Application of the variation principle for the problem of buckling of a nonlinearly elastic ring nonuniform along its thickness

There has been considerable recent attention given to the stressed and buckled states of items with complicated configuration made of different nonlinearly elastic materials joined by complete adhesion. However, effective analytical solutions for such problems have been hindered by mathematical difficulties. Approximate methods have thus been developed for such problems. A variational combined principle has been formulated in this communication. A nonlinear geometrical approach has been used for formulating a mixed-type functional with physical relationships given by Euler equations, nonlinear equilibrium equations, and nonlinear boundary conditions for a piecewise-nonuniform nonlinearly elastic body composed of finite elements (particles). As an example, buckling along the nonuniform thickness of nonlinearly elastic rings was analyzed hypothetically assuming plane cross-sections. Options for two-, three-, four-, five-, and six-layered rings in a periodical structure have been reviewed. The critical buckling forces for an even number of layers have been found to be equal to each other. The ratios of the critical forces, elasticity moduli, and proportionality levels were determined for all five variants by the Runge-Kutta method.Presented at the Ninth International Conference on the Mechanics of Composite Materials (Riga, October, 1995).Translated from Mekhanika Kompozitnykh Materialov, Vol. 31, No. 2, pp. 262–268, March–April, 1995.     

Reactions of cyclochlorotriphosphazatriene with 2-mercaptoethanol. Calorimetric and spectroscopic investigations of the derived products

Abstract

The reactions of hexachlorocyclotriphosphazatriene, N₃P₃Cl₆ (1) with 2-mercaptoethanol, 2-HS-CH₂-CH₂-OH (2), in (1:1, 1:2 and 1:3) mole ratios, in excess of NaH, in THF and diethylether solutions yield a total of 6 novel products: one mono spiro, N₃P₃Cl₄[O-CH₂-CH₂-S] (3); one mono-substituted open chain, N₃P₃Cl₅[S-CH₂-CH₂-OH] (4); one dispiro, N₃P₃Cl₂[O-CH₂-CH₂-S]₂ (5); one tri-substituted open chain, N₃P₃Cl₃[S-CH₂-CH₂-OH]₃ (6); one tris-spiro, N₃P₃[O-CH₂-CH₂-S]₃ (7) and one disubstituted open chain, N₃P₃Cl₄[S-CH₂-CH₂-OH]₂ (8) derivatives. The spiro products (3, 5 and 7) are formed as the major products in this system and all of the synthesized compounds are found to be stable at room temperature. The structures of the derived compounds were elucidated by elemental analysis, TLC-MS, ³¹P and ¹H NMR spectral data. For evaluation of melting behavior of derivatives (6) and (7), thermal transition peaks and their corresponding enthalpies were determined via DSC technique.     

Synthesis of polyfunctional polyconjugated oligomers of 4-aminophenol and their use in obtaining of antistatic composite materials

Polyconjugated oligomers containing aromatic links with hydroxyl and amino functional groups were synthesized by oxidative polycondensation of 4-aminophenol. They exhibit solubility and fusibility, heat resistant, paramagnetic and semiconductor properties, and also high reactivity in reactions characteristic for aromatic hydroxyl groups. These oligomers were used as supplements to industrial polymers. Composite materials were obtained including a rubber with high physico-mechanical, thermal, and electrical properties.     

Role of the Matrix Effect in Analysis of Biological Objects Using Mass Spectrometry with Inductively Coupled Plasma

Technical Physics - An attempt at eliminating the nonspectral matrix effect leading to suppression of the analytic signal intensity at instrument output has been made using an Agilent-7700 mass...     

Resonance Assisted Chalcogen Bonding as a New Synthon in the Design of Dyes

Intramolecular chalcogen bonding in arylhydrazones of sulfamethizole is strengthened by conjugation in the π-system of a noncovalent five-membered ring. The S⋅⋅⋅O distance in the sulfamethizole moiety of these compounds ranges from 2.698(3) to 2.806(15) Å, which indicates its strong dependence on the attached arylhydrazone fragments. Information on the nature of the intramolecular chalcogen bond was afforded by DFT calculations.     

First example of the cascade acylation/IMDAV/ene reaction sequence,leading to N-arylbenzo[f]isoindole-4-carboxylic acids possessing anti-viral activity

The reaction between readily accessible N-aryl-3-phenylallylamines and maleic anhydride led to unexpected products – polysubstituted hydrogenated benzo[f]isoindole-4-carboxylic acids. This transformation proceeds through a previously unknown sequence of steps: N-acylation of the allylamine with maleic anhydride, intramolecular Diels-Alder reaction of the vinylarene in the intermediate N-maleamide, and Alder-ene reaction of the products of the previous two steps. Selected benzo[f]isoindoles displayed antiviral activity.     

Changes in Operating Characteristics of Transformer Oil under the Action of Ionizing Radiation

Physics of Atomic Nuclei - The changes in physicochemical parameters such as specific resistance, viscosity, density, and formation of gaseous products H2, CH4, C2H4, C2H6, C3H8, C4H10, C5H12, and...     

Compensation of the volume charge of ions in a time-of-flight mass analyzer

A method of forced compensation of the volume charge of ions leading to considerable deterioration of the dispersion characteristics of a time-of-flight mass analyzer with a sector electrostatic field is described. It is shown that recompensation of the voluem charge also deteriorates the resolution of the instrument.     

The biomolecular alterations in cladonia convoluta in response to lead exposure

In this study, structural alterations in the biomolecular profile of the Cladonia convoluta exposed to lead were investigated considering the potential of lichens in biomonitoring practices. Particularly, qualitative and quantitative changes in the lipids, polysaccharides, proteins, and nucleic acids along with various organic acids in lead-exposed lichen were analytically analyzed using infrared spectroscopy. Moreover, the quantitative changes in chlorophyl and malondialdehyde levels were measured by independent biochemical assays. Chlorophyll content analysis revealed a dose- and time-dependent decrease in chlorophyl content, whereas malondialdehyde content analysis revealed lipid peroxidation as a result of lead exposure. Lead exposure diminished total nucleic acid quantity, which can be an important parameter for the elucidation of heavy metal tolerance mechanisms in lichens. Furthermore, lead exposure increased the quantity of usnic acid, signifying its importance in the lichen-based decontamination of metal polluted areas.