This paper study the influence of surface properties of encapsulated CLC on response time and reflectance via polymerization induced phase separation. The cured polymer layer, which is composed of the mixture of EMA and TRI, adhere to the inside of the non-treated glass substrate and change the surface properties to vertical alignments. Different boundary conditions caused by various UV curing intensity and cell gap lead to different electro-optical properties for CLC display. With a proper boundary structure, the transition time from homeotropic to planar of CLC can be reduced obviously with slightly reduced reflectance.

South Africa currently has the highest incidence of TB per 100 000 people in the world. In 2007 alone 112 000 people died of TB in South Africa, of which 94 000 were co-infected with HIV. Although TB treatments exist, poor patient compliance and drug resistance are challenges to TB management programs worldwide. Here, this challenge was addressed by the development of a polymeric anti-TB nanodrug delivery system for anti-TB drugs that could enable entry, targeting and sustained release for longer periods, hence reducing the dose frequency and simultaneously improve patient compliance. The aim was to prepare functionalised polymeric nano drug delivery vehicles to target TB infected macrophage cells. Successful nano encapsulation of anti-TB drugs was achieved and uptake of the antibiotics in the cells, demonstrated. A possible targeting agent, mycolic acids (MA) from M. tuberculosis was explored. The MA incorporated into nanoparticles could possibly serve as a ligand for cholesterol-rich areas, due to the cholesteroid nature of MA and the fact that MA is attracted to cholesterol. In another targeting scenario, MA incorporated into nanoparticles may interact with the anti-mycolic acid antibodies that are anticipated to be present in higher concentrations at the infected areas. The cholesteroid nature of MA was confirmed and how it related to the fine structure of the MA. The prepared MA containing nanoparticles were shown in vitro to be taken up in macrophage cell lines, without the MA hindering the uptake of the particles. In terms of toxicity, nanoparticles with or without MA were found to be acceptable for use, although MA did affect the viability of the cells more than poly, DL, lactic-coglycolic acid particles alone in in vitro studies. This paves the way for testing MA as a ligand to target anti-TB drugs to the sites of infection in human TB patients. / Thesis (PhD)--University of Pretoria, 2010. / Biochemistry / unrestricted

This dissertation presents the development of a new form of biomolecular material system which features interface lipid bilayers capable of hosting a wide variety of natural and engineered proteins. This research builds on the droplet interface bilayer (DIB) platform which first demonstrated that, through self-assembly, lipid-encased water droplets submersed in oil can be physically connected to form a liquid-supported lipid bilayer at the droplet interface. Key advantages of the DIB method over previous bilayer formation techniques include the lack of a supporting substrate which simplifies bilayer formation and the ability to connect many droplets to form `cell-inspired' networks which can provide a collective utility based on the compositions and arrangement of the droplets. The research present herein specifically seeks to overcome three limitations of the original droplet interface bilayer: limited portability due to lack of droplet support, the use of externally supported electrodes to electrically probe the network, and the requirement that in order to form DIB networks, aqueous volumes must be individually dispensed and arranged. The approach presented in this document is to provide increased interactions between the contained liquid phases and a supporting substrate in order to achieve both increased usability through refined methods of packaging and in situ interface formation which eliminates the need to create individual droplets. Physical encapsulation is defined as the the use of a solid substrate to contain both liquid phases such that the aqueous volumes are physically supported on one length scale (10-1000µm) while not inhibiting the self-assembly of phospholipids at the oil/water interface occurring on a much smaller length scale (1-10nm). Physically-encapsulated droplet interface bilayers are achieved by connecting lipid-encased droplets within a substrate that tightly confines the positions of neighboring droplets. A term called the packing factor is introduced to quantify the ratio of the aqueous volumes per the total compartment volume. Physically-encapsulated droplet interface bilayers formed in high packing factor substrate (30%) that also features integrated electrodes demonstrate all of the properties that unencapsulated DIBs exhibit (electrical resistances greater than 1GΩ, failure potentials between |200-300|mV, and the ability to host transmembrane proteins) but these confined assemblies can be moved, shaken, and even completely inverted. Additionally, a structured experiment to quantify the durability of interface bilayers shows that encapsulated and unencapsulated droplet interface bilayers can both survive 3-7g of lateral acceleration prior to bilayer failure, but have different modes of failure. Encapsulated DIBs tend to rupture, while unencapsulated DIBs completely separate. Physical encapsulation is also shown to permit the in situ formation of durable interface bilayers when the substrate is made from a flexible material. The importance of this approach stems from the fact that, by using the substrate to locally partition a single aqueous volume into multiple volumes, there is no need to arrange individual droplets. This method of bilayer formation is termed the regulated attachment method (RAM), since the separation and subsequent reattachment of the aqueous volumes is regulated by the opening and closing of an aperture within the flexible substrate. In this dissertation, a mechanical force is used to directly modulate the aperture dimension for controlling both the initial formation and final size of the interface. With the demonstrated advantages of portability and controlled attachment offered by physical encapsulation, encapsulated lipid bilayers are formed within a completely sealed flexible substrate. A key aspect of this final work is to demonstrate that both the organic and aqueous phases can be stabilized internally, creating a complete material system that features tailorable interface bilayers. / Ph. D.

