bluuebunny/crossref_metadata_2025 huggingface dataset:
CHARACTERISTICS OF USDA UTILITY COW BEEF SUBJECTED TO BLADE TENDERIZATION AND HYDRODYNAMIC SHOCK WAVES
Authors: SCHILLING M. W. , MARRIOTT N. G. , WANG H. , SOLOMON M. B.
Published: May 2007

Longissirnus lumbonun samples were removed 24 h postmortem from six U.S. Utility carcasses to be utilized in determining the effects of tenderness enhancement methods and aging time on quality attributes of beg. Within each sample, sections were randomly assigned to hydrodynamic shock waves (HSW). blade tenderization (BT), a combination of BT and HSW (HSBT). or no treatment (C). Steaks within each treatment (excluding HSW) were aged for 7 and 14 days. Sensory evaluation included subjective ratings for myofibrillar tenderness, connective tissue amount, and overall tenderness. Objective measurements included thaw and cooking losses, shear force, and standard plate count. HSW and HSBT were effective in decreasing (P<0.05) Warner‐Bratzler peak force, total energy, and standard plate count. However, aging time (14 days) was more effective (P<0.05) in decreasing peak force shear values than BT, HSW, or HSBT. Sensory values, thaw and cooking losses were not affected (P>0.05) by any treatments.
BREAKDOWN OF LARGE PROTEOGLYCANS IN BOVINE INTRAMUSCULAR CONNECTNE TISSUE EARLY POSTMORTEM
Authors: HANNESSON KIRSTEN O. , PEDERSEN MONA E. , OFSTAD RAGNI , KOLSET SVEIN O.
Published: May 2007

In the present study, a decomposition of intramuscular connective tissue in beef early postmortem was demonstrated by comparing samples from M. longissimus dorsi (LO) collected immediately after slaughter and after 24 h and 48 h storage by histological and biochemical methods. The histological study showed a widening of the endomysial sheaths after storage. For fiactionation of proteoglycans, extraction in 4M guanidine‐HCl added protease inhibitors, CsCl, gradient ultracentrifugation and gel chromatography were used. Gel chromatography demonstrated that the proteoglycan preparation was broken into fragments of lower molecular weight. Cellulose acetate electrophoresis and dot blot analysis identified the components involved as hyaluronic acid (HA) and a large proteoglycan (PGL) immunologically related to aggrecan from sclera. SDS polyacrylamide gel electrophoresis (SDS‐PAGE) confirmed depolymerization of the high molecular weight components, and a large component of molecular weight above 220 KDa with glycosaminoglycan (GAG) staining properties was not visible in the gel after storage.
ANTIMICROBIAL AND ANTIOXIDANT ACTIVITIES OF CORN GLUTEN MEAL SUBSTANCES IN AN EMULSIFIED MEAT MODEL SYSTEM
Authors: HOMCO‐RYAN C. L. , RYAN K. J. , WICKLUND S. E. , BREWER M. S.
Published: May 2007

Corn gluten meal (CGM) and pH adjusted (6.6)/particle size‐reduced (∼7μm‐MC7; ∼38μm‐MC38) CGM increased oxidative and microbiological shelf‐life of a model emulsified meat system. After 14 days, TBARS were significantly lower for samples containing MC7 and MC38 when compared to controls, and samples containing soy protein isolate (SPI) or native CGM. Based on aerobic plate counts, MC38 and CGM increased product shelf‐life by ∼7days compared to SPI‐ and MC7‐containing products and controls. These results suggest that the use of corn gluten meal substances in an emulsified meat product could create a more shelf stable product. These functional characteristics may make the incorporation of corn gluten meal into foods more feasible.
Development of aggregation inhibitors for amyloid‐β peptides and their evaluation by quartz‐crystal microbalance
Authors: Okuno Hiroaki , Mori Kanae , Okada Tomoko , Yokoyama Yuusaku , Suzuki Hideharu
Published: May 2007

A series of amyloid‐β aggregation inhibitors composed of a molecular recognition element (KLVFF) and an aggregation‐disrupting part (having an electrostatic and hydrophilic nature) based on amino acid analogs have been synthesized. A quartz‐crystal microbalance (QCM) method was applied and found to be very successful in evaluating the inhibitory activity of the Aβ aggregation, which was observed when the frequency was increased. The QCM can detect a mass change with differences in frequency that correspond to a 1 Hz frequency decrease per 30 pg mass increase on a 4.9 mm2 electrode. Furthermore, bioassay results showed no toxicity of the inhibitor itself against IMR‐32 neuroblastoma cells, and remarkably reduced cytotoxicities of both Aβ1–40 and Aβ1–42 were exhibited in the presence of these inhibitors. The KLVFF‐(EEX)3 derivative was the most efficient Aβ aggregation among the inhibitors examined here.
On the value of formal assessment of uncertainty in regulatory analysis
Authors: Jaffe Judson , Stavins Robert N.
Published: May 2007

The US Office of Management and Budget introduced in 2003 a new requirement for the treatment of uncertainty in Regulatory Impact Analyses (RIAs) of proposed regulations, requiring agencies to carry out a formal quantitative uncertainty assessment regarding a regulation’s benefits and costs if either is expected to reach $1 billion annually. Despite previous use in other contexts, such formal assessments of uncertainty have rarely been employed in RIAs or other regulatory analyses. We describe how formal quantitative assessments of uncertainty – in particular, Monte Carlo analyses – can be conducted, we examine the challenges and limitations of such analyses in the context of RIAs, and we assess how the resulting information can affect the evaluation of regulations. For illustrative purposes, we compare Monte Carlo analysis with methods typically used in RIAs to evaluate uncertainty in the context of economic analyses carried out for the US Environmental Protection Agency’s Nonroad Diesel Rule, which became effective in 2004.
Compensatory Growth of Pond‐reared Hybrid Striped Bass, Morone chrysops × Morone saxatilis, Fingerlings
Authors: Turano Marc J. , Borski Russell J. , Daniels Harry V.
Published: May 2007

