BEPCⅡ国产500 MHz超导腔运行综述

北京正负电子对撞机二期(BEPCⅡ),国产500 MHz超导腔经过紧张的安装调试于2017年10月正式投入带束流运行。首先对此国产超导腔两次降温调试的相关参数进行了监测和对比分析;其次研究了通过高功率老练的方法改善超导腔的品质因数,并实时监测超导腔老练过程中的辐射剂量;最后对超导腔的带束流运行情况进行了介绍分析。结果表明:BEPCⅡ国产500 MHz超导腔虽然放置了6年,但是状态良好,通过高功率老练能够降低超导腔的辐射剂量,改善其性能,完全满足束流运行要求。     

稀土和锕系化合物中重费密子行为

本文采用周期Anderson哈密顿量研究了稀土和锕系化合物中的重费密子行为。对f电子间库仑关联项做了平均场近似并引入自能项反映多体作用的效应。对自能项采用了单格位近似,在准粒子表象中讨论了系统的性质,通过对f电子平均占据数的自洽计算,得到了准粒子有效质量,讨论了形成重费密子的条件,以及相应的磁性的变化,并做了数值计算。所得结果与最近的实验进行了比较。 关键词：     

Statistical description of a paired nucleus with the inclusion of angular momentum

The effect of angular momentum on an excited paired nucleus has been studied. The BCS Hamiltonian, modified to include the z-projection of angular momentum has been diagonalized and expressed in terms of the quasiparticle occupation numbers. The grand partition function and all the relevant thermodynamical functions as well as the level-density expression have been derived for the general case of an arbitrary set of single-particle levels. Furthermore, the formalism has been applied to the uniform model and, whenever possible, analytical expressions have been derived. In particular the zero-temperature angular momentum dependence of the gap parameter, the critical angular momentum as well as the yrast line have been calculated. The critical temperature as a function of angular momentum, which defines the phase transition between paired and unpaired systems, has been calculated. A new effect called the thermally assisted pairing correlation, involving an increase of pairing with increasing temperature has been predicted. The completeness of the formalism as applied to spherical or deformed nuclei has been discussed.     

Synthesis,experimental and theoretical analysis,and antiproliferative activity of 2-(4-methoxyphenylamino)-2-oxoethyl methacrylate

In this study 2-(4-methoxyphenylamino)-2-oxoethyl methacrylate (MPAEMA) has been synthesized and characterized experimentally (FTIR, NMR). Theoretically, physical, electronic and vibrational properties of MPAEMA molecule have been investigated using density functional theory (DFT) calculations at B3LYP/6-311++G(d,p) basis set. Bond distance, FTIR spectrum, NMR spectra and vibrational frequencies have been carried out. The calculated FTIR and NMR spectra of the headline molecule from the DFT have been compared with the measured ones, and good results have been obtained. UV spectrum characteristics and the electronic properties, like frontier orbitals, and band gap energy of MPAEMA have also been recorded by time-dependent (TD-DFT) method based on optimized structure with different solvent. The experimental results have been compared with theoretical values. Both experimental and theoretical methods have shown that the compound has successfully been synthesized. Cytotoxicity of MPAEMA has been investigated by XTT cell proliferation assay. IC50 values of MPAEMA have been identified as 1.8 mM on HeLa cell line.     

Features of magnetic and magnetoelectric properties of rare-earth multiferroic PrFe3(BO3)4 with the singlet ground state

The features of magnetization of rare-earth multiferroic PrFe₃(BO₃)₄ with the singlet ground state have been investigated theoretically. The magnetic anisotropy of the crystal has been studied. The temperature dependences of anisotropy constants have been calculated. The phase H-T diagram has been constructed. The dependences of the behavior of magnetization vectors of magnetic sublattices on the external magnetic field have been obtained. The magnetoelectric effect has been investigated, and the dependences of polarization on the temperature and field have been found for its various orientations. The theoretical data have been compared with the experimental data and their good agreement has been established.     

Generalized classical mechanics

Generalized classical mechanics has been introduced and developed as a classical counterpart of the fractional quantum mechanics. The Lagrangian of generalized classical mechanics has been introduced, and equation of motion has been obtained. Lagrange, Hamilton and Hamilton-Jacobi frameworks have been implemented. Oscillator model has been launched and solved in 1D case. A new equation for the period of oscillations of generalized classical oscillator has been found. The interplay between the energy dependency of the period of classical oscillations and the non-equidistant distribution of the energy levels for fractional quantum oscillator has been discussed. We discuss as well, the relationships between new equations of generalized classical mechanics and the well-known fundamental equations of classical mechanics.     

