuously under agitation, for the different time intervals and different temperature. The residual concentration of dye in the reaction mixture was measured spectrophotometrically. The results obtained for the degradation of Methyl Blue is shown in Figure 9-11. Click here to view Large Figure 9 Click here to view Large Figure 10 Click here to view Large Figure 11 Effect of temperature: The effect of system temperature on photocatalysis has not attracted enough attention. But In present research, it is found that the temperature has a great effect on the photodegradation of Methyl Blue. The photocatalytic efficiency can be increased about 2-3 times if the temperature increased from 30 °C to 40 °C Because the solar energy include UV light, which can be used to activate the photocatalytic course, which is increase the temperature of photocatalytic system. The experiments showed that Methyl Blue were photodegraded in presence of photocatalyst and Visible light. The Methyl Blue was efficiently degraded shown in Figure 9. The obvious decrease of concentration of dye shows that the Tio2 and Co:La:Tio2 can serve as an effective photocatalyst [40]. Effect of concentration of dye: Effect of dye concentration Keeping the catalyst loading concentration constant at 800g/ liter of the dye solution, the effect of varying concentration of the dye was studied on its rate of degradation (from 25ppm to 100ppm) as given in Figure 10. With increasing concentration of Methyl Blue the rate of degradation was found to decrease. This is because as the number of dye molecules increase, the amount of light (quantum of photons) penetrating the dye solution to reach the catalyst surface is reduced owing to the hindrance in the path of light. Thereby the formation of the reactive hydroxyl and superoxide radicals is also simultaneously reduced. Thus there should be an optimum value maintained for the catalyst and the dye concentration, wherein maximum efficiency of degradation can be achieved [41]. Effect of irradiation time on photodegradation: The effect of irradiation time on the photodegradation of methyl blue has been studied in presence of Tio2 and Co:La:Tio2. The photodegradation of methyl blue was increased with increase irradiation time. The photodegradation was found maximum in case of Co:La:Tio2 for 180min irradiation of visible light. Fig.11 shows the effect of irradiation time on photocatalytic degradation of methyl blue. This is due to the interaction of dye molecule with the surface of photocatalyst as well as the time of irradiation increase the interaction increased. Therefore the photodegradation efficiency of photocatalyst was increased. Effect of pH of solution: The photodegradation reaction was also carried out under varying ph conditions from (2 to 9), by adjusting with H2 SO4 and NaOH, with Tio2 kept at constant amounts of 800mg/ L of dye solutions (Figure 12). The reaction was found to have low rates at acidic ranges of pH. While at pH 5 photodegradation was found maximum. This implies that less acidic conditions are favourable towards the formation of the reactive intermediates that is hydroxyl radicals is significantly enhanced, which further help in enhancing the reaction rate. On the other hand in highly acidic medium conditions for the formation of reactive intermediates is relatively less favorable and hence less spontaneous [42]. Click here to view Large Figure 12 Effect of photocatalyst amount: The effect of photocatalyst amount has been studied by applying the different amount (100ppm to 800ppm) of the photocatalyst. The photodegradation rate was found to increase by increasing the amount of photocatalyst. It is clear from the results shown in Fig.13, the photodegradation increased rapidly with increase of amount of Co:La:Tio2. This is due to the fact that introduction of Co2+ and La+3 the band gap energy decreased up to 3.0eV which enhance the photocatalytic activity [43]. Effect of photocatalyst: It is clear from the results shown in Figure 9-12 that both Tio2 and Co:La:Tio2 are effective photocatalyst for the degradation of Methyl Blue (MB) dye. However Co:La:Tio2 seems to be more effective as photo-catalyst for the degradation of Methyl Blue (MB). The prominent degradation of Methyl Blue was found in 3 hour study in the presence of