No / The minerals involved in the formation of metazoan skeletons principally comprise glassy silica, calcium phosphate or carbonate. Because of their ancient heritage, glass sponges (Hexactinellida) may shed light on fundamental questions such as molecular evolution, the unique chemistry and formation of the first skeletal silica-based structures, and the origin of multicellular animals. We have studied anchoring spicules from the metre-long stalk of the glass rope sponge (Hyalonema sieboldi; Porifera, Class Hexactinellida), which are remarkable for their size, durability, flexibility and optical properties. Using slow-alkali etching of biosilica, we isolated the organic fraction, which was revealed to be dominated by a hydroxylated fibrillar collagen that contains an unusual [Gly-3Hyp-4Hyp] motif. We speculate that this motif is predisposed for silica precipitation, and provides a novel template for biosilicification in nature.

No / The use of nanoparticles have provided numerous of advantages in medicine due to their unique physiochemical characteristics such as size, charge, shape and surface reactivity [1-4]. Understanding the interaction between engineered nanomaterials and living matter has attracted increasing attention in recent years. Toxicity of nanoparticles was studied in different cell types and cell lines. Nano-SiO2 has good stability, easy dispensability, and melting degeneration, and is widely used in rubber, paints, biomedical and biotechnology fields [5]. In this study, the LDH assay and the MTT assay were applied to evaluate the cytotoxicity of in vitro Silicon dioxide nanoparticles (SiO2-NP, 20nm) on cultured cell lines. Human lung adenocarcinoma epithelial cell line (A549) were used as a lung related cell line and human keratinocyte cell line (HaCaT) as a skin related cell line representing different uptake routes. The percentage cytotoxicity of the silicon dioxide nanoparticles was measured once cultured in a 24 hour incubation period. The concentration of the SiO2 nanoparticles chosen was 10, 50, 100 and 200µg/ml. To measure the cytotoxicity of nanoparticle on cultured cell lines, we used 104*cells/100 µl of cell culture media being placed in a 96 well rounded bottom plate with the LDH assay. The extracellular lactate dehydrogenase release was measured by using a colorimetric CytoTox 96 non-radioactive assay kit and the absorbance was recorded at 492nm. The MTT assay was used to evaluate mitochondrial activity which includes cell growth and cell death. This has been performed by inserting a premixed optimized dye solution in the culture wells. The Absorbance was recorded at 570 nm, from the recorded absorbance is directly proportional to the number of live cells. In order to maintain the cell lines, they were placed in a plastic T-75cm² tissue culture flasks grown in Dulbecco's Modified Eagle's Medium. Studies were performed in the absence of serum. Cytotoxicity was found in both cells the A549 and HaCaT cells and cytotoxicity increased as concentration of the silicon dioxide increased. The percentage cytotoxicity calculated was higher in HaCaT cells compared to the A549 cells. A cell count assay was plated in order to display the cell number of both the HaCaT and A549 cells. The cell count reaffirmed that cytotoxicity did occur as the cell count decreased as the concentration of the silicon dioxide increased compared to the control. These results show that silicon dioxide nanoparticles acted differently in two different cell types and that the metabolic rate of a cell can be used to determine the nanoparticles affect. Further understanding of the mechanism involving the ROS generation could provide more information on how silicon dioxide nanoparticles increase cytotoxicity. / Physiology 2015 conference abstract

Heterogeneous reactions between mineral dust aerosols and gas phase volatile organic compounds have the potential to impact important atmospheric chemical processes. However, little is known about the uptake and reactivity of volatile organic compounds on particulates found in the environment. A Knudsen cell was designed and constructed for providing precise measurement of reaction probabilities within these systems. The instrument was validated through a series of experiments. After validating the Knudsen cell against several key benchmarks, the instrument was used to measure the uptake coefficient for ethanol on particulate silicon dioxide. The uptake coefficient of ethanol on silicon dioxide, a common compound in mineral dust aerosols, was determined to be 7 x 10-7. Therefore, uptake of ethanol on silicon dioxide would be competitive with the loss of other volatile organic compounds on silicon dioxide, which show similar rates of uptake. The Knudsen cell was validated and measured the uptake of ethanol on silicon dioxide, and future work with the Knudsen cell will study the uptake of chemical warfare agent simulants on metal oxides. / Master of Science

