bluuebunny/crossref_metadata_2025 huggingface dataset:
Rho-kinase inhibitors Y-27632 and fasudil prevent agonist-induced vasospasm in human radial artery
Authors: Disli Olcay Murat , Ozdemir Ercan , Berkan Ocal , Bagcivan Ihsan , Durmus Nedim , Parlak Ahmet
Published: September 2009

Radial artery (RA) vasospasm remains a potential cause of early graft failure after coronary artery bypass graft surgery, despite pretreatment with α-adrenergic or calcium channel blockers. Our aim was to investigate the mechanism of the vasorelaxant effects of Rho-kinase inhibitors (Y-27632 and fasudil) on the human RA. Segments were obtained from 30 patients undergoing coronary artery bypass graft and were divided into 3–4 mm vascular rings. The rings were stimulated with 10−5 mol/L phenylephrine (PE) by using the isolated tissue bath technique and were relaxed with 10−6 mol/L acetylcholine. Relaxation responses were recorded for Y-27632 (10−9–10−4 mol/L), fasudil (10−9–10−4 mol/L), and sodium nitroprusside (SNP) (10−9–10−5 mol/L). Y-27632 and fasudil relaxation responses were repeated in either NG-nitro-l-arginine (l-NNA), which is a specific endothelial nitric oxide synthase inhibitor, or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), which is a guanylate cyclase inhibitor. SNP relaxation responses were repeated in 10−8 mol/L Y-27632 and 10−8 mol/L fasudil. Y-27632 and fasudil caused concentration-dependent vasorelaxation in RA rings precontracted with PE, and maximal relaxation (100%) was recorded at the highest concentration used (10−4 mol/L). The vasorelaxant effects of Y-27632 and fasudil were significantly reduced in the presence of l-NNA and ODQ, and the pD2values of Y-27632 and fasudil were not changed. The vasorelaxant effects of SNP were significantly increased in the presence of Y-27632 and fasudil, and the pD2values of SNP were not changed. These findings indicate that Y-27632 and fasudil caused concentration-dependent vasorelaxation in the RA rings. Because this effect was decreased in a dose-dependent manner by l-NNA and ODQ, the relaxant effects of Y-27632 and fasudil could be due to stimulation by nitric oxide that is being released. Rho-kinase inhibitors may have an important role in preventing vasospasm in arterial grafts used for coronary artery surgery.
Cerebral blood flow regulation by nitric oxide in neurological disorders
Authors: Toda Noboru , Ayajiki Kazuhide , Okamura Tomio
Published: September 2009

There has been a rapid increase in the amount of information on the physiological and pathophysiological roles of nitric oxide (NO) in the brain. This molecule, which is formed by the constitutive isoforms of NO synthase, endothelial (eNOS) and neuronal (nNOS), plays an obligatory role in the regulation of cerebral blood flow and cell viability and in the protection of nerve cells or fibres against pathogenic factors associated with Alzheimer’s disease, Huntington’s disease, seizures, and migraine. Cerebral blood flow is impaired by decreased formation of NO from endothelial cells, autonomic nitrergic nerves, or brain neurons and also by increased production of reactive oxygen species (ROS). The NO–ROS interaction is an important topic in discussing blood flow and cell viability in the brain. Excessive production of NO by inducible NOS (iNOS) and nNOS in the brain participates in neurotoxicity. Recent studies on brain circulation have provided useful information about the involvement of impaired NO availability or uncontrolled NO production in cerebral pathogenesis, including Alzheimer’s disease, seizures, vascular headaches, and inflammatory disorders. Insight into the role of NO in the brain will contribute to our better understanding of cerebral hemodynamic dysfunction and will aid in developing novel therapeutic measures in diseases of the central nervous system.
ASYMPTOTIC BEHAVIOR OF A VISCOUS FLUID WITH SLIP BOUNDARY CONDITIONS ON A SLIGHTLY ROUGH WALL
Authors: CASADO-DÍAZ J. , LUNA-LAYNEZ M. , SUÁREZ-GRAU F. J.
Published: September 2009

For an oscillating boundary of period and amplitude ε, it is known that the asymptotic behavior when ε tends to zero of a three-dimensional viscous fluid satisfying slip boundary conditions is the same as if we assume no-slip (adherence) boundary conditions. Here we consider the case where the period is still ε but the amplitude is δε with δε/ε converging to zero. We show that if [Formula: see text] tends to infinity, the equivalence between the slip and no-slip conditions still holds. If the limit of [Formula: see text] belongs to (0, +∞) (critical size), then we still have the slip boundary conditions in the limit but with a bigger friction coefficient. In the case where [Formula: see text] tends to zero the boundary behaves as a plane boundary. Besides the limit equation, we also obtain an approximation (corrector result) of the pressure and the velocity in the strong topology of L2 and H1 respectively.
GLOBAL EXPONENTIAL STABILITY OF REACTION-DIFFUSION TIME-VARYING DELAYED CELLULAR NEURAL NETWORKS WITH DIRICHLET BOUNDARY CONDITIONS
Authors: BAI JIANGHONG , TENG ZHIDONG , JIANG HAIJUN
Published: September 2009

This paper is devoted to global exponential stability of reaction-diffusion time-varying delayed cellular neural networks with Dirichlet boundary conditions. Without assuming the monotonicity and differentiability of activation functions, nor symmetry of synaptic interconnection weights, the authors present some delay independent and easily verifiable sufficient conditions to ensure the global exponential stability of the equilibrium solution by using the method of variational parameter and inequality technique. These conditions obtained have important leading significance in the designs and applications of global exponential stability for reaction-diffusion neural circuit systems with delays. Lastly, one example is given to illustrate the theoretical analysis.
PERMANENCE FOR THE LOTKA–VOLTERRA COOPERATIVE SYSTEM WITH SEVERAL DELAYS
Authors: NAKATA YUKIHIKO
Published: September 2009