Co:La:iO2 in comparison to the prepared Tio2 [44] (Figure 13). Click here to view Large Figure 13 Recyclability of photocatalyst The photocatalyst and Methyl Blue mixture was agitated, illuminated with visible light and after desired time, the mixture was centrifuge to remove the photocatalyst. The obtained photocatalyst was washed three times with distilled water and kept in oven for 24h at 60 °C and reused for the degradation of Methyl Blue. The photodegradation of Methyl Blue by the recyclized Photocatalyst are showing in Figure 14. The result shows that the recyclized photocatalyst efficiency is slightly decreased probably due to the loss of some active sites and decrease of collection efficiency of photon [45]. Click here to view Large Figure 14 Stability of composite photocatalyst: Some kinds of experiments were carried out to confirm the photostability of polyaniline modified Tio2 photocatalysts. The FT-IR spectra of PANI-modified Tio2 particles before and after reaction were recorded as shown in Figure 9. It is found that the shape of composite IR spectrum after photocatalytic experiment is similar to that of particles before experiment. It indicates that the structure of PANI-modified Tio2 does not change during the photo catalytic process. The PANI is very stable and is not chemically transformed to other organic compounds. It has been confirmed that the PANI-modified Tio2 shows good stability under irradiation conditions and they continue to maintain perfect photocatalytic activity also after several cycles (Figure 10). A slight decrease of photoactivity after each cycle is due to slight aggregation of nanoparticles during the catalytic process. Lowering of electron-hole recombination Photoluminescence spectra have been used to examine the mobility of the charge carriers to the surface as well as the recombination process involved by the electron-hole pairs in semiconductor particles. PL emission results from the radiative recombination of excited electrons and holes. In other words, it is a critical necessity of a good photocatalyst to have minimum electron-hole recombination. To study the recombination of charge carriers, PL studies of synthesized materials have been undertaken. PL emission intensity is directly related to recombination of excited electrons and holes. Figure 15 shows the photoluminescence spectra of synthesized photocatalysts. In the PL spectra the intensity of Tio2 is higher than Co:La:Tio2 indicating rate of recombination of e-- h+ is higher in Tio2 than that of Co:La:Tio2.The weak PL intensity of Co:La:Tio2 may arise due to the impregnation of Ni in Titania lattice, which for sub band level in band gap region of Tio2. This delays the electronsholes recombination process and hence utilized in the redox, reaction leading to improved photocatalytic activity [46]. Click here to view Large Figure 15 Hydroxyl radical formation As hydroxyl radical performs the key role for the decomposition of the organic pollutants, it is necessary to investigate the amount of hydroxyl radicals produced by each photocatalyst. In this study Terephthalic Acid (TA) has been used as a probe reagent to evaluate •OH radical present in the photoreaction pathway. Figure 16 shows the PL spectra of Tio2and Co:La:Tio2 recorded Methyl Blue solution in presence of 10- 3M Terephthalic solution. OH radical attack Terephthalic, forming 2-hydroxyl Terephthalic Acid (TAOH) which gives a fluorescence signal at 426nm. The fluorescent intensity is linearly related to the number of hydroxyl radicals formed by the photocatalysts. Higher the generation of hydroxyl radical, more will be yield of TAOH and hence more intense will be the fluorescence peak. The spectra show that the intensity of peak indicating in presence of Co:La:Tio2 higher generation of more number of hydroxyl radicals compared to Tio2 [47]. Click here to view Large Figure 16 Mechanism of photooxidation process The photocatalytic mechanism is initiated by the absorption of the photon hv with energy equal to or greater than the band gap of Tio2 (3.3eV for the anatase phase) producing an electron hole pair on the surface of Tio2 nanoparticles. An electron is promoted to the Conduction Band (CB) while a positive hole is formed in the Valence Band (VB). Excited state electrons and holes