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Peer Reviewed
See detailOptimization of calcium phosphate scaffold-cell combinations using an integrative model based approach
Carlier, Aurélie ULg; Chai, Yoke Chin; Theys, Tina et al

in International Conference on Tissue Engineering (ECCOMAS) - proceedings (2011, June 03)

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See detailOptimization of computed tomography (CT) arthrography of hip for the visualization of cartilage: an in vitro study
SIMONI, Paolo ULg; Leyder, Pierre-Philippe; Albert, Adelin ULg et al

in Skeletal Radiology (2013), 43(2), 169-178

OBJECTIVE: We sought to optimize the kilovoltage, tube current, and the radiation dose of computed tomographic arthrography of the hip joint using in vitro methods. MATERIALS AND METHODS: A phantom was ... [more ▼]

OBJECTIVE: We sought to optimize the kilovoltage, tube current, and the radiation dose of computed tomographic arthrography of the hip joint using in vitro methods. MATERIALS AND METHODS: A phantom was prepared using a left femoral head harvested from a patient undergoing total hip arthroplasty and packed in a condom filled with iodinated contrast. The right hip joint of a cadaver was also injected with iodinated contrast. The phantom and the cadaver were scanned using different values of peak kilovoltage (kVp) and tube current (milliamp seconds, mAs). Three different regions of interest (ROI) were drawn in the cartilage, subchondral bone plate, and intraarticular contrast. The attenuation values, contrast/noise ratio (CNR), and effective dose were calculated. Two independent observers classified the quality of the contrast-cartilage interface and the cartilage-subchondral bone plate interface as (1) diagnostic quality or (2) nondiagnostic quality. RESULTS: Contrast, cartilage, and subchondral bone plate attenuation values decreased at higher kVp. CNR increased with both kVp and mAs. The qualitative analysis showed that in both phantom and cadaver, at 120 kVp and 50 mAs, the contrast-cartilage and cartilage-subchondral bone plate interfaces were of diagnostic quality, with an effective dose decreased to 0.5 MSv. CONCLUSIONS: The absolute effective dose is not directly related to the quality of images but to the specific combination of kVp and mAs used for image acquisition. The combination of 120 kVp and 50 mAs can be suggested to decrease the dose without adversely affect the visibility of cartilage and subchondral bone plate. [less ▲]

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See detailOptimization of conditions for the glycosyltransferase activity of penicillin-binding protein 1a from Thermotoga maritima.
Offant, Julien; Terrak, Mohammed ULg; Derouaux, Adeline ULg et al

in FEBS Journal (2010), 277(20), 4290-8

Cell wall biosynthesis is a key target for antibacterial drugs. The major constituent of the bacterial wall, peptidoglycan, is a netlike polymer responsible for the size and shape of the cell and for ... [more ▼]

Cell wall biosynthesis is a key target for antibacterial drugs. The major constituent of the bacterial wall, peptidoglycan, is a netlike polymer responsible for the size and shape of the cell and for resisting osmotic pressure. It consists of glycan chains of repeating disaccharide units cross-linked through short peptide chains. Peptidoglycan assembly is catalyzed by the periplasmic domain of bifunctional class A penicillin-binding proteins. Cross-linking of the peptide chains is catalyzed by their transpeptidase module, which can be inhibited by the most widely used antibiotics, the beta-lactams. In contrast, no drug in clinical use inhibits the polymerization of the glycan chains, catalyzed by their glycosyltransferase module, although it is an obvious target. We report here the purification of the ectodomain of the class A penicillin-binding protein 1a from Thermotoga maritima (Tm-1a*), expressed recombinantly in Escherichia coli. A detergent screen showed that detergents with shorter aliphatic chains were better solubilizers. Cyclohexyl-hexyl-beta-D-maltoside-purified Tm-1a* was found to be monomeric and to have improved thermal stability. A miniaturized, multiwell continuous fluorescence assay of the glycosyltransferase activity was used to screen for optimal reaction conditions. Tm-1a* was active as a glycosyltransferase, catalyzing the formation of glycan chains up to 16 disaccharide units long. Our results emphasize the importance of the detergent in preparing a stable monomeric ectodomain of a class A penicillin-binding protein. Our assay could be used to screen collections of compounds for inhibitors of peptidoglycan glycosyltransferases that could serve as the basis for the development of novel antibiotics. [less ▲]

