Orientador: Alvaro Penteado Crósta / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-24T23:17:39Z (GMT). No. of bitstreams: 1 RodriguezMelo_Juanita_M.pdf: 7821554 bytes, checksum: 5ad2b10d82bc051c55f839d303453afd (MD5) Previous issue date: 2014 / Resumo: O objetivo principal deste trabalho foi avaliar o potencial prospectivo para ouro e metais associados de uma área localizada no norte do Cinturão de Maricunga, Chile. Análises por espectroscopia de reflectância foram obtidas na área do prospecto Salares Norte possibilitando o reconhecimento de assembléias de alteração hidrotermal incluindo minerais como caulinita, esmectita, alunita, ilita e minerais portadores de sílica. A presença destes minerais foi conferida por análise petrográfica e de microscópio eletrônico de varredora (MEV). A análise da distribuição espacial desses minerais foi determinada aplicando as seguintes técnicas de processamento digital a uma cena do sensor Terra/ASTER: Análise por Principais Componentes (APC), Spectral Angle Mapper (SAM) e Mixed Tuned Matched Filter (MTMF). A exatidão de cada um dos mapas foi avaliada tomando como referência os dados de espectroscopia de reflectância. O resultado indicou a APC como a técnica mais acurada para o mapeamento de minerais de alteração hidrotermal, com uma exatidão total de 44,34%. Embora este valor de exatidão seja relativamente baixo, os dados de menor acurácia encontram-se nas regiões onde não é reconhecida alteração e os de maior acurácia concentram-se nas áreas alteradas e, por conseguinte, as de maior interesse. Combinando a informação espectro-mineralógica à interpretação de dados geoquímicos (ICP-MS) e litológicos, foi possível concluir que as assembléias minerais de alteração em Salares Norte se formaram sob condições epitermais de alta sulfetação, com atual exposição, marcada por baixo nível de erosão. Os tipos de alteração identificados foram argílica (caulinita±esmectita), argílica avançada (quartzo+alunita+caulinita) e alteração com sílica no núcleo do sistema. Alteração tardia do tipo steam-heated foi reconhecida em uma ampla área, sendo que quase em toda a sua extensão se encontra sobreposta às alterações argílica avançada e silícica. As zonas de alteração exibem uma evidente tendência estrutural de direção NW-SE coincidente com a disposição de anomalias geoquímicas de Au, Ag e Hg. Por essa razão, este componente estrutural NW-SE se destaca como possível controle da alteração/mineralização em Salares Norte. Dentre as unidades litológicas identificadas no prospecto, uma brecha freato-magmática destaca-se como provável portadora/concentradora da mineralização, pois nela se encontraram as maiores anomalias de Au, Ag e Hg. Regionalmente, foram identificadas outras áreas de alteração situadas fora dos perímetros do prospecto Salares Norte, usando-se a técnica APC (Técnica Crósta) numa imagem ETM+ do satélite Landsat-7, e na imagem do sensor ASTER. Os resultados obtidos indicam ocorrências de zonas de alteração hidrotermal em áreas próximas a Salares Norte, com similaridades quanto ao tipo de assembléia mineral hidrotermal e controle estrutural, indicando estas áreas como alvos potenciais para mineralização de ouro e outros metais nesta região / Abstract: The main objective of the project was to evaluate the prospectivity potential for gold and associated metals of an area located in the northern part of the Maricunga Belt, Chile. Reflectance spectroscopy was used in the region of the Salares Norte Prospect to identify hydrothermal alteration mineral assemblages comprising kaolinite, smectite, alunite, illite and silica-bearing minerals. The presence of these minerals was confirmed by petrographic and electronic microscope (SEM) analyses. The spatial distribution of these minerals was determined by applying the following digital processing techniques to a Terra/ASTER scene: Principal Component Analysis (APC), Spectral Angle Mapper (SAM) and Mixed Tuned Matched Filter (MTMF). The accuracy of each resulting map was calculated, using as reference reflectance spectroscopy data obtained. The result showed APC as the most accurate