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Preparation and characterization of natural zeolite clinoptilolite coated with sulfide species - determination of the selectivity of the prepared sample towards Hg(II) in relation to other divalent heavy metal cations : diplom athesis
No full textPrirodni zeolit klinoptilolit obložen sulfidnim specijama (SZ-25) dobiven je kemijskom modifikacijom prirodnog zeolita (PZ) klinoptilolita s Na 2 S pri 25 °C. Svrha modifikacije zeolita bila je poboljšati sorpciju Hg(II). Klasična kemijska analiza, kisela i bazična svojstva određena Bohemovom metodom, kemijsko ponašanje pri različitim pH o vrijednostima, zeta potencijal pri različitim pH o vrijednostima, specifična površina, rendgenska difrakcijska analiza praškastog uzorka (XRPD), pretražna elektronska mikroskopija s energijsko disperzivnom rendgenskom spektroskopijom (SEM-EDS), infracrvena spektroskopija s Fourierovom transformacijom (FTIR) kao i termogravimetrijska analiza (TG-DTG) korišteni su za detaljnu komparativnu mineralošku i fizikalno-kemijsku karakterizaciju PZ i SZ-25. Rezultati su pokazali da je površina SZ-25 uspješno obložena sulfidnim specijama u obliku FeS i CaS. Kemijska modifikacija uzrokovala je povećanje bazičnosti i ukupnog negativnog naboja površine zbog povećanja funkcionalnih skupina koje sadrže kisik te smanjenje specifične površine i kristaliničnosti zbog stvaranja nakupina koje sadrže sumpor na površini zeolita. Modificirani uzorak, SZ-25 pokazao je iznimnu selektivnost prema Hg(II) u odnosu na ostale dvovalentne katione teških metala. Utvrđen je sljedeći redoslijed selektivnosti: Hg > Pb > Cd > Zn > Cu > Ni > Co > Mn. Na temelju dobivenih rezultata, modificirani uzorak se čini izvrsnim izborom za sanaciju područja onečišćenih živom.Natural zeolite clinoptilolite coated with sulfide species (SZ-25) was obtained by chemical modification of natural zeolite clinoptilolite (PZ), with Na 2 S at 25 °C. The purpose of the zeolite modification was to improve the sorption of Hg(II). Chemical analysis, acid and basic properties determined by Bohem’s method, chemical behavior at different pH o values, zeta potential, cation- exchange capacity (CEC), specific surface area, X-ray powder diffraction (XRPD), scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), as well as thermogravimetry (TG-DTG) were used for detailed comparative mineralogical and physico-chemical characterization of PZ and SZ-25. The results showed that the surface of SZ-25 was successfully coated with sulfide species in the form of FeS and CaS. Chemical modification caused an increase in basicity and total negative surface charge due to an increase in functional groups containing oxygen and a decrease in specific surface area and crystallinity due to the formation of clusters containing sulfur on the zeolite surface. The modified sample, SZ-25, showed exceptional selectivity towards Hg(II) in relation to other divalent heavy metal cations. The order of selectivity was determined as follows: Hg > Pb > Cd > Zn > Cu > Ni > Co > Mn. Based on the obtained results, the modified sample appears to be an excellent choice for the remediation of mercury-contaminated sites
Microclimatic features of the cave Golubnjača in Plitvice Lakes National Park
No full textU diplomskom radu su prikupljeni i analizirani podaci o mikroklimi špilje Golubnjače u NP Plitvička jezera. Do 1991. godine Golubnjača je bila turistička špilja. Podaci su prikupljeni memorijskim termohidrografima, anemometrom te logerom za koncentraciju ugljikovog dioksida. Mikroklimatski parametri su mjereni 2022. i 2023. godine. Analizirani su i podaci o antropogenom utjecaju u špilji tijekom radionice restauriranja. Svrha mjerenja bila je odrediti na koji način se mikroklima u podzemlju mijenja i zašto te što i kako utječe na promjene koje se događaju.The thesis collects and analyses data on the microclimate of the Golubinjača cave, which is located in the Plitvice Lakes National Park. Until 1991, the cave was used for tourism. Data were collected with memory thermohydrographs, anemometer, and carbon dioxide concentration logger. Microclimatic parameters were measured in 2022 and 2023. Moreover, the data on the anthropogenic impact on the cave during the restoration workshop was also analysed. The purpose is to determine how the microclimate of Golubnjača is changing and why as well as what affects the changes that occur and how
The influence of inhibitors on the protective properties of biological acrylate coating
No full textU skladu s rastućom potražnjom za ekološki prihvatljivim alternativama u industriji premaza,
razvijen je vodorazrjedivi akrilatni premaz na bioosnovi za direktnu zaštitu metalnih površina.
