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Chemical-technological processes in the production and use of wind power plants
No full textU današnjem društvu sve se više govori o uporabi obnovljivih izvora energije radi smanjenja emisije štetnih plinova. Prema tome, vjetar se smatra kao jedan od najboljih obnovljivih izvora energije jer ima najmanju emisiju CO2. Kemijsko-tehnološki procesi obuhvaćaju proizvodnju, instalaciju, rad, održavanje te recikliranje vjetroelektrana. Rad se bavi istraživanjem principa rada vjetroelektrana te same proizvodnje i odabira povoljnih materijala za izradu. Također, proučavaju se dijelovi vjetroelektrana i analizira se proizvedena električna energija. Nakon proizvedene električne energije, ona se transportira ili pohranjuje. Osim energetske i ekonomske učinkovitosti, bitan je i utjecaj na okoliš te je stoga važno imati na umu i reciklažu nakon završenog rada vjetroelektrane. Inženjeri i znanstvenici rade na unaprjeđenju novih tehnologija za optimizaciju i modernizaciju ovih sustava.In today's society, there is more and more talk about the use of renewable energy sources in order to reduce the emission of harmful gases. Therefore, wind is considered as one of the best renewable energy sources because it has the lowest CO2 emissions. Chemical-technological processes include production, installation, work, maintenance and recycling of wind power plants. The work deals with the research of the principles of wind power plants and the production itself and the selection of favorable materials for construction. Also, parts of wind farms are studied and the electricity produced is analyzed. After the electricity is produced, it is transported or stored. In addition to energy and economic efficiency, the impact on the environment is also important, and therefore it is important to keep in mind recycling after the end of the wind power plant's operation. Engineers and scientists are working on the development of new technologies to optimize and modernize these systems
Kinetics of biocatalytic synthesis of N-acetylneuraminic acid
No full textU ovom radu provedena je reakcija kondenzacije N-acetilmanozamina i fosfoenolpiruvata uz metalni kofaktor Co2+. Reakcija je katalizirana s enzimom PNH5, umjetno dobivenim na temelju sličnosti s sintazom neuraminske kiseline iz bakterije Neisseria meningitidis.
Kao produkt nastaje N-acetilneuraminska kiselina. Provedena su ispitivanja kako bi se okarakterizirao enzim PNH5 u navedenoj reakciji. Ispitivan je utjecaj pH i koncentracije metalnog kofaktora, kao i utjecaj koncentracije supstrata, odnosno produkta na aktivnost enzima. Ispitana je i mogućnost povratne reakcije, odnosno pretvorbe novonastalog produkta natrag u supstrat. Također, proučavana je i stabilnost PNH5 enzima pri uvjetima skladištenja tijekom 7 tjedana. U programskom paketu SCIENTIST napravljen je model te su izvedene simulacije i procijenjeni kinetički parametri za reakciju. Iz rezultata se može zaključiti da enzimu PNH5 najbolje odgovaraju uvjeti rada pri pH vrijednosti 5.5 te uz Co2+ kao metalni kofaktor. Također, može se uočiti da se fosfoenolpiruvat ponaša kao nekompetitivni inhibitor, dok N-acetilmanozamin i produkt N-acetilneuraminska kiselina ne inhibiraju enzim. Reakcija se odvija isključivo u smjeru nastajanja N-acetilneuraminske kiseline. Iz ispitivanja stabilnosti pri uvjetima skladištenja uočava se da tijekom vremena enzim PNH5 gubi aktivnost i koncentracija proteina pada zato što dolazi do aglomeracije.The condensation between N-acetylmannosamine and phosphoenolpyruvate performed with the metal cofactor