591 research outputs found
Sort by
Determination of fatty acid profile in laying hens feed
No full textTriacilgliceroli su esteri alkohola glicerola i masnih kiselina. Masne kiseline skladište i transportiraju energiju, izgrađuju stanične membrane i reguliraju gene. U radu je opisano određivanje profila masnih kiselina u hrani za nesilice. Uspoređena su četiri načina ekstrakcije: Soxhlet ekstrakcija, mikrovalna ekstrakcija, direktna ultrazvučna ekstrakcija i indirektna ultrazvučna ekstrakcija. Ekstrahirani uzorci su prevedeni u metilne estere masnih kiselina uz borov trifluorid u metanolu i analizirani metodom plinske kromatografije. Najuspješnijim metodoma su se pokazale direktna i indirektna ultrazvučna ekstrakcija s najviše ukupno određenih masnih kiselina, zatim Soxhlet ekstrakcija nakon koje u uzorcima nije određena niti jedna PUFA (engl. Polyunsaturated Fatty Acids) n-3 masna kiselina dok se mikrovalna ekstrakcija pokazala najmanje uspješnom prema broju ukupno određenih masnih kiselina.Triacylglycerols are esters of alcohol glycerol and fatty acids. Fatty acids store and transport energy, build cell membranes and regulate genes. This paper describes the determination of fatty acid profiles in chicken feed mixtures. Four extraction methods were compared: Soxhlet extraction, microwave extraction, direct ultrasonic extraction, and indirect ultrasonic extraction. The extracted samples were converted to fatty acid methyl esters with boron trifluoride in methanol and analyzed by gas chromatography. The most successful methods were direct and indirect ultrasonic extraction with the highest total number of fatty acids detected, followed by Soxhlet extraction after which PUFA (Polyunsaturated Fatty Acids) n-3 fatty acids were not detected in the samples, while microwave extraction proved the least successful according to the number of fatty acids detected
Electro modulation of composite chitosan-carbon nanotube films for controlled release of insulin
No full textDijabetesu tipa 1 uzrok je apsolutni nedostatak lučenja inzulina. Inzulin se trenutno može davati pacijentu jedino parenteralno odnosno injekcijom ili infuzijom u potkožno tkivo. Kao alternativni način dostave inzulina u ovom je radu istražen koncept za kontrolirano otpuštanje inzulina elektromodulacijom kompozitnih filmova kitozan-ugljične nanocijevi. Kompozitni filmovi kitozan-ugljične nanocijevi sa zarobljenim inzulinom naneseni su na screen printed carbon elektrode drop casting metodom, neutralizirane 0,01 mol/L otopinom NaOH. Paralelno je ispitano otpuštanje inzulina difuzijom i elektromodulacijom, a primijenjeni potencijal za elektromodulaciju bio je -0,60 V. Metoda korištena za određivanje količine otpuštenog inzulina bila je voltametrija s linearnom promjenom potencijala (eng. linear sweep voltametry).Type 1 diabetes is caused by an absolute lack of insulin secretion. Insulin can currently be administered to the patient only parenterally i.e., by injection or infusion into the subcutaneous tissue. As an alternative mode of insulin delivery, this master thesis investigates the concept for controlled insulin release by electromodulation of chitosan-carbon nanotube composite films. Composite films of chitosan-carbon nanotubes with loaded insulin were applied to screen-printed carbon electrodes using a drop-casting method and neutralized with NaOH. Insulin release by diffusion and electromodulation were parallelly tested, and the applied potential for electro modulation was -0.60 V. The method used to determine the amount of insulin released was linear sweep voltammetry
Ultrasound assisted extraction of lutein from lutein-enriched eggs
No full textLutein je biljni pigment iz skupine karotenoida, odnosno ksantofila. Koncentracija luteina određivana je u osam skupina jaja. Tri skupine jaja kupljene su u tri različita trgovačka centra, dvije skupine proizvedene su na dva obiteljska gospodarstva. Tri skupine jaja su dobivene s Fakulteta agrobiotehničkih znanosti (FAZOS), od kojih su: jedna skupina jaja fazana, druga skupina su jaja koka nesilica koje su hranjene krmnom smjesom obogaćenom luteinom, a posljednja skupina su jaja obogaćena luteinom i ostalim nutrijentima. Uporabom ultrazvučne ekstrakcije poboljšana je ekstrakcija luteina pa su vrijednosti koncentracija poboljšane za 8,95 %. Koncentracija luteina određivana je iz žumanjka jaja pomoću tekućinske kromatografije visoke djelotvornosti s UV detekcijom. Najmanja koncentracija luteina 0,7255 mg/100 g žumanjka određena je u jajima fazana, dok je najveća koncentracija