瓦斯气体在煤层中的扩散机理及模式

根据气体在多孔介质中的扩散模式 ,结合煤结构的实际特点 ,分析了瓦斯气体在煤孔隙中的扩散机理 ,得出瓦斯在煤体中几种扩散模式 :菲克型扩散、诺森扩散、过渡型扩散、表面扩散和晶体扩散。从微观上看 ,影响瓦斯气体在煤层中扩散的主要因素是瓦斯气体的平均自由程和煤不同尺寸微孔隙的分布情况。根据不同孔隙分布的煤层 ,探讨了各种扩散模式的适用条件     

碳酸钙自发沉淀析出的动力学研究

通过记录析晶过程中溶液各组份随时间的变化关系,研究了不同过饱和度的碳酸钙水溶液的沉淀动力学过程．实验结果显示,异相成核是主导的成核机制．通过实验数据计算出了表面二维晶核的棱自由能为２．５３ × １０－８ｍＪ·ｍ－１．实验数据表明,碳酸钙晶体生长的过程是扩散控制过程．     

Novel polymer monolith microextraction using a poly-(methyl methacrylate-co-ethylene dimethacrylate) monolith and its application to the determination of polychlorinated biphenyls in water samples

A novel and simple method based on polymer monolith microextraction (PMME) coupled to gas chromatography with electron-capture detection (GC-ECD) was developed for the determination of six polychlorinated biphenyls (PCBs) residues in water samples. The proposed method used poly-(methyl methacrylate-co-ethylene dimethacrylate) (MMA-co-EDMA) monolith as extraction media. Several factors affecting experiments such as sample flow rate, sample volume, the type of eluent, eluent volume, eluent flow rate, effect of salt addition and carry over effect were investigated and optimized systematically. The limits of detection (LODs) for six PCBs were 0.028-0.043 ng mL⁻¹ in water samples. The intra-day and inter-day precisions (R.S.D.) were less than 9.2% and 9.6%, respectively. The proposed method was successfully applied to the determination of six PCBs in tap water, lake water and industrial waste water and the trueness has been evaluated by recovery experiments. The obtained relative recoveries were in the range of 63.3-105.6%.     

Naphthenic acid biodegradation by the unicellular alga Dunaliella tertiolecta

Naphthenic acids (NAs) are a major contributor to toxicity in tailings waste generated from bitumen production in the Athabasca Oil Sands region. While investigations have shown that bacteria can biodegrade NAs and reduce tailings toxicity, the potential of algae to biodegrade NAs and the biochemical mechanisms involved remain poorly understood. Here, we discovered that the marine alga Dunaliella tertiolecta is able to tolerate five model NAs (cyclohexanecarboxylic acid, cyclohexaneacetic acid, cyclohexanepropionic acid, cyclohexanebutyric acid and 1,2,3,4-tetrahydro-2-naphthoic acid) at 300 mg L⁻¹, a level which exceeds that of any single or combination of NAs typically found in tailings ponds. Moreover, we show that D. tertiolecta can metabolize four of the model NAs. Analysis of NA-amended cultures of D. tertiolecta via low resolution gas chromatography-mass spectrometry allowed us to quantify decreasing NA levels, identify metabolites, and formulate putative mechanisms of biodegradation. Degradation of cyclohexanebutyric acid and cyclohexanepropionic acid proceeded via β-oxidation and resulted in the transient accumulation of cyclohexaneacetic acid and cyclohexanecarboxylic acid, respectively. Cyclohexanecarboxylic acid was metabolized via 1-cyclohexenecarboxylic acid suggesting that further degradation may occur by step-wise β-oxidation. When D. tertiolecta was inoculated in the presence of oil sands tailings water from the Athabasca region, biodegradation of single-ring NAs was observed relative to controls. This result corroborates the trend we observed with the single-ring model NAs.     

氯气泄漏扩散模型的初步研究

根据京沪液氯泄漏的一些数据,选取液氯泄漏的瞬间为研究范围,设定液氯泄漏的瞬间为2 min,大气压力为10.132 5 kPa,温度为15℃,风速为6m/s,假设液氯泄漏后全部变成蒸气,重气云团半径为10 m,利用重气云扩散模型--盒子模型,对氯气云团扩散后果进行定量计算,得到氯气泄漏瞬间的伤害范围分别是致死区0.042 9 km2,重伤区0.0979 km2,轻伤区1.067 km2.据此判断,氯气泄漏事故后果非常严重.提出了该模型的不足和需要改进的地方.     

