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See detailAutomated analysis of enzyme inactivation phenomena. Application to beta-lactamases and DD-peptidases.
De Meester, Fabien; Joris, Bernard ULg; Reckinger, Georges et al

in Biochemical Pharmacology (1987), 36

In the presence of a reporter substrate, the progressive inactivation of an enzyme was easily studied by directly transmitting absorbance readings to a microcomputer. Pseudo-first order rate constants as ... [more ▼]

In the presence of a reporter substrate, the progressive inactivation of an enzyme was easily studied by directly transmitting absorbance readings to a microcomputer. Pseudo-first order rate constants as high as 0.3 sec-1 were rapidly and accurately measured. When utilization of the reporter substrate did not exceed 10%, the rate of the reaction (vt) could be considered as proportional to the active enzyme concentration at any time during the analysis and the decrease of vt was first order with time. This simple method was used to follow the inactivation of beta-lactamases (EC 3.5.2.6) by various physical and chemical agents. When a large proportion (30-80%) of reporter substrate was destroyed, a correction was introduced to account for the corresponding decrease of its rate of utilization. This enabled experiments to be performed with a DD-peptidase and a substrate exhibiting a low delta epsilon upon hydrolysis. For the first time, the inactivation of a penicillin-sensitive enzyme by a beta-lactam could be continuously and directly observed. Finally, the method was extended to the study of hysteresis phenomena. [less ▲]

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See detailAutomated characterisation of intergrowth textures in mineral particles. A case study
Perez-Barnuevo, Laura; Pirard, Eric ULg; Castroviejo, Ricardo

in Minerals Engineering (2013)

The characterisation of mineral texture has been a major concern for process mineralogists, as liberation characteristics of the ores are intimately related to the mineralogical texture. While a great ... [more ▼]

The characterisation of mineral texture has been a major concern for process mineralogists, as liberation characteristics of the ores are intimately related to the mineralogical texture. While a great effort has been done to automatically characterise texture in unbroken ores, the characterisation of textural attributes in mineral particles is usually descriptive. However, the quantitative characterisation of texture in mineral particles is essential to improve and predict the performance of minerallurgical processes (i.e. all the processes involved in the liberation and separation of the mineral of interest) and to achieve a more accurate geometallurgical model. Driven by this necessity of achieving a more complete characterisation of textural attributes in mineral particles, a methodology has been recently developed to automatically characterise the type of intergrowth between mineral phases within particles by means of digital image analysis. In this methodology, a set of minerallurgical indices has been developed to quantify different mineralogical features and to identify the intergrowth pattern by discriminant analysis. The paper shows the application of the methodology to the textural characterisation of chalcopyrite in the rougher concentrate of the Kansanshi copper mine (Zambia). In this sample, the variety of intergrowth patterns of chalcopyrite with the other minerals has been used to illustrate the methodology. The results obtained show that the method identifies the intergrowth type and provides quantitative information to achieve a complete and detailed mineralogical characterisation. Therefore, the use of this methodology as a routinely tool in automated mineralogy would contribute to a better understanding of the ore behaviour during liberation and separation processes. [less ▲]

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See detailAutomated Defect Detection Algorithm Applied to Shearography in Composites
Vandenrijt, Jean-François ULg; Georges, Marc ULg

in Osten, Wolfgang (Ed.) Fringe 2013 (2014)

The aeronautic industry is progressively introducing composite material in its products. Nowadays the fabrication begins to be mature, but huge efforts remains to be done on the experimental validation of ... [more ▼]

The aeronautic industry is progressively introducing composite material in its products. Nowadays the fabrication begins to be mature, but huge efforts remains to be done on the experimental validation of these materials. More specifically, these composite materials introduce new type of defects (such as delamination, glue defects…) which need to be detected during the fabrication and maintenance to prevent failures. Moreover, the widespread use of these materials impose to the future detection instruments to be cheap, robust and easy to manipulate by non-specialists. Currently shearography is widely used for the detection of defects in the composite material. It is cheap, and relatively robust and flexible, but requires special qualification to interpret the shearograms and identify the defects. Therefore, efforts need to be carried to ease the interpretation of stereographic results for non-specialist of the technique. For this, we propose to automate the identification of defects in shearograms by the development of specific algorithms. In this paper, we present an innovative algorithm which realizes this operation. The process inspects the wrapped phase map obtained to identify high local fringe density. These potential detects are then analyzed and selected based on a set of parameter criteria such as dimensions, shape, and detection threshold. Successful results obtained on thermally solicited composite sample observed in industrial conditions are shown. We also discuss the limitations and perspective of this approach. [less ▲]

