Aerosols of nitrate solutions were irradiated in the presence of radical scavengers in an attempt to measure the yield of hydroxyl radical in both the aqueous phase and the gas phase. Carbon monoxide, benzoic acid, benzene and cyclohexane were used as scavengers to trap hydroxyl radical. The products from the reaction of these scavengers with hydroxyl radical were analysed with High Performance Liquid Chromatography and mass spectrometry. The radiant flux in the chamber was measured via ferrioxalate actinometry, both with bulk liquid and aerosol droplets. Many quantitative results were obtained but several anomalies were found. This suggests that Mie theory is not capable of predicting rates of photochemical reactions within droplets.

Thesis (Ph.D.)--University of Melbourne, School of Chemistry, 2007. / Typescript. Includes bibliographical references (leaves 103-109).

Anthropogenic gas- and particle-phase emissions affect the climate by absorbing and scattering radiation, and have been linked to adverse health effects. Black carbon (BC), a by-product of incomplete combustion, is the most potent light-absorbing component of atmospheric aerosols, with a top-of-the atmosphere direct radiative forcing estimated to be only second to CO2. However, there is a large uncertainty associated with BC’s total direct and indirect radiative forcings due to uncertain source emissions and optical properties and complex interactions with clouds. In this dissertation we investigate the direct radiative impact of two of the most important sources of BC particles: biofuel combustion and vehicles. Together these sources contribute around 40% of the global atmospheric BC burden. Recently, both of these energy sources are undergoing rapid technology changes, and the climate impacts from the emissions of these newly adopted technologies remain uncertain. We also investigate the role of atmospheric processing on the optical properties and growth rates of particles. This dissertation first assesses the climate impacts of aerosol emissions of two rapidly emerging technologies: improved cookstoves and gasoline direct injection (GDI) vehicles. We performed extensive measurements of gas- and particle emissions and optical properties of emissions from both these sources. Our data suggests that improved rocket cookstoves have, on average, a factor of two lower particulate matter (PM) emissions compared to traditional cookstoves but only a 4% climate benefits associated with their emissions. In contrast, we estimated a 30% climate benefit from switching traditional cookstoves to gasifier ones. Of all the stoves tested, charcoal stoves had the lowest emissions and climate impacts. Our data suggests the widespread deployment of improved cookstoves to replace existing, inefficient, traditional cookstoves will likely result in health and climate co-benefits. Similarly, we estimated that the rapid adoption of GDI vehicles to replace existing port fuel injection (PFI) vehicles will likely result in reduced warming from emissions. This is due to the higher fuel economy of GDI engines; we measured an average CO2 reduction of 57 g/mi, from switching engine technologies. GDI engine emissions had higher PM emissions compared to PFI engines, similar to previous findings. In addition, our data suggests that newer GDI engines have a factor of two lower PM emissions compared to older GDI engines. These improvements in emissions may enable GDI-equipped vehicles to meet the new Federal Tier 3 PM standard of 3.0 mg/mi without gasoline particulate filters (GPF, which would reduce their fuel economy). To better constrain the large uncertainty of radiative forcing associated with cookstove emissions, this dissertation examines emissions and optical properties from several cookstove and fuel combinations. We performed extensive laboratory measurements of the optical properties of fresh cookstove emissions using the newly developed firepower sweep protocol. Current model treatments of the optical properties of cookstove emissions assume: (1) complete internal mixture between BC and non-BC material and (2) absorption properties of organics based on parametrizations developed for biomass burning emissions. These assumptions do not accurately represent optical properties of fresh cookstove emissions. We developed new parametrizations of optical properties (BC-mass absorption cross section (MACBC), absorption angstrom exponent (AAE), and single scattering albedo (SSA)) of aerosol emissions from cookstoves as a function of the BC-to-PM mass ratio. These parametrizations are designed for use in climate models to more rigorously assess the global climate implications from adoption of improved stove technologies. Upon entering the atmosphere aerosol emissions undergo complex chemical transformations. Aerosol optical properties depend on their atmospheric processing which controls the amount of coating the particles accumulate and their lifetime. To assess the effects of coating on the optical properties, we performed targeted experiments using real world, size selected, BC particles emitted from a rocket improved cookstove, and coated with biogenic secondary organic aerosol (SOA) material. These experiments explicitly target to evaluate measurements and modeling using simple formulation like Mie theory. Measurements of MACBC and the mass scattering cross section (MSC) of coated BC particles were in good agreement with Mie predictions when the organic-to-BC mass ratio>5. Scattering (but not absorption) was sensitive to BC fractal-like morphology; Mie theory under-predicted measured scattering of fresh emissions. Our data suggest that Mie theory can be used in climate models to approximate the optical properties of coated BC particles emitted from cookstoves, if the mixing-state of BC particles is known. In this dissertation, we present initial evidence that particle growth rates depend on seed composition and gas-phase supersaturation. Current models do not account for seed-dependent growth rates. We conducted experiments to investigate the growth of diesel and biogenic SOA particles. Both seeds were exposed to the same gas-phase supersaturation, which allows us to accurately retrieve differences in growth rates and decouple the effects of surface activity and accommodation coefficients. We estimated that the accommodation coefficients of condensing material was 10% to 30% lower on the diesel particles compared to the SOA particles. Moreover, we measured larger surface activity of condensing material on the diesel particles, potentially due to less-miscible condensing vapors in the diesel particles compared to the SOA particles. Our data suggest that growth of BC (diesel) particles in the atmosphere is likely slower compared to SOA particles. Accurately representing these processes is important to estimate the lifetime and absorption enhancement from coated BC particles, as they compete with other particles for condensable vapors.

