519 research outputs found
Intermittent chaotic states in oxi-halide oscillatory reactions
Oscilatorna dinamiÄka stanja su veoma Äesta u prirodim procesima i stoga važna za postojanje živog sveta. Složeni prirodni sistemi poseduju veliki broj vrsta koje meÄusobno interaguju na razliÄite naÄine i kao takvi su veoma komplikovani, ili gotovo nemoguÄi, 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 aperiodiÄna dinamiÄka stanja odnosno haos. Poseban oblik haosa predstavljaju intermitentne oscilacije odnosno intermitentan haos. Intermitentan haos je ono haotiÄno stanje gde se dva kvalitativno razliÄita dinamiÄka stanja naizmenicno i haotiÄno smenjuju, pri konstantnim vrednostima kontrolnih parametara. Kao takav uoÄen 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 haotiÄnu i naizmeniÄnu smenu intervala oscilacija velikih amplituda i intervala oscilacija malih amplituda. Za eksperimentalno praÄenje intermitentnog haosa u ovoj tezi je koriÅ”Äena potenciometrijska metoda, koja se inaÄe Å”iroko primenjuje za praÄenje dinamike hemijskih oscilatora. U oba oksihalogenidna sistema, obuhvaÄena tezom, intermitentne oscilacije su uoÄene 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 omoguÄila 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 numeriÄkih metoda, poput onih koja se Äesto 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 PoincarƩ 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 Äelija kvasca Saccharomyces cerevisiae
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 elektriÄnog, magnetnog i elektromagnetnog polja na mikroorganizme je
veoma aktuelni predmet istrazivanja, jer ova fiziÄka polja potencijalno deluju kao faktori
stresa i tako utiÄu 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 Äelija kvasca, S. cerevisiae. Eksperiment je raÄen u
pet ponavljanja i praÄen Micro-OxymaxĀ® respirometrom. Kumulativna potroÅ”nja kiseonika
je bila manja kod Äelija izloženih MP u svih pet ponavljanja, dok je produkcija CO2 bila
nekonzistentna. MeÄutim, ove razlike u potroÅ”nji O2 i produkciji CO2 su statistiÄki znaÄajne.
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
The influence of four low-frequency magnetic field (MF) ranges 10ā300 Hz, 10ā100 Hz, 10ā50 Hz and 50ā100 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 BrayāLiebhafsky Oscillator-Specific Flow Rate Dependence
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 BrayāLiebhafsky (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 minā1 . 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 Äelija kvasca Saccharomyces cerevisiae
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 elektriÄnog, magnetnog i elektromagnetnog polja na mikroorganizme je veoma aktuelni predmet istrazivanja, jer ova fiziÄka polja potencijalno deluju kao faktori stresa i tako utiÄu 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 Äelija kvasca, S. cerevisiae. Eksperiment je raÄen u pet ponavljanja i praÄen Micro-OxymaxĀ® respirometrom. Kumulativna potroÅ”nja kiseonika je bila manja kod Äelija izloženih MP u svih pet ponavljanja, dok je produkcija CO2 bila nekonzistentna. MeÄutim, ove razlike u potroÅ”nji O2 i produkciji CO2 su statistiÄki znaÄajne. 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 Äelija kvasca Saccharomyces cerevisiae
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 elektriÄnog, magnetnog i elektromagnetnog polja na mikroorganizme je veoma aktuelni predmet istrazivanja, jer ova fiziÄka polja potencijalno deluju kao faktori stresa i tako utiÄu 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 Äelija kvasca, S. cerevisiae. Eksperiment je raÄen u pet ponavljanja i praÄen Micro-OxymaxĀ® respirometrom. Kumulativna potroÅ”nja kiseonika je bila manja kod Äelija izloženih MP u svih pet ponavljanja, dok je produkcija CO2 bila nekonzistentna. MeÄutim, ove razlike u potroÅ”nji O2 i produkciji CO2 su statistiÄki znaÄajne. 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 Äelija kvasca Saccharomyces cerevisiae
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 elektriÄnog, magnetnog i elektromagnetnog polja na mikroorganizme je
veoma aktuelni predmet istrazivanja, jer ova fiziÄka polja potencijalno deluju kao faktori
stresa i tako utiÄu 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 Äelija kvasca, S. cerevisiae. Eksperiment je raÄen u
pet ponavljanja i praÄen Micro-OxymaxĀ® respirometrom. Kumulativna potroÅ”nja kiseonika
je bila manja kod Äelija izloženih MP u svih pet ponavljanja, dok je produkcija CO2 bila
nekonzistentna. MeÄutim, ove razlike u potroÅ”nji O2 i produkciji CO2 su statistiÄki znaÄajne.
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 Äelija kvasca Saccharomyces cerevisiae
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 elektriÄnog, magnetnog i elektromagnetnog polja na razliÄite mikroorganizme, jer pomenuta fiziÄka polja potencijalno deluju kao faktori stresa i tako utiÄu 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 Äelija kvasca, Saccharomyces cerevisiae. Eksperimenti su raÄeni u pet ponavljanja i kumulativna potroÅ”nja O2 i produkcija CO2 praÄena je pomoÄu Micro-OxymaxĀ® respirometra. U svih pet ponavljanja, Äelije koje su bile izložene magnetnom polju pokazale su manju kumulativnu potroÅ”nju kiseonika u poreÄenju sa uzorcima van magnetnog polja i nekonzistentnu produkciju CO2. Rezultati su obraÄeni uporednim jednosmernim T-testom, koji je pokazao da postoje statistiÄki znaÄajne razlike u kumulativnoj potroÅ”nji O2 izmeÄu kontrolnih Äelija i onih izloženih magnetnom polju, Å”to nije sluÄaj 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
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
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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