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See detailÉmile de LAVELEYE (1822-1892) et le « bon » gouvernement
Grandjean, Geoffrey ULiege

Conference (2017, September 20)

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See detailBreed fast, die young - Demography of a Neotropical fossorial frog
Székely, Diana ULiege; Székely, Paul; Stănescu, Florina et al

Poster (2017, September 19)

Information regarding age- and size-related parameters is of paramount importance both to understanding the life-history of populations, and for designing effective conservation strategies; however, such ... [more ▼]

Information regarding age- and size-related parameters is of paramount importance both to understanding the life-history of populations, and for designing effective conservation strategies; however, such base-line data lacks for many species, especially for those inhabiting tropical habitats. Using skeletochronology, we provide the first detailed information regarding the demography of the Pacific horned frog, Ceratophrys stolzmanni, a vulnerable, fossorial amphibian, that lives in the Tumbesian dry-forests of Ecuador. The species shows an intense growth rate during the first activity season, both before and after metamorphosis. Sexual maturity is achieved by both sexes before the first year of life, after which growth rates abruptly decrease. Females are on average larger, but not older, than males, mean age being two years in both sexes. The rapid sexual maturation is associated with a short life-span, the observed maximum longevity being three years in males and four years in females. The short reproductive life-span, which offers few mating opportunities, might have important implications for the conservation of this species, that can be especially at risk in the case of prolonged droughts expected to affect its habitat. [less ▲]

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See detailStochastic multiscale modeling of MEMS stiction failure
Hoang Truong, Vinh ULiege

Doctoral thesis (2017)

In the context of microelectromechanical systems, due to their reduced size, the surface phenomena, e.g. adhesion contact, play an important role in the reliability of the devices. Indeed, the adhesive ... [more ▼]

In the context of microelectromechanical systems, due to their reduced size, the surface phenomena, e.g. adhesion contact, play an important role in the reliability of the devices. Indeed, the adhesive forces, e.g. capillary and van der Waal forces, can lead to the stiction failure for which the two contacting surfaces can accidentally be stuck together permanently. This is a common failure of MEMS. Because of the comparability between the roughness of the contacting surfaces and the ranges of adhesive stress, the interaction area can be much smaller than the apparent one. Since the contact zone is reduced and becomes comparable with the characteristic length scale of the surface roughness, the behaviors of micro structures subjected to adhesion suffer from a scatter, i.e. while some devices are unstuck, the others with an identical design are stuck. The objective of this work is to predict in a probabilistic way the adhesion behaviors of MEMS by accounting for the randomness of the contacting surfaces. The straightforward solution toward this end consists in constructing a numerical model, e.g. using finite element method, and in performing a Monte-Carlo simulation (MCS) directly on that model. Because the problem spans multiple scales, including the nanometers range of adhesive stress and the micrometers length scale of MEMS, that method demands a huge computational cost and becomes unpractical. In this work, a stochastic model-based multiscale method is developed to fulfill the predefined objective while remaining efficient in terms of computational cost. In this model, MCS is also per- formed, however, in a scale-by-scale way. With this method, the model is executed with acceptable computational cost. To verify the proposed model, a comparison in terms of the numerical predictions obtained from two approaches, direct MCS and stochastic model-based method, is performed. Furthermore, the model is applied to simulate the stiction tests reported in the literature, and also on the experimental surfaces fabri- cated by our partner at IMT-Bucharest lab 1 (without stiction test). By comparing the numerical predictions with the experimental results, the model is then validated. The model is used to broaden our knowledge in stiction phenomenon by considering the effects of the following aspects on the adhesion energies: the roughness of surfaces, the non-Gaussianity in the probability distribution of surface heights, and the humidity of the environment conditions. Furthermore, the comparison between different sources of uncertainty, e.g. due to the surfaces roughness and in the geometry dimensions of the devices, is performed. [less ▲]

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See detailThe Cassini-Huygens mission: tale of a 13-year journey in the Saturnian system
Palmaerts, Benjamin ULiege

Conference (2017, September 19)

On the 15th of September 2017, the Cassini spacecraft will plunge into the atmosphere of Saturn, making the end of the successful Cassini-Huygens mission. During this unprecedented mission, Cassini will ... [more ▼]

