SH波作用下界面任意形状孔洞附近的动应力集中

采用Green函数和复变函数法求解了平面SH波在界面任意形状孔洞上的散射问题.首先,取含有任意形状凹陷的弹性半空间,在其水平表面上任意一点承受时间谐和的反平面线源荷载作用时的位移场作为Green函数.然后,按契合方式构造出界面任意形状孔洞对SH波的散射模型,利用所得Green函数按界面位移连续条件建立求解问题的定解积分方程组,求解界面孔附近的动应力集中系数.最后,给出了界面上椭圆孔和方孔边缘动应力集中系数的数值结果,并讨论了不同介质参数和孔洞形状对孔附近动应力集中系数的影响.     

孔边裂纹对SH波的散射及其动应力强度因子

采用Ｇｒｅｅｎ函数法研究任意有限长度的孔边裂纹对ＳＨ波的散射和裂纹尖端场动应力强度因子的求解．取含有半圆形缺口的弹性半空间水平表面上任意一点承受时间谐和的出平面线源荷载作用时位移函数的基本解作为Ｇｒｅｅｎ函数,采用裂纹“切割”方法并根据连接条件建立起问题的定解积分方程,得到动应力强度因子的封闭解答．最后给出了孔边裂纹动应力强度因子的算例和结果,并讨论了圆孔的存在对动应力强度因子的影响     

Phonon-polariton and band structure of electro-magneto-acoustic SH wave propagation oblique to the periodic layered piezoelectric structures

Electro-magneto-acoustic SH waves propagating oblique to the periodic layered piezoelectric structures are studied under the coupling of the acoustic wave and the electromagnetic wave. Band structures of the so-called piezoelectric superlattice and phononic/photonic crystal are given both at acoustic frequencies and at optical frequencies. For the periodic layered piezoelectric structures, phonon-polaritons (the coupling modes of the phonons and photons) are found not only happening near the center of the Brillouin zone (in the long-wavelength limit) at acoustic frequencies, but also being able to appear in the whole Brillouin zone at optical frequencies. Appearing of these phonon-polaritons may provide a way to design a new type of acousto-optic devices.     

固-固无限周期声子晶体中SH波全反射隧穿的谐振理论

利用边界条件推导出SH波在一维固-固声子晶体中的转移矩阵, 得出一维固-固无限周期声子晶体中SH波的色散关系. 通过建立一维固-固无限周期声子晶体的谐振腔模型并利 用共振条件得出SH波的全反射隧穿的波长公式. 利用波长公式研究了SH波全反射隧穿的波长变化规律, 其结果与色散法一致. 解释了一维固-固无限周期声子晶体中SH波的全反射隧穿效应产生的原因. 关键词： 声子晶体 SH波 全反射隧穿 谐振理论     

Synthesis,Crystal Structure and Anticancer Property of （Z）-N-（4-Bromo-5-ethoxy-3,5-dimethyl-furan-2（5H）-ylidene）-4-methylbenzenesulfonamide

The novel title compound(Z)-N-(4-bromo-5-ethoxy-3,5-dimethylfuran-2(5H)-yli-dene)-4-methylbenzenesulfonamide 1(C15H18BrNO4S) has been unexpectedly synthesized by the aminohalogenation reaction of ethyl 2-methylpenta-2,3-dienoate with TsNBr2,and characterized by mp,IR,1H NMR,EIMS,ESIHRMS and single-crystal X-ray diffraction.It crystallizes in mono-clinic,space group P21/c with a = 11.714(5),b = 14.106(5),c = 10.402(4) ,β = 97.298(8)°,V = 1704.9(12) 3,Mr = 388.27,Z = 4,Dc = 1.513 g/cm3,μ(MoKα) = 2.549 mm-1,F(000) = 792,the final R = 0.033 and wR = 0.062 for 3098 observed reflections(Ⅰ 2σ(Ⅰ)).     

SH wave propagation in magnetic–electric periodically layered plates

In this paper, dispersive behavior and band structure of SH waves in magnetic–electric (ME) periodically layered plate are investigated by the transfer matrix method. Two kinds of unit cell form, one is piezoelectric (PE)/piezomagnetic (PM)/PE, and the other is PM/PE/PM, are considered in detailed. A peculiar case of the generalized single-celled plate is first presented and then the multi-celled periodical layered plates for discussion on the propagation behaviors and the band characteristics of SH waves, respectively. The effects on dispersive curves of four kinds of ME boundary conditions at the free surface of plates are discussed. Numerical examples for phase velocities or frequencies all show that the zero-order mode is non-dispersive both for single-celled and multi-celled periodically layered plates. The high modes of dispersive curves tend to the shear wave velocity of the slower sub-layer as frequencies increase both for these two structures. The frequency pass-band and frequency band gaps appear in multi-layered ME periodically layered plates. Electrical and magnetic boundary conditions, respectively, determine the dispersive curves for SH waves in the PE/PM/PE and PM/PE/PM periodically layered plates.     