luteina 5,4613 mg/100 g žumanjka, određena je u jajima koka nesilica koje su hranjene smjesom obogaćenom luteinom. Sve vrijednosti relativne standardne pogreške su veće od prihvatljivi 5 %, ali je važno napomenuti da se radi o 10 uzoraka jaja unutar svake skupine te da su jaja dobivena od različitih koka nesilica, što utječe na odstupanja relativne standardne pogreške.Lutein is a plant pigment from the group of carotenoids, i.e. xanthophylls. Lutein concentration was determined in eight groups of eggs. Three groups of eggs were purchased in three different malls, two groups were produced on two family farms. Three groups of eggs were obtained from the Faculty of Agrobiotechnical Sciences (FAZOS), of which: one set of pheasant eggs, another set of eggs from lying hens fed with a lutein-enriched mixture, and the last set consisted of eggs enriched with lutein and other nutrients. The use of ultrasonic extraction improved the extraction of lutein, so the concentration values in analysed samples were improved by 8.95%. Lutein concentration was determined by high performance liquid chromatography with UV detection. The lowest concentration of lutein 0.7255 mg / 100 g of yolk was determined in pheasant eggs, while the highest concentration of lutein of 5.4613 mg / 100 g of yolk was determined in laying hen eggs fed with a lutein enriched mixture. All relative standard error values are greater than acceptable 5 %, but it is important to note that there are 10 egg samples within each group and that the eggs were obtained from different laying hens, which affects the deviations of the relative standard error
Application of differential scanning calorimetry in the characterization of organic compounds
No full textFizikalna svojstva (talište) organskih spojeva iz skupine aromatskih alkohola u kojima su dvije aromatske jezgre povezane alifatskim lancima različitih duljina ispitivana su termogravimetrijskom analizom i razlikovnom pretražnom kalorimetrijom. Pomoću krivulja snimljenih TGA/DSC instrumentom utvrđeno je da duljina alifatskog lanca i njegova planarnost utječu na tališta organskih spojeva. Rezultati su pokazali da spojevi s dužim alifatskim lancima imaju niža tališta zbog većeg broja alifatskih skupina koje su hidrofobne i uzrokuju međusobne odbojne interakcije zbog kojih dolazi do destabilizacije kristalne strukture molekule. Rezultati također pokazuju da nepravilnosti kao što su odstupanje od planarnosti kod molekula s neparnim brojem CH2 skupina uzrokuju niže talište.The physical properties (melting points) of organic compounds from the group of aromatic alcohols in which two aromatic nuclei are connected by aliphatic chains of different lengths were examined by thermogravimetric analysis and differential scanning calorimetry. Using curves recorded with a TGA / DSC instrument, it was determined that the length of the aliphatic chain and its planarity affect the melting points of organic compounds. The results showed that compounds with longer aliphatic chains have lower melting points due to a larger number of aliphatic groups that are hydrophobic and cause mutual repulsive interactions which lead to destabilization of the crystal structure of the molecule. The results also show that irregularities such as deviations from planarity in molecules with an odd number of CH2 groups cause lower melting point
Ultrasound assisted extraction of vitamin E from eggs enriched with vitamin E
No full textKao vitamin koji pripada skupini vitamina topljivih u mastima, vitamin E je od izuzetne važnosti za zdravlje ljudskog organizma. Glavna i najvažnija uloga mu je kao antioksidans. Svojim djelovanjem sprječava razaranje membrane, uništavanja singlet molekularni kisik, sudjeluje u metabolizmu kolesterola, održava imunološki sustav, itd. Glavni cilj ovog istraživanja bio je ekstrahirati vitamin E iz jaja obogaćenih vitaminom E uz pomoć ultrazvuka te odrediti koncentraciju vitamina E u jajima koja su obogaćena vitaminom E korištenjem tekućinske kromatografije visoke djelotvornosti. Prije analize realnih uzoraka uspoređena je klasična ekstrakcija tekuće-čvrsto i ekstrakcija potpomognuta ultrazvukom, ispitan je utjecaj amplitude na uspješnost UZV ekstrakcije te vrijeme ekstrakcije. Kod određivanja koncentracije vitamina pomoću tekućinske kromatografije visoke djelotvornosti, ispitan je utjecaj temperature. Odabrana je ekstrakcija potpomognuta ultrazvukom uz amplitudu 70 % te vremenom ekstrakcije 1 sat. Koncentracija vitamina E određivana je tekućinskom kromatografijom visoke djelotvornosti