海洋大气环境对铝合金电连接器壳体腐蚀及电气性能影响

目的研究海洋大气环境对2A12和6061铝合金电连接器性能的影响。方法开展2A12和6061铝合金电连接器在海南万宁试验站4 a棚下暴露试验,通过宏微观形貌观察和电气性能测试对比分析两种铝合金电连接器壳体的腐蚀差异和电气性能变化。结果两种铝合金电连接器壳体均出现镀层鼓泡、剥落和基体腐蚀,6061铝合金电连接器壳体腐蚀程度高于2A12铝合金电连接器。2A12铝合金基体发生点蚀和晶间腐蚀,6061铝合金基体发生剥蚀,基体腐蚀产物堆积,导致镀镍层开裂剥落,进而失去防护作用。相对于导通性能、耐压强度,电连接器的绝缘电阻对海洋大气环境更为敏感。结论铝合金化学镀镍壳体电连接器在热带海洋大气环境下不适宜长期使用。     

Effects of solution conditions on the physicochemical properties of stratification components of extracellular polymeric substances in anaerobic digested sludge

The composition and effects of solution conditions on the physicochemical properties of the stratification components of extracellular polymeric substances (EPS) in anaerobic digested sludge were determined. The total EPS in anaerobic digested sludge were extracted by the cation exchange resin method. Another EPS extraction method, the centrifugation and sonication technique was employed to stratify the EPS into three fractions: slime, loosely bound (LB)-EPS, and tightly bound (TB)-EPS from the outside to the inside of the anaerobic digested sludge. Proteins and polysaccharides were dispersed uniformly across the different EPS fractions, and humic-like substances were mainly partitioned in the slime, with TB-EPS second. Protein was the major constituent of the LB-EPS and TB-EPS, and the corresponding ratios ranged from 54.0% to 65.6%. The hydrophobic part in the EPS chemical components was primarily comprised of protein and DNA, while the hydrophilic part was mainly composed of polysaccharide. In the slime, the hydrophobic values of several EPS chemical components (protein, polysaccharide, humic-like substances and DNA) were all below 50%. The protein/polysaccharide ratio had a significant influence on the Zeta potentials and isoelectric point values of the EPS: the greater the protein/polysaccharide ratio of the EPS was, the greater the Zeta potential and the higher the isoelectric point value were. All Zeta potentials of the EPS showed a decreasing trend with increasing pH. The corresponding isoelectric point values (pH) were 2.8 for total EPS, 2.2 for slime, 2.7 for LB-EPS, and 2.6 for TB-EPS. As the ionic strength increased, the Zeta potentials sharply increased and then gradually became constant without charge reversal. In addition, as the temperature increased (< 40°C), the apparent viscosity of the EPS decreased monotonically and then gradually became stable between 40 and 60°C.     

上海地区不同类和不同强度灰霾季节分布特征

主要采用美国宇航局(NASA)2007年1月-2010年11月CALIPSO卫星搭载的正交极化云-气溶胶激光雷达(CALIOP)L1产品及地面气象观测资料,分析得到上海地区干霾和湿霾、不同强度灰霾天气的季节分布特征,并重点研究了发生干霾时气溶胶散射强度、粒子规则性和尺度大小随季节的变化规律。结果表明:灰霾的发生具有较明显的季节性,春季为干霾高发期,其次是夏冬季;夏冬两季轻度以上干霾发生比例均大于春季与秋季;大气中主要以小尺度、较规则的气溶胶粒子为主;干霾时,气溶胶粒子和不同量级色比值所占比例季节变化不大;夏季发生干霾时小尺度粒子所占比例最大。     

Assessment of properties of Tunisian agricultural waste composts: Application as components in reconstituted anthropic soils and their effects on tomato yield and quality

