Volume 12
Worldwide Scientist
New Books
Forthcoming Events
1st National Conference with International Participation on Biomedical and Bioprocess Engineering - BM & BP'2009
22nd International Symposium "Bioprocess Systems - BioPS'2010"
Bioprocess Systems
A Genetic Algorithm for Feeding Trajectory Optimisation of Fed-batch Fermentation Processes 1-12
Olympia Roeva, Stoyan Tzonkov
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In this work a genetic algorithm is proposed with the purpose of the feeding trajectory optimization during a fed-batch fermentation of E. coli. The feed rate profiles are evaluated based on a number of objective functions. Optimization results obtained for different feeding trajectories demonstrate that the genetic algorithm works well and shows good computational performance. Developed optimal feed profiles meet the defined criteria. The ration of the substrate concentration and the difference between actual cell concentration and theoretical maximum cell concentration is defined as the most appropriate objective function. In this case the final cell concentration of 43 g·l-1 and final product concentration of 125 g·l-1 are achieved and there is not significant excess of substrate.
Fed-batch Process Optimisation for the Intracellular Enzyme Superoxide Dismutase Production 13-20
Elena Chorukova
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This investigation deals with optimising the glucose feeding of the fed-batch process for the intracellular enzyme superoxide dismutase production on the basis of a hybrid model of the process. The control action has been the concentration of feeding glucose. The theoretical problem statement has been examined. The optimal profiles for glucose feeding of the process have been developed using three optimisation criteria.
Removal of Copper Ions by Non-living Aquatic Macrophytes Egeria Densa 21-32
Juliana Martins Teixeira de Abreu Pietrobelli, Aparecido Nivaldo Módenes, Fernando Rodolfo Espinoza-Quiñones, Márcia Regina Fagundes-Klen, Alexander Kroumov
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In this work, the removal potential of Cu2+ ions by non-living macrophytes Egeria densa has been studied. Adsorption kinetic and equilibrium tests were carried out in flasks under batch operations and controlled pH and temperature. The biosorption kinetic results have shown that Cu2+ ions removal rate was at its maximum at the beginning of the process. The equilibrium state was achieved after 60 min, and the Cu2+ ions removal was higher than 70% for the given experimental conditions. The kinetic biosorption data were better fitted by using a pseudo second order model. The equilibrium data at pH 5 were better described by the Langmuir isotherm than the Freundlich one, with a maximum metal content value of 1.47 mequiv⋅g-1 and an adsorption rate value of 3.73 l⋅mequiv-1. The kinetic parameters values were in agreement with other biosorbents data published in the literature, indicating that the macrophytes E. densa have a good potential to be used as biosorbent material in industrial effluent treatment system.
Modelling of L-valine Repeated Fed-batch Fermentation Process Taking into Account the Dissolved Oxygen Tension 33-44
Kalin Todorov, Tzanko Georgiev, Ignat Dimov, Julia Kristeva, Alexander Ratkov
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This article deals with synthesis of dynamic unstructured model of variable volume fed-batch fermentation process with intensive droppings for L-valine production. The presented approach of the investigation includes the following main procedures: description of the process by generalized stoichiometric equations; preliminary data processing and calculation of specific rates for main kinetic variables; identification of the specific rates takes into account the dissolved oxygen tension; establishment and optimisation of dynamic model of the process; simulation researches. MATLAB is used as a research environment.
Biomedical Systems
Bulgarian Youth and Europe. Multivariate Psycho-cultural Study of the Mobility Attitudes 45-52
Tsveta Mladenova, Mikhail Matveev
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The objective of this study is to examine the Bulgarian youths’ mobility towards Europe. The investigation was carried out with 570 Bulgarian students. The data are presented as a questionnaire consisting of five parts. The first one deals with the motivations and is based on the Reversal Theory – predicting eight motivational states. The second part is based on the 2PAP theoretical model structuring the attitudes around four factors: Push, Pull, Anti Push and Anti Pull. The third one falls back on the Big Five Personality Test measuring five personality dimensions. And the concluding two parts are designed to obtain information about the degree of attraction and the intentions for mobility to the 25 destination countries of the European Union (EU). This has led to the hypothesis that a model of mobility exists based on these three theoretical models, as well as on emotional factors like attraction-repulsion to the country referred to. The hypothesis that was strongly supported by the statistical processing of the data will broaden our understanding of the youth’s mobility. The present research is a part of a longitudinal study of the mobility intentions among young people. The investigation is of great interest from an educational, political and social point of view.
