Mjerenje udarnog presjeka za zajedničku tvorbu Higgsovog bozona i elektroslabog bozona u konačnim stanjima s dva b kvarka i dva leptona u proton proton sudarima na Velikom hadronskom sudarivaču

This thesis summarizes the analysis in which we measure the cross-section for the production of the standard model Higss boson of 125 GeV in association with an electroweak boson (W or Z). The analysis is performed in the final state where the Higgs boson decays into a pair of b quarks and the electroweak boson decays leptonically resulting in three channels based on the number of charged leptons in the final state (0, 1 or 2 leptons). The analysis uses data recorded by the CMS experiment from proton-proton collisions at √s= 13 TeV in the LHC during the full Run 2 data taking period (2016-2018). The recorded data corresponds to an integrated luminosity of 138 fb−1. The analysis searches for 2 b-jets produced from b-quarks originating from the Higgs boson along with lepton candidates decaying from the vector boson. The mass of the Higgs boson is reconstructed from the four momenta of the b-jets which are identified using b-tagging algorithms. To account for events with a Lorentz boosted Higgs boson, a single large cone jet is reconstructed which consists of the two b-jets merged together due to the boost. Taking this into account, separate analysis called the boosted analysis is performed along with the nominal resolved analysis to improve sensitivity in high pT phase space. Both resolved and boosted analysis are combined together in the final fit to enhance precision of the measurement. To reduce the dependency on theoretical uncertainties this measurement is performed in the simplified template cross-section (STXS) scheme. This also allows for straightforward comparison of theoretical models using such measurements. Under this scheme, the cross section measurement is done in regions delineated by type of vector boson (W or Z), vector boson transverse momentum (pT ), and the presence of additional jets.Budući da se udarni presjeci mjere u shemi STXS, konačni skup događaja u kanalu i u svakoj regiji (signal ili kontrola) dalje se dijele prema shemi predloška STXS. Prilagodba maksimalne vjerodostojnosti izvodi se istovremeno u signalnim i kontrolnim područjima za svako STXS područje kako bi se dobio modifikator jačine signala (μ) koji označava omjer promatranog broja VHbb događaja u odnosu na onaj koji se očekuje u SM-u. μ=1 predstavlja udarni presjek u skladu s SM-om

Visokoenergijsko gama-zračenje pulsara i maglica pulsarovog vjetra opažanih teleskopima MAGIC

