In live acid solutions at concentrations of HCl namely 15-20 wt% HCl, elastic modulus remained quite low as compared to 10-12 wt% HCl concentrations. At 10 wt% HCl concentration, elastic modulus was 3.4 Pa observed whereas at 20 wt% HCl concentration, elastic modulus was 0.03 Pa. 0.5- 1.0 wt% concentrations of NaCl and CaCl2 showed negligible effect on the elastic modulus while 3-10 wt % concentrations, substantially reduced the elastic modulus. As little as 0.5 wt% Fe (III) concentration reduced elastic modulus quite significantly. In live acids, increase in temperature resulted in viscous modulus dominating the elastic modulus. Corrosion inhibitor reduced values of elastic modulus significantly, at 10 wt% HCl concentration elastic modulus dropped from 5.1 Pa to 3.4 Pa. Preparation of acid solution with sea water showed negligible effect at higher concentrations of HCl (> 10 wt% HCl) whereas at lower concentrations of HCl the elastic modulus fell sharply. For spent acid solutions, the elastic modulus at room temperature was quite low. Increase in temperature resulted in the increase in elastic modulus up to 130 F after which it decreased. At 190 - 205F and 18.8 rad/s, elastic modulus for 12 wt% HCl concentrations was 0.4 Pa whereas at 130 F, it was 2.25 Pa. At high temperatures (>130 F), the maximum elastic modulus shifted to higher concentrations of HCl namely 20 wt% HCl concentration. At 160 F, elastic modulus of 20 wt% HCl concentration at 18.8 rad/s was observed to be 2.6 Pa, whereas for 12 wt% HCl concentrations, it was 1.27 Pa. Throughout the HCl concentration and temperature range tested, viscous modulus dominated the elastic modulus for spent acid solutions. The effects of organic acids namely, formic and acetic acid, on the elastic modulus of viscoelastic surfactants have also been investigated.

Advances in the field of medicine have extended the average human life expectancy worldwide. As a result an increasing number of people will suffer from problems associated with their mineralized tissues and will require orthopedic and dental implants to restore their quality of life. Ideally, implants should have mechanical and structural properties compatible with the original mineralized tissue, and should also promote faster and stronger implant fixation. An improved understanding of the properties of mineralized tissues can help with the improvements of implants. This thesis focuses on improving the understanding of two aspects related to mineralized tissues and implant systems: the mechanical properties of peri-implant bone, and the mechanical, composition and structural properties of dentin and jawbone. Studies have shown that local delivery of alendronate, an anti-osteoporosis drug, enhances new bone formation; however, the effects of the drug on the elastic modulus of new formed bone are unknown. In this study, nanoindentation was used to evaluate and compare the elastic modulus of peri-implant bone with and without the presence of alendronate. To better understand the properties of dentin and jawbone, nanoindentation and qualitative backscattered electron imaging were used to measure their elastic modulus, mineral content and volume fraction, and regression analyses were used to establish correlation between the properties. In this thesis, mineralized tissue samples were collected from an animal study. To study the effects of alendronate on the elastic modulus of peri-implant bone, porous tantalum implants with three different coating treatments were used: non-coated (Ta), calcium phosphate coated (Ta-CaP), alendronate-immobilized-calcium-phosphate coated (Ta-CaP-ALN). The calcium phosphate coatings, with or without alendronate, increased the elastic modulus of peri-implant Ingrown Bone by approximately 22% (3GPa). The addition of alendronate did not significantly increase the elastic modulus of peri-implant. For the study of dentin and jawbone, regression analyses showed that the elastic modulus of dentin is strongly dependent on the porosity and to a lesser extent on the calcium content. The elastic modulus of jawbone and dentin were compared and the elasticmodulus of jawbone was generally higher than that of dentin while the mineral content was lower.

