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See detailImpact of formic/acetic acid and ammonia pre-treatments on chemical structure and physico-chemical properties of Miscanthus x giganteus lignins
Vanderghem, Caroline ULg; Richel, Aurore ULg; Jacquet, Nicolas ULg et al

in Polymer Degradation & Stability (2011), 96(10), 1761-1770

Miscanthus x giganteus was treated with formic acid/acetic acid/water (30/50/20 v/v) for 3 h at 107 C and 80° C, and soaking in aqueous ammonia (25% w/w) for 6 h at 60 C. The effects of these ... [more ▼]

Miscanthus x giganteus was treated with formic acid/acetic acid/water (30/50/20 v/v) for 3 h at 107 C and 80° C, and soaking in aqueous ammonia (25% w/w) for 6 h at 60 C. The effects of these fractionation processes on chemical structure, physico-chemical properties and antioxidant activity of extracted lignins were investigated. Lignins were characterized by their purity, carbohydrate composition, thermal stability, molecular weight and by Fourier transform infrared (FTIR), 1H and quantitative 13C nuclear magnetic resonance (NMR), adiabatic broadband {13C-1H} 2D heteronuclear (multiplicity edited) single quantum coherence (g-HSQCAD). The radical scavenging activity towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) was also investigated. Formic/acetic acid pretreatment performed in milder conditions (80° C for 3 h) gave a delignification percentage of 44.7% and soaking in aqueous ammonia 36.3%. Formic/acetic acid pretreatment performed in harsh conditions (107°C for 3 h) was more effective for extensive delignification (86.5%) and delivered the most pure lignin (80%). The three lignin fractions contained carbohydrate in different extent: 3% for the lignin obtained after the formic/acetic acid pretreatment performed at 107 C (FAL-107), 5.8% for the formic/acetic acid performed at 80°C (FAL-80) and 13.7% for the ammonia lignin (AL). The acid pretreatment in harsh conditions (FAL-107) resulted in cleavage of b-O-4' bonds and aromatic C-C. Repolymerisation was thought to originate from formation of new aromatic C-O linkages. Under milder conditions (FAL-80) less b-O-4' linkages were broken and repolymerisation took place to a lesser extent. Ammonia lignin was not degraded to a significant extent and resulted in the highest weight average 3140 g mol -1. Despite the fact of FAL-107 repolymerisation, significant phenolic hydroxyls remained free, explaining the greater antioxidant activity. [less ▲]

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See detailPretreatment And Enzymatic Hydrolysis Of Miscanthus x giganteus: Influence Of Process Parameters
Vanderghem, Caroline ULg; Brostaux, Yves ULg; Jacquet, Nicolas ULg et al

Poster (2010, September 21)

Miscanthus x giganteus is a perennial grass which grows rapidly and gives high yields of biomass per hectare. It can be grown in poor quality soil and is non invasive. Due to its high cellulose and ... [more ▼]

Miscanthus x giganteus is a perennial grass which grows rapidly and gives high yields of biomass per hectare. It can be grown in poor quality soil and is non invasive. Due to its high cellulose and hemicellulose content, it has attracted considerable attention as a possible energy crop to produce bioethanol. Pretreatment of lignocellulosic biomass is a key step to unlocking the protective structures so that the enzymatic hydrolysis of the carbohydrate fraction to monosugars can be achieved more easily and with greater yield. In this study, Miscanthus x giganteus was delignified by a chemical pre-treatment process using a mixture of formic acid/acetic acid (1). The treated material was then hydrolyzed. By means of Box-Behnken experimental design and response surface methodology we investigated the effect of cooking time (60, 120 and 180 min), formic acid/acetic acid/water concentration (20/60/20, 30/50/20 and 40/40/20) and temperature (80, 90 and 107°C) on the residual Klason lignin content and the % of digestibility. The optimal pretreatment process parameters were identified. [less ▲]

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See detailInfluence of steam explosion and thermal degradation of cellulose
Jacquet, Nicolas ULg; Quiévy, Nicolas; Vanderghem, Caroline ULg et al

Poster (2010, August 20)

The aim of the present work is to compare the effect of different steam explosion pretreatments on the thermal degradation of a bleached cellulose where components like hemicelluloses and lignin have ... [more ▼]

The aim of the present work is to compare the effect of different steam explosion pretreatments on the thermal degradation of a bleached cellulose where components like hemicelluloses and lignin have already been removed by acid and alkaline treatments. The results of this study show that thermal degradation of cellulose fibres, studied by TGA, is still limited for a temperature process below 240 °C. However, derivative TGA show that thermal stability of cellulose obtained by these conditions decreases with the increase of temperature. For temperatures above 250°C, char level is higher at the end of the pyrolysis. According to the literature, the increase of the char level is correlated to an increase of the degradation product1. Determination of the degradation products in the liquor obtained after the pretreatment show an important increase of furfural and 5-hydroxymethylfurfural concentration with the temperature in agreement with the increase of the char level. These results confirm the important degradation of the cellulose fibres. [less ▲]

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See detailSteam explosion pretreatment and thermal degradation of cellulose fibers
Jacquet, Nicolas ULg; Quiévy, Nicolas; Vanderghem, Caroline ULg et al

