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Volatile compounds of Salvia sclarea L. : bachelor thesis
No full textMuškatna kadulja (Salvia sclarea L.) je biljka iz porodice usnača (Lamiaceae) koja prirodno raste oko Mediteranskog mora, na području južne Europe i sjeverne Afrike, i u srednjoj Aziji. Cilj ovog rada bio je odrediti profil hlapljivih spojeva muškatne kadulje, i to odvojeno cvjetova, a odvojeno cijele biljke, odnosno odrediti sastav i sadržaj ovih spojeva. Radi što potpunijeg uvida u sastav i sadržaj hlapljivih spojeva za njihovu izolaciju su korištene dvije metode: hidrodestilacija i ekstrakcija vršnih para na čvrstoj fazi. Analiza uzoraka provedena je vezanim sustavom plinska kromatografija-spektrometrija masa (GC/MS). Terpenski spojevi su kvalitativno i kvantitativno najvažniji sastojci eteričnih ulja i vršnih para izoliranih iz cvjetova i biljke muškatne kadulje. Glavni spojevi u oba eterična ulja, izolirana iz biljke i iz cvjetova, su oksidirani monoterpeni linalil-acetat (27,4-30,6%) i linalol (18,2-19,1%). Glavni spojevi vršnih para su linalil-acetat (54,9%) i seskviterpen germakren D (19,7%) u uzorku izoliranom iz cijele biljke, odnosno linalil-acetat (76,6%) i linalol (6,1%) u uzorku izoliranom iz cvjetova.Clary sage (Salvia sclarea L.) is a plant from Lamiaceae family that naturally grows around the Mediterranean Sea, in southern Europe and northern Africa and in central Asia. The aim of this study was to determine the chemical profile of clary sage volatile compounds, from flowers and whole plant separately, and determine the composition and content of these compounds. For more complete insight into the composition and content of volatile compounds two isolation methods were used: hydrodistillation and headspace solid-phase microextraction (HS-SPME). Analysis of volatile samples was carried out by gas chromatography-mass spectrometry (GC/MS). Terpenes are qualitatively and quantitatively the most important ingredients of essential oils and headspaces obtained from clary sage flowers and whole plant. The major constituents of both essential oils, obtained from whole plant and from flowers, were oxygenated monoterpenes linalyl acetate (27,4-30,6%) and linalool (18,2-19,1%). The major constituents of headspaces were linalyl acetate (54,9%) and sesquiterpene germacrene D (19,7%) in sample obtained from whole plant, and linalyl acetate (76,6%) and linalool (6,1%) in sample obtained from flowers
Overview of techniques for preparation and application of magnetic colloid suspension of iron oxide - ferrofluid : bachelor thesis
No full textFerrofluidi su koloidne suspenzije magnetnih nanočestica u tekućem mediju koje reagiraju na primijenjeno vanjsko magnetsko polje. Magnetne čestice se lako mogu slijepiti jedna s drugom što se sprječava korištenjem surfaktanata koji oko čestica stvaraju nabijene slojeve koji se onda međusobno odbijaju, tj. kada čestice dođu vrlo blizu jedna drugoj, neće doći do njihove aglomeracije nego će se istovrsni naboji odbiti. Korištenjem surfaktanata se osigurava proizvodnja stabilnih suspenzija. Kao magnetne čestice najčešće se koriste željezovi (ΙΙΙ) oksidi (Fe 3 O 4 ) odnosno magnetit. Ove metalne čestice se lako proizvode i imaju visoko magnetsko zasićenje. Zbog dobre reakcije na magnetsko polje, ferrofluidi se koriste u različitim područjima. Služe kao brtve, pomažu ciljanu aplikaciju lijekova u organizmu bez velikih nuspojava, smanjuju neželjene vibracije i zagrijavanje u snažnim zvučnicima. U ovom radu su opisane tehnike priprave i aplikacije ferrofluida.Ferrofluids are colloidal suspensions of magnetic nanoparticles in a liquid carrier that react to an external magnetic field. Due to their small dimensions, magnetic nanoparticles can agglomerate easily and this can be prevented by the use of surfactants. Surfactants form a charged layer around nanoparticles and two same charged layers repulse each other. The use of surfactants ensures the production of stable ferrofluids. The most commonly used magnetic nanoparticles are iron (ΙΙΙ) oxides, Fe 3 O 4 (magnetite), due to their easy production and high magnetic saturation. Ferrofluids are widely used because of their great reaction to an external magnetic field. They act as seals in rotating shafts, help in targeted drug delivery in the organism while minimizing side effects, reduce unwanted vibrations and heating in loud speakers. Methods for the production and application of ferrofluids are described in this paper
