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Application of polymer blends in drug delivery
No full textDasatinib je antikancerogeni lijek koji se koristi u liječenju kronične mijeloične i akutne limfoblastične leukemije. Zbog svoje slabe topljivosti u vodenom mediju ima ograničenu bioraspoloživost. S ciljem povećanja njegove topljivosti i modifikacije profila oslobađanja, pripravljene su ternarne čvrste disperzije s poli(vinil-pirolidonom) i hidroksipropil-metil-celulozom mljevenjem u planetarnom kugličnom mlinu. Mehanokemijska aktivacija omogućuje pripravu bez primjene otapala poštujući načela zelene kemije, a istovremeno poboljšavaju topljivost i bioraspoloživost dasatiniba. Čvrste ternarne disperzije s polimernim mješavinama i granulati pomoćnih tvari korišteni su u pripravi tableta. Dobivene tablete karakterizirane su pomoću standardiziranih farmaceutskih testova u skladu s preporukama Europske farmakopeje. Rezultati testiranja pokazali su produljeno oslobađanje djelatne tvari uz poboljšanje topljivosti u usporedbi s čistim dasatinibom, što ukazuje na potencijalno poboljšanje bioraspoloživosti i terapijske učinkovitosti lijeka. Ovaj rad jasno ukazuje na potencijal polimernih mješavina za postizanje ciljanog profila oslobađanja, a time i poboljšanje bioraspoloživosti i efikasnosti dasatiniba, što može pridonijeti boljem ishodu liječenja leukemije.Dasatinib is an anticancer drug used in the treatment of chronic myeloid and acute lymphoblastic leukemia. Due to its poor solubility in aqueous medium, it has limited bioavailability. To increase its solubility and to modify drug release profile, ternary solid dispersions with polyvinylpyrrolidone and hydroxypropyl methylcellulose were prepared by milling in a planetary ball mill. Mechanochemical activation allows for preparation without the use of solvents, following the principles of green chemistry while simultaneously improving the solubility and bioavailability of dasatinib. Ternary solid dispersions and granulates of excipients were used in the preparation of tablets. Obtained tablets were characterized using standardized pharmaceutical tests in accordance with the European Pharmacopoeia recommendations. Testing results showed prolonged release of drug with an improvement in solubility when compared to pure dasatinib, indicating a potential enhancement in bioavailability and therapeutic efficacy of drug product. This thesis clearly indicates the potential of polymer blends to achieve aimed release profile, and thus enhacement of the bioavailability and efficiency of dasatinib, which may contribute to better treatment outcomes for leukemia
Antimicrobial coatings based on metal and metal oxide nanoparticles
No full textBakar je jedan od najpoznatijih antimikrobnih metala povezan s različitim antimikrobnim mehanizmima kao što su: permeabilizacija plazma membrane, lipidna peroksidacija membrane, izmjena proteina, inhibicija sastavljanja i aktivnosti proteina ili denaturacija nukleinskih kiselina. Nadalje, bakar u obliku nanomaterijala pokazuje veću antimikrobnu aktivnost te predstavlja novu klasu nano-antimikrobnih sredstava koja pružaju dodatne učinke i karakteristike u usporedbi s često korištenim nanočesticama srebra ili cinkovog oksida. Vlakna, pređe i drugi materijali obogaćeni nanočesticama bakra mogu se koristiti u različitim biomedicinskim i tekstilnim primjenama kao što su medicinski uređaji, zavoji za opekline ili rane, zdravstveni materijali (uključujući proizvode za jednokratnu upotrebu), proizvodi za osobnu njegu, veterinarski proizvodi, vojne i bio-obrambene stavke, zaštitna odijela ili odjeća. Ovaj rad stoga predstavlja primjenu Cu nanočestica u funkcionalizaciji površine medicinskog materijala. Biokompatibilne pređe dobivene elektropredenjem modificirane su primjenom sol-gel postupka tijekom kojeg su Cu nanočestice ugrađene u antimikrobne