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Lasers
No full textLaser je uređaj za stvaranje i pojačavanje koherentnog elektromagnetskog, najčešće monokromatskog, usko usmjerenog zračenja. Otkriće lasera pripisuje se Theodoru Maimanu koji je uspio proizvesti prvu lasersku zraku u Hughes Research Laboratoriju u Kaliforniji, 16. svibnja 1960. godine. Maiman je pomoću bljeskalice obasjavao crveni kristal rubina, čije su plohe bile posrebrene i čime je izazvao lasersku emisiju u crvenom dijelu spektra na 694 nm. S obzirom na agregatno stanje tvari, laseri se dijele na plinske, tekuće i krute. Plinski laseri se zatim dijele na atomske, ionske, molekularne i kemijske. Tekući laseri se dijele na: lasere "kaveznih" molekula i lasere na organskim bojama. Posljednji iz podjele prema agregatnom stanju, kruti laseri dijele se na kristalne, amorfne (stakleni, plastični) i poluvodičke. Lasere također možemo podijeliti prema načinu rada te ih tako dijelimo na impulsne i kontinuirane. Primjenu lasera možemo pronaći u mnogim granama ljudske djelatnosti kao što su industrija, medicina, stomatologija, telekomunikacije, energetika, obrada materijala, vojna industrija te mnoge druge.Laser is a device for creating and enhancing coherent electromagnetic, most often monochromatic, narrow-beam radiation. The laser discovery was attributed to Theodore Maiman, who succeeded in making the first laser beam at the Hughes Research Laboratory in California, May 16, 1960. Maiman blasted a red crystal of ruby with a flash of light, the surface of which was hot and caused a laser emission in the red section of the spectrum at 694nm. By the aggregate state of the substance, the lasers are divided into gas, liquid and rigid. Gas lasers are then divided into atomic, ionic, molecular and chemical. Liquid lasers are divided into: lasers of "cage" molecules and lasers on organic dyes. The last from the split to the aggregate state, solid lasers are divided into crystal, amorphous (glass, plastic) and semiconductor. They can be divided into mode and thus shared on impulsive and continuous. Lasers found applications in many branches of human activity such as industry, medicine, dentistry, telecommunications, energy, materials processing, military industry and many others
Rate of chemical reactions
No full textJedna od glavnih karakteristika kemijske reakcije je njezina brzina. Kako bi došlo do kemijske reakcije najprije molekule moraju doći u dodir jedna sa drugom, odnosno mora doći do uspješnog sudara reaktanata. Broj uspješnih sudara u jedinici vremena određuje brzinu kemijske reakcije. U ovom radu opisani su glavni pojmovi vezani uz brzinu kemijske reakcije, a također su dane i teorije brzine reakcije. Svaka reakcija slijedi kinetiku određenog reda, pa ih tako svrštavamo u reakcije: nultog, prvog, drugog i trećeg reda. Osim navedenog, u radu se spominju i čimbenici koji utječu na brzinu kemijske reakcije, kao i važnost brzine reakcije u svakodnevnom život.One of the main characteristics of the chemical reaction is the rate of reaction. In order for chemical reaction to start, first molecules must get in touch with one another, and must come to a successful collision of reactants. The number of these successful collisions in time determine the rate of a chemical reaction. In this thesis, the main concepts related to the speed of chemical reactions are described together with reaction rate theories. Each reaction followskinetics of particular order, so we can classify reactions as the zeroth-order, first-order, second-order and the third-order reactions. This thesis also elaborates factors that influence rate of chemical reactions as well the importance of the reaction rate in everyday life
Terpenes in the parfume industry
No full textTerpeni su najviše zastupljeni kemijski spojevi u industriji parfema i najveći dio mirisnih spojeva čine upravo terpeni. Ovaj rad obrađuje terpene i spojeve koji su dobiveni iz njih a koji se koriste u parfemima ili proizvodima za svakodnevnu upotrebu u koje se dodaju parfemi kako bi se poboljšao njihov miris. U uvodu je opisana uloga terpena u biljkama, fizikalna i kemijska svojstva terpena te njihova upotreba u proizvodima koje svakodnevno koristimo, od kojih su najvažniji parfemi i proizvodi koji ih sadrže. Terpeni se pojavljuju u prirodi te je objašnjena njihova biosinteza i metode izolacije iz prirodnih izvora. Kako je izolacija prirodnih parfemskih sastojaka često komplicirana