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See detailAbout the Acidity-Catalytic Activity Relationship in Ionic Liquids: Application to the Selective Isobutene Dimerization
Magna, Lionel; Bildé, Jean; Olivier-Bourbigou, Hélène et al

in Oil & Gas Science and Technology (2009), 64(6), 669

The Brønsted acidity level was evaluated for ionic liquids to which a strong acid has been added. As a first approach, the evaluation method was based on the determination of the Hammett acidity functions ... [more ▼]

The Brønsted acidity level was evaluated for ionic liquids to which a strong acid has been added. As a first approach, the evaluation method was based on the determination of the Hammett acidity functions H0, using UV-Visible spectroscopy. The acidity of protons is mainly determined by their solvation state and consequently, the properties of protons depend on both the nature of the solvent and the nature and concentration of the acid. An apparent acidity scale was defined following this principle. It was found that, for the investigated ionic liquids, the cation does not play a dominant role on the acidity level ([BMIm] ~ [BHIm] ~ [HNEt3]), whereas changing the nature of the anion of the ionic liquid may lead to very different acidities ([SbF6] > [PF6] > [BF4] > [NTf2] > [OTf]). This “acidity scale” was tentatively compared with an “activity scale” obtained for the dimerization of isobutene into isooctenes. The tendencies concerning the cation effect were confirmed ([BMIm] ~ [BuMePyrr] ~ [HNEt3]). The anion effect in only partially validated with a different behaviour for NTf2 type ionic liquids ([NTf2] ~ [SbF6] > [PF6] ~ [BF4] > [OTf]). By an adequate choice of the ionic liquid, selectivity for isobutene dimers can reach 88 wt% (at 70% isobutene conversion) with possible recycling of the catalytic system without loss of activity and selectivity. [less ▲]

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See detailA Comparison of the Acidity Levels in Room-Temperature Ionic Liquids
Robert, Thierry ULg; Magna, Lionel; Olivier-Bourbigou, Hélène et al

in Journal of the Electrochemical Society (2009), 156(9), 115

The Broensted acidity level was evaluated for several ionic liqs. ([BMIm][BF4], [BMIm][PF6], [BMIm][SbF6], [BMIm][OTf], [BMIm][NTf2], [HNET3][NTf2], and [HBIm][NTf2]) to which a strong acid, such as HNTf2 ... [more ▼]

The Broensted acidity level was evaluated for several ionic liqs. ([BMIm][BF4], [BMIm][PF6], [BMIm][SbF6], [BMIm][OTf], [BMIm][NTf2], [HNET3][NTf2], and [HBIm][NTf2]) to which a strong acid, such as HNTf2 [NTf2=N(CF3SO2)2] and HOTf (OTf=CF3SO3), has been added. The main purpose is to tentatively measure the influence on the resulting acidity of (i) the solvent anion or cation structure and (ii) the added acid nature. The evaluation method is based on the detn. of the Hammett acidity functions H0 using UV/visible spectroscopy. The acidity of protons is mainly detd. by their solvation state, and consequently, the properties of protons depend on both the nature of the solvent and the nature and concn. of the acid. In practice, for the investigated ionic liqs., the cation as well as the added acid nature does not play a dominant role, whereas changing the anion nature may lead to very different acidities. Indeed, for a similar content of added acid, the measured acidity levels are in the order PF6- > BF4- > NTf2- > OTf-. The problems of the influence of impurities on the final acidity and of the dissocg. character of the ionic liq. are addressed. [less ▲]

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See detailIn search of blood – detection of minute particles using spectroscopic methods
Lepot, Laurent ULg; Gilbert, Bernard ULg; De Wael, Kris et al

in Forensic Science International (2008), 180(1), 37-42

An examination protocol for rapid detection of remnants of blood particles on garments of suspects in bloody murder cases is described. Micro particles of blood are sampled along with fibres and hairs ... [more ▼]

An examination protocol for rapid detection of remnants of blood particles on garments of suspects in bloody murder cases is described. Micro particles of blood are sampled along with fibres and hairs using the tape lifting method. The tapings are searched with a low power microscope for red particles with morphology similar to blood. Presumed blood traces are further examined using microspectrophotometry on the cut out piece of taping. The typical visible spectrum of haemoglobin is characteristic for blood. Alternatively Raman spectroscopy can be used to measure the characteristic vibrational spectrum of haemoglobin. At a later stage, these particles may be removed from the piece of taping in order to extract the blood and attempt to obtain a genetic profile. [less ▲]

