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Antinociceptive effect of botulinum toxin type A on CGRP release in the trigeminal ganglion in an animal model of formalin-induced pain
No full textBotulinum toksin tipa A (BT-A) potentan je neurotoksin kojeg proizvodi bakterija Clostridium botulinum.
Mehanizam djelovanja mu se temelji na sprječavanju otpuštanja neurotransmitera u sinaptičku pukotinu
proteolitičkim kidanjem SNARE proteina zaduženih za njihovu egzocitozu. Dugo se vremena smatralo da je
djelovanje BT-A ograničeno samo na periferna područja u kojima je i primijenjen, zbog čega mu je terapijska
primjena bila ograničena na liječenje autonomnih poremećaja, lokalizirane spastičnosti i hiperkinetičkih
poremećaja pokreta. S vremenom je bilo ustanovljeno kako BT-A ima izraženo antinociceptivno djelovanje i na
središnjoj razini uz minimalne nuspojave, dugotrajan učinak i izostanak tolerancije za razliku od ostalih analgetika
sa sistemskim djelovanjem što ga čini izuzetno privlačnim kandidatom za daljnja istraživanja, posebice u vidu
liječenja boli kroničnog tijeka. Cilj ovog diplomskog rada bio je istražiti utjecaj BT-A na ekspresiju CGRP-a,
neuropeptidnog medijatora boli i upale, u području trigeminalnog ganglija, u modelu upalne orofacijalne boli
uzrokovane primjenom formalina u štakora. BT-A (7 i.j./kg) bio je unilateralno primijenjen u područje desnog
brka (ipsilateralno) Wistar štakora. Šest dana kasnije u područje lijevog brka (kontralateralno) uzrokovana je bol
primjenom 50 μL 2,5 % formalina nakon čega su životinje žrtvovane te su analizirani prerezi njihovih
trigeminalnih ganglija. U negativnoj kontrolnoj skupini se umjesto BT-A koristila fiziološka otopina primijenjena
bilateralno, dok se u pozitivnoj kontrolnoj skupini fiziološka otopina primijenila ipsilateralno, a 50 μL 2,5 %
formalina kontralateralno. Imunohistokemijskom analizom i statističkom obradom praćen je i kvantificiran
intenzitet signala CGRP-a u poprečnim prerezima trigeminalnih ganglija. U eksperimentalnoj skupini primijećeno
je statistički značajno smanjenje ekspresije CGRP-a u odnosnu na kontrolnu skupinu. Dobiveni rezultati sugeriraju
da BT-A djeluje i na suprotnoj strani od mjesta primjene, što upućuje na njegovu mogućnost aksonalnog transporta
i potencijalnog među-sinaptičkog prijenosa (transcitoze). Zaključno, ovaj diplomski rad pokazuje da BT-A može
djelovati ne samo na lokalnoj razini, već i na razini središnjeg živčanog sustava putem moguće transcitoze što
otvara prostor za daljnja istraživanja njegovog središnjeg antinociceptivnog djelovanja.Botulinum toxin type A (BT-A) is a potent neurotoxin produced by the bacterium Clostridium botulinum. Its
mechanism of action is based on preventing the release of neurotransmitters into the synaptic cleft by proteolytically
cleaving SNARE proteins responsible for their exocytosis. For a long time, it was believed that the effects of BT-A
were limited to the peripheral areas where it was applied, restricting its therapeutic use to treating autonomic disorders,
localized spasticity, and hyperkinetic movement disorders. Over time, it was established that BT-A has significant
antinociceptive effects at the central level, with minimal side effects, long-lasting impact, and no development of
tolerance compared to other systemically acting analgesics, making it an exceptionally attractive candidate for further
research, particularly in the treatment of chronic pain. The aim of this thesis was to investigate the influence of BT-A
