bluuebunny/crossref_metadata_2025 huggingface dataset:
U.S. Department of Energy Polymer Electrolyte Membrane Fuel Cell Catalyst Development Activities
Authors: Benjamin Thomas G. , Epping-Martin Kathleen , Garland Nancy L. , Ho Donna L. , Kopasz John P. , Papageorgopoulos Dimitrios C. , Podolski Walter F.
Published: March 2013

The U.S. Department of Energy's (DOE's) Fuel Cell Technologies Program supports research and development of electrocatalysts for polymer electrolyte membrane fuel cells. R&D projects address cost, durability, and performance with the goal of reducing or eliminating platinum group metals from the catalysts. The projects' strategies include: ultra-low platinum loading, platinum alloy catalysts, novel architectures, and non-PGM catalysts. The deposition of Pt monolayers on Pd nanoparticles was improved by displacement of Pd by Pt; the catalyst activity is comparable to those fabricated using Cu underpotential deposition. The specific activity of nanoparticles can be improved by ~4x using ternary alloys. Catalysts, prepared with excess non-noble elements that are removed during processing, i.e., dealloying, attain a mass activity exceeding that of commercial catalysts. Extended catalyst surfaces on nanotubes, nanowires, and metal oxides have been developed. Results from DOE's catalyst projects will be discussed in detail.
Size-Selected Platinum Clusters as Electrocatalysts for the Oxygen Reduction Reaction
Authors: Nesselberger Markus , Kunz Sebastian , Schweinberger Florian Frank , Schlögl Katrin , Mayrhofer Karl J.J. , Heiz Ueli , Arenz Matthias
Published: March 2013

In the present study size-selected platinum clusters fabricated by a laser ablation source are investigated with respect to the oxygen reduction reaction. Pt46 Clusters were deposited onto planar carbon surfaces leading to different cluster coverages between 0.018 clusters / nm² and 0.115 clusters / nm². In all cases the coverage on the glassy carbon support was low enough to avoid cluster agglomeration and hence probe the activity of isolated Pt46 clusters. The result shows that the specific ORR activity of the Pt46 clusters, i.e. the reaction rate normalized with respect to the electrochemical active surface area, depends on the cluster coverage and increases with higher coverage.
Synthesis of Platinum Catalyst Clusters and Electrochemical Investigation of Stability
Authors: Hackendorn Robert Andrew , Virkar Anil V.
Published: March 2013

In the current work, platinum catalyst nanoclusters were synthesized using two methods: (a) ascorbic acid reduction of K2PtCl4, (b) an H2PtCl6 polyol process. The processes yield clusters of platinum consisting of nanoparticles with a narrow size distribution. Experiments were conducted using platinum clusters as the working electrode and bulk platinum wire as the counter electrode, both supported on inert, electronically conducting substrates. The electrodes spaced between 1 mm and 6 mm apart, were immersed in a Pt2+/Pt4+ containing electrolyte solution and electric potential was measured across the two electrodes. Experimental data show significantly lower kinetics of particle growth for the clustered, uniformly sized particles as compared to commercially available carbon supported platinum catalysts.
Development of Alternated Catalyst Layer Structure for PEM Fuel Cells
Authors: Mei Wu , Fukazawa Taishi , Nakano Yoshihiko , Akasaka Yoshihiro , Naito Katsuyuki
Published: March 2013

A novel alternated catalyst layer structure (ACLS) has been developed for fuel cell applications. Sputtering process was applied directly on commercial gas diffusion layer (GDL) by depositing catalyst-forming material and pore-forming material alternately in a nanometer- scale and then removing the pore-forming material. The main physical features of the ACLS are (1) carbon-free and support-free (2) a large amount of void layers/pores, (3) sheet-like catalyst with extended surface and compressed lattice, and (4) a large amount of <111> crystalline planes parallel to catalyst sheet surface. Such characteristics make the ACLS a promising candidate for the PEM cathode application. In this report, some basic evaluation results of the ACLS cathode are presented. Electrochemical surface area (ECSA) evaluations showed that the typical ACLS exhibited a value of 15~30 m2/g and had a high Pt utilization efficiency. For oxygen reduction reaction activity (ORR), the measurement on 5 cm2 fuel cell membrane electrode assemblies showed that an ACLS with 5 nm-thick Pt sheets could increase mass activity 1.5 times and specific activity 3.5 times compared to the commercial Pt/C. Cathode potential at high current densities was evaluated by H2/O2 single-cell test. An ACLS with a Pt loading of 0.07 mg/cm2 demonstrated performance comparable to that of a commercial Pt/C with 0.2 mg/cm2 Pt loading. Excellent durability of the ACLS was also confirmed.
Effect of Silicotungstic Acid on Cathode Performance in Proton Exchange Membrane Fuel Cells
Authors: Baker Phillip , Kunz H. Russell , Bonville Leonard J.
Published: March 2013

Silicotungstic acid, a heteropolyacid, was added to the cathode of polymer electrolyte membrane fuel cells and evaluated for increased performance at high temperature and low relative humidity (RHs). Electrodes showed significant flaking and cracking with addition of silicotungstic acid at 15%. Adjustment of catalyst ink pH and addition of silicotungstic acid to a known ionomer morphology showed increased activity at 120{degree sign}C/35%RH by as much as 36% for cells dipped in STA compared to cells dipped in deionized water. Additionally, membrane resistance was improved by 28%. The performance impact of STA was extended out to higher current densities showing a significant improvement in cell performance.
High-Performance Pt Catalysts Supported on High-Surface-Area Graphene Composites for PEFCs
Authors: Sun Lili , Zhang Hangyu , Li Zhefei , Stanciu Lia , Ilavsky Jan , Xie Jian
Published: March 2013