A vast majority of heart attacks occur due to rapid progression of plaque buildup in the coronary arteries that supply blood to the heart muscles. The diseased arteries can be treated with drugs delivered locally to vulnerable plaques—ones that may rupture and release emboli, resulting in the formation of thrombus, or blood clot that can cause blockage of the arterial lumen. In designing these local drug delivery devices, important issues regarding drug distribution and targeting need to be addressed to ensure device design optimization as physiological forces can cause the local concentration to be very different from mean drug tissue concentration estimated from in vitro experiments and animal studies. Therefore, the main objective of this work was to develop a computational tool-set to support the design of a catheter-based local drug delivery system that uses nanoparticles as drug carriers by simulating drug transport and quantifying local drug distribution in coronary artery walls. Toward this end, a three dimensional mathematical model of coupled transport of drug and drug-encapsulated nanoparticles was developed and solved numerically by applying finite element based isogeometric analysis that uses NURBS-based techniques to describe the artery wall geometry. To gain insight into the parametric sensitivity of drug distribution, a study of the effect of Damkohler number and Peclet number was carried out. The tool was then applied to a three-dimensional idealized multilayered model of the coronary artery wall under healthy and diseased condition. Preliminary results indicated that use of realistic geometry is essential in creating physiological flow features and transport forces necessary for developing catheter-based drug delivery design procedures. Hence, simulations were run on a patient-specific coronary artery wall segment with a typical atherosclerotic plaque characterized by a lipid pool encased by a thin fibrous cap. Results show that plaque heterogeneity and artery wall inhomogeneity have a considerable effect on drug distribution. The computational tool-set developed was able to successfully capture trends observed in local drug delivery by incorporating a multitude of relevant physiological phenomena, and thus demonstrated its potential utility in optimizing drug design parameters including delivery location, nanoparticle surface properties and drug release rate. / text

Unstable oil markets with rising environmental concerns have revived widespread interest in production of fuel ethanol from renewable materials. Cellulosic materials are abundant and prominent feedstocks for cheap ethanol production. However, due to recalcitrant structure of these materials, pretreatment is a prerequisite. Depending on the biomass, pretreatment and hydrolysis conditions, a number of degradation products and/or toxic components may be released that show strong inhibitory effects on the fermenting microorganisms. This thesis deals with application of encapsulation technology to ferment the highly toxic hydrolyzates without further pretreatment. Free cells could not tolerate presence of 5 g/l furfural in defined medium, and inhibitors in wood and peel hydrolyzates in batch mode of operation and fermentation failed. Continuous cultivation of wood hydrolyzate was only successful at 0.1 h−1 and the majority of cells lost their viability after 5 retention times. Encapsulated cell system could successfully ferment the synthetic medium containing 5 g/l furfural during sequential batch cultivations with ethanol yield of 0.41-0.42 g/g. Cultivation of undetoxified hydrolyzates was also carried out, where glucose and mannose were converted within 10 h without significant lag phase. However, a gradual decrease in cell activity was observed in sequential batches. Continuous cultivation was more successful, and wood hydrolyzate was fermented to ethanol by encapsulated S. cerevisiae at dilution rates up to 0.5 h−1. More than 75% of the encapsulated cells were viable in the worst conditions. Ethanol was produced with yield 0.44 g/g and specific productivity 0.14–0.17 g/g•h at all dilution rates. Contrary to wood hydrolyzate, where there is no preference for permeation of sugars or inhibitors through the capsules’ membrane, encapsulation technology was applied to eliminate inhibition of limonene in fermentation of orange wastes to ethanol. The capsules’ membrane, of hydrophilic nature, is practically impermeable to hydrophobic compounds such as limonene while