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See detailDevelopment of a multiplexed surface-enhanced Raman scattering quantitative approach for bisphenols detection
De Bleye, Charlotte ULg; Dumont, Elodie ULg; Sacre, Pierre-Yves ULg et al

Conference (2014, June 23)

Over the last decade, bisphenol A (BPA) attracted a lot of attention. This molecule, commonly used as a precursor to produce epoxy-resin and plastics, is an endocrine disruptor presenting an estrogenic ... [more ▼]

Over the last decade, bisphenol A (BPA) attracted a lot of attention. This molecule, commonly used as a precursor to produce epoxy-resin and plastics, is an endocrine disruptor presenting an estrogenic activity [1]. Despite its health toxicity, BPA is present in a broad variety of consumer goods released from plastic bottles and packaging for example. Since the discovery of its adverse health effect of BPA, the manufacturers tend to use structural analogues of BPA such as BPS, BPF and BPB to produce plastic materials [2]. However, the health safety of these molecules is still not demonstrated. Currently, bisphenols are actively researched and quantified using solid phase extraction and chromatography techniques which are time and solvents consuming. Therefore, it could be very interesting to quantify simultaneously bisphenols using a fast and “green” technique. Surface-enhanced Raman scattering (SERS) exalts dramatically the Raman scattering of molecules adsorbed or very closed to metallic surface enabling to detect very low amounts of analytes while keeping the structural information obtained from the spectrum which is very interesting to consider multiplexed analyses [3-4]. Moreover, SERS, which is a solvent free and fast acquisition technique, is an attractive tool in “Green Chemistry” [5]. In this context, the development of a multiplexed quantitative approach to detect bisphenol was considered. Silver nanoparticles (AgNps) were selected as SERS substrate and their functionalization was investigated taking into account the weak affinity of phenolic molecules for gold and silver surface [6]. Pyridine was selected as surface modifier and allowed to attract bisphenols around metallic surface thanks to hydrophobic interaction and hydrogen bonds [7]. Afterwards, the SERS samples preparation was optimized playing on the concentrations of pyridine and aggregating agent used to get the nanoparticles closer to each other which promotes the SERS effect. Tap water samples were spiked with different concentration of BPA from 5 ppb to 1000 ppb and analyzed using the optimized SERS sample preparation. A good linearity of the response was observed and a calibration curve with coefficient of determination (R2) of 0.9922 was obtained by plotting the intensity of a principal band of BPA versus the concentration. This last step was repeated using BPB as analyte and a calibration curve with a R2 of 0.9991 was obtained for the same range of concentration using a specific band intensity of BPB. Finally, tap water samples were spiked with different concentrations of BPA and BPB simultaneously and analyzed using SERS and it was possible to detect selectively the two molecules thanks to specific bands and a good linearity of the response was observed for both. To conclude, promising results were obtained which pave the way to “green” multiplexed quantitative analyses of very low concentrated analytes using SERS. References: [1] J.-H. Kang et al., Toxicology 226 (2006) 79-89 [2] C. Liao et al., J. Agric. Food Chem. 61 (2013) 4655-4662 [3] K. Kneipp et al., Chem. Rev. 99 (1999) 2957-2975. [4] R.F. Aroca et al., Adv.Colloid Interface Sci. 116 (2005) 45-61. [5] C. De Bleye et al., Talanta 116 (2013) 899-905. [6] X.X. Han et al., Anal. Chem., 83 (2011) 8582-8588. [7] B. San Vicente et al., Anal. Bioanal. Chem. 380 (2004) 115-122. [less ▲]

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See detailDevelopment of a national EUCAST challenge panel for antimicrobial susceptibility testing
Desmet, Stefanie; Verhagen, Jan; Glupczynski, Youri et al

in Clinical Microbiology and Infection (2016)

A challenge panel of bacterial strains useful for clinical laboratories to validate their European Committee on Antimicrobial Susceptibility Testing (EUCAST) antimicrobial susceptibility test (AST) system ... [more ▼]