Standard optical microscopes cannot resolve images below 200 nm within the visible wavelengths due to optical diffraction limit. This Thesis reports an investigation into super-resolution imaging beyond the optical diffraction limit by microsphere optical nano-scopy (MONS) and submerged microsphere optical nano-scopy (SMON). The effect of microsphere size, material and the liquid type as well as light illumination conditions and focal plane positions on imaging resolution and magnification have been studied for imaging both biological (viruses and cells) and non-biological (Blu-ray disk patterns and nano-pores of anodised aluminium oxide) samples. In particular, sub-surface imaging of nano-structures (data-recorded Blu-ray) that cannot even be seen by a scanning electron microscope (SEM) has been demonstrated using the SMON technique. Adenoviruses of 75 nm in size have been observed with white light optical microscopy for the first time. High refractive index microsphere materials such as BaTiO3 (refractive index n = 1.9) and TiO2-BaO-ZnO (refractive index n = 2.2) were investigated for the first time for the imaging. The super-resolution imaging of sub-diffraction-limited objects is strongly influenced by the relationship between the far-field propagating wave and the near-field evanescent waves. The diffraction limit free evanescent waves are the key to achieving super-resolution imaging. This work shows that the MONS and SMON techniques can generate super-resolution through converting evanescent waves into propagating wave. The optical interactions with the microspheres were simulated using special software (DSIMie) and finite different in time domain numerical analysis software (CST Microwave Studio). The optical field structures are observed in the near-field of a microsphere. The photonic nanojets waist and the distance between single dielectric microsphere and maximum intensity position were calculated. The theoretical modelling was calculated for comparisons with experimental measurements in order to develop and discover super-resolution potential.

