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Properties of polyvinylpyrrolidone
No full textPrimjena polimera postala je neizostavna tijekom posljednja dva stoljeća. U svim sferama ljudskog života prisutni su polimeri. Kako bi se proizvodnja i upotreba polimera odvijala uz što bolje iskorištenje i što manje onečišćenje okoliša, potrebno je dobro ispitati svojstva samih polimera i optimizirati njihovu proizvodnju i upotrebu. U ovom radu istraživan je poli(vinil pirolidon), sintetski polimer koji se dobiva polimerizacijom monomera N-vinilpirolidona. Ispitivana su mehanička, toplinska i reološka svojstva vodenih otopina s ciljem upoznavanja samog polimera, usporedbe s drugim sintetskim polimerima te određivanja njegove najbolje upotrebe. Pripremljeni uzorci poli(vinil pirolidona) analizirani su diferencijalnom pretražnom kalorimetrijom (DSC), termogravimetrijskom analizom (TGA) te reološkom analizom.
Rezultati navedenih ispitivanja pokazali su da je poli(vinil pirolidon) jako krt materijal, da je jako toplinski stabilan te da vodena otopina poli(vinil pirolidona) ima Ostwald de Waeleovo ponašanje.The application of polymers has become indispensable during the last two centuries. Polymers are present in all spheres of human life. In order for the production and use of polymers to take place with the best possible utilization and the least environmental pollution, it is necessary to thoroughly examine the properties of the polymers and optimize their production and use. The objective of this study was to examine poly(vinyl pyrrolidone), a synthetic polymer obtained by polymerization of N-vinyl pyrrolidone. Mechanical, thermal and rheological properties of water solution were tested with the aim of getting to know the polymer, comparing it with other sinthetic polymers and determine its best use. The samples of poly(vinyl pirrolidone) were analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and rheological analysis. Results of the mentioned tests showed that poly(vinyl pyrrolidone) is very brittle material, that it is very thermally stable and that the aqueous solution of poly(vinyl pirrolidone) has Ostwald de Waele behavior
Galactooligosaccharides - synthesis and application
No full textGalaktooligosaharidi kao skupina oligosaharida koja se zbog svoje strukture i svojstava neprobavljivosti u gornjem dijelu probavnog sustava ubraja u skupinu prebiotika sve se više proučava. Njihov prebiotički učinak najviše je izražen u donjem dijelu probavnog sustava – u debelom crijevu budući da tamo postaju hrana za korisne bakterije i samim time pospješuju njihov rast. Korisne bakterije poput bifidobakterija i laktobacila potrebne su u što većem broju zbog svog pozitivnog učinka na crijevnu mikrofloru. Po kemijskoj strukturi, spojevi su koji se sastoje od lanca molekula galaktoze koje su glikozidnim vezama povezane na molekulu glukoze. Cilj ovog rada jest upoznati se sa sintezom ovih spojeva iz raznih supstrata, konkretno laktoze te istražiti gdje se sve oni mogu primijeniti. Sinteza galaktooligosaharida provodi se pomoću enzima poput β-galaktozidaze koji razgrađuju laktozu (disaharid koji se sastoji od glukoze i galaktoze) i potom kataliziraju prijenos galaktoznih jedinica na različite akceptorske molekule. Kao prebiotički spojevi, svoju primjenu nalaze prvenstveno u prehrambenoj industriji, a potom i u farmaceutskoj i kozmetičkoj. Također, pomažu u očuvanju zdravlja kostiju te jačanju imunološkog sustava.Galactooligosaccharides, a