透射电镜薄样品倾转过程中的附加旋转及其计算

模拟透射电镜双倾台进行样品位向调整过程,推导出反映样品倾转前后其合成倾转轴(即共有菊池线对的法线)方向变化规律的计算公式,称为附加旋转角计算公式。指出,实现样品位向调整的双倾操作,等效于样品绕其合成倾转轴的倾转及该倾转轴绕Z轴(平行入射束方向)的旋转之和。利用双倾台对薄膜样品进行的系列倾转实验表明,由附加旋转角公式计算的附加旋转角和实测值相一致。还根据双倾操作过程导出了合成倾转角的计算公式,它可用于判断样品位向调整的准确度。     

无机含氧酸的强度与結构的关系

1.提出计算无机含氧酸的pK值的经验公式。计算结果与实验值极为接近。 2.由于公式中包含有各项结构因素如电负性值、配键、双键、OH基、已电离的OH基等。讨论了各项因素对酸性强度的影响,并计算出其影响的大小。 3.还计算了一般在前人无法计算的OH,H_2O,H_2O_2,H_2S_2O_3,H_2N_2O_2,H_2CrO_4,HSO_3Cl的pK值。 4.提供计算3价金属离子水解及其氢氧化物酸式电离的pK值的经验公式,计算结果与实验值非常接近。也讨论了结构因素对酸性强度的影响。     

重金属氟化玻璃的光学特性研究

介绍含有镧、铈、铪、锆等重金属氟化玻璃（HMF）的光学性质。光激发荧光的测量是在含有不同浓度金属铈（5%及8%）的氟化玻璃中进行的。在氟环境中,这种玻璃表现出很强的激发特性和发射荧光光谱。在激发光波长为290 nm 时,样品光谱峰值较宽并位于310 nm处。相同元素构成的样品都有几乎相同的光谱,只有当玻璃中用锆代替铪时,其出射光强相当小。折射实验表明,含有铪、镧、铈的样品折射率都很低。同时还观察到,相同组分的氟化玻璃其折射率完全相同,而组分不同就能观察到折射率较大的变化。折射实验数据均采用Sellmeier公式进行了曲线拟合。阿贝数是在含有铈和镧的样品中测量并计算出结果。     

OCS电子基态势能面与振动光谱的理论研究

本文采用键长-键角内标系下的自洽场-组态相互作用方法精确计算了OCS分子的振动高激发态能级,并结合实验观测到的振动能级利用非线性最小二乘法优化电子基态势能函数中的势能参数。由优化所得的势能面计算出的振动激发态能级与50个实验观测到的振动能级比较,标准偏差为0.08cm^-^1。此外,还用该势能面计算了OCS同位素分子的振动能级,计算结果与实验值也十分吻合。     

X射线荧光光谱法在电气石标准物质均匀性检验中的应用

采用粉末压片–X射线荧光光谱法对电气石标准物质候选物的均匀性进行检验。选择Si,Al,Mg,Fe,Ca,Na等6个元素作为检验元素,样品以随机方式进行测量,根据单因素方差分析的F值和测定值的相对标准偏差(RSD)判定样品的均匀性,并计算了检测方法的误差和样品不均匀误差。结果表明,方差检验的F计算值在0.80~1.93之间,小于F临界值1.96,测定结果的相对标准偏差小于0.9%;检测方法相对标准偏差和样品不均匀度(以RSD表示)均小于0.5%,说明制备的电气石标准物质候选物具有良好的均匀性。通过公式计算,确定最小取样量为200 mg。该方法无需湿法分解样品,绿色环保,简便快速,测定结果精密度高。     

基于激光三维扫描的gamma谱仪无源效率刻度方法的应用技术研究

对基于激光三维扫描的谱无源效率刻度方法在分析不同密度和形状样品的应用开展了研究。首先利用点源对高纯锗探测器进行表征,应用激光三维扫描仪对不同容器扫描建模,在无源效率刻度软件中调用相应的参数库和样品相应形状的三维模型,采用数值积分方法计算出不同能量下的探测效率。在几种不同形状的容器中装入已知放射性活度的样品,在被表征的高纯锗谱仪上进行测量,应用计算出的效率值分别处理分析得出样品中所含标准物质的活度值。结果表明在分析天然放射性核素时,测量值与标准物质证书给定值相对偏差不大于10%。因此,基于激光三维扫描的谱无源效率刻度方法,在可接受的测量不确定度下,现实工作中可用于不能被破坏、不规则样品的测量分析工作中。     

