Dielectric studies of the 4-n-alkyl-4'-thiocyanatobiphenyl (nBT) homologous series (n=2-10) in the isotropic and E phases

Results of the dielectric studies of nine members of the nBT (4-n-alkyl-4'-thiocyanatobiphenyl, n= 2-10) homologous series in the crystal E (E) and isotropic (I) phases are presented. The dependence of the static permittivity ?_s in the isotropic phase, the longitudinal relaxation times τ_is and τ_∥, and the activation enthalpies ΔH _is and ΔH _∥ on the number of carbon atoms in the alkyl chain n are analysed. A considerable increase in the retardation factor g= τ_∥/τ_is with decreasing n is observed. The results are compared with those obtained for similar two-ring homologous series. The parameters characterizing the molecular rotations around the short axis in the E phase (τ_∥ and ΔH _∥) indicate a hardening of this solid-like phase with shortening of the alkyl chain.     

Phase diagram and dielectric relaxation studies of n-octyl-isothiocyanato-biphenyl (8BT) in the crystalline E phase under high pressure

The pressure-temperature phase diagram of n-octyl-isothiocyanato-biphenyl (8BT) in the pressure range up to 250 MPa (2.5 kbar) and the temperature range 250-400 K was established with the aid of DTA. At 1 atm the substance exhibits exclusively CrE polymorphism. At pressures above 190 MPa, the clearing line splits showing an additional phase which is not yet identified. Dielectric relaxation measurements on the CrE phase of 8BT were performed in the pressure range 0.1-120 MPa and the temperature range 304-345 K. A Debye-type relaxation process was observed in the frequency range 100 Hz-1 MHz. The longitudinal relaxation time τ, characterizing the molecular reorientations around the short axis, was analysed with respect to the pressure and temperature, yielding the activation volume, Δ^# V = RT(? ln τ/?p)_T, and activation enthalpy, Δ^# H = R(? ln τ/? T^-1)_p, respectively. The results are compared with analogous data obtained recently for similar compounds having other liquid crystalline phases (N, SmA).     

Dye distribution in fluorescent-labeled latex prepared by emulsion polymerization

Emulsion polymerizations were used for preparing fluorescent-labeled polymers. The labeled polymers were analyzed by gel permeation chromatography (GPC) using both fluorescence (FL) and refractive index (RI) as detectors. The uniformity of polymer labeling was measured by the ratio between FL and RI signals, calculated by a computer software, on the basis of each GPC chromatogram. It was found that in emulsion polymerizations, the semicontinuous process can produce a more homogenous dye distribution in the host polymer molecules than the batch method. Uniform labeling of a polymer with various dyes can be achieved by the semi-continuous process. However, experimental conditions for polymerization, such as initiator concentration and the presence of surfactant or chain transfer agent, may influence the uniformity of dye distribution. © 1994 John Wiley & Sons, Inc.     

Lipids of the leaves of Brassica oleracea

The composition of the various groups of liposoluble compounds in the leaves of wild cabbage of early-, middle-, and late-ripening varieties have been identified and their amounts have been determined by chromatographic and chemical methods. About 30 groups of lipid substances have been identified, among which free and esterified forms of sterols, di- and triacylglycerols, hydrocarbons, lipoquinones, mono- and digalactoside glycerides, cerebrosides, phosphatidylethanolamines, phosphatidylglycerols, and phosphatidylcholines predominate. The presence of 13 components has been established among the fatty acids, linolenic acid being present in the greatest amount (50%). The influence of the time of ripening of the cabbage variety (early-, middle-, or late-ripening) on the composition of the lipid complex has been elucidated.M. V. Lomonosov Technological Institute of the Food Industry, Odessa. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 180–185, March–April, 1989.     

4-Hydroxy-2-quinolones 113. Synthesis and antitubercular activity of N-R-amides of 4-hydroxy-6-methyl-2-oxo-1-propyl-1,2,5,6,7,8-hexahydroquinoline-3-carboxylic acid

A preparative method has been developed and the synthesis has been effected of anilides and heterylamides of 4-hydroxy-6-methyl-2-oxo-1-propyl-1,2,5,6,7,8-hexahydroquinoline-3-carboxylic acid. A comparative analysis has been carried out of the structure and antitubercular properties of the synthesized compounds and their analogs unsubstituted in the quinoline nucleus. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 405–414, March, 2007.     

CO2 gasification of char from spent mushroom substrate in TG-MS system

Journal of Thermal Analysis and Calorimetry - Gasification of the char obtained from the spent substrate after mushroom cultivation was carried out in a thermobalance connected to a mass...     

Recursive intermediate factorization and complete computational linearization of the coupled-cluster single,double, triple,and quadruple excitation equations

Summary The nonlinear CCSDTQ equations are written in a fully linearized form, via the introduction of computationally convenient intermediates. An efficient formulation of the coupled cluster method is proposed. Due to a recursive method for the calculation of intermediates, all computational steps involve the multiplication of an intermediate with aT vertex. This property makes it possible to express the CC equations exclusively in terms of matrix products which can be directly transformed into a highly vectorized program.This work has been supported by the U.S. Air Force Office of Scientific Research, Grant No. 90-0079