Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailThe lipoxygenase metabolic pathway in plants: potential for industrial production of natural green leaf volatiles
Gigot, Cédric ULg; Ongena, Marc ULg; Fauconnier, Marie-Laure ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(3), 451-460

Lipoxygenase enzymatic pathway is a widely studied mechanism in the plant kingdom. Combined actions of three enzymes: lipase, lipoxygenase (LOX) and hydroperoxide lyase (HPL) convert lipidic substrates ... [more ▼]

Lipoxygenase enzymatic pathway is a widely studied mechanism in the plant kingdom. Combined actions of three enzymes: lipase, lipoxygenase (LOX) and hydroperoxide lyase (HPL) convert lipidic substrates such as C18:2 and C18:3 fatty acids into short chain volatiles. These reactions, triggered by cell membrane disruptions, produce compounds known as Green Leaf Volatiles (GLVs) which are C6 or C9-aldehydes and alcohols. These GLVs are commonly used as flavors to confer a fresh green odor of vegetable to food products. Therefore, competitive biocatalytic productions have been developed to meet the high demand in these natural flavors. Vegetable oils, chosen for their lipidic acid profile, are converted by soybean LOX and plant HPL into natural GLVs. However this second step of the bioconversion presents low yield due to the HPL instability and the inhibition by its substrate. This paper will shortly describe the different enzymes involved in this bioconversion with regards to their chemical and enzymatic properties. Biotechnological techniques to enhance their production potentialities will be discussed along with their implication in a complete bioprocess, from the lipid substrate to the corresponding aldehydic or alcoholic flavors. [less ▲]

Detailed reference viewed: 65 (15 ULg)
Full Text
Peer Reviewed
See detailLipoxygenase pathway and antioxidant system in salt-stressed tomato seedlings (Lycopersicon esculentum Mill.).
Delaplace, Pierre ULg; Frettinger, P.; Ghanem, M. E. et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2009), 13

Detailed reference viewed: 50 (24 ULg)
Full Text
Peer Reviewed
See detailLes lipoxygénases du soja.
Fauconnier, Marie-Laure ULg; Marlier, M.

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (1997), 1(2), 125-141

Dans cet article de synthèse, les auteurs font le point sur les connaissances actuelles dans le domaine des lioxygénases du soja. Une attention particulière est portée à la compréhension des mécanismes ... [more ▼]

Dans cet article de synthèse, les auteurs font le point sur les connaissances actuelles dans le domaine des lioxygénases du soja. Une attention particulière est portée à la compréhension des mécanismes réactionnels (substrats, inhibiteurs, site actif, etc.). Le rôle physiologique ainsi que l'utilisation de cet enzuyme dans les industries agroalimentaires et en biotechnologie sont également abordés. [less ▲]

Detailed reference viewed: 10 (3 ULg)
Full Text
Peer Reviewed
See detailLiquid chromatographic analysis of local anesthetics in human plasma after sample preparation by on-line dialysis. Optimization by use of experimental design
Chiap, Patrice ULg; Boulanger, Bruno ULg; Fotsing, Lucas ULg et al

in Chromatographia (2001), 53(11-12), 678-686

A fully automated method involving dialysis, clean-up and enrichment of the dialysate on a pre-column packed with a strong cation-exchange phase, and subsequent liquid chromatographic (LC) analysis with ... [more ▼]

A fully automated method involving dialysis, clean-up and enrichment of the dialysate on a pre-column packed with a strong cation-exchange phase, and subsequent liquid chromatographic (LC) analysis with UV detection at 220 nm has been developed for the determination of local anesthetics (prilocaine, mepivacaine, and bupivacaine) in human plasma. All sample-handling operations were executed automatically by means of an Asted XI system. To identify the most important conditions affecting analyte recovery from the dialysis and trace-enrichment processes, a seven-factor D-optimal design with 16 experimental points was elaborated as a screening test A four-factor D-optimal design with 24 experimental points was then used to predict and optimize analyte recovery. Derringer's desirability function was also used to deduce optimum conditions for analyte recovery and dialysis time within the experimental domain. Finally, the method developed was validated. Mean recoveries were approximately 72% for bupivacaine and approximately 67% for mepivacaine and prilocaine. The limits of quantification were 28 ng mL(-1) for bupivacaine and 25 ng mL(-1) for mepivacaine and prilocaine. [less ▲]

Detailed reference viewed: 11 (1 ULg)
Full Text
Peer Reviewed
See detailLiquid chromatographic determination of enrofloxacin in nasal secretions and plasma of healthy pigs using restricted access material for on-line sample clean-up
Bimazubute, M. A.; Rozet, Eric ULg; Dizier, Isabelle ULg et al

in Journal of Chromatography. A (2008), 1189(1-2), 456-466

A new fully automated method was developed for the quantitative analysis of an antibacterial drug, enrofloxacin (ENRO), in both nasal secretions and plasma samples of healthy pigs. The method is based on ... [more ▼]

