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See detailChemical Experts & their roles in the Belgian Sugar Industry
Melard, François ULg

Conference (1998, November 25)

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See detailChemical fixation of CO2 with epoxides: towards the synthesis of cyclic carbonates, precursors of CO2-based polyurethanes
Gennen, Sandro ULg; Grignard, Bruno ULg; Gilbert, Bernard ULg et al

Poster (2014, May 20)

Due to concerns about global warming combined with the decrease of fossil resources, the chemical transformation of carbon dioxide into added-value products has gained interest in both academic and ... [more ▼]

Due to concerns about global warming combined with the decrease of fossil resources, the chemical transformation of carbon dioxide into added-value products has gained interest in both academic and industrial fields. To date, the chemical fixation of CO2 onto epoxides is one of the most promising ways to valorize carbon dioxide at an industrial scale . Indeed, cyclic carbonates are useful intermediates for polycarbonates and polyurethanes synthesis or can be used as electrolytes in lithium ion batteries. Although fixation of carbon dioxide onto epoxides has been extensively studied, the design of highly effective catalysts still remains a challenge. Here, we present a new highly efficient biocomponent organocatalyst based on the use of an ammonium salt (TBAI) in combination with single or double hydrogen bond donors activators (typically fluorinated alcohols). [less ▲]

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See detailChemical Force Microscopy Study of Adhesion Properties of Polyolefin Surfaces
Duwez, Anne-Sophie ULg; Legras, R.; Daoust, D. et al

Conference (2000, May 02)

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See detailChemical Force Microscopy Study of Adhesion Properties of Polyolefin Surfaces
Duwez, Anne-Sophie ULg; Legras, R.; Nysten, B.

Conference (2000, September 18)

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See detailChemical Hydrolysis of Fagus sylvatica Wood: Dilute Acid vs. Alkaline Treatment
Miazek, Krystian ULg; Goffin, Dorothée ULg; Richel, Aurore ULg

Poster (2014, March 05)

Lignocellulosic biomass, found in a large variety of plants such as coniferous trees (Softwood), broad leaved trees (Hardwood), grasses and agricultural or food residues, is the most abundant source of ... [more ▼]

Lignocellulosic biomass, found in a large variety of plants such as coniferous trees (Softwood), broad leaved trees (Hardwood), grasses and agricultural or food residues, is the most abundant source of molecules required for production of biofuels and high value - added products. Lignocellulose is composed of three polymers: cellulose, hemicellulose and lignin. Cellulose is a non-branched polymer consisting of glucoses (hexoses). Hemicellulose is a complex carbohydrate containing pentoses (mainly xyloses in the case of Hardwood, grasses and agricultural wastes) or hexoses (usually mannoses in the case of Softwood) as the main sugars. Lignin is a biopolymer with aromatic alcohols as basic monomeric units. Cellulose chains are arranged in bundles and interlinked with hemicellulose. Lignin is cross-linked with hemicellulose and occupies space between cellulose bundles. Due to complex polymeric structure, lignocellulosic materials are resistant to hydrolysis. A number of treatment methods (mechanical, chemical, biochemical) is implemented to successfully hydrolyse lignocellulose. Amongst chemical methods harnessed to break lignocellulose structure, dilute acid and alkaline treatments are commonly mentioned, as the most efficient ones. The objective of this study was to evaluate the effect of dilute acid and alkaline treatment on hydrolysis rate of polymeric components in Fagus sylvatica wood. Fagus sylvatica also known as common beech is a broad leaved, deciduous tree that belongs to the family of Fagaceae, widely spread in Europe. Beech wood was determined to contain 48 % glucose, 18 % xylose and 20 % Klason lignin in its dry material. Results of this study showed that 1 h hydrolysis at 100 °C with the use of 3 % H2SO4 resulted in 71 % removal of xylose and 4 % removal of glucose with Klason lignin remained intact. Additionally, the presence of sugar degradation products: 2 - furfural and hydroxymethylfurfural was detected in dilute acid hydrolysate. Release of 2 - furfural and hydroxymethylfurfural from beech wood was determined as 0.03 % and 0.1 %, respectively. On the other hand, 1 h hydrolysis at 100 °C with the use of 7 % NaOH caused 59 % xylose removal and 11 % removal of Klason lignin with no effect on glucose. Dilute acid hydrolysis proved to be more efficient in removing xylose, but alkaline hydrolysis additionally showed to remove Klason lignin. [less ▲]

