改性壳聚糖吸附剂对水中低浓度汞的吸附

制备了几种改性壳聚糖吸附剂,通过优化试验确定了制备改性壳聚糖吸附剂的乙酸/壳聚糖浓度配比及固化碱液条件,并比较了不同吸附剂对Hg2+的吸附性能.以分子印迹法结合交联胺化改性法制备的Hg2+分子印迹改性壳聚糖吸附剂小球(P-C-CTS-ex(Hg0.3))对Hg2+具有最高的吸附容量,在低浓度Hg2+(CHg2+<40mg/L)溶液中,此吸附剂对Hg2+的吸附容量可达9.017 mg/g,比未改性壳聚糖(CTS)的吸附量高出1倍以上.研究还揭示了交联前Hg2+对壳聚糖分子中的活性氨基的保护功能及除Hg2+后的分子印迹作用.循环再生实验表明,P-C-CTS-ex(Hg0.3)经过8个循环以后的吸附容量保持稳定,颜色与外观等基本不变,重复使用性能稳定;而未改性CTS吸附剂经过"吸附-脱附-再生"8个循环后,球体积明显变小,颜色逐渐变黄,吸附容量不稳定.这表明本研究制备的Hg2+分子印迹改性壳聚糖吸附剂的吸附容量和再生性能均明显优于普通壳聚糖吸附剂,具有应用于含Hg废水处理的潜力.     

基于距离函数的3种夹具定位分析方法的比较

建立了点-面、面-面有向距离函数的一阶、二阶微分表达式的统一理论模型.在此理论模型的基础上提出了线性方法(基于点面距离函数一阶微分性质)、单边二次方法(基于点-面距离函数一、二阶微分性质)和双边二次方法(面-面距离函数一、二阶微分性质)的3种夹具定位分析方法,进而分析了定位元和工件的局部曲率对夹具定位精度的影响.仿真试验表明:当定位元的曲率半径相对于工件的曲率半径较小时,3种分析方法的精度相当;但当定位元的曲率半径相对于工件的曲率半径较大时,线性方法、单边二次方法不能跟踪理论值的变化,而双边二次方法却能很好地跟踪理论值的变化,表明了双边二次模型的高精度特性.     

不对称模态密频结构的主动控制

分析了具有不对称模态的密频结构在脉冲荷载作用下,采用单主动质量阻尼器(AMD)和双AMD在速度和状态反馈下进行主动控制时,两个密集频率模态之间的模态阻尼比的分布规律;通过构建采用具有密集频率的斜拉桥模型并进行了主动控制试验,通过模态分析将试验结果和理论分析结果进行了对比验证,结果显示了较好的吻合程度.     

关于右型B半群的真覆盖

给出了右型B半群真覆盖的定义. 证明了相应于一右型B半群的任意真覆盖为作用于左消去幺半群上的相应于该右型B半群的真覆盖,并给出了相应于右型B半群的真覆盖的结构定理.     

Protection efficacy of national wetland reserves in China

Wetlands have the most abundant biodiversity,the highest carbon sequestration capacity,and the highest values for ecological services per unit area,of all the world’s ecosystems.Practice has shown that establishing reserves is the most effective way of protecting typical ecosystems and their biodiversity,and saving rare or endangered wildlife.The Chinese government’s policy is to protect wetland systems by establishing reserves that encompass a massive network of wetlands,including wetland nature re-serves,internationally important wetlands,and wetland parks.Many are already established.The effect of protecting wetland nature reserves at the national level has not yet been reported.We used the latest database evaluating the protection value of wet-land reserves,and remotely sensed wetland maps(1978-2008) ,developed by the same mapping specialists and based on the same classification system,and related environmental data,to evaluate the effects of protecting China’s national wetland reserves over the last 30 years.We conclude that(i) the total area of wetland in the national wetland reserves has decreased over the last 30 years to 8152.47 km2,and just 8% of China’s net decrease in wetlands;(ii) about 79% of the 91 national wetland reserves are in a poor condition.These are generally located around the Yangtze River,Eastern Coast,the Three Rivers Source,and Southwest China.Protection measures should be undertaken urgently in these areas.Only 15% of national wetland reserves are under sound protection,and these are generally located in the upper reaches of the Songhua River;(iii) although 88% of national wetland re-serves are primitive(relatively natural) ,implying that the site selection has been scientific,a high percentage of national wetland reserves show early warning signs of decline and require urgent attention;(iv) based on our evaluation of protection effects and pressures on ecology,we have made a priority list of national wetland reserves,and propose several protection strategies.     

