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See detailPoly(acrylic acid)-block-poly(vinyl alcohol) anchored maghemite nanoparticles designed for multi-stimuli triggered drug release
Liu, Ji ULg; Detrembleur, Christophe ULg; Debuigne, Antoine ULg et al

in Nanoscale (2013), 5(23), 11464-11477

Original core/corona nanoparticles composed of amaghemite core and a stimuli-responsive polymer coating made of poly(acrylic acid)-block-poly(vinyl alcohol) macromolecules were fabricated for drug ... [more ▼]

Original core/corona nanoparticles composed of amaghemite core and a stimuli-responsive polymer coating made of poly(acrylic acid)-block-poly(vinyl alcohol) macromolecules were fabricated for drug delivery system (DDS) application. This kind of DDS aims to combine the advantage of stimuli-responsive polymer coating, in order to regulate the drug release behaviours under different conditions and furthermore, improve the biocompatibility and in vivo circulation half-time of the maghemite nanoparticles. Drug loading capacity was evaluated with methylene blue (MB), a cationic model drug. The triggered release of MB was studied under various stimuli such as pH, ionic strength and temperature. Local heating generated under alternating magnetic field (AMF) application was studied, and remotely AMF-triggered release was also confirmed, while a mild heating-up of the release medium was observed. Furthermore, their potential application as magnetic resonance imaging (MRI) contrast agents was explored via relaxivity measurements and acquisition of T2-weighted images. Preliminary studies on the cytotoxicity against mouse fibroblast-like L929 cell line and also their cellular uptake within human melanoma MEL-5 cell line were carried out. In conclusion, this kind of stimuli-responsive nanoparticles appears to be promising carriers for delivering drugs to some tumour sites or into cellular compartments with an acidic environment. [less ▲]

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See detailPubertal timing after neonatal diethylstilbestrol exposure in female rats: Neuroendocrine vs peripheral effects and additive role of prenatal food restriction.
Franssen, Delphine ULg; Ioannou, Yiannis S.; Alvarez-Real, Alexandra et al

in Reproductive toxicology (Elmsford, N.Y.) (2013)

We studied the effects of neonatal exposure to diethylstilbestrol (DES) on pubertal timing in female rats. We examined associated neuroendocrine changes and effects of prenatal food restriction. Age at ... [more ▼]

We studied the effects of neonatal exposure to diethylstilbestrol (DES) on pubertal timing in female rats. We examined associated neuroendocrine changes and effects of prenatal food restriction. Age at vaginal opening was advanced after exposure to 10mug/kg/d of DES and delayed after 1mug/kg/d (subcutaneous injections). Using this lower dose, pulsatile GnRH secretion was slower at 25 days of age. Both doses reduced KiSS1 mRNA levels at 15 days of age. Using functional Kisspeptin promoter assay, 1 or 10muM DES reduced or increased KISS1 transcription, respectively. Leptin stimulatory effect on GnRH secretion in vitro (15 days of age) was reduced after prenatal food restriction and neonatal DES exposure (higher dose), both effects being cumulative. Thus, alterations in pubertal timing by DES neonatally are not unequivocally toward precocity, the level of exposure being critical. We provide evidence of neuroendocrine disruption and interaction with prenatal food availability. [less ▲]

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See detailInversion of a part of the numerator relationship matrix using pedigree information
Faux, Pierre ULg; Gengler, Nicolas ULg

in Genetics, Selection, Evolution [=GSE] (2013), 45

Background. In recent theoretical developments, the information available (e.g. genotypes) divides the original population into two groups: animals with this information (selected animals) and animals ... [more ▼]