pri 40 °C. Koncentracija vitamina E određivana je u komercijalno dostupnim jajima, jajima dobivenima od nesilica s dva obiteljska poljoprivredna gospodarstva te jajima dobivenima od nesilica hranjenih krmnom smjesom s dodatkom vitamina E. Dobiveni rezultati pokazuju da je najveća koncentracija vitamina E prisutna u jajima dobivenima od nesilica hranjenih krmnom smjesom s dodatkom vitamina E, nešto niža koncentracija vitamina E određena je u jajima dobivenima od nesilica s dva obiteljska poljoprivredna gospodarstva, dok je najniža koncentracija određena u komercijalno dostupnim jajima. Usporedba dobivenih rezultata mjerenja ukazuje da će dodatak vitamina E u hranu nesilica povećati njegov sadržaj u jajima.As a vitamin that belongs to a group of fat-soluble vitamins, vitamin E is extremely important to human health. Its main and the most important role is as an antioxidant. It prevents membrane destruction, destroys single molecular oxygen, participates in cholesterol metabolism, maintains the immune system, etc. The main goal of this study was to extract vitamin E from eggs enriched with vitamin E with ultrasound-assited (UA) extraction, and to determine its concentration by using high performance liquid chromatography (HPLC). Before analyzing the real samples, the classical liquid-solid extraction and UA extraction were compared, the influence of the amplitude on the successes of the UA extraction and the extraction time were examined. The influence of temperature during HPLC determination of vitamin E was examined. UA extraction with an amplitude of 70%, extraction time of 1 hour and temperature 40 °C during HPLC analysis was selected. Vitamin E concentration was determined in commercially available eggs, eggs obtained from two family farms, and eggs obtained from laying hens fed with a mixture of vitamin E. The results show that the highest concentration of vitamin E is present in eggs obtained from laying hens fed with a mixture supplemented with vitamin E, a slightly lower concentration of vitamin E was determined in eggs obtained from laying hens from two family farms, while the lowest concentration was determined in commercially available eggs. A comparison of the obtained measurement results indicates that the addition of vitamin E to the feed of laying hens will increase its content in eggs
Synthesis and biological activity of imidazolium salts
No full textPoznata je široka primjena kvaternih amonijevih soli imidazola pa tako i njihova antibakterijska i antifungalna svojstva. Provedene su jednostavne reakcije kvaternizacije imidazola, 1-vinilimidazola i 4-metilimidazola s alkil-halogenidom pri čemu je alkilni lanac (R) varirao između 12 i 20 ugljikovih atoma, a za halogenid (X) je uzet bromid ili jodid. Reakcije su se odvijale u bazičnim uvjetima uz acetonitril kao otapalo, u zatvorenoj inertnoj atmosferi dušika pri 100°C ili na sobnoj temperaturi. Uspješno je sintetizirano deset kvaternih amonijevih soli imidazola. Dobiveni spojevi su izolirani i karakterizirani infracrvenom spektroskopijom (IR) te masenom spektrometrijom (MS). Potencijalna antibakterijska svojstva sintetiziranih spojeva nisu ispitivana u ovome radu.Widespread use of quaternary ammonium salts of imidazole is known, as well as their antibacterial and antifungal properties. Simple quaternization reactions of imidazole, 1-vinylimidazole and 4-methylimidazole with alkyl halide were carried out with the alkyl chain (R) varying between 12 and 20 carbon atoms and the bromide or iodide taken as the halide (X). The reactions were performed under basic conditions with acetonitrile as solvent, under a closed inert nitrogen atmosphere at 100° C or at room temperature. Ten quaternary ammonium salts of imidazole have been successfully synthesized. The obtained compounds were isolated and characterized by infrared spectroscopy and mass spectrometry. The potential antibacterial properties of the synthesized compounds have not been investigated in this paper
Review of biological activities of quercetin
