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Spectrophotometric deteremination of drugs which contain a phenolic group-review : bachelor thesis
No full textFenoli su aromatski spojevi koji imaju hidroksilnu skupinu vezanu na benzene. Danas je poznato nekoliko tisuća fenolnih spojeva. Fenolni spojevi imaju pozitivan učinak na ljudsko zdravlje, zbog čega su prisutni su u mnogim lijekovima. Oni imaju protuupalna, antimikrobna, antipiretička, analgetska, antioksidacijska i brojna druga svojstva. Često korišteni lijekovi koji imaju fenolnu skupinu su paracetamol, amoksicilin, salbutamol, piridoksin, izoksuprin itd. Lijekovi su kemijski spojevi koji poboljšavaju kvalitetu života. Provjera njihove kvalitete bitan je dio farmaceutske industrije. Spektrofotometrija je jedna od najčešće korištenih tehnika koja se koristi za određivanje lijekova. Kvalitativna analiza se zasniva na Beerovom zakonu. Beerov zakon nam omogućuje određivanje koncentracije analita mjerenjem apsorbancije. U ovom radu dat je pregled spektrofotometrijskih metoda koje se koriste za određivanje fenolnih lijekova.Phenols are aromatic compounds that have a hydroxyl group attached to benzenes. Today, several thousand phenolic compounds are known. Phenolic compounds have a positive effect on human health, which is why they are present in many drugs. They have anti-inflammatory, antimicrobial, antipyretic, analgesic, antioxidant and many other properties. Commonly used drugs that have a phenolic group are paracetamol, amoxicillin, salbutamol, pyridoxine, isoxuprine, etc. Drugs are chemical compounds that improves quality of life. Checking their quality is an essential part of the pharmaceutical industry. Spectrophotometry is one of the most commonly used techniques to determine drugs. Qualitative analysis is based on Beer's law. Beer's law allows us to determine the concentration of analytes by measuring the absorbance. This paper provides an overview of the spectrophotometric methods used to determine phenolic drug
Investigation of response of membranes made of FePO4:Ag2S:PTFE=1:1:2 enriched with goethite nanoparticles : diploma thesis
No full textIonsko-selektivne elektrode su u posljednje vrijeme pobudile veliki interes znanstvenicima i postale predmet brojnih znanstvenih istraživanja. Često se obogaćuju raznim modifikatorima od kojih je važno spomenuti nanočestice. U ovom radu, testirane su tri membrane u čijem su sastavu kao osnovne komponente prisutni: željezov(III) fosfat, srebrov sulfid te politetrafluoroetilen uz dodatak 0,25, 0,5 i 1% nanočestica getita sintetiziranih mikrovalnom sintezom. Navedene membrane su testirane na odziv prema željezovim(III) ionima pri raznim pH vrijednostima. Željezo je široko rasprostranjen element, kako u okolišu tako i u ljudskom organizmu. Stoga je od iznimne važnosti pronaći senzor koji bi brzo, pouzdano i selektivno odredio njegovu koncentraciju u različitim realnim uzorcima. Najprikladnija za ovo ispitivanje ispostavila se potenciometrijska metoda zbog svoje robusnosti, jednostavnosti, praktičnosti i primjerene cijene.Ion-selective electrodes have recently aroused great interest among scientists and have become the subject of numerous scientific studies. They are often enriched with various modifiers of which it is important to mention nanoparticles. In this work, three membranes were tested in which the basic components are present: iron(III) phosphate, silver sulfide and polytetrafluoroethylene with the addition of 0.25, 0.5 and 1% of goethite nanoparticles synthesized by microwave synthesis. These membranes were tested for response to iron(III) ions at various pH values. Iron is a widespread element, both in the environment and in the human body. Therefore, it is extremely important to find a sensor that would quickly, reliably and selectively determine its concentration in different actual samples. The potentiometric method turned out to be the most suitable for this test due to its robustness, simplicity, practicality and acceptable price
