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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.
371

The functional morphology of the human thoracolumbar transversospinal muscles

Cornwall, Jonathan Edgar, n/a January 2009 (has links)
The thoracolumbar transversospinal muscles are vital in normal function and are implicated in the pathogenesis of different forms of spinal pathology and pain. They are the target for specific forms of clinical intervention such as exercise regimens and the release of �trigger points�, and are often analysed through imaging studies and electromyographic recordings. Despite the importance of these muscles, there is a paucity of knowledge in regard to aspects of their functional morphology. The aim of this thesis was to examine the thoracolumbar transversospinal muscles between the mid-thoracic spine and sacrum, examining their gross morphology, fibre arrangement, fibre types, and an animal model in order to provide a better understanding of their functional morphology. The gross morphology of these muscles was studied by micro-dissection of cadaveric material. Their form was found to differ from that published in either text book or peer reviewed articles, clearly indicating the existence of a �semispinalis� muscle in the lumbar spine. In addition, the arrangement of these muscles was found to be homologous between the thoracic and lumbar regions, which is contrary to published descriptions. Arrangement of the muscle fibres was examined by identifying motor endplates with acetylcholinesterase histochemistry in all muscles throughout the area of interest. Only one endplate per fibre was observed, and no in-series fibres were found. All muscles showed a complex multipinnate form with large areas of muscle tendon intruding into each muscle. Fibre type proportions in each muscle were investigated by immunohistochemistry. Results indicate the percentage of total muscle area occupied by type I fibres decreased the more caudad the vertebral level of origin, for all muscles. There were significant differences in the area percentage of type I fibres between many different vertebral levels. These differences were mostly found between the most cranial and most caudal levels examined. The percentage of type I fibres recorded suggest all muscles are likely postural in function, and the gradual decrease in type I fibres and the lack of a distinct thoracic / lumbar boundary in the data suggests the thoracic and lumbar transversospinal muscles are homologous. The thoracolumbar transversospinal muscles of the MLC3F nlacZ transgenic mouse were micro-dissected to determine their morphology, and their fibre arrangement subsequently determined using acetylcholinesterase histochemistry. These muscles showed a homogeneous form throughout the thoracolumbar spine, and no in-series muscle fibres were observed with all muscles having one motor endplate per fibre. Results indicated similarities between the morphology of mouse and human transversospinal muscles, perhaps indicative of an adaptation to an upright posture. This thesis provides information that facilitates a more complete understanding of the morphology and function of the thoracolumbar transversospinal muscles. In addition, results indicate that these muscles are homologous through the thoracic and lumbar spine, and therefore the classification and nomenclature used to describe these muscles should be re-examined. Furthermore, the morphological evidence, combined with recent embryological studies, supports the use of the term �spinotransverse� to more accurately describe this muscle group.
372

Modification of fly ash colour from grey black to near white and incoporation of fly ash in polypropylene polymer

Zaeni, Akhmad, Materials Science & Engineering, Faculty of Science, UNSW January 2009 (has links)
Particulate filled polymer composites are gaining growing acceptance in the commodity industry because the properties can be adjusted according to the industry's requirements. As particulate filler, fly ash is ready to compete with other particular fillers in polymer composites industries. Although fly ash is a cheap material but the fact that fly ash is grey-black in colour, limits the application of fly ash only to product where colour is not important. As such, a method was needed to be developed to increase the whiteness of fly ash without reducing the advantages of it as a cheap material. In this research, twelve commercially provided fly ash samples from Australian thermal power stations were investigated with respect to composition. Seven of them were thermally modified and further investigated and characterized with respect to colour, size, size distribution, and density. Of these seven fly ashes a particular grade was modified to a whiteness of 93.3 in L*a*b* scale (using barium sulfate as standard), without changing other inherent properties such as particle size and density. By comparison L*a*b* value for Omy carb 20, based on calcium carbonate is 96.9. The whiteness of fly ash was increased using a one stage thermal method ensuring the related cost of production would be not a major hurdle. The next aspect of the thesis involved incorporating as-received and heat treated fly ash samples in isotactic polypropylene up to 80 parts of fly ash per hundred resins (phr), demonstrating that fly ash content in polypropylene composites can be quite high with properly maintained combination of mechanical properties -- in particular up to 200 % improvement in Young's modulus and 63 % gain in notched impact properties, as explained in the thesis. Whilst the Young's modulus properties of the fly ash PP composites match very well with Kerner model, they lie in between the Rule of Mixture series and parallel. The tensile strength properties obtained in this research are at least 25 % higher than those predicted by Nielsen, Landon and Nicolais; whereas the strain to failure values are between 25 - 50 % higher than those predicted by Nielsen, and Smith. Whilst tensile strength of the fly ash filled polypropylene composites were less than the original polypropylene samples, as normally reported in the literature, in this thesis surface modification of fly ash particles by using 10% vinyl triethoxy silane (VTES) coupling agent gave a nominal increase in tensile strength especially at higher fly ash content. The final aspect involved study of oxidation behavior of fly ash filled polypropylene composites. Fillers, including fly ash can shorten the life time of polymers from both chemical as well as physical factors. As-received fly ash contains iron based impurities which may catalyze the anti oxidant in polypropylene, therefore reducing the service life time of the polymer. In this work, thermal treatment studies showed that the iron in fly ash can be changed to a chemically inert material so the effective service life of the polymer will only be influenced by physical factors. Therefore thermal treatment of fly ash not only increases the whiteness but also it reduces the risk of the filler on the life time of the polymer, and hence the composites.
373