Background. In recent theoretical developments, the information available (e.g. genotypes) divides the original population into two groups: animals with this information (selected animals) and animals without this information (excluded animals). These developments require inversion of the part of the pedigree-based numerator relationship matrix that describes the genetic covariance between selected animals (A22). Our main objective was to propose and evaluate methodology that takes advantage of any potential sparsity in the inverse of A22 in order to reduce the computing time required for its inversion. This potential sparsity is brought out by searching the pedigree for dependencies between the selected animals. Jointly, we expected distant ancestors to provide relationship ties that increase the density of matrix A22 but that their effect on A22i might be minor. This hypothesis was also tested. Methods. The inverse of A22 can be computed from the inverse of the triangular factor (T-1 ) obtained by Cholesky root-free decomposition of A22 . We propose an algorithm that sets up the sparsity pattern of T-1 using pedigree information. This algorithm provides positions of the elements of T-1 worth to be computed (i.e. different from zero). A recursive computation of A22i is then achieved with or without information on the sparsity pattern and time required for each computation was recorded. For three numbers of selected animals (4000; 8000 and 12 000), A22 was computed using different pedigree extractions and the closeness of the resulting A22i to the inverse computed using the fully extracted pedigree was measured by an appropriate norm. Results. The use of prior information on the sparsity of T-1 decreased the computing time for inversion by a factor of 1.73 on average. Computational issues and practical uses of the different algorithms were discussed. Cases involving more than 12 000 selected animals were considered. Inclusion of 10 generations was determined to be sufficient when computing A22. Conclusions. Depending on the size and structure of the selected sub-population, gains in time to compute A22 are possible and these gains may increase as the number of selected animals increases. Given the sequential nature of most computational steps, the proposed algorithm can benefit from optimization and may be convenient for genomic evaluations. [less ▲]

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See detailEtat des lieux et perspectives de la foresterie communautaire au Gabon
Meunier, Quentin; Boldrini, Sylvie; Vermeulen, Cédric ULg

Conference (2013, December 06)

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See detailEncres anciennes: utilisation non conventionnelle d'aliments
Bouchat, Isabelle; Wymeersch, Noémie; Bchir, Brahim ULg et al

in Septième symposium du GCNAS: Vendredi 6 décembre, Louvain-La-Neuve (2013, December 06)

De tout temps l’homme utilise des pigments pour peindre. Il y a 27.000 ans déjà, près de Marseille, dans la grotte Cosquer, des fresques furent peintes par des hommes préhistoriques. Il existe deux ... [more ▼]

De tout temps l’homme utilise des pigments pour peindre. Il y a 27.000 ans déjà, près de Marseille, dans la grotte Cosquer, des fresques furent peintes par des hommes préhistoriques. Il existe deux grandes catégories de pigments et colorants: les naturels et les artificiels. La première catégories contient les pigments minéraux tels que les argiles (ocre jaune ou rouge, argile verte ou brune) mais aussi des pierres (lapis lazuli (bleu)) et les pigments organiques d’origine végétale (gaude (jaune)) ou d’origine animale (murex (pourpre). La deuxième catégorie contient les pigments et colorants artificiels issus de réactions chimiques (minium (orange)) ou bien des mi-végétaux, mi-minéraux comme les encres ferro-galliques classés dans les divers. Après avoir servi pendant plusieurs siècles, tous ces pigments ont été remplacés à la fin du XIXe par des colorants synthétiques issus de la pétrochimie, car ces derniers ont l'avantage de la reproductibilité constante des couleurs. Mais la fin programmée du pétrole suscite un regain d'intérêt pour les préparations naturelles. C'est donc très logiquement que notre laboratoire a décidé de s'intéresser au sujet et en particulier aux encres venant du jus de chou rouge et aux encres ferro-grenadiques en collaboration avec l'Abbaye de Villers-la-Ville. [less ▲]

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See detailReliability of resistivity-derived temperature: insights from laboratory measurements
Robert, Tanguy ULg; Hermans, Thomas ULg; Dumont, Gaël ULg et al

Conference (2013, December 06)

This contribution consists in studying the reliability of resistivity-derived temperature, for example from time-lapse electrical resistivity tomography (ERT) surveys. The idea of using temperature as a ... [more ▼]

