双水相萃取-连续光源石墨炉原子吸收光谱法测定水样中的痕量锑

提出了以吡咯烷基二硫代氨基甲酸铵(APDC)为螯合剂,乙腈为萃取剂,氯化钠为无机盐的双水相萃取-连续光源石墨炉原子吸收光谱法测定水样中痕量锑的方法。优化的双水相萃取Sb³⁺的条件如下：螯合反应体系酸度为pH 4,0.5 mL的2 g·L^-1APDC储备溶液,1.6 mL的乙腈,1.2 g的氯化钠,反应时间为20 min。在此试验条件下,Sb³⁺的质量浓度在1.00～20.00μg·L^-1内与对应的吸光度呈线性关系,检出限(3s/k)为0.048μg·L^-1。分别对5.00,10.00μg·L^-1的Sb³⁺标准溶液测定10次,测定值的相对标准偏差为4.6%和3.3%。按照标准加入法对实际样品进行回收试验,回收率为95.8%～102%。将此方法用于检测自来水、河水、湖水中的痕量锑,显示这些环境样品中含有部分痕量锑。     

在无机化学教学中增加纳米化学内容的实践与探讨

简单介绍了在无机化学教学中增加纳米化学内容的重要性和意义,并对如何在无机化学教学中引入纳米化学内容进行了实践和初探。     

化学共还原法制备Mo/Ni双金属纳米颗粒及其催化制氢性能研究

采用化学共还原方法,以ISOBAM-104作为保护剂制备了Mo/Ni双金属纳米颗粒,并研究了ISOBAM-104用量、还原过程中KBH_4用量、金属离子浓度等对其催化KBH_4制氢性能的影响.结果表明:R_(ISO)=40 (R_(ISO)为ISOBAM-104与金属盐的物质的量的比),R_(KBH_4)=5 (R_(KBH_4)为KBH_4与金属盐离子的物质的量的比),金属离子的浓度为2 mmol·L~(-1)时,Mo_(10)Ni_(90)的催化制氢效果最好.在303 K的条件下,Mo_(10)Ni_(90)的催化活性达1 134 mol-H_2·mol-cat~(-1)·h~(-1),其催化KBH_4水解反应的活化能为39.84 kJ/mol.同时Mo/Ni双金属催化剂具有良好的耐久性,在九次重复试验后,其催化性能无明显降低.     

管道中CaO颗粒吸收CO2的格子Boltzmann方法模拟

采用格子Boltzmann方法对多孔CaO颗粒与CO₂之间的气固反应过程进行模拟.主要研究在二维矩形截面管道中雷诺数(Re)和孔隙率对单个CaO颗粒吸收CO₂效率的影响.结果表明:增大Re会相应提高CaO颗粒吸收CO₂气体的效率.同时对于同一Re,CaO颗粒吸收CO₂气体的效率随其孔隙率呈非线性变化,这是由于不同孔隙率颗粒固体量和渗透率存在差别因而影响化学反应的速率.     

三弹性圆柱壳体多重耦合声辐射计算方法

为研究多圆柱壳组合结构的声辐射特性,采用模态叠加法建立了3个并排无限长弹性圆柱壳的振动声散射耦合物理模型,充分考虑了三圆柱壳的表面振动与散射声场的耦合,其中散射声场可分解为各圆柱壳刚性散射声场和弹性辐射声场的叠加,数学上将各壳间的声场耦合关系通过柱函数加法公式描述。利用该物理模型,分析了多重散射对稳态声场求解结果的影响,比较了三圆柱壳耦合系统与单个圆柱壳系统的辐射声场指向性、声压级及辐射声功率级的差异及其产生机理,结果表明:结构弹性耦合声辐射不仅在低频对总声场有显著影响,在高频范围也不可忽略;另外,针对本文设定参数的组合圆柱壳,在150 Hz以上频段,两旁圆柱壳对中间圆柱壳在正横方位产生了声辐射遮蔽效应,垂直方位则体现声泄漏作用。本文建立的方法可推广到三维空间任意多壳结构的声振耦合建模。      

