The K5 capsular polysaccharide of the bacterium Acinetobacter baumannii SDF with the same K unit containing Leg5Ac7Ac as the K7 capsular polysaccharide but a different linkage between the K units

Russian Chemical Bulletin - The K5 capsular polysaccharide (CPS) was isolated from the bacterium Acinetobacter baumannii (A. baumannii) SDF and studied by 1D and 2D 1H and 13C NMR spectroscopy...     

On the modeling of a prestressed thermoelectroelastic half-space with a coating

The constitutive equations of nonlinear mechanics of a prestressed electrothermoelastic continuum are linearized in the framework of the theory of small strains imposed on finite strains. Simple and convenient-to-operate formulas of linearized constitutive equations and equations of motion of the mediumare obtained. A model of electrothermoelastic half-space with inhomogeneous coating, which is a structure of functionally graded layers, is proposed. It is assumed that each of the medium components is under the action of initial mechanical strains and initial temperature, and the materials of the medium components are orthotropic pyroelectric materials of hexagonal crystal system of class 6 mm. The integral representation of the mediumwave field is constructed by a hybrid numerical-analytical method based on a combination of analytical solutions and numerical schemes used to reconstruct the Green function for the inhomogeneous components of the coating and the matrix approach used to satisfy the boundary conditions.     

Dynamic equations of a prestressed magnetoelectroelastic medium

The constitutive relations of nonlinear mechanics of a magnetoelectroelastic medium subjected to initial mechanical stresses are linearized in the framework of material (Lagrangian) coordinates. The final expressions are constructed independently of the choice of curvilinear coordinates and are represented in a form convenient for theoretical and applied studies. The constitutive relations for the motion of a prestressed magnetoelectroelastic medium are given in rectangular Cartesian coordinates. The influence of the initial mechanical stresses on piezomagnetoelectric materials of the class 6mm is studied.     

Resolution of overlapping luminescence bands by measurement of time-resolved spectra

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 3, pp. 431–438, September, 1991.     

Carbohydrate Structure Database (CSDB): new features

Russian Chemical Bulletin - Carbohydrate Structure Database (CSDB) is a regularly updated database containing structural, taxonomic, bibliographic, NMR spectroscopic, and other information on...     

New synthesis of moraprenyl bromide

An efficient method for the synthesis of moraprenyl bromide by the reaction of moraprenol (WT₃C_6—8—OH), the polyprenol from the mulberry tree Morus alba leaves, with bromo-trimethylsilane has been elaborated.     

Physical states and properties of barium titanate films in a plane electric field

The influence of a plane electric field on the phase states of barium titanate thin films under the conditions of forced deformation has been studied. The field dependence of a complete set of material constants has been taken in the region of the c-phase, where polarization losses are absent. The material constants are calculated using equations of the piezoelectric effect derived by linearizing the nonlinear equations of state from the phenomenological; theory for barium titanate. It has been shown that there is a critical value of the field at which the electromechanical coupling coefficient reaches a maximum.     

Physical properties of Ba<Subscript>0.8</Subscript>Sr<Subscript>0.2</Subscript>TiO<Subscript>3</Subscript> thin films

The behavior of material constants in ferroelectric Ba_0.8Sr_0.2TiO₃ thin films is studied depending on the misfit strain at room temperature in the context of nonlinear thermodynamic potential of the phenomenological theory. Some constants are found to undergo drastic changes with the alternating strain at the interfaces. The gathered results allow one to evaluate the material constants for a specific film and to outline the direction in searching the ways to synthesize films with the needed properties.     

On the problem of analyzing the dynamic properties of a layered half-space

An efficient method is developed for constructing the Green matrix functions of a layered inhomogeneous half-space. Matrix formulas convenient for programming are proposed, which make it possible to study the properties of a multilayered half-space with high accuracy. As an example of the problem of oscillations of a three-layer half-space, transformation of the dispersion characteristics of a three-layered medium is shown as a function of the relations of the mechanical and geometric parameters of its components. Study of the properties of the Green’s function of a medium with a low-velocity layered inclusion showed that each mode of a surface wave exists in a limited frequency range: in addition to the critical frequency of mode occurrence, the frequency of its disappearance exists—a frequency above which the mode is suppressed because of superposition of the zero of the Green’s function on its pole. A similar study conducted for a medium with a high-velocity layered inclusion has shown that in addition to the cutoff frequency (the frequency at which a surface wave propagating in the low-frequency range disappears), there is the frequency of its recurrent generation—the upper boundary of the “cutoff range” of the first mode. Beyond this range, the first mode propagates, and also the other propagating modes can appear. The critical relation of the geometric parameters of the medium determining the existence and boundaries of the cutoff range of a wave is established.     

Material constants of (Ba,Sr)TiO3 solid solutions

The phenomenological theory of solid solution is used to calculate the material constants (elastic compliances, susceptibilities, piezoelectric moduli, pyroelectric constants) of Ba _x Sr_{1 ? x} TiO₃ solid solutions over the entire range of concentrations x at room temperature. The phenomenological potential constants and the numerical values of the material constants are given for specific concentrations.