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See detailInfluence of the operating conditions on the production rate of multi-walled carbon nanotubes in a CVD reactor
Gommes, Cédric ULg; Blacher, Silvia ULg; Bossuot, C. et al

in Carbon (2004), 42(8-9), 1473-1482

A kinetic study is presented for the synthesis of multi-walled carbon nanotubes in a semi-continuous chemical vapor deposition reactor. The study is based on the use of a mass spectrometer that allows the ... [more ▼]

A kinetic study is presented for the synthesis of multi-walled carbon nanotubes in a semi-continuous chemical vapor deposition reactor. The study is based on the use of a mass spectrometer that allows the reaction rate to be inferred from the exhaust gas composition measurements. The tested reactor operating variables are the length and thickness of the catalytic bed, the total feed flow and the molar fraction of hydrocarbon in the feed. The results of the study are analyzed using well known reactor engineering models, which allows the origin of the observed physical limitations to be ascertained. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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See detailPlasmin-activated doxorubicin prodrugs containing a spacer reduce tumor growth and angiogenesis without systemic toxicity
Devy, L.; de Groot, F. M.; Blacher, Silvia ULg et al

in FASEB Journal (2004), 18(3), 565-567

To generate doxorubicin (Dox) specifically at the tumor site, the chemotherapeutic agent was incorporated into a prodrug by linkage to a peptide specifically recognized by plasmin, which is overproduced ... [more ▼]

To generate doxorubicin (Dox) specifically at the tumor site, the chemotherapeutic agent was incorporated into a prodrug by linkage to a peptide specifically recognized by plasmin, which is overproduced in many cancers. ST-9905, which contains an elongated self-elimination spacer, is activated more rapidly in vitro by plasmin than is ST-9802. Prodrug activation in vitro depended on the level of urokinase produced by tumor cells and was inhibited by aprotinin, a plasmin inhibitor. Comparison of equimolar concentrations of ST-9905, ST-9802, and Dox in EF43.fgf-4 and MCF7 models revealed that both prodrugs, in sharp contrast to Dox, displayed antiproliferative and antiangiogenic activities without discernible toxicity. Although MCF7 cells are poor urokinase producers in vitro, prodrug efficacy in this model may be explained by production of plasmin by tumor-infiltrating host cells. Mice treated with equitoxic concentrations (maximum tolerated doses) of prodrugs showed 100% survival and negligible body weight loss, in contrast to results after Dox treatment. ST-9905 was substantially more effective than ST9802 and induced similar tumor growth inhibition as Dox but without apparent toxicity. This finding may be explained by the elongated spacer, which facilitates enzymatic prodrug activation. These data validate both the use of elongated spacers in vivo and the concept of targeting anticancer prodrugs to tumor-associated plasmin. [less ▲]

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See detailImage analysis of X-ray microtomograms of soft materials during convective drying
Léonard, Angélique ULg; Blacher, Silvia ULg; Marchot, Pierre ULg et al

in Journal of Microscopy (2003), 212(Pt 2), 197-204

X-ray microtomography is used to explore the textural evolution that soft materials undergo during a drying treatment. An original image processing algorithm is applied to vertical projections and ... [more ▼]

X-ray microtomography is used to explore the textural evolution that soft materials undergo during a drying treatment. An original image processing algorithm is applied to vertical projections and reconstructed cross-section images in order to quantify the texture at different stages of drying. Measurements are performed both on grey-level and on binary images. It is shown that X-ray microtomography is a very promising tool in the field of drying investigations. It can be used to determine internal moisture profiles, and to follow crack development and shrinkage in an accurate and non-destructive way. This information is crucial to validate drying models. Waste-water sludges are used as test materials to assess the validity of the proposed methodology. The management of these sludges, often including a drying stage, will become a challenge in the forthcoming years in accordance with environmental regulations. Samples collected in two waste-water treatment plants are investigated. Their analysis by X-ray microtomography brings to the fore two different drying behaviours, illustrating that sludge drying is a complex unit operation very sensitive to the way the material is produced. [less ▲]

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See detailCaractérisation par analyse d'images de nanotubes multiparois
Gommes, Cédric ULg; Masenelli-Varlot; Pirard, Jean-Paul ULg et al

Scientific conference (2003, October)

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See detailTime-resolved SAXS measurements of phase separation during silica gel formation
Gommes, Cédric ULg; Goderis, Bart; Pirard, Jean-Paul ULg et al

Poster (2003, October)

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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 detailRestricted expression of membrane type 1-matrix metalloproteinase by myofibroblasts adjacent to human breast cancer cells
Bisson, C.; Blacher, Silvia ULg; Polette, M. et al

in International Journal of Cancer = Journal International du Cancer (2003), 105(1), 7-13

The membrane type-1 matrix metalloproteinase (MT1-MMP), a protease originally identified in breast carcinoma, is characterized by its capacity to activate other MMPs (MMP-2 and MMP-13) and to degrade ... [more ▼]

