Environmental sustainability, strict Municipal bylaws, ever-increasing waste disposal / Thesis (M.Sc.) - University of KwaZulu-Natal, Pietermaritzburg, 2009.

Fluorescence microscopy techniques, restricted by the diffraction limit of light, have seen a remarkable advancement in recent years. An approach called dSTORM (direct stochastic optical reconstruction microscopy) utilises the photoswitching capabilities of organic fluorophores when in the presence of special mounting media, the solution within which the sample is placed, to detect single molecule fluorescing events over time. The image that can be reconstructed from these events is not diffraction limited, but instead is limited by how well each event can be precisely localised. In Chapter 3 the importance of using a suitable mounting buffer in order to achieve super-resolution dSTORM is discussed in detail. A quantitative method for determining the reactivity of thiol dSTORM switching mountants was developed for use within the lab. Every fluorescent probe has different photophysical properties which can be manipulated by varying the composition of the switching buffer to enhance desirable qualities, such as; increased photon counts, faster switching rates, and longer survivability. In addition to investigating the effects of buffer composition the use of a near UV light-source was also explored as a means of manipulating the same properties to improve overall resolution and quality of the resulting images. A range of photoswitchable fluorescent dyes were tested including Alexa Fluor 660 which is a dye that to my knowledge has not been greatly tested for use in single molecule localisation microscopy by others to date. This dye performed strongly alongside the traditional Alexa Fluor 647 used for dSTORM imaging in optimal conditions. A relatively new approach to single molecule imaging which does not require the fluorophore to photoswitch, called DNA-PAINT (point accumulation for imaging in nanoscale topography), has been investigated throughout this thesis. This approach relies on the transient binding of small oligonucleotide sequences, called “Imagers”, to target docking strands anchored in positions of interest. These imagers have a photostable and bright fluorophore conjugated to the oligonucleotide. It is the transient immobilisation of the imager strand, as it binds to a fixed docking strand, which appears as stochastic blinks. The duration of these events, which can be extended by increasing the number of overlapping base pairs, is primarily responsible for improved localisation precision and therefore potentially overall resolution. At the end of Chapter 3 I compare this new pointillism microscopy approach, DNA-PAINT, with dSTORM using a set of custom-designed oligonucleotide sequences that allow both formats to be employed on the same target. The transient binding of small strands of oligonucleotides offers a far more controllable system for stochastic imaging. In Chapter 4 I use this superior approach to achieve greater resolution than other fluorescence techniques in biological samples, sufficient to visualise single ryanodine receptors (RyR). The RyR are extremely important in the contraction of muscle cells as they are capable of detecting transient changes to calcium concentration and are responsible for releasing large stores of calcium from the sarcoplasmic reticulum. With DNA-PAINT I observed that RyRs cluster into irregular arrays which contain significant gaps that are occupied by other proteins, including junctophilin (JPH). The stoichiometry of JPH with RyR varied cluster to cluster, exposing a new complexity in the regulation of RyRs. In Chapter 5, quantitative super-resolution is reliably achieved through the implementation of quantitative DNA-PAINT (qPAINT) within the Python Microscopy Environment (PYME) software. Quantitative measurements are possible because of the statistical predictability of DNA hybridisation and the near constant influx of fresh imager strands by diffusion. This results in limited photobleaching, a permanent dark state. The frequency with which a region of interest blinks is proportional to the number of binding sites available, and therefore the mean dark time between detected events is also inversely proportional. I validate my approach to qPAINT, which maintains the spatial information of individual structures, by using a DNA-origami test slide. Two distinguishable structures were present and an estimate for the ratio of available docking sites between them was satisfactorily established. I conclude that with this tool, molecule densities can be inferred and information about biological samples can be probed to new levels. The results of the full methodological approach to accomplish dual-colour super-resolution imaging of optically thick cardiac tissue, using both dSTORM and DNA PAINT techniques, is discussed in detail in Chapter 6. The current range of photoswitchable fluorophores limits the possible combination of molecular dyes for use with dSTORM and some compromise is made in their selection. For DNA-PAINT, the prospect of chromatic aberration is removed by imaging the same dye in subsequent rounds of imaging. The process, called Exchange-PAINT, allows the user to remove previously imaged imager strands, through a series of washes, and replace them with a complementary sequence for another target. I introduce the concept of using quencher strands to eliminate signal from unwanted imager sequences, accelerating their removal in samples of reduced diffusion and decreasing the risk of sample disturbance, in a process we termed Quencher Exchange-PAINT. Using this technique, I achieve superior super resolution results in optically thick samples. The results presented in this thesis are expected to (1) lead to a better understanding of the variables associated with single molecule localisation microscopy, (2) further reveal the complexity in cardiac protein distribution, (3) quantify relationships between co-localising proteins and other targets, and (4) apply DNA-PAINT to imaging in optically thick biological samples. This study shows promise for the future applications of the DNA-PAINT pointillism super-resolution method and its ability to investigate a multitude of biological questions.

