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Peer Reviewed
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

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See detailCarbonate chemistry in the coastal zone responds more strongly to eutrophication than to ocean acidification
Borges, Alberto ULg; Gypens, N.

in Limnology & Oceanography (2010), 55(1), 346-353

The accumulation of anthropogenic CO2 in the ocean has altered carbonate chemistry in surface waters since preindustrial times and is expected to continue to do so in the coming centuries. Changes in ... [more ▼]

The accumulation of anthropogenic CO2 in the ocean has altered carbonate chemistry in surface waters since preindustrial times and is expected to continue to do so in the coming centuries. Changes in carbonate chemistry can modify the rates and fates of marine primary production and calcification. These modifications can in turn lead to feedback on increasing atmospheric CO2. We show, using a numerical model, that in highly productive nearshore coastal marine environments, the effect of eutrophication on carbon cycling can counter the effect of ocean acidification on the carbonate chemistry of surface waters. Also, changes in river nutrient delivery due to management regulation policies can lead to stronger changes in carbonate chemistry than ocean acidification. Whether antagonistic or synergistic, the response of carbonate chemistry to changes of nutrient delivery to the coastal zone (increase or decrease, respectively) is stronger than ocean acidification. [less ▲]

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See detailCarbonate dissolution in the turbid and eutrophic Loire estuary
Abril, Gwenaël; Etcheber, Henri; Delille, Bruno ULg et al

in Marine Ecology. Progress Series (2003), 259

We measured particulate and dissolved organic carbon (POC and DOC), chlorophyll, oxygen, partial pressure of Co-2, pH, total alkalinity (TAlk) and particulate inorganic carbon (PIC) during a late summer ... [more ▼]

We measured particulate and dissolved organic carbon (POC and DOC), chlorophyll, oxygen, partial pressure of Co-2, pH, total alkalinity (TAlk) and particulate inorganic carbon (PIC) during a late summer cruise in the eutrophic Loire estuary. These parameters reveal an intense mineralisation of organic matter in the estuarine maximum turbidity zone (MTZ) that results in oxygen deficits (down to 20% of the saturation level) and high CO2 oversaturations (pCO(2) up to 2900 muatm). Several facts revealed the occurrence of carbonate dissolution in the Loire MTZ: large amounts of alkalinity were produced in the upper estuary, increasing its transfer to the ocean by 30%; the calculated saturation index showed a net undersaturation for aragonite and a slight undersaturation for calcite in the MTZ; and PIC decreased from 2.1% (% dry weight) in riverine suspension to 0.4% in the MTZ. A stoichiometric approach is used to assess the coupling between aerobic respiration and carbonate dissolution, where apparent oxygen utilisation, excess CO2, TAlk and dissolved inorganic carbon are compared quantitatively. About 20%, of the CO2 generated by respiration was involved in carbonate dissolution. The loss of PIC at the river-estuary transition quantitatively corresponds to the amount of authigenic calcite precipitated upstream in the highly eutrophic river. This suggests that CO2 exchange with the atmosphere along the eutrophic river-estuary continuum is buffered by carbonate precipitation in the autotrophic river and its dissolution in the heterotrophic estuary. [less ▲]

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See detailCarbonate Mounds: from Paradox to World Heritage
Henriet, Jean-Pierre; Hamoumi, N.; Da Silva, Anne-Christine ULg et al

in Marine Geology (2014), 352

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See detailThe carbonate system in the North Sea: sensitivity and model validation
Artioli, Y.; Blackford, J.C.; Butenschön, M. et al

in Journal of Marine Systems (2012), 102-104

The ocean plays an important role in regulating the climate, acting as a sink for carbon dioxide, perturbing the carbonate system and resulting in a slow decrease of seawater pH. Understanding the ... [more ▼]

The ocean plays an important role in regulating the climate, acting as a sink for carbon dioxide, perturbing the carbonate system and resulting in a slow decrease of seawater pH. Understanding the dynamics of the carbonate system in shelf sea regions is necessary to evaluate the impact of Ocean Acidification (OA) in these societally important ecosystems. Complex hydrodynamic and ecosystem coupled models provide a method of capturing the significant heterogeneity of these areas. However rigorous validation is essential to properly assess the reliability of such models. The coupled model POLCOMS–ERSEM has been implemented in the North Western European shelf with a new parameterization for alkalinity explicitly accounting for riverine inputs and the influence of biological processes. The model has been validated in a like with like comparison with North Sea data from the CANOBA dataset. The model shows good to reasonable agreement for the principal variables, physical (temperature and salinity), biogeochemical nutrients) and carbonate system (dissolved inorganic carbon and total alkalinity), but simulation of the erived variables, pH and pCO2, are not yet fully satisfactory. This high uncertainty is attributed mostly o riverine forcing and primary production. This study suggests that the model is a useful tool to provide information on Ocean Acidification scenarios, but uncertainty on pH and pCO2 needs to be reduced, particularly when impacts of OA on ecosystem functions are included in the model systems. [less ▲]

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See detailCarbonate system in the water masses of the Southeast Atlantic sector of the Southern Ocean during February and March 2008
Gonzalez-Davila, M.; Santana-Casiano, J. M.; Fine, R. A. et al

in Biogeosciences (2011), 8

Carbonate system variables were measured in the South Atlantic sector of the Southern Ocean along a transect from South Africa to the southern limit of the Antarctic Circumpolar Current (ACC) from ... [more ▼]

Carbonate system variables were measured in the South Atlantic sector of the Southern Ocean along a transect from South Africa to the southern limit of the Antarctic Circumpolar Current (ACC) from February to March 2008. Eddies detached from the retroflection of the Agulhas Current increased the gradients observed along the fronts. Minima in the fugacity of CO2, fCO2, and maxima in pH on either side of the frontal zone were observed, noting that within the frontal zone fCO2 reached maximum values and pH was at a minimum. Vertical distributions of water masses were described by their carbonate system properties and their relationship to CFC concentrations. Upper Circumpolar Deep Water (UCDW) and Lower Circumpolar Deep Water (LCDW) offered pHT,25 values of 7.56 and 7.61, respectively. The UCDW also had higher concentrations of CFC-12 (>0.2 pmol kg−1) as compared to deeper waters, revealing that UCDW was mixed with recently ventilated waters. Calcite and aragonite saturation states (Ω) were also affected by the presence of these two water masses with high carbonate concentrations. The aragonite saturation horizon was observed at 1000 m in the subtropical area and north of the Subantarctic Front. At the position of the Polar Front, and under the influence of UCDW and LCDW, the aragonite saturation horizon deepened from 800 m to 1500 m at 50.37° S, and reached 700 m south of 57.5° S. High latitudes proved to be the most sensitive areas to predicted anthropogenic carbon increase. Buffer coefficients related to changes in [CO2], [H+] and Ω with changes in dissolved inorganic carbon (CT) and total alkalinity (AT) offered minima values in the Antarctic Intermediate Water and UCDW layers. These coefficients suggest that a small increase in CT will sharply decrease the status of pH and carbonate saturation. Here we present data that suggest that south of 55° S, surface water will be under-saturated with respect to aragonite within the next few decades. [less ▲]

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