279 resultados para Gels


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Pós-graduação em Ciência da Informação - FFC

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As características estruturais de sonogéis obtidos a partir da hidrólise ácida do TEOS estimulada por ultrasom foram estudadas por espalhamento de raios-x a baixo ângulo (SAXS). O estudo inclui: i) o processo de agregação em diferentes temperaturas; ii) o envelhecimento dos géis úmidos na fase líquida de preparação e depois da troca da fase líquida por álcool e acetona; iii) a secagem dos géis; iv) a estrutural evolução de xerogéis e aerogéis com o tratamento térmico até 1100 oC; e v) um estudo comparativo usando SAXS e adsorção de nitrogênio na caracterização de aerogéis e xerogéis... (Resumo completo, clicar acesso eletrônico abaixo)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Changes in protein content, peroxidase activity, and isozyme profiles in response to soybean aphid feeding were documented at V1 (fully developed leaves at unifoliate node, first trifoliate leaf unrolled) and V3 (fully developed leaf at second trifoliate node, third trifoliate leaf unrolled) stages of soybean aphid-tolerant (KS4202) and -susceptible (SD76R) soybeans. Protein content was similar between infested and control V1 and V3 stage plants for both KS4202 and SD76R at 6, 16, and 22 d after aphid introduction. Enzyme kinetics studies documented that control and aphid-infested KS4202 V1 stage and SD76R V1 and V3 stages had similar levels of peroxidase activity at the three time points evaluated. In contrast, KS4202 aphid-infested plants at the V3 stage had significantly higher peroxidase activity levels than control plants at 6 and 22 d after aphid introduction. The differences in peroxidase activity observed between infested and control V3 stage KS4202 plants at these two time points suggest that peroxidases may be playing multiple roles in the tolerant plant. Native gels stained for peroxidase were able to detect differences in the isozyme profiles of aphid-infested and control plants for both KS4202 and SD76R.

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Mesenchymal stem cells (MSCs) are a heterogeneous population of cells that proliferate in vitro as plastic-adherent cells, have fibroblast-like morphology and can differentiate into bone, cartilage and fat cells. Therapeutic potential of MSCs have been studied in experimental models, such as rabbit, in Laboratory of Cell Engineering of Botucatu. However, no specific markers have been reported for expanded rabbit MSCs, which hampers the isolation of pure MSC populations by immunophenotypic characterization. Thus, the objective of this study was to produce monoclonal antibodies (mAbs) to rabbit MSCs. MSCs derived from rabbit bone marrow (BM) were isolated, cultured, expanded ex vivo, and immunized into three BALB/c mices, and spleen cells subsequently harvested were used to generate hibridoma cell lines secreting antibodies against MSCs. Hybridoma cells were screened by flow cytometry and antibody-producing cells were subjected to subsequent rounds of retests. MSC1-160 obtained the best positivity for IgG expression and was cloned by limiting dilutions and micromanipulation. Ascitic fluid from ten best clones was purified by affinity chromatography in Protein A-sepharose CL-4B column and purification control was performed by electrophoresis in agarose gels. The purified IgG were tested against rabbit MSCs, obtaining high positivity by flow Cytometry. In conclusion, we developed 10 mAbs, MSC1-160 A20, A30, A41, A47, A55, A60, A63, A69, A81, and A82, that recognize rabbit MSC cell surface antigens showing potential for immunophenotypic characterization of rabbit MSC cell lines

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Introduction: Tuberculosis (TB) is a granulomatous disease caused by Mycobacterium tuberculosis. The genus Mycobacteriumhas two different complexes: M. tuberculosis Complex and M. avium Complex. This is a global health epidemic and remains a major global health problem, besides, the clinical severity of TB is significantly higher in transplanted patients. The detection of these mycobacteria complexes in transplanted patients, by molecular methods, is fundamental for quick treatment of patients and can contribute for rapid and accuracy of diagnosis. Objective: To detect mycobacteria DNA of M. tuberculosis and M. avium Complexes in formalin fixed paraffin-embedded samples (FFPE) of two patients groups: non transplanted and transplanted. Materials and Methods: The study includes 40 FFPE biopsies separated in four groups: NTP – presence of epithelioid granuloma and positive ZN, non-transplanted patients – 9 samples; NTN - presence of epithelioid granuloma and negative ZN, non-transplanted patients – 10 samples; TP – positive ZN, transplanted patients – 9 samples; TN – negative ZN, transplanted patients – 7 samples. Sections were cut for DNA extraction. Samples were submitted to PCR for amplification of: a) β-actin, b) IS6110 insertion and c) IS1245 insertion. DNA evaluation was made by spectrophotometry and efficiency and PCR analysis was made by agarose gels under UV light. Results: In all samples processed, 97.1% were positive for human β-actin gene. In22.2% of NTP group were found the IS6110 insertion sequencebut the IS1245 wasn´t. In the NTN group was not found any sequence. In theTP group, 11.1% of the samples were positive for IS6110 and also 11,1% werepositive for IS1245. In the TN group, 14.3% of the samples were positive forIS6110 and for IS1245, 14.3% was also positive. Conclusion: Although factors such as DNA degradation after formalin fixation and paraffin embedding, were possible to detect DNA from the human gene ...

