Evolved Gas Analysis of Secondary Organic Aerosols

Secondary organic aerosols have been characterized by evolved gas analysis (EGA). Hydrocarbons selected as aerosol precursors were representative of anthropogenic emissions (cyclohexene, cyclopentene, 1-decene and 1-dodecene, n-dodecane, o-xylene, and 1,3,5-tri-methylbenzene) and of biogenic emissions (the terpenes α-pinene, β-pinene and d-limonene and the sesquiterpene trans-caryophyllene). Also analyzed by EGA were samples of secondary, primary (highway tunnel), and ambient (urban) aerosols before and after exposure to ozone and other photochemical oxidants. The major features of the EGA thermograms (amount of CO₂ evolved as a function of temperature) are described. The usefulness and limitations of EGA data for source apportionment of atmospheric particulate carbon are briefly discussed.     

Oxidative Stability of Papaya Seed Oil From Hainan/Eksotika Obtained by Subcritical and Supercritical Carbon Dioxide Extraction

Papaya seed is a good source of edible oil with considerable antioxidant activity. Here, papaya seed oil (PSO) of Hainan/Eksotika variety was obtained by subcritical butane extraction (SBE) and supercritical carbon dioxide extraction (SCDE), and its yields, physicochemical properties, oxidative and thermal stability, and chemical and microscopic structures were compared. The results showed that SBE‐PSO had a higher yield (25.88 ± 0.29% vs. 19.47 ± 0.92%), but a lower melting point compared to SCDE‐PSO. Molecular structures indicated that there was no oxidative degradation during SBE and SCDE. Both SBE and SCDE caused significant structural changes of seed tissues. In addition, aldehyde composition analysis using high performance liquid chromatography (HPLC) showed that SBE‐PSO had fewer octanal, nonanal, 2‐decenal, and 2‐undecenal contents than SCDE‐PSO. All these results proved that SBE‐PSO exhibited superiority on the oxidative stability compared to SCDE‐PSO. It indicated that SBE was a superior method to obtain antioxidant edible oil with good stability.     

JOB-9003炸药释出气体研究

采用固相微萃取(SPM E)、GC、GC/M S技术,对JOB-9003炸药及Φ10 mm×8 mm小药柱加速老化贮存初期释出气体进行了研究。检测到的气体物质主要包括JOB-9003的各组分生产过程中使用的溶剂和原料、JOB-9003造粒过程中使用的溶剂、JOB-9003的组分、JOB-9003释出物质互相反应的产物。研究表明,JOB-9003加速老化贮存初期释出气体以生产过程中被封闭在材料中或溶入材料中的气体为主。随着贮存温度的升高和贮存时间的延长,JOB-9003造型粉及小药柱释出的各种气体组分的浓度大都呈升高的趋势。     

四氟化碳中痕量气体杂质的气相色谱分析

采用配有放电离子化检测器的气相色谱仪分析高纯四氟化碳中痕量气体杂质。研究了分析四氟化碳中氧气、氮气、一氧化碳、二氧化碳和六氟化硫等气体杂质的操作参数,确定了高纯四氟化碳中痕量气体杂质的分析方法。     

Physical Properties of Butter Oil Fractions Obtained by Supercritical Carbon Dioxide Extraction

Butter oil has been fractionated with supercritical carbon dioxide at 40°C. 125 bar and 350 bar, respectively. The chemical composition and physical properties of the butter oil fractions have been studied with gas chromatography and differential scanning calorimetry (DSC). The polymorphism of the fractions has been studied by X-ray diffraction during crystallization. Fractionation carried out at lower extraction pressure results in higher selectivity. The first fractions collected during the extraction process contain triglycerides which are enriched in short chain fatty acids. The colourless fractions melt and crystallize at a lower temperature compared to the original butter. The residual fraction is enriched in triglycerides with long chain fatty acids, is yellow, melts and crystallizes at a higher temperature. All the investigated fractions shows the β′ form when crystallized from the melt.     

气体氮化法制备Fe4N超细粉末的工艺研究

采用铁粉氮化法制备铁氮化合物,通过XRD测试结合SEM测试分析,对产物的成份以及表面形貌进行了表征;分析了工艺参数对产物的影响,实验表明:在550 ℃、氨氢比为1∶ 1时,氮化3～5 h均可制得单相的Fe4N.此制备方法工艺简单,操作方便.     

Reaction Mechanisms of Silicon Carbide Fiber Synthesis by Heat Treatment of Polycarbosilane Fibers Cured by Radiation: I, Evolved Gas Analysis.

