Acoustic rectification and generation of the second hypersonic harmonic in the resonant parametric soliton regime

A resonant parametric mechanism of generation of the zeroth and second harmonics of acoustic pulses propagating in a crystal involving resonance Zeeman transitions is proposed. The analysis performed has made it possible to determine the conditions for the effective acoustic rectification and excitation of the second harmonics in the resonant parametric soliton regime. The advantage of the proposed mechanism of acoustic harmonic generation over the conventional mechanism associated with the acoustic anharmonicity is that the degree of conversion is controlled by a change in the external magnetic field strength and the direction of propagation of the input pulse.     

Generalized coherent states and the statistics of two-photon lasers

Stimulated two-photon emission is proposed as a possible mechanism for the generation of “generalized coherent states”, which have useful quantum properties not available in ordinary coherent states.     

A possible quark mechanism for the saturation of nuclear matter

A nuclear matter saturation mechanism based on the quark structure of the nucleon is proposed. Nuclear matter is described by nucleons and mesons but the meson field modifies the internal quark motion and this induces a saturation mechanism. Its possible relevance for nuclear physics is studied in a schematic model where it is the only active mechanism. Though caricatural, this model provides a rather satisfactory interpretation of the nuclear matter properties.     

Surface instability induced by the singular scattering of a three-dimensional Phonon

The conditions under which a bulk phonon, incident on the surface of a semi-infinite crystal, may induce an infinite vibrational amplitude inside the surface layers, are analysed. This mechanism is proposed as a possible driving force for surface reconstruction. A numerical application given for W(100) shows that this mechanism is a better candidate, to account for surface reconstructed W(100)/c(2 × 2), than the soft phonon process.     

Oscillations of the crystallization front of adsorbed water

Relaxation oscillations of the crystallization front in a gradient temperature field have been observed for water adsorbed on a metal film deposited on a glass substrate. The metal film plays an important role in heat removal from the crystallization front and determines the existence of oscillations. A possible mechanism is proposed for the development of oscillations. It is shown that the oscillations observed are similar to the oscillations of the front of self-propagating high-temperature synthesis.     

Dissipative enhancement of the response of a bistable noisy oscillator to external driving

A study of the linear response susceptibility of a noisy bistable oscillator as a function of damping is carried out using the method of moments. It is found that this dependence, counterintuitively, has a nonmonotonic character and shows a maximum when the driving frequency is comparable to the thermal interwell hopping rate. The possible mechanism responsible for the occurrence of such dissipative sensitivity enhancement is proposed.     

Mechanism of crossover between hadron gas and QGP and the liquid property of sQGP

We raise for the first time the highly important question that the hadronization of partons one by one as assumed in current models for crossover in QCD, contradicts color confinement. A possible mechanism — molecule-like hadron aggregation — is proposed for crossover compatible with color confinement. A toy model to realize this mechanism is constructed. A kind of grape-shape quark gluon plasma (gQGP) is obtained. Pair distribution function for gQGP is calculated which exhibits the character of liquid.     

Statistical Property and Model for the Inter-Event Time of Terrorism Attacks

The inter-event time of terrorism attack events is investigated by empirical data and model analysis. Empirical evidence shows that it follows a scale-free property. In order to understand the dynamic mechanism of such a statistical feature, an opinion dynamic model with a memory effect is proposed on a two-dimensional lattice network. The model mainly highlights the role of individual social conformity and self-affirmation psychology. An attack event occurs when the order parameter indicating the strength of public opposition opinion is smaller than a critical value. Ultimately, the model can reproduce the same statistical property as the empirical data and gives a good understanding for the possible dynamic mechanism of terrorism attacks.     

The mechanism of generating fermion masses in the 8-dimensional geometric theory

The fermion sector of the 8-dimensional geometric Kaluza–Klein theory of gravi-strong interactions is considered. A mechanism of generating fermion masses via conformal (Weyl) transformations is proposed. It can be regarded as geometric analogue of the Higgs mechanism in standard gauge models. In this approach it is possible to eliminate Planck masses of particles which often appear in many Kaluza–Klein models of this type.     

The electric dipole moment of the neutron in the Kobayashi-Maskawa model

A possible mechanism for producing a neutron electric dipole moment to order G_F² in the Kobayashi-Maskawa model is proposed; the consequent order of magnitude of the dipole moment would be 10^?30 cm in units of the electric charge.     

Chiral effect of electrons from supernova outbursts in the neutron fireball model

The previously proposed idea about the possible role of neutrons released during the supernova (SN) outburst as a source of polarized electrons causing chiral asymmetry of organic molecules in interstellar gas—dust clouds is developed. A specific physical mechanism of removal of a large number of free neutrons beyond the dense SN shell via the relativistic neutron fireball with a Lorentz factor on the order of 100 is considered. Estimations show high efficiency of the chiral effect of electrons from the SN in the mechanism under consideration.     

