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Synthesis and surface modification of superparamagnetic nanoparticles in microfluidic flow reactor
No full textNanočestice magnetita sintetizirane su koprecipitacijom iz otopine koja sadrži fero i feri ione otopinom natrijeva hidroksida u mikrofluidičkom reaktoru. Površina nanočestica magnetita modificirana je lizinom. Uvjeti sinteza su sistematski mijenjani kako bi se provjerio njihov utjecaj na veličinu nastalih nanočestica. Veličina nastalih nanočestica kontrolirana je promjenom početnih uvjeta, ukupnom brzinom protoka i omjerom brzine bočnih i srednjeg kanala. Povećanjem ukupne brzine protoka s 3 na 7,5 μL/s veličina nanočestica se smanjila s 8,59 na 4,22 nm, a povećanjem omjera brzine bočnih i srednjeg kanala s 1,5 na 4 veličina nanočestica se povećala sa 4,23 na 7,2 nm. Nastale nanočestice karakterizirane su IR spektrofotometrijom s Fourierovom transformacijom kako bi se dokazala površinska modifikacije te transmisijskom elektronskom mikroskopijom kojom smo odredili veličinu nastalih nanočestica.Magnetite nanoparticles are synthesized using co-precipitation method from solution containing ferrous and ferric ions with solution of sodium hydroxide in microfluidic reactor. Surface of magnetite nanoparticles is modified with lysine. Synthesis parameters are systematically changed to make sure which of them and how affect the size of obtained nanoparticles. Particle size has been controlled through adjustment of initial parameters, total flow rate and ratio of flow rates of side and main channel. Increasing total flow rate from 3 to 7,5 μL/s, size of nanoparticles is reduced from 8,59 to 4,22 nm. Increasing ratio of flow rates of side and main channel from 1,5 to 4 resulted in increasing nanoparticles size from 4,23 to 7,2 nm. Obtained nanoparticles are characterized with IR spectrophotometry to confirm surface modification and with transmission electron microscopy with which size of obtained nanoparticles is determined
Implementation of electrophoretic techniques in analysis of nucleic acids
No full textU ovom radu opisana je primjena elektroforetskih tehnika u svrhu ispitivanja nukleinskih kiselina. Opisane su značajke i struktura nukleinskih kiselina i značaj različitih postupaka elektroforeze. Provedena je elektroforeza u agaroznom gelu pri čemu su ispitivani humani uzorci DNA, RNA i PCR produkti. Svrha provedenog eksperimenta bio je uvid u cjelokupni postupak elektroforeze u agaroznom gelu.This work examines the application of electrophoretic techniques for the purpose of researching nucleic acids. The features and the structure of nucleic acids are theoretically described, and the importance of each of the electrophoretic procedures is included. The procedure of electrophoresis in agarose gel was implemented with human samples of DNA, RNA and PCR products. Purpose of this experiment was insight into the overall procedure of electrophoresis in agarose gel
Synthesis and identification of nical complex compounds with dipicolinic acid derivatives
No full textKompleksni spojevi su spojevi u kojima su skupine atoma povezane u manje ili više stabilne jedinice, a sastoje se od središnjeg iona ili atoma metala koordiniranog određenim brojem liganada. Kompleksi mogu biti pozitivno, negativno ili neutralno nabijeni. Ukupan naboj kompleksa ovisi o oksidacijskom stanju metala i naboju koji donose ligandi. Kompleksni spojevi dobivaju se dodavajući ligande prijelaznim metalima kao što su titanij, vanadij, krom, magnezij, željezo, kobalt, nikal itd. Prijelazni metali mogu postojati u različitim oksidacijskim stanjima, s različitom brojem elektrona u d ljusci. Oksidacijom ili redukcijom metala u središtu kompleksa, njegova se svojstva mijenjaju. U ovom završnom radu pripremljeni su kompleksni spojevi derivata dipikolinske kiseline, nikla kao prijelaznog metala te različitim vrstama diaminskog liganda kako bi ispitali njihova različita fizikalna i kemijska svojstva. Sve sinteze