Poly(ethilene oxide) based polymer electrolyte : doctoral thesis
No full textSažetak U ovom radu provedeno je sustavno istraţivanje strukture i toplinskih svojstava nanokompozita na bazi poli(etilen-oksida) (PEO) u svrhu dizajniranja nanokompozitnog polimernog elektrolita poboljšane ionske provodnosti. Pripravljeni su nanokompoziti PEO-a s razliĉitim nanopunilima (natrijev montmorilonit-NaMMT, komercijalno dostupni organski modificirani montmoriloniti Cloisite 10A, Cloisite 15A, Cloisite 20A, Cloisite 25A, Cloisite 93A i Cloisite 30B) metodom interkalacije iz taljevine. Uloga nanopunila je sniţavanje kristalnosti i povećanje udjela amorfne faze polimerne matrice u svrhu poboljšanja prijenosa kationa i ionske provodnosti, a da se pritom ne pogoršavaju ostala svojstva. Na osnovi rezultata provedene strukturne i toplinske karakterizacije izvršena je procjena najpovoljnijeg sustava nanokompozita polimera i nanopunila u koji je naknadno uveden Li + ion. Rezultati analize raspršenja X-zraka pri malom kutu (SAXS) pokazali su da kod svih ispitivanih uzoraka dolazi do interkalacije PEO-a u meĊuslojni prostor montmorilonita, ĉime je potvrĊen nastanak nanokompozitne strukture. Analiza spektara infracrvene spektroskopije s Fourierovom transformacijom (FTIR) svih ispitivanih nanokompozita ukazuje na postojanje interakcija izmeĊu PEO-a i punila. Narušavanje helikoidalne konformacije PEO-a, tj. smanjenje kristalne faze dodatno potvrĊuju nastanak interkalirane strukture. Primjenom diferencijalne pretraţne kalorimetrije (DSC) ispitan je utjecaj nanopunila na toplinske prijelaze (staklište, talište, kristalište) i kristalnost PEO-a. Naizraţeniji utjecaj na sniţavanje stupnja kristalnosti PEO-a u nanokompozitima pokazao je NaMMT. Organski modificirani montmoriloniti pri niţim udjelima punila djeluju kao centri nukleacije koji posljediĉno povećavaju stupanj kristalnosti PEO-a. Analiza dinamiĉke termogravimetrije (TG) pokazala je da NaMMT poboljšava toplinsku postojanost PEO-a do odreĊenog udjela. Organski modificirani montmoriloniti pri udjelima većim od 10 mas. % znaĉajno sniţavaju temperaturu poĉetka razgradnje PEO-a. Najizraţeniji negativni utjecaj uoĉen je u nanokompozitima s Cloisite 10A gdje se temperature poĉetka razgradnje sniţavaju i do 198 °C u odnosu na one ĉistog PEO-a. Rezultati karakterizacije s aspekta odgovarajućih toplinskih i strukturnih svojstava nanokompozita ukazali su na najveći potencijal NaMMT-a kao nanopunila. UvoĊenje litijevog iona u sustav provedeno je modifikacijom NaMMT-a metodom ionske izmjene s LiCl ĉime je dobiven LiMMT. Prouĉavan je utjecaj LiMMT-a i molekulne mase PEO- a na strukturna i toplinska svojstva nanokompozita PEO/LiMMT te je ispitana meĊuovisnost dobivenih rezultata i ionske provodnosti. SAXS i FTIR analiza potvrdile su nastanak nanostrukture kod svih pripravljenih nanokompozita PEO/LiMMT. Rezultati FTIR analize ukazali su na znaĉajniju interkaciju Li + iona s polimernom matricom u nanokompozitima pripravljenim s PEO- om visoke molekulne mase u odnosu na one pripravljene s PEO-om niske molekulne mase. Primjenom DSC analize utvrĊeno je da dodatak LiMMT znaĉajno utjeĉe na sniţavanje staklišta i stupnja kristalnosti PEO-a, što je stvorilo vaţan preduvjet za ostvarivanje poboljšane ionske provodnosti. Polimerni nanokompoziti pripravljeni s PEO-om viših molekulnih masa pokazali su niţe vrijednosti stupnja kristalizacije. Rezultati dinamiĉke TG analize pokazali su da LiMMT pogoršava toplinsku postojanost PEO-a, ali i dalje zadovoljava toplinsku postojanost potrebnu za ĉvrsti polimerni elektrolit. Rezultati dinamiĉke termogravimetrije ukazuju da LiMMT utjeĉe na mehanizam toplinske razgradnje PEO-a. Primjenom elektrokemijske