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See detailCarbon stars, comets and combustion phenomena
Rosen, B.; Swings, Polydore ULg

in Annales d'astrophysique (1953), 16

La question de l'identification de la molécule responsable pour l'émission du « groupe 4 050 » dans les comètes et les sources terrestres et pour l'absorption de ce groupe dans les atmosphères des étoiles ... [more ▼]

La question de l'identification de la molécule responsable pour l'émission du « groupe 4 050 » dans les comètes et les sources terrestres et pour l'absorption de ce groupe dans les atmosphères des étoiles carbonées du type N avancé est examinée en détail. Les relations entre l'émission et l'absorption de ce groupe et les phénomènes observés dans les décharges, flammes et explosions ainsi qu'en pyrolyse et photolyse sont discutées. L'attention est attirée en particulier sur le fait que l'émission et l'absorption du « groupe 4 050 » sont toujours liées à la formation de particules de carbone (suie). Des arguments sont présentés en faveur de l'attribution de ce groupe (pour lequel un nouveau schéma vibrationnel est proposé) à la molécule C3. Le rôle possible des particules de carbone dans les atmosphères des étoiles du type N avancé a été discuté. La possibilité a été envisagée d'interpréter la formation des molécules responsables pour l'émission du « groupe 4 050 » dans les comètes par collision de protons d'origine solaire avec les surfaces des glaces organiques des noyaux ou avec des molécules carbonées sublimées qui se trouvent à proximité de ces surfaces. [less ▲]

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See detailCarbon stocks and isotopic budgets of the terrestrial biosphere at mid-Holocene and last glacial maximum times
François, Louis ULg; Godderis, Y.; Warnant, Pierre ULg et al

in Chemical Geology (1999), 159(1-4), 163-189

The carbon fluxes, stocks and isotopic budgets of the land biosphere at mid-Holocene (6 ka BP) and last glacial maximum (21 ka BP) times are reconstructed with the CARbon Assimilation In the Biosphere ... [more ▼]

The carbon fluxes, stocks and isotopic budgets of the land biosphere at mid-Holocene (6 ka BP) and last glacial maximum (21 ka BP) times are reconstructed with the CARbon Assimilation In the Biosphere (CARATB) model forced with two different sets of climates simulated by the European Centre-HAMburg (ECHAM) and LMD general circulation models. It is found that the trends predicted on the basis of both sets of GCM climatic fields are generally consistent with each other, although substantial discrepancies in the magnitude of the changes may be observed. Actually, these discrepancies in the biospheric results associated with the use of different GCM climatic fields are usually smaller than the differences between biospheric runs performed while considering or neglecting the CO2 fertilization effect (which might, however, be overestimated by the model due to uncertainties concerning changes in nutrient availability). The calculated changes with respect to the present of the biosphere carbon stock range from - 132 to + 92 Gt C for the mid-Holocene and from -710 to +70 Gt C for the last glacial maximum. It is also shown that the relative contribution of the material synthesized by C-4 plants to the total biomass of vegetation, litter and soils was substantially larger at mid-Holocene and last glacial maximum times than today. This change in the relative importance of the C-3 and C-4 photosynthetic pathways induced changes in the C-13 fractionation of the land biosphere. These changes in the average biospheric fractionation resulting from the redistribution of C-3 and C-4 plants were partly compensated for by changes of opposite sign in the fractionation of C-3 plants due to the modification of the intercellular CO2 pressure within their leaves. With respect to present times, the combination of both processes reduced the C-13 discrimination (i.e., less negative fractionation) of the land biosphere by 0.03 to 0.32 parts per thousand during the mid-Holocene and by 0.30 to 1.86 parts per thousand at the last glacial maximum. (C) 1999 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailCarbon substrate utilization and microbial biomass in European forest soils are related to tree species diversity
Carnol, Monique ULg; Baeten, Lander; Bosman, Bernard ULg et al

Poster (2015, December)

Tree species influence biogeochemical cycling through element deposition (throughfall, litterfall), root decomposition and exudates, and through their influence on the microbial activities in the soil ... [more ▼]