kompleksnih spojeva izvedene su na sobnoj temperaturi.Complex compunds are compunds in which the groups of atoms are linked to more or less stable units and consist of a central ion or a metal atom co-ordinated by a specific number of ligands. Complexes can be positive, negative or neutral. The total charge of the complex depends on the oxidation state of the metal and the charge that brings ligand. Complex compounds are obtained by adding ligands to transition metals such as titanium, vanadium, chromium, magnesium, iron, cobalt, nickel, etc. Transition metals may exist in different oxidation states, with different number of electrons in D shell. Oxidizing or reducing the metal at the center of the complex, its properties change. In this paper complex compounds of dipicolinic acid derivatives, nickel as a transition metal and various types of diamin ligand have been prepared to examine their various physical and chemical properties. All complex compound syntheses were performed at room temperature
Dioxine and dioxin-like compounds
No full textDioksini i spojevi slični njima su organski spojevi, te primarno nastaju kao produkti spaljivanja otpada, ali i raznim industrijskim procesima. Radi se o vrlo toksičnim, kancerogenim spojevima koji su uz to i teško razgradivi. Upravo zbog tih karakteristika je potrebno dobro ih upoznati, a nakon toga pobuditi svijest o važnosti dobrog gospodarenja opasnim organskim kemijskim otpadom.Dioxins and dioxin-like compounds are organic compounds and primarily result from waste incineration, as well as various industrial processes. They are very toxic, carcinogenic compounds that are hardly degradable. This is the reason why it is necessary to know them well, and then to raise awareness of the importance of good management of hazardous organic chemical waste
Biological Ligands for Matal Ions
No full textU ovom radu opisane su interakcije metalnih iona s raznim vrstama biomolekula (proteinima, enzimima, nukleinskim kiselinama i sl.). Općenito, interakcije ovise o biološkoj vrsti i svojstvima promatrane specije, te o prijelazima elektrona unutar atoma, što ima utjecaj na kemijsku aktivnost i sposobnost elementa da stupi u reakciju s ciljanim odredištem u tkivu - ligandima. Poseban naglasak je stavljen na esencijalne elemente (npr. Cu, Se, Fe, Zn) čiji nedostatak može dovesti do ozbiljnih poremećaja u funkcioniranju organizma pa i smrti, dok s druge strane, velike količine ovih elemenata mogu imati toksičan efekt. Biološki ligandi najčešće ostvaruju veze s metalima preko atoma dušika, kisika ili sumpora, te koordiniraju metalni centar na strogo određen način. Ulogu biološkog liganda u organizmu najčešće može imati voda, anorganski anioni (, , ) razni proteini, porfirini te nukleinske kiseline. Biološki ligandi od značaja još su i različiti koenzimi, vitamini te mnoge druge organske molekule koje sudjeluju u metabolizmu (npr. riboflavini, nikotinamidi, biotin).This thesis gives an overview of metal ion interactions with different kinds of biomolecules (proteins, enzymes, nucleic acids etc.). In general, the interactions depend on the biological species and their properties, as well as on the electron transitions inside the atom, which affects the chemical activity and the ability of the element to react with the target tissue - ligands. More detailed consideration is given to the essential elements (e.g. Cu, Se, Fe, Zn), due to the fact that their absence in the organism leads to various disfunctions, including death, while, on the other hand, in abundance, these elements might have a toxic effect. Biological ligands most commonly form bonds with metal ions via nitrogen, oxygen or sulphor atoms, and coordinate the metal center in a strictly specific way. The role of the biological ligand in the organism is most frequently taken by water, inorganic anions (,, ) , various proteins, porphyrins and nucleic acids. Other significant biological ligands are various coenzymes, vitamins and many other organic molecules which partake in the metabolism (e.g. riboflavin, nicotinamide, biotine)