Advances in the field of medicine have extended the average human life expectancy worldwide. As a result an increasing number of people will suffer from problems associated with their mineralized tissues and will require orthopedic and dental implants to restore their quality of life. Ideally, implants should have mechanical and structural properties compatible with the original mineralized tissue, and should also promote faster and stronger implant fixation. An improved understanding of the properties of mineralized tissues can help with the improvements of implants. This thesis focuses on improving the understanding of two aspects related to mineralized tissues and implant systems: the mechanical properties of peri-implant bone, and the mechanical, composition and structural properties of dentin and jawbone. Studies have shown that local delivery of alendronate, an anti-osteoporosis drug, enhances new bone formation; however, the effects of the drug on the elastic modulus of new formed bone are unknown. In this study, nanoindentation was used to evaluate and compare the elastic modulus of peri-implant bone with and without the presence of alendronate. To better understand the properties of dentin and jawbone, nanoindentation and qualitative backscattered electron imaging were used to measure their elastic modulus, mineral content and volume fraction, and regression analyses were used to establish correlation between the properties. In this thesis, mineralized tissue samples were collected from an animal study. To study the effects of alendronate on the elastic modulus of peri-implant bone, porous tantalum implants with three different coating treatments were used: non-coated (Ta), calcium phosphate coated (Ta-CaP), alendronate-immobilized-calcium-phosphate coated (Ta-CaP-ALN). The calcium phosphate coatings, with or without alendronate, increased the elastic modulus of peri-implant Ingrown Bone by approximately 22% (3GPa). The addition of alendronate did not significantly increase the elastic modulus of peri-implant. For the study of dentin and jawbone, regression analyses showed that the elastic modulus of dentin is strongly dependent on the porosity and to a lesser extent on the calcium content. The elastic modulus of jawbone and dentin were compared and the elasticmodulus of jawbone was generally higher than that of dentin while the mineral content was lower.

Advances in the field of medicine have extended the average human life expectancy worldwide. As a result an increasing number of people will suffer from problems associated with their mineralized tissues and will require orthopedic and dental implants to restore their quality of life. Ideally, implants should have mechanical and structural properties compatible with the original mineralized tissue, and should also promote faster and stronger implant fixation. An improved understanding of the properties of mineralized tissues can help with the improvements of implants. This thesis focuses on improving the understanding of two aspects related to mineralized tissues and implant systems: the mechanical properties of peri-implant bone, and the mechanical, composition and structural properties of dentin and jawbone. Studies have shown that local delivery of alendronate, an anti-osteoporosis drug, enhances new bone formation; however, the effects of the drug on the elastic modulus of new formed bone are unknown. In this study, nanoindentation was used to evaluate and compare the elastic modulus of peri-implant bone with and without the presence of alendronate. To better understand the properties of dentin and jawbone, nanoindentation and qualitative backscattered electron imaging were used to measure their elastic modulus, mineral content and volume fraction, and regression analyses were used to establish correlation between the properties. In this thesis, mineralized tissue samples were collected from an animal study. To study the effects of alendronate on the elastic modulus of peri-implant bone, porous tantalum implants with three different coating treatments were used: non-coated (Ta), calcium phosphate coated (Ta-CaP), alendronate-immobilized-calcium-phosphate coated (Ta-CaP-ALN). The calcium phosphate coatings, with or without alendronate, increased the elastic modulus of peri-implant Ingrown Bone by approximately 22% (3GPa). The addition of alendronate did not significantly increase the elastic modulus of peri-implant. For the study of dentin and jawbone, regression analyses showed that the elastic modulus of dentin is strongly dependent on the porosity and to a lesser extent on the calcium content. The elastic modulus of jawbone and dentin were compared and the elasticmodulus of jawbone was generally higher than that of dentin while the mineral content was lower. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

No description available.

Organic solar cells promise a cheap and easy alternative to silicon photovoltaics, but there are many problems that must be solved before they can be a stable and efficient substitute. One such problem is the degradation of solar cells under exposure to light and oxygen. In response to evidence of change in electronic properties of polymer:PCBM solar cells, the mechanical properties of pristine PCBM films are investigated for analogous development using atomic force microscopy. Although no signicant change in the elastic modulus is detected, differences in material response indicate a skin effect which is beyond measurement sensitivity. Presence of a hard skin is verified in tapping phase imaging and spectroscopy.

