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See detailCatalytic reforming of biomass gasification tars with bimetallic catalysts
Claude, Vincent ULg; Vilasecca, Miriam; Heinrichs, Benoît ULg et al

Poster (2016, May)

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See detailCatalytic reforming of gasification tars with bi- and trimetallic catalysts optimized with organosilane precursors
Claude, Vincent ULg; Lambert, Stéphanie ULg

Poster (2017, March 07)

Biomass gasification is interesting for the production of CO + H2 from wastes and catalysts are necessary for tars degradation. Catalysts were synthesized by the sol-gel process to develop γ-Al2O3 doped ... [more ▼]

Biomass gasification is interesting for the production of CO + H2 from wastes and catalysts are necessary for tars degradation. Catalysts were synthesized by the sol-gel process to develop γ-Al2O3 doped with 10%wt of nickel and 2 wt.% of a second dopant (Co, Cu, Fe, Mn, Mo). Before their adding in AlOOH sol, metallic dopants were complexed with (OCH3)3-Si-(CH2)3-NH-(CH2)2-NH2 (EDAS) to increase their dispersion by cogelation between EDAS and AlOOH clusters. These catalysts were tested at 650°C for toluene reforming. [less ▲]

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See detailCatalytic transformation of CO2: from monomers to polymers
Alves, Margot ULg; Grignard, Bruno ULg; Boyaval, Amélie ULg et al

Conference (2016, May 24)

Valorising CO2 as a renewable C1 feedstock for producing added value building blocks is the scope of many academic and industrial researches. Carbon dioxide is a thermodynamically and kinetically stable ... [more ▼]

Valorising CO2 as a renewable C1 feedstock for producing added value building blocks is the scope of many academic and industrial researches. Carbon dioxide is a thermodynamically and kinetically stable molecule that can be converted into five membered cyclic carbonates by coupling with epoxides using organometallic complexes or organocatalysts. To date, the identification and development of highly efficient (organo)catalysts under mild experimental conditions still remains challenging. In particular, the synthesis of six membered cyclic carbonates by the CO2/oxetane coupling using such organocatalysts has never been reported to our knowledge. In this context, we developed a new highly efficient bicomponent homogeneous organocatalyst composed of an ammonium salt as the catalyst and fluorinated single or double hydrogen bond donor activators (HBD). First, the efficiency of this new organocatalyst for the fast and selective CO2/epoxide coupling was investigated through detailed kinetic studies by IR spectroscopy under pressure and results were compared with the most efficient organocatalysts reported in the literature. This study was completed by molecular modeling in order to elucidate the reaction mechanism. DFT calculations showed that the hexafluoroisopropanol functionalities of HBDs strengthened the proton donor capability and allowed a better stabilization by hydrogen bonding of the intermediates and transition states. Finally, the use of this dual organocatalyst was extended to the coupling of CO2 with less reactive oxetanes to produce hydroxyl telechelic oligocarbonates. [less ▲]

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See detailThe Catalytic, Glycosyl Transferase and Acyl Transferase Modules of the Cell Wall Peptidoglycan-Polymerizing Penicillin-Binding Protein 1b of Escherichia Coli
Terrak, Mohammed ULg; Ghosh, Tushar K.; van Heijenoort, Jean et al

in Molecular Microbiology (1999), 34(2), 350-364

The penicillin-binding protein (PBP) 1b of Escherichia coli catalyses the assembly of lipid-transported N-acetyl glucosaminyl-beta-1, 4-N-acetylmuramoyl-L-alanyl-gamma-D-glutamyl-(L)-meso-diaminopimelyl ... [more ▼]