Modified Aqueous Sol-gel Route Towards Complex Metal Oxides Containing tungsten
No full textU moderno doba ubrzanog razvoja digitalne tehnologije javlja se sve veća potreba za umanjenjem raznih elektroničkih uređaja i povećanjem gustoće zapisa podataka koje ti uređaji pohranjuju. Za postizanje multifunkcionalnih i multiferoičnih svojstava gradivnih materijala ključni su feroelektricitet i feromagnetizam iz čega se javlja potreba za sintezom materijala koji će posjedovati ova svojstva. U ovome diplomskom radu sintetizirani su složeni metalni oksidi perovskitne strukture i modificiranom citratnom sol-gel metodom te su osušeni uzorci kalcinirani pri 600 ℃ i 950 ℃ u peći u struji zraka s temperaturom zagrijavanja 2℃/min. Dobiveni su spojevi okarakterizirani infracrvenom spektroskopijom (FT-IR), rentgenskom difrakcijom na prahu (PXRD), energijski razlučujućom rentgenskom spektroskopijom (EDX), transmisijskom elektronskom mikroskopijom (TEM), pretražnom elektronskom mikroskopijom (SEM), te su im određena magnetska svojstva SQUID mjerenjima. Ovim analitičkim metodama utvrđeno je da su sintetizirani spojevi čistoće 96 w.t. %, da su veličine kristalita ostale male unatoč visokim temperaturama kalciniranja (15-27 nm), te da pokazuju ferimagnetska svojstva. Također, opisan je i metodički dio na temu "Kiseline" za 8. razred osnovne škole koji sadrži pisanu pripremu za nastavni sat, radni listić, te dva pokusa. Nakon što učenici samostalnim izvođenjem predviđenih pokusa u 4 skupine (po dvije skupine izvode isti pokus) dođu do određenih zaključaka, predviđeno je frontalno predavanje kao zaključak na pojave dokazane pokusima.In modern times of technology development there is a need for reducing size and expanding density of data storage components. Ferroelectricity and ferromagnetism are essential for achieving multifunctional properties wherefore a need for synthesizing materials which have these properties appears. In this diploma thesis complex metal oxides of perovskite type crystal structure and have been synthesized using modified citrate sol-gel route. Dried samples were calcined at 600 °C and 950 °C in furnace with air flow and at a temperature rate of 2 °C per minute. Calcined samples were characterized by Fourier transform infrared spectroscopy (FT-IR), Powder X-ray diffraction (PXRD), Energy-dispersive X-ray spectroscopy (EDX), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM) while magnetic ground state has been determined using SQUID measurement. Obtained results have revealed that synthesized materials are 96 wt. % pure and their average crystallite size has remained in nanometer range despite the high calcination temperatures. As a result, magnetic measurements have revealed that these materials posses ferrimagnetic properties. This thesis also contains a part with teaching methods on elementary school level including printed preparation for lesson on "Acids", corresponding working papers and two experiments for group work. After students divided into 4 groups experimentally come to certain conclusions (two groups perform the same experiment), there is a lecture predicted as a conclusion to the phenomena seen in experiments
Determination of two-component mixtures of anionic surfactants using liquid membrane electrode modified by carbon particles
No full textTenzidi ili površinski aktivne tvari su organski spojevi koji smanjuju površinsku napetost otopine u kojoj se nalaze. Sastoje se od polarne (hidrofilne) glave i nepolarnog (hidrofobnog) repa. Dijelimo ih na kationske, anionske, neionske i amfolitske tenzide. Anionski tenzidi u vodenim otopinama disociraju te daju negativno nabijene površinski aktivne organske ione. Potenciometrijske titacije često se koriste za određivanje tenzida. Pri potenciometrijskim mjerenjima korištena je tenzidno selektivna elektroda, čija tekuća membrana je bila sastavljena od dimetildioktadecilamonijevog