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Study of chemical composition of antartic species Stereocaulon glabrum : master thesis
No full text: Stereocaulon glabrum je vrsta u rodu Stereocaulon, koji je dio obitelji Stereocaulaceae. Ova vrsta lišajeva je dobro poznata po svojim karakterističnim obilježjima i potencijalu kao izvor značajnih sekundarnih metabolita. Razumijevanje kemijskog sastava Stereocaulon glabruma ključno je za istraživanje njegovih mogućih primjena u disciplinama poput farmaceutike. Rod Stereocaulon razlikuje se po svom kustoškom primarnom talusu i vresastom sekundarnom talusu. Ova vrsta može se pronaći kako kolonizira brojne podloge, poput stijena, tla i kore drveća, i rasprostranjena je diljem različitih geografskih područja, čime postaje dobar kandidat s obzirom na količinu za buduće primjene. Prema ranijim istraživanjima, rod Stereocaulon je izvor mnogih sekundarnih metabolita koji podržavaju biološke funkcije organizma, kemijske interakcije sa svojim okolišem i također ima potencijala za medicinsku primjenu. Ti metaboliti uključuju depside, depsidone, dibenzofurane i druge specifične kemijske spojeve. Gotovo svi od njih su fenolne prirode koji daju raznovrsne kemijske strukture. Karakteristični sekundarni metaboliti roda Stereocaulon su stictična kiselina, atranorin, lobarična kiselina i drugi fenolni spojevi. Kako bismo prepoznali sličnosti i potencijalne razlike u molekularnoj identifikaciji, usporedit ćemo spojeve koje smo identificirali u Stereocaulon glabrumu s onima koji se redovito nalaze u drugim vrstama roda Stereocaulon. Glavni cilj ovog rada je započeti sveobuhvatnu analizu sekundarnih metabolita prisutnih u Stereocaulon glabrumu. Izolirati ćemo i analizirati neke od različitih kemijskih komponenti koje se nalaze u ovoj vrsti lišaja koristeći analitičke i spektroskopske metode poput kromatografije, NMR spektroskopije i masene spektrometrije. Očekujemo da će rezultati ovog istraživanja unaprijediti naše znanje o kemijskoj raznolikosti roda Sterocaulon i farmakološkom potencijalu, pružajući važne uvide u stvaranje novih lijekova, prirodnih proizvoda i ifiziološki akitvnih kemijskih spojeva u budućnosti.Stereocaulon glabrum is a species in the genus Stereocaulon, which is part of the Stereocaulaceae family. This lichen presents distinctive traits and it is a potential source of significant secondary metabolites. Understanding S. glabrum's chemical composition is of importance for investigating its possible applications in disciplines such as pharmaceuticals. Stereocaulon genus is distinguished by its crustose-type primary thallus and fruticose type secondary thallus. This species can be found colonizing numerous substrates, such as rocks, soil, and tree bark, and is distributed across various geographical regions, making it a very good candidate in terms of quantity for future applications. According to earlier research, Stereocaulon genus synthesizes a wide range of secondary metabolites that support the organism's biological functions, chemical interactions with its environment and also has potential in medicinal applications. These metabolites include depsides, depsidones, dibenzofurans, and other specific chemicals. Almost all of them are of phenolic nature displaying a diverse range of chemical structures. The typical secondary metabolites in the Stereocaulon genus are stictic acid, atranorin, lobaric acid, and other phenolic compounds. In order to identify similarities and potential differences in molecular identification, we will compare the compounds that we have identified in S. glabrum to those that are regularly found in other Stereocaulon species. The primary goal of this thesis is to start a comprehensive analysis of the secondary metabolites present in S. glabrum. We will isolate and characterize some of the chemical components present in this lichen by using analytical and spectroscopic methods like chromatography, NMR spectroscopy, and mass spectrometry. We anticipate that the results of this research will advance our knowledge of Stereocaulon genus chemical diversity and pharmacological potential, offering important insights into the identification of new leads for drug develpment, discovery of new natural products, and new physiologically active chemicals in the future
