Effect of Ni–V loading on the performance of hollow anatase TiO2 in the catalytic combustion of dichloromethane

A catalyst based on mixed V-Ni oxides supported on TiO_2(Ni-V/TiO_2)was obtained using the sol-gel method.Its catalytic performance relative to dichloromethane(DCM)degradation was investigated.Characterization and analysis were conducted using transmission electron microscopy,H2 temperature-programmed reduction,pyridine-Fourier transform infrared spectroscopy(FTIR)characterization,and X-ray diffraction.Results showed that the original hollow anatase structure of pure Ti02 was well-maintained after Ni-V loading.The loading of NiO-VOx not only significantly improved the stability of pure Ti02 but also inhibited the formation of the by-product monochloromethane(MCM).Among the series of Ni-V/TiO_2 catalysts,4%Ni-V/TiO_2 possessed the highest catalytic activity,with 90%DCM conversion at only 203℃.No by-products and no significant changes in the catalytic activity were observed during combustion of DCM after 100 hr of a continuous stability test.Furthermore,thermogravimetric analysis(O_2-TG)and energy dispersive spectrometer(EDS)characterization of the used 4%Ni-V/TiO_2 catalyst revealed that no coke deposition or chlorine species could be detected on the catalyst surface.     

苏州河生态恢复初期自净能力的综合评估方法

利用苏州河水的化学及生物学参数,以及水样对几种添加化学品的降解延滞期及降解率,综合评估了水体自净能力,并探讨了苏州河生态恢复初期自净能力的评估方法。对比2008年上、下游水样对醋酸钠、苯酚、苯胺、二甘醇、乙二醇、三聚乙醛等6种化学品的降解情况,比较分析了2006年及2008年两年度间苏州河自净能力的变化。相对2006年而言,2008年水体的氧化还原电位急剧下降,上、下游水体对化学品降解能力整体减弱,三聚乙醛降解能力的减弱尤为明显,降解率从2006年的77.82%和88.73%降至2008年的35.83%和65.86%。在外部有机物输入量无明显变化的情况下,上游的好氧异养菌数由2006年的4.7×104CFU/mL降为2008年的2.2×103CFU/mL。2008年苏州河上游水体对化学品(二甘醇除外)降解能力较下游水体更弱,且延滞期长。与2006年相比,2008年苏州河水体的自净能力整体减弱,上游水体自净能力的损失更为明显。     

Chemical characterization of size-resolved aerosols in four seasons and hazy days in the megacity Beijing of China

Size-resolved aerosol samples were collected by MOUDI in four seasons in 2007 in Beijing. The PM₁₀ and PM_1.8 mass concentrations were 166.0 ± 120.5 and 91.6 ± 69.7 μg/m³, respectively, throughout the measurement, with seasonal variation: nearly two times higher in autumn than in summer and spring. Serious fine particle pollution occurred in winter with the PM_1.8/PM₁₀ ratio of 0.63, which was higher than other seasons. The size distribution of PM showed obvious seasonal and diurnal variation, with a smaller fine mode peak in spring and in the daytime. OM (organic matter = 1.6 × OC (organic carbon)) and SIA (secondary inorganic aerosol) were major components of fine particles, while OM, SIA and Ca^2 + were major components in coarse particles. Moreover, secondary components, mainly SOA (secondary organic aerosol) and SIA, accounted for 46%–96% of each size bin in fine particles, which meant that secondary pollution existed all year. Sulfates and nitrates, primarily in the form of (NH₄)₂SO₄, NH₄NO₃, CaSO₄, Na₂SO₄ and K₂SO₄, calculated by the model ISORROPIA II, were major components of the solid phase in fine particles. The PM concentration and size distribution were similar in the four seasons on non-haze days, while large differences occurred on haze days, which indicated seasonal variation of PM concentration and size distribution were dominated by haze days. The SIA concentrations and fractions of nearly all size bins were higher on haze days than on non-haze days, which was attributed to heterogeneous aqueous reactions on haze days in the four seasons.     

Carbon and nitrogen composition and stable isotope as potential indicators of source and fate of organic matter in the salt marsh of the Changjiang Estuary, China

Elemental (TOC, TN, C/N) and stable carbon and nitrogen isotopic (delta(13)C, delta(15)N) compositions were measured for surface sediments, three sediment vibrocores, plants, and suspended particulate matter (SPM) collected from salt marsh of the Changjiang Estuary. The purpose of this study is to characterize the sources of organic matter in sediments and to further elucidate the factors influencing the isotope signature in the salt marsh. Our results indicate that organic matter preserved in the sediments is predominantly controlled by the particulate organic matter in the Changjiang Estuary. The in situ contribution of marsh plants carbon to sediment organic matter is clearest in the high marsh, where the low delta(13)C of the plants (-28.1 per thousand) is reflected by a sediment delta(13)C (-24.7 per thousand) lower than values found for the low marsh and bare flat sediments (-23.4 per thousand and -23.0 per thousand, respectively). The effect of grain size on the spatial difference of isotope composition in the marsh sediments is insignificant, based on the observation that similar isotope values are found in different size particles, both for delta(13)C and delta(15)N. Nutrient utilization by plant assimilation, however, shows great impact on the surface sediment delta(15)N composition, due to the isotope fractionation. With extensive plant coverage and the consequent low surface water nitrate concentration, delta(15)N values of the high marsh surface sediments show (15)N enrichment.     

