Theoretical study of the isomers of the anions N2 −, P3 −, N2P−, and NP2 −

It has been shown by nonempirical calculations of the potential surfaces of the isomers that for the anions N₃ ^– and N₂P^– linear structures are somewhat more favorable than others. For P₃ ^– and P₂N^– there are several isomers lying close together: linear, angular, and cyclic. The stability of the cyclic relative to the linear isomers increases sharply when two or all of the atoms of the 2nd period are replaced by their analogs in the subgroups of the 3rd or later periods.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1590–1597, July, 1990.     

Synthesis and Antioxidant Activity Evaluation of Novel 5,7-dimethyl-3H-Thiazolo[4,5-B]Pyridines

Abstract

5,7-Dimethyl-3H-thiazolo[4,5-b]pyridine-2-one was obtained under the reaction of 4-iminothiazolidin-2-one with acetylacetone. Further structural modifications include the introduction of diversity at the N³ and C⁶ positions. The antioxidant activity of the synthesized compounds was evaluated in vitro by the method of scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the following free supplemental files: Additional figures]     

Mixtures of Diethyl Sulfoxide and Methanol: Structure and Thermodynamics

Journal of Solution Chemistry - Mixtures of sulfoxides with molecular solvents possess interesting physicochemical properties and may have applications in chemical synthesis. Hereby we confirm and...     

The equation of state of an anisotropic continuum

We establish the connection between the action and reaction vectors of a continuous hysteresis-free irrotational medium using the matrices of static parameters in the principal axes of anisotropy and the connection between the increments of these vectors using the matrices of differential parameters. We give an algorithm for computing the elements of both matrices as functions of the absolute value of the action vector. The results can be applied to fields of different physical natures: electromagnetic, mechanical, and others. Translated fromMatematicheskie Metody i Fiziko-Mekhanicheskie Polya, No. 37, 1994, pp. 84–86.     

Heat capacity close to the unattainable critical layering point

An analysis of the literature data on the heat capacity of aqueous low-concentration solutions of tert-butanol at several temperatures showed that the heat capacity peak in this concentration region was largely related to critical concentration fluctuations close to the binodal, which appeared because of microlayering on the network of H-bonds in solutions of hydrophobic nonelectrolyte molecules.     

Superconducting clusters in the pseudogap region

The upper boundary of the pseudogap state has been derived as a function of the doping within the impurity mechanism of high-T _c superconductivity under the assumption that, in the region bordering the superconducting phase on the side of the doping less than the optimum level (the pseudogap region), there exist finite superconducting clusters and the boundary of the superconducting phase corresponds to the threshold of the existence of an infinite superconducting cluster. The position of this boundary is in agreement with experiment. The condition imposed on the doping level at which the giant proximity effect should be observed has been derived. It means essentially that the thickness of the nonsuperconducting layer should be small compared to the average size of the superconducting clusters.