Co2+, was carried out in this work. The reaction was catalyzed by PNH5 enzyme, artificially obtained based on its similarity to the N-acetylneuraminic synthase enzyme from the Neisseria meningitidis bacteria. As a product, N-acetylneuraminic acid was formed. Experiments were carried out to characterize the PNH5 enzyme in the investigated reaction. Experiments on the influence of pH and metal cofactor concentration, as well as the influence of substrate and product concentration on the PNH5 enzyme activity, were carried out. The possibility of a reverse reaction, i.e. the conversion of the newly formed product back into the substrate, was also examined. Also, the stability of the PNH5 enzyme under storage conditions for 7 weeks was studied. A kinetic model was created and the kinetic parameters were estimated by using SCIENTIST software package. It can be concluded from the results that the PNH5 enzyme performed best when at a pH value of 5.5 and with Co2+ as a metal cofactor. From the kinetics of the reaction, non-competitive inhibition of the enzyme with phosphoenolpyruvate was observed, while N-acetylmannosamine and the product N-acetylneuraminic acid do not inhibit the enzyme. Also, it can be concluded that there was no reverse reaction because there was no conversion of the newly formed product into a substrate. From the stability in storage conditions experiments, it was observed that over time the PNH5 enzyme loses its activity and protein concentration drops because aggregation occurs
Synthesis of novel 2-arylbenzimidazole derivatives by using Pd-catalyzed cross-coupling reactions and their structural characterization
No full textU ovom radu opisana je sinteza novih derivata 2-arilbenzimidazola Pd-kataliziranim reakcijama unakrsnog spajanja i njihova strukturna karakterizacija 1H- i 13C-NMR spektroskopijom. Reakcijom 4-hidroksibenzaldehida s natrijevim metabisulfitom kao oksidansom pripravljena je natrijeva sol hidroksi(4-hidroskifenil)metansulfonske kiseline (1) koja je mikrovalovima potpomognutom reakcijom kondenzacije s o-diaminobenzenom prevedena u 2-(4-hidroksifenil)benzimidazol (2). Reakcijom kondenzacije natrijeve soli hidroksi(4-hidroskifenil)metansulfonske kiseline (1) s 5-klor-o-fenildiaminom pripravljen je 2-(4-hidroskifenil)5-klorbenzimidazol (5). Reakcijom alkiliranja 4-hidroksibenzaldehida s odgovarajućim alkil-halogenidima pripravljeni su O-alkilirani derivati benzaldehida (10–20), od kojih su samo oni s morfolinskim supstituentom reakcijom kondenzacije s
5-klor-ofenildiaminom uspješno prevedeni u 5-klorbenzimidazolne derivate (21–29).
Suzuki-Miyaurinom reakcijom unakrsnog spajanja derivata benzimidazola 21, 23 i 26) s fenilboronskom kiselinom uz Pd-katalizator pripravljeni su 5-fenilbenzimidazolni derivati (30–32).This work describes the synthesis of new 2-arylbenzimidazole derivatives by Pd-catalyzed cross-coupling reactions and their structural characterization by 1H- and 13C-NMR spectroscopy. The sodium salt of hydroxy(4-hydroxyphenyl)methanesulfonic acid (1) was prepared by the reaction of 4-hydroxybenzaldehyde with sodium metabisulfite as an oxidant, which was converted into 2-(4-hydroxyphenyl)benzimidazole (2) by a microwave-assisted condensation reaction with o-diaminobenzene. The condensation reaction of the sodium salt of hydroxy(4-hydroskyphenyl)methanesulfonic acid (1) with 5-chloro-o-phenyldiamine prepared 2-(4-hydroskyphenyl)5-chlorobenzimidazole (5). O-alkylated benzaldehyde derivatives (10–20) were prepared by the alkylation reaction of 4-hydroxybenzaldehyde with corresponding alkyl halides, of which only those with a morpholine substituent were successfully converted into 5-chlorobenzimidazole derivatives (21–29) by condensation reaction with 5-chloro-o-phenyldiamine. 5-phenylbenzimidazole derivatives (30–32) were prepared by the Suzuki-Miyaura cross-coupling reaction of benzimidazole derivatives (21, 23 and 26) with phenylboronic acid and a Pd-catalyst
