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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.
1

The ecology of stored grain insects in Zimbabwe and their control using diatomaceous earths with particular reference to the grain moth Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae)

Mvumi, Brighton Marimanzi January 2001 (has links)
No description available.
2

The development of a commercial production process for p-menthane-3,8-diol

Rust, Nico January 2009 (has links)
The synthesis of p-menthane-3,8-diol via the acid-catalyzed cyclization of citronellal in a dilute aqueous sulphuric acid medium was investigated using conventional batch and continuous systems in order to develop a commercial production process for said p-menthane-3,8-diol (PMD). The batch studies conducted during the first part of this study showed that the formation of PMD from citronellal occurs via an intra-molecular Prins reaction that results in the formation of both the desired PMD product, as well as the partially hydrated isopulegol. It was shown that the formationof the by- product, PMD-acetal, results from the reaction between an intermediate, 5-methyl-2- isopropylcyclohexanol, and the citronellal starting material, and not from the reaction between PMD and citronellal as previously reported. Kinetic studies confirmed the existence of a complicated kinetic model. The formation of PMD from citronellal displayed typical pseudo first order kinetics up to conversions of 70 after which the kinetic model becomes complicated as the result of the establishment of quasi equilibrium reactions between PMD and isopulegol (dehydration of PMD and hydration of isopulegol) and between PMD the PMD-acetal, both systems being acid catalysed. The PMD-acetal formation reaction appears to be second order with respect to PMD. Scale-up studies of the batch process to 30L and 50L scales showed that it would be extremely difficult to limit the level of PMD-acetal formation below the desired level of 1 percent, even if citronellal conversions are restricted to about 50 percent. During studies conducted on a commercially availablemicro-structured organic synthesis plant (OSP) it was shown that it is possible to perform the PMD reaction as a continuous process. The results obtained showed that the use of a micro-mixer such as the caterpillar micro-mixer did not provide enough residence time in order for desirable conversions (- 40 percent) to be obtained. By combining themicro-mixer with delay-loops of different thicknesses and lengths, and using increasing reaction temperatures, it was shown that the conversion of citronellal could be improved to some extent, but compared poorly to the expected conversions for a well-stirred batch reactor. By packing selected delay loops with inert SiC particles, improved mass transfer was observed between the organic and aqueous phases as reflected in the increased conversion of citronellal. Using the observations that were made during the use of the OSP, a continuous-flow, tubular reactor system was designed and constructed. Advanced statistical techniques were used to investigate the effect of variables such as temperature, acid concentration, reactor length, flow rate and the organic to aqueous ratio on the rate and selectivity of the reaction. Mathematical models were derived for citronellal conversion, yield of PMD and yield of PMD- acetals, and used to predict the concentrations of citronellal, PMD and PMD-acetals at set experimental conditions. The results obtained showed that it was possible to obtain a product which approached desired specifications.Downstream processing of the PMD reaction mixture as it exits the reactor requires phase separation and neutralization of the acid catalyst solution, followed by further work-up to recover unreacted starting material and intermediates for recycle back to the synthesis reactor, followed by purification of crude PMD to the desired specification. The study showed that neutralization, prior or after phase separation, does not affect the selectivity of the PMD to such a great extent, but does influence the relative conversion due to extended contact of the catalyst with the organic phase after the reaction is terminated. Recovery of unreacted citronellal and isopulegol could be achieved by a simple vacuum evaporation step, which may either be carried out in a batch manner using traditional distillation equipment, or in a continuous process using wiped-film (short path) techniques. It was also shown that selective crystallization of PMD from the crude product mixture by addition of a solvent, such as heptanes or hexane proved to be the best way of achieving the desired product specification.
3

Seed treatments for insect control, with special reference to their effect upon germination

Kent, Virgil Fletcher January 1930 (has links)
No description available.
4

Arizona Insect Control Recommendations, 1954

Roney, J. N. 02 1900 (has links)
This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.
5

Control of Insects of Flowers, Shrubs and Shade Trees

Roney, J. N. 03 1900 (has links)
This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.
6

Arizona Insect Control Recommendations, 1953

Roney, J. N. 02 1900 (has links)
This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.
7

Household Pests

Roney, J. N. 08 1900 (has links)
This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.
8

Control Insects of Flowers, Shrubs and Shade Trees

Roney, J. N. 02 1900 (has links)
This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.
9

Control Insects of Flowers, Shrubs, and Shade Trees

Roney, J. N. 09 1900 (has links)
This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.
10

Arizona Insect Control Recommendations

Roney, J. N. 07 1900 (has links)
This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

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