Modelling, Optimization and Optimal Control of Small Scale Stirred Tank Bioreactors

Models of the mass-transfer in a stirred tank bioreactor depending on general indexes of the processes of aeration and mixing in concrete simplifications of the hydrodynamic structure of the flows are developed. The offered combined model after parameters identification is used for optimization of the parameters of the apparatus construction. The optimization problem is solved by using of the fuzzy sets theory and in this way the unspecified as a result of the model simplification are read. In conclusion an optimal control of a fed-batch fermentation process of E. coli is completed by using Neuro-Dynamic programming. The received results after optimization show a considerable improvement of the mass-transfer indexes and the quantity indexes at the end of the process

Effect of various factors to ammonia biodegradation by two stage biofiltration system

[Abstract] An autotrophic ammonia-biodegrading PNNS association was isolated from the biological activated sludge of the fish factory wastewater treatment plant and used in the two-stage biofiltration system with the ammonia load 0.78 g/m3h ensured the total removal efficiency up to 0.69 g/m3h as the result of the denitrification process. Additional investigations were made to study physiological and biochemical properties of individual strains of the PNNS association in order to control their growth under various cultivation conditions with the aim to find out the most optimal conditions for biomass preparation and immobilisation. Individual strains of the association can be revealed and counted because of their different colony morphology using selected medium. Cultivation of individual strains of the PNNS association under aerobic conditions revealed a stimulation effect of (NH4)2SO4 in the concentration range of 0.21 – 4.45 g N/l to their growth. Addition of saccharose, glucose, fructose and/or cabbage leaf extract (CLE) in various combinations to agarized medium resulted in the growth stimulation of individual strains of the PNNS association, i.e. Pseudomonas sp., Nitrosomonas sp., Nitrobacter sp. and Sarcina sp. The whole association was cultivated in the liquid mineral medium with amendments mentioned above. Stimulation of the growth in the presence of CLE and some reducing sugars was observed. The results obtained in these experiments will be used for further optimisation of the two-stage biofiltration system using the PNNS association

Diagnostic Value of Histological and Microbiological Screening in Etiopathogenesis of Recurrent and Hypertrophic Tonsillitis

Interest in the mechanisms and causes of recurrent tonsillitis is considerable. CD4+CD25+ T-lymphocytes have an important role in the maintenance of immunological tolerance. The aim of our research was to compare the diagnostic value of palatine tonsils histological and microbiological screening in patients with hypertrophic and recurrent tonsillitis. 14 patients with hypertrophic and 10 patients with chronic tonsillitis undergoing tonsillectomy were enrolled in the study. Rapid diagnosis of adenovirus, parainfluenza, influenza A and B, and respiratory syncytial virus infection was made before tonsillectomy by viral antigen detection using the immunofluorescence procedure from tonsils. Herpes simplex and cytomegaloviruses DNA were detected by the polymerase chain reaction. Samples for bacteriological studies were collected using a cotton swab. Immunohistochemical methods were used to evaluate S-100 and TGF-beta1 expression. The obtained results showed that patients with recurrent tonsillitis had less S-100 and TGF-beta1 positive cells in parafollicular regions compared to patients with hypertrophic tonsillitis. In both groups, tonsils were colonized predominantly by gram-positive microorganisms and adenovirus (36% of cases). However, in patients with recurrent tonsillitis, associations of gram-positive, gram-negative bacteria and viruses (40% of cases) were observed. To conclude, recurrent tonsillitis is characterized by the breakdown of the immunological tolerance to oral microflora

Model-Driven Secure System Development Framework

Security is definitely one of the most important aspects in business information systems. This aspect is strongly related to costs, risks and reputation of organization. That’s why authors want to propose “secure-by-design” principle by using innovative and proven development approaches in whole system lifecycle to maintain high security level. There are already some existing techniques to solve this problem but they are mainly linked with specific technologies and most frequently focus only on production phase. This paper presents new secure system development methodology based on three general aspects – model-driven secure code development, model-driven policy development and usage of run-time security management system to maintain necessary security level. All these aspects are integrated into one framework