A sensitive and reliable quantification method for Bisphenol A based on modified competitive ELISA method

Bisphenol A (BPA), generally known as bisphenols, has been identified as a potential estrogenic substance. BPA must be conjugated to carrier protein and BSA was commonly used. 4,4-Bis(4-hydroxyphenyl) valeric acid (BHPVA) has a bisphenolic structure and a long carbon chain with a reactive carboxyl group on the end. In this study, BHPVA-BSA was used to produce polyclonal antibody against bisphenolic structure, and a modified competitive ELISA method for quantification of BPA was developed. This system was based on BHPVA-BSA for polyclonal antibody production against bisphenolic structure, and BHPVA-HRP for determination of BPA substituting detection antibody in competitive reaction. Recovery was assessed at 10 different concentrations (2-1000 ng/ml) of BHPVA, and the recovery range was from 96.3% to 107.2%. The variation was from 6.2% to 9.8% for intra assay and from 10.1% to 12.6% for inter assay. The quadratic was used to establish the curve regression. The range was found to be between 2 and 1000 ng/ml. This modified competitive ELISA method has proven to be a very useful tool for quantification of BPA without the unexpected interaction of BSA and anti-BSA polyclonal antibody.     

pH对氢自养型反硝化菌反硝化性能的影响

采用模拟硝酸盐污染地下水(简称模拟水)驯化培养氢自养型反硝化菌,建立了定量分析氢自养型反硝化菌生物量的方法,研究了pH对氢自养型反硝化菌反硝化性能的影响。结果表明,每单位OD600相当于水样中氢自养型反硝化菌的生物量为491.75mg/L。当初始pH在6.7以下或9.2以上时,氢自养型反硝化菌生物活性会受到抑制,而初始pH为7.2、7.7、8.2和8.7时,反硝化进行12h后模拟水中的总氮去除率分别为99.7%、99.6%、96.6%和83.5%。经过12h的反硝化模拟水的pH增加0.1～0.9,硬度降低10.01～48.05mg/L;初始pH为6.7～8.7的模拟水在反硝化进行12h后生物量增加5.68～6.03mg/L,初始pH为7.7的模拟水反硝化速率最高,达0.041mg/h。     

甘肃省自然灾害与综合防御对策

本文讨论了甘肃省主要自然灾害对社会造成的危害，并提出了减轻自然灾害的综合防御对策。     

四边形网格生成的基区拼合法

提出了一种新的四边形有限元网格的生成方法基区拼合法。在基区划分的基础上 ,先进行基区内部的网格生成 ,然后把各个基区缝合起来 ,形成完整的有限元网格。该方法简单且行之有效 ,特别适用于解决轮廓形状不太复杂的二维问题。     

基于1983—2019年文献计量对多环芳烃降解基因研究及进展的剖析

为全面、系统地了解1983—2019年37年间多环芳烃降解基因研究领域的发文趋势、主要的研究国家和机构、研究热点及其变化趋势等,本文以Web of Science核心数据库为数据源,利用文献计量学方法对此进行分析,结果表明：①全球对多环芳烃降解基因研究的重视程度越来越高,而且分子生物学的技术手段在该研究领域中得到了广泛应用,发文主要集中于微生物学、生物技术与应用微生物学、环境科学等3个学科;②美国、中国、日本、德国等国家发文较多,相比其他国家,中国需进一步加强与其他研究机构间的交流合作;③1983—1995年该研究领域侧重于高效降解菌的筛选及其特性研究,1996—2019年则大规模展开了对其降解途径多样性的研究,近年来更侧重于运用多种生物信息技术来研究多环芳烃的代谢机理及构建生物降解调节机制;④目前已报道了nah、phd、nag、phn、nar和nid等6类多环芳烃降解菌的功能基因,为污染场地的生物修复提供了相应支撑.     

车载储氢瓶泄漏及车库内通风方式研究

为研究车库内燃料电池汽车氢气意外泄漏后的浓度分布情况,采用ANSYS软件,通过分析可燃性气体体积、水平方向和垂直方向氢气的扩散分布、不同泄漏位置氢气的扩散情况,研究6种不同通风方式对氢气意外泄漏扩散分布的影响,针对车库内氢气泄漏的特性,在通风方式上引入侧墙底部送风和侧墙顶部送风方式。研究结果表明：底部送风能显著加快氢气的扩散和排出。垂直高度上氢气浓度分布不均,侧墙顶部送风能使顶部堆积的氢气向下扩散,降低最大气体浓度;在墙角泄漏会由于墙壁的影响导致氢气堆积,对墙角局部通风尤为重要。研究结果可为氢燃料电池汽车专用车库的通风设计提供重要参考。