Compensatory growth (CG) or “catch‐up growth” is a period of super‐accelerated growth following a period of suboptimal conditions (i.e., lack of prey availability or overwintering). Little is known about the CG response in pond‐raised fish and whether hybrid striped bass (HSB), Morone chrysops × Morone saxatilis, might exhibit the rapid growth states or improvements in other production characteristics that may accompany the response. To evaluate the potential for CG in HSB culture, a 16‐wk growth trial in twelve 0.1‐ha earthen ponds was conducted. Approximately 2850 fish (mean weight ± SD = 3.2 g ± 1.1) were stocked into ponds and subjected to one of four cyclic feeding regimens. Treatment regimens included a control (0 wk, fed twice daily to apparent satiation) and cycles of 1, 2, or 4 wk of feed deprivation, followed by 1, 2, or 4 wk of feeding to apparent satiation. Fish in the 4‐wk feeding regimen were offered feed twice during the feed‐deprivation period (once every other week). Growth, specific growth rate (SGR), hepatosomatic index (HSI), intraperitoneal fat ratio, and condition factor (CF) were measured every other week, while overall growth, feed efficiency (FE) (FE = [weight gain/feed fed] × 100), and survival were calculated at the trial termination. The effect of these feeding regimens on water quality was examined by monitoring pH, turbidity, total ammonia nitrogen, nitrite–nitrogen, nitrate–nitrogen, soluble reactive phosphorus, and chlorophyll a weekly; total nitrogen and phosphorous biweekly; and dissolved oxygen and temperature twice daily. Cyclic feeding elicited CG; fish subjected to the 2‐wk regimen had a significantly higher SGR than 0‐wk controls during all but the final refeeding period. FE was higher for all fish in the cyclic regimens, although only FE for fish in the 2‐wk regimen was statistically greater (40%) than the controls. HSI was the most responsive measure and significantly decreased in the 2‐ and 4‐wk treatments during feed‐deprivation period and overcompensated during the refeeding period. CF also varied with feeding cycle and proved to be an effective nonlethal measure of predicting a CG response. No statistical differences in water quality parameters were observed. These data suggest that CG can be effectively induced in pond‐raised HSB and that the increase in FE warrants further research for practical application. Future pond studies with fingerling HSB fish should be conducted with emphasis on feed‐deprivation periods of 2 wk and refeeding periods of at least twice that of the feed‐deprivation period.
Modeling of Rotary Screw Fluid Dispensing Processes
Authors: Chen X. B.
Published: May 2007

Fluid dispensing is a process widely used in electronics packaging manufacturing, by which fluid materials are delivered in a controlled manner for the purpose of bonding, sealing, coating, or conducting. Among various dispensing approaches, the use of a motor-driven screw is recognized as one of the most promising approaches due to its capacity of achieving high flow rates without the need of refilling. In a dispensing process, the flow rate of fluid dispensed is critical to control the volume or amount of fluid dispensed. This paper presents the development of a model for the rotary screw dispensing process. By using the power law equation, the flow behavior of the fluid being dispensed is characterized and then, based on the fundamentals of flow in screw channels and circular tubes, a model is developed to represent the flow rate in the rotary screw dispensing process. Experiments and simulations were carried out to verify the model effectiveness as well as to investigate the performance of the rotary screw dispensing process.
Comment on "Dispersal Limitations Matter for Microbial Morphospecies"
Authors: Pither Jason
Published: May 2007

Telford
et al
. (Brevia, 19 May 2006, p. 1015) reported that freshwater diatoms exhibit regional-scale richness-pH relationships that depend substantially on regional habitat availability. On this basis, the authors argued that, despite their microscopic size, diatoms are not ubiquitously dispersed. Here, I describe my demonstration that their primary evidence against the ubiquitous dispersal hypothesis is spurious.
The Catalytic Cross-Coupling of Unactivated Arenes
Authors: Stuart David R. , Fagnou Keith
Published: May 2007

The industrially important coupling of aromatic compounds has generally required differential prefunctionalization of the arene coupling partners with a halide and an electropositive group. Here we report that palladium, in conjunction with a copper oxidant, can catalyze the cross-coupling of
N
-acetylindoles and benzenes in high yield and high regioselectivity across a range of indoles without recourse to activating groups. These reactions are completely selective for arene cross-coupling, with no products arising from indole or benzene homo-coupling detected by spectroscopic analysis. This efficient reactivity should be useful in the design of other oxidative arene cross-couplings as well.
trans-Bis[1,3-bis(2,4,6-trimethylphenyl)imidazolidin-2-ylidene]dichloronickel(II): Synthesis and Structure
Authors: Kozioł Andrzej , Pasynkiewicz Stanisław , Pietrzykowski Antoni , Jerzykiewicz Lucjan B.
Published: May 2007

trans-Bis[1,3-bis(2,4,6-trimethylphenyl)imidazolidin-2-ylidene]dichloronickel(II), [NiCl2(SIMes)2], was synthesized in a one-pot reaction of fluorenyllithium with nickel(II) bromide followed by the addition of 1,3-bis(2,4,6-trimethylphenyl)imidazolidinium chloride. Labile difluorenyl- nickel, formed in the course of the reaction, behaves differently than nickelocene and indenocene in analogous reactions. It exchanges both fluorenyl ligands giving the title compound. The crystal and molecular structure of this compound have been determined by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic crystal system with square-planar geometry around the central nickel atom.
Routine antenatal HIV testing: the responses and perceptions of pregnant women and the viability of informed consent. A qualitative study: Table 1
Authors: de Zulueta Paquita , Boulton Mary
Published: May 2007

