Last 7 days
Bookmark and Share    
See detailSeasonal Transport in Mars’ Mesosphere revealed by Nitric Oxide Nightglow
Stiepen, Arnaud ULg

Conference (2017, June 21)

We analyze the ultraviolet nightglow in the atmosphere of Mars through Nitric Oxide (NO) δ and γ bands emissions. On the dayside thermosphere of Mars, solar extreme ultraviolet radiation partly ... [more ▼]

We analyze the ultraviolet nightglow in the atmosphere of Mars through Nitric Oxide (NO) δ and γ bands emissions. On the dayside thermosphere of Mars, solar extreme ultraviolet radiation partly dissociates CO2 and N2 molecules. O(3P) and N(4S) atoms are carried by the day-to-night hemispheric transport. They preferentially descend in the nightside mesosphere in the winter hemisphere, where they can radiatively recombine to form NO(C2Π). The excited molecules promptly relax by emitting photons in the UV δ bands and in the γ bands through cascades via the A2Σ, v’ = 0 state. These emissions are thus indicators of the N and O atom fluxes transported from the dayside to Mars’ nightside and the winter descending circulation pattern from the nightside thermosphere to the mesosphere (e.g. Bertaux et al., 2005 ; Bougher et al., 1990 ; Cox et al., 2008 ; Gagné et al., 2013 ; Gérard et al., 2008 ; Stiepen et al., 2015, 2017). Observations of these emissions have been accumulated on a large dataset of nightside disk images and vertical profiles obtained at the limb by the Imaging Ultraviolet Spectrograph (IUVS, McClintock et al., 2015) instrument when the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft is at its apoapsis and its periapsis phases along its orbit, respectively. We present discussion on the variability in the brightness and altitude and of the emission with season, geographical position and local time and possible interpretation for local and global changes in the mesosphere dynamics. IUVS images and limb scans reveal unexpected complex structure of the emission. The brightest emission is observed close to the winter pole. The emission is also surprisingly more intense in some longitude, revealing possible impact of tides and waves in Mars’ nightside mesosphere. Observations also reveal spots and streaks, indicating irregularities in the wind circulation pattern. The disk images and limb profiles are compared to the LMD-MGCM model (Gonzàlez-Galindo et al., 2009 ; Lopez-Valverde et al., 2011) to focus on the seasonal, local time and geographical influences on the NO Nightglow emission. We will also provide a statistical study of the regions of enhanced brightness (i.e. splotches and streaks) and discuss possible interpretation from the comparison to the GCM. [less ▲]

Detailed reference viewed: 19 (1 ULg)
Full Text
See detailL’art de gouverner les régions par les finances publiques
Piron, Damien ULg

Conference (2017, June 21)

Detailed reference viewed: 22 (1 ULg)
Full Text
See detailConclusions of the 6th European Drying Conference
Léonard, Angélique ULg

Conference (2017, June 21)

Detailed reference viewed: 28 (1 ULg)
Full Text
See detailImpact of conditioning on sludge internal structure evolution during drying
Fraikin, Laurent ULg; Pambou, Yvon Bert; Salmon, Thierry ULg et al

Conference (2017, June 20)

This paper investigated the influence of dual conditioning of waste water treatment sludge on the evolution of sludge internal structure during convective drying. Results showed clearly an impact of ... [more ▼]

This paper investigated the influence of dual conditioning of waste water treatment sludge on the evolution of sludge internal structure during convective drying. Results showed clearly an impact of chemical conditioners on the evolution of the created porosity. For sludge flocculated by single conditioning, a centered porosity delimiting by external crust was shown, while for dual conditioning, a porosity structured in lamellae, was identified. [less ▲]

Detailed reference viewed: 8 (0 ULg)
Full Text
See detailDiametral dimension(s) and prominent bounded sets
Demeulenaere, Loïc ULg

Conference (2017, June 20)