A pulsar wind nebula (PWN) is a system with a central rotating object, a pulsar, which powers a surrounding nebula. This complex system is observed to emit radiation throughout the electromagnetic spectrum, from radio to gamma rays. In this thesis I explored the gamma-ray emission from pulsars, their respective nebulae and one PWN candidate at very high energies (VHE, E > 100 GeV) using the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes. At the beginning of this research, only one pulsar, the Crab pulsar, was known to emit at VHE, challenging the theoretical models. The observed electromagnetic radiation from the pulsar-nebula system implies the presence of a mechanism that accelerates charged particles to ultra-relativistic energies. However, this mechanism is poorly understood, thus VHE pulsar observations are relevant not only as information for emission modelling but also as a contribution for better characterization of fundamental properties of these complex astrophysical systems. The MAGIC telescopes, with its novel trigger especially developed for pulsar obser- vation, is the most suitable instrument to search for new VHE pulsars. In this thesis, I present the observations and analysis of two galactic sources: Crab (PSR J0534+2200) and Dragonfly (PSR J2021+3651) pulsars. For the well-known and previously detected Crab pulsar, the anal- ysis shows the expected results and is used as a performance check of the method. The same method is then used to search for VHE emission from the Dragonfly pulsar, proposed as a very likely VHE pulsar candidate due to its similar characteristics to the Crab pulsar. I found no significant pulsed emission from Dragonfly pulsar in low Eγ-range (50 GeV 200 GeV), only upper limits were derived. However, with the same set of data, the Dragonfly nebula surrounding the pulsar was detected. I also present the study of the unidentified TeV source, HESS J1858+020, that was put forward as a relic PWN candidate using the archival data collected from the MAGIC telescopes where this source was relatively far from the centre of the camera implying a decrease in detection sensitivity. Nevertheless, the source was detected, source extension estimated and the spectrum between 300 GeV and 10 TeV was constrained, but morphological or other details were not discerned. Neither the PWN scenario could be refuted nor confirmed. Overall, detailed studies of the VHE gamma-ray emission from pulsars and nebulae seem more challenging than expected, and longer observations are needed for pulsed detection or for morphological characterization of nebulae. The next-generation Cherenkov telescope array (CTA) with an order of magnitude better sensitivity and with 1 arcminute resolution, will certainly allow detailed morphological and spectral studies of this kind of source. Furthermore, I also studied a faint component of the Galactic diffuse synchrotron emission at low-radio frequencies by using multiple polarimetric observations with the LOw Frequency ARray (LOFAR). Before stacking them, these observations first needed to be corrected for the Faraday rotation in the Earth’s ionosphere, otherwise, the observed polarized emission may be either partially or in exceptional cases fully depolarized. I used the observed polarized diffuse synchrotron emission to characterize and additionally correct for the ionospheric Faraday rotation. After stacking twenty observations, the noise was reduced by ∼ √20, as expected. A higher signal-to-noise ratio achieved with this method enables a study of the faint component of the Galactic diffuse emission, which was not visible in a single reference observation. Moreover, the applied technique can also be used for studies of faint polarized sources, including pulsars.Glavna tema ovog rada je proučavanje visokoenergijskog gama-zračenja iz pulsara i maglica pulsarovog vjetra opažanih teleskopima MAGIC (engl. Major Atmospheric Gamma Imaging Cherenkov). Gama-astronomija proučava procese u svemiru koji se odvijaju u uvjetima ekstremno velikih energija i gustoća. Podrijetlo kozmičkog gama-zračenja vrlo visokih energija (100 GeV < E < 100 TeV) su netermički procesi koji nose informaciju o galaktičkim i izvangalaktičkim izvorima. Galaktički izvori su ostaci supernova (engl. supernova remnants), pulsari, maglice pulsarovog vjetra (engl. pulsar wind nebulae), dvojni gama-sustavi (engl. binary systems) te magnetari, dok su izvangalaktički izvori npr. aktivne galaktičke jezgre, provale gama-zračenja (engl. gamma ray burst, GRB) i tamna tvar - koja je potencijalno i galaktički izvor. U prošlom desetljeću, opažanjima opservatorija na energijama u području TeV (MAGIC, VERITAS, HESS, Milagro) otkriven je velik broj izvora u galaktičkoj ravnini, među kojima su maglice pulsarovog vjetra dominantna populacij

Interakcije onkoproteina E6 HPV-a s vezujućim partnerima: utjecaj na stabilnost i stanične funkcije E6

