591 research outputs found
Sort by
Preparation and characterization of calcium oxalate monohydrate crystal seeds
No full textKalcijevi oksalati sastavni su dio bubrežnih kamenaca, a najčešće se pronalazi kalcijev oksalat monohidrat i kalcijev oksalat dihidrat dok se trihidrat jako rijetko pronalazi. U ovom diplomskom radu provedena su istraživanja spontanog taloženja kalcijeva oksalata monohidrata pri različitim uvjetima; različite temperature u rasponu od 25-80 ℃, različiti načini miješanja otopina (bez miješanja i ultrazvučno miješanje). Dobiveni kristali okarakterizirani su optičkom mikroskopijom, infracrvenom spektroskopijom, termogravimetrijskom analizom i rendgenskom difrakcijom na prahu. Cilj istraživanja ovog diplomskog rada je procesom spontanog taloženja i u različitim uvjetima sintetizirati što veće i pravilnije kristale kalcijeva oksalata monohidrata te na temelju dobivenih rezultata procijeniti koji su uvjeti najbolji za sintezu što pravilnijih kristala.Calcium oxalates are an integral part of kidney stones, and calcium oxalate monohydrate and calcium oxalate dihydrate are most often found, while trihydrate is very rarely found. In this thesis, investigations were carried out on the spontaneous precipitation of calcium oxalate monohydrate under different conditions; different temperatures in the range 25-80 ℃, different methods of mixing solutions (no mixing and ultrasonic mixing). The obtained crystals were characterized by optical microscopy, infrared spectroscopy, thermogravimetric analysis and X-ray powder diffraction. The aim of the research of this thesis is to synthesize the largest and most regular crystals of calcium oxalate monohydrate by the process of spontaneous precipitation and under different conditions, and based on the obtained results, to assess which conditions are best for the synthesis of the most regular crystals
Serotonin and serotonin receptors
No full textSerotonin je biogeni monoamin i klasični neurotransmiter, jedan je od glavnih neurotransmitera središnjeg živčanog sustava. U ovom radu razmatran je mehanizam njegova djelovanja kao neurotransmiter te kao hormon i mitogen. Počevši od osnovnih pojova živčanog sustava, te njegovih funkcionalnih i strukturnih svojstava. Također je anlizirana struktura i funkcija receptora serotonina, koji najčešće imaju veću ulogu u tome što će se dogoditi nego sam serotonin. Spomenuta su djelovanja selektivnih agonista i antagonista te njihov utjecaj, kako na receptore središnjeg živčanog sustava tako i na receptore drugih organskih sustava poput krvožilnog, probavnog, reproduktivnog i drugih. Raznolikost njegova djelovanja posljedica je toga što je skupina serotoninskih receptora najveća skupina receptora nekog neurotransmitera, to objašnjava njegovu središnju ulogu u regulaciji moetabolizma. Budućnost ovog područja istraživanja biti će presudna u tome kako ćemo se nositi s aktivnom krizom mentalnog zdravlja pružajući dvije opcije: aktivno ili pasivno suočavanje.Serotonin is a biogenic monoamine and classic neurotransmitter. It is one of the main neurotransmitters of the central nervous system. In this paper, the mechanism of its action as a neurotransmitter as well as as a hormone and mitogen is discussed, starting with the basic concepts of the nervous system, and its functional and structural properties. The structure and function of serotonin receptors, which usually have a greater role in what will happen than serotonin itself, were also analyzed,. The effects of selective agonists and antagonists and their influence on the receptors of the central nervous system as well as on the receptors of other organ systems such as circulatory, digestive, reproductive and others are mentioned. The diversity of its action is due to the fact that the group of serotonin receptors is the largest group of receptors for a neurotransmitter, which explains its central role in the regulation of metabolism. The future of this area of research will be crucial in how we deal with an active mental health crisis by providing two options: active or passive coping
