Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailMicroparticles loaded with PAR-1 agonist peptide for tissue repair
Markvicheva, E; Stashevskaya, K; Strukova, S et al

in European Journal of Cell Biology. Supplement (2006), 85(S 56), 38

Detailed reference viewed: 11 (0 ULg)
Full Text
Peer Reviewed
See detailMicroPET Focus 120 scanner use at high-­‐count rate
Bahri, Mohamed Ali ULg; Warnock, Geoffrey ULg; Taleb, Dounia ULg et al

Poster (2012, September)

Kinetic modeling of physiological processes using imaging techniques requires an accurate measurement of the time-activity curve of the tracer in plasma, known as the arterial input function (IF). The IF ... [more ▼]

Kinetic modeling of physiological processes using imaging techniques requires an accurate measurement of the time-activity curve of the tracer in plasma, known as the arterial input function (IF). The IF can be obtained by manual blood sampling, can be derived from PET images, or continuously measured by the use of small counting systems such as beta microprobes [1]. However, some beta microprobe systems can suffering from high background counts and low sensitivity compared to PET can obligate the use of activities higher than those typical for the imaging system. In the present study, the NEMA NU4-2008 image quality (IQ) phantom [2] was used to evaluate the image quality of the microPET Focus 120 at high activity values. Attenuation correction was obtained from transmission measurement using 57Co point source. Eight emission scans of 20 minutes were performed at decreasing activity starting from 109 MBq to 3.7 MBq (total activity in the field-of-view). To study the effect of normalization in high count rate studies, several normalization scans were performed using activities ranging between 18 and 212 MBq. Images were reconstructed with all corrections using Fourier rebinning and filtered backprojection. The mean activity and the coefficients of variation of the uniform slices were measured. All high activity reconstructed images showed a detector-block-patterned artifact with an overestimation of the counts when normalization activity is higher than that used in the IQ phantom and underestimation of the counts when normalization activity is below the activity used in the IQ phantom. Using the same high activity for acquisition and normalization considerably reduces the patterned-artifact but does not eliminate it entirely. The observed artifact is due to pulse pile-up in the detectors at high count-rates. A dedicated rejection of the pulse pile-up does not appear to have been implemented for the microPET Focus 120. An alternative would be to re-calibrate the detectors with higher activity values to prevent any pile-up effect or to create an attenuation volume into which phantoms or small animals could be inserted thus decreasing the artifact. This latter option is under development. References: [1] G. Warnock et al, European Journal of Nuclear Medicine and Molecular Imaging Research, 1-13 (2011) [2] NEMA Standards Publication NU4-2008. Rosslyn, VA: National Electrical Manufacturers Association; (2008). [less ▲]

Detailed reference viewed: 127 (10 ULg)
Full Text
Peer Reviewed
See detailMicrophase separation at the surface of block copolymers, as studied with atomic force microscopy
Rasmont, A.; Leclère, Philippe; Doneux, C. et al

in Colloids and Surfaces B : Biointerfaces (2000), 19(4), 381-395

Atomic force microscopy (AFM) is used to study the phase separation process occurring in block copolymers in the solid state. The simultaneous measurement of the amplitude and the phase of the oscillating ... [more ▼]

Atomic force microscopy (AFM) is used to study the phase separation process occurring in block copolymers in the solid state. The simultaneous measurement of the amplitude and the phase of the oscillating cantilever in the tapping mode operation provides the surface topography along with the cartography of the microdomains of different mechanical properties. This technique thus allows to characterize the size and shape of those microdomains and their organization at the surface (e.g. cubic lattice spheres, hexagonal lattice of cylinders, or lamellae). In this study, a series of symmetric triblock copolymers made of a inner elastomeric sequence (poly(butadiene) or poly(alkylacrylate)) and two outer thermoplastic sequences (poly(methylmethacrylate)) is analyzed by AFM in the tapping mode. The microphase separation and their morphology are essential factors for the potential of these materials as a new class of thermoplastic elastomers. Special attention is paid to the control of the surface morphology, as observed by AFM, by the molecular structure of the copolymers (volume ratio of the sequences, molecular weight, length of the alkyl side group) and the experimental conditions used for the sample preparation. The molecular structure of the chains is completely controlled by the synthesis, which relies on the sequential living anionic polymerization of the comonomers. The copolymers are analyzed as solvent-cast films, whose characteristics depend on the solvent used and the annealing conditions. The surface arrangement of the phase-separated elastomeric and thermoplastic microdomains observed on the AFM phase images is discussed on the basis of quantitative information provided by the statistical analysis by Fourier transform and grain size distribution calculations. [less ▲]

