bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic Monte Carlo Approach to the Effects of Additives in Electrodeposition
Authors: Kaneko Yutaka , Hiwatari Yasuaki , Ohara Katsuhiko , Asa Fujio
Published: October 2011

The effects of additives in copper electrodeposition have been studied by using the multi-scale kinetic Monte Carlo simulation. Recently we have extended the solid-by-solid model for crystal growth to a multiple scale model for the simulation of the copper deposition from electrolytic solution. The system consists of the electrode, the solution and the diffusion layer. The solution contains copper ions and the model additives of chloride ions, polyethylene glycol (PEG) and bis(3-sulfopropyl) disulfide (SPS). We have performed the simulations of copper deposition with different combinations of the additives and studied the surface morphology. The suppressing effect of PEG and the accelerating effect of SPS have been confirmed.
Tafel Slope Component Analysis of Polymer Electrolyte Fuel Cell Cathode Current-Potential Behavior
Authors: Tryk Donald A. , Lee Myoung S. , Uchida Makoto , Uchida Hiroyuki , Watanabe Masahiro
Published: October 2011

The current-potential behavior of the polymer electrolyte fuel cell cathode has been subjected to a new type of curve-fitting analysis that is not based on a specific model but rather utilizes a series of Tafel slope components: a primary slope, with an effective transfer coefficient αc,eff of close to unity, plus a doubled component (αc,eff ca. 1/2), a quadrupled component (αc,eff ca. 1/4) and a limiting current, the latter being necessary for air feed. With this approach, we are able to fit single-cell data within experimental error. The parameters can be used conveniently to compare the performance of different cathodes.
Study of SEI Formation in Li-Ion Batteries by Acoustic Emission Technique
Authors: Kircheva Nina , Thivel Pierre-Xavier , Genies Sylvie , Brun-Buisson David , Bultel Yann
Published: October 2011

This paper has the aim to demonstrate that Acoustic Emission (AE) is an appropriate technique to be a diagnostics tool for state of charge, state of health of state of security of lithium-ion cells. This issue is actually a key parameter for both performance and durability improvement. The presented results concern the survey of the SEI formation and the first lithium ion intercalation on the surface and inside the graphite electrode. AE events coming from different sources have thus been identified. A large number of acoustic emission events occur during the film formation corresponding to gas evolution and cracking processes appearing at the electrode surface (lithium intercalation). The acoustic emission signals were analyzed and correlated with electrochemical phenomena taking place during the cell operation.
STEP Decrease of Anthropogenic CO2: Solar Thermal Electrochemical Production of Energetic Molecules, A Different Solar Energy Conversion Process
Authors: Licht Stuart , Wu Hongjun , Wang Baohui , Lau Jason , Hettige Chaminda
Published: October 2011

STEP, the Solar Thermal Electrochemical Production of energetic molecules uses the whole spectrum of sunlight to produce useful chemicals, rather than electricity. The STEP process powers a high temperature molten electrolysis to produce useful chemicals including metals, such as iron and magnesium, fuels and bleach. Utilizing molten salts, the system has the potential to operate 24/7 without interruption from lack of sunlight. High temperature decreases the chemical production voltage to a small fraction of the room temperature electrolysis potential through the absorption of solar thermal energy. As one example, carbon dioxide is converted from its 0.03% concentration in air, directly to carbonate, which is reduced to form fuels at 50% solar energy conversion efficiency. The lithiated oxide/carbonate electrolyte spontaneously absorbs CO2. Carbonate is the reactant, which is renewed through CO2 absorption, and is efficiently reduced at high rate, low electrolysis potential, and high solar efficiency.
Voltammetry of Aniline in 9:1 Acetonitrile/Water
Authors: Haque Inam U. , Asghar Kaleem Abbas , Sadaf Shamaila , Tariq Muqaddas , Khan Asim , Rashid Ashi
Published: October 2011

This work relates to the electrochemistry of aniline in acetonitrile, in water and in the mixture of acetonitrile + water, in the presence of picrate buffers, at platinum electrode using different voltammetric techniques, e.g. cyclic, normal pulse and differential pulse voltammetry. Results suggested that nature of the solvent led to change in the reaction pathways as evident from variation of peak potential for the anodic oxidation of aniline.
Study of the EC' Mechanism by Scanning Electrochemical Microscopy (SECM)
Authors: Calhoun Rob , Bard Allen
Published: October 2011

Scanning electrochemical microscopy (SECM) experiments were undertaken to study the EC'mechanism, e.g. where a product of the electrode reaction reacts to regenerate the starting material. Digital simulations of the two dimensional SECM were carried out and the results tested with the known EC' system of Fe(CN)64- / cysteine for validation. The results were then used in SECM experiments with Ru(phen)2dppz2+, a known DNA intercalator, to study the instability of the oxidized form in the absence and presence of DNA.
Anode Processes on Carbon in Chloride-Oxide Melts
Authors: Tunold Reidar , Haarberg Geir Martin , Osen Karen S. , Martinez Ana Maria , Sandnes Espen
Published: October 2011

Alkali and alkaline earth metals such as lithium, sodium, magnesium and calcium are produced by electrowinning in chloride melts. Direct cathodic reduction of metal oxides in chloride melts has been proposed for the FFC process. Fundamental data for the anodic process on carbon in mixed chloride/oxide melts are lacking. Anodes of graphite and vitreous carbon (VC) were studied in NaCl-NaO, and in binary melts of the type NaCl-MCl2-MO with 0-7 mol% oxide, (M = Ca, Sr and Ba), using linear polarization, CV and EIS. The gaseous products were Cl2, CO and CO2 and the exit concentration of carbon oxides were analysed by gas chromatography. In this paper the emphasis is on the NaCl-CaCl2-CaO system.
A Glucose Biofuel Cell to Generate Electricity
Authors: Mecheri Barbara , Geracitano Antonio , D'Epifanio Alessandra , Licoccia Silvia
Published: October 2011

We fabricated an enzymatic fuel cell (EFC) device based on glucose as fuel, the bioanode consisting in a commercial carbon cloth electrode containing the glucose oxidase (GOx) enzyme. The bioanode was prepared by immobilizing GOx in a Nafion matrix. The outcome of the immobilization procedure was tested by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and cyclic voltammetry (CV) which indicated a good catalytic activity and stability of the immobilized enzyme toward the reaction of glucose oxidation. The bioanode was the assembled in a glucose fuel cell, using a ferricyanide cathode and a Nafion 117 membrane as electrolyte. Polarization and power density curves were then acquired to evaluate the electrochemical performance of the EFC device demonstrating the applicability of the GOx-modified electrode as promising bioanode for energy production.
Process Optimization for the Electroenzymatic Hydroxylation of 3-Phenoxytoluene Catalyzed by P450 BM-3
Authors: Güven Guray
Published: October 2011

Bioelectrochemical hydroxylation of 3-phenoxyroluene has been carried out as a model system in which redesigned P450 BM-3 accepting electrons from electrode surface modified with a conducting polymer, poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid (PEDOT/PSS) was used. Experimental runs were performed in accordance with central composite design and conducted batch-wise to visualize the effects of independent factors (thickness of enzyme-polymer layer, applied potential and substrate concentration). Process was optimized with response surface methodology. Optimum conditions at 25ºC were estimated as - 0.70 V (vs. SCE) applied potential, 1.35 mM substrate concentration and ~60.35 nm thickness of enzyme-polymer layer to achieve 330.49 μM of product formation after 6 h of reaction in the presence of catalase. Kinetic studies reveal that electrochemical system can be an alternative and cost-effective electron donor compared to natural cofactor with further improvement of protein engineering strategies.
Fabrication of Horseradish Peroxidase Modified 3D Pt Nanowire Array Electrode and its Electro-Catalytical Activity towards H2O2
Authors: Jamal Mamun , Hasan Maksudul , Mischieri Jennifer , Mathewson Alan , Razeeb Kafil M.
Published: October 2011

A vertically aligned three dimensional (3D) Pt nanowire array electrode has been fabricated by electrodeposition of Pt into an anodic aluminium oxide (AAO) template. After immobilizing horseradish peroxidase (HRP) on this 3D nanowire platform, its electrochemical behavior has been examined for the detection of hydrogen peroxide (H2O2). The HRP/Pt nanowire platform showed a remarkable sensitivity of 345 µAmM-1cm-2 with a linearity range up to 2.5 mM towards H2O2.
Electrochemical Reduction of 4-Iodophenyl Sulfonyl Chloride
Authors: Hamed Emad M. , Houmam Abdelaziz
Published: October 2011

Important aspects of the electrochemical reduction of 4-iodophenyl sulfonyl chloride are investigated in acetonitrile at a glassy carbon electrode. The first electron transfer follows a concerted process where the S-Cl chemical bond is cleaved upon injection of the first electron. An interesting autocatalytic mechanism is encountered and the 4-iodophenyl sulfonyl chloride is reduced both at the electrode and through homogeneous electron transfer from the resulting sulfinate anion. An electron transfer between the generated sulfinate anion and the parent molecule is the basis to the observed autocatalytic process. Consequently, the reduction process depends on both the concentration of the substrate and the scan rate. Gas phase chemical quantum calculations results help to rationalize the mechanism of the first electron transfer.
Electrochemically Initiated Degradation of a New Energetic Material 2,2-Didnitroethene-1,1-Diamine (FOX-7)
Authors: Šimková Ludmila , Ludvík Jiri
Published: October 2011

The recently synthesized energetic material 2,2-dinitroethene-1,1-diamine (FOX-7) is interesting not only as an explosive, but also as a molecule with multiple redox centers, where strong electron donors (amino groups) and acceptors (nitro groups) are close to each other. The present fundamental electrochemical study revealed that in aqueous solutions the reduction pathway during the exhaustive electrolysis does not follow the expected pattern but after the first electron transfer a chain of spontaneous intramolecular (eventually intermolecular) redox processes takes place leading not to reduction products, but to a total degradation of the title compound. Since evolution of gaseous products has been detected during the electrolysis, the electrochemically initiated decomposition of the FOX-7 seems to be analogous to the explosion process slowed down by the very low concentration and cooled by the solution.
Inhibition Efficiency of Alkaline Metal Salts on Carbon Steel Corrosion in Acidic Media
Authors: Asefi Dourna , Arami Mokhtar , Mahmoodi Niyaz Mohammad
Published: October 2011

Corrosion inhibitors are widely used in acid solutions during pickling and descaling. In this study, the inhibition performance of different alkaline metal salts in the concentration range 0-0.1 M has been found out. The corrosion behavior of low carbon steel in 1 M HCl in the presence of different metal cations and different anions is studied using weight loss and OCP (Open Circuit Potential) methods at 20 åC. It is found that the addition of these salts inhibits the corrosion markedly. The inhibition effect is in the following order Na2SO4 >NaI > LiCl > NaCl > KCl > NaNO3 > NaBr.
Realization of a Multilayered Nano-Crystalline Silicon Structure by a Novel Low Temperature Process Suitable for Silicon-Based Light Emitting Diodes
Authors: Darbari Sara , Mohajerzadeh Shamsoddin , Robertson Michael
Published: October 2011

