bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Compositional and Mechanical Stabilities of a (La,Sr)(Co,Fe)O3-δ Cathode under SOFC Operation
Authors: Kawada Tatsuya , Oh Mi Young , Watanabe Hidetaka , Kimura Yuta , Fujimaki Yoshinobu , Masumitsu Tomohisa , Watanabe Satoshi , Hashimoto Shin-ichi , Amezawa Koji
Published: April 2012

Compositional and mechanical stabilities of (La,Sr)(Co,Fe)O3 electrode are discussed in terms of possible kinetic decomposition under oxygen potential gradient in the electrode layer, The effect of the local oxygen potential change to the local stress and its effect, vise versa, on defect equilibrium will be discussed.
Nanostructured Anodes for Direct Methane Thin Film Solid Oxide Fuel Cells
Authors: Takagi Yuto , Adam Suhare , Ramanathan Shriram
Published: April 2012

This proceedings manuscript describes in brief representative results on porous Ru anodes incorporated into thin film solid oxide fuel cells (SOFCs). Thin film of 8 mol% yttria-stabilized zirconia (YSZ) was fabricated as free-standing electrolytes, with porous platinum (Pt) and porous Ru deposited as cathode and anode electrodes, respectively. μSOFCs were tested with methane as the fuel and air as the oxidant, exhibiting an open circuit voltage of 0.71 V and a peak power density of 450 mW/cm2 at 500 °C. Anode electrodes were investigated for structural change and was found that morphology evolution in anode electrodes were strongly dependent on the fuels used. Auger electron spectroscopy was carried out on Ru anodes before and after methane operation, and revealed minimal amount of carbon existing on Ru surface, possibly being reaction intermediates. On-going studies on Ru-CGO composite anodes are discussed.
Cr-Substituted La0.3Sr0.7FeO3-δ Mixed Conducting Materials as Potential Electrodes for Symmetrical SOFCs
Authors: Chen Min , Paulson Scott , Thangadurai Venkataraman , Birss Viola
Published: April 2012

The structure stability, conductivity and electrochemical properties of Cr-substituted La0.3Sr0.7FeO3-δ SOFC electrode materials were investigated in this work, primarily for application in symmetrical solid oxide fuel cells. Cr substitution, giving La0.3Sr0.7Fe1-xCrxO3-δ (LSFC, x = 0, 0.2, 0.3), remarkably improves the phase stability of La0.3Sr0.7FeO3-δ materials in reducing atmospheres and their redox tolerance in varying atmospheres. Symmetrical half-cells employing La0.3Sr0.7Fe0.8Cr0.2O3-δ on La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) electrolyte supports exhibit electrode polarization resistances (RP) of as low as 0.25 Ω•cm2 in air and 0.45 Ω•cm2 in humidified H2 at 750oC. Maximum power densities of 0.30 W/cm2 (800oC) and 0.22 W/cm2 (750oC) were obtained for a symmetrical single cell using humidified H2/air. The excellent anodic and cathodic electrochemical performance of LSFC is thought to be due to its high electrical conductivity (180 and 0.43 S•cm-1 at 700oC in air and 10%H2+N2, respectively) and good ionic conductivity.
Oxygen Nonstoichiometry and Defect Chemistry of Mixed Conductor La0.9Ca0.1FeO3- δ at Low PO2
Authors: Geary Tim C. , Adler Stuart B.
Published: April 2012

The equilibrium oxygen nonstoichiometry, δ, for the perovskite La0.9Ca0.1FeO3-δ (LCF) was determined for oxygen partial pressures, PO2, between 10-3 and 10-20 atm and temperatures of 800, 850 and 900C using a tubular, two-probe Pt|YSZ|LCF coulometric titration cell. The PO2-nonstoichiometry relationship was interpreted using a dilute point-defect model, analogous to that of La1-xSrxFeO3-δ (LSF), and the resulting equilibrium constants were reported.
Sr2Fe1+xMo1-xO6-δ as Anode Materials for Solid Oxide Fuel Cells
Authors: Xiao Guoliang , Liu Qiang , Nuansaeng Sirikanda , Chen Fanglin (Frank)
Published: April 2012

Recently Sr2Fe1+xMo1-xO6-δ (0<=x<=1) oxides have attracted considerable interest as electrodes for solid oxide fuel cells (SOFCs). In this work, two compositions, Sr2Fe1.5Mo0.5O6-δ and Sr2Fe1.33Mo0.67O6-δ, have been studied as anodes for SOFCs using La0.8Sr0.2Ga0.87Mg0.13O3-δ (LSGM) as the electrolyte and the impact of Mo-content in these materials has been evaluated. Both compositions have shown reasonable cell performance and can be regarded as promising anode materials for SOFCs.
Impact of Reduction Parameters on the Initial Performance and Stability of Ni/(Sc)YSZ Cermet Anodes for SOFCs
Authors: Ebbeho̸j Soren L. , Ramos Tânia , Mogensen Mogens
Published: April 2012

In-situ reduction of Ni cermet anodes produces the porosity and influences the microstructure, performance and stability of the anodes. The impact on initial performance, stability and microstructure of two different reduction procedures currently in use at DTU Energy Conversion with reduction temperatures of 850 °C and 1000 °C was evaluated for tape-cast, thin electrolyte, Nickel/8 mol% Yttria-Stabilized Zirconia (Ni/8YSZ) or (Ni/10Sc1YSZ) symmetric cells. High temperature activation produced the lower Ohmic and polarization resistances related to Triple Phase Boundary (TPB) charge transfer processes for Ni/10Sc1YSZ cells. The Ni/8YSZ cells behaved oppositely with respect to reduction temperature. A hypothesis is proposed relating performance to variations in Ni microstructure, Ni/ceramic contacting and extent of TPB resulting from differences in reduction parameters. Further, the performance stability under high steam conditions was evaluated, and very stable performances and microstructures of the anode layers were observed.
Performance-Microstructure Relations in Ni/CGO Infiltrated Nb-doped SrTiO3 SOFC Anodes
Authors: Ramos Tânia , Bernuy-Lopez Carlos , Sudireddy Bhaskar R. , Bentzen Janet J. , Zhang Wei , Jo̸rgensen Peter S. , Kuhn Luise T.
Published: April 2012

