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Determination of the strength of portland cement with the addition of waste building bricks : bachelor thesis
No full textU ovom radu provedeno je odreĊivanje ĉvrstoće portland cementa bez i uz dodatak otpadne graĊevinske opeke. OdreĊivanje ĉvrstoće provedeno je nakon 24 h, 48 h, 7 dana i 28 dana njegovanja u vodi pri temperaturi od 20 ⁰C, bez i uz dodatka 20 mas. % otpadne opeke te omjeru voda/cement = 0,5. Pomoću ureĊaja za odreĊivanje ĉvrstoća prvo je odreĊena savojna ĉvrstoća cementnih kompozita bez i s dodatkom otpadne graĊevinske opeke, a potom i tlaĉna ĉvrstoća. Iz dobivenih rezultata odreĊeno je maksimalno opterećenje koje je primijenjeno na uzorak kako bi došlo do njegovog loma, a na temelju ĉega se vidi jesu li prema normi HRN EN 196-1 zadovoljeni uvjeti rane i normirane ĉvrstoće. Dodatkom otpadne graĊevinske opeke utjeĉe se na ĉvrstoću cementnog morta. Dodatkom 20 mas. % otpadne opeke ne zadovoljava se uvjet rane ĉvrstoće, meĊutim zadovoljen je uvjet normirane ĉvrstoće.In this work, the strength of Portland cement was determined without and with the addition of waste building bricks. Determination of strength was carried out after 24 h, 48 h, 7 days and 28 days of curin in water at a temperature of 20 ⁰C, without or with the addition of 20 wt. % waste bricks and water/cement ratio = 0.5. The strength determination device is used to first determine the flexural strength of cement composites without and with the addition of waste building bricks, and then the compressive strength. From the obtained results, the maximum load that was applied to the sample in order to cause it`s breakage was determined, based on which it can be seen whether the early and standardized strength conditions are met according to the standard HRN EN 196-1. The addition of waste building bricks affects the strength of the cement mortar. With the addition of 20 wt. % waste bricks doesn´t meet the condition of early strength, however the condition of standardized strength is met
MS-dial in metabolomics : bachelor thesis
No full textMS-DIAL je softver razvijen 2015. godine za analizu podataka masene spektrometrije, posebno u identifikaciji i kvantifikaciji metabolita i lipida. Koristi se za analizu složenih bioloških uzoraka poput krvi, urina i tkiva, primjenom GC-MS, LC-MS i MS/MS tehnika. Kroz dekonvoluciju spektra, softver omogućuje razlikovanje preklapajućih ionskih signala i točnu identifikaciju spojeva. Integrira se s bazama podataka poput MassBanka, što olakšava usporedbu i identifikaciju metabolita. Također, MS-DIAL podržava relativnu i apsolutnu kvantifikaciju spojeva, omogućujući točne mjere koncentracija. Njegova vizualizacija podataka, automatizacija analiza i fleksibilnost doprinijeli su širokoj primjeni u biomedicinskim istraživanjima, metabolomici i znanosti o okolišu. Značajna nadogradnja softvera kroz godine uključuje otvoreni kod i napredne algoritme, čime su omogućeni daljnji razvoj i prilagodbe. MS- DIAL je postao ključan alat u istraživanjima povezanima s bolestima poput dijabetesa i kardiovaskularnih bolesti, te je znatno unaprijedio analizu lipidoma i metaboloma.MS-DIAL is software developed in 2015 for mass spectrometry data analysis, specifically for the identification and quantification of metabolites and lipids. It is used for analyzing complex biological samples like blood, urine, and tissue, employing GC-MS, LC-MS, and MS/MS techniques. Through spectral deconvolution, the software enables distinguishing overlapping ion signals and accurate compound identification. It integrates with databases like MassBank, facilitating comparison and identification of metabolites. Additionally, MS-DIAL supports both relative and absolute quantification of compounds, allowing precise concentration measurements. Its data visualization, automation of analyses, and flexibility have contributed to its widespread use in biomedical research, metabolomics, and environmental science. Significant software upgrades over the years include open-source code and advanced algorithms, enabling further development and customization. MS-DIAL has become a key tool in research related to diseases like diabetes and cardiovascular conditions, significantly advancing lipidomics and metabolomics analysis