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See detailOptimization of cricket breeding production system for human food in Ratanakiri province (Cambodia)
Caparros Megido, Rudy ULg; Alabi, Taofic ULg; Nieus, Clément et al

Poster (2014)

Despite many natural resources, Cambodia is considered as a relatively poor country with a Gross National Income per capita averaging about 880 USD in 2012. Annâdya project in the Ratanakiri province ... [more ▼]

Despite many natural resources, Cambodia is considered as a relatively poor country with a Gross National Income per capita averaging about 880 USD in 2012. Annâdya project in the Ratanakiri province (Cambodia) aims to improve the food security and nutrition of smallholder households by introducing and facilitating the adoption of productive and environmentally sustainable agricultural technologies. The main purpose of this work was to optimize a cheap cricket breeding production system for local farmers to contribute to the reduction of protein deficiency and to create new source of incomes. Cricket development, Teleogryllus testaceus (Walker), was compared between seven diets composed of different ratio of aerial parts of taro, young cassava leaves, young cashew leaves, brown rice flour (with or without the addition of banana slices) and between the traditionally used chicken feed diet. Cricket mortality was relatively low on all diets (<10 %) excepted on the two cashew-based diets where mortality achieves 90 %. Mean adult body mass of the cricket was significantly higher on control diet (chicken feed) and on the two cassava-based diet (80% of cassava leave flour, 20% of brown rice with or without banana slices) than on the other diets (F = 20.87, P<0.001). The nutritional analyzes of the seven diets shows that the ideal diet should contain 19% protein, 5-6% fat, and a percentage of carbohydrates as high as possible. While the cricket mass body gain seems to be proportional to the carbohydrate content of the diet, the use of older cassava leaves, more rich in carbohydrates than the younger ones, is an interesting solution to substitute relatively expensive brown rice and banana slices also consumed by local population. In the future, consideration should be given to the adjustment of cassava leave maturity in function of the cricket growth stage as it is already done with chicken feed in Thai cricket farms. [less ▲]

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See detailOptimization of drug-cyclodextrin complexation reaction by a static supercritical carbon dioxide method
Brion, Michael; Nizet, Dominique; Piel, Géraldine ULg et al

Conference (2007)

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See detailOptimization of dynamic embedded, Water based surface heat (and cold) emitting system for buildings.
Thomas, Sébastien ULg; Franck, Pierre-Yves ULg; Andre, Philippe ULg

Conference (2009, October)

This paper presents the heat flow model and the experimental test bench developed to optimize a new kind of heating floor. In the first part of the text is described the new kind of high reactivity ... [more ▼]

This paper presents the heat flow model and the experimental test bench developed to optimize a new kind of heating floor. In the first part of the text is described the new kind of high reactivity emitting device for building heating and cooling. A second part illustrates the numerical model developed to evaluate the device efficiency. Finally experimental test bench implementation and results are presented. Both computational and experimental results support the use of colder water in comparison to other heating devices. This implies energy savings for building heating. [less ▲]

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See detailOptimization of encoding specificity for the diagnosis of early AD: The RI-48 task
Adam, Stéphane ULg; Van der Linden, Martial ULg; Ivanoiu, A. et al

in Journal of Clinical & Experimental Neuropsychology (2007), 29(5), 477-487

The aim of this study was to evaluate the discriminant validity of the RI-48 test, a shorter French version of the Category Cued Recall portion of the Double Memory Test developed initially by Buschke and ... [more ▼]

The aim of this study was to evaluate the discriminant validity of the RI-48 test, a shorter French version of the Category Cued Recall portion of the Double Memory Test developed initially by Buschke and colleagues (1997), in the diagnosis of mild and very mild Alzheimer disease (AD). The distinctive feature of the RI-48 task is that encoding specificity was increased by adding an immediate cued recall stage at the encoding phase. The results show that the RI-48 task seems to be well adapted to the clinical context and to have good psychometric properties, in particular a lack of a ceiling effect. Moreover, this task appears to be especially well suited for the diagnosis of both mild and very mild AD (sensitivity of 93% and 83.8%). From a more theoretical point of view, this study confirms the importance of optimizing the encoding specificity for the diagnosis of very mild AD, since the more encoding specificity is accentuated, the more discriminating power is increased for the diagnosis of very mild AD. [less ▲]

