Effects of vitamin A on the activity of glutathione system enzymes of liver detoxication after administration of nitroso-compound precursors to rats

The activity of glutathione system enzymes exposed to nitroso-compound (NC) precursors in small doses for 12 months and preliminary injection of vitamin A have been studied. The histo- and biochemical examinations have revealed a pronounced increase in the enzyme activity exposed of NC precursors and a slight increase when injecting preliminary vitamin A.     

Adsorption of sodium atoms on the (111) germanium surface

Within the framework of the Anderson-Newns model and taking into account the dipole-dipole repulsion and the exchange interaction, the work-function variation caused by the adsorption of sodium atoms is calculated for the (111) germanium surface. The obtained results agree well with the experimental data. However, the suggested model fails to describe adequately the Na/Si(111) adsorption system.     

Electromigration Effect on Vacancy Islands Nucleation on Si(100) Surface during Sublimation

Semiconductors - By means of in situ ultrahigh vacuum reflection electron microscopy, the nucleation of vacancy islands on wide terraces of the Si(100) surface is investigated. The temperature...     

Effect of modifiers of microsomal enzymes on the enzymatic denitrosation of dialkyl-N-nitrosamines

The antioxidant butyl-hydroxytoluene has been shown to increase denitrosation of some dialkyl-N-nitrosamines by the liver microsomes of different lines of rats and to protect against diethyl-N-nitrosamine toxicity. 3-Methylcholanthrene, while decreasing denitrosation of diethyl-N-nitrosamine, increased its toxic effect. This data suggested that enzymatic denitrosation is an effective pathway for the inactivation of dialkyl-N-nitrosamines.     

MgO在含铅PTCR陶瓷中的作用

研究了ＭｇＯ加入到含铅ＰＴＣＲ陶瓷中的作用。用碱土金属Ｍｇ２＋对（Ｂａ，Ｐｂ）ＴｉＯ３掺杂，在１２４０～１３００℃空气中烧结，获得工艺性能良好，烧结温度较低，电性能优良的ＰＴＣＲ陶瓷材料。试验结果表明：ＭｇＯ的加入降低了含铅ＰＴＣＲ陶瓷的烧结温度，抑制了ＰｂＯ的挥发。     

Effect of the Crystallographic Orientation of GaSb Films on Their Structural Properties during MBE Heteroepitaxy on Vicinal Si(001) Substrates

Semiconductors - GaSb films are grown by molecular-beam epitaxy using AlSb/As/Si transition layers on vicinal Si(001) substrates miscuted by 6° in (111) plane direction. The effect of GaSb...     

(Ba,Co,Nb)掺杂SnO2压敏材料电学非线性的研究

通过对样品的伏安特性，晶界势垒的测量和分析，研究了BaCO3对新型(Co，Nb)掺杂SnO2压敏材料微观结构和电学性质的影响。晶界势垒高度测量表明，SnO2晶粒尺寸的迅速减小是压敏电压急剧增高的原因。对Ba含量增加引起SnO2晶粒减小的根源进行了解释。掺杂x(BaCO3)=0．4％的SnO2压敏电阻击穿电压为最小(140V／mm)；掺杂x(BaCO3)-0．8％的SnO2压敏电阻具有最高非线性系数(α=19．6)，最高的势垒电压(ψB=1．28eV)。     

A tutorial on the Digital Audio-Visual Council (DAVIC)standardisation activity

International compatibility for the distribution of video and multimedia content through communication networks is something which has thus far not been achieved. New digital systems provide an opportunity for global compatibility between audio and video transmission and full multimedia communications incorporating text, data, audio, still and moving video in an interactive environment. It is with this commercial opportunity in mind that the Digital Audio-Visual Council (DAVIC) has been created and its first standards, DAVIC1.0 and 1.1, have been released. In Europe the European Commission is actively supporting the development of DAVIC through its Advanced Communications Technologies and Services (ACTS) initiative but DAVIC has widespread international support     

Effect of the annealing temperature on erbium ion electroluminescence in Si:(Er,O) diodes with (111) substrate orientation