tetrafenilborata (DDA-TPB) uz dodatak čestica ugljika. Natrijev dodekansulfonat, koncentracije 1× mol/, i natrijev dekansulfonat, koncentracije 1× mol/, određivani su potenciometrijskom titacijom, najprije oba zasebno, a potom zajedno u smjesi. Kao titrant korišten je cetilpiridinijev klorid (CPC) koncentracije 1× mol/.Surfactants or surface active agents are organic compounds that lower the surface tension of a solution. They consist of polar (hydrophilic) head and unpolar (hydrophobic) tail. We differ anionic, cationic, nonionic and amphoteric surfactants. Anionic surfactants dissociate on negatively charged organic ions in liquid solutions. Potentiometric titrations are commonly used for surfactants determination. Surfactant selective electrode with liquid membrane based on dimethyldioctadecylammonium - tertraphenylborate (DDA-TPB) and carbon particles was used for potentiometric measurements. The sodium dodecane sulfonate, c = 1x mol/, and sodium decanesulfonate, c = 1x mol/ were determined using potentiometric titration, first separately than in a mixture. Cetylpyridinium cloride (CPC), c = 1x mol/ was used as a titrant
Preparation of primary amine salts with dipicolinic acid derivatives
No full textU ovom su radu pripremljene soli amina sa derivatom dipikolinske kiseline. Sve soli pripremljene su dvama različitim metodama. Prva metoda uključuje otapanje amina i liganda u metanolu ,a nakon toga miješanje navedenih otopina. Drugi način sinteze aminskih soli je mehanokemijska metoda. Mehanokemijska metoda uključuje dodatak amina, a zatim i liganda u tarionik, a nakon toga njihovo usitnjavanje i mljevenje, pri čemu dolazi do kemijske reakcije. Svi nastali spojevi analizirani na IR spektofotometru, i korištenjem termogravimetrijske metode.In present study amine salts with dipicolinic acid derivatives were prepared. All salts were prepared using two different methods. First method includes solvatation of amine and ligand in methanol and mixing solutions together. The other way to prepare the salts is mechanochemical synthesis. Mechanochemical synthesis includes addition of amine, after that addition of ligand into the mortar, and the mixture is grinded and mixed, consequently the chemical reaction occurs. All formed compounds have been analysed using FT-IR spectrophotometer and thermogravimetric analysis
Leptin in pregnancy
No full textLeptin je polipeptidni hormon, produkt ob/ob gena koji u organizmu djeluje kao adipostat. Glavno mjesto produkcije leptina je adipozno tkivo, a u ostalim tkivima je prisutan u manjim količinama. Signalizira o dostupnim količinama energije, te utječe na rast, razvoj, razmnožavanje i metabolizam. Djeluje preko leptinskih receptora, OB-Rb duge forme proteina i OB-Ra kratke forme proteina. Leptin je metabolički signal koji signalizira spremnost organizma na reprodukciju, sudjeluje u kontroli spolne diferencijacije mozga, početku puberteta, u trudnoći preko posteljice i u laktaciji. Poslije puberteta i u ranoj trudnoći koncentracija leptina u serumu raste, te se smanjuje prema kraju trudnoće i menopauzi. Leptinski receptori prisutni su u endometriju i decidui, te mogu sudjelovati u implantaciji blastociste za stijenku maternice. U trudnoći leptin produciraju majka, fetus i posteljica. Također, prisutan je u krvi novorođenčeta, a također utječe i na porođajnu duljinui masu, fetalnu angiogenezu, hematopoezu embrija i biosintezu hormona između majke i posteljice. Nova istraživanja upućuju na povezanost inzulina i leptina, što dovodi do prekomjernog fetalnog rasta kod trudnica s dijabetesom.Leptin is a polypeptide hormone, the product of the ob gene that works as adipostat in the human organism. Leptin is mainly produced in adipose tissue, but its presence can be found in smalleramounts in other tissues too. Leptin signalises the available amounts of energy and influences growth, development, reproduction and metabolism. It works through leptin receptors, OB- Rb long form of protein and OB-Rb short form. Leptin