In this paper, we establish a new sufficient condition of the permanence for the Lotka–Volterra cooperative systems with multiple discrete delays by extending the results in [Nakata and Muroya, Permanence for nonautonomous Lotka–Volterra cooperative systems with delays, Nonlinear Anal. RWA., in press]. Our condition holds even if the instantaneous feedback does not dominate over the total of the interspecific interactions and does not need the restriction on the size of time delays, different from the results in [Lu and Lu, Permanence for two-species Lotka–Volterra cooperative systems with delays, Math. Biosci. Eng.5 (2008) 477–484]. We offer an example for comparison with the previous results and numerical results supporting our theoretical analysis are given.
Impact of the Volatile Acid Contaminants on Copper Interconnects Electrical Performances
Authors: Fontaine Hervé , Feldis Hélène , Danel Adrien , Cetre Sylviane , Ailhas Christelle
Published: September 2009

The volatile acids impact on the via resistance of a Cu interconnect base structure was investigated by the intentional Cu-surfaces contamination with HF or HCl at a sensitive process step. The wafers acid contamination was performed from polluted FOUPs outgassing during a queue time step with or without an additional direct contamination in gas phase. Electrical results clearly shows that HF and HCl contamination on Cu surfaces at a sensitive step in the interconnects processing can lead to significant degradation of via resistances. The impact intensity appears to be dependent on the contaminant level and nature but also for HCl of the contamination moment (just after process or during q-time). Finally, from the data obtained, specifications of F or Cl threshold levels are proposed to control contamination both on Cu-surfaces and in FOUPs in order to avoid detrimental impacts in fab.
Using a Novel Solvent-based Technology to Preserve Low-k Material when Removing Gap Fill Material
Authors: Franklin Cole , Rector Allison , Pfettscher Don , Pollard Kimberly , Scheele Diane
Published: September 2009

As the technology nodes shrink, device makers are running into barriers with traditional post etch process flows. In the back-end-of-line (BEOL), the porous low-k materials can be damaged by the etch chemistries, the dry ash plasmas and the subsequent cleaning processes. Replacing the dry ash and typical wet cleaning processes with a one step selective solvent-based removal process can work to protect the etched low-k. The solvent-based blend must remove the reactive ion etch (RIE) residues and gap fill material used in the patterning step while preserving the low-κ from further damage. This paper will focus on the removal of films and post etch residues in under 2 minutes with a novel solvent formulation.
Drying Impact on Semiconductor Surfaces after Innovative Solvent Exposure
Authors: Le Tiec Yannick , Fournel Frank , Rochat Névine , Barnes Jean-Paul , Veillerot Marc , Morales Christophe , Moriceau Hubert , Clavelier Laurent , Rieutord Francois , Morote Carlos , Vandenbossche Martin , Butterbaugh Jeff , Radu Ionut
Published: September 2009

The wafer direct bonding technique is very sensitive to surface adsorbed water; hence it is a useful way to characterize the impact of wafer drying. We have focused this work on the drying impact on surfaces after innovative solvent exposure, in a liquid or in a vapor phase, compared with standard isopropyl alcohol drying: we report characterization results from different techniques investigating both native and thermal oxide surfaces. We report promising drying through low surface tension solvent exposure, especially in a vapor phase.
Particle Removal and Damage Thresholds from Particle Removal and Damage Formation Frequency for High-Velocity-Aerosol Cleaning
Authors: Wostyn Kurt L. , Wada Masayuki , Andreas Michael , Kenis Karine , Roussel Philippe , Bearda Twan , Leunissen Peter , Mertens Paul
Published: September 2009

Particle removal without damage addition remains a grand challenge. Particle removal and damage addition are macroscopic effects of the cleaning technique. In order to improve the understanding of cleaning techniques like high-velocity-aerosol cleaning, these macroscopic properties need to be linked to the fundamental properties of the technique like its spray characteristics. Here we show that using the particle removal or damage addition frequency, we can estimate the fraction of droplets contributing either to particle removal or damage addition. We find that only a very small fraction of the droplets leads to damage formation. We also show that for particle removal only a very small fraction of droplets is needed, or the droplets only need to clean a very small surface area. The fraction of droplets contributing to particle removal depends on the effective area used to analyze the particle removal frequency.
Effect of Laser Shock Wave Cleaning Direction on Particle Removal Behavior at Trenchs
Authors: Kim Jin-Su , Busnaina Ahmed A. , Park Jin-Goo
Published: September 2009

Laser shock wave cleaning (LSC) has been introduced to remove particles on patterned wafers. For the application of LSC to EUV mask cleaning or any BEOL cleaning process, the questions have been raised how the particles behave when patterns exist. The effect of pattern topography on the particle removal was investigated on trench patterns using LSC. The topographical effect was characterized as a function of laser shock wave propagation direction. Comparison of particle removal efficiency (PRE) between parallel and vertical direction of laser shock wave to the trench patterns was done. PRE was lower in case of vertical direction when compared to parallel direction. LSC in parallel direction has more PRE than in vertical direction and hence topography is an important consideration during LSC.
Monitoring of Semiconductor Surfaces using Photoconductance Decay (PCD) Method
Authors: Drummond Patrick , Ramani Shankarram , Ruzyllo Jerzy
Published: September 2009

