bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatially Resolved Electrochemical Performance in a Segmented Planar SOFC
Authors: Schiller Guenter , Bessler Wolfgang G. , Friedrich K. A. , Gewies Stefan , Willich Caroline
Published: May 2009

Spatially inhomogeneous distributions of current density and temperature in solid oxide fuel cells (SOFC) can contribute significantly to electrode degradation, thermomechanical stresses, and reduced efficiency. A combined experimental and modeling study of the spatial distribution of electrochemistry was performed in order to determine local effects. A planar anode-supported SOFC single cell was locally characterized in a 4x4-segmented cell arrangement in dependence of gas composition and fuel utilization. A two-dimensional elementary kinetic electrochemical model was used to quantitatively interpret experimental observations. The model was validated by comparison to experiments under a wide range of operating conditions. When the cell was operated at high fuel utilization, both measurements and simulations show a strong variation of the electrochemical performance along the flow path. The simulations predict a considerable gradient of gas-phase concentrations along the fuel channel and through the thickness of the porous anode, while the gradients are lower at the cathode side.
Evaluation of Impurity Levels in Real SOFC Stacks and Modules
Authors: Yamaji Katsuhiko , Kishimoto Haruo , Xiong Yue-Ping , Horita Teruhisa , Brito Manuel E. , Yokokawa Harumi
Published: May 2009

Reliability of SOFC stacks/modules were investigated in NEDO SOFC project from FY2005-FY2007. In this project, the same technique of detecting the impurities inside the cell component using the SIMS (Secondary Ion Mass Spectrometry) machine was applied to four different stacks and modules before and after long term power generation tests. In cathodes, Cr and S were mainly detected. On the other hand, many elements like Na, Al, Si and Sr were detected in anodes. These impurities may come from components in the system or gases like water vapors.
Measurement of Input Energy of LNG-based Gaseous Fuels with Capillary-typed Thermal Mass Flowmeter for Fuel Cells
Authors: Tanaka Yohei , Kato Ken , Negishi Akira , Nozaki Ken , Kato Tohru
Published: May 2009

With capillary-typed thermal mass flowmeters (ctMFM) primarily calibrated with methane, it was investigated to measure input energy of LNG-based gaseous fuels to fuel cell systems. Energy flow rate can be expressed as Q× CLNG× FR where Q is heating value, CLNG is conversion factor from CH4 to the fuels, and FR is reading of ctMFM expressed as CH4 flow rate. Strong and negative correlation was observed between Q and CLNG, which will reduce deviation of the term "Q× CLNG" to 20% of deviation of Q. Calibration of ctMFM with an average composition of the fuels is necessary to obtain the correction factor Q× CLNG. It was found that input energy of LNG-based fuels can be measured with 40-100% range of ctMFM within {plus minus}1.5% uncertainty even if heating value of the fuels deviates by {plus minus}4.0%.
One-Dimensional Modeling of a Liquid Tin Anode Solid Oxide Fuel Cell
Authors: Sikha Godfrey , McPhee William A. , Zhang Qi , Koslowske Mark , Tao Tom , White Ralph
Published: May 2009

The integration of electronics into modern warfare has seen the creation of a niche market for portable power generators that run on military logistic fuel (JP-8). The 2 stage chemical/electrochemical reaction of the fuel on the anode side of the Liquid Tin Anode (LTA)-SOFC allows a range of carbonaceous fuels to be directly utilized at high efficiencies. However, the LTA-SOFC technology currently has a peak power density of 120 mW.cm-2 on JP-8. A better understanding of the anode side kinetics, thermodynamic, and transport properties would allow further optimization of this technology. A physics-based model of the LTA-SOFC was built. The model was initially developed for simple fuel before incorporation of heavy hydrocarbon fuels. This paper reports on the modeling efforts to date.
Methane Dilution Effect on a 5 kW Tubular SOFC System
Authors: De Benedictis Ferrante , Gariglio Marcello , Delloro Francesco , Santarelli Massimo , Orsello Gianmichele , Calì Quaglia Michele
Published: May 2009

The EOS Project carries on an industrial research on Stationary Fuel Cells based on the SOFC technology developed by Siemens, through a co-operation between TurboCare S.p.A. and Politecnico di Torino. This paper describes testing of the 5kW Alpha 6 SOFC with a low heating value fuel. A factorial analysis has been applied considering three factors: methane percentage, stack temperature and current. The obtained data have been analyzed using the Analysis of Variance (ANOVA) for every dependent variable and a non-linear regression model for the voltage. Those models were used to evaluate the performance of the system. The analysis has focused on how fuel dilution affects the local fuel utilization in different sectors of the stack.
PEM Fuel Cell Systems for Distributed Energy: Actual Performance, Lifetime and Reliability of a Pure Hydrogen Pre-commercial System
Authors: Ferraro Marco , Sergi Francesco , Brunaccini Giovanni , Dispenza Giorgio , Andaloro Laura , Briguglio Nicola , Antonucci Vincenzo
Published: May 2009

In the framework of a national research program the development of fuel cell systems ranging from 1 to 5 kW of power and based on either solid polymer (PEFC) or solid oxide (SOFC) technology are in progress. In this paper, the demonstration of pre-commercial PEFC systems fed with hydrogen and developed in cooperation with NUVERA is described. The systems have been evaluated in order to determine theirs limits and capacity in relation to start-up time, response time, consumption, efficiency, reliability, etc. It has currently reached 2,000 working hours of continuous performance with variable loads that simulate those of a typical residential dwelling.
A High A High Efficiency PEFC System Development for Long-Range Cruising Autonomous Underwater Vehicles (LCAUVs)
Authors: Yoshida Hiroshi , Hyakudome Tadahiro , Ishibashi Shojiro , Sawa Takao , Tsukioka Satoshi , Tahara Junichiro , Aoki Taro , Tani Toshihiro , Iwata Mitsuyoshi , Takuya Moriga
Published: May 2009