Metal oxide and metal oxide-supported metal nanoparticles can adsorb and decompose chemical warfare agents (CWAs) and their simulants. Nanoparticle activity depends on several factors including chemical composition, particle size, and support, resulting in a vast number of materials with potential applications in CWA decontamination. Current instrumentation in our laboratory used to investigate fundamental gas-surface interactions require extensive time and effort to achieve operating conditions. This thesis describes the design and construction of a high-throughput, high vacuum surface analysis instrument capable of studying interactions between CWA simulants and nanoparticulate surfaces. The new instrument is small, relatively inexpensive, and easy to use, allowing for expeditious investigations of fundamental interactions between gasses and nanoparticulate samples. The instrument maintains the sample under high vacuum (10?⁷-10?⁹ torr) and can reach operating pressures in less than one hour. Thermal control of the sample from 150-800 K enables sample cleaning and thermal desorption experiments. Infrared spectroscopic and mass spectrometric methods are used concurrently to study gas-surface interactions. Temperature programmed desorption is used to estimate binding strength of adsorbed species. Initial studies were conducted to assess the performance of the instrument and to investigate interactions between the CWA simulant dimethyl methylphosphonate (DMMP) and nanoparticulate silicon dioxide. / Master of Science

O presente trabalho teve como objetivo verificar a influência dos parâmetros tecnológicos do processo de secagem por aspersão sobre as características do produto obtido a partir de extrato seco de Maytenus ilicifolia. Para tanto, foi realizado um estudo exploratório, utilizado um desenho experimental fatorial, analisando quatro parâmetros: a concentração de dióxido de silício coloidal (10 e 30 %), o tempo de dispersão em meio líquido das matérias-primas (0,5 e 4 horas), a temperatura de entrada do ar de secagem na torre de aspersão (150 e 180 ºC), e a velocidade de rotação do disco aspersor (9.500 e 11.000 rpm). O teor de umidade residual, a morfologia, a distribuição granulométrica e o fluxo dos pós obtidos, assim como o rendimento do processo e a concentração do marcador catequina foram considerados como respostas ao desenho fatorial. O aumento da temperatura de entrada conduziu a produtos com umidade reduzida e a maior eficiência do processo. A concentração do dióxido de silício coloidal afetou principalmente as propriedades de fluxo e o teor de catequina nos pós produzidos. A maior velocidade de rotação influenciou de modo positivo somente sobre o rendimento do processo. / The present study aimed to evaluate the influence of technological parameters related to the spray drying process over the product obtained from a Maytenus ilicifolia spray dried extract. Therefore, an exploratory study was carried out using an experimental factorial design assessing four parameters: colloidal silicon dioxide concentration (10 – 30 %), dispersion time of the feed material (0.5 – 4 h), air inlet temperature in the spray dryer (150 – 180 ºC), and atomizer speed (9,500 – 11,000 rpm). According to an experimental factorial design four parameters were assessed: colloidal silicon dioxide concentration (10 – 30 %), mixing time (0.5 – 4 h), inlet temperature (150 – 180 ºC), and atomizer speed (9,500 – 11,000 rpm). Moisture content, morphology, particle size, flow, process yield and catechin concentration were considered as responses of the factorial design. Increasing inlet temperature led to dried products with reduced moisture content and higher process yield. Aerosil content mainly affected flow properties and catechin content in the powders. Atomizer speed at high level only enhanced process yield.

