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Nanocompósitos para a liberação controlada de compostos triazínicos aplicados como defensivos agrícolas
(Universidade Federal de São Carlos, 2013-08-02) Giroto, Amanda Soares; Oliveira, Cauê Ribeiro de; https://lattes.cnpq.br/5321313558714462; https://lattes.cnpq.br/9177789234139161
This research proposed a preparation method for a nanocomposite, able to control the delivery of high quantities of an active compound, inserted on its matrix, in order to prospect an application for the controlled delivery of herbicides. To that, a nanocomposite system was prepared based on the exfoliation of a clay mineral in a continuous starch phase, loading around 50% weight of a model herbicide ametryne. The starch was loaded with 50 to 80% of montmorillonite, dispersed through the starch gelification at 90o C in water. The herbicide was added during the cooling process, at 70o C. The materials were characterized by X-ray diffraction and thermal analyses, where the intercalation of the biopolymer in the clay lamellar structure was observed. The herbicide release showed that the releasing behavior was governed by the starch amount in the nanocomposite, for short periods, and by the clay, in longer periods. It was observed also a synergic effect between the nanocomposite constituents, since the reference materials (produced with starch: ametryne or clay: ametryne) did not showed adequate release behaviors. However, this behavior was shown as governed by physical barriers for the ametryne diffusion, since nuclear magnetic resonance in solid state experiments showed that the starch: ametryne interactions were weak. On the other hand, the starch: clay interactions were shown by the same technique, supporting the synergic behavior of the release. Finally, the nanocomposite system improved the resistance to the UV light attack, reducing the herbicide volatilization under irradiation. This effect was evaluated by mass loss experiments after different irradiation times, compared to infrared spectroscopy measurements.
Características e mecanismos de desgaste dos refratários MgO-C usados na linha de escória de panelas de aço
(Universidade Federal de São Carlos, 2013-08-02) Leite, Frederico Concon; Pandolfelli, Victor Carlos; https://lattes.cnpq.br/7369376873984839; https://lattes.cnpq.br/6163613687453825
Steel ladles are special vessels used for liquid steel transportation from the primary refining stage up to its solidification one at the casting shop. The MgO-C bricks have been used for lining this equipment due to its high chemical resistance to steel slags and thermal shock. However, new procedures during refining stages have increased the attack of the refractory lining, especially in the slag line, where the corrosion and wearing processes are intense. This fact has significant implications in reducing the ladle availability, leading to the need of intermediary repairs, besides increasing production costs and affecting the operational safety. In this context, the present study aims to evaluate the wear mechanisms of the steel ladle slag line by identifying the effects of some variables during the refractory production, placing and operation. In order to achieve that, the computational thermodynamics was widely used to understand the reactions and transformations that occur in complex systems, such as the interaction between refractory and slag. The software helped in evaluating the effect of raw materials, antioxidants additives and alternative materials (such as spinel) of new MgO-C ceramic compositions performance. The laboratory tests indicated the oxidation and corrosion as the main wearing mechanisms in MgOC refractory. In the first case, it was detected the importance to develop solutions for carbon protection, such as, applying a lining antioxidant coating for the first ladle heating. In addition, the slag conditioning efficiency to reduce the bricks corrosion rate was attested, due to the chemical potential decrease for dissolving the refractory constituents. Thus, this project has improved the knowledge of MgO-C behavior at high temperatures and also helped in the development of alternative solutions (focused in operational standards and formulations) to maximize the refractory performance.
