Search results for "Geology"
showing 10 items of 6012 documents
The boson peak of deeply cooled confined water reveals the existence of a low-temperature liquid-liquid crossover.
2014
International audience; The Boson peak of deeply cooled water confined in the pores of a silica xerogel is studied by inelastic neutron scattering at different hydration levels to separate the contributions from matrix, water on the pore surfaces and "internal" water. Our results reveal that at high hydration level, where the contribution from internal water is dominant, the temperature dependence of the Boson peak intensity shows an inflection point at about 225 K. The complementary use of differential scanning calorimetry to describe the thermodynamics of the system allows identifying the inflection point as the signature of a water liquid-liquid crossover.
Carbon dynamics in highly heterotrophic subarctic thaw ponds
2015
Abstract. Global warming has accelerated the formation of permafrost thaw ponds in several subarctic and arctic regions. These ponds are net heterotrophic as evidenced by their greenhouse gas (GHG) supersaturation levels (CO2 and CH4), and generally receive large terrestrial carbon inputs from the thawing and eroding permafrost. We measured seasonal and vertical variations in the concentration and type of dissolved organic matter (DOM) in five subarctic thaw (thermokarst) ponds in northern Quebec, and explored how environmental gradients influenced heterotrophic and phototrophic biomass and productivity. Late winter DOM had low aromaticity indicating reduced inputs of terrestrial carbon, wh…
Investigating the Multi-Recyclability of Recycled Plastic-Modified Asphalt Mixtures
2023
Although the benefits of asphalt recycling have been scientifically proven and several best practices are being implemented, further research is required in specific and specialized areas. One of these circumstances is the recycling of Reclaimed Asphalt Pavements (RAPs) that contain asphalt modifiers such as elastomers and/or plastomers. Following the principles of the circular economy and considering the sustainability implications of asphalt mixtures, this paper deals with the multi-recyclability of asphalt mixtures containing 50% RAP with and without a recycled plastic asphalt modifier and rejuvenating agent. The recycled plastic asphalt modifier was made of hard recycled plastics and wa…
STOP 12: Late-glacial and Holocene development of Lake Rāzna as recorded by biostratigraphy
2014
Halogens and trace metal emissions from the ongoing 2008 summit eruption of Kīlauea volcano, Hawai`i
2012
Volcanic plume samples taken in 2008 and 2009 from the Halemàumàu eruption at Kīlauea provide new insights into Kīlauea's degassing behaviour. The Cl, F and S gas systematics are consistent with syn-eruptive East Rift Zone measurements suggesting that the new Halemàumàu activity is fed by a convecting magma reservoir shallower than the main summit storage area. Comparison with degassing models suggests that plume halogen and S composition is controlled by very shallow (<3m depth) decompression degassing and progressive loss of volatiles at the surface. Compared to most other global volcanoes, Kīlauea's gases are depleted in Cl with respect to S. Similarly, our Br/S and I/S ratio measurem…
Elemental and isotope covariation of noble gases in mineral phases from Etnean volcanics erupted during 2001–2005, and genetic relation with peripher…
2008
Abstract During 2001–2005, Mount Etna was characterized by intense eruptive activity involving the emission of petrologically different products from several vents, which involved at least two types of magma with different degrees of evolution. We investigated the ratios and abundances for noble-gas isotopes in fluid inclusions trapped in olivines and pyroxenes in the erupted products. We confirm that olivine has the most efficient crystalline structure for preserving the pristine composition of entrapped gases, while pyroxene can suffer diffusive He loss. Both the minerals also experience noble gas air contamination after eruption. Helium isotopes of the products genetically linked to the …
Fracture stratigraphy of Mesozoic platform carbonates, Agri Valley, southern Italy
2022
The outcropping platform carbonates form a layered succession crosscut by a dense array of bed-parallel pressure solution seams and veins, oblique-to-bedding pressure solution seams, and high-angle joints, veins, and pressure solution seams. Altogether, these structural elements form sub-seismic heterogeneities that formed during the polyphase tectonic evolution of the southern Apennines fold and-thrust belt, Italy. Aiming at assessing the role exerted by the primary carbonate architecture on failure modes and fracture geometry and distribution, we conduct a multi-disciplinary study by performing stratigraphic, petrographic, mineralogical, and mesoscale structural analyses. Based on carbona…
Molecular dynamics simulations of heavy ion induced defects in SiC Schottky diodes
2018
Heavy ion irradiation increases the leakage current in reverse-biased SiC Schottky diodes. This letter demonstrates, via molecular dynamics simulations, that a combination of bias and ion-deposited energy is required to produce the degradation. Peer reviewed
Los Mapas contables de gestión de las empresas cotizadas chilenas : análisis cualitativo
2017
espanolEl articulo analiza las clases de gestion realizadas por las empresas cotizadas chilenas localizadas en los espacios administrativos de Chile. La orientacion del analisis realizado considera que el factor cultural de la region donde estan localizadas las empresas chilenas condiciona la clase de gestion desarrollada por dichas empresas. El desarrollo de esta hipotesis se realiza aplicando la metodologia contable de los graficos radiales. Las tensiones existentes entre los periodos medios de maduracion representados en un grafico radial asumen la existencia de un factor cultural en las transacciones realizadas por las empresas en una region y supone que la toma de decision en un area t…
Towards a new marine structural model of Italy
2013
The exploitation of economic resources in marine environment and the assessment of natural hazards press a greater knowledge of the sea floor geology. Since the Structural Model of Italy was published in the 1991 by the CNR, new data have been collected concerning the marine geology of the sea floor surrounding Italy, also by means of up to date technologies (digital seismics, SBP Chirp, Multibeam). Data collected during the last decades in the frame of research programs as CROP MARE, CARG, morpho-bathymetric survey of the Tyrrhenian Sea, MAGIC, allow investigating the submerged geological structures with different temporal and spatial resolution. As consequence, at present marine geologist…