group of oligosaccharides that are classified as prebiotics due to their structure and indigestibility in the upper part of the digestive system, are increasingly being studied. Their prebiotic effect is most pronounced in the lower part of the digestive system—in the colon—since they become food for beneficial bacteria there, thereby promoting their growth. Beneficial bacteria such as bifidobacteria and lactobacilli are needed in large numbers due to their positive effect on the intestinal microflora. By chemical structure, these are compounds consisting of a chain of galactose molecules linked to a glucose molecule by glycosidic bonds. The aim of this work is to explore the synthesis of these compounds from various substrates, specifically lactose, and to investigate their potential applications. The synthesis of galactooligosaccharides is carried out using enzymes like β-galactosidase, which break down lactose (a disaccharide consisting of glucose and galactose) and then catalyze the transfer of galactose units to different acceptor molecules. As prebiotic compounds, they are primarily used in the food industry, and also in the pharmaceutical and cosmetic industries. Additionally, they help in maintaining bone health and strengthening the immune system
Use of natural ingredients to replace harmful synthetic ingredients in cosmetic products
No full textRazvitkom kozmetičke industrije razvija se i čovjekova svijest o samim proizvodima koje koristimo i njihovoj štetnosti za zdravlje i okoliš. Različiti štetni sastojci, mirisi, aditivi i kemijski spojevi koji se koriste u kozmetičkoj industriji utječu na zdravlje čovjeka. Posljednjih godina, razvija se osobiti interes korištenja prirodne kozmetike. Raste svijest o prednostima prirodnih sastojaka u odnosu na sintetičke, koji mogu uzrokovati alergije, probleme s kožom i negativno utjecati na zdravlje. Ovaj rad nudi uvid o primjeni prirodnih komponenti u kozmetici za njegu kože. Cilj ovog rada je ispitati toplinska svojstva prirodnih sastojaka koji se koriste u pripremi dezodoransa, shea maslaca, kokosovog maslaca, kakao maslaca, škroba tapioke, natrijevog hidrogenkarbonata i eteričnih ulja grejpa i palmarose. Toplinska svojstva određena su diferencijalnom pretražnom kalorimetrijom (DSC) i termogravimetrijskom analizom (TGA). Diferencijalna pretražna kalorimetrija (DSC) pokazuje da maslaci imaju složene termičke profile zbog različitih faza kristalizacije i polimorfnih prijelaza. S druge strane, termogravimetrijska analiza (TGA) potvrđuje njihovu visoku toplinsku stabilnost, pri čemu se shea maslac izdvaja kao posebno stabilan. Eterična ulja grejpa i palmarose imaju različite razine toplinske stabilnosti, s tim da ulje grejpa pokazuje veću otpornost na razgradnju. Također, škrob tapioke i natrijev hidrogenkarbonat pokazuju značajnu toplinsku stabilnost.With the development of the cosmetics industry, people are becoming increasingly aware of the products we use and how harmful they are to our health and the environment. Various harmful ingredients, fragrances, additives and chemical compounds used in the cosmetics industry affect human health. In recent years, there has been a particular interest in the use of natural cosmetics. Awareness of the benefits of natural ingredients compared to synthetic ingredients, which can cause allergies and skin problems and affect health, has grown.
This paper provides an insight into the use of natural ingredients in skin care cosmetics.