Detailed reference viewed: 49 (3 ULg)
Full Text
See detailMicrophone arrays fundamentals
Embrechts, Jean-Jacques ULg

Conference (2011, November 23)

Microphone arrays are essentially directional sensors. They are therefore mainly used for locating, identifying, isolating, measuring and recording individual sound sources. The main principles governing ... [more ▼]

Microphone arrays are essentially directional sensors. They are therefore mainly used for locating, identifying, isolating, measuring and recording individual sound sources. The main principles governing the directivity of microphone arrays are reviewed: phase differences between signals create constructive and destructive interferences, depending on the direction of the sound source. Moreover, signal processing is applied to provide “beamforming”, i.e. beam shaping and steering. Contrary to continuous antenna, discrete arrays can create aliasing, which can result in false detections of sound sources. The delay-and-sum and filter-and-sum beamformers are described. Finally, as simple beamformers are often frequency dependent, some solutions to obtain constant (broad-band) directivity are presented. [less ▲]

Detailed reference viewed: 43 (3 ULg)
Full Text
Peer Reviewed
See detailMicrophysical characteristics of artificial fog produced in laboratory to study road visibility.
Colomb, M.; Serezat, L.; Boreux, Jean-Jacques ULg

in Proceedings of the 23th Session of the International Commission of Illumination (1995)

Pour étudier la visibilité des équipements de la route dans le brouillard, une approche expérimentale a été choisie. On reproduit du brouillard artificiel en laboratoire par injection d'eau sous pression ... [more ▼]

Pour étudier la visibilité des équipements de la route dans le brouillard, une approche expérimentale a été choisie. On reproduit du brouillard artificiel en laboratoire par injection d'eau sous pression. Pour qualifier ces installations, il est nécessaire de connaître la granulométrie de ce brouillard. Le spectre dimensionnel des gouttelettes est mesuré avec un compteur optique de particules, en divers points de la salle. L'opacité du brouillard est contrôlée en permanence pendant les essais à l'aide d'un transmissiomètre. La concentration des gouttelettes varie avec l'opacité. La taille des particules se répartit suivant une distribution dont le pic en diamètre est de l'ordre de 1µm. Ces données sont comparées aux caractéristiques des brouillards naturels. [less ▲]

Detailed reference viewed: 20 (5 ULg)
Full Text
Peer Reviewed
See detailMICROPHYSIQUE DES NUAGES ET RAYONNEMENT SOLAIRE : COMPARAISON DES MESURES IN SITU AU MONT RIGI EN HAUTE BELGIQUE ET DES DONNÉES CLOUD PHYSICAL PROPERTIES (CPP) OBTENUES À PARTIR DES IMAGES METEOSAT-9
Beaumet, Julien ULg; Clerbaux, Nicolas; Cornet, Yves ULg et al

in Camberlin, Pierre; Richard, Yves (Eds.) Actes du XXVIIe Colloque de l'Association Internationale de Climatologie : CLIMAT : SYSTÈME & INTERACTIONS (2014, July 02)

Le rayonnement solaire global mesuré au mont Rigi a été comparé à l'épaisseur optique des nuages (COT) estimée à l'aide des données SEVIRI. Une relation logarithmique avec un coefficient de détermination ... [more ▼]