This contribution consists in studying the reliability of resistivity-derived temperature, for example from time-lapse electrical resistivity tomography (ERT) surveys. The idea of using temperature as a quantitative tracer is growing in the hydrogeophysical community, especially to simulate geo/hydrothermal systems. However, plenty of physico-chemical processes are influenced by temperature and most of them impact directly resistivity measurements. Therefore, one needs to take them into account to retrieve quantitative temperature estimates from resistivity measurements but, up to now, it is seldom the case. The experiment we conducted consisted in simulating an ERT monitoring of heat storage in a sandy aquifer. We show that using experimental relationships between fluid electrical conductivity and temperature alone does not allow reliable temperature estimates, simply because rock-water interactions are neglected. Worst, from a certain temperature (45°C here), the bulk resistivity starts to increase with temperature although this is not expected from the experimental law. Chemical analyses made on water samples collected during the experiment highlight the importance of accounting chemical reactions (e.g. calcite precipitation with increasing temperature) occurring when temperature changes as well as their kinetics. Finally, other parameters as surface conductivity cannot always be neglected when estimating temperature from resistivity measurements. This means that retrieving reliable temperatures from bulk resistivity measurements (e.g. time-lapse ERT) requires the knowledge of water mineralization as well as the rock / soil mineralogy in order to fully integrate physico-chemical reactions between groundwater and the host rock, for example with a joint inversion scheme. [less ▲]

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See detailMonitoring temperature changes during heat tracing experiments using electrical resistivity tomography
Hermans, Thomas ULg; Wildemeersch, Samuel ULg; Nguyen, Frédéric ULg

Conference (2013, December 06)

Thermal tracing experiments are becoming common in hydrogeology to estimate parameters governing heat transport processes and to study geothermal reservoirs. Electrical resistivity tomography (ERT) has ... [more ▼]

Thermal tracing experiments are becoming common in hydrogeology to estimate parameters governing heat transport processes and to study geothermal reservoirs. Electrical resistivity tomography (ERT) has proven its ability to monitor salt tracer tests, but few studies have investigated its performances, both qualitatively and quantitatively, in thermal tracing experiments. In this study, we monitored a heat injection and pumping experiment in an alluvial aquifer using both surface and crosshole ERT. The data sets of the surface profile, located along the main direction of flow, are distorted during injection by an electrical short-circuit through the external pumping-heating-injection experimental set-up. Current is flowing outside the subsurface leading to bad data for electrode dipoles located near the pumping and injection wells. The crosshole ERT panel is perpendicular to the main direction of flow. Difference inversion time-lapse images clearly show a preferential flow path in the bottom of the aquifer related to the presence of a coarse and clean gravel layer. Direct temperature measurements are available in control piezometers during the experiment to validate the ERT-derived temperatures and confirm the spatial pattern of temperature observed with ERT. Breakthrough curves are correctly retrieved in time and difference of 10 to 20% are observed for temperature estimation. The latter requires site-specific petrophysical laws and chemical stability assumptions that must be carefully verified. Our study proves that ERT, especially crosshole ERT, is a reliable tool to follow thermal tracing experiments but also to characterize heat transfer in the subsurface and to monitor geothermal resource exploitations. We also show that surface ERT may be impacted by the survey layout in unsuspected ways. [less ▲]

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See detailThe impact of the salience of fluency in recognition memory in Alzheimer’s disease
Simon, Jessica ULg; Bastin, Christine ULg; SALMON, Eric ULg et al

Poster (2013, December 06)

According to the dual-process models, recognition memory is supported by recollection and familiarity (Yonelinas, 2002). Familiarity is a complex function that depends on several processes. One of the ... [more ▼]