A plasma enhanced chemical vapor deposition (PECVD) of amorphous-Si followed by in-situ crystallization has been applied to realize nano-scale crystal grains embedded in amorphous medium. Removal of extra amorphous Si layer is achieved using a sequential reactive ion etching process while the nano-crystalline grains are preserved. The process is carried out all at temperatures below 350o C which is fully compatible with soda-lime glass substrates. Photoluminescence analysis indicates the light-emitting behavior of the processed layer at a wavelength around 550 nm. A correspondence between the photoluminescence peak position and silicon grain size is observed using SEM. Multilayered structures have been employed to realize light emitting diodes on glass substrates. The electroluminescence spectrum of the device has been investigated.
Residual Stress Properties of Nickel and Copper Deposits Used for C4 Interconnects
Authors: Arvin Charles L. , Scott George , Goldsmith Charles , Parks Christopher , Wang Chen , Zhang Yun , Abys Joe , Takahashi Ken
Published: October 2011

Semiconductor packaging technology requires understanding how the fundamental materials properties of different structures interact to impact the final reliability of the system, how to measure those properties and how to control them. We investigated the impact of residual stress of electrodeposited Ni (sulfamate) and Cu (sulfate and MSA) deposits that are used for C4 (controlled collapse chip connection) interconnects using X-ray lattice distortion method, sin2ψ and wafer bow measurement as a function of thermal excursions up to 400 C. The impact of this stress on the final reliability of a flip chip package was studied in order to determine useful guidelines to limit post-plate process temperatures, to conduct anneals when possible, to establish best known methods to monitor plated materials stresses and to develop methods to maintain and condition chemical plating baths to control those deposits. Finally, dynamic SIMS was utilized to aid in the interpretation of those data.
Electrochemical Formation of the Redox-Active Metal-Containing Polymers for Catalytic and Electrocatalytic Applications
Authors: Magdesieva Tatiana V. , Nikitin Oleg M. , Polyakova Olga V. , Yakimansky Alexander V. , Goikhman Mikhail Y. , Podeshvo Irina V.
Published: October 2011

A convenient electrochemical approach to new redox-active Cu, Pd, Ni -containing polymers of polyamic type with biquinoline (biQ) fragments was elaborated. The comparative analysis of the data obtained revealed the main factors which influence the type of metal coordination unit formed in the polymer: the nature of metal, the number of biQ fragments and conformational rigidity of the polymer backbone as well as the electrolysis conditions. Voltammetric investigation of metal-polymers allows distinguishing the types and relative amounts of metal-coordination units formed. The comparison of the electrochemical data with the results of catalytic tests revealed the guidelines for electrochemical synthesis of efficient catalytic systems.
Structure, Morphology and Reactivity of Conducting Polymer-Linked Polyoxometallate-Modified Gold Nanoparticles
Authors: Zoladek Sylwia , Rutkowska Iwona A , Zurowski Artur , Skorupska Katarzyna , Kulesza Pawel J. , Jouini Mohamed , Perruchot Christian , Cox James A.
Published: October 2011

In the present work, Keggin-type polyoxometallates are utilized as both reducing and protecting agents during fabrication of gold nanoparticles ranging from 5 to 100 nm covered (protected) with monolayer-type films of polyoxometallates (phosphododecamolybdates). Immobilization of phosphomolybdate-modified gold nanoparticles into ultrathin layers of conducting polymer films of poly(3,4- ethylenedioxythiophene), PEDOT and polyaniline, PANI is also described. We pursue here the concept based on multiple formation of two-dimensional arrays and three-dimensional networks composed alternately of conducting polymers linking negatively charged monolayer-type films of phosphomolybdate-protected gold nanostructures performed using a layer-by-layer technique. The morphology of the resulting multilayer network films was determined using transmission electron microscopy (TEM) and their formation and electrochemical properties were examined using cycling voltammetry. Resulting monolayer and multilayer assembles composed of phosphomolybdate-stabilized gold nanoparticles have occurred to be attractive towards electrocatalytic reduction of hydrogen peroxide.
Low-Temperature Grown High-Quality Piezoelectric AlN Film for Sensor Applications
Authors: Sah R. Ekwal , Bludau O. , Röhlig C.-C. , Kirste Lutz , Cimalla V. , Lebedev V.
Published: October 2011

Aluminum nitride thin films grown at low temperature (< 200°C) on Si(001) using radio frequency (RF) sputter deposition technique have been characterized by measuring infrared (IR) spectra, breakdown voltage, and crystallographic orientation. The full-width-at-half-maximum of the E1(TO) mode in the IR measurement has been found to decrease for higher RF power. The breakdown electric field strength under dc voltage is around 5 MV/cm. The X-ray diffraction measurements indicated negligible change in the tilt of the film crystallites following annealing for 1 h in vacuum at 1000°C. Cantilevers that can be used both as pressure/force or inertial sensors and actuators have been fabricated from our low-temperature grown, thermally stable films.
Low Stress In Situ Boron Doped Poly SiGe Layers for MEMS Modular Integration with CMOS
Authors: Kazmi Syed Naveed Riaz , Aarnink Tom , Kovalgin Alexey Y. , Salm Cora , Schmitz Jurriaan
Published: October 2011

