Thesis (Ph. D.)--Lehigh University, 2002. / Includes vita. Includes bibliographical references (leaves 240-245).

Streptomyces fradiae is a bacterium which has been previously found to produce extracellular enzymes which are capable of wool degradation and skin depilation. Streptomyces fradiae 3739 and other strains of Streptomyces were found in this study to be able to degrade a keratin source (wool) to a considerable degree. However according to the evidence of SEM micrographs presented here the highly keratinised spindle cells of the paracortex are fairly resistant to protease attack, and it is the cementation material which binds these cells together which is initially degraded by the proteases. A large degree of correlation was found with the strains of Streptomyces studied, between the ability of the individual strains to degrade wool and the ability of their extracellular proteases to reduce the depilation load of sheepskins. With further analysis S. fradiae 3739 was found to produce at least one amylase and four or more proteases. The proteases as a group had maximal proteolytic activity in the 8.0-9.0 pH unit range, and were considerably thermostabilised by the inclusion of calcium ions into the reaction solution. The protease group was found to cause depilation of merino sheepskins. For comparative purposes a protease produced by a strain of Proteus vulgaris isolated from a staling hide with hair slip (natural depilation) was studied. The protease activity was maximal in the alkaline region between 8.0-9.0 pH units. Tbe protease appeared to be a single enzyme with a molecular mass of approximately 44 000 daltons. The protease was maximally active at 40°C, although it was only thermostable to 30°C. The enzyme was ineffectual as a depilant except when the skin was pre-treated with a strong alkali, preferably including sodium sulphite in the protease preparation. One of the most important differences between the extracellular proteases of S. fradiae and P. vulgaris was that the former were greater in variety and caused a greater decrease in the depilation load of sheepskins than the latter. Further research with mixtures of commercial proteases provided evidence that a synergistic depilatory effect occurs when proteases of complementary bond specificities are used in conjunction in enzymic depilatory preparations. Some form of strong alkali treatment of skins was found to be necessary to produce leather of the prerequisite quality when the skin was depilated by proteases, otherwise the skin was found to be depleted and stiff. Calcium hydroxide alone was found to be inadequate for this task, probably owing to the fact that it is less alkaline than the lime-sulphide mixture. The calcium hydroxide (lime) must therefore be used in conjunction with sodium hydroxide (which makes the solution as alkaline as that of the lime-sulphide solution) to produce leather comparable to that produced by the lime sulphide treatment. A combination of the information provided by the present research and that gleaned from the relevent literature allows for the construction of a model to represent the possible mechanism of enzymic depilation of skins, in which depilation is caused by the disruption of the basement membrane at the dermal-epidermal junction by the degradation of its constituent molecular components by general proteases, resulting in the removal of the epidermis and its associated wool or hair

Call number: LD2668 .T4 1963 P43 / Master of Science

Thesis (PH. D)--University of Nebraska. / "Bibliography": p. 16. Also issued in print.

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 218-228). Also available on the World Wide Web.

Thesis (PH. D)--University of Nebraska. / eContent provider-neutral record in process. Description based on print version record. "Bibliography": p. 16.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Thesis (Ph.D.) -- University of Adelaide, Dept. of Animal Physiology, Waite Agricultural Research Institute, 1977.

Thesis (M.Sc.(Metallurgy))--University of the Witwatersrand, Science Faculty, 1990. / A study of phase relations and thermodynamic properties in iron, tin, sulphide system was conducted, [Abbreviated abstract. Open document to view full version] / MT2017

Dissertation submitted in compliance with the requirements for the Master's Degree in Technology: Education at Technikon Natal, 1999. / TOPIC: An investigation of the role of practical laboratory work in bridging programmes forchemical technicians in technikons in South Africa, with particular reference to Mangosuthu Technikon. This research considers the role of introductory practical laboratory work, in a bridging course, in the success or otherwise of vocationally orientated students at technikons in South Africa. Mangosuthu Technikon, on which the study focuses, provides mainlyfor students whose educational background has ill-prepared them for the demands of tertiary studies. Besides the disadvantage of studying through the medium of English, students in the Engineering Schools are further hampered in their studies by having inadequate practical skills for laboratory work. The need to redress the problem of access to tertiary education has resulted in the introduction and continued use of bridging courses for educationally disadvantaged students. Since the secondary education system does not appear to be improving substantially, it would appear that the bridging courses will remain a necessity for some time. InitiallyMangosuthu Technikon offered a school/discipline bridging programme (Pre- Technican Course) for aspirant Engineering students, which allowed disadvantaged applicants a second chance to access tertiary education. It was an intensive six months' course, comprising experiential learning in the integrated components of Mathematics, Communication, Physics and Chemistry. The latter two subjects incorporated a substantial practical component. In the interests of rationalisation, a general Access Course replaced the former course in 1994. The emphasis became largely focussed on theoretical rather than practical work. After initial research indicated that the role of practical laboratorywork inthe trainingof chemicaltechniciansintechnikonsin South Africawas of consequence, a practically orientated bridging course was reintroduced in 1995. This dissertation shows that an educationally disadvantaged student who aspires to becoming a chemical technician requires an holistic education, at the Mangosuthu Technikon bridging course level, which incorporates relevant theoretical and practical components, in order to procure, and succeed in, tertiary education. Such practical work is a prerequisite for aspirant chemical technicians ifthey are to satisfy the needs of tertiary programmes and the demands of their future employers. Findings throughout the dissertation show that practical work is of consequence. Technikon and Industry representatives confirm their commitment to the inclusion of practical work in bridging courses. The implementation and administration of practical bridging courses also play important roles in ensuring that disadvantaged students gain access to tertiary education. This study evaluates Mangosuthu Technikon's original Pre-Technician Course, its 1994 general Access Course and its subsequent Pre-Technician Courses, and finds that Pre-Technician Course (1989/1990) students performed well and that the majority of them were able to access tertiary education and cope with its demands reasonably well. The Access Course (1994) students, by comparison, performed dismally. Years subsequent to 1994 have seen an improvement in the pass rates, but not to the levelofl989/1990. The study, thus, concludes that practically orientated bridging courses impact significantly on successful performance in formal courses for technicians. / M