Colloid and nanodimensional catalysts in organic synthesis: VIII. Hydrogenation of C=N bond with hydrogen in the presence of colloid nickel

Hydrogenation of azomethines with hydrogen at atmospheric pressure using nickel nanoparticles as catalyst was carried out. Reaction may be used for the preparation of secondary amines under mild conditions on an available catalyst. Continuation of studies will lead to development of a convenient method for the reductive amination of carbonyl compounds.     

Structural and phase characteristics of the diamond/matrix interfacial zone in high-resistant diamond composites

The structural-phase state of the contact zone and the factors that influence on the strength of diamond retention in the diamond carbide composites were determined. Composites were obtained by the new hybrid technology that eliminates the reheating of the metalized coating. The elaborated technology combines the thermal diffusion metallization of a diamond and the sintering by the scheme of self-dosed impregnation in a one-stage technological cycle. By the methods of electron microscopy, X-ray diffraction analysis, and Raman spectroscopy the structural and phase characteristics of the interphase boundary were investigated. The improvement of chemical and mechanical adhesion between the diamond and carbide matrix was obtained. It was shown that the specific productivity of the samples with a metalized diamond component is 39% higher than those without metallization.     

A method for constructing the trajectory for an unmanned aerial vehicle in a city

A synthesis method for the reference trajectory of an unmanned aerial vehicle that flies around obstacles of urban buildings in the horizontal and vertical planes is proposed. To solve this problem, for the first time a conformal mapping is constructed for a collection of rectangles that approximate the obstacles on the digital map of a terrain.     

Condensation of adamantanone with methylene-active compounds

A convenient method was developed for the preparation of potentially bioactive substances with 2-adamantyl radical and of intermediates for their synthesis. Condensation of adamantanone with methylene-active compounds was performed, and the reaction features were determined.     

Simulating resistance switching in amorphous carbon

The resistance switching in amorphous carbon (a-C) is mathematically simulated on the basis of quantum molecular dynamics. The electric conductivity in thin a-C films is related to a phase transition due to an electric field and corresponding Joule heating and cooling. Simulations show that the transition mechanism is related to the clusterization of existing conducting regions of graphite (sp ²) in a nonconducting diamond (sp ³) matrix. Simulations yield the conditions for the phase transition in a-C from one state to another. Excited molecular orbitals and the energy gap at different temperatures are also calculated.     

Between Aromatic and Quinoid Structure: A Symmetrical UV to Vis/NIR Benzothiadiazole Redox Switch

Reversibly switching the light absorption of organic molecules by redox processes is of interest for applications in sensors, light harvesting, smart materials, and medical diagnostics. This work presents a symmetrical benzothiadiazole (BTD) derivative with a high fluorescence quantum yield in solution and in the crystalline state and shows by spectroelectrochemical analysis that reversible switching of UV absorption in the neutral state, to broadband Vis/NIR absorption in the 1st oxidized state, to sharp band Vis absorption in the 2nd oxidized state, is possible. For the one-electron oxidized species, formation of a delocalized radical is confirmed by electron paramagnetic resonance spectroelectrochemistry. Furthermore, our results reveal an increasing quinoidal distortion upon the 1st and 2nd oxidation, which can be used as the leitmotif for the development of BTD based redox switches.     

Helical Ullazine-Quinoxaline-Based Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic azomethine ylides (PAMYs) are powerful building blocks in the bottom-up synthesis of internally nitrogen-containing polycyclic aromatic hydrocarbons (N-PAHs) through 1,3-cycloaddition reactions. In this work, the cycloaddition reaction of PAMYs to asymmetric ortho-quinones is presented, which, in contrast to the addition to symmetric para-quinones, facilitates subsequent condensation reactions and allows the synthesis of three helical N-PAHs with ullazine-quinoxaline ( UQ - 1 – 3 ) backbones. UQ - 1 and UQ - 2 possess two helical centers; however, single-crystal X-ray analysis together with the computational modeling of UQ - 3 elucidate the formation of only the thermodynamically most stable geometry with four helical centers in a (P,P,M,M) configuration. For the series UQ - 1 – 3 , the number of redox steps is directly correlated with the number of ullazine or quinoxaline units incorporated into the targeted molecular backbones. A detailed investigation of the spectroscopic and magnetic properties of the radical cation and anion as well as the dication and dianion species by in situ EPR/UV/Vis-NIR spectroelectrochemistry is provided. The excellent optical and redox properties combined with helical geometries render them possibly applicable as chiral emitter or ambipolar charge transport material in organic electronics.     

Determination of the Mn/Fe Ratio in Ferromanganese Nodules Using Calibration-Free Laser-Induced Breakdown Spectroscopy

Optics and Spectroscopy - The Mn/Fe ratio in ferromanganese nodules is determined by calibration-free laser-induced breakdown spectroscopy based on the use of only the plasma temperature and...     

The Concept of a Hybrid Pulsed Plasma Thruster for Small-Size Space Satellites

Russian Physics Journal - A concept of a hybrid plasma source to be used as a micro satellite thruster is proposed, where the propellant is a liquid gallium–indium alloy. The plasma source...