INFLUENCE OF SEAWATER SALINITY ON THE CORROSION BEHAVIOR OF COPPER : diploma thesis
No full textU radu je ispitano korozijsko ponašanje bakra u morskim vodama različitog saliniteta tj. bočatoj, morskoj i gorkoj morskoj vodi pri temperaturama 15 °C, 25 °C i 35 °C. Ispitivanja su provedena pod utjecajem gibanja elektrolita koji simulira prirodno kretanje vode pri svim temperaturama. Provedena su elektrokemijska ispitivanja mjerenja potencijala otvorenog strujnog kruga u trajanju od 45 min, te mjerenja linearne i potenciodinamičke polarizacije. Ispitivanja su pokazala da porast temperature kod sva tri prisutna elektrolita ima značajan utjecaj na porast gustoće korozijske struje i smanjenje vrijednosti polarizacijskog otpora, dok je utjecaj na vrijednost korozijskog potencijala gotovo zanemariv. Smanjenje vrijednosti polarizacijskog otpora uzrokuje veću koroziju bakra, a najniže vrijednosti polarizacijskog otpora dobivene su u gorkoj morskoj vodi pri temperaturi 35 °C. Analiza površine uzoraka nakon elektrokemijskih ispitivanja optičkom mikroskopijom i optičkom profilometrijom, potvrdile su rezultate elektrokemijskih mjerenja. SEM/EDS analizom određena je mikrostruktura i elementarni sastav korozijskih produkata na površini uzoraka.The corrosion behavior of copper in seawater with different salinity, i.e. brackish water, seawater and seawater bittern at temperatures of 15 °C, 25 °C and 35 °C, was investigated. The tests were carried out under the influence of the movement of the electrolyte at all temperatures, simulating the natural movement of water. Electrochemical tests were carried out, measuring the open circuit potential over a period of 45 minutes as well as the linear and potentiodynamic polarization. The tests showed that for all three electrolytes present, an increasing in the temperature has a significant effect on the increase in the corrosion current density and the decrease in the value of the polarization resistance, while the effect on the value of the corrosion potential is almost negligible. A decrease in polarization resistance leads to a stronger corrosion of copper, and the lowest polarization resistance values were obtained at a temperature of 35 °C in seawater bittern. The analysis of the surface of the samples after the electrochemical tests using optical microscopy and optical profilometry confirmed the results of the electrochemical measurements. The microstructure and elemental composition of the corrosion products on the surface of the samples were determined by SEM/EDS analysis
Influence of the seed mass with a size of L=82,5 um on the properties of potassium sulphate crystals in the seeded crystallization : diploma thesis
No full textCilj rada je bio sagledati utjecaj mase cjepiva, definirane veličine na karakteristike kristala dobivenih procesom cijepljene kristalizacije. Ispitivanje se provodilo u kristalizatoru s razbijalima virova i radijalnim miješalom čija je brzina vrtnje iznosila N =300 o. min -1 . Matična otopina, zasićena pri 30 °C, hladila se linearno do 15 °C. U prvom dijelu rada provedena je necijepljena šaržna kristalizacija s ciljem određivanja širine metastabilne zone te granulometrijskih svojstava produkta kako bi se definirali uvjeti provedbe cijepljene kristalizacije. Kao cjepivo su korišteni kristali kalijevog sulfata prosječne veličine 82,5 μm pri četiri različite mase koje su iznosile