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See detailA push–pull strategy to control aphids combines intercropping with semiochemical releases
Xu, Qingxuan ULg; Hatt, Séverin ULg; Chevalier Mendes Lopes, Thomas ULg et al

in Journal of Pest Science (in press)

Even if insect pest populations can be reduced by increasing plant diversity through intercropping, natural enemies are not always favored in such systems. Alternatively, semiochemical substances have ... [more ▼]

Even if insect pest populations can be reduced by increasing plant diversity through intercropping, natural enemies are not always favored in such systems. Alternatively, semiochemical substances have been tested to enhance biological control, with inconsistent results. Combining both strategies can be an interesting way to maximize pest control. In this work, a 2-year setup involving wheat–pea strip intercropping combined with the release of E-b-farnesene (EBF) or methyl salicylate (MeSA) was tested as a push–pull strategy to simultaneously repel aphids and attract beneficials. Two types of slow-release formulation (i.e., oil and alginate beads) containing EBF or MeSA were deployed with the intercropping. The abundance of aphids was significantly decreased, while hoverfly larvae and mummified aphids increased on both pea plants and wheat tillers by the release of oil-formulated EBF and MeSA. The proportion parasitism of the aphid-parasitism rate [mummies/(aphids + mummies)] was also increased by treating both crops in both years. Releasing EBF through oil rather than alginate beads proved significantly better for attracting natural enemies and reducing aphids. Aphids were negatively correlated with the density of hoverflies (both adults and larvae) and numbers of mummies. All these results showed that combining intercropping with the release of EBF or MeSA formulated in oil can significantly reduce aphid density and attract their natural enemies. Therefore, the combination of both strategies could help farmers reduce the use of insecticides. [less ▲]

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See detailProtein requirements of collared peccary (Pecari tajacu)
Borges, Rogerio; Mendes, Alcester; Nogueira, Selene et al

in Tropical Animal Health and Production (in press)

A nitrogen (N) balance digestion trial was conducted to determine the protein requirement of collared peccaries (Pecari tajacu). In a 4 × 4 Latin square design, four captive adult male peccaries were fed ... [more ▼]

A nitrogen (N) balance digestion trial was conducted to determine the protein requirement of collared peccaries (Pecari tajacu). In a 4 × 4 Latin square design, four captive adult male peccaries were fed four isoenergy diets containing four different levels of N (11.7, 16.3, 22.8, and 26.7 g N/kg of dry matter—DM). After 15 days of adaptation, a total collection of feces and urine was carried out for five consecutive days. Regression analyses between N intake and N in feces and urine allowed to calculate the metabolic fecal nitrogen (MFN = 2.3 g N/kg of dry matter intake—DMI) and daily endogenous urinary N (EUN = 185 mg N/kg0.75). Likewise, by regression analyses between consumption of nitrogen and the nitrogen balance (NB = N ingested − N excreted, mg N/kg0.75), a daily requirement of 514 mg N/kg0.75 was calculated. Therefore, if food intake is unrestricted, collared peccaries require a minimumin their diet of about 5.4% crude protein on DM basis. These values are almost as low as those found for browsing and frugivorous wild ruminants, which reinforce the proposition that peccaries’ digestive physiology is nearer to that of domestic and wild ruminants than domestic pigs. This relatively low protein requirement of collared peccary and its great ability to digest protein reveal the relevance of the forestomach for the species on nitrogen/protein metabolism and allow the use of diets with lower crude protein levels than the commercial ones used for the domestic pig, which reduces feed costs. [less ▲]

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See detailRegiospecific radiolabelling of Nanofitin on Ni Magnetic Beads with [18F]FBEM and in vivo PET studies
Dammicco, Sylvestre ULg; Goux, Marine; Lemaire, Christian ULg et al

in Nuclear Medicine & Biology (2017)

Introduction: Nanofitins are low molecular weight, single chain and cysteine-free protein scaffolds able to selectively bind a defined biological target. They derive from Sac7d bacterial protein family ... [more ▼]

