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Surface modification of cobalt-chromium based implant materials
No full textPotreba za razvojem implantne tehnologije sve se više javlja zbog porasta broja starije populacije koja je sklona oštećenjima koštanih tkiva. Implantni materijali moraju biti sposobni imitirati strukturu i mehanička svojstva tkiva, organa ili kosti kako bi implantati u konačnici uspješno nadomjestili funkciju strukture za zamjenu. No, ugradnjom metalnih implantnih materijala u agresivni okoliš ljudskog tijela može doći do korozije (degradacije) materijala te je stoga važno istražiti korozijsku otpornost istih. Legura na bazi kobalt-krom-molibdena (CoCrMo) koristi se za izradu ortopedskih implantata zbog svojih superiornih mehaničkih svojstava i dobre korozijske otpornosti, ali ista nije bioaktivna. Stoga se u ovom radu, modifikacijom površine legure stvaranjem prevlake na bazi kalcijevih fosfata (CaP), nastoje povećati korozijska otpornost i stupanj bioaktivnosti. Formiranjem CaP prevlake na površini CoCrMo legure kombiniraju se mehanička svojstva metalne legure sa osteokonduktivnim svojstvima kalcijevih fosfata. Modifikacija površine CoCrMo legure provedena je metodom elektrodepozicije; uvjeti elektrodepozicije određeni su metodom cikličke voltametrije (CV). Uspješnost formiranja prevlake potvrđena je optičkom mikroskopijom (OM) i infracrvenom spektroskopijom s Fourierovom transformacijom uz prigušenu totalnu refleksiju (ATR – FTIR). Usporedba elektrokemijskog ponašanja nemodificirane CoCrMo legure i CaP modificirane legure provedena je korištenjem izmjeničnih i istosmjernih elektrokemijskih metoda, koje uključuju metodu određivanja polarizacijskog otpora (eng. Linear Polarization Resistance LPR), metodu Tafelove ekstrapolacije i elektrokemijsku impedancijsku spektroskopiju (EIS) provedenu u simuliranoj tjelesnoj tekućini, Hanksovoj otopini u in vitro uvjetima.The need for development of implant technology is rising due to the increasing proportion of the elderly population who are prone to bone tissue damage. Implant materials must be able to imitate the structure and mechanical properties of tissue, organe or bones in order for implants to successfully replace the functionality of wanted structure. However, after the implantation of metallic implant materials into the aggressive environment of the human body, corrosion (degradation) of the material can occur, so the corrosion resistance of metallic implant materials is examined. An alloy based on cobalt-chromium-molybdenum (CoCrMo) is used as an orthopeadic implant due to its superior mechanical properties and good corrosion resistance, but this alloy is not bioactive. Hence, in this work the CaP coating is formed on the surface of CoCrMo alloy in order to increase the corrosion resistance and bioactivity. The formation of CaP coating on the alloy surface combines the mechanical properties of metal alloy with the osteoconductive properties of CaP materials. Surface modificitaion was performed by electrodeposition method with electrodeposition conditions determined by cyclic voltammetry (CV) method. The successful formation of CaP coating was confirmed by optical microscopy (OM) and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR). The comparison of electrochemical behaviour of unmodified and CaP modified CoCrMo alloy was performed using ac and dc electrochemical methods, including linear polarization resistance (LPR), Tafel extrapolation method and electrochemical impedance spectroscopy (EIS) performed in simulated body fluid, Hank’s solution under in vitro conditions
Categorization of fuel from waste
No full textProizvodnja otpada kontinuirano raste diljem svijeta, što predstavlja sve veći izazov za okoliš, društvo i gospodarstvo. Istovremeno, postaje sve važnije osigurati pristup održivoj energiji koja je dostupna svima. U ovom kontekstu, Waste-to-Energy (WtE) tehnologija, koja omogućuje konverziju otpada u energiju, predstavlja učinkovito rješenje za ove izazove. Otpad često sadrži komponente s visokim energetskim potencijalom koje se mogu iskoristiti za proizvodnju goriva. Time se ne samo smanjuje količina otpada koja završava na odlagalištima, već se otpad koristi kao vrijedan resurs. WtE tehnologija također pridonosi ostvarenju ciljeva kružnog gospodarstva jer potiče kružni tok materijala i energije. Umjesto