This experiment is concerned with photoconductive decay (PCD) measurements devised specifically for the purpose of characterization of the near-surface region of semiconductor substrates. The method was tested through the measurements of the germanium wafers for which the surface was roughened in a controlled fashion, and multi-crystalline silicon wafers with textured surfaces. The near-surface lifetime of minority carriers and carrier mobility were reduced as the Ge surface roughness increased, and increased for mc-Si as saw damage was removed by chemical treatment. These results demonstrate a direct correlation between condition of the semiconductor surface and the electrical parameters measured. It is postulated that the PCD method using temporary contact can be effectively used to monitor the condition of semiconductor surfaces during device processing.
SOFC Stacks for Mobile Applications
Authors: Lang Michael , Weckesser Tilman , Auer Corinna , Jentsch Paul , Friedrich K. A. , Westner Christina
Published: September 2009

Solid Oxide Fuel Cells (SOFCs) are gaining more and more importance as auxiliary power units (APU), e.g. for passenger cars, trucks and airplanes. In this context, the main challenge is the development of SOFC stacks, which fulfill the strong requirements for mobile applications, e.g. low weight and volume, high power densities with reformate gases and low degradation rates under dynamic operating conditions. The paper presents results of investigations of SOFC short stacks and stacks for mobile applications, which were developed in an industrial consortium. The stack design is based on stamped metal sheet bipolar plates, into which anode supported cells are integrated. The stacks were electrochemically characterized mainly by long-term measurements, by current-voltage measurements and by impedance spectroscopy. The SOFC stacks were operated at different temperatures, varying fuel gas compositions and different fuel gas flow rates. The electrochemical performance, the uniformity, the voltage losses and the degradation mechanisms of the short stacks were analyzed.
Long-term, Redox and Thermal Cycling Stability of Electrolyte Supported Cells
Authors: Glauche Andreas , Betz Thomas , Mosch Sindy , Trofimenko Nikolai , Kusnezoff Mihails
Published: September 2009

The electrolyte supported cells with low area specific resistance (ASR<0.34 Ohm cm²) have been tested for long-term, thermal and redox stability in ceramic housing. It has been shown that the cells with optimized anode microstructure have degradation <0,1 % / 1000h and no measurable resistance change in the range of mistake of used method after ten thermal and redox cycles. The small fluctuation of contact resistance between anode and current collector has been observed especially during cycling experiments. The redox cycles lead to the largest fluctuation of ASR values during cycling due to direct influence on the bonds between anode and current collector.
Locally-Resolved Study of Degradation in a SOFC Repeat-Element
Authors: Wuillemin Zacharie , Nakajo Arata , Müller Andres , Schuler Andreas J. , Diethelm Stefan , Van Herle Jan , Favrat Daniel
Published: September 2009

The locally-resolved degradation behavior was studied during 1900 hours in a SOFC repeat-element. In-situ measurements of local electrochemical performance were made on 18 locations over a segmented anode-supported cell. The evolution of local current densities, overpotentials and area-specific resistances was studied, showing a reorganization of the electrochemical reaction with time. The extent and the spatial distribution of degradation were established for different electrochemical reactions steps using impedance spectroscopy. The low-frequency cathode contribution was the mostly altered process, followed by the charge transfer reaction on anode side. Post-experiment analyses allowed to identify three major pollutants on the cathode side (chromium, silicon and sulfur), whose spatial distributions corresponded to the observed local degradation. Chromium was present only near the air inlet, while silica was found to affect a larger area, with decreasing amounts along the flow. Sources of pollutants were identified in system components as well as within the stack repeat-element.
Comparison of the Degradation of the Polarisation Resistance of Symmetrical LSM-YSZ cells, with Anode Supported Ni-YSZ/YSZ/LSM-YSZ SOFCs
Authors: Torres da Silva Iris M. , Nielsen Jimmi , Hjelm Johan , Mogensen Mogens
Published: September 2009

Impedance spectra of a symmetrical cell with SOFC cathodes (LSM-YSZ/YSZ/LSM-YSZ) and an anode supported planar SOFC (Ni-YSZ/YSZ/LSM-YSZ) were collected at OCV at 650{degree sign}C in air (cathode) and humidified (4%) hydrogen (anode), over 155 hours. The impedance was affected by degradation over time in the same frequency range for both cells (~10 Hz), possibly indicating that the same physical process was affected in both types of cell. However, deconvolution of the impedance data was not straightforward. When n-values of the constant phase elements in the otherwise identical equivalent circuit for the full cell were changed slightly, very different results were obtained, showing the high sensitivity of the fitting procedure. Therefore, the equivalent circuit applied should be refined further, requiring comparison of impedance data of the cells at higher temperature (750, 850{degree sign}C).
Behavior of High Temperature SOFC Materials Subjected to Thermal Cycles
Authors: Yasumoto Kenji , Yamamoto Tohru , Takei Katsuhito , Izaki Yoshiyuki , Minamizono Takahiro
Published: September 2009

In order to evaluate the thermal stress of high temperature SOFC materials, four different square bars of materials were examined under four different thermal cycles. Materials composed of a Ni-YSZ anode in H2 and 5%H2-N2, a YSZ electrolyte, and a (La,Sr)(Cr,Co)O3 interconnect were unaffected by the thermal cycles. However, a Ni-YSZ anode in N2 purge gas and a (La,Sr)MnO3+d cathode in air were affected by the thermal cycles strongly. Thus, by using 5%H2-N2, the anode can evade thermal cycle damage. The shrinkage characteristic of two cathode materials in air and N2 atmospheres were also evaluated. A reduction of thermal cycle induced shrinkage is made possible by a mixture of La0.6Sr0.4MnO3 and stabilized zirconia materials, and when the atmosphere of the temperature decrease phase of the thermal cycle is nitrogen, the behavior becomes independent of the atmosphere for the temperature increase portion of the cycle.
Development of Anode Supported Tubular SOFC Components
Authors: Seabaugh Matthew M. , Day Michael , Cummings Steven , Miller Amanda , Menzer Sophie
Published: September 2009

