Hydrogen exposion properties

The purpose of this study was to measure and compare the fracture toughness properties of Type 21-6-9 stainless steel for high-energy-rate and conventional forgings in the unexposed, hydrogen-exposed and tritium-exposed-and-aged conditions. 

Of course, oxygen is not the only impurity that will react with beryllium. Another material that is important in forming mixed-material layers with beryllium is carbon. The saturated value of retention that has been found in beryllium surfaces exposed to a large deuterium ion fluence could easily be overshadowed if a carbon rich layer forms on the beryllium surface due to impurity carbon ions in the incident plasma flux. The hydrogen retention properties of plasma deposited carbon films has been shown to dominate the total retention in beryllium samples exposed to the plasma at lower temperature. Once the sample temperature during exposure approaches 500°C there is little difference between the retention in Be/C mixed-material layers compared to clean beryllium samples [48]. The temperature dependence of the retention of carbon containing mixed material layers, as well as that of clean beryllium surfaces is shown in Fig. 14.10. There are two possible explanations for the reduced retention in the mixed-material layers formed at elevated temperature. The first is that beryllium carbide forms more readily at elevated temperature and less retention is expected in beryllium carbide [11]. The second is that carbon films deposited at elevated temperature also tend to retain less hydrogen isotopes [49]. 

It is somewhat less corrosion resistant than tantalum, and like tantalum suffers from hydrogen embrittlement if it is made cathodic by a galvanic couple or an external e.m.f., or is exposed to hot hydrogen gas. The metal anodises in acid electrolytes to form an anodic oxide film which has a high dielectric constant, and a high anodic breakdown potential. This latter property coupled with good electrical conductivity has led to the use of niobium as a substrate for platinum-group metals in impressed-current cathodic-protection anodes. 

Because of the exposed histidine ligands of the [2Fe-2S] cluster, the Rieske is capable of binding quinones in a redox-dependent manner. The variation of the hydrogen bond strength and of the electrostatic properties will control the movement of the catalytic domain of the Rieske protein. Therefore, the function depends on the unique structural and electrochemical properties of the Rieske cluster. 

The effect of microwave irradiation on the catalytic properties of a silver catalyst (Ag/Al203) in ethane epoxidation was studied by Klimov et al. [91]. It was found that on catalyst previously reduced with hydrogen the rates of both epoxidation and carbon dioxide formation increased considerably on exposure to a microwave field. This effect gradually decreased or even disappeared as the catalyst attained the steady state. It was suggested that this was very likely because of modification of electronic properties of the catalyst exposed to microwave irradiation. 

Double-stranded DNA has a unique property in that it is able to make identical copies of itself when supplied with precursors, relevant enzymes, and cofactors. In simplified terms, two strands begin to unwind and separate as the hydrogen bonds are broken. This produces single-stranded regions. Complementary deoxyribonu-cleotide triphosphates then pair with the exposed bases under the control of a DNA polymerase enzyme. 

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