同位素源激发X-射线荧光分析合金样品的吸收-增强效应的数学校正—基本参数法

本文叙述了利用基本参数法校正源激发合金元素荧光分析的基体效应的基本原理、基体效应的修正方法。讨论了当激发源的能量比元素的吸收限大很多时,吸收系数的散射修正,利用~(241)Am源激发,测量了铅锡合金和高合金钢样品中各元素的荧光强度,并用自编数据处理程序计算了元素含量,结果与标准含量进行比较。计算含量误差一般小于10％。     

合金电子谱定量分析中离子溅射修正因子的研究

离子溅射修正是电子谱(俄歇电子谱,AES和X射线光电子谱,XPS)、离子谱(二次离子质谱,SIMS和低能离子散射谱,ISS)定量分析中的关键问题之一。本文根据作者最近提出的离子轰击合金表面成分再分布关系,得到了表面分析中离子溅射修正因子的分析表达式,总结了近十多年来合金离子溅射修正因子的一些较普遍的实验结果,用本文报道的计算关系较好地解释了这些实验结果。讨论了溅射修正因子受轰击离子参数(入射角、能量)、组分浓度等因素的影响。同时用本文给出的分析计算关系讨论了择优溅射、离子辐照诱导偏析和增强扩散效应对溅射修正因子的影响。     

高纯氧化钇电感耦合等离子体原子发射光谱分析中的校正因子法初步研究

本文提出用校正因子法补偿基体效应对待测元素谱线强度的影响。考察了ICP工作参数对校正因子的影响,在优化的条件下,14个稀土元素的校正因子值为1.10～1.40,其波动系数<7.5％。对高纯氧化钇试样进行了分析,并将所得结果同基体匹配法作了比较,分析误差基本符合痕量分析要求。本法的优点是省去了基体匹配,这对高纯稀土分析有一定参考价值。     

ICP-AES法测定高合金钢中主合金元素含量

利用全谱直读ICP－AES（CID检测器）分析技术，通过对试样溶解方法，元素分析谱线和背景校正扣除，仪器分析参数等因素进行了试验研究，综合确定了最佳试验条件，并采用元素多谱线平均值法对高合金钢中主合金元素进行了光谱分析。结果表明，方法测定高合金钢中主合金元素的准确度和精密度符合国家标准中允许误差的要求，可用于日常材质的检验。     

X 射线荧光光谱法测定铀矿石中的铁、钛、钙、硫、磷、硅、铝和铀——两步校正程序初探

本工作采用X射线荧光光谱法对含铀硅酸盐、磷酸盐和碳酸盐矿石样品中的铁、钛、钙、硫、磷、硅、铝和铀的分析进行了研究,对基体效应采用散射内标法-经验系数法两步校正程序分析了样品中的铁和铀,其余元素只作后一步校正,实验结果表明,本法可以较好地应用于矿样中含量范围较宽的主元素的分析。前言在X射线光谱分析时,为了克服基体效应对分析结果的影响有多种方法,其中以经验系数法研究和应用的最多,日本钢铁研究所提出的数学校正模型是其中应用较多的一种,     

镧与Sn-Pb合金体系中组元的相互作用关系

采用二元系Ｍｉｅｄｅｍａ生成热模型及其Ｔａｎａｋａ过乘熵修正和三元系Ｃｈｏｕ几何模型分析了稀土元素Ｌａ与Ｓｎ－Ｐｂ软钎料合金体系中组元元素的相互作用关系,热力学计算表明,在Ｓｎ－Ｐｂ合金体系中,Ｌａ具有“亲Ｓｎ”倾向。这是添加稀土元素Ｓｎ－Ｐｂ软钎料合金金属学性能的一个基本前提 。     

达乌里秦艽化学元素特征及其与环境关系

应用全谱直读等离子体发射光谱法（ICP—AES）对不同居群达乌里秦艽（Gentiana dahurica Fischer）中15种元素含量进行了测定,通过聚类分析和主成分分析探讨了其化学元素特征及与生态环境的关系,为深入认识该药材的元素特征及其功效提供参考。结果表明,达乌里秦艽药用部位元素含量较丰富,以大量元素K,Ca和Mg含量较高。不同居群元素含量水平显示出地理分布差异特点;且各元素之间具一定的协调促进或拮抗作用,这种作用在聚类分析中再次得到证明;主成分分析的结果表明,其元素特征可用“代谢增强”作用因子和“酶活促进”作用因子来体现。海拔对两个因子有正向促进作用;经纬度则对前者具负向影响,对后者具正向影响。     