allowing penetration of nutrients and products. While presence of 0.1% v/v limonene in the medium results in strong inhibition or even failure of cultivation with free cells, using this technique allowed fermentation of a medium containing 1.5% v/v limonene. The impact of encapsulation on the anaerobic growth pattern, morphological and physiological changes of S. cerevisiae over long-term application was investigated. The growth rate, total RNA and protein content of the encapsulated cells decreased gradually over repeated batch cultivations, while stored carbohydrates content increased. Within 20 batch cultivations, total RNA and protein content of encapsulated cells decreased by 39% and 24%, whereas glycogen and trehalose content increased by factors of 4.5 and 4, respectively. / <p>Akademisk avhandling som för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 18 april 2008.</p>

Lignocellulosic biomass is a potential feedstock for production of sugars, which can be fermented into ethanol. The work presented in this thesis proposes some solutions to overcome problems with suboptimal process performance due to elevated cultivation temperatures and inhibitors present during ethanol production from lignocellulosic materials. In particular, continuous processes operated at high dilution rates with high sugar utilisation are attractive for ethanol fermentation, as this can result in higher ethanol productivity. Both encapsulation and membrane bioreactors were studied and developed to achieve rapid fermentation at high yeast cell density. My studies showed that encapsulated yeast is more thermotolerant than suspended yeast. The encapsulated yeast could successfully ferment all glucose during five consecutive batches, 12 h each at 42 °C. In contrast, freely suspended yeast was inactivated already in the second or third batch. One problem with encapsulation is, however, the mechanical robustness of the capsule membrane. If the capsules are exposed to e.g. high shear forces, the capsule membrane may break. Therefore, a method was developed to produce more robust capsules by treating alginate-chitosan-alginate (ACA) capsules with 3-aminopropyltriethoxysilane (APTES) to get polysiloxane-ACA capsules. Of the ACA-capsules treated with 1.5% APTES, only 0–2% of the capsules broke, while 25% of the untreated capsules ruptured within 6 h in a shear test. In this thesis membrane bioreactors (MBR), using either a cross-flow or a submerged membrane, could successfully be applied to retain the yeast inside the reactor. The cross-flow membrane was operated at a dilution rate of 0.5 h-1 whereas the submerged membrane was tested at several dilution rates, from 0.2 up to 0.8 h-1. Cultivations at high cell densities demonstrated an efficient in situ detoxification of very high furfural levels of up to 17 g L-1 in the feed medium when using a MBR. The maximum yeast density achieved in the MBR was more than 200 g L-1. Additionally, ethanol fermentation of nondetoxified spruce hydrolysate was possible at a high feeding rate of 0.8 h-1 by applying a submerged membrane bioreactor, resulting in ethanol productivities of up to 8 g L-1 h-1. In conclusion, this study suggests methods for rapid continuous ethanol production even at stressful elevated cultivation temperatures or inhibitory conditions by using encapsulation or membrane bioreactors and high cell density cultivations. / <p>Akademisk avhandling som för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 4 april 2014, klockan 9:30 i KE-salen, Kemigården 4, Göteborg.</p>

As formigas-cortadeiras do gênero Atta são apontadas como os principais herbívoros da região Neotropical, sendo capazes de causar grandes danos à agricultura, às pastagens e à silvicultura em especial. No controle químico dessa praga, a tática mais usual e efetiva tem sido o uso de iscas granuladas tóxicas. Todavia, têm-se procurado métodos alternativos para o controle de cortadeiras, sobretudo por pressão de agências certificadoras de manejo florestal como o FSC (Forest Standarship Council). Recentemente, isolados de Trichoderma spp. começaram a ser testados no controle de formigas-cortadeiras em razão das suas propriedades antagonísticas ao fungo simbionte por elas cultivados. Além disso, destacam-se substâncias que têm o potencial de inibir a resposta imune inata dos insetos. Por exemplo, alguns elementos químicos como, cádmio e zinco. O presente trabalho objetivou o preparo de uma formulação com iscas granuladas e encapsuladas do fungo Trichoderma