Introduction: Nanofitins are low molecular weight, single chain and cysteine-free protein scaffolds able to selectively bind a defined biological target. They derive from Sac7d bacterial protein family and are highly stable over a wide range of pH (0-13) and temperature (Tm ~80°C). Their extreme stability, low cost of production and high tolerability for chemical coupling make Nanofitins a very interesting alternative to antibodies and their fragments. Here, a hexahistidine tagged model Nanofitin (H4) directed against hen egg white lysozyme was radiolabelled and injected in mice to provide a baseline biodistribution and pharmacokinetic profiles to support future Nanofitin development programs. Method: A single cysteine residue has been genetically inserted in a model Nanofitin and its regioselective radiolabelling has been performed with 4-[18F]fluorobenzamido-N-ethylamino-maleimide ([18F]FBEM). The synthesis of [18F]FBEM has been completely implemented on a radiosynthesis unit (FastLab) including HPLC purification and formulation. Coupling with the [18F]FBEM has been achieved on a solid support (Ni magnetic beads) allowing rapid purification at room temperature without organic solvent. PET-MRI studies on C57BL/6 mice were conducted after injection of [18F]FBEM-Cys-H4 in order to access the biodistribution of this Nanofitin model. Results: Radiochemical yield (decay corrected) of 54±7% (n=4) was obtained after optimization for coupling the [18F]FBEM to Nanofitin. Pharmacokinetics results of [18F]FBEM-Cys-H4 revealed a fast clearance through the liver and the kidneys. Conclusion: An efficient new method on Ni magnetic beads was developed to radiolabelled his-tagged biomolecules with [18F]FBEM. This procedure was applied on a Nanofitin model Cys-H4 and biodistribution kinetic studies were achieved to evaluate the potential use of Nanofitin for diagnostic imaging. Fast clearance indicates that Nanofitins represent very interesting tools for diagnostic imaging. [less ▲]

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See detailSpatial diversification of agroecosystems towards biological control of insect pests: A focus on intercropping and wildflower strips
Hatt, Séverin ULg

Doctoral thesis (2017)

Facing the limits of input-intensive agriculture, agroecology aims at thinking ways to design a sustainable agriculture that is economically viable and socially relevant. It notably invites to mobilize ... [more ▼]

