Heat of formation of solid solution of alkali halides

Based on a semicontinuum model, the electrostatic, the polarisation, and the repulsive energy change of a lattice is calculated numerically, as a function of the relaxation of the nearest neighbouring ions of a substitutional impurity in an alkali halide crystal. It is found that for a particular displacement, the total energy change of the lattice is a minimum. Thus the heat of formation of a dilute solid solution is obtained. Here, we report calculations on the heat of formation of the following systems-Na⁺ in LiCl, Li⁺ in NaCl, K⁺ in NaCl, Na⁺ in KCl, Rb⁺ in NaCl, Na⁺ in RbCl, F^? in NaCl, Cl^? in NaF. Br^? in NaCl and Cl^? in NaBr.     

Simulation of the superlinearity of dose characteristics of thermoluminescence of anion-defective aluminum oxide

The specific features revealed in the superlinearity of dose dependences of thermoluminescence of anion-defective aluminum oxide single crystals have been considered theoretically in terms of the model of an interactive trap system. The model explains the decrease in the degree of superlinearity at a low heating rate, as well as with an increase in the dose increment, the occupancy of deep traps, and the sensitivity of the crystals to radiation due to the increase in the concentration of luminescence centers. The obtained results indicate a widening of the possibilities of the model for interpreting experimental data in the investigation of the dose characteristics of thermoluminescence of the studied crystals.     

Model of stochastization of the oscillatory regime of superradiance

Based on the analysis of the experimental data on the observation of the fluorescence and superradiance of praseodymium ions in a matrix of lanthanum trifluoride, a model of superradiance of three-level radiators with two close upper levels is developed in the mean-field approximation and studied. The uppermost level is coherently pumped by an ultrashort pulse of electromagnetic field, after which the excitation is transferred to the close energy level, from which the superradiance transition occurs to the lower level. In limiting cases, the considered model is reduced to the known models of superradiance and describes the ordinary regimes of monopulse and multipulse (oscillatory) superradiance. However, in a certain region of parameters, the model under discussion describes such a multipulse superradiance signal in which electromagnetic field spikes composing it follow in time with random intervals and amplitudes, so that the regime of regular chaotic dynamics is demonstrated in a single superradiance signal. In a certain time interval, the proposed model can be described by the Lorenz equations with the parameters corresponding to the chaotic dynamics of spikes composing the superradiance signal. The presented results of the numerical simulation of the model equations qualitatively correspond to the picture of stochastic pulsations observed experimentally.     

Influence of angles of incidence of laser radiation on the generation of fast ions

It was established experimentally that the number and energy of fast ions in laser plasma increased with increasing angle of focusing laser radiation onto a flat target. Numerical calculations showed that the increase in angle of focusing brought the mean angle of incidence of laser radiation closer to the optimal angle corresponding to the maximal efficiency of the resonance absorption mechanism and, as a result, increased the fraction of absorbed laser energy in the energy of fast electrons and increased the number of fast electrons. In turn, the increase in the energy and number of fast electrons resulted in an increase in the number of fast electrons involved in the formation of a self-consistent electric field at the target edge and led to the growth of the field strength, which, eventually, was the reason for the increase in the number and energy of fast ions.     

在磁场作用下水的特性的变化和它的变化机理

我们研究了在磁场作用下水的光学性质和电学性质等的变化,实验发现它们的这些特性和未受磁场作用的水有重大改变特别是在红外光谱和拉曼光谱中的变化更加明显,这种现象就称为水的磁化。我们从水的中红外光谱得知在3000~3800 cm-1的范围内有奇特的六个峰值存在,从水分子结构和红外光谱的特性出发了解到它们分别代表了自由水分子的OH键的对称与反对称的振动,众多水分子通过氢键连接而成的线性链和环形链的OH键的对称与反对称振动,于是从这个实验我们看到了在这个水中存在有众多水分子结合成的环形氢键链的存在。我们用水分子的极化特性,一阶相变的特性和实验进一步证实了这些环形链的客观存在,根据质子或氢离子在氢键系统中传递理论得知在磁场的罗仑兹力作用下处于水中环形氢键链中质子能够进行传导产生环形电流.这些环形电流象一个分子电流或是个小磁体,它们能彼此相互作用或与外加磁场相互作用,从而改变了水分子的分布和结构状态,导致了水的一些特性的变化,这就是水的磁化的分子机理,我们用这个机理解释了我们从实验中所发现的磁处理过的水的特性如饱和效应和记忆效应等,因此这是非常有趣的实验和现象.     

