钙钛矿CaTiO3的超高压结构研究

利用同步辐射x射线衍射和 DAC 高压技术在室温下测量了钙钛矿CaTiO₃在压力0—44.53 GPa下的结构变化.结果表明，随着压力的增加CaTiO₃的三个晶轴都受到不同程度的压缩，a,b的压缩率相近且相对比较大，c的压缩率最小，但没有证据表明有相变的发生.在压力范围内CaTiO₃的P-V关系用Murnaghan状态方程表示，设定K′0=4，得到V0=0.2245(6)nm3和K0=222(9) GPa.应用赝立方角γpc与压力的关系，初 关键词： 3')" href="#">CaTiO₃ 结构 超高压 状态方程     

Comparative XPS study between experimentally and naturally weathered pyrites

A comparative study has been carried out between experimentally and naturally weathered pyrites. Both were found to share similar species of weathering products and a similar weathering mechanism. The weathering products could be divided into sulphur-bearing or iron-bearing groups. The sulphur-bearing group was comprised of sulphate, sulphite, thiosulphate, elemental sulphur, polysulphide, and mono-sulphide. The iron-bearing group was comprised of goethite, hematite or magnetite, and iron sulphate. The weathering structural profile was also similar for both types of weathering, being composed of a surficial layer and a transitional layer. The surficial layer was made up of both the sulphur-bearing and the iron-bearing products, while the transitional layer was comprised of goethite, and hematite or magnetite. The inward migration of the weathering interface was stimulated by the diffusion of oxygen and moisture. The oxygen was considered to preferably squeeze the iron to form goethite, and the ferric ions of goethite to have acted as a bridge for electron transfer between the oxygen and bulk S₂²⁻ and Fe²⁺ of pyrite.     

Surface active properties of N-(2-Aminoethyl)-3-aminopropyltetrasiloxane lactobionamide and aggregation behavior in aqueous solution

The aggregation behavior of tetrasiloxane-lactobionamide (Si4N2-LA) in aqueous solution has been characterized by dynamic light scattering (DLS), negative-stained transmission electron microscopy (TEM) and X-ray Diffraction methods. Compared with the micellar sizes 7.0 nm of n-dodecyllactobionamide (C12Glu2), the Si4N2-LA molecule can self-assemble into spherical vesicle with diameters in the range from 60 to 300 nm.     

Studies on the Synthesis and Antiproliferative Activities of 13‐cis‐Retinoyl Sugar Derivatives

New retinoyl sugar derivatives of 13‐cis‐retinoic acid were synthesized in three ways in this paper in order to enhance pharmacal effects, especially antiproliferative activities of 13‐cis‐retinoic acid. Their structures were confirmed by IR, ¹H‐NMR, ¹³C‐NMR, and MS spectra and their antiproliferative activities were determined in vitro using human cancer lines. Results showed that some compounds possessed potential antitumor activities.     

条件风险下的两基金分离定理

鉴于条件风险价值CVaR具有风险度量的合理性以及两基金分离定理对证券投资的重要意义,以CVaR作为风险度量研究两基金分离定理.在组合收益率服从正态分布的假设下,分别就投资组合含有或没有无风险资产的情形提出并证明了两基金分离定理;放开方差-协方差矩阵为非奇异这一通常假设,证明了CVaR风险度量下的两基金分离定理依然成立.     

一个修正Novikov方程弱解的全局存在性

主要研究了一个修正的Novikov方程,并给出了当初值u0(x)满足一定条件时,方程弱解的全局存在性,推广了Novikov方程的相关结果.     

Palladium‐Catalyzed C(sp3)?H Activation: A Facile Method for the Synthesis of 3,4‐Dihydroquinolinone Derivatives

3,4‐Dihydroquinolinones were synthesized by the palladium‐catalyzed, oxidative‐addition‐initiated activation and arylation of inert C(sp³) H bonds. Pd(OAc)₂ and P(o‐tol)₃ were used as the catalyst and ligand, respectively, to improve the efficiency of the reaction. A further advantage of this reaction is that it could be performed in air. A relatively rare seven‐membered palladacycle was proposed as a key intermediate of the catalytic cycle.     

Self-calibration method for cerium-doped lanthanum bromide scintillator detector in the 0.1–2.0 MeV energy range

In recent years, the cerium-doped lanthanum bromide, LaBr₃ (Ce = 5 %) detector is increasingly playing an important role in radiation measurements because of its higher energy resolution (~3 % at 662 keV), faster luminescence decay time (~35 ns) and higher detection efficiency compared to 7.65 cm × 7.65 cm NaI(Tl) detector. Intrinsic spectra between 1,800 and 3,000 keV derived from internal radioactivity within LaBr₃(Ce) scintillators have been investigated in some literatures, and these results are confirmed by the experiments in this work. In this paper, a new method for LaBr₃(Ce) detector energy calibration from 100 to 2,000 keV is proposed using the intrinsic spectra (self-calibration) instead of the standard gamma sources. Proof-of-concept experiment results show that self-calibration can guarantee energy accuracy of better than 0.815 % and can be applied outside the laboratory. The stability and applicability of this method are also investigated systematically.