Le rayonnement solaire global mesuré au mont Rigi a été comparé à l'épaisseur optique des nuages (COT) estimée à l'aide des données SEVIRI. Une relation logarithmique avec un coefficient de détermination d'environ 0,5 a été trouvée. Ce résultat plutôt faible peut en grande partie s'expliquer par un nombre limité de cas où subsistent des erreurs de positionnement ou par des interactions plus complexes entre nébulosité et rayonnement. De plus, l'incertitude sur l'estimation de l'épaisseur optique des nuages à l'aide des données SEVIRI pour les nuages optiquement plus épais n'est pas négligeable. [less ▲]

Detailed reference viewed: 22 (1 ULg)
Peer Reviewed
See detailMicroplastics caught in herring gill rakers: illustration by scanning electron microscopy
Collard, France ULg; Das, Krishna ULg; Parmentier, Eric ULg

Conference (2014, March 07)

Plastics are produced in huge quantity (280 million of tons in 2012) and more than 10% end up in the oceans. It is estimated that between 60 and 80% of all marine debris are plastics. Plastics are ... [more ▼]

Plastics are produced in huge quantity (280 million of tons in 2012) and more than 10% end up in the oceans. It is estimated that between 60 and 80% of all marine debris are plastics. Plastics are persistent and have accumulated in the oceans for several decades. Plastics may adverse wildlife in many ways: they can be ingested by marine vertebrates and cause internal wounds in the digestive tract. Plastics are also vectors of organic pollutants including. Once ingested, plastics may release these pollutants in the organism. Plastics present in the marine environment fragment in small pieces by mechanical stress and UV radiation leading to the so-called microplastics smaller than 5 mm. Little is known about microplastics ingestion and toxicity in planktivorous fish such as the herring, Clupea harengus. Planktivorous fish have gill rakers, which may function as a trap for microplastics. This study aims to describe and characterise microplastics present on gill rakers of the herring, Clupea harengus. Ten gill cavities were sampled in January 2013 in the Channel and the North Sea during a fishery campaign organized by the IFREMER. Gills cavities were placed in a fixating solution until preparation for scanning electron microscopy (SEM). SEM was used in order to detect microplastics which are too small to be observed by a dissection microscope, to compare them with the distance between gill rakers and to characterise the surface and the shape of microplastics. Scanning electron microscopy revealed large variety of microplastics, which lengths ranged from 0.05 to 5mm. Relationship between microplastics length and distance between gill rakers was analysed on the same branchial arch. The present study revealed the presence of microplastics in an edible species of high economic value and raise question about potential impact on the herring and its consumers, including human beings. [less ▲]

Detailed reference viewed: 103 (4 ULg)
Full Text
Peer Reviewed
See detailMicroplastics contamination in two planktivorous and commercial fish species
Collard, France ULg; Parmentier, Eric ULg; Das, Krishna ULg

Poster (2014, May 13)

Plastic pollution is a huge environmental concern and affects each marine ecosystem. Plastics are produced by millions of tonnes each year in the world and finally accumulate in oceans. They adsorb many ... [more ▼]

Plastic pollution is a huge environmental concern and affects each marine ecosystem. Plastics are produced by millions of tonnes each year in the world and finally accumulate in oceans. They adsorb many persistent organic pollutants, cause external and internal wounds and provoke blockage of the digestive tract of marine mammals, birds and turtles. Plastics can also threaten marine organisms of small size class in the same way by fragmenting in smaller parts that result in microplastics of less than five millimetres. These microplastics are of the same order of magnitude than plankton and can thus be ingested by filter-feeders, suspension-filters and planktivorous organisms such as fish. Few studies deal with microplastics ingestion by fish and even less by commercial fish species. The herring (Clupea harengus) and the sardine (Sardina pilchardus) were respectively the third and the eighth most caught fish species in the world in 2009. We focused our research on these two species which are of economic importance. We sampled around thirty individuals of each species in the Channel and in the North Sea in January 2013. The stomach contents were digested by sodium hypochlorite and then analyzed. Microplastics were characterized by size, colour and shape. The results of these analyses will highlight the need for studies about microplastics ingestion by planktivorous species. [less ▲]