O presente trabalho teve como objetivo verificar a influência dos parâmetros tecnológicos do processo de secagem por aspersão sobre as características do produto obtido a partir de extrato seco de Maytenus ilicifolia. Para tanto, foi realizado um estudo exploratório, utilizado um desenho experimental fatorial, analisando quatro parâmetros: a concentração de dióxido de silício coloidal (10 e 30 %), o tempo de dispersão em meio líquido das matérias-primas (0,5 e 4 horas), a temperatura de entrada do ar de secagem na torre de aspersão (150 e 180 ºC), e a velocidade de rotação do disco aspersor (9.500 e 11.000 rpm). O teor de umidade residual, a morfologia, a distribuição granulométrica e o fluxo dos pós obtidos, assim como o rendimento do processo e a concentração do marcador catequina foram considerados como respostas ao desenho fatorial. O aumento da temperatura de entrada conduziu a produtos com umidade reduzida e a maior eficiência do processo. A concentração do dióxido de silício coloidal afetou principalmente as propriedades de fluxo e o teor de catequina nos pós produzidos. A maior velocidade de rotação influenciou de modo positivo somente sobre o rendimento do processo. / The present study aimed to evaluate the influence of technological parameters related to the spray drying process over the product obtained from a Maytenus ilicifolia spray dried extract. Therefore, an exploratory study was carried out using an experimental factorial design assessing four parameters: colloidal silicon dioxide concentration (10 – 30 %), dispersion time of the feed material (0.5 – 4 h), air inlet temperature in the spray dryer (150 – 180 ºC), and atomizer speed (9,500 – 11,000 rpm). According to an experimental factorial design four parameters were assessed: colloidal silicon dioxide concentration (10 – 30 %), mixing time (0.5 – 4 h), inlet temperature (150 – 180 ºC), and atomizer speed (9,500 – 11,000 rpm). Moisture content, morphology, particle size, flow, process yield and catechin concentration were considered as responses of the factorial design. Increasing inlet temperature led to dried products with reduced moisture content and higher process yield. Aerosil content mainly affected flow properties and catechin content in the powders. Atomizer speed at high level only enhanced process yield.

O presente trabalho teve como objetivo verificar a influência dos parâmetros tecnológicos do processo de secagem por aspersão sobre as características do produto obtido a partir de extrato seco de Maytenus ilicifolia. Para tanto, foi realizado um estudo exploratório, utilizado um desenho experimental fatorial, analisando quatro parâmetros: a concentração de dióxido de silício coloidal (10 e 30 %), o tempo de dispersão em meio líquido das matérias-primas (0,5 e 4 horas), a temperatura de entrada do ar de secagem na torre de aspersão (150 e 180 ºC), e a velocidade de rotação do disco aspersor (9.500 e 11.000 rpm). O teor de umidade residual, a morfologia, a distribuição granulométrica e o fluxo dos pós obtidos, assim como o rendimento do processo e a concentração do marcador catequina foram considerados como respostas ao desenho fatorial. O aumento da temperatura de entrada conduziu a produtos com umidade reduzida e a maior eficiência do processo. A concentração do dióxido de silício coloidal afetou principalmente as propriedades de fluxo e o teor de catequina nos pós produzidos. A maior velocidade de rotação influenciou de modo positivo somente sobre o rendimento do processo. / The present study aimed to evaluate the influence of technological parameters related to the spray drying process over the product obtained from a Maytenus ilicifolia spray dried extract. Therefore, an exploratory study was carried out using an experimental factorial design assessing four parameters: colloidal silicon dioxide concentration (10 – 30 %), dispersion time of the feed material (0.5 – 4 h), air inlet temperature in the spray dryer (150 – 180 ºC), and atomizer speed (9,500 – 11,000 rpm). According to an experimental factorial design four parameters were assessed: colloidal silicon dioxide concentration (10 – 30 %), mixing time (0.5 – 4 h), inlet temperature (150 – 180 ºC), and atomizer speed (9,500 – 11,000 rpm). Moisture content, morphology, particle size, flow, process yield and catechin concentration were considered as responses of the factorial design. Increasing inlet temperature led to dried products with reduced moisture content and higher process yield. Aerosil content mainly affected flow properties and catechin content in the powders. Atomizer speed at high level only enhanced process yield.