Preparation of complex compounds with quinazoline dipicolinic acid derivative
No full textDipikolinsku kiselinu pronalazimo u različitim prirodnim spojevima, a najčešće se koristi kao kelatni ligand u kompleksnim spojevima zbog svoje velike biološke aktivnosti, niske toksičnosti i amfofilne prirode. Derivati kinazolina tijekom proteklih godina pokazuju značajnu antitumorsku terapeutsku učinkovitost. U ovom završnom radu sintetizirani su bakrov (II), željezov (III) i cinkov (II) kompleks s kinazolinskim derivatom dipikolinske kiseline kao ligandom. Dobiveni produkti analizirani su FT-IR i TGA analizom u svrhu dobivanja uvida u njihov sastav i strukturu. Rezultat analize je pretpostavljena struktura bakrovog (II) kompleksa (C26H23Cl2CuN7O5) i željezova (III) kompleksa (C25H19Cl3FeN7O4).Dipicolinic acid is found in various natural compounds and it is mostly used as a chelating ligand in complex compounds because of its great biological activity, low toxicity and amphophilic nature. Quinazoline derivates showed significant antitumor terapeutic activity over the past few years. In this thesis copper (II), iron (III) and zinc (II )complex compounds were prepared with quinazoline derivate of dipicolinic acid as a ligand. Analysis of prepared products was conducted by means of FT-IR and TGA, so that insight into their composition and structure could be obtained. As a result, a structure of copper (II) complex (C26H23Cl2CuN7O5) and iron (III) complex (C25H19Cl3FeN7O4) has been presumed
The application of fresh aronia fruit, Aronia melanocarpa (Michx.) Elliott, as acid-base indicator
No full textAronia melanocarpa (Michx.) Elliott, nazvana još i crnoplodna aronija, biljka je koja pripada porodici ruža (Rosacea), a svoje stanište pronalazi na kiselom i vlažnom tlu. U prirodi raste u obliku grma, a prepoznatljiva je po ljubičasto-crvenim plodovima koji se pojavljuju u velikom broju. U ovisnosti o pH medija, plod aronije mijenja boju otopine od crvene, roza preko ljubičaste, žute i zelene zbog čega se može koristiti kao alternativni kiselo-bazni indikator. Stoga je u ispitivanju korišten plod svježe aronije za pripremu kiselo-baznih indikatora s odabranim otapalima. Cilj rada bio je utvrditi trajnost ovako pripremljenih indikatora i značaj otapala s kojim se indikator priprema. Ispitivanje uključuje i mogućnost recikliranja biljnog materijala u pripremi novih (recikliranih) indikatora. Rezultati istraživanja pokazuju izuzetnu dugotrajnost indikatora pripremljenih na ova način i samog korištenog prirodnog materijala. Ovakvi indikatori imali bi veliku primjenu zbog niske cijene, dugog roka trajanja, jednostavne pripreme i mogućnosti skladištenja. Zbog svih navedenih karakteristika, svježa je aronija izuzetno primjenjiva u nastavi kemije čime bi se učenicima vizualno približilo gradivo o indikatorima, što ujedno doprinosi boljem shvaćanju i razumijevanju gradiva. Na taj bi se način, primjenom svježe aronije kao kiselo-baznog indikatora, zadovoljila potreba kurikularne reforme "Škola za život" jer bi učenici naučeno gradivo mogli povezati sa svakodnevnim životom i primjenom istog.Aronia melanocarpa (Michx.) Elliott, also called black-fruited aronia and chokeberry, is a plant that belongs to the rose family (Rosacea), and finds its habitat on acidic and moist soil. In nature, we find it in the form of a bush, and it is recognizable by its purple-red fruits that appear in large numbers. Depending on the medium pH, chokeberry fruit changes colour of the medium from red, pink to purple, yellow and green, which is why it can be used as an alternative acid-base indicator. Therefore, in this study fresh chokeberry fruit was used in order to prepare acid-base initiators with selected solvents. The aim of this work was to determine the durability of indicators prepared in this way and the importance of the solvent with which the indicator