References of "Goderis, Bart"
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See detailThe Structure and Thermal Stability of Amylose−Lipid Complexes: A Case Study on Amylose−Glycerol Monostearate
Goderis, Bart; Putseys, Joke; Gommes, Cédric ULg et al

in Journal of Crystal Growth (2014)

Three different crystalline amylose−glycerol monostearate (GMS) complexes with increasing thermal stability can be distinguished: type I, type IIa, and type IIb. All complexes consist of GMS-loaded ... [more ▼]

Three different crystalline amylose−glycerol monostearate (GMS) complexes with increasing thermal stability can be distinguished: type I, type IIa, and type IIb. All complexes consist of GMS-loaded amylose helices that pack hexagonally into lamellar habits. The complex melting points are proportional to the thickness of the lamellae and depend on the amount of water in the system. For type I complexes, SAXS experiments reveal folded amylose chains and a lamellar thickness governed by the presence of two stretched lipid molecules per amylose helix. In the conversion from type I to type IIa complexes, the short amylose chains unfold and assume a stretched conformation, which increases the number of aligned lipid molecules within the helices to four. In type IIb complexes, another pair of lipid molecules is added. The derived quantitative relation between crystal layer thickness, water content and melting point for amylose−GMS complexes also predicts the melting points of other amylose−monoacyl glycerol complexes. [less ▲]

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See detailMolecular and Morphological Aspects of Annealing-Induced Stabilization of Starch Crystallites
Gomand, Sara; Lamberts, Lieve; Gommes, Cédric ULg et al

in Biomacromolecules (2012), 13

A unique series of potato (mutant) starches with highly different amylopectin/amylose (AP/AM) ratios was annealed in excess water at stepwise increasing temperatures to increase the starch melting (or ... [more ▼]

A unique series of potato (mutant) starches with highly different amylopectin/amylose (AP/AM) ratios was annealed in excess water at stepwise increasing temperatures to increase the starch melting (or gelatinization) temperatures in aqueous suspensions. Small-angle X-ray scattering (SAXS) experiments revealed that the lamellar starch crystals gain stability upon annealing via thickening for high-AM starch, whereas the crystal surface energy decreases for AM-free starch. In starches with intermediate AP/AM ratio, both mechanisms occur, but the surface energy reduction mechanism prevails. Crystal thickening seems to be associated with the cocrystallization of AM with AP, leading to very disordered nanomorphologies for which a new SAXS data interpretation scheme needed to be developed. Annealing affects neither the crystal internal structure nor the spherulitic morphology on a micrometer length scale. [less ▲]

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See detailBridging the gap between cellulose chemistry and heterogeneous catalysis
Van de Vyver, S; Geboers, J; Peng, Li et al

in WIT Transactions on Ecology and the Environment (2011), 154

Although cellulosic biomass offers a promising alternative as an abundant renewable resource in the production of biofuels and platform chemicals, so far only a few studies have reported its aqueous-phase ... [more ▼]

Although cellulosic biomass offers a promising alternative as an abundant renewable resource in the production of biofuels and platform chemicals, so far only a few studies have reported its aqueous-phase conversion into glucose or sugar alcohols using solid chemocatalysts. The principal reason is that these polymeric biomolecules with semi-crystalline structure cannot penetrate the pores of conventional heterogeneous chemocatalysts. New advances in the conversion of cellulose thus require the design of efficient multifunctional catalytic systems with sterically accessible acid and metal sites. [less ▲]

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See detailIn situ SAXS under shear unveils the gelation of aqueous starch suspensions and the impact of added amylose-lipid complexes
Putseys, Joke; Gommes, Cédric ULg; Van Puyvelde, P. et al

in Carbohydrate Polymers (2011), 84

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See detailModeling the morphology and mechanical behavior of shape memory polyurethanes based on solid-state NMR and synchrotron SAXS/WAXD
D'Hollander, Stijn; Gommes, Cédric ULg; Mens, Raoul et al

in Journal of Materials Chemistry (2010), 20

A combination of solid-state proton Wide-line Nuclear Magnetic Resonance (NMR) relaxometry and synchrotron Small-angle (SAXS) and Wide-angle (WAXD) X-ray scattering was used to elucidate the microphase ... [more ▼]

A combination of solid-state proton Wide-line Nuclear Magnetic Resonance (NMR) relaxometry and synchrotron Small-angle (SAXS) and Wide-angle (WAXD) X-ray scattering was used to elucidate the microphase morphology of shape memory thermoplastic multi-block polyurethanes based on poly(3-caprolactone), as switching segment and polyurethane based permanent or hard segments (HS). The polyurethanes are produced from the condensation of 1,4-butanediol (BDO) with hexamethylenediisocyanate (HDI). The morphology – induced by the hard-segment crystallization – converts from dispersed randomly placed hard-segment domains into progressively more periodic, but interconnected HS nanophases with increasing HS content. Irrespective of the actual morphology, the SAXS data could be described satisfactorily by using a clipped Gaussian random field (GRF) model. The NMR data demonstrate that the HS domain fraction corresponds to the chemical feed, pointing at a complete phase separation. The material mechanical behavior during repeated deformation cycles can be explained on morphological grounds and involves a spatially heterogeneous plastic deformation of the hard domains. [less ▲]