Detailed reference viewed: 143 (3 ULg)
Full Text
Peer Reviewed
See detailMicropolitiques du boom minier
Rubbers, Benjamin ULg

in Politique Africaine (Paris, France : 1981) (2013), 131

De nombreux pays africains ont, à l’instigation de la Banque mondiale, libéralisé leur secteur minier au cours de ces deux dernières décennies, ce qui leur a valu de connaître un afflux d’investisseurs ... [more ▼]

De nombreux pays africains ont, à l’instigation de la Banque mondiale, libéralisé leur secteur minier au cours de ces deux dernières décennies, ce qui leur a valu de connaître un afflux d’investisseurs privés d’origines diverses. Comment la mise en oeuvre de ces réformes estelle négociée par les élites politiques, de la présidence aux édiles locaux ? Dans quelle mesure les comptoirs et les sociétés qui organisent l’exploitation minière artisanale facilitent-ils l’implantation de ces investisseurs ? Que deviennent, dans ce « new scramble » des ressources naturelles, les creuseurs artisanaux et les employés des anciennes entreprises minières ? De quelle façon les syndicats se positionnent-ils face à l’ordre économique et politique qui est en train de se mettre en place ? Au-delà des évaluations générales et normatives dont les investissements miniers font habituellement l’objet, ce numéro a pour ambition d’interroger la portée des changements qu’ils induisent en partant des espaces de lutte dans lesquels ils sont pris et des logiques d’action de ceux qui y prennent part. Sur la base de recherches menées au Burkina Faso, au Cameroun, en République démocratique du Congo et en Afrique du Sud, les contributions réunies ici proposent des pistes d’analyse originales pour décrypter les jeux micropolitiques qui président à la « formation » du boom minier en Afrique. [less ▲]

Detailed reference viewed: 10 (0 ULg)
Full Text
Peer Reviewed
See detailMICROPOLLUTANTS ISSUES: A MODELLING STUDY OF HEAVY METALS WITHIN TWO FRENCH BASINS AND A TEST APPLICATION TO COCAINE IN BELGIUM
Deliège, Jean-François ULg; Everbecq, Etienne ULg; Grard, Aline ULg et al

Poster (2010, April)

European policies (European Framework Directive: Water 2000/60/CE, Directive 76/464/CE) impose to reduce the releases of about a hundred substances in surface water. In the last years, the AQUAPOLE has ... [more ▼]

European policies (European Framework Directive: Water 2000/60/CE, Directive 76/464/CE) impose to reduce the releases of about a hundred substances in surface water. In the last years, the AQUAPOLE has been involved in two studies related to this matter. First, on the request and with the financial support of both the French Ministry of Environment and ONEMA (“Office National de l’Eau et des Milieux Aquatiques”), INERIS (“Institut National de l’Environnement Industriel et des Risques”) drew up the guidelines of a methodology allowing fixing the local Limit Values to Emission so as to abide by the quality standards on the whole watershed. Within this context, INERIS wishes to test the use of pollutant transfer models on pilot sub-basins. The PEGASE model has been used to simulate micropollutants on two concrete use cases (1): (iii) in the Meuse sub-basin, managed by the French Water Agency Rhine-Meuse, for simulations concerning cadmium and zinc; (iv) in the Adour sub-basin, managed by the French Water Agency Adour-Garonne, for simulations applied to cadmium and copper. The choice of each substances and sub-basins was made by mutual agreement between INERIS, the concerned Water Agencies, and the AQUAPOLE. A major selection criterion for the substances and the sub-basins was the availability of data (sources and in situ measurements). For the second study, the PEGASE model has been adapted to describe the cocaine’s behaviour (using a stable metabolite of the cocaine in the environment: the benzoylecgonine (BZE)) in waste water, waste water treatment plants (WWTP) and surface water (2). The cocaine is newly described in the model as an additional micropollutant (PEGASE already treats numerous heavy metals), thanks to the implementation of new state variable equations and their specific parameterizations. Simulations of BZE have been done in the Walloon and Flemish regions, where many measurements from the COWAT project (3) were available. The first results are showing good agreement between calculated and measured values. The ability of the model to simulate the fate of studied micropollutants (cadmium, zinc, copper, and the cocaine derivatives) in surface waters should be enhanced and extended to other substances and basins. Moreover, additional data still have to be collected and measured. [less ▲]

