HOW TO DETERMINE THE NUCLEAR MATRIX ELEMENT IN 2β-Decay?-A DISCUSSION OF PCAC, 2β-DECAY AND DOUBLE-CHARGE EXCHANGE REACTION OF PIONS ON NUCLEI

It is shown that by applying PCAC, the 2β-decay process can be directly related to double-charge-exchange reaction. Therefore, by studying double-charge-exchange reactions one is able to determine the nuclear matrix element of the relevant 2β-decay experimentally. A preliminary analysis has indicated that if the experimental data of forward-angle cross section on Ca⁴⁰ with pion beam at 164 Mev^[9] are used and extrapolated to Ca⁴⁸, then the squared nuclear matrix element thus determined is smaller than that calculated for Ca⁴⁰→Ti⁴⁸+2e^-+2v^[11] by 10⁵～10⁶.     

IS 40Ca A STABLE ISOTOPE?

It is shorn that the double magic nucleus ⁴⁰Ca is unstable with respect to the double K-electron capture ⁴⁰Ar. By using the shell model wave functions for both ⁴⁰Ca and ⁴⁰Ar, the lifetime of ⁴⁰Ca is estimated as 1.2×10³³yrs.     

高频红外碳硫仪测定区域地球化学样品中的硫

高频红外碳硫仪由于便捷高效,常应用于区域地球化学样品中硫的分析检测。本文采用高频红外碳硫仪测定低中高含量的硫,以纯铁屑、锡粒和钨粒为助熔剂,对样品称样量、助熔剂的种类、加入顺序和用量等因素进行探讨,确定了最佳分析岩石、土壤和水系沉积物中硫含量的条件,并且用国家一级标准物质验证了该方法的准确度和精密度。结果表明,当样品和助熔剂的加入顺序和质量分别为：0.05 g样品、0.5 g铁助熔剂、1.7 g钨粒时,土壤和水系沉积物中硫的测定结果最稳定,岩石标准样品额外的加入0.5 g锡改善样品流动性,提高分析准确度。该方法的相对标准偏差（RSD）小于6%（n= 12）,相对误差绝对值小于8%。此方法具有操作简单、高效、稳定性好的特点,适合于大批量区域地球化学样品中硫的检测。     

基于银膜孔阵列超强透射效应的相敏表面等离子体共振传感器的仿真研究(英文)

We present an ultra compact and high resolution free space optical spectrometer and demonstrate it by using FDTD simulations. The miniature interferometer-based spectrometer is a series of submicron phase objects on a polymethyl methacrylate(PMMA) film with a CCD as the detector. The spectrum is obtained by solving a system of simultaneous linear equations. The Tikhonov regularization method is used to achieve a resolution at the picometer level. Compared with conventional spectrometers, the proposed device...     

Thermodynamic,structural and morphological studies on liquid-crystalline blue phases

Abstract

This article describes the progress in experimental studies of liquid-crystalline blue phases during the past 5 years. Additionally, these results are compared critically with the predictions of theories of the blue phases. Areas considered in this review include (i) the thermodynamic stability of the three polymorphic blue phases and the influence of the cholesteric pitch on this; (ii) the phase diagrams of blue phases; (iii) electric field effects on the blue phase structure and stability; (iv) the morphology and growth of liquid single crystals of blue phases; (v) the symmetry and structural properties of the blue phases.     

STABILIZATION OF LIPID BILAYERS ON SURFACES THROUGH CHARGED POLYMERS

ABSTRACT

It is our concept to use a polymer as a hydrophilic cushion to stabilize a lipid bilayer on a solid support. This can be accomplished by using polyacrylamides with disulfides and DMPE anchors as a hydrophilic cushion. These polymers have the additional functionalities to chemisorb on gold surfaces through the disulfides and to bind a lipid bilayer on it through the insertion of the lipid anchors into the lipid bilayer. This paper shows that a polymer with the additional functionality of charged groups increases the attraction of vesicles to form a tethered supported lipid bilayer. By varying the amount of charged groups in the polymer, we are able to control the hydrophilic behavior of the polymer and therefore are able to change the wetting on a surface. This was examined by measuring the contact angles. Using the technique of the surface plasmon spectroscopy, we are able to monitor the process of vesicle fusion on the polymer support.     

Human Neuroepithelial Cells Express NMDA Receptors

L-glutamate, an excitatory neurotransmitter, binds to both ionotropic and metabotropic glutamate receptors. In certain parts of the brain the BBB contains two normally impermeable barriers: 1) cerebral endothelial barrier and 2) cerebral epithelial barrier. Human cerebral endothelial cells express NMDA receptors; however, to date, human cerebral epithelial cells (neuroepithelial cells) have not been shown to express NMDA receptor message or protein. In this study, human hypothalamic sections were examined for NMDA receptors (NMDAR) expression via immunohistochemistry and murine neuroepithelial cell line (V1) were examined for NMDAR via RT-PCR and Western analysis. We found that human cerebral epithelium express protein and cultured mouse neuroepithelial cells express both mRNA and protein for the NMDA receptor. These findings may have important consequences for neuroepithelial responses during excitotoxicity and in disease.     

部分屏蔽多极电子鎗聚焦问题

本文对于在有磁场下多阳极电子鎗的电子注聚焦问题进行了理论分析。阴极处磁场可以具有任意屏蔽程度,得到了在加速场内描写电子轨迹的傍轴方程的解析解。在理论分析中,考虑了包括空间电荷效应的情况。