Effect of F,Cl, Br and I substitution on the BphB enzyme for the degradation of halogenated biphenyls,revealed by quantum and molecular mechanics

Halogenated biphenyls are worldwide persistent pollutants of great environmental concern. In particular, polychlorinated biphenyls and polybrominated biphenyls have been globally used for industrial purposes until they were found highly toxic, mutagenic and carcinogenic to humans. Therefore, ecological strategies to remove halogenated biphenyls, such as enzyme-catalyzed degradation, are needed. Here, we studied the effect of substitution of F, Cl, Br or I at the 4,4′-positions of 2,3-dihydro-2,3-dihydroxybiphenyl-2,3-dehydrogenase (BphB) on the degradation of halogenated biphenyls by quantum and molecular mechanics. Results show that Boltzmann-weighted average degradation barriers of substituted BphB are all lower than the unsubstituted biphenyl, except for chlorinated biphenyl. The roles of residues nearby the active site, e.g., isoleucine89, asparagine115, serine142, asparagine143, proline184, methionine187 and threonine189, were also investigated.

     

Deep learning of grasping detection for a robot used in sorting construction and demolition waste

Journal of Material Cycles and Waste Management - The traditional construction and demolition waste (CDW) treatment process adopts the method of crushing and screening after mixing and combines the...     

元宝山中山土壤形成特点及系统分类

通过对元宝山的实地考察,选取具有代表性的6个山地土壤剖面进行描述及分析,研究了元宝山土壤的形成条件和特点,并按照《中国土壤系统分类:理论·方法·实践》一书要求,根据诊断层及诊断特性,检索了土壤系统分类名称。得出元宝山土壤垂直分布按海拔由低到高依次为:粘化富铝湿润富铁土-强度铝质湿润淋溶土-黄色铝质湿润淋溶土-普通铝质常湿雏形土-石质铝质常湿雏形土。     

合成有机物结构-生物降解性关系的研究

本文综述了合成有机物生物降解性的研究方法.以及定性结构-生物降解性关系(SBR).重点综述了芳香类化合物的结构与生物降解性的关系.研究这一关系有助于有毒化学品生物降解性的预测.     

高温固硫反应中锶化合物的促进作用

本文论述了锶化合物在高温燃烧条件下固硫反应的促进作用，通过Ｘ－射线粉晶衍射及扫描电镜的研究，证明形成含硫酸钙的复合盐的生成是提高固硫率的关键，用该方法制成的工业型煤，在实际锅炉中试烧其固硫率可达７０％，是烟气排烟脱硫的有效方法之一，对净化大气，减少污染有现实意义。     

生物质燃烧释放N2O的测定及其分布

本文报导了实验室规模的生物质封闭燃烧系统及稻草、玉米秸、麦杆燃烧过程中Ｎ２Ｏ排放因子的测定结果，测定结果表明：稻草、麦杆及玉米秸燃烧排气中Ｎ２Ｏ的排放因子分析是８４．４ｇ／ｔ，２７．３ｇ／ｔ，１３２ｇ／ｔ。用Ｎ２Ｏ－Ｎ占生物全氮的百分含量表示，稻草及玉米秸分别上０．５９％，０．８７％。用实验得到的Ｎ２Ｏ的排放因子计算出了生物质燃烧产生Ｎ２Ｏ在全国各省、直辖市、县的年排放量，并作出了全国年排放的分布     

Net emissions of CH4 and CO2 in Alaska: implications for the region's greenhouse gas budget.

We used a biogeochemistry model, the Terrestrial Ecosystem Model (TEM), to study the net methane (CH4) fluxes between Alaskan ecosystems and the atmosphere. We estimated that the current net emissions of CH4 (emissions minus consumption) from Alaskan soils are approximately 3 Tg CH4/yr. Wet tundra ecosystems are responsible for 75% of the region's net emissions, while dry tundra and upland boreal forests are responsible for 50% and 45% of total consumption over the region, respectively. In response to climate change over the 21st century, our simulations indicated that CH4 emissions from wet soils would be enhanced more than consumption by dry soils of tundra and boreal forests. As a consequence, we projected that net CH4 emissions will almost double by the end of the century in response to high-latitude warming and associated climate changes. When we placed these CH4 emissions in the context of the projected carbon budget (carbon dioxide [CO2] and CH4) for Alaska at the end of the 21st century, we estimated that Alaska will be a net source of greenhouse gases to the atmosphere of 69 Tg CO2 equivalents/yr, that is, a balance between net methane emissions of 131 Tg CO2 equivalents/yr and carbon sequestration of 17 Tg C/yr (62 Tg CO2 equivalents/yr).     

福建丰产荔枝园土壤微量元素含量的研究

与我国红壤平均水平相比，福建丰产荔枝园土壤有效态锌、钼及水溶态硼含量较高，而活性锰及有效铜含量较低；土壤全锌、锰、钢量亦较低。在土壤ｐＨ４．５４—８．７６时，ｐＨ值与有效态钼含量呈较显著正相关，而与代换态锰、水溶态硼、有效态铁含量呈显著或极显著负相关。本文初步提出福建荔枝园土壤微量元素含量的适宜指标，可供土壤营养诊断及平衡施肥之参考。     

生物降解途径的理论预测与QSBR研究

本文把有机污染生生物降解途径理论预测的结果与ＱＳＢＲ模型中化合物选择相结合，所遵循相同理论生物降解途径作为化合物分组的原则，以分子连接性接数和ＥＨＯＭＯ作为结构参数与电性参数，采用逐步回归的方法建立了新的ＱＳＢＲ模型，新模型的预测民实验结果能较好地吻合。     

湖泊水环境保护功能区划分

在浓度场基础上，利用总磷、总氮和ＣＯＤ三项指标的综合指数法，结合管理部门提供的资料，划分了滇不不环境保护功能区，给出了划分指标值及功能区划分图。