References of "Brostaux, Yves"
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See detailLarval development sites of the main Culicoides species (Diptera: Ceratopogonidae) in northern Europe and distribution of coprophilic species larvae in Belgian pastures
Zimmer, Jean-Yves ULg; Brostaux, Yves ULg; Haubruge, Eric ULg et al

in Veterinary Parasitology (in press)

Some Culicoides species of biting midges (Diptera: Ceratopogonidae) are biological virus vectors worldwide and have indeed been associated with outbreaks of important epizoonoses in recent years, such as ... [more ▼]

Some Culicoides species of biting midges (Diptera: Ceratopogonidae) are biological virus vectors worldwide and have indeed been associated with outbreaks of important epizoonoses in recent years, such as bluetongue and Schmallenberg disease in northern Europe. These diseases, which affect domestic and wild ruminants, have caused considerable economic losses. Knowledge of substrates suitable for Culicoides larval development is important, particularly for the main vector temperate species. This study, realized during two years, aimed to highlight the larval development sites of these biting midge species in the immediate surroundings of ten Belgian cattle farms. Moreover, spatial distribution of the coprophilic Culicoides larvae (C. chiopterus and C. dewulfi) within pastures was studied with increasing distance from farms along linear transects (farm–pasture–woodland). A total of 4347 adult specimens belonging to 13 Culicoides species were obtained by incubation of 2131 soil samples belonging to 102 different substrates; 18 of these substrates were suitable for larval development. The Obsoletus complex (formed by two species) was observed in a wide range of substrates, including silage residues, components of a chicken coop, dung adhering to walls inside stables, leftover feed along the feed bunk, a compost pile of sugar beet residues, soil of a livestock trampling area, and decaying wood, while the following served as substrates for the other specimens: C. chiopterus, mainly cow dung; C. dewulfi, cow dung and molehill soil; C. circumscriptus, algae; C. festivipennis, algae and soil in stagnant water; C. nubeculosus, algae and silt specifically from the edge of a pond; C. punctatus, mainly wet soil between silage reserves; C. salinarius, algae; and C. stigma, algae and wet soil between silage reserves. We also recorded significantly higher densities of coprophilic larvae within pastures in cow dung located near forests, which is likely due to the localization of potential hosts; the presence of these larvae within cow dung is, however, uninfluenced by relative distance from farms. A better knowledge of the microhabitats of Culicoides biting midges and their spatial distribution may allow the development of targeted species-specific vector control strategies, and may help to prevent the creation of new larval development sites. [less ▲]

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See detailSoil contamination near a former Zn-Pb ore-treatment plant: Evaluation of deterministic factors and spatial structures at the landscape scale
Liénard, Amandine ULg; Brostaux, Yves ULg; Colinet, Gilles ULg

in Journal of Geochemical Exploration (in press)

Historical soil contamination within a 3 km radius of a former ore treatment plant was evaluated. A total of 247 topsoil samples were collected in a stratified random sampling design taking into account ... [more ▼]

Historical soil contamination within a 3 km radius of a former ore treatment plant was evaluated. A total of 247 topsoil samples were collected in a stratified random sampling design taking into account three factors: land use (LU), soil type (ST) and wind direction (WD). Concentrations of trace elements (Cd, Co, Cr, Cu, Ni, Pb and Zn) and major elements (Ca, Mg, K, Fe, Al, Mn) as well as various soil properties (pHwater, pHKCl, TOC and N) were measured. Total Cd, Pb and Zn concentrations were higher than typical background values. Enrichment factors for these three metals were, respectively, 260, 77.4 and 35.5. Principal components analysis (PCA) and factor analysis segregated anthropogenic contamination as a premier factor in influencing concentrations, followed by a second lithogenic factor. The anthropogenic origin of substantial contamination was confirmed though mapping of sample locations relative to contaminant sources. Factor 1 (26.5% of the variance) impacts a large area around the contaminated site and is also indicative of WD influence. Factor 2 (23.9% of the variance) is naturally linked to the local lithology and geology. LU and soil fertility are, respectively, represented by factor 3 (16.5% of the variance), which is linked to pH, and factor 4 (9.3% of the variance), related to organic content. The significance of landscape factors in the spatial distribution of metallic trace elements (MTE) was assessed with an ANCOVA using “distance to the source” as a covariate. Results of the analysis support the hypothesis that Cd, Cu, Pb and Zn concentrations are mainly driven by anthropogenic factors, specifically historical industrial activity at the former ore treatment plant. The ANCOVA also provides a means to quantify the impact of LU and ST as well, particularly on MTE availability in soils. The presence of MTE in soil poses known, and potentially significant, risks to both human health and the environment. [less ▲]

