References of "Wathelet, Bernard"
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See detailInfluence des traitements de steam explosion sur la dégradation thermique des fibres de cellulose
Jacquet, Nicolas ULiege; Quievy, Nicolas; Vanderghem, Caroline ULiege et al

in Récents Progrès en Génie des Procédés (2011), 101

The aim of this study is to identify the impact of different steam explosion treatments on the thermal degradation of cellulose fibers. The intensities of the treatments were defined by a severity factor ... [more ▼]

The aim of this study is to identify the impact of different steam explosion treatments on the thermal degradation of cellulose fibers. The intensities of the treatments were defined by a severity factor (SF), based on the residence time and the process temperature. The results obtained show that thermal degradation of cellulose fibers is limited when the severity factor value is below 4.0. At higher intensities, determination of thermal degradation products shows a significant increase of the hydroxymethylfurfural (5-HMF) amount when increasing the intensity of the treatment. When the severity factor reached 5.2, TGA analysis shows that the increase of degradation products is coupled to an increase of the char level meaning a strong degradation of the cellulose. [less ▲]

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See detailInfluence des traitements de steam explosion sur la dégradation thermique des fibres de cellulose
Jacquet, Nicolas ULiege; Quievy; Vanderghem, Caroline ULiege et al

Poster (2011, December)

La présente étude a pour but d’identifier l’impact de différents traitements de steam explosion sur les propriétés de dégradation thermique des fibres de cellulose. Dans un premier temps, les intensités ... [more ▼]

La présente étude a pour but d’identifier l’impact de différents traitements de steam explosion sur les propriétés de dégradation thermique des fibres de cellulose. Dans un premier temps, les intensités des traitements appliqués ont été définies sur base d’un facteur de sévérité (SF), établi par une corrélation entre le temps de séjour et la température du process. Les résultats obtenus montrent que la dégradation thermique des fibres de cellulose reste limitée lorsque la valeur du facteur de sévérité est inférieure à 4.0. Aux intensités supérieures, le dosage des produits de dégradation montre une croissante importante des concentrations en hydroxyméthylfurfurals (5-HMF) dans les phases liquides issues des différents traitements. Lorsque la valeur du facteur de sévérité dépasse 5.2, les analyses TGA indiquent que l’augmentation des produits de dégradation est couplée à une croissance importante du taux de résidus carbonés, indiquant une forte dégradation thermique de la cellulose [less ▲]

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See detailInfluence of steam explosion on the thermal stability of cellulose fibres
Jacquet, Nicolas ULiege; Quievy, Nicolas; Vanderghem, Caroline ULiege et al

in Polymer Degradation & Stability (2011), 96

The aim of the present study was to compare the effect of different steam explosion treatments on the thermal degradation of a bleached cellulose. The intensity of a steam explosion treatment, which ... [more ▼]

The aim of the present study was to compare the effect of different steam explosion treatments on the thermal degradation of a bleached cellulose. The intensity of a steam explosion treatment, which allows breakdown of the structural lignocellulosic material was determined by a correlation between time and temperature of the process. Results of this study showed that thermal degradation of cellulose fibres was limited when the severity factor applied was below 4.0. For higher intensities, determination of the degradation products in the water-soluble extract showed an important increase of the 5-hydroxymethyl-furfural concentration with the temperature. When the severity factor reached 5.2., TGA analysis showed that the increase of degradation products was coupled to an increase of the char level meaning a strong degradation of the cellulose. dTGA behaviour also showed that thermal stability of the steam explosion samples decreased with the intensity of the treatment. To conclude, a theoretical diagram predicting the degradation of the cellulose during the steam explosion treatment was established. [less ▲]

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See detailMonolayer Properties of Uronic Acid Bicatenary Derivatives at the Air-Water Interface: Effect of Hydroxyl Group Stereochemistry Evidenced by Experimental and Computational Approaches
Razafindralambo, Hary ULiege; Richel, Aurore ULiege; Wathelet, Bernard ULiege et al

in Physical Chemistry Chemical Physics [=PCCP] (2011), 13(33), 1529115298

By screening uronic acid-based surfactant interfacial properties, the effect of the hydroxyl group stereochemistry (OH-4) on the conformation of bicatenary (disubstituted) derivatives at the air–water ... [more ▼]