全谱拟合定量分析方法及其影响因素的研究

为研究全谱拟合定量分析方法,将此定量分析方法与内标法、K值法、绝热法进行对比分析,主要讨论了图谱的收集方式、拟合过程中所用的峰形函数,以及温度因子对全谱拟合定量分析结果的影响。结果表明,相对其他定量方法,全谱拟合定量分析只需知物相的结构信息,无需标样,具有较高的准确性。另外,衍射角的收集范围通常与被测试样材料有关,一般扫描范围包括待测试样的主要衍射峰区域即可;步长越小,每步扫描时间越长,衍射强度高,拟合因子越小,计算图谱与实测图谱吻合程度越好;基本参数法通过已知实验仪器的几何参数计算出仪器的仪器峰形,可简化精修过程,减少人为误差;选用结构数据库中的结构信息进行的拟合定量,得到的拟合因子最小,拟合结果最好;拟合过程中修正阳离子的温度因子比修正氧离子的温度因子得到的拟合因子小,拟合定量结果较好一些。     

ICP–AES测定铌铪合金中的铪、钛、锆、钨、钽

采用氢氟酸–硝酸溶解铌铪合金样品,建立电感耦合等离子体原子发射光谱法(ICP–AES)测定铌铪合金中铪、钛、锆、钨、钽元素的分析方法。铪、钛、锆、钨、钽的分析谱线分别为232.247,368.519,339.197,224.876,248.870nm,通过基体匹配法消除基体铌的干扰。在优化条件下对铌铪合金样品进行测定,各元素的质量浓度在其线性范围内与其光谱强度呈良好的线性关系,线性相关系数大于0.998,定量限为0.003 6%~0.007 4%。测定结果的相对标准偏差(n=11)小于1%,回收率为96.8%~105.0%。该方法快速、准确,可以满足实际生产中铌铪合金样品的测定要求。     

电感耦合等离子体质谱法测定镍基高温合金中10种元素

采用电感耦合等离子体质谱法测定镍基高温合金中锗、砷、钇、钌、铟、碲、铪、铂、金、汞等10种元素。样品以盐酸-硝酸混合酸溶解,并在完全溶解后滴加过氧化氢防止生成钨酸沉淀。在测定中采用基体匹配法和在线内标法校正基体效应和进样不均匀导致的信号扰动。待测元素的质谱干扰通过选择合适的同位素、加入元素修正方程和在测试中应用动能碰撞模式来进行消除。10种元素的检出限(3s)在0.002~0.65μg·g-1之间。应用此方法分析了3个标准样品(GBW01636,GBW 01638,GBW 01640),测定值与认定值相符,测定值的相对标准偏差(n=10)在0.60%~45%之间。     

An improvement of window factor analysis for resolution of noisy HPLC-DAD data

Window factor analysis (WFA) is a powerful tool in analyzing evolutionary process. However, it was found that window factor analysis is much sensitive to the noise involved in original data matrix. An error analysis was done with the fact that the concentration profiles resolved by the conventional window factor analysis are easily distorted by the noise reserved by the abstract factor analysis (AFA), and a modified algorithm for window factor analysis was proposed. Both simulated and experimental HPLC-DAD data were investigated by the conventional and the improved methods. Results show that the improved method can yield less noise-distorted concentration profiles than the conventional method, and the ability for resolution of noisy data sets can be greatly enhanced.     

CALCULATING THE MOLECULAR INTERNAL ROTATING STERIC FACTOR OF POLYMERS BY THE RADIATION CROSSLINKING METHOD

In this paper, calculating the molecular internal rotating steric factor of polymers by the radiation crosslinking method is studied and a relationship between the molecular internal rotating steric factor (σ) and crosslinking parameter βis established~([1]) by taking account of the effect of polymer chain flexibility on βvalue, σvalue of polymer obtained by this method is in agreement with that given with other method.     

Role of the one‐body Jastrow factor in the transcorrelated self‐consistent field equation

The one‐body Jastrow factor has been introduced into the transcorrelated variational Monte Carlo (TC‐VMC) method. The principal role of the one‐body Jastrow factor in the Jastrow–Slater‐type wave function is to prevent an unfavorable effect of the two‐body Jastrow factor that alters the charge density. In the TC‐VMC method, since the one‐body orbitals are optimized by the transcorrelated self‐consistent field (TC‐SCF) equations, which take into account the electron–electron correlation interactions originating from the two‐body Jastrow factor, the unfavorable effect of altering charge density can be avoided without introducing the one‐body Jastrow factor. However, it is found that it is still better to incorporate a one‐body Jastrow factor into the TC‐VMC method for the practical effect of reducing numerical errors caused by the Monte Carlo sampling and the re‐weighting calculations in solving the TC‐SCF equations. Moreover, since the one‐body Jastrow function adopted in the present work is constructed from the two‐body Jastrow factor without increasing any variational parameter, the computational cost is not significantly increased. The preferable effect of the use of the one‐body Jastrow factor in the TC‐VMC calculation is demonstrated for atoms. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

Theory of error applied to factor loadings resulting from combination target factor analysis

The theory of error for target factor analysis is used to derive a simple equation from which the root-mean-square error in the factor loadings can be calculated. The method is applied to a problem in gas—liquid chromatography and is shown to agree with errors estimated by the 'jackknife' method.     