od 2 do 5 % teorijskog prinosa kristala. Tijekom provedbe kristalizacije periodično je uzorkovana suspenzija kristala koja je granulometrijski analizirana metodom laserske difrakcije. S ciljem detaljnog sagledavanja utjecaja cjepiva na rast kristala sagledane su funkcijom gustoće raspodjele tijekom procesa hlađenja te promjene srednje veličine rastućih kristala kao i promjene koncentracije matične otopine. Po završetku procesa kristalizacije, produkt je granulometrijski analiziran te s obzirom na najveći volumni promjer i najmanju standardnu devijaciju kristala dobivenih pri korištenju cjepiva najveće mase, masa cjepiva m 4 smatra se najpovoljnijom.In this study, seeded crystallization of potassium sulphate was carried out using a controlled cooling method. The aim of the study was to investiage the influence of the seed mass, defined by its size, on the properties of the crystals obtained in this process. The experiment was conducted in a crystallizer equipped with baffles and a radial impeller, rotating at a speed of N =300 rpm. The mother liquor, saturated at 30 °C, was cooled linearly to 15 °C. In the first part of the study, an unseeded batch crystallization was carried out to determine the width of the metastable zone and the granulometric properties of the product in order to define the conditions for seeded crystallization. Potassium sulphate crystals with an average size of 82,5 μm were used as seed material, with four different seed masses ranging from 2 to 5 % of the theoretical crystallization yield. During crystallization, crystal suspension samples were periodically withdrawn and subjected to granulometric analysis using laser diffraction. In order to gain a detailed insight into the influence of the seed on crystal growth, the changes in the particle size distribution function during the cooling process as well as the changes in the mean crystal size and the concentration of the mother liquor were monitored. After completion of the crystallization process, a granulometric analysis of the final product was performed. Based on the largest mean volume diameter and the lowest standard deviation of the crystals obtained with the highest seed mass, the seed mass m 4 was considered the most favorable
ANALYSIS OF THE VOLATILE COMPOUNDS OF HALOPHYTES FROM THE PANTAN RESERVE AREA : diploma thesis
No full textHalofiti su biljke koje, za razliku od većine poznate flore, mogu preživjeti, rasti i razmnožavati se na slanim područjima s ekstremnim uvjetima. Preživljavanje nepovoljnih uvjeta omogućuju im razne strukturne i biokemijske adaptacije ovisne o pojedinoj vrsti, području, vrsti staništa itd. U ovom radu izolirani su i identificirani hlapljivi spojevi, sastavnice ekstrakata različitih halofitnih vrsta sakupljenih u području rezervata Pantan kod Trogira. Eterična ulja su izolirana hidrodestilacijom u aparaturi po Clevengeru, dok su hlapljivi spojevi hidrolata, zaostali nakon izolacije eteričnog ulja, ekstrahirani mikroekstrakcijom na čvrstoj fazi (SPME). Izolirani hlapljivi spojevi su identificirani vezanim sustavom plinska kromatografija-spektrometrija masa (GC-MS). Najzastupljenije komponente eteričnog ulja biljke Limonium narbonense su cis-2-heksenol (12,5%), nonakozan (11,3%) i heptakozan (10,6%), dok se u hidrolatu ističu cis-2-heksenol (16,5%), kamfor (15,2%) i α-tujon (14,9%). Najzastupljenije komponente eteričnog ulja biljke Artemisia caerulescens su kamfor (41,6%) i α-tujon (34,2%), dok je najzastupljenija komponenta hidrolata kamfor (52,1%). Najzastupljenija komponenta i eteričnog ulja i hidrolata biljke Halimione portulacoides je kamfor (63,6 i 69,6%). Najzastupljenije komponente eteričnog ulja biljke Glaucium flavum su pentakozan (21,3%), trikozan (14,4%) i p-vinil-gvajakol (13,9%), dok su najzastupljenije komponente hidrolata 10-(acetil- metil)-3-karen (23,4%), (E)-3-heksen-1-ol (20,6%) te p-vinil-gvajakol (17,9%). Najzastupljenije komponente eteričnog ulja biljke Inula crithmoides su p-cimen (29,3%), δ-8,9-dehidrotimol-metil-eter (19,0%) i p-cimen-7-ol (11,2%), dok su najzastupljenije komponente hidrolata timil-2-metil-butanoat (21,8%) i p-cimen-7-ol (18,9%). Identifikacija hlapljivih spojeva ovih biljnih ekstrakata doprinosi boljem razumijevanju kemijskog sastava, kao i potencijala svake od biljnih vrsta u farmaceutskom, kozmetičkom ili prehrambenom smislu.Halophytes are plants that, unlike most flora, can survive, grow, and reproduce in saline areas with extreme conditions. Their survival in adverse environments is enabled by structural and biochemical adaptations, varying by species, region, and habitat type. In this study, volatile compounds from extracts of halophyte species collected in the Pantan reserve near Trogir were isolated and identified. Essential oils were extracted by hydrodistillation using a Clevenger apparatus, while volatile compounds from hydrosols, left after essential oil extraction, were obtained by solid-phase microextraction (SPME). The isolated volatile compounds were identified via gas chromatography-mass spectrometry (GC-MS). The most abundant components of Limonium narbonense essential oil are cis-2-hexenol (12.5%), nonacosane (11.3%), and heptacosane (10.6%), while the hydrosol contains cis-2-hexenol (16.5%), camphor (15.2%), and α-thujone (14.9%). Artemisia caerulescens contains camphor (41.6%) and α-thujone (34.2%) in essential oil and camphor (52.1%) in the hydrosol. In Halimione portulacoides, camphor dominates both the essential oil (63.6%) and hydrosol (69.6%). Glaucium flavum essential oil contains pentacosane (21.3%), tricosane (14.4%), and p-vinyl-guaiacol (13.9%), while its hydrosol has 10- (acetylmethyl)-3-carene (23.4%), (E)-3-hexen-1-ol (20.6%), and p-vinyl-guaiacol (17.9%). Inula crithmoides essential oil contains p-cymene (29.3%), δ-8,9-dehydrothymol-methyl-ether (19.0%), and p- cymene-7-ol (11.2%), while its hydrosol contains thymyl-2-methyl-butanoate (21.8%) and p-cymene-7-ol (18.9%). Identifying volatile compounds in these plant extracts helps better understand their chemical composition and potential applications in pharmaceutical, cosmetic, or nutritional terms
ANTIOXIDANT CARACTERISATION OF SPICES AND AUTOCHTONIC DALMATIAN SPECIES BY ELECTROCHEMICAL AND SPECTROPHOTOMETRIC METHODS : diploma thesis
No full textKao doprinos u proučavanju oksidacije galne kiseline na ugljikovim materijalima izrađeno je pet elektroda: elektroda od staklastog ugljika, elektroda modificirana jednozidnim ugljikovim nanocjevčicama, te tri elektrode od ugljikovih mikrovlakana različite površine. Ovisnost vršne struje o pH ispitana je cikličkom voltametrijom u fosfatnom puferu sa i bez prisutne galne kiseline. Kao najjednostavniji i najosjetljiviji elektrokemijski senzor izdvojila se elektroda s jednozidnim ugljikovim nanocjevčicama, odnosno modificirana elektroda od staklastog ugljika (SWCNT/GCE). Svojevrsni senzor pripremljen je za izravno određivanje ukupnog sadržaja fenola kao ekvivalenta galne kiseline. Radna elektroda karakterizirana je voltametrijom s pravokutnim signalom pobude. Rezultati otkrivaju da SWCNT/GCE senzor može značajno poboljšati oksidacijski signal kao i pomaknuti vršne potencijale prema manje pozitivnim vrijednostima. Koristeći optimizirane uvjete, senzor je dao izuzetan linearni odziv u cijelom rasponu koncentracije; ΔI=0,280×c, (osjetljivost 0,280 μAmol -1 dm 3 ), od 2×10 -7 do 1×10 -4 mol dm -3 , s granicom detekcije od 1×10 -7 mol dm -3 . Konstruirani senzor pokazuje dobru stabilnost i ponovljivost. Za validaciju predložene metode priređeni su vodeni ekstrakti mikrovalnom ekstrakcijom lavande, smilja, kadulje, muškatnog oraščića, cimeta i klinčića. Svim uzorcima su spektrofotometrijski