The aim of this paper is to investigate the thermal properties of natural ingredients used in the production of deodorants: Shea butter, coconut butter, cocoa butter, tapioca starch, sodium bicarbonate and grapefruit and palmarosa essential oils. The thermal properties were determined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Differential scanning calorimetry (DSC) shows that butters have complex thermal profiles due to different crystallization stages and polymorphic transitions. On the other hand, thermogravimetric analysis (TGA) confirms their high thermal stability, with shea butter proving to be particularly stable. The essential oils of grapefruit and palmarosa exhibit different thermal stability, with grapefruit oil showing a higher resistance to degradation. Tapioca starch and sodium bicarbonate also exhibit high thermal stability
Effect of water matrix on removal of contaminants of emerging concern by membrane separation processes
No full textKontaminanti koji stvaraju zabrinutost su spojevi koji se u širokoj primjeni koriste u ljudskoj i veterinarskoj medicini, a također se smatraju „novim zagađivalima“ zbog povećanog ispuštanja u okoliš i otpadne vode tijekom posljednjih desetljeća. Zbog njihovog negativnog utjecaja na okoliš i zdravlje sve se veća pozornost pridaje tehnologijama uklanjanja takvih kontaminanata iz okoliša. Jedna od takvih tehnologija je upotreba membranskih separacijskih procesa koja je i korištena u ovom radu. Tlačni membranski procesi reverne osmoze (RO) i nanofiltracije (NF) korišteni su u ovom radu pri ispitivanju matica modelne otopine poznatog sastava i vodovodne vode na uklanjanje ispitivanih antibiotika – ciprofloksacina i sulfametoksazola. Korištene XLE i NF90 membrane pokazale su se najuspješnijima za uklanjanje antibiotika s faktorom zadržavanja > 90 % u većini slučajeva kod obje membrane za obje matice vode. Nešto lošiji rezultati, ali i dalje uspješni, dobiveni su upotrebom NF membrane čiji je faktor zadržavanja > 88 %, što je rezultat većih pora od ostalih ispitivanih membrana koja posljedično tome pokazuje slabije uklanjanje antibiotika. Različita molekulska masa ciprofloksacina i sulfametoksazola utjecala je na rezultate faktora zadržavanja na taj način da je ciprofloksacin pokazao bolje zadržavanje na membranama jer je veća molekula i teže prolazi kroz pore membrana. Dobiveni rezultati pokazali su da je efekt prosijavanja dominantan mehanizam separacije.Contaminants of emerging concern (CEC) are widely used substances in human and veterinary medicine that are also considered "emerging contaminants" due to their increasing release into the environment and wastewater in recent decades. Due to their negative impact on the environment and health, increasing attention is being focused on technologies to remove such contaminants from the environment. One such technology is the use of membrane separation processes, which were applied in this study. In this study, pressure-driven membrane processes such as reverse osmosis (RO) and nanofiltration (NF) were used to examine model solutions of known composition and tap water for the removal of the targeted antibiotics – ciprofloxacin and sulfamethoxazole. The XLE and NF90 membranes used in this study proved to be the most effective for antibiotic removal, achieving a retention factor of more than 90% for both membranes and for both water matrices in most cases. Slightly lower, but still successful results were obtained with the NF membrane, which had a retention factor of over 88%. This can be attributed to the larger pore size compared to the other membranes tested, resulting in a slightly lower removal of antibiotics. The different molecular mass of ciprofloxacin and sulfamethoxazole influenced the retention results, with ciprofloxacin showing better retention on the membranes due to its larger molecular mass, making it more difficult to pass through the membrane pores. The results obtained indicated that size exclusion was the predominant separation mechanism
Template removal techniques during the synthesis of mesoporous silicon materials
No full textMezoporozni silicijevi materijali imaju ključnu ulogu u raznim područjima primjene, poput katalize, adsorpcije, separacije i dostave lijekova, zahvaljujući njihovoj velikoj specifičnoj površini i kontroliranoj veličini pora. Njihova sinteza obično uključuje upotrebu organskih predložaka koji oblikuju poroznu strukturu. Uklanjanje strukturnih predložaka iz mezoporoznih silicijevih materijala ključno je za postizanje željenih svojstava i primjene tih materijala.
