bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of the ORR Activity of Carbon Supported PtCo/C and PtSnCo/C Electrocatalysts for PEM Fuel Cells
Authors: Ozenler Sibel , Sahin Nihat , Akaydin Beril , Ovecoglu Lutfi , Genc Aziz , Léger Jean-Michel , Napporn Teko W. , Kadirgan Figen
Published: October 2011

Besides producing clean energy via fuel cells, the costs and activations of catalysts have a great importance. In order to reduce cathode activation losses due to comparably sluggish kinetics of oxygen reduction reaction, more active catalysts than Pt should be used. Mostly, noble metals are alloyed with second or third metal as cathode catalysts in order to obtain a synergistic effect. The objective of this study is to improve and enhance the electrocatalytic activities and to lower costs of Pt-based cathode catalysts. Microwave assisted polyol synthesis is used to synthesize bimetallic or ternary catalysts in a very short time with particle size smaller than 10 nm. PtCo/C and PtSnCo/C electrocatalysts is shown ORR activities higher than Pt/C catalyst. Effect of the addition of Co and/or Co and Sn catalyst to Pt/C over ORR kinetic is investigated. Characterization of catalysts is carried out by electrochemical, spectroscopic and microscopic methods.
Synthesis of Pt-Based Electrocatalysts with Core-Shell Structure through Electrochemical Reduction for Oxygen Reduction in PEMFC
Authors: Choi Insoo , Lim Taeho , Ahn Sang Hyun , Kwon Oh Joong , Kim Jae Jeong
Published: October 2011

It has been largely emphasized to reduce the use of Pt in fuel cell, because the price of Pt has ever-increased over the past years. Therefore, people have been trying to develop new types of Pt-based electrocatalyst where less amount of Pt was needed. The objective of this study is to suggest that electrochemical reduction could play a crucial role to fabricate Pt-based catalyst having core-shell structure. Electrochemical reduction of Cu was used to form Cu ad-layer which was later displaced with Pt, and electrochemical reduction of Pt was employed to make Pt layer on colloidal silica. The catalysts were characterized by XRD, XPS, TEM, and ICP-AES. The catalytic activities of both catalysts were examined by cyclic voltammetry or linear sweep voltammetry in a conditioned environment and compared to those of commercial Pt-only catalyst.
Electrocatalytic Activities of Ru85Se15 Catalysts Prepared by Microwave Method
Authors: Zheng Qiaoming , Lia Haixia , Cheng Xuan , Jao Ting-Chu , Weng Fang-Bor , Su Ay , Chiang Yu-Chun
Published: October 2011

The Vulcan carbon black (XC-72R) supported or multiwalled carbon nanotubes (MWCNTs) supported Ru85Se15 nonoparticles were synthesized by microwave assisted method at different pH. The XC-72R and MWCNTs supports were functionalized using citric acid treatment. Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and rotating disk electrode (RDE) techniques were applied for characterizations of the obtained catalysts. The results revealed that the smaller sized Ru85Se15 nanoparticles were better dispersed on citric acid treated XC-72R or MWCNTs supports prepared at pH=7, and the Ru85Se15 catalysts possessed high electrocatalytic activities for oxygen reduction reaction in acidic solutions both in the absence and presence of methanol.
Enhanced Methanol Electro-Oxidation on Pt-Ru Decorated Self-Assembled TiO2-Carbon Hybrid Nanostructure
Authors: Nishanth Karimbintherikkal G. , Sridhar Parthasarathi , Pitchumani Sethuraman , Shukla Ashok K.
Published: October 2011

Porous titanium oxide-carbon hybrid nanostructure (TiO2-C) is directly synthesized via supramolecular self-assembly with in situ crystallization process. TiO2-C supported Pt-Ru electrocatalyst (Pt-Ru/TiO2-C) is synthesized and investigated as an alternative anode catalyst for direct methanol fuel cells (DMFCs). TiO2-C with a specific surface area of 350m2/g and an average pore radius of 21.8Aå has been synthesized. X-ray diffraction, Raman spectroscopy and Transmission electron microscopy (TEM) have been employed to evaluate the crystalline nature and the structural properties of TiO2-C. TEM images reveal uniform distribution of Pt-Ru nanoparticles (dPt-Ru =1.5-3.5 nm) on TiO2-C. The methanol oxidation and accelerated durability (ADT) studies for Pt-Ru/TiO2-C show enhanced catalytic activity and durability, respectively compared to that for carbon supported Pt-Ru. DMFC employing Pt-Ru/TiO2-C as an anode catalyst delivers a peak-power density of 91mW/cm2 at 65ºC as compared to the peak-power density of 60mW/cm2 obtained with carbon supported Pt-Ru catalyst under similar conditions.
Improved Platinum Electrocatalyst for the Oxygen Reduction Reaction Using Nitrogen-Modified Carbon Support
Authors: Herrmann-Geppert Iris , Radnik Joerg , Kramm Ulrike I. , Fiechter Sebastian , Bogdanoff Peter
Published: October 2011

Platinum electrocatalysts for the oxygen reduction reaction have been prepared by impregnation of platinum acetylacetonate on pristine and NH3 treated Black Pearls. The subsequent heat treatment leads to electrochemical active platinum particles in nmscale (2 - 3 nm). By electrochemical measurements (CV and RDE), the platinum surface properties and their activity in the ORR were investigated. Structural and chemical analysis of the catalysts have been performed by means of XPS, XRD and TEM. From the correlation between the electrochemical and structural results it can be concluded that the nitrogen modified carbon surface provides an improved linkage of the platinum particles to the carbon surface. Furthermore the chemical functionalisation of the support takes obviously influence on the surface formation of the platinum nanoparticles so that their electrochemical activity is increased.
PtNb Deposited on High Surface Area Carbon Support as Catalyst for Ethanol Electroxidation
Authors: De Araújo Rocha Thairo , Linares José J. , González Ernesto R.
Published: October 2011