is prepared. Thesis also includes study of the possibility of recycling plant material in the preparation of new (recycled) indicators. The results of the research show the exceptional durability of indicators prepared in this way and of the used plant material. Such indicators could be widely used due to their low cost, long shelf life, easy preparation and possibility of storage. Due to all the above-mentioned characteristics, fresh chokeberry is very applicable in chemistry classroom since it visually brings the teaching material about indicators closer to students and contributes to better comprehension and understanding of these lessons. The application of fresh chokeberry as an acid-base indicator would meet the need of the "School for Life" curricular reform, as the students would be able to connect the learned material with everyday life and its application
Uptake of volatile solids and liquids in a porous Schiff base macrocycle
No full textPredmet istraživanja ovog diplomskog rada je unos hlapljivih čvrstih i tekućih tvari u porozne makrocikličke Schiffove baze. U ovome radu opisana je sinteza i karakterizacija Schiffove baze (pDo5 = 1,6,20,25 - tetraaza - 2,5:8,9:17,18:21,24:27,28:36,37 - heksabenzo - 10,16,29,35-tetraoksa-ciklooktatriakonta-1,6,20,25 - tetraen). Dobiveni produkti okarakterizirani su FT-IR spektroskopijom i TGA analizom. Ispitana je adsorpcija lakohlapljivih krutina i tekućina; naftalena, kamfora, metanola, etanola, izopropanola, butanola i dekanola.The subject of this thesis is the uptake of volatile solids and liquids in a porous Schiff base macrocycle. This paper describes the synthesis and characterization of Schiff's base (pDo5 = 1,6,20,25 - tetraaza - 2,5:8,9:17,18:21,24:27,28:36,37 - hexbenzo - 10,16,29,35-tetraoxa-cyclooctatriakonta-1,6,20,25 - tetraen). The obtained products were characterized by FT-IR spectroscopy and TGA analysis. Adsorption of volatile solids and liquids was investigated; naphthalene, camphor, methanol, ethanol, isopropanol, butanol and decanol
Synthesis and structural characterization of ceria-zirconia catalyst doped with europium
No full textU ovom radu sintetizirano je 4 fazno čistih čvrstih otopina cerij-cirkonij oksida dopiranih s 10 mol% europija. Dopiranje cirkonija i europija u kristalnu rešetku cerijeva(IV) oksida dovodi do povećanja katalitičke aktivnosti te termičke stablinosti katalizatora. Cerijev dioksid je široko upotrebljivani spoj u raznim katalitičkim reakcijama, između ostalih i fotokatalitičkim reakcijama. Zbog miješanog valentnog stanja (Ce3+/4+), dolazi do brze izmijene elektrona te do zavidnih redoks svojstava, koji se dodatno mogu poboljšati dopiranjem drugih elemenata u kristalnu rešetku, najčešće drugih lantanoida i/ili prijelaznih metala manjeg ionskog radijusa (Zr, Y). Sintetizirani uzorci su okarakterizirani koristeći rentgensku difrakciju na prahu, termogravimetrijsku analizu te IR spektroskopiju, dok je fotokatalitička aktivnost praćena na UV/VIS spektrofotometru s halogenom lampom od 20 W. Fotokatalitička aktivnost je praćena na razgradnju 3 AZO boje, od kojih je primjećena najbolja razgradnja na metil crveno (40% kroz 15 minuta).In this work, 4 phase-pure solid solutions of ceria-zirconia doped with 10 mol% europium were synthesized. Doping zirconium and europium into the crystal lattice of cerium(IV) oxide leads to an increase in catalytic activity and thermal stability of the catalyst. Cerium dioxide is a widely used compound in various catalytic reactions, including photocatalytic reactions. Due to the mixed valence state (Ce3+/4+), there is a rapid exchange of electrons and enviable redox properties, which can be additionally improved by doping other elements into the crystal lattice, usually other lanthanides and/or transition metals with a smaller ionic radius (Zr, Y). The synthesized samples were characterized using X-ray powder diffraction, thermogravimetric analysis and IR spectroscopy, while the photocatalytic activity was monitored on a UV/VIS spectrophotometer using a 20 W halogen lamp. The photocatalytic activity was monitored for the degradation of 3 AZO dyes, of which the best degradation was observed on methyl red (40% in 15 minutes)
