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See detailDevelopment and validating procedure of a formula to calculate a minimum separation distance from piggeries and poultry facilities to sensitive receptors
Nicolas, Jacques ULg; Delva, Julien ULg; Cobut, Pierre et al

in Atmospheric Environment (2008), 42(30), 7087-7095

A specific formula to calculate separation distance from piggeries and poultry facilities to sensitive receptor is developed for Walloon Region, in Belgium. The paper briefly presents the main principles ... [more ▼]

A specific formula to calculate separation distance from piggeries and poultry facilities to sensitive receptor is developed for Walloon Region, in Belgium. The paper briefly presents the main principles of the formula and discusses more deeply the compatibility of the distance approach with odour units, odour rate and percentiles usually applied to assess the odour annoyance zones. A method of validation is presented and tested to adjust the different parameters of the formula to Belgian field reality. A total of 43 farms of which 21 piggeries and 22 poultry facilities are visited and, for each case, the distance calculated by the formula is compared to the one deduced from odour annoyance criterion (10 ou m-3 at 98th percentile). Validation work results in discussing the sensibility of different factors of the formula and especially in adjusting a fitting factor to match the absolute distances to real field annoyance impression. Conclusions show that both approaches - separation distance formula and percentile evaluation - are coherent. The validation method allows parameter adjustment but should need further refinements to examine separately piggeries and poultry facilities. [less ▲]

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See detailDevelopment and validation by accuracy profile of a method for the analysis of monoterpenes in indoor air by active sampling and thermal desorption-gas chromatography-mass spectrometry
Marlet, Christelle ULg; Lognay, Georges ULg

in Talanta (2010), 82(4), 1230-1239

The technique of thermal desorption (TD)-GC/MS was evaluated for the measurement of monoterpenes in indoor air. The validation strategy was intentionally oriented towards routine use and the reliability ... [more ▼]

The technique of thermal desorption (TD)-GC/MS was evaluated for the measurement of monoterpenes in indoor air. The validation strategy was intentionally oriented towards routine use and the reliability of the method rather than extreme performance. For this reason, validation by accuracy profile was chosen. The accuracy profile procedure, which is based on the concept of total error (bias + standard deviation), guarantees that a known proportion of future results obtained with the method will be within acceptance limits. For all the compounds tested in the present study, α-pinene, α-terpineol, β-pinene, d-limonene, Δ3-carene, camphene, 1,8-cineole, p-cymene, linalool, but not in the case of carvone, the accuracy profile procedure established that at least 95% of the future results obtained would be within the ±15% acceptance limits of the validated method over the whole defined concentration range. Other parameters, such as selectivity, recovery, repeatability, stability of the molecules of interest and the effect of temperature, were also determined. The performance of the described method was finally evaluated by the analysis of indoor air from new timber frame constructions. [less ▲]

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See detailDEVELOPMENT AND VALIDATION OF A LC-UV METHOD FOR THE DOSAGE OF A TRACER IN AN IMPROVED TRADITIONAL MEDICINE
Tshisekedi Tshibangu, Pascal; Kalenda Dibungi T., Pascal; Wauters, Jean-Noël ULg et al

Conference (2012, July)

According to World Health Organisation, 80% of the African populations use Improved Traditional Medicines (ITM) to threat several diseases. Even if some of these ITM are nowadays registered with local ... [more ▼]

According to World Health Organisation, 80% of the African populations use Improved Traditional Medicines (ITM) to threat several diseases. Even if some of these ITM are nowadays registered with local health authorities, the knowledge of their qualitative and quantitative composition still remains a challenge for ensuring health security of populations. In this context, an analytical method using liquid chromatography technique with UV detection was developed to allow the dosage of a tracer (major compound) in an ITM (syrup containing extract plants) registered in D.R. Congo by the “Centre de Recherche en Médecine Traditionnelle Améliorée” and marketed for use against malaria. For that purpose, a simple and rapid experimental plan considering a Plackett-Burman design was applied by testing simultaneously two significant factors, temperature of analytical column (T°) and gradient time (TG) for eluting acetonitrile (ACN) from 5% to 95%, while focusing on the separation of the tracer and an adjacent unknown compound (critical peak pairs). Suitable separation (resolution of 1.5) was obtained between these latter with T° of 15°C and TG of 60 min (20% to 65% of ACN). Prior to routine use, the analytical method was validated following the total error strategy described by the SFSTP guidelines and according to the ISO norm 17025:2005. Specificity/selectivity of the method was demonstrated by the absence of interference at the retention time of the major compound comparing to the syrup matrix. Very interesting results were observed for trueness (relative biases below 0.9%), for precision (RSD mostly below 2.2% for repeatability and time-different intermediate precision), for accuracy (beta tolerance intervals below 10% of the acceptance limits) and linearity. Finally, the method was applied to quantify the major compound in several batches of syrups ITM as well as for stability studies. [less ▲]

