用选择离子流动管质谱测定汽油和柴油蒸汽成分

采用选择离子流动管质谱(SIFT／MS)装置，以H30^ 、N0^ 为初始离子对汽油和柴油蒸汽进行了研究，质谱分析表明，汽油和柴油主要由C—H化合物组成，包括烷烃、环烷烃、烯烃、炔烃、二烯烃以及芳香烃。在这几种成分中，烷烃都占有最大的比例；汽油蒸汽和柴油蒸汽最大的区别是柴油蒸汽中长链大分子的挥发性C—H化合物所占的比例远远高于汽油蒸汽。文中还给出了以H30^ 、N0^ 为初始离子所得到的汽油蒸汽的质谱图，以及汽油、柴油蒸汽中各种成分的定量分析结果。     

The effect of gas injection on a thermal argon plasma flow in a water-cooled tube

The effect of gas injection on an atmospheric thermal argon plasma flow in a water-cooled tube was investigated experimentally and numerically. The injection gas is argon, helium, or nitrogen. The static pressure with helium injection increases greatly because of its high thermal conductivity, while little increase occurs for nitrogen injection because of the dissociation. The increasing rate of the static pressure depends on the ratio of the momentum term to the viscosity term. The heat flux to the tube wall with gas injection changes less than that without injection. The numerical results showed variations similar to the experimental ones.     

C12簇及其碳管烷C12H12的理论研究

C60和C70等碳笼烯的发现及其在新物质、新材料等研究领域中的重要性，激励人们去探索合成更多新型多面体碳簇化合物与碳元素类似物[1，2]．最近，两类新型多面体碳管笼烯的设想提出来了[3，4]应用HMO和MNDO方法对其稳定性变化规律、结构和成键特征进行了讨论.关于多苯的vanderWaals簇实验上已有广泛的调查[5，6]，理论上对其二聚物（C6H6）。的不同几何构型与稳定性进行了深入的研究[7]．本文采用abinitio计算有效势（effectivecorePotential）方法，对C12碳管元素簇和C12H12，碳管烷的平衡结构、稳定性和价键特征进行了理论预测．1…     

Influence of the variable wall thickness of the sample tubes and a quartz Dewar on the EPR signal intensity in a single TE102 and double TE104 rectangular cavity

The response of a single TE₁₀₂ and double TE₁₀₄ rectangular cavity to the insertion of samples contained in tubes with variable wall thickness and a quartz Dewar into the cavity has been analyzed. A direct, indirect, and concurrent (positive or negative) “lens effect” inside the double TE₁₀₄ rectangular cavity is discussed. The experimental dependence of the EPR signal intensity on the wall thickness of the sample tube, δ, for the line-like samples with identical length of the sample material column, L=30 mm, recorded in the microwave cavity showed a directly proportional increase of the relative “lens effect” with the increase of the wall thickness of the tube in the interval, δ∈<0.1 mm, >0.5 mm. The insertion of the variable-temperature double-wall quartz Dewar (home-built, resonant frequency shift, ca. −300 MHz) into the single TE₁₀₂ rectangular cavity showed the same relative “lens effect”, with ca. 1.5-time increase of the EPR signal intensity, for a point-like sample and the line-like samples with material columns of diameter of 1 and 1.3 mm, and wall thickness of the sample tubes, δ∈<0.1 mm, >0.5 mm. The increased effect of the Dewar arises because the active volume of the quartz Dewar tube walls is always much more larger than the active volume of the sample tube wall. In the case of the double TE₁₀₄ rectangular cavity, the insertion of the quartz Dewar: (i) into the same cavity, in which the sample is present, caused a direct “lens effect”, with ca. 1.8-fold increase of the EPR signal intensity; however, (ii) into the complementary cavity, in which the sample is absent, caused an indirect “lens effect”, with ca. 0.6-fold decrease of the EPR signal intensity. With the Dewar and sample in one cavity and a large empty sample tube in the complementary cavity, a concurrent (positive or negative) “lens effect” can be observed. Thus, the possible increase/decrease of the EPR signal intensity depends on the volume ratio of the quartz Dewar tube walls and large sample tube wall inserted into the double TE₁₀₄ rectangular cavity. Each of the above phenomena may be a significant source error in quantitative EPR spectrometry unless the samples to be compared in the quantitative EPR analysis are contained in sample tubes having the same wall thickness and each EPR spectra should be recorded inside an identical quartz Dewar.     