Formation of x-ray images by the action of an optical image on a diffracting lithium niobate crystal

A possible mechanism for the formation and processing of an x-ray image using a corresponding optical image as a template is considered. The method is based on the thermal influence of light on the x-ray diffraction parameters of an LiNbO₃ crystal. A mechanism for the influence of the gradients of the temperature fields formed in the crystal on the x-ray structural parameters of the crystal is proposed. Information which permits the evaluation of some practical aspects of the application of the observed effect in technology is given. Zh. Tekh. Fiz. 67, 76–79 (September 1997)     

On the conventional QED interpretation of the GSI ee narrow resonances

A possible mechanism for the GSI e⁺e^- narrow resonances as being due to non-perturbative effects of conventional QED is proposed. An application of the quasi-potential approach discloses a set of new resonances in a system of two charged particles. Numerical calculations agree with data on e⁺e^- and pp narrow resonances. Additional new resonances are predicted for e⁺e^-, pp, e^-e^- systems.     

A simple way to prepare monolayer films of the magnetite nanocrystal by the Langmuir-Blodgett-like technique

A simple preparation of water-soluble magnetite nanoparticles protected by sodium oleate has been demonstrated. The magnetite particles are nanocrystal, which are confirmed with XRD. This kind of magnetite nanocrystal can be changed into amphiphilic particles and steadily exist at the interface of water/toluene. The amphiphilic nanocrystal can form monolayer film on hydrophilic substrate by the Langmuir-Blodgett-like technique. The results of SEM indicate that the magnetite nanocrystal film is a uniform compact monolayer film that is composed of nanosized magnetite particles. We also proposed a possible mechanism for the formation of the nanocrystal monolayer film.     

Influence of radiational damage on the background of internal friction

It is experimentally established that, with the accumulation of radiational defects arising in neutron irradiation, the high-temperature background of internal friction of iron and nickel samples decreases. A hypothesis regarding the possible mechanism of this effect is proposed. A simple expression is given for estimating the magnitude of the background.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 32–36, June, 1984.     

Preparation and Characterization of Polypyrrole Microbelt via Cotton Template

脱脂棉作为模板首次合成了聚吡咯微带. 聚吡咯微带的结构通过红外进行表征,微带的稳定性、形貌和电性能通过扫描电子显微镜、热重分析仪和四探针电导率仪进行检测. 提出了聚吡咯微带的形成机理,并且结合实验结果分析了吡咯的摩尔浓度对材料的电导率的影响.     

铜催化的乙酰苯胺间位碳氢芳基化反应机理的理论研究

通过系统的理论计算研究了Gaunt报道的一个新颖的间位选择性C-H键芳基化反应的机理. Oxycupration机理含有一个关键的Cu(III)基团和酰胺氧原子对苯环C2=C3键的反式加成步. 但是计算结果表明这个反应路径的活化能太高(>175.56 kJ/mol),所以是动力学禁阻的. 提出了一个含有关键的酰胺导向的Cu(III)-Aryl对底物C2=C3键的顺式加成步的机理,这一步是反应的决速步,也是决定产物区域选择性的一步. 这个机理的活化能与实验条件是符合的,而且这个机理预测的产物区域选择性与实验     

吡喃木糖热裂解机理的密度泛函理论研究

采用密度泛函理论理论方法 M062X/6-311++G(d,p),对吡喃木糖的热解反应机理进行了理论计算分析.针对吡喃木糖热解可能发生的化学反应共设计了九条可能的热解路径,并对各路径中的反应物、中间体和过渡态的几何结构进行了能量梯度全优化,并在梯度全优化的基础上计算了各热解反应路径的热力学和动力学参数.文中以两大类方式来设计反应路径:1)木糖首先经过过渡态TS1发生开环反应生成链状中间体2,该步的反应能垒为188.7 kJ/mol,对于中间体2共设计了五种可能的热解反应路径;2)考虑双键同时断裂的情况,木糖先发生脱水反应,接着按C-C和C-O键同时断裂的情况发生开环反应,针于这种情况共设计了四条可能的热解路径.计算结果表明,吡喃木糖热解的主要反应产物有乙醇、乙醛、糠醛、丙酮、酸类、CO_2和CO等小分子化合物.     

吡喃木糖热裂解机理的密度泛函理论研究

采用密度泛函理论理论方法M062X/6-311++G(d,p)，对吡喃木糖的热解反应机理进行了理论计算分析。针对吡喃木糖热解可能发生的化学反应共设计了九条可能的热解路径，并对各路径中的反应物、中间体和过渡态的几何结构进行了能量梯度全优化，并在梯度全优化的基础上计算了各热解反应路径的热力学和动力学参数。文中以两大类方式来设计反应路径：1）木糖首先经过过渡态TS1发生开环反应生成链状中间体2，该步的反应能垒为188.7 kJ/mol，对于中间体2共设计了五种可能的热解反应路径；2）考虑双键同时断裂的情况，木糖先发生脱水反应，接着按C-C和C-O键同时断裂的情况发生开环反应，针于这种情况共设计了四条可能的热解路径。计算结果表明，吡喃木糖热解的主要反应产物有乙醇、乙醛、糠醛、丙酮、酸类、CO2和CO等小分子化合物。