Tree species influence biogeochemical cycling through element deposition (throughfall, litterfall), root decomposition and exudates, and through their influence on the microbial activities in the soil. Yet, the effect of mixing tree species on soil functioning is unclear, in particular concerning the microbial diversity and activity in soils. Here we synthesize results from the Exploratory Platform of the FunDivEUROPE project (http://www.fundiveurope.eu/). This network of 209 comparative plots covering tree diversity levels of 1 to 5 species was established in existing mature forests in 6 European regions. These six focal regions represent a gradient of major European forest types from boreal to Mediterranean forests. The aims of this study were to determine the soil microbial biomass and metabolic diversity of soil bacteria for these 6 European forest regions, presenting each a tree species richness gradient and to analyse the impact of tree species richness and the role of other controlling factors. We analysed the relation between tree species diversity, the proportion of coniferous tree species and soil factors (pH, soil organic carbon, water soluble carbon and nitrogen) and the carbon substrate utilisation pattern of soil bacteria (BIOLOG Ecoplate), soil microbial biomass (fumigation-extraction), hot water carbon and nitrogen in the forest floor and the upper mineral soil horizon (linear mixed models, GLM for multivariate abundance data, discriminant correspondence analysis). Mean values of microbial biomass carbon ranged from 3264 (Italy) to 8717 (Finland) mg kg-1 in the forest floor and from 465 (Italy) to 3748 (Finland) mg kg-1 in the mineral soil. Statistical models predicted microbial biomass to increase in both soil layers by 7-8% with each step increase in tree diversity. Increased proportion of conifers was linked to a decrease in the number of carbon substrates used by soil bacteria. The types of carbon sources used were dependent on region, proportion of conifers, soil pH and water-soluble carbon and nitrogen. [less ▲]

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See detailCarbon Supply and Photoacclimation Cross Talk in the Green Alga Chlamydomonas reinhardtii.
Polukhina, I; Fristedt, R; Dinc, E et al

in Plant Physiology (2016), 172(3), 1494-1505

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See detailCarbon xerogels as catalyst supports
Job, Nathalie ULg; Léonard, Angélique ULg; Lambert, Stéphanie ULg et al

Poster (2007, August)

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See detailCarbon xerogels as catalyst supports for PEM fuel cell cathode
Job, Nathalie ULg; Marie, J.; Lambert, Stéphanie ULg et al

in Energy Conversion and Management (2008), 49

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See detailCarbon xerogels as catalyst supports for PEM fuel cell cathode
Job, Nathalie ULg; Marie, Julien; Lambert, Stéphanie ULg et al

Conference (2007)

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See detailCarbon xerogels as catalyst supports: study of mass transfer
Job, Nathalie ULg; Heinrichs, Benoît ULg; Lambert, Stéphanie ULg et al

in AIChE Journal (2006), 52

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See detailCarbon xerogels as model materials: toward a relationship between pore texture and electrochemical behavior as anodes for lithium-ion batteries
Piedboeuf, Marie-Laure ULg; Léonard, Alexandre ULg; Deschamps, Fabien ULg et al

in Journal of Materials Science (2016), 51(9), 4358-4370

The mechanisms of Li+ insertion in porous hard carbons used as anodes for Li-ion batteries are still a matter of debate, especially considering the divergence of electrochemical performances observed in ... [more ▼]

The mechanisms of Li+ insertion in porous hard carbons used as anodes for Li-ion batteries are still a matter of debate, especially considering the divergence of electrochemical performances observed in literature. Since these materials usually exhibit several levels of porosity, the pore texture vs. electrochemical behavior relationship is difficult to establish. In this paper, we propose to use carbon xerogels, prepared from aqueous resorcinol-formaldehyde mixtures, as model materials for Li-ion battery anodes to study the influence of the pore texture on the overall electrochemical behavior. Indeed, carbon xerogels are described as microporous nodules linked together to form meso- or macroporous voids inside a 3D gel structure; the size of these voids can be tuned by changing the synthesis conditions without affecting other parameters such as the micropore volume. The materials are chosen so as to obtain identical average particle sizes, homogeneous coatings with similar thicknesses and a comparable surface chemistry. The electrochemical behavior of carbon xerogels as Li-ion anodes are correlated with the surface accessible to the electrolyte and are not dependent on the total specific surface area calculated by the BET method from nitrogen adsorption isotherms. The key parameter proposed to understand their behavior is the external surface area of the nodules, which corresponds to the surface of the meso/macropores. [less ▲]

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See detailCarbon xerogels as supports for catalysts and electrocatalysts
Job, Nathalie ULg; Berthon-Fabry, S.; Lambert, Stéphanie ULg et al

in Proceedings of the International Carbon Conference 2009 (2009)

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See detailCarbon xerogels as supports for catalysts and electrocatalysts
Job, Nathalie ULg; Berthon-Fabry, S.; Lambert, Stéphanie ULg et al

