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Coordination compounds of cobalt (II): synthesis, spectroscopic and electrochemical research : diploma thesis
No full textPripravljeni su koordinacijski polimeri kobaltovog(II) iona s miješanim ligandima: derivatima nikotinske kiseline (2-bromnikotinska kiselina ili 2-klornikotinska kiselina) te 1,2-bis(4-piridil)etanom ili 1,2-bis(4- piridil)etenom. Kao metalna sol korišten je kobaltov(II) nitrat heksahidrat, a kao otapala korišteni su DMF i voda. Spojevi su karakterizirani IR spektroskopijom, UV-Vis-NIR spektroskopijom termogravimetrijskom analizom (TGA), diferencijalnom skenirajućom kalorimetrijom (DSC) te cikličkom voltametrijom. Dobiveni su koordinacijski polimeri molekulskih formula: [Co(2-Cl-nic) 2 (1,2-bpeten)] n , [Co(2-Br-nic) 2 (1,2-bpeten)] n , [Co(2- Cl-nic) 2 (1,2-bpetan)] n. Kobaltov(II) ion oktaedarski je koordiniran s četiri O donirajuća liganda (karboksilatni kisici derivata nikotinske kiseline i/ili vode) i s dva piridinska dušikova atoma. Molekule 1,2-bis(4-piridil)etana i 1,2-bis(4-piridil)etena premošćuju kobaltove(II) ione dajući beskonačni jednodimenzijski polimerni lanac.Coordination polymers of cobalt(II) ion with mixed ligands: nicotinic acid derivatives (2- bromonicotinic acid or 2-chloronicotinic acid) and 1,2-bis(4-pyridyl)ethane or 1,2-bis(4-pyridyl)ethene were prepared. Cobalt(II) nitrate hexahydrate was used as the metal salt, and DMF and water were used as the solvent. The compounds were characterized by IR spectroscopy, UV-Vis-NIR spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and cyclic voltammetry. Coordination polymers of molecular formulae were obtained: [Co(2-Cl-nic) 2 (1,2-bpetene)]n, [Co(2-Br-nic) 2 (1,2-bpetene)] n , [Co(2-Cl-nic) 2 (1,2- butane)] n . The cobalt(II) ion is octahedrally coordinated with four donating O ligand (carboxylate oxygens of nicotinic acid derivatives and/or water and with two pyridine nitrogen atoms. Molecules of 1,2-bis(4-pyridyl)ethane and 1,2- bis(4-pyridyl)ethene bridge cobalt(II) ions to give an infinite one-dimensional polymer chain
The effect of V2O5 on magnesium oxide sintering : bachelor thesis
No full textSinterirani magnezijev oksid zbog svoje velike i raznovrsne primjene kao visoko temperaturni, vatrostalni te izolacijski materijal zauzima značajno mjesto u industrijskoj primjeni. Sinteriranje je završni proces dobivanja vatrostalnih materijala na povišenim temperaturama, pri čemu sustav disperznih čestica postaje cjelina čime se povećava gustoća, čvrstoća i smanjuje poroznost polaznog materijala. U ovom radu na temelju dosadašnjih istraživanja opisan je proces sinteriranja te su navedene mogućnosti poboljšanja procesa sinteriranja magnezijeva oksida s ciljem dobivanja visoko temperaturne i korozijski otporne vatrostalne keramike dobrih mehaničkih svojstava. Sagledan je utjecaj svojstava polaznog materijala i procesnih varijabli na karakteristike konačnog proizvoda sinteriranja. Naposljetku je razmotren utjecaj dopiranja magnezijeva oksida s V 2 O 5 u svrhu poboljšanja procesa sinteriranja i svojstava vatrostalnih materijala na temelju magnezijeva oksida.Because of its broad and various appliance as high-temperature, refractory and isolation material sintered magnesium oxide takes significant place in the industrial appliance. Sintering is final, high-temperature process of obtaining refractory materials which transforms system of dispersed particles in a whole of increased density and firmness with lowered porosity. In this papper, based on previous researches, sintering process is described along with the possibilities of improving magnesium oxide sintering process with goal of obtaining high-temperature, corrosion resistent refractory material with good mechanical properties. The influence of feed material properties and process variables on the characteristics of final product of sintering are reviewed. Finally, the effect of doping magnesium oxide with V 2 O 5 is considered with the goal of improving sintering process and magnesium oxide based refractory materials properties
