植物菘蓝稳定碳同位素组成与生态因子的关系

采用气体同位素质谱法,对植物菘蓝的根和叶以及种植地土壤中稳定碳同位素组成进行了测定。在此基础上,通过相关回归分析考察了植物菘蓝的根和叶以及种植地土壤中稳定碳同位素与种植地的地理位置因子和气象因子的相关性。结果表明,菘蓝根中稳定碳同位素组成与纬度、经度、平均气压、最高气压、最低气压、相对湿度、降水量、日平均地温、日最高地温、日最低地温和日照时数不具有相关性,与海拔、平均气温、最高气温、最低气温有低度相关性;菘蓝叶中稳定碳同位素组成与经度、平均气压、最高气压、最低气压、相对湿度、降水量、日最高地温不具有相关性,与海拔和日照时数具有低度相关性,与纬度、平均气温、最高气温、最低气温、日平均地温、日最低地温具有中度相关性;种植地土壤与海拔、平均气温、最高气温、平均气压、最高气压、最低气压、相对湿度、降水量、日平均地温、日最高地温不具有相关性,与纬度、经度、最低气温、日最低地温和日照时数具有低度相关性。本研究成果为植物中碳同位素分馏作用的研究和稳定碳同位素作为植物菘蓝产地溯源的指标提供了理论依据。     

稳定同位素技术在中药产地溯源方面的应用研究进展

中药的产地溯源在保证中药品质及疗效、维护市场秩序、降低由于假冒中药材引发医疗事故的风险等方面具有重要的作用。稳定同位素技术作为产地溯源的有效技术之一,对中药进行产地溯源具有理论基础及技术优势,近年来也被广泛应用于部分名贵中药的产地溯源。本文简要介绍了稳定同位素技术的基本原理,着重阐述了中药产地溯源中常用的同位素指标,并对近年来中药稳定同位素产地溯源的研究现状进行了总结与展望。旨在推动稳定同位素技术在中药产地溯源中的广泛应用,促进中药稳定同位素数据库及中药溯源技术体系的建立和完善。     

不同生境红树林青蟹的稳定同位素组成及其产地溯源意义

采用同位素比率质谱仪测定了野生和人工养殖的红树林青蟹(scylla paramamosain)的碳、氮稳定同位素组成,探讨了利用稳定同位素技术辨识野生和人工养殖青蟹的可行性。结果显示,红树林青蟹的碳、氮同位素组成主要受组织的有机物组成、代谢特征以及生境的食物组成控制,但与个体(或年龄)大小无关。排除一些特例后,人工养殖的红树林青蟹的碳、氮同位素组成明显不同于野生青蟹,利用稳定同位素技术可为区分红树林青蟹的不同产地提供科学参数。     

基于稳定同位素比率差异的西湖龙井茶产地溯源分析

通过测定不同产区扁形茶稳定同位素比率,借助化学计量学工具探索建立西湖龙井茶产地区分模型。从山东、四川、浙江、贵州等扁形茶主产区代表性取样,采用稳定同位素质谱测定样品中碳、氢、氧、氮、锶、铅、镉稳定同位素比率,对其进行方差分析,采用逐步线性判别（FLDA）、决策树C5.0和神经网络方法构建模型进行产地区分。结果表明,不同产地扁形茶中稳定同位素比率表现出产地差异。δD、δ¹⁸O受陆地效应和高程效应影响较大,并且二者有较好的正相关关系,⁸⁸Sr/⁸⁶Sr比值随地区纬度增加而增大,在不同产地扁形茶间差异尤为显著。FLDA和BP-ANN模型对外部样本的预测能力相对较差,分别为76%和84%;决策树算法模型回代验证准确率为91.35%,对外部样本的预测准确度达到92%。结果表明,在西湖龙井茶产地判别中,采用基于稳定同位素比率的决策树算法模型可取得较好的效果。     

稳定同位素技术在我国食品安全检测领域的应用进展

为了深入了解稳定同位素技术在近十多年来食品安全领域的应用热点,本文着重关注国内科研领域的相关研究,从稳定同位素比值测定在食品溯源技术中的应用、稳定同位素技术在食品真实属性鉴别中的应用、稳定同位素内标试剂与同位素稀释质谱法结合的检测技术在食品中有害物质检测中的应用等三个方面综述了稳定同位素在食品安全领域的快速发展及已经形成规范的技术水平。随着稳定同位素技术的发展及数据库的积累,相关理论不断完善,其必将在食品安全领域成为至关重要的应用技术之一。     

重水中氢氧同位素的质谱分析

用高分辨率质谱计分析了重水中氢与氧的同位素组成；分析了重水的分子组成、质谱中的单电荷离子；利用高分辨率质谱峰相对强度，计算了重水中的氢氧同位素组成。结果表明，高分辨率质谱法分析重水，可同时分析其中的氢同位素和氧同位素，并且用样量小，结果可靠。     