Nb-doped SrTiO3 anodes, infiltrated with CGO/Ni, were investigated by electrochemical impedance spectroscopy (EIS) and high resolution microscopy techniques, upon varying production and testing parameters. The electrochemical analysis involved a combination of distribution of relaxation times (DRT) and complex non-linear least squares (CNLS) fitting routine. These electrodes were studied as single-phase or as composites with 8YSZ. Sr0.94Ti0.9Nb0.1O3-δ/ 10 vol.% 8YSZ composite infiltrated electrodes were the best overall performers, with enhanced performance stability under higher steam contents. Combined DRT/CNLS showed the existence of at least three contributing processes to the total polarisation resistance (Rp) of these electrodes. Microstructural changes involving infiltrate growth and redistribution were also confirmed.
(Invited) Role of Chemical Heterogeneities on Oxygen Reduction Kinetics on the Surface of Thin Film Cathodes
Authors: Lee Wonyoung , Cai Zhuhua , Yildiz Bilge
Published: April 2012

We investigated the effects of annealing and A-site stoichiometry on the surface heterostructures at (La0.8Sr0.2)yMnO3 (LSM, y≤1) dense thin films. While annealing at high temperatures induces cation segregation on LSM, A-site deficiency is hypothesized to reduce the level of Sr enrichment on the surface by providing more space in the bulk of LSM for this relatively large cation. Localized chemical analysis by Auger electron spectroscopy revealed the strong enrichment of Sr and Zr in annealing-induced particles on LSM surfaces. By systematically varying y from 1.0 to 0.95, A-site deficiency in LSM films was shown to suppress Sr segregation and decrease the density of these secondary phases on annealed LSM surfaces, suggesting a higher chemical stability of LSM surfaces with A-site deficiency. Our results contribute to understanding the elastic energy contributions to cation segregation on perovskite cathode surfaces, and to elucidating the role of surface chemical heterogeneities to the ORR kinetics.
Evaluation of the Structure and Electrical Transport Properties of Doped CeO2
Authors: Handal Hala Talaat , Singh Kalpana , Li Qin , Thangadurai Venkataraman
Published: April 2012

In this paper, we report the structure, chemical stability and electrical conductivity of Mn, Mo and Y or Sm-codoped CeO2. Ce0.9-xY0.1MnxO2-δ (x = 5-15%) (CYMO) were prepared by solid state reactions and co-precipitation at elevated temperatures. Powder X-ray diffraction patterns showed that the samples prepared through wet chemistry route were single-phase fluorite structure over the entire concentration ranges of Mn. However, Mn3O4 was detected in solid state method synthesised CYMO. Among the CYMO investigated in the present work, Ce0.8Y0.1Mn0.1O2-δ showed the highest total electrical conductivity of 6.1 x 10-3 Scm-1 and 1.5 x 10-2 Scm-1 at 700 οC in air and H2, respectively. Mo and Y or Sm-codoped CeO2 were found to be stable in 30 ppm H2S in H2 at 600 oC for 12 h, and found to form a single-phase solid solution at elevated temperatures with Y-doped ZrO2 (YSZ) in air.
Deposition and Characterizations of Pt/YSZ Nanocomposite Thin Films for Micro-SOFCs
Authors: Huang Hong , Rottmayer Michael , Singh Raj
Published: April 2012

Microfabricated solid oxide fuel cells (micro-SOFCs) have gained much attention as a promising technology to portable power applications. Pt and perovskite materials, the two common cathodes used in micro-SOFCs, have significant technical challenges due to their microstructural instability and low bulk conductivity, respectively. Pt/YSZ nanocomposites which combine the high electronic conductivity and catalytic activity of Pt and high ionic conductivity of YSZ, is a promising electrode candidate to improve the performances of micro-SOFCs. In this approach, Pt/YSZ nanocomposite thin films are deposited via RF co-sputtering. The structural, morphological, and electrical properties of the nanocomposite thin films were systematically studied. The thin films have been verified through SEM to be dense, crack-free, and homogeneous in thickness. The film crystallinity increases with Pt content and the thermal treatment. Upon increasing Pt content, the nanocomposite thin films gradually transform from dominant ionic-conducting to a mixed ionic/electronic and eventually metallic characteristic behavior.
Current-Voltage and Temperature Characteristics of Anode Supported Solid Oxide Electrolyzer Cells (SOEC)
Authors: Klotz Dino , Njodzefon Jean-Claude , Weber André , Ivers-Tiffée Ellen
Published: April 2012

Our zero-dimensional and isothermal stationary model predicts the current-voltage (C/V) characteristics of anode supported SOFC single cells in the direct as well as in the reverse (electrolyzer) operation mode. An extended model is presented for the electrolyzer mode, taking the corrected cell temperature as additional variable into consideration. This cell temperature is derived from measurement applying single-frequency electrochemical impedance spectroscopy (SF-EIS).
Effects of Cell Distance on the Performance of GaN High-Voltage Light Emitting Diodes
Authors: Horng Ray-Hua , Shen Kun-Ching , Lin Jia-Hua , Kuo Yu-Wei , Wuu Dong-Sing
Published: April 2012

The effect of spacing among cell LEDs in high voltage (HV) LEDs performance was investigated in this study. Four kinds of HV LEDs with different spacing are presented. From the results of LEDs output power and luminance intensity distribution, the spacing certainly influences the light extraction of LEDs. The 110% enhanced output power and 10% increased Wall-plug efficiency HV LED was demonstrated with using 80 µm spacing in compared with 20 µm due to the suppression of light absorbed by neighbor cell LEDs.
Dilute Magnetic Semiconductors: ab initio Studies of V doped ZnO
Authors: Dunne Peter , Uhlemann Margitta , Gebert Annett , Schultz Ludwig
Published: April 2012