This qualitative cross-sectional survey, undertaken in the antenatal booking clinics of a hospital in central London, explores pregnant women’s responses to routine HIV testing, examines their reasons for declining or accepting the test, and assesses how far their responses fulfil standard criteria for informed consent. Of the 32 women interviewed, only 10 participants were prepared for HIV testing at their booking interview. None of the women viewed themselves as being particularly at risk for HIV infection. The minority (n = 6) of the participants who declined testing differed from those who accepted, by interpreting test acceptance as risky behaviour, privileging the negative outcomes of HIV positivity and expressing an inability to cope with these, should they occur. Troublingly, only a minority of women (n = 9) had a broad understanding of the rationale for the test, and none fulfilled the standard criteria for informed consent. This study suggests that, although routine screening combined with professional recommendation may be successful in increasing uptake, this may be at the cost of eroding informed consent. Protecting third parties (notably fetuses) from a preventable disease may outweigh the moral duty of respecting autonomy, enshrined in Western bioethical tradition. Nevertheless, such a policy should be made transparent, debated in the public domain and negotiated with women seeking antenatal care.
Scientists, bioethics and democracy: the Italian case and its meanings
Authors: Corbellini Gilberto
Published: May 2007

In June 2005, Italy held a referendum on repealing the law on medically assisted fertilization (Law 40/2004), which limits access to artificial reproduction to infertile couples, and prohibits the donation of gametes, the cryopreservation of embryos, preimplantation genetic diagnosis (PDG), and research on human embryos. The referendum was invalidated, and the law remained unchanged. The Italian political e bioethical debate on assisted reproduction was manipulated by the Catholic Church, which distorted scientific data and issues at stake with the help of Catholic politicians and bioethicists. What happened in Italy shows that some perverse socio-cultural e political mechanisms are spreading the absurd and anti-historical view that scientific and technological advancements are threatening democracy and personal freedom. Scientists should not only contrast the political attempts at limiting freedom of scientific research, but also tell politicians, humanists and citizens that the invention of Western science with its view of scientific community as an “open society”, contributed and still contributes, through scientific education, to the construction and maintaining of the moral and political values underlying Western democracies.
Trace element profiles as unique identifiers of western sandpiper (Calidris mauri) populations
Authors: Norris D.R. , Lank D.B. , Pither J. , Chipley D. , Ydenberg R.C. , Kyser T.K.
Published: May 2007

Understanding the ecology and evolution of migratory animals requires information on how populations are geographically linked between periods of the annual cycle. To examine whether trace elements could be used to track migratory birds, we analyzed concentrations of 42 trace elements in feathers of western sandpipers ( Calidris mauri (Cabanis, 1857)) that were grown at five different wintering sites ranging from San Francisco Bay (USA) to the Bay of Panama. Linear discriminant analysis of 15 elements correctly classified all 26 individuals to their wintering sites, including two sites that were separated by less than 3 km. A randomization procedure confirmed the robustness of these findings. Our analysis suggests that trace elements can be used to assign individuals to specific sites of origin. Although we did not sample feathers from all wintering areas, the regions our sites represented comprised a significant percentage of the global population. However, since trace element profiles appear to be highly specific to geographic sites, we suggest that this technique is best suited for cases where samples can be obtained from the majority of populations throughout a species range. Thus, under certain circumstances, trace element profiles may provide the potential to identify populations with a high degree of spatial accuracy.
Do warning displays predict striking behavior in a viperid snake, the cottonmouth (Agkistrodon piscivorus)?
Authors: Glaudas Xavier , Winne Christopher T.
Published: May 2007

Warning displays are defined as signals designed to intimidate predators or indicate a proclivity to fight. However, support for the idea that warning behaviors signal an intent to fight is largely based on anecdotes and isolated observations, and a complete understanding of antipredator behavior will only be achieved if specific hypotheses are experimentally tested. Herein, we tested in a North American viperid snake, the cottonmouth ( Agkistrodon piscivorus (Lacépède, 1789)), the hypothesis that warning displays serve as a reliable signal to potential predators that a snake will strike. The cottonmouth exhibits two stereotypical warning displays during predator confrontation, i.e., mouth gaping and tail vibrations, making it an ideal study organism to experimentally test the relationship between warning displays and defensive striking. To test this idea, we recorded the sequence of defensive behavior — gaping, tail vibrating, and striking — of cottonmouths towards a standardized predatory stimulus in the laboratory. As predicted, snakes that gaped during the trials were subsequently more likely to strike than snakes that did not. In contrast, striking behavior was independent of the occurrence of tail vibrations. Our results suggest that gaping behavior — but not tail-vibrating behavior — may provide an honest signal to would-be predators.
Winter selection of roost sites by ruffed grouse during daytime in mixed nordic-temperate forests, Quebec, Canada
Authors: Blanchette Pierre , Bourgeois Jean-Claude , St-Onge Sylvain
Published: May 2007

