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Investigation of mechanical properties of high strenght shipbuilding steel LR-AH36 at different temperatures : bachelor thesis
No full textU ovom radu provedeno je ispitivanje mehaničkih svojstava brodograđevnog materijala kvalitete AH36 pri različitim temperaturama. Dio epruveta je podvrgnut pothlađivanju do -30 °C, a dio zagrijavanju do 650 °C. Mjerenje je provedeno u Brodosplitu na kidalici MAN 60 na kojoj se vlačnom silom djeluje na ispitni uzorak sve do pojave loma. Dobiveni dijagrami pothlađenih epruveta jasno prikazuju točku granice razvlačenja dok je kod epruveta povišene temperature ona slabije izražena. Iz rezultata se može zaključiti da granica razvlačenja i vlačna čvrstoća rastu snižavanjem temperature, a izduženje se smanjuje. Kod epruvete 8 i 11 uočena su manja odstupanja od navedenog zaključka.In this paper, the mechanical characteristic of AH36 quality shipbuilding material was tested at different temperatures. Part of the tubes was subjected to subcooling to -30 °C, and part to heating to 650 °C. The measurement was performed in Brodosplit on a MAN 60 tensile testing machine on which the tensile force acts on the test specimen until fracture occurs. The obtained diagrams of subcooled specimens clearly show the point of yield strength, while in the case of elevated temperature specimens it is less expressed. From the results it can be concluded that the yield strength and tensile strength increase with decreasing temperature, and the elongation decreases. In test tubes 8 and 11 minor deviations from the stated conclusion were observed
preparation of poly(lactic acid) composites with modified olive stone flour : bachelor thesis
No full textU ovom radu provedena je esterifikacija površine mljevenih koštica masline (MKM) sa stearinskom kiselinom (SA). Dokazivanje provedene reakcije esterifikacije površine punila izvršeno je pomoću infracrvene spektroskopije s Fourierovom transformacijom (FT-IR). Uočene promjene FT-IR spektra modificiranih koštica masline (mMKM) u odnosu na MKM jasno ukazuju na uspješno proveden postupak esterifikacije nakon čega se modificirano punilo upotrijebilo za pripravu kompozita s polilaktidnom kiselinom (PLA). FT-IR spektroskopija je također upotrijebljena za ispitivanje interakcija između PLA i mMKM. Dodatak kao i povećanje sadržaja modificiranog punila nije dovelo do uspostave interakcija između komponenata kompozita, pa se buduća istraživanja moraju usmjeriti prema drugim modifikatorima ili postupcima modificiranja kako bi se dobili PLA kompoziti što boljih svojstava.In this work, the esterification of olive stone flour surface (OSF) with stearic acid (SA) was performed. Analysis of successfully performed esterification of the filler surface was performed using Fourier transform infrared spectroscopy (FT-IR). The observed changes in the FT-IR spectrum of modified olive stone flour (mOSF) relative to OSF clearly indicate successful esterification process after which the modified filler was used to prepare poly(lactic acid) (PLA) composites. FT-IR spectroscopy was also used to investigate the interactions between PLA and mOSF. The addition as well as the increase in the content of the modified filler did not lead to the establishment of interactions between the composite components, so future research must be directed towards other modifiers or modification procedures in order to obtain PLA composites with better properties
Antioxidant properties of spices : diploma thesis
No full textPod utjecajem različitih čimbenika u organizmu se stvaraju štetni slobodni radikali, koji predstavljaju stalnu prijetnju ljudskom organizmu. Kako bi se obranio od istih organizam u normalnom fiziološkom stanju proizvodi antioksidanse, molekule sposobne da spriječe oksidaciju drugih molekula. Brojnim istraživanjima pokazalo se da različite vrste začinskog bilja imaju značajna antioksidacijska svojstva u borbi protiv slobodnih radikala i pozitivan učinak na ljudsko zdravlje. Za određivanje antioksidacijske sposobnosti nekog uzorka koriste se različite metode zasnivane na različitim mehanizmima djelovanja na određenu vrstu slobodnih radikala. U cilju određivanja