A new fully automated method was developed for the quantitative analysis of an antibacterial drug, enrofloxacin (ENRO), in both nasal secretions and plasma samples of healthy pigs. The method is based on the use of a pre-column packed with restricted access material (RAM), namely RP-18 ADS (alkyl diol silica), for on-line sample clean-up coupled to a liquid chromatographic (LC) column containing octadecyl silica. The only off-line sample preparation was the 50-fold dilution of nasal secretions and plasma samples in the washing liquid composed of 25 mM phosphate buffer of pH 7.4. A 10 μl diluted sample volume was injected directly onto the pre-column and washed for 7 min. By rotation of a switching valve, the analyte of interest was eluted in the back-flush mode with the LC mobile phase which consisted in a mixture of 25 mM phosphate buffer of pH 3.0 and acetonitrile according to a segmented gradient elution. By a new rotation of the switching valve, the pre-column and the analytical column were equilibrated for 3 min with the initial mobile phases. The flow-rate was 0.8 ml min−1 for the washing liquid and 1.5 ml min−1 for the LC mobile phase. ENRO was detected by fluorescence at excitation and emission wavelengths of 278 and 445 nm, respectively. Finally, the developed method was validated using an original strategy based on total measurement error and accuracy profiles as a decision tool. The limits of quantitation of ENRO in plasma and in nasal secretions were 30.5 and 91.6 ng/ml, respectively. The validated method was then applied successfully to the determination of ENRO in healthy pigs treated by intramuscular injection at different doses (2.5, 10 and 30 mg/kg bodyweight) for a pilot study. This method could be also used for the simultaneous analysis of ENRO and its main metabolite, ciprofloxacin (CIPRO). [less ▲]

Detailed reference viewed: 65 (4 ULg)
Peer Reviewed
See detailLiquid crystalline ordering of procollagen as a determinant of three-dimensional extracellular matrix architecture.
Martin, Raquel; Farjanel, J.; Eichenberger, D. et al

in Journal of Molecular Biology (2000), 301(1), 11-7

The precise molecular mechanisms that determine the three-dimensional architectures of tissues remain largely unknown. Within tissues rich in extracellular matrix, collagen fibrils are frequently arranged ... [more ▼]

The precise molecular mechanisms that determine the three-dimensional architectures of tissues remain largely unknown. Within tissues rich in extracellular matrix, collagen fibrils are frequently arranged in a tissue-specific manner, as in certain liquid crystals. For example, the continuous twist between fibrils in compact bone osteons resembles a cholesteric mesophase, while in tendon, the regular, planar undulation, or "crimp", is akin to a precholesteric mesophase. Such analogies suggest that liquid crystalline organisation plays a role in the determination of tissue form, but it is hard to see how insoluble fibrils could spontaneously and specifically rearrange in this way. Collagen molecules, in dilute acid solution, are known to form nematic, precholesteric and cholesteric phases, but the relevance to physiological assembly mechanisms is unclear. In vivo, fibrillar collagens are synthesised in soluble precursor form, procollagens, with terminal propeptide extensions. Here, we show, by polarized light microscopy of highly concentrated (5-30 mg/ml) viscous drops, that procollagen molecules in physiological buffer conditions can also develop long-range nematic and precholesteric liquid crystalline ordering extending over 100 microm(2) domains, while remaining in true solution. These observations suggest the novel concept that supra-fibrillar tissue architecture is determined by the ability of soluble precursor molecules to form liquid crystalline arrays, prior to fibril assembly. [less ▲]

Detailed reference viewed: 25 (1 ULg)
Full Text
Peer Reviewed
See detailLiquid Crystalline Phases Induced by the Hydroxyl Group Stereochemistry of Amphiphilic Carbohydrate Bicatenary Derivatives
Razafindralambo, Hary ULg; Richel, Aurore ULg; Paquot, Michel ULg et al

in Journal of Physical Chemistry B (2012), 116(13), 3998-4005

Liquid-crystals (LC) may exist in different phases depending upon the orientational and positional orders of molecules in the material. Here, we demonstrate that the class of LC state induced by ... [more ▼]

Liquid-crystals (LC) may exist in different phases depending upon the orientational and positional orders of molecules in the material. Here, we demonstrate that the class of LC state induced by amphiphilic carbohydrate bicatenary derivatives is strictly a hydroxyl group stereochemistry-dependent. This statement results from the experimental and theoretical investigations of surface film (2D) and bulk solid (3D) thermal behavior of synthetic stereoisomers n-tetradecyl (-D-n-tetradecyl) galacto- and gluco-pyranosiduronate, with an axial (GalA-C14/14) or equatorial (GlcA-C14/14) hydroxyl group at the fourth carbon, respectively. Surface pressure-area isotherms (283 K to 310 K), differential scanning calorimetry thermograms (223 K to 573 K), and polarized optical textures (298-363 K) reveal that GlcA-C14/14 organizes as a smectic LC-like phase (positional or lateral order) whereas the analogous stereoisomeric GalA-C14/14 behaves as a nematic LC-like phase (orientational order). Thermodynamic investigations and molecular dynamics models computed under similar temperature conditions provide consistent data with physical properties resulting from experimental approaches. [less ▲]