prevlake. Materijali su karakterizirani prije i nakon modifikacije pomoću FTIR, UV-VIS, SEM i DLS metoda. Rezultati su dokazali učinkovitu tvorbu novog antimikrobnog premaza koji je homogeno raspoređen na površini pređe. Osim toga, antimikrobni testovi Cu nanočestica dokazali su antimikrobno svojstvo Cu nanočestica u prevlakama, omogućujući buduću primjenu biopolimera kao novih medicinskih materijala.Copper is one of the most widely recognized antimicrobial metal linked to multiple antimicrobial mechanisms such as: plasma membrane permeabilization, membrane lipid peroxidation, alteration of proteins, inhibition of protein assembly and activity, or denaturation of nucleic acids. Moreover, copper in a form of nanomaterials shows grater antimicrobial activity so is an emerging class of nano-antimicrobials providing complimentary effects and characteristics, as compared to widely used silver or zinc oxide nanoparticles. Metal nanoparticle-loaded yarns can be used in a number of biomedical and textile applications such as medical devices, burn or wound dressings, healthcare materials (including disposables), personal care products, veterinary, military and bio-defense items, protective suits or clothing. This work therefore presents application of Cu nanoparticles in functionalization of the surface of medical material by deep coating method. Electrospun biocompatible yarns were modified by using sol-gel procedure during which the Cu nanoparticles were incorporated within the coating. The materials were characterized before and after the modification by FTIR, UV-VIS, SEM and DLS methods. The results proved efficient formation of a novel antimicrobial coating homogeneously distributed on the surface of the yarns. Additionally, antimicrobial tests of Cu nanoparticles proved the antimicrobial property of Cu nanoparticles in coating, enabling future application of novel medical materials
Organic pollutants in indoor air
No full textU ovom radu naglasak je bio na analizi onečišćenja zraka u zatvorenim prostorima. Onečišćujuće tvari u zatvorenim prostorima mogu potjecati od uobičajenih predmeta koji se nalaze u kućanstvima, kao što su namještaj, tepih, sredstva za čišćenje, uređaji za kuhanje i drugi. Onečišćenje unutrašnjeg zraka može biti puno izraženije od onečišćenja vanjskog zraka. Dozvoljene koncentracije onečišćujućih tvari vanjskog zraka propisane su zakonima i direktivama, međutim kvaliteta unutrašnjeg zraka nije regulirana. U ovom radu određene su koncentracije PM1 frakcije lebdećih čestica (čestice aerodinamičkog promjera 1 μm ili manje) te sadržaj policikličkih aromatskih ugljikovodika (PAH) u PM1 frakciji. Uzorkovanje je provedeno u kućanstvima na području Zagreba i okolice. Za čestice PM1 Direktivom o kvaliteti zraka i čišćem zraku za Europu (EU, 2008) nisu propisane granične vrijednosti, iako mogu biti opasnije po ljudsko zdravlje od čestica PM2,5 i PM10 jer se mogu lakše distribuirati po tijelu zbog svojih dimenzija. Najviša masena koncentracija PM1 frakcija čestica, kao i najviša masena koncentracija svih PAH-ova izmjerena je u uzorku uzorkovanom u kućanstvu na području naselja Trstenik. Osim Trstenika povećana koncentracija PM1 i PAH-ova izmjerena je u kućanstvu u Sigetu i Jarunu. Uočene su značajne prostorne razlike što ukazuje na nužnost daljnjih istraživanja koje će uzeti u obzir brojne čimbenike kao što su kvaliteta vanjskog zraka, fizičke karakteristike kućanstva i same navike ukućana. Dominantni PAH-ovi na gotovo svim mjernim mjestima su benzo[b]fluoranten (BbF), benzo[a]piren (BaP), benzo[ghi]perilen (BghiP) i indeno[1,2,3-cd]piren (IP). Na temelju specifičnih omjera pojedinačnih PAH-ova izvedeni su zaključci o potencijalnim izvorima onečišćenja (fosilna goriva, sagorijevanje ugljena). Utvrđen je veći doprinos PAH-ova s većim brojem prstenova u odnosu PAH-ove s 2 ili 3 prstena. Izračunati