浙江沿海大弹涂鱼、弹涂鱼的线粒体COI基因序列差异及其系统发育

为探讨浙江沿海大弹涂鱼和弹涂鱼线粒体细胞色素氧化酶I号(COI)基因序列差异及其系统发育, 对两者进行了COI扩增、测序和分析. 结果显示: 扩增得到大弹涂鱼、弹涂鱼COI基因序列长度分别为1554bp和1556bp; 大弹涂鱼和弹涂鱼COI基因序列中, 所占比例(分别为55.8%和56.0%)均高于 所占比例(分别为44.2%和44.0%); 大弹涂鱼和弹涂鱼的种内平均遗传距离分别为0.002和0.003, 两者的种间遗传距离为0.183. 构建的系统发育树显示, 大弹涂鱼与红狼牙虾虎鱼、孔虾虎鱼、犬齿背眼虾虎鱼聚为一簇(大弹涂鱼COI序列与三者的同源性分别为91.0%、92.0%和88.0%), 弹涂鱼与青弹涂鱼聚为一簇(两者COI序列同源性为99.0%)后与大弹涂鱼所在的簇相聚. 研究结果可为探讨大弹涂鱼、弹涂鱼的系统发育及建立基于COI序列的弹涂鱼类鉴定方法提供参考资料.     

Required width of exit to avoid the faster-is-slower effect in highly competitive evacuation

A group of competitive people escaping through an exit could lead to the formation of a deadlock, which significantly increases the evacuation time. Such a phenomenon is called the faster-is-slower effect(FIS) and it has been experimentally verified in different systems of particles flowing through an opening. In this paper, the numerical simulation based on discrete element method(DEM) is adopted to study a group of highly competitive people through an exit of varying widths. The FIS effect is observed for a narrow exit whilst it is not observed for the exit wide enough to accommodate two people through it side-by-side. Experimental validation of such a phenomenon with humans is difficult due to ethical issues. The mouse is a kind of self-driven and soft-body creature and it exhibits selfish behaviour under stressed conditions.Particles flowing through an opening in different systems, such as pedestrian flow, animal flow, silo flow, etc. have similar characteristics. Therefore, experimental study is conducted by driving mice to escape through an exit of different widths at varying levels of stimulus. The escape time through a narrow exit(i.e., 2 cm) increases obviously with the increase of stimulus level but it is quite opposite to a wider exit(i.e., 4 cm). The FIS effect is avoided for an exit wide enough to accommodate two mice passing through it side-by-side. The study illustrates that FIF effect could be effectively prevented for an exit when its width is twice the size of particles.     

A numerical study of contact force in competitive evacuation

Crowd force by the pushing or crushing of people has resulted in a number of accidents in recent decades. The aftermath investigations have shown that the physical interaction of a highly competitive crowd could produce dangerous pressure up to 4500 N/m, which leads to compressive asphyxia or even death. In this paper, a numerical model based on discrete element method(DEM) as referenced from granular flow was proposed to model the evacuation process of a group of highly competitive people, in which the movement of people follows Newton's second law and the body deformation due to compression follows Hertz contact model. The study shows that the clogs occur periodically and flow rate fluctuates greatly if all people strive to pass through a narrow exit at high enough desired velocity. Two types of contact forces acting on people are studied. The first one, i.e., vector contact force, accounts for the movement of the people following Newton's second law. The second one, i.e., scale contact force, accounts for the physical deformation of the human body following the contact law. Simulation shows that the forces chain in crowd flow is turbulent and fragile. A few narrow zones with intense forces are observed in the force field, which is similar to the strain localization observed in granular flow. The force acting on a person could be as high as 4500 N due to force localization, which may be the root cause of compressive asphyxia of people in many crowd incidents.     

大数据条件下结构区间可靠性与概率可靠性比较

对于结构服役期间收集到的结构相关大数据,首先对数据进行整理与分析,根据数据的特征进行分类;然后利用应力-强度干涉理论建立结构大数据条件下区间可靠性计算模型与随机可靠性计算模型,按大数据所分类型,分别计算每一类型大数据中结构区间非概率可靠度指标与随机概率可靠度,在区间非概率可靠度指标与随机概率可靠度计算结果中,最小区间可靠性指标是结构最终的区间可靠性指标,最小随机可靠度是结构最终的随机可靠度．最后,利用两个算例说明了大数据条件下结构区间可靠性计算方法与概率可靠性计算方法的优点与缺点．     

半透明Cu2O/ZnO异质结的制备及其光电性能研究

为研究具有更好材料稳定性的半透明薄膜太阳能电池,本文采用直流磁控溅射技术沉积氧化亚铜(Cu_2O)薄膜和氧化锌(ZnO)薄膜,制备了Cu_2O/ZnO异质结.使用扫描电镜、X射线衍射仪、拉曼光谱仪、薄膜测定系统和太阳能模拟器,研究在不同氩/氧气体流量比的条件下制备的Cu_2O层对异质结的材料特性、光学特性及光电特性的影响.研究结果表明:在一定氩/氧气体流量比范围内制备的Cu_2O/ZnO异质结,在AM1.5的标准模拟太阳光的照射下具有一定的光电转换能力,可作为半透明太阳能电池的换能单元.