U radu su evaluirane karakteristike razvijenog bio-premaza uspoređujući tri vrste inhibitora
korozije: hlapljivi inhibitor korozije, inhibitor korozije na bazi metalnog kompleksa te
inhibitor korozije na bazi aminokarboksilata. U eksperimentalnom dijelu određena su
fizikalna i mehanička svojstva ispitnih premaza s fokusom na usporedbu zaštitnih svojstava
inhibitora korozije koristeći ispitivanje u vlažnoj i slanoj komori, te elektrokemijsku
impedancijsku spektroskopiju (EIS). Rezultati ovog rada doprinose kontinuiranim naporima u
razvoju održivih premaza s poboljšanim svojstvima zaštite od korozije te pruža vrijedne
informacije o performansama ekoloških alternativa u usporedbi s tradicionalnim premazima.In response to the growing demand for environmentally friendly alternatives in the coating
industry, a water-dilutable bio-based acrylic coating for DTM protection has been developed.
The characteristics of the developed bio-coating were evaluated by comparing three types of
corrosion inhibitors: volatile corrosion inhibitor, metal complex-based corrosion inhibitor,
and amino carboxylate-based corrosion inhibitor. In the experimental section, the physical
and mechanical properties of the test samples were determined, with a focus on comparing the
protective properties of corrosion inhibitors using humidity testing, salt spray testing, and
electrochemical impedance spectroscopy (EIS). The results of this study contribute to ongoing
efforts in the development of sustainable coatings with improved corrosion protection
properties and provide valuable information on the performance of environmental alternatives
compared to traditional coatings
APPLICATION OF PHOTOGRAPHY IN ALGAE AND CYANOBACTERIA DETERMINATION
No full text“Whole slide imaging” (WSI) je relativno nova fotomikrografska metoda koja se koristi za dobivanje
fotomikrografija velike razlučivosti cjelokupnog preparata. Komercijalni WSI sustavi su relativno skupi što
ovisi o različitim stupnjevima mogućnosti koje WSI moţe imati, stoga će u ovom radu biti predstavljena
povoljna opcija stvaranja WSI fotomikrografija, koja je testirana na algalnim preparatima. WSI još nije
primijenjen u fikologiji te ovaj rad daje uvid u potencijalnu upotrebu ove metode za determinaciju algi
prilikom kvalitativne i/ili kvantitativne analize. Pomoću digitalne kamere/fotoaparata, adaptera i računalnog
programa, moguće je svaki mikroskop pretvoriti u jednostavan WSI sustav, što ima veliki potencijal u
srednjem i visokoškolskom obrazovanju.“Whole slide imaging” (WSI) is a relatively new photomicrography method which is utilized for acquiring
high-resolution photomicrographs. Commercial WSI systems are expensive and with different numbers of
options, therefore we will present affordable options for creating WSI photographs. There are no examples of
WSI application in phycology so the system was tested on algal slides to provide insight into the potential use
of WSI in algae determination for qualitative and/or quantitative analysis. Using a DSLR, adapter and
software, it is possible to convert any microscope into a simple WSI system, which also has big potential in
highschool and university education
THE EFFECT OF PESTICIDES ON BIOFILM ACTIVITY IN SOIL
No full textU današnje vrijeme sve intenzivnije tretiranje zemlje
pesticidima dovelo je do stvaranja brojnih ekoloških problema. Sve veća prisutnost polutanata
u tlu dovodi do promjene njegovog sastava i kvalitete. Biofilmovi igraju važnu ulogu u
održavanju tla, a učinci pesticida na njihovu metaboličku aktivnost ostaju slabo istraženi. Ovaj
rad pokušava proučiti i objasniti učinke pesticida propikonazola i klorantraniliprola na
mikrobne zajednice u močvarnom glejnom tlu prije i nakon suše.Nowadays, intensive treatment of soil with pesticides is leading to numerous
ecological problems. The ever increasing presence of pollutants in soil is inducing a change in
it's composition and quality. Biofilms play an important role in maintaining soil fertility and
effects of pesticides on microbial activity remain poorly researched. This thesis tries to study
and explain effects of propiconazole and chlorantraniliprole on microbial communities in
wetland gleyic soil before and after drought
MICROPHYTE DIVERSITY IN EPIXYLON IN LAKE SAKADAŠ
No full textIstraživanje raznolikosti mikrofita na grančicama bijele vrbe (Salix alba L.) provedeno je u Sakadaškom jezeru,