on the expression of CGRP, a neuropeptide mediator of pain and inflammation, in the trigeminal ganglion in a model
of inflammatory orofacial pain induced by formalin application in rats. BT-A (7 i.j./kg) was unilaterally administered
to the area of the right facial vibrissae (ipsilateral) in Wistar rats. Six days later, pain was induced in the area of the left
facial vibrissae (contralateral) by applying 50 μL of 2.5% formalin, after which the animals were sacrificed and
sections of their trigeminal ganglia were analyzed. In the negative control group, saline was used instead of BT-A,
administered bilaterally, while in the positive control group, saline was administered ipsilaterally, and 50 μL of 2.5%
formalin was applied contralaterally. Immunohistochemical analysis and statistical processing were used to monitor
and quantify the intensity of CGRP signals in transverse sections of the trigeminal ganglia. In the experimental group,
a statistically significant reduction in CGRP expression was observed compared to the control group. The obtained
results suggest that BT-A also acts on the opposite side of the application site, indicating its potential for axonal
transport and possible trans-synaptic transfer (transcytosis). In conclusion, this thesis demonstrates that BT-A can act
not only at the local level but also at the central nervous system level through potential transcytosis, opening up the
possibility for further research into its central antinociceptive effects
Determination of metal impurities in dietary supplements for the treatment of inflammatory bowel diseases using the GFAAS technique
No full textPrimjena dodataka prehrani koji sadrže biljne sastavnice u stalnom je porastu, a zahtjevi za
kontinuiranu kontrolu sigurnosti istih ne postoje. Kurkuma, justicija, indijski tamjanovac i crni papar
sadrže biološki aktivne tvari koje pokazuju pozitivan učinak na tijek upalnih bolesti crijeva.
Navedene biljke iz tla akumuliraju, u svojim podzemnim i nadzemnim organima, teške metale koji
imaju negativan učinak na zdravlje ljudi. Određen je sadržaj kobalta, nikla, srebra i selena u 15
dodataka prehrani različita porijekla metodom atomske apsorpcijske spektrometrije, grafitnom
tehnikom. Kobalt i selen imaju važne uloge u organizmu, no u prekomjernim količinama ostvaruju
štetno djelovanje. Nikal i srebro štetni su već pri malim količinama. Analizi sadržaja metala
prethodila je mikrovalna digestija. Koncentracije analiziranih metala ispod su maksimalno
dozvoljenog dnevnog oralnog unosa za metalna onečišćenja koji navode ICH smjernice iz čega se
zaključuje da analizirani dodaci prehrani ne predstavljaju rizik za zdravlje. Pretraživanjem dostupne
stručne i znanstvene literature, rezultati rada uspoređeni su s prethodnim istraživanjima na istim
biljkama te nisu uočene statistički značajne razlike u sadržaju metala u biljkama.The use of dietary supplements containing herbal components is constantly increasing, yet the
requirements for continuous safety control of these supplements do not exist. Turmeric, Indian
frankincense, Green chiretta, and Black Pepper contain biologically active substances that show a
positive effect on the course of inflammatory bowel diseases. These plants accumulate heavy metals
from the soil in their underground and aboveground organs, which have a negative impact on human
health. The content of cobalt, nickel, silver, and selenium in 15 dietary supplements of various
origins was determined using atomic absorption spectrometry with graphite furnace technique.