DEVELOPING HACCP SYSTEM IN FISHMARKET : bachelor thesis
No full textGlavni cilj rada bio je opisati implementaciju HACCP sustava kontrole u ribarnici te dati opći opis implementacije HACCP sustava u proizvodnim pogonima. Opseg rada bio je analiza potencijalnih prijetnji i određivanje kritičnih kontrolnih točaka (KTT), te određivanje kritičnih granica i metoda praćenja. Kritične kontrolne točke određene su analizom rizika i korištenjem stabla odluke. Posebno su obrađeni preduvjetni programi odnosno dobre prakse, standardni operativni postupci kao i standardni sanitacijski operativni planovi čije dobro funkcioniranje je temeljno za uspješnu implementaciju i realizaciju HACCP plana. Analizom opasnosti putem stabla odlučivanja, a prema načelima HACCP sustava utvrđene su kritične kontrolne točke: razvoj mikroorganizmima uslijed neadekvatne temperature skladištenja i ostaci sredstava za kontrolu štetočina ili ostaci sredstava za pranje i dezinfekciju. Za iste su kontrolne mjere i mjere nadzora te predstavljena evidencija.The main goal of the paper was to describe the implementation of the HACCP control system in the fish market and to give a general description of the implementation of the HACCP system in production plants. The scope of the work was the analysis of potential threats and the determination of critical control points (CCP), as well as the determination of critical limits and monitoring methods. Critical control points are determined by risk analysis and using a decision tree. Prerequisite programs, i.e. good practices, standard operating procedures as well as standard sanitation operating plans, whose good functioning is fundamental for the successful implementation and realization of the HACCP plan, are specially processed. Critical control points were determined through hazard analysis using a decision tree, and according to the principles of the HACCP system: development of microorganisms due to inadequate storage temperature and residues of pest control agents or residues of washing and disinfection agents. Control measures and surveillance measures and the presented records are for the same
ELECTROCHEMICAL BEHAVIOR TIN IN NaCl SOLUTION IN THE PRESENCE OF MOLYBDATE ION : bachelor thesis
No full textIspitivano je elektrokemijsko ponašanje kositra u NaCl otopini bez i uz dodatak molibdat iona, pri temperaturi 20 ± 2 o C. Korištene su metode linearne polarizacije i elektrokemijske impendacijski spektroskopije. Određeni su korozijski kinetički parametri: nagibi katodnih i anodnih Tafelovih pravaca (b k i b a ), gustoća korozijske struje (j kor ), polarizacijski otpor (R p ) i vrijednost korozijskog potencijala (E kor ). Zaključeno je da se molibdat ion u ovoj koncentraciji i pri ovom uvjetima ne može uspješno koristiti kao inhibitor korozije kositra u otopini NaCl.The electrochemical behavior of tin in NaCl solution without and with the addition of molybdate ions ,was examined at a temperature of 20 ± 2 o C. The methods of linear polarization and electrochemical impedance spectroscopy were used. Corrosion kinetic parameters were determined: slopes of cathodic and anodic Tafel lines (b k and b a ), corrosion current density (j kor ), polarization resistance (R p ), and corrosion potential value (E kor ). It was concluded that molybdate ions in this concentration and under these conditions cannot be successfully used as a tin corrosion inhibitor in NaCl solutions
Potentiometric sensors with the addition of nanoparticles of hematite for the determination of iron(III) cations : bachelor thesis
