Desenho e relevo

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Baixo-relêvo: o método das projeções centrais

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Necrose

Sin resume

SUSY partners and SS-matrix poles of the one dimensional Rosen-Morse II Hamiltonian

Among the list of one dimensional solvable Hamiltonians, we find the Hamiltonian with the Rosen-Morse II potential. The first objective is to analyze the scattering matrix corresponding to this potential. We show that it includes a series of poles corresponding to the types of redundant poles or anti-bound poles. In some cases, there are even bound states and this depends on the values of given parameters. Then, we perform different supersymmetric transformations on the original Hamiltonian using the ground state (for those situations where there are bound states) wave functions, or other wave functions that comes from anti-bound states or redundant states. We study the properties of these transformations.Comment: 20 pages, 6 figure

Removal of 1,4-dioxane from industrial wastewaters: routes of decomposition under different operational conditions to determine the ozone oxidation capacity.

This paper denotes the importance of operational parameters for the feasibility of ozone (O3) oxidation for the treatment of wastewaters containing 1,4-dioxane. Results show that O3 process, which has formerly been considered insufficient as a sole treatment for such wastewaters, could be a viable treatment for the degradation of 1,4-dioxane at the adequate operation conditions. The treatment of both synthetic solution of 1,4-dioxane and industrial wastewaters, containing 1,4-dioxane and 2-methyl-1,3-dioxolane (MDO), showed that about 90% of chemical oxygen demand can be removed and almost a total removal of 1,4-dioxane and MDO is reached by O3 at optimal process conditions. Data from on-line Fourier transform infrared spectroscopy provides a good insight to its different decomposition routes that eventually determine the viability of degrading this toxic and hazardous compound from industrial waters. The degradation at pH>9 occurs faster through the formation of ethylene glycol as a primary intermediate; whereas the decomposition in acidic conditions (pH<5.7) consists in the formation and slower degradation of ethylene glycol diformate

Direct Production of Cellulose Nanocrystals from Old Newspapers and Recycled Newsprints

Cellulose nanocrystals (CNC) are high added value products which can be used in many applications. In this research, CNC were directly produced from two recycled papers: old newspapers (ONP) and 100% recycled newsprint (NP). CNC were also obtained from NP by previously isolating the cellulose particles by alkali and bleaching treatments. CNC yield and quality was assessed through lignin and ash determination, X-ray diffraction analysis, atomic force microscopy and thermogravimetric analysis. Not only crystallinities resulted similar (92-95%), but also aspect ratios (L/d) (each in the range of 50-120). However, different CNC purities and hydrolysis and process yields were obtained. Thus, CNC purity decreased from 93 to 77%, hydrolysis yield was reduced from 64 to 58% but process yield strongly improved from 35 to 60% when no pretreatment was used. Therefore, this study proves the viability of the direct production of CNC from recycled papers

Internal Treatment of Process Waters in Paper Production by Dissolved Air Flotation with Newly Developed Chemicals. 1. Laboratory Tests

New chemicals, based on the synergistic effect between inorganic polyaluminium salts and organic cationic polyelectrolytes, have been tested for the chemical optimization of a dissolved air flotation (DAF) unit, used as internal treatment of process waters in a paper mill based on 100% recovered paper. Laboratory tests have demonstrated that polyamine modifications of the aluminum salts are the most efficient in the removal of contaminants, the combination of a polyaluminium nitrate sulfate salt and a polyamine being the most efficient. This chemical has been studied under different conditions, such as different dosages or in combination with a flocculant for the treatment of waters from different paper grades production, and the results have demonstrated a good performance at laboratory scale. Therefore, a field trial has been recommended for assessing its potential benefits at mill scale, which will be described in a future paper

Aprovechamiento de la lejias residuales resultantes del decapado del hierro con ácido clorhidrico para la obtención de pigmentos

El objetivo de la investigación que se presenta en esta memoria es proponer un procedimiento para tratar las lejías residuales procedentes del decapado del hierro en bandas con ácido clorhídrico, en el que se recupera el hierro en forma de pigmentos que puedan ser utilizados en la industria de pinturas. Con ello, además de reducir la contaminación acuosa, se logra la revalorización del residuo ferroso. Se llega a la conclusión de que el proceso propuesto es valido por el rendimiento de recuperación del fe, por la velocidad de reacción y por la calidad de los productos obtenidos, pudiendo con la investigación desarrollada seleccionar las condiciones óptimas de oxiprecipitación para obtener los máximos rendimientos de eliminación de fe y productos sólidos de contrastada calidad pigmentaria.Depto. de Ingeniería Química y de MaterialesFac. de Ciencias QuímicasTRUEpu

Effects of Chlorpyrifos Over Reproductive Traits of Three Sympatric Freshwater Crustaceans

The exposure to environmentally relevant chlorpyrifos concentrations (0.03, 0.06 and 0.12 µg chlorpyrifos L−1) causes increases in precopulatory guardian behavior time, amplexus reformulation after exposure and in the number of ovigerous females in the amphipod Hyalella curvispina. Effects in incubation period, effective hatching and median lethal concentration on the decapods Macrobrachium borellii and Aegla uruguayana, both in adults and embryos, were achieved at higher concentrations than those found in the environment. Environmentally relevant chlorpyrifos concentrations appear not to affect decapods but several effects in reproductive traits of amphipods were observed.Fil: Negro, Carlos Leandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Estrubia, J. F.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Rivera, F.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Collins, Pablo Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentin