Features of the molecular structure of organochromiumoxane yttriumoxane alumoxane oligomers

Russian Chemical Bulletin - Geometric parameters of one of the probable molecular structures of amorphous organochromiumoxane yttriumoxane alumoxane oligomers have been calculated using...     

Hydrosilylation of Allylgermanes

Russian Journal of General Chemistry - The hydrosilylation reactions of allylgermanes R3GeAll (R3 = Cl3, Me3) in the presence of a platinum catalyst (Karstedt catalyst) with...     

Interaction of physical fields in the acoustomagnetic effect

Experimental studies of the acoustomagnetic effect in a magnetic fluid are performed. The linear sizes of magnetic nanoparticles of the dispersed phase are determined by the acoustogranulometric method. The mean deviation of the diameters of magnetic nanoparticles obtained at eight fixed frequencies in the range of 18?C65 kHz from their average values ??d _max?? = 16 nm and ??d _max?? = 9 nm is 4.4%. These results are in satisfactory agreement with the results obtained by the magnetorelaxometry method for magnetite nanoparticles. On the basis of experimental data, in the framework of the concentrational model, interaction between the elastic and thermal fields and between the magnetic and dynamic demagnetizing fields in the acoustomagnetic effect is studied. The conclusions of the model theory are confirmed by the experimental results.     

泥沙输运模拟综述——现状及其发展趋势

随着流体力学中数值方法的飞速发展,计算模型已经成为研究流体运动,泥沙输运和不同环境(诸如河流,湖泊及沿海地区)中相应污染物归趋过程等方面非常有吸引力的工具,在过去的30多年里,发展了许多计算水动力学/泥沙输运模型.文章追溯当前具有代表性的(一维、二维、三维)模型的发展历程,描述他们各自的特点,优势及局限,力图作为对模型方面感兴趣读者的第一指南,同时也为大家讨论模型的局限性,未来的发展趋势和研究需求方面搭建一个平台.给出了模型的表达,时空特性,水动力学和沉积物的耦合方式,处理非恒定流,推移质和悬移质,泥沙交换过程,泥沙类型(粘性或非粘性)及非均匀泥沙输运的能力.总结了不同模型的应用实例,读者可以运用这些例子作为研究模型设置,模型率定及模型验证的参考.给出了选择泥沙输运模型应遵循的原则,模型输入及率定方面存在的问题及改进的途径.探讨了现有水动力学/泥沙输运模型在处理复杂湍流,泥沙携带,流动与输沙耦合,非均匀泥沙,离散和扩散系数,河岸来沙处理等方面的局限性及改进的方向.最后,对基于多相流思想的泥沙输运模型及其它一些交叉性问题作了评述与展望.     

A method of approximating functions in Hp, 0<p≤1

Translated from Matematicheskie Zametki, Vol. 57, No. 4, pp. 580–585, April, 1995.     

13C NMR spectra of 9-R-9,10-di-p-X-phenylphenanthrenonium ions: Apparent “nonclassical” interaction effect

Conclusions In the example of 9-R-9,10-di-p-X-phenylphenanthrenonium ions, it has been established that the so-called tool of increasing electron demand that is used to detect nonclassical interactions in carbonium ions, based on an analysis of the chemical shifts of the carboniumcenter atoms in the¹³C NMR spectra of -X-phenyl-substituted carbocations as a function of the electronic effects of the substituent X, is not universal in nature.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 304–308, February, 1983.     

Free and total para-aminobenzoic acid analysis in plants with high-performance liquid chromatography/tandem mass spectrometry

para-Aminobenzoic acid (PABA), a precursor in the synthesis of folates in plants, is determined by liquid chromatography/tandem mass spectrometry (LC/MS/MS). In plants PABA can be converted into its beta-D-glucopyranosyl ester (PABA-Glc) and can also exist in its free form. In this work, we developed and validated a quantitative method to study free and total PABA in plants. The total PABA (free PABA plus PABA-Glc) can be evaluated after acid hydrolysis at 80 degrees C for 2 hours. The plant material is homogenized and the PABA content is quantified using the standard addition procedure. The validated method is selective, sensitive, simple, accurate, has a recovery between 99.6 to 102.5%, is reproducible (RSD between 1.4 and 4.4%), and is linear between 2.5 and 1538 ng/mL. Free and total PABA determinations in five vegetables showed that different plant species had different amounts of free and total PABA, and that the ratios of total versus free PABA were also variable. This new method could be valuable for studies of folate synthesis in plants.     

Crystal structure of ZnCl2·H2O·18-crown-6

State Scientific Research Institute for the Chemistry and Technology of Heteroorganic Compounds. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 4, pp. 188–189, July–August, 1989.