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131.
论文以北京市沙河流域为研究区,选择1999-2007年不同季节典型日的TM/ETM+数据,辅助相关气象观测资料,以地表蒸散发遥感反演双层模型为基础,构建了估算沙河流域地表日蒸散发反演系统。该系统包括三部分:基于双层模型的蒸发比估算;日净辐射总量估算;基于蒸发比不变法的日蒸散发估算。模拟的典型日序列中,春季晴日流域日均蒸散发约为2.28 mm、夏季2.97 mm、秋季1.59 mm、冬季0.5 mm;以林地为主的流域上游山区日蒸散发普遍高于以居民地和农田为主的下游平原区,上下游春、秋、冬季空间差别较大,夏季较小。估算结果与贾贞贞等、徐自为等利用大孔径闪烁仪和涡动相关仪的观测值对比,相对误差介于0到16%之间,平均相对误差为11.1%,均方差为0.77 mm,精度较高。 相似文献
132.
Detection of a Toxic Product Released by a Polyurethane-Containing Film Using a Composting Test Method Based on a Mineral Bed 总被引:1,自引:0,他引:1
Maurizio Tosin Francesco Degli-Innocenti Catia Bastioli 《Journal of Polymers and the Environment》1998,6(2):79-90
The degradation of a film containing a 4,4diphenyl methane diisocyanate (MDI) poly(€-caprolactone)-based polyurethane was followed in a test system based on a mineral solid bed designed to facilitate analysis of break-down products released under composting conditions. The use of a mineral solid bed can help extraction and analytical procedures which could be hindered by the heterogeneous nature of compost. The fermentation conditions are typical of the composting environment and generate a powerfully degradative environment. The film fully disintegrated within 30 days of treatment. Analysis on the mineral bed extracts showed that: (i) about 40% of the initial polyurethane was still present in the bed extracts; (ii) this residue was strongly degraded in the poly(€-caprolactone) part, while the urethane part was almost completely recovered (from 80 to 95%, according to the measurement method); (iii) 4,4 diamino diphenyl methane (MDA), a very dangerous product of MDI, was released during biodegradation. The results indicate that a mineral bed can be employed to study degradation and metabolites formation in solid phase fermentation and that the MDI-based polyurethanes are not susceptible of a full degradation during composting and maintain the potential of a slow release of MDA into the environment after soil application. 相似文献
133.
Veska Toncheva An Van Den Bulcke Etienne Schacht Joris Mergaert Jean Swings 《Journal of Polymers and the Environment》1996,4(2):71-83
Poly (-caprolactone) (PCL), poly (-valerolactone) (PVL), poly (-caprolactone-co--valerolactone) [P(CL-co-VL)], and poly (-caprolactone-co-ethylene oxide-co--caprolactone) (PCL-PEO-PCL) were synthesized by ring-opening and diol-initiated polymerization of -caprolactone and -valerolactone. The degradation of the samples by chemical hydrolysis and in a soil burial test was evaluated. It was found that PCL, PVL, and P(CL-co-VL) degrade mainly enzymatically. The rate of degradation depends on their molecular weight, chemical structure, composition, and morphology. PCL-PEO-PCL block copolymers exhibit a repelling effect to the microorganisms in the soil, which depends on the molecular weight and relative amount of PEO block in the copolymer. 相似文献
134.
The hydrolytic and enzymatic degradation of newly developed hydrogels, produced by cross-linking purified poly(-glutamic acid) (PGA) with dihaloalkane compounds, was studied and is reported in this paper. Analysis of hydrolysis of the hydrogel as a function of pH indicated that the hydrolysis occurred slowly at neutral pH, but fast in both acidic and alkaline solutions, while the polymer could be hydrolyzed rapidly only in acidic solutions. The ester bonds were more sensitive to hydrolysis than peptide bonds. The biodegradability of the hydrogel and polymer was further confirmed when enzymatic degradation was studied by three enzymes (cathepsin B, pronase E, and trypsin), which were able to cleave both ester and peptide bonds gradually. A slow-release system for porcine somatotropin (pST) formed by using the hydrogel as matrix to entrap the hormone was evaluatedin vitro andin vivo. Results demonstrated that the hydrogel was able to release the hormone for a period of 20–30 days and indicated its potential application in slow-release systems for bioactive materials, especially macromolecules, such as peptides and proteins. 相似文献
135.
136.
采用沉积沉淀-光还原法制备了不同AgIO3含量的BiOI光催化剂,利用X射线衍射、N2吸附-脱附、扫描电子显微镜、X射线光电子能谱、紫外-可见漫反射光谱和电子自旋共振对其物理化学结构进行表征,在光催化反应器上研究了AgIO3负载量、光照、溶液温度、pH值、SO2和NO对气态单质汞(Hg0)去除性能的影响.结果表明,与BiOI相比,Ag-AgIO3改性后光催化剂的脱汞性能大幅提高.当AgIO3负载量为4wt.%时,光催化剂的脱汞效率高达98%.与NO相比,SO2对脱汞性能的抑制作用更大.由于Ag和AgIO3在BiOI表面的高度分散性,Ag-AgIO3(4%) BiOI的可见光吸收性能明显提高.荧光灯辐照与Ag-AgIO3/BiOI光催化剂协同会产生大量的活性物种.在Ag-AgIO3/BiOI光催化剂的高效脱汞体系中,超氧阴离子自由基(·O2-)为最主要的活性物质,而空穴(h+)和羟基自由基(·OH)次之. 相似文献
137.
采用嗜热膜生物反应器(TMBR)同时处理含NO和Hg0的烟气,结果发现,该反应器可实现100 d的长期稳定运行,NO和Hg0去除效率分别可达87.9%、82.4%.适宜运行条件为:喷淋量为60 m L·min~(-1),p H为6.5~8.0,气体停留时间GRT为9.3 s,COD/TN为2~4.同时,采用16S r DNA分析了TMBR微生物群落.结果表明,在属类别上优势菌种是Ureibacillus和Pseudoxanthomonas.Pseudoxanthomonas、Hydrogenophaga、Thauera、Bacillus、Paracoccus、Comamonas、Pseudomonas、Nitrosovibrio、Ochrobactrum属于脱硝类菌属;Pseudomonas和Halomonas与Hg2+转化有关.Pseudomonas同时具有反硝化和还原汞化合物能力. 相似文献
138.
采用化学-机械溴化法对废弃物石油焦进行改性,制得的载溴石油焦吸附剂用来脱除燃煤烟气中的痕量Hg0.通过比表面积及孔径分析(BET)、X射线衍射(XRD)和X-射线光电子能谱(XPS)对石油焦载溴前后进行表征和分析,发现石油焦中的有机硫促进了溴的负载,且负载方式为化学吸附.通过固定床脱汞试验,并应用4种动力学模型对初始汞浓度梯度和反应温度梯度下的实验数据进行拟合分析,结果表明:温度在150℃时,载溴石油焦的汞吸附效果最优;增加烟气中痕量Hg0浓度能提高载溴石油焦的汞吸附速率和单位累积汞吸附量;描述化学吸附的Elovich动力学模型的拟合相关系数达到0.9999以上,说明化学吸附在载溴石油焦脱汞过程中起主导作用. 相似文献
139.
Particles and porous tablets based on Fe0/ZSM-5 composites prepared by ball-milling for heavy metals removal: Dissolved Fe2 +, pH, and mechanism 总被引:1,自引:0,他引:1
Novel, low-cost Fe~0/ZSM-5-based particles and porous tablets were prepared by a ballmilling method and used for the removal of Pb~(2+) in solution. Solid-phase characterization by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy(SEMEDS) and transmission electron microscopy(TEM) revealed that the Fe0 microparticles were evenly loaded and tightly immobilized on the surface of ZSM-5 because of the extrusion/welding impact during ball-milling. For different Pb~(2+) concentrations, batch experiments indicated that the removal of Pb~(2+) increased with the decline of dissolved Fe2+and p H value in the solution for particles; opposite results were obtained for the tablets. The differences in the contact between both materials and Pb~(2+) were the main factor controlling Pb~(2+) removal in the solution. Investigation into the effect of initial p H value revealed that high p H reduced the number of electrons released from Fe corrosion. Consequently, low levels of removed Pb~(2+) and dissolved Fe~(2+) were synchronously observed. Also, simulated electroplating wastewater was treated using the prepared particles and porous tablets,and the removal order of Pb~(2+) Cr~(6+) Cu~(2+)≈ Cd~(2+) was observed. The Fe~0/ZSM-5 particles and tablets prepared through ball-milling show potential as materials for treatment of Pb~(2+) and other toxic metals. 相似文献
140.
Mats Olsson Thomas Madsen Erik Wapstra Bengt Silverin Beata Ujvari Håkan Wittzell 《Behavioral ecology and sociobiology》2005,58(3):289-294
Good genes are genetic elements that contribute to lifetime reproductive success, regardless of an individuals additional genotype. Their existence is debated, and most work has targeted their viability benefits to the offspring of choosy females. In the present study, we analyze a case of potential good genes effects in adult male sand lizards (Lacerta agilis). We show that males with a particular RFLP (Restriction Fragment Length Polymorphism) MHC genotype (O-males), as opposed to those that lack this genetic element (NO-males), have less ectoparasites under increasing physiological stress (indexed by baseline corticosterone level), and are not constrained by parasites at production of status coloration. Furthermore, O-males are more successful at mate acquisition and guard their partners longer. Ultimately, they have a higher genetic reproductive success as assigned by microsatellites.Communicated by W. Cooper 相似文献