Graphene sheet/nanocarbon composites (GSNC) have achieved a specific surface area as high as 1256 m2/g. In these GSNCs, the nanosized functionalized carbon black (FCB) particles attach to the surface of the graphene sheets and serve as spacers to separate and support the neighboring sheets, resulting in the high surface area. In this work, we developed Pt catalysts supported on a nanostructured GSNC. The Pt/GSNC was prepared by hydrazine reduction of exfoliated graphene oxide in the presence of different loadings of the FCBs. The catalytic performance of the different catalysts in the oxygen reduction reaction (ORR) was characterized using cyclic voltammetry (CV) and a rotating disk electrode (RDE). It was found that the Pt/GSNC catalyst prepared with 15% FCB had a higher ECASA than the others.
Rotating Disk Electrode Techniques Designed to Simulate Fuel Cell Startup/Shut-Down Transient Conditions
Authors: Stevens David A , Harlow Jessie , Sanderson Robbie J. , Watson Cody W , Crowtz Timothy J. , Dahn J. R. , Vernstrom George D. , Atanasoska Liliana L , Haugen Greg M. , Atanasoski Radoslav T.
Published: March 2013

A test protocol to measure catalyst durability and OER activity through multiple simulated fuel cell start-up shut-down pulses has been developed. Data for NSTF-coated glassy carbon disks coated with platinum and platinum with an overlayer of IrRu are presented. A small amount of catalyst with high oxygen evolution activity deposited on platinum leads to a significant reduction in the potential an electrode will see during a transient start-up or shut-down pulses.
PtCo Alloy Stability in PEMFCs under Automotive Cyclic Conditions
Authors: Chuy Carmen , Davis Mike , Guenther Matthew , Haas Herwig , Susac Darija , Talpalaru Ciprian , Zhang Hao
Published: March 2013

The present work examines the stability of a Pt-Co/C catalyst by subjecting it to voltage cycling windows and accelerated stress tests (ASTs), which represent a range of cycling profiles that a fuel cell may experience under automotive conditions. The results indicate that depending on the voltage window selected, performance degradation is accelerated or minimized due to nano-structural changes within the Pt-Co catalysts particles. A Pt skin surrounding a Pt-Co core is observed after testing, causing a significant reduction of their specific activity without significant loss in Pt or particle size growth.
Time Resolved Corrosion of Electrode Supports in PEM Fuel Cells
Authors: Fairweather Joseph D , Spernjak Dusan , Mukundan Rangachary , Ahluwalia Rajesh K. , Arisetty Srikanth , Borup Rodney L.
Published: March 2013

The potentiodynamic corrosion rates of two carbon supports are discussed. The rapid degradation of a high surface area support illustrates the effects of electrode breakup and surface oxide accumulation, and how these changes can actually accelerate further corrosion. Power law decay of corrosion rate is observed for a graphitized support during potential cycling. The initial corrosion rate is a strong function of the reducing condition applied before the start of cycling, consistent with literature postulation of a reversible passivating surface oxide.
Real-time CO2 Detection from Carbon Support Oxidation in PEM Fuel Cell Cathodes during Potential Cycling
Authors: Niangar Ellazar , Han Taehee , Dale Nilesh , Adjemian Kev
Published: March 2013

A CO2 detection system that enables in-situ and real-time monitoring of CO2 formation from carbon corrosion during start-stop potential cycling was developed. The set-up included a nondispersive infrared (NDIR) CO¬2 detector connected to the fuel cell cathode exhaust. For both Ketjen Black (KB) and Platinum/Ketjen Black (Pt/KB) (50 wt% carbon) cathodes, the amount of CO2 was found to increase with the number of potential cycles (up to 500 cycles) and the carbon loading. Pt was found to increase the initial rate (µg CO2/cycle) of CO2 formation, confirming the findings of earlier studies that Pt accelerates carbon corrosion. Preliminary calculations show that carbon loss is about 30% for both KB and Pt/KB cathodes under the potential cycling protocol used in this study. Pt only acts as a catalyst for the reaction, and it does not significantly affect the total carbon loss which is a function of the amount of corrodible carbon.
Core-Shell Fine Structure and Size-Dependent Morphology of Dealloyed Pt Bimetallic Nanoparticle Fuel Cell Electrocatalysts
Authors: Oezaslan Mehtap , Heggen Marc , Hasché Frédéric , Strasser Peter
Published: March 2013

Electrochemical dealloying is a simple facile synthetic approach to prepare advanced core-shell nanocatalysts with improved activity for the oxygen reduction reaction (ORR). The catalytically active core-shell structure forms by selective dissolution of the less noble metal from a uniform Pt-poor alloy precursor nanoparticle. However, the processes during the dealloying of nanoscale alloys are still unclear. We present a comparative structural and elemental sensitive investigation of dealloyed Pt-M (M=Ni,Cu,Co) alloy nanoparticles in their catalytically most active state. Based on the Cs-corrected high resolution scanning transmission electron microscopy (HR-STEM) results, we have uncovered a number of different dominant morphological structure types for Pt alloys as a function of their particle size. With increasing particle size the dealloyed particles show increased complex self-organized structures such as multiple cores with irregular shape and nanopores. The size-composition-structure relations link the dealloyed nanoparticles with dealloyed bulk materials to minimize the existing material gap.
The Potential of Non Carbon Based Catalysts for Automotive Fuel Cells
Authors: Suchsland Jens-Peter , Klose-Schubert Barbara , Herein Daniel , Martin Thomas , Eickes Christian , Lennartz Michael
Published: March 2013

