a total of 40 samples from carbonates and 8 samples from silicate rocks were analyzed from the sangan iron skarn deposit to examine behavior of the oxygen and carbon isotopes. the higher values of ?18o are from metamorphic calcite and dolomite and lower ones are from granitic rocks. although the ?18o and ?13c values of calcite and dolomite in marble yield the highest values in the sangan deposi...

a total of 40 samples from carbonates and 8 samples from silicate rocks were analyzed from the sangan iron skarn deposit to examine behavior of the oxygen and carbon isotopes. the higher values of ?18o are from metamorphic calcite and dolomite and lower ones are from granitic rocks. although the ?18o and ?13c values of calcite and dolomite in marble yield the highest values in the sangan deposi...

1. Stable urea isotopes can be used to study urea kinetics in humans. The use of stable urea isotopes for studying urea kinetic parameters in humans on a large scale is hampered by the high costs of the labelled material. We devised a urea dilution for measurement of the distribution volume, production rate and clearance of urea in healthy subjects and renal failure patients using the inexpensi...

A recent communication (I) has suggested a method of studying 13C-13C couplings in samples with the natural 13C abundance by suppressing the strong cemral resonance from molecules containing a single isolated 13C nucleus, revealing the weak satellite signals from the coupled 13C-13C systems. Excellent suppression ratios were achieved by momentary conversion of the magnetization from coupled spi...

In order to delineate the origin of soil fatty acids, crop soil samples have been incubated for 21 days in vitro either with unlabelled or 13C-labelled glucose. Analyses of C14-C32 n-alkanoic acids from monocarboxylic acid fractions, as methyl esters, by gas chromatography-combustion-isotope ratio monitoring mass spectrometry (GC-C-IRMS) show that C14, C16 and C18 n-alkanoic acids are 13C-label...

The biosynthetic origins of the carbon skeleton in graphenone were verified by feeding the culture of spore-derived mycobionts of the lichen Graphis handelii with sodium [1-13C]-acetate, sodium [1,2-13C2]-acetate, sodium [2-13C]-pyruvate, [1,2,3-13C]-glycerol, [13CH3]-methionine and sodium [1,4-13C2]-succinate.

In this study, we present the first experimental results for stable barium (Ba) isotope ((137)Ba/(134)Ba) fractionation during low-temperature formation of the anhydrous double carbonate BaMn[CO(3)](2). This investigation is part of an ongoing work on Ba fractionation in the natural barium cycle. Precipitation at a temperature of 21±1°C leads to an enrichment of the lighter Ba isotope described...

BACKGROUND AND AIMS The 13C-Hiolein breath test (98% [U-13C] labelled long chain triglyceride mixture (highly labelled triolein) was evaluated as a non-invasive, non-radioactive test for exocrine pancreatic insufficiency. Accuracy and clinical validity were examined with reference to both the secretin pancreozymin test and faecal fat analysis. METHODS A secretin pancreozymin test and faecal f...

Biosynthesis of griseolic acids, competitive inhibitors of cyclic nucleotide phosphodiesterase, was investigated with the culture of a producing strain of Streptomyces griseoaurantiacus. 13C-Labeled and 15N-labeled compounds were added into the culture, and 13C-enriched and 15N-enriched griseolic acid A was isolated from the culture medium and analyzed by 13C NMR and 15N NMR spectroscopy. The c...