Human papillomaviruses (HPVs) are a group of small DNA viruses that cause various human malignancies, with cervical cancer being the most significant disease associated with a persistent HPV infection. Only a small number of HPV types has been shown to be responsible for these malignancies. These HPVs are referred as high-risk (HR) types, with HPV-16 and -18 being the most prominent ones. Two major viral oncoproteins, E6 and E7, directly contribute to the development of cancers by interfering with various cellular signaling pathways. A number of HPV-16 variants has been identified in different geographical locations, with some variants exhibiting higher oncogenic potential than others. The first part of thesis focuses on the analysis of the HPV-16 E6 D25N L83V variant, which was shown to be strongly associated with the development of cervical cancer. It was shown that this variant exhibits an increased capacity for interacting with E6AP ubiquitin ligase and consequently degraded it more efficiently, in comparison to the other analyzed mutants HPV-16 E6 D25N and E6 L83V. The HPV-16 E6 mutants' abilities to degrade key cellular target proteins, including the p53 tumor suppressor and PDZ-domain containing substrates, were investigated through in vitro and overexpression degradation assays. The analyses revealed no significant differences in the degradatory activities among the evaluated E6 mutant oncoproteins. Furthermore, the second part of this thesis demonstrates that multiple α-E6 oncoproteins can bind to MAML1 via LXXLL motif, resulting in an increased α-E6 protein stability. β-E6 oncoprotein stability was also shown to be dependent on the interaction with MAML1, whilst the absence of MAML1 led to both HPV-8 E6 and HPV-18 E6 oncoprotein rapid turnover at the proteasome. The study proposed a model by which most of β-E6s interact exclusively with MAML1, whereas it appears that two cellular pools of HR α-E6 are present, one forms a complex with MAML1, while the other one interacts with E6AP. Although HR α-E6/MAML1 complex does not affect the targeting of cellular substrates such as p53 and DLG1, co-expression of MAML1 and E6AP with HR α-E6 modulates MAML1's normal cellular activities leading to a significant increase in cellular proliferation. Silencing MAML1 decreases wound closure in HeLa cells, suggesting its role in the regulation of cellular migration in HPV-positive cells and maintenance of the transformed phenotype. Overall, this doctoral thesis provides novel insights into the functions of both α- and β-E6 oncoproteins and their roles in HPV-induced pathogenesis.Humani papilomavirusi (HPVs) pripadaju skupini malih DNA virusa koji uzrokuju različita maligna oboljenja, pri čemu je rak vrata maternice najznačajnija bolest povezana sa dugotrajnom HPV infekcijom. Samo mali broj HPV tipova uzrokuje zloćudne bolesti. Spomenuti tipovi nazivaju se visokorizičnim (HR), među kojima su HPV-16 i HPV-18 najistaknutiji. Dva glavna virusna onkoproteina E6 i E7 svojim djelovanjem izravno pridonose razvoju raka djelujući na različite stanične signalne puteve. Postoje mnoge varijante HPV-16 zastupljene na različitim geografskim lokacijama te se pokazalo da neke od varijanti imaju veći onkogeni potencijal. Prvi dio doktorske disertacije usmjeren je na analizu HPV-16 E6 D25N L83V varijante koja je usko povezana s nastankom raka vrata maternice. Utvrđeno je da varijanta D25N L83V ostvaruje povećanu interakciju sa ubikvitinskom ligazom E6AP te je posljedično najučinkovitija u poticanju njezine razgradnje u usporedbi sa ostalim ispitanim mutantima HPV-16 E6 D25N i E6 L83V. Svojstva mutanata da izazovu razgradnju ključnih staničnih ciljnih proteina, uključujući tumor-supresor p53 i stanične proteine koji sadrže PDZ-domene ispitana su in vitro esejima razgradnje i esejima razgradnje provedenim korištenjem kulture stanica. Međutim, nisu otkrivene značajne razlike u aktivnostima razgradnje među ispitivanim HPV-16 E6 mutantima. Drugi dio doktorske disertacije otkriva da se različiti α-E6 onkoproteini vežu za MAML1 putem LXXLL strukturalnog motiva, što rezultira povećanom stabilnošću onkoproteina E6. Nadalje, stabilnost onkoproteina β-E6 također ovisi o interakciji s MAML1, dok utišavanjem MAML1 dolazi do brže proteasomske razgradnje onkoproteina HPV-8 E6 i HPV-18 E6 u HPV-pozitivnim stanicama. Studija predlaže molekularni model prema kojemu većina onkoproteina β-E6 stupa u interakciju isključivo s MAML1, dok su prisutna dva stanična skupa HR α-E6, od kojih jedan tvori kompleks s MAML1, a drugi stupa u interakciji s E6AP. Iako kompleks HR α-E6/MAML1 nema ulogu u razgradnji važnih staničnih ciljnih proteina kao što su p53 i DLG1, zajednička ekspresija MAML1 i E6AP sa HR α-E6 mijenja uobičajene stanične aktivnosti MAML1 dovodeći do značajnog povećanja stanične proliferacije. Dodatno, utišavanje MAML1 smanjuje „proces cijeljenja rane“ u HeLa stanicama ukazujući na njegovu ulogu u regulaciji stanične migracije HPV-pozitivnih stanica i održavanju transformiranog fenotipa. Sveobuhvatno, doktorska disertacija donosi nove uvide o funkcijama onkoproteina α- i β-E6 i njihovoj ulozi u patogenezi izazvanoj HPV infekcijom

