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Stability and application of polyphenol extract from olive leaves
No full textFenoli su spojevi koji se nalaze u nusproduktima masline, a njihovo djelovanje može pozitivno utjecati na ljudsko zdravlje. Oni se iz nusprodukata mogu separirati ekstrakcijom pri određenim uvjetima. Pri tome je bitno odabrati prirodno otapalo koje zadovoljava kriterije zelene kemije. U posljednje vrijeme istražuju se prirodna niskotemperaturna eutektička otapala koja se dobivaju miješanjem prirodnih komponenti i imaju ogroman potencijal i mogućnosti pri ekstrakciji prirodnih komponenti iz različitih biljaka. U sklopu ovog završnog rada istraživana je ekstrakcija polifenola iz lista masline pomoću prirodnog niskotemperaturnog eutektičkog otapala pripravljenog od mliječne kiseline, fruktoze i glicina uz dodatak vode. Otapalu je određena viskoznost, gustoća i pH vrijednosti. Nakon provedene ekstrakcije, ekstrakt je umiješan u baznu, hidratantnu kremu u različitim koncentracijama. Kreme pripremljene s manjim udjelom ekstrakta, pokazale su bolju stabilnost.Phenols are compounds found in olive byproducts, and their action can positively affect human health. They can be separated from byproducts by extraction under certain conditions. It is important to choose a natural solvent that meets the criteria of green chemistry. Recently, solvents have been reaserched, which are obtained by mixing natural components and have a huge potential and opportunities in extraction of natural components from different plants. As part of this work, the extraction of polyphenols from olive leaves using a natural deep eutectic solvent composed of lactic acid, fructose, and glycine with the addition of water was investigated. The viscosity, density, and pH values of the solvent were measured. After the extraction, different amounts of the extract are combined with the moisturizer base cream. The creams with the lowest extract content were the most stable
Removal of microplastic particles using ferrate (VI) from water
No full textPlastika se najčešće odlikuje visokom stabilnosti, trajnosti i niskom cijenom proizvodnje. Postala je sveprisutna u okolišu kao posljedica masovne proizvodnje i lošeg gospodarenja otpadom. Mikroplastika nastaje kroz fizičku, kemijsku i biološku degradaciju većih komada plastike u okolišu. Mikroplastiku karakterizira velika kemijska stabilnost u okolišu, mogućnost daljnje fragmentacije u nanoplastiku i sposobnost adsorpcije drugih onečišćivala, kao i potencijal za bioakumulaciju. Otpadne vode sadrže mikroplastiku i nepoznate količine nanoplastike koje ne mogu biti u potpunosti uklonjene. Studije efikasnosti uklanjanja mikroplastike u početnoj su fazi zbog nedostatka standardnih protokola kvantifikacije mikroplastike u okolišnim matricama. Ferat je već dugo poznat kao svestran i multifunkcionalni reagens u obradi voda s mogućnošću pročišćavanja različitih vrsta zagađivača, ali nedostaci poput niske stabilnosti ograničavaju njegovu široku primjenu. U ovom radu provedeno je modelno starenje mikroplastike, te je ispitana mogućnost uklanjanja PET mikroplastike procesom koagulacije feratima iz vodene otopine u blago kiselom pH. Uzorci su karakterizirani FTIR spektrofotometrom, a masa istaložene mikroplastike određena je mjerenjem sadržaja organskog ugljika u filtratima uzoraka. Ferat se pokazao donekle primjenjivim za uklanjanje mikroplastike, međutim potrebno je ispitati učinkovitost uklanjanja u širem rasponu pH te kvantificirati udio nanoplastike.Plastics are often characterized by high stability, durability and low production cost. It has become ubiquitous in the environment as a result of mass production and poor waste management. Microplastics form through the physical, chemical and biological degradation of larger plastic pieces in the environment. Microplastics are highly stable in the environment, have a high potential towards further fragmentation to nanoplastics and are able to adsorb other contaminants, as well as they have a potential for bioaccumulation. Wastewater contains microplastics and unknown amounts of nanoplastics that are difficult to remove entirely. Studies on the efficiency of microplastic removal are in the initial phase due to the lack of standard protocols for the quantification of microplastics in environmental matrices. Ferrate has been known for long as a versatile and multifunctional reagent in water treatment with the ability to purify various types of pollutants, but disadvantages such as low stability limited its wide application. Herein the environmental aging of microplastics, the methods of detection and microplastics removal, and the removal of UV-aged and non-aged PET microplastics particles by the process of ferrate coagulation from an aqueous solution in a low acidic pH. The samples were characterized by FTIR spectrophotometry, the mass of precipitated microplastic was measured by determining the organic carbon content