can recombine and dissipate the input energy as heat, get trapped in meta stable surface states, or react with electron donors and electron acceptors adsorbed on the semiconductor surface or within the surrounding electrical double layer of the charged particles. After the reaction with water, these holes can produce hydroxyl radicals with high redox oxidizing potential [48-50]. Depending upon the exact conditions, the holes, OH radicals, O2, H2O2 and O2 itself, When the semiconductor is illuminated with light (hυ) of greater energy than that of the band gap, an electron is promoted from the VB to the CB leaving a positive hole (h+) in the valence band and an electron (e-) in the conduction band as illustrated in Figure 17. Click here to view Large Figure 17 If charge separation is maintained, the electron and hole may migrate to the catalyst surface where they participate in redox reactions with sorbed species. Specialy, h+vb may react with surface-bound H2O or OH- to produce the hydroxyl radical and ecb- is picked up by oxygen to generate superoxide radical anion (O2-), as indicated in the following equations 6-8; Absorption of efficient photons by titania (hυ ≥ Ebg = 3.2ev) Tio2+ hυ → ecb + h+vb (6) Formation of superoxide radical anion O2 + ecb → O2- (7) Neutralization of OH- group into OH by the hole (H2O ⇔ H+ + OH-)ads + h+vb → •OH + H+ (8) It has been suggested that the hydroxyl radical (•OH) and superoxide radical anions (O2 - ) are the primary oxidizing species in the photocatalytic oxidation processes. These oxidative reactions would results in the degradation of the pollutants as shown in the following equations 9-10; Oxidation of the organic pollutants via successive attack by OH radicals R + •OH → R. + H2O (9) or by direct reaction with holes R + h+ → R+ → degradation products (10) Kinetic study The pseudo-first-order rate constant (k, min-1) for the photodegradation reaction of Methyl Blue was determined through the following relation where, k can be calculated from the plot of ln (Co/Ct) against time (t), Co and Ct denote the initial concentration and reaction concentration, respectively. ln Co/Ct =k1 t……………………………………..……………1 In addition, the linear feature of plots of ln(Co/Ct) versus time (Figure 18) indicates that this photocatalytic degradation reactions follow the pseudo-first-order rate law [51-54]. The rate constant of the photocatalysis at 30 °C is 0.04260 to 0.0234min- 1. The effect of temperature and concentration are showing in Table 3. Click here to view Large Figure 18 Click here to view Large Table 3 Thermodynamic parameter study In this section an attempt has been made to calculate different activation parameters. For this the reaction has been studied at two different temperatures and with the help of observed rate / rate constant, the energy of activation (DE*), specific rate constant (kr), entropy of activation (DS*), enthalpy of activation (DH*), free energy of activation (DG*) and Arrhenius frequency factor (A) have been computed for different reactions (Table 4) [55]. The activation parameters have been calculated with the help of following equations. Click here to view Large Table 4 DE* = value of slope x 2.303R log A = Log kr (at 35 °C ) + Ea /2.303RT ΔS* = 2.303 R(log A-13) ΔG* = Ea - TΔS* ΔH*=ΔG* + TΔS* The calculated values of various activation parameters for different redox systems are as follows: Go to Conclusion Prepared nanocomposites of Co:La:Tio2 were characterized by X-Ray Diffractometer, SEM,TEM, UV- Vis, FT-IR, Band gap energy and BET. The Tio2 and Co:La:Tio2 were used as photocatalyst for the degradation of Methyl Blue. The particle size was estimated by the Scherrer’s and found 68 and 32nm for Tio2 and Co:La:Tio2 respectively. The surface area of the photocatalysts were found 37.52 and 106.68m2/g for Tio2 and Co:La.Tio2 respectively . The band gap energy of Tio2 and Co:La. Tio2 were 3.2 and 3.0eV. The photodegradation of Methyl Blue has been found maximum at 5pH, 25ppm concentration of dye, 800mg/L amount of photocatalyst and 180min illumination of visible light. The photodegradation was following the first order kinetics. For more Open Access Journals in Juniper Publishers please click on: https://juniperpublishers.com/ for more details click on the juniper publishers material science