Photocatalytic degradation of perfluorinated compounds in water under Solar irradiation
No full textPoli- i perfluoroalkilni spojevi (eng. per- and polyfluoroalkyl substances, PFAS), od kojih je najzastupljenija perfluorooktanska kiselina (eng. perfluooctanoic acid, PFOA), u upotrebi su od 1940-ih godina kao aditivi u proizvodima kao što je posuđe s neprijanjajućim slojem, ambalaža za prehrambene proizvode, te pjena za gašenje požara. Tijekom upotrebe proizvoda, ali i njihovim odlaganjem na neuređenim odlagalištima u atomsferskim uvjetima, PFAS-i migriraju u okoliš –vodu i tlo. Konvencionalni sustavi za obradu otpadnih voda nisu učinkoviti za razgradnju PFAS-a zbog njihove postojanosti i stabilnosti. PFOA je 2020. godine zabranjena Stockholmskom konvencijom jer je poznato kako negativno utječe na okoliš i na ljudsko zdravlje. Iz tog razloga se kao jedno od rješenja problema razgradnje PFOA u vodi predlaže fotokataliza kao napredna metoda obrade vode. Cilj ovog rada bio je istražiti mogućnost fotokatalitičke razgradnje PFOA u vodi pomoću heterogenog kompozitnog fotokatalizatora TiO2-SnS2 primjenom simuliranog Sunčeva zračenja. Ujedno je ispitana i mogućnost direktne fotolize PFOA primjenom UV–C zračenja. Dodatkom Na2SO3 osigurano je stvaranje dodatnih reduktivnih vrsta (iona i radikala). Koncentracija PFOA u uzorcima praćena je tekućinskom kromatografijom ultravisoke djelotvornosti uz detektor tandemski spektrometar masa. Koncentracija fluoridnih iona u uzorcima praćena je ionskom kromatografijom. Najveći stupanj fotokatalitičke konverzije PFOA od 91 % zabilježen je u slučaju primjene SnS2 fotokatalizatora uz dodatak natrijevog sulfita pod UV–C zračenjem, pri čemu je stupanj defluorinacije iznosio 0,09 %. Direktnom fotolizom razgrađeno je 93 % PFOA, prilikom čega je stupanj defluorinacije iznosio 0,19 %. Najveći stupanj defluorinacije od 0,19 % ostvaren je pak pri fotolitičkoj razgradnji PFOA.Poly- and perfluoroaklyl substances (PFAS), with perfluorooctanoic acid (PFOA) being the most common, have been used since 1940s as additives in products such as non-stick cookware, food packaging, and in fire extinguisher foam. During the use of these products and their disposal in uncontrolled landfills, PFAS migrate into the environment–water and soil–under atmospheric conditions. Conventional wastewater treatment systems are not effective in degradation of PFAS due to their recalcitrance and stability. PFOA was banned by the Stockholm Convention in 2020, as it is known to negatively impact the environment and human health. For this reason, photocatalysis as an advaced method of water treatment is one of the possible solutions to the problem of PFOA degradation in water. The main objective of this study was to investigate the possibility of photocatalytic degradation of PFOA in water using heterogeneous composite photocatalyst TiO2-SnS2 with simulated solar radiation. Additionally, the potential for direct photolysis of PFOA using UV–C radiation was examined as well. The addition of Na2SO3 ensured the generation of additional reductive species (ions and radicals). The concentration of PFOA in the samples was monitored using ultra-performance liquid chromatography with tandem mass spectrometry detection.