We determined the categories of roost sites used by ruffed grouse ( Bonasa umbellus (L., 1766)) during daytime in winter from 245 radiotelemetric locations of 26 adult females. We conducted our study in the Réserve faunique de Portneuf, located in a mixed nordic-temperate softwood–hardwood forest in Quebec, Canada. We evaluated the effects of weather, snow, and habitat variables on the incidence of snow burrowing, tree roosting, and on-snow roosting using mixed multinomial models, ANOVA, and logistic regressions. The best logistic regression model of snow burrowing probability was identified using the Akaike path. The incidence of each category of roost sites was 41.2% tree roosts, 36.3% snow burrows, and 22.4% on-snow roosts. Coniferous canopy closure and depth of fluffy snow were the variables that influenced roosting behavior the most. Probability of snow burrowing increased with compaction depth and decreased with coniferous cover. Probability of tree roosting increased with temperature. On-snow roosts had a denser lateral obstruction than snow burrows, whereas tree roosts had a greater coniferous basal area, stem density, and canopy cover than snow burrows. Stand type also influenced the incidence of each category of roost sites, snow burrows dominating in deciduous stands and tree roosts dominating in mixed and coniferous stands.
Development of 25kW Class SOFC Module
Authors: Ikeda Koji , Hisatome Nagao , Nagata Katsumi , Tsukamoto Daisuke , Kawaguchi Yutaka , Kosaka Kenichiro , Matake Norihisa , Sasatsu Hiroshi , Takahashi Yasuhiro , Konishi Kinhei
Published: May 2007

Mitsubishi Heavy Industries, Ltd. (MHI) and Electric Power Development Co.,Ltd. (JPOWER) started SOFC module development in collaboration in 1991. Since 2001 we have focused on improvement on SOFC module aiming for high reliability and lower cost. The 5kW-class Cartridge test with 104 cell-tubes was successfully accomplished in 2003. We also executed a dynamic simulation and thermal fluid analysis of improved SOFC module and control system development under atmospheric pressure. In 2006, we have succeeded in the operation of 25kW-class sub- module that will be a unit of highly scalable SOFC system. This module dose not need heating support to maintain the operating temperature, because the fuel exhaust gas from the SOFC module is burned in the combustor and used for heating supply air to SOFC module.
Long-Term Operations Test and Investigation on Stack Performance of Tubular-type SOFC Stacks
Authors: Yamamoto Tohru , Etori Yoshiyuki , Morita Hiroshi , Mugikura Yoshihiro , Watanabe Takao , Yamashita Akihiro
Published: May 2007

Investigation on degradation phenomena during long term operations of four different SOFC modules/stacks has been initiated in the NEDO SOFC project from 2005FY to 2007FY. We, CRIEPI, were operating tubular-type SOFC stacks fabricated by MHI and obtaining data on the long-term stack performance. The obtained data is analyzed to estimate the impact of voltage losses (Nernst loss, Ohmic potential drop and polarization of electrode) by using electrochemical model and compared with the result of initial stack performance. After the long-term operation, the stack will be disassembled to post-test analyses of each component. In additional results of initial and post-test analysis of stack by using SIMS will be reported another presentation
Development of Segmented-in-series Cell-stacks with Flat-tubular Substrates
Authors: Koi Makoto , Yamashita Shoji , Matsuzaki Yoshio
Published: May 2007

The SOFC cell-stacks called flat-tube segmented-in-series cell-stacks have been developed by a joint work of Tokyo Gas and Kyocera. The cell-stacks were composed of multiple single- cells (8YSZ electrolyte, Ni/8YSZ anode, and LaSrCoFe cathode) and current-collectors, placed on both sides of the flat- tubular substrate. The fuel to electric power-generation efficiency of the latest cell-stack converted as the methane fuel was estimated more than 53% HHV-DC at 1023K at the current density, 0.2A/cm2. The complex impedance spectra of the cell- stacks were measured under the operating conditions, for investigations of the relation between the performance and components design. By the measurements under several conditions, we identified the relationship between the impedance spectra and the fuel usage dependence and degradation of the segmented-in-series type cell-stack performance. Based on these results, we continue further studies of the component design (especially anode), for higher efficiency and long-term durability of the cell-stacks.
Development of Anode Supported Solid Oxide Fuel Cells using LaNi(Fe)O3 for Cathodes.
Authors: Orui Himeko , Nozawa Kazuhiko , Chiba Reiichi , Komatsu Takeshi , Watanabe Kimitaka , Sugita Satoshi , Arai Hajime , Arakawa Masayasu
Published: May 2007

We are developing anode-supported solid oxide fuel cells (SOFCs) using LaNi(Fe)O3 (LNF) and Al2O3 doped ScSZ (SASZ) for the cathode and electrolyte, respectively. Anode-supported SOFCs were fabricated using two types NiO powder with different sinterbility to control the anode performance. The cells with an anode made from fine NiO powder show high-power performance, while those made from coarse NiO powder show good gas diffusion characteristics. Combining the merits of these anodes, we successfully fabricated a cell that exhibits high- power-generation characteristics and smooth gas diffusion through the anode substrate at the same time. Moreover, by controlling the anode construction, we were able to keep the warpage in the cells below 0.3 mm even for large cells (~ 100 mmφ) and thereby improve the performance of a single-cell stacks.
Development of Novel Cell Components for Low-temperature SOFC
Authors: Zhang-Steenwinkel Ye. , van Tuel Marc M. , van Berkel Frans P. , Rietveld Bert
Published: May 2007