The classical diametral dimension (Bessaga, Mityagin, Pelczynski, Rolewicz), denoted by "Delta", is a topological invariant which can be used to characterize Schwartz and nuclear locally convex spaces ... [more ▼]

The classical diametral dimension (Bessaga, Mityagin, Pelczynski, Rolewicz), denoted by "Delta", is a topological invariant which can be used to characterize Schwartz and nuclear locally convex spaces. Mityagin also introduced a variant of this diametral dimension, denoted by "Delta_b", using bounded sets in its definition, contrary to "Delta". In this talk, we present some conditions assuring the equality of these two diametral dimensions for Fréchet spaces. Among these conditions, there is the notion of existence of prominent bounded sets, due to Terzioglu. In fact, it appears that the existence of prominent sets is implied by the property "Omega Bar" of Vogt and Wagner. Finally, we describe a construction which gives Schwartz and nuclear non-Fréchet spaces E verifying "Delta_b(E) = \Delta(E)". [less ▲]

Detailed reference viewed: 26 (3 ULg)
Full Text
See detailLe pouvoir politique des juges
Grandjean, Geoffrey ULg

Conference given outside the academic context (2017)

Notre société est marquée par un phénomène de judiciarisation qui voit une emprise croissante des juges dans les systèmes politiques et sociaux. Certains représentants n'hésitent d'ailleurs plus à ... [more ▼]

Notre société est marquée par un phénomène de judiciarisation qui voit une emprise croissante des juges dans les systèmes politiques et sociaux. Certains représentants n'hésitent d'ailleurs plus à fustiger le « gouvernement des juges ». Quels pouvoirs les juges exercent-ils dans nos systèmes démocratiques ? Pour répondre à cette question, il est proposé de présenter les trois grandes fonctions politiques des juges : 1) la production de normes, 2) l'arbitrage de valeurs morales et 3) la stabilisation du système politique. Ces trois fonctions sont autant de déclinaisons du pouvoir politique des juges qui concrétisent un nouvel équilibre entre les pouvoirs. De nombreuses décisions de jurisprudence illustrent le propos. [less ▲]

Detailed reference viewed: 74 (0 ULg)
Full Text
Peer Reviewed
See detailMorphology Development and Mechanical Properties Variation during Cold-Drawing of Polyethylene-Clay Nanocomposite Fibers
Coppola, Bartolomeo ULg; Scarfato, Paola; Incarnato, Loredana et al

in Polymers (2017), 9(6), 235-251

In this work, the influence of composition and cold-drawing on nano- and micro-scale morphology and tensile mechanical properties of PE/organoclay nanocomposite fibers was investigated. Nanocomposites ... [more ▼]

In this work, the influence of composition and cold-drawing on nano- and micro-scale morphology and tensile mechanical properties of PE/organoclay nanocomposite fibers was investigated. Nanocomposites were prepared by melt compounding in a twin-screw extruder, using a maleic anhydride grafted linear low density polyethylene (LLDPE–g–MA) and an organomodified montmorillonite (Dellite 67G) at three different loadings (3, 5 and 10 wt %). Fibers were produced by a single-screw extruder and drawn at five draw ratios (DRs): 7.25, 10, 13.5, 16 and 19. All nanocomposites, characterized by XRD, SEM, TEM, and FT-IR techniques, showed an intercalated/exfoliated morphology. The study evidenced that the nanoclay presence significantly increases both elastic modulus (up to +115% for fibers containing 10 wt % of D67G) and drawability of as-spun nanocomposite fibers. Moreover, at fixed nanocomposite composition, the cold-drawing process increases fibers elastic modulus and tensile strength at increasing DRs. However, at high DRs, “face-to-edge” rearrangement phenomena of clay layers (i.e., clay layers tend to rotate and touch each other) arise in fibers at high nanoclay loadings. Finally, nanocomposite fibers show a lower diameter reduction during drawing, with respect to the plain system, and surface feature of adjustable roughness by controlling the composition and the drawing conditions. [less ▲]

