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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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See detailRuralité et mondialisation dans l'oeuvre de Josef Winkler
Neelsen, Sarah ULiege

Conference (2017, September 15)

Une œuvre à ce point enracinée dans le paysage, la culture et la langue de l’Autriche semblait peu propice à intégrer les bouleversements de l’ordre mondial après 1989 et son auteur bel et bien enfermé ... [more ▼]

Une œuvre à ce point enracinée dans le paysage, la culture et la langue de l’Autriche semblait peu propice à intégrer les bouleversements de l’ordre mondial après 1989 et son auteur bel et bien enfermé dans une certaine tradition nationale. Pourtant à partir de 1996, les récits de voyage, journaux intimes et romans sur l'Inde se multiplient. La mondialisation semble donc bien avoir eu un impact profond sur son travail et l'étude approfondie du roman Roppongi montre comment se construisent des effets de résonance entre rituels funéraires hindous et catholiques. Cette communication analyse les différences entre interculturalité et mondialisation, lieux et non-lieux et conclut sur la tension entre la mobilité des corps et l'obsession de l'image fixe. [less ▲]

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See detailIdentification of Signaling Pathways Regulating Beta Cell Regeneration in Zebrafish
Massoz, Laura; Bergemann, David ULiege; Lavergne, Arnaud ULiege et al

Conference (2017, September 15)

Diabetes is becoming a leading health issue worldwide. It occurs under insulin resistance/deficiency and when insulin-producing pancreatic beta-cell mass is dramatically reduced. Besides therapeutic ... [more ▼]

Diabetes is becoming a leading health issue worldwide. It occurs under insulin resistance/deficiency and when insulin-producing pancreatic beta-cell mass is dramatically reduced. Besides therapeutic strategies to preserve beta-cell mass and function and improve insulin treatments, beta-cell replacement constitutes a promising alternative to replenish the pancreas with functional beta-cells. Beta-cell neogenesis can be achieved from different pancreatic cell types leading to the hope that triggering regeneration could be harnessed in future therapies. Still, mammals show limited regenerative capabilities, making difficult the study of these mechanisms. In contrast, zebrafish is extensively used for regeneration studies notably of beta-cells. We recently showed that the adult zebrafish ducts display characteristics of embryonic pancreatic progenitors that give rise to beta-cells in physiological and induced diabetic condition*. To better understand the molecular mechanisms underlying this potential, genes and signaling pathways regulated in the zebrafish pancreatic ducts after beta-cell ablation have been identified by transcriptomic profiling. For functional studies, we have developed an assay using 7-20 days old larvae to investigate the role of selected candidate pathways in beta-cell regeneration with pharmacological inhibitors/activators and by transgenic overexpression of candidate signaling factors. These results should provide new hints to help improve regenerative competences in mammals. [less ▲]

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See detailFatigue resistant designs using stress-based topology optimization
Collet, Maxime ULiege; Bauduin, Simon ULiege; Fernandez Sanchez, Eduardo Felipe ULiege et al

Conference (2017, September 15)

Fatigue is an important mode of failure in mechanical engineering and accounting for it as soon as the early stage of design using topology optimization sounds primordial. Structures undergoing high-cycle ... [more ▼]

Fatigue is an important mode of failure in mechanical engineering and accounting for it as soon as the early stage of design using topology optimization sounds primordial. Structures undergoing high-cycle fatigue can be described by the stress-based approach and then a stress-based topology optimization framework, which has received great interest since almost 20 years because of the innovative designs that can be achieved to answer strength requirements, can be used. Literature reports many good results for shape optimization [Mrzyglod & Zielinsky(2006)] whereas in the eld of topology optimization several authors have shown that considering fatigue in an optimization framework leads to more relevant solutions where fluctuating loads are involved [Holmberg E.(2015), Collet et al(2016), Sv ard(2015)]. The good behaviour of the implementation of an advanced fatigue criterion, i.e. the multiaxial Dang Van criterion [Dang Van et al(1989)] is first investigated in the framework of a density-based topology optimization problem. The choice of this fatigue criterion is justifed by its good applicability in automotive or aeronautic industry as well as its relevancy with respect to experimental results. We present the sensitivity analysis with stress constraints and present some classical benchmarks to illustrate the behaviour of the optimized solution. In a second time, the fatigue resistance is introduced in the well-known microstructural design [Sigmund (2000)] also know as architectured material design which are now considered in mechanical engineering because of their manufacturability thanks to additive manufacturing processes. Ensuring the fatigue resistance of the cellular material will by extension ensure the structural integrity of the overall structure itself. The optimization is performed by using the MMA optimizer [Svanberg(1987)] whereas the singularity phenomenon of the stress constraints is circumvented by using the qp-relaxation [Bruggi(2008)]. Both types of optimization framework are evaluated in term of their numerical performances and are compared to classical results generated by a regular stress-based topology optimization. Finally, the results are 3D-printed to assess for their manufacturability. [less ▲]

