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See detailDevelopment of an all-solid-state pulsed Nd:YAG laser for pumping picosecond OPO systems
Mani, A. A.; Dreesen, Laurent ULg; Hollander, Ph. et al

in Proceedings (1999)

High performance mode-locking of a pulsed Nd:YAG laser was achieved at 1.064 µm by using a frequency doubling nonlinear mirror (FDNLM) based on a BBO crystal for second harmonic generation and on a ... [more ▼]

High performance mode-locking of a pulsed Nd:YAG laser was achieved at 1.064 µm by using a frequency doubling nonlinear mirror (FDNLM) based on a BBO crystal for second harmonic generation and on a dichroïc mirror. A GaAs platelet was inserted into the laser cavity for providing a passive negative feedback. Pulses shorter than 15 ps were generated. The FDNLM has the following merits: photochemical stability, short response time, simplicity and applicability to a wide spectral range. The optical oscillator is the first element of a two-color laser system including two synchronously pumped optical parametric oscillators (OPO) built around a BBO and a LiNbO3 crystal, and tunable from 410 to 2600 nm and from 2.5 to 3.6 µm, respectively. [less ▲]

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See detailDevelopment of an all-solid-state pulsed picosecond laser system for nonlinear spectroscopy
Mani, A. A.; Jazmati, A. K.; Zidan, M. D. et al

in Physical Chemical News (2007), 36

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See detailDevelopment of an analytical method to detect metabolites of nitrofurans. Application to the study of furazolidone elimination in Vietnamese black tiger shrimp (Penaeus monodon)
Douny, Caroline ULg; Widart, Joëlle ULg; De Pauw, Edwin ULg et al

in Aquaculture (2013), 376-379

Nitrofurans, banned antibiotics in European Union (EU), have often been found in imported aquaculture products in the past and are still found nowadays according to the Rapid Alert System for Feed and ... [more ▼]

Nitrofurans, banned antibiotics in European Union (EU), have often been found in imported aquaculture products in the past and are still found nowadays according to the Rapid Alert System for Feed and Food (RASFF) of the European Commission. A quantitative method based on liquid chromatography coupled to isotopic dilution tandem mass spectrometry (LC–IDMS/MS) was developed for the determination of the residues of four nitrofuran antibiotic residues in shrimps. The experimental protocol consisted of an acid-catalysed release of protein-bound metabolites, followed by derivatisation with 2-nitrobenzaldehyde (NBA). Then, a double liquid–liquid extraction with ethyl acetate was performed before LC–IDMS/MS analysis by positive electrospray ionisation (ES+) with multiple reaction monitoring (MRM) of two transitions per compound. An “in-house” validation of the method for shrimp analysis was conducted according to the EU criteria for the analysis of veterinary drug residues in foods. The decision limits (CCalpha) were 0.08–0.36 µg kg -1 and the detection capabilities (CCbeta) were 0.12–0.61 µg kg-1, which are both below the minimum required performance limit (MRPL) set at 1 µg kg -1 by the EU. The developed method was applied to evaluate the elimination of furazolidone residues in shrimp muscles after a contamination experiment. After 28 days of decontamination, a concentration of 115 µg kg-1 of furazolidone metabolite 3-amino-2-oxazolidinone (AOZ) was still measured in shrimp muscle. [less ▲]

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See detailDevelopment of an analytical method to detect simultaneously bisphenols using a multiplexed surface-enhanced Raman scattering quantitative approach
De Bleye, Charlotte ULg; Dumont, Elodie ULg; Sacre, Pierre-Yves ULg et al

Poster (2014, May 15)

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 an analytical method to determine the composition of cryolitic baths used in the Hall-Heroult process, by Raman spectroscopy, at 1000°C
Malherbe, Cédric ULg

Doctoral thesis (2013)

Worldwide metallic aluminium production involves the Hall-Héroult process where the metal is electro-deposited from aluminium oxide solubilised in a molten NaF-AlF3-CaF2 mixture at around 950°C. The ... [more ▼]

