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Atomic Force Microscope Based Near-field Imaging for Probing Cell Surface InteractionsAmini, Sina 03 October 2013 (has links)
Near-membrane and trans-membrane proteins and their interactions with the extracellular matrix (ECM) can yield valuable information about cell dynamics. However, advances in the field of nanoscale cellular processes have been hindered, in part, due to limits imposed by current technology. In this work, a novel evanescent field (EF) imaging technique is designed, modeled, created and tested for near-field imaging in the apical surface of cells. This technique and Förster resonance energy transfer (FRET) were used to investigate interactions between integrins on the cell surface and the ECM protein, fibronectin. The goal was to monitor changes in the integrin density at the cell surface as a function of clustering after binding to fibronectin on the microsphere surface. For the EF technique, quantum dot (QD)-embedded polystyrene microspheres were used to couple light into whispering gallery modes (WGMs) inside the microspheres; the resulting EF at the surface of the microsphere was used as a near-field excitation source with ~50 nm axial resolution for exciting fluorescently-labeled integrins. For FRET measurements (~10 nm axial resolution), QDs (donors) were coated on the surface of microspheres and energy transfer to red fluorescent protein (RFP)-integrin constructs (acceptors) studied. In both techniques, the QD-modified microspheres were mounted on atomic force microscope (AFM) cantilevers, functionalized with fibronectin, and brought into contact with fluorescently-labeled HeLa or vascular smooth muscle (VSM) cells. The results obtained from both methods show the clustering and activity of the integrins and are in good agreement with each other.
Amsterdam discrete dipole approximation (ADDA) was used to study the effects of inhomogeneous surrounding refractive index on the quality factor and position of the WGMs due to the attachment of a microsphere to an AFM cantilever. WGMs of various QD-embedded microspheres mounted on AFM cantilevers were experimentally measured and shown to be consistent with the model.
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Improved Desiccant Coatings for Heat and Water Vapour Transfer on the Matrix Surfaces of Air-To-Air Regenerative Wheels2012 July 1900 (has links)
Air-to-air energy recovery wheels are now widely used in industry and buildings; however, the effectiveness of water vapor exchange in these regenerative wheels appears to be much lower than may be economically feasible. The purpose of this research is to investigate the feasibility of using agglomerated desiccant particle coatings to improve the performance of regenerative wheels used in HVAC air-to-air heat and moisture exchange and energy recovery applications. Desiccant particles coated on wheels lose most of their water vapor sorption capacity due to the method of coating.
Desiccant agglomerates can be made by mixing starch, fine silica gel particulate, and water within an agglomerating device. The desiccant particle agglomerating process improves the desiccant mass transfer properties by increasing the overall surface area of desiccant particles; and also by creating a much rougher surface that can increase the likelihood of turbulent flow, and therefore, increasing the overall mass transfer rates.
The industrial desiccant coating process involves submerging the desiccant into a coating agent and then applying this mix to the substrate or the matrix of the energy wheel. This process was improved in this research by ensuring the particles are applied after the coating agent is applied to ensure that the agglomerates or desiccant particles are not submerged by the coating material.
Because testing energy wheels under steady state operating conditions has proved to be difficult, time consuming and costly in the past, a small parallel flow test cell is used to measure the transient response of coated substrate aluminum sheets after a step change in the inlet air humidity or temperature. Using a previously developed theoretical model, the time constants for these inlet step change responses are then used to predict the sensible and latent effectiveness of a regenerative energy wheel coated with the same agglomerated particles, which is rotated at a known operating speed and wheel face velocity. When the new desiccant coatings are used, it is shown that the latent heat effectiveness for a typical wheel could be up to 85%.
It is found that the steady state air flow pressure drop readings for the test cell shows that agglomerated particles coated on the surfaces within the test cell implies some transitional turbulent flow behavior compared to similar substrate surfaces coated in a conventional manner with desiccant particles (e.g. up to 60% higher pressure drop at a channel Reynolds number of 300) in the same test cell. This implied enhanced turbulence flow friction factor in the test cell suggests a somewhat similar enhancement for increased mass and heat transfer coefficients for the test cell or coated wheel matrices.
