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See detailDetermination of the relationship between foam morphology and electrical conductivity of polymer/carbon nanotube nanocomposite foams
Tran, Minh Phuong ULg

Doctoral thesis (2014)

The lightweight of porous nanocomposites makes them attractive materials for various applications such as thermal and sound barriers, shock absorbers, insulation, packaging, and their porous structure is ... [more ▼]

The lightweight of porous nanocomposites makes them attractive materials for various applications such as thermal and sound barriers, shock absorbers, insulation, packaging, and their porous structure is very interesting in bone tissue engineering. Moreover, the incorporation of appropriate carbonaceous nanoparticles into polymeric foams contributes to the reinforcement of their mechanical performances but also renders them electrically conductive, consequently extending their potential interest in electromagnetic shielding (EMI) and electrostatic discharge (ESD) applications for instance. In this PhD thesis, we aim at designing various polymeric foams containing a conductive nanofiller (carbon nanotubes) and to identify the main morphological parameters (pore size, cell density, cell wall thickness,…) that affect and govern the final properties of the foams. In this work, the electrical conductivity of the foams is the main property investigated because it is governing their performances as materials for EMI absorbers, the main application targeted in this work. These important morphology/electrical conductivity relationships would indeed be very useful to guide the foam development towards the material with the best performances for the targeted applications. Two different foaming methods are used in this work: (i) the supercritical CO2 (scCO2) foaming technology and (ii) the freeze-drying process. The first technique enables to produce isotropic foams with spherical closed cells structures and the second one, oriented anisotropic foams with cylindrical open cells. The variation of the foaming parameters allows preparing foams with a large panel of morphologies required for the establishment of the structure/properties relationships. In parallel to this main objective, an improvement of the overall conductive performances of the nanocomposites foams is also investigated through the optimization of the foam morphology and the content in conductive nanofillers. [less ▲]

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See detailDetermination of the respective contributions of energy-dissipating athways to mitochondrial respiration : The ADP/O method
Sluse, Francis ULg; Jarmuszkiewicz, W.; Almeida, A. et al

in Moller, I. M.; Gardestrom, P.; Glimelius, K. (Eds.) et al Plant mitochondria : from gene to function (1998)

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See detailDetermination of the respective contributions of the cytochrome and alternative oxidase pathway in Acanthamoeba catellanii
Jarmuszkiewicz, W.; Sluse-Goffart, C.; Hryniewiecka, L. et al

in Westerhoff, H.; Snoep, J.; Sluse, Francis (Eds.) et al Biothermokinetics of the living cell (1996)

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See detailDetermination of the response factors of several desulfoglucosinolates used for quantitative analysis of Brassicaceae
Wathelet, Jean-Paul ULg; Iori, R.; Mabon, N. et al

Poster (2001)

Quantitative determination of total and individual glucosinolate contents in Brassica samples (rapeseed/canola, broccoli, cabbage, mustard…) is generally realised according to the reference method ISO ... [more ▼]

Quantitative determination of total and individual glucosinolate contents in Brassica samples (rapeseed/canola, broccoli, cabbage, mustard…) is generally realised according to the reference method ISO 9167-1. After extraction, glucosinolates are purified, then desulfated by Helix pomatia sulfatase. The desulfo-glucosinolates (DSGSL) formed are then separated by reverse phase chromatography associated with UV detection (229 nm). As each compound can possess a very different molar extinction coefficient, it is important - on a quantitative point of view - to define accurately relative response factors. The response factors actually used in the official method have been determined experimentally through indirect methods and have been fixed, some years ago, by consensus between the various laboratories who took part in a ring test. They may need to be revised and calculated for a broader panel of glucosinolates. [less ▲]

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See detailDetermination of the ruminant origin of bone particles using fluorescence in situ hybridization (FISH).
Lecrenier, Marie-Caroline ULg; Ledoux, Quentin; Berben, Gilbert et al

in Scientific reports (2014), 4

Molecular biology techniques such as PCR constitute powerful tools for the determination of the taxonomic origin of bones. DNA degradation and contamination by exogenous DNA, however, jeopardise bone ... [more ▼]

Molecular biology techniques such as PCR constitute powerful tools for the determination of the taxonomic origin of bones. DNA degradation and contamination by exogenous DNA, however, jeopardise bone identification. Despite the vast array of techniques used to decontaminate bone fragments, the isolation and determination of bone DNA content are still problematic. Within the framework of the eradication of transmissible spongiform encephalopathies (including BSE, commonly known as "mad cow disease"), a fluorescence in situ hybridization (FISH) protocol was developed. Results from the described study showed that this method can be applied directly to bones without a demineralisation step and that it allows the identification of bovine and ruminant bones even after severe processing. The results also showed that the method is independent of exogenous contamination and that it is therefore entirely appropriate for this application. [less ▲]