Calculation of energy characteristics of adsorption of metals

Within the framework of the electron density functional, a technique is developed for calculation of the adsorption energy and variation in the electron work function for metal substrates due to metal atom adsorption. The corrections to the local density approximation, which are associated with non-uniformity of the electron density in the subsurface region and discontinuous ion charge distribution over the crystal lattice sites, are included into consideration. It is shown that adsorption of alkali metal atoms results in lower electron work function, while that of transition metals (cobalt, iron, and chromium) might both decrease and increase the electron work function. Formation of a variety of adsorption structures from metal atoms depending on the temperature is discussed. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 14–19, July, 2007.     

Optimization of the calculations of the electronic structure of carbon nanotubes

A method is proposed for calculating the electronic structure and physical properties (in particular, Young’s modulus) of nanotubes, including single-walled carbon nanotubes. This method explicitly accounts for the periodic boundary conditions for the geometric structure of nanotubes and makes it possible to decrease considerably (by a factor of 10–10³) the time needed to calculate the electronic structure with minimum error. In essence, the proposed method consists in changing the geometry of the structure by partitioning nanotubes into sectors with the introduction of the appropriate boundary conditions. As a result, it becomes possible to reduce substantially the size of the unit cell of the nanotube in two dimensions, so that the number of atoms in a new unit cell of the modified nanotube is smaller than the number of atoms in the initial unit cell by a factor equal to an integral number. A decrease in the unit cell size and the corresponding decrease in the number of atoms provide a means for drastically reducing the computational time, which, in turn, substantially decreases with an increase in the degree of partition, especially for nanotubes with large diameters. The results of the calculations performed for carbon and non-carbon (boron nitride) nanotubes demonstrate that the electronic structures, densities of states, and Young’s moduli determined within the proposed approach differ insignificantly from those obtained by conventional computational methods.     

航天器空间静电效应研究进展

航天器在轨运行过程中面临的空间环境复杂多变,高能电子、等离子体环境、低气压、大温差等环境因素会引起航天器发生静电带电和放电效应,对航天器的安全运行造成严重影响。基于国内外试验数据和案例分析了空间环境引起的航天器故障,从数值仿真软件、地面模拟技术、强场诱发放电以及防护技术等方面介绍了空间环境作用下航天器充放电效应研究进展,对我国目前研究差距和未来研究方向进行了展望。研究表明：我国航天器充放电效应防护技术研究取得了进步,下一步重点针对空间站、深空探测、探月工程等新任务,进一步拓展空间环境作用下航天器充放电效应机理和防护新技术研究,为提升我国航天器的安全性和可靠性提供技术支撑。     

One method of describing the transfer of energy of the kinetic degrees of freedom to the electronic states of molecules

An analysis is made of the process of transferring the kinetic energy of highly excited vibrational terms of a molecule to an electronic state of one of its constituent atoms. This is done by utilizing a wave equation for the effective wave functions of the atom, corresponding to mixed states, in which the velocity of this atom relative to the neighboring atoms in the molecule enters as a parameter. An expression is found for the excitation probability in the case of a hydroge-like atom in the resonant approximation. State University, Omsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 20–26, September, 1996.     

Current status of equation of state of nuclear matter

The equation of state (EOS) of symmetric nuclear matter (SNM) is a very important ingredient in the study of various phenomena of interest in nuclear physics and astrophysics. Accurate assessment of the value of the SNM incompressibility coefficient, K, which is directly related to the curvature of the EOS, is needed to extend our knowledge of the EOS in the vicinity of the saturation point. We review the current status of K as determined from experimental data on compression modes in nuclei using the mean-field-based random-phase approximation. The text was submitted by the authors in English.     