Tubular solid oxide fuel cells present particular design advantages to stack and system development, including robust component strength, and simple sealing approaches in stack design. Anode supported tubular technology provides a path to thin electrolyte membranes through co-sintering during cell manufacturing. In coordination with CoorsTek, NexTech Materials has developed a SOFC fuel cell component for researchers and product developers, (Figure 1). The baseline cell performance for the ASC tubes is shown in Figure 2, demonstrating performance of representative cells at temperatures of 750 and 850{degree sign}C. The cell development has been performed through the evaluation and down-selection of materials and processes to assure performance stability, reproducibility and cost-effectiveness at high volume production.
Tubular Metal Supported SOFC Development for Domestic Power Generation
Authors: Villarreal Igor , Rivas Mikel , Rodriguez-Martinez Lide M. , Otaegi Laida , Zabala Aingeru , Gomez Nuria , Alvarez Mario , Antepara Inigo , Arizmendiarrieta Nagore , Manzanedo Jaio , Olave Mireia , Urriolabeitia Abel , Burgos Nerea , Castro Francisco , Laresgoiti Ander
Published: September 2009

Tubular metal supported SOFC technology has successfully been developed over the past years with the aim at domestic CHP systems below 3 kWe. The basic cell structure consists of a metal porous support, a protective barrier layer, an anode and an electrolyte cofired at 1350ºC. Cathode and contacting layers are subsequently sintered at lower temperatures. Latest achievements include average cell performances of 400 mW/cm2 at 0.7 V and 800ºC, over 350 thermal cycles and more than 1500 hours of steady operation. Several stack concepts are currently being tested and BoP components such as fuel processing, power electronics and control system developed in parallel to achieve a successful micro-CHP proof of concept by the end of 2010.
A Flexible Solid Oxide Fuel Cell Supported on the Thin Porous Metal
Authors: Cho Hyoup Je , Min Park Young , Choi Gyeong Man
Published: September 2009

Metal-supported SOFCs are very attractive due to their high mechanical strength, thermal conductivity, and low material cost. These properties make SOFCs suitable for mobile application as well as the traditional stationary application. Contrary to many researches, using the thin-metal support will be more suitable for potable application because it provides the cell with flexibility, light weight, and good stacking property. In this study, thin metal-supported SOFC (~100μm) was fabricated and tested. Green sheets of thin STS support, Ni-YSZ anode, and YSZ electrolyte were prepared by tape casting method in order to fabricate the single cell. Three tapes were laminated and co-fired at 1300oC in reducing atmosphere. Microstructure of 3-layered cell was examined and the performance was tested with a LSCF cathode at 800oC. Thin and strong metal-supported SOFC was successfully fabricated by co-firing process. Total thickness of the sintered cell was ~80μm. This thin cell showed flexible nature and was easily bent without visible cracks on the electrolyte. The Cr-poisoning of Ni in the anode was occurred during sintering at high temperature, which could lower the cell performance. Cr diffusion barrier may be used in order to enhance the cell performance.
Fabrication of Anode Supported Micro Tubular SOFCS by Dip-Coating Process on NiO/YSZ Hollow Fibers
Authors: Yang Nai-Tao , Tan Xiaoyao , Meng Xiu-Xia , Yin Yimei , Ma Zi-Feng
Published: September 2009

NiO/YSZ hollow fibers were fabricated via a combined phase inversion and sintering technique, where polyethersulfone (PESf) was employed as the polymeric binder and N-methyl-2- pyrrolidone (NMP) as solvent. After sintering at 1400{degree sign}C and being reduced by hydrogen at 800{degree sign}C, the hollow fibers showed a mechanical strength of 178 MPa, conductivity of 772 S⋅cm-1, and porosity of 37.0%, which were used as the porous anode support for MT-SOFCs. A 8% yttria stabilized Zirconia (8YSZ) electrolyte film with a thickness of 10μm was prepared by a dip-coating and co-sintering process on the outer surface of the NiO/YSZ hollow fiber to form anode/electrolyte half cell. A porous LSM layer with a thickness of 15 μm was coated on the surface of the electrolyte film as the cathode to form a single cell. The resultant cells displayed peak power densities of 964, 828 or 480 mW·cm-2 at 800{degree sign}C using H2/O2, H2/Air or CH4/air as the fuel/oxidant gases, respectively.
Foturan® Glass Ceramic - a Substrate for Power Delivering Free-standing µ-SOFC Membranes
Authors: Toelke Rene , Bieberle-Hutter Anja , Rupp Jennifer L. , Gauckler Ludwig J.
Published: September 2009

We investigated Foturan® glass ceramic as a promising substrate material for micro-solid oxide fuel cells (μ-SOFC), including processing and electrochemical characterization of free-standing μ- SOFC membranes. The Foturan® wet etching rate was determined to be 16 μm/min. This results in 31 min etching to fabricate a freestanding μ-SOFC membrane. The maximum power output of μ- SOFC membranes was 209 mW/cm2 at 550{degree sign}C with an open circuit voltage of 0.58 V.
Miniaturized Low-temperature Solid Oxide Fuel Cells with an Yttria-stabilized-zirconia Foil Electrolyte
Authors: Evans Anna , Bieberle-Hutter Anja , Bonderer Lorenz J. , Chen Philipp , Hodel Damian , Rupp Jennifer L. , Gauckler Ludwig J.
Published: September 2009

