Heats of displacement of hydrogen from palladium by noble gases

It has been observed that noble gases, such as helium, neon and argon produce heat evolution when contacted with Pd powder partially saturated with hydrogen. These phenomena have been studied with flow-through adsorption microcalorimetry. The observed exothermic effects are comparable to those usually associated with the heat of sorption of hydrogen in palladium. It is suggested that the noble gases displace the adsorbed H species from the surface of Pd, causing their reabsorption in the Pd lattice with the exothermic heat of PdH bonds formation, or the formation of H₂, both heat evolutions being observed with a flow-through microcalorimeter.     

Hydrogen and noble gas interactions with iron nano-flakes

Exposure of pure iron nano-flakes to hydrogen generates a high heat evolution associated with hydrogen uptakes shown by flow-through microcalorimetry. A large part of the hydrogen was found to be irreversibly absorbed by the iron flakes at 220 °C and atmospheric pressure, but an increased desorption of hydrogen was achieved by noble gases, such as helium and argon. Thus the iron surfaces displayed strong affinity for hydrogen, but also, surprisingly, for the noble gases, which were found to be able to displace hydrogen from the iron surfaces.The uptake of hydrogen by the iron flakes was observed to reach 9 wt.% after exposure for 5 h, which may be of interest in hydrogen storage applications. Desorption with the help of argon may provide an acceptable method of hydrogen recovery.     

Copper and iron interactions with angiotensin-converting enzyme inhibitors. A study by fast-atom bombardment tandem mass spectrometry

Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd.     

Finite groups ofOD-conjugates

Given any setx, define the set of conjugates ofx to be Given any subgroupG of the group of permutations of {1, ?,n}, it is consistent with ZFC that there exists an orderedn-tuple 〈x ₁, ?, x_n〉 such that $$c(\langle x_1 ,...,x_n \rangle ) = \{ \langle x_{\pi 1} ,...,x_{\pi n} \rangle |\pi \in G\} .$$      

Activation of Au/TiO2 catalyst for CO oxidation

Changes in a Au/TiO(2) catalyst during the activation process from an as-prepared state, consisting of supported AuO(x)(OH)(4-2x)(-) species, were monitored with X-ray absorption spectroscopy and FTIR spectroscopy, complemented with XPS, microcalorimetry, and TEM characterization. When the catalyst was activated with H(2) pulses at 298 K, there was an induction period when little changes were detected. This was followed by a period of increasing rate of reduction of Au(3+) to Au(0), before the reduction rate decreased until the sample was fully reduced. A similar trend in the activation process was observed if CO pulses at 273 K or a steady flow of CO at about 240 K was used to activate the sample. With both activation procedures, the CO oxidation activity of the catalyst at 195 K increased with the degree of reduction up to 70% reduction, and decreased slightly beyond 80% reduction. The results were consistent with metallic Au being necessary for catalytic activity.