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Giant Hyalinizing Trabecular Carcinoma of the Thyroid Gland in a 20-Years Old Male Patient | Juniper Publishers

Juniper Publishers-Open Access Journal of Endocrinology and Thyroid Research

Authored by Michael S Papageorgiou

Abstract

Hyalinizing trabecular tumors (HTT) are a rare and relatively young entity in thyroid pathology. They are tumors that are frequently mistaken for papillary or medullary carcinomas and they are characterized by the trabecular growth pattern and hyalinizing stroma. Most of them are benign, but there are few reports of malignant behavior (capsular invasion, metastases etc.) We report a case of a 20-years-old male with a 6,5cm left lobe thyroid nodule, who was treated with total thyroidectomy and level VI lymph nodes dissection. The final pathology diagnosed the tumor as a Hyalinizing trabecular carcinoma (HTC).

Keywords: Hyalinizing trabecular carcinoma; Hyalinizing trabecular tumor; thyroid

Introduction

Hyalinizing trabecular tumors were first described in 1987 by Carney et al. [1] who reported a series of 11 cases that they were categorized as HTTs, while the distinctive features of these tumors were the trabecular cell growth pattern and the hyalinizing stroma [1]. Ever since, it was believed that these tumors were completely benign, with only a handful of exceptions. To add in the controversy, in everyday practice, these tumors were often misdiagnosed as papillary carcinomas or medullary carcinomas. To answer this controversy, World Health Organization (WHO) classified these tumors as Hyalinizing trabecular tumors (HTTs), thus including adenomas and carcinomas in a mixed category [2]. HTTs affect mainly the female population (male to female ratio 1:6) [2,3]. Although cases were reported between 20 and 80 years old, the mean age of diagnosis is 50,5 years-old. We report a rare case of a 20-years-old male with a gigantic (6,5cm) Hyalinizing trabecular carcinoma (HTC). Diagnosis and treatment are presented, and some key points of the literature are discussed.

Case Report

A 20-years-old male patient presented to the Outpatient Department with a large cervical mass, extending predominantly to the left side. Family members stated that he had the mass for many years (at least 4 years), although not as big as it was at present. The patient had no previous medical conditions and there was not any family history of thyroid diseases. An ultrasound and a CT scan demonstrated a large nodule of the left thyroid lobe, measuring 9x6,5x5cm and two smaller cystic nodules in the right lobe. Lymph nodes ultrasonic investigation demonstrated mildly enlarged level VI nodes, with no evidence of infiltration, while an FNA of the large mass showed a Thy-4 neoplasm, suspicious for papillary carcinoma. Considering the size of the tumor and the evidence of lymph nodes participation, a total thyroidectomy with level VI lymph nodes dissection was proposed and finally performed. In surgery, a neuromonitoring device was used and both recurrent laryngeal nerves and 4 parathyroid glands were identified and saved. The postoperative course was uneventful, and the patient was discharged on the first postoperative day, with calcium supplements and thyroxin tablets. Final pathology stated that the large mass was a Hyalinizing trabecular carcinoma. Detailed description stated that the tumor cells were arranged in elongated trabeculae and in one point the tumor extended through the adjacent capsule in an invasive growth pattern. Immunotoxins showed positivity for PAX-8 and TTF-1, while chromogranin and calcitonin were negative. Ten (10) lymph nodes that were removed, proved to be negative for malignancy. Patient was referred for RAI treatment and it was performed with any indications of persistent or recurrent disease (Tg<0,1 ng/ml with TSH 78,3 μIU/ml). Afterwards, the patient was under close follow-up, and 2 years since, he is free of any indications of recurrence.

