IR Spectroscopic Investigation and Conformational Analysis of Unsaturated C<Superscript>20</Superscript> and C<Superscript>22</Superscript> Steroid Alcohols

With the IR-spectroscopy method and the quantum-chemical AM1 method, the Δ²² and Δ²³ steroids containing a hydroxyl group at C²⁰ or C²² have been studied in order to elucidate the mutual arrangement in space of the hydroxyl group and of the double bond in the side chain of the molecules. The conformational analysis of steroid alcohols has been performed and the population of their stable conformers has been calculated. The frequencies of the bands in the IR spectra of alcohols in the region of the stretching vibration of OH groups have been assigned to certain conformers and the possibility of formation of the intramolecular hydrogen bond of the OH groups with the π-electron cloud of C=C bonds has been analyzed. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 3, pp. 317–324, May–June, 2005.     

Circular Sandwich Plates under Local Impulsive Loads

The axisymmetric transverse vibrations of a circular elastic sandwich plate under impulsive surface and linear loads are studied. To describe the kinematics of the asymmetric plate, the hypotheses of broken normal are adopted. The core is a lightweight material. Analytical solutions are obtained using Heaviside functions and Dirac delta-function. The solutions are analyzed numerically     

X-ray structure and vibrational spectroscopy of a cobalt(II) complex prepared with excess of 4-hydroxybenzhydrazide

A new cobalt(II) complex was obtained from CH₃OH/H₂O solution containing CoSO₄ and 4-hydroxybenzhydrazide (4hbah) in 1?:?3 molar ratio. The crystals are composed of polymer chains [Co(4hbah)₂(μ-SO₄)] _n accompanied by lattice H₂O and CH₃OH forming the 3-D network. The CH₃OH molecules are highly disordered. For the assignment of IR and Raman spectra, the O,N-deuterated compound was prepared and DFT calculations were carried out.     

Ground‐State Chemical Reactivity under Vibrational Coupling to the Vacuum Electromagnetic Field

The ground‐state deprotection of a simple alkynylsilane is studied under vibrational strong coupling to the zero‐point fluctuations, or vacuum electromagnetic field, of a resonant IR microfluidic cavity. The reaction rate decreased by a factor of up to 5.5 when the Si?C vibrational stretching modes of the reactant were strongly coupled. The relative change in the reaction rate under strong coupling depends on the Rabi splitting energy. Product analysis by GC‐MS confirmed the kinetic results. Temperature dependence shows that the activation enthalpy and entropy change significantly, suggesting that the transition state is modified from an associative to a dissociative type. These findings show that vibrational strong coupling provides a powerful approach for modifying and controlling chemical landscapes and for understanding reaction mechanisms.     

Green functions for a compressible linearly non homogeneous half-space

Summary The paper presents a study of time-harmonic vibration of a half-space possessing a shear modulus linearly increasing with depth. Completing the previous paper [1], where the time-harmonic vibration of an incompressible half-space has been considered, the problem is now solved for a compressible as well as an incompressible material. The half-space is subjected to a vertical or horizontal surface load. The solution is represented in terms of Fourier-Bessel integrals containing functions of depth coordinate that are expressed through confluent hypergeometric functions. Numerical results concerning surface displacements due to a point force are given for a wide range of frequency variations and degree of non-homogeneity. The results show that, as compared to the homogeneous case, non-homogeneity can considerably increase vibration amplitudes at large distances from the applied force. Received 19 August 1996; accepted for publication 16, December 1996     

Effect of High-Frequency Vibration on Convection in Miscible Fluids

The effect of high-frequency vibrations of the field of external mass forces on convection in miscible fluids is considered for a system of convection equations obtained by an averaging technique. The structures of flows formed under initial conditions corresponding to physical experiments in microgravity are examined. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 2, pp. 49–59, March–April, 2006.     

Motion types and chaos of multi-body systems vibrating with impacts

In this paper, the limit sets theory for an autonomous dynamical system is generalized to a multi-body system vibrating with impacts. We discover that if every motion of the system is bounded, it has only four different types: periodic motion γ1, non·periodic recurrent motion γ2, and non-Poisson stable motions γ3 and γ4 approaching γ1 and γ2, respectively. γ2 is the source of chaos. It is very interesting that chaotic motions seem stochastic but possess the character of recurrence. By way of example, we discuss chaotic motions of a small ball bouncing vertically on a massive vibrating table. The result obtained by us is different from that obtained by Holmes. The project supported by National Natural Science Foundation of China     

Flexural Vibrations and Heating of a Circular Bimorph Piezoplate under Electric Excitation Applied to Nonuniformly Electroded Surfaces

The flexural vibrations and dissipative heating of a circular bimorph piezoceramic plate are studied. The plate is excited by a harmonic electric field applied to nonuniformly electroded surfaces. The viscoelastic behavior of piezoceramics is described in terms of temperature-dependent complex moduli. The nonlinear coupled problem of thermoviscoelasticity is solved by step-by-step integration in time, using the discrete-orthogonalization method to solve the mechanics equations and the finite-differences method to solve the heat-conduction equations. A numerical analysis is conducted for TsTStBS-2 piezoceramics to study the influence of the nonuniform electroding on the resonant frequency, amplitude, and modes of flexural vibrations and the amplitude- and temperature-frequency characteristics of the plate __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 9, pp. 94–100, September 2005.     

Energy Pumping with Various Nonlinear Structures: Numerical Evidences

Numerical investigations are carried out on a linear structure, weakly coupled to a small nonlinear attachment. The essential nonlinearity of the attachment enables it to resonate with any of the linearized modes of the structure leading to energy pumping, i.e. passive, one-way, irreversible transfer of energy from the structure to the attachment. Different nonlinear structures (piecewise linear system, chaotic system) and efficiency of energy pumping are studied in each case in order to be able to apply it to civil engineering. As a specific application, attenuation of vibrations of a building is studied with two building models. In particular, the case of stochastic excitations is analyzed to examine if it is possible to process energy pumping when a seism occurs and an indicator of efficiency has been introduced.     

Resonant Vibrations and Dissipative Heating of an Infinite Piezoceramic Cylinder

The monoharmonic radial vibrations and dissipative heating of an infinite hollow piezoceramic cylinder are studied in dynamic formulation, taking into account the temperature dependence of the complex electromechanical characteristics over a wide range of temperatures, including depolarization temperatures. The influence of the heat exchange conditions, the level of electric load, and geometry on the thermoelectromechanical characteristics is studied in the case of forced vibrations at the first resonance__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 3, pp. 101–107, March 2005.