Reactions of 5-nitrospiro[benzimidazole-2,1′-cyclohexane] 1,3-dioxide with nucleophiles

Reactions of 5-nitrospiro[benzimidazole-2,1′-cyclohexane] 1,3-dioxide with aliphatic amines and sodium hydroxide resulted in removal of one N-oxide oxygen atom and formation of 4-alkylamino- or 4-hydroxy-substituted 5-nitrospiro[benzimidazole-2,1′-cyclohexane] 1-oxides, respectively. The title compound reacted with ammonia and methylamine in the presence of MnO₂ with conservation of both N-oxide moieties, and the products were 4-amino- and 4-methylamino-5-nitrospiro[benzimidazole-2,1′-cyclohexane] 1,3-dioxides. The reactions with aromatic amines were accompanied by removal of both N-oxide oxygen atoms with formation of N-aryl-5-nitrospiro[benzimidazole-2,1′-cyclohexane]-4-amines. In the reactions of 5-nitrospiro-[benzimidazole-2,1′-cyclohexane] 1,3-dioxide with sodium azide and aromatic amine hydrochlorides nucleophilic replacement of the 5-nitro group by azido or arylamino occurred, in the first case both N-oxide fragments being conserved. The reactions with aromatic amine hydrochlorides afforded N-aryl-5-nitrospiro[benzimidazole-2,1′-cyclohexan]-4-amine 1-oxides. Treatment of 5-nitrospiro[benzimidazole-2,1′-cyclohexane] 1,3-dioxide with sodium cyanide led to the formation of 5-oxo-3,5-dihydrospiro[benzimidazole-2,1′-cyclohexane]-4-carbonitrile 1-oxide.     

Gas chromatographic determination of admixtures of permanent gases, CO, CO2, and hydrocarbons in methylsilane

A procedure is developed for the gas chromatographic determination of admixtures of permanent gases, CO, CO₂, and hydrocarbons in methylsilane with detection limits of 0.02–0.8 ppm. The procedure was applied to the analysis of methylsilane obtained by reducing methyltrichlorosilane with sodium tetrahydrob-orate in an organic solvent. Admixtures of permanent gases and C₁–C₅ hydrocarbons the in synthesized methylsilane were detected.     

Non-Volatile Threshold Adaptive Transistors with Embedded RRAM

We propose a novel nonvolatile threshold adaptive transistor （TAT） for neuromorphic circuits. The threshold adaptive transistor is achieved by embedding a resistive random-access memory （RRAM） material stack between the gate electrode and gate dielectric. During operation, the embedded RRAM device is kept at a high resistance state, which makes it act as a nonvolatile capacitor. The threshold could be nonlinearly adjusted by the voltage pulses applied on the gate of the transistor. We quantitatively estimate the range of the capacitance variation of the RRAM device. The threshold voltage of the TAT is simulated and shows expected variation. The simulated output of an inverter using a TAT shows a nonlinear adaptive behavior.     

Formation of nanosized oxide films via thermal oxidation of Co<Subscript>3</Subscript>O<Subscript>4</Subscript>/InP heterostructures

Modification of InP film with magnetron-deposited 30 nm nanolayer of Co₃O₄ has resulted in the transit mechanism of thermal oxidation of the semiconductor and formation of nanosized oxide-phosphate films. Efficient transit interactions of Co₃O₄ with the semiconductor due to fast chemical binding of indium has led to the suppression of its diffusion inside the films. Secondary interactions of the oxides result in the formation of phosphate scaffold in the inner film regions, whereas the surface layer contains cobalt and indium oxides.     

The Influence of the Geometric Shape of Carbon Nanoparticles on the Strength Properties of Nanocomposite Materials Obtained by Filling an Epoxy Matrix

Abstract

The effects of filling an epoxy matrix modified with “Viniflex” with carbon nanotubes, fullerene C₆₀, or graphene on the mechanical properties, surface morphologies and glass transition temperatures of the composite materials obtained after curing were studied. It was shown that the largest decrease in glass transition temperature and an increase in impact strength was achieved by the introduction of 0.1 mass% graphene. Filling with graphene and carbon nanotubes increased the bending strength while filling with C₆₀ fullerenes provided the greatest compressive strength and elasticity modulus. An explanation of the results was based on ideas about the relationship of the geometrical shape of the nanofiller to the load direction and features of the phase composition of the composite materials. It is suggested that the carbon nanomaterials had a template effect on the packing of the epoxy matrix chains.     

Phase-Transfer Catalysis in Alkaline Hydrolysis of N-Benzyloxycarbonylglycine 4-Nitrophenyl Ester in the Two-Phase System Chloroform-Borate Buffer

Alkaline hydrolysis of N-benzyloxycarbonylglycine 4-nitrophenyl ester in the two-phase system chloroform-borate buffer (pH 10 and 11) in the presence of C₁₆H₃₃NMe₃Br and Ph₄PZ (Z = Cl, Br, I) at 25°C follows the extraction mechanism where the rate-determining stage is the chemical reaction in the organic phase. The different kinetic profiles of the reaction depending on the nature of Z^- were explained in terms of concurrent extraction of three kinds of anions: nucleophile OH^-, nucleofuge 4-NO₂C₆H₄O^-, and foreign ion Z^-.     

Uniaxial exchange flows of two Bingham fluids in a cylindrical duct

Buoyancy driven flows of two Bingham fluids in an inclined ductare considered, providing a simplified model for many oilfieldcementing processes. The flows studied are near-uniaxial andstratified, with the heavy fluid moving down the incline, displacingthe lighter fluid upwards. Existence and uniqueness resultsare obtained for quite general flows and for those which satisfyan axial flow rate constraint. Parametric dependence of thesolutions on the axial pressure gradient is studied. Flows whichsatisfy a zero net axial flow constraint result from an axialpressure gradient which minimizes the viscous dissipation, butnot the plastic dissipation. A regularization method is usedto compute solutions to these problems for (more or less) arbitraryfluid-fluid interfaces and duct-cross sections. Examples relatedto a number of practical applications are presented.     

Thermodynamic model of the stabilization of an intermediate state in the region of the metamagnetic phase transition in erbium orthoferrite

The possible mechanisms of the thermodynamic stabilization of an intermediate state in the first-order metamagnetic phase transition in a magnetic field parallel to the Ising c axis of the Er³⁺ ions in erbium orthoferrite at T = 1.6 K have been analyzed. The model is chosen using the magneto-optical experimental data on the features of this state.