Density functional theory calculations were performed on bulk and V-doped ZnO. Electronic correlations on the O 2p band were introduced using a Hubbard Hamiltonian (DFT + Ud + Up). An excellent agreement was found between the calculated electronic and crystallographic structure and the experimental values for bulk ZnO. The band gap was found to be 3.4 eV, with a lattice parameter error of < 1%. Antiferromagnetic and ferromagnetic ground states were found to coexist in V-doped ZnO, with little site preference, explaining the conflicting reports in experiments.
Effects of Alternating Pulse Bias Stress on Amorphous InGaZnO Thin Film Transistors
Authors: Park Suehye , Cho Edward N. , Yun Ilgu
Published: April 2012

Amorphous InGaZnO (a-IGZO) TFTs attracted more demands due to the transparency and high mobility. Since TFTs are always exposed to both positive and negative gate bias, the alternating pulse bias stress tests are required to ensure stable TFT characteristics. In this paper, the effects of alternating pulse bias stress on the threshold voltage shift (ΔVth) of a-IGZO TFTs with respect to the channel length (L) and the stress time interval (Tinterval) are investigated using the concepts of the stretched-exponential function and the density of total trap states (NT).
Band Gap Modulation in ZnO Thin Films through Cd Doping by Sol-Gel Method and Its Characterizations
Authors: Singh Amanpal , Deshwal Jagbir , Kumar Dinesh , Khanna P.K. , Kumar Mukesh
Published: April 2012

Zn1-xCdxO nanocrystalline thin films with different Cd volume ratios (x = 0.00 to 0.35) were successfully deposited by sol-gel spin coating method on p-Si (100) and quartz glass substrates. Thin films were characterized using X-ray diffraction, Atomic force microscopy, UV-Vis spectroscopy and Photoluminescence spectroscopy. XRD results revealed that thin films were polycrystalline in nature and crystallinity reduced with Cd contents. Phase segregation as cubic CdO was observed for x ≥ 0.15. Stress and strain in the films were strongly influenced by Cd contents. The optical reflectance spectra indicated that the optical quality of thin films was degraded with larger cadmium content. The band gap of samples was determined through UV-Vis transmission spectra and it is found that the band gap of ZnCdO thin films decreased exponentially with amount of Cd. Photoluminescence spectra exhibited single near band edge emission in visible violet region for lower Cd contents. This emission surprisingly splits in UV and green- yellow emissions for x ≥ 0.15.
Point Defects in Chemical-Vapor Deposited Diamond, High-Purity Semi-Insulating SiC, and Epitaxial GaN
Authors: Polyakov V. I. , Rukovishnikov A.I. , Garin B.M. , Druz B.
Published: April 2012

The native and impurity induced point defects in undoped chemi-cal-vapor deposited diamond, high-purity semi-insulating SiC and grown by molecular beam epitaxy GaN were investigated by isothermal charge-based deep level transient spectroscopy (Q-DLTS). It was found that deep levels in undoped diamond have a continuous energy spectrum with two maximums at energies 0.71 and 0.54 eV. Several discrete deep levels were found in SiC. Defect level E1 is attributed to atom displacement on the carbon sublattice in SiC. Levels E2, E4 are related to (Vc - Vsi) complex and silicon vacancy Vsi, respectively. Obtained values of active-tion energy and capture cross-section allow expecting that deep level E3 associated with the carbon vacancy Vc, while acceptor level En is vanadium-induced level. Eight deep levels were observed in GaN. Levels E1, E2, E7, and E8 have been observed in low doped n-GaN are characterized for the first time in our studies.
Structural and Optoelectronic Properties of GZO/SiOx Bilayer Films by Atmosphere Pressure Plasma Jet
Authors: Chang Kow-Ming , Ho Po Ching , Wu Chi-Wei , Wu Chin-Jyi , Chang Chia-Chiang
Published: April 2012

Using simple technique to obtain high haze and high conductivity TCO films to enhance optical absorption for silicon thin film solar cell is important. The bilayer GZO film of high haze and low resistivity is achieved by atmosphere pressure plasma jet (APPJ). Thickness of bilayer GZO film was thinner than Asahi-U type FTO film and this result indicated that the APPJ deposition technique has lower material comsumption. The minimum resistivity of 6.00×10-4 was achieved at 8 at% gallium doping. X-ray diffraction spectrum showed that an increase in scanning times led to an increase in crystallinity of bilayer GZO films. The bilayer GZO film has much higher haze value in the visible and NIR regions as compared to Asahi U-type FTO film.
The Influences of Oxygen Incorporation on the Defect Trap States of a-IGZO Thin-Film Transistors
Authors: Lo Chun Chieh , Hsieh Tsung Eong
Published: April 2012

Thin-film transistors (TFTs) comprised of amorphous indiumgallium-zinc-oxide (a-IGZO) as the active channel layers were prepared by sputtering process at various Ar/O2 gas flow ratios and their electrical properties were investigated. Device characterizations indicated that the TFT sample prepared at the condition of Ar/O2 ratio = 20:0.6 exhibits the best performance with field-effect mobility (μFE) = 5.2 cm2⋅V−1⋅sec−1, threshold voltage (Vth) = 0.7 V, subthreshold gate swing (S.S.) = 0.9 V⋅decade−1 and on/off ratio = 5×106. Such a sample also exhibited the lowest interface trap density (Dit = 2.8×1010 eV−1⋅cm−2) and the highest capacitance density (334 nF⋅cm−2) as revealed by capacitance-voltage (C-V) analysis and the lowest leakage current density of 25 nA/cm2 at 10 MV/cm (in case of positive bias on top electrode) as revealed by current-voltage (I-V) measurement.
Platinum Monolayer Electrocatalysts for the Oxygen Reduction Reaction
Authors: Vukmirovic Miomir B. , Cai Yun , Bliznakov Stoyan T. , Sasaki Kotaro , Wang Jia X. , Adzic Radoslav R.
Published: April 2012

