University of Zagreb Repository
Not a member yet
127122 research outputs found
Sort by
Archaeology of identities in 5th and 6th centuries in late antique Dalmatia and southern Pannonia
No full textOva disertacija predstavlja istraživanje identiteta 5. i 6. stoljeća na prostoru nekadašnjih rimskih provincija (Savia, Sirmiensis, Dalmatia), odnosno istraživanje područja južne Panonije i Dalmacije, s osobitim naglaskom na teritorij Republike Hrvatske. Pitanja identiteta, u velikoj mjeri neistraženih stoljeća turbulentnog razdoblja velike seobe naroda tijekom navedena dva stoljeća, u arheologiji se najčešće baziraju na donošenju mišljenja i zaključaka o etničkim identitetima novodoseljenog stanovništva na teritorij spomenutih rimskih provincija. Disertacija donosi pogled na istraživanje identiteta uopće te se ne ograničava isključivo na etnički identitet već problem sagledava dubinski, prateći sociološke promjene pojedinaca i skupina unutar društva koje se suživotom novodoseljenog i starosjedilačkog stanovništva neminovno mijenja velikom brzinom. Razmatra se pitanje u kojoj mjeri predmeti arheološke materijalne kulture mogu nedvosmisleno svjedočiti identitetu nositelja materijalne kulture. Na taj način, disertacija predstavlja zanimljive društvene fenomene koji mijenjaju etnički, socijalni, ekonomski i gospodarski profil navedenog područja. Interdisciplinarnim pristupom znanstvenom istraživanju nerimskog stanovništva južne Panonije i Dalmacije, mogu se temeljitije promatrati navedeni fenomeni koji se u arheologiji mogu odražavati u materijalnoj kulturi koju je to stanovništvo tijekom 5. i 6. stoljeća ostavilo na obrađivanim područjima. Pojedine, već postojeće, interpretacije arheološkog materijala potrebno je preispitati te iscrpiti maksimum mogućih podataka koji predmet može pružiti s obzirom na navedene kategorije. Pristup istraživanju neminovno je interdisciplinaran te, uz arheologiju, pretpostavlja uključivanje drugih znanstvenih disciplina koje nadopunjuju arheološke zaključke. Posebno se razmatra odnos pisanih izvora naspram istraženih predmeta materijalne kulture, u smislu relevantnih informacija koje dobivamo s jedne i s druge strane da bi se izbjegla česta situacija u prošlosti kada su se pisana vrela uzimala kao činjenice. Detaljno proučavanje te predstavljanja većine istraženih i objavljenih predmeta materijalne kulture nerimskog stanovništva na jednom mjestu, olakšavaju rad istraživača koji će, u budućnosti, interesno zadirati u ovo razdoblje. Interpretacija nalaza kroz tekstualni i slikovni dio rekonstukcija, otvara ovu temu za daljnju raspravu o mogućnostima interpretacije identiteta nerimskog stanovništva južne Panonije i Dalmacije tijekom 5. i 6. stoljeća. Razdoblje navedena dva stoljeća označava turbulencije koje su se u to vrijeme događale na teritoriju Rimskog Carstva, a koje su značile korjenite promjene i temelj uspostave Europe kakvu poznajemo danas.This dissertation represents the research of the identity of the 5th and 6th centuries in the area of the former Roman provinces (Savia, Sirmiensis, Dalmatia), that is, the research of the area of southern Pannonia and Dalmatia, with a special emphasis on the territory of the Republic of Croatia. Questions of identity, largely unexplored during the turbulent period of the great migration of peoples during the aforementioned two centuries, in archeology are most often based on opinions and conclusions about the ethnic identities of the newly settled population in the territory of the mentioned Roman provinces. The dissertation brings a view of identity research in general and is not limited exclusively to ethnic identity, but the problem of looking in-depth, following the sociological changes of individuals and groups within society, which is inevitably changing at a high speed due to the coexistence of the newly settled and indigenous population. The question to what extent objects of archaeological material culture can unequivocally testify to the identity of the bearer of material culture is considered. In this way, the dissertation presents interesting social phenomena that change the ethnic, social, economic and economic profile of the mentioned area. With an interdisciplinary approach to the