Shortening Lifetime Research Articles

Sulfur poisoning of La(Ni0.6Fe0.4)O3 cathode material for solid oxide fuel cells

Sulfur poisoning of cathode materials is one of the important factors to cause cathode performance degradation resulting in shortening lifetime of SOFC. The sulfur attacks alkali earth components of the rare earth-transition metal perovskite oxides, such as Ba, Ca, Sr, which reacts with SO2 to form sulfates. In this work, the La(Ni0.6Fe0.4)O3 (LNF) cathode material without alkali earth elements was employed to investigate the sulfur poisoning behavior by flowing 30 ppm SO2 at different temperatures of 500 °C–800 °C. It was found that SO2 readily reacts with the La2O3 component in LNF to form La2O2SO4 at 700 °C and 800 °C. The extent of the chemical reaction is temperature dependent. These results confirm that sulfur poisoning also occurs in cathode materials free of alkali earth components. The study prompts the exploration of new materials and new strategies for the developing new cathode materials with high sulfur tolerance.

Framework for the Life Cycle Assessment of non-permanent process units in volatile chemical recycling process chains

To handle the rising amount of plastic waste in the environment, new technologies are necessary to recover the value of this resource. Chemical recycling is one option to treat mixed and multi-layer plastic waste streams. Emerging technologies works e.g. with pyrolysis (via thermal or catalytic cracking) of the plastic waste streams and results in multi-material output streams. Membranes are a widely adopted and a relevant technology for bulk separations, within chemical recycling operations. Based on a different separation principle, they need less thermal energy than e.g. distillation columns. However, when it comes to their contribution to the environmental impact of the whole process chain, membranes need special attention. Compared to installed process units, such as pyrolysis and catalytic upgrading reactors, membranes have a shortened life time (non-permanent) compared to the whole process chain and need extra treatments to avoid fouling and maintain their efficiency. These points make it challenging to integrate a LCA model representing membranes within the whole LCA process model. In this paper a framework for the LCA of membranes will be presented regarding their impact in a chemical recycling process and how a shortened life time model can be integrated into a longer life LCA process model with focus on the handling of the different time scales.

Improvement in stability of PtRu electrocatalyst by carbonization of in-situ polymerized polyaniline

As well known, ruthenium is electrochemically unstable in direct methanol fuel cell (DMFC) operation shortening lifetime and deteriorating performance of DMFC device. In this work, a facile methodology for improvement in stability of PtRu electrocatalyst is described, in which PtRu alloyed nanoparticles are decorated by nitrogen-doped carbon (NxC) originating from the carburization of in-situ polymerized polyaniline (PANI). Deceleration in Ru dissolution of NxC protected PtRu electrocatalyst comes from the ionized Ru atoms induced by the carburization of PANI transferring electrons from Ru to nitrogen atoms evidenced by XPS measurement, which results in higher CO tolerance during potential sweeping from 0.6 to 1.0 V versus RHE for NxC decorated PtRu electrocatalyst. Meanwhile, NxC protected PtRu electrocatalyst only losses 10% of active sites after stability estimation; in contrast, 50% of active sites are lost for bare PtRu electrocatalyst. Moreover, fuel cell test illustrates that NxC protected PtRu electrocatalyst shows comparable performance to bare PtRu electrocatalyst.

Exploring technology opportunities by visualizing patent information based on generative topographic mapping and link prediction

The shortening lifetime of technology requires companies to make intensive efforts to continuously explore new technology. Although many researchers have proposed visualization methods to find technology opportunities, little attention has been paid to present detailed directions of technology development with specified characteristics of technology. Thus, this research aims to suggest a systematic approach to conducting technology opportunity analysis by visualizing patent information, such as patent documents and citation relationships. First, keywords that explain core concepts, functions, and so on are extracted from collected patent documents by text mining. Second, patents are visualized in a two-dimensional space, and vacant cells are identified with their estimated keyword vectors by generative topographic mapping (GTM). Third, since many vacant cells will be potential candidates for developing new technologies, link prediction tools can choose promising vacant cells to connect existing cells with potential, but not yet existent, cells. Finally, the results of prediction are tested by comparing the predicted cells with the actual developed cells. The research reported in this paper is based in three technologies that have emerging, stable, and declining patterns, in order to illustrate the proposed approach, and investigate in which types it is relevant. It is found that the proposed approach provided a good prediction performance in the case of a technology that has a stable pattern. In addition, among link prediction methods, a semantic similarity-based approach showed better prediction results than a machine learning technique due to modest data availability for training. Thus, the results of this research can help R&D managers plan and evaluate R&D projects for technology development.