mutageni ekvivalent za detektirane PAH-ove u uzorcima iznosio je 0,439 ng/m^3, dok je karcinogeni ekvivalent iznosio 0,313 ng/m^3. Dobiveni rezultati potvrdili su prikladnost BaP-a kao markera mutagenog i kancerogenog potencijala različitih PAH-ova u zraku. Razine za dobivene ekvivalente su bile niske, stoga nisu ukazivale na lošu kvalitetu unutarnjeg zraka s obzirom na PAH-ove.The focus of this work was on the analysis of indoor air pollution. Indoor pollutants can come from typical household items such as furniture, carpets, cleaning products, cooking appliances and much more. Indoor air pollution can be much worse than outdoor air. While the concentrations of pollutants in outdoor air are regulated by laws and directives, there are no regulations for indoor air quality. The concentrations of the PM1 fraction (particles with an aerodynamic diameter of 1 μm or less) of particulate matter and the composition of polycyclic aromatic hydrocarbons (PAH) in the PM1 fraction were determined, and sampling was carried out in households in the Zagreb area and its surroundings. The Air Quality and Cleaner Air for Europe Directive (EU, 2008) does not set limit values for PM1, although they can be more dangerous to human health than PM2.5 and PM10 particles because their size makes them easier to disperse in the body. The highest mass concentration of PM1 particle fractions and the highest mass concentration of all PAHs were measured in the sample taken from a household in the Trstenik. In addition to Trstenik, elevated concentrations of PM1 and PAHs were also measured in households in Siget and Jarun. Significant spatial differences were observed, which indicates the necessity of further research that will take into account numerous factors such as the quality of the outdoor air, the physical characteristics of the household and the habits of the householders themselves. The dominant PAHs at almost all measurement sites are benzo[b]fluoranthene (BbF), benzo[a]pyrene (BaP), benzo[ghi]perylene (BghiP), and indeno[1,2,3-cd]pyrene (IP ). Based on the specific ratios of the individual PAHs, conclusions were drawn about possible sources of pollution (fossil fuels, coal combustion). A greater contribution was found from PAHs with a larger number of rings than from PAHs with 2 or 3 rings. The calculated mutagenic equivalent for the PAHs detected in the samples was 0.439 ng/m^3, while the carcinogenic equivalent was 0.313 ng/m^3.
The results obtained confirm the suitability of BaP as a marker for the mutagenic and carcinogenic potential of various PAHs in the air. The values determined for the equivalents were low and therefore not indicative of poor indoor air quality in view of PAHs
Oxidation of glucose catalyzed by glucose dehydrogenase in a batch reactor
No full textU današnje vrijeme sve je veći jaz između energetskih potreba i ograničenih izvora energije kao što su to fosilna goriva. Zbog toga se sve više istražuju obnovljivi energenti kao što je to primjerice vodik. Vodik se smatra jednim od najperspektivnijih izvora energije budućnosti jer ima visok energetski prinos. Vodik proizveden iz bioloških izvora naziva se biovodik te danas predstavlja jedan od najzanimljivijih obnovljivih izvora energije. Jedan od načina proizvodnje biovodika je i enzimska konverzija glukoze u glukonsku kiselinu uz regeneraciju koenzima i paralelnu proizvodnju molekularnog vodika. U okviru ovog istraživanja provedena je oksidacija glukoze katalizirana enzimom glukoza dehidrogenaza (GDH) iz Pseudomonas sp. uz koenzim NAD+ u kotlastom reaktoru. U prvom dijelu istraživanja provedena je karakterizacija enzima GDH iz Pseudomonas sp. na način da su određeni temperaturni i pH optimum za provedbu reakcije, te je odabran najbolji pufer. Rezultati su pokazali kako je optimalna temperatura za provedbu reakcije 40 ℃, pH 7 te pufer 0,1 mol/L TRIS-HCl pH 7.