Detailed reference viewed: 14 (2 ULg)
Full Text
See detailCharacterisation of Luvisol compaction under two different tillage systems and field traffic zones by assessing soil mechanical properties
Taguem Ngoualadjio, Eric Martial ULg; Destain, Marie-France ULg; ROISIN, Christian et al

Conference (2017, June 20)

Compaction of arable soils is a consequence of tillage systems and agricultural machinery traffic year after year. Its negative effects on crop production and on the environment have been put into ... [more ▼]

Compaction of arable soils is a consequence of tillage systems and agricultural machinery traffic year after year. Its negative effects on crop production and on the environment have been put into evidence by several studies. However, soil compaction is a complex phenomenon and the understanding of the involved mechanisms related to agricultural practices still remains limited. This contribution aims to study the influence of the interaction between traffic intensity and tillage system on soil compaction. Soil samples were taken from topsoil (0.07-0.25 m), plough pan (0.30-0.35 m) and subsoil (0.35 – 0.52 m), on plots under long-term reduced tillage (RT) and conventional tillage (CT). For each tillage system, intensive traffic zones (IT) and non-intensive traffic zones (NT) were considered. Swelling index (Cs), compression index (Cc), precompression stress (Pc) obtained by oedometer test, porosity (n) and water content obtained by gravimetric determination were chosen to characterise the soil mechanical properties. An analysis of covariance (ANCOVA) was performed to study the effect of the depth, the tillage and the traffic intensity on the variables measured, with the water content as covariable. The results show that, after ten years of reconversion from CT to RT, the plough pan is still present in RT and its compaction appears as important as in CT ( nRT-30cm = 36.9% , nCT-30cm = 38.0%, p-value = 0.098). In subsoil, the compression index was high in CT, as well as in RT (CcRT = 0.150 kPa-1, CcCT = 0.148 kPa-1, p-value = 0.617), involving that this layer remains susceptible to compaction under heavy loads. Moreover, the mean value of the precompression stress (meanPc = 92±34 kPa) remains lower than stresses induced by heavy machines such as beet harvesters. The results also show that the presence of two traffic zones induces a spatial heterogeneity in the field (CcIT = 0.138 kPa-1; CcNT = 0.154 kPa-1, p-value = 0.031). These main results could be used in computational modelling to develop decision support systems to mitigate the effects of soil compaction. [less ▲]

Detailed reference viewed: 31 (9 ULg)
See detailRachid Tahzima lauréat du journal of general virology for best oral scientific presentation award 2017
Massart, Sébastien ULg; Tahzima, Rachid

Article for general public (2017)

Detailed reference viewed: 19 (3 ULg)
See detailRelease of Neutrophils Extracellular Traps as a main trigger for asthma onset
Radermecker, Coraline ULg; Sabatel, Catherine ULg; Toussaint, Marie et al

Poster (2017, June 20)

Allergic asthma is an important Th2 associated immunopathology. Even if the pathology of the disease is well described, its etiology is still largely unknown. Nevertheless, some environmental factors like ... [more ▼]