In-situ boron doped LPCVD polycrystalline silicon-germanium (poly Si30Ge70) layers are deposited from silane (SiH4) and germane (GeH4) with fixed GeH4 to SiH4 partial pressure ratio at 430 oC and 0.2 mbar. The layers exhibit resistivities less than 1 mΩ-cm with a uniform boron distribution over the film thickness. The effect of the diborane (B2H6) partial pressure on the properties of the SiGe alloy is investigated. The layers deposited at low partial pressures of B2H6 exhibit very low stress with a trend from tensile to compressive with increasing B2H6 partial pressure, accompanied by a phase transition from polycrystalline to amorphous, allowing to tune for minimal stress.
Hybrid Backside Illuminated CMOS Imager for High-End Applications
Authors: De Vos Joeri , De Munck Koen , Erismis Mehmet Akif , Minoglou Kiki , Rao Padmakumar Ramachandra , Zhang Wenqi , Sabuncuoglu Tezcan Deniz , De Moor Piet , Soussan Philippe
Published: October 2011

In this paper we present a successful integration scheme of a backside illuminated 1024x1024 pixel, 30µm thin, sensor array that is flip chipped on a ROIC die with 10µm diameter Indium micro bumps, where the pixel pitch is 22.5µm. Special attention is given to critical steps leading towards high broadband quantum efficiency It is shown that through introduction of a high aspect ratio pixel separating trenches, inter pixel electrical crosstalk can be avoided. In the end, to increase bump yield, an alternative micro bump formation by means of CuSn bumps is presented.
How to Make Optimized Arrays of Si Wires Suitable as Superior Anode for Li-Ion Batteries
Authors: Quiroga González Enrique , Ossei-Wusu Emmanuel , Carstensen Jürgen , Föll Helmut
Published: October 2011

The fabrication process to produce Si wires with superior structural properties for application in Li-ion batteries is described. The process is based on the electrochemical etching of pores in Si, followed by a chemical over-etching step. The wires obtained have a quadratic cross section of around 1.5 x 1.5 micron and are organized in an array stabilized by two in-situ-created supports. An electrodeposited Cu film on the array is used as current collector. The method described is a production-near process with a potential for low costs and high yield.
Substoichiometric TiO2 Thin Films as a Support Catalyst for Hydrogen Fuel Cells
Authors: Hansen Robin P. , Phillips Richard , Eisenbraun Eric
Published: October 2011

Substoichiometric titanium oxide films as thin as 25nm were grown using atomic layer deposition (ALD) and determined by x-ray diffraction (XRD) to consist of Magneli phase Ti4O7. These films were synthesized at temperatures as low as 125°C, significantly lower than traditional methods. The films possess high electrical conductivity, making them attractive as potential fuel cells support materials. Titanium oxide nanotubes 70 nm in diameter and 2-3 um long were formed when the deposition was performed over sacrificial porous aluminum substrates.
Prevention of Solid Electrolyte Interphase Damaging on Silicon by Using Polymer Derived SiCN Ceramics
Authors: Reinold L. Mirko , Graczyk-Zajac Magdalena , Fasel Claudia , Riedel Ralf
Published: October 2011

A new composite anode material for lithium ion batteries, based on nano-silicon particles dispersed in a polymer-derived ceramic (PDC) matrix, was produced, characterized and electrochemically analyzed via cyclic voltammetry (CV). For this purpose a commercial preceramic polymer , namely the polysilazane HTT 1800, was mixed with silicon nano powder and pyrolyzed at 900, 1100, 1300 and 1500 °C. It was found that in comparison with pure silicon, the composite presented an enhanced electrochemical stability during lithium insertion/extraction. Moreover, dispersing the silicon into the ceramic matrix avoids a continuous energy loss related to the formation of a solid electrolyte interphase (SEI). By means of cyclic voltammetry measurements we found that for the composites synthesized at temperatures exceeding 1000 °C, no more losses were observable during subsequent insertion/extraction once the stable SEI was formed.
Diffusion of Li+ Ions in LiNi1/3Mn1/3Co1/3O2
Authors: Zhang Xiaoyu , Mauger Alain , Jiang Weijun , Groult Henri , Julien Christian M.
Published: October 2011

Electrochemical properties of LiNi1/3Mn1/3Co1/3O2 powders have been investigated for a sample free on any impurity and cation mixing reduced to 1.3%. The discharge capacity decreases from 174 mAh/g (0.01C) to 133 mAh/g when cycled at a high current density of 3C-rate. The sample reaches high capacity of 146 mAh/g after 90 cycles when using 1C-rate for discharging, with high capacity retention of 97%. The diffusion coefficient of the Li+ ions has been determined as a function of the delithiation rate by GIT and EIS analysis. The diffusion coefficient is in the range 1011-1012 cm2/s, and goes through a maximum at intermediate delithiation rate.
LiNi0.33+δMn0.33+δCo0.33-2δO2 (0.025 ≤ δ ≤ 0.075) Cathode Materials for Li-Ion Batteries: Electrochemical Features
Authors: Ben-Kamel Karim , Amdouni Nouredine , Trottier Julie , Zaghib Karim , Mauger Alain , Groult Henri , Julien Christian M.
Published: October 2011

Electrochemical features of LiNi0.33+δMn0.33+δCo0.33-2δO2 (0≤δ≤0.075) oxides (LNMCOs) have been studied as a function of the composition. The cation mixing was characterized by a set of methods including Rietveld refinement of XRD patterns and magnetic experiments. It is observed that the decreasing amount of cobalt favouring the presence of Ni2+ ions in the Li(3b) site affects the electrochemical performance of lithium cells.
Electrochemical Supercapacitors Based on Graphene-Conducting Polythiophenes Nanocomposite
Authors: Alvi Farah , Ram Manoj Kumar , Basnayaka Punya , Stefanakos Elias , Goswami Yogi , Hoff Andrew , Kumar Ashok
Published: October 2011