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See detailEffects of tillage practices and crop residue exportation on earthworm communities and soil physico-­chemical properties in silt loam arable soil (Belgium)
Lemtiri, Aboulkacem ULg; Colinet, Gilles ULg; Alabi, Taofic ULg et al

Poster (2014, June 08)

Earthworms are known to play integral roles in soils, and are often referred to as vital soil and ecosystem engineers due to their capacity to influence a wide range of chemical, physical, and biological ... [more ▼]

Earthworms are known to play integral roles in soils, and are often referred to as vital soil and ecosystem engineers due to their capacity to influence a wide range of chemical, physical, and biological properties of soil environments. Therefore, it is important to understand how earthworm communities are impacted by tillage systems and crop management practices. In the present study, earthworm and soil samples were collected from wheat cultivated fields in Gembloux, Belgium under the following four experimental treatments: (1) conventional tillage with crop residues left in the soil (CT/IN); (2) conventional tillage with crop residues removed from the field (CT/OUT); (3) reduced tillage with crop residues left in the soil (RT/IN); and (4) reduced tillage with crop residues removed from the field (RT/OUT). The different tillage systems were applied for four consecutive years prior to the initiation of the current study. Results indicated soil compaction was significantly higher in RT compared with CT up to a depth of 6–49 cm. Significant differences were not detected between residue incorporation depth systems, where results showed mean earthworm abundance was respectively 182.25 and 180 individuals.m-2 in CT and RT. Mean earthworm biomass was similarly not significantly different between CT and RT, where results were respectively 48.52 and 57.27 g.m-2. However, a significant difference was observed between IN and OUT treatments, suggesting the exportation of wheat residues will limit earthworm abundance and biomass in CT and RT plots. Data showed high representation of the endogeic earthworm ecological category, notably N. c. caliginosus regardless of treatment. Despite tillage system and exportation of crop residues, N. c. caliginosus, L. terrestris, and A. r. rosea exhibited high abundance, indicating tolerance to soil environmental conditions. For each depth, measures of soil physico-chemical properties showed significant differences among treatments. Furthermore, soil chemical property attributes were significantly higher in the first soil centimetres compared to lower soil layers. These results were attributable to earthworm activity and wheat residues, suggesting earthworms contributed to nutrient dynamics, particularly at increased soil depths. Overall, the results emphasise the influence of exportation of crop residues on earthworm community and also, the important influence of earthworm activity on soil physico-chemical properties change, processes which are closely linked. [less ▲]

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See detailIs conspecific substrate marking a long-term external memory of previously colonized overwintering sites in Harmonia axyridis?
Durieux, Delphine ULg; Fassotte, Bérénice ULg; Vanderplanck, Maryse et al

in Journal of Applied Entomology (2014), 138(5), 338-345

The multicoloured Asian ladybeetle, Harmonia axyridis (Pallas), aggregates inside dwellings during winters to survive the cold. This beetle uses chemical cues coming from congeners to select an ... [more ▼]