En raison de leur capacité à absorber et diffuser la lumière, les aérosols jouent un rôle essentiel dans le bilan radiatif de la Terre. Cependant, la grande variabilité spatiale et temporelle de leur concentration et propriété physico-chimique rend délicate la quantification précise de leur impact sur le climat. Les mesures par télédétection sont des outils efficaces d’observation et d’analyse des aérosols de l’échelle locale à globale. Néanmoins, pour exploiter pleinement les capacités de ce type d’instruments, il est indispensable de mieux connaître les propriétés optiques des aérosols qui dépendent de leurs propriétés minéralogiques ou chimiques. Ces deux propriétés sont liées par l’Indice Complexe de Réfraction (ICR), qui représente une des principales sources d’incertitudes de l’étude des aérosols par télédétection. L’objectif de ce travail est donc de proposer et d’exploiter une méthode originale visant à mieux déterminer les ICR de particules. Pour cela, une nouvelle approche robuste et versatile a été développée et mise en œuvre. Ainsi, afin de déterminer précisément les capacités de cette dernière, la validation de chacune des étapes du processus d’obtention des ICR a été réalisée. L’approche complète a ensuite été appliquée pour des particules en suspension de SiO2 amorphe et cristalline, qui constituent notamment, la fraction majoritaire des aérosols volcaniques et désertiques.Enfin, les premiers résultats obtenus pour des aérosols prélevés lors de campagnes de mesures sont également présentés. Ceux-ci mettent en évidence le potentiel de l’approche proposée pour la détermination d’ICR, en vue d’améliorer l’exploitation de la mesure des aérosols par télédétection. / Due to their ability to absorb and scatter radiations, aerosols play an important role in the Earth’s radiative budget. However, quantitative estimations of their effects on climate are quite uncertain due to their large spatial and temporal variability in terms of concentration and physical properties. Measurements from remote sensing instruments are efficient tools to observe and investigate aerosol distributions from regional to global scales. Nevertheless, to fully exploit instrument capabilities, precise optical properties – dependent on chemical or mineralogical properties – are needed. These properties are linked by the Complex Refractive Index (CRI), which represents one of the main sources of uncertainty for studying aerosols from remote sensing instruments.The objective of this study is to propose and exploit a new methodology, aiming to determine precise CRI of particles. For this purpose, a new robust and versatile approach has been developed and implemented. Moreover, to determine capabilities of this approach, validation of each step in the procedure for CRI determination has been realized. The complete approach has been also applied for suspended particles of amorphous and crystalline SiO2, which are the major fraction of volcanic and mineral dust aerosols. Lastly, first results from collected samples from measurement campaigns are also presented. These results highlight the potential of the proposed approach to determine CRI, in order to improve the aerosol measurement exploitations by remote sensing instruments.

Black carbon (BC) is the light-absorbing component of soot, a combustion-generated aerosol that warms the climate by absorbing solar radiation. Its impacts on climate depend on its microphysical properties, which are modified by atmospheric processes including condensation, coagulation and wet removal. State of the art climate models consider soot in a concentric core/shell configuration, with a BC core coated by nonrefractory material such as organics or sulphate. Within this model, thicker coatings enhance visible light absorption, but also wet removal efficiency, and these have opposing effects on the total amount of light absorbed over BC’s lifetime. How well the core/shell model can calculate Mass Absorption Coefficient (MAC, the ratio of absorption to BC mass) is uncertain, as real soot forms more complex (often fractal) shapes, and detailed optical models using these morphologies predict the core/shell model may under- or over-estimate MAC depending on the precise properties of the particles. Few reliable measurements of variations in ambient MAC are available, as most older measurement techniques suffer from systematic uncertainties. In this work, a Single Particle Soot Photometer (SP2) and PhotoAcoustic Soot Spectrometer (PASS) were used to measure BC mass concentration and absorption, and these instruments do not suffer from such uncertainties. The SP2 was also used to report core size and coating thickness distributions that are required to test state of the art climate models. Firstly, a method was developed to minimise bias in the measured coating thicknesses related to the limited detection range of the SP2. The sensitivity of this technique to the assumed density and refractive index of the BC core was also explored, and the most appropriate parameters to use with ambient measurements were determined. Core and shell distributions were measured in Pasadena, California under a range of different photochemical ages. These were then used to calculate MAC, which was compared to that measured using the SP2 and PASS. The measured and modelled MAC agreed within 10% at 532 nm, though this was dependent on the assumed refractive index of the BC core. Overall MAC increased by 15 –25% in around one third of a day of photochemical ageing. This is quite modest compared to some climate models, but not compared to the previous best estimate, which predicted MAC may increase by a factor of ~1.5 over BC’s lifetime. Core and coating distributions were also measured in Canadian boreal biomass burning plumes. A case study was presented comparing the properties of BC in three plumes, one of which had passed through a precipitating cloud. It was demonstrated that larger and more coated BC-containing particles were removed more efficiently, in agreement with previous thermodynamic theory. By calculating MAC using the measured core/shell distributions and comparing to measured scattering, it was demonstrated that the MAC and single-scattering albedo in the plumes were likely not significantly affected by the wet removal, as greater differences were observed between the two plumes not affected by precipitation.