Detailed reference viewed: 34 (10 ULg)
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See detailAutomated determination of acyclovir in human plasma using solid phase extraction and liquid chromatography
Chiap, Patrice ULg; Planck, I.; Evrard, Brigitte ULg et al

in Journal de Pharmacie de Belgique (1998), 53

Detailed reference viewed: 17 (1 ULg)
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See detailAutomated determination of camazepam in human plasma by solid phase extraction coupled to HPLC
Hubert, Philippe ULg; Chiap, Patrice ULg; Ceccato, Attilio ULg et al

in Journal de Pharmacie de Belgique (1995), 50

Detailed reference viewed: 6 (2 ULg)
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See detailAutomated determination of drugs in ibological fluids using solid-phase extraction coupled to HPLC
Hubert, Philippe ULg

in Dissertation abstracts international (1995)

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See detailAutomated determination of pirlindole enantiomers in plasma by on-line coupling of a pre-column packed with restricted access material to a chiral liquid chromatographic column
Chiap, Patrice ULg; Ceccato, Attilio ULg; Gora, R. et al

in Journal of Pharmaceutical & Biomedical Analysis (2002), 27(3-4), 447-455

A fully automated liquid chromatographic method has been developed for the determination of the enantiomers of pirlindole, an antidepressant drug, in human plasma. The method is based on the use of a pre ... [more ▼]

A fully automated liquid chromatographic method has been developed for the determination of the enantiomers of pirlindole, an antidepressant drug, in human plasma. The method is based on the use of a pre-column packed with restricted access material (RAM) (LiChrospher ADS RP-4) for sample clean-up coupled to a column containing a cellulose tris-(3,5-dimethylphenylcarbamate) based chiral stationary phase (Chiralcel OD-R) for the separation and quantitative analysis of pirlindole enantiomers. A 50-microl plasma volume was injected directly onto the pre-column using a mixture of phosphate buffer (pH 5.0) and methanol (97:3; v/v) as washing liquid. By rotation of a switching valve, the analytes were then eluted in the back-flush mode with the LC mobile phase. A complete separation of pirlindole enantiomers was obtained in 22 min on the Chiralcel OD-R column, using a mobile phase made of a mixture of phosphate buffer (pH 5.0) containing 50 mM sodium perchlorate and acetonitrile (65:35; v/v). The flow-rate was 0.6 ml/min and the analytes were detected fluorometrically using 295 and 340 nm as excitation and emission wavelengths, respectively. The method was then validated and was found to be linear in the 2.5-200 ng/ml range. The limit of detection was lower than 1 ng/ml. Repeatability and intermediate precision at a concentration of 50 ng/ml were about 1.5 and 3.5%, respectively. [less ▲]

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See detailAutomated determination of sulfadimidine in ovine plasma by solid phase extraction and HPLC
Hubert, Philippe ULg; Evrard, Brigitte ULg; Delattre, Luc ULg et al

in Journal de Pharmacie de Belgique (1992), 47

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See detailAutomated Determination of Tramadol Enantiomers in Human Plasma Using Solid-Phase Extraction in Combination with Chiral Liquid Chromatography
Ceccato, Attilio ULg; Chiap, Patrice ULg; Hubert, Philippe ULg et al

in Journal of Chromatography. B : Biomedical Sciences and Applications (1997), 698(1-2), 161-70

A sensitive and automated method for the separation and individual determination of tramadol enantiomers in plasma has been developed using solid-phase extraction (SPE) on disposable extraction cartridges ... [more ▼]

A sensitive and automated method for the separation and individual determination of tramadol enantiomers in plasma has been developed using solid-phase extraction (SPE) on disposable extraction cartridges (DECs) in combination with chiral liquid chromatography (LC). The SPE operations were performed automatically by means of a sample processor equipped with a robotic arm (ASPEC system). The DEC filled with ethyl silica (50 mg) was first conditioned with methanol and phosphate buffer, pH 7.4. A 1.0-ml volume of plasma was then applied on the DEC. The washing step was performed with the same buffer. The analytes were eluted with 0.15 ml of methanol, and 0.35 ml of phosphate buffer, pH 6.0, containing sodium perchlorate (0.2 M) were added to the extract before injection into the LC system. The enantiomeric separation of tramadol was achieved using a Chiralcel OD-R column containing cellulose tris-(3,5-dimethylphenylcarbamate) as chiral stationary phase. The mobile phase was a mixture of phosphate buffer, pH 6.0, containing sodium perchlorate (0.2 M) and acetonitrile (75:25). The mobile-phase pH and the NaClO4 concentration were optimized with respect to enantiomeric resolution. The method developed was validated. Recoveries for both enantiomers of tramadol were about 100%. The method was found to be linear in the 2.5-150 ng/ml concentration range [r2=0.999 for (+)- and (-)-tramadol]. The repeatability and intermediate precision at a concentration of 50 ng/ml were 6.5 and 8.7% for (+)-tramadol and 6.1 and 7.6% for (-)-tramadol, respectively. [less ▲]