technique with an overall accuracy of 44.34%. Although this value is relatively low, the less accurate data were found in regions with no alteration, whereas higher accuracy values were spatially related to altered regions, thus the ones with more interest. The spectral-mineralogical information was used together with geochemical (ICP-MS) and lithological data to analyze alteration assemblages in Salares Norte, showing that they were formed under epithermal conditions, most specifically in a high sulfidation environment, which currently shows a shallow erosion level. The alteration types identified in the prospect were argillic (kaolinite±smectite), advanced argillic (quartz+alunite+kaolinite) and siliceous in the core of the system. A late steam-heated alteration was recognized in a broad area, overprinting the advanced argillic and siliceous alteration in almost all its extension. The alteration zones exhibit an evident structural trend along NW-SE that coincides with Au, Ag and Hg geochemical anomalies. For this reason, the directional structural component appears to have acted as a possible alteration/mineralization control in Salares Norte. Within the lithological units identified in the prospect, a phreatomagmatic breccia stands out as a probable carrier/concentrator of mineralization, since the higher Au, Ag and Hg geochemical anomalies are associated with this unit. Other hydrothermally altered areas were identified in the region surrounding Salares Norte prospect using the APC technique (Crósta Technique) on an Landsat-7/ETM+ image, and also on an ASTER image, depicting similar aspects regarding the type of alteration assemblage and structural control, indicating these areas as potential targets for gold and other metals / Mestrado / Geologia e Recursos Naturais / Mestra em Geociências

Orientador: Inés Joekes / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-25T11:57:45Z (GMT). No. of bitstreams: 1 Alves_ScheilaDaianaFausto_M.pdf: 2196472 bytes, checksum: c6f04b6d2db3f6b1a2f50a2fabb1e67f (MD5) Previous issue date: 2013 / Resumo: Os cabelos tingidos, como é de conhecimento comum, desbotam com o passar do tempo. Estudos mostram que tanto cabelos naturais quanto tingidos apresentam desbotamento quando expostos à radiação ultravioleta, e este mesmo fenômeno também é observado em outras fibras naturais. Além disso, o processo de lavagem tem grande influência nesta perda de cor. No entanto, há poucos estudos que combinem os efeitos da radiação ao de tensoativos, utilizados no processo de lavagem. Neste trabalho, estudamos a permanência da cor em cabelos Caucasianos tingidos frente à exposição à radiação UV-Vis e a três diferentes tensoativos, coco glucosídeo, cocoil sarcosinato de sódio e coco sulfato de sódio, de mesma cadeia apolar e diferente grupo polar. Cabelos castanhos foram oxidados antes do tingimento. Cabelos loiros foram tingidos sem oxidação prévia. Cabelos castanhos e loiros sem tingir foram usados como controles. Foram simulados danos diários por meio de irradiação em lâmpada de vapor de mercúrio e lavagens, em 30 ciclos sequenciais de 8 h de irradiação e uma lavagem. As diferenças de cor foram medidas por espectrofotometria de reflectância difusa.. Foram obtidos espectros no UV-Vis das soluções de lavagem com os diferentes tensoativos. Como esperado, todas as mechas, naturais e tingidas, apresentaram diferença de cor. No caso das mechas sem tingir, os espectros das soluções de lavagem correspondem aos das melaninas. No caso das mechas tingidas, as soluções de lavagem têm o mesmo perfil de absorbância que as soluções de tintura. As mechas oxidadas e tingidas desbotaram mais que as que foram apenas tingidas. Observou-se diferença entre o efeito dos tensoativos apenas nas mechas que foram tingidas. Tanto para o cabelo castanho oxidado e tingido quanto para o cabelo loiro tingido, a ordem de extração do pigmento é: coco sulfato de sódio > cocoil sarcosinato de sódio > coco glucosídeo, concordando com o respectivo índice HLB / Abstract: It is well known that dyed hair fades with time. There are studies showing that dyed and natural