Worldwide metallic aluminium production involves the Hall-Héroult process where the metal is electro-deposited from aluminium oxide solubilised in a molten NaF-AlF3-CaF2 mixture at around 950°C. The cryolitic melt is conveniently characterised by both the molar NaF/AlF3 ratio and the Al2O3 content. Nowadays the Hall-Héroult process remains the more economically efficient process even if it still suffers from a high consumption of energy. In particular the overvoltage required by the electrolysis is strongly dependent on the melt composition, especially regarding the Al2O3 content. Controlling the industrial baths composition during the process is therefore critical to reduce the energy loss. Unfortunately there is, up to now, no in situ direct analytical method to do so. Considering our experience in the study of such highly corrosive media by Raman spectroscopy, that technique has been applied to directly determine the melt composition. Three sets of reference spectra are considered in this study, each of them recorded with a different setup. The employed setups were developed to reach progressively, at the laboratory scale, a design that is suitable for a plant application. Eventually, a high quality spectrum can be recorded by the top of the melt, in less than 20 seconds. The employed apparatus is found to influence significantly the shape and quality of the spectra, and consequently their involvement in the quantification. A complex digital treatment of the spectral data acquired is necessary because all Raman bands of interest strongly overlap and some are situated close to the Rayleigh decay. Two main quantitative procedures for the melt composition determination are studied. The first one, the AutoAnalysis procedure, developed in the past and adapted here to the new data, gives reliable predictive results for both the NaF/AlF3 molar ratio and the alumina content. They can be determined with an absolute deviation of 0.06 molar ratio unit and 0.5 wt% respectively. However, the intensity normalisation, required for comparing the intensities of different spectra, relies on the Rayleigh decay that is likely to change with the experimental conditions in the plants. In our second quantitative procedure, the NormaAnalysis procedure, the intensity normalisation is based on the equilibria taking place in the melt. Since those equilibria do no differ with the experimental setup, the NormaAnalysis procedure can be imported to the industrial field. The predicted composition is also evaluated with a good precision: the NaF/AlF3 molar ratio and the alumina content can be determined with an absolute deviation of 0.08 cryolitic ratio unit and 0.3 wt% respectively. It is concluded that the composition of the melt can now be determined with our NormaAnalysis procedure, from a single Raman spectrum, recorded with a Raman apparatus exportable for an in situ measurement on the industrial cells. [less ▲]

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See detailDevelopment of an analytical method to determine the cryolitic bath composition by Raman spectroscopy
Malherbe, Cédric ULg; Gilbert, Bernard ULg

Poster (2010, April 23)

Since the end of the nineteenth century, metallic aluminium is produced by electro-deposition from a solution of aluminium oxide in cryolitic melts around 1000°C (Hall-Héroult process). The industrial ... [more ▼]

Since the end of the nineteenth century, metallic aluminium is produced by electro-deposition from a solution of aluminium oxide in cryolitic melts around 1000°C (Hall-Héroult process). The industrial melt is composed mostly of cryolite (Na3AlF6) and AlF3 and is characterized by the molar NaF/AlF3 ratio, named cryolitic ratio (CR). It turns out that the bath composition is critical: for instance, it has been shown that a small change in the Al2O3 content leads to a great change in the overvoltage required for the electrolysis. Therefore controlling the melt composition is very important in order to reduce the energy lost. Unfortunately no in situ analytical method allows studying the composition of the melt yet. Considering our experience in the study of such highly corrosive media by Raman spectroscopy and since the bath spectrum is function of both the CR and the Al2O3 content, we have proposed in the past to apply that technique to the direct determination of the melt composition. Despite the CR could be well evaluated in the lab, experimental problems however made the practical application difficult. The purpose of this presentation will be to show the new results obtained on an updated instrument: - Spectra are recorded in 20 s or less with a higher quality than before. - The previously developed home-made software was adapted to the updated instrument and various spectra analysis procedures are under study. - A procedure to prepare reference samples was also developed taking into account the homogeneity problems that have been met. - The slopes of the alumina calibration curves are depending on the bath CR, in confirmation of our previous results. - The new results are compared with the previous ones. It will be concluded that Raman spectroscopy is indeed becoming a suitable technique for developing an analytical method to determine the composition of industrial cryolitic melts. [less ▲]

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See detailDevelopment of an analytical strategy to measure major selenium-containing species in juvenile turtles (Trachemys scripta scripta) by SAX-HPLC-ICP MS
Far, Johann ULg; Dyc, Christelle; Das, Krishna ULg et al

Poster (2013, July)

Sea turtles are exposed to many environmental elements such as selenium (Se). Sea turtles are listed under the Red List of threatened species by the International Union for Conservation of Nature. It is ... [more ▼]

Sea turtles are exposed to many environmental elements such as selenium (Se). Sea turtles are listed under the Red List of threatened species by the International Union for Conservation of Nature. It is thus mandatory to use low-invasive tissue collection (skin, carapace, blood ) for estimating Se exposure in these highly protected turtles. For this purpose, a biological modal Trachemys scripta scripta (or slider turtle) was selected. For two months, juvenile turtles were dietary exposed to Se by spiking the food with Selenomethionine (SeMet) or Methionine as control groups. Individuals were sacrificed after different time of exposure and tissues (skin, liver, muscle, carapace and blood) collected to perform Se speciation and determine some biological endpoints. An analytical strategy was developed to cope with the very low amount of available sample. It is briefly consisting by reduction, alkylation and proteolysis of the entire freeze-dried tissues followed by sample clean-up using ultra-filtration membrane. Then anion exchange HPLC using salt and pH gradient was developed to prevent the introduction of organic solvents, which cause severe fooling of ICP MS and avoid ultra-trace analyses of sea water in routine analysis. This method successfully achieved the detection and quantification at ppm level of expected species (i.e SeMet, selenocysteine, inorganic Se) and also unknown species but their relative amounts were time and tissues dependent. [less ▲]