Detailed reference viewed: 49 (23 ULg)
Full Text
Peer Reviewed
See detailLiquid detection in confined aircraft structures based on lyotropic percolation thresholds
Pfeiffer, Helge; Heer, Peter; Pitropakis, Ioannis et al

in SENSORS AND ACTUATORS B-CHEMICAL (2012), 161(1), 791-798

In aircraft, aqueous liquids arising from spillage, condensation or rainfall during boarding can result in heavy corrosion of structural parts. This is especially the case for the so-called floor ... [more ▼]

In aircraft, aqueous liquids arising from spillage, condensation or rainfall during boarding can result in heavy corrosion of structural parts. This is especially the case for the so-called floor structures in the passengers cabin. A reliable sensor for detecting aqueous liquids which is interrogated at least on a weekly base, or even more frequently, could help to reduce repair and maintenance costs considerably. An important challenge for the installation of sensors in the floor beam area is the limited space available. Furthermore, the sensor has to cover an extended area. To achieve this target, an organo-ceramic composite was developed containing a conducting compound (conducting ceramic powder) which is embedded in a hydrophilic matrix. The functionality of the sensing material is based on the collapse of percolation conductivity of the composite. When the composite is exposed to aqueous liquids, the conductivity is essentially lost by sorption and swelling of the matrix material. Sorption experiments indicate that the loss of conductivity could be triggered, or at least promoted by a lyotropic glass-rubber transition in the hydrophilic matrix. The applicability of the integral system was shown on lab-scale, and a sensor network is already implemented and tested in an operational commercial airliner. (C) 2011 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailLiquid distribution images on structured packing by X-ray computed tomography
Marchot, Pierre ULg; Toye, Dominique ULg; Pelsser, A. M. et al

in AIChE Journal (2001), 47(6), 1471-1476

Detailed reference viewed: 29 (5 ULg)
Full Text
Peer Reviewed
See detailLiquid distribution through a Katapak column by X-ray tomography
Aferka, Saïd ULg; Saroha, Anil; Toye, Dominique ULg et al

Conference (2006)

Detailed reference viewed: 19 (3 ULg)
Full Text
Peer Reviewed
See detailLiquid flooded compression and expansion in scroll machines - Part II: Experimental testing and model validation
Bell, Ian ULg; Lemort, Vincent ULg; Groll, Eckhard et al

in International Journal of Refrigeration (2012), 35

The use of liquid-flooding in the compression and expansion of non-condensable gas in scroll compressors and expanders enables the possibility of quasi-isothermal working processes. Liquid-flooded scroll ... [more ▼]

The use of liquid-flooding in the compression and expansion of non-condensable gas in scroll compressors and expanders enables the possibility of quasi-isothermal working processes. Liquid-flooded scroll machines were installed in a fully-instrumented Liquid- Flooded Ericsson Cycle test rig to conduct entire cycle performance tests. In addition, detailed compressor and expander performance data was obtained. Oil mass fractions of up to 92% and 76% were added to the gas entering the scroll compressor and expander respectively. The overall isentropic efficiency of the scroll compressor based on the shaft power with flooding was up to 73% and the volumetric efficiency was above 92%. For the expander, the best overall isentropic and volumetric efficiencies achieved were 66% and 105% respectively. The mechanistic model presented in the companion paper was vali- dated against the experimental data for both the compressor and the scroll expander with good agreement, though the agreement is better for the scroll compressor. [less ▲]

Detailed reference viewed: 23 (4 ULg)
Full Text
Peer Reviewed
See detailLiquid flow distribution in catalytic distillation columns : use of high-energy X-ray tomography
Aferka, Saïd ULg; Saroha, Anil; Toye, Dominique ULg et al

in AIChE (Ed.) AIChE Annual Meeting, Conference Proceedings, San Francisco, CA, United States, Nov. 12-17, 2006 (2006)

Detailed reference viewed: 11 (3 ULg)
Peer Reviewed
See detailLiquid flow maldistribution in trickle-bed reactors
Crine, Michel ULg; Marchot, Pierre ULg; L'Homme, Guy ULg

in Chemical Engineering Communications (1980), 7

Detailed reference viewed: 24 (17 ULg)
Peer Reviewed
See detailLiquid hold-up measurement in Mellapak Plus 752Y packed bed using X-ray tomography
Aferka, Saïd ULg; Viva, Aurora ULg; Brunazzi, Elisabetta et al

in VCIPT (Ed.) Proceedings of 6th World Congress On Industrial Process Tomography (WCIPT6), Beijing, China, 6-9 Septembre 2010 (2010)

Detailed reference viewed: 71 (9 ULg)