The penicillin-binding protein (PBP) 1b of Escherichia coli catalyses the assembly of lipid-transported N-acetyl glucosaminyl-beta-1, 4-N-acetylmuramoyl-L-alanyl-gamma-D-glutamyl-(L)-meso-diaminopimelyl+ ++- (L)-D-alanyl-D-alanine disaccharide pentapeptide units into polymeric peptidoglycan. These units are phosphodiester linked, at C1 of muramic acid, to a C55 undecaprenyl carrier. PBP1b has been purified in the form of His tag (M46-N844) PBP1bgamma. This derivative provides the host cell in which it is produced with a functional wall peptidoglycan. His tag (M46-N844) PBP1bgamma possesses an amino-terminal hydrophobic segment, which serves as transmembrane spanner of the native PBP. This segment is linked, via an congruent with 100-amino-acid insert, to a D198-G435 glycosyl transferase module that possesses the five motifs characteristic of the PBPs of class A. In in vitro assays, the glycosyl transferase of the PBP catalyses the synthesis of linear glycan chains from the lipid carrier with an efficiency of congruent with 39 000 M-1 s-1. Glu-233, of motif 1, is central to the catalysed reaction. It is proposed that the Glu-233 gamma-COOH donates its proton to the oxygen atom of the scissile phosphoester bond of the lipid carrier, leading to the formation of an oxocarbonium cation, which then undergoes attack by the 4-OH group of a nucleophile N-acetylglucosamine. Asp-234 of motif 1 or Glu-290 of motif 3 could be involved in the stabilization of the oxocarbonium cation and the activation of the 4-OH group of the N-acetylglucosamine. In turn, Tyr-310 of motif 4 is an important component of the amino acid sequence-folding information. The glycosyl transferase module of PBP1b, the lysozymes and the lytic transglycosylase Slt70 have much the same catalytic machinery. They might be members of the same superfamily. The glycosyl transferase module is linked, via a short junction site, to the amino end of a Q447-N844 acyl transferase module, which possesses the catalytic centre-defining motifs of the penicilloyl serine transferases superfamily. In in vitro assays with the lipid precursor and in the presence of penicillin at concentrations sufficient to derivatize the active-site serine 510 of the acyl transferase, the rate of glycan chain synthesis is unmodified, showing that the functioning of the glycosyl transferase is acyl transferase independent. In the absence of penicillin, the products of the Ser-510-assisted double-proton shuttle are glycan strands substituted by cross-linked tetrapeptide-pentapeptide and tetrapeptide-tetrapeptide dimers and uncross-linked pentapeptide and tetrapeptide monomers. The acyl transferase of the PBP also catalyses aminolysis and hydrolysis of properly structured thiolesters, but it lacks activity on D-alanyl-D-alanine-terminated peptides. This substrate specificity suggests that carbonyl donor activity requires the attachment of the pentapeptides to the glycan chains made by the glycosyl transferase, and it implies that one and the same PBP molecule catalyses transglycosylation and peptide cross-linking in a sequential manner. Attempts to produce truncated forms of the PBP lead to the conclusion that the multimodular polypeptide chain behaves as an integrated folding entity during PBP1b biogenesis. [less ▲]

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See detailCatalytically-inactive human cathepsin D triggers fibroblast invasive growth.
Laurent-Matha, V.; Maruani-Herrmann; Glondu, M. et al

in Journal of Cell Biology (2005), 168(3), 489-99

The aspartyl-protease cathepsin D (cath-D) is overexpressed and hypersecreted by epithelial breast cancer cells and stimulates their proliferation. As tumor epithelial–fibroblast cell interactions are ... [more ▼]

The aspartyl-protease cathepsin D (cath-D) is overexpressed and hypersecreted by epithelial breast cancer cells and stimulates their proliferation. As tumor epithelial–fibroblast cell interactions are important events in cancer progression, we investigated whether cath-D overexpression affects also fibroblast behavior. We demonstrate a requirement of cath-D for fibroblast invasive growth using a three-dimensional (3D) coculture assay with cancer cells secreting or not pro-cath-D. Ectopic expression of cath-D in cath-D–deficient fibroblasts stimulates 3D outgrowth that is associated with a significant increase in fibroblast proliferation, survival, motility, and invasive capacity, accompanied by activation of the ras–MAPK pathway. Interestingly, all these stimulatory effects on fibroblasts are independent of cath-D proteolytic activity. Finally, we show that pro-cath-D secreted by cancer cells is captured by fibroblasts and partially mimics effects of transfected cath-D. We conclude that cath-D is crucial for fibroblast invasive outgrowth and could act as a key paracrine communicator between cancer and stromal cells, independently of its catalytic activity. [less ▲]

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See detailCatamenial Pneumothorax: A Case Report and Review of the Literature
Pappalardo, E.; LAUNGANI, Alexis ULg; DURIEUX, Rodolphe ULg et al

in Acta Chirurgica Belgica (2007), 107(6, Nov-Dec), 695-6

Catamenial pneumothorax is a rare condition that is often misdiagnosed. It is defined as spontaneous pneumothorax occuring within 72 hours before or after onset of menstruation. Etiology is unknown but ... [more ▼]

Catamenial pneumothorax is a rare condition that is often misdiagnosed. It is defined as spontaneous pneumothorax occuring within 72 hours before or after onset of menstruation. Etiology is unknown but could be linked to endometriosis. Treatment is medicosurgical: thoracoscopy for pleural abrasion and hormonotherapy to avoid recurrence. [less ▲]