Supercapacitors represent an attractive alternative for portable electronics and automotive applications due to their high specific power, and extended lifetime. The poly (3, 4-ethylenedioxythiophene) (PEDOT) and polythiophene (PTh) have attracted much attention because of their excellent environmental stability, optical, electrical and electrochemical properties. We present here the synthesis, characterization and application of graphene (G)-PEDOT and G-PTh nanocomposites as electrode material for supercapacitor applications. These nanocomposites were synthesized using chemical oxidative polymerization technique, and characterized using Scanning Electron Microscopy (SEM), X-ray-diffraction, Electrochemical Impedance Spectroscopy (EIS), and Cyclic Voltammetry (CV) techniques. The electrochemical charge/discharge characteristics of G-PEDOT and G-PTh nanocomposites were investigated in 2M HCl electrolytic medium, and the specific discharge capacitance values were estimated to be varying from 160 to 400 Farad (F)/gram. This study has revealed that the G-PEDOT and G-PTh nanocomposite electrode materials may lead to a stable supercapacitor for portable electronic applications.
Thermal Characterization of LiFePO4 Cathode in Lithium Ion Cells
Authors: Ben Mayza Aadil , Ramanathan Mayandi , Radhakrishnan Rajeswaran , Ha Seonbaek , Ramani Vijay , Prakash Jai , Zaghib Karim
Published: October 2011

The thermal behavior of carbon-coated LiFePO4 cathode material was investigated using three different calorimetric techniques. Heat released during charge and discharge of cylindrical 18650 size cells was measured in an isothermal calorimeter. Accelerating rate calorimetry was used to investigate the cause of thermal runaway of the cylindrical 18650 size cells. On the other hand, differential scanning calorimeter was used to study the contribution of the delithiated carbon-coated LiFePO4 and the lithiated graphite to the overall thermal runaway through coin cells of 2032 size. The carbon-coated LiFePO4 showed very good thermal stability.
Supported Nanostructured Ir and IrRu Electrocatalysts for Oxygen Evolution in PEM Electrolysers
Authors: Thomassen Magnus S. , Mokkelbost Tommy , Sheridan Edel , Lind Anna
Published: October 2011

With a modified polyol method, Ir and IrRu was deposited on Sb-doped SnO2 nanoparticles functioning as a support material for the anode catalysts for poylmer electrolyte water electrolysers. Nanostructured iridium particles (2-3 nm) were deposited onto the ATO particles, characterized with XRD, TEM and XPS. The Ir/ATO particles showed a higher surface area and catalytic activity for the oxygen evolution than unsupported Ir black. A PEM water electrolyser single cell with 4 mg 20 wt% Ir/ATO cm-2 achieved 1.65 V at 1 A cm-2 at 80 °C. After operation at 1 A cm-2 for 100h, an increase of the iR-corrected cell voltage with 50 mV was observed.
Electrochemical Reduction of Sulfur Hexafluoride in Novel, Air-Independent Power Systems
Authors: Burke Alan , Carreiro Louis
Published: October 2011

Sulfur hexafluoride (SF6) is an alternative oxidant that can be liquefied and stored at relatively low pressure, making its storage lower maintenance than that for pure oxygen. Using SF¬6 as the oxidant in undersea (air-independent) fuel cell systems can offer greater safety, comparable oxidant storage capacity and improved thermal management of the system. This study investigated the electrochemical reduction of SF6 in order to evaluate its potential for electrochemical systems.
Multiwall CVD Carbon Nanotubes as Insulated Nanowires
Authors: Belli Stuart L. , Oh Scott P. , Kaur Saranjit , Pearce Matthew A. , Smart Christopher J.
Published: October 2011

Carbon nanotubes grown from acetylene gas by chemical vapor deposition onto conducting substrates have been investigated as working electrodes for voltammetric studies. Both the bare carbon nanotubes as well as nanotubes decorated with electrochemically-deposited gold were investigated. The electrodes exhibit high specific capacitance and good electrode behavior for interfacial electron transfer. The nanotubes appear to have electrochemical properties that depend on the surface morphology; interfacial electron transfer occurs preferentially at the tube ends or edges, while double-layer capacitance reflects the higher surface area of the tube sidewalls. The nanotubes act as insulated wires. Cyclic voltammetry of the hexacyanoferrate (III/II) couple was used to estimate the relative electrochemical surface areas of the two regions.
Single Wall Carbon Nanotubes as Transparent Cathode Electrodes for OLED Applications
Authors: Chien Yu-Mo , Shih Ishiang , Izquierdo Ricardo
Published: October 2011

Preliminary work has been conducted in order to investigate the possibility of using transparent electrodes made of single wall carbon nanotubes as cathodes in OLED applications. From the results, efficient electron injection from SWCNTs was achieved by modifying the surface of SWCNTs with a thin layer of Pd/Al/LiF while maintaining transparency. However, such devices did not emit light and had unusually low turn on voltage.
Pt Based Nanocomposites for Direct Glucose Determination Sensitive Nonenzymatic Amperometric Glucose Detection by Carbon Supported PtAu Based Bimetallic Nanomaterials
Authors: Singh Baljit , Dempsey Eithne
Published: October 2011