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See detailDevelopment of an animal experimental model to study the effects of levonorgestrel on the human endometrium.
Alvarez Gonzalez, Maria-Luz ULg; Galant, C.; Frankenne, F. et al

in Human Reproduction (2009), 24(3), 697-704

BACKGROUND: This study was designed to develop an animal model to test the response of endometrium to local progestin delivery. METHODS: Proliferative human endometrium was subcutaneously grafted in two ... [more ▼]

BACKGROUND: This study was designed to develop an animal model to test the response of endometrium to local progestin delivery. METHODS: Proliferative human endometrium was subcutaneously grafted in two groups of SCID mice that received, 2 days before, a subcutaneous estradiol (E2) pellet and, for half of them, an additional implant of levonorgestrel (LNG). Mice were sacrificed 1, 2, 3 or 4 weeks after endometrial implantation and grafts were histologically analysed. Proliferation, steroid hormone receptors, blood vessels and stromal decidualization in both groups (E2 and LNG) were immunohistologically evaluated and compared with proliferative endometrium and endometrium from women with an LNG intrauterine device. RESULTS: Grafts presented normal morphological endometrial characteristics. The expression of progesterone receptors was significantly decreased in glands and stroma of the LNG group as compared with the E2 group at all times. A significant decrease was also observed in the stromal expression of estrogen receptor- in the LNG group. At 4 weeks, the mean cross-sectional area of vessels was significantly higher after LNG treatment. CONCLUSIONS: These morphological and immunohistochemical characteristics are similar to those observed in women treated with local LNG. This mouse model might facilitate further investigations needed to understand the mechanisms responsible for the breakthrough bleeding frequently observed in progestin users. [less ▲]

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See detailDevelopment of an antidepressant compliance questionnaire
Demyttenaere, K.; Bruffaerts, R.; Albert, Adelin ULg et al

in Acta Psychiatrica Scandinavica (2004), 110(3), 201-207

Objective: The development of the Antidepressant Compliance Questionnaire (ADCQ), assessing patients' attitudes and beliefs on depression and antidepressants. Method: A 51-item questionnaire was applied ... [more ▼]

Objective: The development of the Antidepressant Compliance Questionnaire (ADCQ), assessing patients' attitudes and beliefs on depression and antidepressants. Method: A 51-item questionnaire was applied to 85 psychiatric out-patients with a DSM-IV diagnosis of major depressive disorder (MDD). This data set was used to assess psychometric properties of the ADCQ. The questionnaire was also applied to 272 primary care out-patients with MDD. Results: A principal component analysis revealed four dimensions with good internal consistency and acceptable test-retest reliability: 'perceived doctor-patient relationship', 'preserved autonomy', 'positive beliefs on antidepressants' and 'partner agreement', resulting in a final questionnaire comprising 33-items. Responses were independent from depression severity and patient age. The response patterns of both psychiatric and primary care patients are provided and illustrate the many erroneous beliefs on antidepressants. Conclusion: The ADCQ has good psychometric properties; further investigation should investigate whether this questionnaire is predictive of patient compliance. [less ▲]

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See detailDevelopment of an Environmental Information System for Odour using Citizen and Technology Innovative Sensors and Advanced Modelling
Uhrner, Ulrich; Grosso, gioavanna; Romain, Anne-Claude ULg et al

in CEUR Workshop Proceedings (2014), 1322

The challenge of OMNISCIENTIS is to develop a community based odour monitoring and information system to mitigate odour annoyance and to foster citizens’ participation in environmental governance. The ... [more ▼]

The challenge of OMNISCIENTIS is to develop a community based odour monitoring and information system to mitigate odour annoyance and to foster citizens’ participation in environmental governance. The core is an information system collecting various data of odour emissions obtained by electronic noses and other sensors, meteorological conditions and observations by citizens acting as human sensors. A specific odour dispersion model is developed to use all this information and provide immediate feedback to all stakeholders. This work presents the architecture of the environmental information system, some first results from odour monitoring and model development and validation. [less ▲]

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See detailDevelopment Of An Enzymatic Assay For The Determination Of Cellulose Bioavailability In Municipal Solid Waste
Rodriguez, Christian; Hiligsmann, Serge ULg; Ongena, Marc ULg et al

in Biodegradation (2005), 16(5), 415-422

As there is a constant need to assess the biodegradation potential of refuse disposed of in landfills, we have developed a method to evaluate the biodegradability of cellulosic compounds (cellulose and ... [more ▼]

