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Infrared visualization was employed to observe the decay of a hydrogen-air flame front propagating in a narrow gap similar to a Hele-Shaw cell. Based on the images, the flame front speeds and sizes for mixtures with hydrogen concentrations of 7 % and 10 % by volume in gaps with widths of 3–5 mm were calculated. The shapes of the individual cells formed were determined, the mechanism of flame front decay due to the critical influence of diffusive-thermal instability was described, and a criterion for flame front decay was proposed. The obtained results may be used in the design of fuel cells and MEMS hydrogen devices to ensure the safety of their operation.

Abstract: Films of nonstoichiometric germanium–silicon glasses of two types—GeOx[SiO](1 –x)and GeOx[SiO2](1 –x)—are deposited onto cold Si (001) substrates by evaporating GeO2and SiO (or SiO2) powders simultaneously in high vacuum. Film samples in their initial (as-deposited) state and after being annealed at 550 and 650°C for 1 h are investigated using IR and Raman spectroscopies and electron microscopy, and their photoluminescence (PL) is studied as well. Raman spectroscopy shows that, in contrast to the initial GeO[SiO2] film, the initial GeO[SiO] one contains clusters of amorphous germanium, their size being ~3 nm, as found by electron microscopy. The presence of Si–O, Ge–O, and Si–O–Ge bonds in the films is established by IR spectroscopy. Clusters of amorphous germanium are found in both films after annealing at 550°C, while germanium nanocrystals are formed in the films subjected to annealing at 650°C. For the initial films, a broad band with a maximum at 1050 nm is registered in their low-temperature PL spectra, which may originate from such defects as oxygen vacancies and overstoichiometric germanium atoms. Annealing causes structural changes in the films and affects their PL behavior. The films containing germanium nanoclusters give rise to PL with a maximum at 1400–1600 nm, with the defect-related signal being diminished. The temperature dependence of PL intensity exhibits a decreasing behavior, but PL is observed to temperatures as high as 200 K. The contribution of germanium nanocrystals formed at the annealing stage to PL is discussed.

Abstract: This work was devoted to studying the atomic structure and electron spectrum of a-SiOx: H films created on silicon and glass substrates by means of plasma-enhanced chemical vapor deposition (PECVD). Depending on the conditions of oxygen supply into the reactor, the stoichiometric parameter xof the films was varied from 0.57 to 2. The structure of the films and the specific features of their electron structure were characterized depending on the parameter xwith a complex of structural and optical methods and ab initio quantum-chemical simulation for the model SiOxstructure. The studied SiOx: H films were established to consist predominantly of silicon suboxides SiOy, SiO2clusters, and amorphous silicon. Based on the spatial fluctuations of their chemical composition, the model of bandgap width and potential fluctuations was proposed for SiOxelectrons and holes. The obtained data would provide the charge transport in a-SiOx: H films with more precise modeling important for the creation of nonvolatile random-access memory (RAM) elements and memristors on their basis.

A course of medication with the Kardisten dietary supplement normalizes an elevated blood cortisol level and optimizes the activity of brain vasculature to improve the functional state and enhance short- and long-term memory performance, especially in subjects younger than 50. Kardisten evokes a more pronounced decrease of cortisol level and improves memory performance more efficiently in the case of initial organic changes in the brain vasculature as compared to advanced atherosclerosis. Kardisten activates the natural mechanisms of enhanced functional capacity in the human organism, exerts a favorable effect on mature and elderly persons, and can be recommended for physical and mental health improvement and the preservation of an active lifestyle during aging.

The clarification of the molecular mechanisms of the effect of a plant adaptogen’s active substance is a topical study direction. In the present work, we studied the effect of phytopreparations containing the Serratula coronataL. phytoecdysteroids (20-hydroxyecdysone and inocosterone) or the Trigonella foenumgraecumL. steroid glycosides (dioscin and protodioscin) on the expression of stress-response genes, stress resistance, and the life span of the Drosophila melanogaster. It was demonstrated that phytopreparations activate the mechanisms of antioxidant protection (Sod1), but reduce the level of induction of DNA repair (XPFand Rad51) and the apoptosis (Hid) genes. At the same time, the studied phytopreparations have a moderate adaptogenic and geroprotective effects associated with activation of the hormesis mechanisms.

Treatments by femtosecond Ti-sapphire laser (wavelength is 800 nm, pulse duration is <30 fs) and nanosecond KrF excimer laser (wavelength is 248 nm, pulse duration is 25 ns) were performed to study the impact of laser fluence, pulse duration and energy of photons on the process of chemical and structural reconstructions in GeOxand GeO2:Ge heterolayers. The solid GeOxfilms are metastable and decompose into two phases - Ge and GeO2. Nanosecond KrF laser irradiation produces significant shrinkage of GeOxfilms and GeO2:Ge heterolayers caped by thin SiNxOyor SiO2films. Pulse annealing by both types of lasers stimulate as the process of nanoclusters forming and crystallization of initial amorphous Ge-nanoclusters in the GeO2matrix. The possibility to use the solid germanium monoxide (GeO(s)) and GeO2:Ge heterolayers (without cap layers) as nano-resist in laser nanolithography was demonstrated. The new nanostructured material was formed - the layers of nanofoam GeO2which can be obtained only with application of femtosecond laser pulse treatments.