određeni ukupni fenoli Folin–Ciocalteu metodom i antioksidacijski kapacitet FRAP metodom. SWCNT/GCE je također primijenjena za određivanje galne kiseline kao ekvivalenta ukupnih fenola i procjenu antioksidacijskog kapaciteta. Sa SWCNT elektrodom pri pH3 nađena je najveća koncentracija GK u uzorku klinčića, 60,25 μmol dm -3 , a Folin-Ciocelteu metodom određeni su ukupni fenoli čija je najveća vrijednost izmjerene apsorbancije u klinčiću i iznosi 1328,74 mg GAE dm -3 . Dobiveni rezultati FC/SWV su pokazali izuzetno dobro slaganje predložene i standardne procjene ukupnih fenola, te ukazuju na mogućnost korištenja ovakve metodologije za procjenu ukupnih fenola u realnim uzorcima kao standardne metode. FRAP metodom najveći antiooksidacijski kapacitet posjeduje klinčić, 26687,70 μM. Omjer FRAP/SWV govori kako predložena metoda nije pogodna za procjenu antioksidacijskog kapaciteta.As a contribution to the study of gallic acid oxidation on carbon materials, five electrodes were fabricated: a glassy carbon electrode, an electrode modified with single-walled carbon nanotubes, and three electrodes made of carbon microfibers of different surface areas. The dependence of the peak current on pH was examined by cyclic voltammetry in phosphate buffer with and without gallic acid present. The electrode with single-walled carbon nanotubes, or modified glassy carbon electrode (SWCNT/GCE), was selected as the simplest and most sensitive electrochemical sensor. A unique sensor was prepared for the direct determination of the total phenol content as gallic acid equivalent. The working electrode was characterized by voltammetry with a rectangular excitation signal. The results reveal that the SWCNT/GCE sensor can significantly improve the oxidation signal as well as shift the peak potentials towards less positive values. Using optimized conditions, the sensor gave an exceptional linear response over the entire concentration range; ΔI=0.280×c, (sensitivity 0.280 μAmol -1 dm 3 ), from 2×10 -7 to 1×10 -4 mol dm -3 , with a detection limit of 1×10 -7 mol dm -3 . The constructed sensor shows good stability and repeatability. To validate the proposed method, aqueous extracts of lavender, immortelle, sage, nutmeg, cinnamon and cloves were prepared by microwave extraction. Total phenols were determined spectrophotometrically by the Folin–Ciocalteu method and antioxidant capacity by the FRAP method for all samples. SWCNT/GCE was also applied to determine gallic acid as an equivalent of total phenols and to estimate antioxidant capacity. With the SWCNT electrode at pH3, the highest concentration of GK was found in the clove sample, 60.25 μmol dm -3 , and the Folin-Ciocelteu method was used to determine total phenols, the highest value of the measured absorbance in cloves being 1328.74 mg GAE dm -3 . The obtained FC/SWV results showed an extremely good agreement between the proposed and standard estimates of total phenols, and indicate the possibility of using such a methodology for estimating total phenols in real samples as a standard method. By the FRAP method, cloves have the highest antioxidant capacity, 26687.70 μM. The FRAP/SWV ratio indicates that the proposed method is not suitable for estimating antioxidant capacity
ISOLATION AND IDENTIFICATION OF VOLATILE COMPOUNDS OF LILAC FLOWER (SYRINGA MEYERI PALIBIN) : bachelor thesis