poplavnom području parka prirode Kopački rit u ranom jesenskom razdoblju 2019. godine. Uzorci su prikupljeni
na tri odabrane postaje u jezeru. Mjereni su fizikalno-kemijski parametri vode te je određen kvalitativni i
kvantitativni sastav mikrofita u obraštajnim zajednicama. Stabilni hidrološki uvjeti bez plavljenja i visoke
koncentracije hranjivih tvari pridonijele su razvoju obraštaja i velikoj raznolikosti mikrofita (ukupno 213 svojti),
posebice iz skupine dijatomeja i zelenih alga. U obraštaju su tijekom cijelog istraživanja brojem jedinki
dominirale dijatomeje. Rezultati istraživanja ukazuju da su potopljene grančice vrbe pogodna podloga za
naseljavanje mikrofita u stabilnim hidrološkim uvjetima i njihovo zadržavanje u poplavnom području Kopačkog
rita može pridonijeti očuvanju biološke raznolikosti ovog jedinstvenog sustava.The investigation of microphyte diversity on white willow twigs (Salix alba L.) was conducted in Lake Sakadaš,
a floodplain area of the Nature Park Kopački rit in the early autumn of 2019. The samples were collected at three
selected stations in the lake. The physico-chemical parameters were measured and the qualitative and
quantitative composition of microphytes in periphyton was analysed. The stable hydrological condition without
flooding and high nutrient concentration contributed to the periphyton development and high microphyte
diversity (a total of 213 taxa) particularly those from the groups of diatoms and green algae. Considering the
microphytes abundance, during the investigation period the dominant taxa were diatoms. The results of the
investigation indicate that in stable hydrological conditions submerged willow twigs represent a suitable
substrate for the colonization of microphytes. Thus, their retention in the Kopački Rit can contribute to the
preservation of biological diversity of this unique floodplain area
Vapnik–Chervonenkisova dimenzija slučajnog grafa
No full textOvaj diplomski rad proučava Vapnik-Chervonenkisovu (VC) dimenziju u kontekstu slučajnih grafova. U radu smo uveli osnovne pojmove iz teorije grafova i VC dimenzije, a zatim analizirani modele slučajnih grafova s fokusom na model . Glavni rezultat rada je određivanje funkcije praga za svojstvo da slučajni graf ima VC dimenziju barem . Taj se dokaz oslanja na koncepte -razdvajajućih grafova i generirajućih podgrafova te pomoću funkcija gustoće dobivamo granice za VC dimenziju. Na kraju, analizirano je ponašanje VC dimenzije za brzo padajuće vrijednosti , koristeći Jansonovu nejednakost.The goal of this thesis is to explore the Vapnik--Chervonenkis (VC) dimension in the context of random graphs. We begin by introducing foundational concepts from graph theory and VC dimension, and then analyze random graph models, focusing on the model. The main contribution of the thesis is the identification of the threshold function for the property that a random graph has VC dimension at least . We employ the notions of -shattering graphs and generating subgraphs, and use density functions to derive bounds for the VC dimension. Finally, we study the behavior of the VC dimension for rapidly decreasing , applying Janson’s inequality
Development of a method for the determination of ritlecitinib in blood plasma using LC/QToF technique
No full textAlopecija areata kronična je autoimuna bolest koja uzrokuje gubitak kose. Do nedavno dostupni tretmani i lijekovi u terapiji alopecije areate pokazivali su ograničenu učinkovitost i visok rizik od nuspojava. Razjašnjenje molekularnih mehanizama uključenih u patogenezu alopecije areate omogućilo je razvoj lijekova s novim mehanizmima djelovanja. Godine 2023. odobren je ritlecitinib, selektivni inhibitor JAK3 i TEC kinaza, za liječenje odraslih i adolescenata starijih od 12 godina u dozi od 50 mg jedanput dnevno. Ritlecitinib, kao ciljani lijek koji pokazuje klinički značajnu učinkovitost, predstavlja veliki iskorak u terapiji AA. U ovom radu predložena je bioanalitička metoda za određivanje ritlecitiniba u plazmi. Primjenom ekstrakcije čvrstom fazom s inovativnim sorbensima za pripremu biološkog uzorka te tekućinske kromatografije visoke djelotvornosti u sprezi s tandemskom masenom spektrometrijom s Q-ToF analizatorom za analizu uzorka, razvijena je metoda koja omogućuje pouzdano određivanje ritlecitiniba. Postignut je širok linearni raspon kvantifikacije pri iznimno niskim