Facing the limits of input-intensive agriculture, agroecology aims at thinking ways to design a sustainable agriculture that is economically viable and socially relevant. It notably invites to mobilize ecological processes within agroecosystems in order to enhance the delivery of ecosystem services towards reducing the use of external inputs – among others insecticides. For enhancing biological control of insect pests, a strategy is to spatially diversify agroecosystems at the field scale. Whereas increasing plant diversity could directly negatively affect pest development on the one hand (i.e. bottom-up effect), providing flowering features could allow the enhancement of natural enemies and their direct effect on pest populations on the other hand (i.e. top-down effect). The present thesis focused on intercropping (i.e. the cultivation of at least two crop species simultaneously in a same field) as a way to diversify crop habitat, and the sowing of wildflower strips as a non-crop feature. A systematic analysis of the literature revealed that, in most of studies, wheat (Triticum aestivum L.)-based intercropping allows a reduction of insect pests on crops, without necessarily favouring their natural enemies, compared to pure-stands. Besides, the provision of flowering resources, by for instance sowing wildflower strips, can attract and support flower visiting predators and parasitoids. Hence, in a first set of field experiments, combining the two tactics of increasing crop diversity and providing flowering resources was tested. First in China, wheat crop was associated with oilseed rape (Brassica napus L.), but it neither allowed reducing aphid (Hemiptera: Aphididae) abundance nor enhancing their natural enemies compared to pure stands. Instead, aphid density – independently from the treatments – affected natural enemy abundance, and interspecific relations between aphids and their natural enemies were observed. Second in Belgium, wildflower strips were sown within a wheat field, which led to a reduction of aphid density in wheat plots in between flowering features and an increase of aphidophagous hoverflies (Diptera: Syrphidae) compared to pure-stand wheat. Nevertheless, the presence of flowering strips did not affect the other natural enemies, i.e. lacewings (Neuroptera: Chrysopidae), ladybeetles (Coleoptera: Coccinellidae) and parasitoid wasps (Hymenoptera: Braconidae). Therefore, a second set of field experiments focussed on ways to compose mixtures of wild flowers attractive to a diversity of natural enemies. Flower functional traits were considered due to their effect on insect behaviour. First, the hypothesis that mixtures with high functional diversity attract and support a high abundance and diversity of aphid flower visiting predators was tested. This hypothesis was not verified. Instead, the high density in the plots of some flower species (especially the Asteraceae Leucanthemum vulgare Lam.) known to be attractive to flower visitors was supposed to have overwhelmed the effect of functional diversity. Second, a methodology was developed to identify which flower traits significantly affect natural enemy abundance – in this experiment parasitoids of oilseed rape beetle pests (i.e. Meligethes spp. [Coleoptera: Nitidulidae] and Ceutorhynchus spp. [Coleoptera: Curculionidae]) – in flower mixtures. Among seven traits, visual traits (i.e. colour, ultra-violet reflectance) and the one related to food availability (i.e. corolla morphology) were found to significantly affect parasitoid abundance. These results highlight that (i) increasing plant diversity at the field scale can – but not systematically – favour a reduction of insect pests, (ii) including flowering features can enhance some – but not all – of their natural enemies, and (iii) in order to compose flower mixes attractive to natural enemies, specific flower traits – rather than functional diversity at the mixture level – can be considered. These results are discussed in a broader perspective. Indeed, strategies to spatially diversify crop and non-crop habitats in agroecosystems are various, as well as the ways to compose, manage and design such habitats. Also, processes at larger scales than the field may be determinant. Moreover, insects are not the only pests, and pests are not the only biotic or abiotic elements that need to be regulated in agroecosystems. Controlling multiple pests simultaneously but also enhancing the provision of multiple regulating services represent challenges for future research in agriculture. [less ▲]

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See detailDevelopment and applications of CRISPR-Cas9 and RNAi for rice and wheat agronomic traits improvement
Sun, Yongwei ULg

Doctoral thesis (2017)

Genome editing technologies enable precise modifications of DNA sequences in vivo and offer a great promise for harnessing plant genes in crop improvement. The precise manipulation of plant genomes relies ... [more ▼]

Genome editing technologies enable precise modifications of DNA sequences in vivo and offer a great promise for harnessing plant genes in crop improvement. The precise manipulation of plant genomes relies on the induction of DNA double-strand breaks (DSBs) by sequence-specific nucleases (SSNs) to initiate DNA repair reactions that are based on either non-homologous end joining (NHEJ) or homology-directed repair (HDR). NHEJ can result in frame-shift mutations that often create genetic knockouts. These knockout lines are useful for functional and reverse genetic studies but also have applications in agriculture. HDR has a variety of applications as it can be used for gene replacement, gene stacking, and for creating various fusion proteins. An overview of development and applications of precise GT in plants using SSNs systems is presented in Chapter I. Cereals high in amylose content (AC) and resistant starch (RS) offer potential health benefits. Starch branching enzyme (SBE) plays a major role in determining the fine structure and physical properties of starch. Here, we use CRISPR/Cas9 technology to generate targeted mutagenesis in SBEI and SBEIIb in rice. The frequencies of obtained homozygous or bi-allelic mutant lines with indels in SBEI and SBEIIb in T0 generation were from 26.7 to 40%. SbeII mutants showed higher proportion of long chains presented in debranched amylopectin, significantly increased AC and RS content to as higher as 25.0% and 9.8%, respectively. The details of results are presented in Chapter IV Complete knockouts and loss-of-function mutations are very valuable in defining gene functions, their applications in crop improvement are somewhat limited because many agriculturally important traits are conferred by point mutations or a change of gene expression levels. Development of a technology that enables gene replacement rather than gene inactivation will greatly facilitate plant breading. In this study, we report an efficient method to introduce multiple discrete point mutations in the rice ALS gene using CRISPR/Cas9-mediated homologous recombination. We not only generated homozygous herbicide resistance rice plants in one generation, but also demonstrated that the presented strategy is feasible and effective in precise gene replacement by using CRISPR/Cas9 system to facilitate crop genetic improvement. The details of results are presented in Chapter V Aphids are major agricultural pests which cause significant yield losses of wheat each year in China. Present attempts to improve the aphid resistance of wheat through conventional breeding in China are being confronted by slow progress due to lack of aphid resistant wheat germplasm, the complexity of plant-aphid interactions and the rapid development of resistant pest biotypes. An overview of the engineering of plants for aphid resistance is presented in chapter II. We identify a gene (23028) related to aphid ingestion and digestion from the aphid, S. avenae. Aphids fed on plant material expressing double-stranded RNA (dsRNA) specific to 23028 and C002 show a decline in growth, reproduction and survival rates. The details of results presented in the chapter VI. [less ▲]