antioksidacijskog kapaciteta uzoraka u ovom radu su korištene ORAC (engl. Oxygen Radical Absorbance Capacity), DPPH (engl. 2,2-diphenyl-1-picryl- hidrazyl-hydrate) i FRAP (engl. Ferric Reducing Antioxidant Power) metode. Analizirani su ekstrakti češnjaka, peršina, limuna, celera, selena, komorača, papra crnog, papra zelenog, kurkume, nusproizvoda kurkume, luka žutog te luka ljubičastog. Najslabiju antioksidacijsku aktivnost ORAC metodom pokazao je ekstrakt komorača, DPPH metodom ekstrakt celera, dok je kod FRAP metode najmanju aktivnost pokazao češnjak. Ostali dobiveni rezultati ukazuju na dobra antioksidacijska svojstva nekoliko začinskih biljaka od kojih se posebno ističe crni papar koji je pokazao znatno najbolju aktivnost korištenjem svih metoda.Free radicals are created under the influence of various factors in the body and they represent a permanent danger to the human organism. To protect themselves from radicals, the organism in the normal physiological state produces antioxidants, molecules capable of inhibiting the oxidation of other molecules. Numerous studies have shown that different types of spices have significant antioxidant properties in the fight against free radicals and positive effects on human health. For determination of the antioxidant capacity of the samples, various antioxidant methods, based on different mechanisms of action on a particular type of free radicals, are used. To determine the antioxidant capacity of the samples in this paper, ORAC (Oxygen Radical Absorbance Capacity), DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate), and FRAP (Ferric Reducing Antioxidant Power) methods were used. Extracts of garlic, parsley, lemon, celery, selenium, fennel, black pepper, green pepper, turmeric, turmeric by-products, yellow onion, and purple onion were analyzed. The weakest antioxidant activity was shown by fennel extract by the ORAC method, the celery extract by the DPPH method, while the FRAP method showed the lowest activity by garlic. Other obtained results indicate good antioxidant properties of several spice plants, of which black pepper stands out, which showed the best activity using all methods
Potentiometric determination of fluoride in honey - review : bachelor thesis
No full textMed je gust i sladak sok kojeg proizvode pčele medarice od nektara koji skupljaju na cvjetovima ili slatkim izlučevinama. Med sadrži flavonoide i antioksidanse koji smanjuju rizik od raznih bolesti. Potenciometrija je elektroanalitička metoda u kojoj se mjeri razlika potencijala između elektroda elektrokemijskog članka uz ravnotežne uvjete. Potenciometrijska određivanja, konkretno fluorida, u medu su počela u 21. stoljeću. U ovom radu dat je pregled novije literature za fluorid ionsko selektivnu elektrodu (FISE), za ionsko- selektivne elektrode, te pregled rezultata laboratorijskih određivanja fluroida fluorid ionsko selektivnom elektrodom.Honey is a thick and sweet juice produced by honey bees from nectar that they collect on flowers or sweet secretions. Honey contains flavonoids and antioxidants that reduce the risk of various diseases. Potentiometry is an electroanalytical method in which the potential difference is measured between the electrodes of an electrochemical cell under equilibrium conditions. Potentiometric determinations, specifically of fluoride, in honey began in the 21st century. This review describes recent literature on fluoride – ion selective electrodes, recent literature on ion-selective electrodes and review for laboratory results of fluoride determination in honey by ion-specific electrod
Preparation and characterization of polylactide/clinoptilolite composites : bachelor thesis
