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See detailDetermination of Six Water-Soluble Vitamins in a Pharmaceutical Formulation by Capillary Electrophoresis
Fotsing, Lucas ULg; Fillet, Marianne ULg; Bechet, I. et al

in Journal of Pharmaceutical & Biomedical Analysis (1997), 15(8), 1113-23

A method was developed for the quantitative analysis of six water-soluble vitamins (thiamine, nicotinamide, riboflavine, pyridoxine, ascorbic acid and pantothenic acid) in a pharmaceutical formulation ... [more ▼]

A method was developed for the quantitative analysis of six water-soluble vitamins (thiamine, nicotinamide, riboflavine, pyridoxine, ascorbic acid and pantothenic acid) in a pharmaceutical formulation, using free solution capillary zone electrophoresis (CZE) in uncoated fused silica capillaries and UV detection. The influence of different parameters, such as the nature of the buffer anionic component and buffer concentration on the CZE separation of vitamins was investigated using four vitamins of the B group as model compounds. A good compromise between resolution, analysis time and analyte stability was obtained by use of a 50 mM borax buffer of pH 8.5. This CZE method was found to be very useful for the separation of more complex samples, a mixture of ten water-soluble vitamins being completely resolved in about 10 min. However, cyanocobalamine could not be separated from nicotinamide in this CZE system, the two compounds being in uncharged form at the pH used. These two compounds could easily be resolved by micellar electrokinetic chromatography (MEKC), the anionic surfactant dodecylsulfate being added to the running buffer at 25 mM concentration. In the pharmaceutical formulation, some excipients were found to be adsorbed to the capillary surface, giving rise to a progressive decrease of the electroosmotic flow and consequently to a simultaneous increase of analyte migration times. A capillary wash with sodium hydroxide had to be made between successive runs in order to minimize these effects. Good results with respect to linearity, precision and accuracy were obtained in the concentration range studied for the six vitamins, using nicotinic acid as internal standard. [less ▲]

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See detailDetermination of solid fat content (SFC) of binary fat blends and use of these data to predict SFC of selected ternary fat blends containing low-erucic rapeseed oil
Danthine, Sabine ULg; Deroanne, Claude ULg

in Journal of the American Oil Chemists' Society (2006), 83(7), 571-581

Several oils and fats often used for the industrial preparation of European shortenings were blended in binary systems. The equilibrium (after 48 h at 15 degrees C) solid fat contents (SFC; determined by ... [more ▼]

Several oils and fats often used for the industrial preparation of European shortenings were blended in binary systems. The equilibrium (after 48 h at 15 degrees C) solid fat contents (SFC; determined by pulsed NMR spectroscopy) were measured and plotted against blend composition. SFC of the blends resulted from the SFC of each fat for the considered temperature as well as the type of interaction existing between those fats (namely, ideal behavior, monotectic interaction, eutectic interaction, and so on). The type of relationship fitted was dependent on the kind of interaction: Linear relationships were found for total compatibility between fats, and polynomial-type (order 2) relationships were found for fats exhibiting incompatibility. Some corresponding ternary oils and fats blends were also prepared and analyzed. Selected relationships (regression equations of the fitted curves) obtained for binary blends were combined in order to calculate the SFC of the corresponding ternary blends. Experimental values were generally close to predicted ones. The representation of SFC as a function of composition is interesting as it allows one to determine rapidly and easily the type of molecular interaction between two fats and also to determine equations that can be. combined to calculate easily the SFC of corresponding ternary blends crystallized in the same way with a good accuracy. The texture (hardness) of several binary and ternary blends was also measured. The combination of the results obtained for SFC with the results obtained for the hardness of binary blends allows the prediction of the hardness of a corresponding ternary blend under the same conditions. [less ▲]

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See detailDetermination of solidification parameters used for the prediction of the thixoformability of several steel alloys
Lecomte-Beckers, Jacqueline ULg; Rassili, Ahmed ULg; Robelet, Marc et al

in Solid State Phenomena (2006), 116-117

This paper focuses on the liquid fraction curves of several steels and the correlation between liquid fraction, temperature and heating rate. The work has been performed along two main axes. First, the ... [more ▼]