Micro-solid oxide fuel cells (SOFC) are promising power sources for portable electronic devices. This study presents the fabrication and electrochemical characterization of a new SOFC design which consists of prefabricated parts such as a nickel-mesh anode, a 3 µm thick yttria-stabilized-zirconia (YSZ) foil or a 140 μm thick YSZ-tape electrolyte and a thin-film cathode that are assembled on a Foturan® glass ceramic support structure. Pull-tests revealed a bonding strength of 100 - 200 g between the Ni-mesh anode and the YSZ electrolyte. An open-circuit voltage of 1.0 V and a maximum power density of 0.84 mW/cm2 were measured at 550{degree sign}C for SOFCs comprising a Ni-mesh anode, an YSZ-tape electrolyte and a Pt-paste cathode.
Study on Electrolyte-Supported Single Chamber Solid Oxide Fuel Cell Stack
Authors: Lu Zhe , Wang Jingfeng , Wei Bo , Huang Xiqiang , Wang Zhihong , Su Wenhui
Published: September 2009

Single cell and short stacks supported with electrolyte were prepared and operated under single chamber solid oxide fuel cell (SC-SOFC) condition. The single cell was tested to investigate the ratio of fuel and oxygen in the mixture working gas as well as the operating temperature. Then single electrolyte pellet-supported SC-SOFC stacks with 2 or 3 cells were fabricated and tested. A 2-cell stack could provide an the open circuit voltages (OCV) of 1.66V that was lower than the OCV sum of near 2V for two standing alone SC-SOFC for some addition cells might composed between each possible pair of anode and cathode on the same bulk electrolyte and depressed the OCV of stack. The OCVs of a 3-cell stack were 2.758V and 2.501V, and the maximum power (MP) were 20.76mW and 16.02mW, at 700 oC and 750 oC respectively.
Electrochemical Performance of Nanostructured IT-SOFC Cathodes with Different Morphologies
Authors: Baque Laura , Djurado Elisabeth , Rossignol Cecile , Marinha Daniel , Caneiro Alberto , Serquis Adriana
Published: September 2009

In this work, the electrochemical performance of La0.4Sr0.6Co0.8Fe0.2O3 (LSCF) cathodes was studied for different morphologies. LSCF powders have been prepared by three different methods: an acetic acid-based chemical route, an hexamethylenetetramine (HTMA) chemical route and spray pyrolysis. The cathode films were fabricated by spin coating inks, starting from these powders, onto Ce0.9Gd0.1O1.95 ceramic substrates. We found that nanostructured LSCF samples can be obtained by all methods, but with different morphologies. In particular, spray pyrolysis method allows the attainment of LSCF cathode films with an atypical microstructure (i.e. spherical particle shape, nanometric grain sizes and large and open porosity). We show that the electrochemical properties of LSCF cathodes films strongly depend on microstructure and morphology and cathode polarization resistance can decrease considerably if optimized synthesis parameters are used.
Properties of Ba0.5Sr0.5Co0.8Fe0.2O3-δ Composite Membrane
Authors: Zhu Pei-Yu , Han Min-Fang , Yang Zhi-Bin
Published: September 2009

The perovskite mixed ionic-electronic conducting membranes (MIEC) are widely used in solid oxide fuel cells, oxygen separation and the partial oxidation of methane to syngas. The synthesis process and properties of the composite membrane including the porous support layer and the thin dense layer with the same material, Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF5582), were investigated in the present study. The powders of perovskite structure BSCF5582 for porous support layer were synthesized by solid-state reaction method (SSR) at 1233 K for 2~6 hours, while the powders of BSCF5582 for dense layer were synthesized by citrate-EDTA complexing method (CC-EDTA) after being calcined at 1173 K for 2~6 hours. The support layer with a thickness of 0.6 mm was made by tape calendering process (TCP), and then pre-sintered at 1073 K for 1 h. The dense layer with a thickness of 30 μm was formed by dip-casting process. The composite membrane of BSCF was formed by co-firing the two layers at 1413 K for 10 hours. Porous support layer and dense layer were clearly identified by scanning electron microscopy (SEM). The conductivity of the composite membrane is 35S·cm-1 at 773K. The electrical-conduction behavior of BSCF obeys the p-type small polaron-hopping mechanism.
The Electrochemical and Thermal Performances of Ca3Co4O9-δ as a Cathode Material for IT-SOFCs
Authors: Nagasawa Kensaku , Mentre Olivier , Daviero-Minaud Sylvie , Preux Nicolas , Rolle Aurelie , Nakatsugawa Hiroshi
Published: September 2009

With the aim of application to cathode material in IT-SOFC, 2D misfit layered calcium cobalt oxide Ca3Co4O9-d was studied using XRD, SEM, thermal dilatometory and impedance spectroscopy. Chemical reactivity of Ca3Co4O9-d with electrolyte indicated good compatibility with CGO against generating impunity phase CaZrO3 with YSZ. Thermal expansion coefficient of pure Ca3Co4O9-d exhibited 10.0-11.0×10-6 K-1, which is similar to that of CGO electrolyte. Indeed, we verified a good adherence between electrode thin layer and the electrolyte. Electrochemical property of Ca3Co4O9-d pellet showed good performances, i.e. ASR values are 3.0 and 24.5 Ωcm2 at 700 and 600 ºC in ambient air respectively, in our experimental conditions.
SmBaCo2O5+d and LnBa0.5Sr0.5Co2O5+δ, Potential Cathode Materials for IT-SOFC
Authors: Kim Jung Hyun , Bae Joongmyeon , Cassidy Mark , Connor P. A. , Zhou W. , Irvine John
Published: September 2009