U ovom radu analizirane su prednosti i nedostaci različitih fizikalnih i kemijskih tehnika uklanjanja strukturnih predložaka. Posebna pažnja posvećena je utjecaju ovih metoda na konačne značajke materijala, kao što su veličina pora, specifična površina i strukturna stabilnost.Mesoporous silica materials play a crucial role in various applications such as catalysis, adsorption, separation, and drug delivery, due to their high specific surface area and controlled pore size. Their synthesis typically involves the use of organic templates that shape the porous structure. The removal of structural templates from mesoporous silica materials is essential for achieving the desired properties and functionalities of these materials. This paper analyzes the advantages and disadvantages of various physical and chemical techniques for template removal. Special attention is given to the impact of these methods on the final characteristics of the materials, including pore size, specific surface area, and structural stability
Optimizing the geometry and configuration of 3D-printed modular system for biodiesel synthesis
No full textU ovom radu eksperimentalno je ispitana mogućnost 3D-ispisa mikroreaktora i mikroseparatora korištenih za kemijsku transesterifikaciju ulja u biodizel. Tehnologija
3D-ispisa pruža izvrsnu fleksibilnost u dizajnu i izradi reakcijskog sustava i uređaja za protočnu kemiju. Brza izrada i mogućnost lake izmjene dizajna prototipa otvara mogućnost brzom napretku. Istražena je uloga računalno potpomognutog dizajna (CAD), 3D-ispisa, mikrostrukturiranih uređaja i računalne dinamike fluida (CFD) u svrhu optimiranja procesa proizvodnje mikroreaktora i procesa sinteze biodizela. Specifični cilj rada bio je 3D-ispisom izraditi optimirani modularni sustav za kontinuiranu sintezu i separaciju biodizela, a ujedno i optimiranje uvjeta 3D-ispisa. Moduli koji su korišteni u sustavu su mikroreaktor i mikroseparator koji su međusobno spojeni teflonskim cijevima. 3D-ispisano je sedam različitih modela mikroreaktora sa statičkim miješalicama i šest modela mikroseparatora u kojima je ispitana učinkovitost sinteze i separacije biodizela. Provedeno je optimiranje 3D-ispisa i naknadne obrade materijala u svrhu analize i odabira optimalnog materijala za izradu svih modela. Provedena je mehanička, toplinska i fizikalno-kemijska karakterizacija materijala kojima je pronađena korelacija između mehaničkih, toplinskih i određenih fizikalno-kemijskih svojstava materijala. Dizajnirani su različiti modeli mikroreaktora u kojima je provedena simulacija gibanja fluida u mikrokanalu, zatim su 3D-ispisani te je na kraju u njima provedena reakcija sinteze biodizela. Nakon 3D-ispisa mikroreaktora tehnologijom proizvodnje rastaljenim filamentom i stereolitografijom analizirani su kvaliteta izrađenih modela, prozirnost i vidljivost slojeva te je na temelju toga odabrana odgovarajuća tehnologija za 3D-ispis mikroreaktora i mikroseparatora. Prilikom sinteze biodizela, uzorci su sakupljani na izlazu pri stacionarnom stanju i analizirani za četiri vremena zadržavanja. Kriterij odabira optimalnog mikroreaktora bio je da u što kraćem vremenu zadržavanja ostvari iskorištenje od minimalno 96 %. Potom je u svakom od šest dizajniranih mikroseparatora proveden proces separacije u spoju sa odabranim mikroreaktorom. Provedenom karakterizacijom materijala korištenih u stereolitografiji i analizom kvalitete predmeta 3D-ispisanih prema zadanim kriterijima, za izradu mikroreaktora i mikroseparatora je odabran materijal High Temp. Materijal High Temp i stereolitografija kao tehnologija izrade, zadovoljili su uvjete dimenzijske točnosti izrade i prozirnosti, te su mehanička, toplinska i fizikalno-kemijska svojstva odgovarajuća za provedbu reakcije sinteze biodizela. Rezultati simulacija strujanja u mikroreaktorima predviđaju najveću brzinu strujanja u središtu kružnog poprečnog presjeka te promjenu raspodjele brzina prilikom prolaska fluida kroz statičke miješalice u obliku koljena. Rezultati analize dobiveni plinskom kromatografijom i nuklearnom magnetskom rezonancijom utvrdili su utjecaj različitih vrsta i broja statičkih miješalica na iskorištenje reakcije. U 3D-ispisanom cijevnom mikroreaktoru sa