U drugom dijelu istraživanja ispitana je reakcijska kinetika oksidacije glukoze metodom početnih brzina te su procijenjeni kinetički parametri. Kinetika oksidacije glukoze katalizirane GDH iz Pseudomonas sp. opisana je dvosupstratnom Michaelis–Menteničinom kinetikom s inhibicijom supstratom i kompetitivnom inhibicijom produktom. Za reakciju provedenu u kotlastom reaktoru postavljen je odgovarajući reaktorski model, koji se sastojao od kinetičkog modela i bilanci tvari za sve komponente reakcijske smjese. Ocjena valjanosti modela provedena na dva seta nezavisnih eksperimenata.In today's world, there is a growing gap between energy demand and limited energy sources such as fossil fuels. As a result, renewable energy sources such as hydrogen are increasingly being researched. Hydrogen is considered one of the most promising energy sources of the future, as it has a high energy yield. Hydrogen produced from biological sources is known as biohydrogen and is one of the most interesting renewable energy sources today. One way of producing biohydrogen is the enzymatic conversion of glucose into gluconic acid with the regeneration of coenzymes and the parallel production of molecular hydrogen. In this study, glucose oxidation, catalyzed by the enzyme glucose dehydrogenase (GDH) with the coenzyme NAD+ was carried out in a batch reactor. In the first part of the study, the characterization of the enzyme GDH was performed by determining the optimal temperature and pH for the reaction and selecting the best buffer. The results showed that the optimal temperature for the reaction is 40°C, pH 7, and the buffer is
0.1 mol/L TRIS-HCl pH 7. In the second part of the study, the reaction kinetics of glucose oxidation was investigated using the initial rate method, and the kinetic parameters were estimated. The kinetics of glucose oxidation catalyzed by GDH is described by two-substrate Michaelis-Menten kinetics with substrate inhibition and competitive product inhibition.
A suitable reactor model was developed for the reaction carried out in the batch reactor, consisting of a kinetic model and mass balances for all components of the reaction mixture. The validation of the model was evaluated using two sets of independent experiments
The development and application of a system for drying under supercritical conditions
No full textTeorijski pregled superkritičnih tekućina, njihovih svojstava i primjena. Poseban naglasak je stavljen na sušenje pri superkritičnim uvjetima, gdje su teorijski proučeni procesi, kinetika i modeli sušenja pri superkritičnim uvjetima. Unutar rada navedeni su patenti i proizvodi napravljeni uz pomoć sušenja pri superkritičnim uvjetima. Opisani su tehnički zahtjevi za konstrukciju aparatura, kao i komercijalno raspoloživi sustavi na razini laboratorija sve do industrijske razine.Theoretical review of supercritical fluids, their properties, and their application. Special emphasis is placed on drying under supercritical conditions, where the processes, kinetics, and models of drying under supercritical conditions are theoretically studied. The patents and products made using drying under supercritical conditions are also reviewed.
The technical requirements for the construction of apparatuses, as well as commercialy available systems ranging from laboratory to industrial scale, are described
Development and validation of a method for the determination of heavy metals in water using the ICP-MS technique
No full textU ovom je radu provedena validacija metode detekcije teških metala tehnikom masene spektrometrije povezane s induktivno spregnutom plazmom (engl. Inductively coupled plasma mass spectrometry, ICP-MS). Za postupak validacije korištene su temeljne standardne otopine (TSO) 19 elemenata (Ag, Al, As, Ba, Cd, Cr, Fe, Hg, K, Mn, Na, Ni, P, Pb, S, Sb, Se, V i Zn). Određeni parametri validacije su linearnost, preciznost, radno područje, granica detekcije (GD), granica kvantifikacije (GK) i istinitost. Validirana metoda je zatim primijenjena za određivanje elemenata u realnim uzorcima: voda sa ulaza i izlaza uređaja za pročišćavanje voda akumulacijskog jezera hidroelektrane (HE) s područja vapnenačkih stijena i na morski sediment iz područja srednjeg i južnog Jadrana. Uzorak sedimenta podvrgnut je kiseloj digestiji u zatvorenim teflonskim posudama u mikrovalnoj pećnici koristeći HNO3, HCl i HF. Optimalni uvjeti razgradnje uzorka sedimenta postignuti su u trećoj digestiji nakon 10 minuta, pri snazi od 400 W i volumenima kiselina; 1 mL HCl, 3 mL HNO3 i 1 