Ab initio study of palladium and silicon carbide

Ab initio methods have been used to investigate the properties of Pd as impurity in bulk SiC at five charged states within the framework of density functional theory using the local spin density approximation. It was found that Pd interstitials and substitutionals have similar energy to their intrinsic counterparts. In addition, Pd substitutes for a vacancy, di-vacancy, and tri-vacancy with similar energies. Pd diffuses through SiC via an interstitial mechanism employing the tetrahedral sites and Pd can substitute for Si and C at positive charged states. Removing electrons (p-type doping) from SiC lowers the formation and migration energies of Pd defects in SiC for most configurations.     

Molecular-orbital X-rays and their anisotropies in heavy-ion collisions in solids and gases

Molecular-orbital spectra and anisotropies were measured in Cl+NaCl, Cl+KCl, Cl +Ti, and Cl+Ar collisions at bombarding energies between 0.5 and 2.6MeV/a.m.u. The results suggest that at low bombarding energies MO x-rays in the KCl and NaCl targets are partly produced by a two-collision process. Qualitative differences between the anisotropies of gas- and solid-target induced MO x-ray spectra underline this result. Also, new information on the bombarding-energy dependency of anisotropies at higher projectile velocities has been obtained, confirming previous observations in low-Z systems.     

Error Bounds for Hermite Interpolation by Quadratic Splines on an {alpha}-Triangulation

For l, an -triangulation F of a planar domain is such that,for every T F, there holds 1 R_T/2r_T , where R_T (resp. r_T)denotes the radius of the circumscribed (resp. inscribed) circleof the triangle T. When T is varying in F the centre of itsinscribed circle is varying in a compact interior to T and itsorthogonal projections on the sides are varying in compact intervalsinterior to these sides. Precise results are given about thesizes of these compacts and are used for the computation oferror constants in the problem of Hermite interpolation by Powell-Sabinquadratic finite elements, bringing to the fore their dependenceon the parameter .     

肉苁蓉精油化学成分的研究

肉苁蓉 Cistanche Salsa(C.A.Mey.)G.Beak 是列当科 Orobanchaceae 植物肉苁蓉的肉质茎;又名大芸,纵蓉。它分布在北疆地区荒漠戈壁地带,有益肾壮阳,延年益寿等功能,故有“沙漠人参”之称。肉苁蓉是一种常用的中药,新疆地区资源丰富,其精油化学成分在国内外未见报道。为了整理和发掘祖国医药学宝库,我们对其化学成分进行了研究。     

Threshold behaviour of the MO x-ray anisotropy spectra observed in heavy ions collisions

The anisotropy of the MO-radiation between the characteristic L and K lines observed in Au-Au collisions has been measured as a function of the projectile energy between 8 and 60 MeV. The observed anisotropy peaks show a threshold behaviour. This behaviour results from transitions into well defined MO-minima formed at different internuclear distances.     

Critical behavior of noninteracting spin waves

Monte Carlo techniques are used to show that a free-spin-wave theory of the quantum Heisenberg spin-1/2 ferromagnet, formulated to accurately represent the state space of the underlying system, predicts the critical temperature of the interacting theory to within 1% and critical exponents to within a factor of two.     

MO X-ray angular distributions from 1 GeV208Pb+208Pb and209Bi+209Bi collisions

The Doppler shift and the anisotropy of the MO X-rays above the separated-atomK-lines have been measured in²⁰⁸Pb+²⁰⁸Pb and²⁰⁹Bi+²⁰⁹Bi collisions at beam energies between 4.2 and 4.8 MeV/u. The Doppler shift is found to be consistent with a source moving with 90% of the center of mass velocity of the colliding system. One peak is observed in the anisotropy spectrum. This peak might be attributed to transitions from the continuum into the minimum of the 2p _1/2 σ MO or from the 3p _1/2 σ and 2p _3/2 σ MO's into the 2 _sσ MO near the united atom limit. Radiative electron capture and secondary electron bremsstrahlung could be excluded as major sources of the observed radiation. Contrary to lighter systems no anisotropy corresponding to transitions into the 1 _sσ orbital could be observed.     

Azimuthal angle dependence of molecular orbital K X-rays in heavy ion collisions

The dependence of molecular X-ray emission on the azimuthal angle in heavy ion collisions has been measured as a function of the impact parameter in the collision systems F-Al and Cl-Cl at projectile energies of 20 and 48 MeV respectively. The values of the observed azimuthal anisotropies agree with dynamical calculations of molecular orbital X-ray emission, but they are at variance with predictions of the kinematic dipole model.     

微波消解ICP-MS测定唐古特乌头中的多种微量元素

采用HNO3-H2O2混合酸体系微波消解及电感耦合等离子体-质谱法,消解唐古特乌头样品,测定其中Mn、Fe、Co、As、Ni、Se、Cu、Zn、V和Cr共10种微量元素。探讨了样品消解的条件,通过加标回收实验,回收率为94.08%—103.50%,验证了分析数据的可靠性。结果表明,该法具有快速、简便、准确度高、能同时分析多元素的优点,结果令人满意。