No full textMeyerov jorgovan, Syringa meyeri Palibin, Oleaceae, je ukrasna biljka sa cvjetovima intenzivnog i opojnog mirisa. Kako miris potječe od hlapljivih spojeva, cilj ovog rada bio je izolirati i identificirati hlapljive spojeve cvijeta jorgovana. Za izolaciju je odabrana tehnika ekstrakcije koja je pogodna upravo za uzorke intenzivnih mirisa poput cvijeća - mikroekstrakcija vršnih para na čvrstoj fazi. Mikroekstrakcija vršnih para na čvrstoj fazi (HS-SPME) iz svježeg i smrznutog biljnog materijala provedena je korištenjem plavog (CAR/PDMS) i sivog vlakna (DVB/CAR/PDMS) pri temperaturi od 50 °C i 60 °C. Analiza vršnih para provedena je spregnutim sustavom plinska kromatografija – spektrometrija masa (GC-MS). Kvalitativni i kvantitativni sastav vršnih para cvijeta jorgovana je sličan bez obzira na biljni materijal (svježi ili smrznuti), upotrijebljeno vlakno (plavo ili sivo) i temperaturu ekstrakcije (50 °C ili 60 °C), tj. glavni sastojci su većinom isti spojevi. Glavni hlapljivi spoj cvijeta jorgovana je seskviterpenski ugljikovodik (E,E)- α-farnezen. Rezultati dobiveni u ovom radu potvrđuju da profil hlapljivih spojeva izoliranih tehnikom mikroekstrakcije vršnih para na čvrstoj fazi najviše ovisi o vrsti korištenog vlakna te o parametrima ekstrakcije, kao što je temperatura. Sivo vlakno učinkovitije je za izolaciju hlapljivih spojeva iz cvjetova jorgovana bez obzira na temperaturu pri kojoj se provodi ekstrakcija i bez obzira je li za izolaciju korišten svježi ili smrznuti biljni materijal. Nadalje, pri višoj temperaturi bez obzira na upotrijebljeno vlakno izolirano je i identificirano više spojeva. Dakle, mikroekstrakcijom vršnih para na čvrstoj fazi korištenjem sivog vlakna i pri temperaturi od 60 °C dobiven je potpuniji profil hlapljivih spojeva cvijeta jorgovana.The Meyer lilac, Syringa meyeri Palibin, Oleaceae, is an ornamental plant with flowers of an intense and intoxicating fragrance. Since the scent is a result of volatile compounds, the main goal of this study was to isolate and identify the volatile compounds of lilac flowers. The extraction technique selected was headspace solid-phase microextraction (HS-SPME), which is particularly suitable for samples with strong aromas like flowers. Headspace solid-phase microextraction (HS-SPME) from fresh and frozen plant material was performed using blue (CAR/PDMS) and gray fibers (DVB/CAR/PDMS) at temperatures of 50 °C and 60 °C. The headspace analysis was performed using coupled system gas chromatography-mass spectrometry (GC- MS). The qualitative and quantitative composition of the lilac flower headspace was similar regardless of the plant material (fresh or frozen), the fiber used (blue or gray), and the extraction temperature (50 °C or 60 °C), meaning that the main components were largely the same compounds. The primary volatile compound of the lilac flower was the sesquiterpene hydrocarbon (E,E)-α-farnesene. The results obtained in this study confirm that the profile of volatile compounds isolated using headspace solid-phase microextraction is primarily dependent on the type of fiber used and extraction parameters such as temperature. The gray fiber was more efficient for isolating volatile compounds from lilac flowers, regardless of the temperature at which the extraction was performed and whether fresh or frozen plant material was used for isolation. Furthermore, a higher temperature resulted in the isolation and identification of more compounds, regardless of the fiber used. Therefore, Headspace Solid - Phase Microextraction using the gray fiber and at a temperature of 60 °C extracted a more complete profile of the lilac flower's volatile compounds
Gasses in the air in the Dubrovnik area : bachelor thesis
No full textOnečišćenje zraka koje je uzrokovano emisijama štetnih plinova iz prometa, industrije i drugih izvora, negativno utječe na zdravlje ljudi i okoliš. Na području grada Dubrovnika, tijekom turističke sezone, povećan broj vozila i turističkih plovila, značajno pridonosi povećanju koncentracije onečišćivala u zraku poput, ugljikovog (IV) oksida (CO 2 ) i dušikovog (IV) oksida (NO 2 ) što predstavlja izazov za očuvanje kvalitete zraka u ovom povijesnom gradu. Pomoću uređaja Dräger X‑am® 8000 nastojale su se izmjeriti koncentracije plinova prisutnih na pojedinim lokacijama u gradu