References of "Pirard, Jean-Paul"
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See detailConvective drying of wastewater sludges: Influence of air temperature, superficial velocity and humidity on the kinetics
Léonard, Angélique ULg; Blacher, Silvia ULg; Marchot, Pierre ULg et al

in Pakowski, Zdzislaw (Ed.) X Drying Symposium, Lodz, 17-19 September 2003 (2003, September)

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See detailUse of X-ray microtomography to determine internal moisture profiles during convective drying of deformable materials
Léonard, Angélique ULg; Blacher, Silvia ULg; Marchot, Pierre ULg et al

in Saravacos, G.; Maroulis, Z. B.; Krokida, M. (Eds.) et al Proceedings of the European Drying Symposium - EuDrying03 (2003, September)

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See detailMoisture profiles determination during convective drying using X-ray microtomography
Léonard, Angélique ULg; Blacher, Silvia ULg; Marchot, Pierre ULg et al

in Proceedings of the 3rd World Congress on Industrial Process Tomography, Banff, Canada (2003, September)

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See detailPreparation of macroporous biodegradable poly(L-lactide-co-epsilon-caprolactone) foams and characterization by mercury intrusion porosimetry, image analysis, and impedancy spectroscopy
Maquet, Véronique; Blacher, Silvia ULg; Pirard, René ULg et al

in Journal of Biomedical Materials Research (2003), 66A(2), 199-213

Two poly(L-lactide-co-epsilon-caprolactone) random copolymers containing 5 and 40 mol% of epsilon-CL, namely P(LA-co-CL5) and P(LA-co-CL40), respectively, have been made macroporous by freeze-drying ... [more ▼]

Two poly(L-lactide-co-epsilon-caprolactone) random copolymers containing 5 and 40 mol% of epsilon-CL, namely P(LA-co-CL5) and P(LA-co-CL40), respectively, have been made macroporous by freeze-drying solutions in dimethylcarbonate. Most of the freeze-dried foams, prepared by varying polymer concentration and cooling rate, exhibited two main pore populations: (1) longitudinally oriented tube-like macropores with diameters greater than or equal to100 mum, and (2) interconnected micropores (10-100 mum). Pore characteristics, including macropore density, mean diameter, and interdistance, as well as micropore density, area, and shape, were determined by image analysis of scanning electron micrographs in order to study the influence of processing and formulation parameters on foam structure and properties. The pore orientation and the 3-D texture also were studied by image analysis and impedance spectroscopy. In the case of the P(LA-co-CL5), the macropore diameter increased with the cooling rate while the micropore diameter decreased. The micropores also became more circular when the cooling rate was increased. The pore size and morphology of the P(LA-co-CL40) were quite unchanged by varying the cooling rate. All the other conditions being the same, the P(LA-co-CL5) foams were better organized than the P(LA-co-CL40) foams, and pore orientation was improved at the higher cooling rate. Pore size and morphology also can be controlled by changing the polymer concentration (Cp), as we showed by studying P(LA-co-CL5) foams prepared by freeze-drying solutions in the 1-10 w/v% Cp range. Macropore density, average diameter, and interdistance of P(LA-co-CL5) foams increased with Cp, but the micropore characteristics remained almost unchanged no matter the Cp. The reliability of the characterization methods has been discussed, with special attention to mercury intrusion porosimetry, which is used primarily for measurement of pore volume and pore size distribution. However, this technique is reported here as a destructive and unreliable method for the characterization of fragile P(LA-co-CL40) foams. This study shows that image analysis and impedance spectroscopy can give reliable information relative to the pore morphology and anisotropy of freeze-dried foams. [less ▲]

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See detailPreparation of low-density xerogels from mixtures of TEOS with substituted alkoxysilanes. II. Viscosity study of the sol-gel transition
Alié, Christelle ULg; Pirard, René ULg; Pirard, Jean-Paul ULg

in Journal of Non-Crystalline Solids (2003), 320(1-3), 31-39

Mixtures of TEOS with substituted methoxysilanes generate low-density xerogels due to a nucleation mechanism involving the substituted alkoxysilane. The sol-gel transition of these mixtures was followed ... [more ▼]

Mixtures of TEOS with substituted methoxysilanes generate low-density xerogels due to a nucleation mechanism involving the substituted alkoxysilane. The sol-gel transition of these mixtures was followed by theological characterisation. The transition from sol to gel takes place in a few minutes at ambient temperature. For the series exhibiting nucleation by the additive. the gel time goes through a slight minimum when the ratio of additive/main reagent increases. The elastic modulus increases with increasing ratio of additive/main reagent as the particle size decreases because of the nucleation mechanism by the additive. Samples with smaller particles exhibit the highest modulus for equal silica concentrations. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailPreparation of low-density xerogels from mixtures of TEOS with substituted alkoxysilanes. I. O-17 NMR study of the hydrolysis-condensation process
Alié, Christelle ULg; Pirard, Jean-Paul ULg

in Journal of Non-Crystalline Solids (2003), 320(1-3), 21-30

Low-density xerogels were synthesised by incorporation of an additive to base catalysed tetraethylorthosilicate (TEOS) alcogels directly during the preparation of the sol. The nucleation mechanism by the ... [more ▼]