Effect of MgO additive on the specific conductivity of portland cement paste : master thesis
No full textU ovom radu provedeno je određivanje specifične električne provodnosti cementnih pasti bez dodatka, te uz dodatak 5 mas. % i 10 mas. % MgO. Ispitivan je utjecaj dodatka MgO na pojavu maksimuma specifične električne provodnosti cementnih pasti. Mjerenja su provedena u termostatu pri 20 ⁰C i pri vodocementnom V/C = 0,5 i voda/kruto omjeru, V/K = 0,5. Sve dobivene krivulje ovisnosti specifične električne provodnosti o vremenu hidratacije pokazuju sličan oblik s naglašenim maksimumom specifične električne provodnosti. Iz rezultata se može zaključiti da čisti portland cement ima najveću vrijednost specifične električne provodnosti koja iznosi 18,22 mS cm -1 , dok dodatak prirodnog i sintetskog MgO uzrokuje pad specifične električne provodnosti.In this paper, the determination of the specific electrical conductivity of the cement pastes was carried out without the addition and with addition od 5 wt. % and 10 wt. % MgO. The effect od MgO addition on the appearance of the maximum soecific electrical conductivity of cement pastes was examined. The measurements were carried out in the thermostat at 20 ⁰C and at the water/cement ratio, W/C = 0.5 and water/solid ration, W/S = 0.5. All obtained curves of specific electrical conductivity dependence on the hydration time of the cement paste show a similar shape with a pronounces maksimum of the specific electrical conductivity. From the results it can be concluded that pure portland cement has the highest value of specific electrical conductivity which is 18.22 mS cm -1 , while the addition of natural and synthetic MgO causes a decrease of specific electrical conductivity. Samples with the addition of MgO have the appearance of a maximum of specific electrical conductivity in earlier hydration times
Dye-sensitized solar cells : bachelor thesis
No full textU ovom radu proučavana su svojstva, prednosti i mane sunčanih ćelija, rad sunčanih ćelija s fotoaktivnim bojilima (DSSC) i aktivnost fotoaktivnih bojila. Sunčane ćelije su uređaji za pretvorbu svjetlosne energije u električnu energiju. DSSC ćelije pripadaju trećoj generaciji sunčanih ćelija i imaju obećavajuće rezultate u odnosu na ostale sunčane ćelije. Pridaje im se veliki značaj zbog niske cijene u odnosu na ostale uređaje koji rade na istom principu. Ćelija se sastoji od fotosenzibilne anode koja se sastoji od poluvodičkog sloja metalnog oksida (TiO 2 , ZnO, Sb 2 O 5 , Al 2 O 3 ) presvučenog prozirnim vodljivim filmom (TCO), molekula bojila adsorbiranih na površini poluvodičkog metalnog oksida i pomoćne elektrode. Prednost nad ostalim generacijama ćelija je niska cijena komponenata, visok stupanj iskorištenja i nisu štetne za okoliš. Kod fotoaktivnih bojila najčešće korištena bojila su rutenijevi spojevi zbog njihove široke apsorpcije u vidljivom području, visoke adsorpcije na površini poluvodiča i velike elektrokemijske stabilnosti. Među najznačajnijim fotoaktivnim bojilima je antocijanin koji pored primjene u industriji sunčanih ćelija ima primjenu i u medicini zbog svojih ljekovitih svojstava. Antocijanin je prirodno bojilo koje se može ekstrahirati iz raznih bobičastih plodova poput crne murve i biljki poput hibiskusa.In this paper the properties, advantages and disadvantages of solar cells, dye-sensitized solar cells (DSSC) and activity of the photoactive dyes have been studied. Solar cell is a device that converts energy of light into electrical energy. DSSC solar cells belong to third generation of solar cells and have promising results compared to other solar cells. They are given great importance due to their low cost compared to other devices that work on the same principle. Cell consists of a photosensitive anode that is made of semiconducter layer of metal oxide (TiO 2 , ZnO, Sb 2 O 5 , Al 2 O 3 ) coated with a transparent conductive oxide (TCO), dye molecules adsorbed on the surface of the semiconductive metal oxide and counter electrode. The advantages over other generation of solar cells is the low cost of components, high efficiency and they are not harmful to the enviornment. Among photoactive dyes, the most commonly used dyes are ruthenium compounds due to their wide apsorption in the visible region, high adsorption on the surface of semiconductors and high electrochemical stability. Among the most important photoactive dyes is anthocyanin, which, in addition to its application in the solar cell industry, is also used in medicine due to its medical properties. Anthocyanin is a natural dye that can be extracted from a variety of berries such as black mulberries and plants such as hibiscus
Chemical composition of Cannabis sativa L. seeds essential oil : bachelor thesis
No full textSjemenke konoplje (Cannabis sativa L.) se u današnje vrijeme sve više koriste u prehrambenoj i kozmetiĉkoj industriji. Osim što su sjemenke konoplje izvor esencijalnih masnih kiselina i imaju velik udio proteina takoĊer su bogate mineralima i vitaminima. U kozmetiĉkoj industriji mogu se pronaći gelovi i razna ulja koja sadrţe ulje sjemenki konoplje upravo zato što ima mogućnost umiriti koţu lica, vidljivo smanjiti crvenilo koţe te ojaĉati zaštitnu barijeru. Eteriĉna ulja su smjese hlapljivih spojeva koja sadrţe na stotine kemijskih spojeva te njihovo djelovanje na ljudski organizam još uvijek nije u potpunosti istraţeno. Imaju mogućnost djelovanja na hormonski i ţivĉani sustav ĉovjeka te intenzivnim mirisom mogu djelovati na raspoloţenje i emocije. Prilikom analize eteriĉnih ulja, jedna od najĉešće korištenih tehnika je plinska kromatografija s masenim spektrometrom kao detektorom. Navedena tehnika omogućuje identifikaciju mnogih spojeva u sloţenim smjesama koji su prisutni i u vrlo malim koliĉinama. U ovom radu prikazana je analiza izoliranog eteriĉnog ulja sjemenki C. sativa i analiza komercijalnog ulja za lice za problematiĉnu koţu, marke Kiehl's, ĉiji je jedan od glavnih sastojaka ulje sjemenki konoplje. Navedene analize provedene su pomoću plinske kromatografije s masenim spektrometrom. Usporedbom rezultata analize dvaju ulja moţe se potvrditi da je ulje C. sativa zaista jedan od sastojaka kozmetiĉkog ulja za lice Kiehl's.Hemp seeds (Cannabis sativa L.) are increasingly used in the food and cosmetics industry today. In addition to being a source of essential fatty acids and having a high protein content, hemp seeds are also rich in minerals and vitamins. Gels and various oils containing hemp seed oil can be found in the cosmetics industry precisely because it has the ability to soothe the facial skin, visibly reduce skin redness and strengthen the protective barrier. Essential oils are mixtures containing hundreds of volatile chemical compounds and their effects on the human body have not yet been fully investigated. They have the ability to act on the human hormonal and nervous system, and with their intense scent can affect mood and emotions. Gas chromatography with mass spectrometer as a detector is one of the most commonly used techniques when analysing essential oils. This technique makes it possible to identify many compounds in complex mixtures that are present even in very small quantities. This thesis presents analysis of the C. sativa seed essential oil and the analysis of Kiehl's commercial facial oil for problematic skin. One of the main ingredients of this facial oil is hemp seed essential oil. These analyses were performed by gas chromatography with a mass spectrometer. By comparing the results of the analyses of the two oils – it was confirmed that C. sativa oil is indeed one of the ingredients of Kiehl's cosmetic face oil
Dalmatian prosciutto : bachelor thesis