The influence of the temperature of secondary annealing, stimulating the formation of optically and electrically active centers, on the erbium ion electroluminescence (EL) at λ≈1.54 μm in (111) Si:(Er,O) diodes has been studied. The diodes were fabricated by the implantation of 2.0 and 1.6 MeV erbium ions at doses of 3×10¹⁴ cm⁻² and oxygen ions (0.28 and 0.22 MeV, 3×10¹⁵ cm⁻²). At room temperature, the EL intensity in the breakdown mode grows with the annealing temperature increasing from 700 to 950°C. At annealing temperatures of 975–1100°C, no erbium EL is observed in the breakdown mode owing to the formation of microplasmas. The intensity of the injection EL at 80 K decreases with the annealing temperature increasing from 700 to 1100°C. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 35, No. 10, 2001, pp. 1224–1227. Original Russian Text Copyright ? 2001 by Sobolev, Emel’yanov, Nikolaev.     

Effect of As overpressure on Si-doped (111)A, (211)A and (311)A GaAs grown by molecular beam epitaxy

Si-doped (111)A, (211)A and (311)A GaAs samples grown by molecular beam epitaxy (MBE) at different As over-pressures have been studied. Hall effect measurements have revealed that the doping changes from p- to n-type when the As pressure is increased. The transition As pressure is lower for the (211)A than for the (311)A surfaces. Photo-luminescence measurements have shown that, when the As pressure is increased, arsenic vacancy defects are changed into pairs of Ga vacancy and Ga antisite defects. These results are explained by considering the orientation dependence of the surface bonding and the kinetics of the MBE growth process.     

Effect of Carrier-Doping on the Thermoelectric Properties of Narrow-Bandgap (Fe,Ru)Ga3 Intermetallic Compounds

We have focused on the binary narrow-bandgap intermetallic compounds FeGa₃ and RuGa₃ as thermoelectric materials. Their crystal structure is FeGa₃-type (tetragonal, P4₂/mnm) with 16 atoms per unit cell. Despite their simple crystal structure, their room temperature thermal conductivity is in the range 4–5–W–m^?1–K^?1. Both compounds have narrow-bandgaps of approximately 0.3–eV near the Fermi level. Because their Seebeck coefficients are quite large negative values in the range 350–<–|S _373K|–<–550–μV–K^?1 for undoped samples, it should be possible to obtain highly efficient thermoelectric materials both by adjusting the carrier concentration and by reducing the thermal conductivity. Here, we report the effects of doping on the thermoelectric properties of FeGa₃ and RuGa₃ as n and p-type materials. The dimensionless figure of merit, ZT, was significantly improved by substitution of Sn for Ga in FeGa₃ (electron-doping) and by substitution of Zn for Ga in RuGa₃ (hole-doping), mainly as a result of optimization of the electronic part, S ² σ.     

Reduced indium incorporation during the MBE growth of In(Al,Ga)As

A reduction in indium incorporation during the MBE growth of In(Al,Ga)As at moderate temperatures has been observed by RHEED oscillations and confirmed by X-ray diffractometry. The cause is believed to be surface segregation which can result in an under-estimate of the indium flux calculated from InAs RHEED oscillations, and the growth under non-optimum conditions of In-deficient In(Al,Ga)As with poor morphology.<>     

A muscle fatigue index based on the relationship between precedingbackground activity, and myotatic reflex response (MRR)

A new index of muscular fatigue was developed using the myotatic reflex response (MRR). The MRR of masseter muscles is evoked by periodical mechanical chin tapping during clenching. The MRR waveform is composed of somewhat synchronized action potentials of muscle fibers. We estimate the change of the MRR waveform due to fatigue using the instantaneous frequency pattern (IFP) with the Hilbert transform. As a result, the features of IFP were different from the monotonic changes that have been observed by the conventional fatigue indices. That is, a plateau IFP was observed ahead of considerable fatigue, whereas the IFP showed a monopeak pattern during other phase of an exercise. Also, the relationship between the preceding background mean power frequency and the instantaneous frequency around the first part of the MRR waveform was nonlinear during the whole process of fatigue. These features may allow us to estimate the degree of fatigue at each time instant. Although the details have not yet been solved, by using the computer simulations one of them seemed to be the alteration of the dominant frequency components. The dominant frequency components may be related to the active muscle fiber types.     