No full textU ovom završnom radu ispitane su membrane za ionsko-selektivne elektrode potenciometrijskom metodom. Membrane su izrađene od srebrovog sulfida, politetrafluoroetilena i željezova fosfata te obogaćene nanočesticama hematita a služe za potenciometrijsko određivanje željezovih kationa u otopini acetatnog pufera pri pH=4 i pH=5. Korištena metoda je odabrana zbog jednostavnosti, praktičnosti i niske cijene. Rezultati ispitivanja su prikazani grafički.In this work, membranes for ion-selective electrodes were tested using the potentiometric method. The membranes were made of silver sulfide, polytetrafluoroethylene and iron(III) phosphate and enriched with hematite nanoparticles. The prepared membranes were tested e for the potentiometric determination of iron(III) cations in the acetate buffer solution at pH=4 and pH=5. The method used was chosen due to its simplicity, practicality and low cost. The test results are presented graphicall
Lactobacillus paraplantarum as a natural preservative : bachelor thesis
No full textBakterije mliječno-kiselog vrenja prisutne su u velikom broju prehrambenih proizvoda i odgovorne su za različite pozitivne (fermentacija, antimikrobno djelovanje, senzorska svojstva proizvoda, probiotski učinak) ali i negativne (bakterije kvarenja, antimikrobna rezistencija) procese u prehrambenim proizvodima. Metaboliti bakterija mliječno-kiselog vrenja u prehrambenim proizvodima imaju sposobnost inhibicije različitih patogenih bakterija kao i bakterija kvarenja zbog čega je moguća njihova primjena u konzerviranju nefermentiranih namirnica. U ovom radu ispitana je antimikrobna aktivnost bakterijske vrste Lactobacillus paraplantarum (talog) i uzgojnog medija nakon inkubacije (supernatant) protiv patogenih bakterija i bakterija kvarenja. Antimikrobna aktivnost procijenjena je metodom minimalne inhibitorne koncentracije (engl. Minimum Inhibitory Concentration, MIC), minimalne baktericidne koncentracije (engl. Minimum Bactericidal Concentration, MBC) i metodom difuzije u jažicama (engl. Well Diffusion Method). Najbolji antimikrobni učinak imao je supernatant L. paraplantarum dok je talog bakterijskih stanica L. paraplantarum pokazao jako slabo djelovanje ili nije imao učinak prema testiranim mikroorganizmima. Najniže MIC i MBC vrijednosti supernatanta L. paraplantarum zabilježene su prema patogenoj bakteriji Enterococcus faecalis, s MIC i MBC vrijednosti od 5% i prema bakteriji kvarenja Pseudomonas fragi s MIC i MBC vrijednosti od 2,5%. Najbolji inhibitorni učinak određen metodom difuzije u jažicama pokazali su supernatant i talog L. paraplantarum prema Pseudomonas fragi.Lactic acid fermentation bacteria are present in a large number of food products and are responsible for various positive (fermentation, antimicrobial activity, sensory properties of the product, probiotic activity) and negative (spoilage bacteria, antimicrobial resistance) processes in foods. Metabolites of lactic acid fermentation bacteria in food products have the ability to inhibit various pathogenic bacteria and spoilage bacteria in foods, making them useful for preservation of non-fermented foods. In this thesis, the antimicrobial activity of the bacterial species Lactobacillus paraplantarum (sediment) and the culture medium after incubation (supernatant) was tested against pathogenic bacteria and spoilage bacteria. Antimicrobial activity was evaluated by the minimum inhibitory concentration (MIC) method, minimum bactericidal concentration (MBC) and well diffusion method. The supernatant of L. paraplantarum showed the best antimicrobial effect, while the precipitate of bacterial cells of L. paraplantarum showed a very weak effect or had no effect against the tested microorganisms. The lowest MIC and MBC values of the supernatant of L. paraplantarum were found against the pathogenic bacterium Enterococcus faecalis, with MIC and MBC values of 5% and against the spoilage bacterium Pseudomonas fragi with MIC and MBC values of 2.5%. The best inhibitory effect determined by the diffusion method in wells was shown by the supernatant and sediment of L. paraplantarum against Pseudomonas fragi