The Pt monolayer electrocatalysts for the oxygen reduction reaction is the most promising approach to reduce the content of Pt in fuel cells while meeting all the performance and durability requirements. An ample illustration of the broad possibilities of tailoring Pt monolayer properties is presented thus revealing the potential of Pt monolayer electrocatalysts for resolving problems of availability of Pt in future catalysis and electrocatalysis and removing the main obstacles to the broad scale application of fuel cell technology.
Transition Metal Oxide Based Materials for Cathode of Polymer Electrolyte Fuel Cells
Authors: Ota Ken-ichiro , Ohgi Yoshiro , Matsuzawa Koichi , Mitsushima Shigenori , Ishihara Akimitsu
Published: April 2012

Group 4 and 5 metal oxide-based compounds might be candidates for new cathode materials of polymer electrolyte fuel cells, if they have high catalytic activity for oxygen reduction. These materials are stable in acidic and oxidative atmosphere. Among these materials, partially oxidized Ta carbonitride (Ta-CNO) and Zr carbonitride (Zr-CNO) had high catalytic activity for the ORR. Their onset potentials were almost catching Pt/C. The cost of raw material for Ta oxide or Zr oxide is far below the present Pt/C cathode. A significant cost reduction of PEFCs might be possible using these materials.
Nanostructured Thin Film Electrocatalysts for PEM Fuel Cells - A Tutorial on the Fundamental Characteristics and Practical Properties of NSTF Catalysts
Authors: Debe Mark K.
Published: April 2012

This tutorial reviews the key aspects and literature to date around the nanostructured thin film (NSTF) electrocatalyst technology platform for PEM fuel cells and electrolyzers. The NSTF technology is to date the only practical example of an extended surface area catalyst shown to effectively address several of the performance, cost and durability barriers facing cathode and anode catalysts for fuel cell vehicles. The unique physical characteristics of these ultra-thin, low Pt-loaded electrodes also require alternative solutions for water management and impurity tolerance. We present an overview of the NSTF electrocatalysts' four primary differentiating features, to show how their material and basic geometric and material characteristics translate to functional performance factors. We conclude by briefly recounting the historical origins of the NSTF material with the recommendation that the field of ordered organic molecular solids represents a large opportunity for developing tailored support materials for heterogeneous catalysis.
Macroscopic Modeling of the Proton-Exchange-Membrane Fuel-Cell Catalyst Layer
Authors: Weber Adam Z.
Published: April 2012

In the catalyst layers, all of the various phases of a fuel cell exist. Thus, there is membrane, gas, liquid, and solid (mainly carbon). In addition, there are electrocatalysts where the charge-transfer reactions take place. An accurate model of a catalyst layer requires that all of these phases and their various interactions be modeled from a physical perspective. In this transaction, the macroscopic modeling approaches towards a catalyst layer will be discussed. Specifically, the modeling and multi-scaling of catalyst-layer phenomena will be introduced including accounting of Pt-oxide formation and non-unity reaction orders in a simultaneous reaction/diffusion framework. Of particular interest is the modeling and accounting of recently observed unexpected mass-transport limitations at very low Pt loadings.
Electrochemical Reduction of Oxygen on Nano-Structured M (M = Fe, Co, Ce, W)Py/C in Alkaline Electrolyte
Authors: Qiao Jinli , Ding Lei , Xu Li , Dai Xiangfeng , Liu Yuyu
Published: April 2012

This work reports the preparation and characterization of novel non-precious metal catalysts metal catalysts supported on carbon, M (M = Fe, Co, Ce, W)Py/C, using a solvent-milling method followed by a heat-treatment at elevated temperature, where pyridine is used as the N-rich ligand for precursor complex formation. The morphology and composition of the catalysts were characterized by Fourier-transform infrared (FT-IR) spectra and thermal analysis (TGA). The catalytic activity on oxygen reduction reaction (ORR) was found to depend strongly on the heat-treatment temperatures and the metal pressures for catalyst synthesis. The resulting MPy/C of 40/60 ratio heat-treated at 800oC shows the best catalytic performance in terms of ORR and follows the order: Co > Fe > Ce > W, where the catalyst composed of Co10wt% -Py30wt%/C shows the highest electroactivity for ORR in alkaline media. Using Rotating disk electrode measurements and Koutechy-Levich analysis, the overall electron transfer number in the catalyzed ORR on Co10wt% -Py30wt%/C was found to be 3.8, suggesting the catalyzed ORR is a 4-electron transfer process from O2 to H2O.
Temperature Tuned Reaction Pathways of CO Electrooxidation in Alkaline Media
Authors: Jiang Junhua , Wieckowski Andrzej
Published: April 2012

CO electrooxidation at Pt-group catalysts in alkaline media has been first studied in the intermediate temperature range of 80 to 150 oC by means of cyclic voltammetry and chronoamperometry. Accelerated CO electrooxidation reaction kinetics has been achieved in this intermediate temperature. A new pathway involving a formate intermediate formed through the reaction of CO and hydroxide has been proposed to account for the accelerated kinetics. This is quite different from the CO electrooxidation in alkaline media at low temperature which follows a Langmuir-Hinshelwood (L-H) mechanism. This accelerated CO electrooxidation reaction kinetics would provide fundamentals for the development of fuel cell and hydrogen purification technologies since CO adsorbed on the catalyst surfaces or in bulk solutions can be oxidized at very low potential in the intermediate temperature alkaline media.
Lactobacillus rhamnosus GG culture supernatant ameliorates acute alcohol-induced intestinal permeability and liver injury
Authors: Wang Yuhua , Liu Yanlong , Sidhu Anju , Ma Zhenhua , McClain Craig , Feng Wenke
Published: April 2012