No full textKvercetin (2-(3,4-dihidroksifenil)-3,5,7-trihidroksikromen-4-on) je flavonoid koji je u prirodi prisutan u mnogim biljkama u obliku glikozida. Glavne skupine derivata kvercetina su kvercetin Oglikozidi, a najčešće mjesto glikolizacije nalazi se na C3. Cilj rada je detaljno predstaviti osnovne informacije o kvercetinu; njegovu strukturu i svojstva, biokemiju i sintezu, biodostupnost te metabolizam. Analizirane su znanstvene studije koje istraţuju bioaktivnost kvercetina te je dan sistematski uvid u značaj i utjecaj prehrane bogate kvercetinom na zdravlje, kao i interakcije kvercetina s lijekovima i njegova potencijalna toksičnost. Kvercetin se smatra snaţnim antioksidansom s izraţenom sposobnosti uklanjanja slobodnih radikala i keliranja prijelaznih metalnih iona. Osim antioksidacijskih, kvercetin posjeduje i antivirusna, antikancerogena, protuupalna i brojna druga farmakološki značajna svojstva koja su detaljnije objašnjena u radu. U radu su usporeĎeni rezultati znanstvenih studija koje ispituju oprečno djelovanje kvercetina, a analizirana istraţivanja su pokazala da je kvercetin, ovisno o dozi, potencijalno sredstvo za prevenciju i liječenje raznih bolesti, kao što su neurodegenerativne i kardovaskularne bolesti te mnoge druge.Quercetin (2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4-H-1-benzopyran-4-one) is a flavonoid present in the plant kingdom in the glycoside form. Main group of quercetin derivates are quercetin O-glycosides, and the main place where glycosylation occurs is C3. The aim of the thesis was to present in details main information regarding quercetin structure and properties, biochemistry and synthesis, bioavailability and metabolism. Scientific studies on quercetin bioactivity were analysed and an insight on the importance and impact of a diet rich in quercetin on health was given, interactions of quercetin with medication and its potential toxic effect were also discussed. Quercetin is considered as a powerful antioxidant with a pronounced capability of free radical elimination and chelation of metals. Aside from antioxidant, quercetin also possesses antiviral, anticancer, anti-inflammatory and other pharmacologically significant properties that were also discussed in the thesis. Results of scientific studies that deal with opposed activity of quercetin were also analysed, and they showed that, depending on the dosage, quercetin is a potential remedy for the prevention and treatment of various illnesses, such as neurodegenerative and cardiovascular and many other
Influence of extraction time on vitamin E extraction from real samples
No full textJaje je namirnica koja sadrži vitamine, mikro- i makroelemente koji su potrebni organizmu kako bi normalno funkcionirao. U sastav su uključeni retinol, kolin, tiamin, kobalamin, riboflavin, vitamini B5 i E, kolesterol, magnezij i ostali elementi koji se pronalaze u sastavu ljudskog tijela. Jedan od važnijih vitamina za ljudsko tijelo je vitamin E koji djeluje kao biokatalizator i antioksidans. Osim što štiti stanicu od štetnog djelovanja slobodnih radikala, vitamin E štiti i druge vitamine poput vitamina B i C. Jednostavna, brza i precizna metoda za ekstrakciju vitamina E ubrzava njegovo određivanje u različitim namirnicama. Cilj ovog završnog rada je ispitati utjecaj vremena ekstrakcije na ekstrakciju vitamina E iz realnih uzoraka. Nakon ekstrakcije, koncentracija vitamina E u realnim uzorcima odredit će se pomoću tekućinske kromatografije visoke djelotvornosti.Eggs contain vitamins, micro and macro elements which are necessary for normal body functions. They contain retinol, choline, lutein, thiamine, cobalamin, riboflavin, vitamin B5, vitamin E, magnesium and other elements which can be found in the human body. Vitamin E is among the most important vitamins for the human body as it acts as a biocatalyst and an antioxidant. In addition, vitamin E protects the cell from the harmful effects of free radicals it also protects other vitamins such as vitamin B and C. A simple, fast and precise method for the extraction of vitamin E accelerates its determination in various foods.The aim of this final paper is to examine the influence of extraction time on the extraction of vitamin E from real samples. After extraction, the concentration of vitamin E in real sample will be determined by using high-performance liquid chromatography
Toxicity of nanomaterials