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See detailChemical imaging of small molecules from simple to complex matrices: Quantitative approaches based on Surface Enhanced Raman scattering
De Bleye, Charlotte ULg; Sacre, Pierre-Yves ULg; Chavez, Pierre-François ULg et al

Conference (2013, July)

Surface Enhanced Raman scattering (SERS) allows to dramatically exalt the Raman diffusion of molecules absorbed or very closed to rough metallic surfaces while keeping their structural information. SERS ... [more ▼]

Surface Enhanced Raman scattering (SERS) allows to dramatically exalt the Raman diffusion of molecules absorbed or very closed to rough metallic surfaces while keeping their structural information. SERS chemical imaging, presenting a high specificity and sensibility, allows acquiring a visual representation of samples combining spectral and spatial measurements. This technique could become a powerful tool in pharmaceutical and biological analysis enabling to identify and quantify molecules thanks to chemometric evaluation while looking at their distribution or their interactions. In this context, SERS chemical imaging is investigated in detection or quantitative determination of molecules in pharmaceutical and biological matrices. The feasibility of making quantitative measurements using SERS is evaluated on small target molecules models such as 4-aminophenol and lactate. Firstly, a SERS method to quantify 4-aminophenol which is the primary impurity of acetaminophen coming from its degradation during the storage or from its synthesis was developed on a real pharmaceutical formulation. The standard addition method was selected as calibration method in order to take into account the matrix effect coming from the different components of the latter. Despite the well-known stability and repeatability problems of SERS, the method was thoroughly validated by means of accuracy profiles as decision tool. Moreover, this validation methodology allowed to define a first estimation of the real analytical performance of the technique. Secondly, the detection of lactate, which is a critical metabolite implicated in several metabolic disorders, was successfully tested in the physiological concentration in a simple matrix. Preliminary results for the determination of this metabolic biomarker were also very promising allowing to consider more complex matrices. Based on these results, SERS chemical imaging was implemented to detect 4-aminophenol in a pharmaceutical tablet formerly pulverised by a SERS substrate. Through this imaging technique, it was not only possible to detect the presence of the impurity at the limit of specification of 0.1% (w/w) but it was also possible to differentiate tablets comprising different concentrations of the latter. These promising results represent the first step towards quantitative measurements using SERS chemical imaging. [less ▲]

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See detailChemical Imaging on Liver Steatosis Using Synchrotron Infrared and ToF-SIMS Microspectroscopies
Le Naour, François; Bralet, Marie-Pierre; Debois, Delphine ULg et al

in PLoS ONE (2009), 4(10), 7408

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See detailChemical inhibitors of cyclin-dependent kinases control proliferation, apoptosis and differentiation of oligodendroglial cells
Nguyen, Laurent ULg; Malgrange, Brigitte ULg; Rocher, Véronique et al

in International Journal of Developmental Neuroscience (2003), 21(6), 321-326

Since cyclin-dependent kinases (Cdks) and their endogenous inhibitors (Cdkis) play an essential role as regulators of cell cycle withdrawal and onset of differentiation within oligodendroglial cells, we ... [more ▼]

Since cyclin-dependent kinases (Cdks) and their endogenous inhibitors (Cdkis) play an essential role as regulators of cell cycle withdrawal and onset of differentiation within oligodendroglial cells, we assessed here the effects of exogenous chemical Cdk inhibitors (CKIs) on cultured rat cortical oligodendrocyte progenitor cells (OPCs). We showed that purine derivatives and especially roscovitine strongly inhibited OPCs proliferation. In the presence of mitogenic signals, roscovitine synergized with thyroid hormone to stimulate oligodendrocyte differentiation. Roscovitine also prevented oligodendroglial apoptosis induced by growth factor deprivation. We thus demonstrated that small molecular weight chemical CKIs have important effects on crucial events of oligodendroglial development in vitro. This might open prospects for using these apparently well tolerated agents in remyelination strategies. (C) 2003 ISDN. Published by Elsevier Ltd. All rights reserved. [less ▲]