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See detailGENETIC DIVERSITY AND FACULTATIVE SYMBIONTS INFECTION PATTERNS OF TWO RHOPALOSIPHUM APHIDS
Guo, Jianqing ULg

Doctoral thesis (2017)

Aphids, during the long-term evolution, kept their genetic traits for continuation of the species while some variations caused by selection, migration, mutation, and genetic drift occurred meanwhile to ... [more ▼]

Aphids, during the long-term evolution, kept their genetic traits for continuation of the species while some variations caused by selection, migration, mutation, and genetic drift occurred meanwhile to adapt to novel environments. The differentiation takes place not only among species but could also be observed within species that finally contributes to the population genetic diversity. However, the migrant behavior of aphid can enhances the gene flow among populations, as a result, decreasing the genetic variation. Additionally, insect such as aphids usually hold the mutualistic relationships with endosymbionts which may affect the adaptive characteristics of the host aphid. Both Corn leaf aphid Rhopalosiphum maidis (F.) (Hemiptera: Aphididae) and Bird cherry-oat aphid Rhopalosiphum padi (L.) (Hemiptera: Aphididae) are worldwidely severe pests that attack cereal crops such as maize, barley, wheat, sorghum and oats. They suck the phloem and can transmit viruses including Maize dwarf mosaic virus (MDMV) and Barley yellow dwarf virus (BYDV), the main virus of maize and barley, which may result in serious damage for the yield and quality of the host plant. Moreover, one aphid species usually exerts genetic differentiation among populations which is related to factors such as geographic conditions, host plants and life history. Hence, it is necessary to have a clear understanding of the genetic structure and variation among geographic populations to further explore the historical expanding routes and occurrence of these pests and design efficient control strategies. Targeting the genetic divergence among populations of two Rhopalosiphum aphids, 32 populations of R. padi and 38 populations of R. maidis were collected on maize from most regions of China as well as some countries in Europe. The sequencing results of two mitochondrial (COI and COII) and one nuclear (EF-1α) genes indicated that a high level of gene flow existed among the populations of R. maidis in terms of geographic locations, proving the migratory capacity of this aphid. With regard to R. padi, high genetic diversity were found between the populations from China and Europe based on combined COI-COII, however, the genetic diversification among Chinese populations and European populations were low, which illustrated that the length of geographic distance may play an important role in genetic diversity. The infection patterns of seven facultative symbionts (Serratia symbiotica, Hamiltonella defensa, Regiella insecticola, Rickettsia, Spiroplasma, Wolbachia and Arsenophonus) in R. padi and R. maidis were investigated as well. Both aphids were found to have wide symbiotic associations with variant symbionts. Unlike Acyrthosiphum pisim (H.) which is frequently infected with S. symbiotica, R. insecticola, Rickettsia and Spiroplasma were dominant facultative symbionts in these two Rhopalosiphum aphids. The results also indicated that the geographic conditions such as latitude of collecting locations may have an effect on the distribution of facultative symbionts, implying the adaptive function of the facultative symbionts to various environmental conditions on their host aphids. Considering the population diversity within species, we also tested the survival and reproduction rates of two R. maidis populations (i.e. Beijing and Mangshi) on barley and maize of small (10 cm) and high (50 cm) size. Direct observation method was used and none of the populations could survive on maize of small size whereas they were capable to develop on maize of high size, but with much lower growing speeds compared with barley on which both populations showed the best performances. In addition, Beijing population was found to perform significantly better than Mangshi population which may be related to the infection of facultative symbionts. We hypothesize that the lethality on small maize may result from the secondary metabolites synthesized to be more abundant in young maize seedlings. [less ▲]