Discussion

Hyalinizing trabecular tumors (HTT) are a new entity in thyroid pathology. The tumors show some mutual characteristics with papillary carcinomas (RET/PTC rearrangements) thus leading some experts believe that they are merely a subtype of papillary carcinomas instead of a distinct category [4]. Other cases are mistaken as medullary carcinomas, non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) or even as paragangliomas [5]. Diagnosis is made as in every other thyroid nodule. Ultrasonography features are general and usually include hypo echogenicity or marked hypo echogenicity in the absence of other suspicious features (calcifications etc.) FNA results are often misleading as well. A previous study showed that only 8% of HTTs were diagnosed preoperatively with FNA and an additional 6% was only suspected. Most of the times FNA reports indicate a possibility or even a certainty for papillary carcinoma (55%-60%) [5,6]. In our case, the FNA report was highly suspicious for papillary carcinoma, with a possibility of 60%-75%. To add up to the controversy, most authors considered HTTs to be always benign. In the following years though, cases were reported with malignant behavior, such as lymph nodes and pulmonary metastases, or detection of BRAF mutations [7-9]. Unfortunately, these few cases cannot be surely distinguished by FNA, core biopsy, or even frozen section during surgery (only 53% could be diagnosed correctly) [10]. In our patient, we performed a total thyroidectomy with central compartment lymph nodes dissection, based on the high suspicious for PTC and the possible lymph nodes participation. Treatment is also an issue for debate. Since the majority of HTTs are benign, a lobectomy is the treatment of choice for these lesions. But taking in concern that even a few cases have a malignant potential and can lead to metastatic disease, a completion thyroidectomy and RAI treatment must be performed in these patients [2,10,11]. Our case presented in this report, is a very rare case of an HTC. The patient was male, in a young age, with a very large tumor. Malignancy was established by a microscopic invasion of the capsule by the tumor cells. Although the size of the tumor was large, lymph nodes removed were negative for infiltration and the postoperative course indicates a relatively low malignant potential.

Conclusion

In conclusion, Hyalinizing trabecular tumors represent a relatively new, rare and understudied part of thyroid pathology. Most of the knowledge acquired is by case reports or a few small case series in the literature. In our opinion, large multicentral studies should be designed, in order to address these following significant questions.

• What is the true malignant potential of these tumors?

• How can we increase our chances for a correct preoperative diagnosis, in order to avoid unnecessary total thyroidectomies and identify only the malignant ones?

• Is a lobectomy the preferred treatment in these tumors from start? What should be our surgical strategy for these patients? Is there a need for prophylactic lymph nodes dissection if there is a possibility or certainty for malignancy?

• Is RAI treatment needed in these patients? And if yes, what is the survival rate in malignant cases?