SiC fibers were synthesized from polycarbosilane (PCS) fibers by heat treatment after electron beam irradiation curing. The pyrolysis reaction mechanisms from the organic PCS to ceramic SiC were investigated by the analysis of gases evolved during heat treatment. There were two steps in the major reaction: the first step was at 800–1200 K where H₂ and CH₄ evolved by scission of Si-CH₃ and Si-H and by rearrangement reactions, and the second step was at 1000–1700 K where H₂ evolved by reactions related to C atoms in the PCS main chain. H₂ evolution in the first step was reduced with increasing oxygen content in the cured PCS fibers.     

Oxidative Stability of Conjugated Linoleic Acid Rich Soy Oil Obtained by Heterogeneous Catalysis

A CLA rich‐soy oil (CLARSO) has been produced by heterogenous catalysis. This oil may provide significant health benefits. The objectives of this study were: to determine the oxidative stability of the CLARSO and CLARSO after adsorption treatment [ 1 ], relative to conventional soy oil, in terms of primary and secondary oxidation products and to determine CLA and other unsaturated fatty acids oxidation kinetics in the CLARSO [ 2 ]. Primary and secondary oxidation products were measured in CLARSO and soy oil samples kept at 50 °C in the dark. The CLARSO was less stable than soy oil but bleaching improved its oxidative stability. The induction times were dependent on the analytical method used. Fatty acid oxidation kinetics was determined by measuring each fatty acid and hydroperoxides in CLARSO at 52, 61 and 69 °C in the dark. Unsaturated fatty acids oxidation rate constants, activation energies and frequency factors were obtained by the Arrhenius equation. Kinetics studies showed that CLA isomers had higher rate constants, higher activation energies and higher frequency factors than linoleic acid which showed that the CLA isomers had more molecular collisions with oxygen than linoleic acid.     

猪骨基多孔碳固定化酶的研究

本文以猪骨基多孔碳为载体,采用明胶包埋与戊二醛交联结合的方法,制备固定化过氧化氢酶,并对固定化酶制备条件的优化,酶作用最适条件及其稳定性进行研究。结果表明:以猪骨基多孔碳为载体吸附2h、1%明胶包埋、1%戊二醛交联过氧化氢酶制备的固定化酶,在最适的缓冲液浓度、溶液pH和体系温度下,虽然催化效率有所下降,但其贮存稳定性和操作稳定性都有所增加,重复使用8次后,活力仍保持在初始活力的90%以上。这对于过氧化氢酶进一步在食品工业和纺织工业的推广可能有潜在的应用价值。     

毛细管气相色谱法测定工业废气中二硫化碳

建立了用气相色谱法测定工业废气中二硫化碳的方法。二硫化碳经活性炭吸附后由乙醇解吸,HP-INNOWAX毛细管色谱柱分离,经氢火焰离子化检测器检测。二硫化碳在5.04~50.4 mg/L范围内标准曲线线性良好,相关系数为0.9995,当采样体积为30 L,二硫化碳最低检出质量浓度为0.009 mg/m3,其加标回收率为94.9%~104.8%。本方法前处理简便,分离度好,干扰少,分析灵敏度高,能满足分析要求。     

The Theory of the Replacement of Methane by Carbon Dioxide in Gas Hydrates

Theoretical Foundations of Chemical Engineering - A plane one-dimensional theoretical model has been considered and numerical solutions have been derived for the replacement of methane by carbon...     

转化率气相色谱分析方法的建立

以气相色谱法定量分析苯乙烯转化为聚苯乙烯的百分比（苯乙烯的转化率）,对聚苯乙烯胶体样品通过二氯甲烷溶解后,再用甲醇沉淀多聚物,然后运用色谱分析未沉淀的清液来分析样品中的组分,克服了一般用的重量法误差大的缺点,大大提高了准确度,使乙苯标准偏差为0.1825%,苯乙烯标准偏差为0.2499%。     

磷威乳油的气相色谱分析

磷威乳油是由水胺硫磷、丁硫克百威两种农药混合复配而成。本文采用气相色谱法，选择５％ＯＶ－３色谱柱，以十九烷为内标，在同温同柱的条件下能完成上述两种不同类型农药有效成分的定量分析。水胺硫磷的标准偏差为０．２，变异系数１．０７％，回收率９９．８１％；丁硫克百威的标准偏差０．０８，变异系数３．５０％，回收率９９．２４％。     

