Phase liquid-crystalline transitions in hydroxypropylcellulose-ethanol and hydroxypropylcellulose-acetic acid systems under deformation

The phase transitions and phase state of hydroxypropylcellulose mixtures with ethanol and acetic acid under static conditions and in the shear field have been studied by the turbidity-point method and polarization microscopy with the use of a polarization-photoelectric setup and a modified plastoviscometer. The deformation of solutions leads to a decrease in the temperature of mesomorphic phase formation and to a change in the type of liquid crystals from cholesteric to nematic.     

Structural-morphological and biological properties of selenium nanoparticles stabilized by bovine serum albumin

Nanostructures formed during the reduction of ionic selenium in the selenite-ascorbate redox system in an aqueous solution of bovine serum albumin (BSA) were studied using static and dynamic light scattering and flow birefringence. It was established that this process results in the formation of stable aggregates of selenium nanoparticles that adsorb BSA molecules. It was found that highly-ordered superhigh-molecular-weight spherical nanostructures with high density and unique morphology are formed. Experiments with a cell culture of promyelocytic leukemia HL-60 showed that BSA adsorbed on selenium nanoparticles can inhibit the growth of tumor cells and deactivate free radicals with an efficiency comparable with that of sodium selenite.     

Champ de vitesse dans un échangeur à vortex en régime turbulentHeat exchanger velocity field with turbulent inlet condition

We consider the isothermal flow through a cylindrical flat chamber, a model of some particular heat exchanger, for which LDV measurements and a numerical simulation have been performed. Experimental results show the establishment of an important vortex zone, the secondary flow extending all along the chamber radius. This observation leads to an expected significant increase of the fluid mixing. Results issued from the numerical simulation appear to be in close agreement with experimental data. Nevertheless, the k–ε model used here must be improved to obtain a better approach near the vortex centre. To cite this article: S. Petitot et al., C. R. Mecanique 330 (2002) 593–599.     

Complex backflow dynamics in nematic liquid crystals

Received December 31, 2001 / Published online May 21, 2002     

Sortability of Multi-partitions

Recently, the theory of sortability of partition property has been shown to be an effective tool to prove the existence of an optimal partition with that property. In this paper, we extend the theory to multi-partition where the partition is on t types of components. We apply our results to settle an optimal assignment problem whose proof was incomplete as given in the literature.     

A new monitoring system of cultured myocardial cell motion: effect of pilose antler extract and cardioactive agents on spontaneous beating of myocardial cell sheets

Effects of various cardioactive agents and a water extract of the pilose antler of Cervus nippon var. mantchuricus on periodic beating of cultured myocardial cell sheets were examined by using an image analyzing system. Norepinephrine increased the beating rate and the beating amplitude, whereas digoxin and forskolin enlarged only the beating amplitude. Verapamil and propranolol decreased both the beating rate and the beating amplitude. The water extract of the pilose antler showed no remarkable effects in a standard medium (2.1 mM Ca2+). However, it significantly increased the beating amplitude when the beating was suppressed by replacement with a low calcium medium (0.5 mM Ca2+). A similar effect was found for 70% ethanol-soluble and -insoluble fractions of the extract.     

Synthesis and structure-activity relationships of N-substituted 2-[(2-imidazolylsulfinyl)methyl]anilines as a new class of gastric H+/K(+)-ATPase inhibitors.

A series of N-substituted 2-[(2-imidazolylsulfinyl)methyl]anilines (3) was synthesized and evaluated for its biological activity against gastric H+/K(+)-ATPase prepared from rabbit stomach and gastric acid secretions in Heidenhain pouch dogs. Monoalkyl substituents on the nitrogen atom of the aniline moiety markedly inhibited the enzyme activity to the same degree as omeprazole, a representative H+/K(+)-ATPase inhibitor. Most of these compounds, administered at 3 mg/kg i.v. inhibited histamine-stimulated gastric acid secretion. The inhibitory activity of these derivatives on the enzymes at pH 6.0 was more potent than that at pH 7.4, and was distinctly correlated to stability in aqueous solution at pH 5.0.