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See detailChemical composition, microstructure and physical properties of magnetically melt-textured bulk Bi2Sr2Ca0.8Dy0.2Cu2O8-y superconducting ceramics
Stassen, Sophie; Cloots, Rudi ULg; Vanderschueren, André et al

in Balachandran, U.; McGinn, P. J.; Abell, J. S. (Eds.) High Temperature Superconductors: Synthesis, Processing, and Large-Scale Applications. (1996)

Dysprosium doped Bi-based 2212 ceramics were synthesized by a melt-texturing growth process in a 1.2 T magnetic field, applied perpendicularly to the main axis of a cylindrical shape sample. Four well ... [more ▼]

Dysprosium doped Bi-based 2212 ceramics were synthesized by a melt-texturing growth process in a 1.2 T magnetic field, applied perpendicularly to the main axis of a cylindrical shape sample. Four well oriented and chemically defined phases forming successive layers were observed and characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The origin and composition of such layers is described. A novel aspect is the calcium solubility at the strontium site in 2212 phases, and the strontium solubility at the calcium site in 8250 structures. The texturing process was optimized with respect to the sample electrical resistivity and ac magnetic susceptibility. The critical current density was then evaluated. [less ▲]

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See detailThe Chemical compositions and the Antioxidant and Antimicrobial Activities of the Essential Oil of Rosemary Leaves from Eastern Morocco
Tahri, Mustapha; Imelouane, Bouchra; Amhamdi, Hassan et al

in Journal of Materials and Environmental Science (2015), 6(3), 666-672

The essential oils compositions of Rosmarinus. tournefortii wild plant, Rosmarinus. tournefortii domesticated plant, and Rosmarinus officinalis.L wild plant growing in different bio climates from eastern ... [more ▼]

The essential oils compositions of Rosmarinus. tournefortii wild plant, Rosmarinus. tournefortii domesticated plant, and Rosmarinus officinalis.L wild plant growing in different bio climates from eastern Morocco, was determined by GC-FID and GC–MS. Oils were assessed for their antimicrobial and antioxidant activities. A variation of chemical compositions attributed to varieties rather than to bio climates was revealed. α-Pinene (0.637% ; 44.22% ; 5.74%), Camphene (11.62% ; 6.52% ; 2.21%), ß-Pinene (14.72% ; 1.14% ; 3.71%), 1,8-Cineole (10.1% ; not identifying ; 56.51%) and Camphor (39.27% ; 7.64% ; 13.56%) were identified as the main constituents of R. tournefortii wild plant, R. tournefortii domesticated plant, and R. officinalis. L wild plant respectively. This study is based on the determination of the diameter of inhibition to moderate antimicrobial and antioxidant activities of oils revealed to be against eight bacteria tested. This was determined by 1,1-diphenyl-1-picrylhydrazyl (DPPH) assay. The highest antimicrobial and antioxidant activities were found in oils from Rosmarinus. tournefortii domesticated plant. [less ▲]

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See detailChemical constituents from Erythrina droogmansiana (Fabaceae), radical scavenging and antibacterial potential of some extracts and compounds
Talla, Emmanuel; Yaya Gbaweng, Joël; Mokale, Laurel et al

in Natural Products : An Indian Journal (2016), 12(1), 12-20

A new ceramide, droogmansiamide (1), was isolated from methanolic extract of roots wood of Erythrina droogmansiana, with eight known compounds namely 3-(3’,4’-methylenedioxyphenyl)-2,3-epoxypropanol (2 ... [more ▼]

A new ceramide, droogmansiamide (1), was isolated from methanolic extract of roots wood of Erythrina droogmansiana, with eight known compounds namely 3-(3’,4’-methylenedioxyphenyl)-2,3-epoxypropanol (2), erythrinasinate A (3), erythrinasinate B (4), abyssinone-IV-4'-methylether (5), erythrabyssin (6), phaseollidin (7), 4’-methoxylicoflavanone (8) and abyssinone-V-4'-methylether (9) respectively from methanolic extract of roots wood and EtOAc extract of roots bark of the same plant. Their structures were elucidated using spectroscopic methods (MS, NMR and IR) and by comparison with some data found in literature. Free radical scavenging (DPPH) and antibacterial potentials of extracts and compounds were also evaluated in this work. For radical scavenging, results showed that it is phaseollidin (7) which is responsible of radical scavenging potential in the ethyl acetate extract of roots barks with value of 1.31 mg/ml; for antibacterial, one of the tested compounds abyssinone-IV-4'-methylether (5) exhibited antibacterial activities against two strains: Providencia stuartiiATCC 29916 and Enterobacter aerogenes ATCC 13048 with MIC values of 25μg/ml. [less ▲]