i ekonomski neisplativa, pojavila se potreba za njihovom sintezom. Zahvaljujući uspješnoj sintezi terpena i drugih mirisnih kemijskih spojeva, parfemi su postali široko dostupni. U radu je poseban naglasak na terpenima, kao i kemijskim spojevima dobivenima iz njih, koji su važni za industriju parfema. Terpeni su podijeljeni u osnovne skupine, navedeni su najvažniji predstavnici svake skupine i reakcije pomoću kojih se dobivaju. Na kraju rada je osvrt o utjecaju parfemskih sastojaka, uključujući i terpene, na ljudsko zdravlje.Terpenes are the most widely distributed chemical compounds in the perfume industry and most of the fragrant compounds are terpenes exact ly. This paper discusses all that is needed to know about terpenes or compounds derived from them, that are used in perfumes and products for everyday use with added perfumes in order to improve their odor. The introduction describes the role of terpenes in plants, physical and chemical properties of terpenes and their use in products we use every day, of which the most important are perfumes and products containing them. Terpenes occur in nature and their biosynthesis and methods of isolation from natural sources are explained. As the isolation of natural perfume ingredients is often complicated and economically inefficient, there was a need for their synthesis. Due to the successful synthesis of terpenes and other aromatic chemicals, perfumes have become widely available. In this paper is particular emphasis on terpenes, as well as the chemical compounds derived from them, which are important for the perfume industry. There are listed key terpenes, raw materials from which they are derived and the most important chemical reactions which lead to the final products. Terpenes are divided into main groups, there are listed the most important representatives of each group and the chemical reactions from which they are derived. At the end of the paper there is review about the impact of perfume ingredients, including terpenes, on human health
Electrochemical characterization of (+)-catechin
No full textU ovom diplomskom radu ispitivana su elektrokemijska svojstva (+)-katehina u različitim puferima uporabom cikličke i diferencijalne pulsne voltametrije. Vrijednosti pH pufera varirale su od pH = 3,5 do pH = 8,0. Cilj rada bio je ispitati utjecaj pH vrijednosti na potencijal oksidacijskog strujnog vrha (+)-katehina, istražiti utjecaj koncentracije (+)- katehina i brzinu promjene polarizacije elektrode na oksido-redukcijska svojstva (+)- katehina, te istražiti moguću adsorpciju oksidacijskog produkta (+)-katehina na površinu elektrode od staklastog ugljika. Elektrokemijska mjerenja provedena su u troelektrodnoj elektrokemijskoj ćeliji gdje je kao kao radna elektroda korištena elektroda od staklastog ugljika, kao referentna Ag/AgCl elektroda, te kao protuelektroda platinska žica. Utvrđeno je da je proces oksidacije (+)-katehina pri nižim pH vrijednostima (pH = 3,5 i 4,5) kvazireverzibilan ( = 140 mV) i slijedi EC mehanizam oksidacije dok pri višim pH vrijednostima postaje reverzibilan ( = 50 mV). Potencijal oksidacijskog strujnog vrha (+)- katehina linearno se smanjuje s povećanjem pH vrijednosti, dok se struja oksidacijskog strujnog vrha povećava do pH = 4,5 i nakon toga opada. Optimalna pH vrijednost za oksidaciju je pH = 4,5. Također je ustanovljeno da s povećanjem koncentracije (+)-katehina raste visina oksidacijskog i redukcijskog strujnog vrha. Struja oksidacijskog i redukcijskog strujnog vrha raste s povećanjem brzine polarizacije elektrode. Rezultati su također pokazali da dolazi do adsorpcije (+)-katehina i oksidacijskih produkata (+)-katehina na površinu elektrode od staklastog ugljika (visina oba oksidacijska strujna vrha (+)-katehina opada uzastopnim snimanjem voltamograma za sve ispitivane pH vrijednosti).In this diploma thesis electrochemical properties of (+)-catechin, in different buffers, was studied by cyclic voltammetry and differential pulse voltammetry. Values of pH of buffers were varied from pH = 3.5 to pH = 8.0. The main goal of this thesis was to examine the influence of pH on the (+)-catechin oxidation peak potential, to investigate the effect of (+)- catechin concentration and scan rate on the oxido-reduction properties of (+)-catechin and the possible adsorption of the oxidation product of (+)-catechin on the surface of the glassy carbon electrode. Electrochemical measurements were carried out in an electrochemical cell with a three electrode system. Glassy carbon electrode was used as a working electrode, Ag/AgCl electrode was the reference electrode and platinum wire electrode was used as auxiliary electrode. It was found that the oxidation process of (+)-catechin at lower pH values (pH = 3.5 and 4.5) is quasi-reversible = 140 mV) and folows the EC mechanisam of oxidation. At higher pH values proces becomes reversable = 50mV).The oxidation peak potential of the (+)-catechin decreases linearly by increasing the pH value, while the oxidation peak current increases to pH = 4.5 and then decreases. The optimum pH for oxidation is pH = 4.5. It has also been found that the increase of (+)-catechin concentration and scan rate increases the value of oxidation and reduction peak current. The oxidation and reduction peak current increases with increasing scan rate. The results also showed adsorption of (+)-catechin and its oxidation products on the surface of the glassy carbon electrode (the height of both oxidation peaks of (+)-catechin decreases with successive scans for all observed pH values)
Coordination polymers
No full textPolimeri su molekule s velikom molekularnom masom koje nastaju udruživanjem ponavljajućih monomernih jedinica međusobno povezanih kovalentnim vezama. Temeljne građevne jedinice koordinacijskih polimera su metalni ioni i organski ligandi koji se povezuju koordinacijskim vezama i ostalim slabim kemijskim vezama kao što su van der Waalsove sile, π-π veze i vodikove veze. Krajnji izgled koordinacijskih polimera ovisi o građevnim jedinicama (organski ligand, metalni centar, njihovi susjedni ioni i molekule otapala) i njihovoj kompatibilnosti. Nalazimo ih isključivo u čvrstom agregatnom stanju. Razvoj istraživanja koordinacijskih polimera je pojačan zbog razvoja dvaju srodnih područja: kristalnog inženjerstva i supramolekularne kemije. Struktura ovih spojeva može se odrediti uz pomoć rendgenske strukturne analize. Metode sinteze koordinacijskih polimera su generalno jednake metodama za uzgoj kristala. Cilj rada jest sinteza koordinacijskih polimera kadmija s različitim stehiometrijskim udjelom pikolinamida. Njihova svojstva i primjena bit će razjašnjeni u daljnjem tekstu.Polymers are molecules with high molecular weight which are formed by associating of repetition monomeric unit mutually connected with covalent bonds. Main elementary units of coordination polymers are metal ions and organic ligands linked by coordination bonds and other weak chemical bonds such as: van der Waals bonds, π-π bonds and hydrogen bonds. Final look of coordination polymers depands on elementary units (organic ligand, metal center, their counter ions and solvent molecules) and their compatibility. They exist only in the solid state. Development of researching coordination polymers is reinforced by development of two related areas: crystal engineering and supramolecular chemistry. Structure of this compounds can be determined by X-ray structural analysis. The synthesis methods utilized to produce coordination polymers are generally the same as methods used to grow a crystals. Purpose of this study is synthesis of coordination polymers of cadmium with different stoichiometric share of picolinamide. Their properties and application will be elucidated hereinafter
Uncoupling proteins and insulin resistence in diabetes
No full textMitohondrijski proteini razdvajanja (UCP) su nosači aniona koji se nalaze u unutrašnjoj membrani mitohondrija i omogućuju protok protona iz citoplazme u matriks. Oni raspršuju proton motornu silu, te umjesto sinteze ATP-a dolazi do stvaranja topline. UCP-ovi se nalaze u raznim tkivima organizma i pretpostavlja se da utječu na razvoj dijabetesa. Zbog djelovanja UCP-a dolazi do smanjenog lučenja inzulina te do inzulinske rezistencije, stanje u kojem dolazi do smanjenog odgovora tkiva na ovaj hormon. Sam inzulin sintetizira se u beta stanicama gušterače, te se izlučuje kada su stanice potaknute određenom količinom glukoze u krvi. Glukoza ulazi u stanice pomoću transportera glukoze (GLUT). U ovom završnom radu proučit ćemo što je dijabetes te kako izgleda metabolizam glukoze. Reći ćemo kako disfunkcija beta stanica utječe na razvoj ove bolesti i nastanak inzulinske rezistencije. Mehanizam djelovanja samih UCP-ova nije još u potpunosti razjašnjen, ali postoje tri pretpostavke koje ćemo navesti.Uncoupling proteins (UCP) are anion carriers expressed in the mitochondrial inner