<p>U okviru ove doktorske disertacije, razvijene su elektroanalitičke metode za određivanje odabranih pesticida primenom hronopotenciometrije. Ispitana je mogućnost primene elektrode od staklastog ugljenika i tankoslojne živine elektrode kao radnih elektroda za određivanje insekticida imidakloprida i herbicida metamitrona i metribuzina. U cilju optimizacije uslova hronopotenciometrijske tehnike, za svaki ispitivani sistem (pesticid/radna elektroda) ispitan je uticaj najznačajnijih eksperimentalnih parametara na analitički signal pesticida, uključujući mehanizam generisanja analitičkog signala na radnoj elektrodi (oksidacija/redukcija), optimalnu metodu za uklanjanje rastvorenog kiseonika iz analiziranog rastvora, kao i vrstu, pH i koncentraciju pomoćnog elektrolita. Nakon toga definisan je optimalni opseg potencijala i struje redukcije. Pored toga, u okviru validacije metode za svaki ispitivani sistem, ispitan je i definisan opseg linearnosti, određena granica detekcije i granica kvantifikacije, ispitana preciznost, tačnost, robusnost i selektivnost metode. Dobijeni analitički signal za ispitivane pesticide bio je posledica ireverzibilne redukcije analita na radnoj elektrodi, a za svaki analit dobijen je jedan redukcioni pik. U slučaju određivanja metribuzina eksperimenti su pokazali da se analitički signal ne može detektovati na elektrodi od staklastog ugljenika uz kori&scaron;ćenje dostupne instrumentacije. Ispitivanja u model-rastvorima za svaki ispitivani sistem pokazala su dobre karakteristike u pogledu preciznosti, tačnosti, selektivnosti i robusnosti metode. Najveća osetljivost za sva tri pesticida postignuta je uz primenu tankoslojne živine elektrode, a vrednosti granice detekcije iznosile su 0,17 mg/l za imidakloprid, 0,07 mg/l za metamitron i 0,04 mg/l za metribuzin. Nakon optimizacije i validacije, razvijene hronopotenciometrijske metode primenjene su na komercijalne formulacije pesticida i uzorke vode. U cilju dodatne potvrde hronopotenciometrijskih rezultata na uzorcima vode izvedena su komparativna merenja uz primenu hromatografske LC-MS/MS analize.</p> / <p>Within this doctoral dissertation, electroanalytical methods for the determination of selected pesticides using chronopotentiometry are developed. The possibility of using glassy carbon electrode and thin film mercury electrode as a working electrode for determination of insecticide imidacloprid and herbicides metamitron and metribuzin is investigated. In order to optimize the conditions of the chronopotentiometric technique for each tested system (pesticide/working electrode), the influence of the most important experimental parameters on the analytical signal of the pesticides is investigated, including the generating mechanism of the analytical signal on the working electrode (oxidation/reduction), the optimal method for removal of dissolved oxygen from the analyzed solution, as well as type, pH, and concentration of the supporting electrolyte. Afterwards, the optimal range of potential and reduction current is defined. Additionally, within the validation of the method for each tested system, the linearity range is determined and defined, limit of detection and quantification are determined, and precision, accuracy, robustness and selectivity of the method are tested. The obtained analytical signal for the investigated pesticides is the result of irreversible reduction of the analyte on the working electrode, and for each analyte one reduction peak is obtained. In the case of metribuzin determination, the experiments have shown that by using the available instrumentation the analytical signal can not be detected on the glassy carbon electrode. Investigation in model solutions for each tested system shows good characteristics in terms of precision, accuracy, selectivity and robustness of the method. The highest sensitivity for all three pesticides was achieved by using thin film mercury electrode, and values of detection limit were 0.17 mg/l for imidacloprid, 0.07 mg/l for metamitron and 0.04 mg/l for metribuzin. After optimization and validation, the developed chronopotentiometric methods are applied to commercial pesticide formulations and water samples. In order to further confirm the chronopotentiometric results on the water samples, comparative measurements are performed using chromatographic LC-MS/MS analysis.</p>

<p>Cilj ove doktorske disertacije je bio odrediti niz tehnolo&scaron;kih postupaka koji bi omogućili iskori&scaron;ćenje sremu&scaron;a u prehrambene i farmaceutske svrhe u svežem ili suvom stanju, kao biljne droge za pripremu različitih formi ekstrakata bogatih bioaktivnim jedinjenjima izolovanih iz njega.<br />List sremu&scaron;a bere se u vrlo kratkom vremenskom periodu tokom proleća, a nakon branja njegovi listovi vrlo brzo venu i gube svoja senzorna, nutritivna i funkcionalna svojstva, zbog čega je dostupnost ove biljne sirovine vremenski vrlo ograničena. Zbog toga su ispitani uslovi skladi&scaron;tenja svežeg lista sremu&scaron;a kako bi se sagledala trajnost sremu&scaron;a za konzumiranje u svežem stanju, ali i mogućnost primene skladi&scaron;tenog sremu&scaron;a za ekstrakciju bioaktivnih jedinjenja. Za dobijanje osu&scaron;enog lista sremu&scaron;a ispitan je uticaj različitih tehnika su&scaron;enja (konvektivno i vakuumsko su&scaron;enje) i temperature su&scaron;enja (40, 50, 60 i 70 &deg;C) na sadržaj bioaktivnih komponenti u osu&scaron;enom proizvodu. Primenom odgovarajuće tehnike su&scaron;enja, povećava se stabilnost i dostupnost listova sremu&scaron;a za potrebe prehrambene i farmaceutske industrije. Primenom savremenih ekstrakcionih tehnika kao &scaron;to je ekstrakcije superkritičnim ugljen-dioksidom, ekstrakcije subkritičnom vodom i ultrazvučne ekstrakcije, ispitan je uticaj procesnih parametara različitih ekstrakcionih tehnika, poput ultrazvučne ekstrakcije (temperatura, vreme ekstrakcije, snaga ultrazvuka, uticaj rastvarača) i ekstrakcije subkritičnom vodom (temperatura, vreme ekstrakcije, dodatak modifikatora), superkritične ekstrakcije ugljen-dioksidom (pritisak i temperatura), dok je maceracija kao konvencionalna tehnika ekstrakcije primenjena za poređenje efikasnosti modernih ekstrakcionih postupaka. U dobijenim ekstraktima ispitan je sadržaj polifenolnih komponenti, antioksidantna aktivnost i sadržaj sumpornih jedinjenja u cilju optimizacije ekstrakcionih parametara i radi utvrđivanja uslova ekstrakcije pri kojima se postiže najveći kvalitet ekstrakata u pogledu sadržaja ciljanih bioaktivnih komponenti.&nbsp; Za odabrane ekstrakte ispitan je antimikrobni potencijal na različite Gram pozitivne i Gram negativne bakterijske sojeve. Za dobijanje stabilnijih formi odabranih ekstrakata primenjena je enkpasulacija spray drying i spray congeling tehnikom. Enkapsuliranim ekstraktima su određene fizičko-hemijske osobine (hemijski sastav, sadržaj vlage, higroskopnost, moć rehidratacije, WAI i WSI) i biolo&scaron;ka aktivnost (antimikrobna i antioksidativna aktivnost).