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  • Author or Editor: M. Wasilewska x
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Abstract  

Fast determination of calcium in cement raw mix is a very important problem from the economic point of view. In order to solve this task, the following two methods are proposed: (i) Non-dispersive X-ray fluorescence analysis (using109Cd as a source of primary radiation); (ii) back-scattering of β-particles (using90Sr+90Y as a source). The influence of the following factors has been studied in both methods: (i) concentration of iron in the matrix; (ii) water content; (iii) grain size of the sample. The influence of the energy of the primary radiation on the slope of a calibration curve has been analyzed in the fluorescence method. In the concentration range of 42–52% CaO, the absolute standard error is 0.17% CaO in the fluorescence analysis, and 0.5% CaO for the method of back-scattering of β-particles. The average time of a determination is about 2 min.

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Abstract  

Theoretical considerations and experimental data are presented concerning the influence of the energy of the primary radiation on the sensitivity of X-ray fluorescence analysis. An additional criterion in selecting the energy of the primary radiation based on the relative sensitivity of X-ray fluoresence analysis depends on the energy of the primary radiation and it becomes higher with the increase of this energy.

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Abstract  

Radiometric methods of determination of platium and palladium (0.1 to 5% of Pt and 0.1 to 2% of Pd), gold and indium (0.01 to 1% of Au and 1 to 4 g In/l) and of platinum and rhodium (0.1 to 9% of Pt and 0.05 to 1% of Rh) in aqueous solution has been worked out. A suitable measuring device has been designed and constructed. The methods are based on the measurement of characteristic radiation of the Lα line for gold and platinum and of the K-series for indium, palladium and rhodium, as well as on the measurement of scattered radiation from a238Pu source. The r.m.s. error of the determination varies from 0.01 to 0.10% of Pt, 0.002 to 0.01% of Au and 0.01 to 0.15% of Pd depending on the concentration. In the case of Rh and In the errors are 0.008% and 0.04 g In/l, respectively.

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Six strains (Bi11, Bi30, Bi36, Bi50, Bi52 and Bi55) isolated from bio-yoghurts and two strains (KD10 and KD11) derived from human faeces were identified by genus- and species specific polymerase chain reaction (PCR) with reference to the type strains of B. animalis subsp. lactis DSM 10140 and B. animalis subsp. animalis DSM 20104. The isolates were differentiated by using Bcu I ( Spe I), Xba I and Dra I endonucleases for subsequent pulsed field gel electrophoresis (PFGE) technique and by API 50 CHL tests.All the isolates tested were classified to B. animalis subsp. lactis species. The reliable identification as B. animalis subsp. lactis (by PCR with Bflact2/Bflact5 primers), however, required confirmation by a negative result of B. animalis subsp. animalis -specific PCR.Differentiation of the B. animalis subsp. lactis isolates with PFGE method enabled to distinguish KD11 strain with all the restriction enzymes applied, and Bi11 and Bi30 — exclusively with Dra I and Spe I enzymes, respectively. The biochemical tests, however, revealed that all the strains tested were characterised by a unique fermentation pattern. It was concluded that differentiation of the B. animalis subsp. lactis strains should be carried out on the basis of both genetic and phenotypic features.

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