The multicoloured Asian ladybeetle, Harmonia axyridis (Pallas), aggregates inside dwellings during winters to survive the cold. This beetle uses chemical cues coming from congeners to select an overwintering site. Recent research has shown that they preferentially gather at places where conspecifics previously laid a substrate marking made up of saturated and unsaturated hydrocarbons. Some authors have reported that H. axyridis colonizes the same overwintering sites from 1 year to another. Herein, the hypothesis that this substrate marking is used by H. axyridis to settle in the same aggregation sites from one winter to another was tested. To this aim, the temporal modification in the chemical profile of the hydrocarbon marking was studied by performing chromatographic analyses. After 1 year, the overall profile was modified qualitatively and quantitatively: the unsaturated hydrocarbons were no longer detected while some saturated hydrocarbons were still present in large quantities. In a behavioural assay conducted in the laboratory, the 12-month-old marking did not induce the aggregation of H. axyridis. This result indicates that the chemical markings left by conspecifics during a previous aggregation period in an overwintering site are not sufficient to induce the gathering of the newly arriving individuals. [less ▲]

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See detailTemperature regimes and aphid density interactions differentially influence VOC emissions in Arabidopsis
Hien, Truong Thi Dieu ULg; Delory, Benjamin ULg; Vanderplanck, Maryse et al

in Arthropod-Plant Interactions (2014)

The effects of volatile emissions from plants exposed to individual abiotic and biotic stresses are well documented. However, the influence of multiple stresses on plant photosynthesis and defense ... [more ▼]

The effects of volatile emissions from plants exposed to individual abiotic and biotic stresses are well documented. However, the influence of multiple stresses on plant photosynthesis and defense responses, resulting in a variety of volatile profiles has received little attention. In this study, we investigated how temperature regimes in the presence and absence of the sucking insect Myzus persicae affected volatile organic compound emissions in Arabidopsis over three time periods (0-24 h, 24-48 h, and 48-72 h). Headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry was used to evaluate Arabidopsis volatile organic compounds. The results showed that under laboratory conditions, eight volatile classes [alcohols (mainly 2-ethyl-hexan-1-ol), ketone (6-methyl hept-5-en-2-one), esters (mainly (Z)-3-hexenyl acetate), aldehydes (mainly phenylacetaldehyde), isothiocyanates (mainly 4-methylpentyl isothiocyanate), terpenes (mainly (E,E)-α-farnesene), nitrile (5-(methylthio) pentanenitrile), and sulfide (dimethyl trisulfide)] were observed on plants exposed to stress combinations, whereas emissions of six volatile classes were observed during temperature stress treatments alone (with the exception of nitriles and sulfides). Aphid density at high temperature combinations resulted in significantly higher isothiocyanate, ester, nitrile and sulfide proportions. The results of the present study provide an insight into the effects of temperature - aphid interactions on plant volatile emissions. [less ▲]

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See detailCoupling X-ray microtomography and macroscopic soil measurements: a method to enhance near saturation functions?
Beckers, Eléonore ULg; Plougonven, Erwan; Gigot, Nicolas et al

in Hydrology & Earth System Sciences (2014), 18

Agricultural management practices influence soil structure, but the characterization of these modifications and consequences are still not completely understood. In this study, we aim at improving water ... [more ▼]

Agricultural management practices influence soil structure, but the characterization of these modifications and consequences are still not completely understood. In this study, we aim at improving water retention and hydraulic conductivity curves using both classical soil techniques and X-ray microtomography in the context of tillage simplification. We show a good match for retention and conductivity functions between macroscopic measurements and microtomographic information. Microtomography highlights the presence of a secondary pore system. Analysis of structural parameters for these pores appears to be significant and offers additional clues for objects differentiation. We show that relatively fast scans supply not only good results, but also enhance near saturation characterization, making microtomography a highly competitive instrument for routine soil characterization. [less ▲]

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See detailEffects of Eisenia fetida on metal uptake of heavy metals from polluted soils by Vicia faba and Zea Mays
Lemtiri, Aboulkacem ULg; Liénard, Amandine ULg; Francis, Frédéric ULg et al

Poster (2014, February 26)

