Experimental comparisons of statistical uncertainties in analysis of nuclear spectra with the Cambio software application

Cambio is a software application well-suited for analysis of high-resolution nuclear spectral data in which the critical information resides in well-masked peaks or in which the data are sparse and good statistics cannot be obtained. The statistical uncertainty in the results is reported in terms of standard deviations. In the practical use of any analysis application, it is important to have a good understanding of the accuracy of the reported statistical uncertainties in the results. The authors report the results of an experiment that provides a quantitative measure of the accuracy of the reported uncertainties in analyses using Cambio. Ten calibration sources ranging in activity from 25 to 450 kBq were placed 20.5 m from a bare, 100 % relative-efficient high-purity germanium detector. Peaks in these sources occur from 20 to 2,800 keV. Data were accumulated for 128 h to create a parent spectrum from which 1024 8-hour statistically-equivalent daughter spectra were created by random sampling of the parent spectrum data. The parent spectrum was analyzed by fitting parameters which included an underlying continuum, a background of natural peaks adjusted by detector efficiency and material attenuation, and a foreground of the ten sources adjusted by detector efficiency only. Each of the daughter spectra were then analyzed starting with the parameters of the fit to the parent spectrum and then minimizing Chi-square with respect to changes in these parameters. The standard deviations of the estimated activities of the sources from all 1024 spectra were then calculated and compared to the reported statistical uncertainty in the activities and peak areas of the sources.     

Resonance Rayleigh scattering spectra, non-linear scattering spectra of tetracaine hydrochloride-erythrosin system and its analytical application

The interaction between erythrosine (ET) and tetracaine hydrochloride (TA) was studied by resonance Rayleigh scattering (RRS), frequency doubling scattering (FDS) and second-order scattering (SOS) combining with absorption spectrum. In a weak acidic medium of Britton-Robinson (BR) buffer solution of pH 4.5, erythrosine reacted with tetracaine hydrochloride to form 1:1 ion-association complex. As a result, the new spectra of RRS, SOS and FDS appeared and their intensities enhanced greatly. The maximum peaks of RRS, SOS and FDS were at 342 nm, 680 nm and 380 nm, respectively. The intensities of the three scattering were directly proportional to the concentration of TA in the range of 0.008-4.2 microg mL(-1) for RRS, 0.027-4.2 microg mL(-1) for SOS and 0.041-4.2 microg mL(-1) for FDS. The methods had very high sensitivities and good selectivities, and the detection limits were 0.003 microg mL(-1) for RRS, 0.008 microg mL(-1) for SOS and 0.012 microg mL(-1) for FDS, respectively. Therefore, a new method was developed to determinate trace amounts of TA. The recovery for the determination of TA in blood serum and urine samples was between 97.0% and 103.8%. In this study, mean polarizability was calculated by AM1 quantum chemistry method. In addition, the reasons for the enhancement of scattering spectra and the energy transfer between absorption, fluorescence and RRS were discussed.     

Study on the resonance Rayleigh scattering spectra and resonance non-linear spectra of congo red-amikacin system and its analytical application

The interaction between congo red (CR) and amikacin (AMK) was studied by resonance Rayleigh scattering (RRS), frequency doubling scattering (FDS) and second-order scattering (SOS) combining with absorption spectrum. In a weak acidic medium, CR combined with AMK to form an ion association complex with the composition ratio of 1∶1 by electrostatic interaction, hydrophobicity and charge transferring effect. As a result, the new spectra of RRS, FDS, and SOS appeared and their intensities were enhanced greatly. The maximum wavelengths of RRS, FDS and SOS were located at 563 nm, 475 nm and 940 nm, and the scattering intensities were proportional to the concentration of AMK. These three methods have very high sensitivities, and the detection limits were 4.0 ng·mL?1 for RRS, 3.6 ng·mL?1 for FDS and 1.9 ng·mL?1 for SOS, respectively. At the same time, the methods have better selectivity. A new method for the determination of trace amounts of AMK with congo red by resonance scattering technique has been developed. The recovery for the determination of AMK in blood serum and urine sample was between 95.5% and 105.5%. In this study, the properties, such as enthalpy of formation, charge distribution and mean polarizability, were calculated by AM1 quantum chemistry method. In addition, the reaction mechanism and the reasons for the enhancement of scattering spectra were discussed.     

Resonance Rayleigh scattering spectra, non-linear scattering spectra of malachite green-12-tungstophosphoric acid system and its analytical application in fish

In 0.1 molL(-1) (pH 1.0) HCl medium, 12-tungstophosphoric acid (TP) reacted with malachite green (MG) to form an ion-association complex. As a result, the new spectra of RRS, SOS and FDS appeared and their intensities were enhanced greatly. The maximum wavelengths of RRS, SOS and FDS were located at 334 nm, 586 nm and 330 nm, and the scattering intensities were proportional to the concentration of MG. Based on it a new method for the determination of MG has been established. The detection limits (3σ) of these methods were in the range of 3.7-27 ng mL(-1). The RRS, SOS, and FDS characteristics, absorption spectrum characteristics and optimum reaction conditions of the system were discussed. Effects of coexistent substances were tested, and the results demonstrated that this method had good selectivity. It has been applied to the determination of malachite green residues in fish flesh with satisfactory results. The reaction mechanism and reasons of RRS enhancement are discussed.     

