387 research outputs found

    Intermittent chaotic states in oxi-halide oscillatory reactions

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    Oscilatorna dinamička stanja su veoma česta u prirodim procesima i stoga važna za postojanje živog sveta. Složeni prirodni sistemi poseduju veliki broj vrsta koje međusobno interaguju na različite načine i kao takvi su veoma komplikovani, ili gotovo nemogući, za detaljna eksperimentalna istraživanja, pa je potrebno da se osnovni fenomeni ispitaju u jednostavnijim hemijskim oscilatorima. U ove jednostavnije hemijske oscilatore spadaju oksihalogenidni oscilatori, od kojih su najpoznatiji Bray-Liebhafsky i Briggs-Rauscher predmet ove teze. U uzanom delu oscilatorne oblasti mogu se zapaziti i aperiodična dinamička stanja odnosno haos. Poseban oblik haosa predstavljaju intermitentne oscilacije odnosno intermitentan haos. Intermitentan haos je ono haotično stanje gde se dva kvalitativno različita dinamička stanja naizmenicno i haotično smenjuju, pri konstantnim vrednostima kontrolnih parametara. Kao takav uočen je u mnogim složenim nelinearnim sistemima mada su saznanja o intermitentnim stanjima u oksihalogenidnim sistemima veoma skromna. Intermitentan haos, koji je u okviru ove teze eksperimentalno generisan, predstavlja haotičnu i naizmeničnu smenu intervala oscilacija velikih amplituda i intervala oscilacija malih amplituda. Za eksperimentalno praćenje intermitentnog haosa u ovoj tezi je koriŔćena potenciometrijska metoda, koja se inače Å”iroko primenjuje za praćenje dinamike hemijskih oscilatora. U oba oksihalogenidna sistema, obuhvaćena tezom, intermitentne oscilacije su uočene u zatvorenom i otvorenom reaktoru, i to u uzanom intervalu kontrolnih parametara u Bray-Liebhafsky sistemu i u uzanom opsegu koncentracija hemijskog perturbatora u Briggs-Rauscher sistemu. Kako bi se omogućila kvantitativna analiza dobijenih rezultata u okviru teze su razvijene i nove metode analize eksperimentalno dobijenog intermitentnog haosa. Pored toga pojedini rezultati su analizirani i primenom numeričkih metoda, poput onih koja se često koriste u analizi haosa, i to PoincarĆ©-ove mape, Lyapunov-ljevi eksponenti i autokorelaciona metoda.Oscillatory dynamic states are very common in natural processes and therefore very important for existence of the living world. Complex natural processes have numerous species that interact between one another in different manners, and so they are very complicated, or almost impossible, for detailed experimental investigations, so principal phenomena sould be examined in simpler chemical oscillators. Such systems are oxi-halide oscillators. The most famous oxi-halide oscillators are Bray-Liebhafsky and Briggs-Rauscher and they are the object of study in this thesis. In the narrow part of the oscillatory region, aperiodic dynamic states or chaos can be found. Intermittent oscillations or intermittent chaos represents a specific form of the chaotic state. Intermittent chaos is considered a chaotic state where transition between two qualitatively different dynamic states occurs randomly and wherein control parameters are constant. As such it was found in many complex nonlinear systems, however knowledge about intermittent states in oxi-halide systems are very modest. Experimentally generated intermittent chaos, within this thesis, represents dynamic state where intervals of high-amplitude oscillations chaotically alternate with intervals of low-amplitude oscillations. For experimental recording of the intermittent chaos, within this thesis, a potentiometric method was used. This method is widely used to follow the dynamics of the chemical oscillators. In this thesis, in both oxi-halide systems, intermittent oscilations were found in open and in closed reactor. Namely, intermitent oscillations were found in narrow interval of control parameters in Bray-Liebhafsky and in narrow range of concentrations of the chemical perturbator in Briggs-Rauscher reaction system. In order to allow quantitative analysis of obtained results, in this thesis new methods of the analysis of the experimentaly obtained intermittent states are developed. Besides, some results were analysed by numerical methods like PoincarĆ© maps, Lyapunov exponents and autocorrelation function since those methods are often used in the analysis of chaos

    Uticaj niskofrekventnog magnetnog polja (10-50 Hz) na respiracionu aktivnost ćelija kvasca Saccharomyces cerevisiae