Deflagration-to-detonation transition process for spherical aluminum dust/epoxypropane mist/air mixtures in a large-scale experimental tube

The deflagration-to-detonation transitions (DDTs) for clouds of spherical aluminum dust (SAD) mixed with air or epoxypropane mist (EPM) and air were investigated in a 29.6-m-long experimental tube of 199 mm in diameter. The clouds formed through the injection of SAD and SAD/liquid epoxypropane samples into the experimental tube. Explosions of the SAD/air mixture were initiated using a 7-m-long EPM/air cloud explosion ignited by a 40-J electric spark. Explosions in SAD/EPM/air clouds were initiated using a 1...     

Ignition delay times of methane and hydrogen highly diluted in carbon dioxide at high pressures up to 300 atm

The need for more efficient power cycles has attracted interest in super-critical CO₂ (sCO₂) cycles. However, the effects of high CO₂ dilution on auto-ignition at extremely high pressures has not been studied in depth. As part of the effort to understand oxy-fuel combustion with massive CO₂ dilution, we have measured shock tube ignition delay times (IDT) for methane/O₂/CO₂ mixtures and hydrogen/O₂/CO₂ mixtures using sidewall pressure and OH* emission near 306?nm. Ignition delay time was measured in two different facilities behind reflected shock waves over a range of temperatures, 1045–1578?K, in different pressures and mixture regimes, i.e., CH₄/O₂/CO₂ mixtures at 27–286 atm and H₂/O₂/CO₂ mixtures at 37–311 atm. The measured data were compared with the predictions of two recent kinetics models. Fair agreement was found between model and experiment over most of the operating conditions studied. For those conditions where kinetic models fail, the current ignition delay time measurements provide useful target data for development and validation of the mechanisms.     

2-丙基-1H-4，5-咪唑二酸构筑的镉(Ⅱ)配位聚合物的合成、晶体结构、形貌及荧光性质

通过水热方法 ,采用H3pimda(2-propyl-1H-imidazole-4,5-dicarboxylic acid)与CdSO4.8/3H2O和Nd2O3反应,合成了1个具有一维孔道的配位聚合物[Cd(H2pimda)2]n(1),并对其结构和荧光性质进行了研究。结构分析结果表明该聚合物的晶体属于单斜晶系,P21/n空间群。4个H2pimda-配体桥联4个镉(Ⅱ)离子形成了1个方环,这些环通过镉(Ⅱ)离子与H2pimda-配体的配位作用形成了1个具有一维孔道的三维框架结构。值得关注的是配合物1的晶体呈现一种微米管的外型。研究表明,该聚合物中在室温下能发出很强的兰色荧光。     

Electrothermal atomic absorption spectrometric determination of cadmium in environmental samples with niobium wire preconcentration method

A preconcentration method by adsorption of cadmium on a niobium wire was developed for the environmental waters, followed by electrothermal atomic absorption spectrometry with a tungsten tube atomizer. After the preconcentration, the niobium wire was directly inserted into the tungsten tube atomizer. In the preconcentration (adsorption) process of cadmium, the optimal immersing time was 60?s. The effects of large amounts of concomitants on the preconcentration of cadmium were evaluated. When 10³–10⁴ fold excess of matrix elements existed in aqueous solution at pH 4 and 9, the cadmium response was profoundly affected by the matrix elements. However, the cadmium absorption signal was not significantly influenced at pH 7. Therefore, pH 7 was selected for the application into the real environmental samples. Under the optimal conditions, the detection limit (3S/N) for cadmium by the niobium wire preconcentration method was 7.0?pg?mL^?1 and the relative standard deviation was 6.8%. The method with preconcentration on a niobium wire was applied to the determination of cadmium in water and proved to be sensitive, simple and convenient. Because this preconcentration method can be utilized in the in situ treatment of trace cadmium in environmental water samples, it was unnecessary to carry the water samples to the analytical work place. The technique was shown to be useful for the determination of cadmium in environmental water samples at 0.1–1?µg?L^?1 levels.     

High-temperature measurements of the rates of the reactions CH2O + Ar → Products and CH2O + O2 → Products

The two-channel thermal decomposition of formaldehyde [CH₂O], (1a) CH₂O + Ar → HCO + H + Ar, and (1b) CH₂O + Ar → H₂ + CO + Ar, was studied in shock tube experiments in the 2258-2687 K temperature range, at an average total pressure of 1.6 atm. OH radicals, generated on shock heating trioxane-O₂-Ar mixtures, were monitored behind the reflected shock front using narrow-linewidth laser absorption. 1,3,5 trioxane [C₃H₆O₃] was used as the CH₂O precursor in the current experiments. H-atoms formed upon CH₂O and HCO decomposition rapidly react with O₂ to produce OH via H + O₂ → O + OH. The recorded OH time-histories show dominant sensitivity to the formaldehyde decomposition pathways. The second-order reaction rate coefficients were inferred by matching measured and modeled OH profiles behind the reflected shock. Two-parameter fits for k_1a and k_1b, applicable in this temperature range, are: