典型复合材料加筋壁板落锤/冰雹冲击损伤仿真分析研究

目的研究复合材料层压板落锤和冰雹离散源冲击损伤特性。方法对于落锤和冰雹,分别以刚体模型和弹塑性模型,构建本构模型。对于加筋板,基于Cohesive内聚力界面单元的B-K失效准则,对复合材料层间分层破坏进行数值模拟。通过对多材质冲头、不同冲击能量、不同冲击角度下其响应及损伤扩展特性开展研究,并对比复合材料层压板落锤冲击及冰雹离散源冲击试验数据,对数值计算方法进行对比验证。结果在机体相同部位的落锤、冰雹能量截止值冲击下,落锤低速冲击的损伤响应要大于冰雹离散源冲击。同时,冰雹冲击能量越大,冲击角度越接近于90°,其损伤响应也越大。结论落锤和冰雹离散源冲击仿真方法在损伤响应及扩展的预测与试验结果接近,可以为复合材料冲击损伤引入及抗冲击性能研究提供基础。     

磁性氮掺杂碳材料活化过硫酸盐降解酸性橙7

采用一步水热碳化法制备出微米级磁性氮掺杂碳材料（Magnetic N-doped Carbonaceous Materials,MNC）作为过硫酸盐（Persulfate,PDS）活化剂,以生成的活性氧化物质降解偶氮类染料酸性橙7（Acid Orange 7,AO7）.同时,利用扫描电镜（SEM）、比表面积与孔径测定仪（BET）、振动样品磁强计（VSM）等对MNC进行表征,考察了MNC投加量、PDS浓度、初始p H值和无机阴离子对活化PDS降解AO7的影响,并采用紫外-可见光谱分析、淬灭实验和电子顺磁性共振（Electron Paramagnetic Resonance,EPR）初步探讨了AO7的降解机理.结果表明,MNC呈微米级球状,表面富含含氧基团和氨基等活性点位;饱和磁化强度为12.7 emu·g^-1,能在外加磁场条件下实现固液分离.AO7去除率随MNC投加量、PDS浓度的增加而增加,但初始p H对AO7降解的影响呈相反规律,随p H升高而降低.3种无机阴离子对AO7降解抑制程度大小顺序为HCO₃^->SO     

红土镍矿基材料吸附及有氧降解水体污染物

以红土镍矿为研究对象,考察了原矿（HT）及改性矿（HT-FeNi）去除水体中罗丹明B （RhB）的效果.借助XRD、BET、IR等表征手段,结合吸附动力学和等温吸附模拟研究了HT吸附RhB的过程及机制.结果表明：HT的孔隙结构较为丰富,有良好的RhB吸附性能.当HT添加量为0.2g/L时,RhB去除率为39.03%,吸附量达到93.80mg/g.HT添加量增加,RhB去除效果增强,平衡吸附量减小.HT吸附RhB的过程更符合准二级动力学,包含表面扩散及颗粒内扩散两个步骤.等温吸附模型拟合发现Freundlich能够准确描述HT吸附RhB的过程.1/n<0.5,表明吸附过程较易进行.HT经5次循环实验后,吸附量仍能达到39.67mg/g,表明HT有较好的循环使用性能.HT吸附RhB主要归因于Si-O吸附位点.通过气基还原制备得到改性矿（HT-FeNi）.采用SEM、XRD、BET、XPS等手段对HT-FeNi进行表征分析,并考察了HT-FeNi降解RhB的效果.结果表明：HT-FeNi比表面积小（14.374m²/g）,主要成分为铁镍双金属.HT-FeNi不能通过吸附作用去除RhB,而HT-FeNi/Air/pH=3体系在40min内RhB降解效率为94%.捕获活性氧物种的实验证明,HT-FeNi/Air/pH=3体系去除RhB过程中起主要作用的活性氧物种是羟基自由基（·OH）.在酸性条件下,HT-FeNi通过活化O₂生成·OH,Ni⁰诱导的Fe²⁺/Fe³⁺循环促使HT-FeNi/Air/pH=3体系生成更多的·OH.将HT-FeNi/Air/pH=3体系应用于去除水体中甲基橙（MO）和二硝基氯苯（DNCB）,去除效率分别为47%、78%.     