Doctor of Philosophy / Department of Chemistry / Kenneth J. Klabunde / Solar energy driven catalytic systems have gained popularity in environmental remediation recently. Various photocatalytic systems have been reported in this regard and most of the photocatalysts are based on well-known semiconducting material, Titanium Dioxide, while some are based on other materials such as Silicon Dioxide and various Zeolites. However, in titania based photocatalysts, titania is actively involved in the catalytic mechanism by absorbing light and generating exitons. Because of this vast popularity of titania in the field of photocatalysis it is believed that photocatalysis mainly occurs via non-localized mechanisms and semiconductors are extremely important. Even though it is still rare, photocatalysis could be localized and possible without use of a semiconductor as well. Thus, to support localized photocatalytic systems, and to compare the activity to titania based systems, degradation of organic air pollutants by nanostructured silica, titania and mixed silica titania systems were studied. New materials were prepared using two different approaches, precipitation technique (xerogel) and aerogel preparation technique. The prepared xerogel samples were doped with both metal (silver) and non-metals (carbon and sulfur) and aerogel samples were loaded with Chromium, Cobalt and Vanadium separately, in order to achieve visible light photocatalytic activity. Characterization studies of the materials were carried out using Nova BET analysis, DR UV-vis spectrometry, powder X-ray diffraction, X-ray photoelectron Spectroscopy, FT-IR spectroscopy, Transmission Electron Microscopy, etc. Kinetics of the catalytic activities was studied using a Shimadzu GCMS-QP 5000 instrument using a closed glass reactor. All the experiments were carried out in gaseous phase using acetaldehyde as the model pollutant. Kinetic results suggest that chromium doped silica systems are good UV and visible light active photocatalysts. This is a good example for a localized photocatalytic activity. In contrast, our xerogel system shows comparatively high visible light photocatalytic activity for the titania based system, showing the importance of non-localized nature of photocatalysis. The Cobalt doped silica system shows interesting dark catalytic activity towards acetaldehyde and several other pollutants. Thus, in summary, based on the different activities we observed during our studies these materials could be successfully used to improve the quality of both indoor and outdoor air.

A corrosão é um dos problemas mais relevantes que afronta a indústria atual, representa mais de 25% do investimento destinado para reparos ou troca de equipamentos com falhas por problemas do ataque corrosivo. Neste panorama nos últimos anos houve um grande aumento no desenvolvimento de novas tecnologias para proteção das estruturas, por outro lado o aço ABTN 1020 é um dos materiais mais usados na indústria principalmente em ambientes contendo cloreto. A sua utilização não é recomendada pelas altas taxas de corrosão, sendo necessário à adoção de pintura como meio de proteção. Este trabalho investigou a resistência à corrosão de uma pintura em meios contendo cloreto cuja composição da matriz foi resina uretânica (PU) e diferentes cargas a base de SiO2 e ZnO em diversas concentrações, sendo avaliadas mediante técnicas de Impedância Eletroquímica- EIS e de varredura com elétrodo vibratório SVET. Verificou-se que a espectroscopia e SVET também fornecem informação suficiente relativo ao desgaste e a possível ação da corrosão, sendo assim foi evidenciado que pintura com carga a base de SiO2 que tem melhor resistência à corrosão em meios contendo cloreto. Em outra análise quando comparados com a carga de ZnO pintura com irradiação, observou-se que houve um aumento na aderência da pintura ao metal base, fornecendo uniformidade e maior proteção anticorrosiva, assim foram determinados parâmetros que podem aplicações na indústria. / Corrosion is one of the most important problems facing today\'s industry, representing more than 25% of the investment destined for repairs or exchange of equipment with failures due to corrosive attack problems. In this panorama in recent years there has been a great increase in the development of new technologies for protection of structures, on the other hand the steel ABTN 1020 is one of the materials most used in the industry mainly in environments containing chloride. Its use is not recommended due to the high corrosion rates, and it is necessary to adopt painting as a means of protection. This work investigated the corrosion resistance of a paint in chloride-containing media whose urethane resin (PU) composition and different SiO2 and ZnO-based loads were evaluated in various concentrations and evaluated by Electrochemical Impedance-EIS and scanning with vibrating electrode SVET. It was verified that the spectroscopy and SVET also provide sufficient information regarding the wear and the possible action of the corrosion, thus it was evidenced that paint with charge based on SiO2 that has better resistance to corrosion in media containing chloride. In another analysis when compared with the ZnO charge with irradiation paint, it was observed that there was an increase in the adhesion of the paint to the base metal, providing uniformity and greater anticorrosive protection, thus determined parameters that can be applied in the industry.

A spin-cast silicone membrane has been successfully bonded between two injection-molded microstructured plastic discs. This sandwich structure creates a useful platform for mass production of microfluidic systems, provided that the bonds are leakproof. The bonds were achieved by a silicon dioxide coating deposited on the plastic discs by evaporation. This investigation is concerned with the process and the result only, no theory is discussed.