Cement composites preparation with the addition of admixtures : bachelor thesis
No full textU ovom radu je istraženo djelovanje aditiva na cementne kompozite. Proizvodnju betona i cementnih kompozita prate brojni problemi i zahtjevi vezani za povećanje učinkovitosti, za poboljšanje trajnosti i svojstava. Dodatkom aditiva djelomično se ostvaraju ti ciljevi. Danas skoro pa da ne postoji izvedbe nekog betonskog objekta bez primjene aditiva. Najviše se koriste za betonske kompozite kojima je postavljen visoki kriteriji kakvoće tj. onih za koje se traže posebna svojstva. Kod samog odabira aditiva treba obratiti pozornost na njegov volumni udio tj. njegovo doziranje i njegov utjecaj na hidrataciju cementnog kompozita.In this bachelor thesis, the effect of admixtures to cement composites has been investigated. The very production of concrete and cement composites is accompained by a number of problems and requirements related to the increase in efficiency, to improve durability and properties. The admixtures has partially achieved these objectives. Today almost there is no construction of a concrete object without the use of admixtures. They are mostly used for concrete composites for wich a high quality criterion has been set, i. e. those for wich special properties are required. In the case of the admixtures itself, attetintio should be paid to its volume fraction, i.e. dosage and its effect on the hydration of cement composites
Green synthesis and characterization of colloidal silver using flower honey at different pH values : master thesis
No full textBrojna izvješća koja se nalaze u literaturi ukazuju na štetnost i ekološku neprihvatljivost sinteze nanočestica kemijskim putem. Stoga postoji rastuća potreba za razvojem ekološki prihvatljivijih i ekonomski izvedljivijih procesa koji ne koriste otrovne kemikalije u procesu sinteze. U ovom radu proučavana je zelena sinteza koloidnog srebra pomoću cvjetnog meda pri pH vrijednostima 6, 7, 8, 9 i 10. Prilikom sinteze korištene su ultra čista voda, otopina cvjetnog meda, otopina srebrova nitrata koncentracije 0,001 mol dm -3 i otopina natrijevog hidroksida koncentracije 0,1 mol dm -3 . Nakon sinteze, izvršena je provjera postojanja koloidnog srebra i koncentracije srebra u otopini propuštanjem laserske zrake kroz otopinu, što je dovelo do pojave Tyndallovog efekta kod svih uzoraka. Karakterizacija dobivenih uzoraka koloida srebra provedena je UV-Vis spektrofotometrijom u području valnih duljina od 300 do 800 nm i FT-IR spektrometrijom u području valnih brojeva od 4000 do 650 cm -1 . Rezultati UV- Vis spektroskopske analize pokazali su pojavu površinskog plazmona rezonancije kod svih uzoraka. Intenziteti apsorbancije ukazuju na povoljnije uvjete odvijanja reakcija pri višim pH vrijednostima. FT- IR mjerenja su provedena kako bi se identificirale moguće biomolekule odgovorne za nastanak i stabilizaciju nanočestica srebra sintetiziranih korištenjem meda. Male razlike u valnim brojevima i intenzitetima apsorpcijske vrpce opažene su u spektrima uzoraka koloidnog srebra pri različitim pH vrijednostima.A number of reports prevailed in the literatures indicate that synthesis of nanoparticles by chemical approaches are eco unfriendly and expensive. Thus, there is a growing need to develop environmentally and economically friendly processes, which do not use toxic chemicals in the synthesis protocols. In this paper, the green synthesis of colloidal silver using floral honey was studied at pH values of 6, 7, 8, 9 and 10. During the synthesis, ultrapure water, floral honey solution, silver nitrate solution with a concentration of 0.001 mol dm -3 and sodium hydroxide solution with a concentration