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See detailDevelopment and validation of a 3D kinematic-based method for determining gait events during overground walking
Boutaayamou, Mohamed ULg; Schwartz, Cédric ULg; Denoël, Vincent ULg et al

in IEEE International Conference on 3D Imaging (IC3D) (2014, December 09)

A new signal processing algorithm is developed for quantifying heel strike (HS) and toe-off (TO) event times solely from measured heel and toe coordinates during overground walking. It is based on a rough ... [more ▼]

A new signal processing algorithm is developed for quantifying heel strike (HS) and toe-off (TO) event times solely from measured heel and toe coordinates during overground walking. It is based on a rough estimation of relevant local 3D position signals. An original piecewise linear fitting method is applied to these local signals to accurately identify HS and TO times without the need of using arbitrary experimental coefficients. We validated the proposed method with nine healthy subjects and a total of 322 trials. The extracted temporal gait events were compared to reference data obtained from a force plate. HS and TO times were identified with a temporal accuracy ± precision of 0.3 ms ± 7.1 ms, and –2.8 ms ± 7.2 ms in comparison with reference data defined with a force threshold of 10 N. This algorithm improves the accuracy of the HS and TO detection. Furthermore, it can be used to perform stride-by-stride analysis during overground walking with only recorded heel and toe coordinates. [less ▲]

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See detailDevelopment and validation of a condenser three zones model
Cuevas, Cristian; Lebrun, Jean ULg; Lemort, Vincent ULg et al

in Applied Thermal Engineering (2009)

A general and simple ‘‘deterministic” model of a refrigeration condenser is presented. The model assumes that the condenser can be divided into three distinct zones on the refrigerant side: the vapour de ... [more ▼]

A general and simple ‘‘deterministic” model of a refrigeration condenser is presented. The model assumes that the condenser can be divided into three distinct zones on the refrigerant side: the vapour de-superheating zone, the two-phase zone and the sub-cooled liquid zone. The model inputs are the air supply temperature, the air mass flow rate, the refrigerant supply temperature (or the over-heating), the exhaust sub-cooling and the refrigerant mass flow rate. The model is able to identify the pressures and temperatures in each zone and the corresponding heat flows. The model also gives the geometrical repartition among the zones and the pressure drop on air-side. The condenser model is validated with a total of 183 tests. Testing conditions cover a very wide domain, including pressures up to 40 bars with refrigerant R134a. The model is able to predict with a probability of 95% the condenser supply pressure within a confidence interval of +0.5 and 0.1 bar. This means a condenser power confidence interval within 200 and +100 W, which is considered here as acceptable. Refrigerant pressure drop is predicted with a higher error, but it is attributed to measuring uncertainty. On the other hand, air pressure drop is predicted with a very poor accuracy. Undoubtedly, this is due to the friction factor correlation used in this study which is not the most adequate. Here a difference of 40% is obtained. [less ▲]

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See detailDevelopment and validation of a fully automated LC method for the determination of cloxacillin in human plasma using anion exchancre restricted access material for sample clean-up
Rbeida, O.; Chiap, Patrice ULg; Lubda, D. et al

in Journal of Pharmaceutical & Biomedical Analysis (2005), 36(5), 961-968

In the framework of a preliminary investigation on the plasma profile of cloxacillin after oral administration, a simple and rapid LC method was developed for the direct determination of this compound in ... [more ▼]

In the framework of a preliminary investigation on the plasma profile of cloxacillin after oral administration, a simple and rapid LC method was developed for the direct determination of this compound in human plasma. The on-line sample clean-up was carried out using a weak anion exchanger (diethylaminoethyl groups) as restricted access material (RAM). The effects of the washing liquid pH, the ionic strength and the addition of organic modifier to the washing liquid were studied in order to obtain an efficient sample clean-up and a high recovery of cloxacillin. The separation was achieved on octadecylsilica stationary phase using a mobile phase consisting in a mixture of phosphate buffer (pH 4.0; 25 mM) and acetonitrile (72:28, v/v). The UV detection was performed at 215 nm. The most appropriate regression model of the response function as well as the limit of quantitation (LOQ) were first selected during the pre-validation step. These criteria were then assessed during the formal validation step. The LOQ was 50 ng/ml. The method was also validated with respect to analyte recovery, precision. trueness, accuracy and linearity. Finally, it was successfully applied for the analysis of the first plasma samples obtained from patients, having taken an oral dose of 500 mg cloxacillin. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailDevelopment and validation of a high performance liquid chromatographic method for quantitative determination of aporphine alkaloids from different samples of Cassytha filiformis
Stevigny, C.; Wautier, M. C.; Jiwan, J. L. H. et al

in Planta Medica (2004), 70(8), 764-770

A sensitive and accurate procedure based on an alkaloid extraction coupled to an HPLC-UV-MS determination has been developed for the separation and quantification of the major aporphines in Cassytha ... [more ▼]