Analysis of The Causes the Degradation of Part Steam Generator by Using Microscopy Methods

Degradation of technical objects is a natural phenomenon, but for users of these objects brings many problems. These problems are manifested by shortening lifetime, lowering safety and increasing costs for the technical operation of technical objects. This article analyzes the causes of degradation of parts steam generator using methods of microscopy. Degradation processes that occur most frequently in parts of steam generators are creep, corrosion and wear. The degradation occurred on the tube of convection superheater from steel CSN 41 5128. It was found that the inner surface was covered with corrosion products and was disrupted its cohesion. For search of the causes of degradation were used spectral analysis, microscopic analysis and determination of the weight of oxide layers according to CSN ISO 8407. Based on the results of analyzes, it was found that the occurrence of degradation is related both microstructure of pipes which did not comply with the required state and also with non-standard environment, which was exposed the inner pipe surface.

고분자 복합재료의 표면 친수화 및 소수화 메커니즘 해석

고분자 절연재료는 기존의 세라믹 절연재료에 대체되는 물질로 매년 수요가 꾸준히 급증하고 있다. 그러나, 실용에 있어 장시간 외부로부터 가해지는 열화인자에 노출됨에 따라 경시적 성능저하 및 수명단축이 발생되고, 이를 근본적으로 해결하기 위한 고분자 열화메커니즘의 규명이 안전성 향상 및 신뢰성 확보를 위해 중요한 과제로 대두되고 있다. 본 연구는 이러한 열화발생 및 진행경로를 해석하기 위한 일환으로 열, 수분에 의한 열화를 각각 임의로 모의하여, 열화 발생메커니즘을 해석하였다. 특히, 본 연구에서는 화학적 측면의 특성분석을 수행하였고, 이를 통해 표면의 친수 소수적 분자구조 분석으로 최종적인 표면열화 모델링을 도출하였다. PCB 기판용 고분자 복합재료를 대상으로 열, 수분 가속열화에 따른 표면에서의 접촉각, XPS 분석을 통해 표면의 변화 메커니즘을 분석하였다. 친수화 경향을 나타내는 표면은 접촉각의 감소와 carboxyl(<TEX>$-COO^*$</TEX>) 라디칼이 다량 발생하였으며, 소수화 경향을 나타내는 표면은 접촉각의 증가와 표면에서 산소기의 이탈과 탄소결합의 불포화 이중결합화로 안정된 화학구조를 구성하고 있었다. The polymer insulators have been extensively used as an alternate material of ceramic insulators. However, when they are used in practical conditions, there are many problems of decreasing performance and shortening lifetime due to the exposures of degradation factors applied from the outdoor situations. Accordingly, the analysis of polymer degradations has been getting influential too late as one of important subjects for improvements of safety and reliability. Heat, water treatments are arbitrary simulated for finding out the initiations and processes of surface degradation on the polymer surface. Especially, this study is focused on the chemical changes properties. From the analysis of hydrophilic and hydrophobic molecular structures, final modeling of surface degradation is accomplished. We checked the contact angle depending on heat and moisturized accelerated degradation and ran an XPS analysis to check the mechanism change of the surface of the PCB polymer composite. The surface that had a tendency to attract moisture showed a decrease in the contact angle and generated a large amount of carboxyl(<TEX>$-COO^*$</TEX>) radicals. The hydrophobized surface showed an increase in the contact angle and had a stable chemical composition constituted of the breakaway of oxygen radicals and the formation of double bond by carburization.

Highly efficient 154 μm emission in Zr/Yb/Er-codoped LiNbO_3 crystal

Codoping with Zr(4+) ions enhances the 1.54 μm emission in Yb/Er:LiNbO(3) crystal by about three times. Optical damage resistant Zr(4+) ion increases the maximum phonon energy of Er:LiNbO(3) host, which is favorable for the nonradiative relaxation from (4)I(11/2) to (4)I(13/2) state (Er). The time decay spectra show that the incorporation of Zr(4+) ions leads to a shortening lifetime of (4)I(11/2) state (Er), increasing the nonradiative relaxation rate of (4)I(11/2)→(4)I(13/2) (Er) in Yb/Er:LiNbO(3). The 1.54 μm emission enhancement is important to telecommunication application.