Earthworms are known to increase availability of heavy metals in soils and also play an important role in maintaining the structure and quality of soil. The introduction of earthworms into soils ... [more ▼]

Earthworms are known to increase availability of heavy metals in soils and also play an important role in maintaining the structure and quality of soil. The introduction of earthworms into soils contaminated with metals has been suggested as an aid for phytoremediation processes. In Belgium (Wallonia), a century of industrial metallurgic activities produced significant heavy metal soil pollution. A large q u a n t i t y o f s m e l t e r w a s t e c r e a t e d a g r a d i e n t o f zi n c, lead and cadmium c o n c e n t r a t i o n . The objectives of our study were to evaluate : (i) the potential toxicity of heavy metal elements on the epigeic earthworms Eisenia fetida and on two plants Zea mays and Vicia faba and (ii) to determine the effects of the earthworms on the growth and contaminants phytoextraction process. The combination of behavioural factor measurements (survival, growth, reproduction of earthworms), physico-chemical parameters such as metal absorption, bioaccumulation by earthworms, soil physico-chemical changes, and plant responses (root and shoot elongation, dried biomass,…) provided a valuable indication of pollutant bioavailability and ecotoxicity. After 56-days exposure, the results suggest that adult earthworms have a strong tolerance for heavy metals exposure, but the responses depend on metal elements. Earthworms modify the bioavailable heavy metals in root and shoot in the contaminated soils and their activities alter shoot and root biomass of V. faba and Z. mays. The presence of earthworms led to a change in physico-chemical caracteristics in contaminated soils. These results show that the ecological context for phytoremediation should be broadened by considering earthwom – plant – soil interactions as they influence both plant health and absorption of heavy metals. [less ▲]

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See detailarchiDART: a R package allowing root system architecture analysis using Data Analysis of Root Tracings (DART) output files
Delory, Benjamin ULg; Baudson, Caroline ULg; Brostaux, Yves ULg et al

Poster (2014, February 07)

In 2010, Le Bot et al presented a free and open-access software (Data Analysis of Root Tracings - DART) allowing the analysis of complex root system architectures from captured images, particularly across ... [more ▼]

In 2010, Le Bot et al presented a free and open-access software (Data Analysis of Root Tracings - DART) allowing the analysis of complex root system architectures from captured images, particularly across time series. Using this software, a user has to manually identify roots as a set of links. After vectorization of a root system, three final data sets (RAC, TPS and LIE) can be exported as table files containing several attributes for (a) each individual root (e.g. root length), (b) each observation day or (c) each point used to construct the vectorized root system respectively. These data sets can finally be used either to calculate derived root system architecture (RSA) parameters or to draw the root system architecture at selected observation dates. However when an experiment involves the analysis and comparison of many root systems, the calculation of RSA parameters for each data set and the drawing of the corresponding vectorized root systems become time-consuming. In this context, we developed a R package, called archiDART, allowing both the automatic calculation of common root architecture parameters and the X-Y plotting of vectorized root systems for selected observation dates. [less ▲]

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See detailOptimization of a formic/acetic acid delignification treatment on beech wood and its influence on the structural characteristics of the extracted lignins
Simon, Mathilde; Brostaux, Yves ULg; Vanderghem, Caroline ULg et al

in Journal of Chemical Technology & Biotechnology (2014), 89(1), 128-136

Background In order to replace petrochemicals by bio-based lignin products in a lot of high value-added applications, a formic/acetic acid treatment was adapted to beech wood (Fagus sylvatica L.) for ... [more ▼]

Background In order to replace petrochemicals by bio-based lignin products in a lot of high value-added applications, a formic/acetic acid treatment was adapted to beech wood (Fagus sylvatica L.) for lignin extraction. Results Beech wood particles were delignified at atmospheric pressure by a formic acid/acetic acid/water mixture. Cooking time and temperature were optimized for delignification, pulp yield and 2-furfural concentration. Response surface design analysis revealed that delignification yield increased with cooking time and temperature. Conclusion The multi-criteria optimization of delignification was used to find the ideal cooking conditions (5h07 min, 104.2°C) which could be satisfactory for the maximization of delignification (70.5%) and pulp yield (58.7%) and, to a lesser extent, for the minimization of 2-furfural production. Treatment conditions were found to influence the chemical structure of extracted lignins. Cooking time and temperature influenced inversely lignin molecular weights. [less ▲]