Cobalt and selenium play essential roles in the body, but in excessive amounts, they have harmful
effects. Nickel and silver are harmful even in small amounts. Microwave digestion preceded the
analysis of metal content. The concentrations of the analyzed metals are below the permitted daily
oral intake for elemental impurities as stated by the ICH guidelines, leading to the conclusion that
the investigated dietary supplements do not pose a health risk. By searching the available
professional and scientific literature, the results of this work were compared with previous studies
on the same plants, and no statistically significant differences in metal content were observed in
plants
Construction of a system for preparing water of increased purity for use in medical laboratories
No full textTema ovog završnog rada je dimenzioniranje sustava za pripremu vode povišene čistoće, koji će proizvoditi minimalno 30 L/h s vodljivošću maksimalno 1 (μS/cm). Sustav je namijenjen za korištenje u medicinskim laboratorijima, gdje su zahtjevi za kvalitetu vode izrazito strogi. Voda koja se obrađuje dolazi iz javnog vodoopskrbnog sustava, što znači da sustav mora biti sposoban ukloniti širok spektar onečišćenja, uključujući otopljene soli, organske tvari, mikroorganizme i čestice. U medicinskim laboratorijima, čista voda je neophodna za precizno izvođenje analiza, pripremu reagensa, ispiranje laboratorijske opreme i mnoge druge ključne procese. Čak i najmanje nečistoće u vodi mogu značajno utjecati na rezultate testova i pouzdanost eksperimenata, stoga je postizanje visoke razine čistoće vode od presudne važnosti. U prvom dijelu rada istražile su se opće karakteristike vode, njezina kemijska i fizička svojstva te važnost čistoće vode u različitim industrijama, s posebnim naglaskom na medicinske laboratorije. Analizirani su specifični zahtjevi koje voda mora zadovoljiti za laboratorijsku upotrebu, uključujući standarde čistoće, kemijsku sastav i biološku sigurnost. Također su predstavljene različite metode pročišćavanja vode, uz detaljan opis principa rada svake metode i njihovih prednosti i nedostataka. Drugi dio rada fokusira se na tehnički aspekt projektiranja sustava. Ovdje je proveden detaljan proračun postrojenja, uključujući dimenzioniranje ključnih komponenti kao što su crpke, membranske jedinice, spremnici i filtri. Proračun uključuje izračune kapaciteta sustava i protoka vode. Posebna pažnja posvećena je se optimizaciji procesa kako bi se osigurala maksimalna učinkovitost i minimalni operativni troškovi, uz istovremeno postizanje visoke razine čistoće vode.
Treći dio rada obuhvaća izradu P&I (Piping and Instrumentation) dijagrama, koji grafički prikazuje sve cjevovode, instrumente i kontrolne uređaje unutar sustava. P&I dijagram omogućuje jasno razumijevanje funkcioniranja i interakcija unutar sustava, što je ključno za njegovu pravilnu instalaciju i održavanje. Uz to, izrađen je detaljan CAD model sustava koji vizualizira sve komponente i njihov raspored u prostoru. CAD model pruža precizan prikaz sustava, olakšava planiranje instalacije i omogućuje identifikaciju potencijalnih problema u dizajnu prije nego što se krene s izgradnjom sustava.The topic of this thesis is the design of a high-purity water preparation system that will produce a minimum of 30 L/h with a conductivity of less than 1 μS/cm. The system is intended for use in medical laboratories, where water quality requirements are extremely stringent. The water to be treated comes from the public water supply system, meaning the system must be capable of removing a wide range of contaminants, including dissolved salts, organic matter, microorganisms, and particles. In medical laboratories, pure water is essential for precise analysis, reagent preparation, washing laboratory equipment, and many other critical processes. Even the slightest impurities in the water can significantly affect test results and experiment reliability, making the achievement of high water purity levels crucial.
The first part of the thesis explores the general characteristics of water, its chemical and physical properties, and the importance of water purity in various industries, with a special focus on medical laboratories. It analyzes the specific requirements that water must meet for laboratory use, including purity standards, chemical composition, and biological safety. Different water purification methods is also presented, along with detailed descriptions of their operating principles, advantages, and disadvantages.
The second part of the thesis focuses on the technical aspect of system design. A detailed plant calculation is conducted here, including the sizing of key components such as pumps, membrane units, tanks, and filters. The calculation includes system capacity and water flow. Special attention is paid to the process optimization to ensure maximum efficiency and minimal operating costs while achieving a high level of water purity.