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See detailOptimization of enzymatic extraction of ferulic acid from wheat bran, using response surface methodology, and characterization of the resulting fractions
Barberousse, Helene; Kamoun, Amel; Chaabouni, Moncef et al

in Journal of the Science of Food and Agriculture (2009), 89(10), 1634-1641

BACKGROUND: The agro-industries generate thousands of tons of by-products, such as bran or pulps, each year. They are, at best, used for cattle feeding. Through biocracking, this biomass may constitute a ... [more ▼]

BACKGROUND: The agro-industries generate thousands of tons of by-products, such as bran or pulps, each year. They are, at best, used for cattle feeding. Through biocracking, this biomass may constitute a renewable source for various molecules of interest for the industry. For instance, ferulic acid, a compound showing antioxidant ability, is found in abundance in cereal bran. Its release depends mainly on the breaking of its ester linkage to other constitutive elements of the cell wall, such as arabinoxylans. Response surface methodology was used to evaluate the effects of ferulic acid esterase (FAE) and xylanase activities, as well as incubation time and temperature, on ferulic acid extraction yield from wheat bran. Under optimized conditions, the composition of the hydrolysate and of residual bran were compared to native bran. RESULTS: Experiments carried out under the predicted optimal conditions (FAE amount, 27 U g(-1); xylanase amount, 304 U g(-1); incubation time, 2 h; and temperature, 65 degrees C) led to an extraction yield of 52.8%, agreeing with the expected value (51.0%). The crude ferulic acid fraction was purified with Amberlite XAD16, leading to a final concentration of 125 mu g mL(-1) of ferulic acid in ethanol. The antioxidant capacity of this purified fraction was evaluated by the DPPH. scavenging method: it exhibited better efficiency (EC50 = 10.6 mu mol L-1 in ferulic acid) than the ferulic acid standard (EC50 = 13.7 mu mol L-1). CONCLUSION: These results confirm the potential of wheat bran valorization in the field of natural antioxidant extraction, possibly viable in an industrial scheme. (C) 2009 Society of Chemical Industry [less ▲]

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See detailOptimization of experimental procedure and statistical data treatment for kinetics of ethylene hydrogenation on a copper-magnesia catalyst
Pirard, Sophie ULg; Heinrichs, Benoît ULg; Heyen, Georges ULg et al

in Chemical Engineering Journal (2008), 138(1-3), 367-378

This study is an example of practical application of kinetic data treatment for simultaneous model discrimination and parameter estimation. The study is applied to the hydrogenation of ethylene on a ... [more ▼]

This study is an example of practical application of kinetic data treatment for simultaneous model discrimination and parameter estimation. The study is applied to the hydrogenation of ethylene on a copper-magnesia catalyst and brings a deepened analysis about the experimental strategy by comparing several alternative strategies using a priori and sequential experimental designs. The best model corresponds to a Langmuir-Hinshelwood mechanism with non-competing adsorption of hydrogen and ethylene and where the rate-determining step is either the addition of molecularly adsorbed hydrogen or the addition of the second atom of hydrogen adsorbed dissociatively. Furthermore, the important question of knowing in practice how many designs and how many measurements per design are actually necessary to determine accurate kinetic and physico-chemical parameters, is addressed. A data correction procedure is also presented that takes catalyst deactivation into account. (C) 2007 Elsevier B.V. All rights reserved. [less ▲]

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See detailOptimization of external poly base sheet resistance in 0.13 µm quasi self-aligned SiGe:C HBTs
You, Suzhen; Van Huylenbroeck, Stefaan; Nguyen, Ngoc Duy ULg et al

in Thin Solid Films (2009), 518(6), 68

This paper investigates the optimization of the external polysilicon base sheet resistance of quasi self-aligned (QSA) SiGe:C HBTs from a 0.13 μm BiCMOS process. Taking advantage of optimized implant ... [more ▼]

This paper investigates the optimization of the external polysilicon base sheet resistance of quasi self-aligned (QSA) SiGe:C HBTs from a 0.13 μm BiCMOS process. Taking advantage of optimized implant conditions to improve the doping of the external base poly, and using an optimized non-selective epitaxy process with improved growth rate ratio of 1.7 between the polycrystalline silicon and monocrystalline silicon of the base, the maximum oscillation frequency fmax reaches 300 GHz. [less ▲]

