多晶铂电极电催化氧化苯酚的电化学过程

采用循环伏安(CV)、Tafel曲线、交流阻抗(EIS)等方法研究苯酚在多晶铂电极上的电氧化过程.在扫描速度分别为10 mV/s、20 mV/s、50 mV/s、100 mV/s和200 mV/s时,以0.25 mol/L的Na2SO4为支持电解质,考查500 mg/L苯酚在铂电极上氧化的CV曲线变化规律.测试表明发生了不可逆的电氧化反应,氧化峰位置为0.926 V(vs.Ag/AgC l,扫描速度50 mV/s,).苯酚氧化峰电流值与CV扫描速率的关系表明苯酚的氧化反应是由扩散过程和吸附过程共同控制的电化学氧化过程.分别选用0.1和1.0 mol/L的H2SO4溶液为电解液,测试Pt电极析氧反应的Tafel曲线,Tafel斜率为149 mV.采用EIS分析苯酚的电氧化反应,结果表明在高频段存在苯酚吸附的特征容抗弧.     

硼掺杂金刚石薄膜电极降解青霉素G钠废水机制

针对抗生素废水中青霉素类物质难于生化降解的问题,采用直流等离子体化学气相沉积方法制备硼掺杂金刚石(boron-doped diamond, BDD)薄膜电极,以典型的青霉素G钠为目标污染物,对BDD电极降解青霉素的规律及降解历程进行研究.结果表明,不同质量浓度的青霉素G钠在电极上均能够被完全降解,发生电化学燃烧.青霉素G钠和化学需氧量(chemical oxygen demand, COD)的降解符合一级反应动力学,电流密度从10 mA/cm²提高到20 mA/cm²时,青霉素G钠和COD的反应速率常数分别增加了51.3%和29.1%.BDD电极上青霉素G钠的降解主要受液相传质过程控制,电流效率(current efficiency, E_C)与青霉素G钠的质量浓度和电流密度有关.得到了青霉素G钠在BDD电极上的降解历程,主要的中间产物有青霉酸、异构青霉酸、青霉烯酸和青霉噻唑酸.     

一株利用木糖用于酒精生产酵母菌的筛选

为获得高效发酵木糖生产酒精的菌株,从牛羊粪便的堆积处进行木糖利用菌的分离筛选,获得一株利用木糖的菌株,根据菌株的生理生化和分子生物学特性,鉴定该菌株为热带假丝酵母(Candidatropicals).以逐渐提高底物中木糖浓度的方法,对该菌株利用木糖的能力进行了驯化,同时对该菌发酵木糖生产酒精的工艺和发酵培养基组分进行了优化.驯化后,在厌氧条件下,木糖浓度在7%,木糖利用率为65.2%,酒精产率达到理论产量的21.9%.在优化培养基的条件下,以木糖/葡萄糖混合糖为碳源,控制pH为5.5,温度35℃接种量为10%,厌氧培养96 h,木糖和葡萄糖转化的酒精产量分别为理论产量的37.7%和79.2%,同时伴有30.2 g/L的木糖醇产生.实验结果表明,该菌株具有较高的木糖和葡萄糖的利用能力,是具有同时发酵葡萄糖和木糖产酒精的天然菌株.     

Effect of wet surface treated nano-SiO<Subscript>2</Subscript> on mechanical properties of polypropylene composite

Nano-SiO2/polypropylene composite was prepared by melt-blending process. The nano-SiO2 particles were organized by wet process surface treatment with silane coupling agent KH-570. The effect of mass fraction of nano-SiO2 particles and dosage of KH-570 on the toughening and strengthening of PP matrix were investigated based on the fractography of impact notch and the analysis of crystal structure by X-ray and dispersive structure of nano-SiO2 by TEM. Results show that the impact and flexural strength and modulus of the composite are improved obviously with low loading of nano-SiO2 （3 wt%-5 wt%）, and the izod impact strength of PP increases twice with 4 wt% nano-SiO2. The nano-SiO2 particles treated can disperse into the matrix resin, which has evident heterogeneous nucleation effects on the crystallization of PP. The optimal toughening and strengthening effects of PP matrix can be obtained when the content of nano-SiO2 and KH-570 are 4 wt% and 3 wt%, respectively.     

电极生物膜法反硝化工艺条件及过程

为获得具有良好反硝化性能的电极生物膜,以活性污泥为出发菌株,分别以连续和间歇培养方式在石墨电极上生长电极生物膜,研究碳氮比、电流强度、pH等工艺条件对电极生物膜反硝化过程的影响.结果表明:当碳氮比小于3.0时,体系的反硝化速率与碳氮比成正比;而在3.0以后,反硝化速率的增长开始趋于缓慢;电流强度为20mA时,硝酸盐去除效率达到最大值9.26mg/(L.h),继续加大电流,硝酸盐的去除率降低;当pH等于7时,硝酸盐氮的去除负荷最大,为7.89mg/(g.h),而pH小于或大于7时,生物膜的反硝化性能均有所降低.对单纯电极法、单纯生物膜法和电极生物膜法进行比较研究,证明电极生物膜法对硝酸盐的去除是电与生物膜共同作用的结果.     