Synthesis and biological activity of macrolide-isoxazole conjugates
No full textMakrolidni antibiotici predstavljaju skupinu prirodnih ili polusintetskih spojeva koji se sastoje od makrocikličkog laktonskog prstena koji je povezan s jednim ili više deoksišećera. Često se koriste u liječenju i prevenciji raznih zaraznih bolesti. S druge strane, zbog širokog spektra biološkog djelovanja, izoksazol ima značajnu ulogu u dizajniranju lijekova. Kao rezultat višegodišnjih istraživanja spojeva koji sadrže izoksazolni prsten, brojni odgovarajući lijekovi našli su se na tržištu. U ovom radu opisana je sinteza novih makrolidnih konjugata s izoksazolom. Pripravljene su četiri klase makrolidnih konjugata s izoksazolom sintezom u četiri stupnja, a njihova ispitivanja antibakterijske aktivnosti su u tijeku. U prvom stupnju sinteze Michaelovom adicijom 9-deokso-9a-aza-9a-homoeritromicina A na akrilonitril pripravljen je 9a-N-(2-cijanoetil)-9-deokso-9a-aza-9a-homoeritromicin A (1). Njegovom katalitičkom redukcijom u drugom stupnju, u atmosferi vodika uz PtO2 pripravljen je 9a-N-(3-aminopropil)-9-deokso-9a-aza-9a-homoeritromicin A (2). U idućem stupnju, reakcijom amidiranja spoja 2 uz odgovarajuću izoksazol-5-karboksilnu kiselinu, HATU ili T3P kao aktivatore te DIPEA ili TEA kao baze pripravljeni su derivati makrolida s izoksazolom (3–5). U posljednjem stupnju sinteze, hidrolizom spojeva 3–5 pripravljeni su dekladinozilni derivati 6–8. Iz ranije pripravljenog 4''-O-(3-aminopropil)-9-deokso-9a-aza-9a-metil-9a-homoeritromicina A uz odgovarajuću izoksazol-5-karboksilnu kiselinu te HATU i DIPEA priređena je treća klasa spojeva (9–11). Četvrta klasa makrolidnih konjugata s izoksazolom (12–14) pripravljena je amidiranjem 9a-N-(3-aminopropil)-9-deokso-9a-aza-9a-3-O-dekladinozil-5-O-dedesozaminil-9a-homoeritromicina A uz odgovarajuću izoksazol-5-karboksilnu kiselinu te HATU i DIPEA. Strukture svih novopripravljenih spojeva potvrđene su 1H- i 13C-NMR spektroskopijom.Macrolide antibiotics represent a group of natural or semi-synthetic compounds consisting of a macrocyclic lactone ring connected to one or more deoxysugars. They are ofen used in the treatment and prevention of various infectious diseases. On the other hand, due to their broad spectrum of biological activity, isoxazole plays a significant role in drug design. As a result of years of research on compounds containing the isoxazole ring, numerous corresponding drugs have found their way to the market. This paper describes the synthesis of new macrolide-isoxazole conjugates. Four classes of macrolide-isoxazole conjugates were prepared through a four-step synthesis and their antibacterial activity tests are underway. In the first step of synthesis, By Michael's addition of 9-deoxo-9a-aza-9a-homoerythromycin A to acrylonitrile, 9a-N-(2-cyanoethyl)-9-deoxo-9a-aza-9a-homoerythromycin A (1) was prepared. By its catalytic reduction in the second step, in a hydrogen atmosphere with PtO2, 9a-N-(3-aminopropyl)-9-deoxo-9a-aza-9a-homoerythromycin A (2) was prepared. In the next step, derivatives of macrolide with isoxazole (3–5) were prepared by amidation of 2 with the appropriate isoxazole-5-carboxylic acid, using HATU or T3P as acid activators and DIPEA or TEA as bases. In the final step of synthesis, decladinosyl derivatives (6–8) were prepared by hydrolysis of compounds 3–5. The third class of derivatives (9–11) was prepared from the previously prepared 4''-O-(3-aminopropyl)-9-deoxo-9a-aza-9a-methyl-9a-homoerythromycin A, using the appropriate isoxazole-5-carboxylic acid with HATU and DIPEA. The fourth class of macrolide-isoxazole conjugates (12–14) was prepared by amidation of 9a-N-(3-aminopropyl)-9-deoxo-9a-aza-9a-3-O-decladinosyl-5-O-dedesosaminyl-9a-homoerythromycin A with the appropriate isoxazole-5-carboxylic acid with HATU and DIPEA. The structures of all newly prepared compounds were confirmed by 1H- and 13C-NMR spectroscopy
