Recently a new x-ray absorption spectroscopy (XAS) called inverse partial fluorescence yield (IPFY) has been developed that is bulk sensitive and free of saturation effects, which also provides a direct measure of total absorption coefficient. However, IPFY was originally formulated for smooth bulk samples, but XAS is often performed on rough samples. To test the applicability of IPFY on rough surfaces, a model is presented and the calculations based on this model are compared to the experimental results measured on NdGaO3. It is shown that the correspondence between calculated and experimental intensities of IPFY is sufficient to corroborate this model a means of estimating the maximum allowable surface roughness size and the optimal detection geometry.

Physical stress such as the surface roughness of the implants may activate the NFkB signalling pathway in macrophages. This activation is intimately related to the mechanism(s) by which the macrophage interacts with the surface through serum proteins and/or the formation of membrane rafts. This thesis examines the role of surface topography on activation of the NFkB signalling pathway in macrophages. We examined the effect of implant surface topography on activating the NFkB signalling pathway in the RAW 264.7 macrophage cell line. We also examined the effect surface roughness had on the adhesion of the macrophages using the different media. To finish, we observed the effect the different media and the surface roughness had on the morphology of the macrophages by Scanning Electron Microscopy. Activation of the NFkB pathway was surface topography dependent. The Smooth surface showed the highest level of activation followed by the Etched then the SLA. Addition of suboptimal concentrations of LPS mildly enhanced the response by signalling through the Toll receptor. Activation of NFKB occurred in the absence of fetal calf sera, although to a lesser extent. All three surfaces had very few cells with nuclear translocation at the 5 minutes time point with no significant statistical differences between the surfaces. After 30 minutes, translocation reached comparable levels to those surfaces tested with complete medium. Disruption of the lipid rafts affected the triggering and signalling of the NFkB pathway. This inhibitory effect was concentration and time dependent. Smooth surfaces bound more macrophages in the 30 minutes assay. Fetal calf serum appeared to be very critical for adhesion and spreading of the macrophages on the various surfaces examined. Removal of cholesterol did not affect adhesion or spreading on their respective surfaces. We have clearly demonstrated that the lipid rafts along with surface topography play a role in the activation on NFKB. This in-vitro study has demonstrated that surface topography modulated activation of the NFKB signalling pathway in a time-dependent manner. However, at present, it is unclear through which receptor(s) / surface structure the signal pathway is initiated.

Thesis (M.S.) in Mechanical Engineering--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 106-111).

Thesis (Ph. D.)--University of Rhode Island, 2003. / Typescript. Includes bibliographical references (leaves 108-111).

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 141-153).

Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2006. / Zhang, Zhuomin, Committee Chair ; Joshi, Yogendra, Committee Member ; Lee, Kok-Meng, Committee Member ; Gallivan, Martha, Committee Member ; Zhao, Yiping, Committee Member.

No description available.

Physical stress such as the surface roughness of the implants may activate the NFkB signalling pathway in macrophages. This activation is intimately related to the mechanism(s) by which the macrophage interacts with the surface through serum proteins and/or the formation of membrane rafts. This thesis examines the role of surface topography on activation of the NFkB signalling pathway in macrophages. We examined the effect of implant surface topography on activating the NFkB signalling pathway in the RAW 264.7 macrophage cell line. We also examined the effect surface roughness had on the adhesion of the macrophages using the different media. To finish, we observed the effect the different media and the surface roughness had on the morphology of the macrophages by Scanning Electron Microscopy. Activation of the NFkB pathway was surface topography dependent. The Smooth surface showed the highest level of activation followed by the Etched then the SLA. Addition of suboptimal concentrations of LPS mildly enhanced the response by signalling through the Toll receptor. Activation of NFKB occurred in the absence of fetal calf sera, although to a lesser extent. All three surfaces had very few cells with nuclear translocation at the 5 minutes time point with no significant statistical differences between the surfaces. After 30 minutes, translocation reached comparable levels to those surfaces tested with complete medium. Disruption of the lipid rafts affected the triggering and signalling of the NFkB pathway. This inhibitory effect was concentration and time dependent. Smooth surfaces bound more macrophages in the 30 minutes assay. Fetal calf serum appeared to be very critical for adhesion and spreading of the macrophages on the various surfaces examined. Removal of cholesterol did not affect adhesion or spreading on their respective surfaces. We have clearly demonstrated that the lipid rafts along with surface topography play a role in the activation on NFKB. This in-vitro study has demonstrated that surface topography modulated activation of the NFKB signalling pathway in a time-dependent manner. However, at present, it is unclear through which receptor(s) / surface structure the signal pathway is initiated. / Dentistry, Faculty of / Graduate

No description available.

In the evaluation of a slope for stability, it is important to determine useable values of various rack properties. One of the most important rock properties which must be determined is the internal angle of friction, Φ. Surface roughness can have a considerable effect upon the friction angle. The norm has been to adjust the friction angle for roughness by the average asperity angle, i, or to compensate by use of a Joint Roughness Coefficient. The objective of this investigation was to develop a method of mathematically quantifying rock discontinuity surface roughness without the need for a subjective determination based upon a visual comparison with some standard. This mathematical relationship then can be used in the evaluation process of the stability of a slope based upon the limit equilibrium concept. This investigation utilized the concept of fractal dimension to quantify the surface roughness along discontinuities in four rock types. It resulted in the development of a relationship between Joint Roughness Coefficient (JRC) and fractal dimension (D) for each of the four rock types of the form:(UNFORMATTED TABLE/EQUATION FOLLOWS): JRC(Pah) = -1002.11 + (1003.83)D, where: D(Pah) averages 1.00837. JRC(Dwd) = -995.58 + (996.92)D, where: D(Dwd) averages 1.00660. JRC(Min) = -925.47 + (927.90)D, where: D(Min) averages 1.00750. JRC(Met) = -1126.41 + (1127.84)D, where: D(Met) averages 1.00336.(TABLE/EQUATION ENDS)These equations for the relationship between JRC and D can be approximated by: JRC = 1000(D - 1). It was possible to substitute this approximate relationship into Barton's equation for shear strength of discontinuities. This resulted in a useable equation for peak joint shear strength which does not require a subjective determination of a "Roughness Coefficient". Instead, the fractal dimension of the discontinuity surface can be precisely mathematically determined. It was next possible to rewrite the equation for the factor of safety for the case of simple plane shear by substituting the equation for T(peak) into the limiting equilibrium equation. This then gave a method for estimating the factor of safety against sliding on a discontinuity given a measurement of the fractal dimension of the discontinuity surface.