impedancijske spektroskopije (EIS) utvrĊena je meĊuovisnost strukture nanokompozita i molekulne mase PEO-a na potencijal poboljšanja ionske provodnosti. Dodatak LiMMT-a poboljšava ionsku provodnost svih ispitanih nanokompozita PEO/LiMMT. Ionska provodnost ovisna je o masenom udjelu LiMMT-a u pripravljenim nanokompozitima i molekulnoj masi PEO-a. Najveća vrijednost ionske provodnosti pri sobnoj temperaturi zabiljeţena je u nanokompozitu pripravljenom s PEO-om viskoznog prosjeka molekulnih masa 300 000 (PEO3) pri 40 mas. % LiMMT-a. Dobivena vrijednost ionske provodnosti iznosi 2,8·10 -6 S cm -1 što je povećanje ionske provodnosti od 949 puta u odnosu na ĉisti polimer. Za seriju nanokompozita PEO/LiMMT s najvećom ionskom provodnosti provedena je kinetiĉka analiza te su razvijeni kinetiĉki modeli procesa dinamiĉke toplinske razgradnje. Na temelju rezultata kinetiĉke analize potvrĊeno je da dodatak LiMMT-a utjeĉe na dinamiĉku toplinsku razgradnju PEO-a. Za razliku od jednostupanjskog procesa dinamiĉke toplinske razgradnje PEO-a, razgradnja nanokompozita PEO3/LiMMT-a se odvija kroz tri stupnja: difuziju, reakciju n-tog reda s autokatalizom i reakciju n-tog reda.Abstract In this work a systematic study of the structure and thermal properites of poly(ethylene oxide) (PEO) based nanocomposites was performed in order to design nanocomposite polymer electrolyte with enhanced ionic conductivity. PEO based nanocomposites with different nanofiller type (sodium montmorillonite, commercially available organoclays Cloisite 10A, Cloisite 15A, Cloisite 20A, Cloisite 25A, Cloisite 93A i Cloisite 30B) were prepared by melt intercalation method. The role of nanofiller is to reduce crystallinity and increase the extent of the amorphous phase of the polymer matrix in order to improve the transfer of cations and ionic conductivity without disruption other properties. Considering the results of structural and thermal characterization, an assessment of the most favourable nanocomposite system of polymers and nanofillers was made for subsequently introduction of Li + ion. The results of the Small angle X-ray scattering (SAXS) analysis showed that PEO was intercalated into montmorillonite layers in all tested samples, which confirmed the formation of nanocomposite structure. Fourier transform infrared spectroscopy (FTIR) analysis showed the existence of an interaction of PEO and nanofiller for all examined nanocomposites. Change in the crystallinity of PEO and distorted helical structure of poly(ethylene oxide) macromolecules in nanocomposites additionally confirmed the formation of intercalated structure. Differential scanning calorimetry (DSC) revealed the influence on thermal transition (glass transition temperature, melting temperature, crystallization temperature) and crystallinity of PEO. The nanofiller NaMMT showed the most pronounced effect on lowering the degree of crystallinity of PEO in nanocomposites. Organically modified montmorillonites at low filler loadings act as nucleation agents that consequently increase the degree of crystallinity of PEO. The non-isothermal thermogravimetric (TG) analysis showed that NaMMT improves PEO thermal stability up to a certain proportion. Organically modified montmorilonites in amounts higher than 10 wt. % strongly reduce the onset degradation temperature. The most pronounced influence was observed in Cloisite 10A based nanocomposites, where the onset degradation temperatures are reduced up to 198 °C compared to the neat PEO. Thermal and structural characterization of above mentioned nanocomposites indicated the greatest potential of the NaMMT as nanofiller and therefore it was selected for the introduction of Li + ion and further analysis. The introduction of lithium ion into the system was carried out by modification of NaMMT by ion exchange method with LiCl resulting in LiMMT. The influence of LiMMT on the structure and thermal properties of PEO/LiMMT nanocomposites prepared with PEO of different molecular weight and the dependence of the results obtained on ionic conductivity have been studied. SAXS