mL HF. Rezultati analize pokazuju kako su u uzorku sedimenta prisutni Al, Fe, P i V. Rezultati dobiveni za uzorke vode na ulazu i izlazu iz uređaja za pročišćavanje vode akumulacijskog jezera HE pokazuju da su na ulazu povišene koncentracije S i Zn. Bitno je da su na izlazu iz uređaja za pročišćavanje vode svi elementi uspješno uklonjeni.In this study, the validation of the method for detecting heavy metals using inductively coupled plasma mass spectrometry (ICP-MS) was carried out. Fundamental standard solutions (FSS) of 19 elements (Ag, Al, As, Ba, Cd, Cr, Fe, Hg, K, Mn, Na, Ni, P, Pb, S, Sb, Se, V, and Zn) were used for the validation process. The specific validation parameters were linearity, precision, working range, limit of detection (LOD), limit of quantification (LOQ), and accuracy. The validated method was then applied to determine the elements in real samples: water from the inlet and outlet of a water treatment device of a hydroelectric reservoir (HE) in an area of limestone rocks, and in marine sediment from the central and southern Adriatic Sea. The sediment sample was subjected to acid digestion in closed Teflon vessels in a microwave oven using HNO3, HCl, and HF. The optimal conditions for sediment sample decomposition were achieved in the third digestion after 10 minutes and with the following acid volumes: 1 mL of HCl, 3 mL of HNO3, and 1 mL of HF. The analysis results show that Al, Fe, P, and V are present in the sediment sample. The results obtained for the water samples at the inlet and outlet of the hydroelectric reservoir water treatment device show elevated concentrations of S and Zn at the inlet. Importantly, all elements were successfully removed at the outlet of the water treatment device
Rheological behaviour of polycaprolactone (PCL)/thermoplastic starch (TPS) blends
No full textU današnje vrijeme, sve veća pažnja usmjerava se prema očuvanju okoliša i biorazgradivosti materijala. Zbog toga se sve više primjenjuju biorazgradivi polimeri poput škroba. Škrob je prah kojeg je potrebno plastificirati da bi se dobro iskoristila njegova svojstva: mekoća, niska cijena i visoki postotak biorazgradivosti. On prelazi u termoplastični škrob (TPS) djelovanjem mehaničke i toplinske energije u prisustvu plastifikatora. Pripravom TPS-a dolazi do potpunog narušavanja kristalne strukture te se dobije potpuno amorfni polimer. Umješavanjem TPS-a s drugim polimerima pokušava se dobiti ekološki prihvatljivije polimere zbog njihove biorazgradivosti. Miješanje TPS-a sa polikaprolaktonom (PCL) daje sustav
TPS/PCL poboljšanih nekih svojstava i moguće šire primjene. Primjer upotrebe TPS/PCL sustava je za proizvodnju vrećica za pakiranje hrane, čija primjena raste zahvaljujući porastu ekološke osviještenosti, a sve u cilju povećanja uporabe biorazgradivih polimera. Dodatno, sve se više rabi u medicinske svrhe. Kod priređenih TPS/PCL mješavina ispitano je njihovo reološko ponašanje te su uz pomoć dinamičko-mehaničke (toplinske) analize (DMTA) istražena mehanička svojstva. Mjerenja na oscilacijskom reometru provedena su ispitivanjem u frekvencijskom području od 0,1 do 100 rad/s pri amplitudi deformacije 0,5% te pri stalnoj temperaturi od 120 °C. Određeno je područje linearne viskoelastičnosti s obzirom na ovisnost modula pohrane o amplitudi deformacije koja je mjerena na 120 °C pri frekvenciji od 1 Hz. Kod DMTA metode se torzijski djelovalo na uzorke u temperaturnom rasponu od -80 °C do 160 °C. Djelovanjem torzije dolazilo je do deformacije ili loma uzorka ovisno o omjeru TPS-a i PCL-a u mješavini. Analiza uzoraka pokazala je da porastom udjela PCL-a dolazi do smanjenja viskoznosti sustava. Najveća viskoznost zabilježena je u sustavu TPS/PCL (80/20). Zbog toga se sustavi udjela TPS-a većeg od 30 mas.% ponašaju kao gelovi te imaju veću otpornost na deformacije, a sustavi manjeg udjela ponašaju se poput tekućina. Dodatkom punila titanijeva dioksida TiO2 mijenjaju se morfološka svojstva i kristalnost mješavina što otvara dodatnu mogućnost kontrole svojstava i utjecaja na njih.In today's world, increasing attention is being directed towards environmental preservation and biodegradability of materials. As a result, biodegradable polymers such as starch are being increasingly applied. Starch is a powder that needs to be plasticized to fully utilize its properties: softness, low cost, and high biodegradability. It transforms into thermoplastic starch (TPS) under the influence of mechanical and thermal energy in the presence of a plasticizer. The preparation of TPS