The electrochemical performance of Co-containing perovskites, La0.6Sr0.4CoO3 (LSC), Sm0.5Sr0.5CoO3 (SSC), Ba0.5Sr0.5Fe0.2Co0.8O3 (BSCF), SrFe0.67Co0.33O3 (SFC) and Pr0.58Sr0.4Fe0.8Co0.2O3 (PSFC), have been investigated by impedance spectroscopy on symmetrical cells. These cathode materials have been integrated into 5x5 cm2 anode-supported cells for the evaluation of cell performance at 600{degree sign} C, using humidified H2 as fuel and synthetic air as oxidant. The use of Co-rich perovskite as cathode material results in improved cell performance at 600oC compared to the state-of-the-art La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathode. Impedance analysis indicates that the performance of the cells containing the Co- rich perovskite cathodes is determined predominantly by the ohmic resistance, especially at low operating temperature (600oC).
Development Status of SOFC Cell and Stack Technology at NRC-IFCI
Authors: Tuck Adam , Zhang Xinge , Hui Rob , Qu Wei , Decès-Petit Cyrille , Xie Yongsong , Roller Justin , Min Kyong-Bok , Robertson Mark , Yick Sing , Maric Radenka , Ghosh Dave
Published: May 2007

Solid Oxide Fuel Cell (SOFC) development was started at the National Research Council of Canada's Institute for Fuel Cell Innovation (NRC-IFCI) in 2003 with the goal to develop the next generation of SOFC's for Canadian Industry. To accomplish this task, work focused on the development of low temperature cermet and metal supported cells, direct deposition methods, low temperature sintering, seal and stack technology. As of November 2006, 5cmx5cm cermet supported cell performance has been improved to 900 mW/cm2 @ 600{degree sign}C. These components have been incorporated into short stacks developed at IFCI to continue the push to commercialize this technology. At the same time, direct deposition technology has progressed rapidly to the point where metal supported 5x5 cells can be fabricated using sintering temperatures below 850{degree sign}C. Results of this work will be presented, along with the development path at IFCI.
Anode Supported Solid Oxide Fuel Cells - Deconvolution of Degradation into Cathode and Anode Contributions
Authors: Hagen Anke , Liu Yi L. , Barfod Rasmus , Hendriksen Peter V.
Published: May 2007

The degradation of anode supported cells was studied over 1500 h as function of cell polarization either in air or oxygen on the cathode. Based on impedance analysis, contributions of anode and cathode to the increase of total resistance were assigned. Accordingly, the degradation rates of the cathode were strongly dependent on the pO2; they were significantly smaller when testing in oxygen compared to air. Microstructural analysis of the cathode/electrolyte interface of a not-tested reference cell carried out after removal of the cathode showed sharp craters on the electrolyte surface where the LSM particles had been located. After testing in air, these craters flattened out and decreased in size, indicating a decreased three phase boundary length. In contrast, they remained almost unchanged after testing in oxygen giving an explanation for the observed smaller - mainly anode related - degradation rate.
Fracture Mechanics Experiments to Characterize the Failure of Ceramic/Metal Joints in SOFC Stacks
Authors: Kuhn Bernd , Wetzel Franz J. , Malzbender Jürgen , Steinbrech Rolf W. , Singheiser Lorenz
Published: May 2007

Mechanical integrity of the sealants in planar SOFC stacks is a key prerequisite for reliable operation. In this respect joining with metals rather than brittle glass-ceramics is considered to have advantages. Hence, as one of the joining solutions for SOFCs of planar design the reactive air brazing of the ceramic cell into a metallic frame has gained increasing interest. Fracture experiments were carried out to characterize the fracture energy and failure mechanisms of silver-based reactive air brazes, used for joining the zirconia electrolyte of an anode supported planar cell with a metallic Crofer22APU frame. The specimens were mechanically tested in notched beam bending geometry. In-situ observation with optical and SEM resolution revealed preferential delamination crack propagation near the steel/braze interface. The influence of brazing parameters and associated interfacial reactions on the crack path location is addressed. Discussion of the results focuses in particular on the role of oxide scale formation.
Reliability Evaluation of SOFC under Simulated Operating Condition
Authors: Sato Kazuhisa , Imanaka Norihiro , Fukui Ken-Ichi , Numao Masayuki , Kyotani Shintaro , Yashiro Keiji , Kawada Tatsuya , Hashida Toshiyuki , Mizusaki Junichiro
Published: May 2007

Self-Organizing Map (SOM) method was developed in order to investigate the fracture process of SOFC module under operating environments. In this study, the damage testing method was applied to ceria electrolyte-supported single cells. The vertical crack in the electrolyte and crack in the glass seal were detected by AE method. The SOM method identified two types of damage. By using this method, it was possible to show the possibility that the detailed deterioration process can be evaluated, visually, and in real- time, even when applied to modules at the actual equipment level.
Fabrication of Micro-Tubular SOFC Stack Using Ceramic Manifold
Authors: Suzuki Toshio , Funahashi Yoshihiro , Yamaguchi Toshiaki , Fujishiro Yoshinobu , Awano Masanobu
Published: May 2007

Micro tubular SOFCs have been expected to overcome shown many desirable characteristics over conventional (planar) SOFCs such as high thermal stability during rapid heat cycling and high packing density of the cells, which enables to realize micro SOFC systems applicable to portable devices and auxiliary power units for automobile. Our research project Advance Ceramic Reactors aims to develop innovative processing method to fabricate such new micro tubular SOFCs and their stacks. In this study, new micro tubular SOFC stacks was fabricated and the performance of the stack was investigated.
Tubular Micro-Solid Oxide Fuel Cell for Remote Power Applications
Authors: Sarkar Partho , Yamarte Luis , Johanson Lorne
Published: May 2007

