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Peer Reviewed
See detailLa catalyse enzymatique en milieu organique : potentialités d'utilisation des lipases.
Blecker, Christophe ULiege

in Bulletin des Recherches agronomiques de Gembloux (1993), 28(1), 51-85

Detailed reference viewed: 83 (11 ULiège)
See detailCatalyse fouronnaise
Verjans, Pierre ULiege

in La Wallonie, une Région en Europe (1997)

L'identité wallonne se construit en partie sur la cristallisation du cas fouronnais, illustrant la faiblesse et la ténacité supposées de la Wallonie face à la Flandre.

Detailed reference viewed: 8 (2 ULiège)
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See detailLa catalyse par les céramiques
Claude, Vincent ULiege

Speech/Talk (2015)

Présentation réalisée à l'Ecole Européenne d'Ingénieurs en Génie des Matériaux, Nancy. Introduction aux procédés sol-gel pour la synthèse d'inorganique et à la catalyse hétérogène.

Detailed reference viewed: 14 (0 ULiège)
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See detailCatalysis and Low Temperature: Molecular adaptations
Feller, Georges ULiege; Gerday, Charles ULiege

in EOLSS (Ed.) Encyclopedia of Life Support Systems (2002)

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See detailCatalyst consumption during growth of carbon nanofilaments on Pd seeds
Breton, Yannick; Fleurier, Romain; Salvetat, Jean-Paul et al

in Applied Physics Letters (2004), 85

Detailed reference viewed: 14 (2 ULiège)
See detailCatalysts - special issue 'Aerogel catalysts'
Job, Nathalie ULiege; Ioannides, Theophilos

Book published by MDPI (2012)

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See detailCatalytic activation of copper(II) salts on the reaction of peroxynitrite with propofol in alkaline medium
Kohnen, Stephan ULiege; Halusiak, Emilie ULiege; Mouithys-Mickalad, Ange ULiege et al

in Nitric Oxide (2005), 12(4), 252-260

We report here on the role of copper (II) salts on the acceleration of peroxynitrite (ONOO-) decomposition and ONOO- reaction with the anaesthetic agent propofol (2,6-diisopropylphenol) in alkaline medium ... [more ▼]

We report here on the role of copper (II) salts on the acceleration of peroxynitrite (ONOO-) decomposition and ONOO- reaction with the anaesthetic agent propofol (2,6-diisopropylphenol) in alkaline medium. We observed a strong acceleration of the ONOO- decomposition in alkaline medium in the presence of copper (I and II) salts. After 18 h of ONOO- reaction with propofol, we observed nitrosated, nitrated, and oxidized (quinone and diphenylquinone) derivatives of propofol, but in the presence of Cu(II) (20% molar vs ONOO-), the yields of quinone and nitrosopropofol strongly increased. We also observed that the temperature and the atmosphere influenced the effects of Cu(II) on ONOO- reactions with propofol: low temperatures promoted nitrosation and high temperatures promoted oxidation; O-2 atmosphere increased the general reactivity and the yield of nitrated and oxidized products. We highlighted the influence of Cu(II) salts on the radical character of the reaction by direct EPR technique. The exact mechanism of the Cu(II) catalysis remains unexplained, but we suggest the formation of a copper complex with propofol or, more probably, the oxidation of ONOO- into ONOO• by copper ions promoting the formation of quinone and nitrosopropofol according to a previously reported mechanism [M. Cudic, C. Ducrocq, Transformations of 2,6-diisopropylphenol by NO-derived nitrogen oxides, particularly peroxyrutrite, Nitric Oxide 4 (2000) 147-156]. © 2005 Elsevier Inc. All rights reserved. [less ▲]

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See detailThe catalytic activity and penicillin sensitivity in the liquid and frozen states of membrane-bound and detergent-solubilised transpeptidase of Streptomyces R61
Dusart, Jean; Marquet, Alberto; Ghuysen, Jean-Marie ULiege et al

in European Journal of Biochemistry (1975), 56(1), 57-65

The Km, app. values of the membrane-bound transpeptidase of Streptomyces R61 for the donor Ac2-L-Lys-D-Ala-D-Ala and the acceptor Gly-Gly are not affected by temperature variations when the reaction ... [more ▼]

