Search results for "ISOTOPES"
showing 10 items of 1216 documents
Synthesis and in vitro evaluation of (S)-2-([11C]methoxy)-4-[3-methyl-1-(2-piperidine-1-yl-phenyl)-butyl-carbamoyl]-benzoic acid ([11C]methoxy-repagl…
2004
The 11 C-labeled sulfonylurea receptor 1 (SUR1) ligand (S)-2-(( 11 C)methoxy)-4-(3-methyl-1-(2-piperidine-1-yl-phenyl)- butyl-carbamoyl)-benzoic acid (( 11 C)methoxy-repaglinide) was synthesized in an overall radiochemical yield of 35% after 55 min with a radiochemical purity higher than 99%. This compound is considered for the noninvasive investigation of the SUR1 receptor status of pancreatic b-cells by positron emission tomography (PET) in the context of type 1 and type 2 diabetes. The specific activity was 40-70 GBq/lmol. In vitro testing of the nonradioactive methoxy-repaglinide was performed to characterize the affinity for binding to the human SUR1 isoform. Methoxy-repaglinide induce…
Nature and origin of natural Zn clay minerals from the Bou Arhous Zn ore deposit: Evidence from electron microscopy (SEM-TEM) and stable isotope comp…
2016
International audience; Zn-clay minerals have been found in the non-sulfide deposit of Bou Arhous (High Atlas, Morocco). They occur as white or ochre clays embedding willemite (Zn2SiO4) and are commonly associated to red detrital clays in karstic cavities. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) with Energy Dispersive X-ray (EDX) analyses were combined in order to characterize the clay minerals and to determine the mechanism of their formation. XRD patterns on oriented and powdered clays and Fourier Transform Infrared (FTIR) spectroscopic analyses suggest that fraipontite is the major Zn clay phase (with some smectite interstrat…
Biogeochemical evaluation of historical sediment contamination in the Gulf of Palermo (NW Sicily): Analysis of pseudotrace elements and stable isotop…
2012
Abstract Sedimentary biogeochemical data from the Gulf of Palermo, which borders one of the major urban and industrial areas of the central Mediterranean, provide a decennial–centennial-scale record of the effects of human activity on this coastal environment. In this study we report trace elements (TE), C org /N tot ratios, δ 13 C org , and δ 15 N tot from dated ( 210 Pb) sediments collected in two coastal stations variably influenced by urban/fluvial loadings and illegal dumping and we compare them with published data for offshore sediments, in order to investigate at a large spatial scale the influence of on-land activities on sedimentary marine system. TE were generally low except for H…
Osmium and lithium isotope evidence for weathering feedbacks linked to orbitally paced organic carbon burial and Silurian glaciations
2022
Abstract The Ordovician (∼487 to 443 Ma) ended with the formation of extensive Southern Hemisphere ice sheets, known as the Hirnantian glaciation, and the second largest mass extinction in Earth History. It was followed by the Silurian (∼443 to 419 Ma), one of the most climatically unstable periods of the Phanerozoic as evidenced by several large scale ( > 5 ‰ ) carbon isotope (δ13C) perturbations associated with further extinction events. Despite several decades of research, the cause of these environmental instabilities remains enigmatic. Here, we provide osmium (187Os/188Os) and lithium (δ7Li) isotope measurements of marine sedimentary rocks that cover four Silurian δ13C excursions. Osmi…
Dynamic Precision Phenotyping Reveals Mechanism of Crop Tolerance to Root Herbivory.
2016
The western corn rootworm (WCR; Diabrotica virgifera virgifera LeConte) is a major pest of maize (Zea mays) that is well adapted to most crop management strategies. Breeding for tolerance is a promising alternative to combat WCR but is currently constrained by a lack of physiological understanding and phenotyping tools. We developed dynamic precision phenotyping approaches using 11C with positron emission tomography, root autoradiography, and radiometabolite flux analysis to understand maize tolerance to WCR. Our results reveal that WCR attack induces specific patterns of lateral root growth that are associated with a shift in auxin biosynthesis from indole-3-pyruvic acid to indole-3-aceton…
Whole-lake dissolved inorganic 13C additions reveal seasonal shifts in zooplankton diet.
2008
Sustained whole-lake additions of 13C-enriched dissolved inorganic carbon (DIC), intended to increase experimentally the delta13C of DIC in the epilimnion of a small lake with high dissolved organic carbon (DOC), were made during three seasonal periods (spring, summer, and autumn). Coupled with carbon and nitrogen stable isotope analysis of zooplankton and several of their putative food sources, these additions were used to investigate seasonal changes in the relative contributions of different food sources to zooplankton diet in the lake. Four main potential food sources were considered: phytoplankton, heterotrophic bacteria (HB), methanotrophic bacteria (MOB), and green sulfur bacteria (G…
In-beam spectroscopic study of Cf244
2018
The ground-state rotational band of the neutron-deficient californium (Z = 98) isotope 244Cf was identified for the first time and measured up to a tentative spin and parity of I I-pi = 20(+). The observation of the rotational band indicates that the nucleus is deformed. The kinematic and dynamic moments of inertia were deduced from the measured gamma-ray transition energies. The behavior of the dynamic moment of inertia revealed an up-bend due to a possible alignment of coupled nucleons in high-j orbitals starting at a rotational frequency of about (h) over bar (omega) = 0.20 MeV. The results were compared with the systematic behavior of the even-even N = 146 isotones as well as with avail…
A dosimetric study of Leipzig applicators.
2005
Purpose: To obtain the absolute dose-rate distribution in liquid water for all six cup-shaped Leipzig applicators by means of an experimentally validated Monte Carlo (MC) code. These six applicators were used in high-dose-rate (HDR) afterloaders with the “classic” and v2 192Ir sources. The applicators have an inner diameter of 1, 2, and 3 cm, with the source traveling parallel or perpendicular to the contact surface. Methods and materials: The MC GEANT4 code was used to obtain the dose-rate distribution in liquid water for the six applicators and the two HDR source models. To normalize the applicator output factors, a MC simulation for the “classic” and v2 sources in air was performed to es…
Determining seasonality of mussel collection from an early historic Inuit site, Labrador, Canada: Comparing thin-sections with high-resolution stable…
2018
International audience; Stable oxygen isotope (delta O-18) analysis of mussels (Mytilus sp.) from a 16th to mid-18th century Inuit site in southern Labrador, Canada, indicates multiple seasons of shellfish collection, and by proxy, multiple seasons of site occupation. High-resolution delta O-18 sampling of shell permits a precise season of mussel collection since the temperature and freshwater signal of the local water is retained in the shell. Live-collected specimens of Mytilus sp. obtained from Labrador, were analyzed for stable oxygen isotopes and for growth patterns. These data were used to interpret results from the archaeological shells. Growth pattern analysis was conducted to test …
Consistent isotopic differences between Schistocephalus spp. parasites and their stickleback hosts
2015
Published version available at http://dx.doi.org/10.3354/dao02893 Parasite−host systems show markedly variable patterns in isotopic fractionation: parasites can be either depleted or enriched in 15N and 13C as compared to their hosts. However, it remains unknown whether isotopic fractionation patterns are similar in comparable parasite−host systems from markedly different ecosystems. Results of this study show that large-sized Schistocephalus spp. endoparasites are consistently depleted in 15N (by on average −2.13 to −2.20‰) as compared to their nine-spined stickleback Pungitius pungitius and three-spined stickleback Gasterosteus aculeatus hosts. The differences between parasites and host f…