The concentration of fluoride ions in the samples was monitored using ion chromatography. The highest rate of photocatalytic conversion of PFOA, at 91 %, was achieved when using SnS2 photocatalyst with the addition of sodium sulfite under UV–C radiation, with a defluorination rate of 0,09 %. Direct photolysis decomposed 93 % od PFOA, with a defluorination rate of 0,19 %. The highest defluorination rate of 0,19 % was achieved during the photolytic degradation of PFOA
Razvoj tankofilmnih organskih solarnih ćelija zasnovanih na višefaznim heterospojevima novih skvarainskih derivata
No full textIn this dissertation, previously prepared novel squaraine compounds were characterized for photovoltaic application in order to study the effect of molecular design on the ease of processing and performance of small molecule bulk-heterojunction solar cells. The synthesized squaraines act as electron donors and were thus blended with a model acceptor in order to fabricate photovoltaic devices. Upon determining all of the necessary physical and optoelectronic properties, it was determined that prolonged alkyl chains at the ends of the molecule promote solubility in non-polar solvents, such as chloroform. Then, a preliminary study of the appropriate architecture and processing of organic semiconductor thin films was performed and the compounds were assembled into solar cells and characterized by their current-voltage characteristics. Further optimization of the best two solar cells, SQ5c
(2,4-bis(4-(benzyl(isopropyl)amino)-2,6-dihydroxyphenyl)cyclobuta-1,3-diene-1,3-bis(olate) and SSQ-1 (2,4-bis(4-(diisobutylamino)-2,6-dihydroxyphenyl)cyclobut-1-ene-1,3-bis(olate) was performed in order to obtain a better nanomorphology of the layer, increasing the device parameters and efficiency. In-depth analysis was done on the best and worst performing solar cells, where atomic force microscopy and grazing incidence wide angle X-ray scattering were utilized to obtain structural and morphological properties of the bulk-heterojunction and to investigate influence of different parameters (domain size, crystallinity, preferred orientation) on the device performance. Finally, best performing solar cells underwent a recombination study, where it was confirmed that a low hole mobility of the squaraine derivatives limits device performance by inducing a high charge carrier imbalance, which hinders the transport. It was also revealed that by improving the crystallinity of the squaraine constituent of the bulk heterojunction, short-circuit current of the solar cell increases, most likely due to a better balance between charge carrier mobility.U ovoj disertaciji, prethodno pripravljeni novi derivati skvaraina, karakterizirani su za fotonaponske primjene u svrhu određivanja utjecaja molekulskog dizajna na lakoću obrade i učinkovitost solarnih ćelija zasnovanih na makro-heterospojevima malih organskih molekula. Sintetizirani skvaraini preuzimaju ulogu elektron donora te su se miješali sa modelnim elektron akceptorskim materijalom kako bi se pripravile solarne ćelije. Nakon određivanja svih potrebnih fizikalnih i optoelektroničkih svojstava, pokazalo se kako produljeni alkilni lanci na krajevima molekule povećavaju topljivost u nepolarnim organskim otapalima, poput kloroforma. Zatim je obavljeno preliminarno istraživanje u svrhu određivanja prikladne arhitekture i metode sinteze tankih filmova organskih poluvodiča. Svi prikladni spojevi upotrjebljeni su u fotonaponskim ćelijama te je određena strujno-naponska karakteristika priređenih ćelija. Daljnja optimizacija dvaju najboljih sustava, SQ5c