Analytical parameter estimation by a general non-linear regression software package with user-defined mathematical model implementation

Summary A general purpose non-linear regression program is presented, particularly allowing an easy implementation of user-defined models of analytical signals and responses. Considerations about using non-linear regression in practice are made. The structure of the program is explained. The different modules show the convenient use of the package. Some typical applications of the method with different mathematical models are shown.

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Bestimmung von analytischen Parametern durch ein Programmpaket basierend auf nicht-linearen Regressionen und einem Benutzer-definierten mathematischen Modell

     

Fingerprinting of ivory and horn through the application of nuclear analytical techniques

The feasibility of fingerprinting elephant ivory and rhino horn to establish the origin and accordingly promote the sale of legally stockpiled reserves from South Africa into the (closed) world markets have been investigated in the past, and preliminary studies with non-nuclear techniques look promising. The Research Reactor programme within the framework of AFRA is currently becoming bent on applications of nuclear analytical techniques for socio-economic development. It is as part of this AFRA programme, that instrumental neutron activation analysis can possibly be used as a powerful and reliable fingerprinting technique for the determination of the origin of ivory.     

5-不饱和取代海因的紫外光谱及其应用

亚苄基海因、对羟基亚苄基海因、吲哚亚甲基海因的最大吸收波长分别在324、370、360nm处,而其相应的饱和取代海因则均无吸收。对羟基亚苄基海因由于酚羟基的存在,pH对其吸收光谱有较大影响。采用紫外分光光度法检测不饱和取代海因具有良好回收率,分别为99%～101%、95%～104%、98%～101%,更适合于加氢过程的在线检测。     

The application of nuclear techniques to high temperature oxidation studies

The¹⁸O(p, α)¹⁵N reaction has been used to determine the¹⁸O distribution in the oxides of a number of alloys which have been oxidised sequentially in natural gas and¹⁸O-labelled gas. A significant feature of all the cases investigated is the penetration of¹⁸O into the oxide formed previously in the natural gas. This penetration may occur in various ways and would be difficult to study by other techniques. The evidence presented here shows that there are subtle differences in oxidation behaviour and confirms that penetration of oxygen is a feature in the oxidation of alloys in which the predominant mechanism is transport of cations. This may have implications in explanations given to account for oxidation kinetics and adhesion and buckling of scales.     

Production of99Mo and its application in nuclear medicine

Molybdenum-99 is produced in large quantities as the parent radioisotopes of^99mTc, which has been used recently in nuclear medicine. The neutron capture reaction on molybdenum and the nuclear fission of uranium are used for the large scale production of⁹⁹Mo. The products by these methods are used properly according to the objects of diagnosis. In this paper, the production of⁹⁹Mo is reviewed and the development of the production in JAERI is outlined.     

35-Cl nuclear quadrupole resonance spectra in diazepam and its 1:1 complex with chloral hydrate

The 35-Cl NQR spectra of diazepam and some of its related compounds are reported; they yield information about the hydrogen bonded complex that diazepam forms with chloral hydrate. The results reflect large changes in electron distribution at the CCl₃ group while the diazepam chlorine at the 7 position remains almost unaffected.     

Fifteen years of nuclear techniques application to suspended particulate matter studies

Acute and chronic exposures to Airborne Particulate Matter (APM) have been linked, in epidemiological studies, to increased mortality and to a wide spectrum of respiratory and cardiovascular disorders. One factor that highly influences the toxicity of APM is its chemical composition. Nuclear Analytical Techniques (NATs) can be advantageously used in the determination of the particles element composition due to their multielement capability in association with low detection limits. Therefore, the characterization of APM by these techniques contributes to the identification of emission sources and, consequently, to the assessment of the effectiveness of the current air pollution abatement strategies. The main goal of this paper was to present the achievements obtained within 15 years of activities related with the use of NATs on the analysis of APM sampled in outdoor, indoor and industrial environments. The results presented in this work confirmed the relevance of NATs as efficient analytical techniques not only in the characterization of APM, but also in source apportionment, identification of long range transport and health assessment studies.     

Model uncertainty and bias in the evaluation of nuclear spectra

Unbiased analysis of γ-ray and X-ray spectra is impossible in the absence of a complete physical or mathematical model. Partial model knowledge may be supplemented by simple assumptions or by various heuristic schemes in order to effect a solution. Assessment of limits for bias, based upon the properties of the surrogate model and physical-chemical knowledge of the measurement system, is the principal target of this work. The Smoothest Consistent Baseline (SCB) approach has been introduced in an attempt to reduce assumptions and minimize bias in the extraction of a spectral peak from a baseline of uncertain shape. The bias matrix, which results directly from the numerical analysis, permits limiting baseline profiles to be simply converted into bounds for systematic model error. Contribution of the National Bureau of Standards; not subject to copyright.     