Elucidating the role of a protease BACE1 in the pathogenesis of a rare neurodegenerative disorder Niemann-Pick type C

Bolest Niemann-Pick tipa C (NPC) je rijetka nasljedna neurodegenerativna bolest nakupljanja slobodnog kolesterola i drugih lipida uzrokovana mutacijama u genu NPC1 ili NPC2, koja pokazuje niz patoloških sličnosti s kompleksnom Alzheimerovom bolesti (AB). Naša prethodna istraživanja su utvrdila povišeno djelovanje ključnog enzima u AB, proteaze BACE1, u NPC modelima. Stoga je cilj ovog doktorskog rada bio istražiti molekularnu pozadinu uočenog efekta te ispitati učinak inhibicije BACE1 na patološke karakteristike bolesti. Također, cilj je bio analizirati lipidom kako bi se utvrdile najranije promjene lipida odgovorne za različitu vulnerabilnost moždanih regija i disfunkciju endosoma u NPC bolesti. Korištene su primarne kulture neurona, kulture organotipskih rezova mozgova te moždane regije hipokampusa i malog mozga miševa koji imaju spontanu mutaciju u genu NPC1 tei ne sintetiziraju proteina NPC1 (miševi NPC1) i miševa divljeg tipa (wt, od engl. wild type). U neuronima miševa NPC1 u odnosu na wt detektirana je povećana proteoliza supstrata BACE1- Sez6L i Sez6. Imunocitokemijska analiza je pokazala nakupljanje ovih supstrata u ranim endosomima NPC1 neurona. Promijenjen smještaj Sez6 i Sez6L u ranim endosomima je potvrđen i frakcioniranjem endolizosoma u moždanim regijama hipokampusa i malog mozga miševa NPC1. Interesantno, tretman inhibitorom BACE1 je djelomično popravio patološke značajke bolesti NPC, uključujući smanjenje nakupljanja Sez6 i Sez6L, smanjenje veličine vezikula ranih endosoma te smanjenje ukupne razine proteina tau u neuronima NPC1, kao i smanjenje neuroinflamacije (aktivacije astrocita i mikroglija) u kortiko-hipokamplanim rezovima miševa NPC1. Nadalje, analiza lipidoma je utvrdila da već u asimptomatskoj fazi bolesti postoji značajna razlika u distribuciji i razini određenih lipida u malom mozgu i hipokampusu, te u ranim endosomima miševa NPC1 u odnosu na wt. Ovo istraživanje je utvrdilo disfunkciju proteaze BACE1 i njenih supstrata te njihovu potencijalnu ulogu u patogenezi bolesti NPC. Uočene promjene sastava lipida moždanih regija i ranih endosoma mogu doprinijeti razvoju patoloških promjena u bolesti NPC.Niemann-Pick disease type C (NPC) is a rare hereditary neurodegenerative disorder, caused by mutations in the NPC1 or NPC2 gene. It is characterised by accumulation of free cholesterol and other lipids and has a number of pathological similarities with complex Alzheimer's disease (AD). In our previous studies, increased activity of BACE1, the key enzyme of AD, was found in NPC mouse models. Therefore, the aim of this dissertation was to explore the molecular background of the observed effect and examine the effect of BACE1 inhibition on the pathological characteristics of the disease. In addition, the goal was to determine the earliest lipid changes responsible for the differences in brain region vulnerability and endosomal dysfunction in NPC disease by lipidome analysis. Primary neuronal cell cultures, organotipic brain slice cultures, and hippocampus and cerebellum of mice that have a spontaneous mutation in NPC1 gene and do not synthesize the NPC1 protein (NPC1 mice) and wild type mice (wt) were used. NPC1 neurons showed increased proteolysis of BACE1 substrates- Sez6L and Sez6 compared with wt neurons. Immunocytochemical analysis demonstrated accumulation of the aforementioned substrates in early endosomes of NPC1 neurons. The altered localization of Sez6 and Sez6L in early endosomes was confirmed by endolysosome fractionation in the hippocampus and cerebellum of NPC1 mice. Interestingly, treatment with a BACE1 inhibitor partially ameliorated the pathological features of NPC disease, including reduction in the accumulation of Sez6 and Sez6L, reduction in the size of early endosome vesicles, reduction in total tau protein level in NPC1 neurons, and reduction in neuroinflammation (activation of astrocytes and microglia) in cortico-hippocampal brain slices from NPC1 mice. Lipidome analysis revealed that even in the asymptomatic phase of the disease, there are significant differences in the distribution and content of certain lipids between NPC1 and wt mice in the cerebellum and hippocampus, and in early endosomes. These studies provide evidence for a possible role of the BACE1 protease and its substrates in the pathogenesis of NPC disease. The observed changes in the lipid composition of brain regions and early endosomes may contribute to the development of the pathological features of NPC disease

