Showing papers by "University of Monastir published in 1998"
TL;DR: Investigation of resistance to the organophosphates temephos and chlorpyrifos, the carbamate propoxur, the pyrethroid permethrin, and the organochloride DDT in Tunisian populations of Culex pipiens pipiens collected between 1990 and 1996 showed that increased detoxification had only a minor role in resistance, although several over-produced esterases known to be involved in organoph phosphate resistance were detected.
Abstract: Resistance to the organophosphates temephos and chlorpyrifos, the carbamate propoxur, the pyrethroid permethrin, and the organochloride DDT was investigated in Tunisian populations of Culex pipiens pipiens (L.) collected between 1990 and 1996. Resistance to temephos was uniformly low, reaching 10-fold in the most resistant population. In contrast, resistance to chlorpyrifos was highly variable, reaching the highest level (> 10,000-fold) recorded worldwide. The chlorpyrifos-resistant populations also were highly resistant to propoxur. Some populations also showed high resistance to permethrin (up to 5,000-fold) and moderate resistance to DDT (approximately 20-fold). Bioassays conducted in the presence of synergists showed that increased detoxification had only a minor role in resistance, although several over-produced esterases known to be involved in organophosphate resistance were detected. To better understand the factors influencing the distribution of resistance in Tunisia, the polymorphism of genes involved in organophosphate resistance (i.e., over-produced esterases and insensitive acetylcholinesterase) was investigated in relation to the genetic structure of populations studied by analyzing the electrophoretic polymorphism of "neutral" genes. Over the area studied, and despite a high level of gene flow, resistance genes showed a patchy distribution. Results are discussed in relation to the selection pressure caused by insecticide treatments.
93 citations
TL;DR: In this article, it was shown that the formation of C16 and C24 ethers arises from the coupling of C8 units within dimeric palladium intermediates with the telogen acting as a bridging ligand.
17 citations
14 Dec 1998
TL;DR: Regardless of the switch state, the bond graph formalism application to power semiconductor devices, combining the electrical and thermal phenomena, is presented and a reduction procedure application to the semiconductor device thermal effects is proposed in order to obtain a reduced electrothermal bond graph model.
Abstract: Faced with the problem of modeling complex and mixed-domain dynamic systems, system engineers use the bond graph formalism. Bond graph techniques are now used for modeling semiconductor devices in power electronics field. To have accurate models of power devices, it is necessary to take into account the thermal phenomena modeled by a thermal network. The thermal network describes the heat flow and the temperature evolution from the chip surface through the package and heat sink. To model these semiconductor devices, the bond graph model of the thermal and electrical parts must be described to illustrate how they are coupled, in order to build the device electrothermal model. In this paper, regardless of the switch state, the bond graph formalism application to power semiconductor devices, combining the electrical and thermal phenomena, is presented. A reduction procedure application to the semiconductor device thermal effects is also proposed in order to obtain a reduced electrothermal bond graph model.