Platinum-niobium catalysts have been proposed as alternative catalysts for ethanol electro-oxidation. Catalysts prepared by a combined alcohol-sodium borohydride reduction method showed crystal sizes in the range of 3-4 nm, with large amounts of niobium oxide, as TPR results confirmed. Platinum decorated on a mixture of Nb2O5 (amorphous and crystalline)/Vulcan XC-72R carbon black was also prepared , with similar crystal sizes. XANES region analyses showed a certain electronic effect in the case of the co-reduction of the two metals, in which a slight alloy fraction was detected. CO stripping results displayed a promising performance of the PtNb/C catalyst, with a small onset potential and a large current density for CO oxidation. Ethanol oxidation tests demonstrated a larger specific activity for the PtNb2O5 (crystalline)/C compared to the other catalysts. Furthermore, a large efficiency for ethanol oxidation was obtained for this platinum-niobium catalyst.
PtSnCe/C and PtSnIr/C Electrocatalysts for Ethanol Oxidation: DEFC and In Situ FTIR studies
Authors: De Souza Rodrigo F. , Da Silva Júlio César M. , Parreira Luanna S. , D'Villa-Silva Melina , Simões Fernando Carmona , Calegaro Marcelo Luiz , De Giz Martha Janete , Câmara Giuseppe Abíola , Neto Almir Oliveira , Santos Mauro C.
Published: October 2011

In the present work, we investigated PtSnCe/C (68:22:10), PtSnIr/C (33:33:33) and commercial PtSn/C (E-Tek) electrocatalysts as anodes in a DEFC. The effects of decreasing the Pt content in the electrocatalysts were also investigated. The product distributions resulting from the ethanol oxidation reaction (EOR) in acid solutions using PtSnCe/C, PtSnIr/C and the commercial PtSn/C materials as electrocatalysts were determined by in situ FTIR spectroscopy. All of the anodes contained 20% (w/w) metal on carbon. From in situ FTIR experiments using 2.0 mol L-1 ethanol, it was observed that the PtSnCe/C and PtSnIr/C materials led to the formation of acetic acid as the predominant oxidation product. The best results for the EOR were obtained with the PtSnCe/C material. However, it was observed that the PtSnIr/C electrocatalyst material tolerated a decrease in Pt content while still showing good performance.
Design of High-Ionic Conductivity Electrodes for Direct Methanol Fuel Cells
Authors: Schrauth Anthony J. , Chun Jung-Hoon
Published: October 2011

Axiomatic Design Theory is used to analyze the design of conventional DMFC anodes. The difficulty conventional electrode design have satisfying the requirements for ionic conductivity in the anode are shown to lead to functional coupling, and therefore, an inability to meet performance requirements. A new anode design is proposed using embossed ionically conductive channels through the thickness of the electrode. Numerical simulation of the proposed design indicates that ionic resistance is greatly reduced and, crucially, no longer a function of catalyst loading. Electrodes are fabricated with 75 μm diameter posts spaced 175 μm apart. These electrodes are tested with impedance spectroscopy and show a 46% reduction in ionic resistance and a 6% increase in catalyst area available. Cell power is estimated to increase by 4% with the current post geometry, while ideal geometry may be able to deliver 9% power improvement.
Fuel Impurity Effects on High Temperature PBI Based Fuel Cell Membranes
Authors: Qian Guoqing , Benicewicz Brian C.
Published: October 2011

The effects of key fuel gas impurities (CO and H2S) on the performance of high temperature PBI-based fuel cells were studied. Fuel cells with high temperature PBI-based MEAs (Celtec P-1000) showed excellent tolerance to CO (up to 2 %) at typical operational temperatures (160 - 180 °C). The fuel cell performance was very sensitive to CO content at lower operational temperatures (140 - 120 °C). Fuel cell performance was immediately recovered by switching back to pure hydrogen. Fuel cells with Celtec P-1000 MEAs showed good tolerance to 0.5 ppm H2S and limited tolerance to 25 ppm H2S at temperatures from 120 oC to 180 oC. The fuel cells also showed quick and almost full recovery when the anode gas was switched from 0.5 or 25 ppm H2S containing reformate back to pure hydrogen.
Ultra-Thin Reinforced Ionomer Membranes to Meet Next Generation Fuel Cell Targets
Authors: Kienitz Brian , Kolde Jeff , Priester Sarah , Baczkowski Carole , Crum Matt
Published: October 2011

Over the last 20 years great progress has been made in increasing fuel cell performance and durability while reducing overall system cost, so much so that the commercialization of fuel cells for automotive and stationary applications is nearing economic feasibility. Still, further advances are needed before the potential of polymer electrolyte membrane fuel cells (PEMFC) can be realized. The incorporation of advanced thin reinforced ionomer membranes into the membrane electrode assembly (MEA) has been paramount to PEMFC progress1. Further reductions in membrane thickness are expected to increase fuel cell performance. In addition, thinner membranes reduce cost by reducing the amount of ionomer used in the MEA. Thin unreinforced membranes are likely to have reduced durability as compared to thicker unreinforced membranes2. Therefore new ionomers and reinforcement strategies are required to increase the durability of thin membranes and further enhance performance.
Investigation of Heteropolyacid Based Composite Membranes
Authors: Rajeswari Janarthanan , Ziegler Zachary , Haugen Gregory M. , Hamrock Steven J , Herring Andrew M.
Published: October 2011