Cell disruption mechanics / by Andrew Royce Kleinig.

Kleinig, Andrew Royce January 1997 (has links)
Bibliography: leaves 213-223. / xv, 223 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis examines the cell-fluid interactions that occur during homogenization and combines them with an investigation of the mechanical properties of the cell. This results in a predictive model for cell-disruption efficiency during high-pressure homogenization. The mechanical properties of individual cells are characterised using a micro-manipulation technique. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 1997
374

Hemp fibre and reinforcements of wheat gluten plastics /

Wretfors, Christer, January 2008 (has links) (PDF)
Licentiatavhandling (sammanfattning) Alnarp : Sveriges lantbruksuniversitet. / Härtill 3 uppsatser.
375

Dynamic mechanical behavior and high pressure phase stability of a zirconium-based bulk metallic glass and its composite with tungsten

Martin, Morgana. January 2008 (has links)
Thesis (Ph. D.)--Materials Science and Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Thadhani, Naresh; Committee Member: Doyoyo, Mulalo; Committee Member: Kecskes, Laszlo; Committee Member: Li, Mo; Committee Member: Sanders, Thomas; Committee Member: Zhou, Min.
376

Wood - an anatomical structure in the tree and an engineering material in industry : prediction of material properties in managed Scots pine stands in the forest /

Eriksson, Daniel, January 2008 (has links) (PDF)
Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2008. / Härtill 5 uppsatser.
377

Development of a novel organ culture system allowing independent control of local mechanical variables and its implementation in studying the effects of axial stress on arterial remodeling

Dominguez, Zachary. January 2008 (has links)
Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Vito, Raymond; Committee Member: Gleason, Rudolph; Committee Member: Rachev, Alexander. Part of the SMARTech Electronic Thesis and Dissertation Collection.
378

Analysis of handling stresses and breakage of thin crystalline silicon wafers

Brun, Xavier F.. January 2008 (has links)
Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Melkote, Shreyes; Committee Member: Danyluk, Steven; Committee Member: Griffin, Paul; Committee Member: Johnson, Steven; Committee Member: Kalejs, Juris; Committee Member: Sitaraman, Suresh. Part of the SMARTech Electronic Thesis and Dissertation Collection.
379

Rapid production of polymer microstructures

Nagarajan, Pratapkumar. January 2008 (has links)
Thesis (Ph.D)--Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Dr. Donggang Yao; Committee Member: Dr. John.Muzzy; Committee Member: Dr. Karl Jacob; Committee Member: Dr. Wallace W. Carr; Committee Member: Dr. Youjiang Wang. Part of the SMARTech Electronic Thesis and Dissertation Collection.
380

Mechanical compression of coiled carbon nanotubes

Barber, Jabulani Randall Timothy. January 2009 (has links)
Thesis (M. S.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009. / Committee Chair: Lawrence Bottomley; Committee Member: Aldo Ferri; Committee Member: E. Kent Barefield; Committee Member: Levent Degertekin; Committee Member: Robert Whetten; Committee Member: Satish Kumar; Committee Member: Zhong Lin Wang.

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