Development of an underwater platform which travels and surveys across entire oceans for the research into the global change, ocean-trench earthquake, and biodiversity is addressed in Japan. The first prototype LCAUV powered by polymer electrolyte membrane fuel cell (PEFC) system named Urashima, which marked the world record of cruising distance of 317 km, had been developed since 1998. Key technology development including a fuel cell system for the second LCAUV started in 2007. A high efficiency PEFC developed by MHI for the LCAUV runs with 60 % of efficiency at an operation point. A function test for a new concept system, which consists of reduced auxiliary devices, using the PEFCs was made. The test results have positive outcomes.
Cold Start and Freeze/Thaw Cycles Effect on PEFMC Performances
Authors: Pinton Eric , Antoni Laurent , Fourneron Yannick , Rosini Sébastien
Published: May 2009

Water production is one of the most interesting characteristic of Proton Exchange Membrane Fuel Cell (PEMFC). However it is also one of the most restricting points, especially for automotive application on winter conditions. In order to further assess the cold operating mechanisms and their effect on durability, specific aging experiments were performed on isothermal single cells. It was found that drying process itself, without start up at sub-zero temperature, can lead to significant degradations. Moreover, 140 freeze/thaw cycles of a fully hydrated MEA have little effect on the FC performances (0.004% cycle-1 at 0.5 A cm-2). Furthermore, successive cold starts with FC starving affect significantly the FC performances. Degradation rates are at least 100 times higher than the one obtained for successive freeze/thaw cycles applied of a non dried cell. This would mean that ice produced during cold start doesn't locate at the same place than the one produced during freeze/thaw cycles.
Architecture Analysis, Modelling and Simulation of PEM Fuel Cell Systems for Aircraft Applications
Authors: Schumann Peter , Graf Christian , Kallo Josef , Friedrich K. A.
Published: May 2009

Fuel cell systems are regarded to be a promising solution for future electrical energy generation on board of commercial aircrafts. In addition to an improved efficiency such systems offer the opportunity of producing water usable for on-board purposes and provide additional functions like inertization (providing a non-inflammable atmosphere) of the jet fuel tank. We present an evaluation and assessment of different system architectures as well as experimental results under low pressure operation. Also complete system modeling is presented and the dynamic system behavior is analyzed.
Parametric Study of a Single Cell PEM Fuel Cell
Authors: Sierra Juan M. , Sebastian Pathiyamattom J. , Gamboa Sergio A.
Published: May 2009

A 3D single cell model of a proton exchange membrane fuel cell (PEMFC) was developed using a computational fluid dynamics software (Fluent 6.3.26). The effect of operating conditions such as pressure, temperature and humidity on the performance of fuel cell was investigated. The study was focused on the activation losses and ohmic resistance. Simulations were performed at three different temperatures 25, 50 and 80 Celsius degrees, at three different gas inlet pressures 1, 2 and 3 atmospheres, and three relative humidity's 25, 50 and 100%. The best results were found when the PEMFC worked at high operating conditions. The analysis showed good agreement with the literature data. The single cell model provided a clear understanding of the influence of operating conditions in the irreversibilities that take place in PEM fuel cells.
Analysis and Optimization of the Cell Design of a PEMFC-Stack
Authors: Pawlik Juergen , Chmielewski Nils , Scholta Joachim , Lehnert Werner
Published: May 2009

Stack modeling and various experiments were performed to enhance stack performance, robustness, lifetime and to lower the degradation rates. The method to analyze and optimize the cell design of the PEMFC-Stack is based on experimentally supported modeling. For modeling the stack, CFD-calculations using Fluent{trade mark, serif} software were performed. The cell designs were subsequently experimentally investigated by polarization curves, gas utilization characterization measurements for anode and cathode as well as current density distribution measurements. With the improved cell design, the stack shows a more equal current density distribution, a significant better performance, an enhancement of the robustness and smaller degradation rates.
Startup-Procedures for a HT-PEMFC Stack
Authors: Scholta Joachim , Kuhn Robert , Wazlawik Stefan , Jörissen Ludwig
Published: May 2009

Up to now, the startup of HT-PEMFC is either requiring starting temperatures of 80 {degree sign}C or more, or will result in a significant cell degradation. In this contribution, investigations on low temperature startup and shutdown procedures are presented. These procedures allow the reduction of the startup temperature down to levels in the range of 60 {degree sign}C without permanently damaging the cell, thus allowing to strongly reduce time and auxiliary energy demand for cell startup. The startup procedure is derived from water vapour pressure data of H3PO4 and is investigated using modelling techniques. The results were experimentally confirmed by repeated startup cycles for different operation parameter sets.
Assessment of a Dedicated On-Site Cell Voltage Monitor for Fuel Cell Systems
Authors: Mulder Grietus , Coenen Peter , Van Bogaert Gilbert , Weyen Dominique , Jacobs Geert , De Ridder Fjo , Martens Adwin
Published: May 2009