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See detailDetermination of the scattering coefficient of random rough diffusing surfaces for room acoustics applications
Embrechts, Jean-Jacques ULg; Archambeau, Dominique; Stan, Guy-Bart

in Acta Acustica United with Acustica (2001), 87

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See detailDetermination of the selenium isotopic compositions in Se-rich yeast by hydride generation-inductively coupled plasma multicollector mass spectrometry
Far, Johann ULg; Berail, S.; Preud'homme, H. et al

in Journal of Analytical Atomic Spectrometry [=JAAS] (2010), 25(11), 1695-1703

A method was developed for the precise determination of selenium isotopic compositions (delta Se-82/77, delta Se-82/76 and delta Se-82/74) by hydride generation inductively coupled plasma multiple ... [more ▼]

A method was developed for the precise determination of selenium isotopic compositions (delta Se-82/77, delta Se-82/76 and delta Se-82/74) by hydride generation inductively coupled plasma multiple collector mass spectrometry (HG-MC ICP MS) in Se-rich yeast. The conversion of all the selenium forms into Se(IV) during digestion and reduction steps was investigated by anion-exchange ICP quadrupole MS (SAX ICP Q MS) and was found to be complete. Measurement precision values expressed as deltas (delta) with regard to NIST SR M3149 were between 0.2-0.4 parts per thousand (2SD) over a period of 6 months for 25 or 50 ng mL(-1) of introduced selenium. The application of the method to the analysis of nine Se-rich yeast supplements from different manufactures showed significant variations in the isotope ratios suggesting that the latter can be an attractive parameter for the yeast provenance discrimination. [less ▲]

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See detailDetermination of the singlet oxygen quantum yield of bacteriochlorin a: a comparative study in phosphate buffer and aqueous dispersion of dimiristoyl-L-a-phosphatidylcholine liposomes
Hoebeke, Maryse ULg; Damoiseau, Xavier

in Photochemical & Photobiological Sciences (2002), 1(4), 283-287

The production of singlet oxygen (1O2) by bacteriochlorin a (BCA) was studied in phosphate buffer and in dimyristoyl-L-α-phosphatidylcholine (DMPC) unilamellar liposomes. The comparative method used to ... [more ▼]

The production of singlet oxygen (1O2) by bacteriochlorin a (BCA) was studied in phosphate buffer and in dimyristoyl-L-α-phosphatidylcholine (DMPC) unilamellar liposomes. The comparative method used to measure 1O2 production was a quantitative analysis of photooxidation reactions leading to the loss of absorbance of the water-soluble specific probe: anthracene 9,10-dipropionic acid. Rose Bengal, whose 1O2 quantum yield (ΦRB) is well known in alcohols and phosphate buffer, was used as the standard for the quantification of the BCA singlet oxygen production. Our results confirm quantitatively that solubilization of BCA in liposomes leads to an increase in 1O2 production. Indeed, the quantum yield of 1O2 production by BCA (ΦBCA) is 0.05 in phosphate buffer and 0.33 in DMPC liposomes. Furthermore, the diffusion characteristics of 1O2 produced by BCA bound to liposome were also examined using the isotopic lifetime enhancement effect of D2O. It was shown that 1O2 spent at least 70% of its lifetime in the vesicular environment [less ▲]

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See detailDetermination of the Spin Axis Orientation of Asteroids: Inversion of Photometric Lightcurves
Hainaut, O.; Detal, Alain ULg; Ibrahim-Denis, A. et al

in Lindblad, B. A.; Lagerkvist, C. I.; Rickman, H. (Eds.) Proceedings of a meeting (AMC 89) Asteroids, Comets, Meteors III (1990)

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See detailDetermination of the Spin Vector of a Synthetic Asteroid
Karttunen, H.; Cellino, A.; Detal, Alain ULg et al

in Lindblad; Lagerkvist; Rickman (Eds.) Proceedings of a meeting (AMC 89) Asteroids, Comets, Meteors III (1990)

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See detailDetermination of the stability constants of uranyl/polymer complexes by differential pulse polarography
Leroy, D.; Martinot, Lucien; Jérôme, Christine ULg et al

in Polymer (2001), 42(10), 4589-4596

Differential pulse polarography (DPP) allows for the determination of the stability constants (K) and the stoichiometry (n) for the complexation of the UO22+ ion by various monomers and the parent ... [more ▼]

Differential pulse polarography (DPP) allows for the determination of the stability constants (K) and the stoichiometry (n) for the complexation of the UO22+ ion by various monomers and the parent polymers. The experimental observation is the shift of the totally reversible reduction wave UO22++e- UO2+ toward more cathodic potentials when the complexing monomer or polymer is added to an uranyl nitrate aqueous solution. This shift is, however, much greater when the polymer is used rather than the monomer, in line with a higher stability of the complexes (Kpolymer>>Kmonomer). A theoretical stability scale of the polymers/UO22+ complexes was compared to an experimental one based on dynamic leaching tests. [less ▲]