An anode-supported tubular 'Micro Solid Oxide Fuel Cell' (μ SOFC) is being developed for fabrication of a high volumetric power density SOFC system for remote power applications. An Electrophoretic deposition (EPD) based manufacturing process is being developed for production of SOFC single cells, this process has the potential to simplify fabrication technology and reduce manufacturing costs. Micro Solid Oxide Fuel Cells have two main advantages, a substantial increase in the volumetric power density of a stack and quick start up. A decrease in single cell tube diameter allows for a reduction in wall thickness without any degradation of a cell's mechanical properties. Due to its thin wall, a μSOFC has an extremely high thermal shock resistance and low thermal mass. These two characteristics are fundamental in reducing start up and turn off time for the SOFC stack.
Power Generating Performance of Honeycomb-type Solid Oxide Fuel Cell Consisting of LaGaO3 Based Oxide Electrolyte
Authors: Zhong Hao , Matsumoto Hiroshige , Ishihara Tatsumi , Toriyama Akira
Published: May 2007

La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) -based honeycomb cell was first time successfully built and operated by using single and 4 walls. The LSGM honeycomb cell shows much higher power density than that using ZrO2 based one from 973K to 1173K. The maximum power density is ca. 390 and 250 mW/cm2 at 1073 and 973K, respectively. The details of internal resistance analysis suggest that the IR loss is dominant internal resistance of the cell. The 4-wall cell is also successfully working at 1073K, and the estimated volumetric power density is as high as 300 W/L.
Synthesis, Structure and Electrochemical Properties of Epitaxial Perovskite Films Deposited on YSZ Substrate
Authors: Mori Daisuke , Oka Hideaki , Suzuki Yoshitaka , Yamada Atsuo , Kanno Ryoji , Imanishi Nobuyuki , Takeda Yasuo
Published: May 2007

Epitaxial film electrodes of La0.8Sr0.2MnO2 (LSM) and Y0.5Ca0.5MnO3 (YCM) with the perovskite structure were obtained by annealing films deposited on the yttria- stabilized zirconia (YSZ) substrates by pulsed laser deposition method. These films were characterized by thin-film X-ray diffraction measurement and ac impedance spectroscopy. The film orientations depended on the substrate plane of YSZ. The electrode reactions proceeded by successive several processes. The activation energies of charge transfer process of both the LSM and YCM films depended on the crystal plane of the electrode surface; the film on YSZ (100) showed smaller activation energy than the film on YSZ (110). Charge transfer process of the LSM films was also affected by the lattice misfit. The crystal plane of the electrode surface and structural distortion of the film were indicated to be important parameters for the electrode reaction.
Electrode Polarization Characteristics of Solid Oxide Fuel Cells Under Pressurized Conditions
Authors: Matsui Toshiaki , Futamura Makoto , Kikuchi Ryuji , Eguchi Koichi
Published: May 2007

Polarization characteristics of both anode and cathode were investigated under pressurized conditions as a basic information for solid oxide fuel cell/gas turbines hybrid systems. The influences of partial pressure of reactant gases on interfacial conductivity were examined at 1000{degree sign} C in the total pressure range of 100-300 kPa by using a conventional single cell employing YSZ tubular electrolyte. For both electrodes, the two arcs were observed in the impedance spectra and the impedance was reduced with an increase in partial pressure of reactant gases. For anode, the interfacial conductivity at high frequencies was independent of the P(H2O) whereas it depended on the P(H2) in the low P(H2O)/P(H2) ratio under an open circuit condition. On the other hand, in the case of cathode, the interfacial conductivity at low frequencies was proportional to P(O2)1/4, whereas that at high frequencies was independent.
Properties of Nickel Products for SOFC Applications
Authors: Renny Les , Yang Quan , Wasmund Eric , Bartout Jean-Dominique , Corbin Stephen
Published: May 2007

The first part of this paper presents a review of all nickel products that find applications in SOFCs. The work covers nickel oxides, nickel and nickel alloy foams, nickel powders, and nickel-coated graphite. The second part of the paper reports experimental work in two areas. The first one is an experimental study on the creep properties of nickel foam under compressive stress at high temperatures. This would provide insights for using nickel and nickel alloy foam as GDL or anode current collector in SOFC's. Another experimental work is concerning the preparation of SOFC anodes using Ni based powders including nickel oxides and nickel powders. Results are reported in this paper on volume and dimensional changes of an anode during burnout stage and sintering stage when various nickel powders and a nickel oxide are used.
Architectures and Performance of High-Voltage, Microscale Single-Chamber Solid Oxide Fuel Cell Stacks
Authors: Crumlin Ethan J. , La O' Gerardo Jose , Shao-Horn Yang
Published: May 2007

In this study, we describe multi-cell SC-SOFC architectures with multiple different electrode/electrolyte systems. These SC-SOFCs are fabricated using thin-film techniques and patterned via photolithography. Micro SC-SOFCs with feature dimensions ranging from 5μm to 200μm are successfully constructed and repeatable. An OCV of approximately 380mV at 400{degree sign}C was found when using methane and air gases. OCV values were found to decrease with increasing temperature and a sign change in voltage was observed around 575{degree sign}C. Future studies will include the results from changing the sizes and spacing between electrodes to create a mechanistic study for SC-SOFCs to understand the rate limiting reactions and electrode selectivity. Additionally various SC-SOFC 'stacked' configurations of up to ten cells will be created. SC-SOFC variables will include changes in length, thickness, area and electrode/electrolyte material to observe the fuel cell stack performance as a result of the altered parameter.
Characterisation of Mixed Conducting La-Sr-Fe Perovskites for Application in Solid Oxide Fuel Cells
Authors: Holtappels Peter , Braun Artur , Thünemann Maik , Vogt Ulrich
Published: May 2007