Endotoxemia is a contributing cofactor to alcoholic liver disease (ALD), and alcohol-induced increased intestinal permeability is one of the mechanisms of endotoxin absorption. Probiotic bacteria have been shown to promote intestinal epithelial integrity and protect barrier function in inflammatory bowel disease (IBD) and in ALD. Although it is highly possible that some common molecules secreted by probiotics contribute to this action in IBD, the effect of probiotic culture supernatant has not yet been studied in ALD. We examined the effects of Lactobacillus rhamnosus GG culture supernatant (LGG-s) on the acute alcohol-induced intestinal integrity and liver injury in a mouse model. Mice on standard chow diet were supplemented with supernatant from LGG culture (109 colony-forming unit/mouse) for 5 days, and one dose of alcohol at 6 g/kg body wt was administered via gavage. Intestinal permeability was measured by FITC-FD-4 ex vivo. Alcohol-induced liver injury was examined by measuring the activity of alanine aminotransferase (ALT) in plasma, and liver steatosis was evaluated by triglyceride content and Oil Red O staining of the liver sections. LGG-s pretreatment restored alcohol-induced reduction in ileum mRNA levels of claudin-1, intestine trefoil factor (ITF), P-glycoprotein (P-gp), and cathelin-related antimicrobial peptide (CRAMP), which play important roles on intestinal barrier integrity. As a result, LGG-s pretreatment significantly inhibited the alcohol-induced intestinal permeability, endotoxemia and subsequently liver injury. Interestingly, LGG-s pretreatment increased ileum mRNA expression of hypoxia-inducible factor (HIF)-2α, an important transcription factor of ITF, P-gp, and CRAMP. These results suggest that LGG-s ameliorates the acute alcohol-induced liver injury by promoting HIF signaling, leading to the suppression of alcohol-induced increased intestinal permeability and endotoxemia. The use of bacteria-free LGG culture supernatant provides a novel strategy for prevention of acute alcohol-induced liver injury.
CaMKII inhibition hyperpolarizes membrane and blocks nitrergic IJP by closing a Cl−conductance in intestinal smooth muscle
Authors: He Xue-Dao , Goyal Raj K.
Published: April 2012

The ionic basis of nitrergic “slow'” inhibitory junction potential (sIJP) is not fully understood. The purpose of the present study was to determine the nature and the role of calmodulin-dependent protein kinase II (CaMKII)-dependent ion conductance in nitrergic neurotransmission at the intestinal smooth muscle neuromuscular junction. Studies were performed in guinea pig ileum. The modified Tomita bath technique was used to induce passive hyperpolarizing electrotonic potentials (ETP) and membrane potential change due to sIJP or drug treatment in the same cell. Changes in membrane potential and ETP were recorded in the same smooth muscle cell, using sharp microelectrode. Nitrergic IJP was elicited by electrical field stimulation in nonadrenergic, noncholinergic conditions and chemical block of purinergic IJP. Modification of ETP during hyperpolarization reflected active conductance change in the smooth muscle. Nitrergic IJP was associated with decreased membrane conductance. The CAMKII inhibitor KN93 but not KN92, the Cl−channel blocker niflumic acid (NFA), and the KATP-channel opener cromakalim hyperpolarized the membrane. However, KN93 and NFA were associated with decreased and cromakalim was associated with increased membrane conductance. After maximal NFA-induced hyperpolarization, hyperpolarization associated with KN93 or sIJP was not seen, suggesting a saturation block of the Cl−channel signaling. These studies suggest that inhibition of CaMKII-dependent Cl−conductance mediates nitrergic sIJP by causing maximal closure of the Cl−conductance.
Ileal smooth muscle dysfunction and remodeling in cystic fibrosis
Authors: Risse P.-A. , Kachmar L. , Matusovsky O. S. , Novali M. , Gil F. R. , Javeshghani S. , Keary R. , Haston C. K. , Michoud M.-C. , Martin J. G. , Lauzon A.-M.
Published: April 2012

Patients with cystic fibrosis (CF) often suffer from gastrointestinal cramps and intestinal obstruction. The CF transmembrane conductance regulator (CFTR) channel has been shown to be expressed in vascular and airway smooth muscle (SM). We hypothesized that the absence of CFTR expression alters the gastrointestinal SM function and that these alterations may show strain-related differences in the mouse. The aim of this study was to measure the contractile properties of the ileal SM in two CF mouse models. CFTR−/−and CFTR+/+mice were studied on BALB/cJ and C57BL/6J backgrounds. Responsiveness of ileal strips to electrical field stimulation (EFS), methacholine (MCh), and isoproterenol was measured. The mass and the cell density of SM layers were measured morphometrically. Finally, the maximal velocity of shortening (Vmax) and the expression of the fast (+)insert myosin isoform were measured in the C57BL/6J ileum. Ileal hyperreactivity was observed in response to EFS and MCh in CFTR−/−compared with CFTR+/+mice in C57BL/6J background. This latter observation was not reproduced by acute inhibition of CFTR with CFTRinh172. BALB/cJ CFTR−/−mice exhibited a significant increase of SM mass with a lower density of cells compared with CFTR+/+, whereas no difference was observed in the C57BL/6J background. In addition, in this latter strain, ileal strips from CFTR−/−exhibited a significant increase in Vmax compared with control and expressed a greater proportion of the fast (+)insert SM myosin isoform with respect to total myosin. BALB/cJ CFTR−/−ilium had a greater relaxation to isoproterenol than the CFTR+/+mice when precontracted with EFS, but no difference was observed in response to exogeneous MCh. In vivo, the lack of CFTR expression induces a different SM ileal phenotype in different mouse strains, supporting the importance of modifier genes in determining intestinal SM properties.
Renoprotective effects of anti-TGF-β antibody and antihypertensive therapies in Dahl S rats
Authors: Murphy Sydney R. , Dahly-Vernon Annette J. , Dunn Kathryn M. J. , Chen Chun Cheng Andy , Ledbetter Steven R. , Williams Jan M. , Roman Richard J.
Published: April 2012

