Dynamics of a continuous flash fermentation for butanol production

The ABE (acetone, butanol, ethanol) fermentation is characterized by its low productivity. In this paper, this issue is overcome with an innovative industrial process that employs the flash fermentation technology. The process consists of three interconnected units, as follows: fermentor, cell retention system (tangential microfiltration) and vacuum flash vessel (responsible for the continuous recovery of butanol from the broth). The dynamic behaviour of the process is described by a nonlinear mathematical model with kinetic parameters determined experimentally. From simulations of the mathematical model the dynamic characteristics of the process were investigated. Analyzes of the open-loop dynamic behavior of the process, after step perturbations in the manipulated variables, determined the best control structures for the process. Copyright © 2010, AIDIC Servizi S.r.l.

GRASP with evolutionary path-relinking for the capacitated arc routing problem

The Capacitated Arc Routing Problem (CARP) is a well-known NP-hard combinatorial optimization problem where, given an undirected graph, the objective is to find a minimum cost set of tours servicing a subset of required edges under vehicle capacity constraints. There are numerous applications for the CARP, such as street sweeping, garbage collection, mail delivery, school bus routing, and meter reading. A Greedy Randomized Adaptive Search Procedure (GRASP) with Path-Relinking (PR) is proposed and compared with other successful CARP metaheuristics. Some features of this GRASP with PR are (i) reactive parameter tuning, where the parameter value is stochastically selected biased in favor of those values which historically produced the best solutions in average; (ii) a statistical filter, which discard initial solutions if they are unlikely to improve the incumbent best solution; (iii) infeasible local search, where high-quality solutions, though infeasible, are used to explore the feasible/infeasible boundaries of the solution space; (iv) evolutionary PR, a recent trend where the pool of elite solutions is progressively improved by successive relinking of pairs of elite solutions. Computational tests were conducted using a set of 81 instances, and results reveal that the GRASP is very competitive, achieving the best overall deviation from lower bounds and the highest number of best solutions found. © 2011 Elsevier Ltd. All rights reserved.

Progressive recovery of a tropical deforested stream community after a flash flood

AIM: In this study, we evaluated and compared community attributes from a tropical deforested stream, located in a pasture area, in a period before (PRED I) and three times after (POSD I, II, and III) a flash flood, in order to investigate the existence of temporal modifications in community structure that suggests return to conditions previous to the flash flood. METHODS: Biota samples included algae, macrophytes, macroinvertebrates, and fish assemblages. Changes in stream physical structure we also evaluated. Similarity of the aquatic biota between pre and post-disturbance periods was examined by exploratory ordination, known as Non-Metric Multidimensional Scaling associated with Cluster Analysis, using quantitative and presence/absence Bray-Curtis similarity coefficients. Presence and absence data were used for multivariate correlation analysis (Relate Analysis) in order to investigate taxonomic composition similarity of biota between pre and post-disturbance periods. RESULTS: Our results evidenced channel simplification and an expressive decrease in richness and abundance of all taxa right after the flood, followed by subsequent increases of these parameters in the next three samples, indicating trends towards stream community recovery. Bray-Curtis similarity coefficients evidenced a greater community structure disparity among the period right after the flood and the subsequent ones. Multivariate correlation analysis evidenced a greater correlation between macroinvertebrates and algae/macrophytes, demonstrating the narrow relation between their recolonization dynamics. CONCLUSIONS: Despite overall community structure tended to return to previous conditions, recolonization after the flood was much slower than that reported in literature. Finally, the remarkably high flood impact along with the slow recolonization could be a result of the historical presence of anthropic impacts in the region, such as siltation, riparian forest complete depletion, and habitat simplification, which magnified the effects of a natural disturbance.

Laser-flash photolysis of alpha-brominated o-xylenes

The flash photolysis (lambda = 266 nm) of four alpha -brominated omicron -xylenes in apolar solvents gives two transients characterized, depending on parent compound substitution, as either monoradicals or carbenes, and quinodimethanes. alpha -Bromomethylbenzyl radical is characterized and the novel species alpha,alpha'-dibromo-omicron -xylylene and omicron-(alpha,alpha -dibromomethyl)benzyl carbene are described for the first time. (C) 2001 Elsevier Science B.V. All rights reserved.

Potencial evocado visual por flash em cães, ovinos e equinos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Micro-arc oxidation as a tool to develop multifunctional calcium-rich surfaces for dental implant applications

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Flash Mob: da rede à praça

This work explores the flash mobs, which are flash mobilizations arranged by intent that involve a large number of people to do something together in a pre-arranged place. With the advent of 2.0 Internet, the sharing of information and the mobile virtual communication grown up and showed behavior of an individual person to meet for a common interest. Those affective relationships born in the social networks come to the urban space in a real-virtual space junction and the possibilities of that are unexplored yet. Studied by this work, the Y generation is the flash mob most popular public and uses those mobilizations to reinforce their fan identity and appreciation for a media product

Optical parameters and crystallization of flash evaporated amorphous gallium antimonide films

Flash-evaporated GaSb films are analysed using a combination of optical, surface and x-ray diffraction techniques. The effects of thermal annealings on nearly stoichiometric GaSb films are studied.

Metamorphic evolution and P-T path of gneisses from Goiás Magmatic Arc in southwestern Goiás State

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)