membrane that enable proton flow from cytoplasm to the matrix. They disperse the proton motor force resulting in heat production instead of ATP synthesis. UCPs are found in various tissues and are supposedly have an affect on development of diabetes. Due to UCPs activity, insulin secretion is reduced and insulin resistance, a condition in which cells do not respond normally to the insulin, is developed. Insulin synthesis takes place in pancreatic beta cells and it's secretion is induced by specific concentrations of glucose. Glucose transporters (GLUT) allow glucose to enter the cells. In this work, we will discuss what diabetes is and how glucose metabolism works. We will find out how dysfunction of beta cells affects diabetes and insulin resistance. The mechanism of action of UCPs is still debated but three potential mechanism will be discussed as well
Synthesis and identification of vanadium complex compoundes with mixed ligands
No full textPredmet istraživanja ovog rada je priprava i određivanje fizikalno-kemijskih svojstava kompleksnih spojeva vanadija s derivatom dipikolinske kiseline i s diaminskom skupinom kao ligandom. Priprava kompleksnih spojeva izvedena je na povišenoj temperaturi uz metanol kao otapalo. Očekivane su strukture za 2 kompleksna spoja: VL1, i VL1L2, . Infracrvena spektroskopija i termogravimetrijska analiza korištene su za karakterizaciju reakcijskih produkata. Kompleksni spojevi vanadija i derivata dipikolinske kiseline su posebno istaknuti zbog svojih inzulinomimetičkih svojstava1.The research subject of this thesis is the preparation and determination of physical and chemical properties of complex compounds of vanadium with dipicolinic acid derivative and diamine types as ligand. The preparation of complex compounds was performed at heated temperature using methanol as a solvent. The expected structures of the two coordination compounds: VL1, i VL1L2, . Infrared spectroscopy and thermogravimetric analysis were used to characterize reaction products. The coordination compounds of vanadium with dipicolinic acid derivative are especially feature for theirs insulin-mimetic properties1
Antioxidants and their contribution to the health and beauty of the skin
No full textSlobodni radikal je svaki atom ili skupina koja ima jedan nespareni elektron ili više njih u vanjskoj ljusci. Reaktivne kisikove vrste su vrlo male molekule ili ioni u koje ubrajamo ione kisika, slobodne radikale anorganske ili organske perokside (ROS). Kako bi izbjegli navedene izvore ROS-a pravilo je da uravnotežimo svoju prehranu koja vodi k zdravijem životu te da povećamo svoju tjelesnu aktivnost. Oksidacijski stres posljedica je prevelikog stvaranja reaktivnih spojeva kisika (oksidansi, radikali) uslijed poremećaja u ravnoteži oksidacijsko - redukcijskih procesa u biološkim organizmima. Odnosno, oksidansi u biološkim organizmima sposobni su otpuštati elektrone, dok su antioksidansi sposobni primati elektrone. Budući da je naš organizam izložen raznovrsnim izvorima oksidacijskog stresa, natjeran je da se zaštiti. Evolucijski su se razvili zaštitni mehanizmi antioksidativne obrane. Antioksidansi su prirodne ili sintetske tvari koje uspješno blokiraju slobodne radikale u njihovom štetnom djelovanju na organizam. Antioksidansi se moraju stalno regenerirati u tijelu, kako bi se uspostavila ravnoteža između njih i slobodnih radikala u tijelu. Čovječji antioksidativni obrambeni sustav sastavljen je od antioksidativnih enzima i neenzimskih antioksidansa. Ključni enzimski antioksidansi koji sudjeluju pri neutralizaciji ROS-a su: superoksid dismutaza, katalaza, glutation peroksidaza, glutation reduktaza.U neenzimske antioksidanse ubrajamo metaboličke antioksidanse i antioksidanse iz hrane. Metabolički antioksidansi (glutation, koenzim Q, lipoična kiselina) su produkti metaboličkih reakcija u tijelu. S druge strane, antioksidansi iz hrane su spojevi koje se ne proizvode u organizmu pa ih stoga moramo unositi putem raznovrsne prehrane. Tu ubrajamo vitamin A, vitamin C, vitamin E, minerali selen i cink, te resveratrol. Svi antioksidansi iz hrane su se pokazali vrlo uspješnim u detoksifikaciji organizma od ROS-a. Uloga antioksidansa u kozmetičkim proizvodima je dvostruka. Sprječavaju nastanak oksidativnog stresa kože koji uzrokuje oštećenje stanica i prijevremeno starenje kože te čuvaju stabilnost kozmetičkih preparata.Free radical is any atom or group having one unpaired electron or more of the outer