Allergic asthma is an important Th2 associated immunopathology. Even if the pathology of the disease is well described, its etiology is still largely unknown. Nevertheless, some environmental factors like viral infections and exposition to low doses of lipopolysaccharide (LPS) strongly increase the risk of disease inception. Interestingly, these two particular risk factors both induce a strong recruitment of neutrophils into the lung. Recently, scientists highlighted the ability of neutrophils to form neutrophils extracellular traps (NETs) composed of a network of extracellular DNA associated to anti-microbial peptides. NETs release (or NETosis) is an important component in organism defence against pathogen invasion but has also been identified as initiator of pathophysiological conditions like erythematous systemic lupus, gout and diabetes. In this study, we investigated the role of NETs as potential asthma inducers in specific pro-Th2 environmental risk factors like respiratory viral infections and low LPS doses exposures (also known as hygiene hypothesis). First, we assessed the correlation between respiratory viral infection or low LPS exposure and NETosis using western blot and confocal microscopy analysis. An influenza A infection induced a strong NETs release between day three and seven after viral inoculation whereas exposition to low (100 ng LPS) but not to high (10 µg LPS) LPS doses also promoted NETosis within 24 hours following the exposition. Then we developed two mouse models, a virus-induced asthma model and a model of asthma promoted by exposition to low LPS doses. In these models, only previously infected mice or mice exposed to low LPS doses displayed all the characteristics of allergic asthma following sensitization and challenge to house dust mite (HDM). The role of NETs in asthma onset was then demonstrated using three NETosis inhibitors (DNAse, Cl-amidine and inhibitor of neutrophil elastase) in our models as infected or low LPS doses exposed mice exhibited strong decreased of all key asthma features when treated with NETs inhibitors compared to non-treated mice. Finally, to address how NETs could lead to a TH2 immune response, we analysed by flow cytometry the distinct subpopulations of lung dendritic cells (DCs) in our two mice models. We observed, during the NETs release phase, a recruitment of monocytic derived DCs (moDCs). In conclusion, we have demonstrated an unexpected role for NETs in asthma onset by recruiting lung moDCs. [less ▲]

Detailed reference viewed: 22 (1 ULg)
Peer Reviewed
See detailOptimization of an electrophoretic approach for the screening and the development of new antithrombotic drugs
Farcas, Elena ULg; Bouckaert, Charlotte; Servais, Anne-Catherine ULg et al

Conference (2017, June 20)

The discovery of lead compounds that can modulate the activity of a biological target is essential to provide efficient pharmacological tools and to serve as starting points for new drug generations ... [more ▼]

The discovery of lead compounds that can modulate the activity of a biological target is essential to provide efficient pharmacological tools and to serve as starting points for new drug generations. Fragment-based drug discovery (FBDD) approach is an attractive tool for the identification of new selective inhibitors of a target of interest, but its success largely depends on the ability to develop screening bioassays capable to detect and gauge weak affinity binders. To achieve this goal, we investigated capillary electrophoresis (CE) for identifying and ranking fragments from an initial library. Indeed, due to its ability to evaluate weak interactions, CE seems to be promising for fragment-based screening. This technique is a powerful analytical tool with a unique separation mechanism, speed, efficiency and versatility. Its main advantages are low protein consumption, higher throughput compared to NMR and X-ray crystallography and the fact that screening can be carried out using native protein in physiological solution without the need of immobilization. We developed a proof of concept study on thrombin, a serine protease implicated in the coagulation cascade using affinity capillary electrophoresis (ACE) for ranking fragments from an initial library. For this study, we followed a probe ligand, benzamidine, and we investigated interactions with the target by monitoring the changes of its electrophoretic mobility upon binding. The first step of this study consisted in the optimization of the experimental conditions suitable for the CE method (target and probe ligand concentrations, separation buffer composition, voltage, separation effective length, target partial filling…). Then, numerous thrombin inhibitors with a wide range of inhibitory potency (i.e. Ki 200 µM – 5 nM) were tested to validate our system demonstrating the possibility to fish binders in the optimized conditions. We also checked the absence of non-specific binding with the target using the inactivated enzyme at the binding site. It is noteworthy that in this operating system (ACE assay), binding occurs in free solution using physiological buffers, thus preventing artifacts that may result from target immobilization, which is a requirement for some techniques such as SPR. [less ▲]

Detailed reference viewed: 33 (13 ULg)
Peer Reviewed
See detailChromatographic analysis of alkaloids in Aconitum pollen : towards new insights in plant protection mechanisms
Vanderplanck, Maryse ULg; Glauser, Gaëtan; Tyteca, Eva ULg et al

Conference (2017, June 19)

Alkaloids are a class of naturally occurring organic nitrogen-containing bases that are found primarily in plants. They display a huge diversity with more than 3,000 different types already identified ... [more ▼]