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In order to enable the reuse of the large surplus volume of petroleum produced water for irrigation of crops inedible, the quality evaluation of this water is very important. This work aimed to evaluate the effectiveness of the diffusive gradient in thin films technique (DGT) for the determination of labile Cu (II), Mn (II) and Zn (II) in petroleum produced water destined to reuse in agriculture. Samples were collected at the exit of the wastewater treatment plant (WWTP) (after separation oil/water and flotation) of a Petrobrás onshore production region. Basically, the laboratory experiments with DGT devices involved the evaluation of the behavior of the main variables of the technique for determination of analytes in the samples (diffusion coefficients, immersion time, fractionation of organic and inorganic species, and performance of diffusion gels with different porosities, among others). Also, experiments were conducted based on the solid phase extraction (SPE) protocol with Chelex- 100 resin using previously established protocols to support the study. During the project the possibility of in situ immersions in water treatment plants was evaluated. The DGT technique presented satisfactory results for determination of Mn in produced water, and can be used for in situ determinations. However, the results obtained for Cu and Zn show the need of additional studies

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The small angle X-ray scattering (SAXS) technique has been used with very much versatility and success in the structural characterization of nanostructured materials. The present work deals with a study of the principles of the SAXS technique and of some classical models employed in the structural characterization of nanostructured materials. Particularly, the study of the models and of the associated methodologies is applied to a set of samples of silica gels, of varied typical structures, prepared in the Laboratório de Novos Materiais of the Departamento de Física of the IGCE. The work discusses in an introductory chapter the principles of the SAXS technique and the foundation of classical models often used in the structural characterization of materials. The classical models and the associated methodologies were applied to a variety of silica gel structures. The studies include: i) the scattering from a system of particles - Guinier's law; ii) the asymptotic scattering from a two-phase system - Porod's law; iii) systematic deviation from Porod's law - Surface Fractal; iv) heterogeneities in solids with random size distribution - DAB Model; and v) the scattering from mass fractal structures. The analyses were carried out from experimental SAXS data obtained in several opportunities at the Laboratório Nacional de Luz Síncrotron (LNLS)

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It is believed that epigenetic mechanisms such as DNA methylation are important for the tumorigenesis and maintenance of the altered state of tumor cells. DNA methylation occurs by the addition of a methyl group to carbon 5 of cytosine, catalyzed by the enzyme DNA methyl-transferase, which can change the expression of a gene, including the tumor suppressor genes. In human squamous cell carcinoma, several features have shown the etiological role of genes in tumor development. Among them, FOXE1 gene (forkhead box E1 - thyroid transcription factor) is presented with an important role in susceptibility to disease. Similarly the FOXE1 methylation pattern could alter the expression of this gene in dogs and predisposed to tumor on. Therefore, this study aims to investigate in dogs, the validity of the strategy employed in humans to analyze the FOXE1 methylation status. DNA extraction from fresh frozen tumoral samples was performed by Wizard Genomic® DNA Purification Kit. The methylation status was determined by MSP-PCR (methylation-specific polymerase chain reaction), using 2.0 ng of DNA treated with sodium bisulphate. One hundred micrograms of bisulphite-modified DNA was amplified using primers specific for either methylated or unmethylated DNA (primers sequences are available at http://pathology2.jhu.edu/pancreas/primer.pdf). The analysis of fragments was loaded on to 7% polyacrylamide gels and silver nitrate staining. In this stage of technical approach, 60% were FOXE1 hypermethylated. In conclusion, it was observed that the standard technique for assessing the methylation pattern of gene FOXE1 in humans can be used for the same evaluation in dogs. The correlation of these molecular data with clinical and histopathological parameters may have diagnostic and prognostic value and still be used as a tumor marker for therapeutic decision and surgical approach

