bluuebunny/crossref_metadata_2025 huggingface dataset:
Defect Structure of BaCo0.7Fe0.22Nb0.08O3-δ
Authors: Lee Taewon , Yoo Han-Ill
Published: October 2013

(Ba,Sr)(Co,Fe)O3-δ systems, e.g., BaCo0.7Fe0.3-xNbxO3-δ
and Ba0.5Sr0.5Co1-xFexO3-δ are the most attractive candidates for oxygen-permeation membranes and SOFC cathodes. Nevertheless, their defect structure is yet to be clarified. The ionic and electronic defects in majority have thus far been believed to be oxygen vacancies and localized holes. Holes as majority electronic carriers are acceptable on the basis of the as-measured total conductivity, that is essentially electronic, and electronic thermopower. The proposal of oxygen vacancies as majority ionic carriers lacks solid evidences. Recently, we have found the experimental evidence for oxygen interstitials being the majority ionic defects by measuring partial ionic conductivity. We hereby present the evidence.
Effect of Cation Nonstoichiometry on Surface Reactivity of LaCoO3-Based Cathode
Authors: Takeshita Ayano , Miyoshi Shogo , Yamaguchi Shu , Kudo Takao , Sato Yasushi
Published: October 2013

The effect of cation nonstoichiometry on the enhancement of surface reaction kinetics of oxide cathode has been studied with bi-layer (La,Sr)CoO3 and LaCoO3 dense thin film electrodes fabricated by an RF-sputtering method for improving the solid oxide fuel cells’ performance. The bi-layer electrodes with cation (A-site or B-site) deficiency at surface show higher surface reaction kinetics than the cation-stoichiometric electrode, which is related to the increase of oxygen vacancy induced by cation vacancy. Additionally the P
O2 dependence of the interfacial conductivity is analyzed based on a defect chemical model in consideration of “cation deficiency”, which supports the effect of cation nonstoichiometry.
Surface Chemistry and Non-Stoichiometry of Nd2NiO4+
δ Epitaxial Thin Films with Different Orientation and Strain
Authors: Tsvetkov Nikolay , Lu Qiyang , Chen Yan , Yildiz Bilge
Published: October 2013

The influence of lattice strain on non-stoichiometry and surface chemical composition was investigated for epitaxial Nd2NiO4+
ä (NNO) films during annealing in ultra high vacuum (below 10-8 mbar) and temperatures of up to 700oC. (100)- and (001)-oriented films with tensile and compressive lattice strain along c-axis were fabricated using pulsed laser deposition method. A significant decrease in the c-lattice parameter during annealing was found by x-ray diffraction (XRD) for the tensile strained films. X-ray photoelectron spectroscopy (XPS) showed that Ni reduction during annealing takes place only in compressively strained films, indicating the lower content of oxygen interstitials. A lower interstitial content in the compressively strained NNO films is consistent with the smaller c-lattice parameter measured by XRD and the easier reducibility of Ni measured by XPS. Cation segregation and morphological changes were found only for the compressively strained film surfaces. These results show that lattice strain along the c-axis is an important parameter that can alter the surface chemistry, and thus the oxygen exchange kinetics, on Nd2NiO4+
ä at elevated temperatures.
Enhancing SOFC Electrode Performance Through Surface Modification
Authors: Ding Dong , Liu Mingfei , Liu Meilin
Published: October 2013

To develop next generation solid oxide fuel cells operated at reduced temperatures with a wide variety of hydrocarbon fuels, surface modification of electrodes is an effective approach to enhancing the performance of both the state-of-the-art Ni-YSZ anode and La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) cathodes. For example,, BaO nano-islands on the surfaces of Ni grains greatly improved the coking-tolerance of Ni-YSZ anode through a water mediated carbon removal process. Similarly, an efficient catalyst layer was created in Ni-YSZ anodes when proper amount of BaCO3 was added to the NiO-YSZ anode support in the early stage of processing. For SOFC cathodes, a solution infiltration process has been used to coat various active catalysts on the surface of LSCF cathodes to enhance the catalytic activity and stability. The surface coatings include discrete particles of doped ceria and samarium doped strontium cobaltite (SSC), and dense, continuous thin films of La1-xSrxMnO3−δ (LSM), Pr0.75Sr0.2MnO3−δ (PSM), and PrSrCoMnO6-δ (PSCM).
TbxCe0.95-XGd0.05O2-δ (0.15 ≤ x ≤ 0.40) Cathode Materials Prepared through Solid State Route for Low Temperature SOFC
Authors: Chockalingam R. , Basu Suddhasatwa
Published: October 2013

Four compositions of TbxCe0.95-xGd0.05O2-δ (0.15 ≤ x ≤ 0.40) have been prepared by varying the Tb content. Phase formation, thermal expansion, ionic conductivity, electronic conductivity, ionic transference number and optical properties have been investigated. XRD results indicate that TbxCe0.95-xGd0.05O2-δ (TCGO) samples crystallize in the fluorite structure. The coefficient of thermal expansion decreases with increasing x, and at x= 0.2 shows comparable TEC value of (12.8 x 10-6 K-1) with that of Ce0.80Gd0.20O2 (GDC) electrolyte at 50-800 °C temperature range. A maximum electrical conductivity of 0.008 S cm-1 is exhibited by the composition, x = 0.40 at 550 °C. Gd3+ contributes to ionic conduction by creating oxygen vacancies and Tb4+ contributes to electronic conduction by decreasing the band gap of CeO2. UV-Visible spectroscopy results show a band gap of 3.19 eV for pure GDC and 1.85 eV for the composition Tb0.20Ce0.75Gd0.05O2-δ.
Oxygen Ion Diffusion in Dense SrZrO3 Layer on YSZ
Authors: Nishi Mina , Yokokawa Harumi , Kishimoto Haruo , Yamaji Katsuhiko , Horita Teruhisa
Published: October 2013