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See detailLe catastérisme chez Homère. Le cas d'Orion
Renaud, Jean-Michel ULg

in Gaia. Revue interdisciplinaire sur la Grèce archaïque (2003), 7

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See detailLe catastérisme d'Orion
Renaud, Jean-Michel ULg

in Bakhouche, Béatrice; Moreau, Alain; Turpin, Jean-Claude (Eds.) Les astres. Actes du Colloque International de Montpellier 23-25 mars 1995 (1996)

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See detailCatastrophe naturelle: Quand la communication se noie (c onfrontation Bénin / Tubize)
Ozer, Pierre ULg

Conference (2013, June 14)

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See detailCatastrophes naturelles et aménagement du territoire: de l’intérêt des images Google Earth dans les pays en développement
Ozer, Pierre ULg

in Geo-Eco-Trop : Revue Internationale de Géologie, de Géographie et d'Ecologie Tropicales (2014), 38(1), 209-220

More and more often, natural disasters linked to extreme weather events defined as extreme are charged to climate change. Here we demonstrate that -very often- these past, current or future disasters ... [more ▼]

More and more often, natural disasters linked to extreme weather events defined as extreme are charged to climate change. Here we demonstrate that -very often- these past, current or future disasters mainly result from the unexpected addition of human activities coupled with the lack of governance, through the non-application of laws and regulations relating to urban planning. To do this, in regions characterized by a patent lack of data, the use of satellite data available in open source via Google Earth can be a very effective tool to track certain processes (coastal erosion, gully erosion, urban sprawl in flood-prone areas) involved in the increasing risk. In addition, it is a very powerful educational tool to illustrate the speed of these phenomena that threaten property and people. To illustrate these assumptions, examples from Nouakchott (Mauritania) and Kinshasa (Democratic Republic of Congo) are successively presented [less ▲]

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See detailCatastrophic antiphospholipid syndrome : case reports and review of the literature
GUNTZ, Julien; LAYIOS, Nathalie ULg; DAMAS, Pierre ULg

in Acta Anaesthesiologica Belgica (2014), 65

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See detailCatastrophic thinking about pain increases discomfort during internal atrial cardioversion
Vlaeyen, Johan W S; Timmernans, Carl; Rodriguez, Luz-Maria et al

in Journal of Psychosomatic Research (2004), 56(1), 139-144

Objectives: This study investigated whether pain catastrophizing is associated with distress and perceived disability in patients with atrial fibrillation, whether pain catastrophizing predicts pain and ... [more ▼]

Objectives: This study investigated whether pain catastrophizing is associated with distress and perceived disability in patients with atrial fibrillation, whether pain catastrophizing predicts pain and fear during a medical procedure of atrial cardioversion, and whether pain catastrophizing influences the effects of an opioid analgesic during internal cardioversion. Methods: A secondary analysis is performed upon data from a double-blind placebo-controlled trial during which the effect of intranasal butorphanol tartrate (INB) was evaluated in patients with atrial fibrillation using a step-up internal atrial cardioversion protocol. Before the procedure, patients completed measures of pain catastrophizing, mood, distress and perceived disability. After each shock, patients completed measures of pain and fear. Results: We found that pain catastrophizing predicted the affective pain rating of the first shock, and the fear increase during subsequent shocks. There was no effect of INB. However, when controlling for the differences in pain catastrophizing, INB significantly reduced fear as compared to placebo. This suggests that the effects of INB during atrial cardioversion were overshadowed by the effects of pain catastrophizing. Conclusions: It is recommended that in future atrial cardioversion trials, stratification based on pain catastrophizing be performed. Reducing catastrophizing thinking about pain through cognitive-behavioral techniques are likely to reduce levels of fear during internal atrial cardioversion and may increase the effectiveness of concomitant analgesics. (C) 2004 Elsevier Inc. All rights reserved. [less ▲]

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See detailCatch the Minima - a Real Challenge on V348-SAGITTARII
Heck, A.; Manfroid, Jean ULg

in International Amateur-Professional Photoelectric Photometric Communications (1985)

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See detailCatch the Minima: A Real Challenge on V348 Sgr
Heck, A.; Manfroid, Jean ULg

in International Amateur-Professional Photoelectric Photometry Communications (1985), 20

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See detailCatching up with America. Productivity missions and the diffusion of American economic and technological influence after the Second World War.
Geerkens, Eric ULg

in Revue Belge de Philologie et d'Histoire (2006), 84(4), 1358-1361

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See detailCatchment modelling and sensitivity analysis to spatial interpolation methods of daily rainfall
Ly, Sarann ULg

