Preparation of organically functionalized silica gel as adsorbent for copper ion adsorption

A novel adsorbent (AMPS-silica) was synthesized by bounding AMPS (2-acrylamido-2-methylpropanesulfonic acid) onto silica surface, which functioned with -methacryloxypropyltrimethoxysilane reagent. The adsorbent was characterized by nitrogen adsorption/ desorption measurement, thermogravimetric analysis (TGA) and potentiometric titration analysis. The TGA result indicated that the surface modification reactions introduced some organic functional groups onto the surface of silica. The surface area of AMPSsilica was 389.7 m2/g. The adsorbent was examined for copper ion removal in series of batch adsorption experiments. Results showed that the adsorption of Cu2+ onto AMPS-silica was pH dependent, and the adsorption capacity increased with increasing pH from 2 to 6. The adsorption kinetics showed that Cu2+ adsorption was fast and the data fitted well with a pseudo second- order kinetic model. The adsorption of Cu2+ onto AMPS-silica obeyed both Freundlich and Langmuir isotherms, with r2 = 0.993 and r2 = 0.984, respectively. The maximum Cu2+ adsorption capacity was 19.9 mg/g. The involved mechanism might be the adsorption through metal binding with organic functional groups such as carboxyl, amino and sulfonic groups. Cu2+ loaded on AMPS-silica could be desorbed in HNO3 solution, and the adsorption properties remain stable after three adsorption-desorption cycles.     

Bacterial community composition and abundance in leachate of semi-aerobic and anaerobic landfills

Different municipal solid waste landfill methods and landfill ages had crucial impacts on bacterial abundance and composition in leachate.     

Fe(Ⅲ)对海藻酸钙凝胶层过滤特性的影响

为考察饮用水处理膜工艺中Fe(Ⅲ)对多糖污染层过滤特性的影响,本研究以海藻酸钠为模型多糖污染物,分析海藻酸钙在有Fe(Ⅲ)及无Fe(Ⅲ)存在时形成污染层的过滤特性,并用压缩性方程及渗透性方程对凝胶层的过滤特性进行定量描述.研究结果表明,Ca2+的存在会使海藻酸钠分子间结合,形成内部结合紧密的凝胶层,产生较大的过滤阻力;往海藻酸钙溶液中进一步加入Fe(Ⅲ)后,由于可溶性Fe(Ⅲ)较易水解,加入Fe Cl3后溶液中铁离子和铁的氧化物/氢氧化物颗粒同时存在,少量Fe(Ⅲ)对海藻酸钙凝胶层的过滤特性影响不大,较多量Fe(Ⅲ)会形成铁的氧化物/氢氧化物颗粒,一定程度上改变了凝胶层的结构,使过滤性能变好.     

Mineral nutrient imbalance, DNA lesion and DNA-protein crosslink involved in growth retardation of Vicia faba L. seedlings exposed to lanthanum ions

Effects of mineral nutrient imbalance, DNA lesion and DNA-protein crosslink on growth of Vicia faba L. seedlings hydroponically cultivated in concentrations of extraneous lanthanum (La) for 20 days were investigated in the present experiment. The results showed that contents of La, Cu or K elements in roots generally changed synchronously with those in leaves, while Ca, Fe, Zn, Mg, Mn or P in the roots altered inversely to those in the leaves. Thus, the extraneous La led to redistribution and imbalance of mineral nutrient elements in the roots and leaves. DNA lesion and DNA-protein crosslink were investigated by single cell gel electrophoresis (SCGE) and sodium dodecyl sulfate/potassium (SDS/K⁺) precipitation methods, respectively. The results demonstrated that the increasing La induced DNA break and DNA-protein crosslinks (DPCs) in the seedlings. These results suggested that mineral nutrient imbalance, DNA lesion and DNA-protein crosslink were involved in the growth retardation and growth alteration of the seedlings, which may help to understand the mechanisms of rare earth elements (REEs) on plant growth.     

一种高效的硅胶中氚化水自动化解析技术

文章介绍采用温度自动控制的铸铝加热方式提取硅胶中氚化水的一种高效节能解析技术,并通过实验验证表明,该解析技术对硅胶吸附氚化水样品的最佳解析时间为15 min,此时100 g饱和硅胶样品至少能解析水7～10 mL用于液闪测量,对硅胶中氚化水的平均回收率优于99%,氚记忆效应小于万分之二。该技术与GB12375-90标准提出的氚蒸馏技术相比,具有能同时处理多个样品,可提高硅胶氚吸附样品前处理制样效率、节约能源等特点。     

固定化细胞生产L-苯丙氨酸研究

用聚乙烯醇（ＰＶＡ）凝胶包埋固定假单胞菌Ｅ４－１０６细胞,最佳ρ（ＰＶＡ）为８０ｇ／Ｌ;最适湿细胞包埋量为每ｍｌ凝胶０．３ｇ;转氨酶活力回收率为７８％,连续反应２１批次后,固定化细胞酶活力为初始最高活力的９１％;用固定化细胞进行间歇式批次反应,结果表明其酶活性半寿期为４个月;制得的固定化细胞为直径约３ｍｍ的珠状颗粒,机械强度良好,间歇式批次反应１０个月,固定化细胞凝胶颗粒无溃破     

微生物分子生态学进展[综述]

现代分子生物学技术在生态学研究中的应用大大推动了微生物生态学的发展,导致了微生物分子生态学的产生．微生物分子生态学方法弥补了传统的微生物生态学方法的不足,使人们可以避开传统的分离培养过程而直接探讨自然界中微生物的种群结构及其与环境的关系．微生物生态学研究中采用的分子生物学方法主要有核酸探针技术、ＰＣＲ扩增技术、ｒＲＮＡ序列同源性分析方法、剃度凝胶电泳方法等．这些技术方法的采用,取得了一系列重要的成果和微生物生态学研究中的突破［１～６］,使得对某些微生物的研究成为可能,并在分子水平上阐述了生态问题…     

微生物分子生态学进展

This paper summarizes some molecular techniques applied in the studies on microbial ecology,such as hybridization of nucleic acid probes,ampification of polymerase chain reaction,denaturing gradient gel electrophoresis and analyses of ribosomal RNA gene sequences,and the progress,performance,achievements and advances made from the researches of microbial ecology in recent years by using these molecular techniques．     

富氧条件下在Ag/Al2O3催化剂上C3H6选择性还原NO

比较富氧条件下,Ｃ₃Ｈ₆ 在溶胶－凝胶和浸渍２种方法制备的Ａｇ／Ａｌ₂Ｏ₃ 催化剂上还原ＮＯ的活性和热稳定性． 结果表明,从活性角度考虑,采用溶胶－凝胶法制备Ａｇ／Ａｌ₂Ｏ₃ 催化剂时,最佳Ａｇ 负载量（ｗｔ）为４％ ～６％ ,其最大活性与浸渍法制备的２％ Ａｇ／Ａｌ₂Ｏ₃ 催化剂相同,而溶胶－凝胶法制备的催化剂有更宽的活性温度范围． 随着焙烧温度提高,溶胶－凝胶法制备的Ａｇ／Ａｌ₂Ｏ₃ 催化剂的比表面和活性下降比浸渍法慢．此外,还考察了气氛中含有ＣＯ对Ａｇ／Ａｌ₂Ｏ₃ 催化剂活性的影响,结果表明活性降低,其原因可能是活性高的氧化态Ａｇ 被ＣＯ部分还原为活性低的还原态Ａｇ．     

二氧化锰颗粒对Hela细胞DNA损伤的尺度依赖性毒作用(英文)

为了观察二氧化锰颗粒物所致的尺度依赖性DNA损伤作用,将纳米尺度二氧化锰颗粒物(Nano-MnO2)和常规尺度二氧化锰颗粒物(Nor-MnO2)所致的DNA损伤进行了对比研究.将Hela细胞分别暴露于不同浓度(0、100、200、400μg·mL-1)的Nano-MnO2和Nor-MnO2中,染毒24h,采用彗星实验检测Hela细胞的DNA损伤水平.结果表明:与对照组相比,Nano-MnO2和Nor-MnO2均可使彗尾DNA百分比(TailDNA%)和尾矩(TailMoment)显著增加(p<0.01);而在同一浓度水平上,Nano-MnO2所致的DNA损伤则比Nor-MnO2所致的DNA损伤更为严重(p<0.01).结果提示:二氧化锰颗粒对Hela细胞DNA损伤具有尺度依赖性毒作用,纳米尺度比常规尺度二氧化锰颗粒毒作用更强烈.