Heteropolyacid based inorganic composite material has been prepared by a sol-gel method assisted by a structure director. PFSA-inorganic composite membranes have been prepared with various weight loadings of the composite. The films have been characterized by various techniques such as XRD, IR, SEM and AFM. Proton conductivity of the films modified by the composite inorganic material has been compared with the control PFSA film. Enhanced proton conductivities have been achieved at 95% and 80% RH for the modified films.
A Numerical Study on Defects in High Temperature Membranes through Solidification
Authors: Ahmad Zakaria Y. , Harris Tequila A. L.
Published: October 2011

Defects such as air bubbles in membranes have been shown to arise during manufacturing. These defects can lead to premature degradation or failure in applications such as fuel cells. In this numerical study, a non-isothermal two-phase computational fluid dynamics (CFD) model is created to investigate the behavior of air bubbles entrained in polyphosphoric acid doped polybenzimidazole (PPA/PBI) membrane solution during casting as it progresses through membrane solidification. The enthalpy-porosity method is used in the CFD model to simulate the solidification process. It is shown that initially the air bubbles are semi-circular. However, as the PPA/PBI solution solidifies and passes through the mushy zone, the shape of the air bubbles change to semi- elliptical. Hence, it is found that the air bubbles will not diffuse but rather remain in the membrane post solidification.
Polystyrene-Based Superacidic Ionomers: Synthesis and Proton Exchange Membrane Applications
Authors: Chang Ying , Bae Chulsung
Published: October 2011

A highly efficient sulfonation of syndiotactic polystyrene which involves the iridium-mediated C-H borylation and the following Suzuki coupling with bromoaryl sulfonate compound as the two key steps was developed. The synthetic method enables a convenient tuning of both sulfonation degree and pendant acid structure. Three different ionomers, including fluoroalkyl, aryl and alky sulfonic acids, were prepared and the acidity effect on PEM performance was investigated.
A Comparison between Dialkyl and Monoalkyl Viologens for Use in Direct-Carbohydrate Fuel Cells
Authors: Hansen Dane , Hadley Jason , Read Adam , Manwill Eric , Pitt William , Wheeler Dean
Published: October 2011

Monoalkyl viologens are N-alkyl-4,4'-bipyridine salts that are being considered as catalysts for oxidation of carbohydrates in alkaline media. Cyclic voltammograms of these viologens have been run and the results are reported here. Simple-fuel-cell tests were also run, with homogeneous viologens as catalysts and primarily fructose as fuel, and it was found that, under otherwise identical conditions, the monoalkyl viologens produced a current about 40% of the current produced by the analogous dialkyl viologen. We conclude that bypiridine, immobilized so that it is functionally similar to monoalkyl viologen, should be tested as a heterogeneous catalyst in direct-carbohydrate fuel cells.
Effect of Temperature on CO and Ethanol Oxidation in Alkaline and Acidic Media
Authors: Cremers Carsten , Niether Christiane , Bayer Domnik , Tübke Jens
Published: October 2011

The temperature dependence of CO and ethanol oxidation was investigated in sulfuric acid and in KOH solution to simulate proton exchange membrane and alkaline anion exchange membrane fuel cell conditions. For the CO oxidation, in both the acidic and the alkaline environment an increase of the oxidation currents in a second oxidation wave at potentials above 1 V vs. RHE is observed. For the ethanol oxidation the expected Arrhenius type of behavior is observed in the acidic environment. In the alkaline environment a decrease of current density with temperature is observed under potentiostatic conditions.
Selective Ethylene Glycol Oxidation Reaction for Carbon Neutral Energy Cycle System
Authors: Takeguchi Tatsuya , Arikawa Hidekazu , Yamauchi Miho , Abe Ryu
Published: October 2011

To realize carbon-neutral energy-cycle system, we have started new JST, CREST project. Ethylene glycol was used as energy media, and selective ethylene glycol oxidation reaction was examined. When ethylene glycol is selectively oxidized to oxalic acid, reaction enthalpy, ΔrH, is -940.6 kJ/mol. This means that 79% of energy can be used compared to complete oxidation reaction. Liquid oxalic acid may be able to be photocatalytically reduced to ethylene glycol. In this study, direct-ethylene glycol fuel cells composed of NaCo2O4 and LaSr3Fe3O10 electrolytes and Pt/C, PtRu/C, Pd/C, and Fe-Co-Ni/C anode catalysts were examined. When Fe-Co-Ni/C is used, the fuel cell is completely noble metal free. The fuel cell generates a high output power density of 27 mW/cm2 at current density of 90 mA/cm2To realize carbon-neutral energy-cycle system, we have started new JST, CREST project. Ethylene glycol was used as energy media, and selective ethylene glycol oxidation reaction was examined. When ethylene glycol is selectively oxidized to oxalic acid, reaction enthalpy, ΔrH, is -940.6 kJ/mol. This means that 79% of energy can be used compared to complete oxidation reaction. Liquid oxalic acid may be able to be photocatalytically reduced to ethylene glycol. In this study, direct-ethylene glycol fuel cells composed of NaCo2O4 and LaSr3Fe3O10 electrolytes and Pt/C, PtRu/C, Pd/C, and Fe-Co-Ni/C anode catalysts were examined. When Fe-Co-Ni/C is used, the fuel cell is completely noble metal free. The fuel cell generates a high output power density of 27 mW/cm2 at current density of 90 mA/cm2
Designing Alkaline Exchange Membranes from Scratch
Authors: Sarode Himanshu , Vandiver Melissa A. , Maes Ashley M. , Caire Benjamin , Horan James L. , Yan Yating , Li Yifan , Lindberg Gerrick E. , Dama James F. , Knight Chris , Jorn Ryan , Lenz Martin E. , Kasper Robert , Gu Shuang , Zhang Bingzi , Seifert Sönke , Tsai Tsung-han , Zhang Wen X. , Coughlin E. Bryan , Knauss Daniel M. , Yan Yushan , Voth Gregory A. , Witten Thomas A. , Liberatore Matthew W. , Herring Andrew M.
Published: October 2011