and FTIR analysis confirmed the formation of nanostructures in all prepared PEO/LiMMT nanocomposites. The results of the FTIR analysis revealed a more significant interaction of Li + ions with a polymer matrix in nanocomposite prepared with PEO of the high molecular weight compared to those prepared with PEO of the low molecular weight. DSC analysis revealed that the addition of LiMMT significantly reduces the glass transition and the degree of crystallinity of PEO, which created important precondition for improving the ionic conductivity. Polymer nanocomposites prepared with PEO of the higher molecular weights showed lower values of the degrees of crystallinity. The results of non-isothermal TG analysis revealed that the addition of LiMMT reduce the thermal stability of PEO, but still satisfies the thermal stability required for solid polymer electrolyte. The results of non-isothermal TG analysis show that LiMMT affects the mechanism of non-isothermal degradation of PEO. The effect of the nanocomposite structure and the molecular weight of PEO on the potential to improve the ionic conductivity of PEO/LiMMT nanocomposites was determined by electrochemical impedance spectroscopy (EIS). The addition of LiMMT improves the ionic conductivity of all tested PEO/LiMMT nanocomposites. The ionic conductivity depends on the weight fraction of LiMMT in the prepared nanocomposites and the molecular weight of PEO. The highest value of ionic conductivity at room temperature was noted in a nanocomposite prepared with PEO with a molecular weight of 300,000 and 40 wt. % LiMMT. The obtained ionic conductivity was 2,8·10 -6 S cm -1 . The obtained result shows an increase in ionic conductivity for 949 times compared to ionic conductivity of pure PEO. For the PEO/LiMMT series with the highest ionic conductivity, kinetic analysis was performed and kinetic models of the non-isothermal thermal degradation were developed. Based on the results of the kinetic analysis, it was confirmed that the addition of LiMMT affects the mechanism of the non-isothermal thermal degradation of PEO. Unlike the one-step process of non-isothermal decomposition of PEO, the decomposition of PEO3/LiMMT nanocomposites takes place through three stage mechanism: diffusion, n-order reaction with autocatalysis and n-order reaction
Spice and herb extracts as natural inhibitors of polyphenol oxidases : bachelor thesis
No full textHrana je izrazito kvarljiv medij, a jedno od najvažnijih vrsta kvarenja je ono uzrokovano enzimima, osobito polifenol oksidazama. Voće i povrće obiluje ovim enzimima i fenolnim spojevima, a oštećenjem biljnog tkiva dolazi do pucanja stanica pri čemu se oslobađaju polifenol oksidaze koje potom dolaze u doticaj sa supstratom-fenolima što se očituje pojavom posmeđivanja. U svrhu sprječavanja posmeđivanja primjenjuju se brojne tehnike konzerviranja, a posebno je atraktivna i uporaba prirodnih dodataka. U ovom radu ispitano je inhibicijsko djelovanje ekstrakata začinskog i ljekovitog bilja na polifenol oksidazu iz jabuke. Dobiveni rezultati su pokazali da su, između testiranih ekstrakata, samo ekstrakti masline, kurkume i češnjaka učinkovito inhibirali polifenol oksidazu i spriječili posmeđivanje.Food is a highly perishable medium, and one of the most important types of spoilage is caused by enzymes, especially polyphenol oxidases. Fruits and vegetables abound in these enzymes and phenolic compounds. Damaging plant tissues causes cells to break releasing polyphenol oxidases, which then come into contact with the phenol substrates-manifested by the appearance of browning. A number of preservation techniques has been used to prevent browning and the use of natural additives is of great interest. In this thesis, the inhibitory effect of spice and herb extracts on apple polyphenol oxidase was investigated. The results showed that, among the tested extracts, only olive, turmeric and garlic extracts effectively inhibited polyphenol oxidase and prevented browning
Usage of Cannabis (Cannabis Sativa L.) and its potential in the future : bachelor thesis