新疆油田盆5气田放空气回收技术应用

新疆油田盆5气田采用分子筛对天然气处理站的放空气进行回收,介绍了分子筛的吸附原理、回收技术原理及工艺流程、净化脱水压力稳定安全措施等。通过优化破乳剂类型及注入量,净化脱水后的放空气满足回收利用要求。此项回收技术的利用,每年可减排废气5209.2×104m3,回收天然气约360×104m3,增加经济效益360万元。     

重大工程对血吸虫病流行区扩散的潜在影响

归纳了我国三峡工程、退田还湖及南水北调等一系列重大工程所引起水位、植被及微生物气候等生态环境要素变化对血吸虫唯一中间宿主钉螺分布的影响,分析了血吸虫病疫区的变化趋势和钉螺北移的可能性。研究表明三大工程实施区存在血吸虫病流行的潜在危险,加之我国新增有螺面积明显增多,血吸虫病疫情呈此消彼涨态势,血防工作形势依然严峻。当前国内有关工程对生态环境及血吸虫病影响的研究,主要为局部的调查报告及在现有基础上预测工程对血吸虫病流行的可能影响,生态环境变化还需要时间来验证。因此,建议应用GIS和RS等技术,监测分析生态环境变化,并进一步研究社会经济变动与血吸虫病传播的关系,同时,工程实施地区应提高疫区群众自我防护意识和能力,并结合林业、水利工程建设对有螺环境进行改造.     

Organic–Inorganic Hybrid Coatings for the Modification of Barrier Properties of Poly(lactic acid) Films for Food Packaging Applications

Organic–inorganic hybrid coatings based on poly(ε-caprolactone), poly(ethylene oxide) or poly(lactic acid) as organic phase and silica from tetraethoxysilane as inorganic phase were prepared by the sol–gel approach. Coatings were applied onto poly(lactic acid) films for food packaging in order to improve its barrier properties towards oxygen and water vapour. All the prepared coatings were dense, homogeneous layers characterized by a good adhesion to the substrate. The permeance of the coating layers resulted one order of magnitude lower than that of the uncoated poly(lactic acid) (PLA) film. The hydrophilic character of the coating did not permit to gain a significant decrease in the water vapour permeance. The perfect visual transparency of the coatings allows their application without worsening of the esthetical properties of the substrate PLA film.     

Method for the determination of selected organochlorine pesticides and polychlorinated biphenyls in human serum based on a gel permeation chromatographic clean-up

A gel permeation chromatographic (GPC) clean-up based method was developed for determination of selected organochlorine pesticides and polychlorinated biphenyls in human serum. The method permits automation of the sample extract clean-up stage and is designed to work with small amounts of sample. Different working variables were studied in its development, including injection volume, flow rate, and fat amount as the most representative coextract. The method provides solvent and time savings. Initial extraction was performed using 96-well solid-phase disk extraction plates, and quantification was performed by gas chromatography with electron capture detection and mass spectrometry. Recoveries of PCB congeners 28, 52, 101, 118, 138, 153, and 180 and organochlorine pesticides HCB, β-HCH, γ-HCH, heptachlor epoxide, p,p′-DDE, and p,p′-DDT at two spiking levels ranged from 55% to 115% with relative standard deviations ranging from 2.0% to 14.6%. Limits of quantification ranged from 0.06 to 0.16 ng mL⁻¹ for PCBs and from 0.12 to 0.36 ng mL⁻¹ for organochlorine pesticides. Finally, the method was applied to the analysis of 38 serum samples and the results were compared with those of another procedure validated at the laboratory.     

建筑物对高架点源大气污染物扩散影响的模拟研究

运用数值方法对城市中高架点源排放大气污染物的扩散规律进行了模拟研究,在计算区域内建立了三维数学模型,并将拉格朗日法描述的颗粒轨道模型耦合到风场。本研究计算了地面风速为3 m/s时的大气流场,并模拟研究了该风场条件下气体污染物的扩散和固体颗粒污染物的运动轨迹。通过分析模拟结果,给出了高架点源中排放的气体污染物的扩散区域和固体颗粒污染物运动轨迹的变化规律。