On the 15th of September 2017, the Cassini spacecraft will plunge into the atmosphere of Saturn, making the end of the successful Cassini-Huygens mission. During this unprecedented mission, Cassini will have spent 13 years around Saturn, achieving almost 300 orbits around the planet and continuously collecting observations of Saturn, its rings, moons and space environment. In this talk, after a short introduction about the genesis of the Cassini mission, I will give a review of all the important results of the mission. The dynamics of Saturn's atmosphere and magnetosphere will be discussed, as well as the discoveries about the evolution of the rings. An important part of the presentation will be also devoted to the moons Titan and Enceladus which both exhibit striking characteristics. [less ▲]

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See detaila journey through stable isotopes applications in trophic ecology
Lepoint, Gilles ULiege

Learning material (2017)

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See detailIdentification and quantitation of intact virus-like particles of human papillomavirus (HPV-VLP) using capillary electrophoresis
Bettonville, Virginie ULiege; Nicol, Jérôme; Furst, Tania et al

Conference (2017, September 19)

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See detailSimple LC Isocratic Methods Development, Validation, and Application in the Analysis of Poor Quality Antimalarial Medicines
Habyalimana, Védaste ULiege; Mbinze Kindenge, Jéremie; Yemoa Loconon, Achille et al

in American Journal of Analytical Chemistry (2017), 8

Liquid chromatographic methods in isocratic mode for the analysis of poor quality medicines are privileged due to their simplicity and facility in methods development. They are generally fast; do not need ... [more ▼]

Liquid chromatographic methods in isocratic mode for the analysis of poor quality medicines are privileged due to their simplicity and facility in methods development. They are generally fast; do not need to be re-equilibrated between sample injections; have larger flexibility with acceptable changes on different column dimensions; and are applicable to LC systems equipped with simple or high developed pumps. In this study, we focused on developing simple isocratic methods using classical mobile phase composed by methanol and ammonium formate buffer for the analysis of most common antimalarial medicines marketed in malaria endemic countries and susceptible of being counterfeit/falsified, substandard and degraded. The selected medicines were quinine and related cinchona alkaloids in tablets and injectable forms; artemether/ lumefantrine tablets; and artemisinin compounds (arteether, artemether, and artesunate) in injectable forms. The current methods were developed thanks to simple methodological approach consisting in sequential isocratic runs through adjustment or adaptation of existing methods to obtain optimal analytical conditions without complex design of experiments that might be long and costly. Then, the new methods presented shorter analysis time; allowed increase of sample analysis throughput; and obviously consumed little mobile phase solvents on classical analytical columns: 50 - 250 mm of length (L), 4.6 mm of internal diameter (I.D.), and 3.5 - 5.0 μm of particle size (dp). [less ▲]

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See detailDecades of self-management: A story of distinctiveness and ideology
Soetens, Aurélie ULiege

Scientific conference (2017, September 19)

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See detailRegards sur la crise politique francophone et perspectives pour les futures élections.
Verjans, Pierre ULiege

Conference given outside the academic context (2017)

La motion de méfiance constructive votée par le CDH à la Région wallonne aura des conséquences sur les prochaines élections s'ajoutant aux effets de la décrédibilisation du PS à la suite de la ... [more ▼]

La motion de méfiance constructive votée par le CDH à la Région wallonne aura des conséquences sur les prochaines élections s'ajoutant aux effets de la décrédibilisation du PS à la suite de la dénonciation des affaires Publifin et Samusocial. Peut-on anticiper ces effets? [less ▲]

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See detailIntroduction
Grodent, Denis ULiege

Learning material (2017)

Introduction

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See detailAtmospheric structure
Grodent, Denis ULiege

Learning material (2017)

Atmospheric structure

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See detailDenitrification, anaerobic ammonium oxidation, and dissimilatory nitrate reduction to ammonium in an East African Great Lake (Lake Kivu)
Roland, Fleur ULiege; Darchambeau, François; Borges, Alberto ULiege et al

in Limnology and Oceanography (2017)

We investigated anaerobic nitrogen (N) cycling in the water column of Lake Kivu, a deep meromictic tropical lake in East Africa. Data were collected at one station in the Northern Basin and one in the ... [more ▼]