Laboratory high performance test equipment is too expensive and bulky for on-site fuel cell stack evaluation. Yet safety assessments show that cell voltage monitoring is a crucial element in operating a fuel cell system. In this paper a dedicated cell voltage monitoring system for on-site applications is evaluated. It describes the specific concept of the on-site monitoring system, shows measurement results for safety, control and long-term evaluation and presents a comparison of communication protocols.
Development of Analytical Techniques to Study H2S Poisoning of PEMFCs and Components
Authors: Brosha Eric L. , Rockward Tommy , Uribe Francisco A. , Garzon Fernando H.
Published: May 2009

Polymer electrolyte membrane fuel cells are sensitive to impurities. H2S at the ppb level will impact fuel cell performance. It is important to quantify H2S adsorption and issues such as permeation and crossover rates become extremely important. Experimental methods have been developed to quantify H2S adsorption onto surfaces and to quantify H2S permeation through Nafion® using common and inexpensive Ag/AgS ion-probes. In addition to calculating the H2S uptake on commonly used XC-72 and Pt/XC-72 materials, the H2S permeability through dry and humidified Nafion® membranes was also studied using specialized techniques. A sulfide anti-oxidant buffer solution was used to trap and concentrate trace quantities of H2S during the course of the measurement. Crossover experiments were conducted for up to 24 hours in order to achieve sulfide ion concentrations high enough to be precisely determined by subsequent titration. We have confirmed H2S crossover in Nafion® membranes and have calculated preliminary rates of crossover.
Optimization of the Conductivity and Passivity Properties of Passive Films on Stainless Steels used as Bipolar Plates in PEFC
Authors: Antoni Laurent , Andre Johan , Petit Jean-Pierre
Published: May 2009

The parameters responsible for electrical contact resistance between a stainless steel bipolar plate and a carbon support in a PEFC has been investigated. Roughness of the bipolar plate is useful but its topography should be adapted to the type of used GDL. Bulk composition of the alloy also plays a role, because it defines the quantity of alloying elements susceptible to participate to the passive film growth, but this role appears secondary. Indeed, passivation pre-treatment can deeply modify both structure and composition of the passive layer as investigated on AISI 316L and 904L steels, until reducing the initial electrical contact resistance at a level comparable to graphite. A low-cost surface treatment could thurs represent a good compromise between using as-received stainless steel plates and deposition precious metals. Compared to bright annealed state, initial ECR is divided by a factor 20 but raised slightly after 500 hours of operation.
Verification of Measurement Method of Current Distribution in Polymer Electrolyte Fuel Cells
Authors: Izumi Masaaki , Gotoh Yuji , Yamanaka Takayuki
Published: May 2009

The aim of the present work is to establish a new technique that can measure current distribution in a Polymer Electrolyte Fuel Cell (PEFC) without contact with the object. When a fuel cell is operated, a magnetic field is caused around the fuel cell by a generated current. The magnetic field strength is measured with a magnetic sensor, and then it is converted to the value of the generated current with the Biot-Savart's law. This technique was verified under the PEFC operating conditions with a specific separator, which could measure real currents in the PEFC. The current distribution determined from a magnetic field is proportional to the real current distribution measured with the specific separator. It appeared that the present technique was useful for measuring the current distribution in PEFCs.
Stainless Steel Bipolar Plates.-Commercial and Technical Feasibility Study for Mass Production in Mexico
Authors: Correa Fernando , Arredondo Gerardo , Meas Yunny , Arriaga Luis Gerardo , Orozco German
Published: May 2009

Stainless steel Type 444 is an excellent material for use in the manufacture of bipolar plates. It is comparable to austenitic stainless steel Type 316 in its corrosion resistance but has the advantage of being half less expensive. The coatings that had the best performance were chromium carbide and gold. Corrosion resistance of ferritic stainless steels 439 and 441, with a Ni-Cr and NiCrAlY coatings, were evaluated under simulated cathodic PEMFC environment. The corrosion current density of the coatings is higher than the US Department of Energy target value and they are not a feasible option to be used in bipolar plates for fuel cell applications. A possible explanation of the inadequate corrosion resistance is the segregation of the elements. The XRD and SEM measurements indicate that the corrosion mechanisms are different for NiCr and NiCrAlY. We have concluded that it is technically possible to produce bipolar plates in Mexico.
Degradation Study of PFSA Polymer Electrolytes: Approach from Decomposition Product Analysis
Authors: Takasaki Mari , Nakagawa Yoshitsugu , Sakiyama Yoko , Tanabe Kenji , Ookubo Kenji , Sato Nobuyuki , Minamide Tomohiro , Nakayama Hiroshi , Hori Michio
Published: May 2009

Fuel cell operation tests (I) and hydrogen peroxide vapor exposure tests with PFSA (perfluorosulfonic acid) polymer membranes (II) were carried out, and the decomposition products of PFSA polymer during the tests were examined mainly by NMR. (I) After OCV-hold and load cycling tests, we analyzed extracts from electrodes separated from a single cell, identifying six decomposition products in the extracts. The total amount generated from the OCV-hold test exceeded that generated from the load cycling test, as well as fluoride ion release rate (FRR). (II) Hydrogen peroxide vapor exposure tests at 90 and 100{degree sign}C under 3 humidity conditions were carried out with Nafion® 112 and Nafion® NRE-212. Decomposition products other than fluoride ions accounted for a significant portion of degradation weight loss, and their generation rates were not proportional to FRR, suggesting the presence of multiple PFSA degradation mechanisms.
Assessment of Methanol Crossover Phenomenon of SPEEK/TPA/MCM-41 and SPEEK/TPA/Y-zeolite Composite Membranes for Fuel Cell Application
Authors: Bello M. , Zaidi S. M. J. , Rahman S. U.
Published: May 2009