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See detailChemical contamination along the Mediterranean French coast using Posidonia oceanica (L.) Delile above-ground tissues: a multiple trace element study
Luy, Nicolas; Gobert, Sylvie ULg; Sartoretto, Stéphane et al

in Ecological Indicators (2012), 18

Levels of Be, Al, V, Mn, Co, As, Se, Mo, Ag, Sn, Sb, Bi as well as of Cr, Fe, Ni, Cu, Zn, Cd and Pb in Posidonia oceanica (L.) Delile from the Mediterranean French coast were analysed using DRC ICP-MS ... [more ▼]

Levels of Be, Al, V, Mn, Co, As, Se, Mo, Ag, Sn, Sb, Bi as well as of Cr, Fe, Ni, Cu, Zn, Cd and Pb in Posidonia oceanica (L.) Delile from the Mediterranean French coast were analysed using DRC ICP-MS. The first twelve elements have not been well studied and can be considered to be potential pollutants as a result of potentially increased levels resulting from anthropogenic activities. Spatial variation and/or compartmentalization were found for all trace elements. Except for Al, Cr, Fe, Cu and Ag, most trace elements were preferentially accumulated in photosynthetic tissues, suggesting uptake from the water column. Moreover, for Be, V, Mn, Co, Ni, As, Mo, Sb, Sn and Pb, adult leaves had higher levels than intermediate leaves, suggesting low kinetics of accumulation. Levels in the third intermediate leaf were representative of the average levels of the integral shoot, and thus can be used alone in chemical biomonitoring. For most of the twelve little-studied trace elements, the background levels of the northwestern Mediterranean Sea can be measured, and their spatial variation can be related to anthropogenic activities. Levels of the seven widely studied trace elements seem to decrease or stabilize over time, probably due to their reduced anthropogenic use. These observations show that P. oceanica is a sensitive bioindicator for the monitoring of chemical contamination of a large number of trace elements. [less ▲]

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See detailChemical contamination in fish species from rivers in the North of Luxembourg: Potential impact on the Eurasian otter (Lutra lutra).
Boscher, Aurore; Gobert, Sylvie ULg; Guignard, C. et al

in Chemosphere (2010), 78

Contamination levels of PCBs, and of the heavy metals cadmium (Cd), lead (Pb) and mercury (Hg) were analyzed in four fish species from seven rivers in the North of Luxembourg. During August and September ... [more ▼]

Contamination levels of PCBs, and of the heavy metals cadmium (Cd), lead (Pb) and mercury (Hg) were analyzed in four fish species from seven rivers in the North of Luxembourg. During August and September 2007, 85 samples of fish were collected belonging to four species: the stone loach (Barbatula barbatula, n = 12 pools), the chub (Squalius cephalus, n = 36), the barbel (Barbus barbus, n = 23) and eel (Anguilla anguilla, n = 14). The concentration of seven indicator PCBs (P7PCBs) reached a mean of 39 ng g􏰀1 and varied between 4.0 and 346.2 ng g􏰀1 (wet wt) depending on the site and species. Fish collected at Wal- lendorf on the Our River and sites on the Wiltz and the Clerve rivers showed the highest concentrations for PCBs. In comparison with 1994, PCB levels in fish decreased strongly during the last decade in these rivers. Lead was detected at low levels (0–181.4 ng g􏰀1 wet wt). Mercury concentrations ranged between 10.3 and 534.5ngg􏰀1 (wet wt) exceeding maximum tolerable levels for human consumption of 500 ng g􏰀1 in two fish out of 85. Chubs and eels from the Sûre River were the most contaminated by mer- cury. Cadmium levels varied between 4.0 and 103.9 ng g􏰀1 (wet wt). In addition to mercury in fish, cad- mium was the most problematic pollutant on the Our, the Wiltz, the Clerve and the Troine Rivers, because values found in 20% of fish exceeded the threshold of about 10–50 ng g􏰀1 (wet wt) recommended for human health. The total PCB level predicted to accumulate in livers from otter potentially feeding on these fish based on a previously published mathematical model is 37.7 lg g􏰀1 (lipid wt), which is between a proposed ‘‘safe level” and a ‘‘critical level” for otters. Rivers in the North of Luxembourg are thus to some extent polluted, and the establishment of otter populations could be affected by current levels of contamination. [less ▲]

