The Shape Memory Properties of Biodegradable Chitosan/Poly(l-lactide) Composites

The shape memory behavior of PLLA (poly(l-lactide)) and chitosan/PLLA composites was studied. PLLA and chitosan were compounded to fabricate novel materials which may have biodegradability and biocompatibility. Chitosan does not significantly affect the glass and melting transition temperature of the PLLA. Both the pure PLLA and chitosan/PLLA composites showed shape memory effect arising from the viscoelastic properties of PLLA comprised of semi crystalline structures. The shape recovery ratio of the chitosan/PLLA composites decreased significantly with increasing chitosan contents due to the incompatibility between PLLA and chitosan. Phase separation structures of the composites were observed by using atomic force microscopy. To obtain good shape memory effect, the chitosan content should be below 15 wt%.     

半密闭排烟罩在15 t电炉烟气捕集上的应用

针对某厂15 t电炉的特点,提出了一种半密闭排烟罩烟尘捕集方案,通过运行和改进,验证了半密闭排烟罩在15 t电炉除尘系统成功的应用,为同类电炉的烟气捕集提供了示范和借鉴.     

关于陕西省城市防洪问题的思考

在系统总结陕西省城市改革发展的现状以及防洪减灾存在问题的基础上,指出了洪涝灾害造成的损失,重点说明城市防洪在经济建设中的重要性;针对省情提出了新时期城市防洪建设的思路、防洪策略和奋斗目标.山洪灾害是威胁中小城市安全的主要问题,要建立多元化的投资机制,鼓励和促进城市防洪建设健康发展.     

基于响应绩效的重大事故应急预案编制技术研究

重大事故应急预案是保证企业应急救援工作快速、高效地开展的关键。应急预案的响应绩效是预案对于预防事故发生和控制事故恶化的实际效果,基于响应绩效的重大事故应急预案编制方法就是将绩效作为核心的思想融入编制的各环节。围绕预案的编制原则、文件要素和编制流程对方法进行介绍,并进一步详细阐述了基于响应绩效的预案编制要点,从而保证预案的完整性、逻辑性、可操作性和指导性四方面的响应绩效要求。     

Racemic,R-, and S-tebuconazole altered chitinase and chitobiase activity of Daphnia magna

Tebuconazole is a chiral trizole fungicide and widely used in many crops for controlling disease. Tebuconazole is potential toxic to some aquatic organisms but relative information of its isomers is scarce. To detect the endocrine disrupting effects and difference of rac-, R-, and S-tebuconazole, the chitinase activity in Daphnia magna and chitobiase activity in each test medium were used as biomonitors after a 14-day exposure. Results showed that chitinase activity was significantly reduced by rac-, R-, and S-tebuconazole. The chitobiase activity in the test medium was reduced by rac- and R-tebuconazole before day 10, and only one peak was observed at day 10 or day 12 compared with two obvious peaks in the control group (days 6 and 12). S-tebuconazole delayed and reduced the reproduction of D. magna, but did not delay the first chitobiase activity peak, whereas the second peak could not be characterized as the exposure concentration and time increased. Compared with chitinase activity, chitobiase activity can still be used as a rudimentary model for identifying molt-interfering xenobiotics, and further studies should focus on the analysis of correlations between these parameters.     

Soil surface Hg emission flux in coalfield in Wuda,Inner Mongolia,China

Hg emission flux from various land covers, such as forests, wetlands, and urban areas, have been investigated. China has the largest area of coalfield in the world, but data of Hg flux of coalfields, especially, those with coal fires, are seriously limited. In this study, Hg fluxes of a coalfield were measured using the dynamic flux chamber (DFC) method, coupled with a Lumex multifunctional Hg analyzer RA-915+ (Lumex Ltd., Russia). The results show that the Hg flux in Wuda coalfield ranged from 4 to 318 ng m^?2 h^?1, and the average value for different areas varied, e.g., coal-fire area 99 and 177 ng m^?2 h^?1; no coal-fire area 19 and 32 ng m^?2 h^?1; and backfilling area 53 ng m^?2 h^?1. Hg continued to be emitted from an underground coal seam, even if there were no phenomena, such as vents, cracks, and smog, of coal fire on the soil surface. This phenomenon occurred in all area types, i.e., coal-fire area, no coal-fire area, and backfilling area, which is universal in Wuda coalfield. Considering that many coalfields in northern China are similar to Wuda coalfield, they may be large sources of atmospheric Hg. The correlations of Hg emission flux with influence factors, such as sunlight intensity, soil surface temperature, and atmospheric Hg content, were also investigated for Wuda coalfield.

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道路交通的社会影响:当地居民的意见和优先考虑顺序

道路交通的社会影响评价经常基于客观指标或专家判断,没有征求被影响社区的意见。此文以一个拟建核电站对乡村地区的影响为例,探讨了当地居民对施工交通造成的影响和可能的减缓措施的意见和优先考虑。研究包括一个定性分析和一个优先考虑调查。使用了计量经济学模型来权衡不同影响和减缓措施的相对优先顺序。影响最大的因素是噪声、振动和增加的机动车交通频次。最受欢迎的减缓措施是夜间限制载重车辆、停车限制和对行人及骑自行车人员的安全保护。优先顺序受被调查人的居住地点、性别、就业状况和家庭组成影响,区别很大。研究指出,现有评价框架里有些信息是趋于合并的,应区分某些活动(如散步和开车)的主动减少和这些活动的被动停止。     

The use of ultrasound-assisted anaerobic compost tea washing to remove poly-chlorinated dibenzo-p-dioxins (PCDDs), dibenzo-furans (PCDFs) from highly contaminated field soils

The remediation of dioxin-contaminated soil of a specific coastal area previously employed for the manufacture of pentachlorophenol (PCP) in southern Taiwan’s Tainan City has attracted much attention of researchers there. This work addresses the possibility of providing an effective and environmentally friendly option for removing PCDD/Fs from soil in that field. Soil screening/sieving was first conducted to assess particle distribution. Fine sand was observed to be the major component of the soil, accounting for more than 60% of the total mass. A combination of ultrasonification and mechanical double-blade agitation was used to facilitate the washing of the soil using the biosurfactant anaerobic compost tea. More than 85 and 95% of total removal efficiencies were achieved for moderately and highly contaminated soils after 6 and 10 washing cycles, respectively, under ambient temperature, a soil/liquid ratio 1:2.5, 700 rpm, and over a relatively short duration. These results were achieved through the collision and penetration effects of this combined treatment as well as PCDD/F partitioning between the particles and anaerobic compost tea. This study represents the first to report the use of anaerobic compost tea solvent to wash soil highly contaminated by dioxin. It was concluded that anaerobic compost tea, rich in non-toxic bio-surfactants (e.g., alcohols, humic acids), can be used to improve bioavailability and bioactivity of the soil making bio-attenuation and full remediation more efficient.     

De novo formation of dioxins from milled model fly ash

Environmental Science and Pollution Research - Municipal solid waste incineration (MSWI) fly ash has been classified as hazardous waste and needs treatment in an environmentally safe manner....