石英灯辐射加热条件下低密度碳/酚醛复合材料高温响应及分析

目的研究低密度碳/酚醛复合材料在不同地面加热实验测试响应的差异性,指导材料在实际应用环境下的高温响应分析。方法对低密度碳/酚醛复合材料开展了热流为400 kW/m~2的单侧石英灯辐射加热实验,利用热电偶测温系统测量试件在加热过程中不同位置的温度时间历程,并对试件的烧蚀形貌和微观结构进行观测。同时与热流为464k W/m~2的氧乙炔加热陶瓷板辐射加热实验结果进行对比分析,并且采用有限元方法对材料的传热传质多场耦合计算进行分析。结果对于石英灯辐射加热,在测量点升温到接近200℃时,温度响应拐点都依次出现。由于加热的辐射热源不同,在不同的辐射波段下,多孔材料吸收和发射的热量不同,短时间内氧乙炔加热陶瓷板辐射加热使材料内部升温速率比石英灯辐射加热实验的要快,但长时间加热时现象刚好相反。结论进行传热传质多场耦合计算材料高温响应时,合理确定材料宏观性能随温度的变化至关重要。     

牛粪-化肥配施对水稻田氮磷迁移转化的影响

在控制外源N输入量相同的前提下,通过田间小区实验,探讨有机肥与化肥不同施用量（牛粪施用量：5,10,20t/hm²）对稻田田间土-水界面氮磷迁移转化特征的影响.结果表明：控制稻田水中NH₄⁺-N、NO₃^--N、TN和TP输出的最佳时期分别为施肥后的第5,30,7,20d,且TN和TP浓度随时间变化符合单指数衰减方程（0.7444≤R²≤0.9724;1.1×10^-6≤F≤0.0055）.采用牛粪部分代替化肥的施肥方式,在一定范围内能降低稻田退水中TN、TP输出负荷（41.8%、36.0%、64.3%;20.3%、39.1%、48.9%）,还可以降低稻田水中N/P,降低水体富营养化风险.同时,牛粪的施用可提高土壤中脲酶和磷酸酶的含量,促进氮磷向植物可吸收形态转化.综合经济成本和生态效益核算,采用10t有机肥代替无机肥的处理是相对经济环保的施肥方法,该施肥方式下,氮磷年输出负荷分别为17.70,1.26kg/hm².     

Effects of Na+ on Cu/SAPO-34 for ammonia selective catalytic reduction

Copper-exchanged chabazite (Cu/CHA) catalysts have been found to be affected by alkali metal and alkaline earth ions. However, the effects of Na⁺ ions on Cu/SAPO-34 for ammonia selective catalytic reduction (NH₃-SCR) are still unclear. In order to investigate the mechanism, five samples with various Na contents were synthesized and characterized. It was observed that the introduced Na⁺ ion-exchanges with H⁺ and Cu^2 + of Cu/SAPO-34. The exchange of H⁺ is easier than that of isolated Cu^2 +. The exchanged Cu^2 + ions aggregate and form “CuAl₂O₄-like” species. The NH₃-SCR activity of Cu/SAPO-34 decreases with increasing Na content, and the loss of isolated Cu^2 + and acid sites is responsible for the activity loss.     

碳量子点掺杂氮化碳提高的光电化学阴极保护性能研究

目的研究g-C_3N_4/C-Dots-M复合材料的光电化学阴极保护性能。方法采用X射线衍射(XRD)、扫描电子显微镜(SEM)和紫外可见漫反射光谱技术对样品的晶体结构、微观形貌和光吸收性能进行表征。通过电化学测试可见光照射下g-C_3N_4/C-Dots-M复合材料光电极偶联316L不锈钢后的光电化学阴极保护电流密度和电位变化曲线,研究材料的光电化学阴极保护性能。结果可见光照射下,该偶联体系的光致混合电位下降至-0.43 V(vs. Ag/AgCl),光电化学阴极保护电流密度达到4.3μA/cm。结论得益于碳量子点优异的电子传导特性,g-C_3N_4/C-Dots-550复合材料的光电化学阴极保护性能比纯g-C_3N_4的明显增强。该复合材料在光电化学阴极保护方面展现了较大的应用潜力。     

Effect of Humic Acid on the Bioavailability of γ-Hexachlorocyclohexane in Marsilea Minuta (L.)

