Repositório RCAAP

The tomato crop is a one of the highest expressed cultivation in the world; however, various pests may attack the crop. The bacterial spot, caused by the bacterium Xanthomonas spp., is one of the most important diseases that cause losses in yield and quality of tomato and one of the most effective ways to control the disease currently is the use of pathogen-free seeds. This paper studied a new type of seed treatment, effective in controlling fitobactérias. A study in vitro was performed of the photodynamic activity of the dyes Methylene Blue, Toluidine Blue and a combination of both dyes in various concentrations, containing a suspension of Xanthomonas spp. The tested dyes are able to inhibit bacterial growth effectively, under irradiation conditions and with all concentrations tested. In this work we developed a seed treatment, and the method tested was effective in controlling bacteria without causing damage quality physiological seed, figuring a new type of seed treatment that avoids the use of pesticides.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

In this work, we studied the corrosion protection efficiency of low carbon steel in synthetic sea water containing inhibitors (commercial and 2,5-dimercapto-1, 3,4 - thiadiazol-DMcT-) at different concentrations. From the analysis of optical emission spectrometer, metallography and microhardness, it was possible to classify the steel sample as low carbon. From the results obtained from the Nyquist diagram, it can be concluded that there is a significant increase in the charge transfer resistance (Rct) values of steel in the presence of higher concentrations of inhibitors. High Rct values were obtained for the steel in synthetic sea water containing 200 ppm of both inhibitors when subjected to an exposure time of 20 h, indicating the coating of the steel by inhibitor film which was confirmed by SEM. Furthermore, in the polarization curves was observed a shift of the corrosion potential to more positive values for the concentration of 200 ppm as compared to the other concentrations. At this concentration, DMcT inhibitor performance was superior to the commercial, obtaining a value of inhibitor efficiency around of 99%. From these results, we can say that the DMcT with concentration of 200 ppm is quite promising as inhibiting corrosion of low carbon steel. As for this commercial inhibitor concentration is not recommended due to high toxicity presented by their constituents. Then, the concentration for commercial inhibitor more suitable is of 100 ppm. The theoretical data of the proposed circuit is adjusted to the experimental data obtained by EIS for both inhibitors, yielding a chi square of 10-2 and 10-3 for the commercial inhibitor and DMcT, respectively. These values are considered acceptable for a good fit and the circuit presented a physical meaning consistent with the realized analyzes. The DMcT has certain advantages compared to other commonly used inhibitors such as low cost, low toxicity to the environment, besides, it is fungicide and bactericide. Therefore, it is a material promising as an inhibitor for corrosion of low carbon steel, even at higher concentration than those used for commercial inhibitor.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

In this work, films of starch and blends of starch/natural rubber latex were produced and characterized by physicochemical properties and evaluation of the water Vapor Permeation. The characterization techniques used were Fourier Transformed Infrared spectroscopy (FTIR), X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM). The spectra in the infrared region of the blends showed changes in the profile and displacement of the absorption bands near 3500 cm-1 when compared to starch films. These modifications are related to changes in the pattern of hydrogen bonds with the addition of latex and glycerol in blends with plasticizer due to the mixing process. These changes are more significant for the blends starch/Latex 50/50% (m/m) (A50/L50) and starch/latex /glycerol 50/48/2 (m/m) (A50/L48/G2). The water permeation results showed a reduction in permeation of the blends and this amount was reduced by about 50% in the blend A50/L50 aspect expected since the blends are more hydrophobic by inserting natural rubber. The application of Parallel Model for immiscible blends for prediction water permeability was best suited to the system since the experimental values were close to the theoretical values, especially for the blends with glycerol. The blends prepared without glycerol present deviations that are associated with the formation of porous structures resulting from the mixing process and possible phase segregation, which facilitate the transport of water by the blend. This was confirmed from the evaluation of the SEM. The micrographs showed phase separation for films with a high percentage of latex. For higher starch content, the blends are more uniform. The DRX and DSC results show that starch undergoes changes in the mixture with latex due to the presence of hydrophilic components. The natural rubber, in other hand, maintain the same value of glass transition temperature, Tg, this aspect indicates low interaction of this polymer with starch and other components of the blend. However, the addition of natural rubber leads to an increased thermal stability and reduced water absorption. The results showed that the A50/L50 blend with and without glycerol, displays the desired physical properties and is therefore compatible. Thus, the blend in question is the starting point for improving the performance of these systems.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coffee is considered one of Brazil s most important commodities and, therefore, its quality is very important. This product must present physical, chemical and sensorial properties according to established standards to reach the quality degree for exportation. Among the several factors that influence the quality of coffee, the presence of defective beans (black, green and sour beans (BGS)) must be avoided. Thus, the aim of this dissertation was to obtain a chemical differentiation between good and defective roasted beans. To study that, samples from Minas Gerais s cerrado and from the South of this state were used. They were roasted until three different degrees (mild, medium and strong roasting). The results showed that beverages prepared from BGS beans were more acid due to fermentative processes, and more astringent due to higher content of phenolic compounds, proanthocyanidins and chlorogenic acids. Moreover, the presence of defective beans reduces the essential oil concentration, but increases the content of undesirable substances for the aroma, as low molecular weight aldehydes and sulfides. These beans are rich in olefins and saturated chains. However, the matrixes of the defective and good beans are similar, being basically composed by sugars, phenols, carboxylic acids and caffeine.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Photodynamic therapy (PDT) is a treatment for cancer and certain non-malignant diseases, which are generally characterized by overgrowth of unwanted or abnormal cells. This technique uses a photosensitizer, light and oxygen to inactivate cells. In this work the photodynamic effects of synthetic photosensitizers chloroaluminum phthalocyanine, zinc phthalocyanine, methylene blue and toluidina blue and crude and parcially fracionated extracts of Bidens sulphurea, known as \"Picão laranja\" over Saccharomyces cerevisiae cultures was studied, because this yeast has a great energetic and structural similarity to cancer cells. To enhance the activity of the photosensitizers were used additives as Moringa oleifera agglutinating protein and albumin and these drugs were also encapsulates in phosphatidylcoline liposomes with cholesterol, poliethyleneglicol and albumin. The times of incubation and irradiation, the distance between the irradiation systems and the cells and the minimum inhibitory concentration of the photosensitizers were also standardized. The results showed that the Moringa oleifera agglutinating proteins were more efficient than liposome as Drug Delivery Systems. The extracts of Bidens sulphurea showed to be efficient to the photodynamic inactivation, being a potential source for the search for new photosensitizers.