As there is a constant need to assess the biodegradation potential of refuse disposed of in landfills, we have developed a method to evaluate the biodegradability of cellulosic compounds (cellulose and hemicellulose) in municipal solid waste. This test is based on the quantification of monosaccharids released after the hydrolysis of solid waste samples with an optimised enzyme preparation containing commercially available cellulases and hemicellulases. We show that the amounts of monosaccharids could be related to the biodegradability of the cellulosic material contained in the samples. This enzymatic cellulose degradation test was assayed on 26 samples originating from two Belgian landfills and collected at different depths. As results correlated well with those obtained with a classical biochemical methane potential assay, this new and rapid test is sufficiently reliable to evaluate cellulose bioavailability in waste samples. [less ▲]

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See detailDevelopment of an enzyme-linked immunosorbent assay for equine neutrophil elastase measurement in blood: Preliminary application to colic cases.
de la Rebière de Pouyade, Geoffroy ULg; Franck, Thierry ULg; Salciccia, Alexandra ULg et al

in Veterinary immunology and immunopathology (2010)

Equine neutrophil elastase (NE) is a protease released in inflammatory diseases and participating in tissue destruction. To measure NE in horse plasma to assess its role in pathological conditions, we ... [more ▼]

Equine neutrophil elastase (NE) is a protease released in inflammatory diseases and participating in tissue destruction. To measure NE in horse plasma to assess its role in pathological conditions, we purified elastase from equine neutrophils by a double step chromatography and obtained a pure protein of 27kDa, 4kDa smaller than the NE 2A previously purified (Scudamore et al., 1993; Dagleish et al., 1999), which was likely to be NE 2B. We developed an ELISA by using two specific polyclonal antibodies obtained from rabbit and guinea pig. The sandwich complex was detected using a secondary antibody conjugated to alkaline phosphatase. The ELISA showed good precision and accuracy, with intra- and inter-assay coefficients of variation below 10% for equine NE concentrations ranging from 1.875 to 60ng/ml. A stable plasma NE value, unaffected by the delay of centrifugation (over 4h), was obtained with plasma from EDTA anticoagulated blood. The mean value (+/-SEM) measured in 37 healthy horses was 32.53+/-4.6ng/ml. NE level in plasma of horses with colic at the time of admission was significantly higher than in healthy horses. Our results indicate that the ELISA technique we developed to measure plasmatic NE is a powerful tool for studying the role of elastase in equine inflammatory disease. In future, the application will be extended to other equine biological fluids. [less ▲]

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See detailDevelopment of an Enzyme-Linked Immunosorbent Assay for Serodiagnosis of Ringworm Infection in Cattle
Bagut, ET; Cambier, Ludivine ULg; Heinen, Marie-Pierre ULg et al

in Clinical and Vaccine Immunology (2013), 20(8), 1150-1154

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See detailDevelopment of an enzyme-linked immunosorbent assay for specific equine neutrophil myeloperoxidase measurement in blood
Franck, Thierry ULg; Grulke, Sigrid ULg; Deby-Dupont, Ginette et al

in Journal of Veterinary Diagnostic Investigation (2005), 17(5), 412-419

Equine inflammatory disease is accompanied by a neutrophil activation resulting in the release of granulocytic enzyme myeloperoxidase (MPO). To measure MPO in horse plasma as marker of neutrophil ... [more ▼]

Equine inflammatory disease is accompanied by a neutrophil activation resulting in the release of granulocytic enzyme myeloperoxidase (MPO). To measure MPO in horse plasma as marker of neutrophil activation, the authors purified equine neutrophil MPO and developed a specific enzyme immunoassay using 2 specific polyclonal antibodies obtained from rabbit (primary antibody) and guinea pig (secondary antibody). The sandwich complex "primary antibody-MPO-secondary antibody" was detected using a goat anti-guinea pig immunoglobulin antibody conjugated to alkaline phosphatase. The enzyme-linked immunosorbent assay (ELISA) showed good precision and accuracy, with intra- and interassay coefficients of variation below 10% for MPO concentrations ranging from 0.78 to 50 ng/ml. A stable plasma MPO value, unaffected by time elapsed between blood collection and centrifugation, was obtained with plasma from EDTA anticoagulated blood. The mean MPO value measured in 38 healthy horses was 181.80 +/- 64.74 ng/ml. In 20 horses suffering from obstruction of the large or small intestine, MPO concentrations measured at the time of arrival at the intensive care unit were significantly higher than mean normal value, ranging from 477.88 to 2,748.13 ng/ml. Work is in progress to apply this MPO ELISA technique to other biological fluids and other equine diseases. [less ▲]

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