The First Photochemical In Situ Production of Ti‐Based Nanoparticles: A SH2 Strategy Using Bis(cyclopentadienyl)titanium Dichloride (Cp2TiCl2)

Bis(cyclopentadienyl)titanium dichloride (Cp₂TiCl₂) is a high performance additive under UV light activation for both i) radical photopolymerization reactions (when added to a Type I photo­initiator such as 2,2‐dimethoxy‐2‐phenylacetophenone, the oxygen inhibition is reduced) and ii) a concomitant in situ photoinduced and oxygen mediated formation of Ti‐based nanoparticles (diameters ranging from 45 to 220 nm). The photochemical properties of Cp₂TiCl₂ are investigated by steady state photolysis and electron spin resonance, and its photoinitiation ability checked. The nanoparticles (NPs) are well characterized by transmission electron microscopy. The high reactivity of Cp₂TiCl₂ under air is ascribed to a bimolecular homolytic substitution (the S_H2 process is clearly demonstrated by density functional theory calculations and ESR experiments), which converts the peroxyls into new efficient initiating radicals. The photochemical in situ incorporation of Ti NPs has never previously been reported. The synthesis of metal nanoparticles by a S_H2 approach instead of the reduction of a metal salt appears to be a promising original method.

     

Electron impact total cross section calculations for CH3SH (methanethiol) from threshold to 5 keV

We report calculated total elastic cross sections Q_el, total ionisation cross sections, Q_ion, summed total excitation cross sections ∑Q_exc and total cross sections Q_T for CH₃SH upon electron impact for energies from ionisation threshold to 5 keV. We have employed Spherical Complex Optical Potential (SCOP) formalism to calculate total elastic cross section Q_el, and total inelastic cross section Q_inel and used Complex Scattering Potential – the ionisation contribution (CSP-ic) method to extract the ionisation cross sections, Q_ion, from the calculated Q_inel. The calculated total cross sections are examined as functions of incident electron energy and are compared with available data wherever possible and overall good agreement is observed. In this work Q_el, Q_ion, and ∑Q_exc are reported for the first time for CH₃SH in this energy range.     

Highly accurate theoretical study on spectroscopic properties of SH including spin–orbit coupling

The multi-reference configuration interaction method plus Davidson correction(MRCI+Q) are adopted to study the low-lying states of SH with consideration of scalar relativistic effect, core-valence(CV) electron correlation, and spin–orbit coupling(SOC) effect. The SOC effect on the low-lying states is considered by utilizing the full Breit–Pauli operator. The potential energy curves(PECs) of 10 Λ–S states and 18 ? states are calculated. The dipole moments of 10 Λ–S states are calculated, and the variation along the internuclear distance is explained by the electronic configurations. With the help of calculated SO matrix elements, the possible predissociation channels of A~2Σ+, c4Σ-and F~2Σ-are discussed. The Franck–Condon factors of A~2Σ~+–X~2Π, F~2Σ~-–X~2Π and E~2Σ~+–X~2Π transitions are determined, and the radiative lifetimes of A~2Σ+and F~2Σ-states are evaluated, which are in good agreement with previous experimental results.     

Scattering of anti-plane shear waves by a single crack in an unbounded trasversely isotropic electro-magneto-elastic medium

A theoretical treatment of the scattering of anti-plane shear (SH) waves is provided by a single crack in an unbounded transversely isotropic electro-magneto-elastic medium. Based on the differential equations of equilibrium, electric displacement and magnetic induction intensity differential equations, the governing equations for SH waves were obtained. By means of a linear transform, the governing equations were reduced to one Helmholtz and two Laplace equations. The Cauchy singular integral equations were gained by making use of Fourier transform and adopting electro-magneto impermeable boundary conditions. The closed form expression for the resulting stress intensity factor at the crack was achieved by solving the appropriate singular integral equations using Chebyshev polynomial. Typical examples are provided to show the loading frequency upon the local stress fields around the crack tips. The study reveals the importance of the electro-magneto-mechanical coupling terms upon the resulting dynamic stress intensity factor. Contributed by SHEN Ya-peng Foundation item: the National Natural Science Foundation of China (10132010, 50135030) Biographies: DU Jian-ke (1970∼)