</p> / <p>The aim of this doctoral dissertation was to determine various technological procedures that would enable the use of fresh and dryed wild garlic leaves in foods and pharmaceutical industry, as a herbal drug or nutraceuticals.<br />The availability period of fresh wild garlic is very short and only during the spring season. After harvest, the leaves are quite perishable, wither very quickly and lose their sensory, nutritive and functional properties. This makes the availability time of this herbal raw material very limited. Therefore, the conditions for storing the fresh leaves of wild garlic and the influences of storing conditions on composition of bioactive compounds were examined in order to extend their use in fresh state. In order to obtain dry herbal drug for extraction, influence of various drying techniques (convection and vacuum drying) and drying temperatures (40, 50, 60, 70 &deg;C) were examinated. The stability and availability of wild garlic in food and pharmaceutical industries was extended by drying. The influence of process parameters of different modern extraction techniques - ultrasonic extraction (temperature, extraction time, ultrasonic power, solvent effect) and subcritical water extraction , extraction time, modifier addition), supercritical carbon dioxide extraction (pressure and temperature) - was examined, while maceration (as a conventional extraction technique) was used to evaluate the efficiency of modern extraction methods. The obtained extracts were analysed in terms of the polyphenolic content, the antioxidant activity and the content of sulfur compounds in order to optimize the extraction parameters and determine the extraction conditions for achieving the highest quality of extracts in terms of the content of the target bioactive components. Antimicrobial potential for different Gram positive and Gram negative bacterial strains was tested for selected<br />extracts. To obtain more stable forms of selected extracts encapsulation techniques - spray drying and spray congeling - were applied. Encapsulated extracts were evaluated in terms of physico-chemical properties (chemical composition, moisture content, hygroscopicity, rehydration power, WAI and WSI) and biological activity (antimicrobial and antioxidant activity).</p>

<p>U ovoj tezi, uz pomoć literaturnih podataka prezentovano je geografsko poreklo masline i maslinovog ulja, njegova upotreba tokom istorije, proizvodni proces, senzorska svojstva, nutritivna vrednost i sastav masnih kiselina i održivost. U eksperimentalnom delu teze detaljno je analizirano pet uzoraka devičanskih maslinovih ulja-DMU proizvedenih na različitim maslinarskim područjima Libije tokom dve uzastopne proizvodne godine. Krakteristike ovih ulja su upoređene sa karakteristikama ekstra devičanskih maslinovih ulja najpoznatijih svetskih proizvođača, Italije. &Scaron;panije i Grčke. Najvažnije masne kiseline u maslinovom ulju su sedam glavnih masnih kiselina- MK koje su detektovane u uzorcima DMU. Oleinska, palmitinska i linolna kiselina su dominantne, dok su druge MK detektovane u malim količinama.Najveći procenat palmitinske kiseline nadjen je u DMU sa područja Tripoli (P &le; 0,05). Oleinska kiselina je dominantna u svim uzorcima DMU.Ustanovljeno je da je Libijsko DMU sa područja Gharyan poseduje najvi&scaron;u koncentraciju oleinske kiseline, mononezasićenih masnih kiselina, najvi&scaron;i sadržaj bioaktivnih jedinjenja i najbolju nutritivnu vrednost.Bioaktivna jedinjenja u maslinovom ulju su tokoferoli, fenoli i pigmenti. Ova jedinjenja čine maslinovo ulje veoma zdravim. Ispitivana je, takođe, i fotostabilnost DMU pod uticajem fluorescentnog svetla u periodu od 35 dana. Ovi eksperimenti su sprovedeni sa tri uzorka DMU sa poreklom iz Libije u poređenju sa uljem iz Italije. Uzorci su bili izloženi fluorescentnom svetlu u providnoj i tamno smeđoj staklenoj ambalaži. Posmatrane su izmene karakteristika boje i rezultati su pokazali da fluorescentna svetlost utiče na smanjenje kvaliteta DMU vi&scaron;e u uzorcima u transparentnoj ambalaži u poređenju sa onima u tamno smeđoj ambalaži.Osim toga, ispitana je i termostabilnost boje DMU primenom Schaal-Oven testa pod uticajem umerene temperature od 63 &plusmn; 2&deg;C tokom perioda od 28 dana. Najmanje promene karakteristika i parametri najboljeg kvaliteta zabeležene su uzorku Gharyan DMU. Uzorak je sadržavao vi&scaron;e pigmenata i fenolnih jedinjenja u poređenju sa uzorkom iz Italije i gubitak je bio najmanji za parametre boje. Pozitivna veza između jodnog broja i polinezasićenih masnih kiselina je registrovana sa koeficijentom korelacije r = +0,927. Primećena je i snažna pozitivna veza između sadržaja hlorofila i (a*) vrednosti boje, (r = + 0,859). Snažna pozitivna veza između TPC i AC (1/EC50DPPH) je takodje primećena, r je bio + 0,511. S druge strane, (1/EC50DPPH) je pokazao pozitivnu umerenu korelaciju sa TTC, (r = + 0,587).</p> / <p>In this thesis, with the help of literature data, the geographical origin of olive and olive oil, its use during history, production process, sensory properties, nutritive value and composition of fatty acids and sustainability were presented. In the experimental part of the thesis, five samples of virgin olive oils-VOO produced in various olive growing regions of Libya were analyzed in detail over the two consecutive production years. The qualities of these oils are compared with the characteristics of extra virgin olive oils of the world&#39;s most famous producers, Italy. Spain and Greece. The most important fatty acids in olive oil are the seven major fatty acids - FA that are detected in the VOO samples. Oleic, palmitic and linolenic acid are dominant, while other FAs are detected in small amounts. The largest percentage of palmitic acid was found in the VOO from the Tripoli area (P &le; 0.05). Oleic acid is dominant in all VOO samples. It has been found that the Libyan VOO from the Gharyan region has the highest concentration of oleic acid, monounsaturated fatty acids, the highest content of bioactive compounds and the best nutritional value. Bioactive compounds in olive oil are tocopherols, phenols and pigments. These compounds make olive oil very healthy. The VOO&#39;s photostability under the influence of fluorescent light for a period of 35 days was also examined. These experiments were carried out with three samples of VOO originating in Libya in comparison with oil from Italy. Samples were exposed to fluorescent light in transparent and dark brown glass containers. Changes in color characteristics were observed and the results showed that fluorescent light influences the quality of VOO more in samples in transparent packaging compared to those in dark brown packaging. In addition, the VOO color thermostability was tested using a Schaal-Oven test under the influence of a moderate temperature of 63 &plusmn; 2&deg;C over a period of 28 days. The smallest changes in characteristics and parameters of the best quality were recorded in the Gharyan VOO sample. The sample contained several pigments and phenolic compounds compared to the sample from Italy and the loss was the smallest for the color parameters. The positive relationship between iodine and polyunsaturated fatty acids is registered with the coefficient of correlation r = + 0.927. A strong positive relationship between the content of chlorophyll and (a*) of the color value was noted, (r = + 0.859). A strong positive association between TPC and AC (1/EC50DPPH) was also observed, r was + 0.511. On the other hand, (1/EC50DPPH) showed a positive moderate correlation with TTC, (r = + 0.587).</p>

