Growth and optical properties of filamentary GaN nanocrystals grown on a hybrid SiC/Si(111) substrate by molecular beam epitaxy

The potential to grow filamentary GaN nanocrystals by molecular beam epitaxy on a silicon substrate with a nanosized buffer layer of silicon carbide has been demonstrated. Morphological and optical properties of the obtained system have been studied. It has been shown that the intensity of the photoluminescence spectrum peak of such structures is higher than that of the best filamentary GaN nanocrystals without the buffer silicon carbide layer by a factor of more than two.     

Reactions of P(III)-Halides with Calix[4]Resorcinarenes

Abstract

Reactions of calix[4]resorcinarenes, bearing aliphatic radicals of different length, with P(III)-halides results in the formation of cyclic chlorophosphites and chlorophosphates.     

Self-assembling catalytic systems based on new amphiphile containing purine fragment,exhibiting substrate specificity in hydrolysis of phosphorus acids esters

Micellar catalytic systems based on new purine-containing amphiphile for hydrolytic decomposition of organophosphorus toxicants have been prepared. The aggregation threshold of the system has been estimated by means of tensiometry, conductometry, spectrophotometry, and dynamic light scattering. The solubilizing action of the amphiphile towards the hydrophobic dye has been demonstrated. Kinetic studies of hydrolysis of phosphonates differing in the hydrophobicity have disclosed the substrate specificity of the micellar catalysts; inhibition instead of catalysis has been observed in the case of the less hydrophobic substrate.     

Structure and dynamics of some macrocyclic pyrimidine derivatives

The conformation of macrocycles consisting of the uracil and two thiopyrimidine moieties linked by polymethylene spacers depends on the spacer length, intramolecular hydrogen bonds, and the solvent nature. In CDCl₃ the intramolecular hydrogen bond (NH) appreciably stabilizes the “skew” conformation but only for the macrocycles with methylene spacers consisting of five carbon atoms. Protonation leads to the cleavage of intramolecular hydrogen bonds, destabilization of the “skew” conformation, and self-association due to the strong intermolecular hydrogen bond involving the acid counterion, and the intermolecular bond is cleaved in a polar solvent.     

Die Zerlegung des Aufwands für Altersversorgungsverpflichtungen aus aktuarieller Sicht

According to the German Accounting Law Modernization Act (BilMoG) it is now mandatory to split the regular pension expense into a finance cost component and an operating cost component. In this article we discuss some possible approaches of how such a decomposition could be accomplished from an actuarial perspective.     

Ring contraction of 1,3-bis(5-bromopentyl)alloxazine

The reaction of 1,3-bis(5-bromopentyl)alloxazine with ethylamine in propan-2-ol resulted in replacement of the terminal bromine atoms by ethylamino groups and was accompanied by contraction of the pyrimidine ring so that the products were 1,3-bis[5-(ethylamino)pentyl]alloxazine and 1,3-bis[5-(ethylamino)-pentyl]imidazo[4,5-b]quinoxalin-2-one.     

A near-field microwave technique for the deep profiling of free carrier concentrations in semiconductors

A technique for the profiling of free carrier concentration N(z) in semiconductors, based on the near-field measurements in microwave frequency range, is proposed. A high accuracy in retrieving the N(z) function with characteristic spatial scales of 10–100 nm using 2–3 probes with apertures of 3–15 μm is demonstrated.     

Freezing out color in fluctuons

We show that an analysis of high-energy hadron-nuclear processes should take the nuclear effects in the nucleon channel into account to make correct conclusions about the contribution of multiquark systems, fluctuons, to the nuclear wave function and about the quark distributions in them. Analysis of these distributions indicates that the color degrees of freedom in a fluctuon are partially frozen out and with a high degree of probability a fluctuon contains one or two diquarks.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 24–29, October, 1989.