We investigated anaerobic nitrogen (N) cycling in the water column of Lake Kivu, a deep meromictic tropical lake in East Africa. Data were collected at one station in the Northern Basin and one in the Southern Basin, during two sampling campaigns (June 2011—dry season, and February 2012—rainy season). Short-term incubations of sulfide-free water with 15N-labeled substrates revealed high potential denitrification and dissimilatory nitrate reduction to ammonium (DNRA) rates (up to 350 and 36 nmol N produced L−1 h−1, respectively), while anaerobic ammonium oxidation (anammox) was lower (up to 3.3 nmol N produced L−1 h−1). However, anammox rates were 15 nmol N produced L−1 h−1 when 15 NH4+ was added at depths where NH4+ concentrations were very low (< 1 μmol L−1). With the addition of 5 μmol L−1 of 15 NO3− and 10 μmol L−1 of H2S, denitrification and anammox were stimulated in the Northern Basin, while the increase of DNRA rates was less notable. In the Southern Basin, the addition of H2S decreased denitrification rates, probably because of competition with DNRA, which increased, while no effect was observed on anammox. This study puts into evidence the co-occurrence of denitrification, anammox and DNRA, for the first time in a great tropical lake, and underlines the spatial heterogeneity of these processes. Contrary to numerous reports in literature, we show that anammox can significantly occur in presence of H2S, suggesting that the contribution of anammox in the N cycle may be underestimated. [less ▲]

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See detailClostridium difficile in beef cattle farms, farmers and their environment: assessing the spread of the bacterium
Rodriguez Diaz, Cristina ULiege; Hakimi, Djalal-Eddine; Vanleyssem, Raphael et al

in Veterinary Microbiology (2017), 2010

n recent years, several studies have described the presence of Clostridium difficile in healthy and diarrhoeic farm and domestic animals. In pigs and cattle, the isolation of some PCR-ribotypes associated ... [more ▼]

n recent years, several studies have described the presence of Clostridium difficile in healthy and diarrhoeic farm and domestic animals. In pigs and cattle, the isolation of some PCR-ribotypes associated with human infection, especially PCR-ribotypes 014 and 078, has led us to hypothesize about the zoonotic transmission of C. difficile infections. If these animals are reservoirs of C. difficile, farmers in close contact with their animals are particularly at risk of acquiring and spreading the bacterium. This study investigates the presence of C. difficile in closely associated populations, beef cattle and farmers, as well as in the animal feed, manure and dust in five different farms in Belgium. C. difficile was isolated from calves and cattle with a prevalence varying between 5.5% and 11.3%. Furthermore, all of the isolates were toxigenic. An important age and breed effect was observed in the colonization of C. difficile. For age, there was a higher probability of colonization in calves of less than 6 months in age than in cattle over 11 months of age. For the type of breed a higher prevalence of the bacterium was detected in the Limousin breed than in the Belgian Bleu breed. By contrast, none of the human and animal feed samples tested positive for C. difficile. The results obtained indicate a persistent animal reservoir of C. difficile, but an indirect dissemination to humans, probably via the environment. [less ▲]

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See detailChallenges in the determination of amyloid oligomeric species by two electrophoretic techniques
Napp, Aurore ULiege; Houbart, Virginie ULiege; Demelenne, Alice ULiege et al

Poster (2017, September 18)

Parkinson’s disease is a frequent degenerative disorder, and for the moment the diagnosis is mainly clinical. When the first symptoms appear, loss of more than 70% of the dopaminergic cells already ... [more ▼]

Parkinson’s disease is a frequent degenerative disorder, and for the moment the diagnosis is mainly clinical. When the first symptoms appear, loss of more than 70% of the dopaminergic cells already occurred. Knowing that, it is of high interest to have one (or more) reliable biomarker(s) at our disposal to diagnose Parkinson before the first symptoms appear. Alpha-synuclein (aSyn) is a protein physiologically expressed at high level by neuronal cells, under a monomeric form. This protein would play a critical role in the development of the disease because under certain conditions, aSyn is capable of self-assembly to form fibrils like those found in Lewy bodies. Other intermediate soluble forms like dimers and oligomers are also formed. As these forms seems to be the toxic species, they are the center of many attentions. The quantification of each form would be a great help, but for the moment only the total forms (of monomeric or oligomeric) can be quantified. In this study, aSyn oligomers were generated after optimization of incubation conditions (pH, temperature, agitation, …). Then, different approaches were investigated to detect and follow the different species formed during the aggregation. We analyzed the oligomers by capillary gel electrophoresis (CGE) and SDS-PAGE. We found that capillary gel electrophoresis is a promising automated technique to analyze aSyn oligomers, due to the fact that it separates the aggregates according to their size, like the SDS-PAGE, but with more advantages. To gain sensitivity and selectivity by CGE, we used a laser-induced fluorescence detector. As aSyn do not have a native fluorescence, we derivatized it. After careful screening and optimization of various derivatization reagents, we could quantify with high sensitivity aSyn oligomers by CGE-LIF. We realized different calibration curves, and we had promising results that will allow us to quantify the different aSyn oligomeric forms in biological fluids. [less ▲]