No full textU ovom radu opisan je hrvatski gastronomski specijalitet, Dalmatinski pršut. Opisano je kakvu sirovinu smijemo koristiti, koje dodatke i začine smijemo upotrebljavati te pravilan slijed faza u tehnološkom procesu, što je vrlo vaţno kako bi se što bolje odvio tehnološki postupak proizvodnje. Upravo zbog svog specifičnog postupka imamo proizvod s jedinstvenim spojem mirisa, okusa i kvalitete. U radu su opisane razlike s drugim hrvatskim pršutima u tijeku proizvodnje. Zbog svog specifičnog okusa i mirisa Dalmatinski pršut zaštićen je oznakom zemljopisnog podrijetla i nadaleko je poznat.This work describes a Croatian gastronomic specialty, Dalmatian prosciutto. It is described what raw materials we may use, what additives and spices we may use and correct sequence of stages in the technological process, which is very important in order to better develop the technological process of production. One to this specific process, we have products with a unique combination of aroma, taste and quality. This work also describes the differences with other Croatian prosciutto during production. Due to its specific taste and aroma, Dalmatian prosciutto is protected by a certificate of geographical origin and is widely known
Development and optimization of electrochemical method for determination of antioxidant capacity : bachelor thesis
No full textPoznato je kako elektrode izrađene od ugljikovih materijala (grafita, staklastog ugljika, ugljikove paste ili grafena) zbog niskog omskog otpora mogu značajno poboljšati elektroanalitička svojstva osjetnih slojeva i pružaju različite mogućnosti modifikacija koje se često koriste za razvoj visoko osjetljivih senzora za istraživanje elektrokemijskih svojstava i otkrivanje raznih spojeva. Prvi cilj ovog rada bio je razviti jednostavnu elektrokemijsku metodu za određivanje vitamina C (VitC) na posebno konstruiranoj mikroelektrodi od lista pirolitičkog grafita (PGS – Pyrolytic Graphite Sheet). Ciklička voltametrija korištena je za karakterizaciju mikroelektrode i pravokutnovalna voltametrija za elektroanalitičke svrhe. Utvrđen je postupak za kvantificiranje VitC –a u realnom uzorku. VitC pokazuje jednu kvazireverzibilnu reakciju koja uključuje prijenos dva elektrona, dok potencijal oksidacije ovisi o koncentraciji analita. Pravokutnovalna voltametrija (SWV) optimizirana je i provedeno je analitičko određivanje u području potencijala od –0,30 do 0,80 V. Dobiveni rezultati pokazuju linearni odziv PGS elektrode u širokom području koncentracija. Drugi cilj bio je utvrditi učinak dodavanja različite vrste „zelenog“ biootpada na rast biljaka, sadržaj VitC –a i antioksidacijsku aktivnost u rikoli (Eruca sativa L) uporabom PGS elektrode. Dobiveni rezultati uspoređeni su sa standardiziranim metodama. Nakon tri tjedna uzgoja uočene su male razlike u rastu i velike razlike u određenim nutritivnim karakteristikama. Dodavanje ljuske kikirikija doprinosi prozračivanju tla, a primijećen je i najbrži razvoj zdrave i zelene Eruca sativa. Dodatak crne kave čini tlo blago alkalnim i rezultira značajnim povećanjem sadržaja VitC –a i antioksidacijske aktivnosti.It is known that electrodes made of carbon materials (graphite, glassy carbon, carbon paste or graphene) due to low ohmic resistance can significantly improve the electroanalytical properties of sensitive layers and provide a variety of modification options that are often used to develop highly sensitive sensors for investigation of electrochemical properties and give opportunity for detection of various compounds. The first goal of this work was to develop a simple electrochemical method for the determination of vitamin C (VitC) on a specially constructed microelectrode made from the Pyrolytic Graphite Sheet (PGS). Cyclic voltammetry was used to characterize the microelectrode and square wave voltammetry for electroanalytical purposes. A procedure for quantifying VitC in a real sample was established. VitC shows a single quasi–reversible reaction involving the transfer of two electrons, while the oxidation potential