<Emphasis Type="Italic">k</Emphasis>-Sum decomposition of strongly unimodular matrices

Networks are frequently studied algebraically through matrices. In this work, we show that networks may be studied in a more abstract level using results from the theory of matroids by establishing connections to networks by decomposition results of matroids. First, we present the implications of the decomposition of regular matroids to networks and related classes of matrices, and secondly we show that strongly unimodular matrices are closed under k-sums for \(k=1,2\) implying a decomposition into highly connected network-representing blocks, which are also shown to have a special structure.     

Metal Extracts as Precursors for the Production of Metal Powders and Coatings via the Extraction-Pyrolytic Method

The extraction of copper, silver, bismuth, and nickel with carboxylic acids thus providing concentrated metal-containing organic solutions and their crystalline salts has been studied. Micron- and submicron-sized metal powders have been obtained via reduction of these metals carboxylates by heating in benzyl alcohol or ethylene glycol. The synthesis of aspherical silver nanoparticles has been achieved by the reduction of a liquid extract of silver neodecanoate in benzyl alcohol. The possibility of the use of concentrated silver-containing solutions as inks for obtaining of electroconductive images has been demonstrated.     

Cyclic oligoesters as potential materials for polymer nanocomposite production

Publications dedicated to cyclic oligoesters based on cyclic butylene terephthalate were analyzed and summarized. The features of their preparation and structure and their properties were considered with a special focus on advantages and disadvantages of the methods of their preparation: polycondensation at high dilution and depolymerization. The prospects of application of cyclic butylene terephthalate for polymer nanocomposite production were demonstrated. A development strategy for this research area was suggested.

     

Low-Temperature Plasma-Chemical Deposition of Nanocomposite Antifriction Molybdenum Disulfide (Filler)–Silicon Oxide (Matrix) Coatings

It was demonstrated experimentally that the spatial separation of two processes of chemical vapor deposition, one of which provides synthesis of filler (MoS₂) nanoparticles and the other yields the matrix (SiO₂) of the nanocomposite coating, performed ina common reactor, enables an independent control over two process rates and makes it possible to widely vary the composition of the films deposited in this way. The deposition was performed in a double-zone vertical tubular quartz reactor. Molybdenum disulfide particles were produced by pyrolysis of aerosols of ammonium thiomolybdate solutions in dimethylformamide in the upper zone of the reactor, and the plasma-chemical deposition of a nanocomposite coating occurred in the lower zone into which MoS₂ nanoparticles were transported by the gas flow and tetraethoxysilane was delivered. It was shown that the nanocomposite coatings composed of molybdenum disulfide (filler) and silicon oxide (matrix) possess improve the antifriction properties as compared with the matrix (SiO₂ layers), these properties being determined by the relative amounts of MoS₂ nanoparticles in the layer and by their average size.     

Degradation of physicomechanical properties of epoxy nanocomposites with carbon nanotubes upon heat and humidity aging

The dependence of the physicomechanical properties of epoxy nanocomposites subjected to heat and humidity aging on the type of covalently functionalized carbon nanotubes and on the uniformity of their distribution in the epoxy matrix was studied. Two types of carbon nanotubes were used: those modified with carboxy and amide groups. The elastic modulus, bending deflection, and ultimate bending strength for the initial epoxy nanocomposites with carbon nanotubes and for those subjected to heat and humidity aging were determined. The epoxy binders modified with carboxylated carbon nanotubes are more resistant to the action of aging factors. The presence of aggregates of carboxylated carbon nanotubes in the epoxy matrix positively influences the preservation of physicomechanical properties of the composite subjected to heat and humidity aging. Microscopic examination revealed structural features of the epoxy nanocomposite and their effect on the resistance of the composite to the heat and humidity aging.     

Copolymers based on (<Emphasis Type="Italic">p</Emphasis>-vinylphenyl)cyclopropylmethyl chlorocinnamate and methyl methacrylate

Abstract—Copolymers of (p-vinylphenyl)cyclopropylmethyl chlorocinnamate with methyl methacrylate were prepared by radical copolymerization. The copolymerization constants were determined, and the Alfrey–Price Q–e parameters were calculated. The possibility of photochemical cross-linking of the copolymer via double bond conjugated with the carbonyl group in the chlorocinnamate moiety and via the cyclopropane ring was demonstrated. The copolymer obtained exhibits sufficiently high photosensitivity (54.5 cm² J^–1) and high refractive index (n _D ²⁰ 1.5890), which opens prospects for using it as a photosensitive base of negative photoresists and in optics.     

Chemical transformations of tetracyclo[3.3.1.1<Superscript>3,7</Superscript>.0<Superscript>1,3</Superscript>]decane (1,3-dehydroadamantane): II. Reaction of 1,3-dehydroadamantane with <Emphasis Type="Italic">N,N</Emphasis>-dialkylcarboxamides

Alkylation of N,N-dialkylcarboxamides with 1,3-dehydroadamantane has been accomplished for the first time. The reaction involves the C–H bond in the α-position with respect to the carbonyl group and provides a convenient one-step preparation of substituted carboxylic acid amides containing an 1-adamantyl substituent and a pharmacophoric group in the amide moiety.     

Halocyclization of 2-allyl(propargyl)sulfanyl-6-aminopyrimidin-4(3H)-ones

Russian Journal of Organic Chemistry - The alkylation of 6-amino-2-thiouracil with allyl, methallyl, and propargyl halides in the presence of bases gave 2-[allyl(methallyl,...     

The influence of stabilizers on the properties of silicone rubber

The influence of various stabilizers on the properties of rubber based on silicone rubber SKTV is studied. It is established that the use of the Ca/Zn stabilizer in the resin composition makes it possible to increase thermal resistance and physico-mechanical characteristics of the rubber used to make sealing elements in the automotive industry.     

Malliavin calculus for regularity structures: The case of gPAM

Malliavin calculus is implemented in the context of Hairer (2014) [16]. This involves some constructions of independent interest, notably an extension of the structure which accommodates a robust, and purely deterministic, translation operator, in $L^2$-directions, between “models”. In the concrete context of the generalized parabolic Anderson model in 2D – one of the singular SPDEs discussed in the afore-mentioned article – we establish existence of a density at positive times.