A sensitive and accurate procedure based on an alkaloid extraction coupled to an HPLC-UV-MS determination has been developed for the separation and quantification of the major aporphines in Cassytha filiformis. The extraction step and the liquid chromatography conditions were optimized in order to improve the selectivity of the method. The HPLC mobile phase consisted of a mixture of water containing 10 mM ammonium acetate adjusted to pH 3 with acetic acid-acetonitrile (90: 10, v/v) (A) and acetonitrile (B) used in a gradient mode (0 to 40%). The stationary phase was an RP-select B (5 mum) column. The method was completely validated using cassythine, one of the major aporphines in our samples, as reference standard and successfully applied to the determination of these pharmacologically interesting aporphines in seven different batches of C. filiformis. The detection and quantitation limits of cassythine were found to be 13 and 20 mug/mL, respectively. The results showed variations in the total alkaloid content in samples from 0.11 to 0.43%. [less ▲]

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See detailDevelopment and validation of a high-performance liquid chromatographic method for the determination of cyproterone acetate in human skin
Henry de Hassonville, Sandrine; Chiap, Patrice ULg; Liégeois, Jean-François ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2004), 36(1), 133-143

In the framework of a preliminary study on the transdermal penetration of cyproterone acetate (CPA), a simple and rapid procedure involving an extraction step coupled to a HPLC-UV determination has been ... [more ▼]

In the framework of a preliminary study on the transdermal penetration of cyproterone acetate (CPA), a simple and rapid procedure involving an extraction step coupled to a HPLC-UV determination has been developed for the separation and quantification of CPA in the two main skin layers-epidermis and dermis-after local application. The separation of epidermis and dermis layers was carefully carried out by means of a sharp spatula after skin immersion in heated water at 65 degrees C. The two skin layers were then treated separately according to the same process: (1) sample homogenization by vibration after freezing with liquid nitrogen in a Mikro-Dismembrator; (2) CPA extraction with methanol after addition of the internal standard (betamethasone dipropionate); (3) centrifugation; (4) evaporation of a supernatant aliquot; (5) dissolution of the dry residue in methanol and addition of water; (6) centrifugation; (7) injection of a supernatant aliquot into the HPLC system. The separation was achieved on octadecylsilica stationary phase using a mobile phase consisting in a mixture of acetonitrile and water (40:60 (v/v)). The method was then validated using a new approach based on accuracy profiles over a CPA concentration range from 33 to 667 ng/ml for each skin layer. Finally, the method was successfully applied to the determination of CPA to several skin samples after topical application of different gel formulations containing CPA. [less ▲]

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See detailDevelopment and validation of a LC method for the enantiomeric purity determination of S-ropivacaine in a pharmaceutical formulation using a recently commercialized cellulose-based chiral stationary phase and polar non-aqueous mobile phase.
Dossou, Katina Sourou Sylvestre ULg; CHIAP, Patrice ULg; Servais, Anne-Catherine ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2011), 54(4), 687-93

Ropivacaine is the first enantiomerically pure long-acting local anaesthetic used for surgical anaesthesia and post-operative pain relief. A liquid chromatographic (LC) method using acetonitrile as the ... [more ▼]

Ropivacaine is the first enantiomerically pure long-acting local anaesthetic used for surgical anaesthesia and post-operative pain relief. A liquid chromatographic (LC) method using acetonitrile as the main solvent and cellulose tris(4-chloro-3-methylphenylcarbamate) coated on silica as chiral stationary phase was successfully developed and applied for the enantiomeric purity determination of S-ropivacaine in a pharmaceutical formulation (Naropin((R))). The key role played by the acidic additive (trifluoroacetic acid or formic acid) in the enantioseparation of basic drugs in these LC systems was demonstrated by the reversal of ropivacaine enantiomers elution order observed when both acids were compared. In order to elute the enantiomeric impurity (R-ropivacaine) before S-ropivacaine, formic acid (FA) was selected. The temperature and the percentages of acidic additive and hexane in the mobile phase were found to significantly influence the retention and resolution of these enantiomers. The optimized mobile phase consisted of ACN/0.1% DEA/0.2% FA/5% hexane (v/v/v/v). The temperature was set at 35 degrees C to avoid the interference from a peak system related to the presence of water in the sample on ropivacaine enantiomers. The LC method was then fully validated applying the strategy based on total measurement error and accuracy profiles. The accuracy profile obtained by linear regression after square root transformation was selected, the acceptance limits being settled at +/-10% for the intended use of this analytical method. The relative bias was lower than 1.5%, while the RSD values for repeatability and intermediate precision were both below 1.0%. The limit of detection (LOD) and the limit of quantification (LOQ) were found to be about 0.2 and 1.0 mug/mL, respectively, corresponding to 0.02 and 0.1% of the enantiomeric impurity in S-ropivacaine. [less ▲]