There is increasing interest in the alkaline exchange membrane (AEM) fuel cells as this device, if realized, could allow the use of inexpensive metal catalysts and the oxidation of a variety of convenient liquid fuels. While there have been some dramatic early achievements, there is still a need for a fundamental study of anion transport, cation stability and the formation of robust thin films in this area. We have undertaken a comprehensive study of AEMs where theory is linked to well-defined model systems, both in solution and in the solid state, which are characterized using very careful environmental control such that the models can be validated and used predictively. We are also fabricating a number of random copolymer AEMs that can be produced readily in large quantities, allowing us to understand film formation coupled with transport and stability. Those based on perfluorinated backbones invite interesting comparisons with the analogous proton exchange membranes.
Anion Exchange Membranes (AEMs) with Perfluorinated and Polysulfone Backbones with Different Cation Chemistries
Authors: Arges Christopher G. , Jung Min-Suk , Johnson Graham , Parrondo Javier , Ramani Vijay
Published: October 2011

Perfluorinated (PF) and polysulfone (PSF) backbones have been functionalized with multiple cation chemistries with varying basicities to prepare anion exchange membranes. The different cation and polymer backbone chemistries were evaluated to ascertain their influence on cation stability in alkaline environments, ionic conductivity, water uptake, and fuel cell performance. Evidence from the several cations/backbones studied support the following conclusions: i.) Basicity of the cation is an appropriate heuristic for assessing ionic conductivity, but it is not always appropriate for comparing alkaline stability across cations with different inorganic atoms. ii.) Phosphonium cations with similar or greater basicity than ammonium cations are observed to have less water uptake, but degrade more rapidly since they favor the formation of ylides. iii.) PF backbones with a sulfonyl group adjacent to the cation site exhibit a higher rate of cation site degradation in comparison to PSF backbones that have a benzyl group adjacent to the cation.
Electrospun Composite Membranes for Alkaline Fuel Cells
Authors: Park Andrew M. , Pintauro Peter N.
Published: October 2011

Electrospun fiber composite anion exchange membranes were created by electrospinning two polymers: a chloromethylated polysulfone that would ultimately serve as the hydroxide ion conductor, and an uncharged polyphenylsulfone to limit water swelling and provide mechanical strength to the final membrane. After electrospinning, the chloromethyl groups were converted into quaternary ammonium moieties for hydroxide ion conduction. The polyphenylsulfone fibers were then selectively made to flow and fill the void space in the dual fiber mat, thus forming a dense, defect free membrane. The final membrane morphology was a quaternized polysulfone interconnecting fiber network embedded in a polyphenylsulfone matrix. For a membrane containing 63 vol% anion-exchange polymer fibers (with a fiber IEC of 2.5 mmol g-1), the OH- ion conductivity was high (40 mS cm-1 in 23oC water) and the equilibrium water swelling at room temperature was low (70 vol%).
Maintaining Desired Temperature and Relative Humidity throughout a Fuel Cell
Authors: Barbir Frano , Tolj Ivan , Bezmalinovic Dario
Published: October 2011

A concept of using the product water to internally humidify the air stream in a PEM fuel cell without external humidification is investigated by a simple, pseudo 2-D model along a single channel. This model takes into account the mass and energy balance, water and heat generation rates, heat removal, and water transport through the membrane. The model and thus the concept were confirmed experimentally using a 5-segment fuel cell. The temperature of each segment is individually controlled, and the temperature and humidity of air could are measured between each segment. A temperature profile has been established that results in relative humidity being close to 100% throughout the cell without any external humidification. Such a profile can be acheived by applying spatially variable heat removal rates along the cathode channel. Operation with spatially variable heat removal resulted in improved performance yielding 0.618 V at 0.5 A/cm2 as compared to 0.548 V achieved in the case of isothermal hardware.
Anode Catalysts for the Direct Dimethyl Ether Fuel Cell
Authors: Li Qing , Wu Gang , Johnston Christina M. , Zelenay Piotr
Published: October 2011