In this paper we compare the performance and stability of state of the art carbon based catalysts with non carbon based catalyst. Technically Iridium-Oxide supported Platinum exhibits excellent stability under corrosion at 1.4V, with good transport properties and activity in a fuel cells electrode. However for commercial success there is a need for replacing Iridium. As one potential example we have prepared Antimony doped Tin-Oxide supported Platinum. This material is showing fundamentally promising properties, but instability of the dopant leads to a reduction in activity of the catalyst.
Conductive Nanostructured Materials for Supported Metal Catalysts
Authors: Sansiñena José-María , Wilson Mahlon S. , Garzón Fernando H.
Published: March 2013

New conductive nanostructured materials based on electrochemically synthesized polypyrrole (PPY) nanowires were developed for the preparation of supported metal catalysts for the oxygen reduction reaction (ORR). The new materials provided very good RRDE results as supports for low Pt load metal catalysts when compared with 46% Pt/C TKK catalyst, which was used as a reference. They demonstrated great potential to increase ORR catalytic activity by enhancing both electronic conductivity and transport properties. Ultimately, PPY-Pt nanowires based catalysts may facilitate the preparation of MEA's by incorporating them as part of a GDE when PPY is directly electrodeposited onto a GDL.
Electrochemical Stability of Topmost Surface of Pt-Enriched Ni/Pt(111) Prepared by Molecular Beam Epitaxy
Authors: Todoroki Naoto , Iijima Yuki , Takahashi Ryota , Yamada Yoshinori , Matsumoto Ken-ichi , Hayashi Takenori , Wadayama Toshimasa
Published: March 2013

Oxygen reduction reaction (ORR) activity and stability of a molecular beam epitaxially (MBE) prepared Pt-enriched Ni0.3nm/Pt(111) surface was investigated. Reflection high-energy electron diffraction (RHEED) patterns, and a scanning tunneling microscopic (STM) image indicated that the Pt-enriched surface has long-range-ordered six-fold symmetry with atomic-scale corrugations. ORR activity was estimated by kinetically-controlled current density at 0.9 V vs. a reversible hydrogen electrode, and the as-prepared Pt-enriched surface showed 8-times-higher ORR activity than clean Pt(111). The activity steeply reduced during potential cycling between 0.6 V and 1.0 V. After 1000 potential cycles, the enhancement factor was 2.5 and a cyclic voltammetry (CV) curve exhibited an increase in (EC) electron charge for the Had&des region accompanied by the emergence of a 0.13 V redox feature caused by (110) surface defects. These results suggest that the electrochemical stability of the underlying Ni atoms determines the durability of Pt-Ni alloy catalysts.
Synthesis and Electrochemical Characterization of Co, Cu, Fe, Ni and Mn-Based Catalysts for ORR in PEM Fuel Cells
Authors: Goenaga Gabriel A. , Brooksbank Jeremy , Dabke Chinmay , Belapure Ashesh , Papandrew Alex , Foister Shane , Zawodzinski Thomas A.
Published: March 2013

We have synthesized a variety of transition metal-ligand complexes supported on carbon black to be used as catalysts for PEMFC cathode electrodes. Complexes of Cu, Co, Fe, Ni and Mn with triazole ligands such as diaminotriazole (DATZ), phthalocyanine (Pc) and pyridine were either adsorbed or covalently attached via diazonium coupling to BP2000 carbon support. Electrochemical activity was investigated via rotating ring disk electrode experiments (RRDE). The as-prepared materials showed low catalytic activity towards the oxygen reduction reaction (ORR). All of our samples demonstrated improved catalytic activity after pyrolysis in an inert atmosphere at temperatures above 600 oC. In general, adsorbed complexes showed lower catalytic activity than immobilized ones. In addition, complexes using Pc ligand presented higher catalytic activity and current densities than DATZ based materials. Catalysts using Co and Cu as the metal centers showed the best onset potentials after the heat treatment.
Surface Reaction Analysis of Tantalum-Oxide Oxygen-Reduction Catalysts by Using X-ray Photoelectron Spectroscopy
Authors: Matsumoto Masashi , Miyazaki Takashi , Fujieda Shinji , Ishihara Akimitsu , Ota Ken-ichiro , Imai Hideto
Published: March 2013

Oxidation states of tantalum that is contained in oxygen-reduction-reaction (ORR) active Ta-CNO catalysts were investigated by hard x-ray photoelectron spectroscopy (HAXPES) to clarify the nature of the active sites of Ta-CNO ORR catalysts. The results of HAXPES measurements showed that both Ta 3d and Ta 4f core levels shifted to the low energy, suggesting that oxygen vacancies were introduced in surface oxide phases of ORR active Ta-CNOs. This result is consistent with previous x-ray absorption spectroscopic studies. We also developed the electrochemical (EC)-XPS and EC-HAXPES techniques to analyze the reaction mechanism of ORR on Ta-CNOs. We demonstrate that EC-XPS and EC-HAXPES are a suitable probe to observe electrochemical reactions at electrode surfaces through an example of observation of the electrochemical oxidation behaviors of Ta-CNO catalysts.
Tuning the Process Gas in a Dual Plasma Process to Enhance the Performance of Cobalt-Polypyrrole Catalyts for the Oxygen Reduction Reaction in Fuel Cells
Authors: Walter Christian , Kummer Kurt , Vyalikh Denis , Brüser Volker , Weltmann Klaus-Dieter
Published: March 2013

In this contribution, the dual plasma process to produce catalytically active cobalt-polypyrrole-compounds is enhanced. This is done by adding nitrogen, hydrogen and oxygen to argon during the plasma process. The so-obtained compounds were analysed by EDX,XRD and NEXAFS to get information on the structural composition. Furthermore, CVmeasurements were done to determine the electrochemical properties of the films. It is shown that the catalytic activity increases slightly while the stability of the films can be greatly improved.
Pt Decorated Amorphous RuIr Alloys as High Efficiency Electrocatalyst for Methanol Oxidation
Authors: Pollet Bruno G , Ma Y. J. , Wang H. , Ji S. , Wang R. F.
Published: March 2013