<p style="text-align: justify;">Plodovi jabuke su tokom čitave godine prisutni u ishrani beba, dece i odraslih ljudi zbog čega je kvalitet i zdravstevena bezbednost ovih namirnica od izuzetnog značaja. Veliki broj fitopatogenih gljiva su prouzrokovači bolesti jabuka međutim, među značajnim prouzrokovačima bolesti jabuka u skladi&scaron;tima spominju se gljive iz rodova Alternaria i Fusarium. Smatra se da su zdravstveno bezbedni plodovi jabuke pre svega zdravi plodovi, bez prisustva fitopatogenih gljiva i bez ostataka fungicida. Sve veća briga oko primene sintetičkih fungicida zbog njihove toksičnosti, razvoja rezistentnosti patogena na fungicide i &scaron;tetnih efekata na životnu sredinu i zdravlje ljudi, doveli su do potrebe za pronalaženjem alternative hemijskoj za&scaron;titi, a jedno od mogućih se ogleda upravo u primeni biotehnolo&scaron;kim postupkom proizvedenih agenasa. Budući da su visoki tro&scaron;kovi biotehnolo&scaron;ke proizvodnje osnovna prepreka za &scaron;iru primenu ovih agenasa, optimizacija uslova izvođenja biosinteze predstavlja najvažniji korak ka njenom prevazilaženju. Stoga je kao cilj istraživanja u okviru ove doktorske disertacije definisana optimizacija biosinteze antagonista skladi&scaron;nih patogena jabuke primenom Streptomyces hygroscopicus na nivou laboratorijskog bioreaktora u pogledu odabira izvora ugljenika i azota i količina izvora ugljenika, azota i fosfora u hranljivoj podlozi za biosintezu željenih antagonističkih agenasa, kao i parametara biosinteze sa posebnim osvrtom na intenzitet primenjene aeracije i me&scaron;anja. Analizom dobijenih rezultata zaključeno je da se podloga za kultivaciju S. hygroscopicus koja je sadržala glicerol i pored već prisutnog azota u podlozi nije sadržala dodatni izvor azota, pokazala kao najpogodnija za produkciju željenih antagonističkih agenasa efikasnih protiv izolata vrsta A. alternata i F. avenaceum. Rezultati optimizacije sastava hranljive podloge ukazuju da se primenom definisanih optimalnih vrednosti ispitivanih faktora, koje su: sadržaj glicerola od 20 g/l, sadržaj (NH₄)₂SO₄ od 0,25 g/l i sadržaj K₂HPO₄ od 1,41 g/l u podlozi za biosintezu antagonista skladi&scaron;nih patogena jabuke primenom S. hygroscopicus, na osnovu definisanih matematičkih modela predviđaju sledeće vrednosti parametara toka i parametara uspe&scaron;nosti biosinteze antagonista skladi&scaron;nih patogena jabuke: rezidualni glicerol od 5,3418 g/l; rezidualni azot od 0,193 g/l; rezidualni fosfati od 0,8601 g/l; prečnik zone inhibicije rasta micelije izolata A. alternata KA10 od 28,22 mm; prečnik zone inhibicije rasta micelije izolata A. alternata T1Jg3 od 36,86 mm; prečnik zone inhibicije rasta micelije izolata F. avenaceum KA12 od 25,54 mm i prečnik zone inhibicije rasta micelije izolata F. avenaceum KA13 od 26,78 mm. Rezultati dobijeni ispitivanjem uticaja različitog intenziteta aeracije i brzine me&scaron;anja na biosintezu antagonista skladi&scaron;nih patogena jabuke primenom S. hygroscopicus u laboratorijskom bioreaktoru standardnih geometrijskih odnosa ukupne zapremine 3 l ukazuju da se primenom definisanih optimalnih vrednosti ispitivanih faktora, brzine me&scaron;anja od 100 o/min, intenziteta aeracije od 1,2 l/l/min i pri trajanju kultivacije od 96 h na osnovu definisanih matematičkih modela predviđaju sledeće vrednosti parametara toka i parametara uspe&scaron;nosti biosinteze antagonista skladi&scaron;nih patogena jabuke: rezidualni glicerol od 8,2645 g/l; rezidualni azot od 0,1723 g/l; rezidualni fosfati od 0,5167 g/l; suva materija 1,5023 g/l; prečnik zone inhibicije rasta micelije izolata A. alternata KA10 od 62,62 mm; prečnik zone inhibicije rasta micelije izolata A. alternata T1Jg3 od 61,09 mm; prečnik zone inhibicije rasta micelije izolata F. avenaceum KA12 od 45,55 mm i prečnik zone inhibicije rasta micelije izolata F. avenaceum KA13 od 43,02 mm. Validnost dobijenih rezultata potvrđena je izvođenjem biosinteze antagonista skladi&scaron;nih patogena jabuke na podlozi optimalnog sastava i primenom optimalnih procesnih parametara u laboratorijskom bioreaktoru standardnih geometrijskih odnosa ukupne zapremine 7l, a efikasnost produkovanih antagonističkih agenasa efikasnih na izolate A. alternata (KA10 i T1Jg3) i F. avenaceum (KA12 i KA13) potvrđena je i u in planta ogledima. Ostavreni rezultati optimizacije biosinteze antagonista skladi&scaron;nih patogena jabuke primenom Streptomyces hygroscopicus na nivou laboratorijskog bioreaktora predstavljaju osnovu za dalje uvećanje razmera do industrijskih, &scaron;to je ključni korak ka potencijalnoj industrijalizaciji predloženog proizvodnog postupka.</p> / <p>Apple fruits are available on the market all year round and their safety is of great importance for the consumers. Unfortunately, many phytopathogenic fungi can cause apple diseases but fungi from the genera Alternaria and Fusarium are listed among important storage pathogens of apple fruits. It is considered that health-safe apple fruits are primarily healthy fruits, without the presence of phytopathogenic fungi and without the remains of fungicides. Excessive use of pesticides in modern agriculture, including those used for control of fungal phytopathogens, has led to several problems related to pollution, environmental degradation and emergence of resistant strains. Biological<br />control of plant pathogens by means of microorganisms is considered as an attractive alternative to chemical-based treatments, with minimal impact on the environment. The main lack of biotechnology production of the antifungal agents are the high costs, so the optimization of the biosynthesis conditions is the most important step towards its overcoming. Therefore, the aim of this research is to optimize the medium composition and process conditions (agitation and aeration rate) of the antagonists of storage apple pathogens biosinthesis by Streptomyces hygroscopicus in laboratory-scale bioreactor. Based on the obtained