No full textSvrha ovog rada je pripremiti kompozite polilaktid/klinoptililot metodom izlijevanja filma i istražiti utjecaj klinoptilolita na svojstva polilaktida (ponašanje u vodi i toplinska razgadnja). Pripremljeni su filmovi kompozita PLA/klinoptilolit u kloroformu s 0, 2, 4, 6, 8 i 10 % klinoptilolita. Analizom FT-IR spektara potvrđen je zaostatak otapala u kompozitima. Primjenom neizotermne termogravimetrije istraživan je utjecaj klinoptilolita na toplinsku postojanost PLA. Rezultati su pokazali da dodatak klinoptilolita poboljšava toplinsku postojanost polilaktida. Kompoziti PLA/klinoptilolit su držani u vodi 5 dana kako bi se utvrdilo dolazi li do procesa apsorpcije vode ili hidrolize polilaktida. Pretpostavlja se da je kod svih kompozita došlo do hidrolize polilaktida, a kod kompozita sa 6 i 8 % klinoptilolita došlo je i do apsorpcije vode.The purpose of this thesis is to prepare polylactide/clinoptilolite composites by the film casting method and to investigate the influence of clinoptilolite on the properties of polylactide (water behavior and thermal decomposition). Films of PLA/clinoptilolite composites in chloroform with 0, 2, 4, 6, 8 and 10 % clinoptilolite were prepared. Solvent residue in the composites was confirmed by FT-IR spectrum analysis. The influence of clinoptilolite on thermal stability of PLA was investigated using non-isothermal thermogravimetry. The results showed that the addition of clinoptilolite improves the thermal stability of polylactide. PLA/clinoptilolite composites were kept in water for 5 days to determine whether a process of water absorption or hydrolysis of the polylactide occurred. It is assumed that polylactide hydrolysis occurred in all composites, and water absorption occurred in composites with 6 and 8 % clinoptilolite
Solid waste from food production and processing as a potential biosorbent treatment of waters polluted by lead and zinc : diploma thesis
No full textRazvoj kemijske industrije i rudarstva, kao i primjena suvremenih agrotehničkih mjera u poljoprivrednoj proizvodnji, doveli su do značajne emisije teških metala u okoliš, posebice u tlo i vodne ekosustave. Takve vode nisu prikladne za ljudsku potrošnju kao ni za potrebe industrije i navodnjavanja te je nužno naći ekonomski prihvatljive i učinkovite načine njihova pročišćavanja. U posljednje vrijeme raste interes za uporabom jeftinih, ekološki prihvatljivih i lako dostupnih materijala za uklanjanje teških metala iz otpadnih voda. Budući da porastom broja stanovnika raste proizvodnja i prerada hrane, a time i količina organskog čvrstog otpada, cilj ovoga rada bio je ispitati mogućnost uporabe takvog otpada u pročišćavanju voda onečišćenih teškim metalima. Za uklanjanje olova i cinka iz vodenih otopina kao biosorbent korišten je otpad prikupljen iz lokalnih pogona za proizvodnju i preradu hrane - koštice masline, pelet komine masline, ostaci hridinskog ježinca, koštice višnje i koštice trešnje. Eksperimenti su provedeni u tri uzastopna ciklusa sorpcije šaržnim postupkom. Ukupna učinkovitost u uklanjanju olova nakon tri ciklusa je od 37,6 do 89,2%, a cinka od 58,43 do 75,09%, s najboljim uklanjanjem na košticama višnje. Promatrajući cikluse pojedinačno, olovo je najbolje uklonjeno na košticama višnje i to u sva tri ciklusa, dok je cink najbolje uklonjen na ostacima hridinskog ježinca u prvom ciklusu, na košticama trešnje u drugom ciklusu te na košticama višnje u trećem ciklusu. Iako konačna koncentracija oba metala nije ispod graničnih dopuštenih vrijednosti, postignuto je zadovoljavajuće uklanjanje na svim biosorbentima. Smanjenje koncentracija olova i cinka do dopuštenih razina za ispust u površinske vode ili u sustav javne odvodnje moglo bi se postići različitim modifikacijama biosorbenata kao i sorpcijom postupkom u koloni, za što su nužna daljnja istraživanja. Ipak, otpad i ostaci iz proizvodnje i prerade hrane mogu se korisno upotrijebiti kao biosorbenti za uklanjanje teških metala olova i cinka, što bi smanjilo ukupne troškove obrade voda te pridonijelo konceptu održivog razvojaThe chemical industry development and mining, as well as the application of modern agrotechnical measures in agricultural production, have led to significant emissions of heavy metals into the environment, especially into soil and aquatic ecosystems. Such waters are not suitable for human consumption as well as for the needs of industry and irrigation, and it is necessary to find economically acceptable and efficient ways of their purification. Recently, there has been a growing interest in the use of low-cost, environmentally friendly and easy available materials for the removal of heavy metals from wastewater. Since the increase in population