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In this work we study zinc oxide nanostructures of various geometries synthesized via the hydrothermal technique on Si (111) substrate. We demonstrate capabilities of the growth protocol for control over the morphology of nanostructures varying from nanowires to hexapods. The obtained samples were studied by photoluminescence spectroscopy to demonstrate a very narrow spontaneous emission near 370 nm. Despite cheap and feasible fabrication, the obtained nanostructures possess high crystallinity confirmed by the absence of typical for ZnO wide emission band in the visible region, related with the structure imperfections. This property together with the capabilities of the geometrical control over the nanostructures unveil perspectives of the reported approach for future UV photonic applications.

The exchange electron-hole (e-h) Coulomb interaction changes essentially the properties of the two-dimensional (2D) magnetoexcitons, whose electron structure is mainly determined by the action of the Lorentz force and by the direct e-h Coulomb interaction. The exchange interaction leads to the mixing of the two bare magnetoexciton states with total angular momentum projections \( F = \pm 1 \). As a result instead of them two new superposition states one symmetric and another asymmetric appeared. The symmetric state acquired a Dirac cone dispersion law in the range of the small in-plane wave vectors \( |\vec{k}_{||} |l_{0} < 1 \), where \( l_{0} \) is the magnetic length, with group velocity proportional to the magnetic field strength. The quantum transitions to this state from the ground state of the crystal under the influence of the light with both circular polarizations have the equal probabilities, being strongly dependent on the direction of the light propagation as regards the plane of the layer. The probability is maximal in the Faraday geometry and vanishes in the Voigt one. In difference on it, the asymmetric state is characterized by the usual dispersion law inherited from the bare magnetoexciton states, is dipole active in both circular polarization, but does not depend on the direction of the light propagation. In the case of light with linear polarizations the both symmetric and asymmetric states reveal the quantum interference effects.

Unlike groups semigroups of cohomological dimension c d need not be free Examples of such semigroups were constructed in and However a weak analog of the Stallings Swan theorem holds a cancellative semigroup of c d can be embedded into a free group So the problem of describing such semigroups is reduced to studying subsemigroups of a free group having c d Nevertheless this question seems rather di cult even for subsemigroups of a free semigroup In this paper we con ne ourselves to a free semigroup F and establish some properties of its subsemigroups of c d Proposition and Corollary using auxiliary results from A left ideal of F has c d if and only if it is free Theorem In particular the c d of all proper two sided ideals of F is greater than Corollary For right ideals the matter is more complicated because of the asymmetric de nition of semigroup cohomology Proposition shows that Theorem does not extend to right ideals Nevertheless a principal right ideal of F has c d if and only if it is free i e is not of the form abaF Theorem

Differential (wavelength-modulated) absorption of sulfoselenide solid-solution nanocrystals has been studied in a glassy fluorophosphate matrix near the fundamental absorption edge at 360–620 nm. The observed oscillations in the absorption are attributed to size quantization of electrons and holes under strong quantum-confinement conditions. The sulfur content in the mixed semiconductor has been refined from Raman scattering spectra in CdSxSe1−x samples with x=0.30, and the nanocrystal size (R≅30 A) has been derived from low-frequency Raman scattering spectra. These data were used to calculate the energies of electron-hole transitions in nanocrystals of mixed composition, and their subsequent comparison with experiment. The calculations were found to be in a good agreement with the observed experimental absorption spectrum for nanocrystals about 45 A in size. The applicability of band-structure simulation for a nonspherical nanocrystal grown in a fluorophosphate glass matrix is discussed.

The methods of animal cell immobilization in chitozan microcapsules and alginate polyethylene glycol microgranules and their in vitro maintenance are presented. Hybridoma SS-3 cells remained viable for at least 20 days and capable of producing IgG immunoglobulins, which penetrate through an alginate-chitosan membrane.

Herpesvirus disease of Siberian sturgeon, caused by SbSHV, is especially severe in the industrial populations. The commonly used method for its specific diagnostics has a sufficient disadvantage because of SbSHV active reproduction in vivo when the water temperature is in the range of 10-18 С, and therefore, can be applied mainly in spring and sometimes in autumn. At other seasons the amount of the virus in the fish tissues reduces so that it becomes nearly unrevealable. We have developed a method for retrospective diagnosis of herpesvirus disease of Siberian sturgeon using indirect ELISA version. Experimental data on ELISA development for the detection of antibodies against Siberian sturgeon herpesvirus are presented. Proce-dures for preparing the ELISA specific reagents are described, including the virus reproduction in cell culture, isolation of IgM-like immunoglobulin from hyperimmune antisera of sturgeon, etc. The effectiveness of the proposed method and the reaction of neutralization was compared. It is shown, that by elaborated method the SbSHV antibodies can be detected both in the Siberian sturgeon, and among closely related species of sturgeon, or their hybrids. Keywords: herpesvirus of the Siberian sturgeon, immunoglobulin, ELISA, serodiagnostics.

A method is described for detecting the onset of boiling of cryogenic liquids. Boiling is initiated by superheating, using an optical system, of a surface placed in a saturated cryogenic liquid. The experimental dependence of the thermal flux on the amount of surface superheating is obtained. 10 refs., 4 figs.

Publisher Summary This chapter describes the general properties of 0-cohomology. It illustrates how 0-cohomology can be seen as a derived functor. The chapter explores how the Hochschild cohomology of contracted algebras relates to the cohomology of semigroups generating them. It also explains the applications of 0-comohology. The definitions and results from homological algebra and theory of semigroups are presented. The chapter explains how 0-comohology links semigroups with several different branches of the algebra.