The Km, app. values of the membrane-bound transpeptidase of Streptomyces R61 for the donor Ac2-L-Lys-D-Ala-D-Ala and the acceptor Gly-Gly are not affected by temperature variations when the reaction mixtures are incubated in liquid suspensions. At -5 degrees C, the incubation can be carried out either in the liquid or in the frozen state. The enzyme is active in the latter state. In the frozen state, the Km, app. value for the acceptor remains unchanged but there is a 3-fold increase in the maximum velocity, a 10-fold decrease of the Km, app. value for the donor and a 10-fold increase of the benzylpenicillin concentration required to inhibit the enzyme activity by 50% (ID50 value). Temperatures of -35 degrees C or below are required to completely inhibit the membrane-bound enzyme in the frozen state. Cetyltrimethylammonium bromide extracts the transpeptidase both from the isolated membranes and, with a much higher yield, from the intact mycelium. The extracted enzyme is not active in the frozen state, requires detergent for activity, has decreased Km, app. values for both donor and acceptor, exhibits the same sensitivity to benzylpenicillin and cephalosporin C as the membrane-bound transpeptidase (in liquid suspensions) and, like this latter enzyme, has no DD-carboxypeptidase activity. The detergent-extracted transpeptidase penetrates gels of Sephadex-100 and is not sedimented at 200 000 X g. [less ▲]

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See detailCatalytic activity of N-heterocyclic carbene complexes of ruthenium and palladium in C-C bond forming reactions
Demonceau, Albert ULiege; Delaude, Lionel ULiege; Delfosse, Sébastien et al

Conference (2005, August)

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See detailCatalytic applications of transition metal N-heterocyclic carbene complexes bearing nitrogen-containing side-groups
Tudose, Adriana; Sauvage, Xavier; Delfosse, Sébastien et al

Poster (2004, July)

Herein, we report preliminary results in olefin cyclopropanation, olefin metathesis, atom transfer radical reactions (ATRA and ATRP), and in the Suzuki coupling reaction when catalyst systems were ... [more ▼]

Herein, we report preliminary results in olefin cyclopropanation, olefin metathesis, atom transfer radical reactions (ATRA and ATRP), and in the Suzuki coupling reaction when catalyst systems were generated in situ from [RuCl2(p-cymene)]2 or Pd(OAc)2, and an imidazolium salt bearing nitrogen-containing substituents. [less ▲]

Detailed reference viewed: 17 (0 ULiège)
See detailCatalytic applications of transition metal N-heterocyclic carbene complexes bearing nitrogen-containing substituents
Sauvage, Xavier ULiege; Tudose, Adriana; Delfosse, Sébastien et al

Poster (2005)

Detailed reference viewed: 30 (3 ULiège)
See detailCatalytic applications of transition metal N-heterocyclic carbene complexes bearing nitrogen-containing substituents
Sauvage, Xavier ULiege; Tudose, Adriana; Delfosse, Sébastien et al

Conference (2005)

Detailed reference viewed: 23 (2 ULiège)
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See detailCatalytic asymmetric dihydroxylation of alpha-methylstyrene by air
Krief, Alain; Colaux, Catherine ULiege

in Tetrahedron Letters (1999), 40(22), 4189-4192

Dioxygen is able, under visible irradiation, to promote the high yielding and highly asymmetric dihydroxylation of alpha-methylstyrene in the presence of catalytic amounts of Os(VI), phthalazine ... [more ▼]

Dioxygen is able, under visible irradiation, to promote the high yielding and highly asymmetric dihydroxylation of alpha-methylstyrene in the presence of catalytic amounts of Os(VI), phthalazine dihydroquinidine chiral ligand [(DHQD)(2)PHAL]. (C) 1999 Published by Elsevier Science Ltd. Ail rights reserved. [less ▲]

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See detailCatalytic asymmetric dihydroxylation of C,C double bonds with osmium tetroxide using selenoxides as co-oxidants
Krief, A.; Colaux, Catherine ULiege

in Synlett (2001), (4), 501-504

Asymmetric dihydroxylation of olefins has been achieved in good yields and ee's using potassium osmate dihydrate (K2OsO2(OH)(4), the pre-oxidant), (DHQD)(2)PHAL (the chiral ligand), potassium carbonate ... [more ▼]