of 0,1 mol dm -3 were used. After the synthesis, the presence of colloidal silver and the concentration of silver in the solution were checked by passing a laser beam through the solution, which led to the appearance of the Tyndall effect in all samples. Characterization of the obtained silver colloid samples was carried out by UV-Vis spectrophotometry in the wavelength range from 300 to 800 nm and by FT-IR spectrometry in the wavelength range from 4000 to 650 cm -1 . The results of UV-Vis spectroscopic analysis showed the appearance of surface plasmon resonance in all samples. The absorbance intensities indicate more favorable conditions for reactions at higher pH values. FT-IR measurements were performed to identify possible biomolecules responsible for the formation and stabilization of silver nanoparticles synthesized using honey. Small differences in wave numbers and absorption band intensities were observed in the spectra of colloidal silver samples at different pH values
Colour substances of fruit wines : bachelor thesis
No full textVoćna vina su prehrambeni proizvodi dobiveni fermentacijom soka ili masulja različitog voća koja odlikuje svojstvena boja, ugodna aroma i okus te izuzetna pitkost. Cilj ovog završnog rada je bio odrediti tvari boje u voćnom vinu kupine, maline, višnje i aronije, odnosno glavne čimbenike boje koje uključuju: intenzitet boje, nijansu boje, sastav boje te udio crvene boje. Osim toga uzorcima je određen i sadržaj ukupnih fenola Folin- Ciocalteu metodom te sadržaj antocijana metodom bisulfitnog izbjeljivanja. Očekivano, potvrđene su razlike u navedenim parametrima među analiziranim uzorcima, pri čemu je dominiralo vino kupine koje je imalo najveći intenzitet boje, te najviši sadržaj fenola i antocijana.Fruit wines are products obtained by fermentation of fruit juice or pomace, distinguished by their inherent colour, pleasant aroma and taste and good drinkables. The aim of this bachelor thesis was to determine wine colour substances in fruit wines from blackberry, raspberries, sour-cherries and aronia; their main color attributes that include: intensity, hue, colour composition and red colour content. In addition, the samples were determined by the content of total phenols using the Folin-Ciocalteu method and content of anthocyanins using the bisulfite bleaching method. As expected, the differences among the analyzed samples were confirmed, with blackberry wine being dominant, with the highest colour intensity, as well as the highest phenolic and anthocyanin content
Seawater - source of broming : bachelor thesis
No full textBrom kao jedini tekući nemetal na sobnoj temperaturi jedan je od vrlo važnih osnovnih kemikalija u kemijskoj i farmaceutskoj industriji. Brom je vrlo reaktivan i stoga se ne nalazi u prirodi u elementarnom stanju, već se nalazi u obliku topljivih soli u morskoj/oceanskoj vodi, slanim jezerima, podzemnim slanim vodama kao i u ugušćenim slanim vodama nakon procesa desalinizacije i/ili dobivanja natrijeva klorida. Stoga se izvori broma, u kojima je isti prisutan u obliku topljivih soli, mogu smatrati neograničenima. Svrha ovog završnog rada je prikazati proces dobivanja broma iz morske vode i ukazati na glavne stavke o kojima treba voditi računa pri tehnološkom procesu dobivanja na temelju pregleda literaturnih referenci. Pregledom literature može se ustanoviti da najviše korištena tehnika komercijalne ekstrakcije broma iz morske vode uključuje primjenu metode ispuhivanja zrakom i metodu destilacije vodenom parom.Bromine, as the only liquid non-metal at room temperature, is one of the very important basic chemical raw materials in the chemical and pharmaceutical industry. Bromine is very reactive and cannot be found in nature in the free elemental state but is found in the form of soluble salts in sea/ocean water, salt lakes, and underground salt water as well as in concentrated