芦丁在酸碱溶液中的紫外光谱研究与应用

芦丁在酸碱溶液中具有不同的紫外吸收光谱.以芦丁的碱性溶液(pH 9.25)为测定液,以等浓度的芦丁酸溶液(pH 2.0)为参比液,用差示法测量其吸光度.结果表明:在405 nm处,当芦丁质量浓度为2.5～25 μg/mL时,吸光度与质量浓度之间存在良好的线性关系,据此建立了差示紫外吸收光度法.并用此法直接测定了芦丁片和槐米中的芦丁,回收率分别为98.8%～102.7%(RSD=1.1%)、97.0%～105.5%(RSD=2.1%).     

Systematic procedure for reduction of kinetic mechanisms of complex chemical processes and its software implementation

Feasibility of multidimensional hydrodynamic modeling depends critically on the availability of accurate reduced kinetic mechanisms of physical and chemical processes taking place in the system. Such mechanisms should describe the processes under consideration within a specified error tolerance in the range of initial conditions of interest while keeping the number of species and reactions as small as possible. We have developed an advanced tool for reduction of detailed kinetic mechanisms with a minimal human effort. The tool includes 10 reduction and 2 analysis methods which are based on the results of zero-dimensional modeling. The methods can be combined and applied in sequence. The reduction tool has been implemented as a part the Chemical Workbench computational package and has been tested for a number of large kinetic mechanisms of gas-phase processes. Using this tool, we reduced the mechanism of tar gasification from 177 species and 879 reversible reactions to only 83 species and 278 reactions, while the mechanism of methane combustion initially involving 127 species and 1,206 reactions was reduced to 42 species and 173 reactions.     

Multiple gamma-ray detection method and its application to nuclear chemistry

A new radionuclide quantification method is proposed on the basis of multiple gamma-ray detection, which is two or higher fold gamma-ray coincidence method. The coincidence method has so far been used for nuclear structure study. We apply this method for quantification of radioactive nuclei. The advantage of this method consists of high energy resolution and high sensitivity. It is successfully applied to nuclear waste analysis, neutron activation analysis and prompt gamma-ray analysis. The principle of the multiple gamma-ray detection method and future perspectives for an innovative pulsed neutron source and a new detector system will be presented.     

Characterization of Indian cigarette tobacco and its smoke aerosol by nuclear and allied techniques

Forty brands of tobacco used in Indian cigarettes, 20 brands of bidis (tobacco rolled in wrapper leaves), 15 brands of chewing tobacco and 15 brands of snuff tobacco were analyzed by nuclear and allied techniques. The elements measured into tobacco can be grouped into seven categories from less than 1 ppm to 5% by weight. Concentration level varied from 0.5-5% for (Ca, K, Cl), 400-1500 ppm (Fe), 200-600 ppm (Na), 100-300 ppm (Ti, Mn, Br and Sr), 10-100 ppm (Cu, Zn and Rb), 1-10 ppm (Cr, Ni, Pb and La) and less than 1 ppm (As, Co, Cd, Sb, Hg and Eu). Among the above elements Cr, Ni, As, Cd, Pb, Hg and Sb are considered toxic. The percentage transfer of the elements from cigarette tobacco to smoke particles during smoking was also estimated using a smoking machine and collecting the smoke particles on a filter paper. The results show that Br, Cr, Sb and Zn have high percentage transfer from tobacco to its smoke of the order of 2-15%. Out of these Sb has the highest 15%. Cobalt, Fe and Sc have lowest percentage of transfer of the order of less than 1%. The percent transfer of these elements from tobacco to tobacco smoke is higher in case of bidis (1.5-3.0 times) as compared to cigarettes. In cigarettes also non-filter cigarettes have higher transfer (2-3 times) as compared to filter tip cigarettes.     

1.5T核磁共振弛豫时间分析仪的研制及其潜在应用

介绍了国产1.5T核磁共振弛豫时间分析仪的基本组成、性能指标,研发过程中攻克的技术难题。该仪器主要由磁体部分、电子部分、软件部分组成,具有体积小、信噪比高、检测无损、使用和维护简便和造价低廉等优点。同时对该系统磁体频率和磁信号的稳定性进行了相关的测试,结果表明该系统稳定可靠。该仪器的磁场强度增加到1.5T,在同等外界条件和环境下,信噪比增加约为0.5T系统的10倍,检测灵敏度大幅度提高;该仪器为食品品质鉴定、食品安全检测、医学诊断、生物标志物的大规模筛选等生化分析提供一个全新的途径。