诸广南棉花坑铀矿床热液蚀变伊利石矿物学和稳定同位素特征

为了探究诸广南长江地区的黏土蚀变特征,在对棉花坑矿床开展野外工作和室内镜下观察的基础上,利用X射线粉晶衍射、氢氧同位素测试等方法对棉花坑铀矿床的热液蚀变伊利石进行了分析研究。伊利石的产出形式分为碎裂充填型、长石原位蚀变型和构造脉型三种,结晶度平均值分别为0.336、0.315和0.395,伊利石结晶受水/岩比和温度共同限制。伊利石的δ~(18)Ο值在0.4‰～9.1‰,δD在-92.4‰～-73.7‰。根据稳定同位素测试和计算,得出形成伊利石流体中水的氧同位素特征和前人研究中成矿晚期流体中水的氧同位素特征一致,同时根据计算所得伊利石形成温度在50～170°C,与成矿晚期流体温度一致;根据形成伊利石的流体中水的氢氧同位素投图可知其流体来源主要为大气降水,与成矿晚期流体来源一致,因此认为伊利石是棉花坑铀矿床成矿晚期特征蚀变矿物。     

稳定同位素技术在牛奶及奶制品溯源应用中的研究进展

本文针对市场上奶制品标签混乱、普通乳制品冒充有机乳制品、复原乳冒充鲜乳等问题,介绍了稳定同位素技术在牛奶及奶制品可追溯性的国内外研究进展,对使用该技术对牛奶及奶制品溯源提出了几点建议,对未来牛奶及奶制品产地溯源进行了展望,以期对稳定同位素技术在牛奶及奶制品研究工作的不断深入及食品溯源系统的不断完善提供帮助。     

铅同位素组成在古陶产地判别中的应用

对铅同位素组成在鉴别古陶产地上的应用进行了探讨。对采自于河南省贾湖和西山两新石器时代遗址的古陶样品进行了铅同位素组成分析，大部分贾湖样品的铅同位素原子数比^206Pb／^204Pb为18．0—18．4，^208Pb／^204Pb为38．4—38．8，而大部分西山样品的铅同位素原子数比。^206Pb／^204Pb为18．6—18．8，^208Pb／^204Pb为38．7—39．1。因此，对某些产地的古陶，铅同位素组成是鉴别其产地的有力工具。     

乳制品掺假现状与稳定同位素鉴别技术研究进展

乳品掺假鉴别是目前我国乳品质量控制的难题之一,相关部门特别是进口监管部门急需快速且准确鉴别乳制品掺假以及原产地来源的新技术和方法。本文综述我国乳制品掺假现状,总结掺假乳制品的常见鉴别技术,重点阐述目前国内外稳定同位素技术在乳制品真实性鉴别研究中的进展,主要介绍C、H、O、N和S稳定同位素的相关应用,并指出该技术在乳品掺假鉴别和产地溯源中的技术优势、存在的问题以及未来发展的方向。     

水平衡法与高温转化法在矿泉水氢氧稳定同位素测定中的应用

为了鉴别不同品牌矿泉水标注水源地信息真伪,对11种不同品牌饮用水的氢氧稳定同位素(δD和δ¹⁸O)进行测定。结果表明,水平衡法(GasBench-IRMS)和高温转化法(TC/EA-IRMS)的测定结果一致性较好,两种方法测定6种不同饮用水的δD和δ¹⁸O的平均差异分别为(0.6±1.59)‰和(0.02±0.13)‰。水平衡法需要较长的制备和测定时间,但δD和δ¹⁸O的测定精度明显优于高温转化法。11种饮用水δD和δ¹⁸O变化范围较大,其δD和δ¹⁸O受不同品牌饮用水的水源地降水影响形成明显的地域性。虽然无法区分矿泉水是否由其他类别饮用水伪造,但δD和δ¹⁸O可以为特定区域(如高海拔与沿海地区)以及产地相近的矿泉水水源地鉴别提供依据。     

Determination of O concentrations in musamples of biological fluids

The ¹⁸O(p, )¹⁵N reaction has been developed for the analysis of musamples of biological fluids containing ¹⁸O-enriched water. Samples as small as 50 μl have been used. Well characterized Ta₂O₅ targets were prepared from these fluids and irradiated with several hundred nA of protons from the 3 MV Van de Graaff at Lucas Heights. The broad (47 keV) 846 kV resonance in this reaction was used to measure ¹⁸O concentrations down to natural backgrounds (0.2 at.%) in a few minutes of accelerator running time. Concentrations of ¹⁸O from 0 to 5 at.% were measured in body fluids in small Australian lizards directly after doping with ¹⁸O-enriched water and then again after several days of roaming around in their natural desert environments. The changes in these levels were related to the metabolic rates of these animals.     

