Unsteady flow around models in an electromagnetic shock tube

Results of experimental studies of the unsteady flow around models of a stream moving behind the front of a very strong shock wave excited in an electromagnetic shock tube are presented. The flow establishment time in the stagnation-point region of blunt bodies is found.     

Wave motions in viscoelastic tubes. Forced oscillations

A characteristic of small blood and lymphatic vessels is the capacity of the wall to change its rheological properties and lumen by active contraction of the annular muscle cells contained in it [1–3]. A model of flow in the vessels taking this feature into account has been proposed in [4, 5], where a linear stability analysis is also given. A consequence of wall activity is the existence of auto-oscillatory flow conditions [6–8], which have also been discovered in the numerical solutions of the corresponding problems [9, 10]. Up to the present time flows have only been studied under steady conditions at the ends of the vessel and in the environment. The wall of an actual blood vessel is subject to various actions, frequently of a periodic nature: pressure pulsations at entry and rhythmically changing external forces applied from the surrounding tissues. Data exist on the sensitivity of vessels to transient actions [11–13], in particular on the relationship of their hydraulic resistance to frequency and amplitude of the action. There has been frequent discussion of the hypothesis that bv contraction of muscles in its walls or by external compression the vessel can act as a valveless pump [14, 15]. Within the framework of the quasione-dimensional approximation given below [4] the movement of liquid along a viscoelastic tube in the presence of small amplitude periodic external actions has been studied. A general solution of the problem has been constructed and concrete examples are given illustrating the features of forced wave motions in a tube having passive and active properties.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No, 4, pp. 94–99, July–August, 1984.     

Structure of nanocomposites based on lead sulfide and poly-<Emphasis Type="Italic">p</Emphasis>-xylylene

Nanocomposites containing controlled (in the course of synthesis) concentrations of lead sulfide nanoparticles dispersed in the polymer matrix were prepared by the method of gas-phase polymerization on the surface of an active monomer, paracyclophane, which was codeposited with lead sulfide molecules. According to wide-angle X-ray diffraction measurements, the prepared nanocomposites contain lead sulfide clusters of 4 nm size, which are localized in the amorphous regions of poly-p-xylylene. Size distribution curves for lead sulfide particles as calculated on the basis of the Fourier analysis of crystallographic X-ray reflections and the volume distributions functions of particles as determined from small-angle X-ray scattering data are reported. A mechanism for the formation of lead sulfide nanoparticles in the poly-p-xylylene matrix is proposed on the basis of analysis of the X-ray scattering curves.     

Discovery of New Ginsenol-Like Compounds with High Antiviral Activity

A number of framework amides with a ginsenol backbone have been synthesized using the Ritter reaction. We named the acetamide as Ginsamide. A method was developed for the synthesis of the corresponding amine and thioacetamide. The new compounds revealed a high activity against H1N1 influenza, which was confirmed using an animal model. Biological experiments were performed to determine the mechanism of action of the new agents, a ginsamide-resistant strain of influenza virus was obtained, and the pathogenicity of the resistant strain and the control strain was studied. It was shown that the emergence of resistance to Ginsamide was accompanied by a reduction in the pathogenicity of the influenza virus.     

Adamantylation of N-aryl and N-arylalkyl acetamides in trifluoroacetic acid

Russian Chemical Bulletin - Alkylation of N-aryl and N-arylalkyl acetamides with hydroxy adamantane derivatives in trifluoroacetic acid was studied. The differentiating effect of trifluoroacetic...     

Quantification of the hygroscopic effect of soot aging in the atmosphere: laboratory simulations

We use a laboratory approach for the quantification of the water uptake by particles with varying amounts of sulfates to simulate the aging of fossil fuel combustion particles in the atmosphere. Diesel fuel and aviation kerosene laboratory-made soots are chosen as representative of the hydrophobic fraction of diesel and aircraft engine-emitted particulates and commercial carbon blacks are used as surrogates for industry emissions. The transformation of soot hydration properties from hydrophobic, through hydrophilic, to hygroscopic is demonstrated based on the amount of water uptake by the laboratory-produced EC soot covered by sulfates as the amount of sulfate increases. The mechanism of water/soot interaction changes from an adsorption on active sites to a water film formation and to the dissolution of water into the water-soluble sulfate, while the amount of sulfate increases. Laboratory simulations show that coverage of EC soot by organics diminishes the effect of sulfuric acid deposition. We demonstrate that the surface chemical properties and the size of primary particles affect the amount of water taken up by the soot particles and their aging in the atmosphere.     

Synthesis of unsaturated esters of pyridine-and quinolinecarboxylic acids

The vinyl esters of pyridine-2-and -4-carboxylic acids, the propargyl esters of pyridine-2-, -3-, and-4-carboxylic acids, the vinyl, allyl, and propargyl esters of quinoline-2-, -4-, and -8-carboxylic acids, and the allyl ester of 2-methylisonicotinic acid have been synthesized.