Conference (2010, August 20)

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See detailPretreatments and enzymatic hydrolysis of Miscanthus x giganteus for oligosaccharides production: delignification degree and characterisation of the hydrolysis products
Vanderghem, Caroline ULg; Jacquet, Nicolas ULg; Blecker, Christophe ULg et al

Poster (2010, February 04)

The aim of the present study is to compare two delignification methods (formic/acetic acid1 and soaking in aqueous ammonia) on Miscanthus x giganteus and to assess the suitability to produce cellobiose ... [more ▼]

The aim of the present study is to compare two delignification methods (formic/acetic acid1 and soaking in aqueous ammonia) on Miscanthus x giganteus and to assess the suitability to produce cellobiose and other oligosaccharides after enzymatic hydrolysis. Oligosaccharides have recently gotten attention for their health benefits. Two methods were compared in order to quantify lignin: the acid detergent lignin method (procedure of Van Soest most commonly employed by animal scientist and agronomists for analysis of forages) and the Klason lignin procedure. Lignin concentrations in raw material determined by both methods were different; Klason lignin value (23.5%) was greater than the acid detergent lignin concentration (12.9%). Possible reasons of these results will be discussed. Pretreatment by the formic/acid mixture showed a better deliginification rate compared to the soaking in aqueous ammonia method. Results were based on Klason lignin. Analysis of the structural carbohydrates revealed that untreated miscanthus was mainly composed of glucose and xylose. Extracted pulps by both delignification methods were hydrolysed by commercial cellulases and hemicellulases. A major challenge is the characterisation of complex mixtures of lignocellulosic hydrolysates. In this study, the hydrolysis products were separated and quantified by highperformance anion exchange chromatography with pulsed amperometric detection (HPAECPAD). This method was successfully applied to the quantitative analysis of monosaccharides (glucose and xylose) and disaccharides (cellobiose and xylobiose) formed by the enzymatic hydrolysis of pretreated miscanthus. The influence of the pretreatments on the oligosaccharides yields will be presented. [less ▲]

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See detailApplication of steam explosion for the pretreatment of the lignocellulosic raw materials
Jacquet, Nicolas ULg; Vanderghem, Caroline ULg; Blecker, Christophe ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(2), 561-566

Application of steam explosion for the pretreatment of the lignocellulosic raw materials. Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural ... [more ▼]

Application of steam explosion for the pretreatment of the lignocellulosic raw materials. Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural components by steam heating, hydrolysis of glycosidic bonds by organic acid formed during the process and shearing forces due to the expansion of the moisture. The process is composed of two distinct stages: vapocracking and explosive decompression. Cumul effects of both phases include modification of the physical properties of the material (specific surface area, water retention capacities, color, cellulose cristallinity rate,.), hydrolysis of hemicellulosic components (mono-and oligosaccharides released) and modification of the chemical structure of lignin. These effects permit the opening of lignocellulosic structures and increase the enzymatic hydrolysis rate of cellulose components in the aim to obtain fermentable sugars used in second generation biofuels or high value-added molecules process. [less ▲]

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See detailInfluence of homogenization and drying on the thermal stability of microfibrillated cellulose
QUIEVY, N.; Jacquet, Nicolas ULg; SCLAVONS, M. et al

in Polymer Degradation and Stability (2010), 95

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See detailInfluence of homogenization and drying on the thermal stability of microfibrillated cellulose
QUIEVY, N.; Jacquet, Nicolas ULg; SCLAVONS, M. et al

in Polymer Degradation and Stability (2010), 95

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See detailLa steam explosion : application en tant que prétraitement de la matière cellulosique
Jacquet, Nicolas ULg; Vanderghem, Caroline ULg; Blecker, Christophe ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(Spécial N°2),

Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural components by steam heating, hydrolysis of glycosidic bonds by organic acid formed during the ... [more ▼]

Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural components by steam heating, hydrolysis of glycosidic bonds by organic acid formed during the process and shearing forces due to the expansion of the moisture. The process is composed of two distinct stages: vapocracking and explosive decompression. Cumul effects of both phases include modification of the physical properties of the material (specific surface area, water retention capacities, color, cellulose cristallinity rate,…), hydrolysis of hemicellulosic components (mono and oligosaccharides released) and modification of the chemical structure of lignin. These effects permit the opening of lignocellulosic structures and increase the enzymatic hydrolysis rate of cellulose components in the aim to obtain fermentable sugars used in second generation biofuels or high value-added molecules process. [less ▲]

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See detailLA STEAM EXPLOSION : PRINCIPE ET ACTION SUR LES MATERIAUX LIGNOCELLULOSIQUES
Jacquet, Nicolas ULg; Blecker, Christophe ULg; Paquot, Michel ULg

Poster (2009, December 16)

La steam explosion est un procédé thermomécanochimique qui va permettre la déstructuration de la matière lignocellulosique par l’action combinée de la chaleur issue de la vapeur, des hydrolyses induites ... [more ▼]

