气相色谱法分析氦中氧气、氮气、一氧化碳、二氧化碳及氙气混合气体标准物质

建立利用气相色谱热导检测器分析气体激光器用氦中氧气、氮气、一氧化碳、二氧化碳及氙气混合气体标准物质的方法。试验比较了不同极性、不同类型的色谱柱,对柱箱温度、载气流量进行了优化,最终确定以HP–PLOT/分子筛色谱柱分离氧气、氮气、一氧化碳、氙气,柱箱温度保持40℃,以HP–PLOT Q柱分离二氧化碳,柱箱温度保持60℃,载气流量均为2 m L/min。在混合气体标准物质量值范围内,该分析方法测定结果的相对标准偏差不大于1%(n=6),对重量法配制得标准气体进行分析比对,测量误差不大于1%。     

Cu2O亚微米空心球的低共熔溶剂辅助合成与表征

以低共熔溶剂(DESs)/H2O混合溶剂为介质成功制备了形貌均一、尺寸小且稳定性高的亚微米Cu2O空心球。采用扫描电镜、透射电镜和X射线衍射等方法表征了所制备样品的形貌、尺寸和结构。同时,研究了温度、p H、聚乙烯吡咯烷酮(PVP)用量等因素对样品尺寸、形貌及纯度的影响。结果表明,制备高纯Cu2O空心球的优化工艺条件为40℃、p H=11和PVP用量0.9g。混合溶剂中DESs的存在对提高所制备Cu2O样品的纯度、形态均一性和稳定性以及缩小颗粒的尺寸起到了重要作用。     

Westerdijkin A,a new hydroxyphenylacetic acid derivative from deep sea fungus Aspergillus westerdijkiae SCSIO 05233

A new methyl 2-(4-((2-hydroxy-3-methylbut-3-en-1-yl)oxy)phenyl) acetate 1, together with five known compounds 2–6, was isolated from the culture of the deep sea-derived fungus Aspergillus westerdijkiae SCSIO 05233. The new structure was determined by NMR (¹H and ¹³C NMR, HSQC, HMBC and MS) and optical rotation analysis. Compound 5 displayed weak inhibitory activities towards K562 and promyelocytic HL-60 with IC₅₀ values of 25.8 and 44.9 μM, and compound 6 showed strong antifouling activity with EC₅₀ value 8.81 μg/mL.     

A novel method to characterize thermal properties of the polymer and gas/supercritical fluid mixture using dielectric measurements

Gases or supercritical fluids (SCF) are widely used in polymer science and engineering, as their dissolution into polymeric materials will alter their inherent thermal properties; including melting and crystallization temperatures (T_m and T_c). One possible method to determine these temperatures, at elevated pressures, is to use a high-pressure differential scanning calorimeter (HP-DSC). However, the elevated pressures used in HP-DSC may result in signal instabilities, limiting the testing window for these pressures. This study presents a novel testing system using dielectric measurements to determine the effects of dissolved gas/SCF on the T_m and T_c of polymers. We have developed an instrument to determine the dielectric properties of both polymer/gas and polymer/SCF mixtures, at elevated pressures and temperatures. Using the change in the measured dielectric constant or loss, T_m and T_c were determined. The effects of hydrostatic pressure and plasticization due to dissolved carbon dioxide (CO₂) and Helium (He) on the T_m and T_c of high density polyethylene (HDPE) are presented and discussed. Both T_m and T_c increase with pressure and decrease due to plasticization, i.e., pressure and plasticization are competing variables. The dissolution of He, having a low solubility into HDPE, reveals that pressure is the dominant effect. In contrast, the dissolution of CO₂, having a high solubility into HDPE, shows that plasticization is predominant.     

The temperature dependence of single-event transients in 90-nm CMOS dual-well and triple-well NMOSFETs

This paper investigates the temperature dependence of single-event transients(SETs) in 90-nm complementary metat-oxide semiconductor(CMOS) dual-well and triple-well negative metal-oxide semiconductor field-effect transistors(NMOSFETs).Technology computer-aided design(TCAD) three-dimensional(3D) simulations show that the drain current pulse duration increases from 85 ps to 245 ps for triple-well but only increases from 65 ps to 98 ps for dual-well when the temperature increases from-55℃ to 125℃,which is closely correlated with the NMOSFET sources.This reveals that the pulse width increases with temperature in dual-well due to the weakening of the anti-amplification bipolar effect while increases with temperature in triple-well due to the enhancement of the bipolar amplification.     