jednostavnog odbacivanja otpada, ovaj pristup omogućuje njegovu pretvorbu u korisno gorivo. Kroz kategorizaciju goriva dobivenog iz različitih vrsta otpada, postiže se pravilno upravljanje otpadom, identifikacija energetskog potencijala materijala te određivanje najprikladnijih postupaka obrade i korištenja. Ova praksa osigurava da se proizvedeno gorivo iz otpada ispunjava specifične zahtjeve i da se koristi na način koji je u skladu s relevantnim smjernicama i propisima. Cilj ovog završnog rada je pružiti dublje razumijevanje kategorizacije goriva iz otpada, istražiti njezinu ulogu u održivom gospodarenju otpadom te analizirati izazove i poteškoće s kojima se susrećemo prilikom kategorizacije goriva iz otpada i njegove prakse korištenja.The production of waste is continuously increasing worldwide, presenting a growing challenge for the environment, society, and the economy. At the same time, it is becoming increasingly important to ensure access to sustainable energy that is available to everyone. In this context, Waste-to-Energy (WtE) technology, which enables the conversion of waste into energy, represents an effective solution to these challenges. Waste often contains components with high energy potential that can be utilized for fuel production. This not only reduces the amount of waste ending up in landfills but also uses waste as a valuable resource. WtE technology also contributes to achieving circular economy goals by promoting the circular flow of materials and energy. Instead of simply discarding waste, this approach allows for its conversion into useful fuel. Through the categorization of fuel derived from different types of waste, proper waste management is achieved, the energy potential of materials is identified, and the most appropriate processing and utilization methods are determined. This practice ensures that the produced fuel from waste meets specific requirements and is used in a manner consistent with relevant guidelines and regulations. The aim of this final paper is to provide a deeper understanding of the categorization of fuel from waste, explore its role in sustainable waste management, and analyze the challenges and difficulties encountered in the categorization of fuel from waste and its practical use
Application of self-assembled monolayers for corrosion protection of metallic implant materials
No full textU današnjoj medicini, sve se veća pažnja pridaje implantnim materijalima koji u ljudskom tijelu služe kao zamjena kostiju, zubi i drugih oštećenih bioloških struktura. Titanij i njegove legure jedni su od najčešće korištenih materijala za izradu implantata, upravo zbog svojih poželjnih svojstava uključujući veliku čvrstoću, malu gustoću, dobru korozijsku otpornost, biokompatibilnost i bioinertnost. Jedan od glavnih problema po postupku implantacije u ljudsko tijelo predstavlja degradacija implantata kao posljedica procesa korozije. Korozija, osim djelomičnog gubitka funkcije implantata ili preuranjenog kvara, štetno djeluje na čovjeka uslijed neželjenog otpuštanja metalnih iona koji se mogu nakupljati u okolna tkiva i organe što može dovesti do opasnih posljedica na ljudsko zdravlje. Kako do toga ne bi došlo, prije ugradnje u ljudsko tijelo, postoje različiti postupci korozijske zaštite implantata, uključujući nanošenje prevlaka samoorganizirajućih monoslojeva koji štite od razarajućeg djelovanja korozije, a u nekim slučajevima i poboljšavaju sama svojstva implantata. Samoorganizirajući monoslojevi (SAM) nastaju adsorpcijom organskih molekula iz homogene otopine i spontanim raspoređivanjem na krutu površinu u gusto pakirane uređene strukture. U ovom radu naglasak je na samoorganizirajućim monoslojevima fosfonskih kiselina koji u usporedbi s drugim SAM-ovima pokazuju bolju temperaturnu stabilnost te bolja hidrofobna svojstva i pokrivenost površine, zbog čega su vrlo atraktivni kandidati u području znanosti o materijalima i inženjerstvu površina. Njihova uloga na površini titanijevog implantata nije samo kao zaštitna barijera protiv korozije, već i za povećanje bioaktivnosti i poboljšanje oseointegracije titanijskog implantnog materijala zbog čega su ključan faktor pri dugoročnoj stabilnosti samog implantata.In today’s medicine, more attention is given to implant materials that serve as replacements for bones, teeth and other damaged biological structures in