According to the dual-process models, recognition memory is supported by recollection and familiarity (Yonelinas, 2002). Familiarity is a complex function that depends on several processes. One of the most important mechanisms is the sense of familiarity driven by the fluency processing (Whittlesea, 1993). The fluency can be defined by the enhancement of processing speed and the ease of processing due to an earlier encounter with the stimulus. Our objective is to explore the effect on an increase of salience of fluency cues on the recognition memory performance of patients with Alzheimer disease (AD). Sixteen AD patients and sixteen healthy elderly controls (HC) performed two conditions of a memory task. In the study phase, 25 words were presented at a rate of one word every 1.5s. Participants were instructed to read the words aloud and to try and remember them. After a break of 5 minutes, participant performed a yes/no recognition task with 25 studied words and 25 new words. In the Non-Overlap condition, the 25 studied words were composed of a subset of letters of the alphabet and the 25 new words of the remaining letters. In the Overlap condition, the 50 words were based on the whole alphabet. The two recognition tasks were separated by a delay of 24h. The capacity to discriminate between old and new items was measured by the index d’. An ANOVA on d’ scores revealed that discrimination was poorer in the AD group than in the HC and also poorer in the Overlap condition than in the Non-Overlap condition. The current results showed that to increase salience of fluency at the level of letter by eliminating letter-overlap between old and new words increases the recognition performance to the same extent in both groups but the amplitude of AD memory deficit was not reduced (Bastin, Willems, Genon, & Salmon, 2013). [less ▲]

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See detailOdour emissions impact of on-farm biogas production with co-digestion : a case study in four European farms of the Great Region
Adam, Gilles ULg; Gennen, Jérome; Ubeda Sanchez, Yolanda et al

Conference (2013, December 06)

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See detailL'India ha fame
Maiorano, Diego ULg

Article for general public (2013)

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See detailDéveloppement professionnel: la place de l'accompagnement dans un système compétent
Pirard, Florence ULg

Scientific conference (2013, December 06)

De nombreuses instances internationales comme l’OCDE (2001, 2006, 2012), la Commission européenne (EACEA, 2009) relèvent l’importance tant des compétences nécessaires dans l’accueil et l’éducation de ... [more ▼]

De nombreuses instances internationales comme l’OCDE (2001, 2006, 2012), la Commission européenne (EACEA, 2009) relèvent l’importance tant des compétences nécessaires dans l’accueil et l’éducation de jeunes enfants que celle des conditions qui permettent leur développement. De nombreuses recherches ont montré la nécessité d’assurer l’organisation de formations initiales de niveau supérieur où les dimensions socio-psycho-éducatives occupent une place de choix. Des travaux récents (Urban, al, 2011) soulignent, dans une perspective systémique, l’importance d’inscrire le développement professionnel dans un processus non seulement individuel, mais aussi collectif qui engage différents niveaux de responsabilité. Ils proposent la notion de « Système compétent » qui met l’accent sur les relations d’interdépendance entre « compétences individuelles », « compétences institutionnelles », « compétences interinstitutionnelles » et « de gouvernance ». Au niveau local, ces travaux donnent un cadre pour repenser les différentes manières de soutenir le développement professionnel, non seulement dans des espaces temps institutionnalisés d’enseignement et de formation centrés sur le développement de savoirs et de capacités, mais aussi dans les lieux d’accueil et d’éducation eux-mêmes où, par des dispositifs d’accompagnement de projets, des groupes d’analyse des pratiques documentées, des professionnel(le)s de l’enfance peuvent être engagé(e)s dans un processus de transformation conjointe à la fois de leurs actions (les pratiques éducatives), des acteurs (leurs propres compétences au bénéfice de l’accueil des enfants et des familles) et de leur environnement (Pirard, Barbier, 2012). Cette évolution témoigne de l’émergence d’une culture de la professionnalisation (Barbier, 2005) dans le secteur de l’enfance. [less ▲]

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See detailL'interface 1ère-2ème ligne de soins
Belche, Jean-Luc ULg

Conference (2013, December 06)

L’implication des MG dans le suivi de patients insuffisants cardiaques sévères est importante. Le « chronic car model » a démontré son efficacité dans le suivi d’une maladie chronique. L’opérationnalité ... [more ▼]