Alkaloids are a class of naturally occurring organic nitrogen-containing bases that are found primarily in plants. They display a huge diversity with more than 3,000 different types already identified. Next to their different pharmacological and therapeutic effects, alkaloids can have a deleterious impact on organisms as they are known to be neurotoxic and cardiotoxic for mammals and insects. In the current context of worldwide bee decline, occurrence of such compounds in floral production, i.e. nectar and pollen, raises major concerns. They could be beneficial to bees by protecting them against disease and pathogens but they could also cause toxicity. Until now alkaloids, and their effect on human health, are mainly studied in vegetative parts of plants. More recently the natural occurrence of alkaloids in nectar was also studied to investigate their effect on bee health. Whereas nectar chemicals can relatively easily and quickly be analyzed by chromatography, extracting chemicals from low pollen amount remains a challenge because of pollen structure and complexity. However, characterization of pollen chemicals can lead to valuable insight in their impact on pollinators allowing the development of mitigation strategies. In this study, we used a UHPLC-(ESI)-Q-ToF/MS method allowing the identification and quantification of alkaloids in pollen matrices from four Aconitum species; A. lycoctonum, A. napellus compactum, A. napellus neomontanum and A. variegatum. Alkaloid extraction was performed using bead-beating disruption of the pollen sample and chromatographic analysis was carried out on an Acquity UPLC system interfaced with a Synapt G2 QTOF. The separation was achieved in gradient mode on an Acquity UPLC BEH C18 column and detection was performed in electrospray positive ionization mode (ES+). Alkaloid concentrations were measured as aconitine equivalents by using a pure aconitine standard as reference compound. The total amount of alkaloids in Aconitum pollen ranged from 0.75 to 1.20 mg/g with 859 different compounds detected, some of them being pollen-specific. Statistical analyses were conducted on the global dataset to assess both quantitative and qualitative interspecific differences. One-way analysis of variance was performed on the total alkaloid content while a permutational test of multivatiate analysis of variance was used to compare the alkaloid profiles among the four Aconitum species. Results are briefly discussed in an ecological context. [less ▲]

Detailed reference viewed: 37 (1 ULg)
Full Text
See detailDEVELOPMENT OF A MULTISCALE CONVECTIVE LABSCALE DRYER
Fraikin, Laurent ULg; Salmon, Thierry ULg; Léonard, Angélique ULg

Poster (2017, June 19)

The convective drying technology is currently used in many industries but the industrial process is frequently poorly mastered and some design security factors are used. The lack of optimized conception ... [more ▼]

The convective drying technology is currently used in many industries but the industrial process is frequently poorly mastered and some design security factors are used. The lack of optimized conception rules lead to large energy consumptions. In the same perspective, the use of superheated steam as drying fluid expands and requests the improvement of the knowledge about this specific drying process. For this goal, the PEP’s developed a new convective labscale dryer to conduct various studies. This article presents the new dryer called VESAC. [less ▲]

Detailed reference viewed: 36 (0 ULg)
Full Text
See detailSTUDY ON THE STRUCTURAL EVOLUTION OF SEWAGE SLUDGE DURING CONVECTIVE DRYING
Li, Jie; Fraikin, Laurent ULg; Salmon, Thierry ULg et al

Poster (2017, June 19)

The structure of the sludge sample continues changing during drying as a result of the shrinkage phenomenon. Then the exchange area becomes smaller and the drying rate decreases. The sludge collected in a ... [more ▼]

The structure of the sludge sample continues changing during drying as a result of the shrinkage phenomenon. Then the exchange area becomes smaller and the drying rate decreases. The sludge collected in a wastewater treatment plant (Grosses Battes WWTP, Belgium) was chosen for both lab-scale experiment and pilot-scale experiment. X-ray macrotomography (resolution: 0.36 mm per pixel) and X-ray microtomography (resolution: 41 μm per pixel) were used to explore the structure evolution of the sludge bed and the single extrudate respectively. 2D cross-sections of the sludge bed and the single extrudate were acquired, which supply a convenient way to investigate the evolution of the structure. The results show that the structure of both the sludge bed and the single extrudate distinctly changes during the drying process. [less ▲]