the human body. Titanium and its alloys are one of the most commonly used materials for making implants, due to their desirable properties including high strength, low density, good corrosion resistance, biocompatibility and bioinertness. One of the main problems in the process of implantation in the human body is the implant degradation as a result of the corrosion process. Corrosion, in addition to partial loss of implant function or premature failure, has a harmful effect on humans due to the unwanted release of metal ions that can accumulate in the surrounding tissues and organs what can lead to dangerous consequences for human health. In order to prevent corrosion, before implantation in human body, various corrosion protection modification methods can be applied, including the self-assembling monolayer coatings that provide corrosion protection to the underlying implant, and in some cases improve the properties of implant itself. Self-assembled monolayers (SAMs) are formed by the adsorption of organic molecules from a homogeneous solution and subsequent spontaneous arrangement on a solid surface into densely packed ordered structures. In this work, the emphasis is on self-organizing monolayers of phosphonic acids, which, compared to other SAMs, show better temperature stability and better hydrophobic properties and surface coverage, hence, serving as very attractive candidates in the field of materials science and surface engineering. Their role on the surface of the titanium implant is not only as a protective barrier against corrosion, but also to increase the bioactivity and improve the osseointegration of the titanium implant material, which is why they are a key factor in the long-term stability of the implant itself
Characterization of biodegradable waste
No full textNepravilno gospodarenje otpadom dovodi do štetnih posljedica u okolišu uz rizik za javno zdravlje. Poznavanje svojstava otpada ključno je za iskorištavanje njegovog potencijala, čija oporaba postaje ozbiljan izazov diljem svijeta. Osim što stvara potencijalne ekološke probleme, otpad ne samo da predstavlja gubitke iz proizvodnog procesa vrijednih sirovina i energije, već zahtijeva i značajna ulaganja u kontrolu onečišćenja. U ovom radu provedena je karakterizacija organske frakcije miješanog komunalnog otpada simulacijom procjedne vode u laboratorijskim uvjetima. Rezultati pokazuju da udio biorazgradive organske frakcije u miješanom komunalnom otpadu je veći od 61,5 % uz visoku prosječnu vrijednost omjera BPK5/KPK od 0,80±0,05 što ukazuje na značajan potencijal za biološku valorizaciju ispitivanog realnog uzorka.Improper waste management leads to harmful environmental consequences and poses risks to public health. Understanding the properties of waste is crucial for harnessing its potential, and its recovery is becoming a serious challenge worldwide. Besides creating potential ecological problems, waste not only represents losses of valuable raw materials and energy from the production process, but also requires significant investments in pollution control.
In this study, the characterization of the organic fraction of mixed municipal waste was conducted by simulating leachate in laboratory conditions. The results show that the biodegradable organic fraction in mixed municipal waste is over 61.5%, with a high average BOD5/COD ratio of 0.80±0.05, indicating significant potential for biological valorization of the tested real sample
Air pollution
No full textPorast industrijske aktivnosti doveo je do povećanja antropogenog učinka na okoliš. Onečišćenje zraka predstavlja značajan problem zbog mogućih štetnih posljedica na okoliš i živi svijet. Onečišćujuće tvari u zraku prenose se na velike udaljenosti u relativno kratkom vremenu te ih je teško ukloniti. Zbog navedenog potrebno je djelovati na izvoru onečišćenja zraka kako bi se spriječile neželjena onečišćenja. U ovom radu navedene su onečišćujuće tvari u zraku, njihovi izvori te posljedice na okoliš i zdravlje ljudi. U preglednom dijelu stavljen je naglasak na onečišćenje zraka iz industrijskih izvora, kao i na specifične onečišćujuće tvari iz pojedinih industrija, koje predstavljaju rizik za okoliš.The increase in industrial activity has led to an increase in the anthropogenic impact on the environment. Air pollution is a major problem due to its potential harmful effects on the environment and the living world. Pollutants in the air are transported over long distances in a relatively short time and are difficult to remove. For this reason, it is necessary to act on the source of air pollution in order to prevent unwanted pollution. In this paper, pollutants in the air, their sources and the consequences for the environment and human health are discussed. The overview section focuses on air pollution from industrial sources and on specific pollutants from individual industries that pose a risk to the environment