salt water after the process of desalination and/or obtaining sodium chloride. The most widely used technique includes the air blow-out method and steam distillation. The purpose of this final paper is to show the process of obtaining bromine from sea water and to point out the main objectives that should be taken into account during the technological process of obtaining it based on a review of literature references. By reviewing the literature, it can be established that the most used technique for commercial extraction of bromine from seawater involves the application of the air blowing method and the steam distillation method
Tetrasubstituted phenanthridine derivative of calix [4]arene as a receptor in theranostics : bachelor thesis
No full textU ovom radu dan je teoretski uvid u supramolekulsku kemiju, teranostiku i kaliksarene, te njihovu primjenu. Eksperimentalno je spektrofotometrijskim titracijama istraživano veže li tetrasupstituirani fenantridinski derivat kaliks[4]arena: 5,11,17,23-tetra-tert-butil-25,26,27,28-tetrakis-((fenantridin-6- il)metoksi)kaliks[4]aren (L), odabrane boje: rodamin B, auramin O i fluorescein, s ciljem primjene dobivenih kompleksa za molekulsko označavanje u teranostici i kemoterapeutike: timokinon i paklitaksel, također za primjenu u teranostici. Pokazano je da L kompleksira navedene boje i farmakološki aktivnu tvar timokinon, međutim za paklitaksel nije opažen nastanak kompleksa. Na temelju eksperimentalnih podataka, izračunate su konstante stabilnosti odgovarajućih kompleksa. Prema dobivenim vrijednostima, u korištenim eksperimentalnim uvjetima, afinitet kaliksarenskog derivata L bio je najveći prema vezanju auramina O. Nadalje, vezanje istraživanih boja bilo je efikasnije od vezanja istraživanih lijekova, što je i očekivano s obzirom na njihove strukturne karakteristike i komplementarnost sa strukturom samog liganda Iz svega navedenog zaključeno je da se ovaj kaliksaren, unatoč dobrim receptorskim svojstvima njegovog veznog mjesta kojeg čine fenantridinske podjedinice na donjem obodu, ne može koristiti u teranostici jer nije topljiv u vodi. Međutim, njegov bi analog, s mogućnošću otapanja u vodi, mogao imati izniman potencijal primjene u teranostici.This paper provides a theoretical insight into supermolecural chemistry, theranostics and calixarene and their application. It was experimentally investigated, by means of spectrophotometric titrations, whether the tetrasubstituted phenanthridine derivative of calix[4]arene: 5,11,17,23-tetra-tert- butyl-25,26,27,28-tetrakis-((phenanthridin-6-yl)methoxy)calix[4]arene (L) binds selected dyes: rhodamine B, auramine O and fluorescein, with the aim of applying the resulting complexes for molecular labeling in theranostics and chemotherapeutic drugs: thymoquinone and paclitaxel, also for use in theranostics. It was shown that L forms complexes with these dyes and the pharmacologically active substance thymoquinone, however, the formation of complexwith paclitaxel was not observed. Based on experimental data, the stability constants of the corresponding complexes were calculated. According to the obtained values, under the experimental conditions applied, the affinity of the calixarene derivative L was the highest for the binding of auramine O. Furthermore, the binding of the three studied dyes were generally more efficient than the binding of the investigated drugs, which was expected considering their structural characteristics and complementarity with the structure of ligand itself. Keeping all of the above in mind, it is concluded that this calixarene derivative, despite of good receptor properties of its binding site formed by phenantridin substituents at the lower rim, cannot be used in theranostics because of its insolubility in water. Nevertheless, its water-soluble analog could have exeptional potential of application in theranostics
