Fluorescent probes: a new way to study lymphocyte activation

Fluorescent dyes can be used as cell probes which bind, according to their chemical structure, to particular subcellular regions of lymphocytes. Because of their sensitivity to variations in the local molecular environment, expressed by changes in fluorescence emission, they provide a means of studying the early events of lymphocyte activation to antigens and mitogens. The technology also yields a rapid assay of lymphocyte activation and thus new diagnostic tests of cell-mediated immunity, for example to organ transplants and to cancer.     

秦始皇兵马俑博物馆室内含硫颗粒物的SEM-EDX研究

本文对秦始皇兵马俑博物馆室内采集的长短期降尘、大气悬浮颗粒物和彩绘漆层进行了SEM-EDX研究，在大气悬浮颗粒、短期和长期降尘中，含硫颗粒的粒径分别为0.9～22.8μm、1.0～29.0μm和1.2～37.7μm，多为石膏与粘土或石英以内部混合的状态存在。降尘中的附着型絮状硫酸钙多于大气悬浮颗粒物中，显示降尘和大气中的二氧化硫发生了累进的化学反应。彩绘漆层表面的坑和裂隙附近观察到原位生长的硫酸钙晶体，显示漆层材料或降尘颗粒物与大气二氧化硫之间的酸化学反应，可能是彩绘漆层表面受侵蚀形成微小坑和裂隙的原因之一。     

A walsh series direct method for solving variational problems

This paper establishes a clear procedure for the variational problem solution via the Walsh functions.technique. First the Walsh functions are introduced and their properties briefly summarized. Then an operational matrix is derived for integration use. The variational problems are solved by means of the direct method using the Walsh series. An illustrative example and a practical application to a heat conduction problem are included.     

Effects of axial conduction in laminar tube flow with convective boundaries

Heat transfer in laminar tube flow with convective boundary conditions and axial heat conduction in the fluid is solved exactly. The effects of the external Biot numbers and the axial conduction in fluid on the temperature distribution and the local Nusselt number are determined for both the upstream and the downstream regions. In order to illustrate the effects of velocity profile, the results for the slug flow and the parabolic velocity profiles are plotted simultaneously. The heat transfer characteristics of the flow are found to be rather sensitive to the Péclét number, the external Biot numbers and the velocity profile in the thermal entrance region.     

Restrictions of the derivatives of positive real functions

Dissipative operators appear in abundance in the study of dynamical systems. In the classical circuit theory they are presented as Positive Real Functions. The coefficients of the Taylor expansion of PRF (driving-point impedance or admittance) must satisfy certain derived inequalities. A method is suggested for obtaining restrictions of the derivative of Positive Real Functions (Dissipative Operators).