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Corrosion Protection of Crude oil or Product Storage Tanks- Front End Designs (FEED) Material Science-Juniper Publishers A Case Study A skid mounted Formation water storage tank farm was set up in a remote marginal oil field in North East India. A Cathodic Protection system was installed in the tanks to protect them from Galvanic corrosion over 10 year service life. The tanks had the following design and process data. Inside diam=6.0m. Height to eaves=4.5m Fixed cone type roof. Liquid capacity=100Kls (Cu.m). Nominal capacity=120Kls. Storage temp=Ambient. Storage pressure = Atmospheric. Max /Min temp (Amb)=38 /3 ᵒC. Design temp = 65 ᵒC. Material of construction = Carbon Steel. Corrosion allowance=3mm Salinity of water=8500ppm. pH=9.5. Go to System Design Approach Design calculation for a single tank will be made The terrain is hilly with heavy slush and mud during monsoon season which extends over April-Dec period every year. This makes the approach to the equipment difficult, requiring stand alone type with least maintenance and low capital investment. So a Sacrificial Anode system was installed. Design life=10 years. Tank painted with 200 micron DFT Coal Tar Epoxy paint on both sides including structural skid which rests on ground. The system is shown in the above figure the tank steel structure is exposed to stored formation water zone inside, atmospheric zone outside and the base in soil zone. Calculation of steel areas in various zones Table 1 Click here to view Large Table 1 Atmospheric zone=3.142 x 6.01 x 4.5 + 3.142 /4 x 7^2=123 m^2 Water zone= 3.142 x 6 x 4.5=85“ Soil zone=3.142 x 6.8^2/4=36“ Table 2 Effective areas. Water zone (inside of tank ) no painting damage=85 m^2 Click here to view Large Table 2 Atmospheric zone (outside of tank) 15% painting damage during installation=105 m^2 Soil zone (tank skid and bottom) 50% painting damage during installation=18 m^2 Assuming uniform 3% painting deterioration per year, the total deterioration during 10 year service life is 30 % Painted area in water zone after 10 years = 60 m^2, Bare area=25 m^2 Painted area in Atmospheric zone=74m^2, Bare area=31m^2 Painted area in soil zone=13m^2, Bare area=5m^2. Total current required for polarisation and maintenance after 10 years Water zone = 60x38 /1000 + 60 x 25 /1000=3.8 Amps Atmospheric zone=74 x 15/1000+31 x 75/1000=3.5Amps. Soil zone=13 x 5/1000+57 x 5/1000=0.35Amps. Therefore, total current required for the entire structure after 10 years=3.8+3.5+0.35=7.65Amps. Design of anode The anode must provide maintenance current over 10 year period. So, the current required is average of initial and final maintenance currents and=(4.92 + 7.65)/2=6.3Amps. The anode will be of high purity Zinc to stand 10 year service life. The weight of Zinc is given by W=CR x L x Amp/n x u Where W=Weight of Zinc in Kgs, CR is the consumption rate of zinc in Kg/Amp year. L=Service life, n=Efficiency factor and u=Utilization factor. In this case W= 10.7x10x6.3/0.9x0.8=936 kilograms. Using 200mmx200mmx300mm long anodes, weight of each anode=0.2x0.2x0.3x7073kg/m^3=84.8kgs, 12nos anodes of this size will provide 1018 kilograms. Energy capacity of the anodes@810A-hr per kilogram=810 x 1018=1,466,100 amps. Energy required for initial polarisation and maintenance over 10 year period = (4.92 +7.65) x 365 x 24 x 10 +13.17 = 1,101,145.17 amps. Therefore, the anode system will be adequate Figure 1 Click here to view Large Figure 1 For more Open Access Journals in Juniper Publishers please click on: https://juniperpublishers.com/ for more details click on the juniper publishers material science