Identification des propriétés thermiques de composites fibres de verre/résines thermodurcissables: Application à l'optimisation des procédés de moulage

Identification of glass fiber/thermosetting resins composites thermal properties. Application to the optimization of molding processes. A procedure has been developed to optimize molding processes of thermosetting composite materials. Three stages have been distinguished. In the first one, some thermal and kinetic properties have been measured by differential scanning calorimetry. Thermal conductivities have been identified afterwards in thick instrumented pieces, placed in a thermally regulated press. High dependences of thermal conductivities on temperature and transformation degree have been shown. Secondly, coupled heat transfers have been numerically simulated and results have been satisfactorily compared with experimental thermograms. Finally, optimization technics based on effective inverse methods have been used.These points have been illustrated with two examples : glass fiber/epoxy resin and glass fiber/polyester. Sufficient mechanical characteristics of the first one, which is cured in oven, and good surface aspect of the second, that is made by injection in heated and closed molds, had to be obtained. The results let foresee real improvement of the corresponding molding processes.     

ESR studies on Mn(II) ion in Chinese limnetic pearls

The X-band and Q-band ESR spectra of Mn(II) ion in Chinese limnetic pearls have been studied. No ESR signal of melanin-like radical has been detected. A method of theoretical treatment on ESR spectrum of Mn(II) ion has been modified. Using it, the parameters of zero field splitting D=224 Gs, E=74 Gs and E/D=0.33 for Chinese limnetic pearls with bright pearlite colour have been calculated. The computer simulation has been done using experimental ESR spectra parameters, and satisfactory results have been obtained.     

Raman Scattering by Crystals of Rare-Earth Hexaborides with Different Isotopes of Boron

Monocrystals of lanthanum hexaboride LaB₆ containing both natural boron and its isotopes ¹⁰B and ¹¹B have been produced using the solution-melt method. Polyelement hexaboride rare-earths have been grown and the corresponding ceramics have been synthesized for the first time. All these crystals have been studied by means of various techniques, generally using Raman scattering. The Raman spectra attributed to various spectral lines corresponding to nonanalyzable representations have been obtained and interpreted. Frequencies and half-widths of spectral lines have been obtained, the removal of degeneracy and the development of respective splitting of degenerate oscillations induced by defects, mainly by boron isotope inclusions, have been identified. The influence of defects on the Raman spectra has been determined.     

Bistability of a “chevron” smectic C* liquid crystal in an external electric field

The system of nonlinear equations describing a surface-stabilized ferroelectric smectic C* liquid crystal in the chevron geometry has been investigated by numerical methods in the framework of the continuum model of liquid crystals. Stable orientational and structural configurations have been studied, and the results obtained have been compared with those derived using simplified models. The height of the potential barrier separating two stable configurations has been determined, and the transition between them under the action of the external electric field has been examined. It has been demonstrated that this effect has a threshold character. The dependence of the threshold field on the film thickness has been analyzed.     

实验室黑白肖像艺术照的拍摄及制作方法的改进

本文对实验室条件下拍摄黑白艺术肖像的方法作了探讨,对放大相片的方法作了改进,给出了实验数据,并对拍摄结果作了分析和讨论。实验获得了放大尺寸的人物肖像艺术照片。     

On wave propagation in a random micropolar thermoelastic medium,second moments,and associated Green’s tensor

The couple stress theory developed by Eringen comprises granular materials as also composite fibrous materials. As such, micropolar materials present an inclusive model of composite materials. This article endeavors to study aspects of wave propagation in a random weakly thermal micropolar elastic medium. The smooth perturbation technique has been employed. The classical thermoelasticity has been used. Six different types of waves have been observed to propagate in the random interacting medium. Dispersion equations have been derived. The effects due to random variations of micropolar elastic and thermal parameters have been observed. Change of phase speed occurs on account of randomness. Attenuation coefficients for high-frequency waves have been computed. Second moment properties have been discussed with application to wave propagation in the random micropolar elastic medium. 36 + 1 components of the associated Green’s tensor have been computed. Integrals involving correlation functions have been transformed to radial forms. A special type of correlation function has been used to approximately measure effects of random variations of parameters.     

Mean-field approximation for the potts model of a diluted magnet in the external field

The Potts model of a diluted magnet with an arbitrary number of states placed in the external field has been considered. Phase transitions of this model have been studied in the mean-field approximation, the dependence of the critical temperature on the external field and the density of magnetic atoms has been found, and the magnetic susceptibility has been calculated. An improved mean-field technique has been proposed, which provides more accurate account of the effects associated with nonmagnetic dilution. The influence of dilution on the first-order phase transition curve and the magnetization jump at the phase transition has been studied by this technique.     