Application of microchip electrophoresis for determination of inorganic analytes
No full textMinijaturizacijom kapilarne elektroforeze nastala je elektroforeza na mikročipu. Separacija nabijenih vrsta odvija se u separacijskom mikrokanalu pod utjecajem električnog polja. Cilj ovog rada je ispitivanje mogućnosti separacije kalija u dijetetskim suplementima elektroforezom na mikročipu. Dijetetski suplementi su dodaci prehrani koji su spravljeni od koncentriranih izvora hranjivih tvari. Zbog njihove sve lakše dostupnosti na tržištu i povećanja broja potrošača, pojavila se potreba za njihovom preciznom analizom. U prikazanom radu ispitana je mogućnost detekcije i separacije kalija u dijetetskim suplementima. Za detekciju je korišten C4D detektor, a kao pozadinski elektrolit octena kiselina kiselina (c = 0,5 mol/dm3). Uz pomoć linearne regresijske analize utvrđen je linearni odziv. Metodički dio rada obuhvaća pripremu za nastavni sat "Elektroforeza i hemodijaliza". Nastavni sat sadrži kombinaciju frontalnog, individualnog i grupnog rada. Pomoću individualnog rada nastoji se osamostaliti učenike i naglasiti posebnost svakog pojedinca, dok se kroz grupni rad i rad u paru, potiče razumijevanje gradiva i razvoj socijalnih kompetencija učenika.Microchip electrophoresis was created by miniaturization of capillary electrophoresis. The separation of charged species takes place in the separation microchannel under the influence of an electric field. The aim of this work is to investigate the possibility of potassium separation in children's supplements by electrophoresis on a microchip. Dietary supplements are nutritional supplements made from concentrated sources of nutrients. Due to their increasingly easy availability on the market and the increase in the number of consumers, the need for their precise analysis has risen. The presented paper examines the possibility of detecting and separating potassium in dietary supplements. A C4D detector was used for detection, and (c = 0,5 mol/dm3) acetic acid was used as the background electrolyte. With the help of linear regression analysis, a linear response was determined. The methodological part of the work includes preparation for the "Electrophoresis and Hemodialysis" lesson. The lesson contains a combination of face-to-face, individual, and group work. Individual work is used to make students independent and emphasize the uniqueness of each individual, while through group work and pair work, the understanding of the material and the development of students' social competences are encouraged
Electrochemical characterization of p-hydroxybenzoic acid
No full textCilj diplomskog rada bio je ispitati elektrokemijska svojstva p-hidroksibenzojeve kiseline u puferima određene pH vrijednosti i realnim uzorcima pomoću cikličke voltametrije i deferencijalne pulsne voltametrije. Ispitivan je utjecaj pH na potencijal oksidacijskog strujnog vrha, utjecaj koncentracije te promjena brzine polarizacije elektrode na oksido-redukcijska svojstva p-hidroksibenzojeve kiseline. Cilj rada bio je odrediti moguću adsorpciju phidroksibenzojeve kiseline i detektirati p-hidroksibenzojevu kiselinu u realnim uzorcima. Mjerenja su provedena pomoću PalmSens potenciostata/galvanostata. Voltametrijski troelektrodni sustav sastoji se od radne elektrode od staklastog ugljika (GC), referentne (Ag/AgCl) elektrode i protuelektrode platinske žice. Prije svakog mjerenja, sustav je propuhan argonom visoke čistoće (ΦAr = 99,999 %). Cikličkom voltametrijom utvrđen je jedan oksidacijski i jedan redukcijski strujni vrh koji odgovaraju oksidaciji hidroksilne skupine i redukciji oksidacijskog produkta p-hidroksibenzojeve kiseline. Oba strujna vrha su se povećavala s povećanjem brzine polarizacije