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Bulk Metal Alloys as a Precursor of Dispersed Particles Catalyzing Growth of Carbon Nanofibers Abstract Bulk metal alloys can be considered as a precursor of self-organized catalysts consisting of dispersed metal particles fixed within the structure of carbon nanofibers, which were grown as a result of catalytic chemical vapor deposition of halogen-substituted hydrocarbons. Being subjected to interaction with aggressive reaction mixture, the bulk alloy precursors undergo relatively fast process of metal dusting, which ends with complete wastage of initial metal item. The catalysts thus obtained are characterized with excellent long-term stability of operation along with high activity in decomposition of hydrocarbons of different nature. The approach described opens new horizons for a synthesis of nanostructured carbon materials including carbon-carbon composites of bimodal structure. Keywords: Bulk metal alloys; Metal dusting; Self-disintegration; Carbon nanofibers; Catalytic chemical vapor deposition Go to Introduction Industrially manufactured bulk metal alloys mostly being the resistive materials are widely applied in the heating systems (as a heating element), in the explosives and fireworks industry (as a bridge wire in igniters), in ceramic (as an internal support structure), etc. These materials are quite stable under both oxidative and reductive atmospheres, but undergo fast self-disintegration if exposed to carbon-containing (carburizing) medium at elevated temperature. The process of self-disintegration of metal items, also known as a metal dusting, is considered as an actual problem of modern chemical industry, which results in a wastage of chemical reactors [1-9]. Thus, steel reactors operated at 400-800 °C during hundreds hours become almost completely disintegrated into a dust consisting of dispersed metal particles and carbon. The situation becomes more complicated if the aggressive medium of halogen-substituted hydrocarbons is used [10,11]. There are a lot of papers devoted to the study on the mechanism of the metal dusting [1,3,6,7,9]. According to Grabke [1], the process goes through the following stages: Decomposition of carbon-containing precursor with subsequent transfer of carbon into solid solution up to oversaturation. Nucleation of metal carbide phase at surface and grain boundaries and its growth with protrusions into the bulk metal phase. Nucleation of the graphite phase. Decomposition of carbide to metal and graphite. Nano particle formed plays a role of catalytic sites for carbon nanofibers (or nanotubes) growth. Formed catalytic sites (dispersed metallic or alloyed particles), being stabilized within the structure of carbon nanofibers, catalyze further formation of nanostructured carbon via catalytic chemical vapor deposition. Thereby, the process of self-disintegration (metal dusting) can be proposed as a novel approach to prepare dispersed metal particles from bulk metal precursors for the synthesis of nanostructured carbon [12-17]. Go to Discussion During the last two decades the process of metal dusting as a way to obtain nanostructured carbon materials attracts more and more attention [12-24]. Carbon nanotubes and nanofibers of various morphologies were produced over stainless steel, iron- and nickel-containing alloys. In all these cases, the surfaceof bulk metals was intentionally subjected to controlled process of metal dusting yielding carbon deposits. As it was already mentioned, the process of self-disintegration is characterized with prolong induction period (up to few hundred hours), when no visible changes take place. At the same time, if the halogenated hydrocarbon is used as a carbon source, the process accelerates significantly [10,11,25,26]. Thus, interaction of bulk nickel alloys (nichrome, chromel, alumel, etc.) with vapors of chlorinated hydrocarbons results in a fast metal dusting with induction period no longer than 3 hours at 550 °C. It should be noted that induction period shortens along with temperature increase. At the end of induction period, the weight of the sample sharply grows up, and the system became inverted into an ensemble of dispersed metal particles fixed within the structure of grown carbon nanofibers. These particles can be considered as self-organized catalyst, and can be applied for decomposition of any other carbon-containing substrates with formation of nanostructured carbon. Thereby it can be concluded that halogen contained in a molecule of substrate affects crucially the rate of metal dusting. HCl emerged in hydrogen-containing reaction mixture provides the occurrence of reversible chlorination-dechlorination process, which leads to quick chemical corrosion of bulk alloy surface. It should be also emphasize that the addition of hydrogen excess into reaction mixture is required for dechlorination of the alloy surface [10]. The duration of induction period of the self-disintegration process can be shortened by using the pretreatment procedures [25,26]. Among such procedures, the most efficient are etching in a mixture of mineral acids (HCl/HNO3=3/1, 2-3min) and redox activation (altering of oxidative and reductive treatment at 500 °C, 3 cycles, 90min).These methods make a rough reconstruction of the alloy surface that eases further formation of dispersed active particles. While the considered alloys are resistive materials, they can be heated up to desired temperature by a direct supply of current. Decomposition of 1,2-dichloroethane in such regime is reported in Ref. [27]. In this case, besides the processes described above, hydrodechlorination and dechloro-coupling reactions take place leading to formation of ethane, ethylene and butenes within the gas phase products. At the resistive heating, the process of substituted hydrocarbon decomposition proceeds through the stages of C-H bond breakage, and hydrogenolysis