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See detailStrategies of host defense and viral counter defense: analysis of Fusarium graminearium responses to FgHV1 infection
Wang, Shuangchao ULg

Doctoral thesis (2017)

Viruses that selectively infect fungi are named fungal viruses or mycoviruses. Fungal viruses exist in all major groups of fungi and are important in both fundamental research and biological control of ... [more ▼]

Viruses that selectively infect fungi are named fungal viruses or mycoviruses. Fungal viruses exist in all major groups of fungi and are important in both fundamental research and biological control of plant pathogens. Fusarium graminearum hypovirus 1 (FgHV1) was the first virus isolated from F. graminearum belonging to the hypoviridae family. FgHV1 was supposed to encode two open reading frames, which had high sequence identities with Cryphonectria hypovirus 1 and 2 (CHV1 and CHV2). F. graminearum strain infected with FgHV1 showed lower growth rate and reduced conidia production, but with no pathogenicity change. To elucidate the host defense and viral counter defense mechanism, we analyzed the F. graminearum stress responses to FgHV1 infection from several aspects. In the first part, we preliminarily elucidated the RNA silencing mechanism of the F. graminearum/hypovirus system from a small RNA (sRNA) perspective. The length distributions of F. graminearum sRNA were altered by FgHV1 infection, especially 24-nt sRNA. Extensive FgHV1-derived sRNAs were detected, yielding the first high resolution map of sRNA from mycoviruses. In particular, the RNA silencing-related genes FgDicer1 and FgRdRp5 were predicted targets of FgHV1- and FgHV2-derived siRNAs, possibly revealing a novel anti-RNA silencing strategy employed by mycoviruses. In the second part, we performed genome-wide expression analysis to reveal stress-related genes with expression changes in response to FgHV1 infection. A total of 248 differentially expressed genes were identified. Cellular redox regulation related genes were the most affected categories in F. graminearum challenged with FgHV1. Then we verified that FgHV1 encoded protein 20 (p20) could induce the H2O2 accumulation and hypersensitive response in Nicotiana benthamiana leaves. In the last part, our experiments confirmed that p20 functioned as a RNA silencing suppressor (RSS) with the agroinfiltration-mediated technique, making p20 the third RSS identified in mycoviruses. By incorporating single strand sRNA, p20 could suppress host RNA silencing. Globally, the defense responses of F. graminearum to FgHV1 infection were studied all-around and in-depth. On the other hand, FgHV1 developed counter defense strategies to protect from invasion resistance. [less ▲]

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See detailStudy of the regulation of β-lactam resistance in Enterococcus hirae
Raymackers, Alice ULg; Maréchal, Maxime; Verlaine, Olivier ULg et al

Poster (2017, June 13)

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See detailRemittances: a Loan Funds for Rural Economy? Illustration from the Kayes Area (Western Mali)
Yao Namé, Juste Michel ULg; Lebailly, Philippe ULg

Conference (2017, June 12)

In addition to have a direct and positive impact on reducing of food insecurity and poverty gaps in more vulnerable countries to shocks on the rainfall, the remittances received by the migrants families ... [more ▼]

In addition to have a direct and positive impact on reducing of food insecurity and poverty gaps in more vulnerable countries to shocks on the rainfall, the remittances received by the migrants families also allow them to have saving. This is what reveals the self-managed village banks of Kayes’ region, the most important emigration basin of Mali and located in strong climate variations area. However, this saving contributes less at agricultural sector finance. [less ▲]