results, it can be concluded that the S. hygroscopicus cultivation medium containing glycerol as a carbon source, with no additional nitrogen source, proved to be the most suitable for the production of the A. alternate and F. avenaceum antagonistic agents. The results of the optimization of medium for biosynthesis of the antagonists of storage apple pathogens using S. hygroscopicus indicated the following optimal values of the examined factors: the content of glycerol of 20 g/l, (NH₄)₂SO₄ of 0.25 g/l and K₂HPO₄ of 1.41 g/l. By applying the defined optimal values and using the appropriate mathematical models, the following responses are predicted: residual glycerol of 5.3418 g/l; residual nitrogen of 0.193 g/l; residual phosphates of 0.8601 g/l; inhibition zone diameters of A. alternata KA10 of 28.22 mm; inhibition zone diameters of A. alternata T1Jg3 of 36.86 mm; inhibition zone diameters of F. avenaceum KA12 of 25.54 mm and inhibition zone diameters of F. avenaceum KA13 of 26.78 mm. Examining the effect of different agitation and aeration rate on the biosynthesis of antagonists of storage apple pathogens using S. hygroscopicus in a laboratory-scale bioreactor with total volume of 3 l, the following optimal values of the investigated factors are obtained: the agitation rate of 100 rpm, the aeration of 1.2 l/l/min and 96-hour as optimal time of cultivation. Bringing together the appropriate mathematical models and defined optimal values, the following responses are predicted: residual glycerol of 8.2645 g/l; residual nitrogen of 0.1723 g/l; residual phosphates of 0.5167 g/l; biomass content of 1.5023 g/l; inhibition zone diameters of A. alternata KA10 of 62.62 mm; inhibition zone diameters of A. alternata T1Jg3 of 61.09 mm; inhibition zone diameters of F. avenaceum KA12 of 45.55 mm and inhibition zone diameters of F. avenaceum KA13 of 43.02 mm. The validity of the results was confirmed by performing the biosynthesis of the antagonists of storage apple pathogens in the medium with optimal composition and the optimal process parameters in a laboratory-scale bioreactor with the total volume of 7l. The efficacy of produced antagonistic agents effective against A. alternata (KA10 and T1Jg3) and F. avenaceum (KA12 and KA13) isolates was confirmed in vitro and in planta. The results obtained within this research represents the basis for the further enlargement of the scale, which is a key step towards the potential industrialization of the proposed production process.</p>

<p>Cilj ove doktorske disertacije je dobijanje vi&scaron;estrukih V₁/U/V₂ emulzija kao nosača aktivnih materija u dvostepenom postupku, pri čemu se za drugi korak pripreme koristi tehnika membranskog emulgovanja (ME), na membrani od sinterovanog stakla implementiranoj u ćeliju sa me&scaron;anjem. Proces ME koristi se u svrhu unapređenja karakteristika formiranih emulzija, u smislu bolje kontrole veličine i raspodele veličina formiranih kapi, koje mogu da dovedu do razlika u stepenu inkapsulacije aktivnih materija u unutra&scaron;njoj vodenoj fazi, u odnosu na proces u kome se za drugi korak pripreme emulzija koristi tehnika homogenizacije.<br />Kompletna optimizacija sastava V₁/U emulzija, koja obuhvata određivanje koncentracije hidrofobnog emulgatora (PGPR), lipofobne materije (NaCl) i tikvinog ulja kao sekundarne aktivne komponente, rezultirala je formiranjem stabilnih nanoemulzija sa pobolj&scaron;anim nutritivnim svojstvima. Nutritivno unapređeni emulzioni sistemi optimizovanog sastava kori&scaron;ćeni su za inkapsulaciju primarnih aktivnih komponenata (vodenog i etanolnog ekstrakata belog luka) u cilju za&scaron;tite bioaktivnih sastojaka i maskiranja neprijatnog mirisa i ukusa. Nakon definisanja sastava svih faza vi&scaron;estrukih emulzija, koje ukljuĉuje određivanje tipa hidrofilnog emulgatora i njegove koncentracije, kao i ispitivanja uticaja dodavanja osmotskog regulatora (glukoze) u spolja&scaron;nju vodenu fazu na stabilnost sistema i difuziju lipofoba, formirane su vi&scaron;estruke emulzije sa unetim aktivnim komponentama membranskim emulgovanjem u ćeliji sa me&scaron;anjem. Sistematiĉna karakterizacija membrane od sinter stakla kao ekonomski opravdanog membranskog materijala, dala je mogućnost njegove primene u procesu. Detaljno ispitivanje uticaja procesnih parametara (transmembranskog pritiska i brzine me&scaron;anja) i vi&scaron;ekriterijumska optimizacija procesa ME, dovela su do formiranja vi&scaron;estrukih emulzija sa užom raspodelom veličina kapi, koja je indirektno uticala i na pobolj&scaron;anje zadržavanja inkapsuliranog materijala u unutra&scaron;njosti emulzija tokom vremena, u odnosu na emulzije pripremljene u postupku homogenizacije.</p> / <p style="text-align: justify;">The aim of this doctoral thesis was to prepare multiple W/O/W emulsions with encapsulated active substances in both phases, by a two-step process, where the stirred cell membrane emulsification (ME) process, with a sintered glass filter disk as a membrane, was used as the second step, instead of conventional process (homogenization). The ME process was employed in order to improve the characteristics of the formed emulsions, in terms of better control of the size and droplet size distribution, that can change the encapsulation degree of active ingredients in the internal aqueous phase.<br />The complete optimization of W/O emulsion composition, which includes determination of optimal contents of a hydrophobic emulsifier (PGPR), a lipophobic substance (NaCl) and pumpkin seed oil as an active component of the oil phase, resulted in the formation of stable nanoemulsions with improved nutritional properties. This nutritionally enhanced emulsion was used to encapsulate primary active ingredients (aqueous and ethanol garlic extract), in order to protect instable bioactive compounds of the extracts and mask the unpleasant smell and taste. After defining the composition of all phases of multiple emulsions, which includes determination of a suitable hydrophilic emulsifier and its optimal content, as well as examining the effect of addition of an osmotic regulator (glucose) in the external aqueous phase on the emulsion stability and lipophobe diffusion, multiple emulsions with encapsulated active components were formed by membrane emulsification in the stirred cell. The complete characterization of the sintered glass as an economically favourable membrane material, gave the possibility of its application in the process. Investigation of the influence of process parameters (transmembrane pressure and impeller rotation speed) and multiobjective optimization of ME, led to the formation of the multiple emulsions with a narrow droplet size distribution, which had improved retention of encapsulated material in the internal water phase over time, relative to the emulsions prepared by the homogenization process.</p>

