Effect of particle polydispersity on the irreversible adsorption of fine particles on patterned substrates

We performed extensive Monte Carlo simulations of the irreversible adsorption of polydispersed disks inside the cells of a patterned substrate. The model captures relevant features of the irreversible adsorption of spherical colloidal particles on patterned substrates. The pattern consists of (equal) square cells, where adsorption can take place, centered at the vertices of a square lattice. Two independent, dimensionless parameters are required to control the geometry of the pattern, namely, the cell size and cell-cell distance, measured in terms of the average particle diameter. However, to describe the phase diagram, two additional dimensionless parameters, the minimum and maximum particle radii are also required. We find that the transition between any two adjacent regions of the phase diagram solely depends on the largest and smallest particle sizes, but not on the shape of the distribution function of the radii. We consider size dispersions up-to 20% of the average radius using a physically motivated truncated Gaussian-size distribution, and focus on the regime where adsorbing particles do not interact with those previously adsorbed on neighboring cells to characterize the jammed state structure. The study generalizes previous exact relations on monodisperse particles to account for size dispersion. Due to the presence of the pattern, the coverage shows a non-monotonic dependence on the cell size. The pattern also affects the radius of adsorbed particles, where one observes preferential adsorption of smaller radii particularly at high polydispersity.Comment: 9 pages, 5 figure

Produção de mudas de vinca e pimenta ornamental em substratos à base de resíduos orgânicos agroindustriais e agropecuários.

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Desenvolvimento de mudas de pinhão-manso (Jatropha curcas L.) submetidas a diferentes substratos e sombreamentos.

Este trabalho teve como objetivo avaliar o efeito de diferentes substratos e níveis de sombreamento no desenvolvimento de mudas de pinhão-manso (Jatropha curcas L. Os frutos foram colhidos em uma área comercial. Após beneficiamento e assepsia, duas sementes foram semeadas em sacos de polietileno de aproximadamente 3 litros, preenchidos com quatro diferentes substratos. Sendo eles, solo (S); areia (A); S1-A1-NPK (solo + areia, na proporção de 1:1, com 5 g de NPK 6:24:12 por litro de substrato); S1-A2-NPK (solo + areia, na proporção de 1:2, com 5 g de NPK 6:24:12 por litro de substrato); S1-A1-E1 (solo + areia + esterco curtido, na proporção de 1:1:1); S1-A1-E1 NPK (solo + areia + esterco curtido, na proporção de 1:1:1, com 5 g de NPK 6:24:12 por litro de substrato). O experimento foi conduzido em três diferentes intensidades de sombreamento: 0% (a céu aberto), 25% e 75% (em telado, com tela sombrite). O delineamento utilizado foi em blocos casualizados, em um esquema fatorial 4 x 3 (quatro substratos x três sombreamentos), perfazendo um total de 12 tratamentos. As plântulas mantidas em sombreamento de 25% apresentaram, em geral, melhores resultados para todas as variáveis avaliadas. Conclui-se que tanto o sombreamento como o substrato interferiram na emergência da espéci

Screening effects in flow through rough channels

A surprising similarity is found between the distribution of hydrodynamic stress on the wall of an irregular channel and the distribution of flux from a purely Laplacian field on the same geometry. This finding is a direct outcome from numerical simulations of the Navier-Stokes equations for flow at low Reynolds numbers in two-dimensional channels with rough walls presenting either deterministic or random self-similar geometries. For high Reynolds numbers, when inertial effects become relevant, the distribution of wall stresses on deterministic and random fractal rough channels becomes substantially dependent on the microscopic details of the walls geometry. In addition, we find that, while the permeability of the random channel follows the usual decrease with Reynolds, our results indicate an unexpected permeability increase for the deterministic case, i.e., ``the rougher the better''. We show that this complex behavior is closely related with the presence and relative intensity of recirculation zones in the reentrant regions of the rough channel.Comment: 4 pages, 5 figure

Gravity with extra dimensions and dark matter interpretation: Phenomenological example via Miyamoto-Nagai galaxy

A configuration whose density profile coincides with the Newtonian potential for spiral galaxies is constructed from a 4D isotropic metric plus extra dimensional components. A Miyamoto-Nagai ansatz is used to solve Einstein equations. The stable rotation curves of such system are computed and, without fitting techniques, we recover with accuracy the observational data for flat or not asymptotically flat galaxy rotation curves. The density profiles are reconstructed and compared to that obtained from the Newtonian potential.Comment: 10 pages, 10 figures, submitted to Brazilian Journal of Physic

The role of cinema on the tourist destination image formation process

Tourism literature widely acknowledges that images of tourist destinations are a product of all the experiences of an individual, being influenced by a series of information sources. The movies figure amongst this sources, and as an autonomous information agent, which in theory are not associated with the tourist market interests, they transmit information that is perceived as more reliable than conventional publicity. Thus, cinema acts directly on the organic image, creating and perpetuating associations about the places it depicts on the collective imagery. The present article aims to provide a bibliographical state of the art about the influence of films on the tourist destinations’ image, contextualizing the cinema on it’s formation process, as well as the cognitive and phsycological processes involved

Frações da matéria orgânica do solo no cerrado sob sistema agroflorestal no Nordeste do Brasil.

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