A survey on heavy metal concentrations in residential neighborhoods: The influence of secondary water supply systems

Water quality deterioration often occurs in secondary water supply systems (SWSSs), and increased heavy metal concentrations can be a serious problem. In this survey, twelve residential neighborhoods were selected to investigate the influence of SWSSs on the seasonal changes in heavy metal concentrations from input water to tank and tap water. The concentrations of nine evaluated heavy metals in all groups of water samples were found to be far below the specified standard levels in China. The concentrations of Fe, Mn, and Zn increased significantly from the input water samples to the tank and tap water samples in spring and summer (p < 0.05), especially for the water samples that had been stagnant for a long time. Negative correlations were found between most of the heavy metals and residual chlorine (Fe, Cu, Zn, and As, r = -0.186 to -0.519, p < 0.05). In particular, a high negative correlation was observed between Fe and residual chlorine (r = -0.489 to -0.519, p < 0.01) in spring and summer. Fe and Mn displayed positive correlations with turbidity (r = 0.672 and 0.328, respectively; p < 0.05). In addition, Cr and As were found to be positively associated with some nutrients (NO₃⁻, TN, and SO₄²⁻; r = 0.420-0.786, p < 0.01). The material of the storage tanks had little influence on the difference in heavy metal concentrations. Overall, this survey illustrated that SWSSs may pose a chronic threat to water quality and could provide useful information for practitioners.     

上海地区大型公共建筑中水工程成本效益分析

针对上海地区大型公共建筑中水回用问题,采用蒙特卡罗模拟技术,对其全生命周期成本效益进行了分析,并讨论了水价对中水工程成本效益的影响.成本计算结果表明生物接触氧化工艺在全生命周期内总成本集中在240.27~276.00万元之间.不同水价方案计算结果表明,在上海现行水价的条件下,生物接触氧化工艺全生命周期效益主要集中在-53.98~-37.54万元之间,50年内不存在投资回收期;当水价为3.8元/t时,生物接触氧化工艺的全生命周期效益主要集中在23.03~51.94万元之间,投资回收期为18~19a;当水价为6.10元/t时,工程效益主要集中在192.47~263.36万元之间,投资回收期为4~5a.因此单从中水工程的成本效益角度来看,上海现行水价偏低,中水回用工程缺乏推广优势,建议适当提高水价或对中水回用工程进行补贴.     

秸秆基建筑保温材料的节能减排分析

计算了秸秆基建筑保温材料的年节能量,并与等量秸秆用作燃料释放的热量进行对比;估算了秸秆基建筑保温材料的CO2减排量;对秸秆基建筑保温材料和发泡聚苯乙烯(EPS)材料生产过程的能耗、CO2排放量和经济性进行对比分析。结果表明,秸秆用于建筑保温在采暖期节能约可高达51 MJ.kg-1.a-1,明显高于其直接用作燃料所释放的热量(7.1~16.7 MJ.kg-1)。若中国北方农村有10万户居民应用特定的秸秆基建筑保温材料,10a的CO2减排量将达到1 600万t以上。在达到相同保温效果情况下,秸秆基材料生产过程中的总能耗和CO2排放量均低于EPS材料,经济性也优于EPS材料。因此,宜在中国北方农村地区大力推广秸秆基建筑保温材料。     

Influence of 1,2,4,5-tetrazine derivatives on growth of bacterial consortium isolated from soil

This article presents the results of laboratory studies of the influence of tetrazine derivatives on the growth kinetic parameters of soil bacteria. 3,6-Dihydrazinotetrazine (DHTz), 3,6- bis(3,5-dimethylpyrazol-1-yl)-dihydro-1,2,4,5-tetrazine (DMPDHT) and N,N′-bis(1,2,4,5-tetrazine-6-(3,5-dimethylpirazylo))hydrazine (BDMPT) were applied. 3,6-Dihydrazinetetrazine had the largest influence on the growth of bacteria, reflected in a significant lengthening of the lag-phase and a decrease in the specific growth rate. Dehydrogenase activity was also determined in bacterial cultures exposed to tetrazine derivatives. Dehydrogenases remained active even at DHTz concentrations of 80 mg · L^?1, which completely inhibited bacterial growth. The compounds studied variously influence the kinetics of growth in the bacterial consortium; at the same time, they undergo biodegradation in soil by autochthonous microflora.     