POLYMER INCLUSION MEMBRANES : bachelor thesis
No full textCilj ovog rada je pružiti općeniti pregled polimernih inkluzijskih membrana (PIM) te razmotriti utjecaj sastava, strukture, stabilnosti i vijeka trajanja PIM na njihovu učinkovitost. Pripremljena PIM otopina ubrizgat će se, pomoću peristaltičke pumpe, u tri različite staklene kapilarne kolone punjene staklenim kuglicama. Svaka kolona obložena PIM pripremit će se različitim brojem ciklusa. Nadalje, usporedit će se dobivene mase nanesenog sloja PIM na svakoj staklenoj koloni i razmotriti kakav utjecaj broj ciklusa može imati na masu PIM te kakav utjecaj masa PIM može imati na kapacitet prijenosa i selektivnost membrane.The goal of this work is to provide a general overview of polymer inclusion membranes (PIMs) and to consider the influence of the composition, structure, stability, and lifetime of PIMs on their performance. Prepared PIMs solution will be injected, using a peristaltic pump, into three different glass capillary columns filled with glass beads. Each PIM-coated column will be prepared with a different number of cycles. Furthermore, the calculated masses of the applied PIMs layer on each glass column will be compared, also, the influence of the number of cycles on the PIMs mass and the effect of the PIM mass on the membrane's transfer capacity and selectivity will be discussed
Electrochemical determination of cooper complexing capacity in the surface layer of the coastal middle Adriatic sea : diploma thesis
No full textU radu je proučavan utjecaj specifičnog atmosferskog taloženja organske tvari na kapacitet kompleksiranja Cu 2+ (CuCC) u površinskim slojevima mora, s naglaskom na površinski mikrosloj mora (SML) srednjeg Jadrana koji je posebno osjetljiv na vanjske utjecaje u oligotrofnim uvjetima (veljača – srpanj 2019. godine). Primjenjena je diferencijalno pulsna voltametrija anodnog otapanja metala (DPASV) sa živinom kap elektrodom kao radnom elektrodom. Dobiveni eksperimentalni podaci transformirani su u Langmuir/Gerringa nelinearni matematički model u programu ProMCC u kojem su određeni parametri CuCC (klase organskih liganada, njihove koncentracije i prividne konstante stabilnosti). Odabrani su optimalni eksperimentalni uvjeti: E a = -0,6 V, t a = 120 s, E d = -1,4 V tijekom 1 s, [Triton-X-100] = 1 mg/L. Prisustvo L 2 klase liganada ([L 2 ] = 28 – 392 nM) utvrđeno je u svim uzorcima SML, dok je samo u četiri uzorka pronađena L 1 klasa liganada s koncentracijama [L 1 ] = 41 – 76 nM. Koncentracije L 2 klase liganada u potpovršinskoj vodi (ULW) bile su u rasponu od 20 – 70 nM. Vrijednosti uvjetnih konstanti stabilnosti za uzorke SML bile su u rasponu logK CuL1 = 10,34 – 11,11 i logK CuL2 = 9,51 – 10,18. Dobiveni rezultati su usporedivi s onima poznatima za istočno Sredozemno more. Faktor obogaćenja SML u odnosu na ULW za ukupnu koncentraciju organskih liganada bio je u rasponu od 0,9 – 9,1, s najvišim koncentracijama u SML koje ne potječu iz vodenog stupca, već su posljedica specifičnog atmosferskog donosa peludi u travnju 2019. godine. Donosi aerosola otvorenog požara i Saharske prašine u istraživanom razdoblju nisu imali začajan utjecaj na parametre CuCC. Koncentracija slobodnog bakra (2 – 46 pM) bila je u rasponu procijenjenih toksičnih granica koncentracije bakra od oko 10 pM.We studied the effect of atmospheric organic matter deposition on the Cu 2+ complexing capacity (CuCC) in the surface seawater layer of the middle coastal Adriatic, especially in the sea-surface microlayer (SML) during the period of retrieval of the oligotrophic conditions (February-July 2019). We applied differential pulse anodic stripping voltammetry (DPASV) in conjunction with static mercury drop working electrode. The obtained experimental data were fitted into the Langmuir/Gerringa nonlinear mathematical model built in the ProMCC software to determine CuCC parameters (organic ligand class, its concentration and apparent stability