To investigate the oxygen ion diffusion behavior in an SOFC typically constructed of an LSCF cathode, a GDC interlayer and a YSZ electrolyte, where an SrZrO3 is unfavorably formed from the Sr component in LSCF and the Zr component in YSZ, various thickness of dense SrZrO3 layers were fabricated on the surface of YSZ pellet by applying SrCO3 paste and heat treating at three different temperatures and subsequently the oxygen isotope exchange experiments were performed for the samples. The 18O profiles and associated elemental distribution were determined across the layers by Secondary Ion Mass Spectrometry. Results have revealed that the 18O profiles are found largely deviated from those expected from the bulk diffusion in the homogenized substance particularly in the vicinity of the surface of SrZrO3 and the phase boundaries between SrZrO3 and YSZ.
Orientation Control of Layered Perovskite La2NiO4 Using Strong Magnetic Field for High Performance Cathode of SOFC
Authors: Hai Chunxi , Hashimoto Miwa , Matsunaga Chika , Uchikoshi Tetsuo , Suzuki Tohru S. , Sakka Yoshio , Matsuda Motohide
Published: October 2013

Aiming at designing a high performance cathode for solid oxide fuel cells (SOFC), orientation of the La2NiO4 (LNO) with layered structure was controlled by slip casing in a strong magnetic field. The oriented LNO compact along a,b-axes was successfully fabricated in a static magnetic field. The c-axis oriented one was managed by applying a rotating magnetic field perpendicular to the slip casting direction. Enhanced conductivities were valid along a,b-axes orientation which resulted in the accelerated mobility of conducive carriers. From those results, it is clearly expected that the orientation control of LNO brings about high performance in the cathode of SOFC.
Investigation of Redox Kinetics by Simultaneous In Situ Optical Absorption Relaxation and Electrode Impedance Measurements: Pr Doped Ceria Thin Films
Authors: Kim Jae Jin , Bishop Sean R. , Thompson Nicholas J. , Tuller Harry L.
Published: October 2013

Fast oxygen incorporation, essential for low temperature SOFCs, is enhanced in mixed ionic electronic conducting electrodes. In this study, simultaneous in situ measurement of transient optical absorption changes and electrode impedance is demonstrated as a powerful and convenient means for examining oxygen exchange kinetics in oxide thin films, utilizing Pr0.1Ce0.9O2-δ
as a model system. Absorption in the visible spectrum is tied to the fraction of Pr in its oxidized state (4+), which in turn is related to the material’s oxygen deficiency. The origin of discrepancies between kchem
derived from optical relaxation measurements and kelec
from electrochemical measurements is discussed in terms of surface contamination and the potential catalytic effect of metal contacts.
Cathodic Reaction of Perovskite Oxide Electrodes on a Proton Conducting Electrolyte
Authors: Suzuki Kota , Hashimoto Shin-ichi , Yashiro Keiji , Amezawa Koji , Kawada Tatsuya
Published: October 2013

Cathodic reaction of protonic ceramic fuel cells (PCFCs) using SrZrO3 based proton conducting electrolyte with perovskite oxide cathode is studied. A dense La0.6Sr0.4CoO3 (LSC) film is fabricated on 10mol% Y-doped SrZrO3 (SZY) electrolyte using pulsed laser deposition (PLD) method as a cathode. Cathodic performance of the dense LSC electrode is evaluated using AC impedance measurement and Secondary Ion Mass Spectroscopy (SIMS) analysis. Impedance spectra suggest that LSC dense film play a role as proton blocking electrode. SIMS analysis reveals that proton concentration in LSC dense film is higher than bulk of LSC, and there is no concentration gradient in LSC and SZY. Therefore, it is suggested that proton surface exchange rate of LSC is very low.
Electrode Properties of Bi-Sr-Fe-Based Perovskite-Type Oxides Coated with Nano-Structured PrBaCo2O5+δ
Authors: Baek Doohyun , Oikawa Itaru , Kamegawa Atsunori , Takamura Hitoshi
Published: October 2013

Nanosized PrBaCo2O5+δ (PBCO) particles were prepared by means of a bead milling and deposited on porous backbone of Bi0.5Sr0.5FeO3-δ (BSF55). PBCO was pulverized into very fine particles with crystallite size of 3.0 nm by bead milling. The electrode resistance with nano-PBCO loading decreased with increasing the loading amount of PBCO at temperatures below 550°C implying that nano-PBCO contributed to the acceleration of both electronic conduction and oxygen reduction reaction. Especially, nano-PBCO coated BSF55 with 23.3 mass% of PBCO showed 4.34 Ω•cm2 at 500°C. In addition, nano-PBCO loaded BSF55 electrodes showed the lowest electrode resistance compared to normal BSF55 cathode and composite cathode with PBCO (7:3 volume ratio) at temperatures below 600°C.
Silver-Based Current Collectors for Industrial Applications
Authors: Stoeck Andrea , Mnich Stephan , Kühn Sascha
Published: October 2013

A major issue for the use of ceramic cathodes in solid oxide fuel cells (SOFCs) is their limited conductivity and fragility. Therefore silver based current collectors were used to obtain highly conductive cathodes. Incorporation of oxide particles prevents densification and led to porous films with enhanced stability and excellent electrochemical properties.
Strontium Effect of Lanthanum Doped Ordered Perovskite Composite Cathode on Electrochemical Characteristics for IT-SOFCs
Authors: Choi Sihyuk , Park Seonhye , Shin Jeeyoung , Kim Guntae
Published: October 2013

The effects of Sr substitution for Ba on the structural properties, electrical conductivity, and electrochemical performance of a cation-ordered perovskite LaBaCo2O5+δ