No full textKonoplja (Cannabis sativa L., Cannabinacae) je jednogodišnja dvodomna zeljasta kritosjemenjača, kojoj su stabljika i listovi prekriveni kratkim dlačicama. Od botaničkih podjela najzastupljenija je ona koja konoplju dijeli na tri vrste, i to: industrijska (lat. Cannabis sativa L. subsp. Sativa), indijska konoplja (lat. Cannabis sativa L. subsp. indica) I divlja konoplja (lat. Cannabis ruderalis). U biološkoj strukturi konoplje postoji više od 400 raznih strukturalno prepoznatljivih spojeva, od kojih su najvažniji kanabinoidi. Kanabinoidi su aktivni sastojci konoplje. Iz biljke Cannabis sativa L. najpoznatiji su kanabidiol (CBD), kanabinol (CBN), delta-9-tetrahidrokanabinol (delta-9-THC), te manje poznati kanabigerol (CBG), kanabikromen (CBC), kanabiciklol (CBL) i dr. Razlikujemo tri vrste kanabinoida: fitokanabinoidi, sintetski kanabinoidi, endokanabinoidi. Nakon otkrića endokanabinoidnoga sustava, ustanovljena je povezanost između ljudskoga tijela i biljke. Endogeni kanabinoidi u međudjelovanju su s određenim receptorima koji se nalaze u raznim dijelovima našeg tijela, poput središnjeg živčanog sustava i imunološkog sustava. Aktiviraju dvije vrste receptora: CB1 i CB2. Konoplja se koristi za izradu različitih komercijalnih i industrijskih proizvoda, uključujući: konop, tekstil, odjeću, obuću, hranu, papir, bioplastiku, izolaciju i biogorivo. Primjena medicinskog kanabisa može se podijeliti na nekoliko područja, a glavna djelovanja su: antiemetičko djelovanje, analgetičko, antidepresivno, u liječenju artritisa, karcinoma, za povećanje apetita, miran san i dr. Utjecaj kanabisa u liječenju simptoma karcinoma zasigurno nije malen. Međutim, kanabis mora, kao i svi ostali lijekovi, da bi bio prihvaćen kao lijek, proći brojna istraživanja, kao i što se treba odrediti odgovarajuća doza i mogući neželjeni učinci. U dosadašnjim istraživanjima, kanabis je pokazao zanimljivu djelotvornost protiv rasta tumorskih stanica.
U Hrvatskoj je od 2016. godine dopušteno korištenje medicinskog kanabisa, propisano od strane liječnika.Hemp (Cannabis sativa L., Cannabinacae) is an annual dioecious herbaceous angiosperm, whose stem and leaves are covered with short hairs. Of the botanical divisions, the most common is the one that divides hemp into three types: industrial (lat. Cannabis sativa L. subsp. Sativa), indian hemp (lat. Cannabis sativa L. subsp. Indica) and wild hemp (lat. Cannabis ruderalis). There are more than 400 different structurally recognizable compounds in the biological structure of hemp, the most important of which are cannabinoids. Cannabinoids are the active ingredients of hemp. From the plant Cannabis sativa L. the most famous are cannabidiol (CBD), cannabinol (CBN), delta-9- tetrahydrocannabinol (delta-9-THC), and the less known cannabigerol (CBG), cannabichromen (CBC), cannabicyclol (CBL) and others. We distinguish three types of cannabinoids: phytocannabinoids, synthetic cannabinoids, endocannabinoids. After the discovery of the endocannabinoid system, a connection was established between the human body and the plant. Endogenous cannabinoids interact with certain receptors located in various parts of our body, such as the central nervous system and the immune system. They activate two types of receptors: CB1 and CB2. Hemp is used to make a variety of commercial and industrial products, including: rope, textiles, clothing, footwear, food, paper, bioplastics, insulation and biofuel. The use of medical cannabis can be divided into several areas, and the main effects are: antiemetic action, analgesic, antidepressant, in the treatment of arthritis, cancer, to increase appetite, restful sleep etc. The impact of cannabis in the treatment of cancer symptoms is certainly not small. However, cannabis, like all other kind of medicine, needs to undergo a number of studies in order to be accepted as a medicine, as well as the appropriate dose and possible side effects. In research to date, cannabis has shown interesting efficacy against tumor cell growth. In Croatia, the use of medical cannabis, prescribed by a doctor, has been allowed since 2016