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    The analysis of the electric, magnetic and electromagnetic fields influence on microorganisms is a very popular research topic, since these fields could potentially act as stressors and affect the microbial metabolism and survival. The aim of this work was to investigate the influence of the low frequency magnetic field (MF) with scan regime from 10 Hz to 50 Hz on S. cerevisiae respiration. The experiment was performed in five replicates and monitored using the Micro-OxymaxĀ® respirometer. All five experiments showed lower cumulative O2 consumption in MF exposed samples, compared to the control sample and inconsistent cumulative CO2 production. However, these differences in O2 consumption and CO2 production were statistically significant. Even though additional experiments are necessary, these results strongly suggest that this is a good basis for further investigation in this field.Ispitivanje uticaja električnog, magnetnog i elektromagnetnog polja na mikroorganizme je veoma aktuelni predmet istrazivanja, jer ova fizička polja potencijalno deluju kao faktori stresa i tako utiču na mikrobni metabolizam, ponaÅ”anje i preživljavanje. U ovom radu ispitivan je uticaj niskofrekventnog magnetnog polja (MP) sa konstantnim intervalom skeniranja od 10 do 50 Hz na respiraciju ćelija kvasca, S. cerevisiae. Eksperiment je rađen u pet ponavljanja i praćen Micro-OxymaxĀ® respirometrom. Kumulativna potroÅ”nja kiseonika je bila manja kod ćelija izloženih MP u svih pet ponavljanja, dok je produkcija CO2 bila nekonzistentna. Međutim, ove razlike u potroÅ”nji O2 i produkciji CO2 su statistički značajne. Iako su dodatna ispitivanja neophodna, dobijeni rezultati ovih inicijalnih eksperimenata predstavljaju dobru osnovu za dalja istraživanja u ovoj oblasti.Related to: [http://cer.ihtm.bg.ac.rs/handle/123456789/3288

    The influence of low-frequency magnetic field regions on the Saccharomyces cerevisiae respiration and growth

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    The influence of four low-frequency magnetic field (MF) ranges 10ā€“300 Hz, 10ā€“100 Hz, 10ā€“50 Hz and 50ā€“100 Hz in scanning regime (all frequencies from selected range were scanned during 100 s repetitively during 24 h) on baker's yeast cells Saccharomyces cerevisiae was examined by continuous measurements of cumulative O2 consumption and cumulative CO2 production over 24 h with Micro-OxymaxĀ® respirometer. Besides respiration activity, measurements of cell growth and glucose uptake were performed as well. Statistical analysis indicated that, among all investigated low-frequency MF ranges, range from 10 Hz to 50 Hz had the greatest influence to yeast cell respiration and cell growth. More precisely, for this region, paired two sample one-tail t-test showed statistically significant differences in cumulative O2 consumption, cumulative CO2 production and S. cerevisiae cell number. Moreover samples exposed to MF range from 10 Hz to 50 Hz showed the same behavior in all five replicates: lower cumulative O2 consumption, higher cumulative CO2 production and higher cell number compared to control sample. This could be important from the application aspect, in industry (food, feed, brewery etc.) and biotechnology, because changes in cells metabolism are not caused by chemical treatment.Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3321

    Intermittent Chaos in the CSTR Brayā€“Liebhafsky Oscillator-Specific Flow Rate Dependence

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    Dynamic states with intermittent oscillations consist of a chaotic mixture of large amplitude relaxation oscillations grouped in bursts, and between them, small-amplitude sinusoidal oscillations, or even the quiescent parts, known as gaps. In this study, intermittent dynamic states were generated in Brayā€“Liebhafsky (BL) oscillatory reaction in an isothermal continuously-fed, well-stirred tank reactor (CSTR) controled by changes of specific flow rate. The intermittent states were found between two regular periodic states and obtained for specific flow rate values from 0.020 to 0.082 mināˆ’1 . Phenomenological analysis based on the quantitative characteristics of intermittent oscillations, as well as, the largest Lyapunov exponents calculated from experimentally obtained time series, both indicated the same type of behavior. Namely, fully developed chaos arises when approaching to the vertical asymptote which is somewhere between two bifurcations. Hence, this study proposes described route to fully developed chaos in the Bray-Liebhafsky oscillatory reaction as an explanation for experimentally observed intermittent dynamics. This is in correlation with our previously obtained results where the most chaotic intermittent chaos was achieved between the periodic oscillatory dynamic state and stable steady state, generated in BL under CSTR conditions by varying temperature and inflow potassium iodate concentration. Moreover, it was shown that, besides the largest Lyapunov exponent, analysis of chaos in experimentally obtained intermittent states can be achieved by a simpler approach which involves using the quantitative characteristics of the BL reaction evolution, that is, the number and length of gaps and bursts obtained for the various values of specific flow rates

