Suchergebnisse

H1: Cercado "Eras de Cristo" -- H2: Edificio que se proyecta ; Manuscritos firmados, rubricados y fechados en Granada ; Sello del Departamento de Armamento de Artillería de Granada ; Varias medidas: H1: 61,5x64, H2: 38x75,3 cm ; Reproducción digital ; . 3ª/2ª/ LEGAJO 140 ; Índices: Catálogo de documentos. Tercera sección.

12 páginas, 1 apéndice, 16 figuras, 6 tablas ; Freeze–drying is considered to be an attractive dehydration method of preserving the quality of high value foods products. Unfortunately, it is an expensive operation, which calls for efficient tools capable of minimizing time and/or energy while preserving product quality. In this work, time-scale analysis has been applied to a detailed first-principle-based model. From such analysis a simplified model, capable of describing freeze–drying at the time scales relevant to quality, has been proposed. The model has been solved by the Finite Element method, showing good agreement with the results in literature. Likewise, the efforts associated with the computation of optimal operation policies have been reduced. In this regard, different operational scenarios that take into account shelf temperature (TL) and chamber pressure (Pc) have been considered on a simulation basis. In all cases the resulting optimal control profiles obtained led to significant reductions of cycle time while ensuring product quality. ; 7th Framework Programme of the European Union (CAFE Project – Large Collaborative Project: KBBE-2007-2-3–01); Spanish Government (MICINN Project AGL2008-05267-C03–01); Xunta de Galicia (IDECOP 08DPI007402PR) ; Peer reviewed

12 páginas, 5 figuras, 3 tablas ; Switch like responses appear as common strategies in the regulation of cellular systems. Here we present a method to characterize bistable regimes in biochemical reaction networks that can be of use to both direct and reverse engineering of biological switches. In the design of a synthetic biological switch, it is important to study the capability for bistability of the underlying biochemical network structure. Chemical Reaction Network Theory (CRNT) may help at this level to decide whether a given network has the capacity for multiple positive equilibria, based on their structural properties. However, in order to build a working switch, we also need to ensure that the bistability property is robust, by studying the conditions leading to the existence of two different steady states. In the reverse engineering of biological switches, knowledge collected about the bistable regimes of the underlying potential model structures can contribute at the model identification stage to a drastic reduction of the feasible region in the parameter space of search. In this work, we make use and extend previous results of the CRNT, aiming not only to discriminate whether a biochemical reaction network can exhibit multiple steady states, but also to determine the regions within the whole space of parameters capable of producing multistationarity. To that purpose we present and justify a condition on the parameters of biochemical networks for the appearance of multistationarity, and propose an efficient and reliable computational method to check its satisfaction through the parameter space. ; Funding provided by Spanish government, Ministry of Science and Innovation project MultiSysBio (ref. DPI2008-06880-C03-02) and DPI2004-07444-C04-03, Xunta de Galicia (PGIDIT02-PXIC40209PN). Consejo Superior de Investigaciones Científicas intramural project BioREDES (ref. PIE-201170E018). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. ; Peer reviewed

13 páginas, 10 figuras, 3 tablas, 1 apéndice ; In this work, a novel algorithmic approach to detect multiplicity of steady states in enzymatic reaction networks is presented. The method exploits the structural properties of networks derived from the Chemical Reaction Network Theory. In first instance, the space of parameters is divided in different regions according to the qualitative behavior induced by the parameters in the long term dynamics of the network. Once the regions are identified, a condition for the appearance of multiplicities is checked in the different regions by solving a given optimization problem. In this way, the method allows the characterization of the whole parameter space of biochemical networks in terms of the appearance or not of multistability. The approach is illustrated through a well-known case of enzymatic catalysis with substrate inhibition ; The authors acknowledge financial support received from the Spanish Government (DPI2004 - 07444 - C04 - 03) and Xunta de Galicia (PGIDIT02 - PXIC40209PN). ; Peer reviewed

13 páginas, 17 figuras, 1 tabla ; In Part I of this study, a method for the derivation of reduced-order models of food thermal processing was presented. In this second part, the capabilities and efficiency of this method is illustrated by applying it to the problems of design and optimization of thermal sterilization. The particular case of conduction-heated foods is considered, without loss of generality. The results clearly indicate that this new methodology allows very fast and accurate solutions of these problems, opening a whole new avenue of possibilities, especially for real-time optimization and control applications. Furthermore, the methodology can be applied to other food processes described by distributed models. ; This work was supported in part by the EU (project FAIR CT96-1192) and the Spanish Government (CICyT project ALI97-1939-CE). ; Peer reviewed