Napredno vođenje procesa šaržne kristalizacije
No full textA method for real-time monitoring of particle size distribution in the batch crystallization process was developed based on an experimental study for the fosamprenavir calcium – methanol system. The aim was to improve the pharmaceutical production process while taking product quality into account. In addition, such a method is a prerequisite for the advanced process control strategy to achieve the desired particle size distribution at the end of batch crystallization. The first part of the research involved the development of an automated laboratory setup for experiments and tests of the developed methods. The next step was the collection of experimental data from the batch crystallization, which was needed for the development of calibration models. The final step of the research was the development and application of methods for real-time monitoring of the particle size distribution of crystallized fosamprenavir calcium. The chord length distribution of the crystallized sample was recorded in real time using focused beam reflectance measurement. Since this type of data is not a reliable representation of the particle size distribution, a calibration model describing the functional relationship between the chord length distribution and the particle size distribution of the crystalline sample is required. The calibration models for real-time monitoring of the particle size distribution were developed separately using partial least squares regression and artificial neural networks. The results of these two mathematical approaches were analyzed. Principal component analysis was used for the preliminary interpretation of the experimental data and for the detection of outliers. Both methods proved to be suitable for this application. Regression models using the partial least squares method proved to be better for this application, although neural networks should not be excluded. For nonlinear systems and a larger amount of available experimental data, artificial neural networks will probably prove to be more suitable than partial least squares regression models. The scientific contribution will be made through the development and application of an original, advanced real-time monitoring strategy for batch crystallization processes. The application of the developed monitoring strategy will, as expected, improve the batch crystallization process and achieve the desired particle size distribution.Na temelju eksperimentalnih istraživanja za sustav fosamprenavir kalcij – metanol razvijena je metoda za praćenje volumne raspodjele veličina čestica u stvarnom vremenu u procesu šaržne kristalizacije. Cilj je poboljšati proces farmaceutske proizvodnje kako bi se ostvarila odgovarajuća kvaliteta proizvoda. Razvijena metoda osnova je za naprednu strategiju vođenja za postizanje željene volumne raspodjele veličina čestica na kraju procesa šaržne kristalizacije. Prvi dio istraživanja uključivao je razvoj automatiziranog i integriranog laboratorijskog sustava za pokuse i ispitivanja razvijenih metoda. Sljedeći korak bilo je prikupljanje eksperimentalnih podataka iz procesa šaržne kristalizacije potrebnih za razvoj kalibracijskih modela. Završni korak istraživanja obuhvatio je razvoj i primjenu metoda za praćenje volumne raspodjele veličina čestica kristaliziranog fosamprenavir kalcija u stvarnom vremenu. Raspodjela veličina čestica izražena duljinom kristaliziranog uzorka snimljena je u stvarnom vremenu pomoću reflektometra s fokusiranim snopom. Budući da ova vrsta podataka ne prikazuje pouzdano raspodjelu veličina čestica, potreban je kalibracijski model koji daje funkcionalni odnos između raspodjele veličina čestica izražene duljinom i volumne raspodjele veličina čestica kristaliziranog uzorka. Kalibracijski modeli za praćenje volumne raspodjele veličina čestica u stvarnom vremenu razvijeni su zasebno primjenom parcijalne regresije najmanjih kvadrata i umjetnih neuronskih mreža. Analizirani su i uspoređeni rezultati ova dva pristupa. Analiza glavnih komponenti primijenjena je za preliminarno tumačenje eksperimentalnih podataka i otkrivanje odstupajućih vrijednosti. Obje metode pokazale su se prikladnima za primjenu. Regresijski modeli dobiveni metodom parcijalnih najmanjih kvadrata pokazali su se boljim. Neuronske mreže, očekivano, bi se trebale pokazati prikladnim rješenjem za nelinearne sustave i veće skupove dostupnih eksperimentalnih podataka. Znanstveni doprinos ostvaren je razvojem i primjenom originalne napredne automatizirane metode praćenja procesa šaržne kristalizacije u stvarnom vremenu. Primjena razvijene metode praćenja u proizvodnji će, očekivano, unaprijediti proces šaržne kristalizacije postizanjem definirane volumne raspodjele veličina čestica