Organic soil improvers are mainly used for their potential for preventing soil losses. This study investigates the physicochemical properties of six different organic soil improvers and their effects on the properties and productivity of reconstituted anthropic soils during short-term application compared to farm manure. Treatment materials were obtained from Tunisian agricultural waste composts (almond shell (AS), sesame bark (SB), olive cake (OC), olive mill wastewater sludge (OMWS) and poultry manure (PM)) as well as mixtures of compost-manure (CM). The characterization of soil conditioners shows that (i) nitrogen contents are higher in olive wastes and PM-based composts; (ii) carbon/nitrogen ratio (C/N) and the organic matter (OM) contents are in the ranges of 14.1-29.7 and 19.3-64.5%, respectively; (iii) the electrical conductivity (EC) is higher in manure (M) and compost-manure mixture (4.8-10.4 mS/cm) and (iv) pH values are alkaline (8.2-8.8). Treatments were applied as components of a reconstituted soil at a rate of 14 kg/m². Except for the manures, the mixtures of soil and treatment material (in a ratio of 600 L/28 kg) were placed in metallic basins to form the reconstituted anthropic soil. Plot areas of 2 m² were used for each treatment and 2 × 2 m² for the control. An assessment of the geochemical properties of soils during the cultivation period reveals variations in soil organic matter (SOM) contents as well as pH and EC values. Soil productivity is determined by quantitative and qualitative comparison of tomato fruits obtained from each plot amended with manure-treated soil.     

Soil organic carbon of degraded wetlands treated with freshwater in the Yellow River Delta, China

Supplying freshwater is one of the important methods to help restore degraded wetlands. Changes in soil properties and plant community biomass were evaluated by comparing sites with freshwater treatment versus reference sites following freshwater addition to wetlands of the Yellow River Delta for 7 years. The results indicated that soil organic carbon (SOC) was significantly increased in all wetland sites that were treated with freshwater compared to the reference sites. The treatment wetlands had greater total nitrogen (TN), lower pH and electrical conductivity and higher water content in the soil compared to the reference wetlands. In general, the upper soil layer (0-20 cm) had greater SOC than the lower soil layer (20-40 cm). The increase of SOC in the freshwater reintroduction wetlands was higher in the Suaeda salsa plant community (mean ± standard error) (6.89 ± 0.63 g/kg) and Phragmites communis plant community (4.11 ± 0.12 g/kg) than in the Tamarix chinensis plant community (1.40 ± 0.31 g/kg) in the upper soil layer. The differences were especially marked between the treated and reference wetlands for SOC and TN in the P. communis plant communities. The C:N ratio of the soil was significantly greater in the treated compared to the reference wetlands for the S. salsa plant community. Although the C: N ratios increased after treatment, they were all <25 suggesting that N availability was not limiting soil organic matter decomposition. Our results indicate that freshwater addition and the concomitant increase in soil moisture content enhances the accumulation of SOC in the Yellow River Delta.     

光质对烤烟生长发育、主要经济性状和品质特征的影响

以烤烟（Nicotiana tabacum）云烟87为材料,在烤烟团棵期和打顶期用透光率相近的有色薄膜分别对其进行遮光处理直到采收结束,研究光质对烤烟生长发育、主要经济性状和品质特征的影响。结果表明：蓝光有促进烟株生殖生长和延缓烟叶成熟的作用,红光、黄光和白光对烟株的生育进程无明显影响,打顶期遮光有延长烟株大田生育期的趋势。光质对叶片生长发育影响最大,红光和蓝光的影响效应主要表现在烟叶生育前期,黄光和白光的影响效应主要体现在烟叶生育后期。自然光和红膜下烟株的农艺性状综合表现最好,红光有促进烟茎生长和叶片发育的作用,蓝光和黄光则抑制茎干生长和降低叶面积。烟株生长前期增加红光比例有助于初烤烟叶主要经济性状的改善,后期蓝光的作用逐渐凸显。烟株不同生长时期红光和黄光的适当组合在改善烟叶品质中起着重要作用,烟株生长前期增加红光比例有利于降低初烤烟叶烟碱和蛋白质含量,提高糖类物质含量和评吸质量,但对氧化钾含量作负效应贡献;烟株生长后期提高黄光比例可使初烤烟叶的化学成分更为协调,对吸食品质有较好的提升作用。     