The substitution of La-Sr-ferrites (LSF) with Ni and Cu on the Fe-site was investigated with respect to the thermal expansion and the electrical properties. The thermal expansion is influenced by the stoichiometry as well as by the Ni or Cu substitution. The apparent CTE below 800{degree sign}C is close to the values for yttria stabilized zirconia, but increased due to the oxygen release at higher temperatures. The conductivity of LSF - also if substituted by Ni and Cu on the Fe site - shows an apparent semi-conductor behaviour, but tend to peak around the SOFC operating temperature. The results indicate the potential of Ni substituted LSF as an SOFC cathode material for operation below 800{degree sign}C.
LSCF Thin Film Cathodes Deposited by Spray Pyrolysis for Micro-SOFC
Authors: Beckel Daniel , Muecke Ulrich P. , Florey Guillaume , Gyger Thomas , Dubach Alban , Infortuna Anna , Gauckler Ludwig J.
Published: May 2007

Porous LSCF thin film cathodes suitable for application in Micro Solid Oxide Fuel Cells (μ-SOFCs) were fabricated by spray pyrolysis and pulsed laser deposition. During spray pyrolysis a precursor is sprayed onto a heated substrate, where an amorphous metal oxide film is obtained. Porosity forms during a subsequent annealing process depending on the maximum crystallization temperature. It was possible to fabricate these cathodes with a maximum processing temperature of 650{degree sign}C, which is desirable for the processes and materials involved in μ- SOFCs fabrication. The films are thinner than 1 μm with nanometer-sized grains. The cathode performance was evaluated by determing the area specific resistance. The microstructure proofed to have a strong influence on the cathode performance. Smaller grain sizes led to better performance and can be achieved by low annealing temperature. Furthermore, the microstructure achieved by spray pyrolysis led to better results, than the microstructure achieved by pulsed laser deposition.
Thermochemical Stability and Polarization Resistance of La(Ni0.6Fe0.4)O3 Cathode
Authors: Sornthummalee Potejanee , Sato Kazunori , Komatsu Takeshi , Orui Himeko , Chiba Reiichi , Arakawa Masayasu
Published: May 2007

Polarization resistance of the LaNi0.6Fe0.4O3 (LNF) cathode has been investigated in relation to the electrical conductivity and thermochemical stability. Electrochemical properties of a solid oxide fuel cell using LNF as the cathode were compared to those using La0.8Sr0.2MnO3 (LSM). Temperature dependence of the cathodic polarization resistance was discussed in terms of the thermochemical stability. The electrical conductivity of bulk LNF sample was measured with the four-probe DC method at different oxygen partial pressures. Phase identification for the LNF powder samples treated at 900oC in the atmosphere of oxygen and argon was studied with time dependency of heat treatment by X- ray diffraction analysis. Although the rhombohedral crystal structure of the starting phase was maintained, the electrical conductivity of LNF sensitively changed with the partial pressure of oxygen.
Ba1-xSrxCo1-yFeyO3-δ Perovskites Bulk and Thin Films: Phase Compositions and Electrical Conductivity
Authors: Yang Zhen , Infortuna Anna , Harvey Ashley , Gauckler Ludwig J.
Published: May 2007

Ba0.5Sr0.5Co0.8Fe0.2O3-δ showed good performance as cathode material on doped ceria electrolyte for intermediate temperature solid oxide fuel cells (1). This cathode exhibits high power densities when operated with humidified hydrogen as the fuel and air as the cathode gas. This compound is part of the Ba-Sr-Co-Fe-O system with BaFeO3, SrFeO3, BaCoO3 and SrCoO3 as end members. We report about the phase stability and the electric properties of these solid solutions. Powders were prepared by the solid state reaction method to synthesize the Ba1-xSrxCo1-yFeyO3-δ (BSCF) compositions with 0.2 {less than or equal to} x {less than or equal to} 0.8 and 0.2 {less than or equal to} y {less than or equal to} 0.8. As raw materials metal carbonates and oxides were used. Electric DC conductivity was measured on polycrystalline bulk samples. All the compounds showed semiconductivity from room temperature up to 500{degree sign}C and a transition to metallic conductivity to higher temperatures. The compositions richer in Sr and Co show the highest electric conductivity as high as 250 S/cm at ~470 {degree sign}C, much higher than the previously reported single compound Ba0.5Sr0.5Co0.8Fe0.2O3-δ. Thin films of BSCF were deposited on MgO substrates by the pulsed laser deposition technique (PLD) and the electric conductivity was measured in plane and compared with bulk values. In order to elucidate the origin of different conductivity values for the different compositions and evaluate the oxygen non stoichiometry, the oxidation state of Co and Fe has been studied by XAS.
Impedance Spectroscopy Studies of Oxygen Reduction Reaction on Thin Film Platinum Microelectrodes Supported on YSZ
Authors: Koc Serkan , La O' Gerardo Jose , Golfinopoulos Theodore , Shao-Horn Yang
Published: May 2007