harzianum. Para encapsulação do fungo, utilizou-se uma mistura de alginato de sódio, farelo de trigo, suco concentrado de laranja e micélio triturado do antagonista. Esta mistura foi gotejada em solução (0,25 M) de CaCl2, o que permitiu a formação de grânulos esféricos de diâmetro regular. Paralelamente testou-se iscas contendo sulfato de zinco ZnSO4 (0,25 g/L), produzidas a partir da mistura de alginato, farelo de trigo e suco concentrado de laranja. Após o fornecimento das iscas fez-se a contagem total de hemócitos das operárias a fim de verificar alterações da sua resposta imune. Não ocorreu declínio na quantidade de hemócitos. Apesar das iscas não terem promovido a morte das colônias, elas apresentaram boa aceitação pelas operárias e promoveram a redução do volume do fungo simbionte. O cloreto e o sulfato de zinco foram empregados nas concentrações de 0,15; 0,25; 0,5; 1,5; 2;5 e 5;0 g/L em placas de Petri em meio BDA para o teste de desenvolvimento dos fungos simbionte e antagonista, e os resultados mostraram inibição no crescimento nas doses máximas tanto em Leucoagaricus gongylophorus como em Trichoderma harzianum. As operárias foram imersas em soluções de sulfato de zinco com as mesmas concentrações daquelas empregadas no teste de inibição dos fungos. Após o tempo de 24 e 48 horas fez-se a contagem total de hemócitos e verificou-se um decréscimo dos mesmos em altas concentrações. Conclui-se que as iscas contendo T. harzianum e sulfato de zinco apresentaram boa aceitação por parte das colônias, elas não promoveram a morte das colônias, no entanto, reduziram o volume do fungo simbionte. Altas doses de cloreto e sulfato de zinco inibem o desenvolvimento do fungo antagonista e do fungo simbionte e elevadas concentrações zinco e o maior tempo de exposição das operárias ao mesmo afetam o seu sistema imune. / The leaf-cutting ants of the genus Atta are cited as the main herbivores of the Neotropical region, being capable of causing major damage to agriculture, pasture and forestry in particular. In the chemical control of this plague, the most common and effective tactic has been the use of toxic granular baits. However, there have been alternative methods for control of cutting, especially by pressure certifying agencies forest management as the FSC (Forest Standarship Council). Recently, Trichoderma spp. They began to be tested in the control of leaf-cutting ants because of their antagonistic properties to the symbiotic fungus cultivated by them. Furthermore, they highlight substances that have the potential of inhibiting the innate immune response of the insects. For example, some chemical elements such as cadmium and zinc. This study aimed to the preparation of a formulation with granulated baits and encapsulated fungus Trichoderma harzianum. For encapsulation fungus, a mixture of sodium alginate was used wheat bran, concentrated orange juice and triturated antagonist mycelium. This mixture was dripped into solution (0,25 M) CaCl2, which allowed the formation of spherical granules of regular diameter. Parallel tested for baits containing zinc sulfate ZnSO4 (0,25 g/L) produced from the mixture of alginate, wheat bran and concentrated orange juice. After the supply of baits made up the total count of hemocytes of the workers in order to verify changes in their immune response. There was no decline in the amount of hemocytes. Despite the baits have not promoted the death of the colonies, they had good acceptance by workers and promoted the reduction of the symbiont fungus volume. Chloride and zinc sulfate were used in concentrations of 0.15; 0.25; 0.5; 1.5; 2, 5 and 5; 0 g /L in Petri dishes on PDA medium for the development and test of antagonist symbiont fungi, and the results showed growth inhibition in both maximal doses Leucoagaricus gongylophorus as Trichoderma harzianum. The ants were dipped in zinc sulfate solutions with the same concentrations of those employed in the fungal inhibition assay. After time 24 and 48 hours we made the total hemocytes count and there was a decrease in high concentrations thereof. We conclude that the baits containing T. harzianum and zinc sulfate showed good acceptance by the colonies, they did not promote the death of the colonies, however, reduced the volume of the symbiont fungus. High doses of zinc chloride and sulfate inhibit the development of the antagonist fungus and symbiont fungus and high concentrations of zinc and the longer exposure time of workers at the same affect your immune system.

