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See detailAmmonium sulphate as promoting agent of the sulphidization process of oxidized Cu-Co ores from the Luiswishi deposit (RDC)
Bastin, David ULg; Frenay, Jean ULg; Philippart, Pierre

Poster (2003)

The Luiswishi deposit belongs to the Cu-Co deposits of the Southern Group of the Katangian Copper Belt and is operated by a joint venture between EGMF (Entreprises Générales Malta Forrest) and Gecamines ... [more ▼]

The Luiswishi deposit belongs to the Cu-Co deposits of the Southern Group of the Katangian Copper Belt and is operated by a joint venture between EGMF (Entreprises Générales Malta Forrest) and Gecamines (Générale des Carrières et des Mines). The Cu-Co ore is beneficiated by the sulphidization process at the NCK (New Concentrator of Kipushi) at Kipushi. Sulphidization followed by flotation with sulphydryl collectors is a common practice for the treatment of oxidized base metals ores. This process is complex and its application at the industrial scale is quite sensitive. In Central Africa it is also a cost intensive treatment as the sulphidizing agent has to be imported. In order to improve the metallurgical performances and to optimise the economics of the process, a laboratory research program was carried out by the Laboratory of Metallurgy and Mineral Processing (MTM) of the University of Liège in close collaboration with EGMF and Gecamines. This program included the study of various flotation reagents as dispersing, depressing and activating agents. This paper presents the results obtained with the use of ammonium sulphate as activator of the sulphidized xanthate flotation. Although ammonium sulphate has been mentioned in the literature as a promoting agent of the sulphidized xanthate flotation of malachite, its effects on the flotation of cobalt oxides was not known. The testworks were carried out on various oxidized siliceous ore types from the Luiswishi deposit. A 1.7 l Agitair laboratory flotation cell was used. NaHS and potassium amylxanthate were respectively choosen as sulphidizer and collector. A mixture of gasoil and tall oil (90/10) was used as secondary collector. A multistage sulphidization was realised. Values of pH were followed during the different tests and an ion selective electrode Ag/Ag2S was used to control the Es potentiel evolution during the stepwise addition of the sulphidizer. The addition of ammonium suphate [(NH4)2SO4] simultaneously with NaHS led to the following results: -A marked improvement of the sulfidization kinetics leading to shorter conditioning times and limiting the number of sulphidizing stages required to reach maximum recoveries. -The inhibition of the depressive effect on Cu and Co flotation of an excess of hydrosulphide ions in the pulp. -An improvement of the selectivity of the flotation combined with higher cobalt recoveries. The promoting effect is indeed more effective for cobalt than for copper and cobalt recoveries were improved by 4 to 8 %. -A significant decrease of the sulfidizer consumption. These laboratory results were implemented at an industrial scale at the NCK at Kipushi. In close accordance with the laboratory results the sulphidization kinetics were improved and the cobalt recoveries rose by 7 % while maintaining the previous Cu and Co grades of the concentrate. Ammonium sulphate being a low cost and common reagent (it is easily found in the fertiliser industry or as a byproduct of the coke industry), its use significantly improved the economics of the flotation of Cu-Co oxides ores from the Luiswishi deposit. [less ▲]

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See detailConlin V3 Optimizer: User and Installation Guide
Fleury, Claude ULg

Report (2003)

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See detailImbalance between lipoxin A(4) and leukotriene B-4 in chronic mastitis-affected cows
Boutet, Philippe ULg; Bureau, Fabrice ULg; Degand, Guy ULg et al

in Journal of Dairy Science (2003), 86(11), 3430-3439

Persistent accumulation of inflammatory cells in the udder, with neutrophils being the predominant cell type, is a characteristic feature of chronic mastitis in dairy cows. Leukotriene (LT) B-4 is a ... [more ▼]

Persistent accumulation of inflammatory cells in the udder, with neutrophils being the predominant cell type, is a characteristic feature of chronic mastitis in dairy cows. Leukotriene (LT) B-4 is a potent chemotactic agent, known to induce recruitment and accumulation of neutrophils in the bovine mammary gland. The LTB4-stimulated neutrophil functional responses are closely opposed by lipoxin (LX) A(4), which promotes the resolution of inflammation. We thus hypothesized that the chronic inflammation of the udder could be associated with an unfavorable ratio between these two eicosanoids and that the persistence of neutrophil accumulation could be due to an increase in LTB4 synthesis and/or an impaired LXA(4) production. In an attempt to verify this hypothesis, we first measured LXA(4), LTB4, and their ratio in the milk of healthy and acute and chronic mastitis-affected quarters. Next, we studied the relationships between these variables and the degree of udder inflammation as assessed by somatic cell count measurement. The LTB4 concentration was low in healthy quarters, drastically increased in acute mastitis, and reached intermediate levels in chronic mastitis-affected quarters. However, whereas LXA(4) concentration was highly increased in acute mastitis, healthy and chronic quarters had similarly low values. The LXA(4):LTB4 ratio was thus significantly lower in chronic mastitis-affected cows. The LTB4 concentrations measured in chronic quarters were highly correlated to somatic cell count and to milk neutrophil and macrophage numbers. A weaker correlation was observed between LXA(4) and these variables. For both eicosanoids, the highest correlation was observed with the number of neutrophils. These results show the existence of an LXA(4):LTB4 imbalance in chronic mastitis-affected cows because of low LXA(4) concentrations. Further studies are needed to determine whether administration of LX or stable analogs could have therapeutic potential in the control of chronic bovine mastitis. [less ▲]