La steam explosion est un procédé thermomécanochimique qui va permettre la déstructuration de la matière lignocellulosique par l’action combinée de la chaleur issue de la vapeur, des hydrolyses induites par la formation d’acides organiques et du cisaillement résultant de la chute brutale de pression. Le procédé est composé de deux phases distinctes. D’une part, le vapocraquage qui consiste à faire pénétrer par diffusion, puis à condenser, la vapeur sous haute pression à l’intérieur de la structure du matériau. L’eau condensée à température élevée va initier l’hydrolyse des groupements acétyles contenus dans les xylanes et induire la formation d’acides organiques. Selon la sévérité des conditions (pression, température), les acides vont catalyser l’hydrolyse des fractions hémicellulosiques, induire des modifications dans la structure des lignines et modifier le degré de cristallinité de la fraction cellulosique. D’autre part, la décompression explosive. Cette phase est provoquée par une chute brutale de pression qui va entraîner la revaporisation d’une partie de l’eau condensée. L’expension brutale de la vapeur va induire des forces de cisaillement qui vont modifier les propriétés physiques (granulométrie, surface spécifique, rétention d’eau…) du matériau. [less ▲]

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See detailVapocraquage et Steam Explosion
Jacquet, Nicolas ULg; Paquot, Michel ULg

Conference (2009, October 21)

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See detailIsothermal titration calorimetry as a tool for improving enzymatic lignocellulose hydrolysis
Razafindralambo, Hary ULg; Boquel, Pascal; Jacquet, Nicolas ULg et al

Conference (2008, December)

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See detailMECHANICAL PRETREATMENT EFFECT ON CELLULOSE ENZYMATICAL HYDROLYSIS
Jacquet, Nicolas ULg; Paquot, Michel ULg

Poster (2008)

Lignocellulosic materials are very interesting for the production of bioethanol after chemical or enzymatical hydrolysis of cellulose. To optimise production rate and increase the output of these ... [more ▼]

Lignocellulosic materials are very interesting for the production of bioethanol after chemical or enzymatical hydrolysis of cellulose. To optimise production rate and increase the output of these processes, different kinds of pre-treatments (grinding, steam explosion…) are often needed for opening the fibrous structure of the cellulose and increase the specific surface of the materials. The present study is focused on two models of “pure” cellulose (cellulose C200 microtechnik, cellulose FD100 FMC biopolymer) in order to analyse the effects of mechanical pretreatments on the kinetics and yields of hydrolysis. The cristallinity index differentiates the two celluloses. Hydrolysis is realized by a cellulase mix (cellulase Trichoderma reesei C2730, Novozyme; cellobiase Aspergillus niger C6105). Results present the influence of homogenisation pretreatment and analyse differents parameters of this technology. [less ▲]

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See detailSTUDY OF THE POSSIBILITY TO PRODUCE CELLULOSE MICROFIBRILS BY APPLYING SHEARING TREATMENTS TO CELLULOSE FIBERS
Jacquet, Nicolas ULg; Paquot, Michel ULg

Poster (2007, June 04)

Cellulose is a linear biopolymer composed of glucose residues linked by β 1-4 glucosidics bonds. These characteristics enable cellulose molecules to adopt an extended rod-like configuration. In the ... [more ▼]

Cellulose is a linear biopolymer composed of glucose residues linked by β 1-4 glucosidics bonds. These characteristics enable cellulose molecules to adopt an extended rod-like configuration. In the microfibrils, the multiple hydroxyl groups on the glucose residues hydrogen bond with each other, holding the chains firmly together and contributing to their high tensile strength. This study has shown the possibility to produce cellulose microfibrils by applying shearing treatment. Homogenisation and microfluidisation treatments permit to obtain microfibrils with 5 to 20 μm length and a 20 to 50 nm diameter. This study also shows that a tridimensional network, typical of a gel, appears in the treated samples [less ▲]

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See detailLe point sur la transplantation pancreatique.
De Roover, Arnaud ULg; Detry, Olivier ULg; Hamoir, Etienne ULg et al

in Revue Médicale de Liège (2001), 56(8), 557-62

Pancreas transplantation significantly improves the quality of life as well as the survival of the diabetic patient. It is also associated with stabilization and reversal of secondary diabetic ... [more ▼]

Pancreas transplantation significantly improves the quality of life as well as the survival of the diabetic patient. It is also associated with stabilization and reversal of secondary diabetic complications. Improvements in organ preservation, surgical techniques and immunosuppression have achieved one-year graft survival of more than 90% for combined kidney-pancreas transplant and 80% for isolated pancreas transplantation. Recipient evaluation must weigh the benefits of the procedure with the risk associated with surgery and chronic immunosuppression. Combined kidney-pancreas transplantation appears today as the best treatment for the diabetic patient with end stage renal disease. Isolated pancreas transplantation is reserved to non-uremic patients with severe diabetic complications or with brittle glycaemic control and severe impairment of quality of life. [less ▲]

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See detailLe chirurgien face aux polyendocrinopathies familiales: attitudes pratiques. Deuxieme partie: La polyendocrinopathie familiale type 2.
Meurisse, Michel ULg; Gérard, J; Plumacker, A. et al

in Revue medicale de Liege (1989), 44(23), 724-30

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