1,612 research outputs found
Development of image analysis methods to evaluate barley / malt grain size
It is known that the barley / malt grain size is an important factor regarding the uniformity of malting
process and hence the brewery process. For that purpose an image processing and analysis system was
built for the evaluation of grain / malt size, on the ImageJ public domain platform. A programme was
developed for the barley / malt images treatment and determination of several morphological
parameters as well as the grain size distribution. The results showed that for the Prestige and Scarlett
barley varieties good correlations could be obtained between the standard weight distribution and the
proposed image analysis method. For the Esterel malt and barley as well as for the Nevada barley
reasonable to good correlations were also obtained upon the introduction of a density correction factor
Integrable theories and loop spaces: fundamentals, applications and new developments
We review our proposal to generalize the standard two-dimensional flatness
construction of Lax-Zakharov-Shabat to relativistic field theories in d+1
dimensions. The fundamentals from the theory of connections on loop spaces are
presented and clarified. These ideas are exposed using mathematical tools
familiar to physicists. We exhibit recent and new results that relate the
locality of the loop space curvature to the diffeomorphism invariance of the
loop space holonomy. These result are used to show that the holonomy is abelian
if the holonomy is diffeomorphism invariant.
These results justify in part and set the limitations of the local
implementations of the approach which has been worked out in the last decade.
We highlight very interesting applications like the construction and the
solution of an integrable four dimensional field theory with Hopf solitons, and
new integrability conditions which generalize BPS equations to systems such as
Skyrme theories. Applications of these ideas leading to new constructions are
implemented in theories that admit volume preserving diffeomorphisms of the
target space as symmetries. Applications to physically relevant systems like
Yang Mills theories are summarized. We also discuss other possibilities that
have not yet been explored.Comment: 64 pages, 8 figure
Optimization of fed-batch fermentation processes with bio-inspired algorithms
The optimization of the feeding trajectories in fed-batch fermentation processes is a complex problem that has gained attention given its significant economical impact. A number of bio-inspired algorithms have approached this task with considerable success, but systematic and statistically significant comparisons of the different alternatives are still lacking. In this paper, the performance of different metaheuristics, such as Evolutionary Algorithms (EAs), Differential Evolution (DE) and Particle Swarm Optimization (PSO) is compared, resorting to several case studies taken from literature and conducting a thorough statistical validation of the results. DE obtains the best overall performance, showing a consistent ability to find good solutions and presenting a good convergence speed, with the DE/rand variants being the ones with the best performance. A freely available computational application, OptFerm, is described that provides an interface allowing users to apply the proposed methods to their own models and data.The work is partially funded by ERDF - European Regional Development Fund through the COMPETE Programme (operational programme for competitiveness) and by National Funds through the FCT (Portuguese Foundation for Science and Technology) within projects Ref. COMPETE FCOMP-01-0124-FEDER-015079 and PEst-OE/ES/UI0752/2011
Parallel neural network recognition - a multi-agent system approach
This paper presents and discusses the design and the development of a pattern recognition agent based on neural networks. This agent is part of an intelligent navigation system, providing it with the necessary vision abilities so that it can be placed on a strange environment in order to explore and recognise its structures and specificities. Although similar, the properties of the recognised objects change through time and according to each specific environment. The flexibility required by such recognition process was implemented by several pattern recognition agents. Each agent is based on a neural network and can be trained on-line by a parallel training algorithm to allow an effective real time utilisation
Modeling and simulation of fructo-oligosaccharides production
It is foreseen that Systems Biology will have a great impact not only in Metabolic Engineering and Drug Discovery efforts, but also in Bioprocess development and optimization. In fact, the computational tools developed in this area made possible to simulate a biochemical process with a mathematical model comprising dynamical equations based on first
principles as well as empirical kinetic equations and parameters that can be estimated from experimental data.
Fructo-oligosaccharides (FOS) have become important as healthy food ingredients because of their beneficial
characteristics to the health of human (Lee, 1999). They can be obtained biotechnologically using the enzyme Betafructofuranosidase,
produced by some fungi.
The main purpose of this work was to develop a mathematical model able to simulate the formation of FOS in a
bioreactor, in order to perform a faster optimization of the FOS production process, allowing to identify which parameters
can influence the final amount of FOS. An empirical model presented by Kow Jen Duan et al (1994) was used to obtain
the first set of reactions. Several hydrolysis equations were added in order to achieve a general mathematical model of
the occurring enzymatic reactions.