Diferencijalna ekspresija gena i evolucijska obilježja morfotipova bakterije Borrelia burgdorferi

In laboratory conditions, Borrelia burgdorferi, the causative agent of Lyme disease, exists as a spirochete, round body, bleb, or biofilm culture. This doctoral thesis suggests that spirochete to round body transition relies on the delicate regulation of a relatively small number of evolutionary conserved genes. In contrast, spirochete to bleb and biofilm transition includes significant reshaping of transcription profiles towards evolutionary young genes.Borrelia burgdorferi u laboratorijskim uvjetima može poprimiti oblik spiroheta, okruglih tjelešaca, mjehurastih formi ili biofilma. Rezultati proizašli iz ovog istraživanja upućuju na to da je tranzicija iz spiroheta u okrugla tjelešca regulirana malim brojem evolucijski konzerviranih gena, dok je prijelaz iz spiroheta u mjehuraste forme ili biofilm popraćen velikim ekspresijskim promjenama koje uključuju pojačanu ekspresiju evolucijski mlađih gena

Characterization and evolution of centromere in nematodes of the genus Meloidogyne

Centromeres are chromosomal regions responsible for the faithful segregation of chromosomes. In contrast to conserved function, the centromere protein (CenH3) and associated repetitive DNA evolve rapidly. However, our study revealed preservation of the αCenH3 variant along with conserved 19-bp box sequence in rapidly evolved centromeric DNA in asexual Meloidoygne nematodes. A similar approach was applied to the beetle Tribolium castaneum and showed a metapolycentric centromere organization with extended centromere regions. Long-range Nanopore sequencing is optimized for further study of centromeric arrays in the genomes of Meloidogyne and Tribolium species

Unutarstanični smještaj, struktura i funkcija proteina NME6 u čovjeka

Nucleoside diphosphate kinase (NDPK/NME/NM23) family of enzymes catalyze the transfer of gamma phosphate group from nucleoside triphosphates to nucleoside diphosphates. The family sparked interest after the discovery of metastasis suppressor activity of NME1, leading to a comprehensive characterization of Group I members (NME1-NME4). In contrast, the evolutionary ancient Group II members (NME5-NME9) are to date barely explored. We aimed to produce an extensive description of the human NME6 protein, by revealing its expression pattern, enzymatic activity, subcellular localization, quaternary structure and cellular function. Our results show the ubiquitous expression of NME6. We demonstrated a lack of enzymatic activity linked to oligomerization deficiency. We confirmed the mitochondrial localization and refined it to a matrix-facing protein, partially bound to the mitochondrial inner membrane, where NME6 interacts with RCC1L protein. Finally, we unraveled a negative impact of NME6 on mitochondrial respiration, possibly linked to the regulation of mitochondria-encoded protein expression.Nukleozid difosfatske kinaze, (NDPK/NME/NM23), kataliziraju prijenos gama fosfata s nukleozid trifosfata na nukleozid difosfate. Ova obitelj enzima privukla je veliku pozornost nakon otkrića da je jedan od njenih članova, NME1, uključen u sprječavanje nastanka metastaza. To je dovelo do sveobuhvatnih istraživanja članova NME iz skupine I (od NME1 do NME4). Nasuprot tome, evolucijski „stariji“ članovi Grupe II (od NME5 do NME9) do danas su vrlo malo istraženi. Cilj ovog rada bio je detaljnije istražiti ljudski protein NME6, utvrditi njegovu ekspresiju, enzimsku aktivnosti, unutarstanični smještaj, kvarternu strukturu i stanične funkcije. Naši rezultati pokazuju sveprisutnu ekspresiju proteina NME6. Pokazali smo da NME6 ne stvara oligomere te da, u vezi s time, ne pokazuje ni enzimatsku aktivnost. Pokazali smo da je protein smješten u matriksu mitohondrija, vjerojatno djelomično vezan na unutarnju membranu, gdje stupa u interakciju s proteinom RCC1L. Konačno, otkrili smo negativan utjecaj pojačane ekspresije NME6 na stanično disanje, što je vjerojatno povezano s regulacijom ekspresije proteina kodiranih mitohondrijskom DNA