This paper focuses on the liquid fraction curves of several steels and the correlation between liquid fraction, temperature and heating rate. The work has been performed along two main axes. First, the solid fraction versus temperature has been obtained experimentally by differential scanning calorimetry (DSC), limited to low heating rates. Then, a shift of the liquid fraction curves has been noticed at high industrial heating rates. The quantification of this effect could not be carried out by DSC and required the elaboration of another experimental device. [less ▲]

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See detailDetermination of Stress and Strain Fields in Cast and Heat Treated Bimetallic Rolling Mill Rolls
Neira Torres, Ingrid; Tchuindjang, Jérôme Tchoufack ULg; Sinnaeve, Mario et al

in Proceedings of the Iron & Steel Technology Conference and Exposition (AISTech 2015 & ICSTI) (2015, May)

Efficient work rolls for Hot Strip mill roughing stands are usually produced as bimetallic spun cast rolls with a core material made of Spheroidal Graphite Iron (SGI) and a shell material made of High ... [more ▼]

Efficient work rolls for Hot Strip mill roughing stands are usually produced as bimetallic spun cast rolls with a core material made of Spheroidal Graphite Iron (SGI) and a shell material made of High Chromium Steel alloy, semi-High speed steel or adapted High Speed steel chemistry. In this paper, the evolution of stress fields and microstructure during post casting cooling and subsequent heat treatment of a standard high chromium steel is targeted. This knowledge is a first step to analyze the different events that could happen during these production stages and provides the residual stress fields as well as the final roll microstructure which are interesting data for roll service life. As far as roughing mill work rolls for roughing mills are concerned, current trends in terms of work roll design are forcing the roll producer to go towards higher usable shell thicknesses or increased residual shell thickness after scrap diameter in order to delay potential fatigue phenomena at the shell-core interface. One important parameter could not be evaluated in this study, it concerns the pollutions of the core material by alloying elements of the shell during production, which could affect to some extent the mechanical properties and microstructure of the core. The macroscopic thermo-mechanical-metallurgical Finite Element model used to perform simulations, takes into account coupled effects. Input data parameters are identified by experimental tests such as compression tests at constant strain rate and numerical procedures such as inverse method. After the model presentation, the material data set is commented. Whole experimental campaign could not be presented, however interested readers are referred to [1] where more details on the material study of High Chromium Steel alloy can be found. The section of simulation results show the phase transformation histories and stress profiles of a typical roll of diameter 1.2 m and shell thickness of 0.08 m. An additional sensitivity analysis of the results to some material data such as induced plasticity transformation coefficient and shift of the martensitic transformation start temperature parameters is reported. Finally, some conclusions analyze the interest and drawbacks of the described model and its results. [less ▲]

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See detailDetermination of surface composition of alloy nanoparticles and relationships with catalytic activity in Pd-Cu/SiO2 cogelled xerogel catalysts
Lambert, Stéphanie ULg; Heinrichs, Benoît ULg; Brasseur, Alain et al

in Applied Catalysis A : General (2004), 270(1-2), 201-208

The combination of results from carbon monoxide chemisorption, X-ray diffraction, and transmission electron microscopy allowed calculating the surface composition of the palladium-copper nanoparticles in ... [more ▼]

The combination of results from carbon monoxide chemisorption, X-ray diffraction, and transmission electron microscopy allowed calculating the surface composition of the palladium-copper nanoparticles in Pd-Cu/SiO2 cogelled xerogel catalysts. Values obtained indicate a very pronounced surface enrichment with copper. Surface compositions obtained with this method, which combines three different experimental techniques, are in agreement with the literature data previously obtained for surface segregation in Pd-Cu/SiO2 catalysts by other techniques as low energy ion scattering and X-ray photoelectron spectroscopy. While 1,2-dichloroethane hydrodechlorination over pure palladium mainly produces ethane, increasing copper content in bimetallic catalysts results in an increase in ethylene selectivity, to reach 100% in ethylene selectivity for the sample containing 1.4 wt.% of palladium and 3.0 wt.% of copper. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailDetermination of Tear Break-up Time reference values and ocular tolerance of tetracaine hydrochloride eyedops in healthy horses
Monclin, Sébastien ULg; Farnir, Frédéric ULg; Grauwels, Magda ULg

in Equine Veterinary Journal (2011), 43(1), 74-77

REASONS FOR PERFORMING STUDY: Tetracaine hydrochloride (THCl) has been reported to cause irritation in dogs. In man, some topical anaesthetics have been shown to disrupt the tear film. Tear break-up time ... [more ▼]