After the reformulation of the Kow Jen Duan model, the kinetic parameters were determined from experimental data using the System Biology toolbox [2] with the Simulated Annealing method for curve fitting. Several experiments in bioreactors were performed with two different FOS producing fungi for that purpose. The time evolution of 7 state
variables (Sucrose, Glucose, Fructose, 1-Kestose, Nystose, 1-Fructosyl Nystose and Biomass) was considered. After
parameter fitting, several simulations were performed in MatLab and the simulation results were compared with experimental data, exhibiting a very satisfactory correlation for both fungal cultures. Correlation coefficients of 0.9980 - 0.9549 between simulated and experimental data were obtained. This model will be used to optimize the production process, using an optimization tool that has been developed in our research group
Optimization of a fructooligosaccharides purification method using activated charcoal
Fructooligosaccharides (FOS) have gained large commercial interest due to its beneficial
properties in the human health as prebiotics. FOS are produced industrially by fermentative
processes. However, the result of such fermentations is a complex mixture containing salts and
approximately 50% (w/w) of low molecular weight sugars that have to be eliminated. Among
other techniques that have been studied, the adsorption onto activated carbon is still the most
suitable one since activated carbon is cheap, has a large surface area and pore volume
conducting to a good sorption capacity. Furthermore, this sorbent can be regenerated during
desorption with ethanol. Based on the above discussion, in this work the adsorption and
desorption characteristics of FOS on activated carbon, using a gradient of ethanol, were
optimized. Initially, the activated carbon was loaded with fermentative broth. To remove the non
adsorbed sugars, a washing step with pure water was included. Afterwards, the retained sugars
were recovered by elution with a gradient of ethanol increased sequentially with specific volumes
from 1 to 50% (v/v). Fractions collected at different time points were evaporated and
subsequently freeze‐dried. This process was found to be very efficient in the demineralization of
broth, and it was possible to recover 80% of the initial FOS loaded on the column with 89% of
purity. Some of the fractions were found to contain 97% of pure FOS in total sugars. In summary,
purification of FOS using an activated charcoal column is a very efficient process yielding high
levels of purity from a fermentative broth
Purification of fructo-oligosaccharides by adsorption onto charcoal filters
Production of fructo-oligosaccharides has received particular attention
recently due to its beneficial effects as prebiotics. Fermentative processes
appear to be a good technique for large scale production of FOS. However,
the result of such fermentations is a complex mixture containing salts and
low molecular weight sugars that do not contribute to the beneficial
properties of the higher molecular weight oligosaccharides, and so have to
be eliminated. Among the several strategies being studied to solve this
problem, the adorption onto activated carbon is a promising technique that
still requires further development. Thus, the aim of this work was the
purification of FOS from a fermentation broth using charcoal filters.
Microfiltration membranes (0,20 micrometers) were successfully used to
separate the biomass; nevertheless salts and other small sugars had to be
eliminated using a charcoal filter. Hence, 200 mL of fermentative broth
(without cells) was passed through the filter. Subsequently, the filter was
washed with water removing the salts and small sugars present in the
mixture. The oligosaccharides adsorbed onto the charcoal filter were
recovered using a 44% ethanol solution. An increased purity, from 30% to
97% (w/w) in total sugars, was achieved using this downstream process, as
compared to the initial mixture. The results gathered in this work suggest
that charcoal filters are a promising technology for the purification of FOS
from fermentation mixtures at an industrial scale, making clear the need for
further work in order to optimize this process
Specific detection of dengue and Zika virus antibodies using envelope proteins with mutations in the conserved fusion loop
Detection of antibodies is widely used for the diagnosis of infections with arthropod-borne flaviviruses including dengue (DENV) and Zika virus (ZIKV). Due to the emergence of ZIKV in areas endemic for DENV, massive co-circulation is observed and methods to specifically diagnose these infections and differentiate them from each other are mandatory. However, serological assays for flaviviruses in general, and for DENV and ZIKV in particular, are compromised by the high degree of similarities in their proteins which can lead to cross-reacting antibodies and false-positive test results. Cross-reacting flavivirus antibodies mainly target the highly conserved fusion loop (FL) domain in the viral envelope (E-) protein, and we and others have shown previously that recombinant E-proteins bearing FL-mutations strongly reduce cross-reactivity. Here we investigate whether such mutant E-proteins can be used to specifically detect antibodies against DENV and ZIKV in an ELISA-format. IgM antibodies against DENV and ZIKV virus were detected with 100% and 94.2% specificity and 90.7% and 87.5% sensitivity, respectively. For IgG the mutant E-proteins showed cross-reactivity, which was overcome by pre-incubation of the sera with the heterologous antigen. This resulted in specificities of 97.1% and 97.9% and in sensitivities of 100% and 100% for the DENV and ZIKV antigens, respectively. Our results suggest that E-proteins bearing mutations in the FL-domain have a high potential for the development of serological DENV and ZIKV tests with high specificity
Resistivity study of the pseudogap phase for (Hg,Re) - 1223 superconductors
The pseudogap phase above the critical temperature of high
superconductors (HTSC) presents different energy scales and it is currently a
matter of intense study. The complexity of the HTSC normal state requires very
accurate measurements with the purpose of distinguishing different types of
phenomena. Here we have performed systematically studies through electrical
resistivity () measurements by several different current densities in
order to obtain an optimal current for each sample. This approach allows to
determine reliable values of the pseudogap temperature , the layer
coupling temperature between the superconductor layers , the
fluctuation temperature and the critical temperature as
function of the doping . The interpretation of these different temperature
scales allows to characterize possible scenarios for the (Hg,Re) - 1223 normal
state. This method, described in detail here, and used to derive the
(Hg,Re)-1223 phase diagram is general and can be applied to any HTSC.Comment: 31 pages, 12 figures, Latex; 25 pages, LaTeX; 11 figures; rewrited
section II and III; added 18 reference; rewrited title, added discussion
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