Physalis withasteroids

The review gives a table of 47 withasteroids isolated from plants of the genusPhysalis. The biogenetic relationship between the different structures of the compounds is discussed on the basis of an analysis of literature material. An assignment of some C-methyl groups of the physalins is made.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 263–277, May–June, 1986.     

Researches on pyrazoles

Alkyl and aryl pyrazoles are acylated at position 4 by the chloroanhydrides and anhydrides of the lowest fatty and aromatic acids in the presence of catalytic amounts of sulfuric acid. Reaction is readily effected because it is the neutral pyrazole molecule which is being acylated. In individual cases 1, 3, 5-trimethylpyrazole can be alkylated at position 4 by the Friedel-Crafts reaction.For Part IL see [6].     

Quality of electron probe X-ray microanalysis determinations obtained from laboratory reference materials of the coppery alloys and basaltic glasses

Nine coppery alloys and five basaltic glasses have been quantitatively evaluated as the reference materials to employ in electron probe X-ray microanalysis. The optimum conditions for measurements were selected considering the dependence of intensity and detection limit on the conditions of the X-ray radiation excitation and analytical signal recording. The homogeneity of basaltic glasses and coppery alloys has been examined. The dependence of electron probe X-ray microanalysis accuracy on the homogeneity of reference materials was studied in the reference materials of coppery alloys.Six data sets comprising the average concentrations, standard deviations, relative standard deviations, confidence interval and the z-score of data quality were calculated for 50 control samples: 10 alloys, 14 glasses, 2 metals, 24 minerals and oxides. The average compositions of every control sample were derived in 8–16 analyses. The measured values were corrected for matrix effects applying the original program. These series of concentrations have been compared with each other and with the certified/recommended values using 2-pair selective Student's t-test.The results gained from both laboratory reference materials and certified glass reference materials show comparable accuracy. The quality of all available results complies with the “applied geochemistry” category of performance (2nd category). The laboratory reference materials give comparable accuracy to certified reference materials and can be used for calibrating microprobe techniques, as well as data quality control. The application of laboratory reference materials in microanalysis of silicate minerals and coppery alloys allows reliable analytical data to be acquired. The applications in mineralogy and metallurgy can be extended successfully to the targets when certified reference materials are not available.