Development of alternative membranes different from Nafion® membranes is among the approaches being pursued to resolve the methanol crossover problem in the direct methanol fuel cell (DMFC). This paper reports comparison of methanol crossover behavior of SPEEK-based composite membranes prepared for use in the DMFC. The composite membranes were prepared by embedding different proportions (10-40 wt %) of inorganic proton conducting material (tungstophosphoric acid (TPA)/MCM-41) and (TPA)/Y-zeolite) into SPEEK polymer matrix. Methanol transport through these membranes was studied using potentiometric technique. The SPEEK/TPA/MCM-41 composite membranes showed lower permeability values of 0.57 x 10-8 cm 2 s-1 - 1.73 x 10-8 cm 2 s-1 compared to the SPEEK/TPA/Y-zeolite composite membranes, which showed permeability values of 2.12 x 10-8 cm2 s-1 - 7.04 x 10-8 cm 2 s-1. These values are low compared to that of pure SPEEK membrane; 4.41 x 10-8 cm2s-1 except the 40wt % TPA/Y-zeolite loading that has a higher permeability value of 7.04 x 10-8 cm2 s-1. Better reduction in methanol permeation was observed with lower loadings of the inorganic material (TPA/MCM-41 or TPA/Y-zeolite) than with higher loadings. The membranes are thermally stable up to 160 ºC. Therefore, these membranes have potential to be used in direct methanol fuel cell due to their low methanol permeability, good thermal stability and moderate cost.
Planar Structure μDMFCs
Authors: Specchia Stefania , Icardi Ugo A. , Spinella Corrado , Baglio Vincenzo , D'Urso Claudia , Stassi Alessandro , Antonucci Vincenzo , Aricò Antonino S. , D'Arrigo Giuseppe
Published: May 2009

A design of a µDMFC using a polymeric substrate was reported. Different cell configurations were realized, tested and evaluated. It was observed that the open circuit voltage varied significantly as a function of the membrane humidification and distance between anode and cathode channels in this planar design. In the presence of a large distance between the anode and cathode channel, the OCV reached 0.97 V. This high OCV reflects the absence of methanol cross-over due to the specific planar design. Unfortunately, the cell resistance limited the performance. A maximum power density (IR-free) of 1.1 mW cm-2 (active area) was achieved at room temperature with the smallest distance between anode and cathode (0.25 mm).
Passive Fuel-Feed Minature DMFCs
Authors: Ohashi Masakazu , Guo Zhen , Wan Niangfan , Kuohao Tseng , Mashiko Kouichi , Mochizuki Masataka
Published: May 2009

We propose a novel passive fuel feeding system for DMFC applications. This system consists of fuel tank, wick structure and pressurized chamber which is referred to chemical pump in this report. The fuel is a mixture of methanol and some chemicals that can generate non-condensable gas in the chemical pump. The methanol fuel is pushed into fuel cell stack by the pressure of non-condensable gas in the chemical pump.
Sulfonated Poly(Phthalazinone Ether Sulfone Ketone)/Poly(Vinylidene Fluoride) Blend Membranes for Direct Methanol Fuel Cell
Authors: Wang Ming , Zhu Hong , Zhao Ting , Yang Yu-Guo
Published: May 2009

SPPESK/PVDF blend membranes with different contents of PVDF were prepared by casting process. Scanning electron microscopy (SEM), liquid uptake, swelling degree, proton conductivity, methanol permeability and longevity of blend membranes were investigated. SEM indicates that phase separation exists in blend membranes. Liquid uptake, swelling degree, proton conductivity and methanol permeability collectively decrease as the content of PVDF increases. The addition of PVDF in blend membranes suppresses swelling degree of SPPESK's hydrophilic part, improves mechanical stability. Though the proton conductivity of blend membranes reduces to a certain extent, their methanol resistant performance remarkably enhances. Oxidation stability test indicates that the longevity of blend membranes is extended due to the addition of PVDF. Based on the preliminary results, it can be concluded that the polymer blends of SPEEK/PVDF can be used as a candidate membrane materials for direct methanol fuel cells (DMFC) applications.
Effect of Impurity on Direct Methanol Fuel Cell (DMFC) Discontinuous Operation Performance
Authors: Nishimura Yasuo , Matsuyama Megumi , Nagai Isao , Yamane Masataka , Yanagida Masahiro , Miyazaki Yoshinori
Published: May 2009

Effect of impurity on direct methanol fuel cell (DMFC) performance was investigated using single cell under discontinuous operation with constant current mode. Ethanol and Na+ were selected as candidate organic compound and inorganic ion for impurities of methanol, respectively. In the case of the fuel including ethanol, rapid cell voltage drop was observed in the early period in each repetitive run. However, after the rapid cell voltage drop, cell voltage behavior approached to that with reference fuel in each repetitive run, and accumulation of adverse effect with repetition of the run was scarce. Rapid cell voltage drop was approximately proportional to the logarithm of concentration of ethanol. In the case of the fuel including Na+, even though the rapid cell voltage drop was not observed, an adverse effect accumulated with repetition of the run and the decrease of cell voltage gradually increased with repetition of the run.
Start-up Behavior of Fuel Processing Systems
Authors: Samsun Remzi C. , Döll Christiane , Peters Ralf , Pasel Joachim , Stolten Detlef
Published: May 2009

