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Investigation of mechanochemicalreactions by in situ Raman spectroscopy - contributions of physical and chemical factors
No full textU sklopu ove disertacije istražen je utjecaj eksperimentalnih parametara i molekulske strukture na mehanokemijsku reaktivnost. Na modelnoj reakciji jednostupanjske trimerizacije niklovog(II) dibenzoilmetanata sustavno je analiziran utjecaj frekvencije mljevenja, veličine i mase kuglice za mljevenje na kinetiku isključivo mehanički aktivirane transformacije. Uloga i učinak udarca kuglice ispitan je za proces kontinuiranog mljevenja u ukupnoj masi uzorka te na sloju praha, čime su povezane globalna i lokalna kinetika. Uspoređeni su reakcijski mehanizmi u kugličnom mlinu, gdje je dominatna mehanička sila, te u sustavu bez kuglica, odnosno u rezonancijsko-akustičnoj miješalici na modelu sinteze kalkonâ. Pored fizikalnih čimbenika, proučen je utjecaj elektronske strukture i aditiva na mehanosintezu iminâ te aza- Michaelovih adukata. Tim eksperimentima potvrđena je primjenjivost Hammettove korelacije, koncepta razvijenog za reakcije u otopini.As part of this doctoral thesis, the influence of experimental parameters and molecular structure on mechanochemical reactivity was investigated. Using the one-step trimerization of nickel(II) dibenzoylmethanate as a model system, the effects of milling frequency, ball size, and ball mass on the kinetics of a purely mechanically activated transformation were systematically analyzed. The role of ball impacts was examined both within the bulk and on the powder layer, thereby connecting global and local kinetics. Reaction mechanisms were compared between ball milling, where mechanical impact is the dominant force, and a system without milling balls, specifically a resonance acoustic mixer, using chalcone synthesis as a model reaction. In addition to physical factors, the influence of electronic structure and additives on the mechanosynthesis of imines and aza-Michael adducts was studied. These experiments confirmed the applicability of the Hammett correlation, a concept originally developed for solution-phase reactions
Basal levels of corticosterone in the serum of sympatric populations of the lizards Podarcis siculus and Podarcis melisellensis
No full textZidne gušterice roda Podarcis prevladavajuća su skupina gmazova u južnoj Europi. Sve više istraživanja bavi se odnosom između dvije nativne vrste istočnog Jadrana, Podarcis siculus i Podarcis melisellensis, a do sad se P. siculus u brojnim terenskim i eksperimentalnim istraživanjima pokazala superiornijom i dominantnijom u odnosu na endemičnu P. melisellensis. Kortikosteron, poznat kao hormon stresa, može imati značajan doprinos u odnosu ove dvije vrste, s obzirom na to da su zabilježene njegove uloge u agresivnosti, dominaciji i modulaciji brojnih fizioloških odgovora. Upravo radi toga, u svrhu boljeg razumijevanja biološke prednosti vrste P. siculus nad endemičnom P. melisellensis, glavni cilj ovog istraživanja bio je otkriti postoji li razlika u bazalnoj razini kortikosterona u serumu dviju vrsta gušterica s područja Sinja i Knina. Optimiziranom metodom ELISA utvrđena je značajno veća razina kortikosterona u serumu P. siculus, no nije uočena značajna razlika u razinama hormona među spolovima niti različitim lokacijama. Zaključili smo kako je razina bazalnog kortikosterona vrsno specifična i vjerojatno povezana s agresivnijim ponašanjem, a potencijalno i s nizom boljih fizioloških prilagodbi, koji potpomažu kompetitivnom isključivanju fiziološki manje adaptivne P. melisellensis.Wall lizards of the genus Podarcis are a predominant group of reptiles in southern Europe. Increasing research focuses on the relationship between two native species of the eastern Adriatic, Podarcis siculus and Podarcis melisellensis. To date, P. siculus is superior and more dominant than the endemic P. melisellensis in numerous field and experimental studies. Corticosterone, known as the stress hormone, can have a significant contribution to the relationship between these two species, given its role in aggressiveness, dominance and modulation of numerous physiological responses. To better understand the biological advantage of P. siculus over the endemic P. melisellensis, the primary aim of this study was to determine whether there is a difference in basal corticosterone levels in the serum of the two lizard species from the Sinj and Knin regions. Using an optimized ELISA method, significantly higher corticosterone levels were observed in P. siculus while no significant differences in hormone levels were observed between the sexes or locations. We concluded that basal corticosterone levels were species-specific and probably associated with more aggressive behavior and potentially with a series of superior physiological adaptations, which support the competitive exclusion of the physiologically less adaptive P. melisellensis