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Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1922. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed March 17, 2010) Includes bibliographical references (p. 34) and index (leaf 35).

Graffiti is a near constant problem for historic structures and monuments, particularly in urban environments. Currently available non-destructive techniques are not always adequate for graffiti removal. Acrylic spray paints, the most common graffiti material, are composed of polymers which are subject to degradation by ultraviolet light. The feasibility of using this mechanism as a tool for graffiti removal was explored through practical experiments. Red acrylic paint was sprayed onto samples Indiana limestone which were then exposed to UV-B light sources for two, four, and six weeks. Following exposure, samples were scrubbed with acetone, a common solvent used in graffiti removal. Relative differences in the paint removal on the treated and untreated sides were observed, with more paint being removed from the treated sides in some cases. Additional samples were coated with titanium dioxide and exposed to ultraviolet light, yielded a greater level of overall paint removal. It was concluded that this mechanism offers promise and warrants further study. / Department of Architecture

Giovanni Bellini (b. 1435/40-d. 1516) has long been considered a dominant figure in the Venetian painting of the Early-High Renaissance, his main reputation being a colourist. The distinctive optical and technical characteristics of his work have drawn substantial scholarly attention in the present century, but the studies in this subject have not been developed as a coherent theory with regard to changes in painting technique in the fiftenth-century Italy. The purpose of this dissertation, therefore, is to investigate Bellini's choice and application of painting materials, attempting to establish links between the technical qualities and the formal values of his work. In the process of establishing Bellini's position with regard to the use of paint media and support, this thesis also provides a substantial overview of the use of canvas and of oil pain in the later fifteenth century. The study is encouraged by recent discoveries about Bellini's technique that have emerged from conservation of his paintings. As well as addressing published conservation results, the thesis includes new observations on four canvases attributed to Bellini's father Jacopo, and two Madonnas from Bellini's workshop scientifically examined at UCL Painting Analysis. In order to investigate Bellini's colour and handling of paint within a broader socio-economic milieu, this study deals with the commercial documents such as tariffs, government records, and merchant account books, indicating that Venice was the centre of the international colour trade and that Venetians were widely engaged with this trade. The resulting advantages of Venetian painters who were active at this commercial heart, and the question of how deeply the pragmatic experience of colours that Venetian merchants obtained from the trade penetrated their aesthetic taste will be discussed. Using both scientific and documentary analyses in combination with visual analysis which integrates these findings, this study examines Bellini's translation of the skills of tempera to oil pain and the stylistic changes that occurred with the extensive use of oil medium. It looks at how Bellini developed canvas as a support for mural painting and the technique he employed on such an unconventional support. It will also study the methods in which he established the predominance of colour as an element of composition at the early sixteenth century. In conclusion, it will argue that Bellini's increasing choice of canvas and corresponding use of oil on it changed the general concept of picture-making and became a new format of painting that was to exert a crucial influence on Cinquecento Venetian painting.

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains vii, 83 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references.

Thesis (Ph.D.)--University of Wollongong, 2003. / Typescript. Bibliography: leaf 288-292.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [195]-197).