Mixed quantum-classical approach to the calculation and assignment of the time- resolved photoelectron spectra

Vremenski razlučena fotoelektronska spektroskopija (TRPES) jedna je od najprikladnijih pobudno-testnih tehnika za praćenje spregnute nuklearne i elektronske dinamike. Med̄utim, kako bi se molekulska dinamika mogla "vidjeti" u spektru, potrebne su teorijske simulacije i asignacije spektara. U ovom je radu klasični formalizam ulazno-izlaznog probira primjenjen na TRPES tehinku. Osmišljena je i implementirana pragmatična metodologija izvrednjavanja izraza, koja se temelji na multireferentnom opisu vezanih elektronskih stanja, miješanoj kvantno-klasičnoj simulaciji neadijabatske dinamike te opisu fotoionizacijskog kontinuuma unutar teorije funkcionala gustoće sa statičkom izmjenom. Uz to, osmišljen je i implementiran jednostavan algoritam za asignaciju TRPES spektra u terminima elektronskih karaktera, temeljen na dijabatizaciji vezanih elektronskih stanja. Ukupna metodologija je primjenjena na dva prototipna fotoinducirana procesa, internu konverziju u pirazinu te otvaranje prstena u cikloheksa-1,3-dienu. Nova saznanja o mehanizmima proučavanih procesa su prezentirana i raspravljena. Dodatno, simulacijama neadijabatske dinamike proučeni su i mehanizmi eliminacije dušika iz diazometana prilikom pobude u prvo i drugo pobud̄eno stanje.Time-resolved photoelectron spectroscopy (TRPES) has proven to be one of the most convenient pump-probe techniques for monitoring the coupled nuclear and electronic dynamics. However, in order to "see" the molecular dynamics in the spectrum, the theoretical simulations and assignment of the spectra are needed. In this work, the classical doorway-window formalism has been applied to the TRPES technique. A pragmatic methodology of evaluation of the expression has been designed and implemented. It consists of multireference treatment of bound electronic states, a mixed quantum-classical simulation of nonadiabatic dynamics and static-exchange DFT treatment of the photoionization continuum. Also, a simple procedure of TRPES assignment in the terms of electronic characters, based on the diabatization of the bound electronic states, has been designed and implemented. The methodology as a whole has been applied on two prototype photoinduced processes: internal conversion in pyrazine and the ring-opening reaction in cyclohexa-1,3-diene. New insights in the mechanisms of the studied processes are presented and discussed. In addition, the mechanisms of nitrogen elimination from diazomethane during excitation to the first and second excited state were studied by simulations of nonadiabatic dynamics

Influence of radiation and high temperatures on electronic properties of diamond detectors