For the last decade, dimethyl ether (DME) has been considered a promising alternative fuel for direct fuel cells because of several advantages over methanol. In this work, PtRu catalysts with a wide range of Pt-to-Ru ratios were screened for the direct DME fuel cell(DDMEFC) performance for the first time. Overall, Pt50Ru50 performs best in the high and middle voltage ranges, whereas Pt80Ru20 performs best at low voltages. A maximum power density of 0.10 W/cm2 is achieved at a current density of 0.37 A/cm2. In spite of using gaseous DME feed, the measured performance exceeds the best previously published results. The anode activity and fuel crossover of a DDMEFC were investigated in this work and compared to those of a DMFC. The adsorption and electrooxidation of DME on Pt black catalyst were also studied in halfcell electrochemical measurements.
Use of Electrochemical Methods for Evaluation of Components for Liquid Fuel Cells
Authors: Krishnan Lakshmi , Huang Tracy , Rainka Matthew P. , Zappi Guillermo , Stein Judith , Soloveichik Grigorii
Published: October 2011

An electrochemical study aimed at understanding the kinetic properties of oxidation of liquid organic fuels on a Pt disk was performed using cyclic voltammetry and rotating disk electrode techniques. Carbocyclic organic compounds and N-containing heterocyclic compounds were investigated as fuels. N-containing heterocyclic fuels were oxidized at lower potentials compared to carbocyclic fuels and the RDE behavior of the N-containing heterocycles indicated that the nitrogen atom in the cyclic ring favors proton release. For N-containing heterocyclic fuels having a conjugated ring, the position of the N-atom also impacted the reaction rate due to the resonance effect of the conjugated ring on the N atom.
Electrochemical Behavior of Direct Methanol Fuel Cells Based on Acidic Silica - Sulfonated Polysulfone Composite Membranes
Authors: Baglio Vincenzo , Lufrano Francesco , Di Blasi Orazio , Staiti Pietro , Antonucci Vincenzo , Aricò Antonino S.
Published: October 2011

This paper reports on the research and development of polymer electrolyte membranes based on sulfonated polysulfone and acidic silica materials for application in DMFCs at different operating temperatures. The sulfonated polysulfone (SPSf) was synthesized using trimethyl silyl chlorosulfonate as the sulfonating agent, whereas silica was modified by treatment with chlorosulfonic acid at room temperature. The composite membranes based on sulfonated polysulfone and acidic silica were prepared by using a casting method from dimethylacetamide solutions. The membranes were characterized in terms of ion exchange capacity, methanol/water uptake, proton conductivity and DMFC performance. The membrane containing 10 wt.% of acidic silica showed a promising performance in DMFC investigations at temperatures comprised between 30°C and 60°C. A maximum power density of 60 mW cm-2 was obtained at 60°C feeding 1M methanol solution at the anode and dry air at the cathode, both at atmospheric pressure.
Structure Alteration and Activity Improvement of PdCoAu/C Catalysts for the Oxygen Reduction Reaction
Authors: Wei Yu-Chen , Wang Kuan-Wen
Published: October 2011

In this study, the ternary catalysts in a form of Pd75Co25-xAux/C (x = 5, 15 and 25 in at.%) are synthesized for the oxygen reduction reaction (ORR) through the deposition-precipitation method. The addition of Au in altering structures, surface conditions and electrochemical properties of PdCo catalysts are investigated by the combined exploration of XRD, TEM, cyclic voltammetry (CV) and linear sweep voltammetry (LSV) measurements. XRD results suggest that the incorporation of Au into Pd-Co contributes to the formation of inhomogeneous alloy structure. Regarding the surface condition, CV examination implies that the Pd-rich surface gradually changes to Pd, PdAu or PdCo alloy mixed surface species after Au modification. For the preparation of high effectively catalysts, it is suggested that the addition of Au can prominently promote the ORR activity owing to the presence of inhomogeneous alloys together with alloy mixed surface species.
Stochastic Reconstruction at Two Scales and Experimental Validation to Determine the Effective Electrical Resistivity of a PEMFC Catalyst Layer
Authors: Barbosa Romeli , Escobar Beatriz , Cano Ulises , Pedicini Rolando , Ornelas Rubén , Passalacqua Enza
Published: October 2011

In this paper we report on the application of statistical information obtained from 2D micrographs of catalyst layers (CL) of proton exchange membrane fuel cell (PEMFC), to derive stochastic replicas of their 3D pore networks at two scales. The main focus is on assessing the scaling strategy to determine effective transport coefficients and the analysis of the experimental results. The continuity equation for charge transport is solved directly on the 3D reconstructed CL to determine effective electrical conductivities at "internal-scale" and to simulate the electrical global performance at "macro-scale". The electrical performance is experimentally determined. The applied image processing method makes use of two immediate scales to improve the image resolution. Pore size distribution of the reconstructed scales is used to avoid the superposition of equal pore sizes. The relative porosities were determined by the statistical analysis of SEM micrographs and verified by mercury intrusion porosimetry.
The Mechanism for Ethanol Oxidation Reaction on SnO2@Pt/C Core Shell Electrocatalyst
Authors: Da Silva Júlio César M. , De Souza Rodrigo F. , Calegaro Marcelo Luiz , Santos Mauro C.
Published: October 2011

In the present work we investigated the products distributions from ethanol oxidation reaction (EOR) in acid solutions using SnO2@Pt/C core-shell, PtSn/C E-TEK and Pt/C E-TEK as electrocatalysts assisted by "in situ" ATR-FTIR technique to obtain information about EOR mechanism on these materials. All materials used were 20% (w/w) metal on carbon XC 72-R. From "in situ" ATR-FTIR experiments with ethanol 1.0 mol L-1 it can be seen that the SnO2@Pt/C material led to CO2 formation in great proportion, while that, in Pt/C E-TEK acetic acid and acetaldehyde were the main products. In the chronoamperometry experiments at 0.5 V (vs RHE), the mass current density for ethanol oxidation was higher using SnO2@Pt/C when compared to Pt/C and PtSn/C E-tek.
Rotating Disk Electrode Investigation of Pt/Carbon Electrocatalyst Activity and Durability
Authors: Wang Chunmei , Dale Nilesh V. , Adjemian Kev
Published: October 2011