L’implication des MG dans le suivi de patients insuffisants cardiaques sévères est importante. Le « chronic car model » a démontré son efficacité dans le suivi d’une maladie chronique. L’opérationnalité de la prise en charge intégrée sur le terrain devrait respecter les particularités locales et/ou les réseaux existants. Le MG n’est pas le seul intervenant actuel de la première ligne de soins ; il travaille le plus souvent en réseau, quand celui-ci n’est pas structuré en centre de santé intégré. Ce modèle, promotionné par l’OMS, repose sur un travail en équipe pluridisciplinaire, dans un souci de continuité relationnelle et informationelle. (Les réseaux multidisciplinaires locaux (RML) ont été créés à cette fin dans le cadre des trajets de soins.) L’adjonction d’intervenant spécialisé dans le suivi de l’insuffisance cardiaque porte en elle le germe de la muliplication des intervenants et de la fragmentation des soins. Cela risque de provoquer un rejet par la première ligne de soins, au moment où on l’appelle à se structurer en réseau d’intervenants, à vocation transversale ou générale. Or la situation la plus prévalente est la multimorbidité, l’insuffisance cardiaque au milieu d’autres maladies ou conditions chroniques. Il est démontré que la multiplication des approches centrées sur la maladie a un impact négatif sur l’efficacité des soins, sur la qualité des soins, et à un coût plus élevé. L’approche centrée sur la maladie, prédominante actuellement, doit glisser lentement mais surement vers une approche centrée sur le patient, et ses propres objectifs. [less ▲]

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See detailDynamique d’une espèce ligneuse héliophile longévive dans un monde changeant : le cas de Pericopsis elata (Harms) Meeuwen (Fabaceae) au sud est du Cameroun
Bourland, Nils ULg

Doctoral thesis (2013)

The Central African forests are characterized by high species richness. While little light generally reaches their litter layer, among the species encountered are major long-lived light-demanding logged ... [more ▼]

The Central African forests are characterized by high species richness. While little light generally reaches their litter layer, among the species encountered are major long-lived light-demanding logged trees. These species may have established in the past because of large disturbances. Indeed, major climate changes have occurred in the past few millennia, in some areas coupled with strong human occupations. Among these light-demanding species we find the assamela / afrormosia (Pericopsis elata (Harms) Meeuwen, Fabaceae), a large high trading value tree of African semi-deciduous moist forests. Nowadays this logged species suffers from significant regeneration problems on its natural range from Ghana to the Democratic Republic of Congo. Therefore, it is included in CITES Appendix II and is recorded as “Endangered A1cd” on the IUCN Red List. No convincing solution can be found in the available scientific literature to overcome the deficiency of its regeneration. In addition, little or no information is available describing ca. its population dynamics, genetics, silviculture or the probable origin of its stands. It is in this context that the present PhD was undertaken. In this study, we have adopted a multidisciplinary approach to understanding the dynamics of this population rich in long-lived light-demanding species logged in the Congo basin. Moreover, we have suggested ways for their management and conservation in a changing world. To do so, we have adopted as a study-model the case of P. elata in southeastern Cameroon. The main results of the study show that, on a local scale, physico-chemical soil parameters have no influence on the presence or absence of this clustered species. However, on the same scale, large quantities of charcoal were found in the soil, mainly inside those clusters. The anthracological analysis has also shown that the vegetation at the time of the burn was similar to that of today. Numerous fragments of pottery were also found in the top soil layers only inside clusters formed by the species. Finally, some 14C datings go back to ca. 200 years BP, which is approximately the average age of concerned clusters. This body of evidence leads us to conclude on an ancient form of shifting cultivation as the most likely origin of the assamela populations currently present in southeastern Cameroon. In addition to its current population structure within the study area, several parameters controlling its population dynamics were estimated. While the annualized natural mortality of the species reaches about 1%, its average diameter growth rate is 0.31 cm.year-1, which is a relatively low value compared to other long-lived light-demanding species. Selective logging seems to have only a light influence on the behavior of the species. On the other hand, the impact of logging on its seed tree populations is only ca. 12%. Each seed tree bears fruit on average only once every five years. The minimum diameter of reproduction and the effective flowering diameter were respectively 32 and 37 cm. The recovery rate, varying greatly from one country to another, is more than 100% in Cameroon, where the conservation status assigned to the species seems excessive. A sufficient regeneration by planting should allow the perpetuation of the assamela populations in the long run, as with other major logged light-demanding trees. [less ▲]