completely disrupts the crystalline structure, resulting in a fully amorphous polymer. By blending TPS with other polymers, efforts are being made to create more environmentally friendly polymers due to their biodegradability. Mixing TPS with polycaprolactone (PCL) produces a TPS/PCL system with improved properties and potentially broader applications. An example of the use of the TPS/PCL system is in the production of food packaging bags, whose application is growing thanks to the rise in environmental awareness, all aimed at increasing the use of biodegradable polymers. Additionally, it is increasingly used for medical purposes. The rheological behavior of prepared TPS/PCL mixtures was examined, and mechanical properties were investigated using dynamic mechanical (thermal) analysis (DMTA). Measurements on an oscillatory rheometer were conducted by testing in a frequency range from 0.1 to 100 rad/s at a deformation amplitude of 0.5% and a constant temperature of 120 °C. The linear viscoelastic region was determined based on the dependence of the storage modulus on the deformation amplitude measured at 120 °C at a frequency of 1 Hz. In the DMTA method, the samples were subjected to torsion in the temperature range from -80 °C to 160 °C. The torsional action caused deformation or fracture of the sample depending on the ratio of TPS to PCL in the mixture. Analysis of the samples showed that increasing the PCL content decreases the viscosity of the system. The highest viscosity was recorded in the TPS/PCL (80/20) system. Therefore, systems with a TPS content greater than 30 wt.% behave like gels and have greater resistance to deformation, while systems with lower content behave like liquids.
The addition of titanium dioxide (TiO2) filler alters the morphological properties and crystallinity of the mixtures, offering an additional possibility to control and influence their properties
Preparing of titanium oxide hierarchical nanostructures by means of scarifying nanostructured zincite template
No full textRazvojem nanotehnologije povećao se interes za istraživanje nanomaterijala, a među oksidima prijelaznih metala, nanostrukture TiO2 su najistraživaniji poluvodički materijali u proteklim godinama. Razlog tome je njegova široka primjenjivost u različitim područjima, uključujući solarne ćelije, ali i druge primjene u kojima do izražaja dolaze i njegova dobra optička, električna i kemijska svojstva. Cilj rada je ispitati mogućnost priprave nanostrukturiranih filmova titanijeva dioksida koristeći cinkit kao žrtveni predložak kako bi se izbjegla potreba za kontrolom samoorganizacije. Glavni je cilj transformacija nanoštapića cinkita, koji služe kao žrtveni predložak, u željene nanostrukture titanijeva (IV) oksida. Nakon priprave, uzorci se karakteriziraju strukturnim, mikrostrukturnim i sastavnim metodama kako bi se bolje razumjela njihova morfološka i kemijska svojstva.With the development of nanotechnology, there has been an increased interest in nanomaterials research. In recent years, titanium dioxide (TiO2) structures have been the most studied semiconductor materials among transition metal oxides. The reason for this is their wide applicability in various fields including solar cells and other applications in which their good optical, electrical, and chemical properties play crucial roles. This master thesis aims to examine the possibility of preparing TiO2 nanostructured films using zincite as the sacrificial template with which the need for self-organizational control is avoided. The primary goal is the transformation of the zincite nanorods, functioning as sacrificial templates, into the wanted TiO2 nanostructures. After the preparation, the samples are characterized with structural, microstructural and compositional methods for a better understanding of their morphological and chemical properties
Application of self-assembled monolayers of organic acids in bronze and patina protection