By screening uronic acid-based surfactant interfacial properties, the effect of the hydroxyl group stereochemistry (OH-4) on the conformation of bicatenary (disubstituted) derivatives at the air–water interface has been evidenced by experimental and computational approaches. Physical and optical properties of a monolayer characterized by Langmuirfilmbalance, Brewster angle microscopy, and ellipsometry at 20°C reveal that the derivative of glucuronate (C14/14–GlcA) forms a more expanded monolayer, and shows a transition state under compression, in the opposite to that of galacturonate (C14/14–GalA). Both films are very mechanically resistant (compression modulus > 300m Nm-1) and stable (collapse pressure exceeding 60mNm-1), while that of C14/14–GalA exhibits a very high compression modulus up to 600mNm-1 like films in the solid state. Computational approaches provide single and assembly molecular models that corroborate the molecule expansion degree and interactions data from experimental results. Differences in the molecular conformation and film behaviours of uronic acid bicatenary derivatives at the air–water interface are attributed to the intra-H-bonding formation, which is more favourable with an OH-4 in the axial (C14/14–GalA) than in the equatorial position (C14/14–GlcA). [less ▲]

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See detailCaractérisation physicochimique et évaluation de la qualité des dattes des cultivars de palmier dattier de la région de Figuig
Hasnaoui, A.; ElHoumaizi, M. A.; Hakkou, A. et al

Poster (2011, May)

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See detailCHIMIE THÉORIQUE ET PHYSIQUE APPLIQUÉE À L’ANALYSE STRUCTURALE DES BIOMOLÉCULES (CG 204) - Exercices
Gillet, Sébastien ULiege; Richel, Aurore ULiege; Wathelet, Bernard ULiege

Learning material (2011)

Le cours est axé sur l'apprentissage de l'analyse spectrale (IR, MS, RMN, RMN2D) des molécules organiques ou biologiques.L'interprétation qui en découle permettra d'en retrouver la structure.

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See detailAphid-host plant interactions: Does aphid honeydew exactly reflect the host plant amino acid composition?
Leroy, Pascal ULiege; Wathelet, Bernard ULiege; Sabri, Ahmed ULiege et al

in Arthropod-Plant Interactions (2011), 5

Plants provide aphids with unbalanced and low concentrations of amino acids. Likely, intracellular symbionts improve the aphid nutrition by participating to the synthesis of essential amino acids. To ... [more ▼]

Plants provide aphids with unbalanced and low concentrations of amino acids. Likely, intracellular symbionts improve the aphid nutrition by participating to the synthesis of essential amino acids. To compare the aphid amino acid uptakes from the host plant and the aphids amino acid excretion into the honeydew, host plant exudates (phloem + xylem) from infested and uninfested Vicia faba L. plants were compared to the honeydew produced by two aphid species (Acyrthosiphon pisum Harris and Megoura viciae Buckton) feeding on V. faba. Our results show that an aphid infestation modifies the amino acid composition of the infested broad bean plant since the global concentration of amino acids significantly increased into the host plant in response to aphid infestations. Specifically, the concentrations of two amino acids glutamine and asparagine were strongly enhanced. The amino acid profiles from honeydews were similar for the two aphid species, but the concentrations found into the honeydews were generally lower than those measured in the exudates of infested plants (aphids uptakes). This work also highlights that aphids take large amounts of amino acids into the host plant, especially glutamine and asparagine which are converted into glutamic and aspartic acids but also into other essential amino acids. The amino acid profiles differed between the host plant exudates and the aphid excretion product. Finally, this study highlights that the pea aphid - a “specialist” for the V. faba host plant - induced more important modifications into the host plant amino acid composition than the “generalist” aphid M. viciae. [less ▲]

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See detailSynthesis of amonabactins by Aeromonas hydrophila : implication of NRPS of a unique iterative-alternative type
Leclère, Valérie; Rathisamy, Subashkumar; Wathelet, Bernard ULiege et al

Poster (2011)