Low-density xerogels were synthesised by incorporation of an additive to base catalysed tetraethylorthosilicate (TEOS) alcogels directly during the preparation of the sol. The nucleation mechanism by the additive was established by experiments during sol-gel transition. O-17 NMR spectroscopy on TEOS-ethanol-water, 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS)-ethanol-water and EDAS-TEOS-ethanol-water solutions shows that the hydrolysis-condensation of EDAS is much faster than that of TEOS. Consequently it can be assumed that EDAS forms nuclei, onto which TEOS condenses later to form the silica particles. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailImage analysis of the axonal ingrowth into poly(D,L-lactide) porous scaffolds in relation to the 3-D porous structure
Blacher, Silvia ULg; Maquet, Véronique; Luyckx, Françoise ULg et al

in Biomaterials (2003), 24(6), 1033-1040

Porous polymer scaffolds are promising materials for neural tissue engineering because they offer valuable three-dimensional (3D) supports for the in vitro and in vivo axonal growth and tissue expansion ... [more ▼]

Porous polymer scaffolds are promising materials for neural tissue engineering because they offer valuable three-dimensional (3D) supports for the in vitro and in vivo axonal growth and tissue expansion. At the time being, how the in vivo neuronal cell development depends on the scaffold 3-D architecture is unknown. Therefore, scanning electron micrographs of longitudinal sections of porous polylactide scaffolds and immunohistological sections of these scaffolds after implantation and neurofilament staining have been studied by image analysis. Pore orientation and axonal ingrowth have been investigated by spectral analysis on gray level SEM images. Binary image processing has been carried out and the binary images have been studied by spectral analysis in order to estimate the possible effect of the image noise on the real pattern. In addition to axonal orientation, density and length distribution of the regenerated axons into the polymer scaffold have been measured. Dependence of the axonal ingrowth on the 3D-polymer scaffold has been discussed on the basis of the collected data. (C) 2002 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailImage analysis characterization of multi-walled carbon nanotubes
Gommes, Cédric ULg; Blacher, Silvia ULg; Masenelli-Varlot, Karine et al

in Carbon (2003), 41(13), 2561-2572

An original image analysis method is presented to characterize multi-walled carbon nanotubes from transmission electron microscopy images. The analysis is performed in three steps: (i) image preprocessing ... [more ▼]

An original image analysis method is presented to characterize multi-walled carbon nanotubes from transmission electron microscopy images. The analysis is performed in three steps: (i) image preprocessing in order to isolate the nanotubes from the background, (ii) image segmentation, aiming at keeping only the measurable sections of nanotubes, and finally (iii) tube characteristics measurement. The measurement is based on a Lambert-like electron absorption law and is performed on the original gray level image itself. Two geometrical and one physical characteristics are determined for each tube, namely, its outer and inner radius and a linear electron absorption coefficient. The method is illustrated by comparing a pristine and an annealed carbon nanotube samples. The compaction of the tube walls during annealing is shown to result from a lowering of the external radius while the inner radius is left unchanged. (C) 2003 Elsevier Ltd. All rights reserved. [less ▲]

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See detailPorous carbon material
Pirard, Jean-Paul ULg; Pirard, René ULg; Job, Nathalie ULg

Patent (2003)

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See detailNucleation phenomenon in silica xerogels and Pd/SiO2, Ag/SiO2, Cu/SiO2 cogelled catalysts
Alié, Christelle ULg; Lambert, Stéphanie ULg; Heinrichs, Benoît ULg et al

in Journal of Sol-Gel Science and Technology (2003), 26(1-3), 827-830

Pd/SiO2, Ag/SiO2 and Cu/SiO2 xerogel catalysts have been synthesized by cogelation of tetraethoxysilane (TEOS) and chelates of Pd, Ag and Cu with 3-(2-aminoethylamino) propyltrimethoxysilane (EDAS). It ... [more ▼]

