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Hydrogen Evolution (hydrogen + evolution)

Distribution by Scientific Domains
Chemistry80%

Selected Abstracts

Polylysine-Catalyzed Hydrogen Evolution at Mercury Electrodes

ELECTROANALYSIS, Issue 17-18 2010
Marko, ivanovi
Abstract It has been shown that peptides and proteins produce at nanomolar concentrations a structure-sensitive chronopotentiometric peak H at mercury electrodes, which is due to the catalytic hydrogen evolution reaction (HER). Herein, we use for the first time poly(amino acids) to obtain information about the role of individual amino acid residues in the HER. At pH,6 polylysine (polyLys) and polyarginine,tryptophan yield a peak H, in agreement with their ionization state, while polyglutamic acid gives no catalytic response. PolyLys catalyzes hydrogen evolution in its adsorbed state. Even at potentials negative to the potential of zero charge, hydrophobic interactions could be involved in polyLys adsorption. [source]

Hydrogen Evolution from Peroxides , a Concerted Reaction

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2004
Werner R. Thiel
Abstract DFT calculations provide strong evidence that the evolution of hydrogen from mixtures of aldehydes and hydrogen peroxide proceeds by a concerted mechanism. The electronic influence of a series of substituents is correlated with the enthalpies of activation and reaction, and the calculated isotope effect of the reaction is compared with experimentally obtained data. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

ChemInform Abstract: A Dawson-Type Dirhenium(V)-Oxido-Bridged Polyoxotungstate: X-Ray Crystal Structure and Hydrogen Evolution from Water Vapor under Visible Light Irradiation.

CHEMINFORM, Issue 43 2008
Chika Nozaki Kato
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Biomimetic Hydrogen Evolution: MoS2 Nanoparticles as Catalyst for Hydrogen Evolution

CHEMINFORM, Issue 25 2005
Berit Hinnemann
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Polylysine-Catalyzed Hydrogen Evolution at Mercury Electrodes

ELECTROANALYSIS, Issue 17-18 2010
Marko, ivanovi
Abstract It has been shown that peptides and proteins produce at nanomolar concentrations a structure-sensitive chronopotentiometric peak H at mercury electrodes, which is due to the catalytic hydrogen evolution reaction (HER). Herein, we use for the first time poly(amino acids) to obtain information about the role of individual amino acid residues in the HER. At pH,6 polylysine (polyLys) and polyarginine,tryptophan yield a peak H, in agreement with their ionization state, while polyglutamic acid gives no catalytic response. PolyLys catalyzes hydrogen evolution in its adsorbed state. Even at potentials negative to the potential of zero charge, hydrophobic interactions could be involved in polyLys adsorption. [source]

Stripping Analysis at Bismuth Electrodes: A Review

ELECTROANALYSIS, Issue 15-16 2005
Joseph Wang
Abstract For many years mercury electrodes were the transducer of choice in stripping voltammetry of trace metals owing to their high sensitivity, reproducibility, and renewability. However, because of the toxicity of mercury, alternative (,environmentally friendly') electrode materials are highly desired for both centralized and field applications. Recently introduced bismuth electrodes offer a very attractive alternative to commonly used mercury electrodes. Such electrodes display well-defined, undistorted and highly reproducible response, favorable resolution of neighboring peaks, high hydrogen evolution, with good signal-to-background characteristics comparable to those of common mercury electrodes. The attractive stripping behavior of bismuth electrodes reflects the ability of bismuth to form ,fused' multicomponent alloys with heavy metals. Bismuth stripping electrodes thus hold great promise for decentralized metal testing, with applications ranging from continuous remote sensing to single-use measurements. Fundamental studies aimed at understanding the behavior of bismuth film electrodes should lead to rational preparation and operation of reliable alternative (,non,mercury') stripping electrodes that would have a major impact upon electroanalysis of trace metals. This article reviews the development, behavior, scope and prospects of bismuth electrodes for stripping-based electrochemical measurements of trace metals. [source]

Sensitive Electrochemical Detection of Native and Aggregated ,-Synuclein Protein Involved in Parkinson's Disease

ELECTROANALYSIS, Issue 13-14 2004
Michal Masa
Abstract The aggregation of ,-synuclein, a 14,kDa protein, is involved in several human neurodegenerative disorders, including Parkinson's disease. We studied native and in vitro aggregated ,-synuclein by circular dichroism (CD), atomic force microscopy (AFM) and electrochemical methods. We used constant current chronopotentiometric stripping analysis (CPSA) to measure hydrogen evolution catalyzed by ,-synuclein (peak H) at hanging mercury drop electrodes (HMDE) and square-wave stripping voltammetry (SWSV) to monitor tyrosine oxidation at carbon paste electrodes (CPE). To decrease the volume of the analyte, most of the electrochemical measurements were performed by adsorptive transfer (medium exchange) from 3,6,,L drops of ,-synuclein samples. With both CPE and HMDE we observed changes in electrochemical responses of ,-synuclein corresponding to protein fibrillization detectable by CD, fluorescence and AFM. Aggregation-induced changes in peak H at HMDE were relatively large in strongly aggregated samples, suggesting that this electrochemical signal may find use in the analysis of early stages of ,-synuclein aggregation. This assumption was documented by marked changes in the peak H potential and height in samples withdrawn at the end of the lag and the beginning of the elongation phase. Native ,-synuclein can be detected down to subnanomolar concentrations by CPSA. [source]

Influence of Heat Treatments on In Vitro Degradation Behavior of Mg-6Zn Alloy Studied by Electrochemical Measurements,

ADVANCED ENGINEERING MATERIALS, Issue 5 2010
Shaoxiang Zhang
The influence of heat treatment on the in vitro degradation of Mg-6Zn alloy is studied by electrochemical measurements. After solid-solution treatment, the microstructure of the Mg-6Zn becomes more homogeneous, along with an elevated charge-transfer resistance in SBF and a reduced corrosion current density. After ageing treatment, the discrete intermetallic ,-MgZn phase enhances the cathodic hydrogen evolution and impairs the corrosion resistance of the alloy. Galvanic cells are expected on ageing, but the ageing process makes the microstructure of the alloy homogeneous. Heat treatment alters the in vitro degradation behavior of Mg-6Zn alloy and is applicable in adjusting the biodegradation rate. [source]

Progress and Challenge for Magnesium Alloys as Biomaterials,

ADVANCED ENGINEERING MATERIALS, Issue 8 2008
R. Zeng
Abstract Magnesium alloys are very biocompatiable and show promise for use in orthopaedic implant. Significant progress of research on bioabsorbable magnesium stents and orthopaedic bones has been achieved in recent years. The issues on degradation, hydrogen evolution, and corrosion fatigue and erosion corrosion of magnesium alloys and various influencing factors in simulated body fluid (SBF) are discussed. The research progress on magnesium and its alloys as biomaterials and miscellaneous approaches to enhancement in corrosion resistance is reviewed. Finally the challenges and strategy for their application as orthopaedic biomaterials are also proposed. [source]