Asymmetric dihydroxylation of olefins has been achieved in good yields and ee's using potassium osmate dihydrate (K2OsO2(OH)(4), the pre-oxidant), (DHQD)(2)PHAL (the chiral ligand), potassium carbonate (the base) and selenoxides (the co-oxidants). Bath the yield and the ee proved to be pH dependent, the highest yield and ee being found at almost the same pH values. The rate of the reaction was found to be highly dependent upon the structure of the selenoxide used. Some representative examples involving aminoxides are presented for comparison. [less ▲]

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See detailCatalytic conversion of lignin to low molecular weight compounds
Verziu, Marian; Richel, Aurore ULiege; Filip, Petru et al

Conference (2011)

Nowadays lignocellulosic materials represent the higher renewable natural resource in the world. These materials consist of 34–50% cellulose, 19–34% hemicellulose and 11–30% lignin. Unlike cellulose ... [more ▼]

Nowadays lignocellulosic materials represent the higher renewable natural resource in the world. These materials consist of 34–50% cellulose, 19–34% hemicellulose and 11–30% lignin. Unlike cellulose, lignin is a three-dimensional aromatic polymer including three main phenylpropane units, namely p-coumaril, coniferyl and sinapyl alcohol which are linked by C-O-C or C-C bonds. To valorize this material it is necessary to achieve its depolymerization to monomers or dimers that typically results from the cleavage of β-O-4 linkages. Literature already reported several approaches to depolymerize lignin using both homogeneous and heterogeneous catalysts. Yuan et all have considered a homogeneous route in this scope using NaOH as catalyst. This solution is however by far non-green leading to no-recyclable wastes. Heterogeneous catalysts offer an alternative. The use of noble metals like Pt or Rh supported on carbon, at 473 K, under H2 pressure, was shown to yield over 50% in monomers and dimers . Cheaper metals as copper represent a more versatile route but the reported example uses high energetic supercritical conditions. The use of inexpensive metals such as Ni may offer another alternative. In this study we propose an inexpensive route presenting results obtained using as active species, nickel in different environments such as NiOx, (NiAl)Ox, (NiMgAl)Ox thus looking also for the effect of basicity in this reaction. These materials were prepared using specific protocols and characterized by several techniques like: XRD, DRIFT, BET, and TEM. The catalysts were tested in autoclave conditions at different temperature (423-473K) under H2 pressure. The lignin was extracted from Miscanthus plants into formic acid / acetic acid / water mixture. Since it is not soluble in water its solubilization was achieved in an [BMIM]OAc ionic liquid, selected from a screening of a series of ILs. On the other side, the analysis of the reaction products is a complicate issue in this chemistry. This was carried out with a chromatographic system equipped with a Detector Triple Quad LC/MS, and a MS Ion Source type, working simultaneously in both APCI and ESI modes. The analysis of the reaction products indicated both polar and less polar compounds with a m/z signal varying from 80 till 900. The population of the different class molecules was carefully analyzed as a function of the nature of the catalyst and the reaction conditions. The higher extent of lignin depolymerization was around 54% and was obtained using a (NiAl)Ox catalyst. Under these conditions the predominant class was that with m/z of 200-300 a.u. Finally the stability of the catalysts was checked looking for their separation and recyclability in several successive cycles. [less ▲]

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Peer Reviewed
See detailCatalytic epuration of biogaz
Claude, Vincent ULiege; Toye, Dominique ULiege; Heinrichs, Benoît ULiege et al

Poster (2015, May 08)

Detailed reference viewed: 17 (2 ULiège)
See detailCatalytic functionalisation of starch and amylose using plant oils: towards polymeric materials and composites
Scholten, Philip ULiege; Söyler, Zafer; Detrembleur, Christophe ULiege et al

Poster (2017, March 19)

Fossil fuels have been the main source of starting materials for the chemical industry over the last century. Especially synthetic polymers rely on this feedstock and are indispensible for mankind’s ... [more ▼]

Fossil fuels have been the main source of starting materials for the chemical industry over the last century. Especially synthetic polymers rely on this feedstock and are indispensible for mankind’s technological advances and status quo. However, a shift to renewable and sustainable resources is needed, as the end of the fossil fuel era is in sight. Biomass presents one possible alternative to fossil fuels, as it consists of a large pool of different chemicals and is inexhaustible. Cellulose, and the closely related starch and amylose, are available cheaply from plants and have favourable properties, such as high strength, thermal stability and biodegradability. However, such poly(saccharides) have been difficult to use directly as materials because of the lack of thermoplasticity, low solubility and high hydrophilicity. Modifications are thus necessary to be able to exploit their advantageous properties. Recently, our group published the catalytic transesterification of maize starch with different plant oils to obtain fully renewable fatty acid starch esters in a sustainable fashion. Polymeric materials with glass transition temperatures (Tgs), soluble in common organic solvents and an increased hydrophobicity were obtained. Compatibilisation tests of the modified starch and amylose with low-density poly(ethylene) (LDPE) and cellulose are being investigated to obtain composites of commodity plastics with improved mechanical properties. [less ▲]