The Institute of Energy Research - Fuel Cells (IEF-3) develops fuel processing systems for APU applications based on autothermal reforming of middle distillates. The long term stability of reforming using commercial diesel fuel and desulphurised Jet A-1 has already been proven using innovative reactors. A special requirement from the system is the capability to be brought into operation in the fastest time possible. Three systems for different fuel cell types were designed. For each system, necessary reactors were identified and modeled mostly based on reactors developed and tested in Juelich. Afterwards, the related reactor models were combined with each other with the aim of efficient heat integration to form fuel processing systems for an SOFC, a PEFC and an HT-PEFC. Start-up strategies were developed and simulated for each system. Finally, the start-up strategy for the HT-PEFC system was further optimized.
Jet Fuel Desulfurizer for Fuel Cell powered APU
Authors: Alptekin Gokhan , Jayaraman Ambalavanan , Dubovik Margarita , Schaefer Matt , Monroe John
Published: May 2009

The effective utilization of logistic fuels in fuel cell applications requires removal of refractory sulfur species (organosulfur compounds) to below 0.1 ppm. TDA has developed a sorbent-based fuel desulfurization system that can easily integrate with any fuel cell fuel processor. TDA's desulfurizer removes all of the refractory organic sulfur compounds from the military fuels (both JP-5 and JP-8), while it is still in the liquid phase and reduces the total fuel sulfur content to sub-ppm levels (e.g., less than 0.1 ppmw). TDA has built a 4-bed prototype jet fuel desulfurization system that could be integrated with a 1.5 kW fuel cell powered APU.
Direct Fuel Cell Materials Experience
Authors: Yuh Chao-Yi , Hilmi Abdelkader , Farooque Mohammad , Leo T. , Xu G.
Published: May 2009

The Direct Fuel Cell® (DFC®) power plant is an emerging high efficiency, ultra-clean electric power generation system. The power-producing block is the carbonate fuel cell, which uses alkali carbonate electrolyte and operates at ~550-650{degree sign}C. Its internal reforming process results in a simpler, more efficient and cost-effective energy conversion system. Since 2000, FCE has placed around the world approximately 85 units ranging from 250kW to 2.4 MW, accumulating extensive materials experience (up to >30,000h). Consistent DFC stack durability and performance improvement, and substantial cost reduction have been demonstrated. This paper describes status of DFC field products, stack material durability, power output increase, and cost reduction.
From Distributed Generation to Smart Grids: Integration of H2 and Renewable Energy towards Zero Emissions Home
Authors: Andaloro Laura , Ferraro Marco , Brunaccini Giovanni , Sergi Francesco , Antonucci Vincenzo
Published: May 2009

Actual trend in stationary energy sector is the zero-emissions-home, in which aim is to limit or avoid taking energy from the grid. The production of energy on-site requires the use of innovative, low environmental impact technologies. To this end, a small laboratory-house was built in which a photovoltaic (PV) plant with an energy-storage battery system is installed, a fuel cell (FC) system of 1.2 kW and a solar thermal panel for the production of sanitary water. The main focus of this activity is to study the integration of unpredictable sources and FC for a possible intake of surplus energy. The project aims at evaluating the energy savings possible by testing and analysing different configurations and/or different combinations of the energy sources. A domotics system is implemented both to manage energy consumption and to increase the comfort and safety of the house. Two separated electric circuits are designed: Energy-Side-Management (ESM), including the energy sources, and Demand-Side-Management (DSM) including the load. The domotics system is the interface between ESM and DSM. Different scenarios can be simulated using several switches, allowing to disconnect a portion of the plant when is not required to study it.
Approach to Developing a Multi-Disciplinary University Fuel Cell Program
Authors: Gervasio Dominic F.
Published: May 2009

University members are working to meet challenges for making practical fuel-cell power-sources. The word, fuel-cell, implies a collection of many things: catalytic electrodes, a polymer electrolyte membrane, fuel and air (oxidant) supplies, mass- and heat-transport controllers and power-conditioning electronics as well as housings for the fuel cell (bipolar plates), the fuel (fuel catridge) and the whole system (packaging). No one researcher can develop a complete fuel-cell power source system. At ASU, a number of research teams in a variety of departments are working on the different aspects of the fuel-cell power-source. This multidisciplinary approach involves: catalysts and electrolytes being developed in the School of Materials, Departments of Chemistry and Physics, fluidics in the Chemical and Mechanical Engineering Departments, water assaying in the Department of Civil and Environmental Engineering working with the Arizona Water Institute (AWI), controls and power conditioning in the Electrical Engineering department, and global impacts are being evaluated in the School of Design, ASU's Global Institute of Sustainability and Arizona Institute for Renewable Energy (AIRE).
The Mechanical and Electronic Properties of Carbon-related Nanoscale Materials: Ab Initio Study
Authors: Masuda-Jindo Kinichi , Menon Madhu
Published: May 2009

The mechanical and electronic properties of the nanoscale materials are studied using ab initio molecular dynamics (TBMD) method. We investigate the strength and fracture behaviors of nanoscale materials like carbon nanotubes (CNT), graphens and nanowires in comparison with those of corresponding bulk materials. The elastic properties, yield strength and fracture behaviors of carbon-related nanomaterials are studied in detail, using the constraint MD method based on the lattice Green's function method. We will show that the strength properties of the nanoscale materials are quite different from those of the corresponding bulk materials. The electronic density of states and electronic transports of the nanomaterials, with and without the atomistic defects (nano cracks), are also discussed.
Preparation and Properties of Smart Nano-Materials from Thermo-Sensitive Polymer Grafted Carbon Nanotubes
Authors: Yamauchi Takeshi , Sato Hiroaki , Ando Masato , Tsubokawa Norio
Published: May 2009