A challenge panel of bacterial strains useful for clinical laboratories to validate their European Committee on Antimicrobial Susceptibility Testing (EUCAST) antimicrobial susceptibility test (AST) system was established. A total of 117 strains, obtained from Belgian Reference Centers (n=57) and from routine clinical samples (n=60) was selected based on resistance pattern. These strains were analyzed in 7 different laboratories by 3 different automated AST systems (Vitek (n=2), Phoenix (n=2) and Microscan (n=2)) and by disk diffusion from 5 different manufacturers (Rosco (n=2), Becton-Dickinson (n=2), Biomérieux (n=1), Bio-rad (n=1) and i2a (n=1)). To select the challenge panel, selection criteria were set for categorical agreement (CA) between the different systems and the number of very major errors (VME), major errors (ME) and minor errors (MI). VMEs or MEs for at least 2 antibiotics were observed in 43% of all strains, leading to the exclusion of these strains to be selected in the panel. In only 10% of all tested strains there was a 100% CA for all antibiotics. Finally, 28 strains (14 Gram-positive and 14 Gram-negative) covering a wide spectrum of resistance mechanisms were selected. Pilot-testing of this challenge panel in 20 laboratories mainly confirmed the results of the validation study. Only 6 strains withheld for the pilot-study could not be used as challenge strain due to an overall (very) major error rate of more than 5% for a particular antibiotic (n=5) or for two antibiotics (n=1). To conclude, this challenge panel should facilitate the implementation and use of EUCAST breakpoints in laboratories. [less ▲]

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See detailDevelopment of a neural network to predict the final geometry of forged rings after cooling
Casotto, S.; Bruschi, S.; Pascon, Frédéric ULg et al

in Banabic, D. (Ed.) Proceedings of the 8th ESAFORM Conference on Material Forming (Vol. 2) (2005)

The paper deals with an application of Artificial Neural Networks (ANNs) to predict the geometry of hot forged pieces after cooling. Different ANNs have been considered and evaluated; then a network with ... [more ▼]

The paper deals with an application of Artificial Neural Networks (ANNs) to predict the geometry of hot forged pieces after cooling. Different ANNs have been considered and evaluated; then a network with two hidden layers has been set up. Training and testing data have been obtained through calibrated numerical simulations of the cooling phase carried out with a finite element (F.E.) code. The good agreement between predicted and numerical results confirms the possibility of using well-trained neural network to foresee final dimensions of pieces after hot forging operations. [less ▲]

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See detailDevelopment of a new commercial qPCR assay to detect and differentiate dermatophyte infections of the skin, nails and hair
Dingemans, Gijs; van den Bosch, Mélanie; HAYETTE, Marie-Pierre ULg et al

Poster (2014, May)

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See detailDevelopment of a new crossbred based evaluation for carcass quality of Piétrain boars in the Walloon Region of Belgium
Dufrasne, Marie ULg; Hammami, Hedi ULg; Jaspart, Véronique et al

in Proceedings of the British Society of Animal Science and the Agricultural Research Forum (2010, April)

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See detailDevelopment of a new crossbred based evaluation for carcass quality of Piétrain boars in the Walloon Region of Belgium
Dufrasne, Marie ULg; Hammami, Hedi ULg; Jaspart, Véronique et al

Poster (2010)

The aim of this study was to develop a genetic evaluation model to estimate the genetic merit of Piétrain boars for some carcass quality traits. These boars are now evaluated on performances recorded on ... [more ▼]

The aim of this study was to develop a genetic evaluation model to estimate the genetic merit of Piétrain boars for some carcass quality traits. These boars are now evaluated on performances recorded on their crossbred progeny fattened in a central test station. Data provided by the on-farm performance recording system were utilized in this study. Traits analysed were backfat thickness (BF) and lean meat percentage (%meat). The data file contains 60 546 records measured on pigs between 150 and 300 days of age. Model developed was a multitrait animal model. Fixed effects were sex, contemporary groups and heterosis, modeled as regression on heterozygosity. Random effects were additive genetic and permanent environment, modeled by random regressions using linear splines, and residual. Variance components were estimated by restricted maximum likelihood (REML) method on random samples of the total dataset and then confirmed by a Gibbs sampling algorithm on the total dataset. Fit of the model was tested by computing residuals from a BLUP (Best Linear Unbiased Prediction) evaluation. BF and %meat have a high heritability that increase with age. These two traits are also highly genetically correlated. Mean residuals are not significantly different from zero for both traits. Given that BF and %meat had high heritability, genetic improvement of carcass quality is possible by selection on these two traits. Like residuals are close to zero for both traits, it seems that model developed explain a great proportion the variance in each traits. [less ▲]

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See detailDevelopment of a new crossbred based evaluation for carcass quality of Piétrain boars in the Walloon Region of Belgium
Dufrasne, Marie ULg; Hammami, Hedi ULg; Jaspart, Véronique et al

in Book of Abstract of the 61st Annual Meeting of the European Association for Animal Production (2010)

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See detailDevelopment of a new design method for steel hollow section members resistance
Hayeck, Marielle ULg

Doctoral thesis (2016)