Carbon supported PtAu based bimetallic nanomaterials were synthesized, heat treated (450 0C, 2 hrs) and characterised using scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), thermo-gravimetric analysis (TGA) and X-ray diffraction (XRD). Cyclic voltammetry was employed in order to confirm the typical metallic electrochemical response of the materials and hydrodynamic amperometry was employed for direct glucose determination. The optimised nanocomposite material (Pt1Au3/C) exhibited excellent sensitive response (27.0 μA mM-1cm-2, LoD 2.9 µM) towards glucose electro-oxidation, over the range 0-10 mM at Eapp = 0.35 V vs Ag/AgCl under neutral conditions (pH 7.4). Overall, the materials demonstrated sensitive and reproducible responses, while eliminating the pH, temperature and lifetime issues associated with enzyme based electrodes and are of great promise in the quantification of glucose in real analysis.
Photostability of N@C60 in Common Solvents
Authors: Farrington Benjamin J. , Hingston Timothy J. , Briggs George A. , Sambrook Mark R. , Porfyrakis Kyriakos
Published: October 2011

Using CW-ESR spectroscopy, the photo induced decomposition of N@C60 in five solvents under irradiation with 254 nm and 365 nm ultra violet light was measured. The results indicate that the decomposition rate of N@C60 is highly dependent on the solvent chosen. The finding shows that carbon disulphide and cis/trans-decalin are the most suitable solvents for future photoexitation experiments of N@C60. In addition a comparison between decay rate of N@C60 in ambient and degassed solvents suggests that decomposition is not principally via an interaction of the 3C60 excited state and the nitrogen atom.
Study of the Kinetics of Vanadium Redox Reaction by Rotating Disk Electrode
Authors: Wu Chun-Hsing , Liao Hsin-Yi , Hsueh Kan-Lin , Hung Ju-Shei
Published: October 2011

This work studied the kinetics of electrochemical reaction of vanadyl ion (VO+2) oxidation (from VO+2 to VO2+) and reduction (from VO+2 to V+3) in aqueous solution containing different vanadium concentrations and pH values. The rotating disk electrode was used to study the reaction kinetics. The potential of water electrolysis reaction could be shifted by changing the solution of pH. Nineteen different solutions were tested in our study. The rate constants of VO+2 oxidation and reduction reaction were calculated, as well as the diffusion coefficient of VO+2 in different electrolyte. We found that the oxidation reaction was much faster than the reduction reaction. The diffusion coefficient of VO+2 varied as the electrolyte pH changed.
Synthesis of New Fluorosulphate Materials Using Different Approaches
Authors: Ati Mohamed , Sougrati Moulay Tahar , Recham Nadir , Barpanda Prabeer , Reynaud Marine , Delacourt Charles , Armand Michel , Jumas Jean Claude , Tarascon Jean-Marie
Published: October 2011

Searching for possible new cathode materials with the ability to outperform LiFePO4, our group has recently discovered LiFeSO4F, a novel metal fluorosulphate compound. Needing no further optimization, it delivers excellent reversible capacity (~140 mAh/g) involving a 3.6 V FeII/III redox plateau. This parent fluorosulphate phase has been synthesized by three different routes, namely ionothermal synthesis, solid-state synthesis and polyol-assisted synthesis. These low temperature processing routes are described focusing on synthesis of LiFeSO4F. Furthermore, these methods were successfully employed to unravel other LiMSO4F compounds (M = Co/Ni/Mn/Zn) as well as sodium-based metal fluorosulphate NaMSO4F compounds (M = Fe/Co/Ni/Mn). These syntheses were realized at temperature not exceeding 300°C. We have discovered many interesting and at times intriguing structural, electrochemical and transport properties in these fluorosulphate materials. A few of these findings are illustrated to show the richness of the metal fluorosulphate chemistry.
Structural Characterization of ORR Active Surface Niobium Oxides on Partially Oxidized Nb Carbonitrides
Authors: Matsumoto Masashi , Miyazaki Takashi , Fujieda Shinji , Ohgi Yoshiro , Ishihara Akimitsu , Ota Ken-ichiro , Imai Hideto
Published: October 2011

In order to identify the active sites for the oxygen reduction reaction (ORR) in a partially oxidized Niobium carbo-nitride (Nb-CNO) catalyst, we investigated the structure of Nb-CNO catalysts by using conversion-electron-yield x-ray absorption spectroscopy (CEY-XAS). CEY-XAS measurements made it possible to selectively analyze the surface oxide phases in Nb-CNO catalysts with Nb2O5/NbCN core-shell structures. The result showed the decrease of the coordination numbers for Nb-O surface oxide phases in ORR active Nb-CNO particles, indicating that oxygen vacancies were introduced in the surface oxide phase. Thus, oxygen vacancies could work as the active sites for ORR in Nb-CNO, similar to Ta-CNO ORR catalysts.
Fabrication of Titanium Nitride and Molybdenum Nitride for Supercapacitor Electrode Application
Authors: Ting Yen-Jui (Bernie) , Lian Keryn , Kherani Nazir
Published: October 2011

Molybdenum nitride was developed through thermal nitridation of electrodeposited molybdenum oxide and was evaluated as electrode materials for electrochemical capacitors. Nitrided molybdenum electrode showed significantly enhanced capacitance and improved chemical stability comparing to the as-deposited molybdenum oxide electrode. The added capacitance was attributed from the reversible pseudocapacitance of molybdenum nitride. The study demonstrated an economical alternative process to produce molybdenum nitride electrodes with area specific capacitance comparable to those deposited by CVD.
Molecular Imprinting: Does It Play a Role in the Reduction of Oxidized Redox Shuttle Molecules
Authors: Patterson Mary L.
Published: October 2011

