161 |
Effect of laser irradiation on enzyme activity and expression of mitochondrial respiratory chain complexesMasha, Roland Tasha 16 October 2012 (has links)
M.Tech. / Low-intensity laser irradiation (LILI), also known as photo-biostimulation, is a type of phototherapy which is based on the application of low power monochromatic and coherent light mostly in the wavelength range of 600 to 1 000 nm to injuries and lesions to stimulate healing. LILI has been shown to increase adenosine triphosphate (ATP) synthesis, cell proliferation (Silveira et al., 2007 and 2009; Hawkins and Abrahamse, 2006a) and collagen synthesis, and release of growth factors from cells (Eells et al., 2004). LILI has not been fully embraced and is mainly due to the fact that the biochemical mechanisms underlying the positive effects are not completely understood (Hamblin and Demidova, 2006). Though the mechanisms of photo-biostimulation on a variety of mitochondrial enzymes have been proposed and studied by different researchers, most of the mechanisms are based on oxygen consumption studies and lack direct experimental support (Chen et al., 2008). This project was designed to study the enzyme activity and expression of the mitochondrial respiratory chain complexes (I to V) post-irradiation with a wavelength of 660 nm and a fluence of 5 or 15 J/cm2 in isolated human skin fibroblast cells. Diabetes mellitus (DM) is a group of diseases marked by high levels of blood glucose resulting from defects in insulin production, insulin action or both. It is found worldwide and is estimated to affect 1.1% of the world population (World Health Organization, WHO, 2002). Estimates from 2009 by the International Diabetes Federation suggest that the number of adults with diabetes in the world will expand by 54%, from 284.6 million in 2010 to 438.4 million in 2030. The projected growth for sub-Saharan Africa is 98%, from 12.1 million in 2010 to 23.9 million in 2030 (Mbanya et al., 2010). Though DM is more common in industrialized countries, the trend is changing.
|
162 |
Collagen production in wounded fibroblasts in response to low intensity laser irradiationAyuk, Sandra Matabi 15 April 2014 (has links)
M.Tech. (Biomedical Technology) / Collagen Type I (Col- I) as well as collagen types III and V, form most of the connective tissues, smooth muscle cells and, endothelial cells in wound healing (Stuart and Leaper, 2008). Col-I is also the main extracellular matrix (ECM) protein (Ricard-Blum and Ruggiero, 2005). Low intensity laser irradiation (LILI) is a non-invasive, photobiomodulatory therapy. Huang et al., (2009a) have shown LILI to be involved in Col-I production both in vitro and in vivo. Enhanced collagen production in human skin fibroblasts is common shortly after irradiation (Illsley et al., 2000). However, its synthesis in wounded fibroblasts has not been well established in an in vitro model. Healing is impaired in chronic diabetic wounds which exhibit reduced proliferation rate and collagen synthesis (Beldon, 2010; Falanga, 2005). Studies have shown that LILI using a wavelength of 632.8 nm was not the only wavelength biostimulated in cultured cells: biological responses were also generated from various wavelengths within the visible to Near Infrared (NIR) spectral region (Hawkins and Abrahamse, 2005; Karu and Kolyakov, 2005). This study aimed to establish if LILI influenced collagen production and related cellular responses at a wavelength of 660 or 830 nm, with a fluence of 5 J/cm2 in an in vitro normal and wounded fibroblasts model. The study also evaluated the expression profiling of genes related to the ECM and adhesion. This study was performed on isolated human skin fibroblasts collected from a consenting adult undergoing abdominoplasty. Cells were routinely cultured according to standard techniques (Houreld and Abrahamse, 2010; Hawkins and Abrahamse, 2007a; Hawkins and Abrahamse, 2006a; Hawkins and Abrahamse, 2005).
