Thesis (M.S. in Physics)--Naval Postgraduate School, December 2002. / Thesis advisor(s): Richard C. Olsen, Richard M. Harkins. Includes bibliographical references (p. 111-114). Also available online.

No description available.

Ultraviolet (UV) radiation is a potent DNA-damaging agent and a known inducer of mutations and skin cancer. The increasing incidence of skin cancer has emphasised the importance of understanding the mechanistic processes involved in the interaction of UV radiation with DNA. One of the most significant photoproducts, induced by UV light, in the DNA molecule is the cis-syn cyclobutane pyrimidine dimer. These dimers, particularly the cytosinecontaining dimers, have been implicated in the mutagenic and carcinogenic effects of sunlight. Dimerisation of contiguous pyrimidine residues in DNA can result from direct irradiation (A = 295-310 nm) or photosensitised irradiation (A > 300 nm) by endogenous photosensitisers. Direct irradiation of DNA produces a wide range of photoproducts, whereas triplet photosensitisation of DNA by acetone produces only thymine, cytosine and cytosinethymine dimers. Thus, acetone photosensitisation of DNA can be used in the elucidation of the mechanistic processes involved in the formation of photoproducts from the direct irradiation of DNA. Calf thymus DNA was irradiated in the presence of acetone at wavelengths greater than 300 nm, using a high pressure mercury lamp. Experimental conditions investigated were irradiation time, acetone concentration and DNA concentration. Irradiated DNA samples were degraded by hot acid hydrolysis to excise the dimers. The yields of thymine and cytosine-thymine dimers were able to be quantitated by reverse phase high performance liquid chromatography with DV detection.Independent kinetic mechanisms were proposed for thymine and cytosine-thymine dimerisation in calf thymus DNA. Rate constants were assigned from experimentally determined values, values cited in literature and values calculated from Stern-Volmer steady state analysis of the proposed mechanisms. Verification of the proposed kinetic mechanisms was achieved by the comparison of experimental dimer yields with those calculated from the computer simulation of the proposed kinetic mechanism. The computer program CAKE (Computer Analysis of Kinetic Equations) was used to obtain the simulated data. Good agreement between the experimental and simulated data was taken as corroboration of the proposed kinetic mechanism. A section of this work was concerned with the application of spectroradiometry to determine the amount of light intensity absorbed by irradiated solutions. The modification, calibration and operation of a Macam SR 9010 spectroradiometer to achieve this aim is discussed. / Thesis (M.Sc.)-University of Natal, Durban, 1992.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 24, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Renee Jiji. Includes bibliographical references.

Thesis (M.S. in Systems Engineering (EW))--Naval Postgraduate School, March 2005. / Thesis Advisor(s): Richard M. Harkins, Richard C. Olsen. Includes bibliographical references (p. 53). Also available online.

No description available.

An ultrafast UV-visible spectrometer was designed and implemented. An optical parametric amplifier was constructed to be used as a pump source for the spectrometer. Using nonlinear optical processes and an 800 nm ultrashort pulses, tunable infrared(IR) light was produced with a wavelength range of ∼.1 mum to 3 mum. The IR light was then mixed with 800 nm light to produce tunable visible light with a wavelength range of 466 nm to 600 nm. Supercontinuum (SC) was used as the probe pulse of the spectrometer, providing a large observation bandwidth. Commercially purchased fast spectrometers were used as the detection mechanism. The characterization of the set up, as well the observation of some ultrafast molecular dynamics observed in 8-hydroxy-1,3,6-pyrenetrisulfonic acid, are presented.

Thesis (M.S.)--Brigham Young University. Dept. of Physics and Astronomy, 2006. / Includes bibliographical references (p. 61-64).

No description available.

Thesis (Master of Applied Sciences in Chemistry)--Cape Peninsula University of Technology, 2018. / Biosensors have been on the forefront to provide clinical diagnosis tools for various diseases. Proper selection of biomarkers as well as chemical electrode modification is key in the fabrication of electrochemical biosensors. Hence, electrode modified with nanomaterials devices to improve electroanalytical applications. These nanomaterials were functionalized to improve conductivity, accelerate signal transduction and amplify biorecognition events. Thus, resulting in novel sensing platforms that are highly sensitive and selective towards the target analyte. In this study, gold nanorods (Au NRs) capped with CTAB, zeolitic imidazole framework were synthesised using the seed mediated and hydrothermal method respectively. Composites of gold nanorods with cysteine, ZIF-8 or both were also synthesised. All synthesised materials were characterized using ultraviolet–visible (UV-Vis) spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-Ray diffraction (XRD) and cyclic voltammetry (CV) techniques. The obtained results confirmed the synthesis of the nanomaterials and composites. Identification of the ideal platform for fabrication of a transducer with the best electrochemical response was determined by studying the combinations of the synthesised nanomaterials and composites. The studied parameters were surface coverage, conductivity, rate of electron transfer constant. Cysteine-Au NRs composites platforms, had exceptional properties hence its synthesis optimisation of was undertaken. The effect of CTAB, reaction time, volume and concentration ratio of Au:Cysteine, temperature and pH on the composite properties were assessed. However, this composite’s electrochemical properties decreased when bioconjugated with the antibodies. Hence, the choice of Au NRs CTAB functionalised ZIF-8 (CTABAu/ZIF-8) as the transducer for biosensor applications due to a more favourable biocompatibility. Biosensor fabrication was done by drop coating glassy carbon electrode with the CTABAu/ZIF-8 forming a transducer followed by immobilisation of the antibody (Ab) using a covalent attachment method with glutaraldehyde (GA) as a cross linker. The target analyte, epidermal growth factor (EGF) was interacted with the Ab binding sites via electrostatic forces. All the fabrication steps were optimized for biosensor components, immobilization technique (drop coating and immersion), concentration and incubation time of linker and bioreceptor, as well as the synthesis of the CTABAu-ZIF-8 composites where in situ and ex situ techniques were compared together with the effect of the concentration ratio of Au: ZIF-8. There was also an analysis of optimum pH. Optimum conditions were found to be immersion in 3 % GA and 2 μg/ml Ab, with incubation times of 8, 10 and 5 minutes for GA, Ab and EGF respectively at a pH of 6. The following electroanalytical techniques: cyclic voltammetry (CV), differential pulse voltammetry (DPV) and square wave voltammetry (SWV) were utilised for EGF detection. The DPV showed better reproducibility, higher currents and better resolution hence; it was the method of choice. The technique’s optimisation involved assessments of the effect of step potential, starting potential and pulse amplitude. The optimum response for pulse amplitude, step potential and starting potential were 60 mV, 20 mV and 0.5 V respectively. The biosensor analytical parameters were linear towards EGF in the concentration range from 2 to 100 nM with a detection limit of 0.58 nM. Reproducibility and repeatability tests were acceptable, and the biosensor had a stability over 80 % within 15 days. There was no interference observed in the presence of glucose and creatine. The EGF biosensor was successfully applied in urine and saliva analysis, obtaining 67.5 and 3.12 nM respectively. This biosensor’s positive outcome strongly suggests its potential as a diagnosis tool for early detection of kidney disease as it was able to detect EGF concentration within physiological levels of EGF in normal kidney function.