depends on the analyte concentration. SWV was optimized and analytical determination was performed in the potential range from –0.30 to 0.80 V. The obtained results show a linear response of the PGS electrode in a wide range of concentrations. The second goal was to determine the effect of adding different types of "green" biowaste on plant growth, VitC content and antioxidant activity in arugula (Eruca sativa L) using PGS electrode. The obtained results were compared with standardized methods. After three weeks of cultivation, small differences in growth and large differences in certain nutritional characteristics were observed. The addition of peanut shell contributes to soil aeration, and the fastest development of healthy and green Eruca sativa has been observed. The addition of black coffee makes the soil slightly alkaline and results in a significant increase in VitC content and antioxidant activity
Polymer packaging waste management in the Republic Croatia : bachelor thesis
No full textAmbalaža predstavlja svaki proizvod koji se upotrebljava za čuvanje i transport sirovina i gotovih proizvoda. Polimeri se zbog svojih povoljnih svojstava, lakog oblikovanja te male gustoće često koriste za izradu ambalaže. Proizvodnja polimerne ambalaže raste, a time i količina polimernog ambalažnog otpada. U 2019. godini u Republici Hrvatskoj više od 50% ambalaže završilo je na odlagalištima od čega je preko 17% plastične ambalaže. Neadekvatno odlaganje polimernog otpada zajedno sa polimernom ambalažom, predstavlja velik ekološki problem današnjice, kako u svijetu tako i u Republici Hrvatskoj. Osim štetnog utjecaja na okoliš, odlaganje ambalažnog otpada sa svojim vrijednim materijalnim i energetskim svojstvima ima negativan utjecaj na ekonomiju. Kao članica Europske unije Hrvatska je dužna ispunjavati zahtjeve i visoke standarde gospodarenja polimernim otpadom te u korisne svrhe koristiti novac iz EU fondova. Glavni cilj Europske unije jest ostvariti kružno gospodarstvo, odnosno odbačeni ambalažni otpad oporabiti te ponovno koristiti. Na taj način smanjuje se količina otpada i emisija štetnih plinova te utrošak resursa (ušteda sirovina). Kako bi se riješio problem otpada općenito, treba razviti dobar sustav gospodarenja otpadom, odnosno odvojenog prikupljanja te njegove ponovne uporabe u materijalne ili energetske svrhe. U ovome radu provedena je analiza gospodarenja polimernim ambalažnim otpadnom u Republici Hrvatskoj temeljem službeno dostupnih podataka.Packaging is any product used for storage and transport of raw materials and finished products. Polymers are often used for packaging due to their favorable properties, easy shaping and low density. The production of polymer packaging is growing, and with it the amount of polymer packaging waste. In 2019, in the Republic of Croatia, more than 50% of the packaging ended up in landfills, of which over 17% was plastic packaging. Inadequate disposal of polymer waste, together with polymer packaging, is a major environmental problem today, both in the world and in the Republic of Croatia. In addition to the harmful impact on the environment, the disposal of packaging waste with its valuable material and energy properties has a negative impact on the economy. As a member of the European Union, Croatia is obliged to meet the requirements and high standards of polymer waste management and to use money from EU funds for useful purposes. The main goal of the European Union is to achieve a circular economy, which means to recover and reuse discarded packaging waste. In this way, the amount of waste and emissions of harmful gases and the consumption of resources (the saving of raw materials) are reduced. A good waste management system should be developed in order to solve the problem of waste in general. In this paper, an analysis of polymer packaging waste management in the Republic of Croatia is performed, based on officially available data