粉垄耕作对耕地土壤细菌群落多样性及微生物网络结构的影响

为了解粉垄耕作对耕地土壤细菌群落多样性和结构分布的影响,以及微生物生态分子网络结构和物种之间的相互作用关系.以宁夏引黄灌区不同耕作方式下耕地土壤为研究对象,设置粉垄耕作(DVRT)和传统耕作(CT)这2种处理,采用Illumina MiSeq技术对不同处理的耕地土壤细菌群落进行了分子生态网络分析.结果表明,0～20 cm土层中,DVRT比CT处理显著提升了总有机碳(TOC)、总氮(TN)、碱解氮(AN)、总磷(TP)、有效磷(AP)和总钾(TK)的含量;20～40 cm土层中,DVRT比CT处理显著提升了TOC、 TN、 TP、 AP、 TK和有效钾(AK)的含量.DVRT处理的含水量(WC)显著提高了8.13%～13.30%,pH和电导率(EC)分别降低了4.51%～5.85%和12.5%～13.33%.玉米不同生育期和土层中,DVRT处理的Shannon和Ace指数均增加.优势细菌门为：放线菌门、变形菌门、绿弯菌门、酸杆菌门和芽单胞菌门.细菌群落β多样性结果显示,DVRT和CT处理的土壤细菌群落结构差异明显.冗余分析和偏曼特尔检验结果表明,pH、 EC和TP是影响细菌群落结构多样性...     

Effects of protein properties on ultrafiltration membrane fouling performance in water treatment

Protein-like substances always induce severe ultrafiltration (UF) membrane fouling. To systematically understand the effect of proteins, regenerated cellulose UF membrane (commonly used for protein separation) performance was investigated in the presence of bovine serum albumin (BSA) under various water conditions. Results showed that although trypsin enhanced the membrane flux via proteolysis, catalysis took a long time. Membrane fouling was alleviated at high solution pH and low water temperature owing to the strong electrostatic repulsion force among BSA molecules. Both Na⁺ and Ca²⁺ could increase membrane flux. However, Ca²⁺ played a bridging role between adjacent BSA molecules, whereas membrane fouling was alleviated via a hydration repulsion force with Na⁺. The order of influence on membrane fouling was as follows: Ca²⁺ concentration > Na⁺ concentration > pH > temperature > trypsin concentration. Furthermore, a polyvinylidene fluoride UF membrane experiment showed that Ca²⁺ could reduce the fouling induced by BSA. Thus, the differences in UF membrane performance will have application potential for alleviating UF membrane fouling induced by proteins during water treatment.     

燃用生物柴油对柴油机颗粒生成和排放特性研究进展

为深入研究生物柴油对柴油机颗粒排放的影响,在总结国内外相关研究进展的基础上,通过研究生物柴油的化学组成和物理特性,讨论了生物柴油产生颗粒的特殊性及其对环境的影响.在此基础上,从PAHs（polycyclic aromatic hydrocarbons,多环芳烃）的形成途径角度简要分析了生物柴油颗粒形成的机理,并从生物柴油的3个关键性质入手,分析了其对颗粒排放的规律和影响.最后,以实际柴油机运行时的5项参数为基础,讨论柴油机实际使用生物柴油对颗粒排放的影响.结果表明:①不同材料和产地生物柴油的理化特性和对颗粒排放的影响有很大不同,但总体有利于减少对人体和环境的有害排放.②生物柴油将改变颗粒形成过程中半挥发性物质在微晶核表面的吸附,富氧作用也使燃烧热解后生成的颗粒尺寸更小,减少40%~50%;同时,纳米结构上的变化增加了生物柴油颗粒的反应活性,形成了更多30 nm以内的核态模式颗粒,更容易被人体吸收.③脂肪酸链的长度、不饱和度和含氧量对生物柴油颗粒排放量的减少发挥了重要作用,而柴油机参数的不同也对生物柴油的颗粒排放十分重要.④生物柴油对颗粒生成机理的关键在于复杂的含碳前驱物的生成路径.使用生物柴油总体上可减少前驱物的排放量,其主要成分为四元环和五元环,占总排放量的58.70%以上,但苯并蒽和?分别上升了44%和340%.研究显示,柴油机燃用生物柴油对颗粒排放有积极的一面,但在超细颗粒和某些特定前驱物控制上仍需引起高度重视.