This paper describes a new version of the measurement of the calibration factor, K, between radon activity concentration and track density. The use of Solid State Nuclear Track Detectors (SSNTDs) is one of the most convenient techniques to assess the radiation level of -activities in the environment. Exposed plastic films are chemically and electrochemically etched in an alkali solution and the -tracks are evaluated under an optical microscope. The detailed procedure for this study and the caliabration of the etched films for conversion of track density to radon exposure in (Bq·m–3) are given in this paper. It was found the experimental and theoretical values of K were 1.37 and 1.27 (track·cm–2·kBq–1·h–1·m3), respectively, for plastic detectors CR-39.
Authors:Christian Mattle, Nico Heigl, Gudrun Abel, Günther Bonn, and Christian Huck
By use of near infrared (NIR) spectroscopy hyphenated to thinlayer chromatography (TLC) for analysis of methoxylated flavones in a phytomedicine we sought to achieve two objectives: first, to establish a method for rapid, qualitative identification of five methoxylated flavones, denoted G1, G2, G3, G4, and G5, in order of their RF values in normal-phase TLC, and, second, to produce a quantitative model for analysis of G4 (3′,4′,5′-trimethoxyflavone), the compound most representative of Primula veris flowers in phytomedicine. To provide appropriate reference analytical data for building the multivariate cluster and partial least-squares regression (PLS) model, TLC was performed on alumina with n-hexane-ethyl acetate 70:30 (v/v) as mobile phase. Forty-four spectra of eleven independent phytomedicine samples were analyzed with five scans to generate a qualitative cluster model based on PCA (principle-components analysis) that enabled differentiation between G1-G5 on the basis of their methoxylation pattern. This PLS model, in the calibration range between 0 and 1000 mg L−1, enabled quantification of G4 with a standard error of cross validation (SECV) ,54.61 mg L−1. The possibility of conducting qualitative and quantitative analysis simultaneously by use of this method revealed NIRS to be an efficient alternative to conventional modes of detection used for analysis of G1-G5, especially in phytomedicines.
Thermodynamic model for the quantitative description of the electromotive force in a thermocouple has been developed. Thermodynamic
equilibrium was applied to the system of electrons in two metals in a contact, contrary to the consideration of the dynamics
of electrons in a metal under external temperature gradient in the previous classical (Drude) and quantum (Sommerfeld) approaches.
The new model has two parameters, the ‘universal’ sensitivity ɛ0 and the characteristic temperature of a particular thermocouple Θv, and quite simple expression for the emf ΔU=ɛ0(T−Θvln(1+T/Θv) and sensitivity ɛ(T)=ɛ0T/(Θv+T). The model is shown to fit the experimental data very well at low temperatures. At high temperatures, the model is less
The characteristic temperature Θv depends on the difference between the electron heat capacity coefficients γ1−γ2 of two metals in the thermocouple. The greater the difference, the higher the sensitivity of the thermocouple.
The application of target factor analysis to the analysis of gamma-ray spectra collected for activation analysis is proposed. Satisfactory analysis of a trial set of samples was carried out using measured spectra as targets. Single-isotope spectra were obtained from mixture spectra by free-floating and performed satisfactorily as target spectra. The factor analysis method requires less resolution than peak-based methods.
Authors:R. Kirchner, M. Rodriguez de Rivera, J. Seidel, and V. Torra
Using an RC model, the behavior of a TAM high-performance calorimeter (Thermometric AB, Sweden) equipped with a flow-mixing
insertion vessel using independent pumps for each reactant is studied. The model shows a reliable sensitivity behavior for
mixtures realized inside the cell. The model behavior is compared with experimental measurements.</o:p>
A method preparing solutions of a mixed chloro, bromo-complex of tellurium labeled with123mTe is described. The solutions are shown to be excellent standards for calibrating radioisotope dose calibrators used to measure123I.