(LBCO) oxide have been investigated as a cathode material for IT-SOFC applications. The electrical conductivity of LaBa0.5Sr0.5Co2O5+δ
(LBSCO) is much higher than that of Sr-free LBCO. The minimum area specific resistance value is achieved at LBSCO composite with 40 wt% Ce0.9Gd0.1O2-δ

(GDC). The best performance of LBSCO-40GDC based on a GDC electrolyte reaches 1.254 W cm-2 at 600 oC. Therefore, the ordered perovsikte structure, LBSCO-40GDC, is a potential candidate cathode material in IT-SOFC applications.
Novel Multilayered PVD-Coating in a Roll to Roll Mass Production Process
Authors: Lundberg Mats W , Berger Robert , Westlinder Jörgen , Folkeson Nicklas , Holmberg Håkan
Published: October 2013

Sandvik Materials Technology develops nanocoatings for SOFC stainless steel interconnects. A study of a novel multilayered PVD-coating for a roll to roll mass production process has been made. Cyclic oxidation for more than 7000 hours at 800°C, chromium volatilization and area specific resistance studies has been conducted on three different coatings. The study shows that each layer has its functionality. AISI441 (EN 1.4509) was coated and investigate.
Diffusion of Nickel into Ferritic Steel Interconnects of Solid Oxide Fuel/Electrolysis Stacks
Authors: Molin Sebastian , Chen Ming , Bowen Jacob Ross , Hendriksen Peter Vang
Published: October 2013

Stainless steels are used as interconnects in Solid Oxide Fuel Cell/Electrolysis stacks. Their high temperature corrosion resistance has been studied mainly to describe oxide scale formation processes. Other corrosion/degradation processes may also be of relevance to overall life time, for example diffusion of nickel from the Ni/YSZ electrode or the contact layer into the interconnect plate. Such diffusion can cause austenization of the ferritic structure and could possibly alter corrosion properties of the steel. Whereas this process has already been recognized by SOFC stack developers only a limited number of studies have been devoted to the phenomenon. Here, diffusion of Ni into ferritic Crofer 22 APU steel is studied in a wet hydrogen atmosphere after 250 hours of exposure at 800°C using Ni-plated (~ 10 micron thick coatings) sheet steel samples as a model system. Even after this relatively short time all the metallic nickel in the coating has reacted and formed solid solutions with iron and chromium. Diffusion of Ni into the steel causes formation of the austenite FCC phase. The microstructure and composition of the oxide scale formed on the sample surface after 250 hours is similar to the one observed with no Ni coating. The results show that over the time studied the overall corrosion rate of the interconnect in wet hydrogen is not affected by the Ni diffusion and formation of the austenitic phase.
Long Term Resistivity Behavior of SOFC Interconnect/Ni-Mesh/Anode Interfaces
Authors: Sarda Venkatesh , Auvinen Sonja , Shemet Vladimir , Quadakkers Willem J. , Pihlatie Mikko , Kiviaho Jari , Haart L.G.J. de
Published: October 2013

Contact resistances between Crofer 22 APU and Crofer 22 H interconnect plates, Ni mesh and Ni-8YSZ anode interfaces were measured under an anode gas atmosphere (97%H2 + 3%H2O) at 700 °C and 800 °C and current densities of 0 and 0.7 A/cm2 for durations up to 3000 hours using the 4-point DC conductivity technique. Phase transformations within the steel samples close to the interface due to inter-diffusion of elements (Ni, Fe, Mn and Cr) were observed and analyzed. These phase transformations and the formation of oxide scales on steel as well as nickel mesh surface and grain boundaries do not seem to substantially affect the measured contact resistance with time.
First-Principles Calculations of the Anodic Oxidation Reactions of Solid Oxide Fuel Cell: Oxygen Potential Effect on Nickel (111) Surface
Authors: Liu Shixue , Ishimoto Takayoshi , Kohno Haruhiko , Koyama Michihisa
Published: October 2013

The anodic reactions of solid oxide fuel cells are examined by density functional theory method under different oxygen coverage on the Ni(111) surface. The oxidation reactions H, OH and CO are calculated and the reaction barriers are affected by the oxygen potential. The concept of oxygen potential is introduced to discuss the effect of the surface chemical potential to the oxidation reactions. The results are valuable for estimating the reaction rate of anodic reactions under different oxygen potential near the anodic three phase boundary.
Theoretical Study on the Effect of Three-Dimensional Porous Structure on the Sintering of Nickel Nanoparticles in the Ni/YSZ Anode
Authors: Xu Jingxiang , Higuchi Yuji , Ozawa Nobuki , Sato Kazuhisa , Hashida Toshiyuki , Kubo Momoji
Published: October 2013

Understanding of the sintering mechanism of nickel nanoparticles in the Ni/YSZ anode is requested for long-term durability of solid oxide fuel cell. To elucidate the effects of a porous structure of the Ni/YSZ anode on the sintering, we investigated the sintering process in the Ni/YSZ anodes with different porosities by using our developed multi-nanoparticle molecular dynamics simulation method. We found that the nickel nanoparticle size significantly increased although the YSZ nanoparticles showed little change during the sintering in all the Ni/YSZ models. Since the decrease in the porosity leads to the decrease in the pore size of the YSZ framework, the sintering of the nickel nanoparticles in the Ni/YSZ model with the less porosity is more prevented by suppressing the neck growth in the small pore. On the other hand, the excessively large porosity increases the distance between the nickel nanoparticles and prevents the nickel nanoparticles from contacting.
Three-Dimensional Performance Model For Oxygen Transport Membranes
Authors: Häffelin Andreas , Niedrig Christian , Wagner Stefan , Ivers-Tiffée Ellen
Published: October 2013