The recombinant avian adenovirus CELO-gpRb expressing glycoprotein G of rabies virus (strain TS-80, ARRIWM, Pokrov, Russia) was used for mice vaccination against rabies. Double intramuscular immunization by recombinant CELO-gpRb adenovirus in a dose 10(9) pfu per mouse caused the induction of virus neutralizing antibodies (VNA) synthesis in 78% of mice, while twice repeated intradermal injections of the recombinant adenovirus failed to induce the VNA production. The protection level in groups of vaccinated mice after intracerebral injection of CVS rabies virus in a dose of 100 MLD50 was equal to 45% at single intramuscular immunization and to 91% after twice repeated intramuscular immunization. The recombinant adenoviral vaccine against rabies, based on CELO viral genome, has a good perspective for domestic and wild animal vaccination, not only due to rather high protection level, but also because the production of adenoviral CELO vaccine in chicken embryos is of high technology and inexpensive.

The temperature dependencies of luminescence spectra of the InAs/GaAs quantum dots L0 (ELO = 1.235 eV), L1 (EL1 1.290 eV) and Ii (E11 = 1.343 eV) and wettings layer (WL) (EWL = 1.408 eV) have been investigated at P = 0 and P = 15 kbar. The InAs quantum dots on vicinal substrates GaAs at misorientation angle 7° [001]have been grown in submonolayer migration enhanced epitaxy mode (SMEE). The activation energies havebeen determined from the temperature quenching of luminescence. Their dependence on a value of hydrostaticpressure have been studied. The available scheme of energy levels of quantum dots has been proposed.Keywords: quantum dots, hidrostatic pressure, activation energies, photoluminescence, exciton INTRODUCTION Nowthe physical properties of quantum dots (QD) InAs/GaAs are researched very intensively. They are usedas materials for JR semiconductor lasers. The experiments with using of high hydrostatic pressure indicated tothe important role of a matrix in forming of excited states [1] .

We report the growth of copper (I) chloride by atomic layer deposition. CuCl was deposited as nanoparticle arrays whose size and density were controlled by the process conditions. The nanoparticles were deposited using the self-limiting reaction of [bis(trimethylsilyl)acetylene]-(hexafluoroacetylacetonato)-copper(I) and hydrogen chloride. UV absorption measurements showed the characteristic Z1,2 and Z3 exciton absorption bands of CuCl. A strong UV emission was observed at 5 K from the free exciton Z3 and bound exciton I1 at 386.7 and 390.6 nm, respectively. A previously unreported visible emission band at 408 nm was also observed and attributed to the acceptor level of Cu vacancies.

Exciton localization in near-surface regions of semiconductors is discussed. Various mechanisms are listed responsible for the effect based on the binding of the excitons by nearsurface imperfections in crystals. One of the most important mechanisms of the localization is the Stark-effect on excitons in space-large layers of semiconductors. It is accounted for in the numerical computation of the exciton reflectance. Essential is a nonuniform character of the electric field. The localization is accompanied by a large enhancement of the exciton reflectance and the appearance of a low-energy spike in the reflection lineshape. The computed lineshapes are typical of the A n = 1 exciton in a number of CdS and CdSe samples. It is shown that the increase of the bulk damping from 1 to 5 em−1 diminishes the influence of localization and transforms the enhanced lineshapes to the ideal form. The latter is typical of the B-type excitons in the same crystals. This finding resolves the paradox of different sensitivity of the A- and B-excitons to various (nondestructive) treatments of the surfaces. It explains also the anomalous behaviour of the minimal reflectance with temperature in CdS reported recently in the literature. [Russian Text Ignored].

The spectral distribution of the photoconductivity of CdS and CdSe single crystals has been investigated at 77 °K in a wide spectral range. The values of the exciton diffusion lengths in these compounds have been obtained from the photocurrent spectra using the absorption coefficient data. The exciton diffusion lengths were found to be within the range of 2000 to 10000 A for CdS and 2000 to 4000 A for CdSe. The proposed model involves the diffusion of the excitons to the surface, where they dissociate into free carriers interacting with the near-to-surface centres. The role of the space charge layer in these phenomena is discussed.

The present paper is a survey of experimental work on exciton interaction carried out in the past three years in the "Optics of Solids Laboratory" at Leningrad University. Investigations of exciton interaction in this laboratory were initiated by the late Prof. E. F. Gross, who discovered the spectrum of exciton absorption in Cu20 in 1951 [1]. Later, he paid great attention to the study of exciton interaction at high density. Gross and his collaborators [2] observed Bose condensation of excitons in CdSe crystals. These investigations are being continued in this laboratory. A short time ago Japanese investigators discovered Bose condensation of excitonic molecules also in CdSe crystals using picosecond laser light pulses for excitation [3]. The germanium crystal is of great interest for investigators with respect to the study of exciton interaction. These properties manifest themselves especially clearly here due to the long life-time of excitons. It was in germanium that the phenomena of metallization and condensation of excitons [4] were first observed, and, later, also the emission from the condensed phase [5]. Interesting information, in the writer's opinion, may be obtained from the spectroscopic study of low-temperature emission in germanium. It will be shown that this emission occurs at 2 K at a rather low excitation density. It has been possible to observe spectroscopically the dynamics of formation of a characteristic lowtemperature emission and its development with increasing density.