(Nd,Pr)12.8Dy0.2Fe77.4Co4B5.6铸锭PPMS和DSC居里温度测量比较研究

为充分拓展DSC测量功能、探寻居里温度的简便测量方法、尤其是探寻高温居里温度的耐久测量方法,对真空电弧熔炼(Nd,Pr)12.8Dy0.2Fe77.4Co4B5.6铸锭,先通过PPMS测量升温速率3 K·min-1时样品的M-T曲线,并用外推法得到居里温度为648.3 K;然后采用DSC分别以3,10,20,30,40 K·min-1速率测量样品的升、降温曲线,分析升、降温曲线上对应吸、放热峰的起始点、峰值、终止点的特征温度值;再分别用最小二乘法拟合特征温度与升降温速率的直线方程,计算升降温速率分别为0和3 K·min-1时特征温度值,并与PPMS测量的居里温度值进行比较。结果表明:由DSC升温曲线起始点的特征温度拟合直线方程计算的升温速率为3 K·min-1的特征温度值为649.1 K,与PPMS外推法得到的居里温度相对差值最小为0.12%,具有足够的精确度。     

1-甲基-3,5-二苯基-吡唑的低温热容和热力学性质

通过精密自动绝热热量计测量了自己合成并提纯1-甲基-3,5-二苯基-吡唑在78～370K温区的摩尔热容。实验结果表明,这个化合物有一个固-液熔化相变,其熔化温度、摩尔熔化焓以及摩尔熔化熵分别为：(332.903±0.152)K,(17463.48±21.81)J·mol^-1和(52.55±0.06)J·mol^-1·K^-1。通过分步熔化法得到样品的纯度和绝对纯样品熔点分别为：0.9954(摩尔分数)和333.115K。在热容测量的基础上计算出了该物质每隔5K的热力学函数值。用DSC技术对该物质的固液熔化过程作了进一步研究,结果与热容实验相一致。     

计算脂肪族胺、醇和醚的气相碱性的经验公式

本文给出计算脂肪族胺、醇和醚气相碱性的经验公式。由公式得出的PA值与ICR实验值接近。     

脂肪酮和脂肪酰卤羰基17O-NMR化学位移的规律

提出计算脂肪酮和脂肪酰卤羰基17O-NMR化学位移的公式:δcal=δOn+Δα+C,通过线性回归法确定了22种取代基参数.经回归检验表明该公式计算结果置信度为99.5%,与实验值的偏差Δδ在10.0以内的羰基17O-NMR化学位移计算值在90%左右.     

最近十年中国头发微量元素研究进展

2006—2015年,是中国头发微量元素研究继续取得重要成果的10年,也是该项研究量质转变的10年。概述了10年内中国头发微量元素研究的进展、现状和发展方向,高通量微量元素组学研究和微量微区分析技术的发展将引领头发微量元素研究领域走向新的高度。     

Etude des transitions de phases du Stearate de lithium: Influence de l'histoire thermique

The phase transitions of lithium stearate have been studied by differential scanning calorimetry and the observation of thin foils under polarized light. A new phase has been demonstrated. The phase transition temperatures and enthalpies have been measured and the dependence of some of them on the earlier cycle characteristics (number, maximum temperature and temperature rate) is demonstrated.     

Monte Carlo transport of electrons and positrons through thin foils

In measurements on electrons traversing matter it is important to know the transmission through that medium, their path-lengths and their angular distribution through matter. This allows one to seek improvement in techniques which employ electrons, including medical applications and materials irradiation. This work presents a simulation of the transport of beams of electrons and positrons through thin foils using an analog Monte Carlo code that simulates in a detailed way every electron movement or interaction in matter. As those particles penetrate thin absorbers, it has been assumed that they interact with matter only through elastic scattering, with negligible energy loss. This type of interaction has been described quite precisely because its angular form influences very much the angular distribution of electrons and positrons in matter. With this code it has been calculated that the number of particles, with energies between 100 and 3000 keV, which are transmitted through different media of various thicknesses as well as their angular distributions, show good agreement with the experimental data. The discrepancies are less than 5% for thicknesses lower than about 30% of the corresponding range in the tested material. As elastic scattering is very anisotropic, its angular distribution resembles a collimated incident beam for very thin foils, becoming slowly more isotropic when absorber thickness is increased.     

Trace Analysis in Industrial Research

Abstract

Public concern and legislative regulations governing environmental pollution have had a dramatic effect on chemists involved in industrial research. The need to establish both the presence and amounts of trace levels of pollutants in industrial products and wastes has become imperative. Since time and cost become important considerations in such analytical determinations, it is apparent that sensitive, rapid and reliable methods of trace analysis are required. Many experimental techniques have been employed to this end and active research programs exist to develop new techniques to make such analysis more efficient.

Techniques capable of determining many elements in a single examination of a sample are of particular interest. No single 'black box' approach is, or is likely to become, feasible for all species of interest. Nonetheless, certain multielement approaches provide adequate information on some species and also provide important guidelines on the determination of other species by more specialized techniques. Problems encountered and progress achieved by the application of various spectroscopic, chromatographic, electrochemical and chemical methods to the trace analysis of industrial materials will be discussed.     