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See detailOptimization of flexible components in reciprocating engines with cyclic dynamic loading
Tromme, Emmanuel ULg; Bruls, Olivier ULg; Duysinx, Pierre ULg

in Samin, Jean-Claude; Fisette, Paul (Eds.) Proceedings of Multibody Dynamics 2011, Eccomas Thematic Conference: Brussels (Belgium), 4-7 juillet 2011 (2011, July 05)

This work considers the optimization of flexible components of mechanical systems modeled as multibody systems. This approach permits to better capture the effects of dynamic loading under service ... [more ▼]

This work considers the optimization of flexible components of mechanical systems modeled as multibody systems. This approach permits to better capture the effects of dynamic loading under service conditions. This process is challenging because most state-of-the-art studies in structural optimization have been conducted under static or quasi-static conditions. The formulation of the optimization problem for dynamic systems is fundamental; it is not a simple extension of static optimization. Naive implementation leads to fragile and unstable results. The present paper addresses the optimization of a connecting rod of a reciprocating engine with cyclic dynamic loading. Gradient-based methods are adopted for their convergence speed. Different formulations are investigated and compared. A first numerical application considers the optimization of the connecting rod regarding its mass and its elongation. After, another numerical application is carried on considering the stresses in the connecting rod. A conclusion on the influence of the optimization problem formulation is realized. [less ▲]

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See detailOptimization of formic/acetic acid delignification of Miscanthus ×giganteus for enzymatic hydrolysis using response surface methodology
Vanderghem, Caroline ULg; Brostaux, Yves ULg; Jacquet, Nicolas ULg et al

in Industrial Crops & Products (2012), 35

A Box–Behnken experimental design and response surface methodology were employed to optimize the pretreatment parameters of a formic/acetic acid delignification treatment of Miscanthus ×giganteus for ... [more ▼]

A Box–Behnken experimental design and response surface methodology were employed to optimize the pretreatment parameters of a formic/acetic acid delignification treatment of Miscanthus ×giganteus for enzymatic hydrolysis. The effects of three independent variables, namely cooking time (1, 2 and 3 h), formic acid/acetic acid/water ratio (20/60/20, 30/50/20 and 40/40/20) and temperature (80, 90 and 107 ◦C) on pulp yield, residual Klason lignin content, concentration of degradation products (furfural and hydroxymethylfurfural) in the black liquor, and enzymatic digestibility of the pulps were investigated. The major parameter influencing was the temperature for pulp yield, delignification degree, furfural production and enzymatic digestibility. According to the response surface analysis the optimum conditions predicted for a maximum enzymatic digestibility of the glucan (75.3%) would be obtained using a cooking time of 3 h, at 107 ◦C and with a formic acid/acetic acid/water ratio of 40/40/20%. Glucan digestibility was highly dependent on the delignification degree. [less ▲]

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See detailOptimization of Hull Structures for a 60 meters Mega Yacht
Motta, Dario; Caprace, Jean-David ULg; Rigo, Philippe ULg et al

in Proceeding of the 11th International Conference on Fast Sea Transportation (2011, September)

As well known already in earliest phases of a ship project many aspects and choices depend on the structural design which has been defined only at a preliminary level. This trend appears to be similar for ... [more ▼]

As well known already in earliest phases of a ship project many aspects and choices depend on the structural design which has been defined only at a preliminary level. This trend appears to be similar for merchant ships, passenger ships and motor yachts. Only in the final part of the project some shipyards begin to apply optimization processes, more or less sophisticated, in order to refine the structural design in view of reducing the weight and/or the construction cost. The weight in particular has a very important impact on pleasure vessels, both motor and sailing. Structural modifications suggested by such optimization procedures imply a number of second order changes in related items such as plant, outfitting and others. As a consequence the structural optimization could be particularly useful if it can be applied during the first stages of the project, this way avoiding very expensive time losses and changes caused by any structural modifications. In this paper the structural optimization of a 60 meters megayacht is presented, performed by LBR-5 code developed by the University of Liege. This code is an optimization tool specifically designed for structures composed by stiffened plates and stiffened cylindrical shells. The optimal solution is reached through an optimization algorithm based on convex linearization and a dual approach. The LBR-5 software has been successfully utilized to optimize hull structures of a 60 meters megayacht. Differently from large ships, the mega yacht has not a “cylindrical body” in the central part of the hull. So, a new module of the software has been used in order to analyze several sections of the ship and to perform an overall optimization. For this application the optimization analysis has been carried out by different approaches: assuming the weight as the objective function a gain of about 8% has been achieved, while a least cost optimization allowed a reduction of 15%. [less ▲]

