一种散体材料SHPB被动围压试验体应力修正方法

本文利用有限元仿真给出了一种修正方法,并用数值仿真和试验验证了该方法的可靠性。研究表明：散体材料SHPB被动围压试验中,试样厚度远小于厚壁圆筒长度时,端部效应会导致厚壁圆筒不均匀凸出变形,计算材料的体应力-应变关系不能将厚壁圆筒应力状态简化为平面应力问题;厚壁圆筒处于弹性状态下,通过厚壁圆筒理论计算出的径向力与真实径向力存在一定比例关系,在一定范围内,折算系数与试样实时厚度呈二次函数关系。

     

Densities,excess molar volumes,and partial molar volumes for binary mixtures of water with monoethanolamine,diethanolamine, and triethanolamine from 25 to 80°C

We have measured densities of binary mixtures of water with monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA) over the full range of compositions and over the temperature range from 25 to 80°C. Results of these measurements have been used in calculating excess molar volumes and partial molar volumes. Knowledge of the volumetric properties of these mixtures is useful in connection with industrial treatment of acidic gases; derived excess molar volumes and partial molar volumes can be used as a basis for understanding some of the molecular interactions in water-organic mixtures.Presented at the Symposium, 76^th CSC Congress, Sherbrooke, Quebec, May 30–June 3, 1993, honoring Professor Donald Patterson on the occasion of his 65^th birthday.     

Nitration of benzyl derivatives of acetylated hexaazaisowurtzitane

Nitration of N-benzylated 2,4,6,8,10,12-hexaazaisowurtzitane derivatives occurs selectively at para-positions of the benzyl groups. The best reagent for this reaction is ammonium nitrate in sulfuric acid.     

Physicochemical Methods Used to Study Internal Structures of Liquid Binary Mixtures

Abstract

Different methods, based on application of studies of intensive physicochemical properties of liquid binary mixtures and ¹H-NMR spectral measurements, used in the analysis of intermolecular interactions and estimation of the internal structure of these mixtures and here reviewed.     

Acoustical Parameters of CuCl-KCl System in Acetonitrile-Water Solvent Mixture

Abstract

Ultrasonic velocity (U) and density (d) have been measured for CuCl-KCl in. acetonitrile water co-solvent at various temperatures from 298.15 to 318.15K. The adiabatic compressibility (β_ad), molar compressibility (β) specific acoustical impedance (Z), Rao Number (R) and Van der Waals Constant (b) have been computed. The variation of d, β_ad, β, Z, R and b with molarity of CuCl have been studied. The association between the components and the formation of complexes are treated.     

The Formation of Rosocyanin in the Presence of Water

Abstract

The reaction between curcumin and boric acid to form the 2:1 complex rosocyanin has hitherto been considered to require an almost water-free solution. It has now been shown that rosocyanin may be formed even if large amounts of water are present, provided that a suitable organic solvent is added. The theoretical conditions for such a solvent have been investigated. Procedures are given where the reaction takes place in a homogeneous solution or possibly at the organic interface. For analytical purposes the rosocyanin formed could either be measured in a homogeneous solution or extracted into an upper or lower organicphase. Methylisobutylketone seems to be the most suitable solvent which possesses convenient analytical properties.     

Hydrophobic hydration of some different types of quaternary ammonium bromides in mixtures of water andN,N-dimethylformamide

Enthalpies of solution of methyltributylammonium bromide, tetraethanolammonium bromide, and three azoniaspiroalkane bromides in binary solvent mixtures of water and N,N-dimethylformamide have been measured calorimetrically at 298.15^oK over the whole mole fraction range. The results are interpreted in terms of a simple hydration model with two parameters and compared with those of the corresponding tetraalkylammonium bromides. Enthalpic studies with different types of quaternary ammonium bromides are useful in reexamining the assumptions and limitations of the hydration model.     

Ionic enthalpies of transfer from water to water-sulfolane mixtures

NaCl, NaBr, NaI, NaClO₄, KCl, KClO₄, NaBPh₄, and Ph₄PBr solution enthalpies were measured in water-sulfolane mixtures at 30°C. Ionic enthalpies of transfer from water to mixed solvents were calculated on the basis of the assumption H _s ^o (BPh ₄ ^– )=H _s ^o (Ph₄P⁺). The variation of the ionic enthalpies of transfer with solvent composition is discussed in terms of ion-solvent interactions and of the effects caused by sulfolane on the structure of water.