辐射演示实验的改进

初中物理第二册第二章辐射中的实验受天气和阳光位置的影响较大,做起来很不方便,为弥补教材中实验的不足,我将辐射源改用40W白炽电灯,将其一侧涂成黑色,另一侧涂成白色,用凡士林将火柴对称地粘在灯泡黑、白处。实验时用两根火柴掉落的时差演示物体表面的颜色与吸收辐射本领的关     

差异蛋白质组学在水生动物免疫研究中的应用

差异蛋白质组学是指依据蛋白质样品在不同时期、不同组织、不同状态或不同外界条件下表达不同,来筛选、鉴定蛋白质,可以通过对差异蛋白质的分析鉴定研究编码该差异蛋白的基因,扩展对该基因功能的研究,也可以结合功能蛋白质组学研究,发现新的蛋白质,完善已有的蛋白质组数据库.     

相分离免疫分析的研究进展

相分离免疫分析通过开展快速的均相反应和简单的异相分离而兼具了均相免疫与异相免疫的优点,方法易于实现自动化.本文介绍了相分离免疫分析的基本原理,对相分离免疫分析载体、固定化方式、标记物、应用及发展方向进行了评述.引用文献60篇.     

两种环境敏感高分子在相分离免疫分析中的比较研究

进行了两种环境敏感高分子在相分离免疫分析嗜水气单胞菌外膜蛋白(outer membrane protein, OMP)中的比较研究. 首先合成温度敏感高分子聚N-异丙基丙烯酰胺和pH敏感高分子聚(N-异丙基丙烯酰胺-甲基丙烯酸), 分别以N-羟基琥珀酰亚胺丙烯酸酯(NAS)和碳二亚胺(EDCI)作为偶联剂与抗OMP抗体(Ab)偶联形成抗体复合物(Ab-polymer), 在竞争型免疫测定中, OMP标准溶液与异硫氰酸荧光素标记OMP在均相条件下竞争性地与Ab-polymer反应, 调节外界环境分离出高分子免疫复合物沉淀, 重新溶解后荧光法定量, 两种体系的OMP浓度均在400～3000 ng/mL范围内与荧光强度呈良好线性关系, 检出限分别为84.7和39.6 ng/mL. pH敏感高分子相比于温度敏感高分子具有以下优点: 可以在37 ℃的生理温度进行免疫反应, 进一步提高了免疫反应的速度和效率; 可利用高分子本身的活性基团进行Ab的固定, 固定化效率、固定Ab的免疫反应活性较之NAS偶联法得到了提高; 有更高的检测灵敏度. 因此, pH敏感高分子更适合于作为相分离免疫分析的载体.     

Nb_3Sn的热电势率

我们测量了Nb_3Sn从4.2K到273K的绝对热电势率,结果表明在18 K以上,Nb_3Sn的热电势率都是正的.在60K左右,观察到由于声子曳引引起的平坦的峰.第一次观察到在超导临界温度附近,热电势率也有一个明显的转变过程.     

荧光团杂化纳米SiO2微球作为生物标记探针的应用研究

近年来 ,无机发光量子点[1,2 ] 、荧光纳米乳液微球[3 ,4 ] 及发光团掺杂 Si O2 纳米粒子[5] 等纳米荧光探针的出现 ,为生物标记提供了新的发展领域 .将有机染料以共价方式包埋在 Si O2 中所得的复合材料具有独特的光学性质 ,然而其在生物标记方面的应用并未得到重视[6 ,7] .本实验通过控制荧光团修饰的硅烷前体在反相胶束体系中的水解缩合 ,合成了用于生物染色和诊断的高灵敏度、高稳定性的新型荧光团杂化纳米 Si O2 微球 ( NFHS微球 ) .在 NFHS微球中 ,荧光团以共价方式地均匀分散在 Si O2 网络结构中 ,避免了与外界体系中溶解氧的…     

不同材料和不同能通量条件下电子束喷射冲量的实验研究

 介绍了采用直接测量特定时间间隔系列和微型红外通光式传感技术的探头原理,在“闪光二号”电子束装置上进行的喷射冲量随不同材料和不同能通量而变化的实验研究。实验结果表明,在能通量大体相同时,A和B这两种特种材料的喷射冲量耦合系数分别只有LY-12铝的1/3和1/2左右。这说明此两种特种材料在受辐照条件下具有良好的降低喷射冲量的性能。     

有机EL器件MEH-PPV/Alq3的光伏特性

制备了ITO/MEH-PPV/Alq3/LiF/Al光伏(PV)器件. MEH-PPV和Alq3分别为电子受体和给体. 光谱响应曲线主要和Alq3的吸收光谱相匹配. 在功率为0.5 mW·cm2的紫外氙灯照射下电池的短路电流为2.4 μA·cm-2, 开路电压为2.6 V, Fill因子为0.71, 电池的能量转换效率达到0.9%. 在直流电的驱动下, 器件具有电致发光的特性并且发出明亮的桔红色光, 在15 V的直流电压驱动下, 最大亮度达到了1 000 cd·cm-2.     

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.