No description available.

Note:

Cryopreservation is a technique used to store cells and tissues for long time. It requires the addition of a cryoprotectant, which prevents damage to cells caused by the formation of large ice crystals. Few compounds have been classified as cryprotectants, and some of them are very toxic like DMSO. Our lab is interested in the synthesis of small, non-toxic cryoprotectants that possess ice recrystallization inhibition (IRI) activity. Much attention has been drawn towards small molecules that contain an amine group because they have some activity towards inhibiting ice recrystallization. Herein we have examined few monoamine and diamine molecules as well as PAMAM dendrimer for IRI activity. Some of the small molecules tested contain an aryl ring, and we found that changing the position of groups around the ring can have some impact in the IRI activity. We have also found that increasing the number of amines in a molecule can have little effect of the IRI activity. It is hoped that these findings can open new doors for further investigation in small amino molecules and the development of novel cryoprotectants. Corticosteroids were first identified and isolated from both teleost and elasmobranch fish. Corticosterone and cortisol were measurable in the plasma of elasmobranchs and 1α-hydroxycorticosterone (1α-OH-B) was the dominant corticosteroid produced by the internal tissue. Limited amount of 1α-OH-B was synthesized because available supplies were exhausted in the early 1990s. Synthetic 1α-OH-B was used in steroid receptor studies to examine the evolution of the corticosteroid receptor system and measure stress levels.

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

This work describes methods for making dynamic observations of the effects of electron beam heating, in a range of applications to semiconductors. The studies were based on the use of the time resolved reflectivity (TRR) method, in which the reflectivity of the specimens surface is measured during the heating cycle. The best experimental conditions for this technique have been identified and several applications are described in detail. Studies were made of epitaxial regrowth of amorphous layers created by ion implantation into silicon. The TRR method was applied using red and infra-red wavelengths, to characterize the regrowth kinetics, paying special attention to the influence of electrically active dopants. The results demonstrate that doping has a large effect on the regrowth process, for reasons which are related to both electrical and structural factors. The use of isothermal electron beam heating for annealing silicon-on-sapphire (SOS) specimens was investigated. In these studies, the TRR technique was applied to measurement of the temperature of the specimens and to observation of epitaxial recrystallization of amorphous layers created by self-implantation. In SOS films the amorphous layers could be at the surface or buried beneath a thin single crystal layer, and these cases resulted in different regrowth behaviour. TRR methods using green and red probe wavelengths proved to be sensitive to the type of crystallization, as well as the rate at which it occurs. They should also help to identify the best conditions for improvement of the crystal quality of SOS films. TRR was also used to examine heating of silicon-on-insulator materials by swept line electron beams. Temperature distributions were evaluated by measuring the reflectivity of a small area as the electron beam passed through it and the effects of various changes in the heating conditions were explored. Studies were made of zone melting recrystallization by observing the abrupt reflectivity changes which occur when silicon melts or freezes. In future work, TRR techniques could be developed to allow detailed investigation of the recrystallization process in structures intended for seeded recrystallization.

No description available.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

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