Conference (2009, June 14)

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See detailCarbon, nitrogen, oxygen and sulfide budgets in the Black Sea: A biogeochemical model of the whole water column coupling the oxic and anoxic parts
Grégoire, Marilaure ULg; Soetaert, Karline

in Ecological Modelling (2010)

Carbon, nitrogen, oxygen and sulfide budgets are derived for the Black Sea water column from a coupled physical-biogeochemical model. The model is applied in the deep part of the sea and simulates ... [more ▼]

Carbon, nitrogen, oxygen and sulfide budgets are derived for the Black Sea water column from a coupled physical-biogeochemical model. The model is applied in the deep part of the sea and simulates processes over the whole water column including the anoxic layer that extends from ~ 115 m to the bottom (~ 2000 m). The biogeochemical model involves a refined representation of the Black Sea foodweb from bacteria to gelatinous carnivores. It includes notably a series of biogeochemical processes typical for oxygen deficient conditions with, for instance, bacterial respiration using different types of oxidants (i.e denitrification, sulfate reduction), the lower efficiency of detritus degradation, the ANAMMOX (ANaerobic AMMonium OXidation) process and the occurrence of particular redox reactions. The model has been calibrated and validated against all available data gathered in the Black Sea TU Ocean Base and this exercise is described in Gregoire et al., (2008). In the present paper, we focus on the biogeochemical flows produced by the model and we compare model estimations with the measurements performed during the R.V. KNORR expedition conducted in the Black Sea from April to July 1988 (Murray and the Black Sea Knorr Expedition, 1991). Model estimations of hydrogen sulfide oxidation, metal sulfide precipitation, hydrogen sulfide formation in the sediments and water column, export flux to the anoxic layer and to the sediments, denitrification, primary and bacterial production are in the range of field observations. With a simulated Gross Primary Production (GPP) of 7.9 molC m-2 yr-1 and a Community Respiration (CR) of 6.3 molC m-2 yr-1, the system is net autotrophic with a Net Community Production (NCP) of 1.6 molC m-2 yr-1. This NCP corresponds to 20 % of the GPP and is exported to the anoxic layer. In order to model Particulate Organic Matter (POM) fluxes to the bottom and hydrogen sulfide profiles in agreement with in-situ observations, we have to consider that the degradation of POM in anoxic conditions is less efficient that in oxygenated waters as it has often been observed (see discussion in Hedges et al., 1999). The vertical POM profile produced by the model can be fitted to the classic power function describing the oceanic carbon rate (CR=Z-) using an attenuation coefficient  of 0.36 which is the value proposed for another anoxic environment (i.e. the Mexico Margin) by Devol and Hartnett, (2001). Due to the lower efficiency of detritus degradation in anoxic conditions and to the aggregation of particles that enhanced the sinking, an important part of the export to the anoxic layer (i.e. 33 %, 0.52 molC m-2 yr-1) escapes remineralization in the water column and reaches the sediments. Therefore, sediments are active sites of sulfide production contributing to 26 % of the total sulfide production. In the upper layer, the oxygen dynamics is mainly governed by photosynthesis and respiration processes as well as by air-sea exchanges. ~ 71 % of the oxygen produced by phytoplankton (photosynthesis + nitrate reduction) is lost through respiration, ~ 21 % by outgasing to the atmosphere, ~ 5 % through nitrification and only ~ 2 % in the oxidation of reduced components (e.g. Mn2+, Fe2+, H2S). The model estimates the amount of nitrogen lost through denitrification at 307 mmolN m-2 yr-1 that can be partitioned into a loss of ~ 55 % through the use of nitrate for the oxidation of detritus in low oxygen conditions, ~ 40 % in the ANAMMOX process and the remaining ~ 5% in the oxidation of reduced substances by nitrate. In agreement with data analysis performed on long time series collected since the 1960's (Konovalov and Murray, 2001), the sulfide and nitrogen budgets established for the anoxic layer are not balanced in response to the enhanced particle fluxes induced by eutrophication: the NH4 and H2S concentrations increase. [less ▲]

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See detailCarbon-isotope analysis of fossil wood and dispersed organic matter from the terrestrial Wealden facies of Hautrage (Mons Basin, Belgium).
Yans, Johan; Gerards, Thomas ULg; Gerrienne, Philippe ULg et al

in Palaeogeography, Palaeoclimatology, Palaeoecology (2010), 291

Detailed reference viewed: 31 (7 ULg)