koncentracijama od 10 ng/mL do 2000 ng/mL.Alopecia areata is a chronic autoimmune disease that causes hair loss. Formerly available treatments and drugs for alopecia areata therapy showed limited effectiveness and a high risk of side effects. Understanding the molecular mechanisms involved in the pathogenesis of alopecia areata has enabled the development of drugs with new mechanisms of action. In 2023, ritlecitinib, a selective inhibitor of JAK3 and TEC kinases, was approved for the treatment of adults and adolescents over 12 years old at a dose of 50 mg once daily. Ritlecitinib, as a targeted drug demonstrating clinically significant efficacy, represents a major breakthrough in AA therapy. This paper proposes a bioanalytical method for the determination of ritlecitinib in blood plasma. By applying solid-phase extraction with innovative sorbents for biological sample preparation and high-performance liquid chromatography coupled with tandem mass spectrometry using a Q-ToF analyzer for sample analysis, a method was developed that enables reliable quantification of ritlecitinib. A wide linear quantification range was achieved at extremely low concentrations from 10 ng/mL to 2000 ng/mL
The effect of temperature on the composition and quality of royal jelly
No full textMatična mliječ je izlučevina podždrijelne i prednjočeljusne žlijezde pčela radilica i predstavlja dobro izbalansiranu hranu kojom pčele hrane ličinke i maticu. Usprkos izuzetnim nutritivnim svojstvima, matična je mliječ osjetljiva na svjetlost, vlagu, zrak te posebice na toplinu. Cilj je ovog rada bio utvrditi utjecaj temperature na sastav i kakvoću matične mliječi primjenom različitih toplinskih tretmana. Istraživanje je provedeno na četiri uzorka matične mliječi prikupljenih iz zajednica sive pčele (Apis mellifera carnica). Uzorci su analizirani metodom infracrvene (FTIR-ATR) spektroskopije u izvornom stanju, nakon izlaganja toplinskom tretmanu (34 °C) u trajanju od 15 minuta te nakon pet dana izloženosti sobnoj temperaturi (24 °C). Rezultati spektralne analize su pokazali kako temperatura ima negativan utjecaj na sastav i kakvoću matične mliječi s obzirom na to da su u svim analiziranim uzorcima uočene spektralne alteracije u vidu pada intenziteta apsorpcijskih vrpci koje ukazuju na promjene (degradaciju) sastava i kakvoće matične mliječi pod utjecajem toplinskih tretmana. Također, rezultati ovog istraživanja ukazuju na to da je matična mliječ osjetljivija na visoke temperature u kraćem vremenskom razdoblju (nakon 15 minuta izloženosti 34 °C), nego na izloženost sobnoj temperaturi kroz duži period (nakon 5 izloženosti 24 °C).Royal jelly is a secretion of the hypopharyngeal and mandibular glands of worker bees and represents a well-balanced food used for feeding larvae and the queen bee. Despite its exceptional nutritional properties, royal jelly is sensitive to light, moisture, air and especially heat. The aim of this study was to determine the influence of temperature on the composition and quality of royal jelly by applying different heat treatments. The research was conducted on four royal jelly samples collected from colonies of the Carniolan bee (Apis mellifera carnica). The samples were analyzed by infrared (FTIR-ATR) spectroscopy as obtained, after exposure to heat treatment (34
°C) for 15 minutes, and after five days of exposure to room temperature (24 °C). The results of the spectral analysis showed that temperature has a negative impact on the composition and quality of royal jelly, given that spectral alterations in terms of decrease in the intensity of absorption bands were observed in all analyzed samples, indicating changes (degradation) in the composition and quality of royal jelly under the influence of heat treatments. The results of this study also indicate that royal jelly is more sensitive to high temperatures in a shorter period of time (after 15 minutes of exposure to 34 °C) than to exposure to room temperature over a longer period (after 5 minutes of exposure to 24 °C)
Analysis of the microstructure in the weld joint on hydrogen pipeline made of API 5L X70
No full textCjevovodi za transport nafte, plina te sve češće i vodika suočavaju se s izazovima očuvanja
mehaničkih svojstava zbog povećanih zahtjeva za promjerima, tlakovima i raznolikosti
transportiranih resursa, što je potaknulo upotrebu čelika visoke čvrstoće poput API 5L X70.
