Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1984. / Includes bibliographical references (leaves 72-74).

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1984. / Bibliography: leaves 61-63.

Thesis (M.S. - Hydrology and Water Resources Administration)--University of Arizona, 1986. / Bibliography: leaves 149-152.

Thesis (M.S. - Geosciences) - University of Arizona. / Includes bibliographical references (leaves 19-20).

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: John F. Valliant. Includes bibliographical references.

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: John F. Valliant. Includes bibliographical references.

Thesis (M.S. - Hydrologyand Water Resources)--University of Arizona, 1985. / Includes bibliographical references (leaves 98-103).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1965. / Vita. Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Ionic materials in solution do not penetrate the skin following local (topical) application. Such a low permeability can, however, be altered by iontophoresis. Utilization of transmission and scanning electron microscopy and cryostat techniques has made it possible to demonstrate the penetration and site of deposition of ionic tracers in the skin of the rat. It has been found that the penetration of cationic dyes and metal cations is facilitated by positive iontophoresis while the penetration of anionic dyes is facilitated by negative iontophoresis. The extent of penetration is determined by the current density, the concentration of the tracer in the vehicle, the physico-chemical properties of the tracers and the type of vehicle used. The removal of surface lipid is regarded as insignificant in terms of enhancing the penetration of tracers by iontophoresis. It has been found that the penetration of ionic tracers into the skin is preferentially transfollicular. However, the penetration of electron-dense tracers into the stratum corneum of the epidermis and the follicular infundibula is preferentially intercellular, while that into the sebaceous glands is transcellular. It is considered that the whole of the stratum corneum of the epidermis is the major barrier to cutaneous penetration by electrolytes. In addition, a barrier function is suggested for sebum situated in the follicular infundibula.

Isotope tracer techniques are widely used in biological, agricultural, chemical and medical research. The use of stable isotopes is not complicated by health hazards, dangers of radiation or time limit for experiments as is the case for radioactive isotopes. However, the analytical methods available for the determination of stable isotopes are much less sensitive, considerably more complicated and time consuming than those for radioactive isotopes. Such methods usually require the use of a mass spectrometer and most employ the combustion technique (Dumas method) for sample presentation. Speciation can be achieved by an isotope ratio mass spectrometer coupled to a gas chromatograph (GC) and combustion interface. Such instruments are expensive and labour intensive. Additionally, the consumables and catalysts employed are costly.