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See detailRole of larval host plant experience and solanaceous plant volatile emissions in Tuta absoluta (Lepidoptera: Gelechiidae) host finding behavior
Caparros Megido, Rudy ULg; De Backer, Lara; Ettaïb, Refki et al

in Arthropod-Plant Interactions (2014)

The tomato leafminer, Tuta absoluta (Lepi- doptera: Gelechiidae), is considered to be a major pest that damages tomato (Solanum lycopersicum L; Solanaceae) crops in South American, European, and ... [more ▼]

The tomato leafminer, Tuta absoluta (Lepi- doptera: Gelechiidae), is considered to be a major pest that damages tomato (Solanum lycopersicum L; Solanaceae) crops in South American, European, and Mediterranean countries. This insect species is polyphagous (i.e., feeds on many types of food); hence, it could also develop on other cultivated host plants, principally solanaceous plants, such as potato (S. tuberosum L.; Solanaceae) and eggplant (S. melongena L.; Solanaceae). Therefore, we tested the hypothesis that host plant choice by adult T. absoluta is influenced by plant volatile organic compounds and larval host plant experience. One tomato cultivar (cv.) ‘Money- maker’ and three potato cv. ‘Charlotte’ ‘Bintje,’ and ‘Nicola’ were tested. Using a flying tunnel, we observed that females reared on tomato preferred flying toward tomato and, to a lesser extent, potato cv. ‘Charlotte.’ These preferences might be explained by the high release of terpenes by these two plants. When conducting oviposition choice assays, we found no preference between tomato and potato in the number of eggs laid by females that had been previously reared on either host plant. This study indicates that the host finding behavior of T. absoluta is mediated by solanaceous volatiles, while oviposition behavior appears to depend on additional stimuli. These results provide baseline information for use in the development of new control strategies against T. absoluta using semiochemicals and plant breeding. [less ▲]

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See detailConsumer acceptance of insect-based meat substitutes
Caparros Megido, Rudy ULg; Gierts, Chloé; Blecker, Christophe ULg et al

Conference (2014)

Meat plays an important role in the consumption pattern of most European and North American consumers. Meat production is responsible for a well known environmental pressure due to the inefficient ... [more ▼]

Meat plays an important role in the consumption pattern of most European and North American consumers. Meat production is responsible for a well known environmental pressure due to the inefficient conversion of plant protein to meat protein and alternatives sources, such as insects or algae, will be rapidly required. In a recent theorical study, de Boer et al. (2013) show that consumers prefer to eat a hybrid meat product (i.e. a mix of meat and its substitute) rather than a pure meat substitute [3]. Based on these preliminary results, hedonic tests were realized to assess the acceptability of insect-based burgers in a target population composed of people from 15 to 25 years old, considered as the future insect consumers. Isolated in a tasting booth, each participant was invited to taste four burger samples containing a ratio of 20 gr of protein by 100 gr of burger. The first burger was prepared with 95% of grounded beef (1), the second with 95% of green lentil (2), the third with 45% of green lentil and 50% of mealworms (Tenebrio molitor L.; Coleoptera, Tenebrionidae) and the fourth with 45% of grounded beef burger and 50% of mealworms. The last 5% of each burger consists of an aromatization portion containing onions, carrots, tomato paste and garlic. Participants were asked to rate each sample on a 9-point hedonic scale, where extreme sides were noted from “extremely dislike” (left) to “extremely like” (right). Tukey post-hoc comparisons on the appreciation results showed that beef-based products (with or without mealworms) were relatively preferred to lentil-based products (with or without mealworms), probably because hybrid meat burgers seem more familiar to the consumers than vegetable burgers, and that no liking differences were noticed between the two beef-based burgers and between the two insect-based burgers. These results confirm that shape and appearance are key criteria in the acceptation of meat substitute by non-vegetarian consumers and that insects will preferentially be consumed, in the future, if they are presented in an invisible way and associated with familiar flavors. [less ▲]