Removal of anthropogenic pollutants
No full textUklanjanje antropogenih onečišćujućih tvari iz okoliša ključno je za očuvanje bioraznolikosti, kvalitete zraka, vode i tla te zaštite zdravlja ljudi. Prisutnost tih tvari, kao rezultat ljudske djelatnosti, može uzrokovati ozbiljne ekološke i zdravstvene probleme. Uzroci prisutnosti antropogenih tvari leže u neodgovornim ljudskim aktivnostima, poput nepravilnog odlaganja otpada i upotrebe štetnih kemikalija. U okviru ovog rada prikazani su procesi obrade otpadne vode onečišćene antropogenim tvarima. Rješavanje navedenog problema nužno je za stvaranje održivijeg okoliša i dugoročnu dobrobit ljudi i planeta.The removal of anthropogenic pollutants from the environment is essential for the preservation of biodiversity, air, water and soil quality and the protection of human health. The presence of these substances as a result of human activities can lead to serious environmental and health problems. The causes of the presence of anthropogenic substances lie in irresponsible human activities such as the improper disposal of waste and the use of harmful chemicals. This paper presents the processes of wastewater treatment that are contaminated by anthropogenic substances. Solving this problem is necessary for the creation of a more sustainable environment and the long-term well-being of people and the planet
Coating technologies and biomedical application of calcium phosphate bioceramics
No full textKalcij-fosfati (CaP) su najčešće korištena skupina biokeramičkih spojeva zbog dobre biokompatibilnosti, oseointegracije i osteokonduktivnosti. Njihova primjena je široka, ali najpoznatiji su po primjeni u dentalnoj i ortopedskoj medicini gdje se zbog kemijske sličnosti s kostima sisavaca koriste kao prevlake na implantatima. Implantati predstavljaju zamjenu/nadomjestak oštećenog dijela kosti ili tkiva i dizajnirani su s ciljem vraćanja funkcije oštećenom dijelu tijela. Najčešće korišteni implantni materijali su metali i njihove legure poput titanija, nehrđajućih čelika i kobalt-krom legura. U tkivnom inženjerstvu za regeneraciju i oseointegraciju kostiju površina implantata modificira se kalcij-fosfatnim prevlakama
(CaP prevlake) koje poboljšavaju i ubrzavaju procese rasta i srastanja kostiju. CaP prevlake povećavaju bioaktivnost, biokompatibilnost, otpornost na koroziju i ostala biomehanička svojstva implantnih sustava. Postoje brojne metode pripreme CaP prevlaka od kojih su one najzastupljenije opisane u ovom radu. Jedna od najšire korištenih metoda je elektrokemijsko taloženje, niskotemperaturna metoda visoke dostupnosti i niske cijene opreme. Obzirom na visoki udio starog stanovništva, i sve češće bolesti kostiju i degenerativna i upalna stanja, uključujući nekrozu i osteoporozu, uporaba tkivnog inženjerstva, odnosno potreba za regeneracijom kostiju i tkiva, sve je veća tako da su razvoj i poboljšanje implantnih sustava sa CaP prevlakama predmet konstantnih istraživanja.Calcium phosphates (CaP) are the most commonly used group of bioceramic compounds due to their good biocompatibility, osseointegration and osteoconductivity. Their application is wide, but they are best known for use in dental and orthopedic medicine where, due to their chemical similarity to mammalian bones, they are used as coatings on implants. Implants represent a replacement/substitution of a damaged part of bone or tissue and are designed with the aim of restoring function to the damaged part of the body. The most commonly used implant materials are metals and their alloys such as titanium, stainless steel and cobaltchromium alloys. In tissue engineering for bone regeneration and osseointegration, the implant surface is modified by calcium-phosphate coatings
(CaP coatings), which improve and accelerate the processes of bone growth and fixation.
