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Based on previous work of the first author, the local sufficient condition of uniqueness of the solution of the incremental boundary-value problem in generalized elastoplasticity which excludes the possibility of bifurcation state is compared with the local necessary condition for the localization of plastic deformations as a Rice—Rudnicki localization plane. The analytical results of limitations imposed on the isothermal hardening functions (moduli) by the Rice—Rudnicki condition of plastic strain localization are compared with those resulting from the local uniqueness condition. It is shown that the local sufficient condition of uniqueness of the solution of the incremental boundary-value problem with an equals sign becomes a local necessary condition of non-uniqueness or local necessary condition of the possible appearance of a bifurcation state. [ABSTRACT FROM PUBLISHER] more...

The classical, most frequently cited constitutive equations of elastic—plastic materials with non-associated and associated plastic flow laws are specified. Local sufficient uniqueness conditions for the solution of the boundary-value problem and local necessary conditions of initiation of deformation localization in the form of a Rice—Rudnicki localization plane are derived. We show that sufficient local uniqueness conditions for these constitutive equations with sign (≤) on the right-hand side become local necessary conditions of non-uniqueness of the solution of the boundary-value problem. [ABSTRACT FROM PUBLISHER] more...

Abstract: The paper presents the conformational, vibrational and hydrogen bond characteristics of 5-methyl-3-nitro-2-hydroxyacetophenone studied with the combined matrix-isolation FT-IR spectroscopic and theoretical (DFT/B3LYP/6-31++G∗∗) technique. Theoretical calculations predict three stable conformations of the studied compound. Only two of these conformations could be identified experimentally using the matrix-isolation FT-IR technique. The conformation with the intramolecular hydrogen bond OH…On found to be more stable than the conformation with the OH…O hydrogen bond by 7.28kJ/mol. The complete assignment of the experimental spectra could be performed based on the theoretical calculations including the normal coordinate analysis and isotopic substitution. [Copyright &y& Elsevier] more...

Abstract: FT-IR and FT-Raman spectra of the ortho-hydroxy acylaromatic Schiff bases (2-(α-(N-methylimino)ethyl)-4-chloro-6-nitrophenol –I, 2-(α-(N-methylimino)ethyl)-4,6-dichlorophenol –II), and their isotoposubstitutions have been recorded in the range of 4000–50cm−1. The spectra were interpreted by a normal coordinate analysis based on B3LYP/6-31++G(d,p) density functional calculations and experimental deuterosubstitution. Proton transfer equilibrium between the enolic and keto tautomers of two sterically hindered Schiff bases has been studied combined experimental (FT-IR matrix-isolation and FT-Raman) and theoretical (DFT/B3LYP/6-31++G(d,p)) methods. [Copyright &y& Elsevier] more...

The vibrational spectrum of 4-methyl-2′-hydroxy-4′-ethyloxyazobenzene (MHEAB) has been studied in low-temperature argon matrices and in CCl4 solutions. Calculations at the DFT (B3-LYP) level of theory with the 6-31++G** basis set, as well as additional IR experiments of deuterated samples and of derivatives without the OH group, have been used to analyze the IR MHEAB spectrum. In the calculations we used the conventional harmonic approach, as well as an approach based on an one-dimensional anharmonic model. It has been shown that introduction of the OH group into the compound and formation of the OH⋯N intra-molecular hydrogen bond cause an increase of the intensity of the stretching N&z.dbnd6;N mode, but do not affect the frequencies of the azo-bridge vibrations. [Copyright &y& Elsevier] more...

A homologous series of 4-methyl-2′-hydroxy-4′-alkoxyazobenzenes with chain lengths from 1 to 12 carbon atoms was synthesized and the temperatures of melting, freezing and transition from nematic to isotropic phase were determined. The main thermodynamic characteristics for those transitions were estimated. The liquid crystalline properties were compared with those of homologous series without OH groups and show a marked extension of the nematic phase for the OH substituted compounds. The spectroscopic manifestations of the hydrogenbonded OH ... N chelate ring are discussed, based on a comparison of experimental and Density Functional Theory (DFT) calculated frequencies and IR intensities. The evolution of the IR absorption in the range 1540-1660 cm[sup -1], ascribed to the OH bending vibrations, is presented on going from the dilute CCl[sub 4] solution through the isotropic and nematic phases to the solid state. [ABSTRACT FROM AUTHOR] more...

The article cites a research study that examines the exercise capacity of adolescent girls with idiopathic scoliosis. It determines whether Cheneau's brace decreases exercise capacity in adolescent patients with idiopathic scoliosis. The study included 22 girls with DM idiopathic scoliosis. It was found that Cheneau's brace essentially reduces exercise capacity for patients with idiopathic adolescent scoliosis. more...