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See detailDevelopment and validation of a liquid chromatographic method for the stability study of a pharmaceutical formulation containing voriconazole using cellulose tris(4-chloro-3-methylphenylcarbamate) as chiral selector and polar organic mobile phases.
Servais, Anne-Catherine ULg; Moldovan, Radu-Cristian ULg; Farcas, Elena ULg et al

in Journal of chromatography. A (2014), 1363

The ophthalmic solution of voriconazole, i.e. (2R,3S)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-y l)butan-2-ol, made from an injection formulation which also contains ... [more ▼]

The ophthalmic solution of voriconazole, i.e. (2R,3S)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-y l)butan-2-ol, made from an injection formulation which also contains sulfobutylether-beta-cyclodextrin sodium salt as an excipient (Vfend((R))), is used for the treatment of fungal keratitis. A liquid chromatographic (LC) method using polar organic mobile phase and cellulose tris(4-chloro-3-methylphenylcarbamate) coated on silica as chiral stationary phase was successfully developed to evaluate the chiral stability of the ophthalmic solution. The percentage of methanol (MeOH) in the mobile phase containing acetonitrile (ACN) as the main solvent significantly influenced the retention and resolution of voriconazole and its enantiomer ((2S,3R)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1- yl)butan-2-ol). The optimized mobile phase consisted of ACN/MeOH/diethylamine/trifluoroacetic acid (80/20/0.1/0.1; v/v/v/v). The method was found to be selective not only regarding the enantiomer of voriconazole but also regarding the specified impurities described in the monograph from the European Pharmacopoeia. The LC method was then fully validated applying the strategy based on total measurement error and accuracy profiles. Under the selected conditions, the determination of 0.1% of voriconazole enantiomer could be performed. Finally, a stability study of the ophthalmic solution was conducted using the validated LC method. [less ▲]

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See detailDevelopment and Validation of a Markov Microsimulation Model for the Economic Evaluation of Treatments in Osteoporosis.
Hiligsmann, Mickaël ULg; Ethgen, Olivier ULg; Bruyère, Olivier ULg et al

in Value in Health (2009), 12(5), 687-696

ABSTRACT Objective: Markov models are increasingly used in economic evaluations of treatments for osteoporosis. Most of the existing evaluations are cohort-based Markov models missing comprehensive memory ... [more ▼]

ABSTRACT Objective: Markov models are increasingly used in economic evaluations of treatments for osteoporosis. Most of the existing evaluations are cohort-based Markov models missing comprehensive memory management and versatility. In this article, we describe and validate an original Markov microsimulation model to accurately assess the cost-effectiveness of prevention and treatment of osteoporosis. Methods: We developed a Markov microsimulation model with a lifetime horizon and a direct health-care cost perspective. The patient history was recorded and was used in calculations of transition probabilities, utilities, and costs. To test the internal consistency of the model, we carried out an example calculation for alendronate therapy. Then, external consistency was investigated by comparing absolute lifetime risk of fracture estimates with epidemiologic data. Results: For women at age 70 years, with a twofold increase in the fracture risk of the average population, the costs per quality-adjusted life-year gained for alendronate therapy versus no treatment were estimated at Euro 9105 and Euro 15,325, respectively, under full and realistic adherence assumptions. All the sensitivity analyses in terms of model parameters and modeling assumptions were coherent with expected conclusions and absolute lifetime risk of fracture estimates were within the range of previous estimates, which confirmed both internal and external consistency of the model. Conclusion: Microsimulation models present some major advantages over cohort-based models, increasing the reliability of the results and being largely compatible with the existing state of the art, evidence-based literature. The developed model appears to be a valid model for use in economic evaluations in osteoporosis. [less ▲]