The effect of various carbon supports on both the platinum (Pt) activity and durability was investigated using rotating disk electrode (RDE) measurements. Pt supported on Vulcan, high surface area, graphitized and heat-treated carbon were evaluated for their electrochemical activity, Pt dissolution and carbon corrosion durability. Cyclic voltammetry and hydrodynamic voltammetry were conducted using Nissan testing protocols. Electrochemical active area (ECA), the area specific and mass specific activities were employed as a measure of electrocatalyst activity. Carbon corrosion and Pt dissolution durability were evaluated as a loss in ECA as a function of potential cycling. The effect of heat-treatment of the catalyst and graphitization of the carbon support on the catalyst's carbon corrosion and Pt dissolution durability is discussed.
Electrochemical Oxidation of Surface Oxides to Partially Recover the Performance of Non-PGM Catalyst under Fuel Cell Operation
Authors: Han Taehee , Dale Nilesh V. , Adjemian Kev , Nallathambi Vijayadurga , Calabrese Barton Scott
Published: October 2011

An iron based metal-nitrogen-carbon (MNC) type oxygen reduction reaction catalyst was tested for in-situ polarization performance and durability. High open circuit voltage (OCV) of ~0.97 V and high activities were observed. Current density around 750 mA/cm2 was obtained at 0.6 ViR-free/RHE and volumetric current density of 31 A/cm3 was obtained at 0.8 ViR-free. A significant decrease in polarization after start-stop durability test was observed for this catalyst. An attempt was made to recover the in-situ performance after start-stop durability test by running the fuel cell at steady state current density. Partial performance recovery was achieved from the significantly degraded MNC based membrane electrode assembly (MEA). However, performance could not be recovered indefinitely due to eventual carbon loss.
Highly Durable Carbon Nanotube-Supported Pd Cathode Catalysts Covered with Silica Layers for Polymer Electrolyte Fuel Cells: Effect of Silica Layer Thickness on the Catalytic Performance
Authors: Takenaka Sakae , Miyamoto Hiroaki , Susuki Naoto , Matsune Hideki , Kishida Masahiro
Published: October 2011

Carbon nanotube-supported Pd catalyst (Pd/CNT) was covered with silica layers a few nanometers thick by successive hydrolysis of 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) to improve the durability of the Pd catalyst under cathode conditions of polymer electrolyte fuel cells (PEFCs). The coverage with silica layers resulted in the improvement of durability of Pd/CNT during the potential cycling between 0.05 and 1.20 V (vs. RHE) in aqueous HClO4 electrolyte. The catalytic activity and durability of silica-coated Pd/CNT strongly depended on silica layer thickness in the catalysts. The coverage with thicker silica layers improved the durability of Pd/CNT but the catalytic activity of the catalysts for the oxygen reduction reaction became lower with silica layer thickness. The coverage of Pd/CNT with silica layers of ca. 3 nm thickness is preferable from a viewpoint of the catalytic activity and durability.
Plantarflexor stretch training increases reciprocal inhibition measured during voluntary dorsiflexion
Authors: Blazevich A. J. , Kay A. D. , Waugh C. , Fath F. , Miller S. , Cannavan D.
Published: October 2011

Agonist-mediated reciprocal inhibition (RI) in distal skeletal muscles is an important neurophysiological phenomenon leading to improved movement coordination and efficiency. It has been shown to be reduced in aged and clinical populations, so the development of interventions augmenting RI is an important research goal. We examined the efficacy of using chronic passive muscle stretching to augment RI. The influence of 3 wk of plantarflexor stretching (4 × 30 s, two times/day) on RI of soleus and gastrocnemius initiated by tonic, voluntary dorsiflexion contractions [20% of maximum voluntary contraction (MVC)] was examined in 11 healthy men who performed stretch training and in nine nontraining controls. Hoffmann's reflexes (H-reflexes) were elicited by tibial nerve stimulation during both weak isometric (2% MVC) plantarflexions and dorsiflexion contractions at 20% MVC. Changes were examined at three joint angles, normalized to each subject's range of motion (ROM; plantarflexed = 10 ± 0°, neutral = −3.3 ± 2.9°, dorsiflexed = −16.5 ± 5.6°). No changes were detected in controls. A 20% increase in ROM in the stretch subjects was associated with a significant decrease in maximum H-reflex (Hmax): maximum evoked potential (Mmax), measured during 2% plantarflexion at the plantarflexed and neutral angles in soleus and at the plantarflexed angle in gastrocnemius ( P < 0.05–0.01). By contrast, decreases in Hmax:Mmax during 20% dorsiflexion contract were also seen at each angle in soleus and at the dorsiflexed angle in gastrocnemius. However, a greater decrease in Hmax:Mmax measured during voluntary dorsiflexion rather than during plantarflexion, which indicates a specific change in RI, was detected only at the dorsiflexed angle (−30.7 ± 9.4% and −35.8 ± 6.8% for soleus and gastrocnemius, respectively). These results demonstrate the efficacy of soleus-gastrocnemius stretch training in increasing agonist-mediated RI from tibialis anterior onto soleus-gastrocnemius in young, healthy individuals at dorsiflexed, but not plantarflexed, joint angles.
Influence of pH, Precursor Concentration, Growth Time, and Temperature on the Morphology of ZnO Nanostructures Grown by the Hydrothermal Method
Authors: Amin G. , Asif M. H. , Zainelabdin A. , Zaman S. , Nur O. , Willander M.
Published: October 2011