Shell&tube exchanger, 1-2 type : bachelor thesis
No full textSvrha ovog završnog rada je istražiti da li se industrijski MIT09 izmjenjivač topline, tip 1-2, duljine cijevi 770 mm može primijeniti za hlađenje mineralnog ulja, kojim se podmazuju klizni ležajevi na srednjem bloku rotacijske peći s vanjske i unutarnje strane južnog kućišta (8) na istočnoj strani peći. Mineralno ulje temperature 40 o C, dostrujava u prostor plašta volumnim protokom od 0,8 m 3 /h na unutarnjoj te 0,36 m 3 /h na vanjskoj strani kućišta. Kroz cijevni snop struji rashladna voda volumnim protokom 1,2 m 3 /h i ulazne temperature 25,1 o C, u dva prolaza. Raspored cijevi u cijevnom snopu je u trokutu s korakom od 13 mm, a broj pregrada u plaštu je 9. Rezultati ispitivanja ukazuju da je režim strujanja u plaštu laminaran dok je strujanje vode u cijevnom snopu u prijelaznom području. Ispitivani višecijevni izmjenjivač MIT09 zadovoljava za hlađenje kliznih ležajeva rotacijske peći i na vanjskoj i na unutarnjoj strani južnog kućišta (8) budući da je potrebna površina za izmjenu topline manja u odnosu na raspoloživu površinu navedenog izmjenjivača. Ukoliko se protok ulja na vanjskoj strani poveća na 0,72 m 3 /h potrebna površina za izmjenu topline je i dalje manja u odnosu na raspoloživu površinu i navedeni izmjenjivač zadovoljava.The main purpose of this bachelor thesis is to determine whether the industrial MIT09 heat exchanger, type 1-2, pipe length 770 mm can be used for cooling mineral oil, which lubricates the plain bearings on the middle block of the rotary kiln on the outside and inside of the south basis (8) on the east side of the kiln. Mineral oil with the temperature of 40 o C flows into shell space with a volume flow 0.8 m 3 /h on the inside and 0.36 m 3 /h on the outside of the basis. Cooling water flows through the pipe bundle with the volume flow of 1.2 m 3 /h and with the inlet temperature of 25.1 o C in two passes. The arrangement of the pipes in the pipe bundle is in a triangle with a step off 13 mm with 9 baffles inside of the shell. The test of examination indicates that the flow regime in the shell is laminar while the water flow in the pipe bundle is in transition area. The examinated multi-tube heat exchanger MIT09 satisfies for cooling the sliding bearings of the rotary kiln on both the outer and inner side of the southern basis (8) since the required heat exchange area is smaller than available area of the specified exchanger. If the oil flow on the outside increases to 0.72 m 3 /h, the heat exchange required area is still smaller than the available area and the specified exchanger satisfies
Determination of the limit for the formation of triple ions in solutions of potassium and 90% butan-2-ol at 25°C : bachelor thesis
No full textU ovom radu konduktometrijskom metodom određena je granica nastajanja trostrukih iona u otopinama kalijevog bromida i 90 %-tnog butan-2-ola pri temperaturi od 25°C. Za obradu podataka korišten je kemijski model provodnosti utemeljen na jednadžbi za provodnost Fuoss-Hsia. Iz koncentracijske ovisnosti elektrolitne vodljivosti razrijeđenih otopina izračunate su granična molarna provodnost i termodinamička konstanta ravnoteže za ionsku asocijaciju te granična molarna provodnost trostrukih iona i termodinamička konstanta ravnoteže za reakciju nastajanja trostrukih iona.In this work, the limit of formation of triple ions in solutions of potassium bromide and 90% butan-2-ol at a temperature of 25° C was determined by the conductometric method. A chemical conductivity model based on the Fuoss-Hsia conductivity equation was used to process the data. From the concentration dependence of the electrolyte conductivity of dilute solutions, the limiting molar conductivity and thermodynamic equilibrium constant for ionic association and the limiting molar conductivity of triple ions and the thermodynamic equilibrium constant for the reaction of triple ion formation were calculated