Search results for "MATTER"
showing 10 items of 16762 documents
Détection d'endommagement dans les composites à l'aide de la technologie micro-onde
2007
6-8 juin 2007; National audience
Formation of microbial organic carbonates during the Late Jurassic from the Northern Tethys (Amu Darya Basin, Uzbekistan): implications for Jurassic …
2020
23 pages; International audience; The Late Jurassic was a period of major global carbon cycle perturbations with episodes of anoxia leading to regional accumulation of organic matter in sediments worldwide. The Tubiegatan section (SW Gissar Mountains, Uzbekistan) located in the Northern Tethys, shows atypical organic-rich limestone and marl deposits (up to 6% of total organic carbon) marked by pronounced negative excursions of δ13Ccarb (amplitude of ca. 12‰) and δ13Corg (amplitude of ca. 4‰) recorded during the Middle Oxfordian (Transversarium Zone). A transdisciplinary approach including sedimentology, palynofacies characterization, mineralogy, organic and inorganic geochemistry was carrie…
Response of Soil Microbial Communities to Iron-Porphyrin Catalytic Amendments.
2010
Intensive agricultural practices strongly increase CO2 emission from soil. Synthetic metal-porphyrins were shown to significantly decreased CO2 emission from soil due to an in-situ catalysis of oxidative polymerization of soil organic matter. This research aimed to assess the effects of iron-porphyrin (POR) amendments on soil microbial communities in three arable soils under wheat and maize cropping located in Naples, Turin and Piacenza, characterized by different pedological and climatic conditions. Bulk-soil and rhizo-soil were sampled during 4 years and the microbial groups directly involved in organic matter (OM) mineralization and in key processes of the nitrogen cycle were examined. M…
Microwave response of bulk MgB2 samples of different granularity
2006
The microwave response of three high-density bulk MgB2 samples has been investigated in the linear and nonlinear regimes. The three samples, characterized by different mean size of grains, have been obtained by reactive infiltration of liquid Mg in powdered B preforms. The linear response has been studied by measuring the microwave surface impedance; the nonlinear response by detecting the power radiated by the sample at the second-harmonic frequency of the driving field. Our results suggest that bulk MgB2 prepared by the liquid Mg infiltration technique is particularly promising for manufacturing resonant cavities operating at microwave frequencies.
Analytical models for the pulse shape of a superconductor-ferromagnet tunnel junction thermoelectric microcalorimeter
2022
AbstractThe superconductor-ferromagnet thermoelectric detector (SFTED) is a novel ultrasensitive radiation detector based on the giant thermoelectric effect in superconductor-ferromagnet tunnel junctions. We demonstrate analytical models and solutions in the time domain for a SFTED operated as a microcalorimeter (pulse excitation), in the linear small-signal limit. Based on these solutions, the signal current and temperature pulse response were studied for two different electrical circuit models, providing design conditions for stable and non-oscillatory response.Kindly check and confirm whether the corresponding author is correctly identified.The corresponding author is correct.
Revisiting the disappearance of terrestrial dissolved organic matter in the ocean: A δ13C study
2014
Abstract. Organic carbon (OC) depleted in 13 C is a widely used tracer for terrestrial organic matter (OM) in aquatic sys- tems. Photochemical reactions can, however, change δ 13 C of dissolved organic carbon (DOC) when chromophoric, aromatic-rich terrestrial OC is selectively mineralized. We assessed the robustness of the δ 13 C signature of DOC ( δ 13 C DOC ) as a tracer for terrestrial OM by estimating its change during the photobleaching of chromophoric DOM (CDOM) from 10 large rivers. These rivers cumulatively ac- count for approximately one-third of the world’s freshwater discharge to the global ocean. Photobleaching of CDOM by simulated solar radiation was associated with the photoch…
Micelles in Mixtures of Sodium Dodecyl Sulfate and a Bolaform Surfactant
2006
Mixtures composed of water, sodium dodecyl sulfate (SDS), and a bolaform surfactant with two aza-crown ethers as polar headgroups (termed Bola C-16) were investigated by modulating the mole ratios between the components. The two surfactants have ionic and nonionic, but ionizable, headgroups, respectively. The ionization is due to the complexation of alkali ions by the aza-crown ether unit(s). Structural, thermodynamic, and transport properties of the above mixtures were investigated. Results from surface tension, translational self-diffusion, and small angle neutron scattering ( SANS) are reported and discussed. Interactions between the two surfactants to form mixed micelles result in a com…
Análisis del modelo de concordancia
2010
En cosmología, el modelo más simple que explica las observa- ciones realizadas sobre las supernovas Ia, sobre el fondo de microon- das, y sobre la estructura del universo a gran escala, es el modelo conocido como modelo concordante o modelo Lambda Cold Dark Matter. Este modelo comunmente aceptado por la comunidad científica, basa sus explicaciones en la aceptación de: • La existencia de una constante cosmológica Λ descrita en tér- minos de fracción de densidad como Ω Λ y que representa a la energía oscura, responsable de la aceleración de la expansión del universo. • Materia oscura fria, modelizada como materia no bariónica y no termalizada, es decir en ausencia de colisiones. • Se asume un…
Polymorphism and Metallic Behavior in BEDT-TTF Radical Salts with Polycyano Anions
2012
Up to five different crystalline radical salts have been prepared with the organic donor BEDT-TTF and three different polynitrile anions. With the polynitrile dianion tcpd2− (=C[C(CN)2]32−), two closely related radical salts: α'-(ET)4tcpd·THF (1) (THF = tetrahydrofurane) and α'-(ET)4tcpd·H2O (2) have been prepared, depending on the solvent used in the synthesis. With the mono-anion tcnoetOH− (=[(NC)2CC(OCH2CH2OH)C(CN)2]−) two polymorphs with similar physical properties but different crystal packings have been synthesized: θ-(ET)2(tcnoetOH) (3) and β''-(ET)2(tcnoetOH) (4). Finally, with the mono-anion tcnoprOH− (=[(NC)2CC(OCH2CH2CH2OH)C(CN)2]−) we have prepared a metallic…
Enhancing Light Emission in Interface Engineered Spin-OLEDs through Spin-Polarized Injection at High Voltages
2019
The quest for a spin-polarized organic light-emitting diode (spin-OLED) is a common goal in the emerging fields of molecular electronics and spintronics. In this device, two ferromagnetic (FM) electrodes are used to enhance the electroluminescence intensity of the OLED through a magnetic control of the spin polarization of the injected carriers. The major difficulty is that the driving voltage of an OLED device exceeds a few volts, while spin injection in organic materials is only efficient at low voltages. The fabrication of a spin-OLED that uses a conjugated polymer as bipolar spin collector layer and ferromagnetic electrodes is reported here. Through a careful engineering of the organic/…