In this research work, we developed smart a nano-material which response to thermal condition and can be controlled its solubility to water solution. Thermo-sensitive polymer was synthesis from peroxyester (POE) groups onto carbon nanotube(CNT) surface by trapping of radicals. The dispersibility of polymer-grafted CNT in good solvent of grafted polymer chain was investigated. The thermal sensitive properties of composite CNT were also evaluated. Untreated CNT precipitated after 30 sec. On the contrary, polyNIPAM grafted CNT gave a stable dispersion in good solvent for 1h. Solubility of CNT was drastically improved by grafted polymer chains on the surface PolyNIPAM-grafted CNT was significantly aggregated at 35 oC as the function of thermo-sensitive polymer. It was appeared that the solubility of PolyNIPAM grafted CNT was controlled by external thermo energy.
Functional Role of P-Glycoprotein and Binding Protein Effect on the Placental Transfer of Lopinavir/Ritonavir in the Ex Vivo Human Perfusion Model
Authors: Ceccaldi Pierre-Francois , Gavard Laurent , Mandelbrot Laurent , Rey Elisabeth , Farinotti Robert , Treluyer Jean-Marc , Gil Sophie
Published: May 2009

Aims. To study the influence of P-glycoprotein (P-glycoprotein, ABCB1, MDR1) function on placental transfer of lopinavir with ritonavir at different albumin concentrations.Methods. Cotyledons were perfused with lopinavir, ritonavir, and the internal control antipyrin, at various albumin concentrations (10, 30, 40 g/L). After the control phase of each experiment, the P-glycoprotein inhibitor ciclosporin A was added at middle perfusion (45 minutes). Fetal Transfer Rate (FTR) and Clearance Index (CLI) were compared between the 2 phases.Results. In the control phase, the clearance index of lopinavir decreased from 0.401±0.058 to 0.007±0.027, as albumin concentrations increased from 10 g/L to higher concentrations (30, 40 g/L). When adding ciclosporin A at physiological albumin concentrations, the clearance index of lopinavir increased significantly 10.3 fold (95% of CI difference [−0.156,−0.002],P=.046) and became positive for ritonavir.Conclusions. Even at high albumin concentrations, inhibition of placental P-glycoprotein increased placental transfer of lopinavir, suggesting that this efflux pump actively reduces placental transfer of the drug. This mechanism may play a role in fetal exposure to maternal antiretroviral therapy.
Effect of TP53 Arg72Pro and MDM2 SNP309 Polymorphisms on the Risk of High-Grade Osteosarcoma Development and Survival
Authors: Toffoli Giuseppe , Biason Paola , Russo Antonio , De Mattia Elena , Cecchin Erika , Hattinger Claudia Maria , Pasello Michela , Alberghini Marco , Ferrari Cristina , Scotlandi Katia , Picci Piero , Serra Massimo
Published: May 2009

Purpose: The germ-line polymorphisms TP53 Arg72Pro and MDM2 SNP309 T>G are risk factors for tumor development and affect response to chemotherapy and survival in several cancers, but their prognostic and predictive value in patients with high-grade osteosarcomas is not yet defined. The purpose of this study was to investigate the effect of the TP53 Arg72Pro and the MDM2 SNP309 on the risk of osteosarcoma development and survival.

Experimental Design: The relative risk to develop osteosarcomas and the overall survival associated to TP53 Arg72Pro and MDM2 SNP309 polymorphisms were investigated in 201 patients. Correlations with event-free survival (EFS) were analyzed in a homogeneous subgroup of 130 patients with high-grade osteosarcomas of the limbs, nonmetastatic at diagnosis, which underwent neoadjuvant chemotherapy.

Results: Multivariate analysis showed that the MDM2 polymorphism T309G was associated with an increased risk of developing osteosarcomas [GG versus TT; odds ratio, 2.09; 95% confidence interval (95% CI), 1.15-3.78]. A case/control gender approach evidenced a significant increased risk only for female osteosarcoma patients (GG versus TT; odds ratio, 4.26; 95% CI, 1.61-11.25). Subjects carrying the TP53 Arg72Pro polymorphism were found to have a significantly increased death risk (Pro/Pro versus Arg/Arg; hazard ratio, 2.90; 95% CI, 1.28-6.66). In the subgroup of 130 high-grade osteosarcomas, the TP53 Arg72Pro was an independent marker of EFS (Pro/Pro versus Arg/Arg; hazard ratio, 2.67; 95% CI, 1.17-6.11).

Conclusion: The study provides evidence supporting the association of MDM2 SNP309 with high-grade osteosarcoma risk in females and shows that TP53 Arg72Pro has a prognostic value for overall survival and EFS in osteosarcoma patients.
Telomeric associations correlate with telomere length reduction and clonal chromosome aberrations in giant cell tumor of bone
Authors: Gebre-Medhin S. , Broberg K. , Jonson T. , Gorunova L. , Vult von Steyern F. , Brosjö O. , Jin Y. , Gisselsson D. , Panagopoulos I. , Mandahl N. , Mertens F.
Published: May 2009