increases the production and processing of food, and thus the amount of organic solid waste, the aim of this study was to examine the possibility of using such waste in the treatment of water contaminated with heavy metals. To remove lead and zinc from aqueous solutions, waste collected from local plants for food production and processing was used as a biosorbent - olive pits, olive pomace pellets, and remains of the sea urchin, sour cherry pits and cherry pits. The experiments were performed in three consecutive sorption cycles by the batch process. The overall efficiency in removing lead after three cycles is from 37.6 to 89.2% and zinc from 58.43 to 75.09%, with the best removal on cherry pits. Observing the cycles individually, lead was best removed on cherry pits in all three cycles, while zinc was best removed on the remains of the sea urchin in the first cycle, on the cherry pits in the second cycle and on the sour cherry pits in the third cycle. Although the final concentration of both metals is not below the limit values, satisfactory removal has been achieved on all biosorbents. Reduction of lead and zinc concentrations to permissible levels for discharge into surface waters or into the public drainage system could be achieved by various modifications of biosorbents as well as by sorption by the column process, for which further research is necessary. Nevertheless, waste and residues from food production and processing can be used as biosorbents to remove heavy metals lead and zinc, which would reduce the total cost of water treatment and contribute to the concept of sustainable development
Biological activity of celery and ginger essential oil : graduate thesis
No full textAlzheimerova bolest je jedna od najčešćih degenerativnih bolesti mozga, a karakterizira ju oštećenje živčanih stanica i propadanje kognitivnih funkcija. Pravi lijek nije poznat, ali se najčešće primjenjuju inhibitori acetilkolinesteraze. U ovom radu kao potencijalni inhibitori ispitana su eterična ulja đumbira (Zingiber officinale Roscoe) i celera (Apium graveolens L.). Kako bi se utvrdila potencijalna inhibicijska sposobnost ispitivanih ulja korištena je modificirana spektrofotometrijska metoda po Ellmanu. Prema dobivenim rezultatima vidljivo je da eterično ulje đumbira nema inhibicijskih sposobnosti, dok eterično ulje celera pokazuje inhibicijsku aktivnost ovisno o koncentraciji ispitivane otopine. Ulja su također ispitivana i na antioksidacijsku aktivnost pomoću DPPH i FRAP metoda te se prema dobivenim rezultatima može zaključiti da ni jedno od ispitivanih ulja nema značajnu antioksidativne sposobnosti. Sastav eteričnih ulja određen je GC-MS analizom te su se kao najzastupljeniji spojevi u eteričnom ulju celera pokazali limonen, β-selinen, sedanenolid, 3-n-butilftalid, α-selinen, dok su kod eteričnog ulja đumbira to α-zingiberen, β-seskvifelandren, β-bisabolen te α-kurkumen.Alzheimer's disease is one of the most common degenerative diseases of the brain, and it is characterized by damage to nerve cells and deterioration of cognitive functions. The exact drug is not known, but acetylcholinesterase inhibitors are most used. In this work, the essential oils of ginger (Zingiber officinale Roscoe) and celery (Apium graveolens L.) are tested as potential inhibitors. A modified Ellman spectrophotometric method was used to determine the potential inhibitory ability of the tested oils. According to the obtained results, it is evident that ginger essential oil has no inhibitory abilities, while celery essential oil shows inhibitory activity depending on the concentration of the test solution. The oils were also tested for antioxidant activity using DPPH and FRAP methods, and according to the obtained results, it can be concluded that none of the tested oils has significant antioxidant capacity. The composition of essential oils was determined by GC-MS analysis, and the most common compounds in celery essential oil were limonene, β-selinene, sedanenolide, 3-n-butylphthalide, α-selinene, while in ginger essential oil it was α-zingiberene, β-sesquifelandrene, β-bisabolene and α-curcumene
ORAC values of equimolar phenolic mixtures : bachelor thesis
