Inhibitions of cotton seedling growth by volatile ketones emitted by cover crop residues

Low-input, sustainable agriculture (LISA) systems can include soil incorporation of residues of weeds and legume cover crop species. However, both seed germination and seedling growth of crops, including cotton (Gossypium hirsutum L.), are inhibited by volatile organic compounds emitted by these residues during decomposition. A cotton seedling-growth assay was used to demonstrate that C₄ through C₉ ketones released by decomposing legume residues significantly inhibited root and shoot elongation, root and shoot fresh and dry weight gain, and cotyledon expansion. Seedling root and shoot water relationships were relatively insensitive to those components of plant residue volatile emissions. Concentration (0.0, 0.5, 1.0, 1.5, or 2.0M/cm³ sterile greenhouse soil mix) and root-zone temperature (20 or 30°C) altered the activity of the more inhibitory ketones. Molecular weight (carbon chain length), carbon chain branching, and position of the carbonyl group also influenced ketone inhibitory activity.Mention of a commercial or proprietary product does not constitute an endorsement by the U.S. Department of Agriculture.     

UV-LED光固化体系光引发剂的新进展

本文综述了可用于UV-LED光固化体系光引发剂的研究进展，包括传统光引发剂及其衍生物（硫杂蒽酮类、二苯甲酮类和酰基膦氧化物）、新型基团的光引发剂（咔唑基、萘酰亚胺基、吩嗪基、苯丙二茂基、咪唑基和三嗪基）以及高分子光引发剂。传统光引发剂的改性和大分子光引发剂的合成，可以提高引发剂的稳定性。新型光引发剂的吸收波长与UV-LED光固化的发射波长匹配性较好，但该类光引发剂常需要加入助剂。此外，描述了氧阻聚对光固化体系的影响，指出了目前UV-LED光引发剂存在的不足，并展望了其发展应用前景。。     

Rapid detection of antigen binding by antibody fragments expressed in the periplasm of Escherichia coli

Bacterial expression systems can greatly facilitate proteinengineering of antibodies. We have developed a system for high-levelexpression of antibodies, antibody fragments, or hybrid antibodieswith novel effector functions in the periplasm of Escherichiacoli. From 5 ml of cells, a simple extraction yields sufficientmaterial for SDS-gel electro-phoresis, detection and characterizationof hapten binding. To demonstrate our system, heavy-chain variableregions and 1 light chains of a mouse anti-NP antibody weresynthesized as hybrid proteins with a bacterial signal peptide(Omp F). Each chain is secreted into the periplasm where processing(cleavage of the signal peptide), folding and heterodimer associationtake place. Periplasmic proteins are released by cold osmoticshock, and hapten-binding activity is easily detected withoutfurther manipulation. The ease of genetic engineering in thissystem will facilitate the production of immunoglobulin derivativesdesigned for specific applications, and expression of thesemolecules in a native state will allow the rapid screening ofcombinatorial libraries and the results of mutagenesis.     

磁性浮板覆盖下干旱区平原水库节水效率分析

针对干旱区平原水库水深浅、风速大、气温高、空气相对湿度低而导致蒸发损失严重的问题,在吐鲁番市胜金乡胜金沟三期水土保持水库进行了一整年不同覆盖面积的带磁性浮板与非磁性浮板覆盖水面来减少水面蒸发的试验,以此来分析相同覆盖面积下带磁性浮板成片整体分布与非磁性浮板分散分布对水库水面蒸发的节水效率。试验结果表明：在气象因素相同的情况下,带磁性浮板分别覆盖水面25％,50％和75％时,蒸发抑制率分别为27.4％,41.5％和59.1％;非磁性浮板分别覆盖水面25％,50％和75％时,蒸发抑制率分别为22.1％,38.1％和57.3％;带磁性浮板比非磁性浮板蒸发抑制率分别提高了5.3％,3.4％和1.8％。可见,带磁性浮板节水效果更加显著,对提高干旱区平原水库水资源的利用效率具有显著意义。     

改性细菌纤维素硫酸酯对Pb(Ⅱ)吸附性能的影响

以廉价且资源丰富的细菌纤维素为原料,研究制备了改性细菌纤维素硫酸酯吸附材料,并对其进行表征分析。以典型重金属污染物Pb(Ⅱ)为去除目标,考察了不同反应时间、溶液p H和反应温度等对改性细菌纤维素吸附Pb(Ⅱ)的影响。结果表明:经改性后细菌纤维素的吸附性能有所增加;其对Pb(Ⅱ)的平衡吸附量随p H的增大而增加,随温度的增加而减小;吸附过程符合拟二级反应方程和Langmuir吸附等温方程。     

