A thermokinetic model of hydrogen diffusion across a metallic tube is established. It includes the enthalpy change of the metal– hydrogen reaction, heat losses, dependences of reaction rate and hydrogen diffusion coefficient on temperature, and self-stress effects, etc. A phenomenon, the super fast diffusion of hydrogen before the up-hill diffusion and Fickian diffusion during hydrogen gas char...

A feasible solution to the problem of urban pollution is hydrogen propelled zero-emission vehicles. The US Department of Energy (DoE) has set the target of 6.5 wt% of H2 storage capacity and a volumetric energy density of 1.5 kWh/L at an operating temperature and pressure conditions of 50C and 2.5 bar respectively by 2010.[1] The storage media being studied until now have not been able to succe...

Identification and characterization of different forms of methotrexate were carried out by crystallization from different solvents. Five different forms of the drug were obtained. Appearance of a desolvation endotherm in the DSC accompanied by mass loss in TGA for forms I, II, IV and V showed these forms to be acetonitrile solvate hydrate (form I), trihydrate (forms II and IV) and dimethylforma...

Meloxicam is widely prescribed as an analgesic and anti-inflammatory drug in human therapeutics. Owing the very low aqueous solubility of meloxicam, this property has been studied dimethyl sulfoxide (DMSO)-aqueous solvent systems at several temperatures from 273.15 to 313.15 K expand database about drugs mixed solvents. The flask shake method followed by ultraviolet-visible (UV-vis) spectrophot...

In a previous paper, Brouwers and Van Eijk [1] presented a theoretical study on the dissolution (reaction) of pulverised powder coal fly ash. This fly ash was modelled as hollow spheres, and a shrinking core model was derived for these hollow spheres that contain two regions (an outer hull and an inner region). The obtained analytical equations were applied to the dissolution experiments by Pie...

Samples of the waste rock obtained from Marofengin South Africa ground 60, 70 and 80% passing 75µm were leached with cyanide in bottle roll tests. The results obtained showed that the percentage gold dissolution depends more on the ore size consists than on the cyanide concentration with the highest average dissolution rates of 88.75, 94.34 and 95.90% found at 600, 500 and 500 ppm, for 60, ...

In this paper, CdSe nanocrystal dissolution in an aqueous solution was studied. It was found that light is a key factor affecting the dissolution of nanocrystals. In the presence of light, the electrons generated from CdSe nanocrystals reduce water to hydrogen and hydroxide ions (OH-) while photo-generated holes oxidize CdSe to Cd2+ and elemental Se. The dissolution was accelerated in an acidic...

The objective of this study was to compare corrosion behavior in several titanium alloys with immersion in acidulated saline solutions containing hydrogen peroxide. Seven types of titanium alloy were immersed in saline solutions with varying levels of pH and hydrogen peroxide content, and resulting differences in color and release of metallic elements determined in each alloy. Some alloys were ...

Density of the Earth's core is lower than that of pure iron and the light element(s) in the core is a long-standing problem. Hydrogen is the most abundant element in the solar system and thus one of the important candidates. However, the dissolution process of hydrogen into iron remained unclear. Here we carry out high-pressure and high-temperature in situ neutron diffraction experiments and cl...

New materials capable of storing hydrogen at high gravimetric and volumetric densities are required if hydrogen is to be widely employed as a clean alternative to hydrocarbon fuels in cars and other mobile applications. With exceptionally high surface areas and chemically-tunable structures, microporous metal–organic frameworks have recently emerged as some of the most promising candidate mater...