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See detailSynthesis of amonabactins by Aeromonas hydrophila : implication of NRPS of a unique iterate-alternative type
Leclère, Valérie; Subashkumar, Rathinasamy; Wathelet, Bernard ULiege et al

Poster (2011)

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See detailBioinformatics tools to decrypt pyoverdine biosynthesis in Pseudomonas sp.
Vanvlassenbroeck, Aurélien; Leclère, Valérie; Pupin, Maude et al

Poster (2011)

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See detailAdenylation domain specificity in pyoverdine NRPS biosynthesis
Vanvlassenbroeck, Aurélien; Leclère, Valérie; Pupin, Maude et al

Poster (2011)

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See detailBioinformatics and molecular approaches to detect NRPS genes involved in the biosynthesis of kurstakin from Bacillus thuringiensis
Abderrahmani, Ahmed; Tapi, Arthur; Nateche, Farida et al

in Applied Microbiology & Biotechnology (2011), 92

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See detailIdentification of surf actin producing strains in Soumbala and Bikalga fermented condiments using polymerase chain reaction and matrix assisted laser desorption/ionization-mass spectrometry methods
Savadogo, A; Tapi, Arthur; Chollet, Marlène et al

in International Journal of Food Microbiology (2011)

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See detailPhysico-chemical Characterization, Classification and Quality Evaluation of Date Palm Fruits of some Moroccan Cultivars
Hasnaoui, Amina; Elhoumaizi, Aziz; Hakkou, Abdelkader et al

in JOURNAL OF SCIENTIFIC RESEARCH (2011), 3(1), 139-149

Fourteen native date cultivars from different oases and regions of Morocco, Tunisia and Algeria were examined for their approximate composition, water activity, and CIELAB parameters. Sugars were the ... [more ▼]

Fourteen native date cultivars from different oases and regions of Morocco, Tunisia and Algeria were examined for their approximate composition, water activity, and CIELAB parameters. Sugars were the predominant component in all studied date cultivars (~ 54.14 - 75.56 g/100g dry matter), followed by moisture content (~7.2 - 31.9%), along with small amount of protein (~1.9 - 3.3g/100g dry matter), fat (~ 0.1 - 0.44g/100g dry matter), and ash (~1.88 - 3.45g/100 g dry matter). Dates with early maturity had the highest water activity (0.78 - 0.87) in contrast to late maturing dates cultivars. In the Deglet Nour (Tunisia) and Aziza bouzid (Morocco) cultivars, sucrose is dominant, whereas, the majority of other cultivars were rich in fructose and glucose in comparable proportions. No significant changes were observed in the approximate composition of samples of different geographical origins. All cultivars show significant differences in color. The date with late maturity (from Assiane, Aziza bouzid and Boufeggous gharas locations of Morocco) were characterized by higher L*, a*, b* than the other date cultivars. Chemical composition of dates seems to be a good tool for fruit physiological and technological ability studies. [less ▲]

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See detailEnzymatic production of pectic oligosaccharides from polygalacturonic acid with commercial pectinase preparations
Combo, Agnan Marie Michel ULiege; Aguedo, Mario ULiege; Goffin, Dorothée ULiege et al

in Food and Bioproducts Processing: Transactions of the Institution of Chemical Engineers, Part C (2011), 90(3), 588-596

The present study investigates the individual efficiency of six commercial pectinase preparations (Endopolygalacturonase M2, Pectinase, Viscozyme L, Pectinex Ultra SP-L, Pectinase 62L and Macer8 FJ) in ... [more ▼]

The present study investigates the individual efficiency of six commercial pectinase preparations (Endopolygalacturonase M2, Pectinase, Viscozyme L, Pectinex Ultra SP-L, Pectinase 62L and Macer8 FJ) in catalyzing the liberation of pectic oligosaccharides (POS) from polygalacturonic acid. On the basis of high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) analysis of the enzymatic hydrolysates, products release kinetics revealed a random cleavage pattern and an exo mode of cleavage for all the enzymes except for Endopolygalacturonase M2. All six enzymes generated oligoGalA with different degree of polymerization (DP); the quantitative composition of oligoGalA depended on the enzyme specificity and the time of enzymatic reaction. Endopolygalacturonase M2 was the best enzyme preparation for production of oligoGalA, with 18% (wt) of digalacturonic acid and 58% (wt) of trigalacturonic acid after 2h of reaction. Concerning galacturonic acid production, Pectinase 62L was superior to the other enzyme preparations with 47% (wt) after 1h of reaction. [less ▲]