The third part of the thesis involves the creation of a P&I (Piping and Instrumentation) diagram, which graphically depicts all pipelines, instruments, and control devices within the system. The P&I diagram enables a clear understanding of the system's functions and interactions, which is crucial for its proper installation and maintenance. Additionally, a detailed CAD model of the system is created, visualizing all components and their arrangement in space. The CAD model provides an accurate depiction of the system, facilitates installation planning, and allows for the identification of potential design issues before construction begins
Synthesis, characterization and derivatization of a polysubstituted piperidino-morpholine spiro building block
No full textMale molekule s novim mehanizmima djelovanja neophodne su u rješavanju izazovnih biomedicinskih problema današnjice poput rezistencije na postojeće lijekove za liječenje raka i zaraznih bolesti. Jedan od pristupa otkriću novih biološki aktivnih molekula uključuje sintezu usmjerenu na raznolikost (engl. diversity-oriented synthesis, DOS), koja primarno podrazumijeva razlike u strukturnoj okosnici, supstituentima i stereokemiji. Različiti lijekovi koji u svojoj strukturi sadrže morfolinski prsten imaju široku terapijsku primjenu. Privilegirani je farmakofor s mogućnošću stvaranja molekulskih interakcija s raznovrsnim biološkim metama i modificiranja farmakokinetičkih svojstava. Stoga je morfolin strukturni motiv od posebnog interesa za dizajniranje i razvoj lijekova. Istodobno je povećan interes za sintezu manje planarnih biološki aktivnih spojeva što rezultira uvođenjem spiro spojeva u nova istraživanja.
Slijedom navedenih spoznaja, cilj ovog diplomskog rada bila je sinteza i karakterizacija polisupstituiranog piperidino-morfolinskog spiro gradivnog bloka te njegova derivatizacija u svrhu dobivanja novih spojeva s različitim svojstvima, korištenjem principa sinteze usmjerene na raznolikost. Osnovna strukturna okosnica sintetizirana je preko dva sintetska puta, u šest odnosno četiri reakcijska koraka, od kojih je zadnji korak intramolekulska ciklizacija u bazičnim uvjetima. U nekoliko sljedećih sintetskih koraka, iz glavnog intermedijara 6, pripravljeni su odgovarajući prekursori. Šest novih derivata 9a-c i 13a-c dobiveno je iz spojeva 8 i 12 s dvije slobodne amino-skupine, završnim reakcijama N-acetiliranja, sulfonamidacije i Eschweiler-Clarke reakcijom. Strukturna raznolikost postignuta je supstituiranjem osnovne strukturne okosnice u tri različita položaja, a strukture novosintetiziranih spojeva potvrđene su uobičajenim spektroskopskim metodama (1D i 2D NMR, MS). Dokazana je izražena trodimenzionalnost struktura finalnih spojeva 9a-c i 13a-c pomoću NOESY NMR spektara. Finalnim spojevima određena su i fizikalno-kemijska svojstva in silico.Small molecules with novel mechanisms of action are necessary in addressing today’s challenging biomedical problems such as resistance to existing drugs for the treatment of cancer and infectious diseases. One of the approaches to the discovery of new bioactive molecules includes diversity-oriented synthesis (DOS), which primarily implies differences in the molecular scaffold, substituents and stereochemistry. Various drugs containing a morpholine ring in their structure are widely used for the treatment of numerous diseases. It is a privileged pharmacophore with the possibility of forming molecular interactions with diverse biological targets and modifying pharmacokinetic properties. Therefore, morpholine is a structural motif of special interest for the drug design and development. At the same time, interest for the synthesis of less planar bioactive compounds increases, resulting in the introduction of spiro compounds into new studies.