Pollution assessment in the Trancão river basin (Portugal) by PIXE, EDXRF and isotopic analysis

This paper reports on the inorganic contamination assessment of a river basin and local water resources in order to establish quality standards. PIXE was applied to the elemental determination of the freeze-dried water dry residue and EDXRF was used for the evaluation of elemental content of sediments. To infer the water provenance the electrical conductivity was measured as well as the isotopic composition of surface waters using the ¹⁸O/¹⁶O ratio. The combined isotopic and elemental composition information enables to establish dominant contamination contributions from the several tributaries. Moreover, the variability observed for certain parameters, associates them with specific basin regions as for instance, dry residue mass, conductivity and Br, or S, Cl and As or Cr, Ni, Zn and Pb which permit to establish both pollution characterisation and their origin (agriculture, industrial, etc.). At certain locations, enhanced concentrations of elements as Cr, Cu, Zn and Pb are observed both in sediments and in the surface water. The elemental particular associations also permit to characterise pollution sources.     

Charged-particle activation methods for the analysis of carbon and oxygen in high-purity gallium

Methods for the instrumental analysis of C and O at trace level in high-purity gallium were developed. The ¹²C (d, n)¹³N and ¹⁶O(t, n)¹⁸F reactions were used between 2.5 and 3.5 MeV, allowing analyses down to tens of ppb/weight. The ¹⁶O(p, )¹³N reaction at 15 MeV was also used; in this case ¹³N has to be separated radiochemically.     

恒星中子源~(13)C(α,n)~(16)O反应的研究

13 C(α,n)16 O是渐进巨星支(AGB)星中慢速中子俘获(s)过程的主中子源反应,而17 O 6.356 MeV1/2+阈下共振对13 C(α,n)16 O反应影响很大。本文使用HI-13串列加速器和Q3D磁谱仪,首次测量了13C(11B,7Li)17 O转移反应角分布,确定了影响13C(α,n)16 O反应最关键、最不确定的17 O(Ex=6.356MeV)阈下共振态的α宽度,从而得出天体物理能区13 C(α,n)16 O反应的天体物理S因子和反应率,澄清了国际上已有S因子数据间高达25倍的巨大分歧。AGB星s过程核合成网络计算表明:新反应率数据导致恒星中铅的丰度增加了25%。     

Radiation damage factor for ion-implanted silicon detectorsirradiated with heavy ions

Ion-implanted silicon detectors were irradiated with 18-150 MeV ¹⁶O, 20 MeV ⁴⁰Ar, and 53 MeV ¹¹⁰Xe. A linear increase of the leakage current was observed as a function of the particle fluence up to 2.2×10⁸ cm^-2. Extracted damage factors are proportional to the averaged nuclear stopping power over five orders of magnitude covering heavy ions studied in the present work and also protons of 25-800 MeV energies     

锦屏深地核天体物理实验(JUNA)进展

锦屏深地核天体物理实验（JUNA）项目将利用中国锦屏深地实验室（CJPL）的良好条件,在天体物理伽莫夫能量窗口开展核天体关键反应²⁵Mg(p,γ)²⁶Al、¹⁹F(p,α)¹⁶O、¹³C(α,n)¹⁶O和¹²C(α,γ)¹⁶O的直接测量。目前已成功完成400 kV强流加速器和ECR离子源的研发,获得了400 keV、10 mA的质子束流和一价氦离子束流及800 keV、2 mA二价氦离子束流。大功率固体靶的研制及实验数据获取系统的建立也已成功完成。超低本底快中子探测器、4π BGO探测器阵列以及大立体角带电粒子探测器阵列已研制组装完成,并测量了地面和锦屏地下实验室的本底水平。总体来说,JUNA项目整体进展顺利,完成了中期设立的目标并通过了基金委评估（A级）和国际评估。     

Low energy radioactive beams by inversion kinematics

Kinematically focussed radioactive beams of energies lower than 10 MeV/nucleon were produced by means of inversion kinematic in heavy ion induced reactions on ¹H. The characteristics of the produced radioactive beam were examined with the view of performing scattering and reaction experiments. On the basis of these results, a new beamline was constructed to collect and focus the radioactive beams. Using this beamline the elastically scattered spectra of ¹⁵O obtained from the ¹H(¹⁵N, ¹⁵O) reaction were observed with an energy resolution better than 0.6 MeV.     

Assessment of pulse height defect in passivated implanted planar Si detectors used for channeling measurements with slow, highly charged heavy projectiles

The pulse height defect (PHD) of slow, highly charged ¹²C, ¹⁶O, ⁴⁰Ar and ⁸⁴Kr ions in a passivated implanted silicon detector has been measured. The detector is part of the channeling setup at the Frankfurt ECR/RFQ installation for beams of highly charged ions. In this experiment the modification of the charge states under channeling conditions in thin silicon membranes is measured. The charge states of the scattered ions are separated by post-acceleration. The PHD is an important input for the energy calibration. It allows the analysis via a parametrization which relates it to the true energy and the order number of the ions through a simple power law.