Orientated crystallization in drawn thermoplastic polyimide modified by carbon nanofibers

The solid state crystallization in drawn thermoplastic polyimide films is studied as a function of draw ratio (DR) under the effect of vapor grown carbon fiber nanoinclusions. The nucleating effect of the nanoinclusions coupled with the orientation effect of drawing generates a unique orientated layered lamellar structure, characteristic of smectic‐like mesophase. The degree of draw induced orientated crystallization increases with the content of nanoinclusions and with the DR, and is reflected in the mechanical behavior of the film. Generally, the Young's modulus and the yield point of the drawn crystalline films in the drawing direction are significantly higher compared with the noncrystalline counterparts. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

Decomposition of aluminum oxynitride compounds in an air-vapor medium at 950°C

Aluminum oxynitride hydrolysis in wet air at a temperature of 950°C has been shown to lead to the formation of a phase whose composition lies beyond the Al₂O₃-AlN join in the Al-O-N system.     

Spinning front formation in fuel gas-air flame

The method of forming a spinning front of the flame in a propane-air mixture in a flat gap between two plates is proposed. It is shown that the spinning flame fronts (SFFs) are formed in gas mixtures with an excess fuel component and are due to the decay of an initial cylindrical front. It is established that the decay of a cylindrical front is related to the onset of a thermodiffusion instability, which is accompanied by the suppression of the majority of small perturbations on the flame surface and results in the development of only two of these perturbations. The subsequent evolution of the fields of temperatures, concentrations, and velocities in the vicinity of the leader points of developing perturbations results in the formation of an SFF, which resembles extended arc-shaped whiskers. Temporal variations in the angular and tangential velocities of SFF propagation are determined.     

Avian adenovirus induces ion channels in model bilayer lipid membranes

The action of duck egg drop syndrome 1976 (EDS-76) adenovirus on model bilayer lipid membranes (BLM) has been investigated on planar egg phosphatidylcholine membranes and small unilamellar vesicles. It was found that the adenovirus formed channels in planar BLM in a pH-dependent manner. The addition of EDS-76 to planar BLM at pH 5 induced voltage-independent channel activity of about 60 pS conductivity after a lag phase. At pH 3, EDS-76 induced irregular spikes of current across the planar BLM which disappeared after several minutes. The adenovirus also was able to induce pH-dependent leakage of calcein-loaded liposomes. EDS-76 did not induce channel activity in planar BLM or liposome leakage at neutral pH.     

The start gene CDC28 and the genetic stability of yeast

The cdc28-srm mutation in Saccharomyces cerevisiae decreases spontaneous and induced mitochondrial rho- mutability and the mitotic stability of native chromosomes and recombinant circular minichromosomes. The effects of cdc28-srm on the genetic stability of cells support the hypothesis that links cell cycle regulation in yeast to changes in chromatin organization dependent on the start gene CDC28 (Hayles and Nurse, 1986).     

Estimate of stiffness of the cellulose cuprammonium complex macromolecule in solution

Conclusions A tentative estimate of the stiffness (from the Kuhn segment) of the cuprammonium complex of cellulose (CCC) in solution has been given; it is about 200 A.The calculated concentration for transition of a CCC solution into the liquid-crystal state is in excess of 27% by wt.Translated from Khimicheskie Volokna, No. 3, pp. 23–24, May–June, 1988.     

Underground Nuclear Explosion Sites in Orenburg Oblast: Current Radiation Situation

The sites of underground nuclear explosions conducted in the Orenburg oblast (Magistral' and Sapfir objects) comprise local areas contaminated predominantly with ¹³⁷Cs, with contaminants spreading outside the fenced area. The radioactive contamination levels in soils, water, and locally produced agricultural foodstuffs in the nearest localities do not exceed the characteristic background level and the maximal permissible concentrations. The regional soils exhibit a high retention power with respect to the main contaminating radionuclide, ¹³⁷Cs, whose minor proportion occurs, however, in a mobile form.