Analysis of platelet-activating factor by gas chromatography-mass spectrometry: low-energy electron impact of the corresponding 3-acetyl-2-tert.-butyldimethylsilyl derivative.

A method for the analysis of platelet-activating factor in platelets employing gas chromatography and selected-ion monitoring mass spectrometry with low-energy electron impact and stable isotope dilution was developed. The procedure involved Bligh and Dyer extraction of the sample followed by thin-layer chromatographic purification. Platelet-activating factor is successively hydrolysed to the corresponding 2-acetyl-1-O-alkylglycerol by digestion with phospholipase C, and the product is allowed to isomerize to the more thermodynamically stable 3-acetyl-1-O-alkylglycerol before column purification and derivatization of the free OH with tert.-butyldimethylchlorosaline-imidazole. This reagent is of common use in platelet-activating factor derivatization, but is made to react with 2-acetyl instead of 3-acetyl isomer. The advantages of using the latter for the final derivatization are discussed and this method is compared with others currently available for gas chromatographic-mass spectrometric analysis of platelet-activating factor.     

Light scattering data evaluation using legendre polynomials

Calculation of the masses and the radii of gyration from static light scattering experiments were performed by approximating the measured angle distributions by Legendre polynomials. The method allows a very good fit to the scattering angle 0°. In this paper the method is discussed applied to discretised theoretical form factors of several geometries as well as measured data of latex particles. If the sample is polydisperse, the resulting form factor is the sum of the form factors of the individual particles. An iterative method was developed, that allows the deconvolution of form factors of spherical particles from the measured form factor to give information about the polydispersity of the sample. This form factor analysis will be discussed for experiments using asymmetrical Flow‐Field‐Flow‐Fractionation (a‐FFFF) of complex plant extracts to interpret the measured form factor as the superimposition of two possible elution modes of the a‐FFF.     

All-numerical noise filtering of fluorescence signals for achieving ultra-low limit of detection in biomedical applications

We present an all-numerical method for post-processing of the fluorescent signal as obtained from labeled molecules by capillary electrophoresis (CE) in an optofluidic chip, on the basis of data filtering in the Fourier domain. It is shown that the method outperforms the well-known lock-in amplification during experiments in the reduction of noise by a factor of (square root)2. The method is illustrated using experimental data obtained during CE separation of molecules from a commercial DNA ladder with 17 fluorescently labeled molecules having different base-pair sizes. An improvement in signal-to-noise ratio by a factor of ～10 is achieved, resulting in a record-low limit of detection of 210 fM.     

Replica-exchange extensions of simulated tempering method

In this paper we consider combinations of two well-known generalized-ensemble algorithms, namely, simulated tempering and replica-exchange method. We discuss two examples of such combinations. One is the replica-exchange simulated tempering and the other is the simulated tempering replica-exchange method. In the former method, a short replica-exchange simulation is first performed and the simulated tempering weight factor is obtained by the multiple-histogram reweighting techniques. This process of simulated tempering weight factor determination is faster and simpler than that in the usual iterative process. A long simulated tempering production run is then performed with this weight factor. The latter method is a further extension of the former in which a simulated tempering replica-exchange simulation is performed with a small number of replicas. These algorithms are particularly useful for studying frustrated systems with rough energy landscape. We give the formulations of these two methods in detail and demonstrate their effectiveness taking the example of the system of a 17-residue helical peptide.     

一种测定天然药物活性成分的HPLC-DAD计算分析方法

将窗口因子分析所得结果作为初值,采用交替迭代进行窗口的自适应优化调整,以迭代逼近方法有效地解决了窗口选择难题.将其用于丹参中丹参酮、隐丹参酮和丹参酮A含量的HPLC-DAD分析测定,加样回收率分别达94.16%,91.57%和104.48%.计算机仿真和模拟中药物质体系的实验结果均表明,本方法分析结果受窗口偏差的影响较小,显著优于经典窗口因子分析法,可推广用于计算解析复杂样品色谱分析中出现的重叠峰.     

Error estimates for factor loadings and scores obtained with target transformation factor analysis

Methods of calculating the errors associated with the reproduction of data from the results of target-transformation factor analysis are demonstrated. Errors in the factor loadings and scores are produced by two methods: the jack-knife method, which is time-consuming, and a faster calculation procedure. The agreement shown between the two methods demonstrates the effectiveness of the calculation approach as a quick and simple method of error estimation.