空间斯特林制冷机应用双机备份技术研究

为了提高斯特林制冷机对于空间探测器等应用的可靠性,往往采用双机备份的结构方式,在一台制冷机出现故障后,立即切换到另一台制冷机。文中介绍了兰州物理研究所研制的一种空间斯特林制冷机双机备份应用系统,主要设计特点、试验达到的性能指标等。     

S-酮洛芬电子结构及手性光谱性质的理论研究

采用DFT及TD-DFT方法在B3LYP/6-311++G**水平对S-酮洛芬电子结构及手性光学性质进行了理论研究. 研究发现,羰基与两个苯环发生共轭;由于C(20)与C(11)上H原子之间存在空间位阻,羰基与环A及环B之间均存在一定的二面角. VCD谱中,标题化合物在1216和1712 cm-1处存在负性康登效应;在733、1803、1465和3751 cm-1处存在正性康登效应. C(14)=O(21)和C(4)=O(5)伸缩振动的空间方向相反,在VCD谱上的康登效应符号也刚好相反. 甲醇溶液中,S-酮洛芬在214、334 nm处存在负性康登效应,在226、274 nm处存在正性康登效应. 214和226 nm、274和334 nm处的电子转移方向分别相反,在ECD谱上呈现出符号相反的康登效应.     

新型β-氨基醇类高碳糖的合成及波谱研究

用C10高碳糖合成了具有潜在生物活性的C10高碳糖氨基醇类化合物及其中间体,并对所合成化合物的IR、ESI-MS/MS、1H NMR和13C NMR图谱进行归属,确证了化合物的结构.     

An improved exponential estimator of finite population mean in simple random sampling using an auxiliary attribute

In this paper, we propose an exponential ratio type estimator of the finite population mean when auxiliary information is qualitative in nature. Under simple random sampling without replacement scheme, the expressions for the bias and the mean square error of the proposed estimator have been obtained, up to first order of approximation. To show that our proposed estimator is more efficient as compared to the existing estimators, we have made a comparative study with respect to their mean square errors. Theoretically and numerically, we have found that our proposed estimator is always more efficient as compared to its competitor estimators including all the estimators of Abd-Elfattah et al. [1] [A.M. Abd-Elfattah, E.A. El-Sherpieny, S.M. Mohamed, and O.F. Abdou. Improvement in estimating the population mean in simple random sampling using information on auxiliary attribute. Applied Mathematics and Computation, 215 (2010), 4198-4202].     

Synthesis and characterization of 1‐phenyl‐3‐(propan‐2‐yl)‐1H‐pyrazol‐5‐ol single crystals

The synthesis of pyrazoles and its derivatives remains of great interest due to their wide applications in pharmaceutical and agrochemical industry. The 1‐phenyl‐3‐(propan‐2‐yl)‐1H‐pyrazol‐5‐ol was synthesized. The 1‐phenyl‐3‐(propan‐2‐yl)‐1H‐pyrazol‐5‐ol single crystals were grown by slow solvent evaporation technique using mixture of chloroform and methanol as a solvent. Yellowish and transparent crystals having maximum dimensions of 0.005 m × 0.004 m × 0.002 m were grown. The crystals were characterized by powder XRD, FT–IR, TG–DTA–DSC and dielectric study. The crystals remained stable up to 160 °C and then start decomposing. The DSC suggested both endothermic and exothermic reactions. One broad exothermic peak was observed at 558.1 °C due to complete decomposition of the sample into the gaseous phase and reaction within the products. Thermodynamic and Kinetic parameters of decomposition were calculated by Coats–Redfern formula. The dielectric study was carried out in the frequency range from 50 Hz to 5 MHz at room temperature. The dielectric constant decreased as the frequency of the applied field increased. The variations of dielectric loss, a.c. conductivity and a.c. resistivity also studied with the frequency of the applied field. Jonscher's power law was verified for a.c. conductivity.     

Key words结构视角下的欧元区主权债务可持续性研究

基于债务结构的研究视角,以德国和PIIGS五国为例,构建主权债务可持续性模型,量化研究债务自身结构、宏观经济结构以及财政支出结构对债务可持续性的影响,并运用向量自回归模型进行检验.研究结果表明：适度地提高长期债券所占比重（以65％-75％为宜）,同时降低短期债务的比重（不超过15％）,改善宏观经济结构并促进国内就业,扩大固定资产投资的财政支出,均有助于抑制债务规模的持续扩张,维持主权债务的可持续性.     

Initial-Condition Sensitivity and Nonlinear Relaxation in Photo-Induced Ionic-to-Neutral Phase Transition in Tetrathiafulvalen- p -Chloranil Crystals

Recent experimental results of the photoinduced ionic-to-neutral (NI) phase transition in tetrathiafulvalen- p -chloranil (TTF-CA) crystals are reviewed with emphasis on the state-sensitive features and nonlinear properties. Frenkel-type and charge transfer (CT)-type excited states can induce the NI transition but with different characteristics; the transition can be induced only above threshold-excitation intensities in the case of CT excitation, whereas it is induced without any threshold for Frenkel-type excitation. The threshold that implies nonlinear processes of CT excited states is strongly state-dependent and temperature-dependent. Femtosecond time-resolved studies have resolved three distinctive sequential steps in the dynamics; formation of the precursor of N-phase domains, the local proliferation of photoinduced changes, and the process of forming N-phase orders. Origin of the nonlinear processes and the mechanism of the NI transition have been discussed based on these results.     

Synthesis, Crystal Structure and Quantum Chemistry Study of Tri（o-bromobenzyl）tin Ferrocenecarboxylate

A novel complex tri(o-bromobenzyl)tin ferrocenecarboxylate has been synthesized and its crystal structure was determined by X-ray diffraction. It belongs to orthorhombic, space group Pbca with a = 1.1340(3), b = 1.7823 (4), c = 3.0119(8) nm, V = 6.088(3) nm3, Mr = 857.81, Z = 8, Dc = 1.872 g/cm3, μ(MoKα) = 52.63 cm-1, F(000) = 3328, R = 0.0683 and wR = 0.1057. The tin atom adopts a distorted tetrahedral coordination geometry. Further studies on the title com- plex have been performed with quantum chemistry calculation at the Lanl2dz basis set level using G98W package. The stability of the complex, some frontier molecular orbital energies and com- position characteristics of some frontier molecular orbitals have been investigated.     

Theoretical Study of the Iodine-catalyzed Nucleophilic Addition by Halogen Bond

The iodine-catalyzed nucleophilic addition of pyrrole to acetone has been studied by density functional theory at the level of Lanl2DZ. It has been shown that the first iodine molecule appears to have a remarkable catalytic effect on this reaction by halogen bond between carbonyl oxygen and iodine molecule,but the second one does not improve the reaction largely. In general,the nucleophilic addition at the C(2) site of pyrrole is more favorable than that at the C(3) site; however,this trend is not prominent or even changed in acetronitrile solvent for the indole system,which is consistent with the experimental result by Bandgar.     

Determination of manganese(II) in powdered barnacle shells by electron paramagnetic resonance

A rapid precise method of determining Mn(II) (as opposed to total manganese) in powdered barnacle shells by e.p.r. is described. The method is based on the linear relationships between the intensity of the first-derivative e.p.r. signal and the weight and Mn(II) concentration in the sample. Atomic absorption was used as a reference method. For eleven samples, the difference between the a.a.s. and e.p.r. methods was, on average, within 3 %; the detection limit was 20 p.p.b. A good correlation between the Mn(II) content of the shell and the position of the animal in an inter-tidal zone was found.