CaP coatings increase bioactivity, biocompatibility, corrosion resistance and other biomechanical properties of implant systems. There are numerous methods of preparing CaP coatings, the most common of which are described in this work. One of the most widely used method is electrochemical deposition, a low-temperature method with high availability and low cost of equipment. Due to high proportion of the elderly population, and increasingly frequent bone diseases and degenerative and inflammatory conditions (including necrosis and osteoporosis), the use of tissue engineering, i.e., the need for bone and tissue regeneration, is increasing so that the development and improvement of implant systems with CaP coatings are the subject of constant research
The influence of the functional comonomer in the structure of the polymer additive on the low-temperature behavior of diesel and biodiesel fuel
No full textU ovome radu su sintetizirani i pročišćeni polimerni aditivi. Prilikom sinteze svih polimernih aditiva korišteni su monomeri metil metakrilat (MMA), dodecil metakrilat (DDMA) i oktadecil metakrilat (ODMA), te ovisno o odabranome polimernome sustavu, funkcionalni monomer tert-butilaminoetil metakrilat (TBAEMA), 2-(diizopropilamino)etil metakrilat (DIPOAEMA) ili 2-(dietilamino)etil metakrilat (DEAEMA). Struktura i čistoća polimernih aditiva potvrđena je korištenjem spektroskopskih metoda infracrvene spektroskopije s Fourierovom transformacijom i protonske nuklearne magnetske rezonancije. Polimeri su podvrgnuti diferencijalnoj pretraženoj kalorimetriji i kromatografiji isključenja, kako bi im se odredila toplinska svojstva i prosječna molekulska masa polimera. Za ispitivanje svojstava formulacija s dizelskim i biodizelskim gorivom, pripravljene su formulacije goriva s 2000 ppm polimernih aditiva. Formulacije su analizirane uz pomoć diferencijalne pretražne kalorimetrije i proučavana je promjena morfologije kristala optičkim mikroskopom s polarizacijom. Određene su točke filtrabilnosti i tecište prema standardnim metodama EN 116 za točku filtrabilnosti i ASTM D5950 za tecište. Dobiveni rezultati pokazali su sniženje temperature tecišta i filtrabilnosti dizelskom gorivu kod svih sintetiziranih polimernih aditiva, a najbolji rezultat pokazao je sustav MDO30-1:1-DEA10 koji je snizio vrijednost točke filtrabilnosti dizelskoga goriva od -8 °C do -18 °C te vrijednost tecišta od -18 °C do -45 °C.In this paper, polymer additives were synthesized and purified. Monomers methyl methacrylate (MMA), dodecyl methacrylate (DDMA) and octadecyl methacrylate (ODMA) were used in the synthesis of all polymer additives, and depending on the selected polymer system, functional monomer tert-butylaminoethyl methacrylate (TBAEMA), 2-(diisopropylamino)ethyl methacrylate (DIPOAEMA) or 2-(diethylamino)ethyl methacrylate (DEAEMA). The structure and purity of polymer additives was confirmed using fourier transform infrared spectroscopy methods and proton nuclear magnetic resonance. Polymers underwent differential scanning calorimetry and exclusion chromatography, to determine their thermal properties and average molecular weight of polymers. For testing the properties of diesel and biodiesel fuel formulations, fuel formulations with 2000 ppm polymer additives were prepared. Formulations were analyzed with the help of differential scanning calorimetry and the change in crystal morphology by optical microscope with polarization was studied. The filtrability points and flow according to the standard methods are EN 116 for the cold filter plugging point and ASTM D5950 for the pour point. The obtained results showed a decrease in the temperature of the liquid and filtrability of diesel fuel in all synthesized polymer additives, and the best result was shown by the MDO30-1:1-DEA10 system, which lowered the value of the cold filter plugging point of diesel fuel from -8 °C to -18 °C and the pour point liquid from -18 °C to -45 °C
Synthesis of bioadditives based on gallic acid for improvement of application properties of diesel fuel
No full textU ovom radu opisana je sinteza i metoda pročišćavanja četiri bioaditiva reakcijom esterifikacije između galne kiseline i odgovarajućega alkohola. Alkoholi koji su korišteni za reakcije su etanol, propanol, butanol i pentanol, a kao katalizator korišten je p-toluen sulfonska kiselina. Sintetizirani produkti pročišćeni su ispiranjem s vodom. Struktura i čistoća priređenih spojeva analizirana je spektroskopskim metodama infracrvene spektroskopije s Fourierovom transformacijom i protonskom nuklearnom magnetskom rezonancijom.