A three-dimensional (3D) finite element method (FEM) model that enables the performance simulation of mixed ionic-electronic conducting (MIEC) oxygen transport membranes (OTM) has been developed. In order to evaluate the influence of a porous functional layer on the membrane performance a numerical geometry generator was implemented that allows to create arbitrary porous microstructures. The 3D OTM model includes the spatially coupled physicochemical processes i) gas diffusion in the porous functional layer, ii) oxygen exchange at the feed-side between the gas phase and the MIEC material, iii) oxygen ion diffusion across the membrane, iv) oxygen excorporation at the permeate-side. The performed simulation carried out for La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) identified a surface exchange dominated regime for membrane thicknesses below 50 µm. While the application of a porous functional layer on the feed-side could only increase the permeation flux by around 26 %, the 3D OTM model demonstrates the significant improvement that can be achieved with a functional layer on the permeate-side of the membrane.
Density Functional Theory Study on the Catalytic Properties of BaTiO3 as Solid Oxide Fuel Cell Anode
Authors: Rivera David Samuel , Ishimoto Takayoshi , Koyama Michihisa
Published: October 2013

The present paper describes our Density Functional Theory (DFT) study about the interaction of H, H2, CH4, H2S on a four layered slab BaTiO3(001) with BaO- and TiO2-terminations. We found that H adsorption is more stable on TiO2-terminated. Moreover, when two H atoms interact with the surface either BaO- or TiO2-terminated they will form H2O and an oxygen vacancy. When, H2 interacts with BaO-terminated we observed the formation of H2O and an oxygen vacancy. When H2 interacts with TiO2-terminated we observed the dissociation of the molecule to form two OH-. CH4 adsorption is more stable on TiO2-terminated, nevertheless the value is minor. When H2S interacts with both surfaces, one of the H from H2S bonds with the O from both surfaces to form OH-, for the case of TiO2-terminated, the remaining HS- will bond with the surface Ti.
Performance Characteristics of Liquid Antimony Anode Direct Carbon Fuel Cell
Authors: Wang Hongjian , Shi Yixiang , Yuan Wei , Cao Tianyu , Cai Ningsheng , Liang Xuesheng
Published: October 2013

A liquid Sb anode direct carbon fuel cell is fabricated on a smooth single crystal YSZ electrolyte (Ra=0.67nm) substrate with porous Pt cathode to reveal the intrinsic reacting kinetics of electrochemical oxidation of liquid Sb in battery mode and the reduction characteristic of Sb2O3 in carbon fuel mode using Taixi de-ash coal. And the reduction kinetics of Sb2O3 with the de-ash coal is obtain using the temperature programmed reaction testing system. The intrinsic exchange current density of the liquid Sb anode is 15A m-2. The reaction kinetics of the Sb2O3 with the de-ash coal, can be enhanced by decreasing the coal particle size. And by adding the de-ash coal into the anode chamber, the performance can be improved and keep stable. Since Sb2O3 is an oxygen ion conductor, the performance can be enhanced at the beginning. And the distribution of Sb / Sb2O3 at the anode has important effects on the liquid Sb DCFC performance.
Investigation of a Solid Oxide Fuel Cell Coupled to a Tri-reforming Process
Authors: Lo Faro Massimiliano , Vita Antonio , Pino Lidia , Aricò Antonino S.
Published: October 2013

This study deals with an investigation of the performance of a biogas-fed Solid Oxide Fuel Cell (SOFC) operating in combination with an external tri-reforming system. The tri-reforming process is carried out using a ceria supported Ni catalyst (1.75-wt% Ni/CeO2), prepared by combustion synthesis. The catalytic tests are carried out at 800°C with fixed CH4/CO2 molar ratio. Different O2/CH4 and H2O/CH4 molar ratios are investigated to evaluate the influence of different feed compositions on the performance of the integrated SOFC and tri-reforming system. The SOFC appears to tolerate different percentages of CO, CH4 and CO2 in the reformate stream without the need of steam addition. The results indicate that the process based on the combination of biogas tri-reforming and SOFC, is promising for application in small and medium sized stationary power systems.
Co-Generation of Electricity and CO from Syngas Via Proton-Conducting Solid Oxide Fuel Cells
Authors: Yan Ning , Fu Xianzhu , Luo Jingli , Chuang Karl T.
Published: October 2013

High performance anode supported proton conducting solid oxide fuel cells (SOFCs) are fabricated and tested in syngas, which enable effective utilization of H2 as fuel. The proposed co-production of concentrated CO and electricity using SOFCs is investigated. The presence of CO in the anode feed does not decrease fuel cell performance considerably and it is found that in the anode effluent, the CO is concentrated whereas H2 is selectively removed with reasonable power output.
An Application of Generalized Least Squares Method to an Analysis of Methane/Steam Reforming Process on a Ni/YSZ Catalyst
Authors: Sciazko Anna , Komatsu Yosuke , Brus Grzegorz , Kimijima Shiniji , Szmyd Janusz S.
Published: October 2013

This paper presents experimental and numerical investigations of methane/steam reforming process over a Ni/YSZ catalyst for SOFCs. Designing and optimizing an indirect internal reformer and a cell with direct reforming for an SOFC application require precise kinetic data. The generalized least squares (GLS) method was applied to evaluate the reaction rate. Mathematical modeling of the process coupled with the GLS algorithm and numerical analyses pointed out that the experimental inaccuracy could be reduced. The proposed algorithm allows for the calculation of the most probable values of kinetic parameters and uncertainties of the obtained results.
Development of Direct Internal Reforming SOFC Integrated with Paper-Structured Catalyst Fuelled by Biofuels
Authors: Shiratori Yusuke , Sakamoto Mio , Takahashi Yutaro , Wakita Yuto , Takada Masaru , Ogura Teppei , Nakajima Hironori , Sasaki Kazunari
Published: October 2013