The membrane type-1 matrix metalloproteinase (MT1-MMP), a protease originally identified in breast carcinoma, is characterized by its capacity to activate other MMPs (MMP-2 and MMP-13) and to degrade extracellular matrix. Our study was undertaken to localize and identify the MT1-MMP expressing cells in human breast adenocarcinomas. A textural analysis of images obtained by immunohistochemistry and in situ hybridization showed precisely the co-expression of alpha smooth muscle actin (alphaSM actin) and MT1-MMP in myofibroblasts. MT1-MMP expression is confined to myofibroblasts in close contact with tumor cells. In sharp contrast, the expression of MMP-2 was more widely distributed in both alphaSM actin positive and negative cells close to and at distance from cancer cell clusters. Our in vitro observations are consistent with the higher level of MT1-MMP expression and of MMP-2 activation observed in alphaSM actin positive fibroblasts derived from breast tumors, as compared to normal breast fibroblasts. Collectively, these results implicate myofibroblasts as major producer of MT1-MMP in breast cancer and emphasize the importance of stromal-epithelial cell interactions in their progression. [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 detailStabilization of a cocontinuous phase morphology by a tapered diblock or triblock copolymer in polystyrene-rich low-density polvethylene/polstyrene blends
Harrats, Charef; Fayt, Roger; Jérôme, Robert ULg et al

in Journal of Polymer Science. Part B, Polymer Physics (2003), 41(2), 202-216

The stability against the thermal annealing of a cocontinuous two-phase morphology developed in polystyrene (PS)/low-density polyethylene (LDPE) blends containing 80 wt % PS was investigated. Blends ... [more ▼]

The stability against the thermal annealing of a cocontinuous two-phase morphology developed in polystyrene (PS)/low-density polyethylene (LDPE) blends containing 80 wt % PS was investigated. Blends containing 1, 5, and 10 wt % of a tapered diblock poly(styrene-block-hydrogenated butadiene) (P(S-b-hB)) or triblock poly(styrene-block-hydrogenated butadiene-block-styrene) (P(S-hB-S)) copolymer were melt-blended with roll-mill mixing equipment. The efficiency of each of the two copolymers in stabilizing against coalescence the cocontinuous morphology was examined. The tensile properties of the resulting blends, annealed and nonannealed, were also examined in relation to the morphology induced by thermal annealing. The phase morphology was studied by optical and scanning electron microscopy. With computer-aided image analysis, it was possible to obtain a measurable characteristic parameter to quantify the cocontinuous phase morphology. When it was necessary, the extraction of one phase with a selective solvent was performed. Although the observed differences were subtle, the tapered diblock exhibited a more efficient compatibilizing activity than the triblock copolymer, particularly at a low concentration of about 2 wt %. The superiority of the tapered diblock over the triblock might be due to its ability to quantitatively locate at the LDPE/PS interface and consequently form a more efficient barrier against the subsequent breakup of the elongated structures of the cocontinuous phase morphology. The tensile properties of the triblock-modified blends were more sensitive to thermal annealing than the tapered-modified ones. This deficiency was ascribed to the phase morphology coarsening of the dispersed polyethylene phase. [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 detailHydrodynamique et morphologie d'une bactérie filamenteuse dans un fermenteur à cuve agitée
Groslambert, Sylvie ULg; Blacher, Silvia ULg; Crine, Michel ULg

in Tribune de l'Eau (La) (2003), 56(622), 58-64

Afin d'étudier l'influence de l'hydrodynamique sur une bactérie filamenteuse, Actinomadura R39, nous l'avons cultivée dans un fermenteur de laboratoire de 5 litres à cuve agitée en faisant varier les ... [more ▼]

Afin d'étudier l'influence de l'hydrodynamique sur une bactérie filamenteuse, Actinomadura R39, nous l'avons cultivée dans un fermenteur de laboratoire de 5 litres à cuve agitée en faisant varier les conditions d'agitation. Les variables sont la vitesse de rotation et le type de mobile utilisé: turbines Rushton ou Intermig. Les deux mobiles se distinguent par leur géométrie et par les schémas d'écoulement qu'ils induisent dans la cuve. L'influence de l'hydrodynamique sur Actinomadura R39 est quantifiée par l'évolution de sa morphologie. Cette dernière est estimée par analyse d'images sur des échantillons prélevés lors des cultures. Parallèlement, nous avons caractérisé l'hydrodynamique du fermenteur dans un milieu artificiel reproduisant la rhéologie des fermentations en mesurant la puissance dissipée et en effectuant des essais de traceurs. Ces derniers sont utilisés pour la modélisation du fermenteur par un modèle compartimenté et le calcul du temps de mélange. Nous avons pu ainsi mettre en relation les modifications de la morphologie et des grandeurs caractérisant les écoulements dans le fermenteur. L'existence de corrélations entre les paramètres du modèle et la morphologie a également permis une validation de la signification physique de ce modèle. [less ▲]

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