Activation mechanism of MntR protein from the bacterium Halakalibacterium halodurans for DNA binding
No full textHalalkalibacterium halodurans je industrijski važna alkalofilna bakterija koja, da bi preživjela, zahtijeva precizan i osjetljiv regulacijski mehanizam održavanja homeostaze iona mangana (Mn2+). Ključni protein u regulacijskom mehanizmu bakterije H. halodurans je MntR - transkripcijski faktor koji selektivno veže ione Mn2+ i posljedično DNA, regulirajući time gensku ekspresiju proteina uključenih u homeostazu Mn2+. Simulacije molekulske dinamike u trajanju 400-1200 ns korištene su za proučavanje strukturnih i dinamičkih svojstava različitih formi proteina s obzirom na prisutnost Mn2+ iona u veznom mjestu. Kada MntR ima Mn2+ u veznom mjestu, dolazi do približavanja DNA-veznih domena te rigidnije konformacije proteina. Takav protein ostvaruje specifične i stabilne interakcije u simulacijama s DNA. MntR u slobodnoj formi zauzima širu i fleksibilniju strukturu, koja se na DNA veže nespecifičnim i kratkoživućim interakcijama. Time je slobodnom proteinu omogućeno lateralno kretanje duž DNA, do trenutka vezanja Mn2+ u vezna mjesta i aktivacije proteina za specifično vezanje u velike utore DNA.Halalkalibacterium halodurans is an industrially important alkalophilic bacterium that, in order to survive, requires a precise and sensitive regulatory mechanism to maintain homeostasis of manganese ions (Mn2+). The key protein in the regulatory mechanism of the bacterium H. halodurans is MntR - a transcription factor that selectively binds the Mn2+ ion and consequently DNA, thereby regulating gene expression of proteins involved in Mn2+ homeostasis. Molecular dynamics simulations lasting 400-1200 ns are used to study the structural and dynamic properties of different protein forms with regard to the presence of Mn2+ ions in the binding site. When MntR has Mn2+ in its binding site, the DNA-binding domains come closer, and the conformation of the protein becomes more rigid. Such a protein achieves specific and stable interactions in simulations with DNA. In its free form, MntR occupies a wider and more flexible structure, which binds to DNA through non-specific and short-lived interactions. This enables the free protein to move laterally along the DNA, until the binding of Mn2+ in the binding sites activates the protein for specific binding in the large grooves of DNA
Plan upravljanja istraživačkim podacima - Utjecaj valova vezanih uz otok na primarnu produkciju - ISLAND (IP-2020-02-9524)
No full textPlan upravljanja istraživačkim podacima za istraživački projekt Hrvatske zaklade za znanost: Utjecaj valova vezanih uz otok na primarnu produkciju - ISLAND (IP-2020-02-9524), za 3. projektno razdoblje (01.07.2023. - 24.06.2025.)
The effect of hydrocortisone and ascorbic acid on viability and activity of major signaling pathways in human ovarian cancer cell lines during carboplatin therapy
No full textPovišena razina hormona stresa kortizola povezana je s povećanjem invazivnog potencijala
stanica raka jajnika te može utjecati na odgovor pacijenata na terapiju i preživljenje. Uočeno
je da visoka doza askorbinske kiseline (vitamina C) može uzrokovati smanjenje razine
kortizola u stresnim uvjetima. Također, askorbinska kiselina korištena u visokim
(milimolarnim) dozama može djelovati citotoksično na različite tumorske stanice, uključujući
stanice raka jajnika, te djelovati sinergistički u kombinaciji s kemoterapijom. Cilj ovog rada
bio je istražiti utječu li hidrokortizon, sintetski oblik kortizola, te askorbinska kiselina u
kombinaciji s kemoterapeutikom karboplatinom na preživljenje staničnih linija raka jajnika
čovjeka IGROV-1 i OVCAR-8. Dodatni cilj bio je istražiti utječe li tretman hidrokortizonom
i askorbinskom kiselinom, u kombinaciji s karboplatinom na aktivnost signalnih puteva MAPK
(engl. mitogen-activated protein kinase) i PI3K/AKT (engl. phosphoinositide-3-kinase/Akt).