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See detailL'art de la médiation scolaire. Entre ambiguïté et interprétations
Dethier, Baptiste ULg

Doctoral thesis (2017)

La thèse porte sur la construction de la politique de médiation scolaire menée en Belgique francophone et sa mise en œuvre concrète par de nouveaux agents chargés de l’interpréter : les médiateurs ... [more ▼]

La thèse porte sur la construction de la politique de médiation scolaire menée en Belgique francophone et sa mise en œuvre concrète par de nouveaux agents chargés de l’interpréter : les médiateurs scolaires. Dans un milieu scolaire où les acteurs, internes et externes aux établissements, sont multiples, les médiateurs sont appelés à prendre en charge des problèmes scolaires tels que la violence, le décrochage et l’absentéisme dans un cadre ambigu et, par conséquent, sujet à interprétation. La thèse rend compte du contexte organisationnel dans lequel les médiateurs s’inscrivent et de la mise en œuvre de cette politique. Baptiste Dethier analyse leur travail à l’aide de la métaphore du travail « artistique », c’est-à-dire comme un ensemble de procédures, de connaissances et de règles encadrant l’exercice d’une activité créative. Tout d’abord, cette activité est construite à partir d’orientations de sens – et non de prescriptions – données par l’État, les médiateurs scolaires étant chargés de les interpréter, grâce à une autonomie partiellement contrôlée. Ensuite, ces interprétations sont analysées grâce aux discours des médiateurs, reflétant la forte hétérogénéité dans la mise en œuvre de la politique de médiation scolaire ainsi que les controverses qui animent en permanence la fonction de médiateur. Enfin, à travers l’analyse des pratiques concrètes des médiateurs, il apparaît qu’elles consistent : d’une part, en la création de mises en scène spécifiques destinées à produire chez les bénéficiaires un état particulier de sensibilité ; d’autre part, comme autant de mises à l’épreuve de leur intégrité « artistique » et des principes dont ils se revendiquent. La thèse montre que les médiateurs scolaires se distinguent moins par ce qu’ils font que par la façon dont ils en parlent. Dès lors, la place de la place de la médiation et de la fonction de médiateur dans la division du travail au sein des organisations scolaires est questionnée. Celle-ci s’y trouve éclatée et ambigüe, entre contre-culture bousculant les équilibres historiques du système et participation au maintien de la forme scolaire traditionnelle. [less ▲]

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See detailStaggered strong coupling between existing fluid and solid solvers through a Python interface for fluid-structure interaction problems
Thomas, David ULg; Variyar, Anil; Boman, Romain ULg et al

in Proceedings of the VII International Conference on Coupled Problems in Science and Engineering (2017, June)

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See detailLong-term monitoring of European eels in the Belgian Meuse River basin. From the historical drastic decline to recent outcomes of restocking practices.
Nzau Matondo, Billy ULg; Dierckx, Arnaud ULg; Benitez, Jean-Philippe ULg et al

Conference (2017, June)

Long-term monitoring of yellow- and glass eel stages were performed in upland areas (>300km from sea) in order (i) to quantify the decline of wild yellow eels entering in the Belgian Meuse from the ... [more ▼]

Long-term monitoring of yellow- and glass eel stages were performed in upland areas (>300km from sea) in order (i) to quantify the decline of wild yellow eels entering in the Belgian Meuse from the Netherlands; (ii) to follow their upstream individual colonization; and (iii) to analyze the adaptation of young eels stocked as glass eels imported from UK. By monitoring a fish pass from 1992 to 2016, we quantified that the number of ascending eels has declined from n=5613 in 1992 to n=21 in 2016 (3.99%/year) and the mean length of eels has increased (4.1mm/year). During 6-years, upstream individual colonization of eels (2010-2015, n=1371) was followed using fixed RFIDtracking system. Few eels continued to migrate 4 years after tagging (<0.3%) and at >20km upstream (3.7%); and velocity of eels varied between individuals (0.012- 3.1km/day). In a 4-year (2013-2016) monitoring study of restocked glass eels using electrofishing and mobile RFID-tracking campaigns, we observed that eels grew rapidly in upland small brooks and recruitment was better in rivers with high carrying capacity (>15.8%, 2years post-stocking). Restocked eels dispersed in up- and downstream directions with behaviors including sedentary, nomadic and intermediate lifestyles. This suggests stocking as potential management measure to enhance local eel stocks. [less ▲]