Fate and behavior of perfluorinated compounds
No full textPerfluorirani i polifluorirani spojevi (engl. Perfluoroalkyl and polyfluoroalkyl substances, PFAS) organski su spojevi koji se upotrebljavaju u sredstvima za impregnaciju, čišćenje prljavštine, masnoća s predmeta ili kao zaštitni premazi. Potkraj 20. stoljeća dokazano je da teško podliježu razgradnji te je dokazano kako se mogu akumulirati u okolišu. Od tada se istražuju njihovi utjecaji na okoliš i ljudsko zdravlje. Podliježu mnogim fizikalno-kemijskim promjenama što može štetno utjecati na ljudsko zdravlje i okoliš. U svojoj strukturi posjeduju vezu između C atoma ugljika i F atoma fluora, koja se smatra jednom od najjačih veza organske kemije. Posjedovanje te veze pridonosi njihovoj postojanosti u okolišu te se još nazivaju i „vječnim kemikalijama”. Prisutni su u svim sastavnicama okoliša te se nakupljaju u okolišu. Najraširenije vrste PFAS-a u okolišu su perfluorooktanska kiselina (engl. Perfluorooctanoic acid, PFOA) i perfluoroktan sulfonska kiselina (engl. Perfluorooctane sulfonic acid, PFOS), koje se koriste u većini industrijskih procesa i potrošačkim proizvodima. PFAS-i se smatraju postojanim organskim onečišćivalima (engl. Persistent organic pollutants, POPs) zbog čega su donesene direktive i uredbe kojima se nastoji urediti njihova upotreba i ispuštanje u okoliš; 2009. godine perfluorirani spojevi uvršteni su u Stockholmsku konvenciju o postojanim onečišćujućim tvarima. Direktivom Europskog parlamenta i vijeća o kvaliteti vode za piće namijenjene za ljudsku potrošnju (engl. The Drinking Water Directive) donesene su granične vrijednosti koncentracija koje ne smiju prelaziti 0,1 do 0,5 μg L^-1. Cilj ovog rada je predstaviti grupu antropogenih perfuoriranih organskih spojeva; načine unosa u okoliš, njihovo ponašanje i sudbinu te prikazati njihov utjecaj na sastavnice okoliša i ljudski organizam.Perfluorinated and polyfluorinated substances (PFAS) are organic compounds used in impregnation agents, cleaning agents for dirt, grease from surfaces, or as protective coatings. At the end of the 20th century, it was proven that they are resistant to degradation and can accumulate in the environment. Since then, their impacts on the environment and human health have been under investigation. They undergo many physicochemical changes which can have harmful effects on human health and the environment. In their structure, they possess a bond between carbon (C) atoms and fluorine (F) atoms, which is considered one of the strongest bonds in organic chemistry. This bond contributes to their persistence in the environment, earning them the nickname "forever chemicals". They are present in all components of the environment and accumulate in it. The most widespread types of PFAS in the environment are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), which are used in most industrial processes and consumer products. PFAS are considered persistent organic pollutants (POPs), leading to the adoption of directives and regulations aimed at regulating their use and release into the environment; in 2009, perfluorinated compounds were included in the Stockholm Convention on Persistent Organic Pollutants. The Drinking Water Directive of the European Parliament and Council sets concentration limits that must not exceed 0.1 to 0.5 μg L^-1. The aim of this paper is to present the group of anthropogenic perfluorinated organic compounds; their pathways into the environment, behavior, and fate, and to demonstrate their impact on environmental components and the human body
Characterization of polycaprolactone/hematite composites
No full textPolikaprolakton (PCL) polimerni je materijal koji se često upotrebljava zbog svoje netoksičnosti, biorazgradljivosti i lake mogućnosti oblikovanja. Osim toga, PCL je biokompatibilan materijal što ga čini pogodnim za medicinsku primjenu, npr. za izradu implantata i kirurških šavova. PCL se može koristiti i kao matrica u polimernim kompozitima.