Preživljenje stanica ispitano je testom redukcije MTT-a (3-(4,5-dimetiltiazol 2-il)-2,5-
difeniltetrazolijev bromid) i bojenjem stanica kristal violetom, a razine biljega aktivnosti
signalnih puteva metodom Western blot. Rezultati su pokazali da hidrokortizon u kombinaciji
s karboplatinom povećava preživljenje stanične linije IGROV-1, dok nije imao značajan učinak
kod linije OVCAR-8. Askorbinska kiselina pokazala je citotoksični učinak na obje stanične
linije, a u kombinaciji s karboplatinom izazvala je dodatno smanjenje preživljenja. Osim toga,
tretman askorbinskom kiselinom je izazvao smanjenje aktivnosti puta MAPK u staničnoj liniji
IGROV-1 te puta PI3K/AKT u liniji OVCAR-8. Ovi rezultati ukazuju na ulogu hidrokortizona
i askorbinske kiseline u promjeni odgovora na kemoterapiju karboplatinom kod različitih
tipova raka jajnika.Increased levels of the stress hormone cortisol are associated with increased invasive potential
of ovarian cancer cells and can influence response to therapy and survival. It was observed that
high doses of ascorbic acid (vitamin C) can cause a decrease in cortisol levels under stressful
conditions. In addition, ascorbic acid used in high (millimolar) doses can have cytotoxic effect
on different tumor cells, including ovarian cancer cells, and act synergistically in combination
with chemotherapy. The aim of this thesis was to investigate whether hydrocortisone, a
synthetic form of cortisol, and ascorbic acid, in combination with the chemoterapeutic agent
carboplatin affect the survival of IGROV-1 and OVCAR-8 human ovarian cancer cell lines.
The additional aim was to explore whether treatments with hydrocortisone and ascorbic acid,
in combination with carboplatin, affect the activity of the MAPK (mitogen-activated protein
kinase) and PI3K/AKT (phosphoinositide-3-kinase/Akt) signaling pathways. Cell survival was
assessed using the MTT assay (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)
and crystal violet staining, while the levels of signaling pathway activity markers were
analyzed by Western blot. The results showed that hydrocortisone combined with carboplatin
increased the survival of the IGROV-1 cell line, while it had no significant effect on the
OVCAR-8 cells. Ascorbic acid showed cytotoxic effect on both cell lines, and in combination
with carboplatin it further reduced survival. In addition, ascorbic acid treatment caused
decrease in the MAPK pathway activity in IGROV-1 and PI3K/AKT pathway activity in the
OVCAR-8 cell line. These results indicate the role of hydrocortisone and ascorbic acid in
modulating the response to carboplatin chemotherapy in different types of ovarian cancer
Longitudinal distribution of benthic macroinvertebrates of the River Cetina
No full textRijeka Cetina podložna je značajnim utjecajima hidromorfološke degradacije uzrokovanih antropogenim djelovanjem. Glavni uzrok predstavljaju hidroelektrane i akumulacije koje uvelike narušavaju hidromorfologiju rijeke. Makrozoobentos je skupina bentičkih beskralješnjaka koja se najčešće koristi u biomonitoringu, jer se smatraju dobrim pokazateljima promjena u vodenim ekosustavima. Glavni ciljevi ovog rada su odrediti sastav i strukturu makrozoobentosa duž toka rijeke Cetine, izraditi hidromorfološke ocjene postaja za koje to do sada nije izrađeno, izdvojiti glavne okolišne čimbenike koji utječu na sastav zajednice makrozoobentosa na istraživanim postajama te usporediti sastav i strukturu makrozoobentosa s prethodnim istraživanjima. Uzorci su uzeti ručnom bentos mrežom, pohranjeni u 96 %–tnom etanolu te pripremljeni i izolirani prema AQEM metodologiji. Postaje Vinalić, Panj, Čikotina lađa i Radmanove mlinice imaju sastav i strukturu zajednica makrozoobentosa u skladu s dijelom toka u kojem se nalaze, dok se postaja Trilj izdvaja zbog povećane koncentracije organske tvari. Postaja Nejašmić izdvaja se malom abundancijom i malim brojem svojti zbog ograničenih izvora hrane i relativno male raznolikosti staništa. Karakter supstrata znatno utječe na sastav i strukturu zajednica. Na postaji Čikotina lađa, 2024. godine je pronađeno značajno više jedinki nego li 