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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.

A study of two component systems, sulfur dioxide and caprylene

Hodnett, Lisle January 1934 (has links)
[No abstract available] / Science, Faculty of / Chemistry, Department of / Graduate

Use of heavy oil residua in coal liquefaction studies by solvent augmentation of iron based catalysts

Badger, Mark William January 1996 (has links)
No description available.

Hardness and penetration of gutta percha when exposed to two endodontic solvents

Patel, Ebrahim 21 April 2015 (has links)
A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science in Dentistry. School of Oral Health Sciences, Faculty of Health Sciences, University of the Witwatersrand, South Africa Johannesburg, 2014 / Purpose: Endodontic retreatment requires the removal of the obturation material from the root canal system. Gutta percha (GP), the most commonly employed obturation material, requires mechanical instrumentation coupled with a chemical adjunct to facilitate its removal. Xylene and Eucalyptus oil are recommended as endodontic solvents due to their dissolving capacity of GP. This study sought to test the changes in the hardness and penetrability of three types of GP (Conventional, Thermafil® and Guttacore™) when exposed to these solvents, utilizing distilled water as a control. Method and materials: Textural analysis was performed to determine the hardness by testing for rigidity, and the penetrability by testing for deformation energy and resilience. These properties were tested on 81 GP cones prior to, and following solvent exposure. For each outcome variable, results were tabulated by group. Between-group differences were assessed by means of a General Linear Model, with the outcome variable as the dependent variable and the solvent, GP type and solvent-GP type interaction as the independent variables. Results: A significant decrease in rigidity and deformation energy was observed across all groups. Resilience was observed to decrease with the thermoplastic GP, Thermafil and Guttacore, but increased with conventional GP. Thermoplastic GP was more amenable to a reduction in hardness and penetration when compared with Conventional GP. A greater reduction in the hardness of Thermafil was observed with Eucalyptus oil. Conventional GP was susceptible to a significant reduction in hardness with both solvents, however its penetrability may be reduced following exposure to Xylene. Guttacore was significantly altered by both solvents. Conclusions: Considering the toxicity profile of Xylene, and the biocompatibility and antimicrobial effects of Eucalyptol, Eucalyptus oil is recommended for use during endodontic retreatment.

The use of a supercritical carbon dioxide-based solvent as a cost effective and environmentally sound alternative to current photoresist stripping solvents

Knutson, Brian. January 2002 (has links) (PDF)
Thesis--PlanB (M.S.)--University of Wisconsin--Stout, 2002. / Includes bibliographical references.

Effect of solvents during material treatment applications tuning hydrophilicity of silicone rubber and drug loading in mesoporous silica /

Hillerström, Anna, January 2009 (has links)
Diss. (sammanfattning) Karlstad : Karlstads universitet, 2009. / Härtill 4 uppsatser.

Investigation of the mechanism of formation of overbased detergents

Courtois, Jean-Philippe January 2002 (has links)
This thesis describes an experimental study of calixarate overbased detergent oil additives, used to neutralise acidic by-products of engine combustion. Aspects of interest in this study include experimental synthesis of calixarenes and overbased detergents, physical and structural characterisation and monitoring of the synthesis process. Two types of calixarenes were prepared (6 and 8 phenolic units). A synthesis procedure of the calixarate overbased detergent was set up, basedono adaptation of existing procedures used for other classes of overbased detergents. The procedure was also modified to suit a lab-scale. 13C NMR and UV-Vis spectroscopy have provided strong evidence for a precursor of the overbased detergent. The ionisation of the surfactants (stearic acid carboxylic group, and phenolic units) was clearly established. The synthesis process was monitored at the molecular and macroscopice level. The use of 13C -labelled compounds enabled a semi-quantitative study of the concentration evolution of each chemical during the synthesis. Langmuir-t rough measurements and dynamic light scattering showed a decrease of particle size during the synthesis of the overbased detergent. The final calixarate overbased detergent was then fully characterised by these two methods. Based on the various information gathered (starting and final material characterisation, monitoring of the process),a mechanism was suggested. This involved a progressive solvation of calcium hydroxide, and breakdown of mixed calcium hydroxide and calcium carbonate.

Studies of racemization rates in solvents of intermediate dielectric constant

Morgan, Lyman Wallace 08 1900 (has links)
No description available.

Adsorption of hydroquinone by calcite and aragonite form organic solvents ...

Leaf, Clyde William, January 1941 (has links)
Thesis (Ph. D.)--Columbia University, 1941. / Vita. Bibliography: p. [30]. Also issued in print.

Hydrotropic solutions as solvents of lignin ...

Pelipetz, Michail Gregory, January 1937 (has links)
Thesis (Ph. D.)--Columbia University, 1937. / Vita. Diagrams 2 and 3 on leaf mounted over diagrams 2 and 3 on p. 13. "LIterature cited": p. 36.

Optimizing solvent selection for separation and reaction

Lazzaroni, Michael John. January 2004 (has links) (PDF)
Thesis (Ph. D.)--School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2005. Directed by Charles A. Eckert. / Charles L. Liotta, Committee Co-Chair ; Charles A. Eckert, Committee Chair ; Amyn S. Teja, Committee Member ; J. Carson Meredith, Committee Member ; Rigoberto Hernandez, Committee Member. Vita. Includes bibliographical references.

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