Search

We discuss the influence of hydrophysical and biological-chemical processes on the distribution of dissolved oxygen in waters of the Sevastopol bay in various seasons. In the winter period, against the background of low rates of biological-chemical processes, the hydrophysical processes provide the homogeneous distributions of temperature and oxygen. In summer, the hydrophysical processes remain dominant, but the influence of biological-chemical processes becomes noticeable. In the autumn period, the vertical distribution of oxygen is strongly affected by biological-chemical processes.

The laws of modification of the microstructure of a copper contact wire, its strength, and the acoustic parameters are investigated as functions of the heating temperature. The acous- tic and strength characteristics of samples of wires subjected to various loads are compared.

The possibilities of using the energy dispersion synchrotron radiation X-ray fluorescence analysis (SRXFA) for control of blood plasma and liver trace element (TE) content in rats with hyperproduction of oxygen radicals and hair TE content in women with mammary hyperplasia and cancer are demonstrated. Our data show that activity of antioxidant enzymes superoxide dismutase (SOD) and catalase in the blood and liver depends on the amount of TE incorporated into the structure of the active center of these enzymes, which are responsible for antioxidant protection. A decrease of activity of these enzymes is accompanied by an increase of production of free OH radicals in the tissues. Clinical data demonstrated that scalp hair of patients with oncological mammary pathology was characterized by a significant decrease of concentrations of selenium (Se) and zinc (Zn) and by an increase of chromium (Cr). The Se deficit was more pronounced in patients with cancer than in those with mammary hyperplasia ( p The SRXFA method permits one to carry out a controllable correction of TE imbalance in many diseases whose development is caused by oxygen radical injury.

We analyse the distribution of the dissolved forms of cadmium, lead, cobalt, copper, and manganese in the near-Danube part of the Black Sea and in a section made at 45° 10′N in the autumn of 1997. It is shown that the discharge of rivers results in the appearance of significant amounts of cadmium, lead, cobalt, copper, and manganese in the near-Danube region. Copper is the most labile element in this collection of metals. Its behaviour is correlated with the vital activity of diatomic algae. The distribution of dissolved manganese in the near-bottom region is correlated with the distribution of O2. Indeed, the elevated concentrations of manganese are observed in the regions with low concentrations of oxygen.

1. The possibility of preparing low-molecular-weight ethers from silanediols and alcohols was established, and four compounds were synthesized: dibutoxymethyl-1-naphthylsilane (I), 1,3-dibutoxy-1,3-dimethyl-1,3-di-1-naphthyldisiloxane (II), l,5-dibutoxy-l,3,5-trimethyl-1,3,5-tri-1-naphthyltrisiloxane (III), and 7-butoxy-1,3,5,7-tetramethyl-1,3,5,7-tetra-1-naphthyl-1-tetrasiloxanol (IV). 2. The use of a vacuum in the synthesis of dibutoxymethyl-1-naphthylsilane from dichloromethyl-1-naphthylsilane and butyl alcohol has a substantial effect on the yield of this compound.

1. With a content in the steel of more than 0.08% residual aluminum the ductility at 900–1250°C is poorer and the tendency toward embrittlement at temperatures below 20°C increases. 2. An increase in the aluminum content aids in the formation in hardened steel of M2N nitrides and after tempering at 800°C of A1N phase. A drop in the ductility and toughness, especially at low temperatures, is caused primarily by the precipitation of nitride phases. 3. Calcium in a calculated quantity of 0.1–0.15% increases the ductility of the steel at hot working temperatures and does not influence the mechanical properties from 20 to −253°C. 4. An increase in the silicon content in the steel over 0.45% causes the appearance after heating to 1250–1350°C of a eutectic with an increased content of silicon and manganese. Heating after working should not exceed 1250°C. 5. To provide statisfactory production conditions for the investigated steel in hot working in combination with sufficiently high strength and ductility from 20 to −253°C the aluminum content in the steel should not exceed 0.06% and that of silicon 0.4%. For final deoxidation it is desirable to use calcium equal to 0.1–0.15% of the weight of the steel.

The authors have investigated the hot-gas desorption of hydrocarbons from NaX zeolites after the dearomatization of liquid paraffins. As the feed they used paraffins from a 190-260/sup 0/C cut, recovered by adsorption on zeolites, with an aromatic hydrocarbon content of 1% by weight. The adsorbent was an NaX zeolite produced by the Salavat Petrochemical Combine. The studies were performed in adsorption-desorption units of the flow type. In the adsorption stage, the feed, in the liquid phase, passed through the zeolite bed from bottom to top. In the desorption, the gas flow (hydrogen, nitrogen) entered the adsorber at the top. They investigated the kinetics of hydrocarbon removal from the zeolite in desorption, and also the dependence of the dynamic activity of the zeolite on the temperature of hot-gas desorption.

1. When potassium chloropalladoate is reacted with anilium chloranilate, in aqueous DMF, the chloranilic acid anion does not react. 2. As the reaction product we isolated a crystalline complex of composition PdCl2(NH2C6H5)2·2HCON-(CH3)2, whose structure was studied by the x-ray structure analysis method.