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See detailDesign of reprocessable poly(ɛ-caprolactone)-based shape-memory materials
Defize, Thomas ULg

Doctoral thesis (2017)

Shape-memory polymers (SMPs) are remarkable materials able to switch from a temporary shape to their initial permanent shape by crossing a thermal transition, e.g. glass or melting transition. Efficient ... [more ▼]

Shape-memory polymers (SMPs) are remarkable materials able to switch from a temporary shape to their initial permanent shape by crossing a thermal transition, e.g. glass or melting transition. Efficient shape-memory effect is notably observed for chemically cross- linked semi-crystalline polymers. Chemical networks of semi-crystalline poly(ε-caprolactone) (PCL) are widely studied for the development of SMPs especially when biomedical applications are foreseen. As these SMPs are irreversibly cross-linked material, their (re)processing is quite limited since they cannot be molten or solubilized after cross-linking. This prevents any recycling. Thereby, using reversible cross-linking reactions allowing the formation or cleavage of the network upon a selected stimulus raise tremendous interest for the development of smart SMPs. Chemically cross-linked but remarkably (re)processable shape-memory polymers (SMP) were designed by crosslinking poly(ε-caprolactone) (PCL) stars via reversible cycloaddition reactions. The thermo-reversible Diels-Alder (DA) reaction between furan and maleimide was investigated to crosslink the PCL matrix. However, the relatively low retro DA temperature of the furan-maleimide adducts led to some inelastic deformation during shape memory tensile cycles. In order to get rid of this drawback, two alternative approaches were investigated, i.e. the substitution of the DA reaction firstly by the efficient triazolinedione click chemistry, especially the very fast and reversible Alder-ene reaction of 1,2,4-triazoline-3,5- dione (TAD) with indole compounds and secondly by a photo-reversible reaction, typically the photo-induced (2+2) cycloaddition of coumarins. With these networks, the typical shape memory properties of PCL networks (high fixity and recovery ratios) were preserved while upon an external (light or stress) stimulus, the PCL network can be (re)processed efficiently. [less ▲]

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See detailSurrogate Generation and Evaluation for Biodiesel and Its Mixtures with Fossil Diesel
Reiter, Anton M.; Schubert, Nikolai; Pfennig, Andreas ULg et al

in Energy & Fuels (2017), 31

In this paper a precedently developed surrogate optimization algorithm for fossil fuels, which originally allowed simultaneous fitting of the true boiling point (TBP) curve, the liquid density at 15 °C ... [more ▼]

In this paper a precedently developed surrogate optimization algorithm for fossil fuels, which originally allowed simultaneous fitting of the true boiling point (TBP) curve, the liquid density at 15 °C, and the cetane number, is refined toward its application to biodiesel and its mixtures with fossil diesel. For this purpose, the algorithm is extended (1) to also include fitting of the kinematic viscosity at 40 °C and (2) to account for peculiarities of biodiesel concerning its narrow boiling range and compensation of systematic errors of measured boiling curves. To illustrate these improvements, first, the algorithm is applied to property estimation and surrogate optimization of three different biodiesel fuels, for which surrogates consisting of one to three components are proposed. Second, a surrogate for a commercial European fossil diesel is calculated and produced in lab-scale. Finally, the algorithm is used for surrogate optimization and property estimation of mixtures of biodiesel and fossil diesel, considering fractions of biodiesel of 7% and 20% per volume. It is shown that the improved algorithm is capable of reliably optimizing surrogates for fuels containing both biogenic and fossil components. [less ▲]

