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See detailA new HPLC method to quantify alliin, the major sulfur compound in garlic
DETHIER, Bérénice ULg; Laloux, Morgan ULg; Hanon, Emilien et al

Poster (2012, February 10)

Garlic is recognized for centuries for its health benefits, mostly linked to its sulfur- components. Among the products extracted from the cloves, alliin retained our attention. Alliin was synthesized ... [more ▼]

Garlic is recognized for centuries for its health benefits, mostly linked to its sulfur- components. Among the products extracted from the cloves, alliin retained our attention. Alliin was synthesized. This process leads to two stereoisomers. Their HPLC separation was the aim of this work. The method described in the literature (amino column, detection at 210 nm) showed a resolution of 1,1 between the isomers. A second method was developed: the stationary phase was porous graphitic carbon and a water-ACN gradient was used for the elution. It provided a resolution of 3,2, was shorter and underwent the validation process. The method leads to satisfying results. The separation is excellent, and the validation criteria are fulfilled. This may be valuable for future research on garlic. [less ▲]

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See detailImplication of honeydew microflora in ant-aphid mutualism
Fischer, Christophe ULg; Lognay, Georges ULg; Haubruge, Eric ULg et al

Poster (2012, February 10)

Some ant and aphid species can present a mutualistic relationship, ants using aphid honeydew as sugar source and in exchange providing the aphid colony cleaning and protection. From a behavioral point of ... [more ▼]

Some ant and aphid species can present a mutualistic relationship, ants using aphid honeydew as sugar source and in exchange providing the aphid colony cleaning and protection. From a behavioral point of view, this phe-nomenon has been well studied from decades. However, its chemistry and semiochemical mechanisms are still largely unknown. This study aims to identify semiochemicals involved in the establishment of this relation, using both chemical and behavioral approaches. Bioassays revealed that the great-est part of ant attraction toward aphid colonies is due to honeydew volatile compounds; enabling ant scouts to find more quickly aphid colonies and distantly recognize myrmecophilous species. Many of those VOCs seeming to have microbial origins, the main honeydew microorganisms have been isolated and their roles in VOCs production and ant attraction have been investigated. It appeared that honeydew microflora holds a key role in the establishment of ant-aphids mutualistic relationship. [less ▲]

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See detailCharacterization of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) overwintering sites
Fassotte, Bérénice ULg; Durieux, Delphine ULg; Haubruge, Eric ULg et al

Poster (2012, February 10)

The invasive multicoloured Asian ladybird, Harmonia axyridis (Pallas), forms large aggregations inside dwellings to overwinter. In order to highlight the specific features of infested houses, we ... [more ▼]

The invasive multicoloured Asian ladybird, Harmonia axyridis (Pallas), forms large aggregations inside dwellings to overwinter. In order to highlight the specific features of infested houses, we investigated a large number of overwintering sites in Wallonia between 2007 and 2011. These sites were characterized through a survey sent to homeowners confronted to invasion problems. The results indicate that H. axyridis preferentially selects isolated brick houses with red or white fronts to take shelter. Aggregations are mostly located at the first floor, essentially inside south or west oriented rooms. Furthermore, ladybirds generally gathered into wooden windows frames facing south or west, and to a lesser extent, in the upper corners of walls presenting the same orientation. [less ▲]

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See detailImpact of cultivation practices on soil respiration
Dufranne, Delphine ULg; Vancutsem, Françoise ULg; Bodson, Bernard ULg et al

Poster (2012, February 10)

Cultivation practices are known to induce a modification of soil organic matter quantity, quality and spatial distribution, which may impact dry matter decomposition kinetics. In order to bring answers to ... [more ▼]

Cultivation practices are known to induce a modification of soil organic matter quantity, quality and spatial distribution, which may impact dry matter decomposition kinetics. In order to bring answers to these questions, a multidisciplinary project (SOLRESIDUS) was set up by the University of Liege, Gembloux Agro-Bio Tech in collaboration with Walloon Agricultural Research Centre (CRA-W). The aim was to investigate the impact of cultivation practices (tillage and residue restitution) on crop growth, yield and environment, as well as on soil properties and on activities. In the present study, we focused on the impacts on soil respiration soil for 3 years. We will present our first results. [less ▲]

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See detailVolatile organic compounds released by barley roots attract wireworms
Barsics, Fanny ULg; Fiers, Marie ULg; Haubruge, Eric ULg et al

Poster (2012, February 10)

Wireworms are the soil dwelling larvae of click beetles and are pests of many crops worldwide. Alternatives to insecticide treatments are needed in order to develop integrated management strategies. Our ... [more ▼]

Wireworms are the soil dwelling larvae of click beetles and are pests of many crops worldwide. Alternatives to insecticide treatments are needed in order to develop integrated management strategies. Our work consists in elucidating the role of barley root-emitted volatile organic compounds on the orientation behaviour of Agriotes sordidus wireworms. Using a dual choice olfactometer we have evaluated the attractiveness of a variety of baits ranging from barley roots themselves to isolated root-emitted volatile organic compounds. Wireworms were significantly attracted towards most of the tested baits. Our results should be taken into account in varietal selection, in crop rotation, or in trapping systems aiming at the reduction of the populations of this pest. [less ▲]

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See detailReplacing explicit water and membrane molecules in molecular dynamics simulation to boost simulation speed
Steinhauer, Sven ULg; Crowet, Jean-Marc ULg; Lins, Laurence ULg et al

Poster (2012, February 10)

Molecular dynamics (MD) is an appropriate method for investigation of biomolecular systems and helps in explaining results from wet lab experiments or in getting further insight into details, which are ... [more ▼]