In this work, we used atomic force spectroscopy to obtain the elastic modulus of melanoma and keratinocytes fixed cells, with the purpose to determine the initial conditions for studies of confluente cultures of these cells in the future. The cell lines used were HaCaT cells and WM1366 melanoma cell, the last one is derived from a radial growth melanoma and both were analyzed, parental WM1366 cells (WM1366 shSCR cells) and galectin-3 silenced WM1366 cells (WM1366 shGal3). Cells were located and images of them were obtained by AFM contact mode under liquid conditions. Single force curves acquired in the central region of cells were used to determine the elastic modulus by the Hertzian contact model for the pyramidal tip, allowing to establish a comparison patter between cancer and normal cells. It was found that the melanoma cell (21.8 ± 0.5 kPa) exhibit smaller elastic modulus than keratinocytes cells (31.9 ± 0.4 kPa). For WM1366 shGal3 was found a elastic modulus of 16.1 ± 0.6 kPa, therefore, we found that for large indentation depth it is possible to distinguish between the same melanoma cell line, which represents general alterations in the organization of the cytoskeleton induced by the presence or absence of the galectin-3 protein. On the other hand, to detect local elastic modulus variations along the cell and to identify subcellular regions characterized by specific stiffness associated with local structures, we took elasticity maps in which a single force curve is acquired in each probe position. In order to interpret these maps, the cell was sliced into several different heights, curves of each height section were analyzed and represented in histograms, adjusted by the binomial distribution function. It was observed that the gradient of elastic modulus in cells from the nuclear region towards the cell periphery is more pronounced in cells devoid of galectin-3 than parental cells. The increased elastic modulus in the pericellular region of cells devoid of galectin-3 suggests that the organization of the extracellular matrix in these areas is different than those observed around HaCaT and shSCR WM1366 cells. / Neste trabalho, utilizamos espectroscopia de força atômica para obtenção do módulo elástico de células fixadas de melanoma e queratinócitos, com o objetivo de determinar as condições iniciais de estudos a serem realizados futuramente de culturas de células confluentes do mesmo tipo. As linhagem celulares utilizadas foram as células HaCaT e as células de melanoma WM1366, sendo a última derivada de um melanoma de crescimento radial sendo analisadas tanto as células parentais (células WM1366 shSCR) e as células WM1366 silenciadas com galectina-3 (WM1366 shGal3). As células foram localizadas e imageadas no modo AFM contato em meio líquido. Curvas de força adquiridas na região central das células foram utilizadas para determinar o módulo elástico, a partir do modelo de contato hertziano por uma ponta piramidal, permitindo estabelecer um padrão para comparação entre células normais e cancerígenas. Verificou-se que a célula de melanoma exibe menor módulo de elasticidade (21.8 ± 0.5 kPa) do que as células de queratinócitos (31.9 ± 0.4 kPa). Para as células WM1366 shGal3 foi encontrado um módulo elástico de 16.1 ± 0.6 kPa. Portanto, verificou-se que, para grandes profundidades de indentação, é possível distinguir entre a mesma linhagem de melanoma, células que apresentam alterações gerais na organização do citoesqueleto induzidas pela presença ou ausência da proteína galectina-3. Por outro lado, para detectar variações locais do módulo elástico ao longo da célula e identificar regiões subcelulares, caracterizadas por rigidez específica associada a estruturas locais, foram obtidos mapas de elasticidade nos quais uma única curva de força é adquirida em cada posição da sonda. Para interpretar estes mapas, a célula foi dividida em regiões de diferentes alturas e curvas de cada seção de altura foram analisadas e representadas em histogramas, ajustadas pela função de distribuição binomial. Observou-se que o gradiente de módulo de elasticidade em células da região nuclear em direção à periferia celular é mais acentuado em células desprovidas de galectina-3 do que em células parentais. O aumento do módulo de elasticidade na região pericelular das células desprovidas de galectina-3 sugere que a organização da matriz extracelular nestas áreas é diferente das observadas em torno das células HaCaT e shSCR WM1366.

Introduction: The purpose of this study was to determine the effect of spinal manipulation therapy (SMT) duration and amplitude on spinal stiffness. Methods: Simulated SMTs were performed at the L6 spinous process in twenty-two felines. SMTs ranging from 25 to 250 ms duration were performed. Groups 1 and 2 received maximal displacements of 1.0mm to 3.0mm. Groups 3 and 4 received maximal loads of 25% to 85% body weight. Local stiffness was quantified by applying an indentation to the vertebra. Results: Repeated SMTs caused minimal changes in stiffness. The interaction effect of duration X displacement in Groups 1 and 2, and the effect of duration in Group 3 were significant. Conclusion: Repeated SMTs cause minimal changes in stiffness thought to be due to a viscoelastic response. Some of the changes following select SMT conditions may be the result of an interaction effect between SMT duration and amplitude. No specific threshold condition was identified as causing a greater stiffness change. / Physical Therapy

The effect of local defect on thin film mechanical properties is studied in this thesis. The molecular dynamics (MD) is employed to simulate and analyze the relation between intermolecular strength and deformation in the nanoindentation test. The variation of hardness and elastic modulus are simulated from the load-displacement response and the projected area of contact at the maximum load. In this study, Tersoff potential function is employed to describe the molecular behavior of nano-scale carbon and silicon films. The MD models of the diamond indenter and film are applied in the simulation. Due to the hardness different, the diamond indenter can be assumed rigid when silicon thin film was test. However, the indenter¡¦s wear and compressive effects can not be ignored when diamond film were studied under nanoindentation simulation. The indentation parameter in the simulation includes substrate size, indentation velocity, peak hold time, system temperature, indentation depth, local void size, void position and vacancy rate. The results show that the hardness and elastic modulus of thin film may decrease significantly with considering the existence of local defect. The results also elucidated that the elastic modulus and hardness for perfect lattice structure thin films should be the upper bond value of the real bulk material.

No description available.