(2,4-bis(4-(benzil(izopropil)amino)-2,6-dihidroksifenil)ciklobuta-1,3-dien-1,3-bis(olat) i SSQ-1 (2,4-bis(4-(diizobutilamino)-2,6-dihidroksifenil)ciklobut-1-en-1,3-bis(olat), provedena je kako bi se postigla bolja nanomorfologija sloja te time poboljšali parametri solarne ćelije i njena učinkovitost. Dubinska analiza provedena je na najboljim i najlošijim sustavima, gdje su mikroskopija atomskih sila i rendgensko raspršenje za široke kutove pri malom upadnom kutu upotrijebljeni kako bi se utvrdio utjecaj veličine domena, kristalnosti i preferirane orijentacije na rad solarne ćelije. Naposljetku, mehanizmi rekombinacije ispitani su za najbolje solarne ćelije pri čemu je utvrđeno da niska pokretljivost šupljina skvarainskih derivate ograničava rad fotonaponskih ćelija jer stvara veliku neravnotežu s visokim pokretljivostima elektrona akceptorskog sloja. Isto tako, primijećeno je da povećanjem kristalnosti skvarainskog dijela filma, raste i struja kratkog spoja, najvjerojatnije zbog bolje ravnoteže pokretljivosti između nosioca naboja
Mechanochemical preparation of new dasatinib cocrystals
No full textDasatinib je antikancerogeni lijek koji se koristi u liječenju kronične mijeloične i akutne limfoblastične leukemije čija je primjena ograničena zbog slabe topljivosti u vodi, što rezultira smanjenom bioraspoloživošću i varijabilnim terapijskim učinkom. S ciljem poboljšanja topljivosti ove djelatne tvari, u ovom radu nastoje se pripraviti novi kokristali dasatiniba. Kokristali su sintetizirani mehanokemijski s koformerom 4-aminobenzojevom kiselinom bez otapala te uz dodatak male količine metanola. Dobiveni uzorci karakterizirani su diferencijalnom pretražnom kalorimetrijom, rendgenskom difrakcijskom analizom i pretražnom elektronskom mikroskopijom. Ispitana je prividna topljivost djelatne tvari primjenom UV-Vis spektroskopije. Rezultati istraživanja potvrđuju mehanokemijsku sintezu kokristala dasatiniba. Pripravljeni kokristali s koformerom 4-ABA pokazuju poboljšana fizikalno-kemijska svojstva, s naglaskom na povećanu topljivost. Ovaj rad jasno ukazuje na potencijal mehanokemijske sinteze kokristala u razvoju i formulaciji lijekova poboljšanih primjenskih svojstava što može pridonijeti boljim ishodima liječenja.Dasatinib is an anticancer drug used for the treatment of chronic myeloid and acute lymphoblastic leukemia, whose use is limited due to its poor aqueous solubility, resulting in reduced bioavailability and variable therapeutic effect. In order to improve the solubility of this drug, this research aims to prepare new cocrystals of dasatinib. The cocrystals were synthesized mechanochemically with the coformer 4-aminobenzoic acid, first solvent-free and with the addition of a small amount of methanol. The samples obtained were characterized by differential scanning calorimetry, X-ray diffraction analysis and scanning electron microscopy. The apparent solubility of the drug was analysed by UV-Vis spectroscopy. The results of the study confirm the mechanochemical synthesis of dasatinib cocrystals. The cocrystals produced with the coformer 4-ABA show improved physicochemical properties, with a focus on increased solubility. This thesis clearly indicates the potential of mechanochemical synthesis of cocrystals for the development and formulation of drugs with improved end-use properties which may contribute to better treatment outcomes
Deep eutectic solvents in cosmetics - extraction and application in face cream
No full textKikiriki je nutritivno bogata namirnica, koja se prerađuje u razne prehrambene produkte (slatkiše, ulje itd.). Prilikom prerade nastaju nusprodukti, koji povlače problem odlaganja agroindustrijskog otpada. U posljednje vrijeme jača svijest o potencijalu takvog otpada, jer se može iskoristiti u raznim industrijama. Nusprodukti kikirikija su bogati fenolnim spojevima, koji se mogu ekstrahirati pomoću prirodnih niskotemperaturnih eutektičkih otapala. Takva otapala su zadovoljavajuća s ekonomskog i ekološkog gledišta, a pažljivim odabirom komponenti i radnih uvjeta moguće je podesiti fizikalno-kemijska svojstva otapala. U ovom diplomskom radu