<p style="text-align: justify;">Betain je bioaktivno jedinjenje, koje ima značajne fiziolo&scaron;ke funkcije u čovekovom organizmu kao osmolit i donor metil grupa za mnoge biohemijske procese. Endogena sinteza betaina je uglavnom nedovoljna da zadovolji potrebe organizma te je zbog toga neophodan njegov unos preko hrane. Žitarice predstavljaju glavni izvor betaina u ljudskoj ishrani. Jedan od načina da se poveća unos betaina u ljudskoj ishrani je preko funkcionalne hrane obogaćene betainom. Prema regulativi evropskog udruženja cerealija za doručak (European Breakfast Cereal Association) iz 2012. god. (Commission Regulation (EU) No 432/2012) dozvoljeno je deklarisanje zdravstvene izjave za prehrambene proizvode koji sadrže najmanje 500 mg betaina po porciji (40g flips proizvoda) uz navođenje napomene da se zdravstveni efekti mogu očekivati ukoliko se dnevno unese 1500 mg betaina. Zdravstvena izjava glasi: &bdquo;betain doprinosi normalnom metabolizmu homocisteina&ldquo;. Povećano interesovanje za zdravu ishranu dovelo je do veće potražnje za alternativnim žitaricama, gde spelta zbog svojih biolo&scaron;kih, agronomskih, prehrambenih i medicinskih karakteristika kao i bogatih nutritivnih svojstava, zauzima značajno mesto. Glavni cilj ove teze je bila optimizacija ekstrudiranja i proizvodnje funkcionalnog flips proizvoda od speltinog integralnog bra&scaron;na sa dodatkom betaina na dvopužnom ekstruderu. Prvi put je u procesu prehrambenog ekstrudiranja primenjena analiza vi&scaron;eciljne optimizacije u kombinaciji sa neuronskim mrežama i genetskim algoritmom kako bi se dobio maksimalan sadržaj betaina u flips proizvodu pri minimalnoj potro&scaron;nji specifične mehaničke energije. Definisan je nov funkcionalni proizvod sa betainom koji bi potencijalno pro&scaron;irio asortiman flips proizvoda na trži&scaron;tu i utvrđene su njegove fizičke, funkcionalne, teksturalne, reolo&scaron;ke i senzorske osobine. Sadržaj betaina i potro&scaron;nja specifične mehaničke energije su ključni izlazi koji predstavljaju konkurentne ciljeve u procesu ekstrudiranja. Za proizvodnju flips proizvoda pobolj&scaron;anog nutritivnog kvaliteta i funkcionalnog profila koji sadrži od 1601,6 do 1764,7 mg betaina u 40 g (čime se i zadovoljava preporučeni dnevni unos betaina) i kome odgovara potro&scaron;nja specifične mehaničke energije od 97,4 do 114,1 Wh/kg optimalni su sledeći procesni parametri: protok materijala od 20,45 do 24,04 kg/h, vlaga materijala od 18,6 do 19,44 % i brzina obrtanja pužnice od 250 obrtaja u minuti. Da bi se dobili pouzdani rezultati za sadržaj betaina u spelti i flips proizvodima razvijena je, optimizovana i validovana metoda tečne hromatografije visokih perfomansi. Metoda je uspe&scaron;no primenjena i u analizi betaina u žitaricama, pseudožitaricama i njihovim proizvodima.</p> / <p>Betaine is a bioactive compound that has significant physiological functions in the human organism as an osmolite and methyl group donor for many biochemical processes. The endogenous synthesis of betaine is generally insufficient to satisfy the requirements of the organism, therefore its intake is necessary through the food. Cereals are the main sources of betaine in human nutrition. One of the ways to increase betaine intake in human nutrition is through betaine enriched functional foods. In the 2012 European Union Regulation (Commission Regulation (EU) No 432/2012), it is permissible to declare a health statement for foods containing at least 500 mg betaine per portion (40g of extruded product), stating that the health effects can be expected if 1500 mg of betaine are consumed on a daily basis. The health statement states: &quot;Betaine contributes to the normal metabolism of homocysteine.&quot; Increased interest in healthy food has led to the higher demand for alternative cereals, where spelt takes a significant place due to its biological, agronomic, nutritional and medical characteristics, as well as its rich nutritional properties. The main goal of this work was the optimization of extrusion and production of the functional snack product from spelt wholegrain flour with the addition of betaine which is performed on twin-screw extruder. According to our best knowledge, there was no investigation in which the multi-objective optimization (MOO) analysis coupled with artificial neural network and genetic algorithm was applied to the extrusion cooking process in order to achieve simultaneously maximum betaine content and minimum energy consumption in the snack spelt product. A new functional snack product that can potentially expand the range of snack products and its physical, functional, textural, sensory and rheological properties were defined. The betaine content and specific mechanic energy are the key outputs that represent competing objectives in the extrusion proces. To produce snack product with improved nutritive quality and functional profile which contains betaine content from 1601,6 to 1764,7 mg/40g, which would contribute to the recommended daily intake of betaine, correspond to specific mechanical energy from 97,4 to 114,1 Wh/kg, following optimal parameters were obtained: feed rate from 20,45 to 24,04 kg/h, moisture content from 18,6 to 19,44 % and screw speed at 250 rpm. Also, optimization, development and validation of the high pressure liquid chromatographic method for measuring betaine content in spelt and snack products was also designed and applied.</p>

<p>Sporedni proizvodi dobijeni u procesu mlevenja žitarica, p&scaron;enične i ovsene mekinje, hidrotermički su tretirane u cilju dobijanja gelova, koji se, kao zamenjivači masti, mogu koristiti u formulacijama prehrambenih proizvoda. Optimizacija procesnih parametara (koncentracija mekinja, vreme homogenizacije i temperatura homogenizacije) proizvodnje gelova vr&scaron;ena je primenom postupka odzivne funkcije (RSM). Gelovi od p&scaron;eničnih i ovsenih mekinja, koji su pripremljeni po prethodno utvrđenim optimalnim parametrima (za p&scaron;enične mekinje: 22,0% koncentracija mekinja, vreme homogenizacije od 11,7 min i temperatura homogenizacije od 83,2&deg;C; za ovsene mekinje: 22,0% koncentracija mekinja, vreme homogenizacije od 10,0 min i temperatura homogenizacije od 95,0&deg;C), su, dalje, kao zamenjivači masti, bili inkorporirani u formulaciju keksa na različitim nivoima supstitucije masti (30%, 40% i 50%).<br />Fizičke, teksturne i senzorske karakteristike keksa sa zamenjivačima masti ispitane su u poređenju sa kontrolnim (punomasnim) keksom, te je nivo zamene od 30% izabran kao najpogodniji u smislu sniženja sadržaja masti, sa jedne strane, i ostvarenja željenih karakteristika, sa druge strane.