Abstract: The electronic structure and g factors of simple impurity centers and hexamer ytterbium clusters in fluorites have been calculated in terms of the exchange charge model. Preliminarily, their local crystal structures have been calculated in the framework of the shell model with the inclusion of lattice distortions near the impurity.

The terahertz time-domain and Raman spectra of corticosteroid hormones in the region of low-frequency infrared vibrations have been measured. On the ground of quantum chemical calculations of the frequencies and normal modes the assignments of vibrational bands in the THz-spectra are performed.

Silicon nanocrystals prepared in phosphorus-doped (at a concentration of 3.3 × 1020cm−3) amorphous silicon films under pulsed irradiation with an excimer laser are studied using Raman spectroscopy and electron microscopy. The experimental data can be interpreted in terms of the Fano interference as a manifestation of the electron-phonon interaction effects in n-type silicon nanocrystals. It is assumed that a strong electron-phonon interaction (as compared to similar interactions in n-type bulk silicon) is due to the weakening of the momentum selection rules in nanocrystals.

We have applied the Raman spectroscopy technique to the study of phonon-plasmon coupled modes in Si-doped GaAs_n/AlAs_m superlattices (SLs), grown on (001), (311)A and (311)B substrates. We have observed the shift and broadening of the Raman peaks in doped SLs, compared with undoped SLs. When the GaAs layers were thinned from 10 to 1 monolayer, the coupled phonon-plasmon modes became three-dimensional-like, and the interaction of plasmons with LO-phonons of AlAs-type took place. The phonon-plasmon interaction of the SLs was numerically simulated. There was a qualitative agreement between the experiment and the calculations. We observed a difference in dispersion between the coupled phonon-plasmon modes for SLs grown on facet surface (311)A and surface (311)B. This is probably due to differences in the electron spectra of such SLs caused by the difference in shape of GaAs quantum objects formed on AlAs reconstructed surfaces.

Phonon spectra of GaAs/AlAs superlattices (SLs) grown on (311)A, B and (001) surfaces were studied using Raman spectroscopy. The thickness of GaAs layers were varied from 1 to 10 monolayers (MLs); the thickness of AlAs barriers were 8 ML in the (311) direction. Different polarization geometries of Raman scattering were applied to study LO and TO modes. The splitting of TO_x (atoms displace in the direction [01&bar1;] perpendicular to the facets on the (311)A surface) and TO_y (atoms displace in the [&bar2;33] direction parallel to the facets) modes was observed for (311)A SLs. In the case of (311)B SLs no splitting was observed. The phonon anisotropy of (311)A SLs may be indirect evidence of anisotropic structure of quantum objects formed on the (311)A GaAs surface. In the Raman spectra of the SL containing GaAs submonolayers (SML) grown on a (2×4) reconstructed (100) surface, Raman peaks corresponding to additional lateral confinement of LO phonons were observed. The calculations of Raman spectra were carried out using the Born-von-Karman model (taking into account Coulomb interaction in the rigid-ion model) and the Wolkenstein bond polarizability model. According to the calculations, the interface structure strongly influences the Raman spectra of GaAs/AlAs heterostructures containing GaAs SML.

Abstract: GaAs-AlAs corrugated superlattices (CSL) are formed on spontaneously nanofaceted (311)A surfaces. Using high-resolution transmission electron microscopy (HRTEM) along the $$[\bar 233]$$ zone axis with an appropriate image evaluation technique to enhance the contract between GaAs and AlAs we found two distinct lateral periodicities along the $$[0\bar 11]$$ directions for two different CSL layer thickness regimes. For multilayer deposition with GaAs layer thickness exceeding 1 nm the lateral periodicity of 3.2 nm is clearly revealed. The contrast originates from the thickness modulation of both AlAs and GaAs layers with a period of 3.2 nm in the $$[0\bar 11]$$ direction. The corrugation height is about 1 nm and it is symmetric for both upper and lower GaAs-AlAs interfaces. Thicker sections of the thickness-modulated AlAs and GaAs layers of the CSL are shifted by a half period with respect to each other. In the regime when the GaAs deposited average thickness is below 1 nm, which is necessary for complete coverage of the AlAs surface, a lateral periodicity of ≈1.5–2 nm is additionally revealed. We attribute this effect to the formation of local GaAs clusters dispersed on a corrugated (311)A AlAs surface resulting in a local phase reversal of the AlAs surface in their vicinity upon subsequent overgrowth. This reversal can be explained by the same effect as the phase shift of the surface corrugation upon heteroepitaxy on (311)A. In our model AlAs does not wet the GaAs cluster surface, unless different more energetically favorable scenario is possible. This causes accumulation of AlAs in the vicinity of the GaAs cluster and, as a result, the local phase reversal of the AlAs surface. The AlAs corrugated surface domains with different phases coexist on the surface resulting in an additional periodicity revealed in the HREM contrast modulation. Additionally HRTEM studies indicate that the AlAs-GaAs interface inclination angles in both regimes are 40° and 140° with respect to the flat (311) surface in an argreement with the {331} facet geometry model proposed by R. Nötzel, N.N. Ledentsov, L. Däweritz, M. Hohenstein, and K. Ploog.

