Synthesis of microsphere-loaded porous polymers by combining emulsion and dispersion polymerisations in supercritical carbon dioxide.

Highly porous materials were produced by acrylamide polymerisation templated by supercritical CO(2)-in-water emulsions using new fluorinated glycosurfactants. Properties of the resulting polymer scaffolds were tuned by performing dispersion polymerisations within their cavities filled with supercritical CO(2).

Morphological models of complex ordered materials based on inhomogeneously clipped Gaussian fields.

Clipping a Gaussian random field at a level that is position-dependent yields statistically inhomogeneous morphologies, relevant to many ordered nanostructured materials. The one-point and two-point probability functions of the morphology are derived, as well as a general relation between the specific surface area and the gradient of the clipping function. The general results are particularized for the comprehensive analysis of small-angle x-ray scattering and nitrogen adsorption of SBA-15 ordered mesoporous silica.

Two methods of random seed generation to avoid over-segmentation with stochastic watershed: application to nuclear fuel micrographs.

A stochastic version of the watershed algorithm is obtained by choosing randomly in the image the seeds from which the watershed regions are grown. The output of the procedure is a probability density function corresponding to the probability that each pixel belongs to a boundary. In the present paper, two stochastic seed-generation processes are explored to avoid over-segmentation.

Multiscale image analysis of microcellular solids: application to hybrid silica xerogels.

A general methodology is proposed to characterize microcellular solids, the structure of which consists of a three-dimensional network of filamentary structures. The analysis is based on transmission electron microscopy observation of the filaments individually and of their spatial arrangement. The micrographs are analyzed with grey-tone digital image analysis techniques, such as opening granulometry and correlation analysis.

Non-destructive characterization of deer (Cervus Elaphus) antlers by X-ray microtomography coupled with image analysis.

X-ray microtomography coupled with image analysis was tested as a non-destructive alternative method for the textural characterization of the trabecular part of deer antlers (Cervus Elaphus). As gas adsorption and mercury intrusion cannot be applied on this soft and spongy material, its pore texture was, up to now, determined from histological sections that give only two-dimensional information. In this work, X-ray microtomography is used to scan entire or half pieces of antlers and three-dimensional image analysis is performed in order to assess the differences between samples collected at various antler locations.

Study of the connectivity properties of Bioglass -filled polylactide foam scaffolds by image analysis and impedance spectroscopy.

The porous structure of two series of poly(D,L-lactide)/Bioglass composite foams prepared by thermal-induced phase separation was investigated by image analysis and impedance spectroscopy. Polymer solutions of either low or high molecular weight containing different concentrations (up to 50 wt.%) of Bioglass particles of mean particle size d < 5 microm were studied.

Structure of silica xerogels synthesized with organoalkoxysilane co-reactants hints at multiple phase separation.

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.

Assessment of the 3D localization of metallic nanoparticles in Pd/SiO2 cogelled catalysts by electron tomography.

The purpose of this study is to analyze the localization of palladium nanoparticles within their silica support, in two heterogeneous catalysts synthesized by the sol-gel process, with different metal loadings. Electron tomography demonstrates that the palladium particles are localized deep inside the silica skeleton. The use of digital image analysis further shows that the dispersion of palladium is optimal in the sample with the lowest loading.

Image analysis of X-ray microtomograms of soft materials during convective drying: 3D measurements.

Drying dewatered sludge leads to a complex three-dimensional porous structure. Moreover, this operation is dependent on the way the material is processed. In this study, textural changes of sludge extrudates submitted to convective drying are followed by a 3D image analysis of reconstructed X-ray microtomograms.

Nitrogen adsorption on silica xerogels or the odd look of a t plot.

Nitrogen adsorption in some silica xerogels leads to t plots that cannot be interpreted by the occurrence of capillary condensation or by the filling of micropores. Their particular appearance stems from the unique columnar structure of these samples at the nanometer scale, by which the adsorbent surface has a positive curvature. A standard thermodynamic approach allows the phenomenon to be exploited to characterize the samples.

Elaboration of new formulations to remove micropollutants in MSWI flue gas.

This study consists in identifying and testing potential inorganic substitutes to carbon based materials commonly used as adsorbents for the removal of organic pollutants such as dioxins and furans released from Municipal Solid Waste Incinerators (MSWI). Although carbon materials enable to reach the current regulation in terms of dioxins and furans emissions, they exhibit a potential auto ignition risk when present in hot flue gases. Here, the adsorption potential of carbon based products is compared to the one of some inorganic materials.

Alignment of glial cells stimulates directional neurite growth of CNS neurons in vitro.

Olfactory ensheathing cells (OECs) together with olfactory nerve fibroblasts (ONFs) and neonatal astrocytes are potent stimulators of neurite growth in adulthood and during development, respectively. Since it is known that alignment of glial cells is important for the correct outgrowth of axon tracts, it was hypothesized that the alignment of glial cells stimulates directional and enhanced neurite outgrowth. Adult OEC/ONF and neonatal astrocytes were cultured either on biodegradable poly(d,l)-lactide matrices or in Petri dishes for 4 days.

Image analysis of X-ray microtomograms of soft materials during convective drying.

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.

Preparation of macroporous biodegradable poly(L-lactide-co-epsilon-caprolactone) foams and characterization by mercury intrusion porosimetry, image analysis, and impedance spectroscopy.

Two poly(L-lactide-co-epsilon-caprolactone) random copolymers containing 5 and 40 mol % of epsilon-CL, namely P(LA-co-CL(5)) and P(LA-co-CL(40)), 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 >or=100 microm, and (2).

Image analysis of the axonal ingrowth into poly(D,L-lactide) porous scaffolds in relation to the 3-D porous structure.

Porous polymer scaffolds are promising materials for neural tissue engineering because they offer valuable three-dimensional (3-D) 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.

Fractal Characterization of Wide Pore Range Catalysts: Application to Pd-Ag/SiO(2) Xerogels.

Fractal analysis has been applied to characterize the structure of Pd-Ag/SiO(2) catalysts dried under vacuum (150 degrees C and 12 hPa) with different concentrations of Pd-Ag. Nitrogen adsorption-desorption, mercury porosimetry, and small-angle X-ray scattering measurements have been used. The different approaches to fractal analysis and their conditions of applicability are briefly described.

Sequentially Compressive and Intrusive Mechanisms in Mercury Porosimetry of Carbon Blacks.

The mechanism of mercury penetration in two different commercial carbon blacks is studied. We show that the volume variation measured by mercury porosimetry in these systems is due to three successive mechanisms, which occur as the pressure increases: (1) mercury invasion of voids between macroscopic grains, (2) compaction and elastic compression of macroscopic grains, (3) intrusion in the voids of aggregates formed by primary particles. The cumulative surface calculated by the Rootare-Prenzlow equation (S(RP)) in the intrusion part and the BET surface area measured by nitrogen adsorption (S(BET)) are compared.

A gas chromatographic separation for the h and C stable isotope ratio determination of coal compounds.

A new, completely automated gas chromatography technique has been developed to separate the different gaseous compounds produced during underground coal gasification for their (13)C/(12)C and D/H isotope ratio measurements. The technique was designed for separation and collection of H(2), CO, CO(2), H(2)O, H(2)S, CH(4), and heavier hydrocarbons. These gaseous compounds are perfectly separated by the gas-phase chromatograph and quantitatively sent to seven combustion and collection lines.