Synthesis and evaluation of phenylboronic and cinnamic acid conjugates : bachelor thesis
No full textCilj rada je prikazati sintezu i evaluaciju konjugata fenilboronične i cimetne kiseline. Fenilboronična kiselina pripada derivatima borne kiseline. Poznata je po svojim mogućim medicinskim svojstvima te je istraživana kao sredstvo u liječenje raka. Cimetna kiselina je široko zastupljena u biljnom svijetu, a izvor je većine derivata hidroksicimetne kiseline poput kumarinske, kafeinske, ferulinske i sinapinske kiseline. U ovom radu opisane su fenilboronična i cimetna kiselina općenito, njihova kemijska svojstva i strukture, upotreba njihovih derivata, te konačno sinteza fenilboronične i cimetne kiseline. Za potrebe rada korištena je relevantna literatura koja se odnosi na stručne članke i knjige koji su u skladu sa temom rada.The aim of this work is to present the synthesis and evaluation of the conjugate of phenylboronic acid and cinnamic acid. Phenylboronic acid belongs to the derivatives of boric acid. It is known for its potential medicinal properties and has been explored as a treatment for cancer. Cinnamic acid is widely distributed in the plant world and is the source of most hydroxycinnamic acid derivatives such as coumarin, caffeic acid, ferulic acid, and sinapic acid. In this paper, phenylboronic and cinnamic acids in general, their chemical properties and structures, the use of their derivatives and finally the synthesis of phenylboronic and cinnamic acids are described. Relevant literature was consulted for the paper, referring to technical articles and books corresponding to the subject of the paper
Antimicrobial activity of blackberry leaf extract and selected phenolics mixtures on pathogenic bacteria : master thesis
No full textSve je veća zabrinutost potrošaĉa oko sigurnosti hrane zbog povećanja broja oboljenja uzrokovanih patogenim mikroorganizmima. Brojna znanstvena istraţivanja ukazuju na mogućnost korištenja nusproizvoda za obogaćivanje drugih proizvoda ili kao zamjena za sintetska antimikrobna sredstva. Antioksidativno i antimikrobno djelovanje bobiĉastog voća je već potvrĊeno, a navedeni uĉinci se uglavnom pripisuju njihovom fenolnom sastavu, odnosno spojevima poput flavonoida i antocijana, a poznato je da listovi kupine isto imaju zanimljiv kemijski profil kao i snaţnu biološku aktivnost. U ovom radu prouĉavano je antimikrobno djelovanje ekstrakta lista kupine u kombinaciji s odabranim fenolnim spojevima (vanilinska kiselina, katehin, rutin, apigenin i oleuropein) na patogene mikroorganizme: Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Escherichia coli, Enterococcus faecalis i Salmonella enteritidis. Analiza je provedena korištenjem dviju razliĉitih metoda: metodom odreĊivanja minimalne inhibitorne koncentracije (engl. Minimum inhibitory concentracion, MIC) i metodom odreĊivanja minimalne baktericidne koncentracije (engl. Minimum bactericidal concentration, MBC). Interakcijski antimikrobni uĉinak izmeĊu ekstrakta i spoja u smjesi odreĊen je izraĉunavanjem frakcijskog inhibitornog koncentracijskog indeksa (eng. Fractional Inhibitory Concentration Index, FICI). Niske MIC vrijednosti (0,63 mg/mL) i dobro baktericidno djelovanje (MBC 1,25 mg/mL) potvrĊeno je za ekstrakt lista kupine prema S. aureus, dok su vrijednosti MIC za ostale ispitivane bakterije bile 5 mg/mL. Sve binarne smjese ekstrakta lišća kupine i odabranih fenolnih spojeva pokazale su vrlo dobru antimikrobnu aktivnost i uglavnom su ukazivale na aditivno djelovanje sastojaka smjese. Samo je smjesa ekstrakta lista kupine i oleuropeina pokazala sinergistiĉki uĉinak prema L. monocytogenes (MIC=1,25+0,31 mg/L, te FICI 0,5).Due to the increasing number of diseases caused by pathogenic microorganisms, consumers are becoming increasingly concerned about food safety. Numerous scientific studies point to the possibility of using by-products