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See detailDevelopment and validation of a morphologic obstructive sleep apnea prediction score: The DES-OSA score
Deflandre, E.; Degey, S.; Brichant, Jean-Francois ULg et al

in Anesthesia and Analgesia (2016), 122(2), 363-372

BACKGROUND: Obstructive sleep apnea (OSA) is a common and underdiagnosed entity that favors perioperative morbidity. Several anatomical characteristics predispose to OSA. We developed a new clinical score ... [more ▼]

BACKGROUND: Obstructive sleep apnea (OSA) is a common and underdiagnosed entity that favors perioperative morbidity. Several anatomical characteristics predispose to OSA. We developed a new clinical score that would detect OSA based on the patient's morphologic characteristics only. METHODS: Patients (n = 149) scheduled for an overnight polysomnography were included. Their morphologic metrics were compared, and combinations of them were tested for their ability to predict at least mild, moderate-to-severe, or severe OSA, as defined by an apnea-hypopnea index (AHI) >5, >15, or >30 events/h. This ability was calculated using Cohen κ coefficient and prediction probability. RESULTS: The score with best prediction abilities (DES-OSA score) considered 5 variables: Mallampati score, distance between the thyroid and the chin, body mass index, neck circumference, and sex. Those variables were weighted by 1, 2, or 3 points. DES-OSA score >5, 6, and 7 were associated with increased probability of an AHI >5, >15, or >30 events/h, respectively, and those thresholds had the best Cohen κ coefficient, sensitivities, and specificities. Receiver operating characteristic curve analysis revealed that the area under the curve was 0.832 (95% confidence interval [CI], 0.762-0.902), 0.805 (95% CI, 0.734-0.876), and 0.834 (95% CI, 0.757-0.911) for DES-OSA at predicting an AHI >5, >15, and >30 events/h, respectively. With the aforementioned thresholds, corresponding sensitivities (95% CI) were 82.7% (74.5-88.7), 77.1% (66.9-84.9), and 75% (61.0-85.1), and specificities (95% CI) were 72.4% (54.0-85.4), 73.2% (60.3-83.1), and 76.9% (67.2-84.4). Validation of DES-OSA performance in an independent sample yielded highly similar results. CONCLUSIONS: DES-OSA is a simple score for detecting OSA patients. Its originality relies on its morphologic nature. Derived from a European population, it may prove useful in a preoperative setting, but it has still to be compared with other screening tools in a general surgical population and in other ethnic groups. © 2016 International Anesthesia Research Society. [less ▲]

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See detailDevelopment and validation of a multi-residue method for pesticide determination in honey using on-column liquid-liquid extraction and liquid chromatography-tandem mass spectrometry
PIRARD, Catherine ULg; Widart, Joëlle ULg; Nguyen, Bach Kim ULg et al

in Journal of Chromatography. A (2007), 1152(1-2), 116-123

We report on the development and validation under ISO 17025 criteria of a multi-residue confirmatory method to identify and quantify 17 widely chemically different pesticides (insecticides: Carbofuran ... [more ▼]

We report on the development and validation under ISO 17025 criteria of a multi-residue confirmatory method to identify and quantify 17 widely chemically different pesticides (insecticides: Carbofuran, Methiocarb, Pirimicarb, Dimethoate, Fipronil, Imidacloprid; herbicides: Amidosulfuron, Rimsulfuron, Atrazine, Simazine, Chloroturon, Linuron, Isoxaflutole, Metosulam; fungicides: Diethofencarb) and 2 metabolites (Methiocarb sulfoxide and 2-Hydroxytertbutylazine) in honey. This method is based on an on-column liquid liquid extraction (OCLLE) using diatomaceous earth as inert solid support and liquid chromatography (LC) coupled to mass spectrometry (MS) operating in tandem mode (MS/MS). Method specificity is ensured by checking retention time and theoretical ratio between two transitions from a single precursor ion. Linearity is demonstrated all along the range of concentration that was investigated, from 0.1 to 20 ng g(-1) raw honey, with correlation coefficients ranging from 0.921 to 0.999, depending on chemicals. Recovery rates obtained on home-made quality control samples are between 71 and 90%, well above the range defined by the EC/657/2002 document, but in the range we had fixed to ensure proper quantification, as levels found in real samples could not be corrected for recovery rates. Reproducibility is found to be between 8 and 27%. Calculated CC alpha and CC beta (0.0002-0.943 mg g(-1) for CC alpha, and 0.0002-1.232 ng g(-1) for CCP) show the good sensitivity attained by this rnulti-residue analytical method. The robustness of the method has been tested in analyzing more than 100 raw honey samples collected from different areas in Belgium, as well as some wax and bee samples, with a slightly adapted procedure. (C) 2007 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 167 (33 ULg)