Molecular imprinting is proposed as a mechanism to explain the reduction of oxidized redox shuttle species at a carbonaceous anode in a lithium ion cell. Electrochemical and lithium ion cell experiments were run to evaluate this hypothesis. The apparent diffusion coefficient of ferrocene was determined at a pristine glassy carbon electrode without an SEI layer and with an SEI layer formed in the absence or presence of ferrocene. Lithium iron phosphate - graphite cells were formed in the presence or absence of a redox shuttle molecule and the voltage of the cell during overcharge was measured, along with the discharge capacity. The data supports the hypothesis that molecular imprinting does play a role in the reduction of oxidized redox shuttle molecules. The molecular imprinting of the solid electrolyte interphase (SEI) layer with template electrolyte species present during SEI formation provides functional porosity at a molecular level.
Advanced CuCl Electrolyzer for Hydrogen Production via the Cu-Cl Thermochemical Cycle
Authors: Kim Soohyun , Schatz Rich , Khurana Sanchit , Fedkin Mark , Wang Chunmei , Lvov Serguei
Published: October 2011

The Cu-Cl thermochemical cycle is among the most attractive technologies for hydrogen production due to its high efficiency and moderate temperature requirements. In this study, the H2 producing reaction of the cycle, CuCl(aq) electrolysis, was investigated in a recently developed electrolyzer using a new type of double layer Nafion 117 membrane. Enhanced MEA durability allowed the system to operate at 80 oC for an extended period of time with continuous anolyte cycling and regeneration. An applied potential of 0.7 V was needed to produce the current density of about 0.12 A/cm2, and the system maintained performance over a period of 100 hours with no substantial decline of hydrogen production rates. Linear polarization and electrochemical impedance spectroscopy were used to monitor the electrolyzer performance over time. Further research is underway to optimize the process parameters and MEA fabrication to extend the electrolyzer life time and current density
Solid Alkaline Fuel Cell Composed of Layered Perovskite-Type Oxide LaSr3Fe3O10
Authors: Takahashi Hiroki , Watanabe Hiroshi , Takeguchi Tatsuya , Yamanaka Toshiro , Ueda Wataru
Published: October 2011

In the present study, solid alkaline fuel cell composed of layered perovskite-type oxide LaSr3Fe3O10 was studied. LaSr3Fe3O10 showed OH- conduction and activity for oxygen reduction reaction. We prepared LaSr3Fe3O10 with various bulk density by sintering at 900, 1100, 1200, 1400, and 1600ºC. When the bulk density increased from 4.03 (sintered at 900ºC) to 4.16 g cm-3 (sintered at 1100ºC), the output power and open circuit voltage increased greatly. However, when the bulk was higher than 4.16 g cm-3, output power decreased with an increase in bulk density.
Nonlinear Dynamics of Vertical-Cavity Surface-Emitting Lasers
Authors: Panajotov Krassimir , Sciamanna Marc , Gatare Ignace , Arteaga Mikel , Thienpont Hugo
Published: October 2011

Nonlinear dynamics of Vertical-Cavity Surface-Emitting Lasers (VCSELs) induced by optical injection, optical feedback, current modulation and mutual coupling is reviewed. Due to the surface emission and cylindrical symmetry VCSELs lack strong polarization anisotropy and may undergo polarization switching. Furthermore, VCSELs may emit light in multiple transverse modes. These VCSEL properties provide new features to the rich nonlinear dynamics induced by an external perturbation. We demonstrate for the case of orthogonal optical injection that new Hopf bifurcation on a two-polarization-mode solution delimits the injection locking region and that polarization switching and injection locking of first-order transverse mode lead to a new resonance tongue for large positive detunings. Similarly, the underlying polarization mode competition leads to chaotic-like behavior in case of gain switching and the presence of two transverse modes additionally reduces the possibility of regular dynamics. The bistable property of VCSEL makes it possible to investigate very fundamental problems of bistable systems with time-delay, such as the coherence resonance phenomenon. We also demonstrate that the synchronization quality between unidirectionally coupled VCSELs can be significantly enhanced when the feedback-induced chaos in the master laser involves both orthogonal LP fundamental transverse modes.
Comparison of the Calculated Collision-Induced Absorption Spectra by Dense Hydrogen-Helium, Deuterium-Helium, and Tritium-Helium Gas Mixtures
Authors: Abel Martin , Frommhold Lothar , Li Xiaoping , Hunt K. L. C.
Published: October 2011

We have recently determined the induced dipole surface (IDS) and potential energy surface (PES) of collisional H2-He complexes. We have used these surfaces to compute the binary collision-induced absorption spectra of H2 molecules interacting with He atoms and of D2 molecules interacting with He atoms. Here we extend these calculations to the case of T2 molecules interacting with He atoms. Whereas the electronic structure of X2-He is virtually the same for all hydrogen isotopes X = H, D, or T, the collisional dynamics and molecular scattering wave functions are different for the different collisional pairs. We have calculated spectra up to a temperature of 9000 K and frequencies up to 20,000 cm−1. Here we compare the calculated collision-induced absorption spectra for the different hydrogen isotopes. While we have observed reasonable agreement between our calculations and laboratory measurements for the collisional H2-He and D2-He complexes, there are no laboratory measurements for T2-He collisional complexes, and one must rely on the fundamental theory, supported by the agreement between theory and experiment for the other isotopes.
A Mobile-Beacon-Assisted Sensor Network Localization Based on RSS and Connectivity Observations
Authors: Teng Guodong , Zheng Kougen , Yu Ge
Published: October 2011