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See detailProfil d'acides gras et stabilité oxydative d'huiles de brisures d'amandons et d'écarts de tri des amandes
Houmy, Nadia ULg; Melhaoui, R; Sindic, Marianne ULg et al

Conference (2017, April 27)

Dans la région orientale du Maroc, en outre du projet *PROFAO, la filière Amandier bénéficie d'une attention particulière. Cependant, les opérations de concassage et de triage des amandes se font encore ... [more ▼]

Dans la région orientale du Maroc, en outre du projet *PROFAO, la filière Amandier bénéficie d'une attention particulière. Cependant, les opérations de concassage et de triage des amandes se font encore de façon artisanale. Dans un but de valorisation après le décorticage/concassage, les brisures et les écarts de tri des amandes, ayant une faible valeur marchande, servent à l'extraction d'huile pour usage alimentaire et cosmétique. Ce travail porte sur l'analyse chimique d'huiles de brisures d'amandes (HbA) et la détermination de leur stabilité oxydative. Ainsi sur trois compagnes agricoles consécutives 2014, 2015, 2016, des analyses par CPG FID des profils d'acides gras (AG) des HbA des variétés Marcona Ferragnes-Ferraduel, ont été effectuées. L'acide Oléique (C18:1) et l'acide Linoléique (C18:2) sont les deux AG majoritaires qui caractérisent les profils d'AG des HbA. Selon l'année de récolte, ces HbA ont montré des variations inter variétale, les différences observées sont significatives et sont de l'ordre de 15 % pour C18:1 et de 13 % pour C18:2. Ainsi la teneur des HbA analysées en C18:1 varie entre un taux-max de 72 % enregistré en 2013/2014 pour Ferrangnes-Ferraduel et un taux-minima de 57 % observé en 2015/2016 pour Marcona. La même remarque pour le C18:2 avec une teneur minimum de 17 % enregistré en 2013/2014 pour Ferragnes-Ferraduel et une teneur maximum de 30 % observé en 2015/2016 pour Marcona. Pour le rapport O/L la plus grande différence a été observée en 2013/2014, avec un ratio O/L de 4,1 pour l'HbA Ferragnes-Ferraduel et de 1,95 pour Marcona. Les résultats observés pour la stabilité oxydative des Hba estimée par des tests Rancimat montrent des valeurs qui varient entre un minimum de 20h pour l'HbA Marcona en 2013/2014 et un maximum de 29h pour l'HbA Ferragnes Ferraduel en 2015/2016. On note une corrélation positive entre la stabilité oxydative et la teneur des HbA en C18:1 ainsi qu'avec le ratio O/L. La suite logique de ce travail est la recherche d'une correlation entre la stabilité oxydative et les composants mineurs de l'huile notamment ceux à activité antioxydante tel les tocophérols. [less ▲]

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See detail¿Cómo enfrentar la crisis migratoria de haitianos y africanos en Baja California?
Lara Guerrero, Larisa Viridiana ULg

Article for general public (2017)

De acuerdo con cifras del Instituto Nacional de Migración (INM), 3,700 migrantes originarios de Haití, Nigeria y El Congo, entre otros países africanos, residen en Baja California. La gran mayoría de ... [more ▼]

De acuerdo con cifras del Instituto Nacional de Migración (INM), 3,700 migrantes originarios de Haití, Nigeria y El Congo, entre otros países africanos, residen en Baja California. La gran mayoría de estos migrantes han llegado al norte del país con el sueño de cruzar hacia Estados Unidos; sin embargo, debido a las políticas de inmigración represivas estadounidenses, dichos extranjeros se han visto obligados a permanecer en el territorio nacional indefinidamente. Frente a esta nueva crisis migratoria que sufre nuestro país, diversas organizaciones cristianas y de protección social han brindado ayuda humanitaria a los migrantes. [less ▲]

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See detailEvolution of fast familiarity and novelty decisions in aging
Delhaye, Emma ULg; Bastin, Christine ULg; Moulin, Christopher et al

Poster (2017)

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