Detailed reference viewed: 61 (16 ULg)
Full Text
Peer Reviewed
See detailMicropore size distributions of activated carbons
Blacher, Silvia ULg; Sahouli, Bendida; Heinrichs, Benoît ULg et al

in Langmuir (2000), 16(16), 6754-6756

Detailed reference viewed: 32 (7 ULg)
Peer Reviewed
See detailMicroporosimétrie quantitative de roches et matériaux par analyse d'images
Pirard, Eric ULg; Pierroux, Alain

in Annales de la Société Géologique de Belgique (1992), 115(1), 245-252

Detailed reference viewed: 31 (1 ULg)
Full Text
Peer Reviewed
See detailMicroporosity formation in nickel-base superalloys in relation to their solidification sequence
Lecomte-Beckers, Jacqueline ULg; Lamberigts, M.

in Proceedings of the International Conference of High Temperature Alloys for Gas Turbine and Other Applications (1986)

This work is aimed at showing how the proneness of superalloys to microporosity formation can be estimated by the tsP* pararneter which makes use of various solidification features. The latter can be ... [more ▼]

This work is aimed at showing how the proneness of superalloys to microporosity formation can be estimated by the tsP* pararneter which makes use of various solidification features. The latter can be derived from quantitative differential thermal analysis (DTA) resuits through the original method described in the text. The technique was applied to two IN 100 master meUs of distinct grades (virgin or revert) which had been showrt to behave very differently in the foundry. It led to ascribe the poorer performance of the revert meit to its particular solidification sequence leading higher dendrite tortuosity and lesser residual liquid fluidity. [less ▲]

Detailed reference viewed: 46 (3 ULg)
Full Text
Peer Reviewed
See detailMicroporous and heterogeneous surface adsorption isotherms arising from Levy distributions
Brouers, François ULg; Sotolongo, O.; Marquez, F. et al

in Physica A: Statistical Mechanics and its Applications (2005), 349(1-2), 271-282

We show that for adsorption on heterogeneous and microporous surfaces, the Freundlich isotherm power-law exponent a is directly related to the Levy tail index of the distribution of the Langmuir parameter ... [more ▼]

We show that for adsorption on heterogeneous and microporous surfaces, the Freundlich isotherm power-law exponent a is directly related to the Levy tail index of the distribution of the Langmuir parameter b and to the expected value and the variance of the adsorption energy distribution. This allows us to view adsorption at low pressure in these systems as a rare event dominated phenomena. Based on this discussion, a generalized isotherm formulation is proposed and applied to the interpretation of recent data on activated carbons. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 30 (3 ULg)
See detailLes microprolactinomes : diagnostic clinique, biologique et radiologique
Burlacu, M. C.; Daly, Adrian ULg; Beckers, Albert ULg

in Young, Jacques (Ed.) Hyperprolactinémies (2008)

Detailed reference viewed: 22 (1 ULg)
Full Text
Peer Reviewed
See detailMicroreactor Technology as an Efficient Tool for Multicomponent Reactions
Cukalovic, Ana; Monbaliu, Jean-Christophe ULg; Stevens, Christian

in Orru, Romano; Ruijter, Eelco (Eds.) Topics in Heterocyclic Chemistry: Synthesis of Heterocycles via Multicomponent Reactions I (2010)

Detailed reference viewed: 17 (5 ULg)