This study focuses primarily on improving the utilization and activity of anodic catalysts for methanol electro-oxidation. The Direct Methanol Fuel Cell (DMFC) anodic catalyst, a carbon supported Pt decorated amorphous RuIr nanoparticles catalyst (Pt@RuIr/C) was prepared by a two-step reduction method. The structure of Pt@RuIr/C nanoparticles was confirmed by Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD). The Pt@RuIr electrocatalysts exhibited good uniformity in distribution. Cyclic Voltammetry experiments showed that under the same quality of noble-metal, the Pt@RuIr/C catalyst had higher activity than the PtRuIr/C catalyst for methanol oxidation. It was also shown that the as-prepared structure of the Pt decorated amorphous RuIr alloys could obviously decrease the usage of noble-metal and enhance its catalytic activity at the same time.
O2-Enhanced Methanol Oxidation at Pt-Ru-C Ternary Sputtered Electrode
Authors: Shironita Sayoko , Ueda Masafumi , Umeda Mimoru
Published: March 2013

We have developed a novel anode catalyst for the direct methanol fuel cell (DMFC). Pt-C and Pt-Ru-C electrodes were prepared by a co-sputtering technique. These electrodes with a specific atomic ratio showed a remarkable O2-enhanced methanol oxidation performance and the reaction selectivity by O2 addition for methanol as a fuel. For practical utilization, the relationship between the O2-enhanced methanol oxidation activity and the thermal stability of the Pt-C and Pt-Ru-C sputtered electrodes were evaluated by a post annealing treatment. It is found that the O2-enhanced methanol oxidation activity of the Pt-Ru-C electrodes is retained if the annealing temperature is less than or equal to 100 C. Finally, the DMFC performance was assessed using a single DMFC cell incorporating a membrane electrode assembly with Pt-Ru-C which was hot pressed at 100 C.
Electrochemical Behavior and Morphology of Nano Catalyst for Fuel Cell: The effect of Ultrasonic and Microwave Techniques
Authors: Tran Man Van , Doan Thuy Thi , Duong Phuc Ngoc , Le My Loan Phung , Nguyen Thi Phuong Thoa
Published: March 2013

In this work, we succeed to prepare the Pt/C and PtRu/C composite electrodes by thermal, sonochemical and microwave methods. The synthesized catalysts are nano uniform particles of 1-6 nm diameters, deposited on pretreated Vulcan carbon 30-50 nm sized aggregates. The pH has important effect on reduction efficiency, the structure and particle-size distribution of synthesized catalyst. The ultrasonification gives smaller and more uniform nano particles than others. The electrochemical measurements of composite electrode in methanol showed that oxidation is irreversible and incompleted, the current density increase with pH and the ultrasonic irradiation gives the best catalytic performance.
DMFC Performance of Cross-Linked Sulfoethylcellulose/Poly(Vinyl Alcohol) Blend Electrolyte Membranes
Authors: Kasai Yutaka , Okayama Toru , Guan Guoqing , Abudula Abuliti
Published: March 2013

Membrane electrode assembly (MEA) was fabricated using cross-linked sulfoethylcellulose/poly(vinyl alcohol) blend membrane (CL-SEC/PVA), and direct methanol fuel cell (DMFC) operation tests with various concentrations of methanol fuel were intensively evaluated. CL-SEC/PVA achieves the highest power density of 23.4 mW cm-2 at 50 ºC with 1 M methanol solution. In spite of lower proton conductivity than Nafion NRE-212, the maximum power density and the open circuit voltage of CL-SEC/PVA are exceeded those of Nafion NRE-212 with higher methanol solution over 10 M because of the extremely low methanol permeability of CL-SEC/PVA. Continuous operation test at a constant current density of 80 mA cm-2 shows the reduction of DMFC performance by about 20 % after 48 h operation. As a result of FT-IR spectroscopy and IEC measurement, it is found that sulfonic groups in the membrane are eliminated during continuous operation of DMFC.
Alkaline Membrane Fuel Cell (AMFC) Materials and System Improvement - State-of-the-Art
Authors: Dekel Dario R
Published: March 2013

In the last few years, developmental work on anion conductive membranes for AMFC has significantly increased and several polymer chemistries have already been tested at very small AMFC scales. On the other hand, scarce work is being done on anion conductive ionomers, and just a very few groups are working on electrocatalysts for the electrodes of this technology. From the limited materials developed for this technology, peak power density records of almost 200mW/cm2 were already achieved. Non-published data suggests that the actual power densities that can be achieved with today's state-of-the-art anion conductive polymers are even much higher. With the latest and most advanced developed materials, AMFC stacks providing 2kW power output were already developed. During this presentation, the state of the art on AMFCs will be reviewed, and current challenges in the development of new materials will be briefly discussed.
Transport Properties of Plasma Polymerized Anion Exchange Membrane for Direct Methanol Alkaline Fuel Cells
Authors: Kurozumi Tomohiro , Okajima Yoshiki , Nagai Hidekazu , Sudoh Masao
Published: March 2013

The objective of this work is to fabricate thin anion conductive membrane, and to adopt for AFCs system. Transport properties were compared with commercial membranes (Nafion117, AHA). Hot-press treatment may affect the decrease in methanol permeability and the increase in OH- transport number.The conductivity increased with the concentration of KOH and plasma polymerized membrane with hot-press treatment had higher conductivity (39.3 mS/cm with 1 M KOH) because the membrane became thin by hot-press treatment.
Membrane Science for Liquid Organic Fuel Cells
Authors: Clark Kyle Tyler , Krishnan Lakshmi , Yeager Gary William , Kerr John
Published: March 2013