Raman investigation of silicon nanocrystals: quantum confinement and laser‐induced thermal effects

We present a detailed experimental and theoretical Raman investigation of quantum confinement and laser‐induced local thermal effects on hydrogenated nanocrystalline silicon with different nanocrystal sizes (3.6–6.2 nm). The local temperature was monitored by measuring the Stokes/anti‐Stokes peak ratio with the laser power density range from ~120 to 960 kW/cm2. In combination with the three‐dimensional phonon confinement model and the anharmonic effect, which incorporates the three‐phonon and four‐phonon decay processes, we revealed an asymmetrical decay process with wavenumbers ~170 and 350 cm–1, an increasing anharmonic effect with nanocrystal sizes, and a shortening lifetime with enhanced temperature and decreasing nanocrystal dimension. Furthermore, we demonstrated experimentally that for Si nanocrystals smaller than 6 nm, the quantum confinement effect is dominant for the peak shift and line broadening. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Excellent Brightness with Shortening Lifetime of Textured Zn2SiO4:Mn2+ Phosphor Films on Quartz Glass

Green-emissive textured Zn2SiO4:Mn2+ phosphor films were fabricated by the thermal diffusion of ZnO:Mn on quartz glass. The Zn2SiO4:Mn2+ phosphor films became textured along several hexagonal directions and their chemical composition was continuously graded at the interface. The decay time of Mn2+ was as short as 4.4 ms, and the optical transition probability of the films defined as the inverse of decay time showed a strong correlation with film texture degree as a function of annealing temperature. The brightest Zn2SiO4:Mn2+ film showed a photoluminescent brightness as high as 65% compared with a commercial Zn2SiO4:Mn2+ phosphor powder screen and a maximum absolute transparency of 70%. These excellent optical properties are explained by the combination of the unique textured structure and continuous grading of the Zn2SiO4:Mn2+ chemical composition at the interface.

Dephosphorylation of Dynamin1 is a Ca2+ Sensor that Triggers Clathrin- Independent Vesicle Recycling Processes in Pancreatic Beta Cells

By tagging fluorphores to different endocytic proteins such as clathrin and dynamin, clathrin-mediated receptor internalization process has been visualized in a number of non-excitable cells in vivo using total internal reflection fluorescence microscopy. In contrast, systematic examination of the tempo-spatial relationship between different exocytotic and endocytic proteins has not been done in excitable cells. The clathrin-dependent receptor endocytosis in non-excitable cells has a long life time. In contrast, the clathrin-dependent vesicle recycling process is faster and subjected to further acceleration by increase in cytoplasmic Ca2+ concentration ([Ca2+]i), as proved by our previous data in pancreatic beta cells and also by recently papers on Calyx neurons. Moreover, elevated [Ca2+]i triggers and accelerates a type of clathrin-independent but dynamin-dependent endocytosis in beta cells. As dynamin1 is a neuronal specific subtype of dynamin that can be dephorsphorylated at S774 and S778 positions upon stimulation-induced Ca2+ influx, we test whether it acts as a signal molecule to sensor increase in [Ca2+]i and act to trigger vesicle recycling processes in our insulin-secreting cells. By mutating the S774 and S778 into A and E, we can mimic dephorsphorylated and phorsphorylated status of dynamin1. We show that dephorsphorylated dynamin1 has a statistically shortened life time as compared to the life times of dynamin1 in cells expressed wide-type dynamin1 or dynamin1 S774ES778E mutant. Moreover, dynamin1 S774AS778A is more likely to be recruited to the vesicle fusion sites, which represent clathrin-independent but dynamin-dependent endoytic events in beta cells. In the end, the fast capacitance decay evoked by homogenous elevation in [Ca2+]i induced by flash-photolysis is selective inhibited by expressing either dynamin1 mutants in INS-1 cells, further reinforce the important role of dynamin1 phorsphorylation-dephorphosphorylation cycle in clathrin-independent vesicle retrieval process.

Microstrain and Defects in Polycrystalline Zn1-xMgxO (0 ¡? x ¡? 0.15) Studied by X-ray Diffraction and Optical and Raman Spectroscopies

The properties of polycrystalline wurtzite Zn_{1-x}Mg_{x}O (0 <= x <= 0.15) have been studied, by powder X-ray diffraction, including an analysis of the X-ray line-broadening, and by luminescence, absorption, and Raman spectroscopies. We have previously established from synchrotron X-ray difffraction that with increasing Mg-concentration, the c-axis compresses, and the off-center cation displacement within each tetrahedral (Zn,Mg)O_{4} unit decreases. Here we perform a size-strain line-broadening analysis of the XRD peaks, which reveals that the Mg-substitution reduces the coherent crystallite size and also develops the lattice microstrain. The optical properties of the samples have been characterized by diffuse-reflectance spectroscopy and fluorimetry. Both the optical band gap and the band-edge emission energies gradually increase with the Mg-concentration in Zn_{1-x}Mg_{x}O. The Mg-substituted samples show broader band tails near the absorption edge, due to the increase of crystal imperfections. The peak broadening of the E_{2}{high} Raman mode, upon the Mg-substitution, is also ascribed to the phonon shortening lifetime mechanism via crystal defects.