Flexible Ni-loaded paper-structured catalysts (PSCs) were prepared by the simple paper-making process. Stable performance of DIRSOFC fuelled by simulated biogas mixture (CH4/CO2 = 1) was demonstrated by the integration of electrolyte-supported cell with PSC array which leads to uniform in-plane reaction distribution. Anode-supported cell stacked with PSC exhibited maximum power density of 820 mW cm-2 and degradation rate of 1.4 %/1000 h at 750 oC in the direct feed of biogas mixture without humidification.
An Al2O3-Doped YSZ Electrolyte-Supporting Solid Oxide Fuel Cell Fabricated by Dip-Coating and Its Direct Operation on Carbon Fuel
Authors: Xie Yongmin , Tang Yubao , Liu Jiang
Published: October 2013

Tubular YSZ and 4wt% Al2O3-doped YSZ electrolyte substrates are fabricated by dip-coating technique. Single solid oxide fuel cells (SOFCs) are prepared by applying an LSM-YSZ cathode on the outside of the electrolyte tube and an Ag-GDC anode on the inside. The cell with Al2O3-doped YSZ electrolyte shows higher performance when using moist hydrogen as fuel at 800 °C. Direct carbon fuel cell with the Al2O3-doped YSZ electrolyte gives a maximum power density of 158 mW cm-2 and an operation time of 4.3 h at a constant output of 167 mA cm-2 at 800 °C with 0.35 g 5wt% Fe-loaded activated carbon as fuel. The degradation of performance is analyzed in detail based on the electrochemical characterization and SEM-EDX measurement.
Performance Analysis of Integrated Coal Gasification Fuel Cell Combined Power Generation System
Authors: Nii Ryosuke , Komatsu Yosuke , Kimijima Shiniji
Published: October 2013

The present paper discusses the performance analysis of a combined power generation system driven with syngas from the coal gasification process. This system consists of a solid oxide fuel cell – gas turbine hybrid system and an exhaust heat power generation (EHPG) system with a steam turbine. The rankine cycle is executed in the EHPG system by using hydrocarbon fluids. The typical compositions of gases obtained from oxygen-blown and air-blown types gasification plants were adopted for fuel in the present investigation. The numerical analysis clarified the effects of the fuel composition caused by the different gasification processes on power generation performance.
In-Operando Raman Spectroscopy Study of Passivation Effects on Ni-CGO Electrodes in CO2 Electrolysis Conditions
Authors: Duboviks Vladislav , Maher Robert C. , Offer Greg , Cohen Lesley F. , Brandon Nigel P.
Published: October 2013

Ni-based solid oxide fuel/electrolysis cell electrodes are often optimized for fuel cell operation without consideration of electrolysis-specific conditions. In-situ Raman spectroscopy was employed to investigate changes that occur in the surface chemistry of such electrodes during operation in electrolysis mode. Carbon deposition on Ni-gadolinium-doped ceria electrodes after CO2 electrolysis was demonstrated. Spatially resolved Raman spectroscopy has been shown to provide valuable insight into electrode optimization. Ex-situ Raman spectroscopy is used in conjunction with high resolution microscopy in order to further characterize the changes occurring within the electrodes during operation.
Stability of Interface between YSZ Electrolyte and GDC Interlayer in Solid Oxide Electrolysis Cell
Authors: Kim Sun Jae , Choi Gyeong Man
Published: October 2013

A steam electrolysis method using Solid Oxide Electrolysis Cell (SOEC) is re-emerging as the state-of-the art technology since water molecules are easier to split into hydrogen and oxygen molecules at high temperature. However, delamination problems have been reported between GDC (Gd0.2CeO2-x) interlayer and YSZ (8mol% yttria-stabilized zirconia) electrolyte under SOEC mode. In this study, Ce0.43Zr0.43Gd0.1Y0.04O2-δ (CGZY) was chosen as a contact layer which was inserted between YSZ and GDC in order to enhance interface stability. SOEC performance was compared with and without contact layer for 100h. The CZGY contact layer significantly improved the stability of cell and the electrochemical performance.
Computational Fluid Dynamics Modeling of Solid Oxide Electrolysis Cell
Authors: Choi Hae-Won , Pharoah Jon G. , Ryland Donald , Kettner Andrew , Gnanapragasam Nirmal
Published: October 2013

Recently, the solid oxide electrolysis cell (SOEC) has gained great attention as it offers higher efficiencies compared to conventional low-temperature electrolysis. High-temperature SOEC systems takes advantage of excess steam from coal or nuclear power plants to reduce the required input energy, thus improving the overall efficiency for electrolysis. A novel three-dimensional computational fluid dynamics (CFD) model is developed to simulate the coupled physical phenomena occurring in SOECs. The computational model is based on the open-source CFD software package, OpenFOAM®. The novelty would be development and implementation of complicated thermo-electrochemical models of underlying governing equations for SOEC.
Modeling of Solid-Oxide Electrolyser Cells: From H2, CO Electrolysis to Co-Electrolysis
Authors: Menon Vikram , Janardhanan Vinod M , Deutschmann Olaf
Published: October 2013

In this analysis, we report an in-house model to describe the complex fundamental and functional interactions between various internal physico-chemical phenomena of a SOEC. Electrochemistry at the three-phase boundary is modeled using a modified Butler-Volmer approach that considers H2 and CO, individually, as electrochemically active species. Also, a multi-step elementary heterogeneous reaction mechanism for the thermo-catalytic H2/CO2 electrode chemistry, along with the dusty gas model (DGM) to account for multi-component diffusion of ideal gases through porous media, are used. The model is geometry independent. Results pertaining to detailed chemical processes within the cathode, electrochemical behavior and irreversible losses during SOEC operation are demonstrated.
Related Biological Research in the Interface between Bone Cement and Bone after Percutaneous Vertebroplasty
Authors: Hu ZhenMing , Zhao Gang , Wang LiJun , Pu Bo , Hao Jie , Lao HanChang , Zhang XiaoJun , Gan Qiang , Jiang Wei
Published: October 2013