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See detailLe transfert de connaissances en promotion de la santé vers les décideurs et acteurs institutionnels
Nisen, Laurent ULiege

Speech/Talk (2017)

allocution de clôture, en réaction aux interventions des ministres en charge et de différents experts du secteur

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See detailThe Synthesis and Evaluation of [18F]BPAM121: Potential of an AMPA Receptor Positive Allosteric Modulator
Manos-Turvey, Alexandra ULiege

Speech/Talk (2017)

AMPA receptors (AMPARs), one of three sub-groups of ionotropic glutamate receptors present in the central nervous system, are recognised for their involvement in long-term potentiation (LTP), and learning ... [more ▼]

AMPA receptors (AMPARs), one of three sub-groups of ionotropic glutamate receptors present in the central nervous system, are recognised for their involvement in long-term potentiation (LTP), and learning and memory processes.1 They represent a valid cognitive enhancer target, particularly in the fight against Alzheimer’s disease (AD).2,3 Benzothiadiazine 1,1-dioxides, such as BPAM121, have emerged as important allosteric modulators of AMPARs, working solely in the presence of the endogenous transmitter.4 Synthesis of BPAM121 labelled with fluorine-18 was proposed, to investigate the utility of this molecule as a PET probe in vivo, and evaluate its potential as an AD diagnostic tool (Figure 1). Figure 1. a) Structure of BPAM121, b) Established radiochemical synthesis of [18F]BPAM121 This work documents the successful optimization of synthesis, purification and formulation of [18F]BPAM121 using an automated FASTlab (GE Healthcare) synthesizer. In particular, the influence of higher-level [18F]fluoride ion starting concentrations on final product formulation requirements is discussed. Finally, results from biological studies of [18F]BPAM121, confirmed to successfully pass the blood brain barrier, are discussed. [1] S. F. Traynelis et al., Pharmacol. Rev. 2010, 62, 405-496. [2] J. Keifer, Z. Zheng, Eur. J. Neurosci. 2010, 32, 269-277. [3] L. Gao et al., J. Neurochem. 2016, 136, 620-636. [4] P. Francotte et al., J. Med. Chem. 2010, 53, 1700-1711. [less ▲]

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See detailEnvironmental sustainability of the Walloon cereal sector using Life Cycle Assessment (LCA) fed with local data - Current situation and potential evolution scenarios
Van Stappen, Florence ULiege

Doctoral thesis (2017)

In a world facing a growing population and diminishing resources, agriculture has a major role to play in terms of sustainable provision of food and feed, job creation in rural areas, preservation of ... [more ▼]

