Mapping the train model for earthquakes onto the stochastic sandpile model

We perform a computational study of a variant of the ``train'' model for earthquakes [PRA 46, 6288 (1992)], where we assume a static friction that is a stochastic function of position rather than being velocity dependent. The model consists of an array of blocks coupled by springs, with the forces between neighbouring blocks balanced by static friction. We calculate the probability, P(s), of the occurrence of avalanches with a size s or greater, finding that our results are consistent with the phenomenology and also with previous models which exhibit a power law over a wide range. We show that the train model may be mapped onto a stochastic sandpile model and study a variant of the latter for non-spherical grains. We show that, in this case, the model has critical behaviour only for grains with large aspect ratio, as was already shown in experiments with real ricepiles. We also demonstrate a way to introduce randomness in a physically motivated manner into the model.Comment: 14 pages and 6 figures. Accepted in European Physical Journal

Lattice Simulation of Nuclear Multifragmentation

Motivated by the decade-long debate over the issue of criticality supposedly observed in nuclear multifragmentation, we propose a dynamical lattice model to simulate the phenomenon. Its Ising Hamiltonian mimics a short range attractive interaction which competes with a thermal-like dissipative process. The results here presented, generated through an event-by-event analysis, are in agreement with both experiment and those produced by a percolative (non-dynamical) model.Comment: 8 pages, 3 figure

Physicochemical characterization of moringa oleífera’s shells as biosorbent for pharmaceuticals biosorption

Pharmaceuticals as emerging contaminants have become one of the most controversial environmental issues at global scale. Over the years, the presence of antibiotics and antiinflammatory drugs in rivers, lakes, and even in drinking water streams has increased. The waste water treatment plants (WWTPs) lack the necessary technology to remove concentrations within the range ng/l-mg/l and therefore, the need to develop new methods able to remove contaminants in an effective, low cost and environmental friendly way arises. “Biosorption” appears as a possible solution. The present work is focused on studying the potential adsorption capacity of Moringa oleífera (MO) to remove Diclofenac (DCF) and Oxytetracycline (OTC) from wastewater. Through different experiences, it was possible to characterizes the main functional groups of MO and determine the principal responsible of the adsorption process.info:eu-repo/semantics/publishedVersio