No full textNanotehnologija je interdisciplinarna znanost koja obuhvaća nanoznanost, nanokemiju, nanoelektroniku, nanometrologiju i sl. To je relativno nova grana znanosti koja se zbog svojeg širokog spektra primjene javlja u raznim područjima i procesima kao što su proizvodnja energije, biomedicinska primjena i raznoliki procesi u industriji. Nanotehnologija uključuje uređaje i sustave koji su izgrađeni manipuliranjem pojedinačnih atoma ili molekula te materijala sitnih struktura. Nanomaterijali su materijali koji su konstruirani na način da imaju jedinstveni sastav i funkcionalnost čime omogućavaju raznolike nove alate i tehnike. To su materijali približne veličine od 1 do 100 nanometara (nm). Iako su nanomaterijali zaslužni za mnogobrojne tehničke i industrijske mogućnosti, također predstavljaju rizik kako za čovječanstvo tako i za okoliš, životinje i biljke. Razlog njihove toksičnosti proizlazi iz toga što su to čestice manjih promjera, a velike površine koje imaju specifična toksikokinetička i toksikološka svojstva. Grana tehnologije koja proučava toksičnost i opasnost nanomaterijala, a razvila se usporedno s nanotehnologijom, naziva se nanotoksikologija.Nanotechnology is an interdisciplinary science that includes nanoscience, nanochemistry, nanoelectronics, nanometrology, etc. It is a relatively new branch of science that, due to its wide range of applications, occurs in various fields and processes such as energy production, biomedical applications and various industrial processes. Nanotechnology includes devices and systems that are built by manipulating individual atoms or molecules and materials of small structures. Nanomaterials are materials that are designed to have a unique composition and functionality thus providing a variety of new tools and techniques. Those are the materials whose size is approximately 1 to 100 nanometers (nm). Although nanomaterials are responsible for many technical and industrial opportunities, they also pose a risk to both humanity and the environment, animals and plants. The reason for their toxicity stems from the fact that they are particles of smaller diameter, and large surface that have specific toxicokinetic and toxicological properties. The branch of technology that studies the toxicity and hazards of nanomaterials is called nanotoxicology, which has developed in parallel with nanotechnology
Preparation of complex compounds with quinoline carboxylic acids
No full textKompleksni spojevi se definiraju kao spojevi koji su građeni od metalnog centra i unutrašnje i vanjske sfere ispunjene ligandima. Razlikuju se po geometrijskim oblicima, bojama i magnetnim svojstvima koja objašnjava teorija kristalnog polja. Vezanjem liganada na metalni kation dolazi do energetskog cijepanja d orbitala što uzrokuje nastanak visoko- i nisko- spinskih kompleksnih spojeva. Nadalje, geometrijski oblici koje kompleksni spojevi najčešće tvore su kvadratni planarni, tetraedarski i oktaedarski oblik. Heterociklički spojevi s dušikom vrsta su spojeva koja sadrži vezan jedan ili više dušikovih atoma u cikličkoj strukturi umjesto ugljikovih atoma. Glavni predstavnici su piridin, pirimidin i kinolin, a jednako važni su piperidin, pirol, indol i kinazolin. Zbog prisustva dušika u strukturi i njegovog induktivnog djelovanja na elektrone smanjena im je reaktivnost u elektrofilnoj aromatskoj supstituciji, a povećava u nukleofilnoj aromatskoj supstituciji. U kompleksnim spojevima vežu se pomoću elektronskih parova dušika. Sintetizirani kompleksni spojevi s ligandom (4-oksokinazolin-3(4H)-il)-octena kiselina s metalnim kationima srebra, kadmija, bakra i cinka analizirani su FT-IR i TGA metodama. Pomoću dobivenih rezultata pretpostavka je da se ligand veže na metalne katione pomoću karboksilne skupine i putem dušika sa kinazolinskog prstena.Complex compounds are defined as compounds that are constructed of a metal center and an inner and outer sphere filled with ligands. They differ in geometric shapes, colors, and magnetic properties as explained by crystal field theory. Binding of ligands to metal cations leads to energy cleavage of d orbitals, which causes the formation of high- and low-spin complex compounds. Furthermore, the geometric shapes most often formed by complex compounds are square planar, tetrahedral, and octahedral shapes. Nitrogen heterocyclic compounds are a type of compound that contains one or more attached nitrogen atoms in a cyclic structure instead of carbon atoms. The main representatives are pyridine, pyrimidine and quinoline, and equally important are piperidine, pyrrole, indole and quinazoline. Due to the presence of nitrogen in the structure and its inductive action on electrons, their reactivity in electrophilic aromatic substitution is reduced, and it increases in nucleophilic aromatic substitution. In complex compounds they are bound by electronic nitrogen pairs. Synthesized complex compounds with ligand (4-oxoquinazoline-3(4H)-yl)-acetic acid with metal cations of silver, cadmium, copper and zinc were analyzed by FT-IR and TGA methods. Using the obtained results, it is assumed that the ligand binds to metal cations using a carboxyl group and via nitrogen from the quinazoline ring