Volatile compounds profile of flower honey : diploma thesis
No full textPripadnici životinjskog carstva malih dimenzija, iznimno važni za ljudski život na Zemlji, su pčele. Medonosne pčele u Bosni i Hercegovini i Republici Hrvatskoj su Apis mellifica, Apis cerana i Apis mellifera. Pčelinji proizvodi su med, pčelinji otrov, polen, matična mliječ, vosak. Senzorska svojstva meda čine boja, okus i miris. Hlapljivi spojevi su nositelji mirisa prehrambenih proizvoda, pa tako i meda. Kako je miris jedna od komponenti arome, hlapljivi spojevi se često nazivaju i „spojevima arome“. U ovom radu hlapljivi spojeva meda iz vlastitog obiteljskog poljoprivrednog gospodarstva OPG-a Trupina (Bosna i Hercegovina) izolirani su ultrazvučnom ekstrakcijom (USE), ekstrakcijom tekuće-tekuće (LLE) i mikroekstrakcijom vršnih para na krutoj fazi (HS-SPME). Dobiveni ekstrakti su analizirani plinskom kromatografijom-masenom spektrometrijom. Glavni sastojci u ultrazvučnim ekstraktima su ravnolančani ugljikovodici dokosan (C 22 H 46 ) i trikosan (C 23 H 48 ). Monoterpenski eter (Z)-anetol je glavni spoj u vršnim parama meda iz 2019. god., a glavni sastojci vršnih para meda iz 2018. god. su benzaldehid i cis-linalol oksid. Ekstrakcijom tekuće-tekuće izoliran je mali broj spojeva, a i uspješnost identifikacije nije zadovoljavajuća te metoda nije prikladna za izolaciju hlapljivih spojeva iz meda.Important members of animal kingdom living on the Earth which contribute to the better quality of human life are bees. Honey bees in Bosnia and Herzegovina and Republic of Croatia are Apis mellifera, Apis cerana and Apis mellifica. Product of bee keeping are venom, pollen, royal jelly, wax and honey. The honey sensory properties are color, taste and aroma. The volatile compounds are the main aroma compounds of foods andhoney, too. The methods used for the extraction of volatile compounds of meadow honey originating from family apiary Trupina (Bosnia and Herzegovina) are ultrasonic extration (USE), liquid-liquid extraction (LLE) and headspace solid-phase microextraction (HS-SPME). Analysis of all samples was carried out by gas chromatography-mass spectrometry (GC/MS). The main compounds in USE extracts are straight chain hydrocarbons docosane (C 22 H 46 ) and tricosane (C 23 H 48 ). Monoterpene ether (Z)-anethol is the major constituent of honey headspace, sample from 2019. The main constituents of honey headspace, sample from 2018., are benzaldehyde and cis-linalool oxide. Small number of compounds is isolated by liquid-liquid extraction and extraction efficiency wasn't satisfactory, too. So, liquid-liquid extraction is not appropriate method for the isolation of honey volatiles
Antioxidant activity of volatile isolates from broccoli and broccoflower obitaned by microwave extraction : bachelor thesis
No full textPovrće iz porodice kupusnjača (Brassicaceae) karakterizira prisutnost glukozinolata, skupine sekundarnih biljnih metabolita, čiji razgradni produkti pokazuju izrazito dobru biološku aktivnost. Cilj ovo rada bila izolacija hlapljivih sastojaka iz brokule (Calabrese broccoli) i kineske brokule (Romanesco broccoli). Frakcije su izolirane iz svježeg biljnog materijala korištenjem uređaja za mikrovalnu ekstrakciju (400 W, 98°C, 35 min), a analizirane primjenom tehnike plinske kromatografije s masenom spektrometrijom (GC- MS). Frakcijama je testirana antioksidacijska aktivnost korištenjem različitih metoda: sposobnost hvatanja molekula slobodnog radikala DPPH (2,2-difenil-1-pikrilhidrazil), Briggs-Rauscher oscilacijskom metodom i metodom određivanja redukcijske aktivnosti FRAP (engl. Ferric Reducing Antioxidant Power). GC-MS tehnika je pokazala da je dominantan sumporov spoj koji je produkt degradacije u svim izolatima bio dimetil trisulfid (nastaje raspadom S-metilcistein sulfoksida). Najveća koncentracija ovog spoja određena je u frakciji brokule (0,74%) koja je ujedno pokazala i najbolju antioksidacijsku aktivnost primjenom svih korištenih metoda.The vegetable from the Brassicaceae plant family is characterized by the presence of glucosinolates, a group of secondary