This study examined the effects of anti-TGF-β antibody (1D11) therapy in Dahl S (S) rats fed a 4% NaCl diet. Baseline renal expression of TGF-β1 and the degree of injury were lower in female than male S rats maintained on a 0.4% NaCl diet. 4% NaCl diet increased mean arterial pressure (MAP), proteinuria, and renal injury to the same extent in both male and female S rats. Chronic treatment with 1D11 had renoprotective effects in both sexes. The ability of 1D11 to oppose the development of proteinuria when given alone or in combination with antihypertensive agents was further studied in 6-wk-old female S rats, since baseline renal injury was less than that seen in male rats. 1D11, diltiazem, and hydrochlorothiazide (HCT) attenuated the development of hypertension, proteinuria, and glomerular injury. 1D11 had no additional effect when given in combination with these antihypertensive agents. We also explored whether 1D11 could reverse renal injury in 9-wk-old male S rats with preexisting renal injury. MAP increased to 197 ± 4 mmHg and proteinuria rose to >300 mg/day after 3 wk on a 4% NaCl diet. Proteinuria was reduced by 30–40% in rats treated with 1D11, HCT, or captopril + 1D11, but the protective effect was lost in rats fed the 4% NaCl diet for 6 wk. Nevertheless, 1D11, HCT, and captopril + 1D11 still reduced renomedullary and cardiac fibrosis. These results indicate that anti-TGF-β antibody therapy reduces renal and cardiac fibrosis and affords additional renoprotection when given in combination with various antihypertensive agents in Dahl S rats.
Cardiovascular effects of partial sleep deprivation in healthy volunteers
Authors: Dettoni Josilene L. , Consolim-Colombo Fernanda Marciano , Drager Luciano F. , Rubira Marcelo C. , Cavasin de Souza Silvia Beatriz P. , Irigoyen Maria Claudia , Mostarda Cristiano , Borile Suellen , Krieger Eduardo M. , Moreno Heitor , Lorenzi-Filho Geraldo
Published: April 2012

Sleep deprivation is common in Western societies and is associated with increased cardiovascular morbidity and mortality in epidemiological studies. However, the effects of partial sleep deprivation on the cardiovascular system are poorly understood. In the present study, we evaluated 13 healthy male volunteers (age: 31 ± 2 yr) monitoring sleep diary and wrist actigraphy during their daily routine for 12 nights. The subjects were randomized and crossover to 5 nights of control sleep (>7 h) or 5 nights of partial sleep deprivation (<5 h), interposed by 2 nights of unrestricted sleep. At the end of control and partial sleep deprivation periods, heart rate variability (HRV), blood pressure variability (BPV), serum norepinephrine, and venous endothelial function (dorsal hand vein technique) were measured at rest in a supine position. The subjects slept 8.0 ± 0.5 and 4.5 ± 0.3 h during control and partial sleep deprivation periods, respectively ( P < 0.01). Compared with control, sleep deprivation caused significant increase in sympathetic activity as evidenced by increase in percent low-frequency (50 ± 15 vs. 59 ± 8) and a decrease in percent high-frequency (50 ± 10 vs. 41 ± 8) components of HRV, increase in low-frequency band of BPV, and increase in serum norepinephrine (119 ± 46 vs. 162 ± 58 ng/ml), as well as a reduction in maximum endothelial dependent venodilatation (100 ± 22 vs. 41 ± 20%; P < 0.05 for all comparisons). In conclusion, 5 nights of partial sleep deprivation is sufficient to cause significant increase in sympathetic activity and venous endothelial dysfunction. These results may help to explain the association between short sleep and increased cardiovascular risk in epidemiological studies.
Sympathoexcitation during chemoreflex active expiration is mediated byl-glutamate in the RVLM/Bötzinger complex of rats
Authors: Moraes Davi J. A. , Zoccal Daniel B. , Machado Benedito H.
Published: April 2012

The involvement of glutamatergic neurotransmission in the rostral ventrolateral medulla/Bötzinger/pre-Bötzinger complexes (RVLM/BötC/pre-BötC) on the respiratory modulation of sympathoexcitatory response to peripheral chemoreflex activation (chemoreflex) was evaluated in the working heart-brain stem preparation of juvenile rats. We identified different types of baro- and chemosensitive presympathetic and respiratory neurons intermingled within the RVLM/BötC/pre-BötC. Bilateral microinjections of kynurenic acid (KYN) into the rostral aspect of RVLM (RVLM/BötC) produced an additional increase in frequency of the phrenic nerve (PN: 0.38 ± 0.02 vs. 1 ± 0.08 Hz; P < 0.05; n = 18) and hypoglossal (HN) inspiratory response (41 ± 2 vs. 82 ± 2%; P < 0.05; n = 8), but decreased postinspiratory (35 ± 3 vs. 12 ± 2%; P < 0.05) and late-expiratory (24 ± 4 vs. 2 ±1%; P < 0.05; n = 5) abdominal (AbN) responses to chemoreflex. Likewise, expiratory vagal (cVN; 67 ± 6 vs. 40 ± 2%; P < 0.05; n = 5) and expiratory component of sympathoexcitatory (77 ± 8 vs. 26 ± 5%; P < 0.05; n = 18) responses to chemoreflex were reduced after KYN microinjections into RVLM/BötC. KYN microinjected into the caudal aspect of the RVLM (RVLM/pre-BötC; n = 16) abolished inspiratory responses [PN ( n = 16) and HN ( n = 6)], and no changes in magnitude of sympathoexcitatory ( n = 16) and expiratory (AbN and cVN; n = 10) responses to chemoreflex, producing similar and phase-locked vagal, abdominal, and sympathetic responses. We conclude that in relation to chemoreflex activation 1) ionotropic glutamate receptors in RVLM/BötC and RVLM/pre-BötC are pivotal to expiratory and inspiratory responses, respectively; and 2) activation of ionotropic glutamate receptors in RVLM/BötC is essential to the coupling of active expiration and sympathoexcitatory response.
Analysis of functional neuronal connectivity in theDrosophilabrain
Authors: Yao Zepeng , Macara Ann Marie , Lelito Katherine R. , Minosyan Tamara Y. , Shafer Orie T.
Published: April 2012

