Оne-dimensional maps of the complex and chaotic oscillations of Bray-Liebhafsky reaction

Cilj disertacije je razvijanje novih metoda obrade i korišćenja 1D mapa u analizi vremenskih serija dinamičkih sistema i njihova primena za razlikovanje različitih tipova dinamike u oscilatornoj reakciji Bray-Liebhafsky. U literaturi se navodi da se uspešnost modeliranja na bazi predloženog modela mehanizma posmatrane reakcije procenjuje na osnovu stepena usaglašenosti simuliranih rezultata sa eksperimentalnim rezultatima. Modeliranje oscilatornih reakcija koje se odigravaju u uslovima udaljenim od termodinamičke ravnoteže je dodatno otežano kompleksnošću ovih reakcija, odnosno činjenicom, da model mehanizma oscilatorne reakcije mora da opiše i brojne dinamičke fenomene karakteristične za nelinerane sisteme: pojavu predoscilatornog perioda, oscilacija, determinističkog haosa, bifurkacija, pobudljivosti oscilatornog sistema i ostale moguće oblike nelinearnosti. U literaturi postoje eksperimentalna i teorijska ispitivanja dinamičkih stanja oscilatorne BL rekacije. Teorijska ispitivanja su zasnovana na numeričkim simulacijama procesa, a na bazi pretpostavljenog modela BL reakcije. To je upravo urađeno u ovoj disertaciji za slučaj procesa u otvorenom-protočnom reaktoru. Rezultati su saglasni sa već postojećima da su dinamička stanja veoma osetljiva na promenu brzine protoka supstanci kroz reaktor, odnosno da se složena dinamička stanja nalaze u veoma uzanom opsegu vrednosti kontrolnog prametra j0, odnosno u uzanom delu koncentracionog faznog prostora. Dinamika složenih reakcionih sistema se može ispitivati na više načina. U literaruti i u disertaciji su opisani postupci: analiza vremenskih serija, analiza atraktora, bifurkaciona analiza, Poenkareovi preseci i jednodimenzione (1D) povratne (iteracione) mape. 1D povratne mape prikazuju dinamičku struktura Poenkareovog preseka preko zavisnost n+1-ve vrednosti posmatrane veličine u tački preseka atraktora od njene n-te vrednosti u prethodnoj tački preseka istog atraktora. Ove mape se relativno retko koriste u literaturi kao metoda za ispitivanje dinamičkih stanja reakcionih sistema, iako je kvalitativno ponašanje 1D mapa veoma korisno da objasni i čak i predvidi različite bifurkacije. U disertaciji se posebno razmatra prednost 1D mapa nad drugim metodama kada je potrebno utvrditi pri kojim protocima se javljaju periodična, a pri kojim...The aim of this Doctoral Dissertation is development of new methods 1D maps using in analysis of time series of dynamical systems and the application thereof to distinguish among different types of dynamics in oscillatory Bray-Liebhafsky reaction. The literature states that the success of the modeling based on the proposed model of the mechanism of the observed reactions, is estimated based on the degree of conformity of simulated results with experimental results. Modeling of oscillatory reactions, taking place under conditions far from thermodynamic equilibrium is further hampered by the complexity of these reactions, and the fact that model oscillatory reaction mechanism must describe a number of dynamic phenomena characteristic of nonlinear systems: the pressence of preoscillatory period, oscillations, deterministic chaos, bifurcation, excitability, oscillatory systems and other possible forms of nonlinearity. The literature records experimental and theoretical study of dynamics of oscillatory BL reactions. Theoretical studies are based on numerical simulations of the reaction process, based on the assumed model of BL reaction. This was exactly done in this dissertation, for the reaction in an open-flow reactor. The results are consistent with the existing ones, confirming dynamic states to be highly sensitive to changes in the flow rate of substances through the reactor, i.e the complex dynamic states range within narrow set of values of the control parameter j0, or in a narrow range of the concentration in phase space. The dynamics of complex reaction systems can be examined in several ways. The reference sources and Dissertation describes procedures: the analysis of time series, attractors analysis, bifurcation analysis, Poincare sections and one-dimensional (1D) (iteration) map. 1D return maps show the dynamic structure of the Poincare-section dependence through n + 1- values of the observed parameter in the attractor cut-point of its n-th value in the preceding cut-point of the same attractor section. These maps are relatively rarely used in the reference sources as a method for testing the dynamic state of the reaction system, although the qualitative behavior of 1D map is very useful in provding explanation, even predicting different bifurcations. The dissertation, ponders especially the advantage of 1D maps over other methods when it is necessary to determine periodical, i.e chaotic dynamic situation, i.e..