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See detailConeX: a program for angular calibration and averaging of two-dimensional powder scattering patterns
Gommes, Cédric ULg; Goderis, Bart

in Journal of Applied Crystallography (2010), 43

CONEX is a Windows application for converting series of two-dimensional X-ray powder patterns measured on flat two-dimensional detectors into onedimensional scattering patterns. It is based on the ... [more ▼]

CONEX is a Windows application for converting series of two-dimensional X-ray powder patterns measured on flat two-dimensional detectors into onedimensional scattering patterns. It is based on the rigorous use of scattering patterns of calibration samples to determine the three-dimensional position of the detector, with respect to the sample and to the beam. This enables correction of the data for geometric distortions, even when the detector is highly tilted and not centred on the beam. [less ▲]

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See detailSulfonated silica/carbon nanocomposites as novel catalysts for hydrolysis of cellulose to glucose
van de Vijver, Stijn; Peng, Li; Geboers, Jan et al

in Green Chemistry (2010), 12

Sulfonated silica/carbon nanocomposites were successfully developed as reusable, solid acid catalysts for the hydrolytic degradation of cellulose into high yields of glucose.

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See detailCondensation-Induced Decrease of Small-Angle X-ray Scattering Intensity in Gelling Silica Solutions
Gommes, Cédric ULg; Pirard, Jean-Paul ULg; Goderis, Bart

in Journal of Physical Chemistry C: Nanomaterials, Interfaces, and Hard Matter (2010), 114

We propose a mathematical modeling of the total SAXS intensity in silica sol-gel processes in terms of hydrolysis and condensation reactions, as well as of microsyneresis. The results are used to ... [more ▼]

We propose a mathematical modeling of the total SAXS intensity in silica sol-gel processes in terms of hydrolysis and condensation reactions, as well as of microsyneresis. The results are used to rationalize previously published SAXS data of TEOS solutions reacting with organically modified trialkoxysilanes. We notably show that the decrease in SAXS intensity reported for these samples at the end of gelation is a consequence of condensation reactions. The water released by the latter reactions contributes to reduce the electron density difference between the silica and the solvent phases of the gels [less ▲]

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See detailSAXS Data Analysis of Ordered and Disordered Morphologies With Gaussian Random Field Models
Gommes, Cédric ULg; Goderis, Bart

Conference (2009, September)

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See detail15 Minutes about SAXS and gels
Gommes, Cédric ULg; Goderis, Bart; Pirard, Jean-Paul ULg

Scientific conference (2009, May)

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See detailIn-situ SAXS of resorcinol-formaldehyde gel formation: either colloid aggregation or microphase separation
Gommes, Cédric ULg; Roberts, Anthony; Goderis, Bart

Poster (2008, October)

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See detailCritical opalescence points to thermodynamic instability:relevance to small-angle X-ray scattering of resorcinol–formaldehyde gel formation at low pH
Gommes, Cédric ULg; Job, Nathalie ULg; Pirard, Jean-Paul ULg et al

in Journal of Applied Crystallography (2008), 41(4), 663-668

During the formation at low pH of resorcinol–formaldehyde gels with a structure in the micrometre range, small-angle X-ray scattering exhibits a nonmonotonic intensity variation as a function of reaction ... [more ▼]

During the formation at low pH of resorcinol–formaldehyde gels with a structure in the micrometre range, small-angle X-ray scattering exhibits a nonmonotonic intensity variation as a function of reaction time. The data are analyzed in terms of scattering by statistical fluctuations of polymer concentration, the amplitude of which is maximal close to the critical point for phase separation between polymer and solvent. The data do not carry any morphological information, but they unambiguously show that the driving force of the gel formation is a thermodynamic instability of the polymerizing solution. [less ▲]

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See detailBranching, aggregation, and phase separation during the gelation of tetraethoxysilane
Gommes, Cédric; Goderis, Bart; Pirard, Jean-Paul ULg et al

in Journal of Non-Crystalline Solids (2007), 353(24-25), 2495-2499

Time-resolved small-angle X-ray scattering is used to follow in situ the structuring of silica sols and gels in various chemical conditions. The acid-catalyzed and base-catalyzed polymerizations of TEOS ... [more ▼]