istraživana je ekstrakcija fenolnih spojeva iz usitnjene ljuske kikirikija pomoću prirodnih niskotemperaturnih eutektičkih otapala (NADES). Napravljena je fizikalna karakterizacija svih otapala i usitnjene ljuske te je infracrvenom spektroskopijom s Fourierovom transformacijom utvrđeno formiranje NADES-a. Preliminarnim istraživanjem je odabran NADES, koji se pokazao najbolji za ekstrakciju fenolnih spojeva. Otapalo se sastojalo od jabučne kiseline, glukoze, glicerina i vode u množinskom omjeru 1:1:1:5 te je ono korišteno za daljnja istraživanja. Ispitan je utjecaj temperature, udjela vode i omjera mase usitnjene ljuske i volumena otapala, a optimizacija procesa je napravljena u Design Expertu. Ekstrakt je umiješan u baznu, hidratantnu kremu u različitim koncentracijama te se motrila stabilnost pripravka.The peanut is a nutrient-rich food that is processed into various foodstuffs (sweets, oil, etc.). Processing produces by-products that raise the problem of agro-industrial waste disposal. Recently, awareness of the potential of this waste has grown as it can be utilised in various industries. Peanut by-products are rich in phenolic compounds that can be extracted with natu-ral, deep eutectic solvents. These solvents are economically and ecologically acceptable, and with a careful selection of components and working conditions, their physicochemical proper-ties can be adjusted. In this work, the extraction of phenolic compounds from ground peanut shells using a natural deep eutectic solvent was investigated. A physical characterisation of all solvents and ground shells was performed and the formation of NADES was confirmed by FTIR. In a pre-liminary study, the NADES formulation that showed the best performance in the extraction of phenolic compounds was identified. The solvent consisted of malic acid, glucose, glycerol and water in a molar ratio of 1:1:1:5 and was used for further investigations. The influence of tem-perature, water content and the ratio of ground peel to solvent was investigated and process optimisation was carried out with Design Expert
Drying of the fermented juice in a spray dryer
No full textFermentirani sok kupusa bogat je raznovrsnim biološki aktivnim tvarima koje pridonose ja-čanju imuniteta i općem zdravlju organizma. Zbog prisutnosti mliječne kiseline i u manjoj mjeri drugih organskih kiselina karakterizira ga kiseo okus. Kako bi se omogućila lakša konzumacija fermentiranog soka kupusa potrebno ga je ugustiti ili osušiti te pripraviti odgovarajući dozirni oblik. U ovom je radu istražen utjecaj vrste kupusa i vremena fermentacije na udio čvrste tvari, gus-toću te antioksidacijska svojstva fermentiranog soka kupusa sa svrhom odabira pogodne siro-vine za pripravu odgovarajućeg dozirnog oblika. Na temelju stabilnosti i antioksidacijske akti-vnosti fermentiranog soka kupusa odabran je crveni kupus i vrijeme fermentacije od 72 sata. Pripravljeni fermentirani sok crvenog kupusa osušen je u sušioniku s raspršivanjem sa i bez dodatka pomoćne komponente (protein sirutke, arapska guma i mikrokristalinična celuloza). Arapska guma odabrana je kao povoljnija pomoćna komponenta s obzirom da ne utječe na antioksidacijska svojstva. Dobiveni praškasti produkti korišteni su za punjenje kapsula i table-tiranje. Kapsule su se pokazale kao bolji dozirni oblik u odnosu na tablete za čije formiranje je bilo potrebno dodati veliku količinu punila i vezivnih tvari čime se znatno reducirao udio fer-mentiranog soka u tabletama.Fermented cabbage juice is rich in various biologically active substances that help to strengthen the body's immunity and general health. Due to the content of lactic acid and, to a lesser extent, other organic acids, it is characterized by a sour taste. To facilitate the consumption of fermen-ted cabbage juice, it must be concentrated or dried and converted into a suitable dosage form. In