2-Propanol oxidation on platinum and platinum–rhodium electrodeposits

The electrocatalytic oxidation of 2-propanol was investigated using on line differential electrochemical mass spectrometry (DEMS) on electrodeposited Pt and an arrange of bimetallics: Pt_0.84Rh_0.16, Pt_0.70Rh_0.30, Pt_0.55Rh_0.45. It has been observed that the Pt_0.84Rh_0.16 bimetallic electrode presented the best catalytic activity for 2-propanol electrochemical oxidation. Since 2-propanol is a secondary alcohol, only acetone and CO₂ are produced. The total yield of CO₂ and acetone has been determined from the DEMS measurements. It is found that acetone is the major product, as reported before for other electrodes. The acetone and CO₂ yield depends on the electrode composition. High amount of rhodium in the electrode composition strongly diminish the reaction rate as indicated by the decrease of both the acetone and CO₂ yield. However, acetone inhibition is much more intense. The only bimetallic electrode that presents considerable mass spectroscopy signals intensity for CO₂ and acetone is the Pt_0.84Rh_0.16 electrode. This electrode shows a slight increase in CO₂ selectivity, compared to the other electrodes studied in this work. Only very low coverages of stable adsorbates were present during the reaction. Two and one carbon adsorbate were observed for all the electrodes. Three carbon adsorbates were detected only for the Pt_0.84Rh_0.16 electrode. Therefore, acetone production does not require a stable adsorbate.     

One singularly perturbed system of partial differential equations of the first order

Translated from Matematicheskie Zametki, Vol. 57, No. 3, pp. 338–349, March, 1995.     

Recyclization of 4-oxo-1,3-benzoxazinium perchlorates to 4-substituted 5-(o-hydroxyphenyl)-1,2,4-oxadiazolium salts

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 280–281, February, 1992.     

Muon spin resonance and repolarization in amorphous silicon monoxide (a-SiO)

Studies of the muonium fractions in the amorphous oxide a-SiO have been carried out by RF resonance at TRIUMF, Canada and LF repolarization techniques at RAL, U.K. The resonance measurements confirm the presence of the interstitial Mu centre in this intermediate oxide of silicon. Analysis of the data gathered at RAL, using a recently-developed fitting technique, reveals that the Mu^* state is present here as well, but with lower relative fractions than in a-Si. However, as in the latter material, but in contrast to c-Si, this bond-centre species appears to be stable up to room temperature.     

取代对苯二酚醚化物的合成研究

本文从取代的对苯三酚３出发、利用Ｗｉｌｌｉａｍｓｏｎ醚化反应合成了一系列它的醚化产物４ａ－４Ｈ，给出了它们的核磁共振数据（氢谱和碳谱）。讨论了影响醚化反应的一些因素，比较了不同烷化剂发生醚化反应的活泼性。     

Europium-151 Mössbauer spectroscopic and XANES investigation of europium-exchanged Y-zeolite

Eu³⁺ in ca. 10 wt% europium-exchanged Y-zeolite is partially reduced by treatment in hydrogen at 600°C to Eu²⁺. The reduction of Eu³⁺ is more readily achieved in Y-zeolite than in europium(III) oxide. The discrepancy in the extent of reduction as revealed by¹⁵¹Eu Mössbauer spectroscopy and near edge X-ray absorption fine structure (XANES) is associated with any difference in the recoil free fractions of Eu²⁺ and Eu³⁺ which may exist at 298 K and the enhanced sensitivity of the XANES to changes in the europium oxidation state.     

Asymptotic expansions of integrals of two Bessel functions via the generalized hypergeometric and Meijer functions

Asymptotic expansions of certain finite and infinite integrals involving products of two Bessel functions of the first kind are obtained by using the generalized hypergeometric and Meijer functions. The Bessel functions involved are of arbitrary (generally different) orders, but of the same argument containing a parameter which tends to infinity. These types of integrals arise in various contexts, including wave scattering and crystallography, and are of general mathematical interest being related to the Riemann—Liouville and Hankel integrals. The results complete the asymptotic expansions derived previously by two different methods — a straightforward approach and the Mellin-transform technique. These asymptotic expansions supply practical algorithms for computing the integrals. The leading terms explicitly provide valuable analytical insight into the high-frequency behavior of the solutions to the wave-scattering problems.