A numerical method has been applied to a turbulent-transport model to examine the cooling of a liquid film in a circular tube.

Without Abstract:

Abstract: The dependence of the energy characteristics on an adiabatically slowly increasing external force is determined analytically for an anharmonic oscillator. The analytical results are confirmed by a numerical calculation. The nature of the force dependences of the energy characteristics are determined and discussed.

Thyroid disease is common in developing countries and its management is based on the measurement of thyroid function and the investigation of thyroid masses. This report discusses techniques and outlines a strategy for the measurement of thyroid function using radioimmunoassays of thyroid-related hormones in the blood. It makes proposals for the evaluation of thyroid morphology using echography, pertechnetate imaging and fine needle biopsy. Note is taken of the difficulties facing laboratories in developing countries and the International Atomic Energy Agency is concerned with the practical assessment of these recommendations and of any alternative proposals in this field.

Without Abstract:

1.The introduction of unidirectional high-modulus fibers into a polymer matrix leads to an abrupt change not only of the elastic but also of the dissipative properties of the composite material.2.The viscoelastic behavior of fibrous composites is due to the special features of the state of stress in the composite which leads, first of all, to an increase of shear deformation and to a more important role of the bulk modulus of elasticity of the matrix.

-- A technological regime for the preparation of polyacrylonitrile fibres from binary and ternary copolymers has been chosen; these differ from known specimens in having a more uniform cross-sectional structure and a smoother elementary filament surface.

Twelve countries participated in the WHO inter-comparison for which transmission CAP (College of American Pathologists) brain and CAP liver phantoms and emission London liver phantoms were used. A total of 157 imaging devices were tested. Overall results from the phantoms revealed a wide range of targets detected. For the CAP-phantoms target detectability dropped below 50% for target sizes less than 9 mm and below 60% for target contrast less than 0.84:1. On average one false positive and six false negative results were reported using CAP-brain phantoms and one false positive and one false negative result using CAP-liver phantoms. For the London liver phantoms containing the tissue equivalent rubber abdominal simulation the target of 1 cm was never visualised. Two targets in this phantom (2 cm and 2.5 cm) were correctly identified in 34% of studied and one of these targets in 52% of studies. Equivocal and false positive results were reported in 42%. The WHO inter-comparison demonstrated the need to establish new, or to improve the existing, quality control programmes.

Use of BFK-28.5 block spinneret assemblies has made it possible to ensure the necessary level of regeneration of the fibre and process stability at a spinning speed of 27 m/min.

Use of modern research procedures has made it possible to observe the creep of alloys AMg6, 01570, and Al—B metal composite under room, elevated, and low temperature conditions with low stress levels significantly less than the yield strength of the test alloys. The effect of temperature and stress level on the maximum creep strain has been considered.

The stress-strain curves of polymeric composites with dispersed fillers are described with a 5% accuracy by a simple formula containing two readily determinable parameters, having a clearly physical significance. These parameters are closely related to the morphology of the composite and the degree of interaction of the filler particles with the matrix, and are therefore useful for a quantitative description of both mechanical and other physical properties of filled composites. Thus, by using one of the stress-strain diagram parameters-the heterogeneity coefficient — the heat conductivity of the composite and its dependence on the degree of filling can be readily and unequivocally determined.

Sixteen European countries participated in this WHO-IAEA intercomparison for which transmission CAP (College of American Pathologists) thyroid and IAEA-WHO liver phantoms were used. A total of 257 laboratories submitted 428 image evaluation reports. Overall results showed differences in performance between the various countries but similarities in performance for two gamma camera subgroups defined by year of manufacture, before and after 1980. A unique review of current European liver imaging practice is presented in terms of technical parameters, imaging conditions and evaluation procedures, and quality control procedures. The WHO-IAEA intercomparison demonstrated the need to establish new, or to improve the existing, quality control programmes in certain countries. However, the large number of participating laboratories, 257 compared with 70 in the previous WHO study, (Volodin et al. 1985), shows that these international studies are serving a useful purpose in promoting quality control in nuclear medicine imaging laboratories.

1. In their deformation properties the polyolefins studied are substances of a single class even under creep conditions. The principal factor which distinguishes the behavior of one polyolefin from another is the critical values of the specific volume Vo. At an identical value of V-Vo (at corresponding temperatures) the creep process is identical in polyolefins of different density.

The effect of temperature on the process of homogeneous uniaxial tension of polyethylenes of different crystallinity is analyzed by means of an analytic formula containing two constants characterizing the modulus of elasticity of the amorphous phase and structure of the polymer.