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See detailRipening influences banana and plantain peels composition and energy content
Happi Emaga, Thomas ULiege; Bindelle, Jérôme ULiege; Angeesens, Richard et al

in Tropical Animal Health and Production (2011), 43

Musa sp. peels are widely used by smallholders as complementary feeds for cattle in the tropics. A study of the influence of the variety and the maturation stage of the fruit on fermentability and ... [more ▼]

Musa sp. peels are widely used by smallholders as complementary feeds for cattle in the tropics. A study of the influence of the variety and the maturation stage of the fruit on fermentability and metabolisable energy (ME) content of the peels was performed using banana (Yangambi Km5) and plantain (Big Ebanga) peels at three stages of maturation in an in vitro model of the rumen. Peel samples were analysed for starch, free sugars and fibre composition. Samples were incubated in the presence of rumen fluid. Kinetics of gas production were modelled, ME content was calculated using prediction equation and short-chain fatty acids production and molar ratio were measured after 72 h of fermentation. Final gas production was higher in plantain (269–339 ml g−1) compared to banana (237–328 ml g−1) and plantain exhibited higher ME contents (8.9–9.7 MJ/kg of dry matter, DM) compared to banana (7.7–8.8 MJ/kg of DM). Butyrate molar ratio decreased with maturity of the peels. The main influence of the variety and the stage of maturation on all fermentation parameters as well as ME contents of the peels was correlated to changes in the carbohydrate fraction of the peels, including starch and fibre. [less ▲]

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See detailCurrent perspectives on microwave-enhanced reactions of monosaccharides promoted by heterogeneous catalysts.
Richel, Aurore ULiege; Laurent, Pascal ULiege; Wathelet, Bernard ULiege et al

in Catalysis Today (2011), 167

Involvment of heterogeneous catalysts as promoters of carbohydrate conversions, in synergy with microwaves as the heating source, is reported. This paper deals with the application of ion-exchange resins ... [more ▼]

Involvment of heterogeneous catalysts as promoters of carbohydrate conversions, in synergy with microwaves as the heating source, is reported. This paper deals with the application of ion-exchange resins, zeolites, clays and metal oxides as convenient mediators for key transformations of carbohydrates. A special emphasis is placed on the use of (doped) mineral supports, in solventless conditions, as clean promoters in combination with microwave dielectric heating. [less ▲]

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See detailMicrowave-assisted conversion of carbohydrates. State of the art and outlook.
Richel, Aurore ULiege; Laurent, Pascal ULiege; Wathelet, Bernard ULiege et al

in Comptes Rendus Chimie (2011), 14

The valorisation of carbohydrates arising from the hydrolysis of renewable feedstocks (i.e. lignocellulosic biomass) is nowadays an area of outmost interest. In this context, the implementation of fast ... [more ▼]

The valorisation of carbohydrates arising from the hydrolysis of renewable feedstocks (i.e. lignocellulosic biomass) is nowadays an area of outmost interest. In this context, the implementation of fast, expeditious and cost-effective methodologies for the modification of these naturally occurring compounds is becoming a prerequisite. In this sense, the application of microwaves has gained progressive attention in laboratories for making a range of high-added value sugars derivatives scaffolds. Advantages of microwaves are numerous and include enhancement of reaction rates and yields, combined to improved regio-, chemo- and anomeric selectivities. Summary: 1. Introduction 2. Chemical transformations of monosaccharides Regioselective hydroxyls protections/deprotections Derivatisation at the anomeric position Other derivatisations Microwave-assisted click chemistry Synergy between microwaves and heterogeneous catalysis Enzymatic modifications of monosaccharides 3. Effect of microwave heating on polysaccharides Hydrolysis and pretreatment of cellulose Derivatisation of cellulose 4. Scale-up of microwave-promoted reactions 5. Conclusions [less ▲]

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