Sadržaj olova, žive i arsena u začinima - crni, beli i zeleni biber, crni kim i đumbir

In order to evaluate the safety of selected commercial spices brands, concentration of lead, mercury and arsenic, as well as moisture and mineral contents were analyzed in samples of dried black and white pepper powders, black, white and green peppercorns, black cumin seeds and ginger powder. Lead (Pb), mercury (Hg) and arsenic (As) concentrations in spice samples purchased from local markets in Belgrade were determined, after a microwave digestion of the samples, by atomic absorption spectrometry (AAS), using the graphite furnace AAS technique (Pb), cold vapor AAS technique (Hg) and hydride generation AAS technique (As). Trace levels of Pb, Hg and As in the selected dried spices samples were in the range 0.10 ppm - 0.79 ppm, 0.01 ppm - 0.10 ppm and 0.01 ppm - 0.51 ppm, respectively. The maximum Pb concentration was determined in the sample of ginger and it was 0.79 ppm, the maximum concentration of Hg was 0.10 ppm, determined in green peppercorns samples, while the maximum concentration of As in powdered black pepper sample was 0.51 ppm. The moisture and mineral contents in the different analyzed spices were in the range 1.70-13.10% and 3.40-6.50%, respectively. According to the obtained results, the concentrations of the analyzed toxic elements, as well as the moisture and mineral content in selected spices, were below the maximum permissible limits declared by the national legislations deemed safe for human consumption.U ovom radu, u cilju utvrđivanja bezbednosti odabranih komercijalnih začina, analizirane su koncentracije teških metala, kao i sadržaj vlage i ukupnih mineralnih materija, u uzorcima sušenog crnog i belog bibera u prahu, crnog, belog i zelenog bibera u zrnu, semena crnog kima i đumbira u prahu. Koncentracije olova (Pb), žive (Hg) i arsena (As) u uzorcima začina iz lokalnih prodavnica u Beogradu, određene su nakon mikrotalasne digestije atomskom apsorcionom spektrometrijom (AAS), primenom tehnike grafitne peći (Pb), tehnike hladne pare (Hg) i hidridne tehnike (As). Određene koncentracije Pb, Hg i As u uzorcima sušenih začina su u opsegu 0,10 ppm - 0,79 ppm, 0,01 ppm - 0,10 ppm i 0,01 ppm - 0,51 ppm, redom. Maksimalna koncentracija Pb od 0,79 ppm određena je u uzorku đumbira, maksimalna koncentracija Hg od 0,10 ppm u uzorcima zelenog bibera u zrnu, dok je maksimalna koncentracija As određena u uzorku crnog bibera u prahu i iznosila je 0,51 ppm. U uzorcima ispitivanih začina sadržaj vlage i mineralnih materija je u opsegu 1,70-13,10% i 3,40-6,50%, redom. Dobijeni rezultati pokazuju da su koncentracije ispitivanih teških metala, kao i sadržaj vlage i mineralnih materija ispod maksimalno dozvoljenih vrednosti propisanih zakonskom regulativom Republike Srbije, kao i da su ispitivani uzorci crnog, belog i zelenog bibera u prahu i zrnu, crnog kima u zrnu i đumbira u prahu propisanog kvaliteta u ovom smislu