Detailed reference viewed: 13 (0 ULg)
Full Text
See detailMODELING MOISTURE TRANSFER OF MORTAR SUBMITED TO CONVECTIVE DRYING
Kahlerras, Loubna ULg

Poster (2017, June 19)

Detailed reference viewed: 18 (1 ULg)
Full Text
See detailGeneralized Pascal triangles for binomial coefficients of finite words
Stipulanti, Manon ULg

Conference (2017, June 19)

We introduce a generalization of Pascal triangle based on binomial coefficients of finite words. These coefficients count the number of times a finite word appears as a subsequence of another finite word ... [more ▼]

We introduce a generalization of Pascal triangle based on binomial coefficients of finite words. These coefficients count the number of times a finite word appears as a subsequence of another finite word. Similarly to the Sierpiński gasket that can be built as the limit set, for the Hausdorff distance, of a convergent sequence of normalized compact blocks extracted from Pascal triangle modulo 2, we describe and study the first properties of the subset of [0, 1] × [0, 1] associated with this extended Pascal triangle modulo a prime p. Then we create a new sequence from this extended Pascal triangle that counts, on each row of this triangle, the number of positive binomial coefficients. We show that this sequence is 2-regular. To extend our work, we construct a Pascal triangle using the Fibonacci representations of all the nonnegative integers and we define the corresponding sequence of which we study the regularity. This regularity is an extension of the classical k-regularity of sequences. [less ▲]

Detailed reference viewed: 30 (7 ULg)
Peer Reviewed
See detailOptimiaztion of an electrophoretic approach for the screening and the development of new antithrombotic drugs
Farcas, Elena ULg; Bouckaert, Charlotte; Servais, Anne-Catherine ULg et al

Poster (2017, June 19)

The discovery of lead compounds that can modulate the activity of a biological target is essential to provide efficient pharmacological tools and to serve as starting points for new drug generations ... [more ▼]

The discovery of lead compounds that can modulate the activity of a biological target is essential to provide efficient pharmacological tools and to serve as starting points for new drug generations. Fragment-based drug discovery (FBDD) approach is an attractive tool for the identification of new selective inhibitors of a target of interest, but its success largely depends on the ability to develop screening bioassays capable to detect and gauge weak affinity binders. To achieve this goal, we investigated capillary electrophoresis (CE) for identifying and ranking fragments from an initial library. Indeed, due to its ability to evaluate weak interactions, CE seems to be promising for fragment-based screening. This technique is a powerful analytical tool with a unique separation mechanism, speed, efficiency and versatility. Its main advantages are low protein consumption, higher throughput compared to NMR and X-ray crystallography and the fact that screening can be carried out using native protein in physiological solution without the need of immobilization. We developed a proof of concept study on thrombin, a serine protease implicated in the coagulation cascade using affinity capillary electrophoresis (ACE) for ranking fragments from an initial library. For this study, we followed a probe ligand, benzamidine, and we investigated interactions with the target by monitoring the changes of its electrophoretic mobility upon binding. The first step of this study consisted in the optimization of the experimental conditions suitable for the CE method (target and probe ligand concentrations, separation buffer composition, voltage, separation effective length, target partial filling…). Then, numerous thrombin inhibitors with a wide range of inhibitory potency (i.e. Ki 200 µM – 5 nM) were tested to validate our system demonstrating the possibility to fish binders in the optimized conditions. We also checked the absence of non-specific binding with the target using the inactivated enzyme at the binding site. It is noteworthy that in this operating system (ACE assay), binding occurs in free solution using physiological buffers, thus preventing artifacts that may result from target immobilization, which is a requirement for some techniques such as SPR. [less ▲]

Detailed reference viewed: 63 (4 ULg)