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See detailAutomated Determination of Verapamil and Norverapamil in Human Plasma with on-Line Coupling of Dialysis to High-Performance Liquid Chromatography and Fluorometric Detection
Ceccato, Attilio ULg; Chiap, Patrice ULg; Hubert, Philippe ULg et al

in Journal of Chromatography. A (1996), 750(1-2), 351-60

A fully automated method for the simultaneous determination of verapamil and its main metabolite norverapamil in human plasma is described. This method is based on on-line sample preparation using ... [more ▼]

A fully automated method for the simultaneous determination of verapamil and its main metabolite norverapamil in human plasma is described. This method is based on on-line sample preparation using dialysis followed by clean-up and enrichment of the dialysate on a precolumn and subsequent HPLC analysis with fluorometric detection. All sample handling operations were performed automatically by a sample processor equipped with a robotic arm (ASTED system). The plasma samples were dialysed on a cellulose acetate membrane (cut-off: 15 kD) and the dialysate was purified and enriched on a short pre-column filled with cyanopropyl silica. Before starting dialysis, this trace enrichment column (TEC) was first conditioned with the HPLC mobile phase and then with pH 3.0 acetate buffer. 370 microliters of plasma sample spiked with the internal standard (gallopamil) were dialysed in the static-pulsed mode. The solution at the donor side was pH 3.0 acetate buffer containing Triton X-100 while the acceptor solution was made of the same acetate buffer. When dialysis was discontinued, the analytes were desorbed from the TEC by the HPLC mobile phase and transferred to the C18 analytical column by means of a switching valve. This mobile phase consisted of a mixture of acetonitrile, pH 3.0 acetate buffer and 2-aminoheptane. The influence of different parameters of the dialysis process on the recovery of verapamil and norverapamil has been studied. The effect of the volume, the aspirating and dispensing flow-rates of the dialysis solution has been investigated. The recoveries of verapamil and norverapamil in plasma were close to 75% and the limits of quantification were 5 ng/ml for both analytes. The method was found to be linear in the concentration range from 5 to 500 ng/ml (r2: 0.9996 for both analytes). The intra-day and inter-day reproducibilities at a concentration of 100 ng/ml were 2.3% and 5.6% for verapamil and 1.7% and 5.1% for norverapamil, respectively. [less ▲]

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See detailAutomated EEG entropy measurements in coma, vegetative state/unresponsive wakefulness syndrome and minimally conscious state
Gosseries, Olivia ULg; Schnakers, Caroline ULg; LEDOUX, Didier ULg et al

in Functional Neurology (2011)

Monitoring the level of consciousness in brain injured patients with disorders of consciousness is crucial as it provides diagnostic and prognostic information. Behavioral assessment remains the gold ... [more ▼]

Monitoring the level of consciousness in brain injured patients with disorders of consciousness is crucial as it provides diagnostic and prognostic information. Behavioral assessment remains the gold standard for assessing consciousness but previous studies have shown a high rate of misdiagnosis. This study aimed to investigate the usefulness of electroencephalography (EEG) entropy measurements in differentiating unconscious (coma or vegetative) from minimally conscious patients. Left fronto-temporal EEG recordings (10-minute resting state epochs) were prospectively obtained in 56 patients and 16 age-matched healthy volunteers. Patients were assessed in the acute (≤1 month post-injury;n=29) or chronic (>1 month post-injury; n=27) stage. The etiology was traumatic in 23 patients. Automated online EEG entropy calculations (providing an arbitrary value ranging from 0 to 91) were compared with behavioral assessments (Coma Recovery Scale-Revised) and outcome. EEG entropy correlated with Coma Recovery Scale total scores (r=0.49). Mean EEG entropy values were higher in minimally conscious (73±19; mean and standard deviation) than in vegetative/unresponsive wakefulness syndrome patients (45±28). Receiver operating characteristic analysis revealed an entropy cut-off value of 52 differentiating acute unconscious from minimally conscious patients (sensitivity 89% and specificity 90%). In chronic patients, entropy measurements offered no reliable diagnostic information. EEG entropy measurements did not allow prediction of outcome. User-independent time-frequency balanced spectral EEG entropy measurements seem to constitute an interesting diagnostic – albeit not prognostic – tool for assessing neural network complexity in disorders of consciousness in the acute setting. Future studies are needed before using this tool in routine clinical practice, and these should seek to improve automated EEG quantification paradigms in order to reduce the remaining false negative and false positive findings. [less ▲]

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See detailAutomated extraction and clean-up system for liquid materials
Focant, Jean-François ULg; De Pauw, Edwin ULg

Scientific conference (2004, April)

Detailed reference viewed: 2 (0 ULg)
See detailAutomated extraction and clean-up system for solid materials
Focant, Jean-François ULg; De Pauw, Edwin ULg

Scientific conference (2004, April)

Detailed reference viewed: 1 (0 ULg)