Strength and working parameters of covers with rubber-cord casings of different designs

A method is proposed for calculating the basic structural parameters, operational characteristics, and strength of covers with rubber-cord casings. The method may be used in developing new designs for temporary covers of petroleum pipelines and covers for sewage and heating pipes.     

An analysis of the equilibrium configurations of charged cylindrical jets of a conducting liquid

A region of physical parameters is found where the equilibrium configurations of charged cylindrical jets of a conducting liquid can exist; these configurations correspond to the azimuthal mode n=2 of the surface deformations of a round jet. A critical value of the jet linear charge is determined for which the jet splits into two. It is shown that such instability is excited in a soft regime.     

Structural Modifications to Polystyrene via Self‐Assembling Molecules

We have previously reported that small quantities of self‐assembling molecules known as dendron rodcoils (DRCs) can be used as supramolecular additives to modify the properties of polystyrene (PS). These molecules spontaneously assemble into supramolecular nanoribbons that can be incorporated into bulk PS in such a way that the orientation of the polymer is significantly enhanced when mechanically drawn above the glass‐transition temperature. In the current study, we more closely evaluate the structural role of the DRC nanoribbons in PS by investigating the mechanical properties and deformation microstructures of polymers modified by self‐assembly. In comparision to PS homopolymer, PS containing small amounts (≤ 1.0 wt.‐%) of self‐assembling DRC molecules exhibit greater Charpy impact strengths in double‐notch four‐point bending and significantly greater elongations to failure in uniaxial tension at 250 % prestrain. Although the DRC‐modified polymer shows significantly smaller elongations to failure at 1000 % prestrain, both low‐ and high‐prestrain specimens maintain tensile strengths that are comparable to those of the homopolymer. The improved toughness and ductility of DRC‐modified PS appears to be related to the increased stress whitening and craze density that was observed near fracture surfaces. However, the mechanism by which the self‐assembling DRC molecules toughen PS is different from that of conventional additives. These molecules assemble into supramolecular nanoribbons that enhance polymer orientation, which in turn modifies crazing patterns and improves impact strength and ductility.     

中国沙棘乙醇提取物的体外及对HepG2细胞的抗氧化活性

本文从生化角度全面分析了中国沙棘乙醇提取物的体外抗氧化活性,并在评价细胞毒性的基础上,以Hep G2细胞为模型,利用流式细胞仪评估了提取物的细胞抗氧化能力。结果表明,中国沙棘乙醇提取物对ABTS自由基具有良好的清除效果,当浓度为5 mg/m L时,其清除能力与阳性对照BHT相当;中国沙棘乙醇提取物对NO自由基也有良好的清除效果,但其整体清除能力不及BHT;当浓度为5 mg/m L时,中国沙棘乙醇提取物对亚油酸脂质过氧化表现抑制,但其抑制效果低于BHT;中国沙棘乙醇提取物的总抗氧化能力随浓度的增大而增强,当浓度为5 mg/m L时,其总抗氧化能力与同浓度下的BHT接近。在浓度为0.05~5 mg/m L范围内,中国沙棘乙醇提取物对Hep G2细胞不显示毒性;当处理浓度为0.5、1、5 mg/m L时,中国沙棘乙醇提取物的阳性细胞率与阳性对照相比分别降低了75.22%、72.36%和78.2%。中国沙棘乙醇提取物不仅在体外条件下具有良好的抗氧化活性,而且在Hep G2细胞内表现出良好的抗氧化能力。      

γ-X-ray-spectrometric investigation of plutonium and241Am content in the soil in regions where peaceful nuclear explosions were conducted

A brief exposition of the γ-x-ray spectrometric method and apparatus for analyzing the content of plutonium and²⁴¹Am in samples of soil and vegetation is presented. The results of an analysis of some samples from the regions where peaceful nuclear explosions were conducted in Yakutiya and Perm oblast' are presented. It is concluded that the γ-x-ray spectrometric method can be used to perform large-scale measurements in regions where peaceful nuclear explosions have been conducted, 2 figures, 3 tables, 8 references. Translated from Atomnaya énergiya, Vol. 88, No. 1, pp. 52–55, January, 2000.     

The effect of light entrainment observed in an optical disk interferometer

We observed a spatial effect of the light entrainment at a wavelength of λ=0.63299 μm by an optical disk with a radius of R ₀=0.06 m rotating at a frequency of ω=25 Hz. A relative shift of the interference pattern, monitored by the time of the interference band motion across the aperture of a photodetector for the disk rotating in the opposite directions, amounts to Δ=0.0094±0.0025 of the interference bandwidth.     

Peptide sequencing by partial acid hydrolysis and high resolution plasma desorption mass spectrometry

A method of deriving peptide sequence information using partial acid hydrolysis in combination with accurate mass measurements and immonium ion analysis provided by high-resolution plasma desorption mass spectrometry has been developed. The technique is very simple in terms of the chemistry and involves a short-time (3-30 min) incubation of the peptide in 1N-6N HCl at 100-110 degrees C with subsequent mass spectrometric analysis. Partial acid hydrolysis is found to produce sequence-specific segments, often ladder-like, although not always a complete set. Two application examples of the method are given: the linear peptide bradykinin and desmopressin, a peptide with an internal S-S bond and a non-amino-acid constituent. The technique has proved to be particularly useful in cases where some a priori information on the peptide structure was already known or where the automated Edman degradation technique might yield erratic results or not work at all.