S druge strane, željezov oksid hematit može se upotrebljavati kao punilo u polimernim kompozitima zbog svoje iznimne stabilnosti, netoksičnosti i niske cijene. Primjenjuje se s ciljem poboljšanja mehaničkih, toplinskih i ostalih svojstava polimernih materijala. U ovom su radu istražena svojstva kompozita polikaprolakton/hematit pripremljenih s česticama hematita različitih veličina i oblika. Provedena je karakterizacija kompozita infracrvenom spektroskopijom s Fourierovom transformacijom (FTIR), diferencijalnom pretražnom kalorimetrijom (DSC) i termogravimetrijskom analizom (TGA), a određena je i propusnost vodene pare. Razmatrao se utjecaj tipa čestica hematita na svojstva polimernih kompozita.Polycaprolactone (PCL) is a polymer material commonly used due to its non-toxicity, biodegradability and susceptibly to moulding. Additionally, PCL is a biocompatible material, suitable for medical applications such as the production of implants and surgical sutures. PCL can also be used as a matrix in polymer composites. On the other hand, iron oxide hematite can be used as a filler in polymer composites because of its exceptional stability, non-toxicity and low cost. It is used to improve the mechanical, thermal and other properties of polymer materials. This study investigates the properties of polycaprolactone/hematite composites prepared with hematite particles of various sizes and shapes. The composites were characterized using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Water vapor permeability is also determined. The impact of the type of hematite particles on the properties of polymer composites was studied
Application of the 'coffee ring' effect in the research of drug product properties
No full textPrimarni cilj ovog rada je istražiti pojavu „Coffee ring“ efekta i primjeniti otkriveno u optimizaciji svojstva ljekovitih pripravaka putem odabira pogodnih tvari tijekom razvoja formulacija. Razumijevanje ovog fenomena omogućuje dublji uvid u međusobne interakcije djelatne tvari (eng. Active Pharmaceutical Ingredients, API) i pomoćnih supstancija (ekscipijenata) što je ključno za razvijanje formulacija s ciljem da se poboljša stabilnost i učinkovitost. Stoga, ovaj rad istražuje kako coffee ring efekt može poslužiti kao koristan alat za razvoj inovatinvnih strategija u formuliranju ljekovitih pripravaka, čime se otvaraju perspektive za unaprjeđenje terapijskih učinaka i farmakokinetičkih svojstava. Glavna prednost ovog pristupa temelji se na uporabi iznimno male količine materijala (svega nekoliko mikrograma po mjerenju), što omogućuje razvoj formulacija u ranim fazama ispitivanja kada je dostupnost materijala za ispitivanje ograničena. Dodatni benefit je i smanjena potreba za potentnim materijalima, što povećava sigurnost i smanjuje troškove prilikom rada s vrlo aktivnim uzorcima. Koncept je potvrđen na nekoliko modelnih sustava koji su sadržavali dvije djelatne tvari, pantoprazol i doksiciklin, te dvije pomoćne tvari, natrijev klorid i 2-hidroksipropil β-ciklodekstrin, koji su istraživani pri različitim uvjetima. Rezultati su obrađeni korištenjem mikroskopa kako bi se pratili karakteristični obrasci. Posebna pažnja posvećena je istraživanju ponašanja fiziološke otopine, pri čemu su dobiveni podaci svrstani u klastere.
U modelnom sustavu koji sadrži pantoprazol i 2-hidroksipropil β-ciklodekstrin, uočeno je ponašanje koje ukazuje na nastanak interakcije između tih dviju komponenti, što je dodatno istraženo korištenjem diferencijalne skenirajuće kalorimetrije. Provedeno istraživanje potvrdilo je postavljenu hipotezu da se pojava coffee ring-a može koristiti u istraživanju svojstava formulacija farmaceutskih pripravaka.The coffee ring effect, a phenomenon observed when a liquid containing suspended particles evaporates, results in a characteristic ring-like stain. This effect occurs due to the differential evaporation rates across the droplet, causing particles to be deposited at the edges. By understanding this phenomenon, we can gain deeper insights into the interactions between active pharmaceutical ingredients (APIs) and excipients, which is crucial for creating formulations that improve stability and efficacy. This approach not only holds promise for improving therapeutic outcomes but also offers potential advancements in pharmacokinetic properties. Furthermore, the reduced need for highly potent materials enhances safety and reduces costs associated with working with very active substances. This dual benefit underscores the significant potential of employing the coffee ring effect in the advancement of pharmaceutical formulation science. Through this innovative approach, we open new avenues for the development of more effective and stable pharmaceutical products.