Lowering plasma frequency by enhancing the effective mass of electrons： A route to deep sub-wavelength metamaterials

Deep sub-wavelength metamaterials are the key to the further development of practical metamaterials with small volumes and broadband properties. We propose to reduce the electrical sizes of metamaterials down to more sub-wavelength scales by lowering the plasma frequencies of metallic wires. The theoretical model is firstly established by analyzing the plasma frequency of continuous thin wires. By introducing more inductance elements, the effective electron mass can be enhanced drastically, leading to significantly lowered plasma frequencies. Based on this theory, we demonstrate that both the electric and the magnetic plasma frequencies of metamaterials can be lowered significantly and thus the electrical sizes of metamaterials can be reduced to more sub-wavelength scales. This provides an efficient route to deep sub-wavelength metamaterials and will give rigorous impetus for the further development of practical metamaterials.     

A new interactive thermoluminescence mixed-order glow curve deconvolution function

An interactive mixed-order thermoluminescence (TL) glow curve deconvolution function is presented for the first time in which the retrapping of thermally stimulated charge carriers in deep traps during the heating stage is taken into account. Considering this transition in the set of differential equations by describing the TL process and by solving them, an analytical function for TL intensity was obtained. This equation reduces to the known deconvolution function for the mixed-order model in the limiting case of saturation of deep trapping (DT) states. In intermediate cases, where the DT states are partially occupied, the proposed function acts as a real interactive model which allows the thermally stimulated electrons to be retrapped to deep electron traps. Applicability of the proposed model in a real TL system is also presented and discussed.     

NM-QELE for ARMA-GARCH models with non-Gaussian innovations

Although the quasi maximum likelihood estimator based on Gaussian density (Gaussian-QMLE) is widely used to estimate parameters in ARMA models with GARCH innovations (ARMA-GARCH models), it does not perform successfully when error distribution of ARMA-GARCH models is either skewed or leptokurtic. In order to circumvent such defects, Lee and Lee (submitted for publication) proposed the quasi maximum estimated-likelihood estimator using Gaussian mixture-based likelihood (NM-QELE) for GARCH models. In this paper, we adopt the NM-QELE method for estimating parameters in ARMA-GARCH models and demonstrate the validity of NM-QELE by verifying its consistency.     

混合气体线性化Boltzmann算子的特征值与特征函数

考虑了混合气体线性化Boltzmann算子的特征值与特征函数问题.通过对算子中核函数的分析得出了更一般的混合气体线性化Boltzmann算子的特征值与特征函数.而且结论还适用于单一气体情况.     

Relativistic effects in HgHe and HgXe CCSD(T) ground state potential curves. Low‐density viscosity simulations of Hg:Xe mixture

The comparison of coupled cluster with single and double excitations and with perturbative correction of triple excitations [CCSD(T)] ground state potential curves of mercury with rare gases (RG): HgHe and HgXe, at several levels of theory is presented. The scalar relativistic (REL) effects and spin‐orbit coupling effects in the ground state potential curves of these weakly bounded dimers are considered. The CCSD(T) ground state potential curves at the level of the Dirac‐Coulomb Hamiltonian (DCH) are compared with CCSD(T) curves at the level of 4‐component spin‐free modified DCH, the scalar 2nd order Douglas‐Kroll‐Hess (DKH2) and the nonrelativistic (NR‐LL) (Lévy‐Leblond) Hamiltonian. In addition, London‐Drude formula and SCF interaction energy curves are employed in the analysis of different contributions of REL effects in dissociation energies of HgRG and Hg₂ dimers. Moreover, the large anharmonicity of the HgHe ground state potential curve is highlighted. The computationally less demanding scalar DKH2 Hamiltonian is employed to calculate the HgXe, Hg₂, and Xe₂ all electron CCSD(T) ground state potential curves in highly augmented quadruple zeta basis sets. These potential curves are used to simulate the shear viscosity of mercury, xenon, and mercury‐xenon (Hg:Xe) mixture. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011