No full textBrončana kulturna baština izložena vanjskom okolišu podložna je degradaciji uslijed korozivnog djelovanja vlage i onečišćenja iz zraka. U praksi se primjenjuju različite metode korozijske zaštite bronce i brončane patine, no zbog specifičnih zahtjeva konzervatorske struke odabir tih metoda je limitiran, a često ih karakterizira nedovoljna trajnost postignute zaštite. Zbog toga je potrebno razviti nove poboljšane postupke njene zaštite. S tim ciljem je u ovom radu ispitana mogućnost primjene dugolančanih fosfonskih kiselina za korozijsku zaštitu čiste i patinirane površine bronce te za poboljšanje adhezije i zaštitnih svojstava transparentnih organskih premaza na navedenim supstratima. S obzirom da postupak formiranja filma može utjecati na njegovu uređenost i stabilnost, istraženo je dobivanje filmova fosfonske kiseline na čistoj površini bronce metodama kista, prskanja i uranjanja. Metodama kista i prskanja, koje su praktičnije za upotrebu na skulpturama, dobivaju se filmovi koji pokazuju nešto veću stabilnost u korozivnom mediju, no reproducibilniji i uređeniji filmovi dobivaju se metodom uranjanja stoga je ova metoda korištena za daljnja istraživanja. Istražen je i utjecaj duljine lanca i završne funkcionalne skupine na uređenost i zaštitna svojstva samoorganiziranih filmova pri čemu je utvrđeno da kiseline s duljim lancem formiraju uređene filmove dok kiselina s kraćim lancem formira film nižeg stupnja uređenosti. Unatoč slabijoj uređenosti filma, kiselina s kraćim lancem pruža visoki stupanj zaštite pri dovoljnoj debljini filma. U idućem koraku ispitan je utjecaj sastava brončane podloge na formiranje samoorganizirajućih filmova fosfonske kiseline. Istraživanje je provedeno na podlogama od cinka, kositra i bakra, kao najčešćim legirnim elementima u bronci, te na tri vrste bronci. Pokazalo se da se na svim ispitivanim podlogama mogu formirati zaštitni filmovi, ali da njihova učinkovitost i stabilnost ovise o korozijskoj stabilnosti supstrata. Podloge koje su manje otporne na koroziju zaštićene su u kraćem periodu jer otapanje podloge dovodi do otapanja zaštitnog filma. U ovom su radu fosfonske kiseline također ispitane kao molekularni promotori adhezije dvaju akrilnih i jednog poliuretanskog premaza na čistoj bronci. Bronca je prije nanošenja premaza tretirana fosfonskim kiselinama te su ispitane različite metode uklanjanja gornjih slabije vezanih slojeva filma kako bi adhezija premaza bila uspješnija. Fosfonske kiseline poboljšale su zaštitna svojstva i adheziju akrilnog premaza Paraloida B72 i poliuretanskog premaza te su inhibirale otapanje bronce. U konačnici je pokazano da samoorganizirajući filmovi fosfonske kiseline doprinose i korozijskoj zaštiti patinirane bronce izložene korozivnom mediju te da također poboljšavaju zaštitna svojstva Paraloida B72 na takvoj površini. Korozijska zaštita koju pružaju ispitivani sustavi određena je na temelju elektrokemijskih ispitivanja (polarizacijska mjerenja i elektrokemijska impedancijska spektroskopija) uzoraka izloženih korozivnom djelovanju umjetne kisele kiše. Dio uzoraka dodatno je bio izložen djelovanju vanjske urbane atmosfere, odnosno agresivnim uvjetima u vlažnoj komori s NO2. Izgled uzoraka prije i nakon izlaganja korozivnom mediju karakteriziran je elektronskom i optičkom mikroskopijom. Uređenost filmova i način vezanja na površinu utvrđeni su spektroskopskim (FTIR, XPS, SFG) tehnikama te TOF-SIMS spektrometrijom. Dodatno su modificirane brončane površine karakterizirane goniometrijom. Adhezija premaza na brončani supstrat određena je na temelju ispitivanja vlačnom (pull-off) metodom.Bronze cultural heritage exposed to the outdoor environment is susceptible to degradation due to the corrosive effects of moisture and air pollution. In practice, various methods of corrosion protection of bronze and bronze patina are used, but due to the specific requirements of the conservation profession, the choice of these methods is limited, and they are often characterized by insufficient durability of the achieved protection. It is therefore necessary to develop new and improved methods of their protection. With this aim, the possibility of using long-chain phosphonic acids for corrosion protection of a bare and patinated bronze surface, as well as for improving the adhesion and protective properties of transparent organic coatings on these substrates was examined in this work. Given that the method of organic film formation can influence on its structure and stability, obtaining phosphonic acid films on a clean bronze surface by brushing, spraying and dip coating was investigated. The brushing and spraying methods, which are more practical for use on sculptures, produce films with slightly greater stability in a corrosive medium, however more reproducible and well-organized films are obtained by the dip coating method, so this method was used for further investigations. The influence of chain length and the terminal functional group of phosphonic acid on the crystallinity and protective properties of the self-assembled films was also investigated. It was found that