不锈钢-气氮板式热沉仿真研究

目的研究不锈钢-气氮板式热沉中,氮气压力、氮气入口流速以及热沉自身流道深度对热沉传热性能的影响。方法利用AnsysFluent软件,对板式热沉壁面温度分布情况以及进出口压力损失进行模拟仿真。结果提高氮气压力和氮气入口速度可以提升热沉的温度均匀性,但热沉进出口压力损失也会增大。对于气氮-板式热沉而言,流道深度的改变对热沉温度均匀性的影响不大,但流道深度较小时,进出口压力损失较大。结论建议在设计气氮-板式热沉时,流道深度选择在8~10 mm,外流程中氮气压力控制在0.3~0.4 MPa,氮气流速控制在20 m/s为宜。     

Microstructures and electrochemical behaviors of the friction stir welding dissimilar weld

By using optical microscope, the microstructures of 5083/6082 friction stir welding (FSW) weld and parent materials were analyzed. Meanwhile, at ambient temperature and in 0.2 mol/L NaHS0₃ and 0.6 mol/L NaCl solutionby gravimetric test, potentiodynamic polarization curve test, electrochemical impedance spectra (EIS) and scanning electron microscope (SEM) observation, the electrochemical behavior of 5083/6082 friction stir welding weld and parent materials were comparatively investigated by gravimetric test, potentiodynamic polarization curve test, electrochemical impedance spectra (EIS) and scanning electron microscope (SEM) observation. The results indicated that at given processing parameters, the anti-corrosion property of the dissimilar weld was superior to those of the 5083 and 6082 parent materials.     

Expression of sulfur uptake assimilation-related genes in response to cadmium, bensulfuron-methyl and their co-contamination in rice roots

The responses of sulfur （S） uptake assimilation-related genes＇ expression in roots of two rice cultivars to cadmium （Cd）, bensulfuron-methyl （BSM） and their co-contamination （Cd＋BSM） were investigated by gene-chip microarray analysis and quantitative real-time PCR （QRT-PCR） technology. Treatments of Cd and Cd＋BSM induced expression of sulfate transporter and permease genes, and promoted sulfate uptake in rice roots. Cd＋BSM could alleviate Cd toxicity to cv. Fengmeizhan seedlings, probably due to Cd＋BSM promoting greater S absorption by seedlings. Cd and Cd＋BSM induced expression of sulfate assimilation-related genes, and thus activated the sulfur assimilation pathway. Cd and Cd＋BSM induced expression of phytochelatin synthase and metallothionein genes, and induced expression of glutathione S-transferases （GSTs）, glutathione synthase （GS） and S- containing antioxidation enzyme genes, which detoxified Cd2＋. It is suggested that （to cope with the toxicity of Cd, BSM and their co-contamination） the S uptake and assimilation pathway was activated in rice roots by increased expression of related genes, thus enhancing the supply of organic S for synthesis of Cd or BSM resistance-related substances.     

Unregulated emissions from diesel engine with particulate filter using Fe-based fuel borne catalyst

The alteration and formation of toxic compounds and potential changes in the toxicity of emissions when using after-treatment technologies have gained wide attention. Volatile organic compound（VOC）, carbonyl compound and particle-phase polycyclic aromatic hydrocarbon（PAH） emissions were tested at European Steady State Cycle（ESC） to study unregulated emissions from a diesel engine with a fuel-borne catalyst and diesel particulate filter（FBC–DPF）. An Fe-based fuel-borne catalyst was used for this study. According to the results, brake specific emissions of total VOCs without and with DPF were 4.7 and4.9 mg/kWh, respectively, showing a 4.3% increase. Benzene and n-undecane emissions increased and toluene emission decreased, while other individual VOC emissions basically had no change. When retrofitted with the FBC–DPF, total carbonyl compound emission decreased 15.7%, from 25.8 to 21.8 mg/kWh. The two highest carbonyls, formaldehyde and acetaldehyde, were reduced from 20.0 and 3.7 to 16.5 and 3.3 mg/kWh respectively. The specific reactivity（SR） with DPF was reduced from 6.68 to 6.64 mg/kWh. Total particle-phase PAH emissions decreased 66.4% with DPF compared to that without DPF. However, the Benzo[a]pyrene equivalent（BaPeq） with DPF had increased from 0.016 to 0.030 mg/kWh.Fluoranthene and Pyrene had the greatest decrease, 91.1% and 88.4% respectively. The increase of two- and three-ring PAHs with DPF indicates that the fuel-borne catalyst caused some gas-phase PAHs to adsorb on particles. The results of this study expand the knowledge of the effects of using a particulate filter and a Fe-based fuel-borne catalyst on diesel engine unregulated emissions.     