hair, besides other natural fibers, have their color lightened when exposed to ultraviolet radiation. Futhermore, shamppoing has a big effect on this color lightening. However, there are few studies combining the effects of radiation and surfactants. In this work, we studied the color durability in dyed Caucasian hair when exposed to radiation and three surfactants, coco glucoside, sodium cocoyl sarcosinate and sodium coco sulfate, with same carbonic chain and different polar groups. Brown hair was chemically bleached before dyeing and blond hair was dyed without previous oxidation. Brown and blond hair with no dyeing was used as control. Simulation of diary damages was done by a mercury vapor lamp and washing cycles, in 30 sequential cycles of 8 h of irradiation and one shampooing. Color changes were measured by diffuse reflectance spectroscopy (DRS), using CIELab system. UV-Vis spectra were obtained from washing solutions with the different surfactants. All tresses, natural and dyed, showed color changes. UV-Vis spectra of the washing solutions of the hair without dyeing are consistent with melanin spectra. Dyed hair washing solutions spectra have the same profile of the dye solutions. The chemically bleached and dyed tresses faded more than the only dyed ones. Differences among the surfactants were observed only in the dyed tresses The pigment removal order for both, oxidized and dyed and only dyed tresses is: sodium coco sulfate > sodium cocoyl sarcosinate > coco glucoside, agreeing with their HLB index / Mestrado / Físico-Química / Mestra em Química

In recent decades, the rapid development of optical spectroscopy for tissue diagnosis has been indicative of its high clinical value. The goal of this research is to prove the feasibility of using diffuse reflectance spectroscopy and fluorescence spectroscopy to assess myocardial infarction (MI) in vivo. The proposed optical technique was designed to be an intra-operative guidance tool that can provide useful information about the condition of an infarct for surgeons and researchers. In order to gain insight into the pathophysiological characteristics of an infarct, two novel spectral analysis algorithms were developed to interpret diffuse reflectance spectra. The algorithms were developed based on the unique absorption properties of hemoglobin for the purpose of retrieving regional hemoglobin oxygenation saturation and concentration data in tissue from diffuse reflectance spectra. The algorithms were evaluated and validated using simulated data and actual experimental data. Finally, the hypothesis of the study was validated using a rabbit model of MI. The mechanism by which the MI was induced was the ligation of a major coronary artery of the left ventricle. Three to four weeks after the MI was induced, the extent of myocardial tissue injury and the evolution of the wound healing process were investigated using the proposed spectroscopic methodology as well as histology. The correlations between spectral alterations and histopathological features of the MI were analyzed statistically. The results of this PhD study demonstrate the applicability of the proposed optical methodology for assessing myocardial tissue damage induced by MI in vivo. The results of the spectral analysis suggest that connective tissue proliferation induced by MI significantly alter the characteristics of diffuse reflectance and fluorescence spectra. The magnitudes of the alterations could be quantitatively related to the severity and extensiveness of connective tissue proliferation.