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See detailChemical control of Haplodiplosis marginata (Diptera: Cecidomyiidae)
Censier, Florence ULg; Chavalle, Sandrine ULg; Wittouck, Daniël et al

Poster (2012, May)

The saddle gall midge, Haplodiplosis marginata (von Roser), is a European pest of cereals. The larvae overwinter into the soil. Emergence of adult midges occurred during the spring and after mating ... [more ▼]

The saddle gall midge, Haplodiplosis marginata (von Roser), is a European pest of cereals. The larvae overwinter into the soil. Emergence of adult midges occurred during the spring and after mating, females lay their eggs on the leaves of cereals and several grasses. Eggs hatch a few days later; young larvae crawl to the stem and introduce themselves between the leaf sheath and the stem, were the larvae develop. As reaction of the presence of midge larvae, stem produce a longitudinal depression of 6-7 mm ended by two ridges looking as a horse saddle. When galls are numerous, they can cause break of stems and important yield losses. The saddle gall midge, which is a major pest in Central Europe, is not very well known in the Western part of the continent. It had already caused huge damage during outbreak periods. The last one reported in Belgium and in The Netherlands occurred between 1965 and 1970. Later, it was never reported again until 2010, where large populations and severe damage were observed, especially in the Flemish polders, a region with clay soils where wheat is cropped intensively. Faced with the resurgence of this pest, we sought to develop effective curative control. To date, crops chemical protection seems to be the only solution in case of heavy emergences. Experimentation was conducted in a highly infested field (Meetkerke, Belgian Polders), according to a randomized complete block arrangement with four replications. Foremost, a lambdacyhalothrin-based insecticide was used to evaluate efficiency of several protection schemes, ranging between one and four spray(s). The large spread of flights observed during the 2011 spring allowed to highlight the effect of treatment date on the attack intensity and also on the galls distribution along the stem, on the different internodes. Moreover, several insecticides already registrated in cereals against aphids were compared for their efficacy against saddle gall midge. Studied pyrethroids have shown a very good efficacy, ranging between 75 % and 87 %, when applied twice with a 2 weeks interval. To be efficient, chemical spray must be synchronized with the flights and egg laying periods. Monitoring the phenology of flights is thus essential as part of integrated pest management against saddle gall midge. [less ▲]

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See detailChemical control of Haplodiplosis marginata von Roser (Diptera : Cecidomyiidae)
Censier, Florence ULg; Chavalle, Sandrine ULg; Wittouck, Daniel et al

in Communications in Agricultural and Applied Biological Sciences (2012), 77(4), 667-675

The saddle gall midge, Haplodiplosis marginata (von Roser), has been detected in Belgium since 2010, after several decades without any reporting. It had indeed caused serious damages between 1965 and 1970 ... [more ▼]

The saddle gall midge, Haplodiplosis marginata (von Roser), has been detected in Belgium since 2010, after several decades without any reporting. It had indeed caused serious damages between 1965 and 1970. This insect is a European cereal pest whose larvae feed on stems and engender saddle-shaped depressions, resulting in yield losses. Face with the resurgence of this pest, it was decided to study its spatial distribution and, because serious damages were observed in some regions, to develop effective curative control. To date, chemical protection seems to be the only immediate solution in case of heavy emergences. Experimentation was conducted in a highly infested field (Meetkerke, Belgian Polders), according to a randomized complete blocks arrangement with four replications. <br />Foremost, a lambdacyhalothrin-based insecticide was used to evaluate efficiency of several protection schemes, ranging between one and four spray(s). The large spread of flights observed during the 2011 spring allowed to highlight the effect of treatment date on the attack intensity and also on the galls distribution along the stem, on the different internodes: the lower internodes were protected by the early sprayings, while last sprayings induced reduction of galls number on the upper internodes. Moreover, several insecticides already registrated in cereals against aphids were compared for their efficacy against saddle gall midge. Studied pyrethroids have shown a very good efficacy, ranging between 75 % and 87 %, when applied twice with a 2 weeks interval. To be efficient, insecticide applications must thus be synchronized with the flights and egg-laying periods. Monitoring the phenology of flights is thus essential as part of integrated pest management against saddle gall midge. [less ▲]

