ABSTRACT The phenomena of infiltration and the percolation of water in the soil are of fundamental importance for the evaluation of runoff, groundwater recharge, evapotranspiration, soil erosion and transport of chemical substances in surface and groundwater. Within this context, the quantitative determination of the infiltration values is extremely important for the different areas of knowledge, in order to evaluate, mainly the surface runoff. Several types of changes in vegetation cover and topography result in significant changes in the infiltration process, making it necessary to use mathematical models to assess the consequences of these changes. Thus, this paper aims to implement the Green-Ampt model using two numerical methods - Newton-Raphson method and W-Lambert function - to determine soil permeability parameters - K and matric potential multiplied by the difference between initial and of saturation - ψ∆θ comparing them to the real data obtained in simulations using an automatic rainfall simulator from the Federal University of Goiás - UFG. The Green-Ampt model adjusted well to the data measured from the rain simulator, with a determination coefficient of 0.978 for the Newton-Raphson method and 0.984 for the W-Lambert function.

Resumo O uso de nanopartículas é uma tendência recente que pode assumir um papel importante para melhorar o desempenho mecânico do cimento Portland. O objetivo deste estudo é avaliar o efeito da nanossílica na matriz de cimento Portland. A distribuição do tamanho das partículas da matriz de cimento Portland foi modificada pela incorporação de 11, 6.2, 3.1, 1.7, 0.85 a 0.42%, em massa, de nanossílica. A demanda de água e o consumo de aditivo dispersante foram ajustados, e as propriedades reológicas das suspensões foram analisadas por meio de reometria rotacional. O desempenho mecânico das misturas foi avaliado pela resistência à compressão. A distribuição do tamanho dos poros foi medida por porosimetria de intrusão de mercúrio, e a hidratação foi analisada por difratometria de raios-X. O comportamento reológico apresentou uma mudança considerável, como consequência da elevada área superficial específica das nanopartículas. O teor ótimo de nanossílica, ou a menor quantidade de nanopartículas, que leva ao maior ganho de resistência, variou de acordo com a relação água/sólidos. Um aumento na hidratação e o refinamento dos poros foram obtidos pelo uso da nanossílica. O efeito de empacotamento e a pozolanicidade são os principais efeitos da nanossílica na microestrutura da matrix de cimento Portland.

Abstract The use of nano-particles is a current trend that may play an important role for improving the mechanical performance of Portland cement. The aim of this study is to evaluate the effect of nano-silica on Portland cement matrix. The particle size distribution of Portland cement matrix was modified by the incorporation of 11, 6.2, 3.1, 1.7, 0.85 and 0.42 wt.% of nano-silica. The water demand and the consumption of dispersant were adjusted, and the rheological properties of suspensions were analyzed through rotational rheometry. The mechanical performance of studied mixtures was evaluated by the compressive strength. The pore size distribution was measured by mercury intrusion porosimetry (MIP), and the hydration was analyzed through X-ray diffractometry. The rheological behavior presented a considerable changed, as a consequence of high specific surface area of nano-particles. The optimum content of nano-silica, or the smaller quantity of nano-particles, that leads to the maximum strength gain, varied according to the water to solids ratio. An increasing on the hydration and a pore refinement were obtained due to the use of silica nanoparticles. The particle’s packing and the pozzolanic reaction were the two main effects of nano-silica on the microstructure of Portland cement matrix.

Resumo O uso de nanopartículas em concretos de ultra-alta resistência pode resultar em um efeito positivo no desempenho mecânico destes materiais cimentíceos. Neste estudo foram avaliadas matrizes cimentíceas contendo 10 e 20% de microssílica, para as quais foi determinado o teor ótimo de nanossílica, i.e. a quantidade de nanossílica que resultou no maior ganho de resistência. A caracterização física das matérias-primas foi realizada em termos de distribuição do tamanho das partículas, densidade e área superficial específica. As composições química e mineralógica dos materiais foram determinadas por meio de fluorescência e difração de raios X. O desempenho mecânico das misturas foi avaliado por meio da medição de resistência à compressão, resistência à tração na flexão e módulo de elasticidade dinâmico. A análise microestrutural das amostras contendo nanossílica foi realizada por meio de difração de raios X, termogravimetria, porosimetria de intrusão de mercúrio e microscopia eletrônica de varredura. Os resultados obtidos indicaram um teor ótimo de 0,62% de nanossílica, considerando resistências à tração na flexão ou à compressão. Este ganho de desempenho foi diretamente relacionado a dois aspectos microestruturais importantes: o efeito de empacotamento e a reação pozolânica da nanossílica.

Abstract The use of nanoparticles in ultra-high strength concretes can result in a positive effect on mechanical performance of these cementitious materials. This study evaluated mixtures containing 10 and 20 wt% of silica fume, for which the optimum nano-silica content was determined, i.e. the quantity of nano-silica that resulted on the higher gain of strength. The physical characterization of raw materials was done in terms of particle size distribution, density and specific surface area. Chemical and mineralogical compositions of materials were obtained through fluorescence and X-ray diffraction. The mechanical performance was evaluated by compressive strength, flexural strength and dynamic elastic modulus measurements. The microstructural analysis of mixtures containing nano-silica was performed by X-ray diffraction, thermogravimetry, mercury intrusion porosimetry and scanning electron microscopy. Obtained results indicate an optimum content of nano-silica of 0.62 wt%, considering compressive and flexural strengths. This performance improvement was directly related to two important microstructural aspects: the packing effect and pozzolanic reaction of nano-silica.