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See detailChemical inhibitors: the challenge of finding the right target.
Calligaris, David ULg; Lafitte, Daniel

in Chemistry & Biology (2011), 18(5), 555-557

A paper in this issue of Chemistry & Biology shows that the diaryl oxazole compound UA62784 that targets pancreatic cancer cells interacts with tubulin near the colchicine binding site (Tcherniuk et al ... [more ▼]

A paper in this issue of Chemistry & Biology shows that the diaryl oxazole compound UA62784 that targets pancreatic cancer cells interacts with tubulin near the colchicine binding site (Tcherniuk et al., 2011). These findings differ from previous observations, highlighting the challenges of identifying the biological target for chemical inhibitors. [less ▲]

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See detailChemical interactions between Bi2Sr3CaO7(Bi-2310) and Bi2Sr2Ca0.8Dy0.2Cu2O8 (Bi-2212(Dy))
Rahier, Sébastien ULg; Lafort, Adeline ULg; Henrist, Catherine ULg et al

in Superconductor Science & Technology (2006), 19(1), 39-43

The chemical interactions between Bi2Sr3CaO7 (Bi-2310) and Bi2Sr2Ca0.8Dy0.2Cu2O8 (Bi-2212(Dy)) at 965 degrees C were investigated by means of: (i) an interdiffusion couple and (ii) layers deposited by dip ... [more ▼]

The chemical interactions between Bi2Sr3CaO7 (Bi-2310) and Bi2Sr2Ca0.8Dy0.2Cu2O8 (Bi-2212(Dy)) at 965 degrees C were investigated by means of: (i) an interdiffusion couple and (ii) layers deposited by dip coating on oxidized nickel Substrates. The samples were characterized by optical and electron microscopies, energy-dispersive x-ray (EDX) analysis and x-ray diffraction. It turns out that at the peritectic temperature Of Bi-2212(Dy), the Bi-2310 phase reacts with the liquid phase resulting from the peritectic decomposition of the Bi-2212(Dy) phase. Dissolution of Bi-2310 leads to an enrichment in Sr and an impoverishment in Cu of the liquid phase, resulting in a shift of the composition of the insoluble phase towards the Ca-rich end of the (Ca, Sr)O Solid Solution. [less ▲]

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See detailChemical Mass Balance model applied to an olfactory annoyance problematic
Clarke, Kevin; Redon, Nathalie; Romain, Anne-Claude ULg et al

in Environmental Science & Technology (2014), Just accepted manuscript(web),

The source-receptor model CMB (Chemical Mass Balance) generally used for air pollution studies is applied for the first time to solve odour signatures issues. The olfactory annoyance perceived at a ... [more ▼]

The source-receptor model CMB (Chemical Mass Balance) generally used for air pollution studies is applied for the first time to solve odour signatures issues. The olfactory annoyance perceived at a receptor site of an industrial area is often the result of a combination of different smells, emitted by several industrial sources. To identify the main responsible for the inconvenience, tools able to determine the contribution of each source directly where the annoyance is perceived are widely developed and deployed. In this work, the contributions of VOC sources, coming from a waste treatment plant containing 3 potential sources of olfactory annoyance (waste storage, production of biogas, and compost piles of green wastes), and perceived at a village located downwind, are studied by chemical analyses. The CMB methodology is applied and the results are finally compared to olfactometric methods, in order to validate whether it is appropriate to use this model for olfactory problems or not. [less ▲]

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See detailChemical methods in an integrated action against Eupulvinaria hydrangeae in Belgium
Tondeur; Schiffers, Bruno ULg; Verstraeten, Ch. et al

Scientific conference (1990)

Detailed reference viewed: 14 (1 ULg)
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See detailChemical modification of the nicotinic cholinergic receptor of PC-12 nerve cell.
Leprince, Pierre ULg

in Biochemistry (1983), 22(24), 5551-6

The identity of the protein that mediates the nicotinic acetylcholine sensitivity in neuronal cells has been investigated by chemical modification and affinity labeling. When an ion flux assay is used, it ... [more ▼]

The identity of the protein that mediates the nicotinic acetylcholine sensitivity in neuronal cells has been investigated by chemical modification and affinity labeling. When an ion flux assay is used, it is possible to measure specifically the activity of the ionophore associated with the nicotinic acetylcholine receptor in cultured nerve cells (PC-12 pheochromocytoma). This activity is modulated by modification of the redox state of at least one disulfide bridge located at the vicinity of the agonist binding site. The oxidizing agent 5,5'-dithiobis(nitrobenzoic acid) restores the complete receptor response which had been inhibited by reduction with dithiothreitol. N-Ethylmaleimide and the nicotinic affinity labels [4-(N-maleimido)benzyl]-alpha-trimethylammonium iodide and bromoacetylcholine react also with the reduced receptor and irreversibly block the agonist-dependent response of the ionophore. The two affinity labels show strong affinities for the receptor, and apparent IC50 values of 20 and 560 nM can be respectively evaluated. Bromoacetylcholine, being an acetylcholine analogue, blocks the receptor function by desensitization, a process in which the constant interaction with the activator causes a shift into an inactive form of the receptor. Bromoacetylcholine can also be shown to activate untreated as well as reduced cells. In this case, the bound label induces a lasting response which is terminated by the irreversible desensitization of the modified receptor. These experiments thus show that the PC-12 nicotinic ionophore shares functional and structural similarities with peripheral receptors. They suggest that nicotinic affinity labels developed for the muscle receptor can also be used as specific markers of the nicotinic neural ionophore. [less ▲]

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See detailChemical modifications of the N-methyl laudanosine scaffold point to new directions for SK channels exploration
Badarau, Eduard; Dilly, Sébastien ULg; Wouters, Johan et al

in Bioorganic & Medicinal Chemistry Letters (2014), 24

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See detailChemical Modifications on 4-Arylpiperazine-Ethyl Carboxamide Derivatives Differentially Modulate Affinity for 5-HT1A, D4.2, and alpha(2A) Receptors: Synthesis and In Vitro Radioligand Binding Studies
Graulich, Amaury; Léonard, Marc ULg; Résimont, Mélissa et al

in Australian Journal of Chemistry (2010), 63

A series of substituted 4-aryl-piperazine ethyl heteroarylcarboxamides were prepared and tested in in vitro radioligand binding studies. The presence of a quinoxaline has a favourable impact in terms of ... [more ▼]

A series of substituted 4-aryl-piperazine ethyl heteroarylcarboxamides were prepared and tested in in vitro radioligand binding studies. The presence of a quinoxaline has a favourable impact in terms of serotonin 5-HT1A versus dopamine D4.2 receptor selectivity. Compounds with a 3-CF3 group at the distal phenyl ring are the most effective in terms of affinity and selectivity for 5-HT1A versus D4.2 receptors. A 4-phenyl-1,2,3,6-tetrahydropyridine in replacement of the corresponding 4-phenyl-piperazine side chain is also favourable not only for the affinity for 5-HT1A and D4.2 receptors but also in some cases for 2A-adrenoceptors. [less ▲]

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See detailChemical Modifiers of Cancer Treatment
Coucke, Philippe ULg; Workman, Paul; Coleman, Norman

in Chemical Modifiers of Cancer Treatment (1995, August 22)

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See detailA Chemical Platform for the Design of Versatile AFM Probes
Willet, Nicolas ULg; Duwez, Anne-Sophie ULg

in Hinterdorfer, Peter; Schütz, Gerhard; Pohl, Peter (Eds.) Proceedings of the IX. Linz Winter Workshop 2007 (2008)

Detailed reference viewed: 14 (4 ULg)
See detailChemical probes and signaling pathways for the orphan GPCR GPR27
Dupuis, Nadine ULg; Gilissen, Julie ULg; Pirotte, Bernard ULg et al

Poster (2013, January 28)

Detailed reference viewed: 21 (1 ULg)