acids with a longer chain form more ordered films, while acids with a shorter chain form film with a lower degree of order. Despite the lower crystalinity of the film, the acid with a shorter chain provides a high degree of protection when a sufficient film thickness is achieved. In the next step, the influence of the composition of the bronze substrate on the formation of self-assembled films of phosphonic acid was examined. The research was conducted on substrates made of zinc, tin and copper, the most common alloying elements in bronze, and on three types of bronze. It was found that protective films can be formed on all substrates, but their effectiveness and stability depend on the corrosion stability of the substrate. Substrates that are less corrosion resistant are protected for a shorter period of time, as the dissolution of the substrate leads to the dissolution of the protective film. In this work, selected phosphonic acids were also tested as molecular promoters of the adhesion of two acrylic and one polyurethane coating on pure bronze. Before applying the coating, the bronze was treated with phosphonic acids. Different methods were tested to remove the weakly bonded upper layers of the film in order to improve the adhesion of the coating. Phosphonic acids improved the protective properties and adhesion of the acrylic coating Paraloid B72 and the polyurethane coating, and inhibited the dissolution of the bronze. Finally, it was shown that self-assembled films of phosphonic acid contribute to the corrosion protection of patinated bronze exposed to a corrosive medium and improve the protective properties of Paraloid B72 on such surface. The corrosion protection provided by the studied systems was examined by electrochemical tests (polarization measurements and electrochemical impedance spectroscopy) on samples exposed to the corrosive effect of artificial acid rain. Some of the samples were additionally exposed to the effect of the outdoor urban atmosphere and to aggressive conditions in a humid chamber with NO2. The surface appearance of the samples before and after exposure to the corrosive medium was characterized by electron and optical microscopy. The structure of the films and their binding to the surface were examined by spectroscopic methods
(FTIR, XPS, SFG) and TOF-SIMS spectrometry. In addition, the modified bronze surfaces were characterized by goniometry. The adhesion of the coating to the bronze substrate was determined based on a pull-off test
Presence of COVID-19 drugs in the environment
No full textNakon pojave virusa COVID-19 zbog visoke zaraznosti i velike stope smrtnosti te nepostojanja učinkovitog cjepiva pristupilo se prenamjenjivanju lijekova razvijenih i korištenih za druga virusna oboljenja. Velik broj zaraženih sa sobom je povukao i veliku količinu korištenih farmaceutika koje postrojenja za obradu otpadnih voda nisu bila u mogućnosti ukloniti. Iz tog je razloga značajno porasla koncentracija farmaceutika detektiranih u površinskim vodama. Prisutnost ovih farmaceutika u okolišu predstavlja potencijalni rizik za ekosustave i ljudsko zdravlje. Ekotoksičnost ovih lijekova može imati negativan utjecaj na vodene organizme i ostale biološke vrste, čime se narušava ravnoteža ekosustava. Ovaj rad daje pregled najčešće korištenih farmaceutika za tretiranje bolesti COVID-19, njihove prisutnosti u okolišu, ekotoksikoloških ispitivanja provedenih sa svrhom ispitivanja utjecaja ovih lijekova na okoliš te načina njihovog mogućeg uklanjanja.After the emergence of COVID-19 virus because of its infectibility and high death rate as well as non-existence of effective vaccine, repurposing of drugs made and used for other viral diseases was approached. A great number of infected caused a great amount of used pharmaceuticals that couldn’t be removed in wastewater treatment plants. For that reason there was a considerable rise in concentration of pharmaceuticals detected in surface waters. Presence of these pharmaceuticalse in the environment poses a potential risk for ecosystems and human health. Ecotoxicity of these pharmaceuticals can have a negative effect on water organisms and other biological species, which causes an imbalance in the ecosystem. This study provides an overview of the most commonly used pharmaceuticals for COVID-19 treatment, their presence in the environment, ecotoxicological experiments carried out with aim of observing the effect of said pharmaceuticals on the environment, as well as possible methods of their removal