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See detailChemical ecology in forensic entomology
Dekeirsschieter, Jessica ULg; Frederickx, Christine ULg; Verheggen, François ULg et al

Scientific conference (2010, January 07)

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See detailChemical Ecology of Aphids (Hemiptera: Aphididae)
Boullis, Antoine ULg; Verheggen, François ULg

in VILCINSKAS, Andreas (Ed.) Biology and Ecology of Aphids (2016)

Aphids are widespread insects considered as crop pest throughout the world. In order to control them, different techniques are known. The study of aphid-related semiochemicals is one topic recently ... [more ▼]

Aphids are widespread insects considered as crop pest throughout the world. In order to control them, different techniques are known. The study of aphid-related semiochemicals is one topic recently studied in integrated pest management, used to control aphid outbreaks. These semiochemicals include those involved in intraspecific communication, in communication among different trophic levels, those which attract or repel aphids, or those which enhance the efficiency of aphid natural enemies. This book chapter summarises the recent findings on aphid chemical ecology, from the discovery of molecules of interest, to their use in IPM methods. [less ▲]

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See detailThe chemical ecology of Harmonia axyridis
Sloggett, John; Magro, Alexandra; Verheggen, François ULg et al

in Roy, Helen; Ware, Remy; Handley-Lawson, Lori (Eds.) et al Invasive arthropod predators and parasitoids: an ecological approach (2011)

We review the chemical ecology of the ladybird beetle Harmonia axyridis from the perspective of its invasiveness and the deleterious effects it exerts in the regions it has colonised. We outline the ... [more ▼]

We review the chemical ecology of the ladybird beetle Harmonia axyridis from the perspective of its invasiveness and the deleterious effects it exerts in the regions it has colonised. We outline the nature and quantification of its chemical defence, and discuss the protection this provides from natural enemies, particularly intraguild predators. We consider the role played by infochemicals in location of prey, intraspecific communication and intraguild interactions; we also discuss the role of prey allelochemicals in relation to H. axyridis extreme dietary generalism. Harmonia axyridis poses a number of practical problems for human health and well-being, including “lady beetle taint” wine contamination and problems consequent on large aggregations overwintering in buildings. We discuss chemical insights into these issues and, in particular, how attractants and repellents might help manage H. axyridis populations. We conclude by discussing future perspectives for research. [less ▲]

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See detailThe chemical ecology of Harmonia axyridis
Sloggett, John; Magro, Alexandra; Verheggen, François ULg et al

in BioControl (2011), 56

We review the chemical ecology of the ladybird beetle Harmonia axyridis from the perspective of its invasiveness and the deleterious effects it exerts in the regions it has colonised. We outline the ... [more ▼]

We review the chemical ecology of the ladybird beetle Harmonia axyridis from the perspective of its invasiveness and the deleterious effects it exerts in the regions it has colonised. We outline the nature and quantification of its chemical defence, and discuss the protection this provides against natural enemies, particularly intraguild predators. We consider the role of infochemicals in location of prey, intraspecific communication and intraguild interactions. We also discuss the role of prey allelochemicals in relation to H. axyridis extreme dietary generalism. Harmonia axyridis poses a number of practical problems for human health and well-being, including “ladybug taint” wine contamination and problems resulting from large aggregations overwintering in buildings. We consider chemical insights into these issues and, in particular, how attractants and repellents might help manage H. axyridis populations through a push–pull strategy. We conclude by discussing future perspectives for research. [less ▲]

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See detailThe chemical ecology of Harmonia axyridis
Sloggett, John; Magro, Alexandra; Verheggen, François ULg et al

in Bulletin OILB/SROP = IOBC/WPRS Bulletin (2013), 94

In the recent SI of BioControl and resultant book from this working group (Roy et al., 2012), we contributed a review paper on the chemical ecology of the invasive aphidophagous ladybird Harmonia axyridis ... [more ▼]