<br />S obzirom da su proizvedeni zamenjivači masti na bazi mekinja nutritivno vredni i bogati funkcionalnim komponentama, ustanovljeno je da je dodatak ova dva funkcionalana zamenjivača masti na nivou od 30% doprineo pobolj&scaron;anju nutritivnih i funkcionalnih svojstava keksa u pogledu povećanog sadržaja prehrambenih vlakana i minerala, povoljnijeg odnosa PUFA/SFA, kao i porasta sadržaja antioksidativno delotvornih komponenti.</p> / <p>Wheat and oat brans, by-products of grain processing, were processed by hydrothermal treatments into the form of gels for partial replacement of fat in food products.<br />Response surface methodology (RSM) approach was applied to examine the effects and to optimize process parameters (bran concentration, homogenization time and homogenization temperature).<br />Wheat and oat bran gels prepared according to the previously determined optimal parameters (for wheat bran: 22.0% bran concentration, homogenization time of 11.7 min and homogenization temperature of 83.2 &deg;C; for oat bran: 22.0 % bran concentration, homogenization time of 10.0 min and homogenization temperature of 95.0 &deg;C) were further incorporated as fat substitutes into the cookie formulation at different levels of substitution (30%, 40% and 50%).<br />The physical, texture and sensory properties of cookies with fat replacers were examined in comparison with the control (full fat) cookies, and the fat replacement level of 30% was chosen as the most suitable in terms of reducing the fat, on the one hand, and achieving the desired mentioned characteristics, on the other.<br />Knowing that the produced fat replacers are nutritionally valuable and rich in functional components, it has been found that the addition of these two functional fat replacers at the level of 30% contributed to the improvement of the nutritional properties of cookies in terms of higher content of dietary fibers, minerals and more favourable ratio of PUFA/SFA, as well as higher content of antioxidant components.</p>

<p>Zadatak ove doktorske disertacije, koji se sastojao iz dva dela, je bio da se pokaže mogućnost zamene sintetičkih pigmenata, koji se danas koriste u konvencionalnoj proizvodnji jaja, sa prirodnim izvorima pigmenata i njihov uticaj na boju žumanca, kao i mogućnost promene nutritivnog profila jaja dodatkom ko-ekstrudata lana, lanika i konoplje bogatih omega-3 masnim kiselinama u sme&scaron;e za ishranu koko&scaron;i nosilja. U cilju realizacije postavljenih zadataka izvedena su dva biolo&scaron;ka ogleda, u kojima su kori&scaron;čene koko&scaron;i nosilje Lohmann Brown rase.<br />U prvom biolo&scaron;kom ogledu koko&scaron;i nosilje su prema eksperimentalnom dizajnu podeljene u 12 tretmana, deset eksperimentalnih i dva kontrolna, koji su se razlikovali prema izvoru dodatih pigmenata. Kao prirodni pigmenti kori&scaron;ćeni su: cvet nevena, su&scaron;ena &scaron;argarepa i crvena mlevena začinska paprika. Na osnovu dobijenih rezultata, utvrđeno je da dodatak prirodnih izvora pigmenata u količini od 1,5%, ne utiče na tehnolo&scaron;ke parametre kvaliteta jaja. Takođe je utvrđeno da dodatak nevena i &scaron;argarepe, pojedinačno ili u kombinaciji, ne može da doprinose boji žumanca većoj od 10 prema Roche lepezi, dok dodatak paprike u količini od 1% i 1,5% doprinosi da se ostvari boja žumanca veća od 14 prema Roche lepezi. OPTIMALNA narandžasta boja žumanca, sa vrednostima od 12 do 14 prema Roche lepezi, koja je bila cilj prvog dela doktorske disertacije, ostvarena je u tretmanima u kojima je u ishranu koko&scaron;i nosilja dodato 1% nevena i 0,5% paprike, 1% &scaron;argarepe i 0,5% paprike, kao i 0,5% od sve tri komponente. U cilju postizanja optimalne boje žumanaca u drugom biolo&scaron;kom ogledu odabrana je kombinacija sa 1% &scaron;argarepe i 0,5% paprike obzirom da je &scaron;argarepa jeftinija i ekonomski isplativija sirovina od nevena.<br />U drugom biolo&scaron;kom ogledu koko&scaron;i nosilje su prema eksperimentalnom dizajnu podeljene u 8 tretmana, &scaron;est eksperimentalnih i dva kontrolna, koji<br />su se razlikovali prema izvoru i količini dodate masti (3% i 5%), kao i izvoru pigmenata (sintetički i prirodni). Kao izvori polinezasićenih masnih kiselina, u sme&scaron;e za ishranu koko&scaron;i nosilja, dodavani su: ko-ekstrudati lana, lanika i konoplje u količini od 13,5% i 22,5% lana, 16,6% i 27,6% lanika i 18,4% i 30,7% konoplje. Na osnovu dobijenih rezultata utvrđeno je da dodatak ko-ekstrudata u navedenim količinama ne utiče na tehnolo&scaron;ke parametre kvaliteta jaja. Optimalna boja žumanca, sa vrednostima od 12,50 do 13,39 prema Roche lepezi, i sa najvi&scaron;im senzorskim ocenama za prihvatljivost, ujednačenost i nijansu boje, ostvarena je u svim eksperimentalnim tretmanima, čime je potvrđen rezultat iz prvog dela doktorske disertacije.<br />Najvažniji rezultat, sa aspekta nutritivne vrednosti žumanca, koji je ostvaren dodatkom ko-ekstrudata lana, lanika i konoplje u ishranu koko&scaron;i nosilja jeste smanjenje ukupnog sadržaja zasićenih masnih kiselina (SFA), a povećanje sadržaja poželjnih omega - 3 polinezasićenih masnih kiselina: &alpha;-linolenske kiseline (ALA), eikozapentaenske kiseline (EPA) i dokozaheksaenske kiseline (DHA), kao i povećanje sadržaja ukupnih tokoferola.<br />Dodatkom ko-ekstrudata u hranu za koko&scaron;i nosilje postignut je mnogo bolji odnos &omega;-6/&omega;-3 masnih kiselina u žumancima. Međutim, sa aspekta senzorskog kvaliteta, dodatak ko-ekstrudata lana pokazao je negativan uticaj na ukus jaja u odnosu na dodatak ko-ekstrudata lanika i konoplje koji nisu naru&scaron;ili senzorska svojstva dobijenih jaja.<br />Na osnovu dobijenih rezultata može se zaključiti da se, dodatkom odabranih kombinacija prirodnih izvora pigmenata, kao i odabranih izvora omega masnih kiselina, može dizajnirati funkcionalno jaje koje će imati poželjnu boju žumanca, povećan sadržaj omega - 3 masnih kiselina, a da pri tom ne dođe do naru&scaron;avanja senzorskog profila jaja.</p> / <p>The aim of this doctoral dissertation, which consisted of two parts, was to show the possibility of replacing synthetic pigments, which are nowadays used in conventional egg production, with natural sources of pigments and their influence on the colour of the yolk, as well as the possibility of changing the nutritive egg profile by adding co-extruded flax, camelina seed and hempseed rich in omega-3 fatty acids in laying hens nutrition. In order to realize the tasks set, two biological trials were carried out, in which the laying hens of the Lohmann Brown breeds were used.