Dubrovniku. Bitan utjecaj na vrijednosti mjerenja ima lokacija mjerenja, meteorološki parametri te period godine. Najveća vrijednost koncentracije CO 2 , u iznosu 800 ppm, očitana je na dvije mjerne postaje visoke prometne opterećenosti (Luka Gruž i Ilijina glavica) u mjesecu kolovozu, dok je srednja vrijednost koncentracija CO 2 na svim mjernim postajama u rasponu od 0,0415 vol% do 0,060 vol% ppm. Provedenim mjerenjima koncentracija NO 2 nije detektirana do ožujka, a najveća koncentracija zabilježena je u kolovozu (0,06 ppm). Osim navedenih plinova, zamijećena je prisutnost ugljikovog (II) oksida (CO) u kolovozu s najvećom vrijednosti u iznosu 3 ppm što se može pripisati nepotpunom sagorijevanju goriva iz prometa koji je tada bilo najfrekventniji. Vrijednosti kisika (O 2 ) su prisutne u zadovoljavajućim vrijednostima, a najveća vrijednost postignuta je u prigradskom dijelu grada Dubrovnika (Stara Mokošica) u iznosu 21,6 vol%, lokacija je prometno izolirana zbog čega nema očitanih mjerenja za NO 2 i CO.Air pollution caused by the emission of harmful gases from traffic, industry and other sources has a negative impact on human health and the environment. In the city of Dubrovnik, the increased number of vehicles and tourist ships during the tourist season contributes significantly to higher concentrations of air pollutants such as carbon dioxide (CO₂) and nitrogen dioxide (NO₂), which poses a challenge to maintaining air quality in this historic city. The Dräger X‑am® 8000 device was used to measure gas concentrations at specific locations in Dubrovnik. The measurement location, the meteorological parameters and the time of year have a significant influence on the measured values. The highest CO₂ concentration of 800 ppm was measured at two busy measuring stations (Gruž Harbour and Ilijina Glavica) in August, while the average CO₂ concentration at all measuring stations was between 0,0415 Vol% and 0,060 Vol%. NO₂ concentrations were only detected in March, with the highest concentration measured in August (0.06 ppm). In addition to these gases, carbon monoxide (CO) was detected in August with a peak value of 3 ppm, which is probably due to the incomplete combustion of fuel due to the heavy traffic at that time. Oxygen (O₂) levels were satisfactory, with the highest value measured in the suburb of Dubrovnik (Stara Mokošica) at 21,6 Vol%, a location that is cut off from traffic and therefore has no NO₂ or CO levels
Green syntesis of colloidal silver : bachelor thesis
No full textU ovom radu opisane su različite metode sinteze koloidnog srebra. Posebni naglasak stavljen je na zelenu sintezu različitim prirodnim reducensima. Zelena sinteza odnosi se na metode kemijske sinteze koje koriste ekološki prihvatljive postupke i materijale. Cilj je smanjiti ili eliminirati upotrebu i stvaranje opasnih tvari, te zamijeniti neobnovljive izvore obnovljivim materijalima. Zelena sinteza se primjenjuje u raznim područjima, uključujući proizvodnju lijekova, materijala i nanotehnologiju. Nanočestice srebra imaju širok spektar primjena zbog svojih jedinstvenih svojstava. Neke od primjena su u: medicini, pročišćavanju vode, tekstilnoj industriji, elektronici, katalizi itd. Zbog široke primjene nanočestica srebra, njihov utjecaj na okoliš iz godine u godinu je zabrinjavajući zbog upotrebe različitih sirovina i kemikalija pri sintezi, koje su skupe, toksične i opasne po okoliš. Stoga je zadnjih godina zelena sinteza sve više zastupljena jer je ekološki prihvatljivija i isplativija, odnosno manji su troškovi proizvodnje, manja potrošnja energije i smanjena ili potpuno uklonjena uporaba toksičnih kemikalija. Toksične kemikalije zamijenjene su s prirodnim tvarima iz okoliša koje su lako dostupne, kao što su biljni ekstrakti te mikroorganizmi.This paper describes various methods of synthesising colloidal