Submitted by Alexandra Feitosa (alexandra.feitosa@ufpe.br) on 2017-07-24T13:44:54Z No. of bitstreams: 1 2011-Dissertação-DeniseSantos.pdf: 1719957 bytes, checksum: b5e452e2896a290b445f98527588536b (MD5) / Made available in DSpace on 2017-07-24T13:44:54Z (GMT). No. of bitstreams: 1 2011-Dissertação-DeniseSantos.pdf: 1719957 bytes, checksum: b5e452e2896a290b445f98527588536b (MD5) Previous issue date: 2011-09-02 / Neste trabalho, estudamos mecanismos de operação de lasers com realimentação por espa-lhamento de luz. Foram usados dois sistemas físicos: colóides consistindo de nanopartículase moléculas de rodamina dissolvidas em álcool e partículas dielétricas contendo rodamina noseu interior. No primeiro, as partículas espalhadoras (nanoesferas de sílica envoltas por umananocasca de ouro) têm diâmetros da ordem do comprimento de onda da luz e usamos a teoriade Mie para entender o comportamento do sistema. Já no segundo, trabalhamos com esferas desílica de dezenas de micrômetros, nas quais o comportamento da luz pode ser descrito atravésda óptica geométrica.Na primeira etapa verificamos que a colocação de uma nanocasca metálica nas partícu-las espalhadoras contribui para o engrandecimento da seção de choque de espalhamento e docampo eletromagnético local, permitindo obtermos lasers aleatórios com um limiar de operaçãomenor do que é obtido com dielétricos. Medimos o espectro de emissão em função da fluênciado bombeamento tanto da suspensão de partículas em uma cubeta como também colocando asuspensão de partículas no núcleo de uma fibra microestruturada ("random fiber laser"). Foipossível, em ambos os casos, verificar uma redução da largura de linha e comportamento nãolinear da luminescência, compatíveis com uma operação tipo laser, como desejávamos. Entre-tanto, verificamos uma diminuição do sinal devido à ablação das nanocascas.Realizamos também um breve estudo da medida do Livre Caminho Médio (LCM) dosfótons no meio aleatório. Para a medida do LCM foi analisada a distribuição espacial da in-tensidade de luz devido ao retro-espalhamento. A técnica utilizada, conhecida comoCoherentBackscattering, é baseada na consideração de que ondas viajando com momentos reversos emum meio espalhador interferem construtivamente gerando um padrão de intensidade, na di-reção de retro-emissão, que tem a forma de um cone, cuja largura é determinada pela distânciamédia que o fóton percorre no meio espalhador, entre duas colisões sucessivas. O LCM é umparâmetro importante para a caracterização de lasers aleatórios.Na segunda etapa, esferas de sílica de dezenas de micrômetros contendo rodamina em seuinterior foram bombeadas individualmente. Partículas com essas dimensões são capazes deconfinar o campo eletromagnético. Esse confinamento é então utilizado como mecanismo derealimentação para a amplificação do campo e operação tipo laser. A emissão do corante nessasmicroestruturas ocorre em conjuntos discretos de frequências, de acordo com os modos resso-nantes da cavidade esférica que são chamados Modos de Galeria de Sussurro. Este sistema foiestudado em detalhes e foi determinado o limiar de operação do laser em tais microcavidades. / In this work, we studied mechanisms for operation of lasers with feedback provided by scat-tering of light. We used two types of physical systems: 1 -colloids consisting of nanoparticlesand rhodamine molecules dissolved in alcohol, 2 - dielectric particles containing rhodamine. Inthe first regime, the scattering particles (nanospheres of silica surrounded by a gold nanoshell)have diameters on the order of the light wavelength and Mie theory was used to understand thebehavior of the system. In the second, we worked with silica spheres of tens of micrometers,whose behavior can be described by geometrical optics.In the first stage of the study, we found that metalic nanoshells suspended in a colloid withrhodamine contribute to enhancement of the local electromagnetic field, allowing to obtain arandom laser operating with a threshold lower than it is achieved with dielectric scatterers, andobtained considerable reduction in the emission spectral width. We performed measurementsof the emission spectrum as a function of the pumping fluence both in particle suspension ina cuvette as well as placing the suspension of particles in the core of a microstructured fiber("Random Fiber Laser"). The latter allows us to perform experiments using a concentration ofscatterers from 3 to 4 orders of magnitude lower than measurements performed with cuvettes.It was possible, in both cases to verify a reduction of line width and non-linear behavior of theluminescence, consistent with laser operation, as we wished. However, we found a decrease insignal due to ablation of nanoslells.We also studied of the mean free path of the photons in a random media. To measure themean free path, the spatial distribution of light intensity due to backscattering was analyzed.The technique, known as Coherent Backscattering of Light, is based on the consideration thatwaves traveling in time-reversed paths through a scattering medium interfere constructively,generating an intensity pattern in the direction of retro-emission, which is shaped like a cone,whose width is determined by the average distance that the photon travels through the scatteringmedia between two successive collisions. The mean free path is a important parameter for thecharacterization of random lasers.In the second stage of the work, silica spheres of tens of micrometers containing rhodaminewere individually pumped. Particles with these dimensions are able to confine the electro-magnetic field. This confinement provides a feedback mechanism for light amplification andlaser operation. The dye emission in these microstructures occurs in discrete sets of frequen-cies, according to the resonant modes of the spherical cavity, which are called WhisperingGallery Modes. This system has been studied in detail and we determined the threshold oflaser operation in such cavities.