In a world facing a growing population and diminishing resources, agriculture has a major role to play in terms of sustainable provision of food and feed, job creation in rural areas, preservation of natural resources and climate change mitigation. As a very intensive agricultural region, Wallonia (southern Belgium) dedicates more than half of its arable land to cereal crops. Thanks to a long history of research and development, rich soils and favorable climate conditions, yields of cereals such as wheat or barley cropped in Wallonia are amongst the highest in the world. As a major sector in the Walloon agricultural landscape, the cereal sector therefore calls for production and processing opportunities that meet the requirements for sustainable agriculture. In this context, the objectives of the present thesis were to evaluate the environmental sustainability of current and potential evolution scenarios for the Walloon cereal sector using the Life Cycle Assessment (LCA) methodology fed with local data. On the basis of current uses of cereals grown in Wallonia, this research aimed first at describing various scenarios for the future of the Walloon cereal sector. Based on contrasting hypotheses, four scenarios for the uses of Walloon cereals by 2030 were defined with the support of stakeholders involved in all parts of the sector. Issues such as competition between food uses (both direct and indirect) and non-food uses or Walloon dependency on cereal imports were addressed in these scenarios, which illustrate contrasting future situations, from food self-sufficiency to drastic globalization, through the development of new outlets combining changes in crop-growing practices and consumption habits and new technologies. Using the widely used, yet continuously improved, methodology of LCA, the second part of this work evaluated the environmental impacts of cereal production in Wallonia. It identified the production steps with the greatest contribution to environmental impacts. The leading contributor was mineral fertilizer production, for which this work used up-to-date data from best available technologies and demonstrated the importance of using such recent data. The second greatest contributor to environmental impacts was emissions from mineral and organic fertilizer use on field, before and during plant growth until harvest. As well as being very important, these emissions are also extremely variable, depending on agricultural practices, soil and weather conditions, and thus particularly difficult to assess. This is particularly true of nitrogen- and carbon-related emissions, whose dynamics are very problematic to evaluate. This work demonstrated the limits of commonly used emission models, which use generic emission factors and therefore weaken LCA results. As a result, the use of more specific models, based on field trials and adapted to local conditions, was placed at the top of the list for future research in this area. From a methodological point of view, this part of the work also confirmed the influence of the functional unit used to express LCA results. It showed the strong link between yield and environmental impacts, and identified cereal crops demonstrating efficient input management, with lower impacts per kilogram of product, per hectare and per euro. Other methodological choices, such as the choice of allocation factor between grain and straw, also showed their relevance. In short, this part of the work demonstrated the pertinence of using local data to feed LCAs of agricultural productions and identified the most sensitive parameters to be adjusted in priority to achieve good quality LCAs. Thirdly, on the basis of an original methodology comparing equivalent balanced animal diets, a case study on cereal processing in a biogas plant assessed the consequences of diverting feedstock from the animal feed industry into the bioenergy sector. Despite the environmental benefits brought by fossil fuel displacement and digestate use as organic fertilizer, the replacement of raw materials previously used as animal feed induces additional impacts potentially more important than the benefits of this technology. The key message from this finding is that it is urgent to stop using potentially edible raw material for bioenergy production. The only countervailing consideration here is that current trends towards decreasing meat consumption would in the longer term make lands and raw material available for purposes other than animal feed. The strength of all the LCA results in this work was tested using a wide range of sensitivity and uncertainty analyses. These good practices, often neglected due to time constraints, proved to be essential to be able to draw robust conclusions. Through the application of LCA to the Walloon cereal sector, this work had some practical implications for enhancing the quality of LCAs of agricultural productions. It showed the sensitivity of the method to the use of local data and demonstrated the strengths and limitations of the method. It has produced specific LCA references for cereal production in Wallonia, which are useful for feeding environmental impact assessments of cereal-based products sourced with Walloon cereal crops. Further improvements could include the use of specific models to assess on-field emissions from fertilizer use and the consideration of additional impact indicators regarding soil organic stock changes, biodiversity impacts and water consumption. Additionally, assessing impacts at the rotation scale would reflect more accurately the way farmers optimize their crops and allow for the evaluation of more diverse cropping systems. [less ▲]

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See detailOf trees and men: new insights into man-environment relationships in the moist forests of central Africa during the late Holocene
Morin, Julie ULiege

Doctoral thesis (2017)

In central Africa, vegetation history has been documented by paleoenvironmental studies (especially palynology), which mainly concerned the way climate has shaped the forest landscapes. Human impacts in ... [more ▼]

In central Africa, vegetation history has been documented by paleoenvironmental studies (especially palynology), which mainly concerned the way climate has shaped the forest landscapes. Human impacts in this region have hardly been studied so far, especially at local scale. The main objective of this PhD is to propose an approach based on archaeology and the use of charred botanical remains found in soils, either wood charcoal or seeds, in order to document the Holocene anthropogenic impacts on the forest structure and composition. When coupled with the diachronic analysis of human activities, these land-use biomarkers can allow a better understanding of the relationship between man and his environment in central Africa during this period. Thereby, the first part of this PhD introduces the conceptual framework and the materials and methods used during the research. Then, the second part constitutes the core of the work, and presents the chronology of human activities in the northern Congo Basin, the use of biomarkers to discrimate between these activities, either domestic or agricultural, and the effect of the recent anthropogenic activities in the dynamic of several light-demanding tree populations. Finally, the third part draws the main recommendations of the work, and formulates potential for additional research. [less ▲]

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See detailPhysics at the Ultra-high Energies
Bhattacharya, Atri ULiege

Scientific conference (2017, September 15)

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See detailThe Einstein Telescope
Cudell, Jean-René ULiege

Speech/Talk (2017)

Brief description of the Einstein Telescope project.

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See detailDark matter
Laletin, Maxim ULiege

Scientific conference (2017, September 15)

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