Fish as an indicator of aquatic environment: Multielemental neutron activation analysis of nutrient and pollutant elements in fish from Indian coastal areas

Fish is the main food in coastal areas and its analysis for toxic metals has been used as an indicator of the pollution status of the aquatic environment. Several different fish species from the three Indian coasts, Visakhapatnam in the east, Mumbai in the west and Mangalore in the south west and also inland freshwater fish from Nagpur in the central region for comparison were analyzed for up to 20 elements (As, Au, Ba, Br, Cl, Co, Cr, Cu, Fe, Hg, K, Mn, Na, P, Rb, Sb, Sc, Se, Sr, Zn) by instrumental neutron activation analysis (INAA). Dried fish samples in powdered form were irradiated with thermal neutrons in a nuclear reactor followed by high resolution gamma ray spectrometry at different intervals. Several Reference Materials (RMs) of biological origin were analyzed for quality assurance and data validation. Elemental contents in different fish species vary in a wide range depending on the species, its size, location, and aquatic environment. Fish from Mangalore showed highest mean contents of Cr (14.8?±?29.9?µg?g^?1), Cu (1005?±?643?µg?g^?1) and Sb (849?±?888?ng?g^?1) whereas those from Mumbai exhibited highest Hg (2066?±?2146?ng?g^?1) and P (20.3?±?4.63?µg?g^?1) but lowest Cu (6.30?±?3.10?µg?g^?1) contents. Fish from all the regions showed significant amounts of nutrient elements such as Na, K, P, Mn, Fe, Se and Zn as well as some pollutant elements (Br, Cr, Sb, Hg). No regularity in variation of elemental contents with the size was observed. Prawn (Panaeus latisulcatus), a popular fish species from four different regions showed wide variation in elemental contents of Cr, Mn, Fe, Zn, Se, P including toxic pollutants, Sb and Hg. An attempt has been made to calculate daily dietary intake (DDI) for some nutrient elements from Indian fish. Elemental data for Cr, Cu, Fe, Hg, Se, and Zn have been compared with those from other fish exporting countries.     

Environmental regulation and competitive performance: new evidence from a sectoral study

Economic theory provides different perspectives on the relationship between environmental regulation and company environmental and competitive performance. A frequently analysed issue refers to the impact of environmental regulation on company performance. Using qualitative data collected within the recently completed Environmental regulation and Market forces Providing Incentives for Resource Efficiency (EMPIRE) project, we analysed the relationship between environmental regulation and company competitiveness, operating in the building and construction (B&C) sector. Empirical evidence from the correlation analysis emphasises that environmental regulation can be an important driver of competitive performance improvements in relevant segments of the European B&C sector.     

Institutional deficiencies and capacity building constraints: the dilemma for environmentally sustainable development in Africa

SUMMARY

The authors question Africa's ability to achieve sustainable development in view of the erosion of its institution building capacity, a problem compounded by the alarming rate of Africa's continuing marginalisation in the world economy. The situation has been provoked by inappropriate domestic policies which have not only compromised Africa's competitiveness, but also made it particularly vulnerable given the increasing globalisation of markets and factors of production. The benefits associated with effective global economic participation transcend direct financial gains and include technology transfers, technical and managerial skills transfers, and other skills transfers associated with the ‘learning and doing’ process. These benefits are instrumental in the development of the economic, administrative, legislative and social institutions that prescribe the organisational and managerial structure of an economy and define its capacity for sustainable growth. In Africa, the absence of such structures has undermined development efforts and created large impoverished populations. But poverty in living standards is not only prevalent, there is also the acute poverty in knowledge and skills which is so damaging to institution building capacity. The socio-economic impact is manifest in dilapidated infrastructure, decaying institutions, the exodus of the professional and managerial cadre, and the almost total disintegration of society. It is within this context that Africa's ability to evolve and effectively manage sustainable development policies is questioned. The study concludes that the continent's capacity to initiate sound environmental and sustainable development policies depends crucially on its ability to develop appropriate and functional institutions.