2005. godine.The Cetina River is under considerable influence of hydromorphological degradation caused by anthropogenic impacts. Hydropower plants and reservoirs significantly alter the hydromorphology of the river in certain sections. Benthic macroinvertebrates are frequently used in biomonitoring as they are good indicators of changes in aquatic ecosystems. The main objectives of this study were to determine the composition and structure of macrozoobenthos along the Cetina River, to conduct hydromorphological assessments for previously unstudied sites, to identify the main environmental factors influencing the macroinvertebrate community composition and to compare the composition and structure of macrozoobenthos with previous studies. The samples were collected using a hand-held benthic net, preserved in 96 % ethanol, isolated and analysed using the AQEM methodology. At the Vinalić, Panj, Čikotina Lađa and Radmanove Mlinice sites, the community composition and structure of macrozoobentos are consistent with the river section in which they are located. The Trilj sampling site is characterised by an increased organic matter concentration and the Nejašmić site by a low abundance and species richness, which is due to the limited diversity of microhabitats and food sources. At the Čikotina Lađa site, a significantly higher abundance was recorded in 2024 than in 2005
THE ROLE OF DEHYDROEPIANDROSTERONE AND ITS SULFATE, AS WELL AS BRAINDERIVED NEUROTROPHIC FACTOR IN DEMENTIA
No full textDemencija predstavlja jedan od najznačajnijih medicinskih i ekonomskih izazova današnjice.
Najčešći uzroci demencije su Alzheimerova bolest, obilježena nakupljanjem proteina Aβ i tau
u mozgu, te vaskularna demencija, izazvana ograničenim dotokom krvi u mozak. Kako trenutno
dostupne terapije samo ublažavaju simptome demencije, uz ograničenu učinkovitost i
nuspojave, istraženi su neuroprotektivni učinci dehidroepiandrosterona i njegovog sulfata
(DHEA(S)) te moždanog neurotrofnog čimbenika (BDNF). U istraživanju su korišteni stanični
(primarna kultura neurona miševa C57BL/6 i stanična linija SH-SY5Y neuroblastoma čovjeka,
izložene oligomerima Aβ, odnosno deprivaciji kisika i glukoze) i životinjski (miševi C57BL/6
injicirani s oligomerima Aβ i transgenični miševi 3xTg-AD) modeli demencija, te uzorci krvi
ispitanika s demencijom i normalnom kognicijom. Rezultati istraživanja ukazuju na blago
neuroprotektivno djelovanje DHEA(S)-a i BDNF-a u staničnim i životinjskim modelima
demencije te na smanjene razine DHEA(S)-a i povećane razine BDNF-a u plazmi ispitanika s
demencijom, upućujući na preventivni i/ili terapijski potencijal ovih supstanci, koji je potrebno
dalje istražiti.Dementia represents one of the greatest medical and economic challenges today. Most common
causes of dementia are Alzheimer’s disease, characterized by Aβ and tau accumulation in the
brain, and vascular dementia, resulting from limited cerebral blood flow. Since available
therapies only alleviate dementia symptoms, with limited efficacy and notable side effects,
neuroprotective effects of dehydroepiandrosterone and its sulfate (DHEA(S)) and brain-derived
neurotrophic factor (BDNF) were investigated. Research utilized cellular (primary neuronal
culture from C57BL/6 mice and SH-SY5Y human neuroblastoma cell line, exposed to Aβ
oligomers or oxygen and glucose deprivation), animal (C57BL/6 mice injected with Aβ
oligomers and transgenic 3xTg-AD mice) dementia models, and blood samples from dementia
and control subjects. Findings revealed mild neuroprotective actions of DHEA(S) and BDNF
in cellular and animal models of dementia, and reduced DHEAS and elevated BDNF plasma
levels in dementia patients, suggesting their preventive and/or therapeutic potential, which
should be further investigated
Use of the computer software Tracker in the demonstration experiments in the physics education