The electrical conductivity of SmBaCo2O5+δ (SBCO) showed a Metal-Insulator Transition (MIT) at about 200åC with maximum conductivity of 570 Scm-1 at 200oC and minimum conductivity 170 Scm-1 at 900oC. The area specific resistance (ASR) of composite cathode (50wt% of SBCO and 50wt% of Ce0.9Gd0.1O2, SBCO:50) on a Ce0.9Gd0.1O2 (CGO91) electrolyte was observed to be 0.05Ωcm2 at 700oC. SmBa0.5Sr0.5Co2O5+δ (SBSCO) electrode was sintered onto CGO91 at 1000oC to form symmetrical cells and exhibited an ASR value of 0.092 Ωcm2 at 700oC. The lowest ASR value was observed when the composite cathode of 50wt% of SBSCO and 50wt% of CGO91 (SBSCO:50) was used and these were 0.10 Ωcm2 at 600oC and 0.013 Ωcm2 at 700oC, respectively. The coefficient of thermal expansion (CTE) was 21.9 x 10-6 K-1 at 700oC. However, the CTE of SBSCO:50 was shown to be 13.6 x 10-6 K-1 at 700oC which are similar to the value of CGO91 electrolyte for intermediate temperature-operating solid oxide fuel cell (IT-SOFC) applications.
Electrochemical Optimization of LSCF/BIT07 as an Alternative Cathode/electrolyte Couple for SOFC
Authors: Letilly Marika , Le Gal La Salle Annie , Joubert Olivier
Published: September 2009

In order to validate the use of BaIn0.3Ti0.7O2.85 (BIT07) as electrolyte material in an intermediate temperature SOFC, its chemical, mechanical and electrochemical compatibilities with the commonly studied MIEC (mixed ionic and electronic conductor) cathode material La0.58Sr0.4Co0.2Fe0.8O3-δ (LSCF) have been checked. X-ray diffraction studies show that the two compounds don't react together below 1000 {degree sign}C. Symmetrical cells cathode/electrolyte/cathode have been prepared at different temperatures in order to study the influence of the formation of a mixed compound at the interface onto the cohesion and studied by SEM observation: for sintering temperatures comprised in the 1000-1150 {degree sign}C, the quality of the interface remains good even after 400 hours at 750 {degree sign}C, contrary to that is observed when YSZ is used instead of BIT07. Using electrochemical impedance spectroscopy, the screen printing parameters of LSCF on BIT07 have been optimized leading to a low Area Specific Resistance (ASR) value of 0.05 Ohm cm² at 700 {degree sign}C.
Surface Adsorption and Stabilization Effect of Iridium in Pt-based Alloy Catalysts for PEM Fuel Cell Cathodes
Authors: Ma Yuguang , Balbuena Perla B.
Published: September 2009

We examine a bimetallic alloy, Pt3Co, modified by addition of Iridium. The ternary alloy, Pt2IrCo, exhibits a strong Pt-segregation tendency to form a Pt-skin surface. The adsorption properties and electrochemical stability of Pt2IrCo(111) surface are studied using density functional theory and compared with Pt(111) and Pt3Co(111) surfaces. It is found that the Pt-skin surface of Pt2IrCo(111) has similar electrochemical stability to the Pt3Co(111) Pt-skin surface. The binding strength of OH is much weaker on the trimetallic Pt-skin surface, suggesting a possible activity enhancement for the oxygen reduction reaction. Further analyses reveal the origin of the catalytic activity and stability enhancement for the alloy.
Analysis of Reactant Gas Transport in Catalyst Layers; Effect of Pt-loadings
Authors: Sakai Kei , Sato Kazuyuki , Mashio Tetsuya , Ohma Atsushi , Yamaguchi Koichi , Shinohara Kazuhiko
Published: September 2009

An analytical in-situ technique was utilized to evaluate reactant gas transport resistance (Rother) in catalyst layers (CLs). It was found that Rother was increased with the decrease of Pt-loadings of the CLs although their thickness was decreased. Effective Knudsen diffusion coefficient was calculated from the pore size distribution and the porosity. It was estimated almost steady regardless of the Pt-loadings. To understand the increase of Rother, a simple transport model was established including Knudsen diffusion resistance in secondary pores and the local transport resistance around the Pt surface. Knudsen diffusion resistance should be decreased in lower Pt-loadings because of the shorter transport length. On the other hand, it was considered that the local transport resistance was increased with decreasing of the effective Pt surface area. Hence, that the effective Pt surface area might be one of the important factors for Rother in the CLs, especially in the lower Pt-loadings.
Calcium Pumps in Health and Disease
Authors: Brini Marisa , Carafoli Ernesto
Published: September 2009

Ca2+-ATPases (pumps) are key actors in the regulation of Ca2+in eukaryotic cells and are thus essential to the correct functioning of the cell machinery. They have high affinity for Ca2+and can efficiently regulate it down to very low concentration levels. Two of the pumps have been known for decades (the SERCA and PMCA pumps); one (the SPCA pump) has only become known recently. Each pump is the product of a multigene family, the number of isoforms being further increased by alternative splicing of the primary transcripts. The three pumps share the basic features of the catalytic mechanism but differ in a number of properties related to tissue distribution, regulation, and role in the cellular homeostasis of Ca2+. The molecular understanding of the function of the pumps has received great impetus from the solution of the three-dimensional structure of one of them, the SERCA pump. These spectacular advances in the structure and molecular mechanism of the pumps have been accompanied by the emergence and rapid expansion of the topic of pump malfunction, which has paralleled the rapid expansion of knowledge in the topic of Ca2+-signaling dysfunction. Most of the pump defects described so far are genetic: when they are very severe, they produce gross and global disturbances of Ca2+homeostasis that are incompatible with cell life. However, pump defects may also be of a type that produce subtler, often tissue-specific disturbances that affect individual components of the Ca2+-controlling and/or processing machinery. They do not bring cells to immediate death but seriously compromise their normal functioning.
Computation of All Stabilizing PID Gain for Second‐Order Delay System
Authors: Farkh Rihem , Laabidi Kaouther , Ksouri Mekki
Published: September 2009