Time-resolved small-angle X-ray scattering is used to follow in situ the structuring of silica sols and gels in various chemical conditions. The acid-catalyzed and base-catalyzed polymerizations of TEOS, as well as the copolymerization of TEOS with organically modified trialkoxysilanes, are followed. The analysis points to the diversity of the mechanisms that govern the structuring of the reacting solutions, and most notably to the important role of physical forces. (C) 2007 Elsevier B.V.All rights reserved. [less ▲]

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See detailRelevance of Spinodal Decomposition for Support Formation and Metal Dispersion in Cogelled Pd/SiO2 Catalysts
Gommes, Cédric ULg; Goderis, Bart; Pirard, Jean-Paul ULg

in Journal of Physical Chemistry C (2007), 111

The structure formation of cogelled Pd/SiO2 catalysts is followed in situ at the nanometer scale using timeresolved small-angle X-ray scattering (SAXS). The SAXS patterns are analyzed in terms of a ... [more ▼]

The structure formation of cogelled Pd/SiO2 catalysts is followed in situ at the nanometer scale using timeresolved small-angle X-ray scattering (SAXS). The SAXS patterns are analyzed in terms of a reaction-induced spinodal decomposition that is responsible for the formation of the silica support and most likely for the metal dispersion as well. The results are discussed in the light of recent electron tomography characterizations of the catalysts. The latter technique reveals regularity in the metal dispersion, the origin of which is likely to be the very occurrence of a spinodal phase separation. [less ▲]

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See detailRole of co-reactants during the formation of silica gels assessed by in situ SAXS
Gommes, Cédric ULg; goderis, bart; Pirard, Jean-Paul ULg et al

Conference (2006, August)

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See detailStructure of Silica Xerogels Synthesized with Organoalkoxysilane Co-reactants Hints at Multiple Phase Separation
Gommes, Cédric ULg; Basiura, Monika; Goderis, Bart et al

in Journal of Physical Chemistry B (2006), 110

The microstructure of hybrid silica xerogels synthesized by the base-catalyzed polymerization of tetraethoxysilane (TEOS) in ethanol in the presence of 3-aminopropyltriethoxysilane (AES) and of 3-(2 ... [more ▼]

The microstructure of hybrid silica xerogels synthesized by the base-catalyzed polymerization of tetraethoxysilane (TEOS) in ethanol in the presence of 3-aminopropyltriethoxysilane (AES) and of 3-(2-aminoethylamino)- propyltrimethoxysilane (EDAS) as co-reactants, and dried in subcritical conditions, is analyzed. A thorough structural characterization of the samples is performed combining nitrogen adsorption, small-angle X-ray scattering (SAXS), and transmission electron microscopy coupled with digital image analysis. The use of these methods shows that, for both co-reactants, the xerogels are made of macropores supported by filaments, with each filament being formed of smaller structures. The quantitative impact of the additive on each structural level is assessed. The data are compared with a previous time-resolved SAXS study conducted during the formation of the gels (J. Phys. Chem. B 2004, 108, 8983-8991). The results are analyzed in the framework of a double phase separation model. [less ▲]

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See detailPhase separation during silica gel formation followed by time-resolved SAXS
Gommes, Cédric; Blacher, Silvia ULg; Goderis, Bart et al

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2005), 238(1-4), 141-145

Time-resolved small angle X-ray scattering data are collected during the formation of silica gels from the base catalyzed polymerization of tetraethoxysilane in ethanol with 3-(2-aminoethylamino ... [more ▼]

Time-resolved small angle X-ray scattering data are collected during the formation of silica gels from the base catalyzed polymerization of tetraethoxysilane in ethanol with 3-(2-aminoethylamino)propyltrimethoxysilane and 3-aminopropyltriethoxysilane as additives. It is shown that a polymerization-induced spinodal demixing occurs during the gel formation. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailPhase separation during silica gel formation followed by time-resolved SAXS
Gommes, Cédric ULg; Goderis, Bart; Pirard, Jean-Paul ULg et al

Poster (2004, August)

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See detailIn situ SAXS analysis of silica gel formation with an additive
Gommes, Cédric ULg; Blacher, Silvia ULg; Goderis, Bart et al

in Journal of Physical Chemistry B (2004), 108(26), 8983-8991

Time-resolved small-angle X-ray scattering (SAXS) measurements performed during the formation of tetraethyl orthosilicate (TEOS) based silica gels in alcohol with 3-(2-aminoethylamino ... [more ▼]

Time-resolved small-angle X-ray scattering (SAXS) measurements performed during the formation of tetraethyl orthosilicate (TEOS) based silica gels in alcohol with 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS) as an additive are reported. The measurements reveal no discontinuity of the nanostructure at the gel point. A chemically induced spinodal phase separation is found to give a coherent picture of the collected data. Increasing the amount of EDAS induces the phase separation on a smaller length scale, which finally leads to a modified gel morphology. The SAXS measurements and the electron micrographs associated with the dry gels could be interpreted in terms of the suggested wet gel formation mechanism. [less ▲]

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