Percutaneous vertebroplasty (PVP) is widely used in the treatment of painful osteoporotic vertebral compression fractures with the injection of PMMA cement, and the controversy for PMMA damage to the osteoporotic bone tissue and to affect the fractures repairing never stops. 72 old female rabbits, each age 3.0~3.5 y, rabbits were assigned randomly to two groups of thirty-six each; PMMA cement were injected into vertebral body in rabbits via mimic PVP, sacrificed at 1 h, 24 h, 3 d, 7 d, 4 w, and 12 w. The expression VEGF and collagen type I, the tissue response, and repair reaction in the interface between PMMA and bone tissue were observed dynamically with RT-PCR and western blot technique; the osteocalcin expression were studied by immunohistochemistry. Compared with the control group, the expression of collagen I increased at 1 hour and was higher from 24 h to 3 d. From 4 weeks to 12 weeks after injection of PMMA. The expression of VEGF decreased at 1 hour and 24 hours, significantly increased at 3 days, decreased once again at 7 days, then increased significantly at 4–12 weeks. The osteocalcin expression continued to increase during 4 to 12 week. PMMA would not cause local bone permanent necrosis, and interface injury repairing cycle could be prolonged in a vertebroplasty.
About the Nature of the Spectrum of the Periodic Problem for the Heat Equation with a Deviating Argument
Authors: Orazov I. , Shaldanbayev A. , Shomanbayeva M.
Published: October 2013

We study the nature of the spectrum of the periodic problem for the heat equation with a lower-order term and with a deviating argument. A significant influence of the lower-order term on the correct solvability of this problem is found. We obtain a criterion for the strong solvability of the above-mentioned problem.
Providers' Perceptions of Challenges in Obstetrical Care for Somali Women
Authors: Lazar Jalana N. , Johnson-Agbakwu Crista E. , Davis Olga I. , Shipp Michele P.-L.
Published: October 2013

Background. This pilot study explored health care providers’ perceptions of barriers to providing health care services to Somali refugee women. The specific aim was to obtain information about providers’ experiences, training, practices and attitudes surrounding the prenatal care, delivery, and management of women with Female Genital Cutting (FGC).Methods. Individual semi-structured interviews were conducted with 14 obstetricians/gynecologists and nurse midwives in Columbus, Ohio.Results. While providers did not perceive FGC as a significant barrier in itself, they noted considerable challenges in communicating with their Somali patients and the lack of formal training or protocols guiding the management of circumcised women. Providers expressed frustration with what they perceived as Somali patients' resistance to obstetrical interventions and disappointment with a perception of mistrust from patients and their families.Conclusion. Improving the clinical encounter for both patients and providers entails establishing effective dialogue, enhancing clinical and cultural training of providers, improving health literacy, and developing trust through community engagement.
In Vitro Antioxidant and Anticancer Activity of Flavonoid Fraction from the Aerial Parts of Cissus quadrangularis Linn. against Human Breast Carcinoma Cell Lines
Authors: Vijayalakshmi A. , Kumar P. R. , Sakthi Priyadarsini S. , Meenaxshi C.
Published: October 2013

Aim. The present study aimed to isolate flavonoid fraction from the aerial parts of Cissus quadrangularis and to evaluate its antioxidant and anticancer potential using in vitro assay system. Methods. Total phenolic and flavonoid contents were calculated for the drug. Flavonoid fraction was isolated using column chromatography and analysed using HPLC. In vitro, antioxidant activity of the ethanol extract and isolated flavonoid fraction was investigated by nitric oxide, DPPH and hydroxyl radical scavenging assays. Breast cancer (MCF 7) cell line was used as the in vitro cancer model for MTT assay. Result. The amount of total phenolic content and total flavonoid content in the ethanol extract showed 28.6 mg/g dry weight expressed as gallic acid equivalents, and 15.8 mg/g was expressed as quercetin equivalents, respectively. The tested extract showed good dose‐dependent free radical scavenging property in all the models with the IC50 values of 98 μg/mL, 125 μg/mL, and 96 μg/mL for ethanol extract and 10 μg/mL, 12 μg/mL, and 10 μg/mL for flavonoid fraction, respectively. The flavonoid fraction possess potent anticancer property against breast cancer cells (MCF7) with IC50 value of 40 μg/mL. Conclusions. It can be concluded that the aerial part of Cissus quadrangularis has potential antioxidant and anticancer activities.
Statins as Modulators of Regulatory T-Cell Biology
Authors: Forero-Peña David A. , Gutierrez Fredy R. S.
Published: October 2013

Statins are pharmacological inhibitors of the activity of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR), an enzyme responsible for the synthesis of cholesterol. Some recent experimental studies have shown that besides their effects on the primary and secondary prevention of cardiovascular diseases, statins may also have beneficial anti-inflammatory effects through diverse mechanisms. On the other hand, the induction and activity of regulatory T cells (Treg) are key processes in the prevention of pathology during chronic inflammatory and autoimmune diseases. Hence, strategies oriented towards the therapeutic expansion of Tregs are gaining special attention among biomedical researchers. The potential effects of statins on the biology of Treg are of particular importance because of their eventual application asin vivoinducers of Treg in the treatment of multiple conditions. In this paper we review the experimental evidence pointing out to a potential effect of statins on the role of regulatory T cells in different conditions and discuss its potential clinical significance.
Detection and Prevention of Selective Forwarding-Based Denial-of-Service Attacks in WSNs
Authors: Cho Youngho , Qu Gang
Published: October 2013