Investigation of surface treatment effect of catalyst on the lifetime for Cat-CVD method

In case of amorphous silicon (a-Si) film deposition by catalytic chemical vapor deposition (Cat-CVD) method, a metal catalyzing wire is converted to silicide and this silicidation causes shortening lifetime of the catalyzing wire. In the present work, the effect of surface carbonization of catalyzing wire against silicide formation is investigated to obtain long-life catalyzer. Characteristics of a-Si film deposited by carbonized tungsten (W) catalyzer are also investigated. Silicide layer thickness formed on carbonized catalyzing wires after 60min a-Si film deposition decreases to half of that on uncarbonized wires. Device quality a-Si films having defect density less than 4×1015cm−3 are obtained by using carbonized W, indicating that surface carbonization of W catalyzer is effective process for industrial application of Cat-CVD method.

HGAL - A Germinal Center-Like Diffuse Large B-Cell Lymphoma Prognostic Biomarker Interacts with the Cytoskeleton and Influences Cell Migration.

Gene expression profiling studies of lymphoid malignancies have led to the discovery of previously unrecognized lymphoma subtypes and associated novel genes. We recently cloned a germinal center (GC) specific gene - human germinal center-associated lymphoma (HGAL), whose expression correlates with survival in patients with diffuse large B-cell lymphoma (DLBCL) and classical Hodgkin lymphoma (HL). HGAL protein contains an ITAM motif and harbors 6 tyrosines that may be potentially phosphorylated. Mice deficient in the HGAL homologue M17 form normal GCs with the exception of reduced-sized Peyer's patches, undergo efficient class-switch recombination and somatic hypermutation, and mount T-cell-dependent antibody responses similar to wild-type controls (Schenten et al., Blood 2006). The biological functions of HGAL in normal GC lymphocytes and lymphoma are unknown. Herein we demonstrate that HGAL plays a role in regulation of cell migration. Ex-vivo exposure of lymphoma or HGAL-transfected HeLa cell-lines to pervanadate resulted in tyrosine phosphorylation of HGAL protein. Stimulation of lymphoma and HGAL-transfected HeLa cell-lines with interleukin (IL)-6 led to transient HGAL tyrosine phosphorylation, peaking at 5–15 minutes. The phosphorylated HGAL had a markedly shortened life time compared to the unphosphorylated protein. No HGAL tyrosine phosphorylation was observed upon stimulation with anti IgM, interferon-g or IL-4. Deletion of the two C-terminal ITAM tyrosines in a truncated HGAL mutant (amino-acids 1-118) totally abrogated HGAL tyrosine phosphorylation upon IL-6 stimulation or exposure to pervanadate. Immunofluorescence and confocal miscroscopic studies of the SUDHL6 lymphoma and transfected HeLa cell-lines demonstrated HGAL redistribution from mainly perinuclear cytoplasmic localization to podosomes and spike-like filopodia. The time-frame of the HGAL relocalization was similar to that of HGAL tyrosine phosphorylation, being most prominent at 5 and 10 minutes in the SUDHL6 and transfected HeLa cells, respectively. Immunofluorescence studies demonstrated HGAL colocalization with actin, myosin and WASP proteins. HGAL immunoprecipitation studies followed by MAS spectroscopy or Western blotting confirmed HGAL interaction with actin and myosin type 2, but not with WASP protein. The N terminal portion of HGAL protein (aa 1-118) was sufficient for these interactions, however HGAL phosphorylation at its C-terminal tyrosines increased and extended the duration of its interaction with the myosin type 2.We further assessed the effects of HGAL on cell migration. Upon IL-6 stimulation for 24 hours, the migration of the Neo-HeLa cells in wound assay was markedly increased. However this effect of IL-6 was significantly ameliorated in the HGAL-HeLa cells. Moreover, siRNA knockdown of the HGAL in the HGAL-HeLa cells markedly reversed the HGAL-induced inhibition of IL-6 stimulated cell migration. This IL-6 effect on HGAL-HeLa and control Neo-HeLa cells was not attributable to differences in cell proliferation. Collectively, our results suggest that HGAL is involved in negative regulation of lymphocyte migration, thus constraining lymphocytes to the GC. Furthermore, inhibition of lymphocyte migration might contribute to the less aggressive clinical behavior of HGAL expressing DLBCL and HL tumors.

