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.     

Plasma Deposition and Properties of Silicon Carbonitride Films

A variety of advanced analytical techniques were used to characterize silicon carbonitride films grown from new volatile nitrogen-rich silyl derivatives of asymmetrical dimethylhydrazine: (CH₃)₂HSiNHN(CH₃)₂ (DMDMSH) and Me₂Si(NHNMe₂)₂ (bisDMHDMS). The results demonstrate that the films contain only Si-C, Si-N, and C(sp ³)-N bonds, in relative amounts that depend on the molecular structure of the precursor and deposition conditions. The Si-C/[Si-N + C(sp ³)-N] ratio is considerably larger in the films grown from DMDMSH. The data obtained by a variety of spectroscopic techniques provide solid evidence that some of the films contain C(sp ³)-N bonds, characteristic of superhard materials, and that the films have a complex, framework structure, rather than being a mixture of Si₃N₄, SiC, and C₃N₄. The structure of the films depends on the N : Si ratio in the precursor: at N : Si = 2, the films are amorphous and contain nanocrystalline inclusions with a tetragonal structure; at N : Si = 4, the films are purely amorphous. The ability to control the chemical composition and structure of deposits allowed us to produce films with various physicochemical and electrical properties.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 7, 2005, pp. 808–815.Original Russian Text Copyright © 2005 by Smirnova, Badalyan, Borisov, Kaichev, Bakhturova, Kichai, Rakhlin, Shainyan.     

Delayed effects of chronic low-dose high linear energy transfer (LET) radiation on mice in vivo

In the present work, the delayed effects of chronic high linear energy transfer (LET) radiation in polychromatic erythrocytes (PCEs) of mice bone marrow were investigated in vivo. Irradiation of the two-month-old SHK white mongrel random-bred male mice was performed in the radiation field behind the concrete shield of the accelerator of 70 GeV protons to accumulate doses of 0.005-0.16 Gy. The dependence of the biological response on dose, adaptive response (AR) and genomic instability (GI) in F(1) and F(2) generations from males irradiated with doses of 0.005 and 0.16 Gy and from males exposed to combined action of immunomodulator-bendazol hydrochloride (BH) and of 0.16 Gy irradiation, were examined using the micronucleus formation test. The data demonstrated that irradiation of mice with these doses lead to an increase in the level of cytogenetic damage and induces no AR. With analysis of the bone marrow radiosensitivity to 1.5 Gy of X rays and the capacity to AR it was found that the chronic high-LET irradiation of parents induced the GI at least two generations. The combined exposure to BH and the dose of 0.16 Gy induces no AR in F(0) generation but induces AR in F(1) and F(2) offspring.     

Defect structure of Cd<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Hg<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Te films grown by liquid-phase epitaxy,studied by means of low-energy ion treatment

Treatment with low-energy ions and measurements of electrical parameters of samples have been used to study the defect structure of Cd _x Hg_{1 − x} Te films grown by liquid-phase epitaxy. The films contain neutral defects supposedly associated with tellurium nanoinclusions. Ion treatment electrically activates these defects, with a high concentration of donor centers (∼10¹⁷ cm⁻³) created in the films. These defects decompose in ∼10³ min of aging at room temperature. Then the properties of the material are determined by the concentration of residual donors, which is found to be very low (down to ∼10¹⁴ cm⁻³) for the films under study.     

Low-temperature investigations of chemically deposited films of substitutional solid solutions based on lead and tin (II) selenides

Photoelectric characteristics of films of the Pb_0.902Sn_0.098Se solid solution based on the four-layer (SnSe-PbSe)₂ composition obtained by layer-by-layer hydrochemical synthesis with subsequent heat treatment in air within the temperature range 523–700 K are investigated. The measurements are performed in the temperature range 220–300 K. The thermal and optical band gaps, temperature coefficient of the optical band gap, dark resistance, volt-watt sensitivity, and spectral characteristics are determined. It is established that, at heat treatment temperatures below 573 K, the conductivity of the four-layer (SnSe-PbSe)₂ compositions is characteristic of metals, while at higher temperatures, it is characteristic of p-type semiconductors.     

有限精度时间自动机的可达性检测

为了缓解状态空间爆炸问题,减小模型检测过程中生成的状态空间,加快模型检测速度,引入有限精度时间自动机(finite precision timed automata,简称FPTA)作为实时系统的形式模型,并提出了一种数据结构SDS(series of delay sequence)符号化表示状态空间中的状态集.FPTA只记录时钟变量的整数值及时钟变化的先后次序,从而减小生成的状态空间.在一定的时间约束下,Alur与Dill提出的时间自动机的可达性检测可简化为FPTA的可达性检测.举例描述了状态空间的生成过程和表示方法.最后,列出部分初步的实验结果,分析了SDS的特点及不足.