silver. Particular emphasis is placed on green synthesis using various natural reducing agents. Green synthesis refers to methods of chemical synthesis that use environmentally friendly processes and materials. The aim is to reduce or eliminate the use and production of hazardous substances and to replace non-renewable sources with renewable materials. Green synthesis is used in a variety of areas, including the production of medicines, materials and nanotechnology. Silver nanoparticles have a wide range of applications due to their unique properties. Some of the applications are: Medicine, water purification, textile industry, electronics, catalysis, etc. Due to the wide application of silver nanoparticles, the impact on the environment is a concern from year to year as the synthesis uses various raw materials and chemicals that are expensive, toxic and hazardous to the environment. In recent years, green synthesis has therefore become increasingly popular because it is more environmentally friendly and profitable, i.e. lower production costs, lower energy consumption and reduced or complete elimination of toxic chemicals. Toxic chemicals have been replaced by natural substances from the environment that are readily available, such as plant extracts and microorganisms
Microwave-assisted isolation and GC-MS analysis of sea fennel volatiles from Korčula (Crithmum maritimum) : bachelor thesis
No full textMotar (Crithmum maritimum L.) je specifična halofitna biljka mediteranskog podneblja. Svojom fiziološkom i morfološkom strukturom prilagođena je životu u ekstremnim uvjetima visokog saliniteta, snažnih vjetrova te dugih sušnih razdoblja. Ističe se svojim aromatičnim okusom i bogatom nutritivnom vrijednošću, a njegova upotreba datira još iz prošlosti, posebno u prehrani, kozmetici i tradicionalnoj medicini. U ovom radu izolirani su hlapljivi spojevi iz svježeg motra koristeći moderne metode izolacije potpomognute mikrovalovima: mikrovalnom destilacijom (MD) te mikrovalnom hidrodifuzijom i gravitacijom (MHG). Uzorci motra, prikupljeni na području otoka Korčule, izloženi su mikrovalovima uz optimizaciju ključnih parametara- temperature, snage mikrovalova i trajanja procesa. GC-MS analizom izoliranih hlapljivih spojeva identificirano je 27 različitih spojeva od kojih su najzastupljeniji terpeni: limonen, sabinen, γ-terpinen i terpinen-4-ol. Analizirani su spektri masa pojedinih spojeva te su izračunati prinosi eteričnih ulja po gramu biljnog materijala. Rezultati su ukazali na bolje iskorištenje izolacije mikrovalnom hidrodifuzijom i gravitacijom (2,72 %) u odnosu na mikrovalnu destilaciju (0,37 %).Sea fennel (Crithmum maritimum L.) is a specific halophytic plant in Mediterranean. By its physiological and morphological structure it is adapted to life in extreme conditions of high salinity, strong winds and long dry periods. It excels in its aromatic taste and rich nutritive value and its use dates back in past, especially in diet, cosmetics and traditional medicine. In this thesis, compounds from fresh sea fennel were isolated using modern techniques of isolation assisted by microwaves; microwave distillation (MD), microwave hydrodiffusion and gravity (MHG). Sea fennel samples, collected on the island of Korčula, were exposed to microwaves with the control of crucial parameters- temperature, microwave power, and process duration. GC-MS analysis of isolated volatile compounds reviled the presence of 27 different compounds, among which the most abundant were terpenes: limonen, sabinen, γ-terpinen and terpinen-4-ol. Certain compounds' mass spectra were analyzed and yield of volatile compounds per gram of plant material was calculated. The results indicate better utilization of isolation done by using microwave hydrodiffusion and gravity (2.72 %) compared to microwave distillation (0.37 %)