Orientadores: Alvaro Penteado Crósta, Catarina Labouré Bemfica Toledo, Adalene Moreira Silva / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-27T00:13:09Z (GMT). No. of bitstreams: 1 Carrino_ThaisAndressa_D.pdf: 37700269 bytes, checksum: 1032551af9407d69e558467ba552091e (MD5) Previous issue date: 2015 / Resumo: O sul do Peru contém importantes depósitos epitermais de Au-Ag (±metais base) de pequeno a médio porte, associados com a orogenia Andina do Mioceno-Plioceno. Uma análise sinóptica da região abrangendo os alvos Chapi Chiara, Cerro Millo, San Antonio de Esquilache e Cerro Chucapaca ¿ localizados em distintos paleoestratovulcões¿, foi feita via processamento e análise de imagem do sensor ASTER. Todos estes alvos são caracterizados por extensas zonas de alteração argílica avançada (alunita-caulinita) (AAA), à exceção de San Antonio de Esquilache, cuja alteração argílica (AA) (esmectita/ilita) e argílica avançada se restringe a intrusões dioríticas aflorantes. Diferentemente, o depósito epitermal de sulfetação intermediária Canahuire (Au-(Cu, Ag)) foi discriminado por extensos afloramentos NW-SE de rochas quartzosas (Grupo Yura/Juro-Cretáceo), e rochas carbonáticas (Formação Gramadal/Grupo Yura) e brechas freáticas e freatomagmáticas pobres em sílica que hospedam a mineralização. Modelo de favorabilidade para depósitos "tipo-Canahuire" foi produzido a partir da integração dos produtos ASTER usando-se a lógica fuzzy. Estudo de detalhe foi realizado no prospecto Chapi Chiara usando-se petrografia, geoquímica, espectroscopia de reflectância, dados de susceptibilidade magnética (SM), imagens da amplitude do sinal analítico e da primeira derivada vertical do campo magnético anômalo, além do processamento de imagens do sensor HyMap. As principais rochas vulcânicas amostradas compreendem andesito porfirítico (SM ~28×10-3 SI), tufo e lapilli tufo de composição riolítica (SM~0). O setor SW do prospecto é caracterizado por três subáreas com extensa AAA, marcadas por quartzo, K-alunita, alunita intermediária, Na-alunita, caulinita, dickita (±topázio, ±huangita, ± minerais APS, ±pirofilita, ±diásporo, ±rutilo) (SM ~0 a ~0,15×10-3 SI). Restritas zonas de AA (quartzo, ilita ± , ilita paragonítica ± , esmectita, ±pirita, ±rutilo) (SM ~0,01×10-3 SI) e de alteração propilítica (clorita, quartzo, calcita, epidoto, esmectita, ±caulinita, ±pirita, ± calcopirita, ± titanomagnetita e magnetita)) (SM ~3,45×10-3 a ~36,03 × 10-3 SI) ocorrem em setores distais. O setor central é marcado por brechas hidrotermais métricas/decamétricas com SM ~0 a 0,01×10-3 SI, compostas de fragmentos de rochas ricos em quartzo vuggy. Há considerável concentração de pirita e forte associação geoquímica de Au, Ag, As, Bi, Hg, Se, Sb, e Te. Os principais minerais supergênicos compreendem jarosita e goethita. As assembléias minerais hipógenas acima mencionadas revelam a existência de um sistema epitermal de alta sulfetação similar ao do prospecto aurífero Cerro Millo e aos dos depósitos auríferos Tucari e Santa Rosa, permitindo a inferência de idade relativa do paleoestratovulcão e da concomitante atividade hidrotermal em Chapi Chiara entre ~11 e ~4 Ma. Intenso processo de lixiviação magmático-hidrotermal visto nas zonas de AAA e AA paramagnéticas e diamagnéticas gerou duas extensas zonas desmagnetizadas NW-SE, compatíveis com o sistema de falhas regionais Condoroma-Caylloma. Estruturas de menor magnitude também aparecem (e.g., NE-SW, E-W). Embora estes trends sejam interessantes vetores exploratórios, a exposição de minerais formados em condições de maior temperatura (e.g., alunita+topázio, alunita+dickita+pirofilita, diásporo, alunita intermediária no setor SW), sugere tratar-se de núcleos mais erodidos, reduzindo-se o potencial de mineralização local, e/ou indicando a proximidade do limite de transição do domínio epitermal para um mesotermal em profundidade, com a possível existência de intrusão(ões) diorítica(s) próxima(s) à superfície do prospecto, similarmente ao que já é observado no alvo análogo de San Antonio de Esquilache / Abstract: Southern Peru contains important small- to medium-sized Au-Ag (± base metals) epithermal deposits, associated with the Miocene-Pliocene Andean orogeny. A synoptic analysis of the region covering the Chapi Chiara, Cerro Millo, San Antonio de Esquilache and Cerro Chucapaca targets ¿ each one located in distinct paleostratovolcanoes ¿ was done through the processing and analysis of ASTER data. These targets are characterized by extensive advanced argillic alteration zones, except San Antonio de Esquilache, that is marked by argillic alteration (AA) (smectite-illite) and advanced argillic alteration (alunite-kaolinite) (AAA) zones restricted to outcropping diorite intrusions. Unlikely, the Canahuire intermediate sulfidation epithermal Au-(Cu, Ag) deposit was discriminated by extensive NW-SE quartz-rich rocks (Yura Group/Juro-Cretaceous), and carbonate rocks (Gramadal Formation/Yura Group) and silica-poor phreatic and phreatomagmatic breccias that host the mineralization. Favorability model for "Canahuire-type" deposits was created through the integration of ASTER data using the fuzzy logic technique. A detailed study was conducted at Chapi Chiara prospect through petrography, geochemistry, reflectance spectroscopy, magnetic susceptibility (MS), images of the amplitude of analytic signal and of first vertical derivative of the anomalous magnetic field, besides the processing of HyMap hyperspectral remote sensing data. The main sampled volcanic rocks comprise porphyritic andesite (MS ~28×10-3 SI), and rhyolitic tuff and lapilli tuf (MS~0). The SW sector of the prospect is characterized by three sub-areas with extensive AAA zones, marked by quartz, K-alunite, intermediate alunite, Na-alunite, kaolinite, dickite (±topaz, ±huangite, ±APS minerals, ±pyrophyllite, ±diaspore, ±rutile) (MS ~0 to ~0,15×10-3 SI). Restricted AA zones (quartz, illite ± , paragonitic illite ± , smectite, ±pyrite, ±rutile) (MS ~0,01×10-3 SI), and of propylitic alteration (chlorite, quartz, calcite, epidote, smectite, ±kaolinite, ±pyrite, ±chalcopyrite, ±titanomagnetite and magnetite)) (MS ~3,45×10-3 to ~36,03×10-3 SI) occur in distal sectors. The central sector is marked by metric/decametric hydrothermal breccias with MS ~0 to 0,01×10-3 SI, composed of vuggy quartz-rich fragments. There is a considerable concentration of pyrite and strong geochemical association of Au, Ag, As, Bi, Hg, Se, Sb, e Te. The main supergene minerals comprise jarosite and goethite. The above mentioned hypogene mineral assemblages reveal a high sulfidation epithermal system similar to the Cerro Millo gold prospect and to Tucari and Santa Rosa gold deposits, allowing to infer a relative age between ~11 and ~4 Ma for the paleoestratovolcano and the concomitant hydrothermal activity in Chapi Chiara. Intense magmatic-hydrotermal leaching seen in the paramagnetic and diamagnetic AAA and AA zones generated two NW-SE extensive demagnetized zones, compatible with the regional Condoroma-Caylloma fault system. Smaller structures also occur (e.g., NE-SW, E-W). Although these trends are interesting exploration vectors, the exposure of minerals formed at higher temperature (e.g., alunite+topaz, alunite+dickite+pyrophyllite, diaspore, intermediate alunite in the SW sector), suggest possible eroded cores, reducing the local potential for mineralization, and/or indicating the proximity of the limit between epithermal and mesothermal domains in depth. In addition, there is a possible proximity of dioritic intrusion(s) near the surface of the prospect, similarly to the currently exposed intrusions at the surface in the analogous target of San Antonio de Esquilache / Doutorado / Geologia e Recursos Naturais / Doutora em Ciências

The use of lasers for diagnosis and treatment in medical and cosmetic applications is increasing worldwide. Not all of these modalities are superficial and many require laser light to penetrate some distance into the tissue or skin to reach the treatment site. Human skin is highly scattering for light in the visible and near infrared wavelength regions, with a consequent reduction of the fluence rate. Melanin, which occurs in the epidermis of the skin, acts as an absorber in these wavelength regions and further reduces the fluence rate of light that penetrates through the epidermis to a treatment site. In vivo fluence rate measurements are not viable, but validated and calibrated computer models may play a role in predicting the fluence rate reaching the treatment site. A layered planar computer model to predict laser fluence rate at some depth into skin was developed in a commercial raytracing environment (ASAP). The model describes the properties of various skin layers and accounts for both