    Uticaj niskofrekventnog magnetnog polja (10-50 Hz) na respiracionu aktivnost ćelija kvasca Saccharomyces cerevisiae

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    The analysis of the electric, magnetic and electromagnetic fields influence on microorganisms is a very popular research topic, since these fields could potentially act as stressors and affect the microbial metabolism and survival. The aim of this work was to investigate the influence of the low frequency magnetic field (MF) with scan regime from 10 Hz to 50 Hz on S. cerevisiae respiration. The experiment was performed in five replicates and monitored using the Micro-OxymaxĀ® respirometer. All five experiments showed lower cumulative O2 consumption in MF exposed samples, compared to the control sample and inconsistent cumulative CO2 production. However, these differences in O2 consumption and CO2 production were statistically significant. Even though additional experiments are necessary, these results strongly suggest that this is a good basis for further investigation in this field.Ispitivanje uticaja električnog, magnetnog i elektromagnetnog polja na mikroorganizme je veoma aktuelni predmet istrazivanja, jer ova fizička polja potencijalno deluju kao faktori stresa i tako utiču na mikrobni metabolizam i preživljavanje. U ovom radu ispitivan je uticaj niskofrekventnog magnetnog polja (MP) sa konstantnim intervalom skeniranja od 10 do 50 Hz na respiraciju ćelija kvasca, S. cerevisiae. Eksperiment je rađen u pet ponavljanja i praćen Micro-OxymaxĀ® respirometrom. Kumulativna potroÅ”nja kiseonika je bila manja kod ćelija izloženih MP u svih pet ponavljanja, dok je produkcija CO2 bila nekonzistentna. Međutim, ove razlike u potroÅ”nji O2 i produkciji CO2 su statistički značajne. Iako su dodatna ispitivanja neophodna, dobijeni rezultati ovih inicijalnih eksperimenata predstavljaju dobru osnovu za dalja istraživanja u ovoj oblasti.Related to: [http://cer.ihtm.bg.ac.rs/handle/123456789/3289

    Uticaj niskofrekventnog magnetnog polja (10-50 Hz) na respiracionu aktivnost ćelija kvasca Saccharomyces cerevisiae

    Get PDF
    The analysis of the electric, magnetic and electromagnetic fields influence on microorganisms is a very popular research topic, since these fields could potentially act as stressors and affect the microbial metabolism and survival. The aim of this work was to investigate the influence of the low frequency magnetic field (MF) with scan regime from 10 Hz to 50 Hz on S. cerevisiae respiration. The experiment was performed in five replicates and monitored using the Micro-OxymaxĀ® respirometer. All five experiments showed lower cumulative O2 consumption in MF exposed samples, compared to the control sample and inconsistent cumulative CO2 production. However, these differences in O2 consumption and CO2 production were statistically significant. Even though additional experiments are necessary, these results strongly suggest that this is a good basis for further investigation in this field.Ispitivanje uticaja električnog, magnetnog i elektromagnetnog polja na mikroorganizme je veoma aktuelni predmet istrazivanja, jer ova fizička polja potencijalno deluju kao faktori stresa i tako utiču na mikrobni metabolizam i preživljavanje. U ovom radu ispitivan je uticaj niskofrekventnog magnetnog polja (MP) sa konstantnim intervalom skeniranja od 10 do 50 Hz na respiraciju ćelija kvasca, S. cerevisiae. Eksperiment je rađen u pet ponavljanja i praćen Micro-OxymaxĀ® respirometrom. Kumulativna potroÅ”nja kiseonika je bila manja kod ćelija izloženih MP u svih pet ponavljanja, dok je produkcija CO2 bila nekonzistentna. Međutim, ove razlike u potroÅ”nji O2 i produkciji CO2 su statistički značajne. Iako su dodatna ispitivanja neophodna, dobijeni rezultati ovih inicijalnih eksperimenata predstavljaju dobru osnovu za dalja istraživanja u ovoj oblasti.Related to: [http://cer.ihtm.bg.ac.rs/handle/123456789/3289

    Uticaj niskofrekventnog magnetnog polja (10-50 Hz) na respiracionu aktivnost ćelija kvasca Saccharomyces cerevisiae