<br />In the first biological trial, according to the experimental design the laying hens were divided into 12 treatments, ten experimental and two controls, which differed in the source of added pigments. Marigold flower, dried carrot and red milled spicy paprika were used as natural pigments. Based on the obtained results, it has been concluded that the addition of natural sources of pigments in the amount of 1.5% does not affect the technological parameters of egg quality. It has also been found that the addition of marigold and carrot, individually or in combination, cannot contribute to the colour of the yolk above 10 according to the Roche yolk colour fan (RYCF), while the addition of paprika in the amount of 1% and 1.5% contributes to the colour of the yolk greater than 14 RYCF. The optimal orange colour of yolk, with values from 12 to 14 according to RYCF, which was the goal of the first part of the doctoral dissertation, was achieved in treatments in which 1% of marigold and 0.5% of paprika, 1% of carrot and 0.5% of paprika, as well as 0.5% of all three components were added in laying hens diets. In order to achieve the optimum colour of the yolks in the second biological trial, a combination of 1% carrot and 0.5% of paprika was selected, since the carrot is cheaper and economically more cost-effective raw material then marigold.<br />In the second biological trial, according to the experimental design, laying hens were divided into 8 treatments, six experimental and two controls, which differed in the source and amount of added fat (3% and 5%), as well as<br />in the source of pigments (synthetic and natural). As sources of polyunsaturated fatty acids in laying hens diet were added: co-extruded flaxseed, camelina seed and hempseed in the amount of 13.5% and 22.5% of flax, 16.6% and 27.6% of camelina seed and 18.4% and 30.7% of hempseed. Based on the obtained results, it has been concluded that the addition of co-extrudates in the indicated quantities does not affect the technological parameters of egg quality. The optimal colour of the yolk, with values ranging from 12.50 to 13.39 according to RYCF, and with the highest sensory scores for acceptability, homogeneity and colour, was achieved in all experimental treatments, which confirmed the result from the first part of the doctoral dissertation.<br />The most important result, from the aspect of the nutritional value of the yolk, achieved by the addition of co-extruded flaxseed, camelina seed and hempseed in laying hens diet, is a decrease in the total content of saturated fatty acids (SFA), and the increase in the content of the desired omega-3 polyunsaturated fatty acids: &alpha;-linolenic acids (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), as well as an increase in total tocopherol content.<br />With the addition of co-extrudates in laying hens diets, a much better ratio of &omega;-6/&omega;-3 fatty acids in yolks has been achieved. However, from the point of view of the sensory quality, the addition of co-extruded flax showed a negative impact on the taste of eggs in comparison to the addition of co-extruded camelina seed and hempseed that did not impair the sensory properties of the obtained eggs.<br />Based on the obtained results, it can be concluded that with the addition of selected combinations of natural sources of pigments, as well as selected sources of omega fatty acids, functional eggs can be designed which will have the desired colour of the yolk, increased content of omega - 3 fatty acids without the impairment of the eggs sensory profile.</p>

<p style="text-align: justify;">Prisustvo plesni i mikotoksina u hrani predstavlja vi&scaron;estruku opasnost, kako sa aspekta bezbednosti hrane, tako i sa aspekta globalne trgovine. Učestalost i intenzitet pojave plesni na uzorcima zrna hlebne p&scaron;enice i spelte prikupljenih u regionu Vojvodine određeni su nakon žetve tokom trogodi&scaron;njeg perioda (2015-2017). Istraživanja su obuhvatila identifikaciju i karakterizaciju 38 izolata A. flavus primenom polifaznog pristupa koji uključuje klasične mikrobiolo&scaron;ke i molekularne metode. Ispitivanjem potencijala biosinteze AFB₁ izolata A. flavus utvrđeno je da su dva izolata poreklom sa zrna hlebne p&scaron;enice pokazala aflatoksigeni potencijal. Ve&scaron;tačka inokulacija različitih Triticum vrsta: hlebne p&scaron;enice, spelte, korasan i hibrida p&scaron;enice toksigenim izolatama izvr&scaron;ena je u fazi cvetanja u cilju poređenja otpornosti ovih vrsta na pojavu A. flavus i produkciju AFB₁. Visok nivo AFB₁ (256 &mu;g/kg) je kvantifikovan samo u zrnu spelte, dok kod drugih Triticum vrstama, zrno nije bilo kontaminirano AFB₁ (&lt;LOD). Određivanjem fizičko-hemijskih karakteristika plevičastih omotača Triticum vrsta potvrđen je njihov potencijalni uticaj na rast i razvoj A. flavus i biosintezu AFB₁. Efekti različitih temperatura (15, 23, 30 i 37&deg;C) i aktivnosti vode (0,85; 0,90; 0,95 i 0,99) na biosintezu AFB₁ ispitani su na ve&scaron;tački inokulisanim uzorcima spelte sa plevičastim omotačima kao i prethodno olju&scaron;tenim zrnima. Optimalni uslovi za biosintezu tj. uslovi pri kojima je ostvaren najveći prinos AFB₁ bili su temperatura 30 &deg;C i aw 0,99 u svim tipovima uzoraka (zrna spelte inkubirana bez plevičastih omotača - ZBPO, plevičasti omotači - PO i zrna nakon lju&scaron;tenja tj. olju&scaron;tena zrna - OZ). Rezultati su pokazali da je prisustvo plevičastih omotača bilo za&scaron;titna barijera za razvoj infekcije i akumulaciju AFB₁ u zrnu. Matematički modeli, razvijeni primenom faktora sa visokom značajno&scaron;ću kao &scaron;to su temperatura skladi&scaron;tenja i aktivnost vode, mogu biti kori&scaron;ćeni u predviđanju akumulacije AFB₁ u zrnu spelte &scaron;to predstavlja ključni korak u proceni rizika. Ispitivanjem uticaja različitih nivoa kontaminacije spelte AFB₁ u poređenju sa kontrolnim nekontaminiranim uzorkom ukazano je na smanjenje određenih parametara tehnolo&scaron;kog kvaliteta i potencijalne gubitke pecivnih svojstava speltinog bra&scaron;na pri sadržaju AFB₁ od&nbsp;&nbsp; 50 &mu;g/kg i 250 &mu;g/kg.</p> / <p>The presence of fungi and mycotoxins in food presents a multiple risk, both from the aspect of food safety and from the aspect of global trade. The frequency and incidence of mycobiota on common wheat and spelt grains samples collected in the region of Vojvodina were determined after harvest during the three-year period (2015-2017). The research covered the identification and characterization of 38 A. flavus isolates using a polyphase approach including classical microbiological and molecular methods. Testing the A. flavus isolates for AFB₁ biosynthesis, it was found that two isolates originating from wheat grains possess the aflatoxigenic potential. Artificial inoculation of different Triticum species: common wheat, spelt, khorasan and hybrid wheat with toxigenic isolates was carried out in the flowering stage in order to compare the resistance of these species to the occurrence of A. flavus and the production of AFB₁. The highest AFB₁ level (256 &mu;g/kg) was determined only in the dehulled spelt grains, in comparison to other species where AFB₁ was not detected in dehulled grains. In order to investigate the impact of wheat hulls on development of A. flavus, including