Pd/SiO2, Ag/SiO2 and Cu/SiO2 xerogel catalysts have been synthesized by cogelation of tetraethoxysilane (TEOS) and chelates of Pd, Ag and Cu with 3-(2-aminoethylamino) propyltrimethoxysilane (EDAS). It appears that, in cogelled samples, the metal complex acts as a nucleation agent in the formation of silica particles. The resulting catalysts are then composed of completely accessible metallic crystallites with a diameter of about 3 nm located inside silica porous particles with a monodisperse microporous distribution. Xerogels without metal synthesized with EDAS and TEOS (C. Alie, R. Pirard, A. J. Lecloux, and J.-P. Pirard, J. Non-Cryst. Solids 289, 88 (2001)) verify this hypothesis of nucleation by EDAS. [less ▲]

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See detailCharacterization of hyperporous polyurethane-based gels by non-intrusive mercury porosimetry
Pirard, René ULg; Rigacci, Arnaud; Marechal, Jacqueline ULg et al

in Polymer (2003), 44(17), 4881-4887

Evaporative drying of polyurethane-based gels produces xerogels. Supercritical drying after replacement of interstitial liquid by supercritical CO2 produces aerogels. SEM micrographs show that both ... [more ▼]

Evaporative drying of polyurethane-based gels produces xerogels. Supercritical drying after replacement of interstitial liquid by supercritical CO2 produces aerogels. SEM micrographs show that both materials are made up of small size particles gathered up in filament-shaped, strongly cross-linked aggregates. Density measurements show that they both have a large pore volume. When submitted to mercury porosimetry, the behavior of these materials is similar to that of inorganic aerogels, as previously observed. Mercury does not penetrate the pore network, but the whole material is densified. The usual Washburn equation cannot be used to analyze the mercury porosimetry. A well-suited equation based on a buckling model of filament-shaped aggregates has been developed in order to determine the pore volume distribution of mineral dried gels. This equation is also valid for analyzing the texture of organic hyperporous materials like polyurethane dried nanoporous gel. (C) 2003 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailMultiscale texture characterization of wastewater sludges dried in a convective rig
Léonard, Angélique ULg; Blacher, Silvia ULg; Pirard, René ULg et al

in Drying Technology (2003), 21(8), 1507-1526

Secondary sludges from two different wastewater treatment plants are conditioned and dewatered in the same way before drying in a lab-scale convective rig at the same operating conditions. Several ... [more ▼]

Secondary sludges from two different wastewater treatment plants are conditioned and dewatered in the same way before drying in a lab-scale convective rig at the same operating conditions. Several techniques are used to characterize the texture of the dried materials over a wide range of scales from nm up to mm. Texture and porosity of the dried products are studied by SEM imaging, nitrogen absorption isotherms (0.5 < d(p) < 50 nm), mercury porosimetry (7.5 nm < d(p) < 150 mum) and X-ray microtomography (spatial resolution= 41 mum). The image analysis of cross-sections reconstructed by microtomography also allows following shrinkage and textural evolution during drying. [less ▲]

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See detailSpectroscopic characterisation of Pd/SiO2 sol-gel prepared catalysts
Beketov, Gennadiy; Heinrichs, Benoît ULg; Lambert, Stéphanie ULg et al

Poster (2003)

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See detailFe/SiO2 sol-gel catalysts synthesised from various iron complexes for N2O decomposition and C3H6 oxidation by N2O
Heinrichs, Benoît ULg; Maxim, Nicolae; Abbenhuis, Hendrikus C L et al

Poster (2003)

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See detailPreparation and characterization of xerogel catalyst microspheres
Alié, Christelle ULg; Ferauche, Fabrice; Heinrichs, Benoît ULg et al

Conference (2003)

For easier handling and use in fixed bed reactors, Pd-Ag/SiO2 aerogel-like xerogel catalysts were shaped into microspheres using the microencapsulation process developed by BRACE GmbH. Before the bead ... [more ▼]

For easier handling and use in fixed bed reactors, Pd-Ag/SiO2 aerogel-like xerogel catalysts were shaped into microspheres using the microencapsulation process developed by BRACE GmbH. Before the bead production process, the xerogel catalyst was ground in water and mixed with ethylene glycol and sodium alginate, the latter of which is the gelation agent. The beads were formed at a vibrating nozzle and solidified during their fall in a water tank containing calcium ions, which induce cross-linking of the alginate and consequent bead hardening. Preliminary work was done using a syringe instead of the material-consuming BRACE unit. The beads were made from a suspension of dried only, dried and calcined, or dried, calcined, and reduced catalyst. The textural properties of the beads were analyzed by nitrogen adsorption-desorption isotherms and mercury porosimetry; and bead catalytic activity was tested for selective hydrodechlorination of 1,2-dichloroethane. The beads made from a suspension of dried catalyst appear to have properties the closest to that of the xerogel reference catalyst. Porosity and surface area are maintained at their level before bead formation. However conversion of 1,2-dichloroethane decreases after the production process, possibly due to poisoning by calcium ions. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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