In the recent SI of BioControl and resultant book from this working group (Roy et al., 2012), we contributed a review paper on the chemical ecology of the invasive aphidophagous ladybird Harmonia axyridis (Sloggett et al., 2011). This paper focused on both the pure and applied aspects of this subject, including sections on: (1) chemical defence; (2) foods, feeding and reproduction; (3) H. axyridis chemistry, humans and human activity, and (4) future research perspectives [less ▲]

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See detailThe chemical ecology of ladybird beetles
Durieux, Delphine ULg; Verheggen, François ULg; Vandereycken, Axel ULg et al

Conference (2010, May 05)

Ladybird beetles (Coleoptera: Coccinellidae) use a wide variety of semiochemicals to communicate with each other, e.g. finding a mate, protecting themselves from predation or cannibalism, finding a ... [more ▼]

Ladybird beetles (Coleoptera: Coccinellidae) use a wide variety of semiochemicals to communicate with each other, e.g. finding a mate, protecting themselves from predation or cannibalism, finding a shelter to overwinter or ensuring a better survival for their offspring. But chemical communication upon ladybeetles has also found recently to occur with their prey, their prey-host plants and even within their interactions with their natural enemies. Thorough studies on ladybird behaviours towards these compounds could lead to their practical implementation in integrated strategies using ladybirds to control pests, like aphids or mealybugs. [less ▲]

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See detailChemical Ecology of the Colorado Potato Beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), and Potential for Alternative Control Methods
Sablon, Ludovic ULg; Dickens, Joseph C.; Haubruge, Eric ULg et al

in Insects (2013), 4(1), 31-54

The Colorado potato beetle (CPB) has been a major insect pest to potato farming for over 150 years and various control methods have been established to reduce its impact on potato fields. Crop rotation ... [more ▼]

The Colorado potato beetle (CPB) has been a major insect pest to potato farming for over 150 years and various control methods have been established to reduce its impact on potato fields. Crop rotation and pesticide use are currently the most widely used approaches, although alternative methods are being developed. Here we review the role of various volatile and nonvolatile chemicals involved in behavior changes of CPB that may have potential for their control. First, we describe all volatile and nonvolatile chemicals involved in host plant localization and acceptance by CPB beetles, including glycoalcaloids and host plant volatiles used as kairomones. In the second section, we present the chemical signals used by CPB in intraspecific communication, including sex and aggregation pheromones. Some of these chemicals are used by natural enemies of CPBs to locate their prey and are presented in the third section. The last section of this review is devoted a discussion of the potential of some natural chemicals in biological control of CPB and to approaches that already reached efficient field applications. [less ▲]

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See detailChemical Experts & their roles in the Belgian Sugar Industry
Melard, François ULg

Conference (1998, November 25)

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See detailChemical fixation of CO2 with epoxides: towards the synthesis of cyclic carbonates, precursors of CO2-based polyurethanes
Gennen, Sandro ULg; Grignard, Bruno ULg; Gilbert, Bernard ULg et al

Poster (2014, May 20)

Due to concerns about global warming combined with the decrease of fossil resources, the chemical transformation of carbon dioxide into added-value products has gained interest in both academic and ... [more ▼]

Due to concerns about global warming combined with the decrease of fossil resources, the chemical transformation of carbon dioxide into added-value products has gained interest in both academic and industrial fields. To date, the chemical fixation of CO2 onto epoxides is one of the most promising ways to valorize carbon dioxide at an industrial scale . Indeed, cyclic carbonates are useful intermediates for polycarbonates and polyurethanes synthesis or can be used as electrolytes in lithium ion batteries. Although fixation of carbon dioxide onto epoxides has been extensively studied, the design of highly effective catalysts still remains a challenge. Here, we present a new highly efficient biocomponent organocatalyst based on the use of an ammonium salt (TBAI) in combination with single or double hydrogen bond donors activators (typically fluorinated alcohols). [less ▲]

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See detailChemical Food Safety of Aquaculture Products from South-East Asia
Scippo, Marie-Louise ULg; Kestemont, Patrick

Conference (2014, December 04)

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