REASONS FOR PERFORMING STUDY: Tetracaine hydrochloride (THCl) has been reported to cause irritation in dogs. In man, some topical anaesthetics have been shown to disrupt the tear film. Tear break-up time (TBUT) is a useful test allowing an assessment of the quality of the precorneal tear film. Only one TBUT value has been reported in horses with no information on the technique used. OBJECTIVES: To provide a method for performing the TBUT in horses and to report any side effects of a single application of THCl in clinically normal horses, particularly on the stability of the tear film. METHODS: In Study 1, one drop of 0.5 or 1% THCl was applied to one eye of 20 horses divided in 2 groups. Treated eyes were assessed for the development of side effects 2.5 and 5 min after treatment. In Study 2, the TBUT was measured in both eyes of 2 groups of 10 horses, before and 2.5 and 5 min after, instillation of one drop of either 0.5 or 1% THCl. RESULTS: No animals developed any ocular side effect after instillation. Basal TBUT was 8.3±1.3 s. TBUT decreased from baseline 5 and 2.5 min after application of one drop of 0.5% THCl and one drop of 1% THCl, respectively. CONCLUSIONS: A technique to measure the TBUT in healthy horses is described and normal range values that could be used as a reference were obtained. POTENTIAL RELEVANCE: THCl is well tolerated in horses but lowers the TBUT. [less ▲]

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See detailDetermination of TGF-β1 plasma levels. Authors' reply
Barthelemy, Nicole ULg; De Jaeger, Katrien; SEPPENWOOLDE, Yvette et al

in International Journal of Radiation, Oncology, Biology, Physics (2004), 60(4), 1339

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See detailDetermination of the Al2O3 content in NaF-AlF 3-CaF2-Al2O3 melts at 950 °c by raman spectroscopy
Malherbe, Cédric ULg; Eppe, Gauthier ULg; Gilbert, Bernard ULg

in Analytical Chemistry (2014)

Thein situ control of the chemical composition of industrial aluminum smelter is a challenge mainly for physicochemical reasons: high temperature, high surrounding electromagnetic field, and the highly ... [more ▼]

Thein situ control of the chemical composition of industrial aluminum smelter is a challenge mainly for physicochemical reasons: high temperature, high surrounding electromagnetic field, and the highly corrosive molten salt electrolyte to deal with. In previous works, we proposed that Raman spectroscopy is a method of choice that could be adapted to real smelters. The laboratory study presented here relies on reproducible Raman spectra recorded on molten mixtures whose compositions are identical to those used during the production of aluminum. A normalization procedure for the Raman spectra is proposed based on the equilibria taking place in the bath. In addition, we discuss two quantitative models to determine the alumina content from the Raman spectra of the molten NaF−AlF3−CaF2−Al2O3 electrolytes. Univariate and multivariate approaches are applied to determine both theCOx (alumina content) and the CR (NaF/AlF3 molar ratio) by Raman spectroscopy without referring to an additional internal reference of intensity. The procedure was successfully tested and validated on industrial samples. [less ▲]

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See detailDetermination of the antimony valence state in Eu10Mn6Sb13
Brown, D. E.; Johnson, C. E.; Grandjean, Fernande ULg et al

in Inorganic Chemistry (2004), 43(4), 1229-1234

The antimony-121 Mossbauer spectra of Eu10Mn6Sb13 have been measured between 2 and 295 K. Although the Zintl formalism indicates that the nine crystallographically distinct antimony sites in Eu10Mn6Sb13 ... [more ▼]