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See detailCatalytic hydroprocessing of lignin under thermal and ultrasound conditions
Finch, Kenneth B.; Richards, Ryan; Richel, Aurore ULiege et al

in Catalysis Today (2012), 196

Lignin isolated from Miscanthus x giganteus using acidic (FAL) and alkali (AL) conditions was thereafter subjected to the catalytic depolymerization under thermal or ultrasounds activation. The ... [more ▼]

Lignin isolated from Miscanthus x giganteus using acidic (FAL) and alkali (AL) conditions was thereafter subjected to the catalytic depolymerization under thermal or ultrasounds activation. The characterization of lignins was achieved by thermogravimetric analysis and FTIR. Three different classes of catalysts, containing nickel as active species, have been prepared in this scope: (i) nano-Ni by reduction of NiCl2 with NaBH4 under ultrasonication, (ii) Fe3O4-(NiMgAlO)x and (NiAlO)x by calcination of Mg(Ni)–Al hydrotalcite incorporated Fe3O4 followed by reduction with hydrogen, and (iii) NiO(111) nanosheets by reduction of Ni(NO3)2 with urea in benzyl alcohol. The catalysts were characterized by XRD and XPS techniques. Reduced mixed oxides displayed a moderate activity while a significant increase in conversion (up to 90%) was observed in the presence of nano-Ni(0). NiO(111) nanosheets catalysts performed very close to nano-Ni(0). The conversion and the mass distribution of the reaction products were strongly related to the procedure used for the extraction of ligning. In all the case AL led to a better depolymerization. The performances of the tested catalysts under ultrasound conditions were inferior to those tested under conventional heating conditions. The nature of the solvent was also found to be very important in this process. Thus, ionic liquid [BMIM]OAc led to the best results in autoclave conditions, and methanol under ultrasounds. [less ▲]

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See detailCatalytic layer for PEMFC based on carbon xerogels
Deschamps, Fabien ULiege; Traina, Karl; Pirard, Jean-Paul ULiege et al

in Proceedings of the Fundamentals and Development of Fuel cells 2013 conference (2013)

Detailed reference viewed: 29 (10 ULiège)
Peer Reviewed
See detailThe catalytic mechanism of beta-lactamases: NMR titration of an active-site lysine residue of the TEM-1 enzyme.
Damblon, Christian ULiege; Raquet, X.; Lian, L. Y. et al

in Proceedings of the National Academy of Sciences of the United States of America (1996), 93(5), 1747-52

Beta-Lactamases are widespread in the bacterial world, where they are responsible for resistance to penicillins, cephalosporins, and related compounds, currently the most widely used antibacterial agents ... [more ▼]

Beta-Lactamases are widespread in the bacterial world, where they are responsible for resistance to penicillins, cephalosporins, and related compounds, currently the most widely used antibacterial agents. Detailed structural and mechanistic understanding of these enzymes can be expected to guide the design of new antibacterial compounds resistant to their action. A number of high-resolution structures are available for class A beta-lactamases, whose catalytic mechanism involves the acylation of a serine residue at the active site. The identity of the general base which participates in the activation of this serine residue during catalysis has been the subject of controversy, both a lysine residue and a glutamic acid residue having been proposed as candidates for this role. We have used the pH dependence of chemical modification of epsilon-amino groups by 2,4,6,-trinitrobenzenesulfonate and the pH dependence of the epsilon-methylene 1H and 13C chemical shifts (in enzyme selectively labeled with [epsilon-13C]lysine) to estimate the pKa of the relevant lysine residue, lysine-73, of TEM-1 beta-lactamase. Both methods show that the pKa of this residue is > 10, making it very unlikely that this residue could act as a proton acceptor in catalysis. An alternative mechanism in which this role is performed by glutamate-166 through an intervening water molecule is described. [less ▲]

Detailed reference viewed: 73 (5 ULiège)