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See detailApplication of Raman spectroscopy to forensic fibre cases
Lepot, Laurent ULg; Gilbert, Bernard ULg; De Wael, Kris et al

in Science & Justice : Journal of the Forensic Science Society (2008), 48(3), 109-117

Five forensic fibre cases in which Raman spectroscopy proved to be a good confirmatory method for microspectrophotometry (MSP) are described. Absorption spectra in the visible range are indeed sometimes ... [more ▼]

Five forensic fibre cases in which Raman spectroscopy proved to be a good confirmatory method for microspectrophotometry (MSP) are described. Absorption spectra in the visible range are indeed sometimes characteristic of a certain dye but this one can be subsequently identified unambiguously by Raman spectroscopy using a spectral library. In other cases the comparison of Raman spectra of reference fibres and suspect fibres led to an improvement of the discrimination power. The Raman measurements have been performed directly on mounted fibres and the spectra showed only little interference from the mounting resin and glass. Raman spectroscopy is therefore a powerful method that can be applied in routine fibre analysis following optical microscopy and MSP measurements. [less ▲]

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See detailA propos des peintures romanes de la cathédrale de Tournai
Lepot, Laurent ULg; Gilbert, Bernard ULg; Denoël, Sophie

in Denoël, Sophie (Ed.) Les peintures murales, Les techniques : Actes du colloque (2008)

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See detailMaya blue-green pigments found in Calakmul, Mexico: a study by Raman and UV-visible spectroscopy
Moreno, Renata Garcia; Strivay, David ULg; Gilbert, Bernard ULg

in Journal Of Raman Spectroscopy (2008), 39(8), 1050-1056

After more than two decades of fieldwork in the Maya archaeological site of Calakmul, Mexico, numerous remnants of blue and green pigments have been reported on wall paintings, as well as on funerary ... [more ▼]

After more than two decades of fieldwork in the Maya archaeological site of Calakmul, Mexico, numerous remnants of blue and green pigments have been reported on wall paintings, as well as on funerary paraphernalia, such as masks, miniatures and vases. The importance of these pigments is linked to the sacred values that Maya people associate with blue and green colours since pre-Columbian times. These hues symbolise water, and are therefore associated with fertility and regeneration. This paper aims to perform a survey of the blue and green pigments used in the Early Classic and Late Classic periods in Calakmul (300-850 A.D.), in order to have a better understanding of their chemical composition and origin. Analyses were performed on microsamples using Raman and UV-visible spectroscopies to evaluate the possibilities that these techniques can offer in future in situ researches on Mesoamerican archaeological materials and objects. With these analyses, we have documented a large blue-green chromatic palette, which includes the earliest Blue Maya and Green Maya known to date, as well as malachite, pseudomalachite and an unknown-up-to-now blue-green mineral pigment, veszelyite, used specifically for ritual objects. The results indicate a careful selection of imported products and the mastering of a complex ancient Maya pictorial tradition. Copyright (c) 2008 John Wiley & Sons, Ltd. [less ▲]

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See detailControlled RAFT synthesis of polyacrylonitrile-b-poly(acrylic acid) diblocks as precursors of carbon nanocapsules with assistance of gold nanoparticles
Aqil, Abdelhafid ULg; Detrembleur, Christophe ULg; Gilbert, Bernard ULg et al

in Chemistry of Materials (2007), 19(9), 2150-2154

A new strategy for the synthesis of carbon nanocapsules has been developed, based on the preparation of well-defined polyacrylonitrile-b-poly(acrylic acid) (PAN-b-PAA) block copolymers followed by their ... [more ▼]

A new strategy for the synthesis of carbon nanocapsules has been developed, based on the preparation of well-defined polyacrylonitrile-b-poly(acrylic acid) (PAN-b-PAA) block copolymers followed by their micellization in basic water to form spherical micelles with a PAN core and PAA shell. The PAN is then cross-linked by the use of gold nanoparticles. After pyrolysis, carbon nanocapsules are produced by graphitization of the PAN core and diffusion of the molten gold nanoparticles out of the nano-objects. [less ▲]

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See detailAbout the Acidity Level in Room Temperature Ionic Liquids
Robert, Thierry ULg; Olivier-Bourbigou, Hélène; Magna, Lionel et al

in ECS Transactions (2007), 3(35), 71

The Brønsted acidity level was evaluated for ionic liquids to which a strong acid has been added. The evaluation method is based on the determination of the Hammett acidity functions H0, using UV-Visible ... [more ▼]