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See detailDetermination Of The Taxonomic Position And Characterization Of Yam Mosaic Virus Isolates Based On Sequence Data Of The 5'-Terminal Part Of The Coat Protein Cistron
Duterme, Olivier; Colinet, Dominique; Kummert, Jean et al

in Archives of Virology (1996), 141(6), 1067-1075

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See detailDetermination Of The Topology Of The Hydrophobic Segment Of Mammalian Diacylglycerol Kinase Epsilon In A Cell Membrane And Its Relationship To Predictions From Modeling
Decaffmeyer, Marc ULg; Shulga, Yv.; Dicu, Ao. et al

in Journal of Molecular Biology (2008), 383(4), 797-809

The epsilon isoform of diacylglycerol kinase (DGKepsilon) is unique among mammalian DGKs in having a segment of hydrophobic amino acids comprising approximately residues 20 to 41. Several algorithms ... [more ▼]

The epsilon isoform of diacylglycerol kinase (DGKepsilon) is unique among mammalian DGKs in having a segment of hydrophobic amino acids comprising approximately residues 20 to 41. Several algorithms predict this segment to be a transmembrane (TM) helix. Using PepLook, we have performed an in silico analysis of the conformational preference of the segment in a hydrophobic environment comprising residues 18 to 42 of DGKepsilon. We find that there are two distinct groups of stable conformations, one corresponding to a straight helix that would traverse the membrane and the second corresponding to a bent helix that would enter and leave the same side of the membrane. Furthermore, the calculations predict that substituting the Pro32 residue in the hydrophobic segment with an Ala will cause the hydrophobic segment to favor a TM orientation. We have expressed the P32A mutant of DGKepsilon, with a FLAG tag (an N-terminal 3xFLAG epitope tag) at the amino terminus, in COS-7 cells. We find that this mutation causes a large reduction in both k(cat) and K(m) while maintaining k(cat)/K(m) constant. Specificity of the P32A mutant for substrates with polyunsaturated acyl chains is retained. The P32A mutant also has higher affinity for membranes since it is more difficult to extract from the membrane with high salt concentration or high pH compared with the wild-type DGKepsilon. We also evaluated the topology of the proteins with confocal immunofluorescence microscopy using NIH 3T3 cells. We find that the FLAG tag at the amino terminus of the wild-type enzyme is not reactive with antibodies unless the cell membrane is permeabilized with detergent. We also demonstrate that at least a fraction of the wild-type DGKepsilon is present in the plasma membrane and that comparable amounts of the wild-type and P32A mutant proteins are in the plasma membrane fraction. This indicates that in these cells the hydrophobic segment of the wild-type DGKepsilon is not TM but takes up a bent conformation. In contrast, the FLAG tag at the amino terminus of the P32A mutant is exposed to antibody both before and after membrane permeabilization. This modeling approach thus provides an explanation, not provided by simple predictive algorithms, for the observed topology of this protein in cell membranes. The work also demonstrates that the wild-type DGKepsilon is a monotopic protein. [less ▲]

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See detailDetermination of the tortuosity of porous materials from binary or grey-tone tomographic reconstructions
Gommes, Cédric ULg; Almazan, Maria del Carmen; Léonard, Angélique ULg et al

Conference (2008, November)

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See detailDetermination of the total glucosinolate content in rapeseed seeds by liquid chromatography: comparative study between the rapid isocratic and the reference gradient methods by a ring test
Quinsac, A.; Krouti, M.; Ribaillier, D. et al

in Ocl-Oleagineux Corps Gras Lipides (1998), 5(5), 398-406

Isocratic liquid chromatography (LC) on cyanopropyl bonded silica column is an alternative method to gradient IC on octadecyl bonded silica column involved in the standardized method for total ... [more ▼]

Isocratic liquid chromatography (LC) on cyanopropyl bonded silica column is an alternative method to gradient IC on octadecyl bonded silica column involved in the standardized method for total glucosinolotes (GSL) analysis in rapeseed seeds. Its advantages consist in more simple apparatus and eluent, and a shorter analysis duration. In the aim of a next standardization of isocratic LC, the performances of both methods ore compared on three rapeseed samples during a ring-test including six laboratories. Statistical treatment or the results according to ISO 5725 shows, with a risk level of 5%, the equivalency of both methods to determine total GSL content in rapeseed seeds. The elution mode appears to have no significant effect on results in opposite to the internal standard when its purity is not well-known. [less ▲]

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See detailDetermination of the Total Ionospheric Electron Content with GPS - Difficulties and their Solution
Wanninger, Lambert; Sardon, E.; Warnant, René ULg

in Kersley, Len (Ed.) Proceedings of Beacon Satellite Symposium '94 (1994)

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See detailDetermination of the true ileal digestibility of amino acids in pigs by means of 15N-labelled diets or animals.
Leterme, Pascal; Van Leeuwen, Piet; Thewis, André ULg et al

in Proceeding of the 6th International Symposium on Digestive Physiology in Pigs, n°80. (1994)

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See detailDetermination of the true ileal digestibility of amino acids in pigs by means of 15N-labelled diets or animals.
Leterme, Pascal; Thewis, André ULg; Van leeuwen, Piet et al

Conference (1993, August)

Detailed reference viewed: 9 (2 ULg)