Volume 13, number 3
Editorial
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"
Invited Paper
Comparison of IDP and LJ Optimization Procedure for Establishing the Optimal Control of a Nonisothermal Fedbatch Reactor 1-14
Rein Luus
[ +/- abstract ] [ full text ]
Optimal control of a nonisothermal fedbatch reactor with heat removal constraint is used as a test problem for comparing iterative dynamic programming (IDP) and Luus-Jaakola (LJ) optimization procedure. Although there are only two control variables, the feed rate and the temperature, the heat production rate constraint makes the optimal control problem very difficult. Therefore, the problem is reformulated by using rate of heat production instead of temperature as the second control variable. To parametrize the optimal control problem, the time interval is divided into P time stages of constant length, and piecewise constant control is used at each time stage. For small values of P, both optimization procedures are almost equivalent. However, when is increased beyond 20, IDP becomes more efficient.
Bioprocess systems
Hybrid Modeling and Optimization of Yogurt Starter Culture Continuous Fermentation 15-26
Petia Koprinkova-Hristova, Silviya Popova, Mihail Angelov, Georgi Kostov
[ +/- abstract ] [ full text ]
The present paper presents a hybrid model of yogurt starter mixed culture fermentation. The main nonlinearities within a classical structure of continuous process model are replaced by neural networks. The new hybrid model accounts for the dependence of the two microorganisms' kinetics from the on-line measured characteristics of the culture medium - pH. Then the model was used further for calculation of the optimal time profile of pH. The obtained results are with agreement with the experimental once.
Genetic Algorithmic Optimization of PHB Production by a Mixed Culture in an Optimally Dispersed Fed-batch Bioreactor 27-46
Pratap R. Patnaik
[ +/- abstract ] [ full text ]
Poly-β-hydroxybutyrate (PHB) is an energy-storage polymer whose properties are similar to those of chemical polymers such as polyethylene and polypropylene. Moreover, PHB is biodegradable, absorbed by human tissues and less energy-consuming than synthetic polymers. Although Ralstonia eutropha is widely used to synthesize PHB, it is inefficient in utilizing glucose and similar sugars. Therefore a co-culture of R. eutropha and Lactobacillus delbrueckii is preferred since the latter can convert glucose to lactate, which R. eutropha can metabolize easily. Tohyama et al. [24] maximized PHB production in a well-mixed fed-batch bioreactor with glucose and (NH4)2SO4 as the primary substrates. Since production-scale bioreactors often deviate from ideal laboratory-scale reactors, a large bioreactor was simulated by means of a dispersion model with the kinetics determined by Tohyama et al. [24] and dispersion set at an optimum Peclet number of 20 [32]. The time-dependent feed rates of the two substrates were determined through a genetic algorithm (GA) to maximize PHB production. This bioreactor produced 22.2% more PHB per liter and 12.8% more cell mass than achieved by Tohyama et al. [24]. These results, and similar observations with other fermentations, indicate the feasibility of enhancing the efficiency of large nonideal bioreactors through GA optimizations.
On the biomass specific growth rates Estimation for Anaerobic digestion Using Differential algebraic Techniques 47-56
Sette Diop, Ivan Simeonov
[ +/- abstract ] [ full text ]
The paper deals with identifiability and observability of anaerobic digestion (AD) processes. In such kind of processes, generally carried out in continuously stirred tank bioreactors, the organic matter is depolluted by microorganisms into biogas and compost in the absence of oxygen. The biogas is an additional energy source, which can replace fossil fuel sources. The differential algebraic approach of general observation problems has been applied to investigate the identification and observation of a simple AD model. The major discovery is that the biomass specific growth rate can be stably estimated from easily measured quantities: the dilution rate and the biogas flow rate. Next if the yield coefficients are assumed known then, of course, the biomass concentration is observable. Unfortunately, even under the latter strongest assumption the substrate concentration is not observable. This concentration becomes observable if an additional model, say the Monod model, is assumed for the specific growth rate. Illustrative simulations are presented.
Biomedical Systems
Brainstem auditory evoked potentials in patients with subarachnoid haemorrhage 57-72
Lyubomir Haralanov, Mikhail Matveev, Elena Mermeklieva
[ +/- abstract ] [ full text ]
Objective. The aim of the present study is to typify BAEPs configurations of patients with different location of lesions caused by subarachnoid haemorrhage (SAH) and the ensuing complications, in view of assessing the auditory-brainstem system disturbance.
Methods. The typization was performed by comparing BAEPs with standard patterns from two sets of types of BAEPs by ipsilateral and binaural stimulation and by cross-stimulation.
Results. 94 BAEPs were used for collection of normal referential values: for the absolute latencies and the absolute amplitudes of waves I, II, III, IV and V; for inter-peak latencies I-III, II-III, III-V, I-V and II-V; for amplitude ratios I/V and III/V. 146 BAEPs of patients with mild SAH and 55 from patients with severe SAH, were typified. In 5 types of BAEPs out of a total of 11, the percentage of the potentials in patients with mild SAH and severe SAH differed significantly (p<0.01).
Conclusions. The use of sets of types of BAEPs by ipsilateral, binaural and cross-stimulation correctly classifies the potentials in patients with mild and severe SAH.
Generalized Nets for the Diagnosis and Management of Diabetic Nephropathy 73-82
Anthony Shannon, Yee Hung Choy
[ +/- abstract ] [ full text ]
This paper develops Generalized Nets for the diagnosis and management of diabetic nephropathy. The first net accounts for the development of nephropathy from an initial increase in glomerular filtration rates through mciroalbuminuria to end stage renal disease. The second net referes to the management of diabetes mellitus to increase the probability of preventing diabetic nephropathyor minimising its effects.
Cardio Compression Control Device: Development, Calibration and Testing 83-96
Irena Jekova, Vessela Krasteva, Tatyana Neycheva, Nikolay Mudrov, Zhecho Kostov, Jean-Philippe Didon
[ +/- abstract ] [ full text ]
Cardio-pulmonary resuscitation (CPR) is a life-saving first aid which is part of the treatment given in case of sudden cardiac death. According to the American Heart Association (AHA) 2005 Guidelines for CPR, there are three key components related to the chest compressions which should be considered: (i) optimal compression depth between 3.8 and 5.4 centimeters; (ii) optimal compression rate between 85 and 115 compressions per minute; (iii) complete chest recoil by releasing all pressure from the chest after each chest compression (CC).
A device for automatic control of the quality of chest compressions during CPR was developed. It embedded hardware and software solutions for simultaneous measurement of the depth, rate and the chest recoil thus providing a feedback about the efficiency of the cardiac massage at each CC compression. The system is applicable as a training device for basic education in CPR or as a consulting system for rescuers on the scene of the cardiac incident. The accuracy of the CC Device was adjusted by theoretical and experimental calibration, and tested by planned experiments, as well as experiments with a medical team.
Bioinformatics
Topics of Bioengineering in Wikipedia 96-110
Vassia Atanassova
[ +/- abstract ] [ full text ]
The present report aims to give a snapshot of how topics from the field of bioengineering (bioinformatics, bioprocess systems, biomedical engineering, biotechnology, etc.) are currently covered in the free electronic encyclopedia Wikipedia. It also offers insights and information about what Wikipedia is, how it functions, how and when to cite Wikipedian articles, if necessary. Several external wikis, devoted to topics of bioengineering, are also listed and reviewed.

© 2009, BAS, Institute of Biophysics and Biomedical Engineering