Self-assembled structure of alkyloxy substituted benzoic acid methyl ester on HOPG：An STM study

Self-assembled structures of 3,4,5-tris-dodecy-loxy benzoic acid methyl ester (E12), 3,4,5-tris-tetradecy-loxy-benzoic acid methyl ester (E14) and their mixture (E12/E14) have been studied on HOPG by scanning tunneling microscopy (STM). Dimer-like patterns induced by dipole-dipole interaction are observed in E12 and E14 monolayers. The molecules form close-packed rows and interdigitate with the alkyl chains in adjacent molecules. The structural differences are proposed to be from the different length of substituted alkyl chains. Owing to similar adsorption energy, phase separation is observed in the E12 and E14 mixed adlayer with different domains.     

非自治脉冲Lotka-Volterra系统的持久性与渐近稳定性

利用微分不等式等理论,讨论了一类非自治脉冲Lotka-Volterra种群竞争系统,得到了判断它的解的部分种群一致持久、灭绝和全局渐近稳定的一个比较结果.     

Fate of secondary effluent dissolved organic matter during soil-aquifer treatment

The reduction of mass and trihalomethane formation potential (THMFP) of dissolved organic matter (DOM) and its fractions from secondary effluent during laboratory-scale soil-aquifer treatment (SAT) soil columns were studied. Reduction in dissolved organic carbon (DOC), absorbance of ultraviolet light at 254 nm (UV-254), biodegradable dissolved organic carbon (BDOC) and nonbiodegradable dis- solved organic carbon (NBDOC) for the bulk DOM averaged 72.35%, 53.98%, 97.49% and 35.33% across the soil columns, respectively. Using XAD-8 and XAD-4 resins, DOM was fractionated into 3 fractions: hydrophobic acid (HPO-A), transphilic acid (TPI-A) and hydrophilic fraction (HPI). HPO-A was removed by 61.06%, TPI-A by 54.86% and HPI by 74.95% as DOC as a consequence of the laboratory-scale SAT, respectively. The reduction of THMFP from HPO-A, TPI-A and HPI was 27.24%, 26.24% and 36.08%, respectively. Proton nuclear magnetic resonance (1H-NMR) spectra revealed that the HPO-A isolated from the secondary effluent contained more aromatic functional groups than the corresponding TPI-A. Fourier-transform infrared (FT-IR) spectrum analysis illustrated that TPI-A had decreased hydrocarbon and increased aromatics content in the SAT columns. Specific ultraviolet light absorbance (SUVA) and specific THMFP for each DOM fraction increased across the soil columns and HPI exhibited greater increase in both than HPO-A and TPI-A. The most problematic THM precursor was found to be HPO-A with its high quantity present in recharged water and high chlorine reactivity.     

超滤膜去除地下水中硝基苯的试验研究

为解决持久性有机污染物对地下水造成的污染，以硝基苯为研究对象，考察了超滤膜对硝基苯的去除效果及影响因素。试验结果表明，当进水硝基苯浓度为85肛μg/L，超滤膜可以连续工作68h，出水小于17μg/L。地下水中铁、锰离子对去除效果没有显著影响。进水硝基苯浓度对去除效果有显著影响。当进水硝基苯浓度由85μg/L上升至340μg/L时，超滤膜连续工作时间急剧下降，仅为14h；对由硝基苯引起的膜污染，2％CH3，CH3CH2OH清洗效果最佳。作为一项应急处理技术，该工艺可以保障小城镇地区饮水安全。     

细晶铸造IN718C合金显微组织对持久性能的影响

探讨了晶粒度为ASTM 3～5级的细晶铸造IN718C合金的显微组织对持久性能的影响．通过分析细晶材料的持久断口和显微组织，发现该合金与普通铸造材料不同的是 细晶材料的持久断裂主要为沿晶断裂形式，其碳化物、Laves相和tex0\delta$相主要分布在晶界； 细晶材料在不同铸态枝晶组织中晶界上碳化物和Laves相都有降低材料持久性能的倾向．     

持久性框架Hibernate在WEB开发中的应用

首先介绍了框架的概念,然后阐述了持久性框架hibernate的体系结构,并基于hibernate框架功能,针对某电力局低压设备线损管理系统所采用的对象持久化应用作了详细介绍.     

改进的价连接指数应用于有机物生物毒性的研究

用改进的分子价连接性拓扑指数^0χ^h、^1χ^h研究了卤代芳烃、醇和含氮杂环化合物对生物毒性的相关性(QSAR)，给出了相关方程。结果表明，新方法计算方便，物理意义明确，预测值与相应的实验值较吻合。     

用阳极溶出伏安法研究天然水中铅与有机物作用的特性

将内蒙古的呼伦湖，中国南海北部的所有水样通过０．４５μｍ过滤，用阳极溶出伏安法进行测定，在天然ｐＨ下，测定了铅的表观络合容量和条件稳定常数，呼伦湖的络合容量（Ｃ．Ｃ）比海水大，ｌｏｇＫ相近，海水的Ｃ．Ｃ极大值在表层，随深度增加而减小。