Effect of various concentrations of humic acid (0.2 to 1%) on thebioavailability of -HCH in vegetative clones of theaquatic fern Marsilea minuta was studied in a staticexperimental bioassay system on different photoperiods. Additionof humic acid showed the reduction in the bioavailability of-HCH in all the photoperiods (72 hr light to 144 hrlight) at the interval of 16 hr light (L) and 8 hr dark (D) inboth aerial and submerged portion as compared to controlindicating its protective role in toxicity.     

Distribution of airborne particles from multi-emission source

The purpose of this work was to study the distribution of airborne particles in the surroundings of an iron and steel factory in southern Finland. Several sources of particulate emissions are lying side by side, causing heavy dust loading to the environment. This complicated multi-pollutant situation was studied mainly by SEM/EDX methodology.Particles accumulated on Scots pine bark were identified andquantitatively measured according to their element content,size and shape. As a result, distribution maps of particulateelements were drawn and the amount of different particle typesalong the study lines was plotted. Particulate emissions fromthe industrial or energy production processes were not themain dust source. Most emissions were produced from theclinker crusher. Numerous stockpiles of the industrial wastesand raw materials also gave rise to particulate emissions as aresult of wind erosion. It was concluded that SEM/EDXmethodology is a useful tool for studying the distribution ofparticulate pollutants.     

Response of the Ascorbate-Peroxidase of Selenastrum capricornutum to Copper and Lead in Stormwaters

The green alga Selenastrum capricornutum expresses a uniqueascorbate peroxidase, that responds to copper and lead. Attemptswere made to test if this peroxidase could be used to monitor thelevels of copper and lead in natural waters. When S.capricornutum was exposed to a stormwater sample, the specificactivity of the peroxidase in the cell extract was commensuratewith the combined copper and lead contents in the sample. Theperoxidase responses were also correlated with the 96 hr biomasstoxicity assay of S. capricornutum. However, unlike thebiomass toxicity assay, the peroxidase activity was not affectedby the anions in the samples. The use of this peroxidase can beused as a marker for testing heavy metal toxicity in the water.     

HNO_3─KI─MIBK萃取／原子吸收光谱法测定固体废物浸提液中的微量银

采用选择性较好的ＨＮＯ３—ＫＩ—ＭＩＢＫ萃取体系对铋渣和尾矿渣浸出液中的痕量银进行预分离富集后，用火焰原子吸收法（ＡＡＳ）进行测定。此法不仅变异系数小（约为３．１％），而且检出限比直接火焰ＡＡＳ法降低两个数量级，达０．５ｎｇ／ｍｌ．另外，还就作品细度对银测定结果的影响原因做了初步探讨。     

新疆生态环境质量综合评价研究

合适的评价指标体系对正确评价区域的生态环境质量起关键的决定性作用。本文综合前人的研究成果，应用RS和GIS技术，采用综合指数评价法，对全疆区域的生态环境质量进行评价、排序及分级，由此得出符合实际的全疆生态环境质量状况。结果表明，全疆生态环境质量总体较差，北疆生态环境质量优于南疆，北疆西部生态环境质量优于北疆东部地区。     

面向新世纪的MARPOL73／78公约及其附则Ⅱ

国际海事组织目前正在对《ＭＡＲＰＯＬ７３／７８公约》附则Ⅱ－控制散装液体有毒物质污染规则作重大修改，内容包手胡毒液体物质和化学品，这很可能对主管机关、船公司和化工界造成严重的冲击。