Full-color Ba 3MgSi 2O 8:Eu 2+, Mn 2+ phosphors for white-light-emitting diodes

The Ba 3MgSi 2O 8:Eu 2+, Mn 2+ phosphors show three emission colors: blue band of 440 nm, green band of 505 nm and red band of 620 nm. The emission colors are tuned through concentration variation of luminescent centers in Ba 3MgSi 2O 8: mEu 2+, nMn 2+ phosphors. The white light color tuning is originated from the energy transfer among luminescent centers. The energy transfer is confirmed through the shortening lifetime of energy donor. Our full-color-emitting and color-tunable phosphors can be used in the application of white-light-emitting diode by the UV LED/phosphor technology.

Dispersion and chemical evolution of ship plumes in the marine boundary layer: Investigation of O3/NOy/HOx chemistry

The dispersion and chemical evolution of NOx in ship plumes has been investigated for marine boundary layer (MBL) conditions. This effort has involved combining a plume dispersion algorithm with a time‐dependent photochemical box model. The analysis has considered several factors, all of which can influence the net impact of NOx on the background environment. These include the following: season of the year, latitude of point of release, meteorological setting, and ship NOx emission rate. Reaction rates within a plume were shown to be a nonlinear function of the levels of NOx, leading to relative estimates of ship plume NOx lifetimes that were factors of 2.5–10 times shorter than for ambient marine conditions. The shortened ship‐plume NOx lifetime reflects both elevated daytime levels of OH and nighttime levels of NO3 and N2O5, all of which were estimated to be several times larger than those typical of ambient marine conditions. During daylight hours, elevated ship plume OH resulted in the net photochemical production of O3, with peak concentrations being 5–65% higher than background values, depending on latitude. The areal integrated O3 effect, however, is estimated to be quite small due to further plume dilution. In addition, because of the shorter estimated lifetime for NOx, it would seem reasonable that the integrated O3 production from the current Lagrangian modeling effort would be significantly lower than that predicted by global 3‐D grid models. The current predicted shortened lifetime for NOx is quite significant in terms of assessing a ship plume's impact on background marine levels of NOx. In fact, these results would seem to explain a significant fraction of the overprediction of NOx levels in and near shipping lanes recently estimated using 3‐D Eulerian global models.

Influence of current rate onto a lead-acid cell performance in photovoltaic applications

Stratification created during charge-discharge cycling in stationary lead-acid batteries supposes serious drawbacks to the system, affecting the performance, reducing the cycle efficiency and shortening lifetime. This phenomenon appears in both charge and discharge half-cycle, but it is much more important in the former. Several methods have been traditionally used to overcome this problem, especially in stand-alone installations and photovoltaic power plants. In this work the concentration gradient dependence on current rate has been studied as well as its influence on general lead-acid cell performance.

A Study of Proof Testing

Proof test is useful for rejecting ceramics of undesirable short life time. But the crack in the proof test survivors propagates in the unloading period of the proof stress. So the shortest life time of the survivors may be shorter than the needed life time. In this paper, the influence of unloading time on the shortening of the life time of the proof test survivors was studied on the basis of fracture mechanics of ceramics. Some formulae are derived for expressing the shortened life time of the survivor during unloading, the ratio of the shortened life time to the needed one, and the longest unloading time allowable to make the shortest life time of the survivors longer than the needed one. According to these formulae, the unloading time gives substantial influence on the life time of the survivors from the point of view of the shortening effect for the life time. The formulae expressing the ratio of shortened life time to the needed one tells that the unloading time must be of the order of 10μs to make the shortest life time negligibly small compared with the needed one, when the proof stress is selected so as to be the value which corresponds to the needed life time. In an actual application of proof test to ceramics, some safety factor is multiplied to the proof stress, so the safety factor is studied in correlation with the unloading time. According to the study, the unloading time can be increased in proportion to Δp/(1+Δp)2, where (1+Δp) is the safety factor. Then, the unloading time reaches the maximum at the value of 2, in an approximation. But even when 2 is selected as the safety factor, the unloading time must be of the order of 5-10μs to make the shortest life time of the survivors equal to or longer than the needed value. Such a short unloading time seems to be inapplicable to the test. Therefore, it can be concluded that the complete elimination of the ceramics having undesirable short life time needs another complementary method such as AE monitoring for proof test.