|
163 |
Nanostructures of Zr-based bulk metallic glasses : induced by ball milling and high-current pulsed electron beams / Nanostructures d'alliages métalliques amorphes Zr-Al-Ni-Cu induites par broyage mécanique et faisceaux d'électrons pulsés à haut courantWu, Jiang 09 July 2010 (has links)
Contrairement aux métaux conventionnels, les verres métalliques amorphes présentent des arrangements atomiques à courte distante. Ce résultat conduit à des propriétés physiques et chimiques fondamentalement différentes de leurs homologues cristallins. Cette étude porte sur la caractérisation et la compréhension de la nanocristallisation de verres métalliques amorphes massifs (BMG) Zr-Al-Ni-Cu induite par traitement thermique, broyage mécanique et faisceaux d’électrons pulsés à fort courant (HCPEB). Deux alliages amorphes massifs ont été cristallisés par broyage mécanique et HCPEB : le classique Zr65Al7.5Ni10Cu17.5 et un nouvel alliage Zr58Al16Ni11Cu15 développé en utilisant un modèle basé sur l’association de clusters. Les échantillons initiaux et traités ont été caractérisés en combinant les microscopies électroniques en transmission (MET) et à balayage (MEB), la diffraction d’électrons rétrodiffusés (EBSD), l’analyse thermique différentielle (ATD) et la spectroscopie Raman afin d’analyser finement les évolutions microstructurales. Les nanocristallisations induites par broyage et HCPEB sont très différentes de celles obtenues par traitements thermiques. Ces travaux de recherche permettent une avancée dans la compréhension des mécanismes de cristallisations mécanique et sous irradiation. Les résultats peuvent être utilisés pour réaliser des structures composites de BMGs avec l’objectif final d’améliorer leur ductilité / Unlike conventional metals, the atomic arrangements in metallic glasses have only short-range order. This results in many physical and chemical properties that are fundamentally different from those of their crystalline counterparts. This study is devoted to charactering and understanding nanostructures and nanocrystallization of Zr-Al-Ni-Cu bulk metallic glasses induced by thermal annealing, ball milling, and high-current pulsed electron beam (HCPEB) treatment. Two Zr-Al-Ni-Cu BMGs were used: the classic Zr65Al7.5Ni10Cu17.5 alloy and a new Zr58Al16Ni11Cu15 alloy developed by using a cluster-based approach. The initial and treated samples were characterized by the combination of transmission electron microscopy (TEM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD), differential thermal analysis (DTA) and Raman spectroscopy in order to analyze accurately the microstructure evolution encountered in the materials. The nanocrystallization behaviour under ball mill and HCPEB is significantly different from the one observed via thermal annealing. The significance of this research is the advancement of the fundamental understanding of mechanical and the electron beam irradiation-induced crystallizations. This research may be used for the design of BMG-related composite structures with the ultimate goal of improving their ductility
|
164 |
Effect of swift heavy ion irradiation and annealing on the microstructure and migration behaviour of implanted Sr and Ag in SiCAbdelbagi, Hesham Abdelbagi Ali 15 December 2019 (has links)
The effect of ion irradiation and annealing on the microstructure and migration behaviour of implanted Sr and Ag in SiC have been investigated. SiC is used as the main barrier for fission products in modern high temperature gas cooled reactors. An understanding of the transport behaviour of the implanted ions under irradiation by swift heavy ions (SHI) will shed some light into SiC’s effectiveness in the retention of fission products. The diffusion behaviour of silver (Ag) and strontium (Sr) implanted separately into SiC was investigated after irradiation by xenon ions and isochronal annealing methods from 1100 ˚C up to
temperatures of 1500 ˚C in step of 100 ˚C for 5 hours. Ion implantation and ion irradiation were performed at room temperature. The implantation fluences in all cases were in the order of 2×10 16 ions per cm 2 . Some of the implanted samples were then irradiated by SHI at different fluences (i.e. 3.4×10 14 and 8.4×10 14 ions per cm 2 ). The implantation depth profiles before and after irradiation and annealing were determined by Rutherford backscattering spectroscopy (RBS). The microstructure of SiC individually implanted with Ag and Sr were investigated using Raman spectroscopy and scanning electron microscopy (SEM). Implantation of Ag and Sr amorphized the SiC, while SHIs irradiation of the as-implanted SiC resulted in limited recrystallization of the initially amorphized SiC. Annealing at 1100 °C caused more recrystallization on the un-irradiated but implanted samples compared to SHI irradiated samples. This poor recrystallization of the irradiated SiC samples was due to the amount of impurities (i.e. concentration of Ag or Sr atoms) retained after annealing at 1100 o C. Raman and SEM results showed that annealing of the un-irradiated but implanted samples at 1100 °C resulted in large average crystal size compared to the irradiated samples annealed in the same conditions. RBS results showed that SHI irradiation alone induced no change in the implanted Ag and Sr. However, annealing the SHI irradiated samples iscohonally up to 1500 ˚C showed a strong diffusion and release of Ag and Sr as compared to the un-irradiated but implanted samples. The differences in the migration behavior of Ag and Sr is due to the difference in SiC structure and recrystallization in the irradiated and un-irradiated but implanted samples. / Thesis (PhD (Physics))--University of Pretoria, 2019. / National Research Foundation (NRF) and The World Academy of Sciences (TWAS). / Physics / PhD (Physics) / Unrestricted
|
165 |
Design of central irradiation facilities for the MITR-II research reactor.Meagher, Paul Christopher January 1977 (has links)
Thesis. 1977. M.S.--Massachusetts Institute of Technology. Dept. of Nuclear Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / M.S.