elektrode. Također je utvrđeno da se radi o difuzijski kontroliranom oksidacijskom procesu. Pomoću diferencijalne pulsne voltametrije utvrđena je adsorpcija p-hidroksibenzojeve kiseline na površinu radne elektrode.. Optimalna pH vrijednost za oksidaciju je pri pH = 6 za elektrodu od staklastog ugljika. Određena je i koncentracija p-hidroksibenzojeve kiseline u realnim uzorcima (grožđu, bijelom vinu, kokosovom mlijeku i suhom kokosu) i ona je varirala od 1,4 μM do 7,6 μM.The aim of this master thesis was to examine the electrochemical properties of phydroxybenzoic acid in buffers of certain pH values and properties of real samples using differential pulse and cyclic voltammetry. The impact of pH on the oxidation peak potential was examined as well as the effect of concentration and scan rate on the oxido-reduction properties of p-hydroxybenzoic acid. Measurements were performed by using the PalmSens potentiostat/galvanostat. The three-electrode voltammetric system consists of a working glassy carbon electrode (GC), reference (Ag/AgCl) electrode, and counter electrode platinum wire. Before each measurement, the system was purged with high purity argon (ΦAr = 99.999 %). Cyclic voltammetry showed one oxidation and one reduction peak which corresponds to oxidation of the hydroxyl group and reduction of an oxidation product of p-hydroxybenzoic acid. Both peaks have increased with the increase of scan rate. It was also determined that the oxidation process was diffusion-controlled. The adsorption of p-hydroxybenzoic acid on the working electrode surface was determined by differential pulse voltammetry. The solution stability with time and the effect of pH on the oxidation peak current was determined. The optimal pH value for oxidation of p-hydroxybenzoic acid was pH = 6 for the glassy carbon electrode. It was determined that with an increase of concentraction of p-hydroxybenzoic acid the oxidation peak current also increased. Concentration of p-hydroxybenozic acid was determined in real samples (grapes, white wine, coconut milk, and dry coconut) and it varied from 1.4 μM to 7.6 μM
Electrochemical characterization of protocatechuic acid
No full textElektrokemijska svojstva 3,4-dihidroksibenzojeve kiseline ispitana su cikličkom voltametrijom i diferencijalnom pulsnom voltametrijom, a antioksidativna aktivnost 3,4-dihidroksibenzojeve kiseline ispitana je DPPH metodom. Glavni cilj istraživanja bio je detektirati 3,4-dihidroksibenzojevu kiselinu u modelnim sustavima te u realnim uzorcima. Mjerenja su provedena pomoću PalmSens potenciostata/galvanostata kontroliranog pomoću PSTrace 1.2. softvera. Troelektrodni sustav sastoji se od radne elektrode od staklastog ugljika ili zlatne elektrode, referentne Ag/AgCl elektrode i protuelektrode platinske žice. Sustav je propuhivan argonom visoke čistoće (ΦA= 99,999 %) prije svakog mjerenja. Ciklički voltamogrami ispitivanog polifenola pokazali su oksidacijski i redukcijski vrh koji odgovaraju oksidaciji hidroksilne skupine i redukciji oksidacijskog produkta ispitivanog antioksidansa. Također, utvrđeno je da je oksidacija ispitivanog polifenola difuzijski kontroliran proces. Diferencijalni pulsni voltamogrami pokazali su da visina oksidacijskog strujnog vrha 3,4-dihidroksibenzojeve kiseline varira s promjenom pH vrijednosti. Utvrđeno je da je optimalna pH vrijednost za oksidaciju 3,4-dihidroksibenzojeve kiseline pri pH = 4,0 za elektrodu od staklastog ugljika te pri pH=6,0 za zlatnu elektrodu. Diferencijalnom pulsnom voltametrijom na elektrodi od staklastog ugljika detektirana je 3,4-dihidroksibenzojeva kiselina u realnim uzorcima; bijelo grožđe, kašica od šljive, sok od jabuke i grožđa te kava od cikorije, gdje je njena količina varirala od 2 M do 9 M.The electrochemical properties of 3,4-dihydroxybenzoic acid were determined by cyclic voltammetry and differential pulse voltammetry, and the antioxidant activity of 3,4-dihydroxybenzoic acid was determined by the DPPH method. The main goal of