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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.
11

Determination of pesticide residues on some commodities in the United Arab Emirates /

Muhairi, Saeed M. Al. January 2001 (has links) (PDF)
Thesis (M. Phil.)--University of Queensland. / Includes bibliographical references.
12

Cloning and expression of herbicide-specific single chain antibody fragments in Escherichia coli and Nicotiana tabacum

Learmonth, Dianne January 1997 (has links)
An anti-diuron scAb fragment was produced and expressed in <I>E. coli.</I> Characterization by ELISA demonstrated that the scAb displayed a similar binding profile to the parent monoclonal antibody, although its binding sensitivity appeared to be 10-50 times lower. Analysis of purified samples by HPLC showed the presence of scAb in both monomeric and dimeric forms. Expression yield of the anti-diuron scAb was low (0.05 mg/l culture volume), and attempts to reduce the toxicity of production in <I>E. coli</I>, using alternative expression vectors, were not successful. Production in an <I>E. coli</I> strain which allowed cytoplasmic folding resulted in an increase in yield of soluble scAb, but this antibody material showed reduced stability. The anti-atrazine scAb was expressed in tobacco. Although the levels of scAb produced were lower than might have been expected (0.014% total soluble protein), the scAb was fully functional and exhibited a binding affinity similar to that of bacterially-produced scAb. BIAcore analysis of affinity purified samples indicated a binding affinity comparable to that of the parental Mab. In competition ELISA, the scAb showed a concentration-dependent reduction in antigen binding in the presence of free atrazine. Binding sensitivity of the scAb for atrazine, and for the closely related triazine propazine, were very similar, while binding sensitivity for simazine was 10 times lower. Bacterially-produced anti-atrazine scAb demonstrated similar binding sensitivities for the atrazine analogues.
13

Air jet behaviour in porous structures with application to orchard spraying

Cant, Ross James January 1999 (has links)
No description available.
14

Extraction and photolysis of pesticides on soil

Fitzpatrick, Lisa Jane January 2000 (has links)
No description available.
15

Esterases as indicators of exposure of birds to pesticides

Thompson, H. M. January 1988 (has links)
No description available.
16

Laboratory studies on the effect of 'stress' on the susceptibility of the diamond moth (Plutella xylostella) and the rose-grain aphid (Metapolophium dirhodum) to insect pathogens

Schuler, Tanja H. January 1995 (has links)
No description available.
17

Pesticide residues in cucumbers cultivated in Bangladesh

Haag, Jennie, Landahl, Anna January 2014 (has links)
Pesticides are widely used for preventing crop losses due to pest attack. In Bangladesh, the food safety and health of farmers are being compromised as a result of poor regulation concerning usage of pesticides in food production. The aim of this study was to identify and quantify pesticides applied on cucumber crops in Bangladesh. A method for extraction and clean-up was developed to allow the quantification of four pesticides by GC-ECD in vegetable samples, specifically cucumber. The accuracy of the method was validated using recovery and its precision by studying the standard deviation and relative standard deviation. Analysis of cucumber samples obtained in the field showed no traces of the target pesticides. The results indicate that different types of chemicals are used on the examined crops. It is also believed that the growth habit of cucumber may affect the exposure to pesticides. To overcome the health hazards, restrictions regarding the types and quantities of chemicals used on the fields need to be implemented. Further studies would benefit from being executed in a controlled environment, and monitoring of which substances that are applied at which amounts.
18

The movement of pesticides within a mixed land use catchment

Llewellyn, Neville January 1999 (has links)
Although the application of UK non-agricultural pesticides (mainly herbicides) comprises only 3% of the total amount used, similar concentrations of agriculturally and non-agriculturallyderived pesticides are routinely detected in surface waters. This has led to concern regarding the contamination of drinking water resources at concentrations above the statutory limits of the EC Drinking Water Directive (ECDWD), and the consequent risk to human health. Before the risks to drinking water resources can be fully assessed, it is important to understand and subsequently predict the chronic and transient levels of herbicide occurrence in receiving surface waters as a result of their normal application. The factors which influence herbicide transport to the aquatic environment from sites of application, particularly from the wide variety of application substrates, are not fully understood. This project addresses this lack of knowledge through an eighteen-month programme (January 1992-March 1993) of storm event herbicide monitoring on a mixed land use catchment at North Weald (Essex) which periodically received applications of common agricultural and non-agricultural herbicides including chlorotoluron, isoproturon, diuron, simazine and atrazine. To support the field monitoring programme a robust multi-residue pesticide method was developed for the simultaneous determination of the previously mentioned compounds from storm water. This was based on liquid-liquid extraction into dichloromethane and high performance liquid chromatography using photo diode array detection. The pesticide runoff data from agricultural land agreed with similar experiments carried out in the UK. The ECDWD was frequently exceeded in baseflow conditions and more frequently during storm event periods. The extent of the exceedance was found to be related to the period which had elapsed between the herbicide application and the timing of the surface water sampling. The range of application losses for the agricultural data-set was 4.0xlO-4-O.204% (median; 4.6x10-2%). The range of peak storm event concentrations was 0.03-10.0jJg/1 (median; 0.34pg/I). Similar exceedances of the ECDWD were observed during storm and non-storm conditions for discharged waters from the urban land area of the catchment. For the urban runoff data-set, the range of application losses was 0.01-45.1% (median; 0.28%) and the range of peak storm event concentrations was 0.2-238.4pg/1 (median; 0.7pg/l). The results of the monitoring programme show that the underlying factor that differentiated between the fates of herbicides applied to the North Weald catchment was the difference in the application substrate properties. Specifically, the hard surfaces, where low infiltration capacity promotes the generation of relatively high volumes of surface runoff and where poor retention behaviour exists, allow applied herbicides to be readily transported in storm event runoff to receiving surface waters. The simazine, isoproturon, chlorotoluron and diuron runoff data produced during the monitoring programme were successfully modelled using the fugacity-based Soilfug model. In the case of chlorotoluron, this model s performance was compared with a statistical model produced using multiple linear regression analysis, which showed the former approach to be superior since it required less input data and was not site specific.
19

Sorption and release of pesticides in soils : the role of chemical nature of soil organic matter / Riaz Ahmad.

Ahmad, Riaz January 1999 (has links)
Bibliography: leaves 198-227. / xx, 260 leaves, [3] leaves of plates : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aims of this study were: 1. to examine the sorption behaviour of selected nonionic and ionic pesticides in a range of soils; 2. to characterise the nature of soil organic matter in a diverse group of soils and relate the structural and molecular variations of organic matter to sorption of nonionic pesticides; and 3. to study the release behaviour of carbaryl and ethion from two historically contaminated soils and to elucidate the mechanisms of their aging/sequestration. (abstract) / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil and Water, 1999
20

Pesticide regulatory actions and the development of pest resistance : a dynamic bioeconomic model /

Kazmierczak, Richard Francis, January 1991 (has links)
Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 284-299). Also available via the Internet

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