Identification of micro-scale calorimetric devices

Micro-calorimetric devices using Si-based sensors are very useful for the study of gas–solid reactions, in which very low mass of reactants are necessary. But in fact the consequence of using flat detectors is an increase of the uncertainty in the measured energy. In this work a calorimetric gas sensor based on Xensor chip is analysed studying the local x–y contributions of dissipation to the sensitivity related to the value in the centre. We study also the effects of the gas-flow on the sensitivity, comparing the results obtained with two Xensor type chips. Finally we carry out a deeper analysis of the x–y effects on the calorimetric detector for dissipations in the reactant shell extremely close to the detector surface to visualize the link between the power density distribution and the output signal.     

SSCH3光解离的多参考理论计算

摘要运用多参考微扰理论(Multireference MΦller-Plesset theory)计算了SSCH3垂直激发能及其S-C与S-S两种断键方式的绝热(Adiabatic)与非绝热(Diabatic)的基态和激发态势能曲线, 研究了在193nm激光作用下SSCH3的光解离过程, 理论计算值与实验值相符.     

Assignment of the first photoelectron band of the CH<Subscript>3</Subscript>CHCl radical using ab initio quantum mechanical calculations

HeI photoelectron spectra have been recorded for the reaction of atomic fluorine with ethyl chloride at different reaction times. A structured band associated with a short-lived primary reaction product has been recorded with adiabatic and vertical ionization energies of (7.84±0.02) and (8.18±0.02) eV respectively. An average vibrational separation of (680±30) cm^–1was observed in this band. Comparison between the experimental vertical and adiabatic ionization energies and ionization energies computed for CH₃CHCl (X²A) and CH₂CH₂Cl (X²A) at different levels of theory led to the assignment of the observed first photoelectron band to the ionization of CH₃CHCl (X²A). The observed vibrational structure was assigned to excitation of the C–Cl stretching mode in CH₃CHCl⁺(X¹A).Proceedings of the 11th International Congress of Quantum Chemistry satellite meeting in honor of Jean-Louis Rivail     

~3Δ、~3Π、~3Σ~＋Ni—CO分子簇的从头算研究

用从头算研究了ｄ空穴位置不同对Ｎｉ—ＣＯ成键机制的影响。结果表明，Ｎｉ—ＣＯ键中σ／π接受作用的相对强弱，取决于Ｎｉ—ＣＯ簇所处的能态。σ空间电子云较π空间电子云弥散，因而Ｎｉ—ＣＯ簇的稳定性与σ空间电子云的排斥密切相关。随着Ｎｉ４ｐσ轨道上电子占据数的增加，Ｎｉ—ＣＯ稳定性减弱。比较了分子簇Ｎｉ—ＣＯ与ＮｉＣＯ分子及ＣＯ／Ｎｉ化学吸附体系之间的性质。     

离子簇合物HeN_2~+的电子光谱的从头算研究

本文报道了离子簇合物HeN2＋的电子光谱的从头算结果。在MCSCF／6－31G（d，p）水平上，对其基态进行了几何优化，用该构型．在SDC1／6－31（d，p）水平上计算了基态的总能量。用SDCI方法计算得到HeN2＋从基态到选择激发态的垂直跃迁能、振子强度、跃迁频率、辐射寿命以及Einstain系数。该结果可以较好的验证maier的实验。     

Application of the iterative difference-dedicated configuration interaction method to the determination of excitation energies in some benchmark systems: Be, CH+, BH and CH2

The iterative difference-dedicated CI method (IDDCI) has been applied to determine excitation energies in small systems for which benchmark FCI and other high-level calculations exist. Transitions to excited singlet and triplet states in Be and vertical transitions in CH⁺, BH and CH₂ are reported. The deviations from FCI results are lower than 0.1 eV and compare advantageously with SDCI including size-consistency corrections, (SC)²SDCI, and with coupled cluster calculations including the effect of triples, especially for the states which have a predominant double excitation character. The IDDCI procedure has been speeded up by using smaller subspaces for optimizing the molecular orbitals. Received: 17 January 1997 / Accepted: 31 July 1997     

The efect of the couple stress parameter and Prandtl number on the transient natural convection flow over a vertical cylinder

An analysis is performed to study transient free convective boundary layer flow of a couple stress fluid over a vertical cylinder, in the absence of body couples. The solution of the time-dependent non-linear and coupled governing equations is carried out with the aid of an unconditionally stable Crank–Nicolson type of numerical scheme. Numerical results for the steady-state velocity, temperature as well as the time histories of the skin-friction coefcient and Nusselt number are presented graphically and discussed. It is seen that for all flow variables as the couple stress control parameter, Co, is amplified, the time required for reaching the temporal maximum increases but the steady-state decreases.     

Identification of conjugation positions of urinary glucuronidated vitamin D3 metabolites by LC/ESI–MS/MS after conversion to MS/MS‐fragmentable derivatives

A liquid chromatography/electrospray ionization–tandem mass spectrometry‐based method was developed for the identification of the conjugation positions of the monoglucuronides of 25‐hydroxyvitamin D₃ [25(OH)D₃] and 24,25‐dihydroxyvitamin D₃ [24,25(OH)₂D₃] in human urine. The method employed derivatization with 4‐(4‐dimethylaminophenyl)‐1,2,4‐triazoline‐3,5‐dione to convert the glucuronides into fragmentable derivatives, which provided useful product ions for identifying the conjugation positions during the MS/MS. The derivatization also enhanced the assay sensitivity and specificity for urine sample analysis. The positional isomeric monoglucuronides, 25(OH)D₃‐3‐ and ‐25‐glucuronides, or 24,25(OH)₂D₃‐3‐, ‐24‐ and ‐25‐glucuronides, were completely separated from each other under the optimized LC conditions. Using this method, the conjugation positions were successfully determined to be the C3 and C24 positions for the glucuronidated 25(OH)D₃ and 24,25(OH)₂D₃, respectively. The 3‐glucuronide was not present for 24,25(OH)₂D₃, unlike 25(OH)D₃, thus we found that selective glucuronidation occurs at the C24‐hydroxy group for 24,25(OH)₂D₃.     

四川省市州经济发展差异的统计分析

采用因子分析研究四川省21市州之间的相关性,利用主因子计算出各个市州得分,以市州得分作为新变量进行集团排序,再将基于相对位置排序法引入到集团排序中,进而得到最终的市州分类结果,在统计分析的基础上对市州经济发展给出一些建议.