The antimony-121 Mossbauer spectra of Eu10Mn6Sb13 have been measured between 2 and 295 K. Although the Zintl formalism indicates that the nine crystallographically distinct antimony sites in Eu10Mn6Sb13 should have formal valence states of -2, -1, 0, and +1, the Mossbauer spectral isomer shifts reveal that the valence states of the 4.0 different sites are all quite similar and correspond to an average electronic configuration for antimony of 5s(1.7)5p(4.0). This configuration corresponds to an excess of negative charge on the antimony of 0.7 or an average valence of -0.7, a valence which is rather consistent with the average antimony valence of -0.61 obtained from the Zintl formalism for the nine antimony sites in Eu10Mn6Sb13. The spectra obtained between 90 and 295 K are more consistent with the absence rather than the presence of any transferred magnetic hyperfine field at the antimony. In contrast, the spectra obtained at 2 and 5 K reveal the presence of an average transferred magnetic hyperfine field of ca. 8 T, a field that arises from the ferromagnetic ordering of the near-neighbor manganese(II) ions. [less ▲]

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See detailDetermination of the complete bifurcation behaviour of aeroelastic systems with freeplay
Dimitriadis, Grigorios ULg

Scientific conference (2010, November 09)

In recent years there have been several applications of the nonlinear numerical continuation approach to aeroelastic systems with freeplay. While some of these have been successful, the general ... [more ▼]

In recent years there have been several applications of the nonlinear numerical continuation approach to aeroelastic systems with freeplay. While some of these have been successful, the general application of the method to such systems remains problematic. Numerical continuation can fail in the presence of complex bifurcations, numerous nearby periodic solution branches and other factors. In this paper, a three-part procedure for applying numerical continuation to aeroelastic systems with freeplay is proposed, designed to ensure that the complete periodic behavior is identified, even for systems with complex bifurcation diagrams. First, the equivalent linearization approach is used to determine approximations to the periodic solution branches of the nonlinear system. Then, a shooting-based technique is applied separately to each linearized approximation in order to pinpoint the nearest exact periodic solution. This process results in a cloud of periodic solutions, representing all the branches and sub-branches. Finally, a branch-following shooting procedure is applied to this cloud of points in order to obtain a complete description of every branch of periodic solutions. The procedure is demonstrated on a simple 3-DOF mathematical aeroelastic system with freeplay; it is shown that an extremely complex bifurcation is fully captured. The system's bifurcation diagram features multiple branch crossings, folds and loops. Its complete calculation allows the justification of several interesting LCO phenomena, such as aperiodic LCOs. [less ▲]

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See detailDetermination of the composition of cryolitic melts involved in the Hall-Heroult process by Raman spectroscopy
Malherbe, Cédric ULg; Gilbert, Bernard ULg

Conference (2012, August)

Considering our experience in the study of such highly corrosive media by Raman spectroscopy and since the bath spectrum is function of the molar NaF/AlF3 ratio and the Al2O3 content, we have proposed in ... [more ▼]

Considering our experience in the study of such highly corrosive media by Raman spectroscopy and since the bath spectrum is function of the molar NaF/AlF3 ratio and the Al2O3 content, we have proposed in the past to apply that technique to the direct determination of the melt composition . Recent instrumental developments on CCD based spectrometers have made the proposed method more feasible. This presentation will first demonstrate that, employing an updated instrument provided with new optical filters and a more sensitive CCD detector, better quality spectra are obtained. Afterward, new results relevant to the development of our analytical method for the direct determination of the molar NaF/AlF3 ratio and the Al2O3 content in cryolitic melt will be discuss. Different aspects of the calculation procedure will be illustrated:  Estimation and subtraction method of the Rayleigh decay from melt spectra;  Development of an internal normalisation procedure based on equilibria in the melt and assisted by home-made software;  Establishment of calibration curves for the determination of the molar ratio NaF/AlF3 in the melt;  Establishment of calibration curves for the determination of oxide content in the melt;  Overall procedure for the composition determination. [less ▲]

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See detailDetermination of the constants of the diurnal nutation
Folie, François ULg

in Science (1895), 2(45), 613-617

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See detailDetermination of the coordination number of particulate nano-materials using nitrogen adsorption
Gommes, Cédric ULg; Ravikovitch, Peter; Neimak, Alex

Scientific conference (2008, April)

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See detailDetermination of the Cosmological Density of Compact Objects using Gravitational Lensing and the HST
Claeskens, Jean-François ULg; Surdej, Jean ULg

in Benvenuti, Piero; Macchetto, F. D.; Schreier, E. J. (Eds.) Science with the Hubble Space Telescope - II (1996)

Detailed reference viewed: 3 (1 ULg)