Vodik, kao gorivo budućnosti, dodatno ističe potrebu za specifičnim procesima toplinskomehaničke obrade čelika, koji prilagodbom mikrostrukture osiguravaju visoku čvrstoću,
žilavost i otpornost na djelovanje vodika. Budući da puknuća cjevovoda često počinju na
zavarima, detaljna istraživanja mehaničkih svojstava zavarenih spojeva ključna su za sigurnost
i pouzdanost transportnih sustava. Vodikova degradacija značajno utječe na mehanička svojstva
čelika, povećavajući rizik od havarija u cjevovodima, spremnicima i strojevima, a njen
intenzitet ovisi o uvjetima okoline, koncentraciji vodika i svojstvima materijala.
U eksperimentalnom dijelu rada, zavaren spoj izrađen automatiziranim MAG postupkom
podvrgnut je detaljnom ispitivanju kako bi se analizirala njegova struktura i mehanička
svojstva. Provedena su ispitivanja makrostrukture, mikrostrukture i tvrdoće, pri čemu su
posebno obrađeni osnovni materijal, zona utjecaja topline te metal zavara. Analiza
makrostrukture uključivala je pregled geometrije zavarenog spoja, dok su mikrostrukturna
ispitivanja pružila uvid u detalje rasporeda zrna i promjena u mikrostrukturi unutar zavara i
okolnih zona. Mjerenje tvrdoće metodom po Vickersu provedeno je radi kvantifikacije
mehaničke otpornosti različitih dijelova zavarenog spoja, čime su dobiveni ključni podaci za
procjenu kvalitete zavara i njegove otpornosti na vanjske utjecaje, poput djelovanja vodika.Pipelines for the transport of oil, gas, and increasingly – hydrogen, face challenges in
maintaining mechanical properties due to growing demands for larger diameters, higher
pressures, and a wider variety of transported resources. This has driven the adoption of highstrength steels such as API 5L X70. Hydrogen, as the fuel of the future, further underscores the
need for specific thermo-mechanical processing of steel to tailor microstructures that ensure
high strength, toughness, and resistance to hydrogen effects. Since pipeline failures often
originate at welds, detailed investigations into the mechanical properties of welded joints are
essential for the safety and reliability of transport systems.
Hydrogen degradation significantly impacts the mechanical properties of steel, increasing the
risk of failures in pipelines, storage tanks, and machinery. The severity of this phenomenon
depends on environmental conditions, hydrogen concentration, and material properties.
In the experimental part of the study, a welded joint created using an automated MAG process
was subjected to detailed examinations to analyze its structural and mechanical properties. Tests
included macrostructure, microstructure, and hardness evaluations, focusing on the base
material, the heat-affected zone and the weld metal. The macrostructural analysis provided an
overview of the general appearance of the welded joint, while the microstructural tests offered
insights into grain distribution and microstructural changes within the weld and surrounding
areas. Hardness measurements using the Vickers method were conducted to quantify the
mechanical resistance of different parts of the welded joint, yielding critical data for assessing
weld quality and its resistance to external effects, such as hydrogen interaction