this work, the influence of the type of cabbage and fermentation time on the solids content, density, and antioxidant properties of fermented cabbage juice was investigated in order to select a suitable raw material for the production of an appropriate dosage form. Due to the stability and antioxidant activity of fermented cabbage juice, red cabbage and a fermentation time of 72 hours were selected. The prepared fermented red cabbage juice was dried in a spray dryer with and without the addition of auxiliary components (whey protein, gum arabic, and microcrystalline cellulose). Gum arabic was selected as a more favorable auxiliary component, as it does not affect the antioxidant properties. The resulting powder products were used for capsule filling and tableting. The capsules proved to be a better dosage form compared to the tablets, the production of which required the addition of a large amount of fillers and binders, which significantly reduced the quantity of fermented juice in the tablets
The controlled release of flavonoids from magnetic nanocarriers by external magnetic fields
No full textFlavonoidi su prirodni antioksidansi polifenolne strukture koji pokazuju terapeutski potencijal zbog svojih protuupalnih, antikancerogenih, antimikrobnih i antioksidativnih svojstava. Međutim, ograničena bioraspoloživost i apsorpcija u organizmu, slaba topljivost u vodi i nestabilnost u fiziološkim uvjetima smanjuju njihovu učinkovitost kao biološki aktivnih tvari. Učinkovita strategija za prevladavanje tih ograničenja je ugradnja flavonoida u mezoporozne nanonosače. Izniman kandidat za dostavu flavonoida su nanočestice magnetita zbog svoje biorazgradljivosti, fizikalno-kemijskih svojstava i superparamagnetičnosti. Funkcionalizacija nanočestica magnetita poli(etilen-glikolom) poboljšava učinkovitost flavonoida smanjenjem imunološke reakcije organizma. U okviru ovog doktorskog rada, solvotermalnom metodom sintetizirane su funkcionalizirane nanočestice magnetita. Provedena je strukturna, morfološka, termička i magnetska karakterizacija nanočestica različitim eksperimentalnim tehnikama te je ispitana stabilnost nanočestica u fosfatnom puferu. Mezoporozna struktura nanočestica magnetita potvrđena je Brunauer-Emmett-Tellerovom analizom. Ugradnja flavonoida kvercetina, miricetina i miricitrina provedena je metodom adsorpcije, a efikasnost ugradnje kvantificirana je UV-Vis spektroskopijom. Strukturnom, morfološkom i termičkom karakterizacijom potvrđena je ugradnja flavonoida u mezoporozne nanočestice magnetita. Kinetika otpuštanja flavonoida iz istraživanih nanonosača in vitro kontrolirana je primjenom vanjskog permanentnog i oscilirajućeg magnetskog polja i kvantificirana UV-Vis spektroskopijom. Rezultati ovog doktorskog rada ukazuju na to da je razvijen nanosustav za efikasnu ugradnju flavonoida radi prevladavanja njihove slabe topljivosti i nestabilnosti u fiziološkim uvjetima. Ujedno su pronađeni optimalni uvjeti za kontrolirano otpuštanje flavonoida iz nanočestica magnetita pomoću vanjskog oscilirajućeg i permanentnog magnetskog polja.Flavonoids are natural antioxidants with a polyphenolic structure that exhibit therapeutic potential due to their anti-inflammatory, anti-cancer, antimicrobial and antioxidant properties. However, limited bioavailability and absorption in the body, poor solubility in water and instability in physiological conditions reduce their effectiveness as biologically active substances. An effective strategy to overcome these limitations is encapsulation into nanocarriers. An exceptional candidate for flavonoid delivery are mesoporous magnetite nanoparticles due to their biodegradability, physicochemical properties and superparamagnetic nature. Functionalization of nanoparticles with poly(ethylene glycol) further improves the effectivness of flavonoids by reducing the body's immune response.