Following the stated facts, the aim of this thesis was to synthesize and characterize polysubstituted piperidino-morpholine spiro building block. Furthermore, this scaffold was derivatized in order to obtain novel compounds with different properties, using the diversity-oriented synthesis approach. The scaffold was synthesized via two synthetic routes, in six or four reaction steps, with the last step of intramolecular cyclization under basic conditions. In several subsequent chemical reactions, the corresponding precursors were prepared from the main intermediate 6. Six novel derivatives 9a-c and 13a-c were obtained from compounds 8 and 12 with two free amino groups by N-acetylation, sulfonamidation and Eschweiler-Clarke reaction respectively. Structural diversity was achieved by substituting the scaffold at three different positions. The structures of the novel compounds were confirmed by standard spectroscopic methods (1D and 2D NMR, MS). Noticeable three-dimensionality of the structures of the final compounds 9a-c and 13a-c was proved by means of NOESY NMR spectra. Additionally, the physicochemical properties of final compounds were calculated in silico
Synthesis and biological activity of N-substituted benzoxazole
No full textU ovom radu opisana je sinteza novih derivata 2-benzoksazolinona u svrhu ispitivanja njihove biološke aktivnosti. Reakcijom nukleofilne supstitucije 5-supstituiranih 2-aminofenola i
1,1`-karbonildiimidazolom u tetrahidrofuranu pripravljeni su 5-supstituirani benzo[d]oksazol-2-oni (1a–c). 5-supstituirani N-propargilbenzo[d]oksazol-2-oni (2a–c) priređeni su reakcijom propargiliranja 5-supstituiranih benzo[d]oksazol-2-ona (1a–c) s propargil-bromidom u acetonu uz prisustvo kalijeva karbonata kao baze. Različito supstituirani 1-azidobenzeni (3a–e) potrebni za klik reakciju sintetizirani su reakcijom odgovarajućih supstituiranih anilina s natrijevim azidom u vodenoj otopini natrijeva nitrita. Huisgenovom 1,3-dipolarnom cikloadicijom kataliziranom bakrom N-propargiliranih benzoksazolona (2a–c) i odgovarajućih azidobenzena (3a–e) dobiveni su ciljani derivati benzoksazolinona supstituirani 1,2,3-triazolnim prstenom (4a–8c). Strukture sintetiziranih spojeva potvrđene su spektroskopijom 1H- i 13C-NMR.This paper describes the synthesis of new 2-benzoxazolinone derivatives with the aim of evaluating their biological activity. 5-substituted benzo[d]oxazol-2-ones (1a–c) were obtained by nucleophylic reaction of 5-substituted 2-aminophenols with 1,1`-carbonyldiimidazole in the tetrahydrofuran. 5-substituted N-propargylbenzo[d]oxazol-2-ones (2a–c) were prepared by the propargylation reaction of 5-substituted benzo[d]oxazol-2-ones (1a–c) with propargyl bromide in the acetone and in the presence of potassium carbonate as a base. Differently substituted 1-azidobenzenes (3a–e) were synthesized using corresponding substituted anilines with sodium azide in an aqueous solution of sodium nitrite. Finally, targeted benzoxazolinone derivatives substituted with 1,2,3-triazole ring (4a–8c) were prepared by copper catalyzed Huisgen's 1,3-dipolar cycloaddition reaction of N-propargylated benzoxazolones (2a–c) and corresponding azidobenzenes (3a–e). The structures of the synthesized compounds were confirmed by 1H- and 13C-NMR spectroscopy
Computational investigation of the interactions of organic pollutants and poly(ethylene terephthalate)
No full textPoli(etilen tereftalat) (PET) je široko korišten polimer, kojeg odlikuju izvrsna mehanička svojstva i kemijska otpornost. Zahvaljujući raširenoj uporabi, često dospijeva u okoliš, gdje se fragmentira na mikro- i nanočestice. U takvom obliku može ostvariti interakcije s raznim organskim onečišćivalima, što ima znatne okolišne implikacije. Ab initio metode pružaju mogućnost detaljnog istraživanja tih interakcija na atomskom nivou, što omogućuje razumijevanje temeljnih sila koje upravljaju vezivanjem organskih molekula na površinu
PET-a. U ovom radu provedeno je istraživanje interakcija između PET-a i dvaju organskih onečišćivala: fenola i anilina, korištenjem DFT metode M06L(GD3)/6-31G(d,p) za geometrijsku optimizaciju modelnih sustava PET-fenol i PET-anilin u softverskom paketu Gaussian. Energija interakcije određena je koristeći osnovni skup 6-31++G(d,p), kako bi se dodatno pokušale bolje opisati disperzijske interakcije. Nadalje, korištena je „counterpoise“ metoda kako bi se korigirala pogreška superpozicije osnovnih skupina. Dobivene energije kompleksacije sustava PET-fenol i PET-anilin su negativne, što ukazuje na stabilnost kompleksa. Međutim, analiza dekompozicije energije otkriva kako sustav PET-anilin ima jače