    Get PDF
    The analysis of the electric, magnetic and electromagnetic fields influence on microorganisms is a very popular research topic, since these fields could potentially act as stressors and affect the microbial metabolism and survival. The aim of this work was to investigate the influence of the low frequency magnetic field (MF) with scan regime from 10 Hz to 50 Hz on S. cerevisiae respiration. The experiment was performed in five replicates and monitored using the Micro-OxymaxĀ® respirometer. All five experiments showed lower cumulative O2 consumption in MF exposed samples, compared to the control sample and inconsistent cumulative CO2 production. However, these differences in O2 consumption and CO2 production were statistically significant. Even though additional experiments are necessary, these results strongly suggest that this is a good basis for further investigation in this field.Ispitivanje uticaja električnog, magnetnog i elektromagnetnog polja na mikroorganizme je veoma aktuelni predmet istrazivanja, jer ova fizička polja potencijalno deluju kao faktori stresa i tako utiču na mikrobni metabolizam, ponaÅ”anje i preživljavanje. U ovom radu ispitivan je uticaj niskofrekventnog magnetnog polja (MP) sa konstantnim intervalom skeniranja od 10 do 50 Hz na respiraciju ćelija kvasca, S. cerevisiae. Eksperiment je rađen u pet ponavljanja i praćen Micro-OxymaxĀ® respirometrom. Kumulativna potroÅ”nja kiseonika je bila manja kod ćelija izloženih MP u svih pet ponavljanja, dok je produkcija CO2 bila nekonzistentna. Međutim, ove razlike u potroÅ”nji O2 i produkciji CO2 su statistički značajne. Iako su dodatna ispitivanja neophodna, dobijeni rezultati ovih inicijalnih eksperimenata predstavljaju dobru osnovu za dalja istraživanja u ovoj oblasti.Related to: [http://cer.ihtm.bg.ac.rs/handle/123456789/3288

    Uticaj niskofrekventnog magnetnog polja (10-1000 Hz) na respiracionu aktivnost ćelija kvasca Saccharomyces cerevisiae

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    The effects of electric, magnetic or electromagnetic fields on different microbes have become a very popular topic nowadays, mostly because the fields could potentially affect the survival of the microbial cells as well as their behavior and metabolism. In this paper the influence of the magnetic field with constant low frequency scan regime from 10 to 1000 Hz on yeast cells S. cerevisiae respiration activity was examined using Micro-OxymaxĀ® respirometer. Experiments were performed in five replicates. All five experiments showed lower cumulative O2 consumption in magnetic field exposed samples, compared to the control sample and inconsistent cumulative CO2 production. The paired two sample onetail T-test showed statistically significant differences between control and magnetic field sample for cumulative O2 consumption, but not for the CO2 production. Even though additional experiments are neccesary to clarify the differencies in CO2 production, these preliminary findings strongly suggest that obtained results represent a good basis for further investigations in this field.Veoma popularna tema danaÅ”njice je ispitivanje električnog, magnetnog i elektromagnetnog polja na različite mikroorganizme, jer pomenuta fizička polja potencijalno deluju kao faktori stresa i tako utiču na njihovo preživljavanje, ponaÅ”anje i metabolizam. U ovom radu ispitivan je uticaj niskofrekventnog magnetnog polja sa konstantnim intervalom skeniranja od 10 do 1000 Hz na respiraciju ćelija kvasca, Saccharomyces cerevisiae. Eksperimenti su rađeni u pet ponavljanja i kumulativna potroÅ”nja O2 i produkcija CO2 praćena je pomoću Micro-OxymaxĀ® respirometra. U svih pet ponavljanja, ćelije koje su bile izložene magnetnom polju pokazale su manju kumulativnu potroÅ”nju kiseonika u poređenju sa uzorcima van magnetnog polja i nekonzistentnu produkciju CO2. Rezultati su obrađeni uporednim jednosmernim T-testom, koji je pokazao da postoje statistički značajne razlike u kumulativnoj potroÅ”nji O2 između kontrolnih ćelija i onih izloženih magnetnom polju, Å”to nije slučaj sa kumulativnom produkcijom CO2. Iako su dodatna ispitivanja neophodna da se objasni nekonzistentnost produkcije CO2, dobijeni rezultati ovih inicijalnih eksperimenata predstavljaju dobru osnovu za dalja istraživanja u ovoj oblasti

    Influence of low frequency ranges of magnetic field on Saccharomyces cerevisiae respiration

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    In this paper influence of the low frequency magnetic field on Saccharomyces cerevisiae respiration was examined. Influence of four low frequency magnetic field ranges was examined: 10-200 Hz, 200-300 Hz, 300-650 Hz and 650-1000 Hz. All analyzed frequency ranges gave the same influence on the yeast cells respiration

    Microwave assisted synthesis of polyaniline/pullulan (pani/pull) composite

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    Poster presented at Physical Chemistry 2021, 15th International Conference on Fundamental and Applied Aspects of Physical ChemistryAbstract: [https://cer.ihtm.bg.ac.rs/handle/123456789/4955
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