This study was aimed at understanding the interaction of liquid organic fuels with Nafion® membranes. Carbocyclic compounds, O-containing and N-containing heterocyclic compounds were investigated as fuels. We report the properties of PEMs, such as solvent uptake, proton conductivity and fuel cell performance in the presence of such liquid organic fuels.
High Temperature Electrochemical Hydrogen Pump Cell Using a PBI Membrane at High Current Densities
Authors: Petek Tyler Joseph , Wainright Jesse S. , Savinell Robert F.
Published: March 2013

The ability of an electrochemical hydrogen pump cell employing a polybenzimidazole membrane imbibed with phosphoric acid to purify hydrogen rich streams has been investigated. It has been found that pure hydrogen can be produced from diluted hydrogen and from typical reformate feeds with less than 5 kW-hrs required per kilogram of hydrogen pumped. The performance of these cells does not degrade under pure hydrogen over 24 hours for current densities up to 0.4 A/cm2. However, in less than 10 hours, the polarization effects had increased by 10% under pure hydrogen at 1.0 A/cm2 and by 50% under reformate at 0.2 A/cm2. However, the performance degradation caused by the presence of CO was observed to be reversible by switching the cell polarization and flows.
Comparing Hydrogen Oxidation and Evolution Reaction Kinetics on Polycrystalline Platinum in 0.1 M and 1 M KOH
Authors: Rheinländer Philipp , Henning Sebastian , Herranz Juan , Gasteiger Hubert A.
Published: March 2013

Alkaline membrane fuel cells (AMFCs) are attracting increasing attention owing to recent developments in anion-exchange membranes and non-noble-metal O2-reduction catalysts. Despite these promising improvements, the sluggish kinetics of the H2-oxidation reaction (HOR) on Pt imply the need for considerable amounts of this noble metal at the AMFC anode, rendering the system more expensive and ultimately hindering its commercialization. Interestingly, the majority of the works dealing with the kinetics of the HOR on Pt were performed in relatively dilute (0.1 M) alkaline electrolytes with a pH lower than that of the operative AMFC. Wondering whether this difference in OH−-concentration would have a significant effect on the HOR-kinetics, here we report our results on the HOR-activity of polycrystalline Pt in 0.1 M and 1 M KOH. These were derived from rotating disc electrode measurements performed in a temperature-controlled PTFE-cell, which allowed us to estimate reliable values for the exchange current density and activation energy in both alkaline solutions.
Rats with adenine-induced chronic renal failure develop low-renin, salt-sensitive hypertension and increased aortic stiffness
Authors: Nguy Lisa , Johansson Maria E. , Grimberg Elisabeth , Lundgren Jaana , Teerlink Tom , Carlström Mattias , Lundberg Jon O. , Nilsson Holger , Guron Gregor
Published: March 2013

Rats with adenine-induced chronic renal failure (A-CRF) develop metabolic and cardiovascular abnormalities resembling those in patients with chronic kidney disease. The aim of this study was to investigate the mechanisms of hypertension in this model and to assess aortic stiffness in vivo. Male Sprague-Dawley rats were equipped with radiotelemetry probes for arterial pressure recordings and received either chow containing adenine or normal control diet. At 7 to 11 wk after study start, blood pressure responses to high NaCl (4%) diet and different pharmacological interventions were analyzed. Aortic pulse wave velocity was measured under isoflurane anesthesia. Baseline 24-h mean arterial pressure (MAP) was 101 ± 10 and 119 ± 9 mmHg in controls and A-CRF animals, respectively ( P < 0.01). After 5 days of a high-NaCl diet, MAP had increased by 24 ± 6 mmHg in A-CRF animals vs. 2 ± 1 mmHg in controls ( P < 0.001). Candesartan (10 mg/kg by gavage) produced a more pronounced reduction of MAP in controls vs. A-CRF animals (−12 ± 3 vs. −5 ± 5 mmHg, P < 0.05). Aortic pulse wave velocity was elevated in A-CRF rats (5.10 ± 0.51 vs. 4.58 ± 0.17 m/s, P < 0.05). Plasma levels of creatinine were markedly elevated in A-CRF animals (259 ± 46 vs. 31 ± 2 μM, P < 0.001), whereas plasma renin activity was suppressed (0.6 ± 0.5 vs. 12.3 ± 7.3 μg·l−1·h−1, P < 0.001). In conclusion, hypertension in A-CRF animals is characterized by low plasma renin activity and is aggravated by high-NaCl diet, suggesting a pathogenic role for sodium retention and hypervolemia probably secondary to renal insufficiency. Additionally, aortic stiffness was elevated in A-CRF animals as indicated by increased aortic pulse wave velocity.
Wrist torque estimation during simultaneous and continuously changing movements: surface vs. untargeted intramuscular EMG
Authors: Kamavuako Ernest N. , Scheme Erik J. , Englehart Kevin B.
Published: March 2013

