Interaction between Dusty Shock Waves and Three-Dimensional Scaffolds of Carbon Nanocomposites upon the Deposition of Biocompatible Coatings

The interaction between shock waves (velocity D0 ≈ 2–2.5 km s^?1 and maximum pressure p_max ≈ 3.1–3.8 MPa) containing finely dispersed hydroxyapatite particles (with mean diameters of d_p ≈ 70 nm and 100 μm) and substrates of carbon nanostructured composites that are a periodic three-dimensional scaffold is investigated experimentally. Study of these processes is important for the development of nonconventional osteoconductive and biocompatible materials with properties of osteoinduction. Features of the interaction between dusty shock waves and these substrates are established on the basis of complex experimental studies. Optimum conditions and ways of forming high-adhesion coatings on carbon composites are determined.     

Singular manifolds in optimal control problems

We propose a method of solving an optimal control problem with constraints on the control. The method is applied to find an upper bound of the Hamilton-Pontryagin function and is based on the construction of a system of differential equations containing the constraints available in the problem as singular manifolds. Bibliography: 2 titles. Translated fromProblemy Matematicheskoi Fiziki, 1998, pp. 214–216.     

Formation of the Magnetic Field in the CC 30/15 Isochronous Cyclotron

Physics of Particles and Nuclei Letters - Design features of the electromagnet of the CC 30/15 isochronous cyclotron using mathematical modeling methods are presented. The electromagnet of shielded...     

Femtosecond Laser Irradiation of a Multilayer Metal–Metal Nanostructure

JETP Letters - The selective modification of upper layers of a Ni/Al multilayer nanostructure irradiated by a single femtosecond laser pulse has been studied. The analysis of surface topography...     

Aerogels Based on Calcium Alginate and Silicon Dioxide and Modified with Carbon Nanotubes for Selective Sorption of Argon from a Mixture with Oxygen

Russian Journal of Applied Chemistry - Two kinds of aerogels, those based on silicon dioxide and on calcium aginate, modified with multiwalled carbon nanotubes, were synthesized by the...     

Geminal systems. 50. Synthesis and alcoholysis of N-acyloxy-N-alkoxy derivatives of ureas,carbamates, and benzamides

Procedures were developed for the synthesis of N-acyloxy-N-alkoxy derivatives of ureas, carbamates, and benzamides by the reactions of the corresponding N-alkoxy-N-chloro derivatives with sodium carboxylates in MeCN. N-Chloro-N-ethoxy-p-toluenesulfonamide was inert in this reaction. Alcoholysis of N-acyloxy-N-alkoxy derivatives of ureas, carbamates, and tert-alkylamines afforded the corresponding N,N-dialkoxy derivatives, whereas alcoholysis of N-acetoxy-N-ethoxybenzamide gave rise to alkyl benzoates.     

Reactions of p-Nitrophenyloxirane with Amines Containing Fragments with Bicyclic Skeleton

Reactions of p-nitrophenyloxirane with amines containing fragments with bicyclic skeleton of norbornene, norbornane, epoxynorbornane (stereoisomeric exo- and endo-5-aminomethylbicyclo[2.2.1]hept-2-enes, N-benzyl-endo-5-aminomethylbicyclo[2.2.1]hept-2-ene, endo-5-(2-aminoethyl)bicyclo[2.2.1]hept-2-ene, stereoisomeric exo- and endo-2-aminomethylbicyclo[2.2.1]heptanes, 2-(1-aminoethyl)bicyclo[2.2.1]heptane, exo-5-aminomethyl-exo-2,3-epoxybicyclo[2.2.1]heptane) were investigated. The aminolysis of p-nitrophenyloxirane occurred regioselectively according to Krasusky rule as was proved by ¹H and ¹³C NMR data. As shown by ¹H and ¹³C NMR spectroscopy the oxyalkylation product obtained from N-benzyl-endo-5-aminomethylbicyclo[2.2.1]hept-2-ene was composed of two diastereomers originating from the presence of a chiral nitrogen atom in the rear part of the rigid bicyclic skeleton. New products of amino groups transformation in the molecules of hydroxyamines were obtained by reaction with p-methylbenzoyl chloride and p-nitrophenylsulfonyl chloride. Regioselectivity of the attack of electrophilic reagents on the nitrogen in the hydroxyamines was confirmed by IR and ¹H NMR spectra of the products. The data on pharmacological activity tests of N-2-hydroxyethyl(p-nitrophenyl)-5-aminomethylbicyclo[2.2.1]hept-2-ene are reported.     

Biological generation of hydrogen

Microorganisms are capable of evolving hydrogen. Such microbiologic processes can be divided into dark anaerobic hydrogen evolution, light-dependent hydrogen evolution without oxygen evolution, and light-dependent hydrogen evolution accompanied oxygen evolution (biophitolysis). The review describes recent advances in biohydrogen production from whole-cell microorganisms.