Due to its ultra-wide bandgap, diamond is a material that offers a unique combination of excellent electrical, mechanical and thermal properties. Contrary to silicon, the operation of diamond-based radiation detectors should thus be possible under specific harsh conditions. In this work, hardness against temperature and radiation damage was investigated with two custom-designed thermally resilient diamond detectors. High purity single crystal diamond samples were used, with tungsten electrodes deposited on the opposing crystal faces. The operation of diamond as a radiation detector was investigated by exposure to fast ions in the MeV energy range, focused on a micrometer spot with the ion microprobe setup. By changing the ion energy and mass, the penetration depth or ionization density can be modified. These capabilities provide information about the interaction volume between the radiation particles and the device, which was exploited in two experimental scenarios: to probe the electronic properties by inducing ionization in the detector (probing ions), or to deposit the radiation damage by exposure to a higher ion dose (damaging ions). The analysis of the induced signal gives us the possibility to extract important parameters related to both the macroscopic detector performance, and the fundamental semiconductor properties of the diamond material used. Charge transport at elevated temperatures was characterized by measuring charge collection efficiency, mobility-lifetime product and drift time of electrons and holes, using both charge- and current-sensitive pulse-processing electronics. Testing the detector for nuclear spectroscopy operation revealed a highest operating temperature of 720 K, at which the energy resolution and collection efficiency of the detector remained virtually unaffected by thermal effects. It was also found that the radiation hardness, after deposition of the radiation damage with 5 MeV protons, deteriorates with elevating temperature. However, the decrease is stopped at temperatures above 660 K, which can be attributed to the beneficial mechanism of thermally induced detrapping of charge carriers. Analysis of the time evolution of the transient charge signal in the detector provided a framework to extract the energy levels of the responsible deep traps. These results are particularly important for the development and new applications of diamond radiation detectors in high-temperature and high-radiation conditions. Finally, an additional investigation was performed to understand the influence of the space-charge-limited regime on the charge carrier dynamics. It was demonstrated that exposure to elevated temperatures led to depolarization of the detector, whereupon the adverse effects on the charge transport were mitigated and collection efficiency was restored

Multimethodological study of trace metal speciation and organic matter in estuarine waters

This work introduces methodological novelties in the field of trace metal speciation and organic matter in natural waters: (i) advancement of competitive ligand exchange - adsorptive cathodic stripping voltammetry; a new modes of multi detection window approach, (ii) revised application of copper (Cu) ion-selective electrodes in high chloride media i.e., seawater and (iii) a novel voltammetric method for quantification of humic substances. The second chapter of the thesis is dedicated to field studies in the Krka River estuary: (i) the dynamics and seasonality of dissolved organic matter (DOM) in the estuary and (ii) organic Cu speciation in the estuarine salinity gradient, (iii) the dynamics of various trace elements (Cu, Zn, Pb, Cd, Ni, Co, Cr, Fe, Mn, Al, As, V, U) and DOM in the estuarine surface microlayer (SML) and (iv) the size partitioning of different trace metals (Cu, Zn, Pb, Cd, Ni, Co, Fe, Mn and Al) in the salinity gradient. In winter, the estuarine waters contained a strong terrestrial signature, whereas in summer in situ production dominated the DOM pool. The high stratification combined with a decoupling between production and removal processes resulted in DOM accumulation above the halocline. In the bottom layer, DOM was released and quickly removed when oxygen was available, whereas in hypoxic waters the production of dissolved organic carbon and chromophoric DOM was linearly related to oxygen consumption. The Cu speciation study identified two ligand classes: L1 (12.5 < logK’CuL1 < 14.3) was mainly derived from recent phytoplankton production and L2 (10.6 < logK’CuL2 < 11.1) was characterised as predominantly humic substances of both terrestrial and autochthonous origin. Seasonal anthropogenic Cu input was successfully buffered by the ambient ligand pool due to the increased ligand concentrations in summer attributable to increased in situ production. The extensive SML samplings gave insights in diel variations of total and dissolved concentrations of trace elements in the SML, which were influenced by various factors: wind speed and wind direction, suspended particulate matter (primarily Fe, Al, Mn and Pb), complexation with organic ligands and bubble scavenging (primarily Fe, Cu and Pb) and bacterioneuston activity. The truly dissolved fraction (< 3 kDa) dominated the size speciation of Ni, Cd, Zn, Co and Cu, while Fe, Al, Pb and Mn were mainly present in particles larger than 5 μm. Of the studied metals, Pb, Al, Fe and Cu showed the highest affinity for colloids (3 kDa – 0.1 μm), which accounted for 30 – 37% of their dissolved pool (< 0.1 μm)