Time Delay and Epo Dose Modulation in a Multilevel Model for Erythropoiesis 53-69
Svetoslav Nikolov, Xin Lai, Olaf Wolkenhauer, Julio Vera
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In this paper we have extended and adapted a multi-level model in ordinary differential equations accounting for erythropoiesis. At the subcellular level, the model includes equations for the regulation of red blood differentiation through Epo stimulated JAK2-STAT5 activation, while at the cell population level the model describes the basic physiological features involved in erythropoiesis. Furthermore, we included additional equations describing the exogenous injection of Epo, one of the usual treatments for several haematological diseases. Our analysis indicates that time-delay associated with the proliferation-differentiation process can provoke pathological sustained oscillations in the erythropoiesis, while other (shorter) time-delays in the model accounting for nucleo-cytoplasmic shuttling of STAT5 or hypoxia-mediated control of Epo synthesis cannot. The consequences of time delays on the dynamics of the multi-level model are analysed using Hopf’s bifurcation theorem. We also investigated the effects that subcellular-level downregulation of the proteins involved in the JA2-STAT5 pathway have in the dynamics of red blood cells population. We found that downregulation of Epo receptor or STAT5 synthesis can reduce considerably the mean value of red blood cells concentration. Our analysis revealed that a realistic scenario for Epo injection (twice-per-day short pulses) can compensate effects of low-medium downregulation, while for intense down regulation Epo injection seems not able to restore the desired hematocrit levels.
EEG Fractal Dimension Measurement before and after Human Auditory Stimulation 70-81
Stiliyan Georgiev, Zlatogor Minchev, Christina Christova, Dolja Philipova
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The aim of this work is to investigate the change of fractal dimension Df with the help of Higuchi Fractal Dimension measure (HFD) in Event-Related Potentials (ERP) of human EEG time series, obtained as a result of oddball paradigm usage and auditory stimulation with instruction for passive listening and counting tasks, depending on gender, personality type and task condition. In our study 77 healthy volunteers have been participated and 38 of them have been selected after a personality classification with Eysenck’s personality questionnaire (EPQ).The achieved results showed specific functional meaning of ERP HFD change depending on the individual personality type and gender.
Evidentiary Standards in Medicine with Particular Reference to Meta-analysis 82-87
Yee Hung Choy, Anthony Shannon
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The purpose of this paper is to raise issues about what constitutes convincing medical evidence, particularly in meta-analysis. While meta-analysis, like any statistical approach, is open to abuse, the point here is how compelling does the quality of evidence need to be in order to be convincing?
Ecological Systems
Parameter and State Estimation of the Anaerobic Digestion of Organic Wastes with Addition of Stimulating Substances 88-105
Ivan Simeonov, Velislava Lubenova, Isabelle Queinnec
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New control inputs are introduced in the 5th order mass-balance non-linear model of the anaerobic digestion, which reflects the addition of stimulating substances (acetate and glucose). Laboratory experiments have been done with step-wise and pulse changes of these new inputs. On the basis of the step responses of the measured variables (biogas flow rate and acetate concentration in the bioreactor) and iterative methodology, involving non-linear optimisation and simulations, the model coefficients have been estimated. The model validity has been proved by another set of experiments. The observation part is built on a two-step structure. One estimator and two observers are designed on the basis of this process model. Their stability has been proved and their performances have been investigated with experimental data and simulations.

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