In this paper, the predictive capability of surface and untargeted intramuscular electromyography (EMG) was compared with respect to wrist-joint torque to quantify which type of measurement better represents joint torque during multiple degrees-of-freedom (DoF) movements for possible application in prosthetic control. Ten able-bodied subjects participated in the study. Surface and intramuscular EMG was recorded concurrently from the right forearm. The subjects were instructed to track continuous contraction profiles using single and combined DoF in two trials. The association between torque and EMG was assessed using an artificial neural network. Results showed a significant difference between the two types of EMG ( P < 0.007) for all performance metrics: coefficient of determination (R2), Pearson correlation coefficient (PCC), and root mean square error (RMSE). The performance of surface EMG (R2 = 0.93 ± 0.03; PCC = 0.98 ± 0.01; RMSE = 8.7 ± 2.1%) was found to be superior compared with intramuscular EMG (R2 = 0.80 ± 0.07; PCC = 0.93 ± 0.03; RMSE = 14.5 ± 2.9%). The higher values of PCC compared with R2 indicate that both methods are able to track the torque profile well but have some trouble (particularly intramuscular EMG) in estimating the exact amplitude. The possible cause for the difference, thus the low performance of intramuscular EMG, may be attributed to the very high selectivity of the recordings used in this study.
Functional organization of human posterior parietal cortex: grasping- and reaching-related activations relative to topographically organized cortex
Authors: Konen Christina S. , Mruczek Ryan E. B. , Montoya Jessica L. , Kastner Sabine
Published: March 2013

The act of reaching to grasp an object requires the coordination between transporting the arm and shaping the hand. Neurophysiological, neuroimaging, neuroanatomic, and neuropsychological studies in macaque monkeys and humans suggest that the neural networks underlying grasping and reaching acts are at least partially separable within the posterior parietal cortex (PPC). To better understand how these neural networks have evolved in primates, we characterized the relationship between grasping- and reaching-related responses and topographically organized areas of the human intraparietal sulcus (IPS) using functional MRI. Grasping-specific activation was localized to the left anterior IPS, partially overlapping with the most anterior topographic regions and extending into the postcentral sulcus. Reaching-specific activation was localized to the left precuneus and superior parietal lobule, partially overlapping with the medial aspects of the more posterior topographic regions. Although the majority of activity within the topographic regions of the IPS was nonspecific with respect to movement type, we found evidence for a functional gradient of specificity for reaching and grasping movements spanning posterior-medial to anterior-lateral PPC. In contrast to the macaque monkey, grasp- and reach-specific activations were largely located outside of the human IPS.
Structures and Properties of Naturally Occurring Polyether Antibiotics
Authors: Rutkowski Jacek , Brzezinski Bogumil
Published: March 2013

Polyether ionophores represent a large group of natural, biologically active substances produced byStreptomyces spp. They are lipid soluble and able to transport metal cations across cell membranes. Several of polyether ionophores are widely used as growth promoters in veterinary. Polyether antibiotics show a broad spectrum of bioactivity ranging from antibacterial, antifungal, antiparasitic, antiviral, and tumour cell cytotoxicity. Recently, it has been shown that some of these compounds are able to selectively kill cancer stem cells and multidrug-resistant cancer cells. Thus, they are recognized as new potential anticancer drugs. The biological activity of polyether ionophores is strictly connected with their molecular structure; therefore, the purpose of this paper is to present an overview of their formula, molecular structure, and properties.
Moderating Material to Compensate the Drawback of High Minor Actinide Containing Transmutation Fuel on the Feedback Effects in SFR Cores
Authors: Merk Bruno
Published: March 2013

The use of fine distributed moderating material to enhance the feedback effects and to reduce the sodium void effecting SFRs is described. The drawback on the feedback effects due to the introduction of minor actinides into SFR fuel is analyzed. The possibility of compensation of the effect of the minor actinides on the feedback effects by the use of fine distributed moderating material is demonstrated. The consequences of the introduction of fine distributed moderating material into fuel assemblies with fuel configurations foreseen for minor actinide transmutation are analyzed, and the positive effects on the transmutation efficiency are shown. Finally, the possible increase of the Americium content to improve the transmutation efficiency is discussed, the limit value of Americium is determined, and the possibilities given by an increase of the hydrogen content are analyzed.
Skin Basement Membrane: The Foundation of Epidermal Integrity—BM Functions and Diverse Roles of Bridging Molecules Nidogen and Perlecan
Authors: Breitkreutz Dirk , Koxholt Isabell , Thiemann Kathrin , Nischt Roswitha
Published: March 2013

The epidermis functions in skin as first defense line or barrier against environmental impacts, resting on extracellular matrix (ECM) of the dermis underneath. Both compartments are connected by the basement membrane (BM), composed of a set of distinct glycoproteins and proteoglycans. Herein we are reviewing molecular aspects of BM structure, composition, and function regarding not only (i) the dermoepidermal interface but also (ii) the resident microvasculature, primarily focusing on theper senonscaffold forming components perlecan and nidogen-1 and nidogen-2. Depletion or functional deficiencies of any BM component are lethal at some stage of development or around birth, though BM defects vary between organs and tissues. Lethality problems were overcome by developmental stage- and skin-specific gene targeting or by cell grafting and organotypic (3D) cocultures of normal or defective cells, which allows recapitulating BM formationde novo. Thus, evidence is accumulating that BM assembly and turnover rely on mechanical properties and composition of the adjacent ECM and the dynamics of molecular assembly, including further “minor” local components, nidogens largely functioning as catalysts or molecular adaptors and perlecan as bridging stabilizer. Collectively, orchestration of BM assembly, remodeling, and the role of individual players herein are determined by the developmental, tissue-specific, or functional context.
Effects of a Commercial Canine Gonadotropin Releasing Hormone Vaccination on Intact Male Llamas and Alpacas
Authors: Donovan C. E. , Grossman J. L. , Patton K. M. , Lamb S. , Bobe G. , Kutzler M. A.
Published: March 2013