Giant cell tumor of bone (GCTB) is characterized cytogenetically by frequent telomeric associations (tas). To explore the mechanisms behind the formation of tas in GCTB and to investigate their karyotypic consequences, the frequencies of tas and clonal aberrations other than tas in 20 GCTBs were compared to telomere length and status, as assessed by quantitative PCR, fluorescence in situ hybridization (FISH), and expression levels of four genes involved in telomere maintenance. Based on the G-banding results, the tumors were divided into two groups, one with a high frequency of tas and one with a low frequency. Clonal aberrations were found to be restricted to the group with a high level of tas, and the same group showed a significantly larger reduction in telomere length in tumor cells compared to peripheral blood cells. Furthermore, 65 out of 66 tas analyzed by FISH were negative for telomeric sequences. The expression levels of TERT, TERF1, TERF2, and POT1 did not correlate with telomere length or the frequency of tas. Thus, the present findings provide strong support for the notion that decreased telomere length is a prerequisite for tas in GCTBs and that the clonal changes occurring in GCTBs are derived from tas.
Cytological studies of recombination in rhesus males
Authors: Hassold T. , Hansen T. , Hunt P. , VandeVoort C.
Published: May 2009

An immunofluorescence approach was used to directly examine meiotic recombination events in 483 pachytene spermatocytes from 11 male rhesus monkeys. Specifically, we examined the nuclear localization patterns of the DNA mismatch repair protein MLH1, known from analyses of other mammalian species to be a useful marker of meiotic cross-overs. Our results indicated that rhesus pachytene spermatocytes contain approximately 40 cross-overs per cell, corresponding to about one cross-over per chromosome. The chromosomal distribution of these exchanges was consistent with data from human and mouse males but, surprisingly, the overall number of foci was lower, and the number of ‘exchangeless’ bivalents higher, than reported for either humans or mice.
Conservation of a chromosome arm in two distantly related marsupial species
Authors: Mohammadi A. , Delbridge M.L. , Waters P.D. , Marshall Graves J.A.
Published: May 2009

Marsupials, which diverged from eutherian mammals 150 million years ago (MYA), occupy a phylogenetic position that is very valuable in genome comparisons of mammal and other vertebrate species. Within the marsupials, the Australian and American clades (represented by the tammar wallaby Macropus eugenii, and the opossum Monodelphis domestica) diverged about 70 MYA. G-banding and chromosome painting suggest that tammar wallaby chromosome 6q has homology to opossum chromosome 7q. We tested this conservation by physically mapping the tammar wallaby orthologs of opossum chromosome 7q genes. We isolated 28 tammar wallaby BAC clones that contained orthologs of 16 opossum chromosome 7q genes. We used fluorescence in situ hybridization (FISH) to show that they all mapped specifically to the tammar wallaby chromosome 6q in nearly the same order as their orthologs on opossum chromosome 7q. Thus this chromosome arm is genetically, as well as cytologically, conserved over the 55–80 million years that separate kangaroos and the opossum.
Chromosome pairing of individual genomes in tall fescue (Festuca arundinacea Schreb.), its progenitors, and hybrids with Italian ryegrass (Lolium multiflorum Lam.)
Authors: Kopecký D. , Bartoš J. , Zwierzykowski Z. , Doležel J.
Published: May 2009

A diploid-like pairing system prevents meiotic irregularities and improves the efficiency of gamete production in allopolyploid species. While the nature of the system is known in some polyploid crops including wheat, little is known about the control of chromosome pairing in polyploid fescues (Festuca spp.). In this work we studied chromosome pairing in allohexaploid F. arundinacea, its progenitors F. pratensis and F. glaucescens, and two intergeneric hybrids Lolium multiflorum (2x) ×F. arundinacea (6x) and L. multiflorum (4x) ×F. glaucescens(4x). The use of genomic in situ hybridization (GISH) permitted the analysis of homoeologous chromosome pairing and recombination of different genomes involved. We detected a diploid-like pairing system in polyploid fescues F. arundinacea and F. glaucescens, the latter being one of the progenitors of F. arundinacea. The pairing control system was absent in the second progenitor F. pratensis. Detailed analysis of intergeneric hybrids confirmed the presumed haploinsufficiency of the fescue system, which resulted in homoeologous pairing between all component genomes. This indicates that introgression of any specific chromosome segment from one genome to another is possible in all genome combinations. Our results not only contribute to the quest to discover the nature of the system controlling chromosome pairing in polyploid fescues, but may also have serious implications for design of hybrid breeding schemes in forage grasses.
Body Mass Index and Prevalence of Skin Diseases in Adults with Untreated Coeliac Disease
Authors: Zingone F. , Bucci C. , Tortora R. , Santonicola A. , Cappello C. , Franzese M.D. , Passananti V. , Ciacci C.
Published: May 2009

Objective: Coeliac disease (CD) is associated with immune-mediated skin diseases such as dermatitis herpetiformis and others. The objective of the study was to investigate the relation of body mass index (BMI), as an index of absorptive status, with the prevalence of skin diseases in adults with untreated CD. Methods: Anthropometry, gastro-intestinal symptoms, nutritional indices and immune-mediated skin diseases (dermatitis herpetiformis, psoriasis, aphthosis and alopecia) at diagnosis were analysed. Results: 223 men and 924 women with untreated CD (aged 20–60 years) were included, the commonest skin disease was dermatitis herpetiformis (18.4 and 6.9%, respectively), the rarest one was alopecia (1.8 and 2.1%). The BMI was positively associated with male gender, age at diagnosis and nutritional indices, negatively with diarrhoea and dyspepsia (p < 0.001). A BMI difference of 3.5 (1 standard deviation) was related to an excess prevalence of dermatitis herpetiformis (odds ratio, OR = 1.46, 95% confidence interval, CI = 1.23–1.72) and of psoriasis (OR = 1.40, 95% CI = 1.10–1.79) but not of other immunological disorders. Findings were similar in analyses by gender or age group and controlled for gender and age. The relation of BMI to dermatitis herpetiformis was linear over the whole BMI range, also excluding overweight patients. The relation of BMI to psoriasis was flat for low-to-normal BMI and explained only by overweight patients. Conclusion: In CD at diagnosis, the BMI is positively related to the prevalence of dermatitis herpetiformis and psoriasis, not to that of other immune-mediated skin diseases.
Gender Differences in Management and Outcome of Acute Myocardial Infarctions Treated in 2006–2007
Authors: Halvorsen Sigrun , Eritsland Jan , Abdelnoor Michael , Holst Hansen Charlotte , Risøe Cecilie , Midtbø Kjell , Bjørnerheim Reidar , Mangschau Arild
Published: May 2009

