Search results for "δ"
showing 10 items of 315 documents
CCDC 1042836: Experimental Crystal Structure Determination
2015
Related Article: Rakesh Puttreddy, James A. Hutchison, Yuri Gorodetski, Jack Harrowfield, Kari Rissanen|2015|Cryst.Growth Des.|15|1559|doi:10.1021/acs.cgd.5b00053
Relation between microstructure and transport properties of epitaxial YBa2Cu3O7-d thin films.
1997
Abstract In order to understand the origin of the high critical current densities observed in thin superconducting films compared to single crystals we measured in several epitaxial YBa 2 Cu 3 O 7−δ thin films the magnetic field and temperature dependence of the superconducting current density j s and the dynamical relaxation rate Q ≡ d ln j s / d ln( d B/ dt ). For all samples we found that (i) the superconducting current density j s is independent of magnetic field up to a certain field B Φ . The value of this field, which is sample dependent, decreases with increasing temperature; (ii) for fields B>B Φ , the superconducting current density falls off as B −1/2 over several decades; (iii) …
Environmental conditions at the Last Interglacial (Eemian) site Neumark‐Nord 2, Germany inferred from stable isotope analysis of freshwater mollusc o…
2020
Acknowledgements The authors acknowledge the two anonymous reviewers for their useful comments that improved the manuscript. Financial support for the excavations in Neumark‐Nord 2 was provided by the Lausitzer Mitteldeutsche Braunkohlengesellschaft mbH, the Landesamt fur Denkmalpflege und Archaologie Sachsen‐Anhalt (Harald Meller, Susanne Friederich), the Romisch‐Germanisches Zentralmuseum Mainz, the Leids Universiteits Fonds ‘Campagne voor Leiden’ program and the Netherlands Organization for Scientific Research (N.W.O.).
Phenotypical and Functional Alteration of γδ T Lymphocytes in COVID-19 Patients: Reversal by Statins
2022
(1) Background: statins have been considered an attractive class of drugs in the pharmacological setting of COVID-19 due to their pleiotropic properties and their use correlates with decreased mortality in hospitalized COVID-19 patients. Furthermore, it is well known that statins, which block the mevalonate pathway, affect γδ T lymphocyte activation. As γδ T cells participate in the inflammatory process of COVID-19, we have investigated the therapeutical potential of statins as a tool to inhibit γδ T cell pro-inflammatory activities; (2) Methods: we harvested peripheral blood mononuclear cells (PBMCs) from COVID-19 patients with mild clinical manifestatio…
Sedimentary record of anthropogenic chemical and organic pollution in a Mediterranean coastal area (Gulf of Palermo, Italy).
2009
The relatively high influx of unregulated industrial and domestic effluents has progressively degraded the Palermo coastal environment in NW Sicily. To evaluate the poorly known effects of these inputs on the Palermo Gulf, three sediment box-cores were collected along a transect perpendicular to the coast, in front of the Oreto river mouth, in water depths of 20—750 m. The samples, dated by 210Pb and 137Cs, were analysed for concentration of major/trace elements, total polycyclic aromatic hydrocarbon (PAH), total organic carbon (TOC) and for organic carbon and nitrogen isotopic compositions. Total organic carbon concentrations show relatively high values (0.4—2.9%), with a decreasing seawar…
Environmental and depositional controls on laminated freshwater carbonates: An example from the Roman aqueduct of Patara, Turkey
2013
Carbonate deposits in aqueducts are a new high-resolution data source for environmental changes during the time of the Roman Empire, notably in the fields of palaeoclimate and spring hydrology. In order to distinguish environmental effects from those related to depositional setting, laminated carbonate deposits were compared along the entire length of an ancient aqueduct channel at Patara, Turkey. The carbonate deposits, up to 80mm in thickness, are composed of lamina couplets up to 1mm thick of alternating porous microspar and dense, columnar sparite. The former formed in the dry, warm season and the latter in the wet, cool season. The presence of biofilms seems to play a role in the devel…
Sea-level changes during the last 41,000 years in the outer shelf of the southern Tyrrhenian Sea: Evidence from benthic foraminifera and seismostrati…
2011
Abstract An integrated high resolution study based both on a seismostratigraphic approach and on a sedimentary core (VIB 10), collected in the outer shelf (127 m depth) from the southern Tyrrhenian Sea (Gulf of Termini, Sicily), provides new data about climatic, eustatic and paleoenvironmental changes during the last ∼41,000 years. The results based on the interpretation of a seismic profile, on benthic foraminifera assemblages and on δ18O records, allowed recognition of two drastic sea-level falls during the Last Glacial Maximum (LGM) and the Younger Dryas (YD). The short deglacial event, between LGM and YD, known as Bolling/Allerod, played an important role in the sea-level rise that prod…
Isotopically (δ13C and δ18O) heavy volcanic plumes from Central Andean volcanoes: a field study
2017
International audience; Stable isotopes of carbon and oxygen in volcanic gases are key tracers of volatile transfer between Earth's interior and atmosphere. Although important, these data are available for few volcanoes because they have traditionally been difficult to obtain and are usually measured on gas samples collected from fumaroles. We present new field measurements of bulk plume composition and stable isotopes (δ13CCO2 and δ18OH2O+CO2) carried out at three northern Chilean volcanoes using MultiGAS and isotope ratio infrared spectroscopy. Carbon and oxygen in magmatic gas plumes of Lastarria and Isluga volcanoes have δ13C in CO2 of +0.76‰ to +0.77‰ (VPDB), similar to slab carbonate;…
Monitoring of Cueva Larga, Puerto Rico—A First Step to Decode Speleothem Climate Records
2017
This study presents results of an ongoing cave monitoring program at Cueva Larga, Puerto Rico. The monitoring includes monthly analyses of stable isotope ratios of rain and drip water, and trace element ratios of drip water and cave air parameters. Drip sites are above growing speleothems offering the unique chance to calibrate geochemical variations in speleothems in order to reconstruct past climate conditions. Seasonal rainfall patterns above Cueva Larga show characteristic stable isotope values. The wet season is characterized by more negative δ18O and δD values and a maritime deuterium excess (+10‰). The dry season has more positive δ18O and δD values and elevated deuterium excess (>15…
Les phénols de la lignine et le 13C, traceurs de l'origine des matières organiques du sol
2001
Abstract In spodosols of Gascony (France), conversion of maritime pine stands into maize cropping leads to an incorporation of maize organic matter, which changed the isotopic (δ13C) and phenolic signature in A and L horizons of soil. Hydrolysis of phenol lignin in forests and cultivated soils showed the predominance of vanillic units under forest and the early but moderate incorporation of cinnamic acids. Incorporation of syringic units appeared higher, related to a large maize production of stable syringic phenols. Syringic units represented a long-term marker of maize inputs in soils, whereas vanillic units revealed the degradation of forest organic matter.