Controle epigenético da expressão do gene CAST, relacionado à maciez de carne em bovinos de corte
(Universidade Federal de São Carlos, 2013-08-02) Rocha, Marina Ibelli Pereira; Niciura, Simone Cristina Méo; https://lattes.cnpq.br/3269530126090378; https://lattes.cnpq.br/4073481479229781
The Meat tenderness, a trate of economic importance in animal production, is influenced by the intensity of the degradation of myofibrillar proteins in post-mortem. The μ-calpain is the main enzyme responsible for meat tenderness of skeletal muscle, and, conversely, the calpastatin, which is encoded by the CAST gene, acts as endogenous inhibitor of calpain and thus decreases the extent of proteolysis in skeletal muscle. Polymorphisms in CAST were associated with enzyme activity and shear force, indicating the great importance of the study of CAST gene regulation. It is known that the transcription of most genes is stably suppressed in most tissues and only remains active in their tissue of expression and in certain developmental stages, and that can be controlled by epigenetic events such as methylation of DNA cytosine that is identified by sequencing of bisulfite-treated DNA. The aim of this study was to evaluate if there was preferential expression, of tissue, genotype and stage of development for the CAST gene in liver, muscle and skin of fetuses and muscle and liver of homozygous and heterozygous adult cattle for the A> G exon 30/3'UTR polymorphism, evaluated by real-time PCR with SYBR ® fluorophore, and to verify if the differential expression is regulated by the methylation status of promoter region. Differential gene expression analyses were normalized to the reference gene RPS-9. When we analyzed the tissue-specific expression in fetuses, the CAST gene was 2 times more expressed in liver than in skin (p <0.05) and almost two times more expressed in liver than in muscle (p <0.05). It was also found that this gene was 1.83 x up regulated in adult muscle when compared to fetal muscle (p <0.05), showing differential expression in the developmental stage. Differences in expression between genotypes were also found, when comparing the homozygous genotype to the heterozygous genotype (used as calibrator). Fetal samples of muscle and skin of individuals with GG genotype presented higher expression (p <0.05) of CAST gene (2x and 1,74 x, respectively, compared to heterozygous) and muscle of animals with AA genotypes also presented higher expression (1.4x compared to AG). In adult animals, the gene was up regulated in liver and muscle of individuals with GG genotype (2x and 1.63x more than AG, respectively) and was less expressed in the liver of homozygote AA (0,32x less than AG) (p <0.05). The presence of a CpG island in the promoter region of the gene CAST was identified and the methylation status was studied after bisulfite treatment, cloning of the fragment and sequencing of clones. The CpG island was hypomethylated in different tissues: 0.63% of methylated CpG dinucleotides in fetal muscle, 0.43% in fetal liver and 0.61% in adult muscle. According to the different genotypes the island was methylated in 0.61%, 0 49%, 0.60% in animal with AA genotype, 0.81%, 0.35%, 0.34% in AG, 0.4%, 0.45% ,0.9% in GG in fetal muscle, fetal liver and adult muscle respectively. In our results we show that the CpG island is hypomethylated and can allow transcription of the gene but the methylation does not explain the differences in expression within tissues, developmental stage and genotypes of the CAST gene.
Método de processamento digital de imagens para inferência da qualidade de materiais preparados com fibras vegetais
(Universidade Federal de São Carlos, 2013-08-02) Miyamoto, Bruno Seiji; Cruvinel, Paulo Estevão; https://lattes.cnpq.br/7924553462118511; https://lattes.cnpq.br/4938115375645472
This Dissertation presents a method development based on image processing techniques, which enables the verification and quality analysis of organic fibers mixture in thermoplastic starch (TPS). In order to do this analysis, we implemented a Python programming language module, which is able to compute invariant moments of Hu and other statistical calculations to quantify homogeneity, we applied this calculations to a set of high resolution tomography images of materials resulting from the mixture of thermoplastic starch and fibers. TPS based compositions, have recently received much attention, from industry and academia, for being one of the most economical options to produce biodegradable plastics. Although promising, there are two major limitations to the use of TPS: their mechanical fragility and sensibility to water. A solution to this problem is to mix TPS with vegetable fibers materials, maintaining its biodegradability, thus offering greater mechanic and humidity resistance. Nowadays there are methods techniques and equipment used to check mechanical resistance, water absorption and crystallinity of biodegradable samples. However, there is a lack of methods used specifically for the measurement of organic fibers homogeneity distribution in TPS, therefore assisting the production quality verification of those samples. As a result of this work, we obtained a method which infers the manufacturing process quality of new biodegradable materials, produced from the mixture of vegetable fibers and TPS, based on the homogeneity and the roughness degree of the samples produced.
Efeito de diferentes solventes nas propriedades fotoluminescentes do CaMoO4
(Universidade Federal de São Carlos, 2013-08-02) Botelho, Gleice Lorena Gonçalves Tavares; Longo, Elson; https://lattes.cnpq.br/9848311210578810; https://lattes.cnpq.br/1653318126569015
The CaMoO4 has been extensively studied due to its luminescent emissions in the visible region of the electromagnetic spectrum at room temperature, presenting potential for technological applications including lasers, light emitting diodes and lamps. The solvent and the method utilized in the synthesis are important in the control of the obtained powders morphology. Therefore, in this master s thesis CaMoO4 samples were obtained by microwave-assisted solvothermal and coprecipitation method, using ethylene glycol and 1,3-propanediol as solvent. As experimental results, the X-ray diffraction patterns and Infrared and Raman-active vibration modes proved that all powders have a scheelita-type tetragonal structure. The Rietveld refinements suggested the existence of distortion both [MoO4] and [CaO8] clusters. The ultraviolet-visible absorption spectra indicated the presence of intermediary energy levels within the band gap, which are arising from structural defects in the materials. Field-emission gun scanning electron microscopy and transmission electron microscopy images revealed the obtainment of nanoscale and agglomerated particles. When excited with 350 nm wavelength, all samples exhibited broadband photoluminescence emissions in the region of the blue and/or green of the electromagnetic spectrum.