disperzijske interakcije i manju repulziju, što rezultira stabilnijim kompleksom u usporedbi sa sustavom PET-fenol. Elektrostatske interakcije slične su u oba sustava, a parcijalni naboji dobiveni Merz-Kollman analizom ukazuju na jake negativne naboje na kisikovim atomima, što omogućuje stvaranje vodikovih veza. Vizualizacija elektrostatskog potencijala također ide u prilog tomu, pri čemu su kisikovi i dušikovi atomi ključni u stvaranju elektrostatskih interakcija.Poly(ethylene terephthalate) (PET) is a widely used polymer known for its excellent mechanical properties and chemical resistance. Due to its extensive use, it often ends up in the environment, where it fragments into micro- and nanoparticles. In these forms, it can interact with various organic contaminants, leading to significant environmental implications. Ab initio methods provide the opportunity to investigate these interactions in detail at the atomic level, enabling an understanding of the fundamental forces that govern the binding of organic molecules to the surface of PET. In this study, interactions between PET and two organic pollutants, phenol and aniline, were investigated using the DFT method M06L(GD3)/6-31G(d,p) for the geometric optimization of the interacting model systems, i.e., PET-phenol and PET-aniline in the Gaussian software package. The interaction energy was determined using the 6-31++G(d,p) basis set to better account for dispersion interactions. Furthermore, the "counterpoise" method was applied to correct for the basis set superposition error (BSSE). The resulting complexation energies for the PET-phenol and PET-aniline systems were negative, indicating favourable interactions and complex stability. However, the energy decomposition analysis revealed that the PET-aniline system exhibits stronger dispersion interactions and lower repulsion, leading to a more stable complex compared to the PET-phenol system. The electrostatic interactions were similar in both systems, with partial charges obtained from the Merz-Kollman analysis indicating significant negative charges on oxygen atoms, facilitating hydrogen bond formation. The visualization of the electrostatic potential further supported this, showing that oxygen and nitrogen atoms are key contributors to the electrostatic interactions
Transport vehicle cooling technologies
No full textTema završnog rada je pregled tehnologija hlađenja te usporedba pogona rashladnih kompresijskih sustava u transportu. Projektiran je rashladni kompresijski sustav dostavnog vozila rashladnog učinka 5 kW pri temperaturi isparavanja od -6 °C i pri temperaturi kondenzacije od 50 °C. Proces hlađenja je direktan, što znači da odabrano rashladno sredstvo propan (R290), hladi zrak koji nastrujava na proizvode koji se nalaze u rashladnom prostoru. Rad obuhvaća proračun toplinskih opterećenja rashladnog prostora, termodinamički proces te izračun učina kondenzatora i snage kompresora. Provedena je analiza potrošnje pogonske energije rashladnog kompresijskog sustava pri različitim temperaturama okoliša na dnevnoj i godišnjoj razini kao i usporedba emisija CO2 kada je isti rashladni kompresijski sustav pogonjen motorom s unutarnjim izgaranjem i baterijskim modulom.The topic of the thesis is a review of cooling technologies and a comparsion of a propulsion systems of refrigeration compression systems in transport. A refrigeration compression system with a capacity of 5 kW at an evaporation temperature of -6 °C and a condensation temperature of 50 °C was desgined. The cooling process is direct, meaning the selected refrigerant, propane (R290), cools the air flowing over the products located in the refrigerated space. The work includes the calculation of thermal loads of the refrigerated space, the thermodynamic process, the calculation of condenser efficiency and the power of the compressor. An analysis of the electric energy consumption of the refrigeration compression system at different ambient temperatures on a daily and yearly basis was conducted, as well as a comparsion of CO_2 emissions when the same refrigeration compression system is powered by an internal combustion engine and a battery module
Gamma-radiolytic degradation of loratadine in water