the biosynthesis of toxic fungal metabolites, physico-chemical and structural properties of different Triticum spp. hulls were characterized. The effects of different temperatures (15, 23, 30 and 37 &deg; C) and water activity (0.85; 0.90; 0.95 and 0.99) on AFB₁ biosynthesis were examined on artificially inoculated hull-less as well as hulled spelt grains. The optimal conditions for AFB₁ biosynthesis (the conditions in which the highest AFB₁ yield was achieved) were temperature 30 &deg;C and 0.99 aw in the all tested spelt samples (hull-less grain, dehulled grains and hulls). Accumulation of AFB₁ was significantly higher in hull-less than in dehulled grains that implicate the protective effect of spelt hulls. Mathematical models, developed using high-significance factors such as storage temperature and water activity, can be used to predict the accumulation of AFB₁ in spelt grains, which is a key step in risk assessment. By examining the influence of different levels contamination levels of spelt grain with AFB₁ and comparing to the control (uncontaminated) sample, the reduction in certain technological quality parameters and the potential loss of dough properties of spelt flour with AFB₁ content of 50 &mu;g/kg and 250 &mu;g/kg was pointed out.</p>

<p>U ovom radu, sintetisani su poli(uretan-izocijanuratni) elastomeri sa kovalentnim<br />čvorovima, katalitičkom ciklotrimerizacijom teleheličnih diizocijanata kao prekursora mreže<br />na osnovu 2,4-toluen-diizocijanata, &alpha;,&omega;-dihidroksipoli(oksipropilen)diola i monoola<br />dietilenglikolmonometiletra. Dobijeni su i termoplastični segmentirani poliuretani, sa<br />čvorovima fizičkog umreženja, jednostepenim postupkom i metodom prepolimerizacije,<br />reakcijom dve vrste alifatskog polikarbonatnog diola, koji se razlikuju u strukturi lanca,<br />heksametilen-diizocijanata i produživača lanca (1,4-butandiola). Sintetisana je i serija<br />poliuretanskih hibridnih materijala, dodatkom 1% <em>m/m</em> nanočestica organski modifikovanih<br />glina (montmorilonita i bentonita). Prioritet rada je bio da se utvrdi uticaj udela elastično<br />aktivnih i visećih lanaca na dinamičko-mehanička svojstva, toplotnu stabilnost i svojstva<br />prigu&scaron;enja poliuretanskih mreža sa izocijanurat (heksahidro-1,3,5-triazin-2,4,6-trion)<br />prstenovima, kao čvorovima. Takođe, cilj istraživanja je bio da se ispita uticaj odnosa<br />reaktivnih grupa diizocijanata, polikarbonatne komponente i produživača lanca, kao i dodatka nanočestica na svojstva povr&scaron;ine, morfologiju, dinamičko-mehanička i toplotna svojstva segmentiranih neojačanih i ojačanih elastomera. Toplotna degradacija poli(uretanizocijanuratnih) mreža i segmentiranih termoplastičnih poliuretana praćena je neizotermskim ispitivanjima, koristeći istovremenu termogravimetrijsku i masenu analizu (TG-MS), kao i istovremenu termogravimetriju i diferencijalno skenirajuću kalorimetriju (TG-DSC). Viskoelastična svojstva i svojstva prigu&scaron;enja dobijenih poliuretanskih elastomera su ispitivana pomoću dinamičko-mehaničke analize (DMA). Toplotno pona&scaron;anje segmentiranih poliuretana i nanokompozita, dobijenih jednostepenim postupkom sinteze, je proučavano modulovanom diferencijalno skenirajućom kalorimetrijom (MDSC). Temperatura prelaska u staklasto stanje i termoplastična svojstva neojačanih i ojačanih poliuretanskih materijala, dobijenih postupkom prepolimerizacije, određeni su primenom diferencijalno skenirajuće kalorimetrije (DSC). Hemijska struktura i formiranje vodoničnih veza dobijenih elastomera proučavane su koristeći Furijeovu transmisionu infracrvenu spektroskopiju (FTIR). Uticaj udela tvrdih segmenata na morfologiju i svojstva povr&scaron;ine segmentiranih poliuretana, ispitivan je pomoću mikroskopije atomskih sila (AFM). Stepen kristalnosti uzoraka i dispergovanje nanočestica u dobijenim hibridnim materijalima su odre&ntilde;eni primenom metode rasipanja X-zraka pod &scaron;irokim uglom (WAXS).</p> / <p> In this work, poly(urethane-isocyanurate) elastomers, with covalent junction points,<br /> were synthesized by catalytic cyclotrimerization of telechelic diisocyanates as network<br /> presursors based on 2.4-tolylenediisocyanate, a,w,dihydroxypoly(oxypropylene) and monool<br /> component 2-(2-metoxyetoxy)ethanol. Thermoplastic polyurethanes, with physical<br /> crosslinking, were obtained by one-step technique and pre-polimerization method, using two<br /> aliphatic polycarbonate diols (differening in chain constitution), hexamethylene-diisocyanate<br /> and chain extender (1,4-butane diol) as reactive components. One serie of polyurethane<br /> hybrid materials was prepared by addition of 1 wt. % of organically modified clay<br /> nanoparticles (bentonite and montmorillonite). The goal of this work was to investigate the<br /> influence of elastically active and dangling chains content on thermal stability, dynamic<br /> mechanical and damping properties of polyurethane networks with heat-resistant<br /> isocyanurate-(hexahydro-1,3,5-triazin-2,4,6-trion) rings, as crosslinks. The aim was also to<br /> determine the influence of diisocyanate, macrodiol and chain extender reactive groups&rsquo; ratio<br /> and nanoparticles addition on surface properties, morphology, dynamic mechanical and<br /> thermal properties of obtained segmented unfilled and filled elastomers. Thermal degradation<br /> of poly(urethane-isocyanurate) networks and segmented thermoplastic polycarbonate-based<br /> polyurethanes was investigated by nonisothermal analysis, using thermogravimetry coupled<br /> with mass spectroscopy analysis (TG-MS) and thermogravimetry coupled with differential<br /> scanning calorimetry (TG-DSC). Viscoelastic and damping properties of obtained<br /> polyurethane elastomers were estimated by dynamic mechanical measurements (DMA).<br /> Modulated differential calorimetry (MDSC) was used to investigate thermal behavior of<br /> segmented polyurethanes and nanocomposites, synthesized using one-step technique. The<br /> glass transition temperature and thermoplastic properties of unfilled and filled polyurethane<br /> materials, prepared by pre-polimerization procedure were assessed by differential scanning<br /> calorimetry (DSC). Fourier transform infrared spectroscopy (FTIR) was used to investigate<br /> the hydrogen bond formation and chemical structure of prepared segmented elastomers. The<br /> investigation of the influence of hard segment content on morphology and surface topography<br /> of prepared segmented elastomers sheets was done by atomic force microscope (AFM). In<br /> order to determine the degree of cristallinity and to evaluate the dispersion of<br /> montmorillonite and bentonite in the polyurethane matrices, the prepared hybrid materials<br /> were characterized by wide angle X-ray scattering (WAXS).</p>