Determining the physical positions of sensors has been a fundamental and crucial problem in wireless sensor networks (WSNs). Due to the inherent characteristics of WSNs, extremely limited resources available at each low-cost and tiny sensor node, connectivity-based range-free solutions could be a better choice to feature a low overall system cost. However, localization by means of mere connectivity may underutilize the proximity information available from neighborhood sensing. Although received signal strength (RSS) values are irregular and highly dynamic, it might provide heuristic information about which neighboring nodes are closer and which are further. We propose a distributed Mobile-beacon-assisted localization scheme based on RSS and Connectivity observations (MRC) with a specific trajectory in static WSNs. To ensure that MRC performs as true to reality as possible, we propose two improved approaches based on MRC to consider irregular radio scenario in the noisy environment. Comparing the performance with three typical range-free localization methods in static WSNs, our lightweight MRC algorithm with limited computation and storage overhead is more suitable for very low-computing power sensor nodes that can efficiently outperform better with only basic arithmetic operations in the simulation and physical environments.
Prognostic Parameters for the Primary Care of Melanoma Patients: What Is Really Risky in Melanoma?
Authors: Göppner Daniela , Leverkus Martin
Published: October 2011

Due to intensified research in recent years, the understanding of the molecular mechanisms involved in the development of melanoma has dramatically improved. The discovery of specific, causal mutations such as BRAF or KIT oncogenes not only renders a targeted and thus more effective therapeutic approach possible, but also gives rise to a new genetic-based classification. Targeting just a few out of several potential mutations, BRAF-Inhibitors such as PLX 4032 achieved already tremendous results in the therapy of metastatic melanoma. Up to now, the correlation of clinical, histomorphologic, and genetic features is, however, not understood. Even more, is it not well known precisely what kind of molecular changes predispose the primary melanoma for metastasis. The identification of morphological surrogates and prognostic parameters in tumors with such genetic alteration seems therefore crucial when differentiating and classifying this heterogeneous tumor entity in more detail and thus facilitates the stratification of prognosis as well as therapy. This review summarizes the current understanding of carcinogenesis and gives a detailed overview of known morphologic and potentially future genetic prognostic parameters in malignant melanoma.
Epidemiology, Diagnosis, and Management of Cystic Lesions of the Pancreas
Authors: de Jong Koen , Bruno Marco J. , Fockens Paul
Published: October 2011

Although little is known on the true prevalence of pancreatic cysts, physicians are currently more frequently confronted with pancreatic cysts because of the increasing use of sophisticated cross-sectional abdominal imaging. Cystic lesions of the pancreas comprise of a heterogeneous group of diagnostic entities, some of which are benign such as inflammatory pseudocysts or serous cystadenomas and do not require resection when asymptomatic. Others like mucinous cysts or intraductal papillary mucinous neoplasms (IPMN) have a malignant potential and in these cases surgical resection is often indicated. For this reason an adequate distinction between the various cysts is crucial to optimize management strategy. Different diagnostic methods that could be of value in the differentiation include radiologic imaging techniques such as CT, MR, and endosonography. In addition, fluid aspiration for cytopathology, tumormarkers or molecular analysis is widely used. Different guidelines are available but so far no optimal diagnostic algorithm exists. We summarize the epidemiology, classification, clinical presentation, diagnostics, management, and future perspectives.
Reforming Characteristics under Visible Light Response of Cr- or Ag-Doped Prepared by Sol-Gel and Dip-Coating Process
Authors: Nishimura Akira , Mitsui Go , Nakamura Katsuya , Hirota Masafumi , Hu Eric
Published: October 2011

A Cr- or Ag-doped TiO2film was prepared by sol-gel and dip-coating process and used as the photocatalyst for CO2reforming under the visible light. The ratio of amount of Cr or Ag added to amount of Ti in TiO2sol solution (R) varied from 0 to 100 wt% or 0 to 50 wt%, respectively. The total layer number of Cr- or Ag-doped TiO2film (N) coated was changed. The CO2reforming performance with the Cr- or Ag-doped TiO2film was tested under a Xe lamp with or without ultraviolet (UV) light. As a result, whenNequals to 1, the concentration of CO which was a product from CO2reforming was maximized in Cr doping case forR= 70 wt% and in Ag doping case forR= 1 wt%, respectively. The best result of concentration of CO = 8306 ppmV, concentration of CH4= 1367 ppmV, concentration of C2H6= 1712 ppmV is obtained when with Cr doping in this study.
Peptide-Conjugated PAMAM Dendrimer as a Universal DNA Vaccine Platform to Target Antigen-Presenting Cells
Authors: Daftarian Pirouz , Kaifer Angel E. , Li Wei , Blomberg Bonnie B. , Frasca Daniela , Roth Felix , Chowdhury Raquibul , Berg Eric A. , Fishman Jordan B. , Al Sayegh Husain A. , Blackwelder Pat , Inverardi Luca , Perez Victor L. , Lemmon Vance , Serafini Paolo
Published: October 2011

DNA-based vaccines hold promise to outperform conventional antigen-based vaccines by virtue of many unique features. However, DNA vaccines have thus far fallen short of expectations, due in part to poor targeting of professional antigen-presenting cells (APC) and low immunogenicity. In this study, we describe a new platform for effective and selective delivery of DNA to APCs in vivo that offers intrinsic immune-enhancing characteristics. This platform is based on conjugation of fifth generation polyamidoamine (G5-PAMAM) dendrimers, a DNA-loading surface, with MHC class II–targeting peptides that can selectively deliver these dendrimers to APCs under conditions that enhance their immune stimulatory potency. DNA conjugated with this platform efficiently transfected murine and human APCs in vitro. Subcutaneous administration of DNA-peptide-dendrimer complexes in vivo preferentially transfected dendritic cells (DC) in the draining lymph nodes, promoted generation of high affinity T cells, and elicited rejection of established tumors. Taken together, our findings show how PAMAM dendrimer complexes can be used for high transfection efficiency and effective targeting of APCs in vivo, conferring properties essential to generate effective DNA vaccines. Cancer Res; 71(24); 7452–62. ©2011 AACR.