The synthesis and characterization of Pt core/ Cu shell (Pt@Cu) dendrimer-encapsulated nanoparticles (DENs) having full and partial Cu shells deposited via electrochemical underpotential deposition (UPD) is described. Pt DENs containing averages of 55, 147, and 225 Pt atoms immobilized on glassy carbon electrodes served as the substrate for the UPD of a Cu monolayer. This results in formation of Pt@Cu DENs. Evidence for this conclusion is based on results from the analysis of cyclic voltammograms (CVs) for the UPD and stripping of Cu on Pt DENs, and from experiments showing that the Pt core DENs catalyze the hydrogen evolution reaction before Cu UPD, but that after Cu UPD this reaction is inhibited. Results obtained by in-situ electrochemical X-ray absorption spectroscopy (XAS) confirm the core@shell structure. Calculations from density functional theory (DFT) show that the first portion of the Cu shell deposits onto the (100) facets, while Cu deposits lastly onto the (111) facets. The DFT-calculated energies for Cu deposition on the individual facets are in good agreement with the peaks observed in the CVs of the Cu UPD on the Pt DENs. Finally, structural analysis of Pt DENs having just partial Cu shells by in-situ XAS is consistent with the DFT-calculated model, confirming that the Cu partial shell selectively decorates the (100) facets. These results are of considerable significance because site-selective Cu deposition has not previously been shown on nanoparticles as small as DENs. In summary, the application of UPD as a synthetic route and characterization tool for core@shell DENs having well defined structures is established. A study of the degradation mechanism and degradation products of Pd DENs is provided as well. These DENs consisted of an average of 147 atoms per dendrimer. Elemental analysis and UV-vis spectroscopy indicate that there is substantial oxidation of the Pd DENs in air-saturated solutions, less oxidation in N₂-saturated solution, and no detectable oxidation when the DENs are in contact with H₂. Additionally, the stability improves when the DEN solutions are purified by dialysis to remove Pd²⁺-complexing ligands such as chloride. For the air- and N₂-saturated solutions, most of the oxidized Pd recomplexes to the interiors of the dendrimers, and a lesser percentage escapes into the surrounding solution. The propensity of Pd DENs to oxidize so easily is a likely consequence of their small size and high surface energy. Calculations from density functional theory (DFT) show that the first portion of the Cu shell deposits onto the (100) facets, while Cu deposits lastly onto the (111) facets. The DFT-calculated energies for Cu deposition on the individual facets are in good agreement with the peaks observed in the CVs of the Cu UPD on the Pt DENs. Finally, structural analysis of Pt DENs having just partial Cu shells by in-situ XAS is consistent with the DFT-calculated model, confirming that the Cu partial shell selectively decorates the (100) facets. These results are of considerable significance because site-selective Cu deposition has not previously been shown on nanoparticles as small as DENs. In summary, the application of UPD as a synthetic route and characterization tool for core@shell DENs having well defined structures is established. A study of the degradation mechanism and degradation products of Pd DENs is provided as well. These DENs consisted of an average of 147 atoms per dendrimer. Elemental analysis and UV-vis spectroscopy indicate that there is substantial oxidation of the Pd DENs in air-saturated solutions, less oxidation in N2-saturated solution, and no detectable oxidation when the DENs are in contact with H2. Additionally, the stability improves when the DEN solutions are purified by dialysis to remove Pd2+-complexing ligands such as chloride. For the air- and N2-saturated solutions, most of the oxidized Pd recomplexes to the interiors of the dendrimers, and a lesser percentage escapes into the surrounding solution. The propensity of Pd DENs to oxidize so easily is a likely consequence of their small size and high surface energy. / text

Olfactory sensory neurons (OSNs) undergo continual degeneration and replacement throughout life, a cycle that can be synchronized experimentally by performing olfactory bulbectomy (OBX). OBX induces apoptosis of mature OSNs, which is followed by an increase in the proliferation of progenitor basal cells. Macrophages, functionally diverse immune effector cells, phagocytose the apoptotic OSNs and regulate the proliferation of basal cells. This provides an advantageous environment to study how macrophages regulate neuronal death, proliferation, and replacement. The purpose of this dissertation was to identify the cellular and molecular mechanisms by which macrophages regulate the degeneration/proliferation cycle of OSNs. Macrophages were selectively depleted using liposome-encapsulated clodronate (Lip-C). Intranasal and intravenous administration of Lip-C decreased the number of macrophages in the OE of sham and OBX mice by 38% and 35%, respectively, compared to mice treated with empty liposomes (Lip-O). Macrophage depletion significantly decreased OE thickness (22% and 21%, p<0.05), the number of mature OSNs (1.2- and 1.9-fold, p<0.05), and basal cell proliferation (7.6- and 3.8-fold, p<0.05) in sham and OBX mice, respectively, compared to Lip-O mice. Additionally, at 48 h following OBX, OSN apoptosis increased significantly (p<0.05) in the OE of Lip-C mice compared to Lip-O mice. A microarray analysis was performed to identify the genomic changes underlying the cellular changes associated with macrophage depletion. There were 4,024 genes with either a significant interaction between group (Lip-C vs. Lip-O) and treatment (OBX vs. sham) or a significant main effect. There were a number of significantly regulated immune response and cytoskeletal genes, and genes encoding neurogenesis regulators and growth factors, most of which were expressed at lower levels in Lip-C mice compared to Lip-O mice. Sdf1, the ligand for the chemokine receptor Cxcr4 involved in leukocyte trafficking, axon guidance, and cell migration, was localized to macrophages on the protein level. Additionally, the microarray expression pattern of Hdgf, a growth factor that promotes neuronal survival and proliferation, was validated on the protein level using immunohistochemistry. HDGF appeared to be localized to basal cells and OSNs where it could act as a proliferative or survival factor whose expression is regulated in part by macrophages.