constant). We defined the optimal experimental conditions: E a = -0.6 V, t a = 120 s, E d = -1.4 V for 1 s, [Triton-X-100] = 1 mg/L. The presence of L 2 ligand class ([L 2 ] = 28 - 392 nM) was determined in all SML samples, while only in four samples L 1 ligand class with concentrations [L 1 ] = 41 - 76 nM were found. The determined concentrations of L 2 ligand class in the underlying water (ULW) ranged from 20 – 70 nM. Values of conditional stability constants for the SML samples were in the range logK CuL1 = 10.34 – 11.11 and logK CuL2 = 8.32 – 10.02, and for the ULW samples logK CuL2 = 9.51 – 10.18. These values are comparable to the values known for the eastern Mediterranean. The SML showed enrichment with organic ligands by a factor of 0.9 – 9.1 relative to ULW, with the highest concentrations of organic ligands present in SML originating from the specific atmospheric deposition of pollen in April 2019. The deposition of open fires and Saharan dust aerosols in the study period did not have a significant effect on CuCC parameters. The free Cu concentrations (2 – 46 pM) were in the range of the estimated toxic Cu concentration limits of about 10 pM
Characterization of PVAL/PEO blends prepared by solution casting method : bachelor thesis
No full textU ovom radu pripremljeni su polimerni filmovi mješavina poli(vinil-alkohol)/poli(etilen-oksid) (PVAL/PEO) razliĉitih sastava. Filmovi dobiveni tehnikom lijevanja iz otopine pri datim uvjetima nisu zadovoljavajuće kvalitete. S ciljem utvrĊivanja možebitnih interakcija istraživanih polimera primjenjeni su infracrvena spektroskopija s Fourierovom transformacijom (FT-IR) i diferencijalna pretražna kalorimetrija (DSC). Temeljem rezultata FT-IR analize može se potvrditi postojanje interakcija PVAL-a i PEO-a u mješavinama u vidu vodikove veze. S druge strane, temeljem rezultata DSC analize, odnosno neznatne promjene karakteristiĉnih temperatura toplinskih prijelaza nije mogući potvrditi postojanje interakcija u istraživanim mješavinama.In this paper, polymer films of poly(vinyl alcohol)/poly(ethylene oxide) (PVAL/PEO) blends of different compositions were prepared. Films obtained by the solution casting technique under the given conditions are not of satisfactory quality. In order to determine possible interactions of the investigated polymers, infrared spectroscopy with Fourier transform (FT-IR) and differential scanning calorimetry (DSC) were applied. Based on the results of FT-IR analysis, the existence of interactions of PVAL and PEO in blends in the form of hydrogen bonds can be confirmed. On the other hand, based on the results of DSC analysis, i.e. a slight change in the characteristic temperatures of thermal transitions, it is not possible to confirm the existence of interactions in the investigated blends
Chemical composition and biological activity of volatile extract from plants: ground ivy and mediterranean buckthorn : master thesis
No full textCilj ovog rada bio je odrediti kemijski sastav i biološki uĉinak hlapljivih ekstrakata biljaka puzava dobriĉica (Glechoma hederacea L.) i vazdazelena krkavina (Rhamnus alaternus L.). MeĊu spojevima koji ulaze u sastav hlapljivog ekstrakta biljke puzava dobriĉica dominira germakren D, dok meĊu hlapljivim spojevima biljke vazdazelena krkavina dominiraju -pinen i linalool. Testiranje antioksidacijskog potencijala hlapljivih ekstrakata ovih biljaka provedeno je DPPH i FRAP metodom. Rezultati su pokazali da testirani ekstrakti koncentracije 1 g/L pokazuju veoma slabu ili nikakvu antioksidacijsku aktivnost testiranu DPPH i FRAP metodom. Testiranje inhibicijskog potencijala hlapljivim ekstraktima ovih biljaka koncentracije 1 g/L provedeno je na enzime AChE i BChE metodom po Ellmanu te na enzim -glukozidazu metodom po Brueggemanu i Hollingsworthu. Uzorak hlapljivog ekstrakta biljke puzava dobriĉica pokazuje dobru sposobnost inhibicije AChE, dok ekstrakt vazdazelene krkavine slabije inhibira AChE. Ekstrakt biljke puzava dobriĉica slabo inhibira