this study was to detect 3,4-dihydroxybenzoic acid in model systems and in real samples. Measurements were performed using a PalmSens potentiostat/galvanostat controlled by PSTrace 1.2. software. The three-electrode system consists of a glassy carbon electrode or gold electrode as a working electrode, Ag/AgCl reference electrode, and a platinum wire counter electrode. Before each measurement, the system was purged with high purity argon (ΦAr= 99.999 %). Cyclic voltammograms of the investigated polyphenol showed oxidation and reduction peak which correspond to the oxidation of the hydroxyl group and the reduction of the oxidation product of investigated antioxidant. Also, oxidation of the tested polyphenol was found to be a diffusion-controlled process. Differential pulse voltammograms showed that the height of the oxidation peak current of 3,4-dihydroxybenzoic acid varies with changes in pH value. The optimal pH value for the oxidation of 3,4-dihydroxybenzoic acid was found to be at pH = 4.0 for the glassy carbon electrode and at pH = 6.0 for the gold electrode. Differential pulse voltammetry on the glassy carbon electrode detected 3,4-dihydroxybenzoic acid in real samples; white grapes, baby plum food, apple and grape juice, and chicory coffee, where its amount varied from 2 M to 9 M
Inhibitors of P-glycoprotein
No full textP-glikoproteini su zanimljiva skupina proteina koja ima pozitivan učinak jer eliminira štetne supstance iz organizma, ali pri tome može eliminirati i lijekove čime smanjuje učinak terapije. U radu je objašnjeno što su P-glikoproteini i koja im je uloga. Također je objašnjeno što su inhibitori P-glikoproteina i kako oni djeluju. Opisani su inhibitori prve generacije, inhibitori druge generacije i inhibitori treće generacije te je objašnjeno zašto imaju više prednosti nego inhibitori prve i druge generacije. Isto tako, navedeni su neki od predstavnika inhibitora treće generacije te su opisane neke njihove karakteristike. Nadalje, opisana je i višestruka otpornost na lijekove i zašto je ona prepreka u uspješnoj terapiji protiv nekih bolesti. Isto tako, pojašnjena je poveznica P-glikoproteina i višestruke otpornosti na lijekove. U radu je objašnjeno kakva je uloga MDR1 (engl. Multidrug Resistance) gena u otpornosti na lijekove, njihova ekspresija i modulacija. Opisana je interakcija između aktivnih tvari u bilju i P-glikoproteina, njihova citotoksičnost i kojim metodama su sintetizirani. Nadalje, opisani su i načini na koje medicinska kemija otkriva inhibitore P-glikoproteina.P-glycoproteins are an interesting group of proteins with positive effect since it eliminates harmful substances, but it also may eliminate drugs and reduce the therapy efficiency. This thesis explains what P-glycoproteins are and what their role is. P-glycoprotein inhibitors and how they work is also explained. This work describes first, second and third generation of inhibitors and explains why they have more advantages than first and second generation of inhibitors. Also, some of the representatives of the third generation of inhibitors are listed and some of their characteristics are described. Furthermore, multiple drug resistance and why it is an obstacle in successful therapy against some diseases are described. Also, the link between P-glycoprotein and multiple drug resistance has been elucidated. This thesis explains the role of MDR1 (multidrug resistance) genes in drug resistance, their expression and modulation. The interaction between active substances in plants and P-glycoproteins, their cytotoxicity and the methods by which medical chemistry detects P-glycoprotein inhibitors are described. The plants whose extract are used and explanation why these extracts are suitable in the treatment of cancer are discussed. Furthermore, the ways in which medical chemistry detects P-glycoprotein inhibitors are described, some novel compounds are listed, and also the explanation of mechanism of P-glycoprotein inhibition is given