This dissertation presents research done in the field of enhancing the performance and the carrying capacity of tubular members, through the development of an original design approach based on the ... [more ▼]

This dissertation presents research done in the field of enhancing the performance and the carrying capacity of tubular members, through the development of an original design approach based on the “Overall Interaction Concept” (O.I.C.). The proposed approach makes use of the interaction between the two ideal behaviours of structural members (resistance and instability) and includes the influence of initial imperfections (out-of straightness, residual stresses, non-homogenous material), to calculate the resistance of a structure through a single parameter: “relative slenderness”. A test program was carried out as a part of a European project named ‘HOLLOPOC’ to determine the experimental behaviour of beam-columns loaded by bi-axial bending with axial force. Twelve buckling tests, consisting of hot-rolled and cold-formed rectangular and circular hollow section members were conducted. These tests were accompanied by preliminary measurements of cross-section geometry, material properties, geometrical imperfections, residual stresses as well as stub column tests. Besides, a finite element model was calibrated on the basis of these tests. For both the present test series and another one from the literature, it was shown that the FE models were capable of replicating accurately the response and resistance of the experiments. Accordingly, the validated FE models have been further used in extensive numerical studies, and a database comprising more than seventy thousand results was built consecutively. Based on these computations, design proposals were made, by considering identified governing parameters, within the context of the Overall Interaction Concept, using an extension of the Ayrton-Perry approach. Finally, a safely evaluation was completed to check the proposed formulae against the results of current Eurocode 3 rules. [less ▲]

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See detailDevelopment of a new design method for the cross-section capacity of steel hollow sections
Nseir, Joanna ULg

Doctoral thesis (2015)

The cross-sectional behaviour of steel sections can be shown to be influenced by two extreme behaviors: the resistance and the instability. These boundaries are accounted for in current standards through ... [more ▼]

The cross-sectional behaviour of steel sections can be shown to be influenced by two extreme behaviors: the resistance and the instability. These boundaries are accounted for in current standards through a classification system consisting on rules depending on the cross-section dimensions. For example, in EN 1993-1-1, classes are defined spanning from stocky sections (class 1) able to develop their full plastic capacity, to slender sections (class 4) for which the effective properties are used with the use of the effective width method (EWM). However, for cold-formed steel sections, characterized by a non-linear material law, the cross-section resistance can go beyond its plastic capacity due to strain hardening effects. Moreover, with the emergence of high strength steel (i.e. cross-sections falling into class 4) and more complex cross-section shapes, the effective width method is becoming too complicated. Many other reasons and discrepancies are making the cross-section classification too complex and inconsistent. The Overall Interaction Concept (OIC) stands as a new design approach that aims at a straightforward design check of the stability and resistance of steel cross-sections. Based on the use of a generalized relative slenderness and so-called interaction curves, it can be applied to any type of cross-section, further includes potential non-linear material behaviour and covers combined loading cases. The main aim of this thesis is to develop and propose OIC interaction curves dedicated to steel hollow sections subjected to various load cases. A test program was carried out as a part of a European project named ‘HOLLOPOC’ to investigate the cross-sectional behavior of cold-formed hot-finished and hot-rolled square, rectangular and circular sections. 57 cross-sections tests including simple and combined load cases were performed. Besides, a finite element model was developed and calibrated on the basis of the tests, and its accuracy was seen to be sufficient to subsequently undergo an extensive numerical parametric study for hot-rolled and cold-formed cross-sections, leading to over than 40 000 numerical results. Based on these computations, design proposals were made within the context of the Overall Interaction Concept, using an extension of the Ayrton-Perry approach. Finally, a validation of the proposed formulae was made through a comparison with existing approach and worked examples were presented, in order to illustrate (i) the application of the method and (ii) its benefits in comparison to application of current EC3 rules. [less ▲]

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See detailDevelopment of a new design method to define the rotation capacity of steel hollow sections
Saloumi, Elsy ULg

Doctoral thesis (2016)

The present PhD thesis is dedicated to the characterisation of hollow section shapes’ rotational capacity. More precisely, the effort was made towards suggesting new ways to resort to plastic analysis, by ... [more ▼]