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See detailOPTIMIZATION OF HUMAN ES CELLS (hESCs) CRYOPRESERVATION
Connan, Delphine ULg; Ectors, Fabien ULg; Grobet, Luc ULg et al

Poster (2012, October 22)

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See detailOptimization Of Issr Marker For African Edible-Seeded Cucurbitaceae Species' Genetic Diversity Analysis
Dje, Yao; Tahi, G. C.; Zoro Bi, Arsène I. et al

in African Journal of Biotechnology (2006), 5(2), 83-87

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See detailOptimization of Large Flexural Finite Element Systems
Fleury, Claude ULg

in HAUG, Edward J.; CEA, Jean (Eds.) Optimization of distributed parameter structures. Proceedings of the NATO advanced study institute held in Iowa City, Iowa, on May 20-June 4, 1980 (1981)

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See detailOptimization of ligand-binding assay in a QbD environment. Use of Bayesian non-linear regression to set up probability profile as quality response
Lebrun, Pierre ULg; Boulanger, Bruno ULg; Hubert, Philippe ULg

Conference (2010, September 28)

For ligan-binding assay, different parameters are controlled in routine. In a development phase, we will show how design of experiment can be used to select these parameters to obtain reliable results in ... [more ▼]

For ligan-binding assay, different parameters are controlled in routine. In a development phase, we will show how design of experiment can be used to select these parameters to obtain reliable results in the future use of the ELISA test. Uncertainties of measurements and models should be taken into account in a predictive manner. Bayesian modelling and MCMC simulations are well suited for this purpose and are flexible enough to include random effects on the parameters on non-linear model. We will focus on 4PL regression as it is encountered in most applications. We will also show that deriving a quality response such as a precision profile is clear and direct in the Bayesian setting. The approach is fully compliant with QbD guidelines and Design Space definition. [less ▲]

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See detailOPTIMIZATION OF LIPASE-CATALYZED SYNTHESIS OF CITRONELLYL ACETATE IN SOLVENT-FREE MEDIUM
Fonteyn, Fabienne ULg; Blecker, Christophe ULg; Lognay, Georges ULg et al

in Biotechnology Letters (1994), 16(7), 693-696

Citronellol esterification catalyzed by Candida antarctica lipase is performed with high yields (74%) in a solvent-free medium. The use of dessicants gives a 10% yield enhancement and substrate excess ... [more ▼]

Citronellol esterification catalyzed by Candida antarctica lipase is performed with high yields (74%) in a solvent-free medium. The use of dessicants gives a 10% yield enhancement and substrate excess consumption by adding calculated amounts of acetic acid lead to a 80% pure citronellyl acetate. Quantities up to 100 ml are treated with success. [less ▲]

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See detailOptimization of Matrix Conditions for the Control of MALDI In-Source Decay of Permethylated Glycans.
Smargiasso, Nicolas ULg; De Pauw, Edwin ULg

in Analytical Chemistry (2010), sous presee

Due to its fastness and its easiness to use, MALDI-MS is currently an analytical tool widely used in glycomic applications. However, the MALDI ionization process could result in the so-called "in-source ... [more ▼]

Due to its fastness and its easiness to use, MALDI-MS is currently an analytical tool widely used in glycomic applications. However, the MALDI ionization process could result in the so-called "in-source decay", or ISD, of analytes, leading to complex spectra. On the other hand, ISD opens the possibility to perform pseudo-MS(3) experiments. This phenomenon must therefore be controlled in order to be used on demand as a supplementary tool for the analysis of permethylated glycans by MALDI mass spectrometry. For this purpose, several matrices were tested and MALDI imaging was used to determine optimal conditions promoting or, inversely, avoiding ISD of permethylated glycans. 2,5-DHB was shown to be a versatile matrix allowing one to induce or prevent ISD according to the location of laser shots. Inversely, it was shown that 9-aminoacridine forms homogeneous spots and avoids completely ISD. This matrix would therefore be suitable for automatic analysis. [less ▲]

Detailed reference viewed: 55 (14 ULg)