Rule of formation of aluminum electroplating layer on Q235 steel

Aluminum electroplating layer on Q235 steel in AlCl₃-NaCl-KCl molten salt was obtained, and the rule of its nucleation and growth were investigated. The results showed that aluminum electroplating layer formed through nucleating and growing of aluminum particles, and thickened by delaminating growth pattern. At low current density, the morphology of aluminum particles took on flake-like, while at high current density they changed to spherical. The thickness of plating layer increases with increasing current density and electroplating time. The relationship between the plating thickness (δ) and electroplating time (t) or current density (i) can be expressed as δ = 0.28f¹³⁷, and δ = 1.1i^1-39.     

In situ adsorption-catalysis system for the removal of o-xylene over an activated carbon supported Pd catalyst

An activated carbon (AC) supported Pd catalyst was used to develop a highly efficient in situ adsorption-catalysis system for the removal of low concentrations of o-xylene. In this study, three kinds of Pd/AC catalysts were prepared and tested to investigate the synergistic efficiency between adsorption and catalysis for o-xylene removal. The Pd/AC catalyst was first used as an adsorbent to concentrate dilute o-xylene at low temperature. After saturated adsorption, the adsorbed o-xylene was oxidized to CO2 and H2O by raising the temperature of the catalyst bed. The results showed that more than 99% of the adsorbed o-xylene was completely oxidized to CO2 over a 5% Pd/AC catalyst at 140℃. Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), temperature-programmed desorption (TPD), and temperature-programmed oxidation (TPO) were applied to investigate the physical properties of o-xylene adsorption-desorption and the in situ adsorption-catalysis activity of the AC support and Pd/AC catalyst. A synergistic relationship between the AC support and the active Pd species for the removal of low concentrations of o-xylene was established.     

三江源地区高寒灌丛生物量空间分布格局

生物量在地上与地下的分配是植物生长策略的反映,对于研究生态系统碳储量和碳循环有着重要的意义.采用收获法对灌丛群落与物种的地上、地下生物量进行测定,并分析温度和降雨量等气候因素对灌丛群落地上和地下生物量及构成的影响.同时选择三江源地区4种典型的灌丛植物,百里香杜鹃(Rhododendron thymifolium Maxim.)、山生柳(Salix oritrepha Schneid.)、金露梅(Potentilla fruticosa Linn.)和鲜卑花(Sibiraea laevigata(Linn)Maxim.),进行地上、地下生物量研究.结果显示:三江源灌丛群落的地上生物量介于209.88-3 632.34 g/m~2之间,地下生物量介于178.81-2 262.03 g/m~2之间,根冠比(R/S)介于0.40-2.57之间;物种的地上生物量介于1.83-3 632.34 g/m~2之间,地下生物量介于1.22-2 262.03 g/m~2之间,根冠比(R/S)介于0.23-2.63之间.灌丛群落与物种的地上、地下生物量拟合的斜率分别为0.66和0.96,前者与1存在显著性差别,后者与1没有显著性差别.这说明灌丛群落与物种的地上、地下生物量分配分别呈异速分配关系与等速分配关系,百里香杜鹃和鲜卑花的地上与地下生物量分配属于等速分配关系,金露梅和山生柳属于异速分配关系.本研究表明三江源高寒灌丛生物量大小与年均温度的变化关系密切;年均温度与年均降雨量都不能明显地改变根冠比(R/S).     

温度对淀粉酶强化污泥为燃料微生物燃料电池的影响

采用单室无膜悬浮阴极微生物燃料电池(MFC),对比分析了温度变化对淀粉酶强化剩余污泥为燃料的MFC(ESMFC)产电特性和污泥减量化效果的影响.研究表明,在40℃时ESMFC最大功率密度相对于参照组(投加等量失活酶系统)功率密度输出增加最大,为94%;此时CE也最大,为9.2%。这主要是由于在此温度下淀粉酶对系统的促进作用更明显。在45℃时,ESMFC系统中污泥减量化效果最好.当运行温度为45℃时,ESMFC中TCOD去除率为87.2%,投加等量失活淀粉酶的ESMFC中TCOD去除率为55.7%;ESMFC中VSS/TSS从原泥中的67.34%下降到28.07%,对照组则下降到45.61%。此研究对投加淀粉酶的ESMFC实际应用具有一定指导意义。     

Catalytic performance of Ag/Al2O3-C2H5OH-Cu/Al2O3 system for the removal of NOx from diesel engine exhaust

The selective catalytic reduction (SCR) of NOx by C(2)H(5)OH was studied in excess oxygen over Ag/Al(2)O(3) catalysts with different Ag loadings at lab conditions. The 4% Ag/Al(2)O(3) has the highest activity for the C(2)H(5)OH-SCR of NOx with a drawback of simultaneously producing CO and unburned THC in effluent gases. An oxidation catalyst 10% Cu/Al(2)O(3) was directly placed after the Ag/Al(2)O(3) to remove CO and unburned THC. Washcoated honeycomb catalysts were prepared based on the 4% Ag/Al(2)O(3) and 10% Cu/Al(2)O(3) powders and tested for the C(2)H(5)OH-SCR of NOx on a diesel engine at the practical operating conditions. Compared with the Ag/Al(2)O(3) powder, the Ag/Al(2)O(3) washcoated honeycomb catalyst (SCR catalyst) has a similar activity for NOx reduction by C(2)H(5)OH and the drawback of increasing the CO and unburned THC emissions. Using the SCR+Oxi composite catalyst with the optimization of C(2)H(5)OH addition, the diesel engine completely meets EURO III emission standards.     

