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...     

纳米零价铜活化分子氧降解水中恩诺沙星

采用纳米零价铜(nanoscale zero-valent copper,nZVC)活化分子氧对水中恩诺沙星(enrofloxacin,ENR)的去除进行了系统研究.通过表征可以发现,纳米铜粉比表面积高于微米级铜粉,无孔隙结构,表面粗糙且容易团聚.纳米级ZVC活化分子氧的性能明显优于微米级ZVC,这主要归因于其较大的比表面积,更容易被腐蚀.通过探究活化机制可以发现,活化分子氧产生的H_2O_2和表面腐蚀产生的Cu+构成了新型类Fenton体系,持续释放的羟基自由基是造成水中ENR高效去除的主导活性物种;同时,反应过程中产生的超氧自由基能够促进Cu2+还原成Cu+,从而加速ENR的去除过程.反应条件对nZVC活化分子氧降解ENR有一定的影响,较高的nZVC投加量、较低ENR浓度、较高的反应温度以及强酸性条件均有利于ENR的去除.     

硫毒化NH3-SCR脱硝催化剂再生方式的构建及机制研究

以CeTi复合氧化物负载NH₄HSO₄(模拟SO₂毒化催化剂)为研究对象,并向其中掺杂Mo作为改性组分,研究了硫毒化催化剂的再生过程与机制.与热再生相比,冷等离子体在再生毒化后催化剂的过程中显现出独特的优势.通过对再生后催化剂的物理化学性质表征及优化再生气氛,确认了冷等离子再生催化剂的优点：不仅能够保持催化剂物相结构的稳定,还可促进催化剂表面NH₄HSO₄的低温分解和硫物种的脱附.虽然冷等离子体再生后的催化剂NH₃-SCR反应活性下降,但可通过纯O₂气氛中焙烧的方式,实现对催化剂物理化学性质的重构和催化活性的再生.通过此研究,初步建立了催化剂“毒化-再生-重构”的基本构效关系,为硫中毒NH₃-SCR脱硝催化剂的再生提供了可行性方案.     

Formic acid fractionation towards highly efficient cellulose-derived PdAg bimetallic catalyst for H2 evolution

The present work, in which cellulose isolated from formic acid fractionation (FAC) is decorated with polyetherimide (PEI) to attain highly efficient cellulose-derived PdAgbimetallic catalyst (PdAg-PEI-FAC), has been investigated, and the catalyst properties are characterized by XRD, XPS, BET, ICP-AES and HAADF-STEM. The as-obtained Pd3.75Ag3.75-PEI-FAC exhibits excellent catalytic performance for H2 evo-lution from a sodium formate-free formic acid (FA) aqueous medium at ambient temperature and the turnover frequency (TOF) reaches a high value of 2875 h-1, which is superior to most of the previously reported Pd-based heterogeneous catalysts supported on a carbon matrix in the literature. The remarkable catalytic activities of PdAg-PEI-FAC result from high dispersion Pd and synergistic effects between the PdAg bimetallic system. Furthermore, the amide (-NH) group in PEI coated on cellulose acting as a proton scavenger efficiently improves the catalytic property of catalyst. In addition, the critical factors affecting H2 release, such as FA concentration, reaction temperature, PdAg compositions and support matrix type, are also evaluated. Based on the experimental results, the probable three-step mechanism of H2 evolution from FA over Pd3.75Ag3.75-PEI-FAC is proposed. In the end, the activation energy (Ea) of Pd3.75Ag3.75-PEI-FAC catalyst is calculated to 53.97 kJ mol-1, and this catalyst shows unique robustness and satisfactory re-usability with no loss of catalytic activity after five recycles. The findings in this work provide a novel routine from lignocellulose fractionation towards cellulose-derived catalyst for H2 evolution.     