Objectives: Women with acute myocardial infarction (AMI) previously received less invasive evaluation and experienced higher mortality than men. After improvements in AMI care it is unclear whether gender differences still exist in management and outcome of AMI. Methods: All patients admitted to Ullevål University Hospital for AMI during 2006 and 2007 were included in this cohort study. Predefined data were recorded during the hospital stay, and the survival status of the patients was ascertained on June 30, 2008. Results: A total of 931 women and 2,174 men were included. No gender differences were observed in treatment delay or age-adjusted odds ratio (OR) of invasive evaluation in ST-elevation myocardial infarction (STEMI). In non-ST-elevation myocardial infarction (NSTEMI), women were less likely than men to undergo coronary angiography (adjusted OR 0.72, 95% CI 0.53–0.99, p = 0.044) and percutaneous coronary intervention (adjusted OR 0.60, 95% CI 0.47–0.76, p = 0.0001). Age-adjusted in-hospital mortality and long-term survival were similar between men and women. Conclusions: Women with STEMI experienced similar treatment delays and odds of invasive evaluation as men. However, gender differences in invasive evaluation were still observed in NSTEMI patients. No sex differences were observed in age-adjusted early and long-term mortality.
Visuospatial Ability and Memory Are Associated with Falls Risk in Older People
Authors: Martin K. , Thomson R. , Blizzard L. , Wood A. , Garry M. , Srikanth V.
Published: May 2009

Background/Aims: Our purpose was to examine whether falls risk is associated with cognitive functions beyond executive function/attention and processing speed. Methods: Cognitive function was measured in a population-based sample (n = 300) of people aged 60–86 years. The physiological profile assessment was used to estimate the falls risk. Results: After adjusting for confounders, visual construction (p < 0.01), executive function/attention and memory (both p < 0.05) were independently associated with falls risk. The associations for visual construction (p < 0.01) and memory (p < 0.01) remained after adjusting for executive function/ attention. Conclusions: The neural basis underlying the associations of visuospatial function and memory with falls risk require further study.
Comparison of the Potency of Lidocaine and Chloroprocaine in Sciatic Nerve Block in Sprague-Dawley Rats
Authors: Yung Elliot , Yarmush Joel M. , Weinberg Jonathan , SchianodiCola Joseph J. , Ray Sidhartha D.
Published: May 2009

Aim: This study investigates the relative potencies and ED50 of the local anesthetics lidocaine and chloroprocaine in a sciatic block in Sprague-Dawley rats. Methods: The study involved 80 rats (chloroprocaine n = 40, lidocaine n = 40). Each rat was injected close to the sciatic nerve with 0.1 ml of the concentration of local anesthetic being tested. Using the up-and-down allocation technique, the next concentration was determined by the response of the previous subject to a higher or lower concentration. A successful block was assessed by pinching the fifth metatarsal. Absent vocalization and a very weak withdrawal response were defined as the onset of block. Results: Using the up-and-down methodology, the estimates of ED50 for chloroprocaine was 0.1 ml of 1.2% (with 95% CI of 1.1–1.6), and that for lidocaine was 0.1 ml of 0.65% (with 95% CI of 0.65–0.88), giving a lidocaine/chloroprocaine potency ratio of 1.85 (with 95% CI of 1.66–2.61). Discussion: Using the results of this study, the effects of the two drugs can be compared using the commercially available concentrations of chloroprocaine and lidocaine in a peripheral nerve block.
Visual Assessment of Left Ventricular Dyssynchrony Using Tissue Synchronization Imaging
Authors: Biner Simon , Rafique Asim M. , Wolak Arik , Tolstrup Kirsten , Siegel Robert J.
Published: May 2009

Background: Tissue synchronizing imaging (TSI) allows visual detection of asynchronous myocardial contraction. Although it is a screening tool for the detection of left ventricular (LV) dyssynchrony, its use as a qualitative method to assess dyssynchrony has not been studied. We evaluated the correlation of the visual assessment of dyssynchrony using TSI with quantitative assessment, the value of visual assessment to predict reverse remodeling to cardiac resynchronization therapy (CRT). Methods: Echocardiograms from 100 consecutive patients were retrospectively evaluated. We compared visual TSI assessment with the qualitative assessment of dyssynchrony obtained by tissue Doppler imaging (TDI). The utility of visual assessment as a predictor of response to CRT was evaluated in 43 patients. Results: In 86% of the cases, visual assessment was possible, and reproducibility was unrelated to observer experience. Each grade of visual dyssynchrony corresponded to a range of values of time to peak velocity (TPV) gradient (p < 0.001). Grade ≥1 dyssynchrony by visual assessment had 90% sensitivity and 95% specificity to identify ≥65 ms TPV gradient of LV opposing walls, and 93% sensitivity and 70% specificity to predict reverse LV remodeling. Conclusion: LV dyssynchrony may be visually assessed by TSI, which can also predict reverse LV remodeling.