Phytoremediation of levonorgestrel in aquatic environment by hydrophytes

Adsorption and degradation of levonorgestrel （LNG） by two hydrophytes, Cyperus alternfolius （CA） and Eichhornia crassipes （EC）, were investigated under light-shielding conditions in the water column. Variations of LNG concentrations in water, plant root epidermis, root, stem and leaf of the plants were analyzed. The results indicated that the removal efficiency of LNG by hydrophytes over the period of 50 days was significantly greater than the blank control （p 〈 0.05）, with the removal rates of 79.80%± 3.10% and 78.86% ± 2.55% for CA and EC, respectively. Compared with bio-adsorption, bio-conversion of LNG was found to be the dominant elimination pathway, evidenced by relatively high conversion rates （77.31% ±2.68% for CA and 77.82% ± 2.95% for EC）, while the adsorption rates were lower （1.77% ± 0.90% for CA and 1.05% ± 0.40% for EC）. The bio-adsorption and conversion of LNG showed no significant differences between the two hydrophytes. Additionally, the mineralization on root epidermis played an important role in the reduction of LNG in water.     

饮用水源地的水华对人体健康风险评价

饮用水源地的水华现象近年来在世界各地不断爆发,给人类饮水安全造成极大的威胁。本文通过检测微囊藻毒素和三卤甲烷类物质,利用急性暴露安全阈值（浓度）计算模型,计算出了各自的急性暴露安全阅值,并对健康风险进行了评价。     

两种喹诺酮类抗生素对亚心形扁藻的毒性效应研究

研究了恩诺沙星和盐酸环丙沙星两种喹诺酮类抗生素对亚心形扁藻的毒理学效应。经多组不同浓度的两种抗生素处理后,分别对扁藻的96EC50、叶绿素和胞外聚合物（EPS）进行分析。结果表明,两种抗生素在低浓度时对扁藻生长具有促进作用,而在高浓度时体现抑制毒性作用。高浓度时,抗生素浓度越高对扁藻的生长、叶绿素和胞外聚合物抑制效果越明显,但当浓度达到一定高度后,抑制会达到其阈值。恩诺沙星和盐酸环丙沙星对扁藻的半生长抑制率分别为19.8 mg/L和28.7 mg/L。     

明矾石在水体微藻去除中的应用研究

以温州市某大学校区内富营养化水体为研究对象,采用本地明矾石对含藻水体进行混凝除藻、除浊实验研究,分别进行投加量、搅拌强度、搅拌时间、静置时间及pH值对微藻去除效率的影响研究,以获得处理工艺的最佳条件,为恢复河流水体生态自净功能提供理论基础.试验中对投加明矾石前后,水体中浊度、总磷、氨氮和总氮进行了测定,结果表明：明矾石最佳投加量为0.35 g/L,最佳搅拌方式为200 rpm搅拌4 min;最佳静置时间为25 min;在碱性或中性水体的处理效果尤佳.     

不同溶剂和反应温度对污泥热液化制取生物质油性质影响研究

选取4种溶剂(水、乙醇、正己烷、水-乙醇共溶济)作为污泥热液化制取生物质油的溶剂,分析溶剂种类和反应温度对热液化效果和生物质油性质的影响.结果表明:相同温度下,生物质油产率随溶剂种类变化趋势为:乙醇水-乙醇共溶剂正己烷水,最高产率为54.82%(乙醇溶剂,240℃).污泥有机物转化率随溶剂种类变化趋势为:水-乙醇共溶剂乙醇水正己烷,最高有机物转化率为96.40%(水-乙醇共溶剂,330℃).污泥经热液化处理后,碳、氢、氮、硫元素在生物质油中富集,氧含量下降,热值36 MJ·kg-1(乙醇、240℃除外).不同溶剂油成分差别较大,采用水或正己烷,产物主要是脂肪酸类、烷烃及部分酰胺和腈类,采用乙醇或水-乙醇共溶剂,产物主要是酯类、烷烃类.生物质油沸点集中分布在250~500℃,添加乙醇溶剂可显著提高生物质油轻组分含量.     

盾构隧道纵向地震响应简化动力有限元法分析(英文)

本文重点关注对盾构隧道的纵向地震响应分析方法的研究,提出了一种简化的动力有限元分析方法。这种方法采纳了响应位移法的一些基本思想,采用和响应位移法一样的环梁和土弹簧模型,但采用动力有限元法来评估地基地震动,而摒弃了响应位移法中采用的地基振动为谐波形式的假定。与响应位移法相比,简化动力有限元法能够提高地基震动的计算精度,从而提高结构响应的计算精度;而与三维连续模型相比,新方法的计算规模小得多,从而能够大幅提高计算效率。然后,本文分别采用相应位移法和新提出的简化动力有限元法,对武汉长江隧道盾构段隧道进行了纵向地震响应分析,并对这2种方法计算结果的差异进行了分析。