浊点萃取-分光光度法测定自来水及酒类样品中的痕量铁

利用非离子表面活性剂TritonX-100在温度高于其浊点时形成相分离行为,建立了浊点萃取-分光光度法测定痕量铁的新方法,探讨优化了以KSCN为显色剂,TritonX-100浊点萃取富集痕量铁的实验条件.研究发现:加入正辛醇可使TritonX-100的浊点降低约30℃,有利于萃取实验的进行;同时,加入的正辛醇与TritonX-100对痕量铁起到了协同萃取作用.在优化了的实验条件下,进行了痕量铁的分析,检出限为0.02mg·L-1,加标回收率为97.4%～101.6%,应用于自来水及酒类样品中痕量铁的测定,结果满意.     

基于有机光电材料的痕量爆炸物识别

随着国际恐怖袭击事件的增多,痕量爆炸物的识别技术研究越来越为重要.本文以作者在该领域的研究为例,综述了基于一维有机纳米材料、荧光金属配位聚合物(金属-有机框架化合物)和聚噻咯的荧光猝灭技术,在痕量爆炸物识别上的应用.同时介绍了酞菁薄膜和苝亚酰胺纳米线制备的电子传感器分别对过氧化物和硝基类爆炸物有灵敏的响应.     

Measurement of trace element concentration in a metal matrix using total reflection X-ray fluorescence spectrometry

Total reflection X-ray fluorescence spectroscopy (TXRF) has been used in combination with synchrotron radiation in order to determine detection limits and lowest limits of concentration of trace elements in metal matrices. Two applications on irradiated material are described, where the TXRF method has some advantages, as compared to other detection methods, because only few micrograms of material is needed for the measurements. The first application is devoted to radiation damage studies on first wall material of future fusion reactors. Therefore, metal foils were irradiated with 590 MeV protons at PSI and the transmutational elements produced in the foils were measured. The second application is the assessment of radiation damage of core components in a nuclear power plant, e.g. the reactor pressure vessel. This is performed by the determination of the fast neutron fluence on the components using an activation reaction of ⁹³Nb which is a trace element in most reactor steels. Detection limits of a few picograms have been found in the experiments.     

微量元素与糖尿病

糖尿病是一种常见病。成人糖尿病患病率约为３％,亦即现有糖尿病人达１亿左右。估计到２０１０年,全球糖尿病人将超过２亿。糖尿病的发展涉及多种病理过程,已有令人信服的证据表明,微量元素在胰岛素的生成和作用以及糖尿病人的能量底物代谢中起着极为重要的作用。本文从糖尿病行病学、微量元素在胰岛素代谢中的作用、糖尿病人的微量元素含量变化和糖尿病的微量元素治疗等四个方面综述了微量元素与糖尿病的关系。参考文献７０,表     

A simple and high sensitive spectrophotometric method for ultra trace determination of ruthenium with its catalytic effect on the oxidation of pyronin B by periodate

A new simple, selective, high sensitive and rapid method has been developed for spectrophotometric determination of ultra trace amounts of ruthenium based on its catalytic effect on the oxidation of pyronin B by periodate at lambdamax=555 nm. The described method is able to quantify ruthenium in the range of 0.1-100 ng ml-1 (r=0.9973), with a detection limit (S/N=3) of 0.036 ng ml-1. Under optimum conditions, this procedure has been successfully applied to determine the trace levels of ruthenium in the environmental and biological samples. The precision, expressed as relative standard deviation of three measurements, is better than 2.44%.     

Quantitative comparison of preparation methodologies for x-ray fluorescence microscopy of brain tissue

X-ray fluorescence microscopy (XFM) facilitates high-sensitivity quantitative imaging of trace metals at high spatial resolution over large sample areas and can be applied to a diverse range of biological samples. Accurate determination of elemental content from recorded spectra requires proper calibration of the XFM instrument under the relevant operating conditions. Here, we describe the manufacture, characterization, and utilization of multi-element thin-film reference foils for use in calibration of XFM measurements of biological and other specimens. We have used these internal standards to assess the two-dimensional distribution of trace metals in a thin tissue section of a rat hippocampus. The data used in this study was acquired at the XFM beamline of the Australian Synchrotron using a new 384-element array detector (Maia) and at beamline 2-ID-E at the Advanced Photon Source. Post-processing of samples by different fixation techniques was investigated, with the conclusion that differences in solvent type and sample handling can significantly alter elemental content. The present study highlights the quantitative capability, high statistical power, and versatility of the XFM technique for mapping trace metals in biological samples, e.g., brain tissue samples in order to help understand neurological processes, especially when implemented in conjunction with a high-performance detector such as Maia.