The transient results for humidity step changes for air flow through the test cell reveals that the adsorption and desorption response time constants are much larger for the agglomerated coated substrate surfaces than the conventional industrial coated surfaces. These data imply much higher moisture or latent heat effectiveness values for wheels coated with agglomerated particles. When the new desiccant coatings are used, it is shown that the latent heat effectiveness for a typical wheel could be better than 80% or 20% higher than currently available typical energy wheels.
With improvements to the desiccant particle agglomerating process, desiccant coating process and particle coating and testing methods, this thesis shows that significant improvements may be practical for the design, testing and operation of regenerative heat and moisture exchange wheels.
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Molecular Designs Toward Improving Organic PhotovoltaicsNantalaksakul, Arpornrat 01 February 2009 (has links)
Organic photovoltaics (OPVs) that have been studied to date have poor power conversion efficiencies. This dissertation focuses on various molecular designs that could lead to both a fundamental understanding of photoinduced charge separation at a molecular level and also provide a solution to improve bulk properties of organic materials to overcome the poor efficiencies of OPV devices. The effect of molecular architectures on the efficiency of electron transfer, a primary step in OPVs functioning, is evaluated in this work. We have shown that even though dendrimer provides an interesting architecture for efficient electron transfer due to the presence of multiple peripheries around a single core, this architecture leads to trapping of charge at the dendritic core. This results in a decrease in the electron transfer efficiency in solution and also limits the possibility of charge transport to the electron in a photovoltaic device. Non-conjugated polymers containing conductive EDOT units at side chains were also designed and synthesized. The frontier energy levels of these polymers can be easily tuned by changing the conjugation lengths of side chain EDOT oligomers. Moreover, by incorporating crosslinkable units as co-side chains, the absorption bandwidth of these polymers can be manipulated as well.
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Studies in collisional energy transfer of highly rotationally and vibrationally excited molecules / Trevor C. Brown. / Studies in collisional energy transfer of highly excited molecules.Brown, Trevor C. January 1988 (has links)
Typescript (Processed) / Errata slip inserted. / Spine title: Studies in collisional energy transfer of highly excited molecules. / Bibliography: leaves 143-167. / viii, 169 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis describes the studies made on several unimolecular reaction systems in order to obtain collisional energy transfer information on highly excited polyatomic molecules. Pressure-dependant very low-pressure pyrolysis (VLPP) and infrared multiphoton decomposition (IRMPD) experimental techniques are used. / Thesis (Ph.D.)--University of Adelaide, 1989
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Energy transfer at gas-liquid interface towards energetic materials /Szabo, Tamas, January 2007 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on February 29, 2008) Vita. Includes bibliographical references.
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Development of a unified mass and heat integration framework for sustainable design an automated approach /Moodley, Anand. January 2007 (has links)
Thesis (M.Eng. (Chemical Engineering)) -- Universiteit van Pretoria, 2007. / Includes bibliographical references.
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Time-fractional analysis of flow patterns during refrigerant condensationVan Rooyen, Eugene. January 2007 (has links)
Thesis (M. Eng.(Mechanical and Aeronautical Engineering))--Universiteit van Pretoria, 2007. / Abstract in English. Includes bibliographical references.
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Absorbed dose and biological effect in light ion therapy /Hollmark, Malin, January 2008 (has links)
Diss. (sammanfattning) Stockholm : Stockholms universitet, 2008. / Härtill 7 uppsatser.
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Blends of Polydioctylfluorene (PFO) with polymeric and monomeric energy acceptors: correlation of fluorescence energy transfer and film morphology in breath figures and filmsNguyen, Vu Anh January 2008 (has links)
Thesis (Ph.D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2008. / Committee Chair: Tolbert, Laren; Committee Member: Collard, David; Committee Member: Lyon, Andrew; Committee Member: Srinivasarao, Mohan; Committee Member: Wilkinson, Angus
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Synthesis and photophysical characterization of porphyrin-containing supramolecular systems structural issues for porphyrin photophysics and electron transfer /Garrison, Shana A. January 2005 (has links)
Thesis (Ph. D.)--University of Akron, Dept. of Chemistry, 2005. / "August, 2005." Title from electronic dissertation title page (viewed 09/24/2005). Advisor, David A. Modarelli; Committee members, Matthew Espe, Michael Taschner, Chrys Wesdemiotis, Stephanie Lopina; Department Chair, David Perry; Dean of the College, Charles B. Monroe; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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