Molecular dynamics (MD) is an appropriate method for investigation of biomolecular systems and helps in explaining results from wet lab experiments or in getting further insight into details, which are not accessible by experimental methods(Lindahl, 2008). By now, many biologically relevant processes for drug design, toxicological studies and other fields of application, can not be performed by atomistic MD simulations (Lindahl, 2008). In MD, the necessary time effort for carrying out a simulation is considerable and depends mainly on (1) the complexity of the simulated system (2) the simulated time scale (3) the simulation method (4) the efficiency of used hardware and software algorithms. Carried out MD simulations nowadays may still take weeks of calculation on high end computers. In practice, biologically relevant processes, as e.g. protein folding, take usually place above the time scale of milli seconds. They can take up to the order of some thousands of seconds (in case of the folding of membrane proteins). Molecular dynamics computer simulations have reached the scale of micro seconds for simulations of systems where each atom was described and simulated over time.(Lindahl, 2008) Nevertheless, MD has risen to an important promoter methodology for many different fields of application. By replacing bunches of atoms by artificial particles, complexity of the systems can be reduced. This method is called the coarse grain method (CG). Biggin and Bond (2008) found an acceleration of their simulation processes for self assembling membrane / protein systems in water by factor 100. They estimated one to two days of calculation for a simulated time scale of 0.1 to 0.2 micro seconds for their systems. Implicit force fields like "IMPALA", aim to describe water and/or membrane molecules in simulations by a couple of simple and partially precalculable equations. “IMPALA” is a force field initially developed by our laboratory. Using this method, thousands of water and lipid molecules can be replaced, leading to a reduced complexity of the system to be simulated. "IMPALA"(Ducarme et al., 1998) based on the assumption of rigid peptides and aimed to find the insertion characteristics of such in membranes. Elimination of the necessity for simulating the aqueous and lipid phase atom by atom in the software package "Gromacs"(Berendsen et al., 1995) will permit both: a gain of speed, as it was already the case for the introduction of the coarse grain method, and a gain of precision by turning rigid molecules flexible through "Gromacs". Our current work is the integration of the "IMPALA" implicit force field into "Gromacs". Biggin, P.C. & Bond, P.J. Molecular dynamics simulations of membrane proteins. Methods Mol. Biol. 443, 147-60(2008). Berendsen, et al. (1995) Comp. Phys. Comm. 91: 43-56. Ducarme, P., Rahman, M. & Brasseur, R. IMPALA: a simple restraint field to simulate the biological membrane in molecular structure studies. Proteins 30, 357-71(1998). Lindahl, E.R. (2008). Molecular dynamics simulations. Methods Mol. Biol. 443, 3-23. [less ▲]

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See detailL'architecture postmoderniste dans la tourmente de l'idéologie du progrès
Steinmetz, Rudy ULg

in André Valérie, Contzen Jean-Pierre (Ed.) L'idéologie du progrès dans la tourmente du postmodernisme (2012, February 10)

Detailed reference viewed: 39 (9 ULg)
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See detailRelationships between methane emissions of dairy cattle and farm management.
Vanrobays, Marie-Laure ULg; Vanlierde, Amélie ULg; Kandel, Purna Bhadra ULg et al

Poster (2012, February 10)

Livestock is considered as an important contributor to global methane emissions, predominately due to methanogenesis from ruminants. Moreover, these emissions also represent major losses of energy for ... [more ▼]

Livestock is considered as an important contributor to global methane emissions, predominately due to methanogenesis from ruminants. Moreover, these emissions also represent major losses of energy for dairy cows and therefore are linked to production efficiency. The on-going development of predictive equations (e.g., from milk composition) would allow to relate methane emissions to farm management (e.g., nutrition, environment) on a large scale in the Walloon Region of Belgium. Finally, by acquiring improved knowledge of these relationships, contributions to mitigate methane emissions could be based on an improved management of dairy herds. [less ▲]

Detailed reference viewed: 81 (29 ULg)
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See detailDirect imaging, photometry and spectroscopy of gravitationally lensed quasars
Ricci, Davide ULg

Doctoral thesis (2012)

Detailed reference viewed: 25 (3 ULg)
See detailDeux méthodes numériques pour la résolution de problèmes de diffraction multiple à haute fréquence
Antoine, X.; Boubendir, Y.; Geuzaine, Christophe ULg

Scientific conference (2012, February 10)

Detailed reference viewed: 16 (1 ULg)
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See detailVariability among morning and evening milk compositions during the lactation
Arnould, Valérie ULg; Gengler, Nicolas ULg; Soyeurt, Hélène ULg

Poster (2012, February 10)

The main objective of this study was to analyze milking-to-milking variability of milk yield and milk composition (such as fat and protein percentages and somatic cell count). Additional objective was to ... [more ▼]

The main objective of this study was to analyze milking-to-milking variability of milk yield and milk composition (such as fat and protein percentages and somatic cell count). Additional objective was to extend this analyze to the milk fat composition. Milk samples (n=195.960) were collected from 29.636 cows in 491 Luxembourg farms and analyzed by MIR spectrometry. The milk contents of saturated, mono-, poly- and unsaturated fatty acids, and short, medium and long chain fatty acids were predicted from the recorded MIR spectral data. As expected, the milk composition and the milk fat composition, are affected by several factors as the milking period and the days in milk. In practice, using separately milk evening and milk morning could be interesting for cheese or butter production. [less ▲]

Detailed reference viewed: 76 (29 ULg)
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See detailSoil Respiration in forest Ecosystems: Combination of a multilayer Approach and an Isotopic Signal Analysis
Goffin, Stéphanie ULg; Longdoz, Bernard; Maier, Martin et al

in Communications in Agricultural and Applied Biological Sciences (2012, February 10)

Detailed reference viewed: 124 (6 ULg)