and breakage of C-C and C-Cl bonds [28]. Unsaturated hydrocarbons and corresponding radical species formed as a result of hydrogenolysis undergo further pyrolysis over nickel crystallites. Table 1 summaries the data on carbon yield resulted from catalytic chemical deposition of 1,2- dichloroethane during 2 hours over different industrially manufactured alloys. As seen, among the studied alloys, nichrome (Ni-80%, Cr-20%) occupies the leading position. It allows one to obtain the carbon yield of 67.5 gC/gAl, which surpasses the values for other samples in one order of magnitude. If the resistive heating is applied (Table 1, row #2), the carbon yield over the same type of nichrome decreases in approximately three times, which is connected, as it was mentioned above, with occurrence of parallel processes [29]. The lowest carbon yield (0.5gC/gAl) was observed in the case of stainless steel, thus indicating that 2 hours is not long enough time for such kind of bulk precursor. Click here to view Large Table 1 *gC -weight of carbon product; gAl -weight of alloy sample Besides the industrially manufactured alloys, similar solid solutions of predefined composition can be especially prepared via multi-stage route involving coprecipitation of salt followed by high-temperature reduction in hydrogen, or via single-stage route of mechanical alloying of metal powders in a planetary mill [30-32]. An advantage of the first approach is a guaranteed formation of solid solution with desired ratio of the metals and homogeneous distribution. The formation of solid solutions was confirmed by precise powder X-ray diffraction analysis [33- 38]. Data on carbon yield over such alloys are shown in Table 2. As it follows, the nature and loading of an alloying metal affect noticeably the productivity of bulk precursor towards carbon. Thus, addition of iron worsens the catalytic behavior of the resulted alloy, while molybdenum, oppositely, significantly enhances it. It should be mentioned that these especially prepared alloy samples being subjected to complete self-disintegration process under aggressive medium of 1,2-dichloroethane can also be considered as self-organized catalyst for further usage in decomposition of various organic substrates [39]. Click here to view Large Table 2 *gC–weight of carbon product; gAl–weight of alloy sample. Self-organized catalysts obtained using both types of bulk precursors (industrially manufactured and especially prepared) were found to be quite active and extremely stable in catalytic decomposition of various hydrocarbons and their mixtures (C2H6, C2-C4 mix, C6H6) [40]. Additionally, it was shown that even chlorofluorocarbons can be efficiently decomposed, but in this case introduction of odd hydrogen into reaction feed is of great importance in order to bind the halogen atoms into HF and HCl. Surprisingly, the interaction of CF2Cl2 with submicron Ni crystals formed during the self-disintegration of bulk alloy precursor and fixed within the structure of carbon nanofibers causes their secondary disintegration which leads to formation of unique bimodal carbon nanomaterial. All processes of catalytic chemical vapor deposition with formation of carbon nanofibers described above were considered within a concept of flow-through or ‘open’ systems, when the reagent(s) continuously inlets into the reaction volume and the gas phase products pass the volume away. On the other hand, application of so called ‘closed’ reaction volume system was recently shown to be perspective for synthesis of various nanostructured inorganic materials [41-46]. Regarding the decomposition of substituted hydrocarbons, the process has the same requirements as in the case of ‘open’ system: both halogen and hydrogen source substrates should present in a reaction volume. Thus, for example, the use of halogenated organics (hexafluorobenzene, hexachlorobenzene, 1-bromobutane 1-iodobutane, etc.) together with hexamethylbenzene (as an inner hydrogen source) was shown to initialize the metal dusting process of bulk NiCr alloy with formation of nanostructured product [46]. Depending on the nature of halogen-containing substrate, the starting temperature of active particles formation detected by means of a ferromagnetic resonance spectrometry was different. The approach additionally provides a possibility to study the metastable reaction intermediates, which is inaccessible in the flow-through regime. Go to Conclusion Preparation of the catalysts for various catalytic processes remains to be a challenge task. At the same time, creation of the appropriate, in most cases aggressive, conditions for the catalyst’s precursor might shift the system towards state of self-organization. One of the most illustrative examples of this phenomenon is a nickel-based catalytic system for chemical vapor deposition of halogen-substituted hydrocarbons resulting in formation of nanostructured carbon fibers. Conventionally used for this process Ni-containing catalysts supported on oxide or carbonaceous supports are known to be rapidly deactivated under the reaction conditions. Oppositely, bulk metal alloys subjected to interaction with aggressive halogencontaining medium were shown to undergo the metal dusting process, which ends with complete wastage of initial bulk item. The dispersed metal particles formed as a result of such selfdisintegration were found to be quite stable and extremely active in decomposition of any other substituted and unsubstituted hydrocarbons that allows one to consider them as self-organized catalysts. The main regularities of the process are similar for the cases of external and direct (resistive) heating of the bulk alloy precursor, and if compare ‘open’ reaction volume systems with ‘closed’ one. For more Open Access Journals in Juniper Publishers please click on: https://juniperpublishers.com/ for more details click on the juniper publishers material scienc