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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Selective chemical control techniques for the desert locust, Schistocerca gregaria (Orthoptera: Acrididae)

El-gadgoud, Khaled Mohamed January 1999 (has links)
No description available.
32

Studies of the metabolism of permethrin

Davies, H. Y. January 1983 (has links)
No description available.
33

Soil biomass changes induced by selected pesticide application

Jones, Alwyn Lloyd January 1992 (has links)
No description available.
34

Bioremediation of the organophosphate pesticide, coumaphos, using microorganisms immobilized in calcium-alginate gel beads

Ha, Jiyeon 25 April 2007 (has links)
Coumaphos is an organophosphate insecticide used predominantly by the US Department of Agriculture, Animal and Plant Health Inspection Services for its tick eradication program. Bioremediation of the hydrolysis products of coumaphos, chlorferon and diethylthiophosphate (DETP), using Ca-alginate immobilized cells was the focus of this research. Consortia of indigenous microorganisms capable of degrading chlorferon and DETP were isolated separately. Since chlorferon inhibited both chlorferon-degrading and DETP-degrading organisms, it was not possible to enrich a consortium of organisms for simultaneous degradation of chlorferon and DETP. A two-step growth procedure was developed for degradation studies to provide biomass acclimated to the target compound and reaction medium since cells lost their degradation activity during the growth in a rich medium. Without acclimation, approximately a week-long lag period was required before degradation was initiated. Optimum reaction conditions were found for the degradation of chlorferon and DETP using free cells. Reaction kinetics of chlorferon and DETP were determined using enzyme kinetics because cell growth was not observed during the degradation. Chlorferon degradation followed substrate inhibition kinetics and DETP degradation followed simple Michaelis-Menten kinetics. A calcium-alginate immobilized cell system was developed, and the optimum bead loadings in the reactor were determined. Degradation rates for immobilized cells were enhanced up to five times that for free cells in untreated cattle dip (UCD) solution. The enhanced degradation of immobilized cells was due to protection of the cells from inhibitory substances present in the UCD solution. In addition, physiological changes of cells caused by Ca-alginate immobilization may have contributed to a slightly increased reaction rate in pure solution. Diffusion coefficients of chlorferon and DETP into Ca-alginate gel beads were studied to assist in designing and operating bioreactor systems. Diffusion coefficients of chlorferon and DETP increased with increasing agitation speed and decreasing substrate concentration. Increased cell concentration in gel beads caused lower diffusivity. Calcium-alginate gel beads used in this study were not subject to diffusional limitations. Both external and internal mass transfer resistances were negligible, and the degradation rate inside Ca-alginate gel beads was reaction-limited.
35

Bioremediation of the organophosphate pesticide, coumaphos, using microorganisms immobilized in calcium-alginate gel beads

Ha, Jiyeon 25 April 2007 (has links)
Coumaphos is an organophosphate insecticide used predominantly by the US Department of Agriculture, Animal and Plant Health Inspection Services for its tick eradication program. Bioremediation of the hydrolysis products of coumaphos, chlorferon and diethylthiophosphate (DETP), using Ca-alginate immobilized cells was the focus of this research. Consortia of indigenous microorganisms capable of degrading chlorferon and DETP were isolated separately. Since chlorferon inhibited both chlorferon-degrading and DETP-degrading organisms, it was not possible to enrich a consortium of organisms for simultaneous degradation of chlorferon and DETP. A two-step growth procedure was developed for degradation studies to provide biomass acclimated to the target compound and reaction medium since cells lost their degradation activity during the growth in a rich medium. Without acclimation, approximately a week-long lag period was required before degradation was initiated. Optimum reaction conditions were found for the degradation of chlorferon and DETP using free cells. Reaction kinetics of chlorferon and DETP were determined using enzyme kinetics because cell growth was not observed during the degradation. Chlorferon degradation followed substrate inhibition kinetics and DETP degradation followed simple Michaelis-Menten kinetics. A calcium-alginate immobilized cell system was developed, and the optimum bead loadings in the reactor were determined. Degradation rates for immobilized cells were enhanced up to five times that for free cells in untreated cattle dip (UCD) solution. The enhanced degradation of immobilized cells was due to protection of the cells from inhibitory substances present in the UCD solution. In addition, physiological changes of cells caused by Ca-alginate immobilization may have contributed to a slightly increased reaction rate in pure solution. Diffusion coefficients of chlorferon and DETP into Ca-alginate gel beads were studied to assist in designing and operating bioreactor systems. Diffusion coefficients of chlorferon and DETP increased with increasing agitation speed and decreasing substrate concentration. Increased cell concentration in gel beads caused lower diffusivity. Calcium-alginate gel beads used in this study were not subject to diffusional limitations. Both external and internal mass transfer resistances were negligible, and the degradation rate inside Ca-alginate gel beads was reaction-limited.
36

