Multicentre interaction in 12-nuclear rhenium carbon-centered chalcocyanide clusters

A topological method of quantum chemistry (AIM) is used to study the contact area of a triangular bridging group {CS₃} in 12-nuclear cluster fragments of {Re₁₂CS₁₇}. It is shown that in the region under consideration the intramolecular interaction is characterized by a ring critical point (rcp), and its parameters depend on the oxidation state and explain the unusual structural changes in cluster complexes in redox transformations: [Re₁₂CS₁₇(CN)₆]⁸⁻ ↔ [Re₁₂CS₁₇(CN)₆]⁶⁻.     

Effect of surface preparation of ABM-1 alloy on properties of glued joints

The possibility of using the bonding method to assemble beryllium ABM-1 alloy has been analyzed. Recommendations are given in relation to the types of film adhesives for bonding parts. It has been established that the soundest results in regards to strength properties and anticorrosion protection can be achieved through the anodic oxidation of alloy’s surface and an additional application of an EP-0214 coat.     

Synthesis and structure of layered fluorine-containing crystal hydrates based on aquacomplexes of noble metals

Crystal hydrates were synthesized based on aquaions of noble metals [M(H₂O)₆]F₃·nH₂O, where n = 3–8 and M = Ir, Rh. The structure of the resulting crystal hydrates with three aqueous molecules is characterized by the space group P3, Z = 1 and has a layered form. The positively charged layers [M(H₂O)₆F ₂ ⁺ which alter with negatively charged layers of the composition ∼_-·3H₂O, are located perpendicular to the c axis. According to X-ray structural and nuclear magnetic resonance data, the water molecules and the F_- ions in the negatively charged layers are disordered. Translated fromZhurnal Strukturnoi Khimii, Vol.40, No. 2, pp. 259–264, March–April, 1999.     

Acid-base conversions of nitrogen heterocycles by the method of NMR spectroscopy. 2. Substituted pyridine- and pyrimidine-1-oxides

Features of the change in the chemical shifts of the protons of substituted pyridine-, pyrimidine-, 3-hydroxypyridine-, and 5-hydroxypyrimidine-1-oxides, as dependent on the basicity of the medium, were investigated. The ionization constants and the possible forms of the occurrence of the molecules were determined. The character of the influence of the substituents (alkyl, hydroxyl) on the pK_a values and the PMR spectral parameters was obtained. The comparison of the results obtained with the data on substituted pyridines and pyrimidines was carried out.For Communication 1, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1369–1376, October, 1987.     

Strong viscous interaction on triangular and slipping wings

The flow past triangular slipping wings is considered in strong viscous interaction conditions. It is shown that the solution of each of the problems discussed is not unique. The condition is obtained which has to be satisfied by the solution on the axis of symmetry of a triangular wing of infinite dimensions. The class of self-similar flows in the boundary layer of a thin triangular wing is found.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 94–99, November–December, 1970.     

多功能两亲梳状聚合物的合成及包覆荧光量子点

利用溶液聚合和成酰胺反应合成了多功能梳状两亲性共聚物,聚(甲基丙烯酸-co-甲基丙烯酸十八酯)-(乙醇胺-乙二胺叶酸)(PSM-EE-FA).用红外光谱(FTIR),核磁共振(1H-NMR)及凝胶渗透色谱(GPC)表征了该聚合物的结构及分子量分布.实验结果证明合成了该聚合物,其数均分子量(Mn)为28600,多分散性为1.375.用该两亲梳状聚合物包覆油溶性CdSe/ZnS量子点,通过相转移作用,得到水溶性靶向量子点(PSM-EE-FA-QDs).该水溶性量子点溶液具有较好的稳定性.通过紫外-可见(UV-Vis)及荧光发射光谱分析对该量子点的光学性质进行研究.结果表明,PSM-EE-FA-QDs的紫外-可见光谱及荧光发射光谱峰形与原量子点基本一致.由于量子点表面聚合物层的形成,峰位发生少量红移.该量子点水溶液的荧光强度是原量子点氯仿溶液的98%,荧光产率是原量子点氯仿溶液的95%.动态光散射(DLS)及透射电镜(TEM)测试结果表明水溶性量子点分布均匀.合成的水溶性量子点不但光学性能稳定,而且聚合物及水溶性量子点的合成方法较为简便.     

1H NMR Study of Zeolite Water Structure and Broensted Acid Centers in Chabazite

The disordered structure of absorbed water in a highly porous zeolite chabazite Ca₂[Al₄Si₈O₂₄]·nH₂O (2 ≤ n ≤ 12.8) is studied from motionally narrowed ¹H nuclear magnetic resonance spectra at room temperature. Concentration phase transitions were observed at n ≈ 8.3 and n ≈ 10.2. The transitions are accompanied by displacement of Ca²⁺ ions and variation of the Broensted acid centers at inner surface of zeolite pores.     

相对论性核碰撞中Φ介子产生和弦碎裂函数

用强子和弦级联模型LUCIAE系统研究从AGS到SPS,到RHIC,再到LHC能量核–核碰撞中Φ介子产生.采用与能量有关弦碎裂函数,并通过与荷电粒子多重数实验数据的比较确定其中的参数后,LUCIAE模型给出的Φ介子产额与实验数据也都相近,得到的事件平均弦碎裂变量随能量之增趋饱和规律,可能是核穿透性能量行为的定性表示.     

Paramagnetic properties of ion-implanted polymer layers

Films of polyethylene, polyethylene terephthalate, and polyamine-6 implanted with B⁺ and N⁺ ions with an energy of 100 keV are investigated by an EPR method in a dose interval of 1·10¹⁴–1·10¹⁷ cm⁻². It is shown that paramagnetic centers with g=2.0025 formed in the implanted polymers have a nature similar to the nature of paramagnetic centers of pyrolized and initially conducting polymers. Correspondence of the character of the variation in paramagnetic characteristics of the modified polymers to the model proposed earlier for the formation of pyrocarbon “drops” in ion implantation is revealed. The relaxation times for paramagnetic centers in the implanted polymer films are calculated and assumptions are made about the formation of a quasi-two-dimensional electron gas as well as the possibility of magnetic ordering in polymer-film layers modified by high-dosage implantation. The effect of oxygen on the electron states of the implanted polymer specimens is studied. Belarusian State University, 4, Skorina Ave., Minsk, 220050 Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 4, pp. 562–567, July–August, 1998.