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See detailA SPRAY DRYING METHOD FOR THE PREPARATION OF Na2FePO4F/CB AND Na2FePO4F/CNT COMPOSITES CATHODE FOR LITHIUM-ION BATTERIES
Mahmoud, Abdelfattah ULiege; Berardo, Loris ULiege; Brisbois, Magali et al

Poster (2017, September 18)

Fluorophosphates are considered among the most interesting series of cathode material for Li/Na-ion batteries1. Na2FePO4F (space group Pbcn), with its layered structure and two-dimensional pathways for ... [more ▼]

Fluorophosphates are considered among the most interesting series of cathode material for Li/Na-ion batteries1. Na2FePO4F (space group Pbcn), with its layered structure and two-dimensional pathways for facile Na+/Li+ transport, exhibits minimal structural changes upon reduction/oxidation. The average working voltage is 3.3 V vs. Li/Li+. Intercalation/deintercalation results in a volume change of only 3.7%. However, one of the key drawbacks of Na2FePO4F electrodes is their low intrinsic electronic conductivity. In order to study the effect of the carbon black and carbon nanotubes on the electrochemical performance of Na2FePO4F cathode material for lithium-ion batteries, Na2FePO4F, Na2FePO4F/CB and Na2FePO4F/CNT were prepared by a spray-drying method with different ratios of CB and CNT (10 and 20%). The crystal and local structure were analyzed by XRD and Mössbauer spectroscopy. The electrochemical properties were studied by galvanostatic cycling in lithium cells. The electrochemical performance is markedly better in the case of Na2FePO4F/CNT (20 wt%), with specific capacities of about 100 mAh/g (Na2FePO4F/CNT) at C/4 rate2 vs. 50 mAh/g for Na2FePO4F/CB. The characterization of Na2FePO4F/CB particles by electron microscopy revealed a carbon-poor surface and a good carbon dispersion for Na2FePO4F/CNT particles attributed to better diffusion of carbon nanotubes in the droplets during drying. References : 1-N. Eshraghi, S. Caes, A. Mahmoud, R. Cloots, B. Vertruyen, F. Boschini, Electrochim. Acta, 228 (2017) 319–324. 2-M. Brisbois, S. Caes, M-T. Sougrati, B. Vertruyen, A. Schrijnemakers, R. Cloots, N. Eshraghi, R-P. Hermann, A. Mahmoud, F. Boschini, Solar Energy Materials & Solar Cells 148 (2015) 67-72. [less ▲]

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See detailPlanetary missions in the STAR institute
Palmaerts, Benjamin ULiege

Scientific conference (2017, September 15)

Quick overview of all the current and future planetary missions in which the STAR institute is involved.

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See detailSurface Micro & Nano Engineering Lab Presentation
Fleury-Frenette, Karl ULiege

Scientific conference (2017, September 15)

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See detailHow classroom teachers do take the ‘Physical Activity Pauses at School’ (PAPS)? A project implemented in Wallonia
Cloes, Marc ULiege; Cloes, Stéphanie

Conference (2017, September 15)

In Wallonia, special efforts are needed in order to respect the international recommendations on physical activity in youth. School is definitely considered as a central pillar in the promotion of an ... [more ▼]

In Wallonia, special efforts are needed in order to respect the international recommendations on physical activity in youth. School is definitely considered as a central pillar in the promotion of an active lifestyle. The aim of this study was to analyze the implementation process of daily activity breaks called ‘Physical Activity Pause at School’ (PAPS) in 6 primary schools of the Liege area. 23 classroom teachers were involved. They had to propose at least one PAPS/day during the 15-16 school year. Diary, questionnaires, focus groups and interviews were used for data collecting. Two thirds of the subjects continued until the end. The videos were not systematically used. Four teachers’ profiles were identified: Innovators, Invested, Careful, and Disengaged. 12 factors facilitating or limitating the involvement of the teachers have been analyzed. The study comes to a model of concrete actions to respect in order to increase the chances of success in the implementation of such project. [less ▲]

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