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See detailVariable Blue Stragglers and the EASE Scenario
Noels-Grötsch, Arlette ULg; Scuflaire, Richard ULg; Magain, Pierre ULg et al

in Thompson, M. J.; Cunha, M. S.; Monteiro, M.J.P.F.G. (Eds.) Asteroseismology Across the HR Diagram (2003)

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See detailLe cabotin sublime et les pisse-froid. Sartre, Hugo et la modernité
Denis, Benoît ULg

in Prévost, Maxime; Hamel, Yan (Eds.) Victor Hugo 2003-1802. Images et transfigurations (2003)

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See detailPregnancy-Associated Glycoprotein 55h [Fragment] from Ovis aries placenta - Access number P83500
El Amiri, B.; Remy, B.; Melo de Sousa, Noelita ULg et al

E-print/Working paper (2003)

N-terminal microsequence obtained after purification and characterization of placental proteins in ovine species. Proteins were submitted to SwissProt databank.

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See detailChlamydomonas reinhardtii as a eukaryotic photosynthetic model for studies of heavy metal homeostasis and tolerance
Hanikenne, Marc ULg

in New Phytologist (2003), 159(2), 331-340

The green alga Chlamydomonas reinhardtii is a useful model of a photosynthetic cell. This unicellular eukaryote has been intensively used for studies of a number of physiological processes such as ... [more ▼]

The green alga Chlamydomonas reinhardtii is a useful model of a photosynthetic cell. This unicellular eukaryote has been intensively used for studies of a number of physiological processes such as photosynthesis, respiration, nitrogen assimilation, flagella motility and basal body function. Its easy-to-manipulate and short life cycle make this organism a powerful tool for genetic analysis. Over the past 15 yr, a dramatically increased number of molecular technologies (including nuclear and organellar transformation systems, cosmid, yeast artificial chromosome (YAC) and bacterial artificial chromosome (BAC) libraries, reporter genes, RNA interference, DNA microarrays, etc.) have been applied to Chlamydomonas . Moreover, as parts of the Chlamydomonas genome project, molecular mapping, as well as whole genome and extended expressed sequence tag (EST) sequencing programs, are currently underway. These developments have allowed Chlamydomonas to become an extremely valuable model for molecular approaches to heavy metal homeostasis and tolerance in photosynthetic organisms. [less ▲]

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See detailL’écrivain et la folie: André Baillon entre à la Salpêtrière
Demoulin, Laurent ULg

in Bertrand, Jean-Pierre; Biron, Michel; Denis, Benoît (Eds.) et al Histoire de la littérature belge 1830-2000 (2003)

Quelle rôle la folie a joué dans la vie et l'oeuvre d'André Baillon? La réponse à cette question se doit d'être nuancée.

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See detailNonisotopic substrate for assaying both human zinc and NAD+-dependent histone deacetylases.
Heltweg, Birgit; Dequiedt, Franck ULg; Verdin, Eric et al

in Analytical Biochemistry (2003), 319(1), 42-8

Histone deacetylases (HDACs) are involved in the regulation of transcription and their inhibitors are a promising class of new anticancer drugs. We have previously reported Boc(Ac)Lys-AMC, also termed MAL ... [more ▼]

Histone deacetylases (HDACs) are involved in the regulation of transcription and their inhibitors are a promising class of new anticancer drugs. We have previously reported Boc(Ac)Lys-AMC, also termed MAL, as a fluorescent substrate for HDACs. Now we present a modification of MAL called Z-MAL that is characterized by an increased rate of conversion by histone deacetylases of classes I and II and the recently discovered sirtuins (histone deacetylases class III). MAL and Z-MAL are the first nonradioactive substrates for class III enzymes. The new substrate Z-MAL allows for shorter assay times in inhibitor screening and is applicable to diverse sources of deacetylase activity even with completely different catalytic mechanisms. Interestingly, MAL shows some relative preference toward class II, indicating that subtype selectivity in small-molecule HDAC substrates might be obtained. [less ▲]