The effect of neutral red on the corrosion inhibition of cold rolled steel in 1.0 M hydrochloric acid

The corrosion inhibition of neutral red on the corrosion of cold rolled steel in 1.0 M hydrochloric acid (HCl) was studied using weight loss method and potentiodynamic polarization method. Results obtained revealed that neutral red is an effective inhibitor. It was found that the adsorption of neutral red could prevent steel from weight loss and the adsorption accorded with the Langmuir adsorption isotherm. Potentiodynamic polarization studies showed that neutral red mainly acted as a mixed-type inhibitor for steel in 1.0 M hydrochloric acid. Thermodynamic parameters such as adsorption heat, adsorption entropy and adsorption free energy were obtained from experimental data of the temperature studies of the inhibition process at four temperatures ranging from 30 to 45 °C. The most suitable range of inhibitor concentration was discussed. The kinetic data such as apparent activation energies and pre-exponential factors at different concentrations of the inhibitor were calculated, the effect of the apparent activation energies and pre-exponential factors on the corrosion rates of cold rolled steel was discussed. The inhibitive action was satisfactorily explained by using both thermodynamic and kinetic models. Synergism between chloride ion and neutral red was proposed. The results obtained from weight loss and potentiodynamic polarization were in good agreement.     

一种海水缓蚀剂缓蚀行为的研究

利用电化学方法和表面分析测试技术，研究了有机膦酸醇酯类缓蚀剂(YKI-05)对于907A钢在天然海水中的缓蚀行为．实验表明，在静态海水中，浓度为300mg／L的YKI-05缓蚀剂能在907A钢表面形成稳定的缓蚀膜层，是一负催化阴极型缓蚀剂，在实验周期内其对907A钢的缓蚀效率较高；并用原子力显微镜(AFM)和俄歇电子能谱(AES)对该缓蚀膜的表面形貌和成分进行分析．     

气相缓蚀剂的研究现状与展望

从缓蚀剂的缓蚀基团和分子结构方面概述了气相缓蚀剂的研究现状，阐述了气相缓蚀剂的有关缓蚀机理。分析了缓蚀效果的影响因素．讨论了气相缓蚀剂的发展方向．     

土壤中SRB及Cl-对1Cr18Ni9Ti不锈钢腐蚀的相互影响

利用交流阻抗测试技术、扫描电镜及表面能谱、失重法、微生物分析等方法 ,研究了在不同Cl-含量的土壤中 ,硫酸盐还原菌对 1Cr18Ni9Ti不锈钢腐蚀的影响规律 .13 6d的试验结果表明 ,不同Cl-含量土壤中SRB菌量在2 3 0 0 0～ 3 5 0 0 0 (个 /克土 )之间 ,Cl-的加入并没有显著影响SRB的生长 ,随着Cl-的加入土壤中SRB的菌量有增大的趋势 ;随着土壤中Cl-含量的增大 ,不锈钢腐蚀电位负偏移 ,而且在接菌土壤中的腐蚀电位比在灭菌土壤中负移幅度更大 ;不锈钢在灭菌土壤中没有发生点蚀现象 ,而在接菌土壤中发生了严重的点蚀 ,最大点蚀深度随着土壤中Cl-含量的增加而增大 ,这说明在土壤中SRB及Cl-的共同作用下 ,增大了不锈钢的点蚀敏感性 .不锈钢在灭菌土壤中的阻抗图谱表现为一个半径很大的容抗弧 ,而在接菌土壤中的阻抗图表现为两个时间常数的双容抗弧     

环己胺类气相缓蚀剂对锌在薄层液膜下的缓蚀机理研究

采用电化学极化曲线和交流阻抗及红外光谱分析法，研究了铬酸二环已胺、磷酸环已胺、亚硝酸二环已胺和碳酸环已胺这4种气相缓蚀剂对金属Zn的缓蚀作用和吸附行为．4种气相缓蚀剂均属于覆盖效应作用机理的阳极型缓蚀剂．铬酸二环已胺、磷酸环已胺和亚硝酸二环已胺抑制了金属Zn在0．5mol/L Na2SO4薄层液膜下的阳极反应而对阴极反应影响很小．缓蚀效果以铬酸二环已胺最好，碳酸环已胺对Zn试件的腐蚀几乎无影响．红外发射吸收光谱的结果也表明铬酸二环已胺在锌试件表面的吸附效果最佳．