由呼出气中的氡浓度估计铀矿工体内~(225)Ra的负荷量

本文测量了某铀矿不同工种的56名矿工下矿井作业前的呼出气中的~(222)Rn浓度,并由此估算了他们体内的~(226)Ra 负荷量。按不同工种的人数加权,呼出气中的~(222)Rn 浓度平均值为34.1Bqm~(-3),体内~(226)Ra 负荷量的均值为1.95kBq。同时还对9名休息了2天的和2名离开井下作业3—4年的矿工以及12名来下过矿井的本矿工人呼出气中氡浓度进行了测量,由此估算出其体内~(226)Ra 负荷量的均值分别为1.11、0.94和0.17kBq。     

鄱阳湖湖底沉积物放射性水平

本文报道了1985年鄱阳湖湖底沉积物放射性水平的调查结果。沉积物中 U、Th、~(226)Ra、~(40)(?)和~(137)Cs 的比活度分别为64.8、67.9,58.9、676.1和3.5Bq/kg;用~(137)Cs 测龄方法作了沉积物泥芯垂直深度的年代定位,由此得知1985—1958年对应深度沉积物中 U、Th、~(226)Ra 和~(40)K 的比活度与1957—1930年对应深度沉积物比较无显著性差异;U、Th 和~(226)Ra 的浓集因予分别为5.2×10~413.9×10~4和4.8×10~4L/kg。     

SVG技术在J2ME手机游戏的应用研究

无线游戏是无线技术的一个应用热点.为了解决无线游戏中光栅格式图形处理中存在失真、图像尺寸较大等问题,探讨了W3C组织提出的Mobile SVG规范,应用矢量图形技术解决无线游戏中图形处理问题.具体方法是利用SVG文件定义游戏中的各个游戏基元,运用SUN公司开发的JSR-226应用接口,访问并控制各个矢量图形基元.为了说明该思路的可行性,利用JSR.226中定义的开发包开发了一个基于Sprite的直排滑轮游戏,希望能为无线游戏开发提供一个思路.     

Analytical Models for Migration of Radionuclides in Geologic Sorbing Media

In safety evaluation of nuclear waste repository systems, the analysis on migration of radionuclides in geologic media is important. In previous analytical models called Band- Release, Step-Release and Impulse-Release for decay chains, nuclide-specific release rate and time-dependence of release rate can not be taken into consideration. In this paper, two new release models are proposed. In Preferential-Release model, both of nuclide-specific release rate and time-dependence of leach are taken into account. Exponential-Release model is a special case of Preferential-Release model, in which no preferentiality in leach is assumed. The obtained analytical solutions for these new models are applicable even to four or more member decay chains and are as simple as those for the previous models.

As an example of the application of the new models, the discharge rates of the four nuclides in the decay chain of ²³⁸Pu→²³⁴U→ ²³⁰Th→²³⁶Ra→ into a surface water body are calculated as a function of time after the start of leach and path length from the repository. By using the result, heavy hazard due to ²³⁸Pu at short distance and ²²⁶Ra at long distance are also discussed briefly.     

一种制备细胞色素C的方法

为了保证细胞色素Ｃ药用的安全性，需要高纯度的细胞色素Ｃ。对新鲜猪心采取提取、吸附、洗脱、去杂、沉淀、树脂纯化等一系列方法，从而制得了纯度较高的细胞色素Ｃ。     

基于PXA255的ARM Linux操作系统移植

Linux在嵌入式领域中应用越来越广泛,已成为最有潜力的嵌入式操作系统。操作系统的移植是进行嵌入式应用开发的前提和基础。ARM Linux是一种针对ARM体系结构的Linux操作系统。本文以新一代高端嵌入式处理器PXA255为例,进行ARM Linux的移植,阐述了移植中需要解决的关键技术,包括:内核的定制、文件系统的创建、设备驱动的移植等。最后,在移植成功的平台上实现了无线接入点。     

The photographic experiments of Henry Brougham

Abstract

Of all the British claimants to the invention of photography, Henry Brougham is the one whose experiments have been given least attention in existing histories of photography. In his posthumously published three-volume autobiography of 1871, The Life and Times of Henry, Lord Brougham, written by himself, Brougham claimed to have engaged in some ‘experiments upon light and colours’ during the years 1794-–5 (when he was 16 years of age). He had, he tells us, included a discussion of his experiments in a paper offered to the Royal Society in 1795. Most of this paper, his first in the field of natural philosophy, was published in the Society's Philosophical Transactions (No. 86) of 1796 under the title ‘Experiments and observations on the inflection, reflection, and colours of light’. The paper, as published, was an attempt to discover analogous relationships between the bending of light within bodies (refraction or, using the 18th-century term, ‘refrangibility’) and the bending of light outside of bodies (reflection and diffraction or, in Brougham's terminology, flexion). As he wrote in the opening lines of his paper:

It has always appeared wonderful to me, since nature seems to delight in those close analogies which enable her to preserve simplicity and even uniformity in variety, that there should be no dispositions in the parts of light, with respect to inflection and reflection, analogous or similar to their different refrangibility. In order to ascertain the existence of such properties, I began a course of experiments and observations, a short account of which forms the substance of this paper.¹     

Variations in radioactivity of phosphate rocks from different sites in Central Eastern Desert of Upper Egypt

Natural radionuclides in the phosphate rock samples collected from Wadi Batur, Wadi Hegaza and Gabal Abu Had at Eastern Desert were determined using a high resolution 7-ray spectrometer. The experimental results concerning 226Ra, 232Th and their daughters are presented. Analyses of the measured spectra show that 226Ra is distinguished with remarkable activities with average values ranging from 22.4 to 558 Bq/kg, while 232Th activity concentration is in the range of 9.7 to 92.8 Bq/kg. The results of the analyses were found to be in a good agreement with the data obtained by others.     

An International Marine-Atmospheric 222Rn Measurement Intercomparison in Bermuda Part I: NIST Calibration and Methodology for Standardized Sample Additions

As part of an international ²²²Rn measurement intercomparison conducted at Bermuda in October 1991, NIST provided standardized sample additions of known, but undisclosed (“blind”) ²²²Rn concentrations that could be related to U.S. national standards. The standardized sample additions were obtained with a calibrated ²²⁶Ra source and a specially-designed manifold used to obtain well-known dilution factors from simultaneous flow-rate measurements. The additions were introduced over sampling periods of several hours (typically 4 h) into a common streamline on a sampling tower used by the participating laboratories for their measurements. The standardized ²²²Rn activity concentrations for the intercomparison ranged from approximately 2.5 Bq · m⁻³ to 35 Bq · m⁻³ (of which the lower end of this range approached concentration levels for ambient Bermudian air) and had overall uncertainties, approximating a 3 standard deviation uncertainty interval, of about 6 % to 13 %. This paper describes the calibration and methodology for the standardized sample additions.