基于量子关联的星间链路技术研究

讨论了基于量子关联的星间链路工作频段,阐明了量子星间链路的体制优势.然后在现有星间链路研究的基础上,推导了量子星间链路的关联度和信号损耗及制备增益间的关系.并讨论了量子星间链路的网络架构.     

Zinc sulfide nanoparticles: Spectral properties and photocatalytic activity in metals reduction reactions

Formation of zinc sulfide nanocrystals in aqueous solutions of various polymers has been studied. Spectral properties of ZnS nanoparticles have been investigated, the structure of the long-wave edge of the fundamental absorption band of ZnS nanocrystals has been analyzed. It has been shown that the variation of the synthesis conditions (stabilizer nature and concentration, solution viscosity, ZnS concentration, etc.) allows tailoring of the ZnS nanocrystals size in the range of 3–10 nm. Photochemical processes in colloidal ZnS solutions, containing zinc chloride and sodium sulfite, have been investigated. It has been found that the irradiation of such solutions results in the reduction of Zn(II), the rate of this reaction growing at a decrease in the size of ZnS nanoparticles. Kinetics of photocatalytic Zn(II) reduction has been studied. It has been concluded that two-electron reduction of adsorbed Zn(II) species is the rate-determining stage of this reaction. Photocatalytic activity of ZnS nanoparticles in KAu(CN)₂ reduction in aqueous solutions has been discovered. Spectral characteristics and kinetics of ZnS/Au⁰ nanocomposite formation have been studied. It has been shown that the photoreduction of gold(I) complex is the equilibrium reaction due to the reverse oxidation of gold nanoparticles by ZnS valence band holes.     

Equilibrium configurations and phase transitions in dipole lattices

Two-dimensional square and hexagonal lattices of magnetic dipoles with the number of rows 1–4 have been studied. Based on the numerical analysis, equilibrium stable domain configurations, including the minimum number of lattice dipoles, have been revealed; the conditions for the creation and destruction of domains have been determined; and their associated changes in the magnetic moment of the lattice and in the energy of the dipole interaction have been found. The conditions for the occurrence of phase transitions that change the configuration of the lattices have been investigated and the conditions for unidirectional propagation of the front of the phase transition have been established. A comparative analysis of different square and hexagonal lattices has been performed in terms of the specific features of the formed domains and the observed orientation phase transitions.     

Simulation of chemical adsorption of hydrogen by carbon nanotubes

The hydrogen chemical adsorption on a single-walled carbon nanotube (6, 6) has been studied by quantum-chemical computer simulation. Different variants of hydrogen coverage of the nanotube have been considered, and the dependences of the adsorption energy and the nanotube strain energy on the coverage density have been found. In addition, the adsorption has been considered on both the outer and inner surfaces of the nanotube wall. It has been established that some adsorption conformations are unstable, which leads to fracture of the nanotubes.     

CCD在光学镀膜宽带膜厚监控系统中的应用研究

讨论了 CCD的主要特性及对宽带膜厚监控系统的影响 ,介绍了典型的 CCD数据采集系统。建立了一套基于 CCD的宽带膜厚监控系统 ,并对该系统进行了光谱标定及光谱补偿 ,给出了提高信噪比及减小非线性影响的处理方法。     

Modifying a graphene layer by a thymine or a uracil nucleobase: DFT studies

The hybridizations of a graphene layer by a thymine and a uracil nucleobase have been investigated by performing density functional theory (DFT) calculations. The isolated and hybrid structures have been firstly stabilized to reach the minimum energy and the electronic properties have been subsequently evaluated for the optimized structures. The structural and atomic scale parameters indicated that the tip of graphene is important in determining the properties of new hybrids. Moreover, different effects of thymine and uracil nucleobases have been identified in the hybrid structures. Quadrupole coupling constants have been evaluated to characterize the atomic scale properties, in which the most notable effects of hybridizations have been observed for the atoms close to the linking regions whereas negligible effects have been seen for other atoms.     

An infrared spectroscopic study of tert-butyl peroxoesters

The infrared spectra of peroxoesters based on tert-butyl hydroperoxide and aliphatic acids, tert-butyl peroxobenzoate, and their nonperoxo analogs have been studied. The observed absorption bands have been assigned to the vibrations of individual bonds, the characteristic features of the structure of the peroxoester molecules have been investigated, and the force constants have been calculated. A set of absorption bands suitable for the identification and analysis of tert-butyl peroxoesters based on aliphatic acids has been proposed.