Drošas programmatūras izstrādes iespējas modeļvadāmās arhitektūras kontekstā

Rakstā ir sniegts modeļvadāmās drošības pārskats un ar to saistīto aspektu izklāsts. Autori izskaidro pašreizējās problēmas un aplūko modeļvadāmo drošību kā vienu no iespējamajiem risinājumiem. Tālāk rakstā ir analizēta ļaunprātīgo lietošanas gadījumu izmantošana un piedāvāta metode nefunkcionālo drošības prasību pārveidošanai funkcionālās prasībās. Raksta nobeigumā ir analizētas vienotas uz MDA balstītas drošas programmatūras izstrādes metodoloģijas izveides iespējas. Pētījums varētu būt interesants sistēmanalītiķiem un programmatūras drošības speciālistiem

Biotechnological Methods for Precise Diagnosis of Methicillin Resistance in Staphylococci

Antimicrobial resistance is one of the most urgent problems in medicine nowadays. The purpose of the study was to investigate the microorganisms resistant to first-line antimicrobials, including gram-positive cocci, particularly the methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococci, the major agents of nosocomial infections. Owing to the multi-resistance of these agents, precise diagnosis of the methicillin resistance of Staphylococci is of greatest clinical importance. It is not enough to use only conventional microbiological diagnostic methods. Biotechnological methods should be also involved. In our studies, the following methicillin resistance identification methods were used: the disk diffusion method, detection of the mecA gene by PCR, E-test and Slidex MRSA test. For molecular typing, PFGL, RAPD tests and detection of the coa gene were used. All the MRS strains were multiresistant to antibacterials. No vancomycine resistance was registered

The Mechanical Transient Process at Asynchronous Motor Oscillating Mode

The research object is squirrel-cage asynchronous motor connected to single-phase sinusoidal. There are shown, that by connecting to the stator windings a certain sequence of half-period positive and negative voltage, a motor rotor is rotated, but three times slower than in the three-phase mode. Changing the connecting sequence of positive and negative half-period voltage to stator windings, motor can work in various oscillating modes. It is tested experimentally. The mechanical transient processes had been researched in rotation and oscillating modes

Extracellular Polysaccharide Production and Biofilm Formation by Coagulase-negative Staphylococci

Coagulase-negative Staphylococci (CoNS) form a part of the skin flora and commonly cause nosocomial bloodstream and catheter- related infections. According to their relatively low virulence, it is important to detect the virulence factors of clinical isolates. The production of extracellular polymers and formation of biofilms belong to virulence factors. We studied clinical isolates of CoNS and compared them with isolates from the healthy skin. The species distribution did not differ significantly. Slime production in clinical strains was more often and more intense. A comparison of methicillin-resistant (MR) and methicillinsensitive (MS) clinical strains has revealed that slime production is more active in MR strains

Development and Application of a Flexible Controller in Yeast Fermentations Using pO2 Cascade Control

The development and application of a flexible process controller in fed-batch yeast fermentations using pO2 cascade control was performed. A new algorithm for fedbatch fermentations using pO2 cascade control was developed, the concept of which could be used as a realizable solution in fermentation systems equipped according to the basic configuration. The algorithm is based on the combined influence of pO2 and pH on the substrate feeding intensity. To test and develop this algorithm, Saccharomyces cerevisiae DY 7221 and Candida tropicalis CK-4 fermentations were carried out. As a result of the use of the combined algorithm, the specific growth rate and productivity grew in both fermentations. In this case, the effect of the use of the algorithm was most pronounced in the C. tropicalis fermentation

Application of a Fuzzy Neural Network for Modeling of the Mass-Transfer Coefficient in a Stirred Tank Bioreactor

A type of a fuzzy neural network for mathematical modeling of the volumetric mass-transfer coefficient is presented in the paper. Performed investigations show that the presented fuzzy neural network can be successfully used for modeling of such a complex process, like mass-transfer