No full textOvaj diplomski rad bavi se primjenom računalnog programa Tracker u nastavi i edukaciji fizike s ciljem poticanja aktivnog i istraživačkog učenja. Tracker je besplatan alat za videoanalizu gibanja koji omogućuje kvantitativnu obradu pokusa korištenjem stvarnih videozapisa. Korištenjem ovog programa moguće je vizualizirati i mjeriti različite vrste gibanja te ih povezati s teorijskim modelima. Rad ima za cilj pokazati kako Tracker može pomoći nastavnicima u objašnjavanju fizikalnih sadržaja i učenicima u njihovom boljem razumijevanju. Predstavljeno je pet eksperimentalnih primjera — od klasičnih tema poput trenja, sudara i njihala, do složenijih pokusa poput Torricellijevog teorema. Uključena je i analiza termoodskočnih kristala, koja povezuje suvremene materijale s osnovnim fizikalnim zakonima kroz modele kosog i vertikalnog hica. Kroz ove primjere pokazano je da Tracker može služiti kao svestran alat u nastavi, sposoban pratiti i jednostavne i složene fenomene. Program se može primjenjivati kako u osnovnim, tako i u srednjim školama, ovisno o kompleksnosti sadržaja i vještini učenika. Može se koristiti frontalno, kao demonstracija u učionici, ali i u sklopu istraživačkih laboratorijskih vježbi. Jedna od glavnih prednosti Trackera je što omogućuje izvođenje pokusa čak i u uvjetima ograničenog školskog budžeta, budući da se mogu koristiti postojeći videozapisi. Time se uklanja potreba za skupom opremom, a učenici i dalje imaju priliku raditi analize temeljene na stvarnim podacima. Analiza gibanja kroz video stvara most između apstraktne teorije i konkretne fizičke pojave. Osim toga, učenici razvijaju digitalne kompetencije, točnost u mjerenju i vještine znanstvene analize. Zaključno, Tracker predstavlja vrijedan doprinos suvremenoj nastavi fizike, promičući znanstveni pristup i razumijevanje kroz pristupačnu tehnologiju.This thesis explores the application of the Tracker computer program in physics education, with the aim of promoting active and inquiry-based learning. Tracker is a free video analysis tool that enables quantitative examination of physical experiments using real-world video recordings. By using this software, various types of motion can be visualized and measured, and then compared to theoretical models. The goal of this work is to demonstrate how Tracker can support teachers in explaining physics concepts and help students understand them more deeply. Five experimental examples are presented — from classical topics such as friction, collisions, and pendulums, to more complex experiments like Torricelli’s theorem. The thesis also includes an analysis of thermosalient crystals, connecting modern material phenomena with basic physics laws through models of projectile motion. These examples illustrate that Tracker is a versatile educational tool capable of handling both simple and advanced physical phenomena. The program can be used at both elementary and secondary school levels, depending on the complexity of the content and students’ abilities. It is suitable for classroom demonstrations as well as for inquiry-based laboratory activities. One of Tracker’s key advantages is its ability to facilitate experimental analysis even in schools with limited resources, since it can utilize pre-recorded videos. This eliminates the need for expensive experimental and measurement equipment while still providing meaningful, data-based learning experiences. Video motion analysis bridges the gap between abstract theory and observable reality. In addition, students develop digital literacy, measurement precision, and scientific reasoning skills. In conclusion, Tracker is a valuable contribution to modern physics education, promoting scientific thinking and conceptual understanding through accessible technology
Photonic crystals in rubidium atomic vapor