No full textLoratadin je antihistaminik koji se zbog česte upotrebe može pojaviti u otpadnim vodama što predstavlja rastući rizik za okoliš. Primjena ionizirajućeg zračenja pokazala se kao dobra alternativna metoda pročišćavanja otpadnih voda. U ovom radu provedena je razgradnja loratadina primjenom gama-zračenja. Utjecaj brzine i doze zračenja, te prisutnost različitih anorganskih soli i hvatača radikala na učinkovitost razgradnje određena je tekućinskom kromatografijom visoke djelotvornosti. Razgradni produkti analizirani su vezanim sustavom tekućinske kromatografije ultravisoke djelotvornosti i spektrometrije masa visokog razlučivanja. Na temelju MS i MS/MS spektara predložene su njihove strukture i razgradni put loratadina.Loratadine is an antihistamine which, because of the frequent use, can be found in wastewater, presenting a growing environmental risk. Ionizing radiation was found to be an effective alternative wastewater purification method. In this work degradation of loratadine by gamma irradiation was performed. The efficiency of degradation at different radiation rates and doses, in the presence of various inorganic salts and radical scavengers was investigated by high performance liquid chromatography. The degradation products were analysed by ultra high-performance liquid chromatography coupled to high-resolution mass spectrometry. Structures of degradants and degradation pathway of loratadine were proposed based on obtained results
Multilayered polymer nano-coatings of fatty acids on copper cross-linked by ionizing radiation
No full textSvakodnevni tehnološki napredak omogućava razvoj novih metoda sinteze i karakterizacije materijala, što potiče znanstvenike da istražuju i razvijaju nove i funkcionalnije prevlake koje mogu zadovoljiti specifične potrebe različitih industrija te pri tome biti ekološki prihvatljivi.
U ovom radu ispitana su zaštitna svojstva prevlaka nastalih samoorganizacijom molekula (SAM-ovi) četiri masne kiseline na površini bakra koje su potom umrežene ionizirajućim gama zračenjem. Prevlake neumreženih SAM-ova u korozijskim uvjetima nisu dugotrajno postojane te se relativno brzo uklone s površine. Primjenom gama zračenja inicira se polimerizacija masnih kiselina čime se postiže stabilnija, homogenija i dugotrajnija prevlaka. U ovome radu ispitana su zaštitna svojstva jednostavnih i slojevitih umreženih samoorganiziranih slojeva četiriju masnih kiselina (Crot, C6, C18 i C22) nanošenih metodom uranjanja. Zaštitna svojstva nastalih ispitana su elektrokemijskim metodama (metoda Tafelove ekstrapolacije i elektrokemijska impedancijska spektroskopija-EIS) u otopini koja simulira atmosferske uvjete, a prevlake su dodatno karakterizirane metodom kontaktnog kuta i termogravimetrijskom analizom. Dobiveni rezultati elektrokemijskih ispitivanja su pokazali da od jednostavnih prevlaka C22 prevlake pružaju najbolja zaštitna svojstva, C18 nešto slabija, a C6 najslabija zaštitna svojstva dok prevlake od Crot kiseline stvaraju zaštitu sličnu C22 prevlaci. Ispitivanja na slojevitim prevlakama pokazala su nešto slabija zaštitna svojstva, te od svih ispitivanih prevlaka C22 prevlaka je pokazala najbolja zaštitna svojstva. Vrijednosti kontaktnih kutova određene goniometrijom kod jednoslojnih prevlaka ukazuju na hidrofobnost svih prevlaka osim C6 prevlake, dok su od slojevitih prevlaka jedino kombinacije C6-C18 također hidrofilne, a ostale dvije kombinacije imaju hidrofobna svojstva. Termogravimetrijska analiza pokazuje da se razgradnja jednostavnih prevlaka odvija u jednom stupnju te da maksimalna temperatura raste s porastom duljine lanca. Razgradnja u dva stupnja se javlja kod većine slojevitih prevlaka, uz prvi pad mase bliži temperaturi određenoj za kraću masnu kiselinu, što ukazuje na manju termičku stabilnost u odnosu na jednostavne prevlake C18 i C22.Everyday technological progress enables the development of new methods of material synthesis and characterization, which encourages scientists to research and develop new and more functional coatings that meet the specific needs of different industries while being environmentally friendly. In this work, we tested the protective properties of the coatings created by the self-assembly of molecules (SAMs) of four fatty acids on the surface of copper, which were then cross-linked by ionizing gamma radiation. The coatings of
non-cross-linked SAMs are not long-lasting under corrosive conditions and are removed relatively quickly from the surface. The applying gamma radiation initiates the polymerization of fatty acids, resulting in a more stable, homogeneous and long-lasting coating. In this work, the protective properties of simple and layered cross-linked SAMs of four fatty acids (Crot, C6, C18, and C22) were investigated. The protective properties were tested by electrochemical methods (Tafel extrapolation method and electrochemical impedance spectroscopy-EIS) in a solution simulating atmospheric conditions, and the coatings were additionally characterized by the contact angle method and thermogravimetric analysis.