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See detailReproductive ecology of Coula edulis Baill., source of a valuable non-timber forest product
Moupela, Christian ULg; Doucet, Jean-Louis ULg; Daïnou, Kasso ULg et al

in Tropical Ecology (2014), 55(3), 327-338

The reproductive ecology of Coula edulis (Olacaceae), source of a highly valuable non-timber product for African populations, has been investigated on a large tree sample size in a Gabonese forest for a 3 ... [more ▼]

The reproductive ecology of Coula edulis (Olacaceae), source of a highly valuable non-timber product for African populations, has been investigated on a large tree sample size in a Gabonese forest for a 3-year period, in order to propose options for its domestication. Reproduction is annual and the minimum tree diameter for flowering was 10.6 cm while the diameter for regular fructification was 23 cm. The annual diameter increment (ADI; mean = 0.22 cm year-1) was affected by crown exposure, but not by initial tree diameter or fruit production. Tree diameter influenced fruiting frequency and fruit production. There was a strong correlation between fruit production of 2011 and 2012 (Pearson's r = 0.85; P < 0.001), suggesting a high heritability of that trait. Phenotypical selection should be performed prior to any propagation activity. Moreover, as most of C. edulis fruits were sterile (64 %), we propose that sylvicultural strategies should be based on vegetative propagation. [less ▲]

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See detailAssociative learning of Nasonia vitripennis Walker (Hymenoptera: Pteromalidae) to methyldisulfanylmethane
Frederickx, Christine ULg; Verheggen, François ULg; Brostaux, Yves ULg et al

in Journal of Forensic Sciences (2014)

Traditional methods of volatile detection used by police typically consist of reliance on canine olfaction. However, dogs have some limitations such as cost of training and time of conditioning. The ... [more ▼]

Traditional methods of volatile detection used by police typically consist of reliance on canine olfaction. However, dogs have some limitations such as cost of training and time of conditioning. The possibility of using parasitic wasps for detecting explosives and narcotics has been developed. Moreover, wasps are cheap to produce and can be conditioned with impressive speed for a specific chemical-detection task. We examined the ability of Nasonia vitripennis Walker to learn and respond to methydisulfanylmethane (DMDS), a volatile discriminator of cadaver. The training aimed to form an association between an unconditioned stimulus (pupae) and the conditioned stimulus (odor source). After the training, the time spent of conditioned wasps in the DMDS chamber was measured. Statistical analysis showed that the increasing concentrations involved an increase in the time spent in the chamber containing DMDS. This study indicates that N. vitripennis can respond to DMDS, which provide further support for its development as a biological sensor. [less ▲]

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See detailEdible insects acceptance by belgian consumers: promising attitude for entomophagy development
Caparros Megido, Rudy ULg; Sablon, Ludovic; Geuens, Mélodie et al

in Journal of Sensory Studies (2013)

Entomophagy is not well accepted in Western European populations but it is common in the world. In the future, populations from developed countries should adapt to other sources of animal proteins because ... [more ▼]

Entomophagy is not well accepted in Western European populations but it is common in the world. In the future, populations from developed countries should adapt to other sources of animal proteins because traditional breeding of beef, poultry or pork will become unsustainable. This study was performed to assess the perception of entomophagy in the Belgian population. A slight neophobia was detected but people agreed to evaluate insect preparations. Various insect formulations (mealworms and house crickets) were prepared, and insects associated with known flavors and crispy textures were preferred. After a hedonic test, people seemed to be willing to eat and cook insects in the near future. The opportunity to introduce entomophagy in food habits of Western Euro- pean populations was positively concluded. Integration of edible insects in human food is a potential solution to replace other animal protein sources in a much more sustainable development and will deserve more attention in the future. [less ▲]