The Brønsted acidity level was evaluated for ionic liquids to which a strong acid has been added. The evaluation method is based on the determination of the Hammett acidity functions H0, using UV-Visible spectroscopy. The acidity of protons is mainly determined by their solvation state and consequently, the properties of protons depend on both the nature of the solvent and the nature and concentration of the acid. In practice, it was found that, for the investigated ionic liquids, the cation as well as the added acid nature does not play a dominant role, whereas changing the anion nature may lead to very different acidities. Indeed, for a similar content of added acid, the measured acidity levels are in the order: PF6- > BF4- > NTf2- > OTf-. The problems of the influence of impurities on the final acidity and of the weakly dissociating character of the ionic liquid are addressed. [less ▲]

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See detailStructural and electrical properties of tellurovanadate glasses containing Li2O
Krins, Natasha ULg; Rulmont, André ULg; Grandjean, Jean ULg et al

in Solid State Ionics (2006), 177(35-36 Sp. Iss. SI), 3147-3150

Glassy materials are promising intercalation compounds, due to their open network structure and absence of grain boundaries. Some glasses containing alkali ions and a high concentration of transition ... [more ▼]

Glassy materials are promising intercalation compounds, due to their open network structure and absence of grain boundaries. Some glasses containing alkali ions and a high concentration of transition metal ions can present mixed ionic-electronic conductivity and are therefore potential candidates for application as cathode material in Li-ion batteries. The present work is devoted to the ternary system xLi(2)O-(1-x)[0.3V(2)O(5)-0.7TeO(2)] with 0 <= x <= 0.4. These compounds were prepared by heat treatment in air at 800 degrees C followed by traditional quenching. Raman spectroscopy and V-51 nuclear magnetic resonance measurements were performed in order to highlight the structural short range order modifications induced by the introduction of the Li2O network modifier. These structural effects can be related to the electrical behaviour, as studied by complex impedance spectroscopy measurements. (c) 2006 Elsevier B.V. All rights reserved. [less ▲]

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See detailCombination of electrografting and atom-transfer radical polymerization for making the stainless steel surface antibacterial and protein antiadhesive
Ignatova, Miléna; Voccia, Samuel; Gilbert, Bernard ULg et al

in Langmuir (2006), 22(1), 255-262

A two-step "grafting from" method has been successfully carried out, which is based on the electrografting of polyacrylate chains containing an initiator for the atom transfer radical polymerization (ATRP ... [more ▼]

A two-step "grafting from" method has been successfully carried out, which is based on the electrografting of polyacrylate chains containing an initiator for the atom transfer radical polymerization (ATRP) of 2-(tert-butylamino)ethyl methacrylate (TBAEMA) or copolymerization of TBAEMA with either monomethyl ether of poly(ethylene oxide) methacrylate (PEOMA) or acrylic acid (AA) or styrene. The chemisorption of this type of polymer brushes onto stainless steel surfaces has potential in orthopaedic surgery. These films have been characterized by ATR-FTIR, Raman spectroscopy, atomic force microscopy (AFM), and measurement of contact angles of water. The polymer formed in solution by ATRP and that one detached on purpose from the surface have been analyzed by size exclusion chromathography (SEC) and H-1 NMR spectroscopy. The strong adherence of the films onto stainless steel has been assessed by peeling tests. AFM analysis has shown that addition of hydrophilic comonomers to the grafted chains decreases the surface roughness. According to dynamic quartz crystal microbalance experiments, proteins (e.g., fibrinogen) are more effectively repelled whenever copolymer brushes contain neutral hydrophilic (PEOMA) co-units rather than negatively charged groups (PAA salt). Moreover, a 2- to 3-fold decrease in the fibrinogen adsorption is observed when TBAEMA is copolymerized with either PEOMA or AA rather than homopolymerized or copolymerized with styrene. Compared to the bare stainless steel surface, brushes of polyTBAEMA, poly (TBAEMA-co-PEOMA) and poly(TBAEMA-co-AA) decrease the bacteria adhesion by 3 to 4 orders of magnitude as revealed by Gram-positive bacteria S. aureus adhesion tests. [less ▲]

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See detailThe technique of the mural paintings of the Tournai Cathedral
Lepot, Laurent ULg; Gilbert, Bernard ULg; Denoël, Sophie

in Journal of Raman Spectroscopy (2006), 37(10), 1098-1103

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See detailElectrografting of Poly(ethylene glycol) Acrylate : A One-Step Strategy for the Synthesis of Protein-Repellent Surfaces
Gabriel, Sabine ULg; Dubruel, Peter; Schacht, Etienne et al

in Angewandte Chemie (International ed. in English) (2005), 44(34), 5505-5509

Electrografting of acrylate end-capped poly(ethylene glycol) (PEG) is an important technique for the one-step coating of electroconductive substrates by an adherent hydrophilic coating (see figure). This ... [more ▼]