LEAD, MERCURY AND ARSENIC CONTENT IN SPICES: BLACK, WHITE AND GREEN PEPPER, BLACK CUMIN AND GINGER

In order to evaluate the safety of selected commercial spices brands, concentration of lead, mercury and arsenic, as well as  moisture and mineral contents were analyzed in samples of dried black and white pepper powders, black, white and green peppercorns, black cumin seeds and ginger powder. Lead (Pb), mercury (Hg) and arsenic (As) concentrations in spice samples purchased from local markets in Belgrade were determined, after a microwave digestion of the samples, by atomic absorption spectrometry (AAS), using the graphite furnace AAS technique (Pb), cold vapor AAS technique (Hg) and hydride generation AAS technique (As). Trace levels of Pb, Hg and As in the selected dried spices samples were in the range 0.10 ppm - 0.79 ppm, 0.01 ppm - 0.10 ppm and 0.01 ppm - 0.51 ppm, respectively. The maximum Pb concentration was determined in the sample of ginger and it was 0.79 ppm, the maximum concentration of Hg was 0.10 ppm, determined in green peppercorns samples, while the maximum concentration of As in powdered black pepper sample was 0.51 ppm. The moisture and mineral contents in the different analyzed spices were in the range 1.70-13.10% and 3.40-6.50%, respectively. According to the obtained results, the concentrations of the analyzed toxic elements, as well as the moisture and mineral content in selected spices, were below the maximum permissible limits declared by the national legislations deemed safe for human consumption.SADRŽAJ OLOVA, ŽIVE I ARSENA U ZAČINIMA: CRNI, BELI I ZELENI BIBER, CRNI KIM I ĐUMBIRU ovom radu, u cilju utvrđivanja bezbednosti odabranih komercijalnih začina, analizirane su koncentracije teških metala, kao i sadržaj vlage i ukupnih mineralnih materija, u uzorcima sušenog crnog i belog bibera u prahu, crnog, belog i zelenog bibera u zrnu, semena crnog kima i đumbira u prahu. Koncentracije olova (Pb), žive (Hg) i arsena (As) u uzorcima začina iz lokalnih prodavnica u Beogradu, određene su nakon mikrotalasne digestije atomskom apsorcionom spektrometrijom (AAS), primenom tehnike grafitne peći (Pb), tehnike hladne pare (Hg) i hidridne tehnike (As). Određene koncentracije Pb, Hg i As u uzorcima sušenih začina su u opsegu 0,10 ppm - 0,79 ppm, 0,01 ppm - 0,10 ppm i 0,01 ppm - 0,51 ppm, redom. Maksimalna koncentracija Pb od 0,79 ppm određena je u uzorku đumbira, maksimalna koncentracija Hg od 0,10 ppm u uzorcima zelenog bibera u zrnu, dok je maksimalna koncentracija As određena u uzorku crnog bibera u prahu i iznosila je 0,51 ppm. U uzorcima ispitivanih začina sadržaj vlage i mineralnih materija je u opsegu 1,70-13,10% i 3,40-6,50%, redom. Dobijeni rezultati pokazuju da su koncentracije ispitivanih teških metala, kao i sadržaj vlage i mineralnih materija ispod maksimalno dozvoljenih vrednosti propisanih zakonskom regulativom Republike Srbije, kao i da su ispitivani uzorci crnog, belog i zelenog bibera u prahu i zrnu, crnog kima u zrnu i đumbira u prahu propisanog kvaliteta u ovom smislu.HIGHLIGHTSCommercially formulated anti-dandruff shampoos contain zinc pyrithione (ZPT) as an active ingredient that has antifungal, antibacterial and anti-seborrheic effects;In ZPT, pyrithione (PT) forms a complex with a zinc ion in the 2 : 1 ratio;Determination of ZPT concentration in commercial anti-dandruff shampoos by differential pulse polarography was based on an electrochemical reduction of zinc ions in ammoniacal buffer at pH 10.2;Surface active ingredients (anionic and amphoteric) and micro-components in the shampoos did not exert a polarographic interference for the determination of zinc and did not affect the determination of the content of ZPT active ingredient;This simple and sensitive differential pulse polarography method is suitable for a routine and rapid control of the active ingredient content, as well as for the quality control of anti-dandruff shampoos

Influence of hydroxycinnamic acids on the oxy-radical generated iodide/hydrogen peroxide reaction system

The influence of hydroxycinnamic acids (HCA): caffeic acid, chlorogenic acid, and p-coumaric acid, on the potassium iodide/hydrogen peroxide system was investigated. A linear correlation between absorption maximum of triiodide (I3 -) at 351 nm and HCA concentration was found. In the presence of HCA, reaction yield of I3 - was found to increase in following order p-cumaric < chlorogenic ≤ caffeic acid. This is attributing to their oxyradical scavenging activity. Results obtained in this study have showed correlation between antioxidant activities of HCA and their ability to enhanced I3 - production

Kvalitet i bezbednost nekih komercijalnih začina

In this study, in order to evaluate the quality and safety of selected commercial spices brands, contents of moisture and minerals, as well as the concentration of certain heavy metals (As, Hg and Pb) were determined in oregano, sweet basil, parsley and celery. The spice samples were subjected to microwave digestion, and were analyzed by atomic absorption spectrometry (AAS), using hydride generation AAS technique, cold vapor AAS technique, and graphite furnace AAS technique for determination of As, Hg and Pb, respectively. Maximum concentrations of As and Pb were determined in the same brand sample of celery, and are 0.75 ppm and 0.40 ppm, respectively, while the maximum concentration of Hg in various brands sweet basil samples is 0.05 ppm. According to the results, the contents of moisture and minerals, as well as the concentrations of heavy metals in all selected spices were below the maximum permissible limits declared by the national legislations, and are safe for human consumption.U ovom radu, u cilju određivanja kvaliteta i bezbednosti izabranih začina, određen je sadržaj vlage i ukupnih mineralnih materija, kao i koncentracije arsena (As), žive (Hg) i olova (Pb) u uzorcima origana, bosiljka, peršuna i celera. Koncentracije teških metala As, Hg i Pb, nakon mikrotalasne digestije, određene su različitim analitičkim tehnikama atomske apsorcione spektrometrije, primenom hidridne tehnike (As), tehnike hladne pare (Hg) i tehnike grafitne peći (Pb). Maksimalne koncentracije As i Pb određene su u istom uzorku celera i iznose 0,75 ppm i 0,40 ppm, respektivno, dok je maksimalna koncentracija Hg određena u uzorcima bosiljka i iznosi 0,05 ppm. U uzorcima začina, vrednosti sadržaja vlage, minerala i koncentracije ispitivanih teških metala su ispod maksimalno dozvoljenih vrednosti propisanih zakonskom regulativom Republike Srbije