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See detailEnfin "Tubambe" devoile son identite! Hadraphe ethiopica (Bethune-Baker) (Limacodidae), une chenille comestible des forets claires zambeziennes.
Malaisse, François ULg; Demesmaecker, Anne; Matera, Joseph et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2003), 7(2), 67-77

La consommation humaine de chenilles de Limacodidae avait été signalée en Afrique centro-australe. L’une de ces espèces, Hadraphe ethiopica, a été déterminée. Des données relatives à sa biologie ont été ... [more ▼]

La consommation humaine de chenilles de Limacodidae avait été signalée en Afrique centro-australe. L’une de ces espèces, Hadraphe ethiopica, a été déterminée. Des données relatives à sa biologie ont été rassemblées. Des analyses d’échantillons séchés ont permis de préciser leur composition chimique et leur valeur nutritionnelle, notamment sur le plan des acides aminés et des acides gras. [less ▲]

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See detailAb initio study of MoS2 nanotube bundles
Verstraete, Matthieu ULg; Charlier, Jean-Christophe

in Physical Review. B : Condensed Matter (2003), 68

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See detailProduction of selenium-enriched grass and haylage by mineral fertilisation in southern Belgium
de Behr, V.; Coenen, M.; Hambuckers, Alain ULg et al

in Proceedings of 7th Conference of the European Society of Veterinary and Comparative Nutrition (2003)

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See detailPiracetam Inhibits The Lipid-Destabilising Effect Of The Amyloid Peptide A Beta C-Terminal Fragment
Mingeot-Leclercq, Mp.; Lins, Laurence ULg; Bensliman, M. et al

in Biochimica et Biophysica Acta-Biomembranes (2003), 1609(1), 28-38

Amyloid peptide (Abeta) is a 40/42-residue proteolytic fragment of a precursor protein (APP), implicated in the pathogenesis of Alzheimer's disease. The hypothesis that interactions between Abeta ... [more ▼]

Amyloid peptide (Abeta) is a 40/42-residue proteolytic fragment of a precursor protein (APP), implicated in the pathogenesis of Alzheimer's disease. The hypothesis that interactions between Abeta aggregates and neuronal membranes play an important role in toxicity has gained some acceptance. Previously, we showed that the C-terminal domain (e.g. amino acids 29-42) of Abeta induces membrane permeabilisation and fusion, an effect which is related to the appearance of non-bilayer structures. Conformational studies showed that this peptide has properties similar to those of the fusion peptide of viral proteins i.e. a tilted penetration into membranes. Since piracetam interacts with lipids and has beneficial effects on several symptoms of Alzheimer's disease, we investigated in model membranes the ability of piracetam to hinder the destabilising effect of the Abeta 29-42 peptide. Using fluorescence studies and 31P and 2H NMR spectroscopy, we have shown that piracetam was able to significantly decrease the fusogenic and destabilising effect of Abeta 29-42, in a concentration-dependent manner. While the peptide induced lipid disorganisation and subsequent negative curvature at the membrane-water interface, the conformational analysis showed that piracetam, when preincubated with lipids, coats the phospholipid headgroups. Calculations suggest that this prevents appearance of the peptide-induced curvature. In addition, insertion of molecules with an inverted cone shape, like piracetam, into the outer membrane leaflet should make the formation of such structures energetically less favourable and therefore decrease the likelihood of membrane fusion. [less ▲]

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See detailProsthetic vascular infection complicated or not by aortoenteric fistula: comparison of treatment with and without cryopreserved allograft (homograft).
Lavigne, Jean-Paul ULg; Postal, Alain ULg; Kolh, Philippe ULg et al

in European Journal of Vascular and Endovascular Surgery (2003), 25(5), 416-23

OBJECTIVES: in patients with vascular prosthesis infection, to compare surgical outcome and long-term results of cryopreserved allograft implantations to conventional surgery. DESIGN: retrospective study ... [more ▼]

OBJECTIVES: in patients with vascular prosthesis infection, to compare surgical outcome and long-term results of cryopreserved allograft implantations to conventional surgery. DESIGN: retrospective study. MATERIAL AND METHODS: two asynchronous series of 44 [series I: 1980-1994; 8 patients with aortoenteric fistula (AEF)] and 22 (series II: 1994-1997; 4 patients with AEF) patients were treated for prosthesis infection. All patients had prosthesis excision. In series I, there were 4 in situ reparations, 26 extra-anatomic bypass, 13 excision only, and one death at laparotomy. In series II, in situ cryopreserved allografts were implanted in all patients. RESULTS: operative mortality was 16% in series I and 13.6% in series II. For AEF patients, mortality was 37% in series I and 50% in series II. Among hospital survivors, infection-related late mortality was 13.5% in series I and 5% in series II. For AEF patients, late mortality was 20% in series I and 50% in series II. Incidence of reoperations was 54% in series I and 10.5% in series II (p<0.01). Hospital stay was 47.2+/-26.4 days in series I and 16.6+/-11.5 days in series II (p<0.001). CONCLUSIONS: compared to conventional treatment, incidence of reoperations and length of hospital stay are significantly decreased after cryopreserved allograft implantation. However, closure of aortic stump and extra-anatomic bypass gives better results for patients with AEF. [less ▲]