Resumo Atualmente, os códigos ambientais restringem a emissão de material particulado, resultando em um resíduo coletado por filtros. Este resíduo basáltico é proveniente de plantas de produção de agregados para construção, situadas na Região Metropolitana de Londrina, PR (Brasil). Inicialmente, o resíduo basáltico foi submetido a peneiramento (< 75 µm) e o pó obtido foi caracterizado em termos de distribuição do tamanho das partículas. A plasticidade de massas cerâmicas contendo 0, 10, 20, 30, 40 e 50% de resíduo basáltico foi medida pelo método de Atterberg. A composição química de formulações cerâmicas contendo 0 e 20% de resíduo basáltico foi determinada por meio de fluorescência de raios X. Corpos de prova prismáticos foram moldados por extrusão e queimados a 850 °C, e determinadas a densidade, a absorção de água, as retrações na secagem e na queima, a resistência à tração na flexão e o módulo de Young das amostras. A microestrutura foi avaliada por microscopia eletrônica de varredura, difração de raios X e porosimetria de intrusão de mercúrio. O pó de basalto apresenta características físicas e químicas similares quando comparado às outras matérias-primas, e contribui para o processamento cerâmico pela redução das retrações na secagem e na queima. O desempenho mecânico da mistura contendo pó basáltico é equivalente à mistura sem pó. Aspectos microestruturais, como a distribuição do tamanho dos poros, são modificados pelo pó basáltico; a fase albita relacionada ao pó de basalto foi identificada por meio de difração de raios X.

Abstract Nowadays, environmental codes restrict the emission of particulate matters, which result in these residues being collected by plant filters. This basaltic waste came from construction aggregate plants located in the Metropolitan Region of Londrina (State of Paraná, Brazil). Initially, the basaltic waste was submitted to sieving (< 75 μm) and the powder obtained was characterized in terms of density and particle size distribution. The plasticity of ceramic mass containing 0%, 10%, 20%, 30%, 40% and 50% of basaltic waste was measured by Atterberg method. The chemical composition of ceramic formulations containing 0% and 20% of basaltic waste was determined by X-ray fluorescence. The prismatic samples were molded by extrusion and fired at 850 °C. The specimens were also tested to determine density, water absorption, drying and firing shrinkages, flexural strength, and Young's modulus. Microstructure evaluation was conducted by scanning electron microscopy, X-ray diffraction, and mercury intrusion porosimetry. Basaltic powder has similar physical and chemical characteristics when compared to other raw materials, and contributes to ceramic processing by reducing drying and firing shrinkage. Mechanical performance of mixtures containing basaltic powder is equivalent to mixtures without waste. Microstructural aspects such as pore size distribution were modified by basaltic powder; albite phase related to basaltic powder was identified by X-ray diffraction.

Hemophagocytic Syndrome is a clinical condition characterized by the activation of either macrophages or histiocytes with a prominent hemophagocytosis feature in the bone marrow and other reticuloendothelial systems. It leads to the phagocytosis of erythrocytes, leukocytes, platelets and their precursors. The presence of hemophagocytosis can be associated to infections, malignancies, autoimmune diseases, drugs and a variety of other medical conditions. We report a case of a previously healthy 36 year-old woman that developed hemophagocytosis at the same time that fulfilled diagnostic criteria for systemic lupus erythematosus. Lupus related hemophagocytic syndrome is a rare and potentially fatal entity. It offers significant differential diagnosis challenges and requires urgent therapeutic intervention. There are only few cases reported in the literature. However, much is still needed in order to better understand its causes, all the immunopathogenic mechanisms, as well as its clinical and therapeutic aspects.

La hemofagocitosis es un cuadro clínico caracterizado por la activación de los macrófagos y histiocitos, con intensa actividad fagocítica en la médula ósea e otras localizaciones del sistema reticuloendotelial, lo que provoca la fagocitosis de los eritrocitos, leucocitos, plaquetas y sus precursores. Su presencia puede estar asociada con infecciones, neoplasias, enfermedades autoinmunitarias, drogas y una variedad de otras condiciones médicas. En este caso clínico, presentamos a una mujer de 36 años, previamente sana, que desarrolló hemofagocitosis, al mismo tiempo que completó los criterios de diagnóstico de lupus eritematoso sistémico. La hemofagocitosis asociada con el lupus es una entidad rara, potencialmente mortal, de diagnóstico diferencial complicado y, que requiere una intervención terapéutica urgente. Hay muy pocos casos comunicados en la literatura, y es necesaria una mejor comprensión de los aspectos clínicos, causas, fisiopatología, criterios de diagnóstico y tratamiento de este síndrome.

We propose a new local algorithm for the thermalization of n-vector spin models, which can also be used in the numerical simulation of SU(N) lattice gauge theories. The algorithm combines heat-bath (HB) and micro-canonical updates in a single step - as opposed to the hybrid overrelaxation method, which alternates between the two kinds of update steps - while preserving ergodicity. We test our proposed algorithm in the case of the one-dimensional 4-vector spin model and compare its performance with the standard HB algorithm and with other HB-inspired algorithms.

Percolation theory is of interest in problems of phase transitions in condensed matter physics, and in biology and chemistry. More recently, concepts of percolation theory have been invoked in studies of color deconfinement at high temperatures in Quantum Chromodynamics. In the present paper we briefly review the basic concept of percolation theory, exemplify its application to the Ising model, and present the arguments for a possible relevance of percolation theory to the problem of color deconfinement.