Application of nitrogen-fixing cyanobacteria in restoration of saline and alkaline soils of Songnen Plain in China

The salt-resistant nitrogen-fixing cyanobacteria 888 was experimentally applied to the reclamation of saline and alkali soil in Songnen Plain in China. The pH, electrical conductivity (EC) and sodium adsorption ratio (SAR) of different saline soils were studied and compared. Results show that different saline soils exhibit various physico-chemical properties. Saline-sodic soils in Songnen Plain are ameliorated by using nitrogen-fixing blue-green algae 888 in the experiment. It is indicated that cyanobacteria 888 can grow in saline and alkaline soils, and the conditions favorable for its growth are soil moisture of 50% and dry algae inoculation at 0.03 mg/cm2. The main actions of nitrogen-fixing cyanobacteria are keeping the adsorbability of rubber sheath for sodium, increasing the organic matter content of the soils and decreasing the pH and the degree of salinity in the soils. But the arid climate and soil depth are the main factors that limit the restoration of saline and alkaline soils.     

硼掺杂对直流热阴极CVD金刚石薄膜生长特性的影响

采用直流热阴极CVD法以B(OCH3)3为掺杂剂制备了硼掺杂金刚石薄膜,利用等离子体发射光谱、SEM、Raman和XRD研究了硼掺杂对金刚石薄膜生长特性的影响,通过与未掺杂金刚石薄膜的对比发现:在直流热阴极CVD系统中,低浓度硼掺杂条件下能够长时间维持稳定的辉光放电. 掺硼后辉光等离子体活性基团(Hα、Hβ、C2、CH)的种类没有改变,但C2基团的浓度升高,而CH基团的浓度下降,薄膜的生长速率提高到0.65mg·cm-2·h-1. 硼掺杂金刚石薄膜为多晶薄膜,晶体生长良好,取向以(111)晶面为主,质量较未掺杂薄膜有所提高. 硼原子以取代或填隙的方式掺杂进入金刚石晶格,没有破坏金刚石晶体结构.     

低温预处理对萝卜种子发芽的影响试验

为探究种子发芽检验方法中预先冷冻处理对萝卜种子发芽的影响,试验以4℃、6℃、8℃、10℃进行雪月萝卜种子低温处理,以不冷藏为对照,筛选最适合萝卜种子发芽的最适冷藏温度。用7d、8d、9d、10d、11d的时间对萝卜种子进行冷藏时间比较。另进行了纸上、纸间、砂上三种发芽方式比较,同时进行大田直播种植。试验结果表明：不同低温预先冷冻处理中以6℃发芽率和发芽势最高,8℃、10℃、4℃依次降低,4℃、6℃、8℃、10℃冷冻后的发芽率极显著优于对照组发芽率,6℃、8℃、10℃冷冻后的发芽势极显著优于对照组发芽势。冷藏时间以10d较好。不同发芽床比较结果以纸上发芽率、发芽势最高,砂上次之,二者均优于纸间发芽率。以8℃预先冷冻处理的种子发芽率与大田直播的最为一致,6℃、10℃处理的种子发芽率与大田直播的较为一致。     

Investigation on tribological behaviors of neodymium dialkyldithiophosphate

Neodymium dialkylthiophosphate (NdDDP) with alkyls of isopropyl and isooctyl were synthesized by exchanged reaction respectively. The structures of the two NdDDPs were determined using IR and XRD. Properties of anti-wear and friction-reducing of the two additives were investigated with four ball experiment and the commercial anti-wear additive ZDDP was selected as control. The elemental analysis of the wear scars after 10s friction at low stress were investigated by EDXA ( Energy Dispersion Analysis of X-ray). Primary results showed that the NdDDPs possess better lubrication ability than ZDDP. This might mainly be contributed to the formation of a boundary film containing Nd2O3, FeS and sulphate, phosphate, organo-sulfide,etc.,and a neodymium-rich diffused layer which changes the crystal structure of the surface of friction materials.     

隐身技术与隐身材料研究进展

隐身技术与隐身材料在现代国防体系中具有非常重要的意义。本文对雷达隐身技术和红外隐身技术的原理做了系统阐述,并介绍了各种雷达隐身材料和红外隐身材料的国内外研究进展,主要包括多晶铁纤维、手性吸波剂、导电高分子等雷达隐身材料以及低发射率和控制目标温度的红外隐身材料。对智能隐身材料以及多功能一体化隐身材料在隐身材料的未来发展中的作用和趋势进行了分析。