We investigated the influence of the pH value, precursor concentration (C), growth time and temperature on the morphology of zinc oxide (ZnO) nanostructures. The pH of the starting solution was varied from 1.8 to 12.5. It was found that the final pH reaches an inherent value of 6.6 independently of the initial pH solution. Various ZnO structures of nanotetrapod-like, flower-like, and urchin-like morphology were obtained at alkaline pH (8 to 12.5) whereas for pH solution lower than 8 rod-like nanostructures occurred. Moreover, we observed the erosion of the nanorods for a pH value less than 4.6. By changing the concentrations the density and size were also varied. On going from a high (C>400 mM) to lower (C<25 mM)C, the resulted ZnO nanostructures change from a film to nanorods (NRs) and finally nanowires (NWs). It was also found that the length and diameter of ZnO NRs follow a linear relation with time up to 10 hours, above which no further increase was observed. Finally the effect of growth temperature was seen as an influence on the aspect ratio.
Nonlinear Vibrations of Multiwalled Carbon Nanotubes under Various Boundary Conditions
Authors: Aminikhah Hossein , Hemmatnezhad Milad
Published: October 2011

The present work deals with applying the homotopy perturbation method to the problem of the nonlinear oscillations of multiwalled carbon nanotubes embedded in an elastic medium under various boundary conditions. A multiple‐beam model is utilized in which the governing equations of each layer are coupled with those of its adjacent ones via the van der Waals interlayer forces. The amplitude‐frequency curves for large‐amplitude vibrations of single‐walled, double‐walled, and triple‐walled carbon nanotubes are obtained. The influences of some commonly used boundary conditions, changes in material constant of the surrounding elastic medium, and variations of the nanotubes geometrical parameters on the vibration characteristics of multiwalled carbon nanotubes are discussed. The comparison of the generated results with those from the open literature illustrates that the solutions obtained are of very high accuracy and clarifies the capability
and the simplicity of the present method. It is worthwhile to say that the results generated are new and can be served as a benchmark for future works.
Enhancement of Heat Transfer by Ultrasound: Review and Recent Advances
Authors: Legay Mathieu , Gondrexon Nicolas , Le Person Stéphane , Boldo Primius , Bontemps André
Published: October 2011

This paper summarizes some applications of ultrasonic vibrations regarding heat transfer enhancement techniques. Research literature is reviewed, with special attention to examples for which ultrasonic technology was used alongside a conventional heat transfer process in order to enhance it. In several industrial applications, the use of ultrasound is often a way to increase productivity in the process itself, but also to take advantage of various subsequent phenomena. The relevant example brought forward here concerns heat exchangers, where it was found that ultrasound not only increases heat transfer rates, but might also be a solution to fouling reduction.
Improved Method of Blind Speech Separation with Low Computational Complexity
Authors: Kondo Kazunobu , Takahashi Yu , Hashimoto Seiichi , Saruwatari Hiroshi , Nishino Takanori , Takeda Kazuya
Published: October 2011

A blind speech separation method with low computational complexity is proposed. This method consists of a combination of independent component analysis with frequency band selection, and
a frame‐wise spectral soft mask method based on an interchannel power ratio of tentative separated signals in the frequency domain. The soft mask cancels the transfer function between sources and separated signals. A theoretical analysis of selection criteria and the soft mask is given. Performance and effectiveness are evaluated via source separation simulations and a computational estimate, and experimental results show the significantly improved performance of the proposed method. The segmental signal‐to‐noise ratio achieves 7 [dB] and 3 [dB], and the cepstral distortion achieves 1 [dB] and 2.5 [dB], in anechoic and reverberant conditions, respectively. Moreover, computational complexity is reduced by more than 80% compared with unmodified FDICA.
An Examination of Palliative or End-of-Life Care Education in Introductory Nursing Programs across Canada
Authors: Wilson Donna M. , Goodwin Barbara L. , Hewitt Jessica A.
Published: October 2011

An investigation was done to assess for and describe the end-of-life education provided in Canadian nursing programs to prepare students for practice. All 35 university nursing schools/faculties were surveyed in 2004; 29 (82.9%) responded. At that time, all but one routinely provided this education, with that school developing a course (implemented the next year). As compared to past surveys, this survey revealed more class time, practicum hours, and topics covered, with this content and experiences deliberately planned and placed in curriculums. A check in 2010 revealed that all of these schools were providing death education similar to that described in 2004. These findings indicate that nurse educators recognize the need for all nurses to be prepared to care for dying persons and their families. Regardless, more needs to be done to ensure novice nurses feel capable of providing end-of-life care. Death education developments will be needed as deaths increase with population aging.
Tridimensional Regression for Comparing and Mapping 3D Anatomical Structures
Authors: Schmid Kendra K. , Marx David B. , Samal Ashok
Published: October 2011