sedam koljena (C7K) za vrijeme zadržavanja 19,9 min te u cijevnom mikroreaktoru sa deset koljena (C10K) za vrijeme zadržavanja 19,2 min iskorištenje je doseglo 100 %. Za daljnju provedbu reakcije sinteze i separacije odabran je 3D-ispisani mikroreaktor C10K koji je pri vremenu zadržavanja 9,6 min postigao iskorištenje 96 %, a sastoji se od mikrokanala kružnog poprečnog presjeka i 10 statičkih miješalica u obliku koljena od 90°. Provedbom sinteze i separacije u integriranom modularnom sustavu primjenom pet mikroseparatora nije došlo do separacije toka, dok je primjenom mikroseparatora MSv5, čiji volumen je najmanji u usporedbi s ostalih pet, došlo do separacije toka uz učinak separacije 55 %. Prema dobivenim rezultatima zaključuje se da je tehnologija aditivne proizvodnje pogodna za proizvodnju mikrofluidnih sustava. Rezultati CFD simulacije su dobra polazna točka za izmjenu i modificiranje različitih dizajna mikroreaktora. Promjenom reakcijskih uvjeta moguće je postići veliko iskorištenje reakcije sinteze biodizela. Koljena u kanalu mikroreaktora ponašaju se kao statičke miješalice. Povećanjem broja statičkih miješalica u mikroreaktoru povećava se iskorištenje reakcije sinteze biodizela. Dokazana je mogućnost 3D-ispisa modularnog sustava za sintezu i separaciju biodizela.In this dissertation, the possibility of additive manufacturing technologies for the purpose of 3D printing of microreactors and microseparators used for oil transesterification into biodiesel was experimentally investigated. 3D printing technology offers superb versatility in the design and fabrication of custom reactionware for flow chemistry. There is potential for creating complex geometries in microfluidic devices to influence the yield of chemical reactions. Rapid fabrication of models, and the ability to easily modify designs open up the possibility of fast progress in flow chemistry. The role of computer-aided design (CAD),
3D printing, microfluidics, and computational fluid dynamics (CFD) was explored to optimise the production process of microreactors and biodiesel synthesis. The specific aim of the work is to 3D print an optimised modular system for biodiesel synthesis and separation, while also optimising the conditions of 3D printing. The modules in the system are a microreactor and microseparator connected by PTFE tubes. Seven different models of microreactors with static mixers and six models of microseparators were 3D printed to assess the efficiency of biodiesel synthesis and separation. The optimization of 3D printing and material post-processing was conducted in order to analyze and select the optimal material for 3D printing of all models. Mechanical, thermal, and physicochemical characterisation of the materials was performed, revealing correlations between the mechanical, thermal, and certain physicochemical properties of the materials. Various models of microreactors were designed in which the fluid movement in a microchannel was simulated and then 3D printed and in which the biodiesel synthesis reaction was finally carried out. After 3D printing of the microreactors using fused filament fabrication and stereolithography, the quality of the model production, the transparency and the layer visibility were analysed. Based on these analyses, the appropriate technology for 3D printing microreactors and microseparators was selected. Sampling from the 3D-printed microreactors was conducted at four different residence times. The criterion for selecting the optimum microreactor was to achieve a conversion of at least 96% in the shortest possible residence time. The separation process was then carried out in each of the six designed microseparators in conjunction with the selected microreactor. The characterisation of the materials used in stereolithography and the analysis of the quality of the 3D-printed objects according to specified criteria led to the selection of High Temp material for the fabrication of microreactors and microseparators. High Temp material and stereolithography as a manufacturing technology met the requirements for dimensional accuracy and transparency, and their mechanical, thermal and physicochemical properties were suitable for carrying out