Karst aquifer average catchment area assessment through monthly water balance equation with limited meteorological data set: Application to Grza spring in Eastern Serbia

In the absence of detailed exploration of karstic catchments, the calculation of available reserves and elements of the water balance equation frequently reflect the topographic size of the catchment area, and not the actual, active (underground) size. The two differ largely where karst is concerned. The paper deals with the problem of average catchment area size estimation in the situation when meteorological data are limited to precipitation and temperature, but discharge records are available for long period. Proposed methodology was applied to, calibrated, and validated on 15 karst springs in Serbia. Results obtained with the model differ up to 20% from hydrogeological exploration results. One of investigated springs is Grza karst spring, which belongs to the karstic formation of Kučaj and Beljanica (the Carpatho-Balkanide Arch of Eastern Serbia). In this paper, we used the Grza Spring to show model application and necessary improvements to progress from graphoanalytical to analytical model. The average catchment area is linked to the model parameter that reduces potential to real evapotranspiration on monthly bases. The model potential lies in the possibility to determine not only catchment area, but real evapotranspiration and dynamic volume of the porous - karst groundwater storage as well

Natural Pigment from Madder Plant as an Eco-Friendly Cathode Material for Aqueous Li and Na-Ion Batteries

Modifying commercial Li-ion batteries to become more environmentally friendly is of a growing concern. This paper provides an examination of a potential replacement for commercial cathode material using a naturally occurring purpurin in aqueous solutions of lithium and sodium salts. The purpurin is extracted from the Madder plant (Rubia tinctorum) and characterized through XRPD, FTIR, and SEM methods. The intercalation and de-intercalation capacities obtained for the purpurin as a cathode material in the aqueous solution of LiNO3 are approximately 40 mAh g(-1). Compared to the capacity of similar to 35 mAh g(-1) obtained for commercially used transition metal oxides in an aqueous solution of Li salt, results presented make the purpurin a promising material for the "green" development of Li-ion batteries. Although the initial purpurin capacity in NaNO3 solution is almost doubled (similar to 73 mA h g(-1)) compared to that of Li-salt, it is unstable and fades during cycling. The possible explanation of the electrochemical behavior of purpurin as the cathode material in aqueous solutions of Li and Na salts is discussed in detail

Physicochemical analysis and phenolic profile of polyfloral and honeydew honey from Montenegro

The research subject of this paper was a detail physicochemical analysis of 28 honey samples from the northern part of Montenegro. The honey from Montenegro has not been previously studied in such detail. Differentiation between samples, such as honeydew honey and polyfloral honey, was based on electrical conductivity, which was higher than 0.8 mS cm-1 for honeydew honey, as was expected. Other investigated physicochemical parameters (water content, free acids, diastase activity, hydroxymethylfurfural (HMF) content and sugar content) have shown great similarity for all honey samples. The main interest of this study was the identification and quantification of phenolic compounds using ultra-high performance liquid chromatography (UHPLC) with mass spectrometry detection. The results show that honey samples are very rich in phenolic compounds, especially quercetin. Among the 31 quantified phenolic compounds, the most dominant were phenolic acids. The highlight was based on p-hydroxybenzoic acid, p-coumaric acid, caffeic acid and ferulic acid. Considering polyphenolic compounds and sugar content, a high nutritional value can be observed in all samples, with an emphasis on polyfloral honeys, as was confirmed with principal component analysis (PCA). In addition, all honey samples were tested for total phenolic content (TPC) and radical scavenging activity (RSA). The results indicate the higher antioxidant ability of honeys from Montenegro in comparison to some honey samples from other countries in the region.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3828

Supplementary data for article: Nešović, M.; Gašić, U.; Tosti, T.; Trifković, J.; Baošić, R.; Blagojević, S.; Ignjatović, L.; Tešić, Ž. Physicochemical Analysis and Phenolic Profile of Polyfloral and Honeydew Honey from Montenegro. RSC Advances 2020, 10 (5), 2462–2471. https://doi.org/10.1039/c9ra08783d

Supplementary material for: [https://doi.org/10.1039/c9ra08783d]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3827