Effect of irradiation on the laws of annealing of impurity hardening of NaCl crystals

Studies were carried out on crystals containing various types of impurity: Ca²⁺, a hole-acceptor impurity, which dissolves well in NaCl; and Pb²⁺, an electronacceptor impurity, which dissolves poorly in NaCl. For the first time when doped crystals were annealed softening was observed to occur as a result of irradiation with soft x-rays prior to the annealing. The microhardness of irradiated doped NaCl crystals drops below the value that corresponds to the unannealed unirradiated sample. This effect is more pronounced in NaCl:Pb. It is postulated that the weakening effect is due to the breakup of impurity complexes. This assumption is supported by the results of studies on the laws governing the annealing of dislocation structures about the imprints of an indenter. These laws are shown to depend on the type of impurity: processes of dislocation polygonization were observed in NaCl:Ca crystals and the dislocation distribution was random in NaCl:Pb crystals. Pre-irradiation of the latter caused dislocations to be built in and polygonization to appear. Evidently, by breaking up impurity complexes in NaCl:Pb crystals x-ray irradiation brings the state of the impurity in them closer to that in NaCl:Ca.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 57–62, August, 1988.     

Formation of a crystallographically oriented colony of products of eutectoid decomposition in the process of plastic deformation of steel by drawing

Methods of transmission electron microscopy and EBSD analysis have been used to study the evolution of the structural state of a eutectoid steel in the process of plastic deformation by drawing. It has been established that the reason for steel embrittlement is in the formation in the former grains of the high-temperature phase of a specific element of the structure, namely, a crystallographically oriented colony of products of eutectoid decomposition, including a conglomerate of morphological colonies with a common orientation along the cleavage plane of one of the constituents of the eutectoid. The process of its formation means multiple changes in the scale of the structure and, therefore, increase in the temperature threshold of the material brittleness.     

墙壁反射中子对脉冲堆波形的影响

墙壁的反射中子会对快脉冲堆的波形产生明显的影响.堆芯中子泄漏后,经过墙壁的反射有一定的概率返回堆芯,由于能量的差异,泄漏中子的返回时间是一个连续的分布.传统的双区模型只考虑了相互作用概率,而没有时间信息,尽管可以很好地解决稳态问题,而无法解决瞬态问题.本文采用等效的方法,把泄漏中子等效为时间相关的堆芯本征源,建立了含有反射效应的时间关联双区模型.求解得到的脉冲波形与CFBR-Ⅱ的实验结果一致,从而合理解释了脉冲波形后沿衰减变慢和坪功率提高的实验现象.     

核磁共振技术在物质表面性质表征领域的新应用

核磁共振(nuclear magnetic resonance)技术具有快速、精确、分辨率高等优点,并已不断成熟成为土壤分析、物质结构鉴定、食品分析和医学成像等领域重要的研究分析手段。本文通过介绍利用NMR技术研究液相环境中高分子聚合物在颗粒表面(主要为SiO₂颗粒)的吸附、解吸及扩散等行为和利用NMR技术研究受污染土壤中水的摄取过程及土壤润湿性两大方面,综述了NMR技术在物质表面性质表征领域的重要应用,展现了NMR技术在高分子材料和环境领域中独特的重要作用。重点介绍基于NMR技术的Acorn比表面分析仪能够直接测定液相环境中物质的弛豫时间,反映物质的表面性质和结构特征,为解释污染物环境行为提供数据支持从而在环境领域发挥重要作用,展现出Acorn比表面分析仪相比于传统BET法在测量环境和测量时间等方面的优越性,尤其是Acorn比表面分析仪可以反映液相环境中物质的表面性质和结构特征的重要特性,解决了传统BET法无法直接获得液相环境中物质的比表面积信息的难题,是液相环境中NMR技术在物质表面性质表征领域的新突破。对Acorn比表面分析仪在制药、化妆品材料和电子产品等方面的应用进行了分析,并在土壤有机质、药物和天然产物检测等方面对NMR技术的应用进行了展望。     

Estimation of the states of an MC-stream of events in the presence of measurement errors

A special case of streams with rate jumps, or so-called MC-streams, is investigated. A change in the rate of MC-streams requires a change in the operating regime of the recording apparatus in physical experiments, making it necessary to estimate the states (or parameters) of these streams of events. An algorithm for estimating the states of an MC-stream of events in the presence of errors of measurement of the event times is proposed, the problem of optimizing the parameters of the algorithm in the sense of minimizing the decision-making error probability is solved, and the results of numerical calculations on a computer are given.V. V. Kuibyshev State University, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 67–85, December, 1993.     