The present PhD thesis is dedicated to the characterisation of hollow section shapes’ rotational capacity. More precisely, the effort was made towards suggesting new ways to resort to plastic analysis, by defining a new and accurate proposition to characterise the rotation capacity Rcap of sections, which could be associated with the rotation demand of a structure Rdem. Therefore, the purpose of this thesis is to establish a direct dependence of the rotation capacity Rcap with a newly defined cross-section slenderness CS. Hence, current design standards disregard the rotation demand of the structure and allow plastic analysis based on a plate slenderness limit. To achieve this purpose, an experimental campaign was performed consisting in 23 bending tests on square and rectangular hollow sections tested in bending, in addition to 8 stub columns. Then, a numerical model based on the finite element software FINELg was calibrated to well represent these experimental tests, as well as cold-formed bending tests from literature. Based on these results, a good agreement between experimental and numerical results was shown and the numerical software was therefore validated. Accordingly, since the numerical software was proved to well represent the bending behaviour of hollow beams, around 8000 finite element simulations were performed while varying sections dimensions, material properties and loading configuration. These results reported that actual standards limitations were inappropriate, and stricter values were proposed. Moreover, based on the numerical computations, a continuous curve capable of describing the rotation capacity of sections as a function of the cross-section slenderness was proposed. The production route, loading application and yield strength were identified as key parameters having a major impact on the rotation capacity of sections. Consequently, different curves were proposed for each parameter; based on these curves, the rotation capacity of the section could be compared to the rotation demand of a structure in order to obtain a practical, safe, and reliable design calculation. [less ▲]

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See detailDevelopment of a new ELISA for measurement of pregnancy-associated glycoprotein.
Delahaut, Ph; Melo de Sousa, Noelita ULg; Huet, A. C. et al

in Proceedings of the 6th European Congress of Bovine Health and Management (ECBHM) (2011, September 07)

In the present study we report the development of a new ELISA for PAG measurement (Ref. code E.G.7, CER, Maloie) in ruminant species. Purified boPAG67kDa protein was purified in our laboratory and used as ... [more ▼]

In the present study we report the development of a new ELISA for PAG measurement (Ref. code E.G.7, CER, Maloie) in ruminant species. Purified boPAG67kDa protein was purified in our laboratory and used as standard. Antiserum raised against caprine PAG 55kDa+62kDa (AS707) was used as capture antibody (1:40,000). Antiserum raised against PAG purified from buffalo placentas (AS859) was used as detection antibody (1:32,000 dilution). Avidin-HRP and TMB completed the ELISA system. Reproducibility was determined by calculating the intra- and inter-assay CV. Accuracy was determined by adding increasing concentrations of purified boPAG67kDa to bovine sera containing low PAG concentrations. Specificity was tested regarding 25 different compounds: carbohydrates, aspartic proteinases, hormones and major plasma proteins. Parallelism was assessed by serially diluting pregnant cow serum containing high PAG concentrations. Sera was collected from pregnant cows (n=4) during the whole duration of gestation. Samples were tested by both RIA and ELISA. Samples giving high PAG concentrations were serially diluted in order to fit with optical density (OD) of the ELISA standard curve. Intra-and inter-assay CV ranged from 5.5 to 9.1%. Accuracy ranged from 92.9 to 105.5%. No cross reaction was observed with almost all tested compounds excepting lactic acid at supra-physiological levels (1 mg/ml). Dilutions of bovine maternal sera were parallel to standard curve. Profiles obtained by ELISA in pregnant cows were very similar to those obtained by RIA. In conclusion, a new PAG-ELISA is available for measurement of PAG concentrations in cattle. This new test was validated in vitro and can be used for pregnancy diagnosis and follow-up of gestation in cattle. [less ▲]

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See detailDevelopment of a new genetic evaluation model for carcass quality based on crossbred performances of Piétrain boars in the Walloon Region of Belgium
Dufrasne, Marie ULg; Hammami, Hedi ULg; Jaspart, Véronique et al

in Proceedings of the 9th World Congress on Genetics Applied to Livestock Production (2010)

In context of the development of the genetic evaluation system of Piétrain boars for crossbred performances, a genetic evaluation model was developed for the estimation of genetic merit of boars for ... [more ▼]

In context of the development of the genetic evaluation system of Piétrain boars for crossbred performances, a genetic evaluation model was developed for the estimation of genetic merit of boars for backfat thickness (BF) and meat percentage (%meat). The model developed was a random regression model using linear splines on age which knots at 175, 200 and 250 days. Variance components were estimated by restricted maximum likelihood and Gibbs sampling. Estimated heritability from 150 to 300 days increased from 0.56 to 0.75 for BF and from 0.55 to 0.69 for %meat. Genetic correlation between BF and %meat varied between -0.90 and -0.93 from 150 to 300 days. According to the study of residuals, the developed model was considered to fit well the data especially between 175 and 250 days of age. [less ▲]

Detailed reference viewed: 31 (8 ULg)