肟菌酯对环境生物急性毒性及安全性评价

本试验通过研究肟菌酯对10种环境生物急性毒性效应,以期评价其对环境生物的毒性风险。结果表明,肟菌酯对日本鹌鹑(Coturnix coturnix japonica)的经口毒性7 d-LD50和短期饲喂毒性8 d-LC50分别大于2.00×103mg a.i.·kg-1bw和5.00×103mg a.i.·kg-1饲料,意大利蜜蜂(Apis mellifera L.)接触与经口毒性48 h-LD50分别为大于100μg a.i.·蜂-1和95.3μg a.i.·蜂-1,家蚕(Bombyx mori)96 h-LC50为1.61×103mg a.i.·L-1,蚯蚓(Eisenia foetida)14 d-LC50大于100 mg a.i.·kg-1干土,赤眼蜂(Trichogramma japonicum)24 h-LR50为0.337μg a.i.·cm-2,羊角月牙藻(Pseudokirchneriella subcapitata)72 h-EC50为5.80×10-3mg a.i.·L-1,大型溞(Daphnia magna Straus)48 h-EC50为1.72×10-2mg a.i.·L-1,斑马鱼(Brachydanio rerio)96 h-LC50为5.40×10-2mg a.i.·L-1,非洲爪蟾(Xenopus laevis)蝌蚪96 h-LC50为8.95×10-2mg a.i.·L-1,土壤微生物28 d硝酸盐转化速率差异小于25%。因此,根据《化学农药环境安全评价试验准则》毒性等级划分标准,肟菌酯对鸟、蜜蜂、家蚕、蚯蚓等陆生生物为低毒,对水生生物的绿藻、大型溞、斑马鱼、非洲爪蟾蝌蚪均为高毒或剧毒,而对天敌赤眼蜂属高风险,故在田间使用过程中应采取措施降低其对水生生物以及天敌昆虫赤眼蜂急性毒性风险,以免造成危害。     

新型鼓风炉铁泥基混凝剂的制备及应用研究

研究在鼓风炉铁泥中加入适量的粉煤灰和助溶剂HS,在90℃温度下搅拌浸取2.5h后,制得集物理吸附和化学混凝为一体的混凝剂.这种混凝剂与PSA絮凝剂配合用于制革和纺织印染废水的处理,与传统混凝剂相比,COD和色度的去除率均提高30%左右.其显著特点是混凝沉降速度快,污泥体积小,处理废水费用低,并结合显微照片探讨了混凝剂对废水的混凝沉降机理.     

Prevalence of GII.4 Sydney Norovirus Strains and Associated Factors of Acute Gastroenteritis in Children: 2019/2020 Season in Guangzhou,China

Food and Environmental Virology - Norovirus, the leading cause of non-bacterial acute gastroenteritis (AGE) worldwide, is constantly mutating. Continuous monitoring of the evolution of epidemic...     

无锡市工业废水污染变迁及其解释

运用EKC分析和分解分析方法,拟合了1991年~2005年无锡工业废水污染随经济发展的演变轨迹,并实证解释了轨迹背后的经济原因。EKC分析结果表明,无锡市工业废水排放量的演变轨迹呈U型,但是市区、江阴和宜兴拥有不同的转折点（7 401元,10 059元,4 718元）。分解分析结果表明,工业废水污染排放强度减轻是形成U型轨迹左半部分的主要原因,而经济规模的大幅度扩张则是形成U型轨迹右半部分的主要原因。     

Complete catalytic oxidation of o-xylene over CeO2 nanocubes

The activities of CeO2 nanocubes calcined at di erent temperatures were tested for catalytic oxidation of o-xylene. Using CeO2 nanocubes as catalysts, complete catalytic oxidation of o-xylene was achieved below 210°C. The CeO2 nanomaterials were characterized by means of BET, X-ray di raction (XRD), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). From the TEM images, all CeO2 nanocubes displayed cubic morphology irrespective of calcination temperature. The HRTEM images revealed that these nanocubes were enclosed by reactive f001g planes, which may contribute to the intrinsically catalytic property of o-xylene oxidation. The higher activity of CeO2 nanocubes calcined at 550°C than those calcined at above 550°C was attributed to their smaller crystallite size and larger surface area. The influences of reaction conditions were also studied, which found that a higher reaction temperature was necessary for complete catalytic oxidation of o-xylene at higher weight hourly space velocity (WHSV) and o-xylene concentration.