the biodiesel synthesis reaction. The results of the flow simulation in the microreactors predict the highest flow velocity in the centre of the circular cross-section and a change in the velocity distribution as the fluid passes through the bends. Gas chromatography and nuclear magnetic resonance analysis showed the influence of different types and numbers of static mixers on the reaction efficiency. In the 3D-printed tubular microreactor with seven bends (C7K), with a residence time of 19.9 minutes, and in the tubular microreactor with ten bends (C10K), with a residence time of 19.2 minutes, the conversion reached 100%. The 3D-printed microreactor C10K, which achieved a conversion of 96% with a residence time of 9.6 minutes and consists of microchannels with a circular cross-section and 10 static mixers in the form of 90° bends, was selected for the further performance of the synthesis and separation reaction. When performing synthesis and separation in an integrated modular system with five microseparators, there was no flow separation, while when using the MSv5 microseparator, which has the smallest volume compared to the other five, flow separation was achieved with a separation efficiency of 55%. The results obtained lead to the conclusion that additive manufacturing technology is suitable for the production of microfluidic systems. The results of the numerical flow simulations provide a good starting point for modifying and adapting various microreactor designs. By changing the reaction conditions, high efficiency can be achieved in the biodiesel synthesis reaction. The bends in the microreactor channel act as static mixers. Increasing the number of static mixers in the microreactor increases the efficiency of the biodiesel synthesis reaction. The feasibility of 3D printed modular system for biodiesel synthesis and separation was confirmed
Preparation and application of co-processed excipients
No full textOvaj rad bavi se problemom poboljšanja topljivosti i bioraspoloživosti dasatiniba, koji se koristi za liječenje leukemije. Dasatinib ima ograničenu topljivost u vodenom mediju, što rezultira slabom i sporom apsorpcijom u gastrointestinalnom traktu te niskom bioraspoloživošću. Modifikacija topljivosti i oslobađanja dasatiniba može imati pozitivan utjecaj na oralnu apsorpciju i bioraspoloživost lijeka. Glavni cilj istraživanja je formulirati ovaj specifičan lijek primjenom koprocesirane pomoćne tvari. Koprocesirana pomoćna tvar pripravljena je mehanokemijskim tretmanom i granuliranjem taljenjem. Pripremljena čvrsta disperzija pomoćnih tvari karakterizirana je metodama analize koje mogu ukazati na uspješnu pripravu disperzija. Pripravljena disperzija, odnosno koprocesirana pomoćna tvar, korištena je u pripravi konačnog dozirnog oblika djelatne tvari, tableta. Mehanokemijskim tretmanom nije ostvarena željena amorfizacija pomoćnih tvari. Granuliranjem taljenjem pripravljene su čvrste disperzije mikrokristalne celuloze, D-manitola i poli(etilen-glikola). Provedena je morfološka i granulometrijska analiza pripravljenih uzoraka. Pripravljene tablete testirane su na ujednačenost masa i sadržaja, čvrstoću, raspadljivost te topljivost. Koprocesiranjem pomoćnih tvari modificiran je profil oslobađanja dasatiniba.This thesis addresses the issue of improving the solubility and bioavailability of dasatinib, which is used to treat leukemia. Dasatinib has limited solubility in aqueous media, resulting in slow and poor absorption in the gastrointestinal tract and low bioavailability. Changing the solubility and release of dasatinib could have a positive effect on the oral absorption and bioavailability of the drug. The main objective of the research is to formulate this specific drug using a co-processed excipient. The co-processed excipient is prepared by mechanochemical treatment and melt granulation. The prepared solid dispersion of excipients was characterized using analytical methods that can give an indication of the successful preparation of dispersions. The prepared dispersion, i.e. the co-processed excipient, was used to prepare the final dosage form of the drug, the tablets. The desired amorphization of the excipients was not achieved by the mechanochemical treatment. Solid dispersions of microcrystalline cellulose, D-mannitol and poly(ethylene glycol) were prepared by melt granulation. Morphological and granulometric analysis of the prepared samples was carried out. The prepared tablets were tested for uniformity of mass and content, hardness, disintegration and solubility. The release profile of dasatinib was modified by co-processing of excipients