We have investigated the effect of immunization against gonadotropin releasing hormone (GnRH) using a commercial canine GnRH vaccine on testosterone concentration, testicular volume, testicular histology, and intermale behavior in intact male llamas and alpacas. Llamas (n=28) and alpacas (n=20) were either immunized (received 3 mL of vaccine given intramuscularly) or treated as controls (received 3 mL of sterile diluent given intramuscularly) at 0, 3, and 6 weeks. Blood samples and testicular volume measurements were taken at 0, 3, 6, 9, and 12 weeks. Owner surveys grading behavior at 0 and 12 weeks were received for 14 llamas. Two llamas at each time point undergoing the vaccination procedure were also castrated for testicular histological examination. Vaccinated animals elicited a GnRH antibody titer, and there was a significant decrease in testosterone concentration and testicular volume when compared with control animals. Intermale aggressive behavior was also significantly decreased in the surveyed llamas. However, histological examination revealed no significant changes. GnRH immunization using the canine GnRH vaccine may be an effective method for reducing intermale aggression in llamas and alpacas by decreasing circulating testosterone concentrations but cannot be recommended as an immunosterilant because of its lack of efficacy in interrupting spermatogenesis.
CDBA Based Universal Inverse Filter
Authors: Pandey Rajeshwari , Pandey Neeta , Negi Tushar , Garg Vivek
Published: March 2013

Current difference buffered amplifier (CDBA) based universal inverse filter configuration is proposed. The topology can be used to synthesize inverse low-pass (ILP), inverse high-pass (IHP), inverse band-pass (IBP), inverse band-reject (IBR), and inverse all-pass filter functions with appropriate admittance choices. Workability of the proposed universal inverse filter configuration is demonstrated through PSPICE simulations for which CDBA is realized using current feedback operational amplifier (CFOA). The simulation results are found in close agreement with the theoretical results.
ZnO‐Based Transparent Conductive Thin Films: Doping, Performance, and Processing
Authors: Liu Yanli , Li Yufang , Zeng Haibo
Published: March 2013

ZnO‐based transparent conductive thin films have attracted much attention as a promising substitute material to the currently used indium‐tin‐oxide thin films in transparent electrode applications. However, the detailed function of the dopants, acting on the electrical and optical properties of ZnO‐based transparent conductive thin films, is not clear yet, which has limited the development and practical applications of ZnO transparent conductive thin films. Growth conditions such as substrate type, growth temperature, and ambient atmosphere all play important roles in structural, electrical, and optical properties of films. This paper takes a panoramic view on properties of ZnO thin films and reviews the very recent works on new, efficient, low‐temperature, and high‐speed deposition technologies. In addition, we highlighted the methods of producing ZnO‐based transparent conductive film on flexible substrate, one of the most promising and rapidly emerging research areas. As optimum‐processing‐parameter conditions are being obtained and their influencing mechanism is becoming clear, we can see that there will be a promising future for ZnO‐based transparent conductive films.
TNNT2Gene Polymorphisms Are Associated with Susceptibility to Idiopathic Dilated Cardiomyopathy in the Han Chinese Population
Authors: Li Xiaoping , Wang Huan , Luo Rong , Gu Haiyong , Zhang Channa , Zhang Yu , Hui Rutai , Wu Xiushan , Hua Wei
Published: March 2013

Background. Idiopathic dilated cardiomyopathy (DCM) is characterized by ventricular chamber enlargement and systolic dysfunction. The pathogenesis of DCM remains uncertain, and theTNNT2gene is potentially associated with DCM. To assess the role ofTNNT2in DCM, we examined 10 tagging single nucleotide polymorphisms (SNPs) in the patients.Methods. A total of 97 DCM patients and 189 control subjects were included in the study, and all SNPs were genotyped by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.Results. In theTNNT2gene, there was a significant association between DCM and genotype for the tagging SNPs rs3729547 (χ2=6.63,P=0.036,OR=0.650, and 95% CI = 0.453–0.934) and rs3729843 (χ2=9.787,P=0.008,OR=1.912, and 95% CI = 1.265–2.890) in the Chinese Han population. Linkage disequilibrium (LD) analysis showed that the SNPs rs7521796, rs2275862, rs3729547, rs10800775, and rs1892028, which are approximately 6 kb apart, were in high LD (D′>0.80) in the DCM patients.Conclusion. These results suggest that theTNNT2polymorphisms might play an important role in susceptibility to DCM in the Chinese Han population.
Bilateral Intracavernous Carotid Artery Aneurysms Presenting as Diplopia in a Young Patient
Authors: Kopsachilis Nikolaos , Pefkianaki Maria , Carifi Gianluca , Lialias Ioannis
Published: March 2013

Introduction. Bilateral intracavernous carotid artery aneurysms (ICAAs) are extremely rare and difficult to treat.Case Report. A 26-year-old female presented in our clinic with acute diplopia due to oculomotor nerve palsy on the left side. Magnetic resonance imaging of the brain showed two heterogeneously enhanced masses indicating bilateral ICAA. An endovascular coil embolization was performed on the left side successfully, resulting in resolution of her symptoms.Conclusion. Thorough systemic evaluation in young patients with diplopia can reveal life-threatening underlying pathology and prevent major complications.
Benzo[1,5]thiazepine: Synthesis, Reactions, Spectroscopy, and Applications
Authors: El-Bayouki Khairy A. M.
Published: March 2013

This review article deals with synthesis and reactions of benzo[1,5]thiazepines and the related derivatives and their applications, biological activity as well as spectroscopic data. Most of the reported data on the methods of synthesis, chemical reactions, and biological activity of these heterocycles published over the last ten years are reviewed in this paper.
Ethanol- and/or Taurine-Induced Oxidative Stress in Chick Embryos
Authors: Berning Emily J. , Bernhardson Noah , Coleman Kelly , Farhat Dina A. , Gushrowski Courtney M. , Lanctot Alison , Maddock Benjamin H. , Michels Kathryn G. , Mugge Luke A. , Nass Catherine M. , Yearsley Sarah M. , Miller Robert R.
Published: March 2013