In the framework of this doctoral thesis, magnetite nanoparticles functionalized with poly(ethylene glycol) were synthesized by the solvothermal method. Structural, morphological, thermal and magnetic characterization of nanoparticles was carried out using different experimental techniques, and the stability of nanoparticles was tested in phosphate buffer. The mesoporous structure of magnetite nanoparticles was confirmed by Brunauer-Emmett-Teller analysis. Encapsulation of flavonoids: quercetin, myricetin and myricitrin was carried out by the adsorption method, and the efficiency of encapsulation was determined by UV-Vis spectroscopy. Structural, thermal and morphological characterization confirmed the encapsulation of flavonoids into magnetite nanoparticles. In vitro kinetics of flavonoid release from magnetic nanocarriers was controlled by combination of external permanent and oscillating magnetic fields and quantified by UV-Vis spectroscopy. The results of this doctoral dissertation indicate that a nanosystem has been developed for the efficient encapsulation of flavonoids in order to overcome their low solubility and instability in physiological conditions. At the same time, optimal conditions were found for the controlled release of flavonoids from magnetite nanocarriers using an external oscillating and permanent magnetic field
Determination of phytotoxicity of phenol, rhodanide and cyanide on Allium cepa
No full textFenoli, cijanidi i rodanidi smatraju se glavnim onečišćujućim tvarima u sastavu koksne otpadne vode koja glasi jednom od najzahtjevnijih industrijskih otpadnih voda za zbrinjavanje. Onečišćujuće tvari u sastavu koksne otpadne vode izazivaju izrazito štetne fitotoksične učinke te je zato od velike važnosti istraživanje o njihovom djelovanju u svrhu procjene rizika, boljeg razumijevanja toksičnog djelovanja i razvoja metoda za zaštitu okoliša i organizama. Stoga se u ovom radu određivala fitotoksičnost fenola, rodanida i cijanida na sjemenkama luka Allium cepa pomoću testa klijavosti (eng. seed germination test) kojim se ispituje utjecaj ispitivanih tvari na klijanje i rani rast biljaka. Tijekom 21 dan sjemenke luka Allium cepa bile su u kontaktu s otopinama ispitivanim tvari, dodanih u tlo, različitih koncentracija (10, 25, 50, 75 i 100 mg/L) u kontroliranim uvjetima, podjednakim za sve tri ispitivane tvari. Tijekom trajanja eksperimenta pratio se broj izraslih izdanaka, postotak nicanja, visina izdanaka te mase svježe i suhe tvari, a rezultati su se uspoređivali s kontrolom kako bi bili sigurni da su učinci pripisani isključivo utjecaju fenola, rodanida i cijanida. Iz rezultata određen je postotak inhibicije gdje je vidljivo da najveći fitotoksični učinak na luk Allium cepa imaju cijanidi, zatim fenoli pa rodanidi.Phenols, cyanides and rhodanides are considered to be the main pollutants in the composition of coking wastewater, which is one of the most demanding industrial wastewaters for disposing. Pollutants, in the composition of coke waste water, cause extremely harmful phytotoxic effects, which is why research of it's mechanism of action is of great importance for the purpose of risk assessment, better understanding of toxicity mechanisms and development of methods for the protection of the environment and organisms. Therefore, in this work, the phytotoxicity of phenols, rhodanides, and cyanides was determined on Allium cepa onion seeds using the seed germination test, which examines the influence of the tested substances on germination and early plant growth. During 21 days, Allium cepa onion seeds were in contact with solutions of test substances, added to the soil, in various concentrations (10, 25, 50, 75 and 100 mg/L) under controlled conditions, identical for all three tested substances. The number of germs, the germination percentage, the height of the shoots and the mass of fresh and dry matter were monitored, and the results were compared with the control to make sure that the effects were prescribed only to the influence of phenol, rhodanide and cyanide. From the results the percentage of inhibition was determined whic showed that cyanides, followed by phenols and then rhodanides have the greatest phytotoxic effect on Allium cepa seeds