Drosophila melanogaster is a valuable model system for the neural basis of complex behavior, but an inability to routinely interrogate physiologic connections within central neural networks of the fly brain remains a fundamental barrier to progress in the field. To address this problem, we have introduced a simple method of measuring functional connectivity based on the independent expression of the mammalian P2X2 purinoreceptor and genetically encoded Ca2+and cAMP sensors within separate genetically defined subsets of neurons in the adult brain. We show that such independent expression is capable of specifically rendering defined sets of neurons excitable by pulses of bath-applied ATP in a manner compatible with high-resolution Ca2+and cAMP imaging in putative follower neurons. Furthermore, we establish that this approach is sufficiently sensitive for the detection of excitatory and modulatory connections deep within larval and adult brains. This technically facile approach can now be used in wild-type and mutant genetic backgrounds to address functional connectivity within neuronal networks governing a wide range of complex behaviors in the fly. Furthermore, the effectiveness of this approach in the fly brain suggests that similar methods using appropriate heterologous receptors might be adopted for other widely used model systems.
Visuomotor feedback gains upregulate during the learning of novel dynamics
Authors: Franklin Sae , Wolpert Daniel M. , Franklin David W.
Published: April 2012

At an early stage of learning novel dynamics, changes in muscle activity are mainly due to corrective feedback responses. These feedback contributions to the overall motor command are gradually reduced as feedforward control is learned. The temporary increased use of feedback could arise simply from the large errors in early learning with either unaltered gains or even slightly downregulated gains, or from an upregulation of the feedback gains when feedforward prediction is insufficient. We therefore investigated whether the sensorimotor control system alters feedback gains during adaptation to a novel force field generated by a robotic manipulandum. To probe the feedback gains throughout learning, we measured the magnitude of involuntary rapid visuomotor responses to rapid shifts in the visual location of the hand during reaching movements. We found large increases in the magnitude of the rapid visuomotor response whenever the dynamics changed: both when the force field was first presented, and when it was removed. We confirmed that these changes in feedback gain are not simply a byproduct of the change in background load, by demonstrating that this rapid visuomotor response is not load sensitive. Our results suggest that when the sensorimotor control system experiences errors, it increases the gain of the visuomotor feedback pathways to deal with the unexpected disturbances until the feedforward controller learns the appropriate dynamics. We suggest that these feedback gains are upregulated with increased uncertainty in the knowledge of the dynamics to counteract any errors or disturbances and ensure accurate and skillful movements.
Incidence and Prevalence of Spinal Cord Injury in Canada: A National Perspective
Authors: Noonan Vanessa K. , Fingas Matthew , Farry Angela , Baxter David , Singh Anoushka , Fehlings Michael G. , Dvorak Marcel F.
Published: April 2012

Background: Despite decades of research, there are no national estimates of the incidence or prevalence of spinal cord injury (SCI) in Canada. Our objective was to utilize the best available data to estimate the incidence and prevalence of traumatic SCI (TSCI) and non-traumatic SCI (NTSCI) in Canada for 2010. Methods: Initial incidence (number of TSCIs at injury scene) and discharge incidence (number discharged into the community) were calculated using published TSCI rates from Alberta and NTSCI rates from Australia. Prevalence was estimated by applying TSCI and NTSCI discharge incidence rates to historical Canadian population demographics using a cohort survival model and age-specific mortality rates for tetraplegia and paraplegia. Results: The estimated 2010 initial incidence of TSCI is 1,785 cases per year, and the discharge incidence is 1,389 (41 per million). The estimated discharge incidence for NTSCI is 2,286 cases (68 per million). The prevalence of SCI in Canada is estimated to be 85,556 persons (51% TSCI and 49% NTSCI). Conclusions: This study provides the first estimates of the incidence and prevalence of SCI in Canada. More population-based studies are needed, particularly for NTSCI, as an increasing number of Canadians are expected to be affected by SCI.
Guillain-Barré Syndrome after H1N1 Vaccination in the United States: A Report Using the CDC/FDA Vaccine Adverse Event Reporting System (2009)
Authors: Souayah Nizar , Yacoub Hussam A. , Khan Hafiz M.R. , Michas-Martin P.A. , Menkes Daniel L. , Maybodi Leila , Qureshi Adnan I.
Published: April 2012

Background: Although the Guillain-Barré syndrome (GBS) can be associated with the seasonal influenza vaccine, there is no definite evidence that GBS is associated with H1N1 influenza vaccination. The objective of this report is to study the occurrence and characteristics of GBS after H1N1 vaccine administration in the United States in 2009. Methods: Data were acquired from the Vaccine Adverse Event Reporting System and supplemented by additional information obtained from the Center for Biologics Evaluation and Research, under the Federal Freedom of Information Act. Results: A total of 62 individuals (mean age 46.51 ± 22.41 years), 33 of whom were men, developed GBS associated with the H1N1 influenza vaccination in 2009. Sixty GBS cases were reported within 6 weeks after vaccination, with 31 cases (50.0%) reported in the first 2 weeks. The estimated rate of occurrence of GBS was 6.2 cases per 10 million vaccinations, which is comparable to the rate of GBS in the general population. Conclusion: The higher rate of GBS reports in the first 6 weeks after H1N1 vaccination suggests that some GBS cases may be triggered by H1N1 vaccination. This warrants early recognition, treatment, and active surveillance in the postvaccination setting.
Macrophage Differentiation and Function in Atherosclerosis: Opportunities for Therapeutic Intervention?
Authors: Williams Howell J. , Fisher Edward A. , Greaves David R.
Published: April 2012

