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An attempt has been made to rationalise the major fragmentation modes of a few C2, C3 disubstituted 7-p-toluene sulphonyl and 7-carbobenzyloxy-7-azabicyclo (2.2.1) heptanes. [ABSTRACT FROM AUTHOR]

The variation in the ratio of the relative abundances of the diene and ene ions formed by competing retro-Diels-Alder reactions with electron energy and subtituents has been studied. This ratio represents the ratio of the rate constants of the processes and depends on the internal energy distribution within the decomposing molecular ions. [ABSTRACT FROM AUTHOR]

Mass spectrometry can be used to characterise fructofuranose units connected via C2 to another sugar. The intensity of the m/ e 101 and m/ e 88 ions cannot be used to differentiate between furanose and pyranose ring forms in disaccharide permethyl ethers. The type of glycosidic linkage has considerable influence on the formation of these ions. [ABSTRACT FROM AUTHOR]

Mass spectral studies on costunolide and lactones derived therefrom, have revealed some general fragmentation modes involving the losses of 44, 55, 57, 59, 71, 73 and 83 mass units from the molecular ion. The probable genesis of these ions is established by high resolution, metastable transitions and deuterium labelling studies. Comparison has been made with the mass spectra of some C6- desoxy esters. [ABSTRACT FROM AUTHOR]

Some of the fragmentation modes operating in a few furanosesquiterpenes have been established from accurate mass measurements and metastable data. [ABSTRACT FROM AUTHOR]

The fragmentation modes of some epimeric 7-substituted norbornenes have been established from deuteration and high resolution studies. Stereochemical differences were found to have very little influence in directing the fragmentation modes of these epimers. Formation of common intermediates or transition states by ring opening process has been proposed to rationalise the mass spectral behaviour of these compounds. [ABSTRACT FROM AUTHOR]

An attempt has been made to correlate the fragmentation modes and structure of costunolide and some lactones derived from it, containing a ten-membered carbocyclic system. The possible origins for the major fragments have been determined, using high resolution mass spectrometry and deuterium labelling. [ABSTRACT FROM AUTHOR]

ABSTRACT For single plane implants with gold seeds, assuming a matrix distribution for the seeds, the optimum separation of the matrix elements and the optimum ratio of the activity of the seeds in the area to that of those in the periphery, have been calculated, so that the uniformity of dose- distribution is within 10%. Area dosages have also been computed and are tabulated. The dose variations in double plane implants and volume implants also have been studied and the results are presented. Dosage graphs have been given for both cases. The theoretical dose distributions have been verified for a few implants experimentally using LiF thermoluminescence dosimeters. [ABSTRACT FROM AUTHOR]

The metabolism of salicylazosulphapyridine was studied in 16 patients with ulcerative colitis admitted to hospital. The acetylator phenotype was determined on admission. The mean serum concentration (μg/ml) (at steady state eight ± two days in patients responding to treatment) of SASP, total SP, and 5-ASA were 18·7 ± 12·8; 53·7 ± 23·1; and 1 ± 0·9 for slow acetylators and 17·6 ± 7·1; 31 ± 9·0 and 1 ± 0·9 for fast acetylators respectively. Twenty-four hour urinary excretion of SASP, total SP, and 5-ASA were 4·6% ± 3·1; 52% ± 9·6 and 22·3 ± 6·7% of the administered dose respectively. Serum total SP concentration of 20 to 50 μg/ml appeared to coincide with clinical improvement in the absence of any side effects related to salicylazosulphapyridine. No such relationship could be shown with serum SASP, individual metabolites, or 5-aminosalicyclic acid. [ABSTRACT FROM PUBLISHER]

The effect of substituents on hydrogen and hydroxyl transfer in substituted benzaldoximes reveals interesting differences. A possible explanation in terms of radical electron site and charge site is suggested. [ABSTRACT FROM AUTHOR]