AOP degradation of atazanavir and nirmatrelvir
No full textOnečišćenje vode predstavlja globalni problem upravo zbog posljedica koje ostavlja po okoliš, ali i zdravlje ljudi i životinja. Izvori onečišćenja su različiti, a danas se veliki naglasak stavlja na nove onečišćujuće tvari u koje se ubrajaju i različiti farmaceutici. Pandemija COVID-19 virusa, koja se pojavila tijekom 2020. godine, ostavila je neizbrisiv trag koji se proteže kroz čitavi ekosustav. Tijekom pandemije, istraživana je učinkovitost različitih vrsta antivirotika koji bi uspješno suzbili virus i na taj način spriječili njegovo širenje. Atazanavir i nirmatrelvir ubrajaju se u antivirotike korištene u liječenju bolesti uzrokovane COVID-19 virusom, te je time veća i njihova prisutnost i akumulacija u vodenom okolišu. U ovom je radu ispitivana učinkovitost naprednih oksidacijskih procesa fotooksidacije, UV/H2O2 i UV/S2O82-, za razgradnju navedenih antivirotika. Tijekom provođenja razgradnje antivirotika, mijenjala su se dva parametra, pH-vrijednost modelne otopine antivirotika i koncentracija oksidansa. Pomoću punog faktorskog plana i metode odzivnih površina razvijeni su modeli uz pomoć kojih je moguće procijeniti utjecaj spomenutih procesnih parametara na brzinu razgradnje atazanavira i nirmatrelvira. Dobiveni modeli su u svim ispitivanim slučajevima značajni, a brzina razgradnje ispitivanih antivirotika opisuje se kinetikom prvog reda. Rezultati potvrđuju veću brzinu razgradnje ispitivanih antivirotika UV/S2O82- fotooksidativnim procesom.Water pollution presents a global problem precisely because of the consequences it leaves for the environment, but also for human and animal health. The main sources of pollution are different, and today a great emphasis is placed on new pollutants, which include various pharmaceuticals. The pandemic of the COVID-19 virus, which apperaed during 2020, left an indelible trace that extends throughout the ecosystem. During the pandemic, the effectiveness of different types of antiviral drugs were investigated for successful suppress of the virus and prevention of its spreading. Atazanavir and nirmatelvir are the antiviral drugs used during the treatment of diseases caused by COVID-19 virus, so they show a greater presence and bioacumulation in the aquatic environment. In this study, the effectiveness of advanced oxidation processes, UV/H2O2 and UV/S2O82- , for the degradation of the mentioned antivirals was investigated. During the photooxidative degradation of antivirals, the pH-value of the antiviral model solution and the concentration of oxidants were two process parameters that changed. Full factorial plan and response surface methodology were used for models development, which could estimate the influence of the mentioned process parameters on the degradation rate of atazanavir and nirmatrelvir. The obtained models are significant in all tested cases, and first-order kinetics can be used to describe the degradation rate of atazanavir and nirmatrelvir. The results confirm that the higher degradation rate of tested antivirals were achieved by UV/S2O82- photooxidation process
New carbamate derivatives of resveratrol - synthesis and spectroscopic characterization