The macrophage is exquisitely sensitive to its microenvironment, as demonstrated primarily through in vitro study. Changes in macrophage phenotype and function within the atherosclerotic plaque have profound consequences for plaque biology, including rupture and arterial thrombosis leading to clinical events such as myocardial infarction. We review the evidence for dynamic changes in macrophage numbers and macrophage differentiation within the atherosclerotic plaque microenvironment and discuss potential approaches to target macrophage differentiation for therapeutic benefit in cardiovascular disease.
Non-Calcium-Containing Phosphate Binders: Comparing Efficacy, Safety, and Other Clinical Effects
Authors: Frazão João M. , Adragão Teresa
Published: April 2012

Phosphate-binder therapy for hyperphosphataemia is key to the treatment of patients with chronic kidney disease (CKD)-mineral and bone disorder (MBD). Calcium-free phosphate binders are increasingly favoured since calcium-based agents potentially cause harmful calcium overload and vascular calcification that confound the benefits of reducing serum phosphorus. Several calcium-free phosphate binders are available, including the non-absorbed agent sevelamer and the absorbed agents, e.g. lanthanum and magnesium salts. Randomised controlled studies consistently show that sevelamer and lanthanum carbonate offer equivalent lowering of serum phosphorus and often effectively achieve phosphorus targets versus calcium salts, with sevelamer having a positive effect on bone disease, vascular calcification, and patient-level outcomes in dialysis patients in several trials. There is also evidence that lanthanum carbonate can improve bone health, but data are limited to its effects to vascular calcification or patient-level outcomes. Magnesium salts have also been shown to reduce serum phosphorus levels, but clear evidence is lacking on bone, vascular, or clinical outcomes. It also remains to be established whether long-term systemic accumulation of lanthanum and magnesium, in tissues including bone, has clinically relevant toxic effects. This review summarises the evidence of efficacy and safety for newer calcium-free phosphate binders in CKD-MBD management.
Tempol Reduces Podocyte Apoptosis via PARP Signaling Pathway in Experimental Diabetes Mellitus
Authors: Peixoto Elisa B.M.I. , Papadimitriou Alexandros , Lopes de Faria Jacqueline M. , Lopes de Faria Jose B.
Published: April 2012

Background/Aims: In diabetic hypertensive rats, tempol reduces albuminuria by restoring the redox imbalance. Increased formation of reactive oxygen species leading to activation of poly(ADP-ribose) polymerase (PARP)-1 and podocyte loss by apoptosis contribute to albuminuria in diabetes mellitus (DM). In the present study, we investigated the hypothesis that in DM tempol reduces albuminuria by inhibition of PARP-induced podocyte apoptosis. Methods: DM was induced in 4-week-old spontaneously hypertensive rats by streptozotocin. Mouse and human podocyte cell lines were cultured in normal or high-glucose conditions, with or without tempol and/or a PARP-1 inhibitor, PJ34. Results: In diabetic rats, tempol treatment did not affect plasma glucose levels or systolic blood pressure. Albuminuria was higher in diabetic rats, and it was reduced by tempol. DM leads to an elevation of glomerular apoptotic cells and to podocyte loss; both were prevented by tempol treatment. DM increases the expression of poly(ADP-ribose)-modified proteins in isolated glomeruli, and it was reduced by tempol. In vitro, high glucose increased caspase-3 activity and led to a higher number of apoptotic cells that were prevented by tempol and the PARP-1 inhibitor. Conclusion: In DM, tempol reduces albuminuria associated with reduction of podocyte apoptosis and decreasing oxidative stress via PARP signaling.
A Single-Centre Study of Acute Cardiorenal Syndrome: Incidence, Risk Factors and Consequences
Authors: Eren Zehra , Ozveren Olcay , Buvukoner Elif , Kaspar Elif , Degertekin Muzaffer , Kantarci Gulcin
Published: April 2012

Objective: Cardiac and kidney diseases are common, and the impact of acute kidney injury (AKI) on patient outcome is well known. We aimed to investigate the incidence of acute cardiorenal syndrome (CRS) and the risk factors and outcomes associated with the disease. Methods: We conducted a retrospective cohort study comprising 289 patients with acute coronary syndrome (ACS) and acute decompensated heart failure (ADHF), examining the incidence of AKI defined according to the Acute Kidney Injury Network (AKIN) classification, the factors contributing to AKI, and the impact of AKI on in-hospital mortality and hospital re-admission. Results: Of 71 patients with AKI, 36 (50.7%) had ACS and 35 (49%) had ADHF. Overall in-hospital mortality was 5.5% (n = 16). Multivariate logistic regression identified the following independent predictors of AKI in male patients with ACS: previous myocardial infarction at age >65 years (OR 5.967, 95% CI 1.16–30.47, p = 0.03), chronic kidney disease (OR 3.72, 95% CI 1.31–16.61, p = 0.01), and decreased hemoglobin levels (OR 0.684, 95% CI 0.53–0.88, p = 0.03). No variable was identified as an independent risk factor in ADHF patients. Kaplan-Meier survival curves indicated that patients with ACS plus AKI had significantly higher in-hospital mortality (log rank = 0.007). Conclusion: Acute CRS (type 1 CRS) is more frequent in patients with ADHF and can be considered multifactorial. Although CRS is less frequent in ACS patients, it is associated with longer hospital stay and with higher in-hospital mortality. The heart-kidney interaction should be managed collaboratively between cardiologists and nephrologists to increase our knowledge and enhance clinical approaches.