The problem of stabilizing a second‐order delay system using classical proportional‐integral‐derivative (PID) controller is considered. An extension of the Hermite‐Biehler theorem, which is applicable to quasipolynomials, is used to seek the set of complete stabilizing PID parameters. The range of admissible proportional gains is determined in closed form. For each proportional gain, the stabilizing set in the space of the integral and derivative gains is shown to be either a trapezoid or a triangle.
Rigorous Solution to Plane Wave Scattering by an Arbitrary-Shaped Particle Embedded into a Cylindrical Cell of Similar Material
Authors: Valagiannopoulos Constantine A.
Published: September 2009

An infinite cylinder of arbitrary shape is embedded into a circular one, and the whole structure is illuminated by a plane wave. The electromagnetic scattering problem is solved rigorously under the condition that the materials of the two cylinders possess similar characteristics. The solution is based on a linear Taylor expansion of the scattering integral formula which can be useful in a variety of different configurations. For the specific structure, its own far field response is given in the form of a double series incorporating hypergeometric functions. The results are in good agreement with those obtained via eigenfunction expansion. Several numerical examples concerning various shape patterns are examined and discussed.
Fine Structures of 8‐G‐1‐(p‐YC6H4C ≡ CSe)C10H6 (G = H, Cl, and Br) in Crystals and Solutions: Ethynyl Influence and Y‐ and G‐Dependences
Authors: Hayashi Satoko , Yamane Kentaro , Nakanishi Waro
Published: September 2009

Fine structures of 8‐G‐1‐(p‐YC6H4C ≡ CSe)C10H6 [1 (G = H) and 2 (G = Cl): Y = H (a), OMe (b), Me (c), F (d), Cl (e), CN (f), and NO2 (g)] are determined by the X‐ray analysis. Structures of 1, 2, and 3 (G = Br) are called A if each Se–Csp bond is perpendicular to the naphthyl plane, whereas they are B when the bond is placed on the plane. Structures are observed as A for 1a–c bearing Y of nonacceptors, whereas they are B for 1e–g with Y of strong acceptors. The change in the structures of 1e–g versus those of 1a–c is called Y‐dependence in 1. The Y‐dependence is very specific in 1 relative to 1‐(p‐YC6H4Se)C10H7 (4) due to the ethynyl group: the Y‐dependence in 1 is almost inverse to the case of 4 due to the ethynyl group. We call the specific effect “Ethynyl Influence.” Structures of 2 are observed as B: the A‐type structure of 1b changes dramatically to B of 2b by G = Cl at the 8‐position, which is called G‐dependence. The structures of 2 and 3 are examined in solutions based on the NMR parameters.
Classification of Nonenzymatic Homologues of Protein Kinases
Authors: Anamika K. , Abhinandan K. R. , Deshmukh K. , Srinivasan N.
Published: September 2009

Protein Kinase-Like Non-kinases (PKLNKs), which are closely related to protein kinases, lack the crucial catalytic aspartate in the catalytic loop, and hence cannot function as protein kinase, have been analysed. Using various sensitive sequence analysis methods, we have recognized 82 PKLNKs from four higher eukaryotic organisms, namely,Homo sapiens,Mus musculus,Rattus norvegicus, andDrosophila melanogaster. On the basis of their domain combination and function, PKLNKs have been classified mainly into four categories: (1) Ligand binding PKLNKs, (2) PKLNKs with extracellular protein-protein interaction domain, (3) PKLNKs involved in dimerization, and (4) PKLNKs with cytoplasmic protein-protein interaction module. While members of the first two classes of PKLNKs have transmembrane domain tethered to the PKLNK domain, members of the other two classes of PKLNKs are cytoplasmic in nature. The current classification scheme hopes to provide a convenient framework to classify the PKLNKs from other eukaryotes which would be helpful in deciphering their roles in cellular processes.
Fixed Point Theory for Admissible Type Maps with Applications
Authors: Agarwal Ravi P. , O'Regan Donal
Published: September 2009

We present new Leray-Schauder alternatives, Krasnoselskii and Lefschetz fixed point theory for multivalued maps between Fréchet spaces. As an application we show that our results are directly applicable to establish the existence of integral equations over infinite intervals.
Fuzzy Stability of the Pexiderized Quadratic Functional Equation: A Fixed Point Approach
Authors: Wang Zhihua , Zhang Wanxiong
Published: September 2009

The fixed point alternative methods are implemented to give generalized Hyers-Ulam-Rassias stability for the Pexiderized quadratic functional equation in the fuzzy version. This method introduces a metrical context and shows that the stability is related to some fixed point of a suitable operator.
Sketch-Based Spatial Queries for the Retrieval of Human Locomotion Patterns in Smart Environments
Authors: de Silva Gamhewage C. , Yamasaki Toshihiko , Aizawa Kiyoharu
Published: September 2009