|
166 |
Establishment of a radiation-induced vocal fold fibrosis mouse model / 放射線照射による声帯線維化マウスモデルの確立Tanigami, Yuki 23 March 2023 (has links)
京都大学 / 新制・課程博士 / 博士(医学) / 甲第24504号 / 医博第4946号 / 新制||医||1064(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 溝脇 尚志, 教授 浅野 雅秀, 教授 鈴木 実 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
|
167 |
The Effects of Irradiation on Inconel X-750Judge, Colin David 11 1900 (has links)
Inconel X-750 is a Ni-rich super-alloy with high strength and creep resistance. In CANDU reactors, it is used as tight fitting fuel channel annulus spacers (in the form of a spring). Unlike other reactor designs, the CANDU reactor has a high thermal neutron flux spectra, which, combined with the higher thermal neutron cross section of 58Ni results in an enhancement of the radiation damage and the internal production of helium and hydrogen. In recent years, it has been observed these spacers are losing ductility and strength following irradiation. The mechanical property evolution of these components is dependent on the irradiation temperature and dose. The primary degradation mechanism remains unclear, and thus provides the focus of this investigation. Inconel X-750 irradiated to these extreme conditions have never been examined prior to this research. The microstructural characterization included in this dissertation include: fractography, microstructural evolution and mechanical property evolution. The discussion of the microstructural evolution is focused on the characterization of helium bubbles. The bubbles form homogeneously in the matrix and aligned along sinks such as dislocations, grain boundaries and precipitates. Electron energy loss spectroscopy (EELS) has been used to probe individual nano-sized bubbles to provide insights into the helium density, helium-to-vacancy ratio, and pressures through the use of a hard sphere equation of state (HSEOS). In addition to understanding the influence of irradiation on helium bubbles, the evolution of secondary strengthening precipitates, gamma prime, are of interest as these precipitates play an important role on the strength and creep resistance of the unirradiated material. The stability of these precipitates with irradiation is thus an important factor to consider with respect to the microstructural degradation. The microstructure is linked to the mechanical properties via microhardness testing on adjacent material. A major contribution to this field is an approach to utilize a focused ion beam (FIB) and transmission electron microscopy (TEM) to perform high
ii
resolution failure analysis of an intergranular fracture surface. Although this technique is not altogether revolutionary, the application of this approach towards post irradiation examination of heavily irradiated Inconel X-750 is unique. This approach provides direct evidence of likely degradation mechanisms, and provides insights for future post irradiation failure analysis for other applicable nuclear components. Working with ex-service material creates some complications with respect to known and unknown variables making it difficult to assess all factors responsible for material degradation. To compliment the program, a controlled proton irradiation program has been performed to gain additional insights into in the effects of irradiation on the microstructure and mechanical property evolution of Inconel X-750, due to the inability to perform controlled experiments with in-service reactor components. In addition to providing a detailed analysis of a CANDU component’s degradation, this study provides comprehensive information on irradiation damage processes applicable to other reactor core components. / Thesis / Doctor of Philosophy (PhD)
|
168 |
Proton irradiation damage in zinc and cadmium doped indium phosphideRybicki, George Charles January 1993 (has links)
No description available.
|
169 |
A Study of the Effects of Neutron Irradiation and Low Temperature Annealing on the Electrical Properties of 4H Silicon CarbideStone, Stephen E. 15 October 2008 (has links)
No description available.
|
170 |
MODELING AND CONTROL OF PHOTOVOLTAIC GENERATING STATIONChatterjee, Abir 25 June 2012 (has links)
No description available.
|
Page generated in 0.1306 seconds