The concept has been validated using several models that included two active substances, pantoprazole and doxycycline, along with two excipients, sodium chloride and
2-hydroxypropyl β-cyclodextrin, studied under various conditions. The results were analyzed using microscopy to observe characteristic patterns. Special attention was given to the behavior of saline solution, with the collected data being categorized into clusters. In the model containing pantoprazole and 2-hydroxypropyl β-cyclodextrin, interactions between these two components were observed, which were further investigated using differential scanning calorimetry. The research validated the hypothesis that the coffee ring effect can be utilized to study the properties of pharmaceutical formulations
Characterisation of sacrificial agents by in situ generated oxygen free radicals and its application in photoelectrochemical hydrogen production
No full textCilj ovog rada bio je provesti proces fotoelektrokemijskog dobivanja vodika pri tome ispitujući svojstva SnS2 elektrode uz dodatak različitih žrtvujućih sredstava. Korištene su različite koncentracije 5-aminosalicilne kiseline (5-ASK) bez prisustva i s prisustvom askorbinske kiseline (AA) u 0,1 M otopini NaCl kao osnovnom elektrolitu. Ispitivanja su provedena sljedećim metodama: linearna polarizacija, ciklička voltametrija, elektrokemijska impedancijska spektroskopija i kronoamperometrija za neosvijetljenu i osvijetljenu elektrodu. Mjerenja su provedena kroz tri ciklusa. S obzirom da SnS2 elektroda apsorbira u vidljivom dijelu spektra, kao izvor svjetla korištena je LED lampa. Za dodatnu karakterizaciju žrtvujućih sredstava ispitana su njihova antioksidativnih svojstava prema O2-‧ radikalu. Fotostruje zabilježene metodom linearne polarizacije potvrdile su dobru fotoaktivnost SnS2 u prisustvu žrtvujućih sredstava.. Također, metodom linearne polarizacije i kronoameprometrije pokazano je kako se najveći iznos struje dobiva kod prvog mjerenja, dok kod ostalih mjerenja imamo niže iznose struja zbog fotokorozije aktivnog materijala. U usporedbi struja za čistu 5-ASK i kombinaciju 5-ASK i AA može se zaključiti kako se njihovom kombinacijom dobivaju veći iznosi struje. Ovaj rezultat istraživanja je bitan jer se u prirodi najčešće pojavljuju kombinacije žrtvujućih sredstava pa je ključno ispitati njihovo međudjelovanje. Impedancijska mjerenja pokazuju kako je impedancija manja za osvijetljene elektrode, tj. manji je otpor prijelazu naboja nego za neosvijetljene elektrode što također potvrđuje dobru fotoaktivnost elektrode. Antioksidativna svojstva su ispitana metodom cikličke voltametrije koja ukazuje da će povećanje koncentracija 5-ASK u smjesi 5-ASK i AA doprinijeti boljem suzbijanju superoksidnog radikala.The aim of this work was to carry out the process of photoelectrochemical production of hydrogen while examining the properties of the SnS2 electrode with the addition of various hole scavengers. Different concentrations of 5-aminosalicylic acid and ascorbic acid were used in 0.1 M NaCl solution as the basic electrolyte. Measurements were performed using the following methods: linear polarization, cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry for unilluminated and illuminated electrodes. Measurements were performed through three cycles. Given that the SnS2 electrode absorbs in the visible part of the spectrum, an LED lamp was used as a light source. As an additional characterization of the sacrificial agents, measurements were carried out to investigate the antioxidant properties against the O2-‧ radical. The results obtained by the linear polarization method indicate the photoactivity of the material due to the appearance of photocurrents for the illuminated electrodes. Also, using the method of linear polarization and chronoamperometry, it was shown that the highest amount of current is obtained in the first measurement, while in other measurements we have lower amounts of current due to photocorrosion of the active material. In comparing the currents for pure 5-ASK and the combination