This paper investigated the effects of swirl number and momentum ratio on the atomization and mixing performance of Swirl-Venturi Lean Direct Injection technology. Mie scattering of liquid water, was used to identify the location of water droplets in a cross section of the injector spray. Experiments were performed with three air swirlers with vane angles of 45, 52 and 60 degrees. The swirl number varied from 0.58 to 1.0 and air-to-liquid ratios from 15.8 to 35.6. A transition was observed in the liquid spray distribution for the 52 degree case, which unexpectedly produced twice as much signal than the 45 and 60 degree cases. The main cause of this increased signal may be due to instabilities in the flow when transitioning from low to high swirl states. The results from investigation of swirl number it was found that the spray pattern for is sensitive to swirl intensity. Two flow states were observed for a lower and higher swirl flow as well as a transition state that occurred with the lower swirl state. This work may aid in the specific inquiry of physical mechanisms relating to the effect of flow states on spray distribution. It is found that improved atomization and mixing performance are a result of increase in swirl number.

Alberto Grau is arguably one of the most influential contemporary Venezuelan choral composers and conductors of the twentieth and twenty-first centuries. This thesis explores the synthesis of Venezuelan nationalism with global internationalism found within his works. As a student of the nationalistic generation of composers (Vicente Emilio Sojo, Juan Bautista Plaza, and Ángel Sauce) Grau's works display the distinct characteristics found in Venezuelan music. His output also exhibits international influences, using texts associated with social and environmental events and concerns including literary and musical influences of other nations and cultures. The first section of the thesis traces the lineage of Venezuelan choral composers beginning with the colonial period and the Escuela de Chacao to the nationalistic composers from the Santa Capilla generation. The second section describes Alberto Grau's compositional style as exemplified in his work Kasar mie la gaji (The Earth is Tired). The final section of the document comprises interviews with Alberto Grau and his wife, the Venezuelan choral conductor, María Guinand. Guinand studied piano and conducting with Alberto Grau and was his assistant at the Orfeón Universitario Simón Bolívar and the Schola Cantorum de Caracas. She is the founding conductor of the Cantoría Alberto Grau and the editor of the Latin American division of Earthsongs Music. Through interviews and analysis this project informa the reader about the life and compositions of Venezuelan choral composer and conductor Alberto Grau.

Patients with pancreatic cancer in metastasis rarely survive, thus the need for diagnostic tools for early stage detection. Current techniques such as ELISA and SPR are complex and expensive and cannot detect cancer in its early stages. Cancer Antigen 242 (CA 242) is a potential protein biomarker of pancreatic cancer with high sensitivity and specificity. This thesis presents a negative Dielectrophoresis (DEP) based method of detecting pancreatic cancer protein biomarker CA 242 in serum. A spectrum of concentration levels was generated with a cut off level 20 U/mL using a transduction mechanism with negative DEP spectroscopy, light scattering, and image processing. This was a fast and cost-effective method to diagnose early stage pancreatic cancer. This thesis also presents the design and simulation of an electrode modified to increase the electric field gradient with reduced heat generation and a concentration prediction model to predict concentrations from the generated spectrum of experiments.