Shape analysis is useful for a wide variety of disciplines and has many applications. There are many approaches to shape analysis, one of which focuses on the analysis of shapes that are represented by the coordinates of predefined landmarks on the object. This paper discusses Tridimensional Regression, a technique that can be used for mapping images and shapes that are represented by sets of three-dimensional landmark coordinates, for comparing and mapping 3D anatomical structures. The degree of similarity between shapes can be quantified using the tridimensional coefficient of determination (). An experiment was conducted to evaluate the effectiveness of this technique to correctly match the image of a face with another image of the same face. These results were compared to the values obtained when only two dimensions are used and show that using three dimensions increases the ability to correctly match and discriminate between faces.
Identification of Adipophilin as a Potential Plasma Biomarker for Colorectal Cancer Using Label-Free Quantitative Mass Spectrometry and Protein Microarray
Authors: Matsubara Junichi , Honda Kazufumi , Ono Masaya , Sekine Shigeki , Tanaka Yoshinori , Kobayashi Michimoto , Jung Giman , Sakuma Tomohiro , Nakamori Shoji , Sata Naohiro , Nagai Hideo , Ioka Tatsuya , Okusaka Takuji , Kosuge Tomoo , Tsuchida Akihiko , Shimahara Masashi , Yasunami Yohichi , Chiba Tsutomu , Yamada Tesshi
Published: October 2011

Background: The aim of this study was to identify a new plasma biomarker for use in early detection of colorectal cancer.

Methods: Using the combination of hollow fiber membrane (HFM)-based low-molecular weight protein enrichment and two-dimensional image converted analysis of liquid chromatography and mass spectrometry (2DICAL), we compared the plasma proteome of 22 colorectal cancer patients with those of 21 healthy controls. An identified biomarker candidate was then validated in two larger cohorts [validation-1 (n = 210) and validation-2 (n = 113)] using a high-density reverse-phase protein microarray.

Results: From a total of 53,009 mass peaks, we identified 103 with an area under curve (AUC) value of 0.80 or higher that could distinguish cancer patients from healthy controls. A peak that increased in colorectal cancer patients, with an AUC of 0.81 and P value of 0.0004 (Mann–Whitney U test), was identified as a product of the PLIN2 gene [also known as perilipin-2, adipose differentiation-related protein (ADRP), or adipophilin]. An increase in plasma adipophilin was consistently observed in colorectal cancer patients, including those with stage I or stage II disease (P < 0.0001, Welch's t test). Immunohistochemical analysis revealed that adipophilin is expressed primarily in the basal sides of colorectal cancer cells forming polarized tubular structures, and that it is absent from adjacent normal intestinal mucosae.

Conclusions: Adipophilin is a plasma biomarker potentially useful for the detection of early-stage colorectal cancer.

Impact: The combination of HFM and 2DICAL enables the comprehensive analysis of plasma proteins and is ideal for use in all biomarker discovery studies. Cancer Epidemiol Biomarkers Prev; 20(10); 2195–203. ©2011 AACR.
Impact of Survivorship-Based Research on Defining Clinical Care Guidelines
Authors: Hudson Melissa M. , Landier Wendy , Ganz Patricia A.
Published: October 2011

The growing number of individuals living five or more years from cancer diagnosis underscores the importance of providing guidance about potential late treatment effects to clinicians caring for long-term cancer survivors. Late treatment effects are commonly experienced by cancer survivors, increase in prevalence with aging, produce substantial morbidity, and predispose to early mortality. Findings from survivorship research permit providers to anticipate health risks among predisposed survivors and facilitate their access to interventions to prevent, detect, or rehabilitate cancer-related morbidity. This article reviews the impact that survivorship research has made in defining clinical care guidelines and the challenges that remain in developing and translating research findings into health screening recommendations that can optimize the quality and duration of survival after cancer. Cancer Epidemiol Biomarkers Prev; 20(10); 2085–92. ©2011 AACR.
Molecular Insights on the Peripheral and Intratumoral Effects of Systemic High-Dose rIL-2 (Aldesleukin) Administration for the Treatment of Metastatic Melanoma
Authors: Weiss Geoffrey R. , Grosh William W. , Chianese-Bullock Kimberly A. , Zhao Yingdong , Liu Hui , Slingluff Craig L. , Marincola Francesco M. , Wang Ena
Published: October 2011

Purpose: We have previously shown that within tumors, recombinant interleukin-2 (rIL-2, aldesleukin) consistently activates tumor-associated macrophages and upregulates IFN-stimulated genes while inducing minimal migration, activation, or proliferation of T cells. These effects are independent of tumor response to treatment. Here, we prospectively evaluated transcriptional alterations induced by rIL-2 in peripheral blood mononuclear cells (PBMC) and within melanoma metastases.

Experimental Design: We evaluated gene expression changes by serially comparing pre- to posttreatment samples in 13 patients and also compared transcriptional differences among lesions displaying different responsiveness to therapy, focusing on 2 lesions decreasing in size and 2 remaining stable (responding lesions) compared with nonresponding ones.

Results: As previously described, the effects of rIL-2 were dramatic within PBMCs, whereas effects within the tumor microenvironment were lesion specific and limited. However, distinct signatures specific to response could be observed in responding lesions pretreatment that were amplified following rIL-2 administration. These signatures match the functional profile observed in other human or experimental models in which immune-mediated tissue-specific destruction (TSD) occurs, underscoring common pathways leading to rejection. Moreover, the signatures observed in pretreatment lesions were qualitatively similar to those associated with TSD, underlining a determinism to immune responsiveness that depends upon the genetic background of the host or the intrinsic genetic makeup of individual tumors.

Conclusions: This is the first prospectively collected insight on global transcriptional events occurring during high-dose rIL-2 therapy in melanoma metastases responding to treatment. Clin Cancer Res; 17(23); 7440–50. ©2011 AACR.