of 5-ASK and AA, it can be concluded that their combination results in higher amounts of current. This research result is important because combinations of sacrificial agents often appear in nature, so it was important to examine their interaction. Impedance measurements show that the impedance is lower for the illuminated electrodes, i.e. the charge transfer resistance is lower than for the non-illuminated electrodes, which confirms the good photoactivity of the electrode. The antioxidant properties were tested using the method of cyclic voltammetry, which indicates that increasing the concentration of 5-ASK in the solution of 5-ASK and AA will contribute to a better quenching of the superoxide radical
Determination of the harmful effect of rhodanide on the environment
No full textRazvojem civilizacije i industrije povećava se i broj i količina onečišćujućih tvari u okolišu. Prisutnost onečišćujućih tvari u okolišu može se odrediti analizom uzoraka vode, tla, zraka i biote. Praćenje onečišćujućih tvari ključno je za razumijevanje njihovih izvora, putanja i učinaka na okoliš i ono pomaže u donošenju regulacija i strategija za smanjenje njihovog štetnog učinka. Ključnu ulogu u procjeni utjecaja onečišćujućih tvari na okoliš imaju testovi ekotoksičnosti. Oni ispituju kako različite tvari, uključujući industrijske kemikalije, pesticide i farmaceutske proizvode, utječu na ekosustave i organizme prisutne u njima. Uobičajene metode testova ekotoksičnosti su laboratorijski testovi na bakterijama, algama, vodenim beskralježnjacima i ribama, kojima se utvrđuje toksičnost, bioakumulacija i dugoročni učinci na populacije i ekosustave. Ekotoksičnost rodanida, odnosno tiocijanata, u ovom radu ispitana je primjenom bakterijske kulture Pseudomonas putida i mikroalge Chlorella sp. Za ispitivanje ekotoksičnosti rodanida pripremljeno je šest različitih koncentracija rodanida, koje su iznosile: γR1 = 1 mg L^-1, γR2 = 10 mg L^-1, γR3 = 25 mg L^-1, γR4 = 50 mg L^-1,
γR5 = 75 mg L^-1, γR6 = 100 mg L^-1. Kao mjerilo utjecaja rodanida na navedene mikroorganizme određivana je CFU vrijednost, odnosno broj živih stanica mikroorganizama tijekom 72 sata izlaganja i određivani su postotci inhibicije rasta navedene bakterijske kulture i mikroalge. U slučaju bakterijske kulture Pseudomonas putida, najveći postotak inhibicije nakon 72 sata izlaganja iznosio je 59,17 %, dok je kod mikroalge Chlorella sp. najveći postotak inhibicije iznosio 71,43 %. Dobiveni podaci pokazuju da mikroalga Chlorella sp. pokazuje veću osjetljivost na rodanide od bakterijske kulture Pseudomonas putida.Along with the development of civilization and industry, the number and amount of pollutants in the environment increases. The presence of pollutants in the environment can be determined by analyzing samples of water, soil, air and biomes. Monitoring of pollutants is essential to understand their sources, pathways and effects on the environment and it helps to formulate regulation and strategy to reduce their harmful effect. Ecotoxicity tests play a key role in assessing the impact of pollutants on the environment. They examine how various substances, including industrial chemicals, pesticides and pharmaceuticals, affect ecosystems and the organisms present in them. Common methods of ecotoxicity tests are laboratory tests on bacteria, algae, aquatic invertebrates and fish, which determine toxicity, bioaccumulation and long-term effects on populations and ecosystems. In this paper, the ecotoxicity of rhodanide, or thiocyanate, was tested using the bacterial culture of Pseudomonas putida and the microalgae Chlorella sp. For testing the ecotoxicity of rhodanide, six different concentrations of rhodanide were prepared and applied, which were: γR1 = 1 mg L^-1, γR2 = 10 mg L^-1, γR3 = 25 mg L^-1, γR4 = 50 mg L^-1, γR5 = 75 mg L^-1, γR6 = 100 mg L^-1. As a measure of the effect of rhodanide on the mentioned microorganisms, the CFU value, i.e. the number of live cells of microorganisms during
