漫谈有效数字和计算器

介绍了有效数字的概念及其计算规则,介绍了计算器的一般特性及使用技巧,并给出计算实例.     

速度算符和电子的颤动

指出了国外某些量子力学教材中关于速度算符的概念错误和相对论自由电子进行颤动的错误,分析了错误的原因.     

Reaction of arylidene-2-naphthylamines with ethyl furoylacetate

The reaction of arylidene-2-naphthylamines with ethyl furoylacetate was studied. It is shown that noncyclic amino keto esters are formed when the reaction is carried out without a catalyst and that esters of the benzo[f]quinoline series are formed when the reaction is carried out in the presence of a catalyst and an oxidizing agent. Esters of the benzo[f]quinoline series are also formed in the cyclization of the amino keto esters. The structures of the reaction products were confirmed by the results of elementary analysis and the IR, UV, NMR, and mass spectroscopic data.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 169–172, February, 1979.     

Spectral-luminescence characteristics of 1,3-diaryl-4,7-phenanthrolines

The effect of the nature of the substituents and the solvent on the absorption and fluorescence spectra and the fluorescence quantum yields of 1,3-diaryl-4,7-phenanthrolines was studied. Electron-donor groups in the para position of the phenyl ring cause a bathochromic shift of the absorption and fluorescence spectra and an increase in the fluorescence quantum yields. A change in the polarity of the solvent leads to a significant shift of the fluorescence spectra of hydroxy and dialkylamino derivatives of 4,7-phenanthroline.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1651–1654, December, 1987.     

Method of high-purity silica production from hexafluorosilicic acid

The method elaborated allows to create a no-waste technology for obtaining two marketable products-high silica purity, which is the raw material for glass surface treatment, and fluorite qith CaF₂ cintents of not less than 92%.     

Local clustering coefficients in preferential attachment models

The local clustering coefficients of preferential attachment models are analyzed. Previously, a general approach to preferential attachment was proposed (the PA-class was introduced); it was shown that the degree distribution in all models of the PA-class obeys a power law. The global clustering coefficient was also analyzed, and a lower bound for the mean local clustering coefficient was found. In the paper, new results are obtained by analyzing the local clustering coefficients of models of the PA-class. Namely, the behavior of the mean value C ₂(n, d) of local clustering over vertices of degree d is studied.