PbO-B2O3-CuV2O6掺杂对(Pb,Ca,La)(Fe,Nb)O3陶瓷微波介电性能的影响

研究了PbO3-CuV2O6(PBC)玻璃对(Pb,Ca,La)(Fe,Nb)O3(PCLFN)陶瓷微波介电性能的影响.当纯PCLFN陶瓷在1150℃烧结,介电常数εr=103,品质因数与频率之积Qf=5640 GHz,频率温度系数τf=7.1×10-6/℃.PBC玻璃添加剂能降低PCLFN陶瓷的烧结温度到1 050℃左右,同时能保持良好的介电性能.随着PBC玻璃添加量的质量分数从1.0%增加2.0%,陶瓷的Qf值减小.掺杂ω(PBC)=1%玻璃、在1 050℃烧结的陶瓷样品,能获得良好的微波介电性能为Qf=5 392 GHz,τf=8.18×10-6/℃,εr=101.     

Effect of Temperature on the Morphology of Planar GaAs Nanowires (Simulation)

Semiconductors - The self-catalyzed growth of planar GaAs nanowires is analyzed using the lattice kinetic Monte Carlo model. Vapor–liquid–solid nanowire growth on (111)A and (111)B...     

Effect of an arsenic flux on the molecular-beam epitaxy of self-catalytic (Ga,Mn)As nanowire crystals

The effect of an arsenic flux on the growth rate of self-catalytic (Ga,Mn)As nanowire crystals is studied. It is shown that, at low arsenic fluxes, nanowire-crystal growth is limited by the crystallization rate of the material below the droplet. However, at high arsenic fluxes, the growth kinetics are controlled by gallium transport into the droplet. It is experimentally demonstrated that, at low arsenic fluxes, the dependence of the nanowire length on the nanowire diameter is a steadily increasing function adequately described by Givargizov-Chernov’s model. At the same time, a steadily decreasing diffusion dependence is observed at high arsenic fluxes.     

Effect on Ordering of the Growth of GaInP Layers on (111)-GaAs Faces

GaInP, an essential material for multijunction structures of III–V compounds for solar cells, can achieve better photovoltaic responses when grown on (111)GaAs faces, due to the large internal electric fields generated by the off-diagonal strain. In this work, we explored metalorganic chemical vapor deposition growth of GaInP layers on (001)-, (111)Ga-, and (111)As-GaAs substrates, using different phosphine flow rates. The structural and optical properties of the layers have been studied by micro-Raman spectroscopy, microphotoluminescence, and cathodoluminescence. Problems such as composition control, growth rate, and the presence of ordered phases are addressed.     

Effect of In Situ Thermal Cycle Annealing on GaN Film Properties Grown on (001) and (111) GaAs, and Sapphire Substrates

The effect of in-situ thermal cycle annealing (TCA) has been investigated for GaN growth on GaAs(lOO), GaAs(111) and sapphire substrates. X-ray diffractometry (XRD) and surface morphology studies were performed for this purpose. Enhanced cubic phase characteristics were observed by employing annealingfor GaN layers grown on (001) GaAs. The thickness of the layer subject to annealing is critical in determining the phase of the subsequently grown layer. Thin initial layers appear to permit maintenance of the cubic phase characteristics shown by the substrate, while hexagonal phase characteristics are manifested for thick initial layers. Higher temperature of annealing of thick pre-annealed layers results in changes from mixed cubic/hexagonal phase to pure hexagonal phase. Growth on GaAs(111) substrates showed single cubic phase characteristics and similar enhancement of crystal quality by using TCA as for layers on GaAs(OOl). Micro-cracks were found to be present after TCA on GaAs(lll) substrates. Thermal cycling also appears to be beneficial for layers grown on sapphire substrates.     

Effect of benzo(a)pyrene on soil microbiocenosis

The experimental studies have shown that benz(a)pyrene being in the soil affects the formation of soil microbiocenosis and biological activity of soils.