is a metabolic signal that signalises the readiness of the organism for reproduction. It also takes part in controlling sexual differentiation of the brain, the beginning of puberty, the pregnancy through placenta and in lactation. After the puberty and in the early stage of pregnancy, the concentration of leptin in serum grows, and it reduces with the end of pregnancy and menopause. Leptin receptors are present in the endometrium and decidua and can participate in placentalimplatation of blastocyst. During pregnancy, leptin is produced by mothers, fetus and placenta. It is also present in the blood of an infant, and influences the infant's length and mass, fetal angiogenesis, hematopoiesis of embryos, and biosynthesis of hormones between the mother and the placenta. New researches point to a connection between insulin and leptin, which leads to fetal overgrowth in mothers diagnosed with diabetes
Use of forensic methods in the analysis of the paint in artwork
No full textCilj je ovoga diplomskoga rada navesti i objasniti forenzičke metode za analizu boja umjetničkih djela uz opis i komentar nekih primjera. U slikarstvu boja je najvažniji element slike. Nastaje fizikalnim miješanjem vezivnih materijala i pigmenata s raznim dodatcima koja imaju svojstva bojanja površine na koju su nanesena. Forenzičkim metodama i njihovom kombinacijom moguće je riješiti pitanje autentičnosti umjetničkih slika, odrediti starost i podrijetlo slika, ublažiti posljedice propadanja umjetničkih djela, stilski i vremenski utvrditi stanja slika, analizirati površinu slika, otkriti podcrteže, podslojeve boja, otkriti krivotvorine i ostalo. Metode koje daju rješenja ovih problema su: rentgenska fluorescentna spektroskopija (XRF), optička mikroskopija, pretražna (skenirajuća) elektronska mikroskopija s energetski disperzivnom rentgenskom spektroskopijom (SEM-EDS), mikrokemijska analiza, tankoslojna kromatografija, infracrvena spektroskopija, infracrvena spektroskopija s Fourierovom transformacijom (FTIR spektroskopija), infracrvena reflektografija, Raman spektroskopija, refleksijska spektroskopija pomoću optičkih vlakana (FORS), ultraljubičasta fluorescencija (UVF), ultraljubičasta reflektografija i druge. U Metodičkom dijelu rada obrađena je nastavna jedinica ''Neke metode razdvajanja smjesa - KROMATOGRAFIJA'' u obliku blok sata s ciljem upoznavanja metode za izdvajanje čistih tvari iz homogenih tekućih ili plinovitih smjesa tj. kromatografijom.The aim of this graduate thesis is to state and explain the forensic methods for the analysis of the colors in the art works by describing and commenting on some examples. In painting, color is the most important element of the image. It is produces by physical mixing of binders and pigments with various additives that have the coloring properties of the surface to which they are applied. By means of forensic methods and their combination, it is possible to solve the question of authenticity of artwork, to determine the age and origin of images, to mitigate the consequences of decay of works of art, to determine the state of image, to analyze the surface of images, to reveal substructures, other layers of colors, to reveal false art etc. Methods that address these problems include: X - ray fluorescence spectroscopy (XRF), optical microscopy, scanning electron microscopy with energy dispersive X- ray spectroscopy (SEM-EDS), micro - chemical analysis, thin layer chromatography, infrared spectroscopy, infrared spectroscopy with Fourier transformation (FTIR spectroscopy), infrared reflection, Raman spectroscopy, optical fiber reflection spectroscopy (FORS), ultraviolet fluorescence (UVF), ultraviolet reflection and others. In the methodological part of the paper, the teaching unit ''Some methods of separating the mixture - CHROMATOGRAPHY'' was elaborated in the form of a block hour with the aim of introducing a method for separating clean substances from homogeneuos liquid or gaseous mixtures, i.e. chromatography