plant metabolites, whose degradation products show significant biological activity. The aim of this study was the isolation of the volatiles from two Brassica oleracea species: broccoli (Calabrese broccoli) and broccoflower (Romanesco broccoli). The flavour and fragrance fractions were collected from fresh plant material using microwave-assisted extraction (400 W, 98°C, 35 min) and analysed by gas chromatography-mass spectrometry (GC-MS). The fractions were tested for antioxidant activity by multiple method approach using free DPPH (2,2-diphenyl-1-picrilhydrazil) scavenging activity, Briggs-Rauscher oscillating reaction and reducing activity determination by FRAP assay (Ferric Reducing Antioxidant Power). The dominant sulfur-containing degradation product in all isolates was dimethyl trisulfide (from degradation of S-methylcysteine sulfoxide). This compound was detected in flavour fraction of broccoli (0.74%) in highest concentration, and that fraction also provided the best antioxidant activity using all applied methods
Electrode preparation and conductometric measurements in cement paste with the addition of ground brick : bachelor thesis
No full textZa provedbu konduktometrijskih mjerenja u cementnim pastama potrebno je izraditi elektrodu otpornu na visoke pH vrijednosti te dobrih mehaničkih svojstava. Cementna pasta nakon početka vezanja otvrdnjava i prelazi u cementni kamen iz kojeg treba osloboditi neoštećenu elektrodu. Prikladan materijal je elektroda s pločicama od nehrđajućeg čelika s tvrdim polimernim tijelom ispunjenim epoksidnom smolom. Izrađenoj elektrodi potrebno je odrediti konstantu. Izvršeno je kontinuirano mjerenje specifične električne provodnosti cementnih pasti pripravljenih od CEM I uz dodatak 0 - 30 mas.% mljevene građevinske opeke. Mjerenja su provedena pri 20 °C i V/K = 0,5, a vrijednosti specifične električne provodnosti digitalno su očitavani i pohranjivani u memoriju računala svakih 5 minuta do pojave maksimalne provodnosti. Utvrđeno je da povećani dodatak mljevene opeke smanjuje vrijednosti specifične električne provodnosti te odgađa početak vezanja cementnih pasti jer se maksimalna električna provodnost događa kasnije.For execution of conductometric measurements in cement paste, it is necessary to produce an electrode resistant to high pH values and good mechanical properties. The cement paste hardens after the beginning of binding and passes into the cement stone from which the undamaged electrode is to be released. A suitable material is a stainless steel tile electrode with a rigid polymer body filled with epoxy resin. It is necessary to determine a constant for the fabricated electrode. Continuous measurement of the specific electrical conductivity of cement paste prepared by CEM was carried out with the addition of 0 - 30 wt.% of ground brick. Measurements were taken at 20 °C and V/S = 0.5, and the values of the specific electrical conductivity were digitally read and stored in the computer's memory every 5 minutes until enhanced maximum conductances. Increasing the addition of ground brick has been found to reduce the values of specific electrical conductivity and delay the beginning of cement paste bonding since the maximum electrical conductivity occurs later
Antimicrobial activity of winw against food borne pathogens : bachelor thesis
No full textRezultati brojnih studija i istraživanja pokazuju kako konzumacija umjerenih količina vina ima povoljan učinak za ljudsko zdravlje. Glavne komponente vina su voda, etanol, glicerol, organske kiseline i fenolni spojevi. Upravo je zbog ovakvog kemijskog sastava dokazano kako vino ima antimikrobne učinke prema nizu patogena koji mogu uzrokovati kvarenje hrane. Zajedno sa alkoholom, fenolni spojevi se smatraju najzaslužnijima za takva svojstva vina. Zbog specifičnog kemijskog sastava i bioloških svojstava u ovom radu je ispitana antimikrobna aktivnost vina na patogene uzročnike kvarenja hrane. Analiza je provedena na dva crna i tri bijela vina vinarija Volarević (Metković) i Krauthaker (Kutjevo), i to prema Gram pozitivnim (Staphylococcus aureus, Enterococcus