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See detailGPS et topographie : erreurs, précision et perspectives futures
Wautelet, Gilles ULg

Conference given outside the academic context (2013)

En topographie moderne, le système GPS (Global Positioning System) permet de mesurer sa position en temps réel avec une précision centimétrique. Ce niveau de précision est atteint grâce à l'utilisation de ... [more ▼]

En topographie moderne, le système GPS (Global Positioning System) permet de mesurer sa position en temps réel avec une précision centimétrique. Ce niveau de précision est atteint grâce à l'utilisation de la technique appelée Real-Time Kinematics (RTK), qui se base sur un réseau de stations permanentes. La précision de la position calculée par RTK varie avec les conditions géométriques de la constellation GPS et dépend également de différentes sources d'erreurs, comme l'effet de l'atmosphère terrestre. Après un bref rappel théorique sur le fonctionnement du GPS, ces différentes sources d'erreur sont présentées, ainsi que leur impact sur le positionnement RTK. Enfin, l'avenir du RTK est évoqué avec, notamment, l'apport de la future constellation européenne Galileo. [less ▲]

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See detailSoil infrastructure evolution and its effect on water transfer processes under contrasted tillage systems with preliminary results of soil moisture sensor calibration
Parvin, Nargish ULg; Degré, Aurore ULg; Garré, Sarah ULg et al

Poster (2013, December 05)

The heterogeneity of soil structure and porosity are highly influenced by external factors like tillage systems and other land management approaches. The aim of this project is to investigate the effect ... [more ▼]

The heterogeneity of soil structure and porosity are highly influenced by external factors like tillage systems and other land management approaches. The aim of this project is to investigate the effect of soil tillage along with residue management on the changing pattern of soil structure. This investigation will help to emphasize the different water flow dynamics especially the preferential flow processes through the soil that are influenced by the changes in structural distribution in the soil profile. Mostly the preferential flow of water is addressed by the apparent velocity through the soil but this study will focus on soil structure along with soil moisture dynamics at aggregate scale or more specifically at pedon scale. The experimentation has been started from June 2013 in the research field known as Solcouvert (objects: strip-till (ST) versus winter ploughing (WP)) and Solresidus (objects: no-till with organic matter restitution (NI) versus no-till without organic matter restitution (NO)). Soil profile description has been carried out in the four objects of land management. Soil sampling has been done in different depths of soil according to the soil profile description. Soil samples will be used for the measurement of water retention capacity, hydraulic conductivity and x-ray microtomography. In addition, there will be soil moisture sensors (Decagon 10HS, 5TM and ML3 Thetaprobe) in the field under four different trials. The soils from the different trials and also from different depths (0-15, 25-30 and 50-60 cm) were calibrated with the sensors. The calibration results were significantly (p<0.05) different between Solcouvert and Solresidus and there was also significant (p<0.05) difference among depths of same field especially between 0-15 and 50-60 cm. Soil bulk density and textural differences are the main reason for the differences of moisture content of different sites and depths measured by the moisture probes. In addition, the results were inconsistent along with overestimation of moisture content if the manufacturer based equation is used for the calibration. In our study, to capture the total soil moisture networks, the moisture sensors will be in the field in winter to spring and summer to autumn. All the experiments will be repeated twice a year. For the specific spatio-temporal comparison, the monitoring results from electrical resistance tomography will be available from the collaborated project of the same faculty. [less ▲]

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See detailThe co-production of genetically modified soy and Argentina
Delvenne, Pierre ULg

Scientific conference (2013, December 05)

Detailed reference viewed: 7 (0 ULg)