The results of the electrochemical tests showed that of the simple coatings, the C22 coatings had the best, the C18 coatings the slightly weaker and the C6 coatings the weakest protective properties. The Crot coatings offered only slightly weaker protection compared to the C22 coatings. Tests with layered coatings showed slightly weaker protective properties, and of all the tested coatings the C22 coating showed the best protective properties.
The contact angle values determined by goniometry for single-layer coatings indicate the hydrophobicity of all coatings except the C6 coating, while of the layered coatings, only the C6-C18 combinations are also hydrophilic, and the other two combinations have hydrophobic properties. Thermogravimetric analysis shows that the decomposition of simple coatings takes place in one step and that the maximum temperature increases with the increase in chain length. Degradation in two stages occurs with most layered coatings, with the first drop in mass closer to the temperature determined for the shorter fatty acid, which indicates lower thermal stability compared to simple C18 and C22 coatings
Design of battery pack mounting bracket as part of prototype battery-driven electric train development
No full textTema ovog završnog rada je konstruiranje i simuliranje nosača krovnih baterija vlaka putem programskog paketa CATIA na način da zadovolje normu HRN EN 12633. Nosače je potrebno izraditi iz legure AlZn10Si8Mg postupkom gravitacijskog lijevanja u pješčani kalup. Prije konstruiranja objašnjena je navedena norma, postupak lijevanja i razlog korištenja navojnih umetaka za vijčane spojeve. Zatim rad prikazuje iterativni postupak dolaska do konačnog proizvoda simuliranjem inačica nosača jednu za drugom unaprjeđujući ih sve do zadnje. Nakon dobivenog oblika konačnog nosača proizveden je 3D printani model koji služi za proizvodnju pješčanih kalupa. Korištenjem programskog paketa Altair Inspire Cast simulirano je lijevanje aluminijske legure u kalup i naznačeni potencijalni problemi prilikom lijevanja te je prikazan postupak lijevanja uživo. Na kraju rada nalaze se rezultati ispitivanja provedenih tokom proizvodnje nosača kako bi se usporedio nosač dobiven u programskom paketu sa stvarnim rezultatima ispitivanja.The subject of this final paper is the construction and simulation of train roof battery supports using the CATIA software package in such a way that the HRN 12633 standard is met. The supports must be made from the AlZn10SiMg alloy using gravity die casting into a sand mold. Before constructing, the stated norm, casting process and the reason for using threaded inserts for screw connections were explained. Then the paper shows the iterative process of working towards the final product by simulating the mounting bracket versions one after the other and improving them until the last one. After obtaining the shape of the final mounting bracket, a 3D printed model was produced, which is used for the production of sand molds. Using the software package Altair Inspire Cast, the casting of the Aluminium alloy into a mold was simulated and potential problems during the casting were indicated after which a live casting process was shown. At the end of the paper, the results of tests carried out during the production of the mounting brackets are shown so that real results could be compared to the ones obtained in the software packages