Produkt je detaljnije analiziran pomoću metoda diferencijalne pretražne kalorimetrije i kromatografije isključenja po veličini. Nadalje, promatrala se topljivost produkata u vodi, dimetilsulfoksidu i dizelskome gorivu. Ustanovljeno je da sintetizirani produkti nisu topljivi u dizelskokome gorivu zbog čega se antiokisdativno djelovanje bioditiva ne može odrediti. Iz svih provedenih analiza može se zaključiti da su produkti sintetizirani, ali s jako malim iskorištenjem.This paper describes the synthesis and purification method of four bioadditives through the esterification reaction between gallic acid and the corresponding alcohol. The alcohols used for the reactions were ethanol, propanol, butanol, and pentanol, with p-toluenesulfonic acid used as the catalyst. The synthesized products were purified by rinsing with water.
The structure and purity of the prepared compounds were analyzed using spectroscopic methods such as Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance. The synthesized product was further analyzed using differential scanning calorimetry and size-exclusion chromatography. Additionally, the solubility of the products in water, dimethyl sulfoxide, and diesel fuel was observed. It was established that the synthesized products were not soluble in diesel fuel, making it impossible to determine their antioxidative properties. From all conducted analyses, it can be concluded that the products were synthesized but with very low yield
Surface modification of dental materials
No full textGlavni izazov za inženjere današnjice, koji se bave dentalnim materijalima, je proizvesti dentalne implantate koji uspješno imitiraju karakteristike prirodnih kostiju kako bi zdravlje kostiju bilo očuvano te kako bi oralna rehabilitacija bila osigurana. Dentalni implantati su uglavnom izrađeni od titanija i njegovih legura. Parametri, poput geometrije i topografije površine, su ključni za uspješan rani klinički ishod. Budući da hrapava površina pogoduje lakšem „usidrenju“ kosti, kao i biomehaničkoj stabilnosti, vrlo je važno da dentalni implantati imaju grubu površinu. Osim površinskih svojstava, kemijski sastav također pridonosi biološkim procesima tijekom oseointegracije. Glavni cilj ovoga istraživanja je modificirati površinu titanija zaštitnom i osteokonduktivnom prevlakom pomoću metode elektroispredanja. Prevlaka je sačinjena od vlakana polivinilpirolidona kao nosača kalcijevih iona. Poznato je da je kalcij nužan za zdravlje kostiju i za dobar metabolizam, stoga je važno da je aktivno uključen u proces oseointegracije jer na taj način ubrzava i pospješuje stvaranje nove kosti koja okružuje implantat. Morfologija površine modificiranog titanija ispitana je pretražnom elektronskom mikroskopijom (SEM), a kemijska analiza je provedena energijski razlučujućom rendgenskom spektrometrijom (EDS) i infracrvenom spektroskopijom s Fourierovom transformacijom uz prigušenu totalnu refleksiju (ATR-FTIR). Korozijska svojstva nemodificiranog i modificiranog titanija ispitana su u otopini umjetne sline u stvarnim uvjetima primjene pomoću elektrokemijske impedancijske spektroskopije (EIS). Rezultati ukazuju na poboljšanu zaštitu od korozije titanija s prevlakom u usporedbi s nemodificiranim titanijem.Nowadays, the major challenge for engineers is to produce dental implant surfaces that closely mimic the characteristics of natural bone to allow patients to achieve healthy bone conditions and oral rehabilitation. Most dental implants are made of titanium and its alloys. Parameters, such as geometry and surface topography, are crucial for a successful early clinical outcome. Since a rough topography favours both bone anchorage and biomechanical stability, it is of great importance that dental implants have a rough surface. In addition to the surface properties, the chemical composition also contributes to the biological processes during osseointegration. The main aim of this study was to modify the titanium surface with a protective and at the same time osteoconductive coating by the electrospinning method. The coating consists of polyvinylpyrrolidone (PVP) fibers as a carrier of calcium ions. It is known that calcium is very important for bone health and metabolism. Therefore, it should be actively involved in the osseointegration process and accelerate and promote the formation of new bone surrounding the implant. The surface morphology of the modified titanium was carried out by scanning electron microscopy (SEM) and the chemical elemental analysis of the coating by energy dispersive X-ray spectroscopy (EDS). The corrosion properties of unmodified and modified titanium were investigated in an artificial saliva solution under real application conditions by electrochemical impedance spectroscopy (EIS). The results indicate improved corrosion protection behaviour of the coated titanium compared to unmodified titanium