Some applications of the discrete fourier transform to problems of crystal lattice deformation II

The method elaborated in [1] is applied to the solution of some problems for a plane lattice and the linear chain. The method can be used to investigate deformations around crystal lattice defects.

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Some applications of the discrete fourier transform to problems of crystal lattice deformation I

The theory of the discrete Fourier transform [1], [2] is applied in solving a system of difference equations describing the positions of atoms in a deformed crystal lattice. The crystal lattice is approximated by the Born-Kármán model modified to include the internal energy of the undeformed crystal.

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Micron Particles of AlN/Al: Efficient,Novel, and Reusable Heterogeneous Catalyst for the Synthesis of Bis(indolyl)methanes

The present work introduces for the first time the catalytic utility of micron particulate aluminium nitride (AlN/Al) as a novel and reusable heterogeneous catalyst for the synthesis of bis(indolyl)methanes involving the electrophilic substitution of indoles on aldehydes. The catalyst is recyclable and works without any significant change in its catalytic activity.     

The first stereoselective synthesis of dendrodolide A

The first stereoselective total synthesis of natural product, dendrodolide A (1) is described from readily available (R)-propylene oxide and 3-buten-1-ol as starting materials. The synthesis was achieved in 10 steps with an overall yield of 19.1%. The key steps involved in the synthesis are Jacobsen hydrolytic kinetic resolution, epoxide ring opening with 2-allyl-1, 3-dithiane, Yamaguchi esterification, and ring-closing metathesis (RCM).     

Solidification of semicrystalline polymers using a variable interface temperature model

Solidification of semicrystalline materials often occurs in significantly undercooled melts. The crystal growth process in such melts is convoluted due to the fact that the interface between the solid and liquid domains of the microscopic crystals is at an unknown temperature. However, it is possible to let the temperature of this interface be unspecified and solve the problem with a semianalytical method if the growth velocity is prescribed. Solutions for the temperature profiles in both solid and liquid phases are presented in this work, along with the interface temperature, for phase change processes controlled by the kinetics of crystallization rather than diffusion processes, which is typical for polymers. The method is used for one-dimensional problems in cartesian, cylindrical, and spherical geometries that correspond to commonly found microstructures. It is found that the temperature of the interface is significantly below the equilibrium melting point and a quasi steady-state regime is reached rapidly. Comparison with the classical Neumann's solution shows that the temperature profiles are similar but the position of the interface differs considerably. © 1996 John Wiley & Sons, Inc.     

Extreme and critical transition events in the memristor based Liénard system

The European Physical Journal Special Topics - We study extreme and critical events in the forced Liénard systems with charge control memristor. It has been found that the system exhibits...     

Thermo emf studies on CdTe:Sb Thin Films

Thermal transport properties have been studied on as-grown and annealed CdTe:Sb thin films of different thicknesses and concentrations of Sb. These films were prepared by sequential vacuum deposition of CdTe and Sb on clean and hot glass substrates held at 210 °C temperature at a constant rate of deposition. From these studies all the films were found to be p-type. It is also observed that the thermoelectric power increases with Sb concentgration, thickness of the film and with annealing process. Fermi-energy variation with temperature have been calculated on the basis of thermo emf data. All these results have been explained on the basis of defects introduced by Sb doping.     

Electrical transport properties of CdTe:Sb films

Hall coefficient and dc conductivity measurements are made on p-type CdTe:Sb films grown by vacuum evaporation technique on glass substrate. The grain boundary potential barrier, which is found mainly to limit the mobility of carriers is calculated as a function of film thickness. The n-type conduction is found to dominate over p-type conduction above about 330 K. The ratio of electron to hole mobility is also calculated.     

Role of Impurity Precipitates on Microhardness of KBr:Ba2+ Crystals

Microhardness of KBr crystals doped with various concentration of Ba²⁺ have been investigated in the asgrown state and after quenching from various elevated temperatures. It is observed that hardness increases with increase in impurity concentration and at high concentration the hardness starts decreasing. Microstructural investigations have showed the formation of visible precipitates at high concentrations. The heat treatment studies showed that in crystals quenched from elevated temperatures the visible precipitates dissociate and hardness increases.     

Microhardness studies on some compound semiconductors

Vickers microhardness studies on some III–V and II–VI compound semiconductors have been made. The results showed that ZnS has the highest microhardness value. These results are compared with other properties of the crystals such as melting point, ionicity etc. Variation of microhardness with load was also studied on all the crystals. The results indicated that the hardness value increases at low loads. These results have been analysed by using resistance pressure model and interpreted.