EFFECTS OF ULTRAVIOLET RADIATION ON THE MITOTIC CYCLE AND DNA, RNA AND PROTEIN SYNTHESIS IN MAMMALIAN EPIDERMIS IN VIVO

Abstract— Acute effects of ultraviolet radiation on the mitotic cycle and macromolecular synthesis were investigated on hairless mouse epidermis in vivo. Colcemid was used to arrest mitoses in metaphase and thus allow more accurate mitotic counts. The radioactive tracers, TdR-³H, cytidine-³H, and the amino acids, histidine-³H and methionine-³H were used to examine DNA, RNA and protein synthesis, respectively. Using these techniques, we found that wavelengths shorter than 320 nm markedly inhibited mitosis, increased the basal cell turnover time and depressed DNA, RNA and protein synthesis within the first few hours post-irradiation. By 24hr, recovery and acceleration of these functions were in progress, reaching a peak by 48–72 hr and persisting though to a lesser degree for 7 days. This stage of acceleration was associated with epidermal hyperplasia and most likely represented post-injury cell renewal.     

A Challenge: Can Mathematics Aid Development of the Process of Operational Research?

Some of the structures developed by operational researchersto help clients explore a problem-situation and design a wayforward are described briefly. The difficulty of getting appropriatemathematical support for the analysis, interpretation, and developmentof these structures is discussed.     

(La1-xCex)2/3Ca1/3MnO3体系的输运性质和反常磁特性研究

本文报告了对Ce掺杂锰氧化物(La1-xCex)2/3Ca1/3MnO3 (x=0～1.0)系列样品的输运特性和反常磁特性的研究结果.实验表明,Ce掺杂对Tc有明显的抑制作用,整体上电阻率随Ce掺杂含量增加而上升,在外加磁场时表现出极大的磁电阻效应.磁化强度随温度变化的曲线出现了两个转变,高温处对应于Mn离子磁矩的铁磁金属转变,低温处的转变则对应于Ce离子磁矩自旋有序排列的形成.表明Ce掺杂引起样品中铁磁双交换作用和反铁磁超交换作用之间的竞争,Ce离子与Mn离子有很强的相互作用.随Ce掺杂含量的增加,铁磁有序转变温度下降,而反铁磁有序转变温度则向高温处移动,铁磁区域明显减小.     

加拿大一枝黄花的研究及应用现状

加拿大一枝黄花(Solidago Canadensis L.),是原产于北美的一种菊科多年生草本植物,20世纪30年代开始进入我国,现在这种植物已成为我国大部分境内迅速扩散传播的恶性杂草。目前,国内外的很多研究者已经利用各种方法从加拿大一枝黄花中提取出了倍半萜烯类、氨基酸、醇类等化学物质,对其生物性能进行了研究,并且对于控制这种植物的生长提出了各种解决方案。同时,加拿大一枝黄花已经在提炼精油、医学制药等方面得到广泛的应用。     

光参量振荡器在红外对抗中的应用研究

介绍了光参量振荡器在红外对抗技术中的应用背景和意义,同时对激光红外对抗的一些基本原理进行了讨论,给出了干扰激光能量的具体分析.用所研制的中红外LiNbO3-OPO,分别通过改变其输出波长和工作频率,对红外热像仪进行了干扰原理性实验.当干扰激光波长为3.8μm,重频20Hz时,成功使热像仪解除锁定.最后,对实验结果进行了分析和讨论.     

A STUDY OF ULTRA-HIGH ENERGY γ-RAYS BY EMULSION CHAMBERS

Ultra-high energy γ-rays have been observed by emulsion chambers exposed at Yunnan Station （3200m, 700g/cm² atmospheric depth）. The integral spectrum, the vertical intensity and the attenuation length in air of the gamma rays in the energy region 2 TeV to 30 TeV are presented. The results of gamma ray families with total observed energies ranging from 5 TeV to 70 TeV are discussed.     

合金钢光谱分析通用方法

本文介绍利用溶液法和粉末法进行合金钢光谱分析的方法,以克服制备标准样品的困难和消除样品组织结构和物理状态的影响。将钢样溶解于酸制成的溶液,滴在平头碳电极上用火花激发,或将钢样制成氧化物粉末,填于碳孔中,用交流电弧激发。初步结果指出,这些方法可以满足一般分析要求。     

新型低beta超导腔调谐算法分析与测试

为了使腔体在复杂电磁环境下处于谐振状态,保持超导腔加速电压的幅度相位稳定,研发了一种应用于自激锁相模式的腔体新型调谐算法。利用正交电压Q值控制调谐器调谐,从而消除了输入和输出间的相位误差,给出了理论推导过程与该算法的可靠性分析。该算法已应用于中国科学院近代物理研究所ADS项目超导加速器中,简化了传统控制模式中的信号采样数量,提高了系统控制精度与抗干扰能力,使腔体克服了在调谐过程中由于功率上冲引起的氦压波动。保证了超导腔在工作状态下,频率稳定在162.5 MHz,频率误差小于17 Hz。For the purposes of keeping the resonant cavity steady in a complex electromagnetic environment and maintaining stable amplitude and phase, a new tuning algorithm for superconducting RF cavity operated in self-excited phase-locked mode has been developed. The quadrature voltage was employed to control the tuner under the phase-locked condition, so as to eliminate phase measurement between the input and the output. This paper demonstrates the principle of this "Minimum Q" tuning algorithm and presents an analysis of the stability of the system. The algorithm is applied to the superconducting accelerator of the Institute of Modern Physics' ADS project. The "Minimum Q" tuning algorithmnot only simplifies the number of signal sampling but also improves the control accuracy and anti-interference ability of the system, while enables the cavity to overcome the helium pressure fluctuation which caused by power overshoot. It ensures that the frequency of the superconducting cavity is stable at 162.5 MHz, and the frequency error is less than 17 Hz.     

椭圆软波导组件功率容量提升的工程研究

作为常用的雷达系统中馈线元件椭圆软波导组件在工程应用中易出现空气击穿问题很少提及,本文通过对输入驻波的频带特性和调谐螺钉的电特性两个方面的研究试验,获得了显著提升椭圆软波导组件实际功率容量的方法,很好地解决了耐功率问题,具有一定的工程应用价值。     

Experimental determination of molecular polarizability anisotropy of nematogens by depolarized Rayleigh light scattering

The anisotropy of molecular polarizability Δα of several nematogens has been determined by depolarized Rayleigh light scattering. The experimentally determined values were found to be noticeably smaller than those obtained by MOPAC calculation. Δα values determined from order parameter S and refractive indices show reasonably good agreement with those determined in the present experiment. This result warns us that Δα calculated by MOPAC, particularly at a finite wavelength, may be larger than the true value.