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This work aims to study the structural characteristics of silica gels obtained from the acid hydrolysis of tetraethoxysilane (TEOS) in water solutions with different concentrations of sodium dodecyl sulfate (SDS). The structural characteristics were studied in stages ranging from the wet gel to the dry stages of the gels (aerogels and xerogels). Aerogels were obtained by ambient pressure drying (APD) after silylation process using trimethylchlorosilane (TMCS) as silylating agent. Xerogels were obtained by conventional evaporating the liquid phase from non silylated gels. The samples were characterized by nitrogen adsorption and small angle X-ray scattering (SAXS). The structure of the wet gels and of the aerogels prepared with the surfactant exhibited characteristics of mass-fractal structures with fractal dimension D in the range 2.1-2.2 for the wet gels and 2.3-2.4 for the aerogels. The characteristic size  of the fractal domain reduces while the size a0 of the primary silica particle composing the fractal structure increases with the drying of the gels, in a process in which share of the porosity is eliminated. Aerogels exhibited typical values for the specific surface of 900 m2g-1 and of 3.5 cm3.g-1 for the total pore volume. These values are correspondingly comparable to those of the aerogels prepared by supercritical drying, since the silylation process replaces hydrophilic –OH groups by hydrophobic –Si-R3 ones, inhibiting the porosity elimination on drying. The silica particle size also increases lightly with the silylation because the attachment of the –Si-R3 groups on the silica surface. The pore size distribution curves of the aerogels are similar for all samples exhibiting a maximum in around 40 nm, independent the concentration of surfactant. This suggests that the characteristic size of 40 nm is due to the association of surfactant micelles... (Complete abstract click electronic access below)

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The DGT technique has been used to determine and better understand the dynamics and bioavailability of metals in the sea near to marine outfalls. In this work, the DGT was assessed for the determination of Cd, Pb, Cu, Zn and Ni in marine water samples from Potiguar Basin in its conventional aspect (binding agent, Chelex-100 and diffusive agent: Diffusive polyacrylamide gel (D) and restrictive (R)) and determination of Pb and Cd through its alternative aspect (binding agent: Saccharomyces cerevisiae immobilized in agarose gels and diffusive agent: 3MM Chromatography Paper). The deployment curves for long periods of immersion in the sample, showed a good linear correlation for the conventional aspect to Zn (D: R²=0.9586, R: R²=0.9444), Ni (D: R²=0.9789, R: R²=0.9286) and Cu (D: R²=0.764, R: R²=0.8143), and alternative to Pb (R²=0.9228) and Cd (R²=0.9673). The results of the organic and inorganic composition analysis in conventional aspect, showed that for every element there is no significant fraction of organic compounds in the sample. In addition, considering the alternative aspect, the comparison of obtained and expected masses suggests that some of the Pb is not labile and that the main retention mechanism of Pb for S. Cerevisiae occurs through ion exchange

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In the present work the thermal characteristics of gels and xerogels of Silica/organic hybrids derived from different concentrations of GPTS-TEOS were investigated by thermal analysis (TG, DTA, and DSC). The preparation of gels of the Silica/organic hybrid matrix was held through the sol-gel process, consisting by the hydrolysis of alkoxides GPTS and TEOS in proportion (1:1) and (1:2) that was promoted in acidic conditions under reflux and stirring at 80oC/2h, producing the matrix in the colloidal state (sol). Gels were prepared by addition of NH4OH to the sol, promoting gelation of sol in sealed plastics containers. Part of the gels samples was analyzed by TG, DTS and DSC techniques in order to characterize water loss and degradation of the polymeric “epoxy” groups present in the structure of the silica derived from the GPTS alkoxide. Another set of samples was dried at 80oC/48h to obtain xerogels (dried gels) and analyzed by the same techniques. We obtained the characteristics temperatures of the matrix by the techniques DTA, DSC and TG, under measurements of thermal analysis until 800oC and 600oC in case of DSC. By thermal analysis (TG, DTA, and DSC) the main endothermic events (loss of water, melting, pyrolysis) and exothermic events (burning of the polymer) of the GPTS-TEOS matrix were determined

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Pós-graduação em Odontologia Restauradora - ICT