Electrografting of acrylate end-capped poly(ethylene glycol) (PEG) is an important technique for the one-step coating of electroconductive substrates by an adherent hydrophilic coating (see figure). This technique is very efficient for the production of new protein-repellent surfaces. [less ▲]

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See detailCombination of electrografting with controlled polymerization: building of anti-bacterial surfaces
Voccia, Samuel; Ignatova, Miléna; Gilbert, Bernard ULg et al

Conference (2005, June 01)

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See detailSemi-crystalline polymer thin films: preparation, processing and peculiar features
Voccia, Samuel; Gilbert, Bernard ULg; Jérôme, Robert ULg et al

Poster (2005, June 01)

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See detailSemi-crystalline polymer thin films: processing and peculiar features
Voccia, Samuel; Gilbert, Bernard ULg; Celle, C. et al

Poster (2005, May 19)

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See detailTechnique of mural paintings from the Tournai Cathedral
Lepot, Laurent ULg; Denoël, Sophie; Gilbert, Bernard ULg

Poster (2005)

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See detailSynthesis of copolymer brushes endowed with adhesion to stainless steel surfaces and antibacterial properties by controlled nitroxide-mediated radical polymerization
Ignatova, Miléna; Voccia, Samuel; Gilbert, Bernard ULg et al

in Langmuir (2004), 20(24), 10718-10726

Novel copolymer brushes have been synthesized by a two-step "grafting from" method that consists of the electrografting of poly(2-phenyl-2-(2,2,6,6-tetramethyl-piperidin-1-yloxy)-ethylacrylate) onto ... [more ▼]

Novel copolymer brushes have been synthesized by a two-step "grafting from" method that consists of the electrografting of poly(2-phenyl-2-(2,2,6,6-tetramethyl-piperidin-1-yloxy)-ethylacrylate) onto stainless steel, followed by the nitroxide-mediated radical polymerization of 2-(dimethylamino ethyl)acrylate and styrene or n-butyl acrylate, initiated from the electrografted polyacrylate chains. The grafted copolymers were quaternized in order to endow them with antibacterial properties. Peeling tests have confirmed the strong adhesion of the grafted copolymer onto the stainless steel substrate. Quartz crystal microbalance experiments have proven that fibrinogen adhesion is lower on the hydrophilic quaternized films compared to the nonionic counterpart. Such quaternized copolymers exhibit significant antibacterial activity against the Gram-positive bacteria S. aureus and the Gram-negative bacteria E. coli. [less ▲]

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See detailPreparation of poly(epsilon-caprolactone) brushes at the surface of conducting substrates
Voccia, Samuel; Bech, Loïc; Gilbert, Bernard ULg et al

in Langmuir (2004), 20(24), 10670-10678

This paper reports on the preparation of polyester brushes at the surface of electrically conducting materials. A two-step strategy has been worked out that consists of the electropolymerization of an ... [more ▼]

This paper reports on the preparation of polyester brushes at the surface of electrically conducting materials. A two-step strategy has been worked out that consists of the electropolymerization of an acrylate under a cathodic potential, such that the polyacrylate layer is chemisorbed at the surface. In a second step, either preformed poly(epsilon-caprolactone) chains are grafted onto the polyacrylate sublayer or the ring-opening polymerization of epsilon-caprolactone is initiated from it. [less ▲]

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See detailPLA-coated gold nanoparticles for the labeling of PLA biocarriers
Qiu, Hongjin; Rieger, Jutta ULg; Gilbert, Bernard ULg et al

in Chemistry of Materials (2004), 16(5), 850-856

POly-DL-lactide end-capped by a protected thiol was synthesized by bulk ring-opening polymerization (ROP) of DL-lactide initiated by the reaction product of aluminum isopropoxide [Al (iOPr) (3)] with ... [more ▼]

POly-DL-lactide end-capped by a protected thiol was synthesized by bulk ring-opening polymerization (ROP) of DL-lactide initiated by the reaction product of aluminum isopropoxide [Al (iOPr) (3)] with alpha- (2,4-dinitrophenylsulfenyl) ethanol. After the thiol deprotection, PLA-SH was used to stabilize gold nanoparticles. Either these nanoparticles were prepared in the presence of PLA-SH, or PLA-SH was substituted for part of the undecanethiol (C11SH) that stabilized preformed gold nanoparticles. In contrast to C11SH-coated nanoparticles, those stabilized by PLA-SH were successfully entrapped into 100-nm PLA nanocarriers prepared by nanoprecipitation. This is an easy technique to label PLA biocarriers and therefore trace their fate in vivo. [less ▲]

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