【作者】 董克君；

【导师】 姜山； 何明；

【作者基本信息】 中国原子能科学研究院 ， 粒子物理与原子核物理， 2003， 硕士

【摘要】 钙是人体中的重要元素，它对于维持人体各系统的正常功能具有重要作用。缺钙可能导致骨质疏松、动脉硬化等多种疾病。另外，Ca²⁺作为一种细胞信使在维持细胞正常变化中起着重要作用。人工合成的钙同位素⁴¹Ca(T_1／2=1.0×10⁵ a)是了解这些疾病机理以及Ca²⁺信使作用机理的理想示踪剂，但是只有当加速器质谱（AMS）法出现后，才实现了对⁴¹Ca的高灵敏测量。本文就是以此为出发点而开展的工作。 本工作是在国家自然科学基金支持下一项工作的重要组成部分，目标是建立HI-13串列AMS测定⁴¹Ca的理想方法。论文工作研究的主要内容包括：1)用于HI-13串列AMS测量的⁴¹Ca样品的制备。主要有标准样品、空白样品与生物样品三种。2)⁴¹Ca的AMS测量。也就是采用与标准样品对比的相对测量方法。已知样品中稳定同位素的量，通过测量⁴¹Ca与⁴⁰Ca比值就可以得到⁴¹Ca的含量。 文章系统阐述了样品制备装置的设计与建立。因为CaH₂样品的制备是本实验中的一个难点，其间涉及到氧化钙的高温还原与金属钙的氢化，两种反应都需要在特殊的装置中进行。论文工作在这方面投入了大量的时间与精力，并最终建立了一套完整的CaH₂样品制备装置，使氧化钙的还原与金属钙的氢化效率都在百分之九十以上，并多次成功地完成了极少量CaH₂样品（质量小于2mg）的制备工作。 AMS测量⁴¹Ca，其主要干扰本底来自于同量异位素⁴¹K，如何有效地排除⁴¹K的干扰并对⁴¹Ca进行鉴别是实现⁴¹Ca高灵敏度测量的关键。工作中选用CaH₂作为待测样品，大大地降低了同量异位素⁴¹K的干扰，使用多阳极电离室成功地对⁴¹Ca进行了鉴别，测量灵敏度达到了10^-14。文中将对这方面的内容做详细论述。 本研究工作的完成标志着我国在⁴¹Ca的研究方面又迈进了新的一步，尤其在生物医学方面。以⁴¹Ca作为示踪剂，测定细胞胞浆内Ca²⁺增加的来源，对于研究因致癌物引发癌症的机理具有重要的意义。此外，开展⁴¹Ca的示踪研究具有极其广泛的应用前景，在我国人体中存在普遍缺钙的情况下，它不仅能为研究人体钙的补充和防止体内钙的流失提供依据，更有助于了解因缺钙所致疾病的机理，找到预防与治疗的途径。更多还原

【Abstract】 Calcium is an important element in human body. It is known that calcium deficiency in human body is related to many diseases such as Osteoporosis, arteriosclerosis and so on. In addition, Ca2+, as a messenger, plays an important role in the normal function of cells. The man-made 41Ca (T1/2=1.0×105 a) is an ideal tracer in these studies. The high sensitivity of AMS has made it possible to determine trace amount of 41Ca.This work was supported by the National Natural Science Foundation. The goal is to develop an ideal 41Ca measurement method with HI-13 tandem AMS. The main topics of research presented in this thesis are as follows: the first is the AMS samples preparation of 41Ca. There are three kinds of samples: standard, blank and the unknown biological samples. The second is the 41Ca AMS measurement. The content of 41Ca in unknown sample can be obtained by measuring the 41Ca/40Ca ratio of the unknown and standard samples.The thesis systemically describes the apparatus of the preparation of CaH2. The sample preparation is very important. It involves the reduction of CaO at high temperature, and the generation of CaH2 from metallic Ca; the two procedures must be done in special equipments. So, lots of work have been done to design and test these equipments. Finally, the overall efficiency for Ca recovery is more than 90%, even for the mass of Ca sample as small as 2mg, or less.The 41K is the main interference in the measurement of 41Ca. By using CaH2 as ion source, the major interference from 41K can be largely reduced. 41Ca is successfully identified and finally quantified by using a multi-anode detector; in present work, the sensitivity for 41Ca measurement is 10"14.The completion of this work marked a major step forward in the applications of 41Ca in our country, especially in the field of biomedicine; 41Ca can be used as a tracer to investigate the origin of the increased Ca2+ in the cells blastula has very great significance for studying the mechanism of cancer caused by carcinogenic substances; 41Ca tracer may also make contribution in the study of the mechanism, possible prevention and treatment of acalcicosis, a disorder very popular in our country.更多还原