Stories in the Sediment: DDD Use at Expo 67

Graham, ANNA 31 May 2012 (has links)
The toxic, persistent pesticide dichlorodiphenyldichloroethane (DDD) was used liberally prior to and during the World Exposition of 1967 (Expo 67) on Île Sainte-Hélène in Montréal to reduce the population of nuisance Trichoptera insects (also called caddisflies or shadflies) in the area. Sixteen thousand kilograms were applied over six periods in two years. Despite reports by the project leaders that the practice was not detrimental to the ecosystem and that DDD was not detected downstream in significant concentrations following applications to the river, further investigation was required to determine the occurrence of the pesticide, and its concentrations. Given the large volume of pesticide that was applied to the river, I hypothesized that there would be a strong DDD signal in sediments downstream of the Expo 67 site. I obtained a sediment core from the bay of Île de Grâce at the mouth of Lac St Pierre in the St. Lawrence River, downstream of Montréal. The core was sliced, dated radioisometrically, and analysed for the presence of dichlorodiphenyltrichloroethane (DDT) and related pesticides using gas chromatography. The isotopes cesium-137 (137Cs), radium-226 (226Ra), and lead-210 (210Pb) were used to establish dates of sediment deposition. Loss on ignition was used to determine organic carbon content. Stable lead content was analysed because it may also support sediment ages. Concentrations of DDT, DDD, and dichlorodiphenylethylene (DDE) ranged from below the detection limit to 3.3 parts per billion (ppb), 57.7 ppb, and 17.1 ppb, respectively. Adjusting the concentrations to reflect organic carbon content did not significantly affect the trend in concentration by depth. Peaks in DDD concentrations and related compounds were discovered that correspond to the Expo 67 applications. These findings demonstrate that DDD was present in unusually high concentrations (well above the probable effect level of 8.51 ppb (Ontario Ministry of the Environment)) in the St. Lawrence River in 1967, potentially exposing a wide variety of organisms. This finding may also be used to inform future decisions regarding the management of the St. Lawrence Seaway. I also investigated the role of fragmentation, specialisation, and interdisciplinarity in this research, and critically examined the historical context of this project in order to pursue knowledge of this field with as full an understanding of it as possible. / Thesis (Master, Environmental Studies) -- Queen's University, 2012-05-31 02:27:28.215
37

A theoretical study of photochemical stability

Migani, Annapaola January 2001 (has links)
No description available.
38

Laser desorption and high resolution studies in quadrupole ion trap mass spectrometry

Bristow, Anthony Walter Thomas January 1996 (has links)
No description available.
39

Preventive behavior on pesticide usage among the rice farmers in Muang district, Suphanburi province, Thailand /

Nguyen, Thi Phuong Mai, Kitti Shiyalap, January 2004 (has links) (PDF)
Thesis (M.P.H.M. (Primary Health Care Management))--Mahidol University, 2004.
40

Development and characterization of resistance to the Cry1F toxin from Bacillus thuringiensis Berliner in the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae)

Pereira, Eliseu J. G. January 1900 (has links)
Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed April 26, 2007). PDF text: v, 109 p. : ill. UMI publication number: AAT 3229553. Includes bibliographical references. Also available in microfilm and microfiche formats.

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