shell. Reactive oxygen types are very small molecules or ions containing oxygen ions, free radicals of inorganic or organic peroxides (ROS). To avoid these sources of ROS rule is to balance your diet that leads to a healthier life and to increase their physical activity. Oxidation stress is the consequence of the excessive formation of reactive oxygen compounds (oxidants, radicals) due to disorders in the balance of oxidation - reduction processes in biological organisms. In other words, oxidants in biological organisms capable of releasing electrons, while antioxidants are able to receive electrons. Since our organism is exposed to various sources of oxidative stress, it has been made to protect it. Antioxidant defence mechanisms have evolved evolutionally. Antioxidants are natural or synthetic substances which successfully block free radicals in their harmful effects to the organism. Antioxidants must be constantly regenerated in the body to balance the free radicals in the body. The human antioxidant defense system is made up of antioxidant enzymes and non-enzymatic antioxidants. The key enzyme antioxidants involved in ROS neutralization are: superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase. Non-enzymatic antioxidants include metabolic antioxidants and antioxidants from food. Metabolic antioxidants (glutathione, coenzyme Q, lipoic acid ) are products of metabolic reaction in our body. On the other hand, antioxidants from food are compounds that are not produced in the body, so we have to enter them through a variety of diets. These include vitamin A, vitamin C, vitamin E, selenium and zinc minerals, and resveratrol. All antioxidants from food proved to be very successful in the detoxification of the body of ROS. The role of antioxidants in cosmetic products is twofold. Prevent the formation of skin oxidative stress that causes cell damage and premature aging of the skin and keep the stability of preparations
Synthesis, thermal and spectroscopic characterization of zinc complex compounds
No full textU ovom završnom radu opisana je sinteza kompleksnih spojeva cinka s dvije vrste liganada. Kao konstantan ligand pri sintezi korišten je derivat dipikolinske kiseline, 6-(2-benzoilhidrazinkarbonil) pikolinska kiselina, s različitim vrstama diaminskih liganada. Karakterizacija nastalih spojeva rađena je infracrvenom spektroskopijom i termogravimetrijskom analizom. Rezultati analiza prikazani su i objašnjeni na temelju dobivenih spektara i termograma pripremljenih kompleksnih spojeva.In this final work, the synthesis of zinc complex compounds made with two types of ligands is described. As a constant ligand for synthesis dipicolinic acid derivate, 6-(2- benzoylhydrazinecarbonyl) picolinic acid, with different types of diamine ligands have been used. Methods infrared spectroscopy and thermogravimetric analysis were used to characterize of the resulting compounds. The results of the analysis are shown and explained on the basis of the obtained spectra and thermogram of the complex compounds
Synthesis and characterization of crom(lll) complex compounds with two ligand
No full textPredmet ovoga završnoga rada je sinteza i karakterizacija kompleksnih spojeva kroma(III) s dvije vrste liganda. Krom(III) s dvije vrste liganda predstavlja kompleksi spoj prijelaznog metala prvoga reda. U svim sintezama kompleksnog spoja kao konstanti ligand se koristio derivat dipikolinske kiseline, 6-(2-benzoilhidrazinkarbonil)-pikolinska kiselina, a kao drugi ligand su se koristile različite vrste diamina. Sinteze kompleksnih spojeva su se izvodile pri povišenoj temperaturi od 30 do 40 oC uz metanol kao otapalo. Od ukupno 6 izvedenih sinteza 4 kompleksna spoja su analizirana IR spektroskopijom i jedan termogravimetrijskom analizom.The subject of this paper work is the synthesis and characterization of complex chromium(III) compounds with two types of ligands. Chromium (III) with two types of ligands represent the complex compounds of first-row transition metals. In all synthesis of complex compounds as a constant ligand was used a dipicolinic acid derivate, 6-(2- benzoylhydrazinecarbonyl)picolinic acid, as a second ligand different types of diamine were used. Synthesis of complex compounds was performed at elevated temperature from 30 to 40 oC. with methanol as a solvent. Only 4 compounds from performed 6 synthesis were used for IR spectroscopy analysis and one compound for thermogravimetric analysis