Designing wireless sensor networks (WSNs) that can work reliably in the presence of inside packet drop attackers is very challenging. Current trust mechanisms and avoidance approaches are promising but have their limitations. Avoidance approaches transmit multiple copies of the packets to avoid attackers and cause high overhead. In trust mechanisms, each sensor monitors it neighbors, evaluates their trustworthiness, classifies them as either trustworthy or untrustworthy, and then discards untrustworthy sensors from the network. However, malicious insiders, which are legitimate members of the network and know exactly what their monitoring nodes know, can launch attacks carefully to avoid being detected and discarded from the network. In this paper, we first show that this is possible by introducing a selective forwarding-based denial-of-service (DoS) attack. We then propose an enhanced trust mechanism to detect such attackers and identify their victims. Furthermore, we design two attacker-aware protocols to reroute victim nodes' packets by avoiding the attackers. We conduct extensive OPNET simulations to validate our claims and demonstrate the advantages of our proposed approaches. Finally, as a complementary defensive method to our detection and avoidance approaches, we introduce a prevention routing algorithm that proactively prevents the attack and provide our preliminary results to evaluate its performance.
A Comparison between Tube Surgery, ND:YAG Laser and Diode Laser Cyclophotocoagulation in the Management of Refractory Glaucoma
Authors: Bloom Philip A. , Clement Colin I. , King Anthony , Noureddin Baha , Sharma Kamal , Hitchings Roger A. , Khaw Peng T.
Published: October 2013

Purpose. To compare the results of intraocular pressure (IOP) reduction by 3 treatment modalities, (a) glaucoma tube implants, (b) noncontact YAG laser cyclophotocoagulation (cycloYAG), and (c) contact transscleral diode laser cyclophotocoagulation (cyclodiode), in cases of advanced glaucoma refractory to alternative treatments.Methods. A consecutive group of 45 eyes that received cycloYAG were matched against two control groups of patients who had received tube surgery or cyclodiode, each control group having been derived from a database of patients.Results. Mean pretreatment IOP improved from 41.3, 38.6, and 32.0 mmHg for the tube, cycloYAG, and cyclodiode groups, respectively, to 16.4, 22.1, and 19.3 mmHg, respectively. Treatment success was achieved in 78%, 69%, and 71% of the tube, cycloYAG, and cyclodiode groups, respectively. Visual acuity deteriorated 2 or more Snellen lines in 16%, 7%, and 9% of the patients in the tube, cycloYAG, and cyclodiode groups, respectively. Complications included retinal detachment, hypotony, and phthisis.Conclusions. All 3 methods provided acceptable IOP lowering in the short and medium term. Control of IOP was best in patients receiving tube surgery. Cyclodiode and cycloYAG treatments were similarly effective in lowering IOP. Tube surgery was associated with a greater incidence of sight threatening complications.
Integrated Analysis of Long Noncoding RNA and Coding RNA Expression in Esophageal Squamous Cell Carcinoma
Authors: Cao Wei , Wu Wei , Shi Fachun , Chen Xiaobing , Wu Lihua , Yang Ke , Tian Fu , Zhu Minghui , Chen Guoyong , Wang WeiWei , Biddle Fred G. , Gu Jianqin
Published: October 2013

Tumorigenesis is a complex dynamic biological process that includes multiple steps of genetic and epigenetic alterations, aberrant expression of noncoding RNA, and changes in the expression profiles of coding genes. We call the collection of those perturbations in genome space the “cancer initiatome.” Long noncoding RNAs (lncRNAs) are pervasively transcribed in the genome and they have key regulatory functions in chromatin remodeling and gene expression. Spatiotemporal variation in the expression of lncRNAs has been observed in development and disease states, including cancer. A few dysregulated lncRNAs have been studied in cancers, but the role of lncRNAs in the cancer initiatome remains largely unknown, especially in esophageal squamous cell carcinoma (ESCC). We conducted a genome-wide screen of the expression of lncRNAs and coding RNAs from ESCC and matched adjacent nonneoplastic normal tissues. We identified differentially expressed lncRNAs and coding RNAs in ESCC relative to their matched normal tissue counterparts and validated the result using polymerase chain reaction analysis. Furthermore, we identified differentially expressed lncRNAs that are co-located and co-expressed with differentially expressed coding RNAs in ESCC and the results point to a potential interaction between lncRNAs and neighboring coding genes that affect ether lipid metabolism, and the interaction may contribute to the development of ESCC. These data provide compelling evidence for a potential novel genomic biomarker of esophageal squamous cell cancer.
Primary Ovarian Large B-Cell Lymphoma
Authors: Islimye Taskın Mine , Gokgozoglu Levent , Kandemır Bedrı
Published: October 2013

The involvement of the ovary by malignant lymphoma is a well-known late manifestation of disseminated nodal disease. Primary ovarian lymphoma is rare. We herein describe a case of primary ovarian diffuse large B-cell lymphoma involving unilateral ovary in a 38-year-old woman which was detected incidentally. Preoperative ultrasonic imaging showed a 46*42 mm heterogeneous cystic mass. Laparotomy revealed that left adnexal mass and left salpingo-oophorectomy was performed. The current diagnosis was determined after immunostaining. The patient was treated with R-CHOP regimen after the operation. She remains cancer-free 24 months after chemotherapy.
Set Pair Analysis Based on Phase Space Reconstruction Model and Its Application in Forecasting Extreme Temperature
Authors: Zhang Yin , Yang Xiao-hua , Zhang Ling , Ma Wan-ying , Qiao Ling-xia
Published: October 2013