Made available in DSpace on 2014-12-17T14:07:02Z (GMT). No. of bitstreams: 1 DarciaSSMM_DISSERT.pdf: 2144091 bytes, checksum: 373e58cf1ee08b2c45a550ad627238d6 (MD5) Previous issue date: 2012-04-09 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The present work has as objective the development of ceramic pigments based in iron oxides and cobalt through the polymeric precursor method, as well as study their characteristics and properties using methods of physical, chemical, morphological and optical characterizations.In this work was used iron nitrate, and cobalt citrate as precursor and nanometer silica as a matrix. The synthesis was based on dissolving the citric acid as complexing agent, addition of metal oxides, such as chromophores ions and polymerization with ethylene glycol. The powder obtained has undergone pre-ignition, breakdown and thermal treatments at different calcination temperatures (700 ?C, 800 ?C, 900 ?C, 1000 ?C and 1100 ?C). Thermogravimetric analyzes were performed (BT) and Differential Thermal Analysis (DTA), in order to evaluate the term decomposition of samples, beyond characterization by techniques such as BET, which classified as microporous materials samples calcined at 700 ? C, 800 ? C and 900 ? C and non-porous when annealed at 1000 ? C and 1100 ? C, X-ray diffraction (XRD), which identified the formation of two crystalline phases, the Cobalt Ferrite (CoFe2O4) and Cristobalite (SiO2), Scanning Electron Microscopy (SEM) revealed the formation of agglomerates of particles slightly rounded;and Analysis of Colorimetry, temperature of 700 ?C, 800 ?C and 900 ?C showed a brown color and 1000 ?C and 1100 ?C violet / O presente trabalho tem como objetivo o desenvolvimento de pigmentos cer?micos a base de ?xidos de ferro e cobalto atrav?s do m?todo dos precursores polim?ricos, bem como o estudo de suas caracter?sticas e propriedades atrav?s de m?todos de caracteriza??es f?sicas, qu?micas, morfol?gicas e ?pticas. Neste trabalho foi utilizado nitrato de ferro e citrato de cobalto como precursores e s?lica nanom?trica como matriz. A s?ntese foi baseada na dissolu??o do ?cido c?trico, como agente complexante; adi??o dos ?xidos met?licos, como ?ons crom?foros e polimeriza??o com etileno glicol. O P? obtido passou por pr?-calcina??o, desagrega??o e tratamentos t?rmicos em diferentes temperaturas de calcina??o (700 ?C, 800 ?C, 900 ?C, 1000 ?C e 1100 ?C). Foram feitas An?lises de Termogravimetria (TG) e An?lise T?rmica Diferencial (DTA), a fim de se avaliar a termodecomposi??o das amostras, al?m de caracteriza??es por t?cnicas como BET, que classificou como materiais microporosos as amostras calcinadas a 700 ?C, 800 ?C e 900 ?C e n?o porosos quando calcinados a 1000 ?C e 1100 ?C; Difra??o de Raios-X (DRX), que identificou a forma??o de duas fases cristalinas, a Ferrita de Cobalto (CoFe2O4) e a Cristobalita (SiO2); Microscopia Eletr?nica de Varredura (MEV), que revelou a forma??o de aglomerados de part?culas ligeiramente arredondadas; e an?lise de colorimetria na regi?o do UV-Vis?vel, verificando a varia??o e o potencial de cromaticidade do pigmento que a temperaturas de 700 ?C, 800 ?C e 900 ?C apresentou a cor marrom e a 1000 ?C e 1100 ?C a cor violeta