Platinum is considered a promising electrocatalyst in solid oxide fuel cells (SOFCs) for micro and portable applications. Although the platinum/YSZ system has been studied extensively, numerous open questions remain with regard to the oxygen reduction reaction (ORR) mechanism at the molecular level. It has been proposed that limiting reaction steps may include dissociative adsorption of oxygen, surface diffusion of oxygen species and migration of oxygen species to the electrolyte (charge transfer) through the three-phase boundaries. In this study, dense platinum microelectrodes with well-defined geometries were prepared by microfabrication techniques and patterned using photolithography. Electrochemical impedance spectroscopy (EIS) of Pt microelectrodes is conducted at pO2 levels between 0.001kPa to 100kPa and temperatures between 570{degree sign}C-750{degree sign}C. The EIS response could be modeled using a Gerischer impedance element below 700{degree sign}C. It is proposed that oxygen adsorption and surface diffusion simultaneously act as rate-limiting (co-limiting) processes of ORR in the temperature and pO2 range examined.
Combination of Electrochemical Impedance Spectroscopy and Cyclic Voltammetry to Investigate Oxygen Ion Transport in YSZ Electrolyte of SOFC
Authors: Boonjob Warunya , Punbusayakul Nitinai -. , Beckett Ron -. , Masomtub Manop -. , Wongtidad Kitsadate -. , Charojrochkul Sumittra , Veerasai Waret -.
Published: May 2007

Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) can be used to study the mechanisms and kinetics of electrochemical reactions at solid-solid interfaces. A thin gold film-yittria stabilized zirconia (Au/YSZ) electrolyte interface was used as a model experimental system with a three-electrode configuration. Oxidation and reduction of the sample surface under chemically well-defined experimental conditions were induced. The oxygen ion transport behavior on the Au/YSZ electrolyte interface was analyzed in order to gain a better understanding of the oxygen reduction mechanism and to improve the electrolyte performance. This work focuses primarily on the charge transfer coefficient of oxygen ion transport on the Au/YSZ electrolyte interface as interpreted in terms of kinetic parameters obtained from impedance spectra and cyclic voltammograms as functions of operating temperature. The charge transfer coefficients obtained agreement suggests from the references that the polarization curve is distributed to a two-electron transfer process.
Multilayer High Performance Ceramic Anodes
Authors: Gross Michael , Gorte Raymond , Vohs John
Published: May 2007

A new approach to the design of ceramic anodes that uses a thin catalytically active functional layer that has only modest electronic conductivity sandwiched between the electrolyte and a non-catalytic electronically conducting ceramic layer that is used as the current collector is described. The anode design is flexible and allows various materials to be used in the functional and current-collector layers. Results are presented for anodes with thin functional layers (12 μm) consisting of a porous CeO2/YSZ composite impregnated 1 wt % Pd to optimize catalytic activity and a 100 μm thick layer of porous La0.3 Sr0.7TiO3 (LST) as the current collector. Low anode impedances and excellent overall performance were obtained with cells with these anodes while operating on both humidified hydrogen and hydrocarbon fuels.
Morphology Control of Ni-GDC Cermet Anode for Lower Temperature SOFC
Authors: Misono Teruhiko , Murata Kenji , Yin Jingtian , Fukui Takehisa
Published: May 2007

A Ni-GDC cermet is expected as one of the materials for lower temperature SOFC anode, which is obtained from reducing NiO-GDC powder. In this work, we report the effects of NiO-GDC powders produced by mechano-chemical technique on the fabricating processes of anode and the electrical performance of the anode. The properties of sintering and dispersion of NiO-GDC powders were studied and the morphology of Ni-GDC anode was characterized. The performance of the cell which consisted of Ni-GDC anode, GDC electrolyte and LSCF cathode was evaluated by current interruption method. The experimental results indicated that the maximum power densities were 0.93 and 0.31 W/cm2 when the cell was operated at 600{degree sign}C and 500{degree sign}C respectively.
Modeling Approach of a New Anode Concept for Gradual Internal Reforming
Authors: Klein Jean-Marie , Bultel Yann , Georges Samuel , Pons Michel
Published: May 2007

Natural gas appears to be a fuel of great interest for SOFC systems. To avoid cooling effect, Gradual Internal Reforming (GIR) can be used. GIR is based on local coupling between steam reforming and hydrogen oxidation. The steam required for the reforming reaction is obtained from the steam generated by the hydrogen oxidation. It was demonstrated in previous studies that the cooling effect disappeared. However, with GIR, the risk of carbon formation is greater. To cope with carbon formation a new cell configuration is studied. This configuration combines a catalyst layer with a cermet anode, allowing GIR without coking. This study proposes simulations, using the CFD RC software package, of the behavior of a tubular SOFC using GIR. A thermodynamic study based on the partial pressure distributions in the cell is carried out to investigate the occurrence of carbon formation. The simulations indicate that, the risks of carbon deposition were strongly reduced if the new configuration is used.
Behavior of Carbon Deposition on Fuel Electrode and Subsequent Deterioration of Cell Performance During Internal Reforming Operation of SOFCs
Authors: Matsui Toshiaki , Iida Tatsuya , Kawano Mitsunobu , Inagaki Toru , Kikuchi Ryuji , Eguchi Koichi
Published: May 2007

Several cermet anodes were investigated for direct internal reforming operation of solid oxide fuel cells. The effects of steam and discharge conditions were examined for internal reforming operation with propane as a hydrocarbon fuel. Even at high steam-to-carbon (S/C) ratio, power generation characteristics with Ni-YSZ were deteriorated during internal reforming operation with propane at 1000åC, due to carbon formation at low current densities, whereas stable generation was observed for the cells with Ni-ScSZ or Ni-SDC anode by feeding propane at low S/C = 0.8. Carbon deposition rate was measured for several cermets by feeding dry or humidified methane by the gravimetric technique. The carbon deposition rate over Ni-ScSZ was lower than Ni-YSZ, leading to better generation performance with propane at low S/C. Ni-SDC showed the highest carbon deposition rate among the cermets investigated, even for humidified methane. This implies that carbon formed over Ni-SDC could be effectively removed upon power generation.