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See detailGeorges Simenon. Un romancier pour aujourd'hui ?
Dumortier, Jean-Louis ULg

Book published by Labor (2003)

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See detailPreparation of nanosized barium zirconate powder by thermal decomposition of urea in an aqueous solution containing barium and zirconium, and by calcination of the precipitate
Boschini, Frédéric ULg; Robertz, B.; Rulmont, André ULg et al

in Journal of the European Ceramic Society (2003), 23(16), 3035-3042

The synthesis of barium zirconate was initiated by urea induced homogeneous precipitation followed by a "low temperature" thermal treatment. The kinetic of the reaction and the optimum urea/cation ratio ... [more ▼]

The synthesis of barium zirconate was initiated by urea induced homogeneous precipitation followed by a "low temperature" thermal treatment. The kinetic of the reaction and the optimum urea/cation ratio have been determined by means of X-ray diffraction and Inductive Coupled Plasma analyses. It has been demonstrated that an amorphous zirconium hydrated oxide starts to precipitate followed by the precipitation of barium carbonate. A calcination at 1200 degreesC during 2 h gives rise to the formation of a pure barium zirconate phase. Microstructural characterisations have been performed in order to evaluate the sintering behaviour. Dilatometric measurements, coupled with scanning electron microscopy analyses clearly indicate that barium carbonate decomposition process leads to the formation of internal porosity which severely limits the density of the material, even if a sintering was performed at 1500 degreesC. A careful control of the heating profile seems to be necessary in order to produce dense materials. (C) 2003 Elsevier Ltd. All rights reserved. [less ▲]

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See detailOn Iterating Linear Transformations over Recognizable Sets of Integers
Boigelot, Bernard ULg

in Theoretical Computer Science (2003), 309(1-3), 413-468

It has been known for a long time that the sets of integer vectors that are recognizable by finite-state automata are those that can be defined in an extension of Presburger arithmetic. In this paper, we ... [more ▼]

It has been known for a long time that the sets of integer vectors that are recognizable by finite-state automata are those that can be defined in an extension of Presburger arithmetic. In this paper, we address the problem of deciding whether the closure of a linear transformation preserves the recognizable nature of sets of integer vectors. We solve this problem by introducing an original extension of the concept of recognizability to sets of vectors with complex components. This generalization allows to obtain a simple necessary and sufficient condition over linear transformations, in terms of the eigenvalues of the transformation matrix. We then show that these eigenvalues do not need to be computed explicitly in order to evaluate the condition, and we give a full decision procedure based on simple integer arithmetic. The proof of this result is constructive, and can be turned into an algorithm for applying the closure of a linear transformation that satisfies the condition to a finite-state representation of a set. Finally, we show that the necessary and sufficient condition that we have obtained can straightforwardly be turned into a sufficient condition for linear transformations with linear guards. [less ▲]

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See detailSexual interactions in triadic encounters involving paedomorphic and metamorphic Alpine newts Triturus alpestris
Denoël, Mathieu ULg

Poster (2003)

Sexual selection theories suppose that morphologically-contrasting alternative morphs may exhibit different mating tactics. Facultative paedomorphosis in newts is a suitable process to explore this ... [more ▼]

Sexual selection theories suppose that morphologically-contrasting alternative morphs may exhibit different mating tactics. Facultative paedomorphosis in newts is a suitable process to explore this question because it implies the coexistence of two morphs differing by the presence of gills and epigamic traits. The aim of this study was to find out whether paedomorphs (i.e. adult retaining larval traits) and metamorphs use similar behavioural patterns to attract mates in the presence of a rival and whether there are differences in sexual activity and success between alternative morphs. Sexual interactions in triadic encounters were staged and analysed in a standardised experimental design. The two kinds of males did not differ in terms of sexual activity, spermatophore deposition or female responsiveness. Both rival paedomorphic and metamorphic males exhibited sexual interference, but in most encounters, intruders just disturbed the courting pair. Sperm transfer success was lower in triadic encounters than in dyadic encounters. These results illustrate that inter-morph breeding also occurs in the presence of competitors, but that the success rate of the newts is considerably decreased in such competitive situations. Moreover, newts do not use alternative reproductive tactics depending of their status (i.e. paedomorph or metamorph). [less ▲]

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