Search results for "ISOTOPES"
showing 10 items of 1216 documents
Leukoma antiqua (Bivalvia) - A high-resolution marine paleoclimate archive for southern South America?
2018
The Patagonian Sea in the SW Atlantic is one of the most productive marine ecosystems worldwide. Besides its economic relevance, this shelf sea serves as a major sink for atmospheric CO2 and thus plays a major role in global climate. Despite that, the marine climate dynamics in that region remain barely known. Instrumental records only cover the last 30 years or so and high-resolution climate archives are currently not available. Here, we explore the possibility to obtain seasonally to inter-annually resolved paleotemperature data from shells of the bivalve mollusk, Leukoma antiqua collected alive from the shallow subtidal zone of the San Jorge Gulf. Results demonstrate that this species gr…
Opposite Trends in Holocene Speleothem Proxy Records From Two Neighboring Caves in Germany: A Multi-Proxy Evaluation
2021
Holocene climate in Central Europe was characterized by variations on millennial to decadal time scales. Speleothems provide the opportunity to study such palaeoclimate variability using high temporal resolution proxy records, and offer precise age models by U-series dating. However, the significance of proxy records from an individual speleothem is still a matter of debate, and limited sample availability often hampers the possibility to reproduce proxy records or to resolve spatial climate patterns. Here we present a palaeoclimate record based on four stalagmites from the Hüttenbläserschachthöhle (HBSH), western Germany. Two specimens cover almost the entire Holocene, with a short hiatus …
Potassic and sodic igneous rocks from eastern Paraguay: their origin from the lithospheric mantle and genetic relationships with the associated Paran…
1997
3 DIPARTIMENTO DI SCIENZE DELLA TERRA, UNIVERSITY OF TRIESTE, VIA E. WEISS 8, I-34127 TRIESTE, ITALY 4 INSTITUTO DE GEOCIENCIAS, UNIVERSIDADE DE SAO PAULO, C.P. 30627, 01051 SAO PAULO, SP, BRAZIL 5 DIPARTIMENTO DI SCIENZE DELLA TERRA, ‘LA SAPIENZA’ UNIVERSITY, PIAZZALE ALDO MORO 5, I-00185, ROME, ITALY 6 ISTITUTO DI MINERALOGIA, PETROGRAFIA E GEOCHIMICA, UNIVERSITY OF PALERMO, VIA ARCHIRAFI 36, I-90100,
In Vitro Evaluation of the Squaramide-Conjugated Fibroblast Activation Protein Inhibitor-Based Agents AAZTA5.SA.FAPi and DOTA.SA.FAPi
2021
Recently, the first squaramide-(SA) containing FAP inhibitor-derived radiotracers were introduced. DATA5m.SA.FAPi and DOTA.SA.FAPi with their non-radioactive complexes showed high affinity and selectivity for FAP. After a successful preclinical study with [68Ga]Ga-DOTA.SA.FAPi, the first patient studies were realized for both compounds. Here, we present a new squaramide-containing compound targeting FAP, based on the AAZTA5 chelator 1,4-bis-(carboxylmethyl)-6-[bis-(carboxymethyl)-amino-6-pentanoic-acid]-perhydro-1,4-diazepine. For this molecule (AAZTA5.SA.FAPi), complexation with radionuclides such as gallium-68, scandium-44, and lutetium-177 was investigated, and the in vitro properties of…
Archaeology, chronology, and age-diet insights of two late fourth millennium cal BC pit graves from central southern Iberia (Córdoba, Spain)
2020
This study presents the isotopic ratios, radiocarbon datings, and anthropological analyses of five (N = 5) Early Copper Age individuals from two archaeological sites (Arruzafa and Iglesia Antigua de Alcolea) of the Middle Guadalquivir Valley near the city of Córdoba (Spain). Four had been buried in the same grave, possibly in a single event or in a very short time lapse. The collagen residue analyses of the individuals offer δC values ranging between −20.08 and −18.4 and δN values between 8.57 and 11.15. The findings indicate that the infant and the elderly had, respectively, the richest and poorest animal protein diets, the first likely as a result of nursing. The combined study of these f…
Chemostratigraphy, magnetostratigraphy, chronology, palaeoenvironments and correlations.
2013
4 pages
Valanginian isotope variation in glendonites and belemnites from Arctic Svalbard: Transient glacial temperatures during the Cretaceous greenhouse
2010
Oxygen and carbon isotope data from Cretaceous (Valanginian) glendonites and belemnites from Arctic Svalbard are presented. Oxygen isotope data from well-preserved glendonites, in conjunction with the ikaite to glendonite pseudomorph transition temperature, are used to provide an estimate of the oxygen isotope composition of ambient seawater. Calculation of such a factor is essential for robust paleotemperature estimates. Using this methodology, our paleotemperatures calculated from the oxygen isotope compositions of coexisting belemnites yield cool temperatures (4–7 °C) consistent with transient glacial polar conditions during the Cretaceous greenhouse. Cool polar temperatures during the C…
Thermal evolution of Tethyan surface waters during the Middle-Late Jurassic: Evidence from δ18O values of marine fish teeth
2003
[1] Oxygen isotope compositions of phosphate from vertebrate tooth enamel were measured to determine the evolution of tropical sea surface ( 0‰ owing to limited growth of continental ice during the early middle Oxfordian. The resulting sea level fall is estimated to be at least 50 m and is compatible with a global regression stage. The middle Oxfordian thermal minimum is followed by a new warming stage of 3–4°C from the middle to the late Oxfordian.
Vertical distribution of AhR-activating compounds in sediments contaminated by modernized pulp and paper industry
2013
Increased ethoxyresorufin-O-deethylase (EROD) activity is a sensitive biomarker of exposure to the chemicals which activate the aryl hydrocarbon receptor (AhR) and induce the cytochrome P450 system, such as many polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs). Pulp bleaching was one of the main sources of PCDDs and PCDFs until elemental chlorine free (ECF) and total chlorine free bleaching processes since 1990s have remarkably decreased but not completely eliminate discharges of these chemicals. In addition, historically contaminated sediments may act as a source of these persistent contaminants. In this study, the contam…
Theoretical estimates of supernova-neutrino cross sections for the stable even-even lead isotopes: Charged-current reactions
2016
A detailed study of the charged-current supernova electron neutrino and electron antineutrino scattering off the stable even-mass lead isotopes $A=204$, 206, and 208 is reported in this work. The proton-neutron quasiparticle random-phase approximation (pnQRPA) is adopted to construct the nuclear final and initial states. Three different Skyrme interactions are tested for their isospin and spin-isospin properties and then applied to produce (anti)neutrino-nucleus scattering cross sections for (anti)neutrino energies below 80 MeV. Realistic estimates of the nuclear responses to supernova (anti)neutrinos are computed by folding the computed cross sections with a two-parameter Fermi-Dirac distr…