72 hours of exposure, was determined, and the percentages of inhibition of the growth of the mentioned bacterial culture and microalgae were determined. In the case of the bacterial culture Pseudomonas putida, the highest percentage of inhibition after 72 hours of exposure was 59,17 %, while in the case of the microalgae Chlorella sp. the highest percentage of inhibition was 71,43 %. The obtained data show that the microalgae Chlorella sp. shows greater sensitivity to rhodanides than the bacterial culture of Pseudomonas putida
The study of metal-organic frameworks by electron paramagnetic resonance spectroscopy
No full textU sklopu ovog doktorskog rada istraživan je potencijal korištenja cirkonijevih
metalo-organskih mreža (MOF-ova) MOF-525 i PCN-223 s ugrađenim paramagnetskim ionima bakra(II) ili vanadila u porfirinskim prstenovima kao molekulskih kvantnih bitova. Za istraživanje mehanizama koherencije odnosno eksperimentalno određivanje relaksacijskog vremena spin-rešetka i relaksacijskog vremena spin-spin paramagnetskih iona korištena je metoda elektronske paramagnetske rezonancije (EPR). Da bi se dobili funkcionalni kvantni bitovi s dovoljno dugim relaksacijskim vremenima, paramagnetski centri u MOF-ovima razrijeđeni su s udjelom 10 % metalnih iona u porfirinskim prstenovima.
Kod bakrovih MOF-ova detektirana je koherencija najviše do temperature od 80 K, dok je za vanadilne MOF-ove koherencija detektirana čak do 200 K. Daljnjim razrjeđenjem vanadilnih iona s 10 % na 5 % u PCN-223 postignuto je produljenje relaksacijskih vremena koje je najizraženije pri temperaturama nižim od 100 K, gdje je dominantan utjecaj međudjelovanja spin-spin. Dodatno produljenje obaju relaksacijskih vremena i postignuto je ugradnjom molekula fulerena u pore PCN-223. Takvo ponašanje može se objasniti djelomičnom izmjenom otapala koje posjeduje nuklearne spinove sa spinski gotovo neaktivnim fulerenom kao i kroz usporavanje spin-fononskih procesa koji utječu na relaksacijsko vrijeme . Istraživani spojevi pokazali su linearnu ovisnost Rabijeve frekvencije o intenzitetu oscilirajućeg magnetskog polja što je potvrda mogućnosti koherentne spinske manipulacije. Mogućnost stvaranja proizvoljnog superpozicijskog stanja dokazalo je potencijal korištenja tih materijala kao molekulskih spinskih kvantnih bitova. Nadalje, dokazana je primjenjivost Carr-Purcell-Meiboom-Gillova (CPMG) impulsnog slijeda na produljenje koherencijskog vremena ispitivanih spojeva.In this dissertation, the potential of using zirconium metal-organic frameworks (MOFs) MOF-525 and PCN-223 with incorporated paramagnetic copper(II) or vanadyl ions in porphyrin rings as molecular spin qubits was investigated. The electron paramagnetic resonance (EPR) method was used to investigate the coherence mechanism, i.e.
the experimental determination of the electron spin-lattice, , and phase-memory, , relaxation times. To obtain viable qubits with sufficiently long relaxation times, the paramagnetic centers in MOFs were diluted with 10 % metal ions in porphyrin rings. Coherence was detected up to 80 K for copper MOFs and up to 200 K for vanadyl MOFs. With a further dilution of vanadyl ions from 10% to 5% in PCN-223, an additional extension of the relaxation time is achieved, which is most pronounced at temperatures below 100 K, where the spin-spin interaction has a dominant influence. The incorporation of fullerene molecules into the structure of PCN-223 leads to an extension of both relaxation times i . This behavior can be explained by the partial exchange of solvent, which has nuclear spins, with almost spin non-active fullerene and by the slowing down of spin-phonon processes that influence . The investigated compounds showed a linear dependence of the Rabi frequency as a function of the oscillating microwave magnetic field, indicating the possibility of coherent spin manipulation. The ability to create an arbitrary superposition of states proved the potential to use these materials as molecular spin qubits. Furthermore,
the Carr-Purcell-Meiboom-Gill (CPMG) pulse EPR sequence was successfully used to extend the coherence time of the investigated compounds