Because taurine alleviates ethanol- (EtOH-) induced lipid peroxidation and liver damage in rats, we asked whether exogenous taurine could alleviate EtOH-induced oxidative stress in chick embryos. Exogenous EtOH (1.5 mmol/Kg egg or 3 mmol/Kg egg), taurine (4 μmol/Kg egg), or EtOH and taurine (1.5 mmol EtOH and 4 μmol taurine/Kg egg or 3 mmol EtOH and 4 μmol taurine/Kg egg) were injected into fertile chicken eggs during the first three days of embryonic development (E0–2). At 11 days of development (midembryogenesis), serum taurine levels and brain caspase-3 activities, homocysteine (HoCys) levels, reduced glutathione (GSH) levels, membrane fatty acid composition, and lipid hydroperoxide (LPO) levels were measured. Early embryonic EtOH exposure caused increased brain apoptosis rates (caspase-3 activities); increased brain HoCys levels; increased oxidative-stress, as measured by decreased brain GSH levels; decreased brain long-chain polyunsaturated levels; and increased brain LPO levels. Although taurine is reported to be an antioxidant, exogenous taurine was embryopathic and caused increased apoptosis rates (caspase-3 activities); increased brain HoCys levels; increased oxidative-stress (decreased brain GSH levels); decreased brain long-chain polyunsaturated levels; and increased brain LPO levels. Combined EtOH and taurine treatments also caused increased apoptosis rates and oxidative stress.
Expression and Regulation of 11-β Hydroxysteroid Dehydrogenase Type 2 Enzyme Activity in the Glucocorticoid-Sensitive CEM-C7 Human Leukemic Cell Line
Authors: Garbrecht Mark R. , Schmidt Thomas J.
Published: March 2013

Glucocorticoids are commonly used in the first-line treatment of hematological malignancies, such as acute lymphoblastic leukemia, due to the ability of these steroids to activate pro-apoptotic pathways in human lymphocytes. The goal of the current study was to examine the gene expression and enzyme activity of the microsomal enzyme, 11-β hydroxysteroid dehydrogenase type 2 (HSD11B2, HSD2), which is responsible for the oxidation of bioactive glucocorticoids to their inert metabolites. Using the glucocorticoid-sensitive human leukemic cell line, CEM-C7, we were able to detect the expression of HSD2 at the level of mRNA (via RT-PCR), protein (via immunohistochemistry and immunoblotting), and enzyme activity (via conversion of tritiated cortisol to cortisone). Furthermore, we observed that HSD2 enzyme activity is down regulated in CEM-C7 cells that were pretreated with the synthetic glucocorticoid, dexamethasone (100 nM, <15 hours), and that this down regulation of enzyme activity is blocked by the administration of the glucocorticoid receptor antagonist, RU-486. Taken collectively, these data raise the possibility that the effectiveness of glucocorticoids in the treatment of human leukemias may be influenced by: (1) the ability of these neoplastic cells to metabolize glucocorticoids via HSD2 and (2) the ability of these steroids to regulate the expression of this key enzyme.
Development of a Broad-Range 23S rDNA Real-Time PCR Assay for the Detection and Quantification of Pathogenic Bacteria in Human Whole Blood and Plasma Specimens
Authors: Gaibani Paolo , Mariconti Mara , Bua Gloria , Bonora Sonia , Sassera Davide , Landini Maria Paola , Mulatto Patrizia , Novati Stefano , Bandi Claudio , Sambri Vittorio
Published: March 2013

Molecular methods are important tools in the diagnosis of bloodstream bacterial infections, in particular in patients treated with antimicrobial therapy, due to their quick turn-around time. Here we describe a new broad-range real-time PCR targeting the 23S rDNA gene and capable to detect as low as 10 plasmid copies per reaction of targeted bacterial 23S rDNA gene. Two commercially available DNA extraction kits were evaluated to assess their efficiency for the extraction of plasma and whole blood samples spiked with different amount of eitherStaphylococcus aureusorEscherichia coli, in order to find the optimal extraction method to be used. Manual QIAmp extraction method with enzyme pre-treatment resulted the most sensitive for detection of bacterial load. Sensitivity of this novel assay ranged between 10 and 103 CFU per PCR reaction forE. coliandS. aureusin human whole blood samples depending on the extraction methods used. Analysis of plasma samples showed a 10- to 100-fold reduction of bacterial 23S rDNA in comparison to the corresponding whole blood specimens, thus indicating that whole blood is the preferential sample type to be used in this real-time PCR protocol. Our results thus show that the 23S rDNA gene represents an optimal target for bacteria quantification in human whole blood.
Preparation of Nanocomposite Based on Exfoliation of Montmorillonite in Acrylamide Thermosensitive Polymer
Authors: Zabarjad Shiraz Nader , Enferad Elham , Monfared Aazam , Mojarrad Mohammad Ali
Published: March 2013

Poly(N-isopropylacrylamide) (PNIPAM) was synthesized in the presence of AIBN as radical initiator. The structure of polymer was elucidated using IR, 1H NMR, and 13C NMR spectroscopies and TGA thermogram. Exfoliated nanocomposite based on thermosensitive polymer (PNIPAM) was prepared utilizing montmorillonite (MMT) by solution blending. Its dispersion characteristics were investigated using SEM, X-ray diffraction, and particle size analysis. XRD showed exfoliation of MMT in polymer matrix above lower critical solution temperature (LCST). SEM indicated that polymer chains were dispersed among the layers of MMT. Particle size analysis showed two distinctive regions at 311 (31/5%) and 1160 (68/5%) nm.