No full textSvrha je ovog rada sinteza novih rezveratrolnih derivata, prvenstveno radi ispitivanja mogućnosti njihove primjene kod liječenja Alzheimerove bolesti, kao inhibitora enzima kolinesteraza. Budući da je rezveratrol već prepoznat kao spoj s jakim antioksidacijskim svojstvima, cilj je ovog istraživanja poboljšanje njegovih bioloških karakteristika modificiranjem njegove kemijske strukture. Stoga su novi derivati sintetizirani postupkom Wittigove reakcije, uz odvajanje nastalih izomera kolonskom kromatografijom. Pritom su korišteni odgovarajući aldehid, sa željenim supstituentom u para-položaju u odnosu na hidroksilnu skupinu, te tiofenska sol, nesupstituirana ili 5-metil-2-supstituirana sol. Uspješno su dobiveni biološki aktivni trans-izomeri novih rezveratrolnih derivata, a njihove su ključne istraživane karakteristike antioksidacijska svojstva i sposobnost inhibicije enzima kolinesteraza. Uz to, spektroskopska karakterizacija sintetiziranih spojeva doprinosi boljem razumijevanju njihovih kemijskih svojstava. Na temelju rezultata mjerenja, spoj trans-7 pokazuje najznačajniju antioksidacijsku aktivnost, ostvarivši inhibiciju butirilkolinesteraze s vrijednosti IC50 od 24,8 μM te negativan in silico test na genotoksičnost.The purpose of this study is the synthesis of new resveratrol derivatives, primarily to investigate their potential application in the treatment for Alzheimer's disease, as cholinesterase enzymes inhibitors. Since resveratrol is already recognized as a compound with strong antioxidant properties, the aim of this research is to enhance its biological characteristics by modifying its chemical structure. Therefore, the new derivatives were synthesized using the Wittig reaction, with separation of the resulting isomers by column chromatography. An aldehyde, with the desired substituent in para-position relative to the hydroxyl group, and a thiophene salt, either unsubstituted or 5-methyl-2-substituted, were used in the process. Biologically active trans-isomers were successfully obtained, and their key characteristics, such as antioxidant properties and the ability to inhibit cholinesterase enzymes, were examined. Additionally, the spectroscopic characterization of the synthesized compounds contributes to a better understanding of their chemical properties. Research results show that compound trans-7 demonstrates the most significant antioxidant activity, achieving butyrylcholinesterase inhibition with IC50 value of 24.8 μM and a negative in silico test for genotoxicity
Structure and properties of polycaprolactone/diatom composites
No full textAdhezija na međupovršini polimer/punilo ključni je čimbenik koji određuje svojstva višekomponentnih sustava kao što su polimerni kompoziti. Cilj ovog diplomskog rada bio je istražiti međupovršinska, mehanička i toplinska svojstva polikaprolaktona (PCL) uz dodatak punila dijatoma (0,1; 0,3; 0,5; 1,0; 3,0 i 5,0 %) pripravljenih zamješavanjem u talini. Utjecaj dodatka punila dijatoma na svojstva PCL kompozita istražen je primjenom tehnika kontaktnog kuta, diferencijalne pretražne kalorimetrije (DSC), termogravimetrijske analize (TGA) i rasteznog ispitivanja. Svojstva međupovršine kompozita procijenjena su na osnovi proračunatih vrijednosti parametara adhezije; termodinamičkog rada adhezije, slobodne međupovršinske energije i koeficijenta razlijevanja. Dobivene vrijednosti parametara adhezije dovedene su u vezu s mehaničkim i toplinskim svojstvima istraživanih nanokompozita. Povećanjem udjela punila dijatoma poboljšavaju se mehanička svojstva i toplinsku stabilnost PCL-a, što se može pripisati boljoj međupovršinskoj adheziji između punila dijatoma i PCL matrice.Adhesion at the polymer/filler interface is a key factor determining the properties of multicomponent systems such as polymer composites. The aim of this work was to investigate the interfacial, mechanical and thermal properties of polycaprolactone (PCL) with the addition of diatomaceous fillers (0, 0.1, 0.3, 0.5, 1.0, 3.0 and 5.0 %) prepared by melt blending. The effects of the addition of diatomaceous fillers on the properties of the PCL composites were investigated using the contact angle technique, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and tensile testing. The properties of the interfaces of the composites were evaluated using the calculated values of the adhesion parameters: thermodynamic work of adhesion, interfacial free energy and spreading coefficient. The values determined for the adhesion parameters are related to the mechanical and thermal properties of the composites investigated. An increase in the diatomaceous filler content improves the mechanical properties and thermal stability of PCL, which can be attributed to better interfacial adhesion between the diatomaceous filler and the PCL matrix