The distinctive relations between biological activity and isotopic effect recorded in biomarkers (e.g., carbon and sulfur isotope ratios) have allowed scientists to suggest that life originated on this planet nearly 3.8 billion years ago. The existence of life on other planets may be similarly identified by geochemical biomarkers, including the oxygen isotope ratio of phosphate (delta(18)O(p)) ...

The alkaline perhydrolysis of the nerve agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) was investigated by studying the ion-molecule reactions of HOO(-) with O,S-dimethyl methylphosphonothioate in a modified linear ion-trap mass spectrometer. In addition to simple proton transfer, two other abundant product ions are observed at m/z 125 and 109 corresponding to the S-met...

A substantial body of evidence suggests that subsurface water masses in mid-Proterozoic marine basins were commonly anoxic, either euxinic (sulfidic) or ferruginous (free ferrous iron). To further document redox variations during this interval, a multiproxy geochemical and paleobiological investigation was conducted on the approximately 1000-m-thick Mesoproterozoic (Lower Riphean) Arlan Member ...

Adsorption of 4-imidazolemethanol (ImMeOH) on a copper electrode has been investigated by in situ isotope-edited (H/D and (63)Cu/(65)Cu) surface enhanced Raman spectroscopy (SERS) in aqueous solutions at physiological pH (7.0) in a potential window from -0.500 to -1.100 V. Theoretical modeling by DFT calculations at the B3LYP/6-311++G(d,p) level for light atoms and LANL2DZ with ECP for copper a...

Revised delta(34)S reference values with associated expanded uncertainties (95% confidence interval (C.I.)) are presented for the sulfur isotope reference materials IAEA-S-2 (22.62 +/- 0.16 per thousand) and IAEA-S-3 (-32.49 +/- 0.16 per thousand). These revised values are determined using two relative-difference measurement techniques, gas source isotope ratio mass spectrometry (GIRMS) and dou...

The earliest indication for the need of an organic sulfur complex in the diet came in 1915 from the work of Osborne and Mendel (I), who showed that when the proportion of casein in the diet of the rat was reduced from 18 to 9 per cent the resulting impairment of growth could be corrected by a supplement of cystine equal to 3 per cent of the casein. This finding was confirmed in many laboratorie...

Archean sulfur mass-independent fractionation (S-MIF) has been widely recognized as one of the strongest indicators for the rise of atmospheric oxygen in the Early Proterozoic. A decade after its discovery, the wide-ranging implications of Archean sulfur MIF have been discussed extensively and despite a number of recent studies on the gas-phase chemistry of sulfur, no definite overall picture h...

Multiple sulfur isotope measurements of sulfur compounds associated with dissimilatory sulfate reduction, elemental sulfur disproportionation and sulfite disproportionation indicate that different types of metabolic processes impart different multiple isotope signatures. An established network for sulfate reduction was used previously to explain the multiple isotope variability. Here, we revisi...

Sediment variables total organic carbon (TOC), total nitrogen (TN), total sulfur (TS), as well as their accumulation rates and atomic ratios (C/N and C/S), were studied along with stable isotopes (δ 13 C, δ 15 N, and δ 34 S), and specific biomarkers (n-alkanes and pigments) in a 35-cm-long sediment core from Lake Bhimtal, NW India. The average sedimentation rate is 3.6 mm yr -1 , and the core r...

The diet-tissue discrimination factor is the amount by which a consumer's tissue varies isotopically from its diet, and is therefore a key element in models that use stable isotopes to estimate diet composition. In this study we measured discrimination factors in blood (whole blood, red blood cells and plasma), liver, muscle and feathers of Double-crested Cormorants (Phalacrocorax auritus) for ...