物联网技术研究进展

目前,物联网因其巨大的应用前景而受到各国政府、学术界和工业界的广泛重视,成为国内外信息通信领域的新研究热点;物联网产业己经成为推动世界经济增长的重要新兴产业,我国已将物联网的发展列为信息产业发展的下一个战略高点;首先总结了物联网的国内外研究进展,其次对物联网的概念、实现原理与体系结构进行了分析,归纳了物联网涉及的关键技术,然后介绍了物联网的一些典型应用,最后指出了物联网进一步研究的方向以及制约国内物联网发展的问题及解决对策。     

Effects of noise on detection of amplitude increments of sinusoidal vibration of the skin.

Vibrotactile thresholds for detecting a 300-Hz signal in the presence of both a 300-Hz sinusoidal pedestal and a background noise were measured as a function of the amplitudes of the pedestal and noise. Threshold increased monotonically as a function of the amplitude of the noise, but was a nonmonotonic function of the amplitude of the sinusoidal pedestal. Negative masking, in which the pedestal facilitated detection of the test stimulus, was observed in the absence of background noise and in the presence of subthreshold background noise when the pedestal was near or below threshold. Negative masking disappeared when the experiment was conducted in the presence of moderately intense to intense background noise. The results are consistent with a peripheral high-energy threshold for taction.     

Pitch of components of complex tones

Subjects made pitch matches to individual components in complex tones consisting of either the 4th to 7th or the 1st to 7th harmonics of a 200-Hz fundamental. All components were at equal levels (either 31-, 51-, or 71-dB SPL per component) and the matching pure tone was equal in level to the component being matched. Attention was drawn to the component to be matched either by giving the matching tone an initial frequency close to that of the component (standard condition) or by suppressing and then introducing the component (emergent condition). The pitch matches did not differ significantly for the two conditions, and did not change with overall level. For two subjects, matches to components in the context of the complexes were very close to matches obtained for the components presented in isolation. For a third subject, matches in context were shifted slightly upwards for the lowest component, and downwards for the highest component. A control condition showed that subjects were able accurately to match a small shift in frequency of one component in a four-tone complex. An adaptive forced-choice method described by Jesteadt [Percept. Psychophys. 28, 85-88 (1980)] was also used to estimate the pitches of the components. A very slight bias was apparent in the results, but the pitches of components in context were again found to be very close to those of components in isolation.     

Measurement of the fission moment of inertia of medium mass nuclides

Measurements have been made, by means of mica nuclear track detectors, of the distributions in tracklength and the angular distributions with respect to the beam direction for the fission fragments from the systems Ag, Te and Au plus 80-MeV alpha particles. Analysis of the tracklength distributions indicated that, in each case, full momentum transfer from the incident projectile characterized those interactions that led to fission. Angular-momentum dependent statistical model calculations for the decay of the respective compound nuclei then provided information on fission-evaporation competition in the de-excitation processes, and in particular the distribution in nuclear temperature and angular momentum at which the fission events took place. This information was then employed in the analysis of the measured fission fragment angular distributions, and to extractK ₀ ² values. From these, the moments of inertia of the fission saddle point shapes were calculated, and the results are in good agreement with theoretical estimates.     

The influence of macromolecular polymerization of spin-lattice relaxation of aqueous solutions

The docking or polymerization of globular proteins is demonstrated to cause changes in proton NMR spin-lattice (T1) relaxation times. Studies on solutions of lysozyme, bovine serum albumin, actin, and tubulin are used to demonstrate that two mechanisms account for the observed changes in T1. Polymerization displaces the hydration water sheath surrounding globular proteins in solution that causes an increase in T1. Polymerization also slows the average tumbling rate of the proteins, which typically causes a contrary decrease in T1. The crystallization reaction of lysozyme in sodium chloride solution further demonstrates that the "effective" molecular weight can either decrease or increase T1 depending on how much the protein is slowed. The displacement of hydration water increases T1 because it speeds up the mean motional state of water in the solution. Macromolecular docking typically decreases T1 because it slows the mean motional state of the solute molecules. Cross-relaxation between the proteins and bound water provides the mechanism that allows macromolecular motion to influence the relaxation rate of the solvent. Fast chemical exchange between bound, structured, and bulk water accounts for monoexponential spin-lattice relaxation. Thus the spin-lattice relaxation rate of water in protein solutions is a complex reflection of the motional properties of all the molecules present containing proton magnetic dipoles. It is expected, as a result, that the characteristic relaxation times of tissues will reflect the influence of polymerization changes related to cellular activities.