Corrosion Resistance and Electrical Conductivity of Hybrid Coatings Obtained from Polysiloxane and Carbon Nanotubes by Electrophoretic Co-Deposition

Nanocomposites developed based on siloxanes modified with carbon nanoforms are materials with great application potential in the electronics industry, medicine and environmental protection. This follows from the fact that such nanocomposites can be endowed with biocompatibility characteristics, electric conductivity and a high mechanical durability. Moreover, their surface, depending on the type and the amount of carbon nanoparticles, may exhibit antifouling properties, as well as those that limit bacterial adhesion. The paper reports on the properties of polysiloxane (PS) and carbon nanotubes (CNT) nanocomposite coatings on metal surfaces produced by the electrophoretic deposition (EPD). A comparison with coatings made of pure PS or pure CNT on the same substrates using the same deposition method (EPD) is provided. The coatings were examined for morphology and elemental composition (SEM, EDS), structural characteristics (confocal Raman spectroscopy), electrical conductivity and were tested for corrosion (electrochemical impedance spectroscopy-EIS, potentiodynamic polarization-PDP). The results obtained in this study clearly evidenced that such hybrid coatings conduct electricity and protect the metal from corrosion. However, their corrosion resistance differs slightly from that of a pure polymeric coating.     

气相色谱法测定混合气体中一氧化碳、二氧化碳、甲烷含量

采用气相色谱法测定混合气体中一氧化碳、二氧化碳、甲烷含量,通过两个色谱柱来分离混合气体,得到相对保留时间,以外标法建立了三种气体的标准曲线,并通过精密度实验和准确度实验验证了检测方法的灵敏度、重现性,最终测定混合气体中一氧化碳、二氧化碳、甲烷摩尔分数分别为1.35×10~(-4),0.35×10~(-4),0.96×10~(-4)。     

三通道色谱法快速分析裂解气组成

建立裂解气的多通道色谱快速分析法。此方法还可以分别用来测定不凝气含量,C1－C6烃类含量及快速测定氮封下密闭容器中的可燃气含量。     

台南气田水平井裸眼井壁稳定性分析

水平井井壁是否稳定关系到水平井在开采过程中的生产动态。井壁稳定性归根结底是井下岩石所受应力大小与岩石强度大小校核的结果。通过调研总结了四种水平井裸眼井壁稳定性分析模型,包括抗压强度法、Mohr-Coulumn剪切应力分析法和Von-Mesis剪切应力分析法。利用上述三种评价方法对台南气田某水平井进行水平井裸眼井壁稳定性分析,得到的结论均是该水平井井壁不稳定或极不稳定,结果说明此井需要考虑能够防止井壁坍塌或变形的水平井完井方式,从而为其进行水平井完井方式优选提供了参考依据。     

Gas Analysis of Carbon Oxidation in a Coin‐Type Direct Carbon Fuel Cell

Carbon oxidation behaviors were illuminated in terms of gas composition in a coin‐type direct carbon fuel cell. The main gas species in the anode chamber at 850 °C was mostly carbon monoxide, which was generated from the chemical reaction of carbon and molten carbonates. The concentration of CO was reduced as time passed because the reactivity of carbonates was weakened. The open circuit voltage was directly dependent on the CO concentration. The gases in the anode chamber had a vertical concentration distribution; the highest CO and the lowest CO₂ concentrations were observed near the electrode. However, the voltage in the polarization state was less dependent on the gas composition. A polarization state of 150 mA cm^–2 allowed the oxidation of CO, resulting in an increased CO₂ concentration near the electrode. The enlarged CO₂ partial pressure facilitated CO generation through the recombination of carbonate ions (CO₃^2–). Decreasing the temperature from 850 to 750 °C reduced the level of carbon monoxide at the anode. The presence of CO as a main component in the anode concludes that the oxidation of solid carbon takes place through the gasification of carbon to CO, then electrochemically to CO₂.     

冷柱头进样气相色谱法分析橡胶防护蜡的碳数分布

研究冷柱头进样气相色谱法分析橡胶防护蜡的碳数分布以及正构烷烃/非正构烷烃比例。结果表明,采用冷柱头进样方法,在样品量为10 mg、样品完全溶解后静置10~30 min并取上层清液以及进样量为1μL时,分析得到的气相色谱峰的峰形和响应信号最优。本方法测定橡胶防护蜡的碳数分布以及正构烷烃/非正构烷烃比例结果准确、可靠。