the absorption and scattering taking place in the skin. The model was validated with optical measurements on skin-simulating phantoms in both reflectance and transmission configurations. It was shown that a planar epidermal/dermal interface is adequate for simulation purposes. In the near infrared wavelength region (676 nm), melanin (consisting of eumelanin and pheomelanin) is the major absorber of light in the epidermis. The epidermal absorption coefficient is one of the required input parameters for the computer model. The range of absorption coefficients expected for typical South African skin phototypes (ranging from photo-sensitive light skin, phototype I on the Fitzpatrick scale, to the photo-insensitive darker skin phototype V) was not available. Non-invasive diffuse reflectance spectroscopy measurements were done on 30 volunteers to establish the expected range of absorption coefficients. In the analysis it became apparent that the contributions of the eumelanin and pheomelanin must be accounted for separately, specifically for the Asian volunteers. This is a new concept that was introduced in the diffuse reflectance probe analysis. These absorption coefficient measurements were the first to be done on the expected range of skin phototypes for the South African population. Other authors dealing with diffuse reflectance probe analysis only account for the dominant eumelanin. Both the epidermal absorption coefficient and thickness are important in the prediction of the fluence rate loss. The computer model was used to evaluate the effect of the epidermal absorption coefficient (a parameter dictated by an individual’s skin phototype) and the epidermal thickness on the fluence rate loss through the skin. The epidermal absorption is strongly wavelength dependent with the higher absorption at the shorter wavelengths. In the computer model a longer wavelength of 676 nm (typical for a photodynamic treatment (PDT) of cancer) was used. For the darker skin phototypes (V) only about 30% of the initial laser fluence rate reached a depth of 200 ìm into the skin (just into the dermis). For the PDT application, results from the computer model indicated that treatment times need to be increased by as much as 50% for very dark skin phototypes when compared to that of very light phototypes. / Thesis (PhD)--University of Pretoria, 2012. / Physics / unrestricted

Near infrared spectroscopy (NIR) has become increasingly widespread throughout various fields as an alternative method for efficiently phenotyping crops and plants at rates unparalleled by conventional means. With growing reliability, the convergence of NIR spectroscopy and modern machine learning represent a promising methodology offering unprecedented access to rapid, high throughput phenotyping at negligible costs, representing prospects that excite agronomists and plant physiologists alike. However, as is true of all emergent methodologies, progressive refinement towards optimization exposes potential flaws and raises questions, one of which is the cornerstone of this study. Spectroscopic determination of plant functional traits utilizes plants' morphological and biochemical properties to make predictions, and has been validated at the community (inter-family) and individual crop (intraspecific) levels alike, yielding equally reliable predictions at both scales, yet what lies amid these poles on the spectrum of taxonomic scale remains unexplored territory. In this study, we replicated the protocol used in studies of the aforementioned taxonomic scale extremes and applied it to an intermediate scale. Interestingly, we found that predictive models built upon hyperspectral reflectance data collected across three genera of woody plants: Cornus, Rhododendron, and Salix, yielded inconsistent predictions of varying accuracy within and across taxa. Identifying the potential cause(s) underlying variability in predictive power at this intermediate taxonomic scale may reveal novel properties of the methodology, potentially permitting further optimization through careful consideration.

No description available.