enzim BChE, dok ekstrakt biljke vazdazelena krkavina ne inhibira BChE. Hlapljivi ekstrakt biljke puzava dobriĉica pokazuje dobru sposobnost inhibicije enzima α-glukozidaza, dok ekstrakt biljke vazdazelena krkavina nije pokazao inhibiciju ovog enzima.Aim in the thesis was to determine chemical composition and biological effect of the volatile extracts from plants such as ground ivy (Glechoma hederacea L.) and mediterranean buckthorn (Rhamnus alaternus L.). Of all the chemical compounds that constitute volatile extract from ground ivy, germacrene D is the most abundant. While chemical compounds like -pinene and linalool represent two most abundant constituents in the volatile extract of mediterranean buckthorn. Antioxidant potential tests of these volatile extracts were conducted using the DPPH and FRAP assays. Results have shown that extracts with concentracion of exactly 1 g/L, tested using DPPH and FRAP assays, display either very small or no antioxidant activity. Testing of the inhibition potential of those volatile extracts with same concentration (1 g/L), was conducted by the Ellman's method for enzymes AChE and BChE, and the Brueggan-Hollingsworth method for -glucosidase. Sample of a volatile extract from ground ivy exibits very good ability to inhibit AChE, while the extract from mediterranean buckthorn shows weaker ability to inhibit said enzyme. Extract from ground ivy inhibits BChE poorly, while extract from mediterranean buckthorn has no abilty to inhibit BChE. Volatile extract from ground ivy inhibits α-glucosidase well, but the extract from mediterranean buckthorn doesn't inhibit this enzime
CONTRIBUTION TO THE KNOWLEDGE OF FRAGRANT COMPOUNDS OF SPANISH BROOM : diploma thesis
No full textBrnistra (Spartium junceum L.) je samonikla, grmolika biljka, šibolikih grana i izrazito žutih, mirisnih cvjetova koja pripada porodici mahunarki (Fabaceae). Rasprostranjena je na Mediteranu pa tako i u mediteranskom dijelu Hrvatske. U prošlosti se iskorištavala cijela biljka za različite namjene, no danas se najčešće koriste njezini cvjetovi u parfumerijskoj industriji. Cilj ovog rada bio je izolirati hlapljive spojeve iz cvjetova brnistre koristeći više metoda: vodenu destilaciju i mikrovalnu ekstrakciju za dobivanje eteričnog ulja i hidrolata, ekstrakciju organskim otapalom za dobivanje konkreta i apsoluta te mikroekstrakciju vršnih para na čvrstoj fazi. Kemijski sastav dobivenih izolata, eteričnih ulja, vršnih para cvjetova brnistre, vršnih para hidrolata, vršnih para konkreta, dietil-eterskog ekstrakta hidrolata te apsoluta, analiziran je primjenom plinske kromatografije s masenom spektrometrijom (GC-MS). Ovakav pristup izolaciji i analizi hlapljivih spojeva omogućio je potpuniji uvid u kemijski sastav i sadržaj hlapljivih spojeva ove biljke.Spanish broom (Spartium junceum L.) is a wild-growing, bushy plant with spindly branches and extremely yellow, fragrant flowers that belongs to the legume family (Fabaceae). It is widespread throughout the Mediterranean region, including the Mediterranean part of Croatia. In the past, the whole plant was used for various purposes, but today its flowers are most often used in the perfume industry. The aim of this work was to isolate the volatile compounds from the fresh flowers of S. junceum using several methods: water distillation and microwave extraction to obtain the essential oils and hydrolate, extraction with organic solvent to obtain concretes and absolutes, and headspace solid-phase microextraction. The chemical composition of the obtained isolates, essential oils, headspace volatiles of S. junceum flowers, headspace volatiles of the hydrolate, headspace volatiles of the concrete, diethyl ether extract of the hydrolate and absolutes, was analyzed by gas chromatography with mass spectrometry (GC-MS). This approach to the isolation and analysis of volatile compounds enabled a more complete insight into the chemical composition and content of volatile compounds of this plant