A system for retrieving video sequences created by tracking humans in a smart environment, by using spatial queries, is presented. Sketches made with a pointing device on the floor layout of the environment are used to form queries corresponding to locomotion patterns. The sketches are analyzed to identify the type of the query. Directional search algorithms based on the minimum distance between points are applied for finding the best matches to the sketch. The results are ranked according to the similarity and presented to the user. The system was developed in two stages. An initial version of the system was implemented and evaluated by conducting a user study. Modifications were made where appropriate, according to the results and the feedback, to make the system more accurate and usable. We present the details of the initial system, the user study and the results, and the modifications thus made. The overall accuracy of retrieval for the initial system was approximately 93%, when tested on a collection of data from a real-life experiment. This is improved to approximately 97% after the modifications. The user interaction strategy and the search algorithms are usable in any environment for automated retrieval of locomotion patterns. The subjects who evaluated the system found it easy to learn and use. Their comments included several prospective applications for the user interaction strategy, providing valuable insight for future directions.
Low‐Latency Wireless Data Transfer for Motion Control
Authors: de Boeij Jeroen , Haazen Maarten , Smulders Peter , Lomonova Elena
Published: September 2009

This paper discusses a new approach for wireless motion control. Existing wireless techniques suffer from large closed loop delays of several milliseconds, which is unacceptable in precision motion systems. These large delays are mainly caused by the protocol used, since these are optimized for transferring large amounts of data, not to minimize transmission delay. A new protocol and wireless system are proposed that reduce the closed loop transmission delay to less than 300 microseconds. The system has been verified in a real control system, and measurements show the performance, which is more than ten times better than existing techniques.
Nonlinear Nonconvex Optimization by Evolutionary Algorithms Applied to Robust Control
Authors: Cervera Joaquín , Baños Alfonso
Published: September 2009

This work focuses on the problem of automatic loop shaping in the context of robust control. More specifically in the framework given by Quantitative Feedback Theory (QFT), traditionally the search of an optimum design, a non convex and nonlinear optimization problem, is simplified by linearizing and/or convexifying the problem. In this work, the authors propose a suboptimal solution using a fixed structure in the compensator and evolutionary optimization. The main idea in relation to previous work consists of the study of the use of fractional compensators, which give singular properties to automatically shape the open loop gain function with a minimum set of parameters, which is crucial for the success of evolutionary algorithms. Additional heuristics are proposed in order to guide evolutionary process towards close to optimum solutions, focusing on local optima avoidance.
Omega-3 Polyunsaturated Fatty Acids (n-3 PUFAs) in Cardiovascular Diseases (CVDs) and Depression: The Missing Link?
Authors: Chang Jane Pei-Chen , Chen Yi-Ting , Su Kuan-Pin
Published: September 2009

Background. Based on epidemiological data, clinical trials, and meta-analytic reviews, omega-3 polyunsaturated fatty acids (n-3 PUFAs) seem to be a biological link between depression and cardiovascular diseases (CVDs).Presentation. Involvement of n-3 PUFAs in depression and CVDs may be associated with a chronic, low-grade, inflammation. We hypothesize that n-3 PUFAs link depression and CVDs via “PUFA-prostaglandin E2 (PGE2) cascade.”Testing. To further support our hypothesis, case-control studies are needed to test the role of COX2 and PLA2 functions in depression and in CVDs. In addition, the effects of n-3 PUFAs on cardiovascular markers in depression and on depressive symptoms in CVDs should be investigated in clinical trials. Finally, the effects of manipulating COX2 and PLA2 functions on depression-like behaviors and cardiovascular functions could be explored in animal studies.Implications. n-3 PUFAs might be a promising treatment for both cardiovascular diseases and depression via its anti-inflammatory, cardioprotective, and neuroprotective effects.
What Is the Role of Serological Markers in IBD? Pediatric and Adult Data
Authors: Dubinsky Marla
Published: September 2009

Physicians rely heavily on the presence of disease markers to support or even at times modify their clinical impression for certain diseases that can only be diagnosed clinically. Typically these markers play an important role in helping to establish a diagnosis and to evaluate the activity of a chronic disease over time. The diagnosis of inflammatory bowel disease (IBD), however, is not based solely on clinical grounds. Invasive endoscopic and radiological as well as histopathological criteria need to be met in order to make a correct diagnosis and differentiate disease subtypes. The search for novel diagnostic approaches that accurately distinguishes a group of patients with IBD from those unaffected by the disease has become a focus in IBD research. This search, however, has taken a very exciting turn in the direction of finding biologic and genetic markers that can assess the natural history and predict the course of individual’s disease including response to treatments over time.
Risk/Benefit Strategies Must Be Employed in the Management of Pediatric Crohn’s Disease
Authors: Hyams Jeffrey S.
Published: September 2009

Clinicians caring for children with Crohn’s disease must consider the long-term implications of therapeutic interventions and cumulative diagnostic studies in their patients whose disease duration will be measured in decades. There is evidence of the increased severity of pediatric Crohn’s disease compared to its adult counterpart, its frequent co-morbid growth disturbances, and the frequent need for aggressive medical therapies including immunomodulators and biological agents. The initial management of most children diagnosed with Crohn’s disease involves enteral nutritional support, corticosteroids, and immunomodulators. Corticosteroids, while initially helpful in decreasing signs and symptoms of disease, are occasionally ineffective, generally do not heal mucosa, impair growth, and are frequently associated with a state of corticosteroid dependency. Immunomodulators are effective maintenance therapies with corticosteroid sparing effects, but have no value in the acutely ill child. The emergence of biological therapy with its impressive record of rapid efficacy and use as maintenance therapy has prompted discussion of its incorporation into initial management, but has also raised concerns about who are the most suitable candidates, which if any medications can be used concomitantly, and long-term safety. The combined use of thiopurines and anti-TNF agents may predispose to a rare and uniformly fatal lymphoma. Identification of children at high risk for complicated disease may allow us to better evaluate risk/benefit in newly diagnosed children, and biologic agents are likely to assume an increasing role in primary therapy in those deemed at highest risk. Long-term observations will determine whether biologics will change natural history and demonstrate adequate safety.