Search results for "GENI"

Gravity-driven stratal pattern in late orogenic extensional setting: an example from north-eastern Sicily

2008

Integrative analysis of the mineralogical and chemical composition of modern microbialites from ten Mexican lakes: What do we learn about their forma…

2021

International audience; Interpreting the environmental conditions under which ancient microbialites formed relies upon comparisons with modern analogues. This is why we need a detailed reference framework relating the chemical and mineralogical compositions of modern microbialites to the physical and chemical parameters prevailing in the environments where they form. Here, we measured the chemical, including major and trace elements, and mineralogical composition of microbialites from ten Mexican lakes as well as the chemical composition of the surrounding waters. Saturation states of lakes with different mineral phases were systematically determined and correlations between solution and so…

Cryo-EM structure of ssDNA bacteriophage ΦCjT23 provides insight into early virus evolution.

2022

AbstractThe origin of viruses remains an open question. While lack of detectable sequence similarity hampers the analysis of distantly related viruses, structural biology investigations of conserved capsid protein structures facilitate the study of distant evolutionary relationships. Here we characterize the lipid-containing ssDNA temperate bacteriophage ΦCjT23, which infects Flavobacterium sp. (Bacteroidetes). We report ΦCjT23-like sequences in the genome of strains belonging to several Flavobacterium species. The virion structure determined by cryogenic electron microscopy reveals similarities to members of the viral kingdom Bamfordvirae that currently consists solely of dsDNA viruses wit…

Derivation of a Homogenized Two-Temperature Model from the Heat Equation

2014

This work studies the heat equation in a two-phase material with spherical inclusions. Under some appropriate scaling on the size, volume fraction and heat capacity of the inclusions, we derive a coupled system of partial differential equations governing the evolution of the temperature of each phase at a macroscopic level of description. The coupling terms describing the exchange of heat between the phases are obtained by using homogenization techniques originating from [D. Cioranescu, F. Murat: Coll\`ege de France Seminar vol. 2. (Paris 1979-1980) Res. Notes in Math. vol. 60, pp. 98-138. Pitman, Boston, London, 1982.]

Aqueous Corrosion of the GeSe4 Chalcogenide Glass: Surface Properties and Corrosion Mechanism

2009

International audience; The aqueous corrosion behavior of the GeSe4 glass composition has been studied over time under various conditions (temperature and pH). The evolution of the surface topography by atomic force microscopy and properties such as surface hardness and reduced modulus, as well as the optical transmission in the 1-16 μm window, have been measured as a function of time spent in the corrosive solution. It was found that even if the glass reacts at room temperature, its optical transparency was barely affected. Nevertheless, the durability of GeSe4 was found to be drastically affected by an increase of both temperature and pH. Furthermore, pure selenium nanoparticles were form…

Positron trapping defects in free-volume investigation of Ge–Ga–S–CsCl glasses

2016

Abstract Evolution of free-volume positron trapping defects caused by crystallization process in (80GeS 2 –20Ga 2 S 3 ) 100−х (СsCl) x , 0 ≤ x ≤ 15 chalcogenide-chalcohalide glasses was studied by positron annihilation lifetime technique. It is established that CsCl additives in Ge–Ga–S glassy matrix transform defect-related component spectra, indicating that the agglomeration of free-volume voids occurs in initial and crystallized (80GeS 2 –20Ga 2 S 3 ) 100−х (СsCl) x , 0 ≤ x ≤ 10 glasses. Void fragmentation in (80GeS 2 –20Ga 2 S 3 ) 85 (СsCl) 15 glass can be associated with loosing of their inner structure. Full crystallization in each of these glasses corresponds to the formation of defe…

Montanacin-L and montanacin-K two previously non-described acetogenins from Annona montana twigs and leaves

2020

A phytochemical study on Annona montana twigs and leaves led to the isolation of eleven annonaceous acetogenins, including two previously non-described compounds, montanacin-L and montanacin-K. Their structures were elucidated by extensive analyses of spectroscopic data (IR, UV, HRTOFMS, EI-MS and 1H, 13C and 2D NMR). The ACGs montanacin-L, montanacin-K, montanacin-D and montanacin-E were evaluated for their toxicity against Spodoptera frugiperda Smith (Lepidoptera: Noctuidae). Results revealed that montanacin-D and montanacin-K exhibited insecticide action. Fil: Ruiz Hidalgo, José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; …

The behaviour of zirconium, hafnium and rare earth elements during the crystallisation of halite and other salt minerals

2017

Abstract Halite crystals from Messinian and Tortonian evaporites from Sicily and Spain and current precipitated halite crystals and the relative parent brines (active evaporation systems) were investigated in order to evaluate the Zr, Hf and Rare Earth Element (REE) behaviour. Halite crystallisation from evaporating brines fractionates Zr, Hf and REE through a two-step process. During the first step, dissolved complexes of studied elements are scavenged onto the surfaces of crystallising halite. During the second step, elements are co-precipitated into the crystal lattice as it grows. The first step mechanism is determined by the dissolved REE speciation. In saltworks where carbonate-REE co…

Rare earths behaviour during the deposition of volcanic sublimates

2017

Abstract In this study, the REE distribution between volcanic fluids and related solids in fumaroles with temperatures ranging from approximately 100 to 421 °C was investigated in different geological scenarios. The treatment of geochemical REE data was carried out by calculating the REE enrichment factors (EF REE ) relative to the volcanic host rocks in studied sites under the assumption that the REE transport takes place as silicate aerosol in volcanic fluids. Shale-normalised REE concentrations in these fluids have been assessed to investigate whether the REE transport as aqueous complexes in water-saturated volcanic gas is reasonable. The REE behaviour in alkaline condensates according …

Anthropogenic lead distribution in soils under arable land and permanent grassland estimated by Pb isotopic compositions

2008

International audience; The role of land use on fate of metals in soils is poorly understood. In this work, we studied the incorporation of lead in two neighboring soils with comparable pedogenesis but under long-term different agricultural management. Distributions of anthropogenic Pb were assessed from concentrations and isotopic compositions determined on bulk horizon samples, systematical 5–10 cm increment samples, and on 24-h EDTA extracts. Minor amounts of anthropogenic lead were detected until 1-m depth under permanent grassland, linked to high earthworm activity. In arable land, exogenous Pb predominantly accumulated at depths <60 cm. Although the proximity between the two sites ens…