Doctoral thesis (2012)

Spatial interpolation of precipitation data is of great importance for hydrological modelling. Geostatistical methods (kriging) are widely applied in spatial interpolation from point measurement to ... [more ▼]

Spatial interpolation of precipitation data is of great importance for hydrological modelling. Geostatistical methods (kriging) are widely applied in spatial interpolation from point measurement to continuous surfaces. The objective of this dissertation is to confront the performances of the several spatial interpolation methods, in particular the geostatistics for daily rainfall data in the nested catchments to realize a sensitivity analysis on discharges modelled at the outlets to the daily rainfall input in the modelling. The previous studies in the literature emphasized a requirement of novel investigation on the essential means to recover the rainfall data and eventually, the quality of the hydrological modelling. This study leaned on 30-year daily rainfall data of 70 raingages in the hilly landscape of the Ourthe and Ambleve catchments in Belgium (2908 km²). Two common deterministic methods are employed here. The Thiessen Polygon (THI) assigns the value from the nearest observation to a certain grid cell. The Inverse Distance Weighting (IDW) is an advanced nearest neighbour approach that allows including more observations than only the nearest points. The value at a certain grid cell is obtained from a linear combination of the surrounding locations. In the geostatistical algorithms, the spatial variation may be better described by a stochastic function. Four versions of kriging are used. The Ordinary Kriging (ORK) is the basic form of Kriging that the prediction is also a linear combination of the measured values. But the spatial correlation between the data, as described by the variogram, determines the weights, assuming that the mean is constant but unknown. The Universal Kriging (UNK) is based on the hypothesis that this mean is a polynomial function of spatial coordinates. So, this type of kriging is not stationary with regard to the mean. The Kriging with External Drift (KED) supposes that the mean of the interest variable depends on auxiliary variables; the theory of this kriging is in fact the same as the theory of UNK, which also contains a non-constant mean. The drift is defined externally through some auxiliary variables. The Ordinary Cokriging (OCK) suggests estimating the variable of interest by weighted linear combination of its observations and the observations of the auxiliary variables. This technique requires the study of the spatial dependence between variables besides the study of the simple spatial dependences. All types of kriging use a variogram model to characterise spatial correlation. A variogram describes in terms of variances how spatial variability changes as a function of distance. Seven semi-variogram models (logarithmic, power, exponential, Gaussian, rational quadratic, spherical and penta-spherical) were fitted to daily sample semi-variogram on a daily basis. These seven variogram models were also adopted to avoid negative interpolated rainfall. The elevation, extracted from a digital elevation model, was incorporated into multivariate geostatistics. Seven validation raingages and cross validation were used to compare the interpolation performance of these algorithms applied to different densities of raingages. The areal rainfalls are calculated for the catchment area and used for analysis of extreme rainfall. The effects of the interpolation methods on the extreme rainfall are analysed. The interpolated rainfalls are also used as rainfall input of the physically-based and distributed EPIC-GRID model. The long series of model results are analysed by comparison with the observed discharges at the different outlets of the catchments. Then, the extreme discharges at the outlets are computed. All of these investigations always take into account of the raingage density and the raingage position for very sparse raingage cases. The main results show that among the methods based on the only rainfall data, the geostatistics and IDW are the best ones. The performances change according to the density of the raingages. For the extreme rainfall and long term modelling results, no big difference is found for a high density of raingage but large difference are found for the case of the scattered raingage. For the latter case, UNK and KED are very sensitive to the position of the raingages. IDW, ORK and OCK are found to be the best performance. However for the extreme flow, KED and OCK is the best whereas IDW is not better for the high density of the raingages. For the case of the scattered raingages, the difference in extreme discharge between the interpolation methods is very large and larger than shown in the extreme rainfall and the long term modelling results. IDW, ORK and OCK always perform better. UNK and KED still are sensitive to the positions of raingages. The index of position is used to describe the form of polygon defined by the four raingages. This index is defined as the relation between the polygon perimeter and a circle perimeter having an area equivalent to that of the polygon. The best raingage position for all interpolation methods used in this research should be arround the catchment area, its index should be close to one. [less ▲]

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See detailCatéchisme correct d'astronomie sphérique
Folie, François ULg

in Memorie della Pontificia Accademia dei Nuovi Lincei (1894), 1 et 2(9-10), 93

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See detailLe catéchisme et la grammaire
Kurth, Godefroid ULg

Conference given outside the academic context (1896)

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