复合惰气在采空区遗煤中竞争吸附的分子动力学模拟研究*

为明确作用于采空区的复合惰气的竞争吸附,进行不同温度、压力及组分下烟煤对N2、O2、CO2多元气体竞争吸附分子的模拟研究。研究结果表明:当注入压力达到3 MPa后,竞争吸附效果不再明显,为高压注入提供一定的理论基础;随着CO2分压的增大,O2吸附量降低速度逐渐平缓,初步确定最佳注入配比范围为2∶1至3∶1,为进一步结合实际工程中成本等因素确定最佳注入配比提供参考;等量吸附热受吸附条件的影响较小,仅与吸附质本身有关;随着CO2分压的增大,范德华能升高56.9%,分子内能升高78.7%,静电能升高67.2%,CO2对整个系统内的吸附作用强度及吸附量有着较大的影响;随着CO2分压增大,N2竞争吸附能力逐渐弱于O2,竞争吸附能力大小顺序为CO2>O2>N2。     

压裂返排液的处理及回用

制备了沸石负载纳米TiO_2催化剂和蒙脱土负载纳米零价铁吸附剂,结合传统处理技术,构建了"絮凝—预氧化(Fenton氧化)—沸石负载纳米TiO_2催化臭氧氧化—蒙脱土载负纳米零价铁吸附"组合工艺,处理压裂返排液,考察了影响COD去除效果的因素。实验结果表明:在催化剂投加量1.0 g/L、臭氧通入时间5 min、吸附剂投加量5.0 g/L、吸附时间4 h的最佳条件下,COD从原水的4 032.60 mg/L降至37.03 mg/L,处理后出水各项指标均达到GB 8978—1996《污水综合排放标准》中的一级标准;80℃下,出水回用配制的压裂液黏度为4.4 mPa·s,高于自来水配制和压裂返排液配制的压裂液,耐温性有一定提升。     

新型固相微萃取头测定胶粘剂中苯及其同系物

结合分子印迹技术与溶胶-凝胶技术,自制新型联苯分子印迹溶胶-凝胶聚合物涂层固相微萃取头,结合顶空固相微萃取-气相色谱法(HS-SPME-GC),测定水溶液中的苯及其同系物。结果表明,该方法精密度良好(RSD<5%),线性范围超过2个数量级,最低检出限达到10ng/mL。运用该法对市售胶粘剂中苯及其同系物进行检测,结果令人满意。     

芳烃石油树脂生产的环境保护

乙烯装置的副产品在综合利用中存在着严重的环境污染问题。中原油田采取了一些措施。用催化剂对生产尾气进行吸收,将有毒的氟化物转化为钙盐用于磷肥生产;将石油树脂聚合液中BF3脱除,防止对大气、水进行污染;用冷却回收工艺对减压蒸馏放空的芳烃气体进行处理。通过上述治理大大改善了企业的环境,有效地防止了环境污染。     

Molecular prenatal diagnosis of Smith–Lemli–Opitz syndrome is reliable and efficient

Smith–Lemli–Opitz (RSH) syndrome (SLOS, OMIM 270400) is a relatively common, autosomal recessive disorder of cholesterol biosynthesis with a broad spectrum of phenotypic abnormalities caused by mutations of the 7-dehydrocholesterol reductase gene (DHCR7) on chromosome 11. Prenatal diagnosis can be established by detection of elevated 7-dehydrocholesterol or of SLOS-causing mutations in the DHCR7 gene. We report here our experience with molecular prenatal diagnosis of SLOS. Mutation analysis of the DHCR7 gene was performed in chorionic villus samples of 13 pregnancies of couples with a family history of SLOS and known SLOS genotypes. This approach is accurate and reliable. If facilities for biochemical analysis are not available, or in cases with ambiguous biochemical patterns, molecular prenatal diagnosis is an attractive, alternative option. Copyright © 2002 John Wiley & Sons, Ltd.     

聚合硫酸铁絮凝剂的物化性质研究

本文通过对直接氧化法聚合硫酸铁(PFS)的热力学研究,首次报道了PFS的一些物化数据:热容、积分溶解热和反应热效应,并根据稀溶液的依数性原理测定了PFS的平均分子量。