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See detailUse of response surface methodology for the optimization of the lipase-catalyzed synthesis of mannosyl myristate in pure ionic liquid
Galonde, Nadine ULg; Brostaux, Yves ULg; Richard, Gaetan ULg et al

in Process Biochemistry (2013), 48(11), 1914-1920

The purpose of the present study is to find the conditions allowing to reach the highest 24 h-yield(24 h- ) for the synthesis of mannosyl myristate catalyzed by the immobilized lipase B from Candida ... [more ▼]

The purpose of the present study is to find the conditions allowing to reach the highest 24 h-yield(24 h- ) for the synthesis of mannosyl myristate catalyzed by the immobilized lipase B from Candida antarctica (Novozym®435) in the ionic liquid (IL) [Bmpyrr][TFO] (1-butyl-1-methylpyrrolidinium tri-fluoromethanesulfonate). A full factorial design (FFD) was used in order to study the influence of three variables (temperature, mannose/vinyl myristate ratio and total substrate quantity) on the 24 h- . This design led to a model based on a second order polynomial response function. The resulting predicted con-tour plots have shown that the highest 24 h- should be obtained with high temperatures, low sugar/vinylester molar ratio and intermediate total substrate quantities (mmol). The model has been successfully verified and experimentally confirmed at the optimal conditions of 80◦C, substrate molar ratio of 1/10and total substrate quantity of 0.26 mmol leading to the highest predicted 24 h- of 72.2%. [less ▲]

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See detailTest modeling of the growth of self-fertilized embryos of Phaseolus vulgaris L. and Phaseolus coccineus L. genotypes
Nguema Ndoutoumou, Pamphile; Boussiengui Boussiengui, Gino; Ngakou, Albert et al

in African Journal of Plant Science (2013), 7(8), 310-316

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See detailHow closely are Pericopsis elata (Fabaceae) patches linked to past human disturbances in South-Eastern Cameroon
Bourland, Nils ULg; Cerisier, François; Daïnou, Kasso ULg et al

Conference (2013, June 26)

Studies conducted in the Congo Basin forests concluded that soil parameters and large disturbances induced by human activities since 3000–2000 BP could be the main driver for the persistence of long lived ... [more ▼]

Studies conducted in the Congo Basin forests concluded that soil parameters and large disturbances induced by human activities since 3000–2000 BP could be the main driver for the persistence of long lived light-demanding tall tree species. Today most of the timber species belong to this group, among them Pericopsis elata (Fabaceae). Like many other light-demanding trees, this species suffers from important regeneration problems. While the conditions for its establishment must have been met in the past, they obviously have become unfavourable. Because of ongoing logging activities and a natural decline of its populations, this species is recorded in both the IUCN Red List and the CITES Appendix II listings. Our goal was to investigate the roles of both pedological and anthropogenic factors in the persistence of forest patches characterized by this clustered species. Soil surveys, botanical inventories and anthracological excavations were conducted in three different forest sites located in south-eastern Cameroon. P. elata patches (3.3-14.7 ha) were studied and compared to their close surroundings. No statistical differences were observed between the results of botanical inventories conducted inside and outside the patches (Morisita-Horn indices from 0.69-0.77). Soils only differed in Fe content, but otherwise no significant differences could be observed. Charcoal is widespread and abundant in study sites, mostly inside the patches. Charcoal radiocarbon dating (2,150-195 BP) was consistent with decoration techniques of archaeological materials that we discovered. The average age of P. elata individuals coincides with fire events that occurred in a region where fires rarely occur naturally. We present evidence of past anthropogenic disturbances (human settlement, slash-and-burn cultivation) in the Congolese mixed moist semi-evergreen forest in south-eastern Cameroon. We discuss the potential influence of our findings on the management of light-demanding tall trees populations in a context of logging activities. [less ▲]

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