In order to improve the precision of forecasting a time series, set pair analysis based on phase space reconstruction (SPA-PSR) model is established. In the new model, by using chaos analysis, we reconstruct the phase space with delay time and embedding dimension. Based on it, we rebuilt history sets and current sets in the SPA-PSR model. Two cases of forecasting extreme temperature in Mount Wutai and Datong are taken to examine the performance of SPA-PSR model. The results indicate that the mean relative error (MRE) of SPA-PSR model has decreased by 65.97%, 59.32%, and 7.79% in the case of Mount Wutai and 29.11%, 32.82%, and 9.03% in the case of Datong, respectively, compared with autoregression (AR) model, rank set pair analysis (R-SPA) model, and Back-Propagation (BP) neural network model. It gives a theoretical support for set pair analysis and improves precision of numerical forecasting.
Using Dynamic Contrast-Enhanced Magnetic Resonance Imaging Data to Constrain a Positron Emission Tomography Kinetic Model: Theory and Simulations
Authors: Fluckiger Jacob U. , Li Xia , Whisenant Jennifer G. , Peterson Todd E. , Gore John C. , Yankeelov Thomas E.
Published: October 2013

We show how dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) data can constrain a compartmental model for analyzing dynamic positron emission tomography (PET) data. We first develop the theory that enables the use of DCE-MRI data to separate whole tissue time activity curves (TACs) available from dynamic PET data into individual TACs associated with the blood space, the extravascular-extracellular space (EES), and the extravascular-intracellular space (EIS). Then we simulate whole tissue TACs over a range of physiologically relevant kinetic parameter values and show that using appropriate DCE-MRI data can separate the PET TAC into the three components with accuracy that is noise dependent. The simulations show that accurate blood, EES, and EIS TACs can be obtained as evidenced by concordance correlation coefficients >0.9 between the true and estimated TACs. Additionally, provided that the estimated DCE-MRI parameters are within 10% of their true values, the errors in the PET kinetic parameters are within approximately 20% of their true values. The parameters returned by this approach may provide new information on the transport of a tracer in a variety of dynamic PET studies.
Design Optimization of Coronary Stent Based on Finite Element Models
Authors: Li Hongxia , Qiu Tianshuang , Zhu Bao , Wu Jinying , Wang Xicheng
Published: October 2013

This paper presents an effective optimization method using the Kriging surrogate model combing with modified rectangular grid sampling to reduce the stent dogboning effect in the expansion process. An infilling sampling criterion named expected improvement (EI) is used to balance local and global searches in the optimization iteration. Four commonly used finite element models of stent dilation were used to investigate stent dogboning rate. Thrombosis models of three typical shapes are built to test the effectiveness of optimization results. Numerical results show that two finite element models dilated by pressure applied inside the balloon are available, one of which with the artery and plaque can give an optimal stent with better expansion behavior, while the artery and plaque unincluded model is more efficient and takes a smaller amount of computation.
Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate
Authors: Qasrawi Hisham , Marie Iqbal
Published: October 2013

The effect of using recycled concrete aggregates (RCA) on the basic properties of normal concrete is studied. First, recycled aggregate properties have been determined and compared to those of normal aggregates. Except for absorption, there was not a significant difference between the two. Later, recycled aggregates were introduced in concrete mixes. In these mixes, natural coarse aggregate was partly or totally replaced by recycled aggregates. Results show that the use of recycled aggregates has an adverse effect on the workability and air content of fresh concrete. Depending on the water/cement ratio and on the percent of the normal aggregate replaced by RCA, the concrete strength is reduced by 5% to 25%, while the tensile strength is reduced by 4% to 14%. All results are compared with previous research. As new in this research, the paper introduces a simple formula for the prediction of the modulus of elasticity of RCA concrete. Furthermore, the paper shows the variation of the air content of RAC.
Safety and Effectiveness of Vibration Massage by Deep Oscillations: A Prospective Observational Study
Authors: Kraft Karin , Kanter Susanne , Janik Hubert
Published: October 2013

The objective of this study is to assess the safety of treatment with vibration massage using a deep oscillation device and the effects on symptom severity and quality of life in patients with primary fibromyalgia syndrome (FMS). Outpatients with FMS performed an observational prospective study with visits 2–4 weeks after the last treatment (control) and after further 2 months (follow-up). Patients were treated with 10 sessions of 45 min deep oscillation massage, 2/week. Primary outcome parameters were safety and tolerability (5-level Likert scale (1 = very good)) (after each treatment session and at control visit). Secondary outcome parameters were symptom severity (Fibromyalgia Impact Questionnaire (FIQ), pain) and quality of life (SF-36). Seventy patients (97.1% females) were included. At control visit, 41 patients (58.6%) reported 63 mild and short-lasting adverse events, mainly worsening of prevalent symptoms such as pain and fatigue. Tolerability was rated as 1.8 (95% confidence interval: 1.53; 2.07). Symptoms and quality of life were significantly improved at both control and follow-up visits (at leastP<0.01). In conclusion, deep oscillation massage is safe and well tolerated in patients with FMS and might improve symptoms and quality of life rather sustained.
Off-Label Use of Liraglutide in the Management of a Pediatric Patient with Type 2 Diabetes Mellitus
Authors: Micale Sara J. , Kane Michael P. , Hogan Eileen
Published: October 2013

Liraglutide is a glucagon-like peptide 1 (GLP-1) analog indicated for the treatment of type 2 diabetes mellitus as an adjunct to diet and exercise in adults. Liraglutide lowers blood glucose levels by stimulating insulin secretion and decreasing glucagon release in glucose-dependent manners, increases satiety, and delays gastric emptying. Liraglutide, unlike metformin and insulin, is not approved for use in the pediatric population. We report the successful off-label use of liraglutide in an obese, 16 year old Caucasian female with type 2 diabetes mellitus.