No full textFenoli su najzastupljeniji organo-kemijski spojevi u prirodi. Ova grupa sekundarnih biljnih metabolita ima razne uloge u prirodi, ali ipak najvažnija je ona antioksidacijska koja ovisi o nekoliko čimbenika. Cilj ovo rada bio je analizirati smjese fenolnih kiselina i to iz podgrupa derivata hidroksibenzojeve i derivata hidroksicimetne kiseline metodom ORAC (engl. Oxygen Radical Absorance Activity) te na temelju rezultata donijeti zaključke o mogućem sinergijskom, aditivnom ili antagonističkom učinku. Rezultati ovog istraživanja pokazuju da je većina smjesa, osobito binarnih smjesa pokazala sinergijsko djelovanje. Dodatkom treće kiseline u smjesu u slučaju derivata hidroksibenzojeve kiseline antioksidacijska aktivnost smjese slabi, ali i dalje uočavamo sinergijski učinak, dok su rezultati kod derivata hidroksicimetne kiseline uglavnom ukazali na aditivno i antagonističko djelovanje. U smjesama četiri i pet kiselina derivati hidroksibenzojeve kiseline su uglavnom pokazali sinergiju, a derivati hidroksicimetne kiseline aditivno djelovanje. Na temelju ovog istraživanja može se zaključiti da su ekvimolarne smjese derivata hidroksibenzojeve kiseline imale bolji antioksidacijsko djelovanje i interakcijski učinak od derivata hidroksicimetne kiseline.Phenols are the most abundant organochemical compounds in nature. This group of secondary plant metabolites has various roles in nature, yet the most important one is the antioxidant activity which depends on several factors. The aim of this study was to analyze mixtures of phenolic acids from subgroups of hydroxybenzoic derivatives and hydroxcinnamic acid derivatives by the ORAC method (Oxygen Radical Absorbance Activity) and to draw conclusions about possible synergistic, additive or antagonistic effect based on the results obtained. The results of this research show that most mixtures, especially mixtures of two acids, showed a synergistic effect. The addition of a third acid in the mixture in the case of hydroxbenzoic acid derivatives weakens the antioxidant activity of the mixture, but we still see a synergistic effect. While, in case of hydroxcinnamic acid derivatives, results mainly indicated both additive and antagonistic effects. In the mixtures containing four and five acids hydroxbenzoic acid derivatives mainly showed synergy, while hydroxcinnamic acid derivatives additive action. Based on this study, it can be concluded that equimolar mixtures of hydroxbenzoic acid derivatives had a better antioxidant activity and interaction effect than hydroxcinnamic acid derivatives
Biotransformations of sesquiterpenes nerolidol and farnesol - in silico approach : bachelor thesis
No full textFarmakokinetika govori o sudbini lijeka unesenog u organizam. Lijek se u krvotok može aplicirati intavenski, subkutano (pod kožu), intramuskularno, rektalno, topikalno (izravno na mjesto na kojem se očekuje djelovanje), inhalacijom i oralno. Raspodjela u organizmu nije ravnomjerna zbog različite prokrvljenosti organa, različitog sastava i propusnosti membrana te zbog različitog lokalnog pH. Jetra su najvažniji organ u metabolizmu lijekova i ksenobiotika (tvari koje su unesene u organizam, strane organizmu), a najvažnija enzimska porodica u metabolizmu lijekova su enzimi citokrom P450 porodice (CYP 450). Bubrezi su najvažniji organi koji pomažu u izlučivanju lijekova iz organizma, a izlučivanje je moguće i pomoću jetre u žuč. Nerolidol i farnezol su seskviterpenski alkoholi prisutni u raznim biljkama cvjetnog mirisa. Imaju brojne biološke aktivnosti od kojih i antikancerogeno djelovanje. Svi programi i modeli predviđanja bioloških aktivnosti mogli bi se podijeliti u dvije skupine: ligand (supstrat) bazirane i strukturno (enzimski) bazirane. Mjesto metabolizma (eng. the site of metabolism-SOM) je mjesto u molekuli koje se sastoji od jednog ili nekoliko atoma koji dolaze u interakciju s enzimima i kemijski se mijenjaju. U ovom radu su korišteni programi sa platforme way2drug. SOMP (eng. site of metabolism prediction) je korišten za predviđanje mjesta metabolizma organskih tvari za pet izoformi citokroma P450 te mjesta za glukuronidaciju UDP-glukuronil transferazom, a RA (eng. reacting atom) za predviđena mjesta