Ammonium has been detected in and around several epithermal Au-Ag deposits, including those in Nevada, Japan, Argentina, Mexico, and New Zealand, using short-wave infrared (SWIR) reflectance spectroscopy. This study examined the distribution and occurrence of ammonium in three epithermal low-sulfidation vein-type deposits in the Hauraki goldfield of New Zealand: Martha (>6.7Moz Au, >42.1Moz Ag), Favona (>0.6Moz Au, >2.36Moz Ag), and the recently discovered Wharekirauponga (WKP; 0.42Moz Au, 0.8Moz Ag) deposit. The Martha and Favona auriferous quartz-adularia veins are hosted by late Miocene to Pliocene andesite, whereas auriferous veins at WKP are hosted by late Miocene to Pliocene rhyolite. The wallrock of all three deposits is altered to form quartz, illite, smectite, adularia, chlorite, and pyrite +/- kaolinite. Ammonium contents are enriched (>137 ppm) in wallrock samples from all three deposits and low (<94 ppm) in vein samples. Ammonium contents are higher at Favona (<10,675 ppm) than at Martha (<192 ppm) and WKP (<2,783 ppm). Leaching experiments using a 2N KCl solution show that most ammonium is in mineral structures (>90% at Favona, >80% at Martha, >70% at WKP). There is a positive correlation of ammonium contents with LOI (0.6 – 16.3 wt%) and with K2O (1.3 – 8.0 wt%) in all samples which suggest a hydrous potassium mineral as the major host of the ammonium. This is supported by the SWIR data obtained by previous workers of these samples where they show an absorption at ~1410 nm due to OH. At Favona, samples with high ammonium (>990 ppm) are reported to have significant absorption at ~2000 nm and ~2100 nm in the SWIR spectra likely due to ammonium. High ammonium contents (990 – 10,675 ppm) are found in rocks less than ~100m from the Favona vein which occur within an ammonium-bearing zone identified by previous workers based on SWIR. Samples outside of this zone contain low ammonium (107 – 301 ppm) with the smectite altered samples being the lowest. Ammonium contents within the hangingwall (1,827 – 10,675 ppm) of the Favona vein tend to be higher than in the footwall (990 – 4,301 ppm) and are highest within the most intensely illite altered rocks. At WKP, the intensely adularia +/- minor illite altered samples within 100m of the main East-Graben (EG) vein contain low ammonium (<200 ppm). The intensely illite altered samples away from the EG vein (>100m) have higher ammonium contents (200 – 800 ppm). This relationship of high ammonium contents to high illite abundance confirms illite as the major host of ammonium in these deposits. δ15N values for all samples (n=54) including near and far from auriferous veins range from +0.5 to +7.9 ‰, suggesting the derivation of most of the ammonium from the Jurassic greywacke basement or sediments intercalated within the volcanic rocks.

Biomedical optics is a rapidly expanding field of research focusing on the development of methods to detect, diagnose, and treat disease using light. While there are a myriad of optical systems that have been developed for biological tissue imaging, optical diagnostics, and optical therapeutics, all of these methods suffer severely limited penetration depths due to attenuation of light by tissue constituent chromophores, including cells, water, blood, and protein structures. Tissue optical clearing is a recent area of study within biomedical optics and photonics, where chemical agents have been used to alter tissue optical properties, reducing optical absorption and scattering and enabling light delivery to and collection from deeper tissue regions. However, there are concerns as to the safety and efficacy of these chemical clearing agents in vivo, especially in the skin, where the projective barrier function of the stratum corneum must be removed. Mechanical optical clearing is a recently developed technology which utilizes mechanical loading to reversibly modify light transport through soft tissues, and much of the work published on this technique has focused on applications in skin tissue. This clearing technique enables deeper light delivery into soft tissues but does not require use of exogenous chemicals, nor does it compromise the skin barrier function. While this clearing effect is thought to be resultant from interstitial water and blood transport, the underlying mechanism has not been concretely identified nor characterized. The hypothesis of this body of work was that interstitial transport of tissue chromophores (e.g. water and blood) causes intrinsic optical property changes, reduces tissue optical absorption and scattering, and improves light delivery in diagnostic applications. To test this hypothesis, we first developed a mathematical framework to simulate mechanical optical clearing, using both mechanical finite element models and optical Monte Carlo simulations. By directly simulating interstitial water transport in response to loading, data from mechanical simulations was combined with optical Monte Carlo simulations, which enabled prediction of light transmission measurements made during mechanical indentation experiments. We also investigated changes in optical properties during mechanical indentation using diffuse reflectance spectroscopy. These studies used controlled flat indentation by a fiberoptic probe to dynamically measure intrinsic optical properties as they changed over time. Finally, we apply mechanical optical clearing principles to functional near-infrared spectroscopy for neuroimaging. By building a prototypical mechanical optical clearing device for measuring cerebral hemodynamics, we demonstrated that mechanical optical clearing devices modify measured cerebral hemodynamic signals in human subjects, improving signal quality. / Ph. D.

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