The effect of dopants on the twist elastic constant and the rotational viscosity coefficient for nematics

The twist elastic constant, K2, and the rotational viscosity coefficient, γ1, are of importance when the response lime for the in-plane switching mode is studied. Since adding dopants is one technique to improve the response characteristics, the effect of dopants on these physical properties is significant. The effect on K2 and γ1 of adding alkyl(alkoxy) phenylcyclopentenones and alkyl(alkoxy) cyanobiphenyls to the base mixture ZLI-4792 together with their temperature dependence have been investigated using different temperature scales. The reduced temperature scale showed the effect of these dopants on K2 is small. On the other hand, the temperature dependence of γ1 depends on both the absolute temperature scale and the reduced temperature scale. Therefore, it is clear that the choice of temperature scale with which to compare γ1 for different systems raises fundamental questions which way not have a unique answer. 2000 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint.

Year-round and rotational freshwater prawn, Macrobrachium rosenbergii and paddy farming: soil quality, production and economics

A study was carried out at five upazillas (Dumuria, Fakirhat, Pirojpur sadar, Gopalgonj sadar and Kalia) of five southern districts of Khulna, Bagerhat, Pirojpur, Gopalgonj and Narail to understand the comparative production performance and any effect on soil quality in case of year-round golda (Macrobrachium rosenbergii), alternate prawn-paddy and year-round paddy farming. A direct interview of 55 farmers was taken, using pretested questionnaire, and soil samples were taken from selected farms before and after each crop. Among the five upazillas, farmers in Gopalgonj sadar and Kalia are not practicing year-round golda. Rotational golda-paddy farming has been recorded to result in maximum profit, with the highest of Tk. 310,912/ha/year in 2003 at Dumuria. Only paddy farming is less profitable than other two cropping patterns, irrespective of study sites. The nutrient status of soil in rotational golda and paddy farming has been found improved, compared to that of only golda or paddy farming.

Chiral symmetry analysis and rigid rotational invariance for the lattice dynamics of single-wall carbon nanotubes

We provide a detailed expression of the vibrational potential for the lattice dynamics of single-wall carbon nanotubes (SWCNT's) satisfying the requirements of the exact rigid translational as well as rotational symmetries, which is a nontrivial generalization of the valence force model for the planar graphene sheet. With the model, the low-frequency behavior of the dispersion of the acoustic modes as well as the flexure mode can be precisely calculated. Based upon a comprehensive chiral symmetry analysis, the calculated mode frequencies (including all the Raman- and infrared-active modes), velocities of acoustic modes, and the polarization vectors are systematically fitted in terms of the chiral angle and radius, where the restrictions of various symmetry operations of SWCNT's are fulfilled.

Properties of the rotational bands in the transitional nucleus 189Pt

High-spin states in 189Pt have been studied experimentally using the 176Yb(18O,5n) reaction at beam energies of 88 and 95 MeV. The level scheme of189Pt has been revised significantly and extended to high-spin states.Rotational bands have been analyzed in the framework of triaxial particle-rotor model, and a γ ≈−30◦triaxial shape and a near-prolate shape have been proposed to the νi−113/2 and νf5/2(p3/2) bands, respectively. Two ΔI = 2 transition sequences with similar energies have been observed, and they have been proposed to be associated with the νi−213/2νf5/2(p3/2) configuration. The structure built on the νi−213/2νf5/2(p3/2) configuration could be interpreted theoretical calculations of the triaxial particle-rotor model if a near-oblate shape is assumed.