No full textFotonički kristali su optičke nanostrukture koje zbog prostornog periodičnog indeksa loma pronalaze primjenu u brojnim granama fizike. Fotonički kristali mogu se podijeliti prema translacijskoj (a)simetriji, a u ovom diplomskom radu proučavane su i kristalne i kvazikristalne (translacijski asimetrične) strukture. Optičke rešetke, kristalne i kvazikristalne strukture, generirane su interferencijom svjetlosti u parama alkalijskih metala, u našem slučaju atomske pare rubidija, koristeći prostorni modulator svjetlosti (SLM). Za razliku od široko korištenih mikrostrukturiranih fotoničkih kristala, ovom metodom omogućeno je podešavanje optičkih svojstava te time i kontroliranje ponašanja svjetlosti tijekom propagacije. Promjenom kuta između pumpnih laserskih zraka može se mijenjati veličina rešetke. Probna laserska zraka propagira se u optički induciranim rešetkama gdje je efekt diskretne difrakcije jasno uočljiv. Promjenom svojstava pumpnih zraka koje čine optičku rešetku, kao i probne zrake, uočene su pojave diskretne difrakcije svjetlosti i generacije solitona. Uočena je lokalizacija svjetlosti probnog lasera pri propagaciji u kvazikristalnoj optičkoj rešetci.Photonic crystals are optical nanostructures that, due to the spatial periodicity of the refractive index, find applications in numerous branches of physics. Photonic crystals can be subcategorized by their transitional (a)symmetry, and in this master's thesis both the crystalline and quasicrystalline (transitionally asymmetric) structures were studied. Both crystalline and quasicrystalline optical lattices were generated by light interference in alkali metal vapors, in our case rubidium atomic vapor, using a spatial light modulator (SLM). Unlike the widely used microstructured photonic crystals, this method enables adjustable optical properties, and therefore the behavior of light as it propagates through the medium can be controlled. The change in beam angles corresponded to a change in lattice period. A probe laser beam propagates through the optically induced lattices, where the effect of discrete diffraction is clearly observed. Varying the beam properties of the pump beams forming the optical lattice, as well as those of the probe beam, discrete light diffraction and soliton generation were observed. Localization of the probe laser beam was observed during its propagation in quasicrystalline optical lattice
Forced degradation study of nabumetone - β-cyclodextrin inclusion complex
No full textNesteroidni protuupalni predlijek nabumeton se u jetri metabolizira u svoj farmakološki akivan
oblik, 6-metoksi-2-naftiloctenu kiselinu, koja djeluje kao selektivan inhibitor izoenzima
ciklooksigenaza-2. Prema biofarmaceutskom sustavu klasifikacije djelatnih tvari, nabumeton
pripada drugoj skupini koju karakteriziraju slaba topljivost i visoka permeabilnost. Njegova se
topljivost može poboljšati nastajanjem inkluzijskog kompleksa s cikličkim oligosaharidima,
ciklodekstrinima. Provođenjem studija prisilne razgradnje dobivaju se informacije o stabilnosti
lijeka i njegovim razgradnim produktima koji utječu na njegovu učinkovitost i sigurnost. U
sklopu ovog diplomskog rada korišten je spregnuti sustav tekućinske kromatografije
ultravisoke djelotvornosti i spektrometrije masa visokog razlučivanja za analizu razgradnih
produkata nabumetona nastalih u kiselom, lužnatom, i oksidirajućem mediju, pri sobnoj ili
povišenoj temperaturi, uz ili bez prisutnosti β-ciklodekstrina. Strukture i sheme fragmentiranja
razgradnih produkata nabumetona pretpostavljene su na temelju rezultata analize tandemnom
spektrometrijom masa.Nonsteroidal anti-inflammatory prodrug nabumetone is metabolized in the liver into its
pharmacologically active metabolite, 6-methoxy-2-naphthylacetic acid, which acts as a
selective cyclooxygenase-2 inhibitor. According to the Biopharmaceutical Classification
System of drug substances, nabumetone is classified in the second group which is characterized
by low solubility and high permeability. Its solubility can be increased by the formation of
inclusion complexes with cyclic oligosaccharides cyclodextrins. Forced degradation studies
provide information about drug stability and its degradation products which affect its
effectiveness and safety. In this work, ultra performance liquid chromatography coupled with
high-resolution mass spectrometry was used for the analysis of nabumetone degradation
products formed in acidic, alkaline, and oxidizing media, at room or elevated temperature, with
or without the presence of β-cyclodextrin. Structures and fragmentation schemes of
nabumetone degradants were proposed according to the results of tandem mass spectrometry
analysis