to fortify foods or their use as substitutes for synthetic antimicrobials. The antioxidant and antimicrobial effects of berries have been already confirmed and are primarily related to their phenolic content, mainly compounds such as flavonoids and anthocyanins, blackberry leaves have interesting chemical profile and strong biological activity. In this work, the antimicrobial activity of blackberry leaf extract in combination with selected phenolic compounds (vanillic acid, catechin, rutin, apigenin and oleuropein) against foodborne pathogens: Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Escherichia coli, Enterococcus faecalis and Salmonella enteitidis was studied. Analysis was performed using two different methods: minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The interaction between extract and compoundsin terms of antibacterial activity was determined by calculating the fractional inhibitory concentration index (FICI). The low MIC (0.63 mg/mL) and good bactericidal activity (MBC 1.25 mg/mL) were confirmed for the blackberry leaf extract against S. aureus, while the MIC values for the other tested bacteria were 5 mg/mL. All binary mixtures of blackberry leaf extract and selected phenolic compounds showed very good antimicrobial activity and mostly indicated additive activity. Only mixture of blackberry leaf extract and oleuropein had a synergistic effect against L. monocytogenes (MIC=1.25+0.31 mg/L, and FICI 0.5)
Determination of eucalyptol (1,8-cineola) in myrtle, cajeput and niaouli essential oils : bachelor thesis
No full text1,8-Cineol monoterpen je sadržan u brojnim eteričnim uljima. Zbog svoje ugodne arome i okusa, koristi se u raznim mirisima i kozmetici. Antioksidacijska i protuupalna svojstva čine ga važnim sastojkom u farmaceutskim proizvodima. U ovom radu razvijena je metoda za određivanje 1,8-cineola. Za kvantitativno i kvalitativno određivanje 1,8-cineola korištena je tehnika plinske kromatografije s tandemskom spektrometrijom masa. Korištenjem iste tehnike određene su koncentracije 1,8-cineola u eteričnim uljima kajeputa, mirte i niauli. Praćenjem MRM načina snimanja za različite signale 1,8-cineola određene su specifične reakcije prijelaza pomoću spektrometra masa s trostrukim kvadrupolom. Tako je spektrometrija masa optimizirana određivanjem energija sraza s dušikom za svaki izabrani prijelaz. Za izradu krivulja umjeravanja korišten je raspon koncentracija 50 µg mL -1 - 2000 µg mL -1 . Zadovoljeni su ispitani parametri vrednovanja metode (točnost, preciznost, specifičnost, linearnost, granice određivanja i dokazivanja). Analizom realnog uzorka eteričnih ulja primjenom navedene metode uspješno su im određene koncentracije.1,8-Cineole monoterpene is contained in numerous essential oils. Due to its pleasant aroma and taste, it is used in various fragrances and cosmetics. Its antioxidant and anti-inflammatory properties make it an essential ingredient in pharmaceutical products. In this work, a method was developed for the quantitative and qualitative determination of 1,8-cineole using gas chromatography with tandem mass. The same technique was employed for detrmination of the concentrations of 1,8-cineole in the essential oils of cajeput, myrtle and niauli were determined. Triple quadeupole mass spectrometer was used for monitoring different 1,8-cineole signals in MRM mode for specific transition reactions. Thus, the mass spectrometry was optimized by determining the collision energies with nitrogen for each selected transition. The concentration range of 50 µg mL -1 - 2000 µg mL -1 was used to create calibration curves. The tested parameters of the evaluation of the method (accuracy, precision, specificity, linearity, limits of determination and proof) were satisfactory. By analyzing real samples of essential oils using the mentioned method, their concentrations were successfully determined