十氢十硼酸双四乙基铵/纳米铝复合物的制备及其性能

为了改善硼氢燃料的能量输出特性,提高其作为推进剂及火炸药添加剂的燃烧效率,使用溶剂-非溶剂法制备了十氢十硼酸双四乙基铵/纳米铝含能复合物,并对其表面形貌、比表面积、热性能及气体分解产物进行了研究。结果表明,使用溶剂-非溶剂方法可制备具有良好分散性的十氢十硼酸双四乙基铵/纳米铝复合物,并能极大的减少纳米铝的团聚。复合物的比表面积为7. 06 m~2/g,远大于混合物的0. 20 m~2/g。BHN-10/纳米铝复合物在分解过程中可形成一种熔融分解型的中间产物,分解过程分为两个阶段,两阶段的分解温度分别为285. 1℃和304. 4℃,在形成BHN-10/纳米铝复合物后分解温度提前,第一分解放热峰提前到262. 0℃,第二分解放热峰提前到298. 8℃。分解气体产物主要为乙烯、乙烷、氨气和氢气等具有高热值的可燃性小分子气体。     

几个扩展基础上的载荷试验及其蠕变行为研究

应用一个新的模型分析了几个扩展基础载荷试验,着重揭示前人无法解释的土体的蠕变行为。发现:使用的模型能够表征扩展基础载荷试验下土体的蠕变行为,且经模型变换后的应变时间曲线在双对数轴上是一条直线,其斜率为模型的指数n值,且n的取值与模型的参考量无关;载荷试验下土体蠕变行为的原始数据受到木制反力梁的自重蠕变、卸载-再加载、不等的蠕变观察时间等三个因素的干扰,当剔除这些干扰后得到的n值荷载水平曲线,显示n值与应力水平无关,n可以被看作表征土体的蠕变特性的一个指标。     

自激流体处理装置阻垢机理研究

在水浴条件下,使用自来水及配制水,研究自激流体处理装置的阻垢机理。自来水成垢量对比实验发现,市政自来水经自激流体处理装置处理后,水垢的生成量小于未经处理的水样。配制水成垢速率实验表明,电导率随时间的下降曲线可以分为四个阶段,对照组水样结垢主要发生在第一阶段,实验组水样结垢主要发生在第二阶段。在60℃的水浴条件下,自激流体处理装置的阻垢时长约为30 min。电镜观察表明,经自激流体处理装置处理的水样形成的水垢结晶主要为文石,未经自激流体处理装置处理的水样形成的水垢结晶主要为方解石。     

Lithium isotope evidence for subduction-enriched mantle in the source of mid-ocean-ridge basalts

'Recycled' crustal materials, returned from the Earth's surface to the mantle by subduction, have long been invoked to explain compositional heterogeneity in the upper mantle. Yet increasingly, problems have been noted with this model. The debate can be definitively addressed using stable isotope ratios, which should only significantly vary in primitive, mantle-derived materials as a consequence of recycling. Here we present data showing a notable range in lithium isotope ratios in basalts from the East Pacific Rise, which correlate with traditional indices of mantle heterogeneity (for example, 143Nd/144Nd ratios). Such co-variations of stable and radiogenic isotopes in melts from a normal ridge segment provide critical evidence for the importance of recycled material in generating chemical heterogeneity in the upper mantle. Contrary to many models, however, the elevated lithium isotope ratios of the 'enriched' East Pacific Rise lavas imply that subducted ocean crust is not the agent of enrichment. Instead, we suggest that fluid-modified mantle, which is enriched during residency in a subduction zone, is mixed back into the upper mantle to cause compositional variability.     

纳米铝在炸药中的分散性和成型性

为了研究纳米铝在炸药中的分散性和成型性,利用不同溶剂对纳米铝进行了分散;利用超声波分散法、高速剪切混合法、叶片式搅拌混合、分散加高速分散机混合对黑索金/铝(RDX/Al)体系进行分散;采用熔融混合造粒工艺研究了不同纳米铝粉含量的成型性,采用直接混合造粒工艺研究了不同纳米铝粉含量对RDX/Al体系成型性,结果表明:乙酸乙酯的分散效果最好;超声分散可以提高纳米铝粉的分散均匀性;采用的三种工艺可以达到相同的分散效果;微米铝和纳米铝在三硝基甲苯(TNT)中的成型性基本无变化;在RDX/Al体系的压装炸药中,含纳米铝的炸药成型性较含微米铝的炸药差;含纳米铝炸药的密度随铝粉含量增加呈现非线性变化,而纳米铝和微米铝级配的炸药密度随铝粉含量增加呈现线性增加.