biotransformacije te vrste reakcija biotransformacije koje bi se mogle odviti koji. Dobivena predviđanja nisu dovoljno precizna da bi predočila metabolički put nerolidola i farnezola u organizmu, ali pružaju bolji uvid u reakcije koje bi se mogle odvijati te mogu pomoći pri daljnjim istraživanjima.Pharmacokinetics shows us fate of ingested drugs. The drug can be administered into the bloodstream intravenously, subcutaneously (under the skin), intramuscularly, rectally, topically (directly at the site where the action is expected), by inhalation and orally. The distribution in the organism is not uniform due to different blood supply to the organs, different composition and permeability of the membranes and different local pH. The liver is the most important organ in drug and xenobiotics (substances introduced into the body, foreign bodies) metabolism. The most important enzyme family in drug metabolism are cytochrome P450 enzymes (CYP 450). The kidneys are the most important organs for excretion of drugs from the body. Excretion is also possible by the liver in the bile. Nerolidol and farnesol are sesquiterpenic alcohols present in various floral fragrance of plants. They have numerous biological activities like anticancer activity. All programs and models for predicting biological activities could be divided into two groups: ligand (substrate) based and structural (enzyme) based. The site of metabolism (SOM) is a site in a molecule that consists of one or more atoms that interact with enzymes and change chemically. In this paper were used programs available on way2drug platform. SOMP (Site of Metabolism Prediction) was used to predict the site of organic matter metabolism for the five cytochrome P450 isoforms and the site for glucuronidation by UDP-glucuronyl transferase. RA (Reacting atom) was used for prediction of biotransformation sites, and the types of biotransformation reactions that could happen. The predictions obtained are not precise enough to show the metabolic pathways of nerolidol and farnesol in the body, but they provide a better view into the reactions that could take place and may help in further studies
Impact of PBT impeller speed on copper adsorption on zeolite : diploma thesis
No full textU ovom radu ispitan je utjecaj brzine miješanja na adsorpciju bakra na zeolitu NaX i utrošak snage miješanja. Otopina koja sadrži Cu 2+ ione pripravljena je otapanjem odgovarajuće mase Cu(NO 3 ) 2 ∙ 3H 2 O. Zeolit NaX samljeven je i prosijan na čestice veličine od 0,063 do 0,090 mm. Eksperiment se proveo u kotlastom reaktoru s razbijalima virova uz turbinsko miješalo s 4 lopatice pod kutom od 45° tzv. PBT. Kako bi se sagledao utjecaj brzine miješala na kinetiku adsorpcije, provedeni su eksperimenti pri četiri različite brzine vrtnje miješala uz stalnu temperaturu suspenzije. Kinetičkom analizom eksperimentalnih podataka Ritchievim i Weber-Morrisovim modelom uočeno je vrlo dobro slaganje dobivenih podataka s Ritchijevim modelom što ukazuje na to da reakcija prati kinetiku drugoga reda. Rezultati ispitivanja ukazali su i da se povećanjem brzine vrtnje PBT miješala povećava utrošak snage miješanja.In this work, the influence of the mixing rate on the kinetics of copper adsorption on NaX zeolite and the mixing power consumption were investigated. A solution containing Cu 2+ ions with known initial concentration was prepared by dissolving the appropriate mass of Cu(NO 3 ) 2 ∙ 3H 2 O. The zeolite NaX was crushed and sieved to obtain particles of 0.063 to 0.090 mm. Mechanical mixing was performed with a turbine impeller with 4 blades at an angle of 45° so-called PBT in a batch reactor with baffles. To observe the influence of the impeller speed on the adsorption kinetics, experiments were performed at four different impeller speeds, while the suspension temperature was constant. The obtained experimental kinetics data were analyzed by Ritchie and Weber-Morris model. The kinetic analysis showed an agreement of the obtained data with the Ritchie model, which indicates that the reaction follows the second-order kinetics. The test results indicated that with the increasing speed of the PBT impeller, the power consumption increases