Considerando-se a crescente participação dos vegetais na transmissão de microrganismos, incluindo as Escherichia coli enteropatogênicas multirresistentes às drogas convencionais, a busca por novos compostos com propriedades antimicrobianas a partir de fontes naturais, tais como os óleos essenciais, tem se intensificado nos últimos anos. Esta pesquisa objetivou avaliar a atividade antibacteriana do óleo essencial do manjericão (Ocimum basilicum Linn.) frente a sorogrupos de Escherichia coli enteropatogênicas (EPEC) isolados de alfaces (Lactuca sativa), utilizando-se o Método de Difusão em Disco (MDD). Os resultados evidenciaram que todas as cepas de E. coli EPEC testadas apresentaram sensibilidade à ação do óleo essencial, sugerindo que este possa ser uma fonte de compostos com potencial terapêutico no combate a bactérias patogênicas.

Considering the increase of the involvement of vegetables in the transmission of microorganism including the enteropathogenic Escherichia coli multiresistance to conventional drugs, the search for new antimicrobial compounds from natural sources, such as the essential oils, has been intensified in the last years. This research aimed to evaluate the antibacterial activity of the essential oil from basil (Ocimum basilicum Linn.) front to sorogroups of enteropathogenic Escherichia coli (EPEC) isolated in lettuces (Lactuca sativa) using the Diffusion in Disk Method. The results showed that, all the tested strains of E. coli EPEC presented sensitivity to the essential oil's action, suggesting that it can be a source of compounds with therapeutic potential in the fighting to bacteria pathogenic.

In this work, aqueous suspensions of aluminas with different particle sizes were evaluated. The effect of pH on the electrosteric stabilization using PMAA-NH4 (ammonium polymethacrylate) as deflocculant was studied. The amount of deflocculant was optimized and rheologic properties were determined at four different pH values. Sedimentation was also evaluated. For suspensions with pH 4, an electrostatic mechanism of stabilization was observed, probably due to a flat adsorption of PMMA- on the alumina surface, leading to a small efficiency in relation to steric stabilization. For a suspension with pH 12, the steric mechanism of stabilization prevails. Suspensions with pH 7 and 9 present a higher flocculation degree. In relation to particle size, A-1000 samples present a smaller particle size, leading to a smaller interparticle distance (IPS), making stabilization more difficult.

A poluição de uma bacia hidrográfica pode causar alterações das propriedades físicas, químicas e biológicas da massa de água, comprometendo o seu uso para o consumo humano e para outros tipos de atividades, dependendo do grau de poluição ou contaminação. Os métodos de tratamentos convencionais de efluentes contendo metais pesados produzem quantidades significativas de subprodutos com características recalcitrantes, além de serem técnicas onerosas e de reprodutibilidade baixa. A busca por soluções mais baratas e definitivas levou ao desenvolvimento de tecnologias limpas, dentre estas tecnologias destaca-se o processo de sorção que baseia-se na utilização de substâncias absorventes desses elementos químicos. Este trabalho teve como objetivo avaliar o processo de sorção de metais pesados pelos resíduos sólidos orgânicos utilizando-se das técnicas de termogravimetria. Os resultados obtidos demonstraram que os perfis das curvas da termogravimetria dos resíduos sólidos orgânicos apresentam modificações significativas nas características físicas e químicas, quando submetidas ao processo de sorção dos metais pesados.

Pollution of a hydrographic basin can cause alterations in physical, chemical and biological properties of water mass, committing its use for the human consumption and for other types of activities, depending on the contamination or pollution level. The conventional treatment methods for effluents containing heavy metals produce significant amounts of byproducts with recalcitrant characteristics; besides the techniques being onerous their reproducibility is low. The search for cheaper and definitive solutions led to the development of clean technologies, among these technologies the sorption process based on utilization of absorbent substances for these elements can be pointed out. This work has the objective of evaluating the sorption process of heavy metals by organic solid waste utilizing the thermogravimetric technique. The results obtained demonstrated that the profiles of the thermogravimetric curves of the organic solid waste presented significant modifications in the physical and chemical characteristics when submitted to the heavy metal sorption process.

Oxides with spinel structures have been studied for many decades as they have been used in a variety of applications like pigments and refractories. They have also been used as a model structure to evaluate the relative stability of ions in octahedral and tetrahedral sites. Zinc- antimony spinels (Zn7Sb2O12) were synthesized by the Pechini method and the cation Zn2+ was substituted by Co2+, taking into consideration the stoichiometry of Co xZn7-xSb2O12 (x = 0 - 7). Characterization of the thermal properties of pyrolyzed powders was carried out with a TG/DTA analyzer, and mass losses were determined as a function of the cobalt content in the resin. The powders were calcined at temperatures in the range 600 to 1000 °C and characterized by XRD, BET and IR spectroscopy. Maximum cristalinity was obtained in powders calcined at 1000 °C. Materials with x = 5 - 7 revealed the presence of a secondary phase (Co, Zn)Sb2O6. Infrared analysis facilitated in the determination of the possible sites of Zn2+, Co2+ and Sb2+ ions in the lattice.

Humidity and ash content of powder and bran of algaroba pods are important quality parameters for biological control during storage. The studies of humidity and ash content were carried out conventional and thermogravimetric methods. Different values were obtained by the various methods. The thermogravimetric method was faster and required less sample for the humidity and ash analyses of the powder and bran of algaroba pods. The differential scanning calorimetry curves of the powder and bran of algaroba pods, dryed at 55 ºC, showed two peaks, one corresponding to the gelatinization of starch and the other to the vaporization of water. The samples dryed at 65, 75, 85, 95 and 105 ºC showed one peak, corresponding to the vaporization of water.

Diversos tipos de poliestireno modificados foram obtidos através da polimerização por enxertia (graft polymerization) de estireno na presença dos seguintes modificadores: copolímero de etileno-acetato de vinila (EVA); polietileno de baixa densidade (PE) e polibutadieno (PB). Os modificadores foram utilizados em separado e combinados. Em todos os casos, manteve-se a concentração de modificador fixa em 8% em peso e foram avaliadas as propriedades dos produtos obtidos em função da sua composição. A técnica de polimerização empregada foi a de massa/suspensão. Os melhores resultados foram obtidos para os sistemas PS/modificadores mistos. Os resultados obtidos para estes sistemas comprovam que a copolimerização por enxertia gera produtos com melhores propriedades de impacto do que as obtidas, a partir de misturas mecânicas dos componentes individuais, em sistemas semelhantes.

Several grades of modified polystyrene were obtained through the graft polymerization of styrene in the presence of modifiers such as ethylene-vinyl acetate (EVA), low density polyethylene (PE), and polybutadiene (PB). These modifiers were used by themselves and in combination. In all cases, the modifier concentration was kept constant at 8% w/w, and the product properties were determined as a function of composition. The polymerization technique employed was that of mass/suspension. The best results were obtained for the PS/mixed modifiers systems. The results confirm that graft copolymers present better impact properties than those of mechanical blends of similar composition.