feacelis i Listeria monocytogenes) i Gram negativnim (Salmonella enterica i Escherichia coli) bakterijama. Analize su provedene korištenjem tri različite metode: metodom određivanja minimalne inhibitorne koncentracije (MIC), metodom difuzije u jažicama (engl. Well diffusion method) i disk difuzijskom metodom. Dobiveni rezultati ukazuju na bolju antimikrobnu aktivnost vina određenu MIC metodom prema Gram pozitivnim bakterijskim vrstama u odnosu na Gram negativne. Najniže MIC vrijednosti pokazali su Plavac mali standardni prema S. aureus i Graševina standardna prema L. monocytogenes, dok disk difuzijskom metodom nije dokazan inhibitorni učinak vina. Najbolji inhibitorni učinak određen metodom difuzije u jažicama pokazao je Plavac mali standardni i to prema S. aureus i E. coli.The results of numerous studies and researches show that wine consumption has beneficial effect on human health. The main components of the wine are water, ethanol, glycerol, organic acids and phenolic compounds. Precisely because of the chemical composition it has been proven that wine has antimicrobial effects against number of pathogens that can cause food spoilage. Along with alcohol, phenolic compounds are considered as the most responsible for such wine characteristics. Due to the specific chemical composition and biological properties of wine, this study aimed to investigate the antimicrobial activity of the wine against pathogenic microorganisms that causes food spoilage. The analysis was carried out on two red and three white wines from the wineries Volarević (Metković) and Krauhter (Kutjevo), against Gram positive (Staphylococcus aureus, Enterococcus feacelis and Listeria monocytogenes) and Gram negative (Salmonella enterica i Escherichia coli) bacterial species. The analyses were carried out using three different methods: minimum inhibitory concentration method (MIC), disc diffusion and well diffusion method. The obtained results indicate a better antimicrobial activity of wine to Gram positive bacterial species in comparison to Gram negative determined by the MIC method. The lowest MIC values show a standard Plavac mali against S. aureus and standard Graševina against L. monocytogenes, while the disc diffusion method has not shown the inhibitory effect of the wine. The most prominent inhibitory effect determined by the well diffusion method was showed standard Plavac mali against S. aureus and E. coli
Testing the response of membranes for ion-selective electrodes constituted of FeS:Ag2S:PTFE 1:4:5 in acetic buffer : bachelor thesis
No full textOsnovni cilj ovoga završnoga rada je testiranje membranskih elektroda napravljenih od mješavine srebrovog sulfida, ţeljezovog(II) sulfida, te teflona u otopini acetatnog pufera pri pH=4,00. Opisano je testiranje prethodno napravljenih triju membrana u osnovnoj otopini ţeljezovog(II) sulfata heptahidrata, te ispitivanje odziva na ţeljezove(II) katione potenciometrijskom metodom, koja se pokazala najučinkovitijom zbog jednostavnosti, praktičnosti i niske cijene. Odziv na ţeljezove(II) ione ispituje se kod triju membrana istog kemijskog sastava, za usporedbu sluţi membrana istog kemijskog sastava, no različitog omjera komponenti. Dobiven je slab odziv ţeljezovih kationa na razvijene membranske elektrode. Rezultati su prikazani grafički.The main goal of this bachelor thesis was to test membrane electrodes made of a mixture of silver sulfide, ferrous sulfide and teflon in acetate buffer at pH = 4.00. Testing of three pre-made membranes in the solution of ferrous sulfate heptahydrate, and testing the response to ferrous cations by the potentiometric method. Potentiometry has been proven to be the most effective because of its simplicity, convenience and low price. The reaction to ferrouse cations is tested on three pre-made membranes with the same chemical composition and for comparison. There were three membranes with the same chemical composition, but with different ratio of components. The response of ferrous cations to the prepared membrane electrodes was poor. The results were presented graphically