scientific research of the non-Roman population of southern Pannonia and Dalmatia, the aforementioned phenomena can be more thoroughly observed, which in archeology can be reflected in the material culture that this population left in the cultivated areas during the 5th and 6th centuries. Certain, already existing, interpretations of archaeological material need to be re-examined and the maximum amount of possible data that the subject can provide with regard to the above categories should be exhausted. The research approach is inevitably interdisciplinary and, along with archaeology, it assumes the inclusion of other scientific disciplines that complement the archaeological conclusions. Special consideration is given to the relationship between written sources and researched objects of material culture, in terms of the relevant information we receive from one side and the other. The detailed study and presentation of most of the researched and published objects of the material culture of the non-Roman population in one place facilitate the work of researchers who, in the future, will interestingly delve into this period. The interpretation of the findings through the textual and pictorial part of the reconstruction opens this topic for further discussion about the possibilities of interpreting the identity of the non-Roman population of southern Pannonia and Dalmatia during the 5th and 6th centuries. The period of the mentioned two centuries marks the turbulences that took place at that time in the territory of the Roman Empire, which meant radical changes and the foundation of the establishment of Europe as we know it today
Improvement of processes in the production of electronic components
No full textU ovom radu predstavljena je i analizirana proizvodnja elektroničkih pločica na proizvodnoj liniji u tvrtki Smart Sense d.o.o. Prije provedene analize razrađena je struktura ključnih pokazatelja uspješnosti te je naposlijetku odabrano nekoliko njih koji su kontinuirano mjereni. Nakon mjerenja analizirana je pojava zastoja, kako njihove vrste tako i učestalosti pojavljivanja, a zastoji su zatim podijeljeni u šest velikih gubitaka. Korištenjem alata Lean metodologije predložena su poboljšanja za eliminaciju ili skraćivanje zastoja te za potencijalno uklanjanje gubitaka. Neka od poboljšanja su i provedena, dok su neka ostala prisutna isključivo kao prijedlozi. Potom je ponovno provedeno mjerenje ključnih pokazatelja uspješnosti te su doneseni zaključci o uspješnosti provedenih poboljšanja. Naposlijetku je raspravljeno potencijalno uvođenje digitalnog sustava za praćenje ključnih pokazatelja uspješnosti kroz analizu jednog gotovog rješenja dostupnog na tržištu i kroz razmatranje mogućnosti razvoja vlastitog rješenja.This thesis presents and analyzes the production of electronic boards on te production line in the company Smart Sense d.o.o. Before the analysis was carried out, the structure of key performance indicators was elaborated, and finally several of them were selected and continuously measured. After the measurements, the occurence of jams and losses was analyzed with both their types and frequency of occurrence, and they were then divided into six big losses. Using Lean methodology tools, improvements were proposed to eliminate or shorten downtime and potentially to eliminate losses. Some of the improvements were eliminated, while some remained present only as suggestions. After that, the key performance indicators were measured again and conclusions were drawn on the success of the implemented improvements. Finally, the implementation of KPI dashboard was discussed through the analysis of a ready-made solution available on the market and through overview of the possibility of developing an in-house solution
Bridge carrier for a 140 t bridge crane
No full textU ovom radu prikazan je postupak dimenzioniranja i konstruiranja mosta granika nosivosti 140 tona za precizno rukovanje teretom, dodatno opremljenog s pomoćnim vitlom nosivosti 15 tona. Nakon uvodnog razmatranja postojećih mogućih konstrukcijskih rješenja, kreće se u detaljan proračun kutijastih nosača mosta te mehanizma za vožnju granika. Nakon proračuna slijedi konstrukcijska razrada mosta ganika uz mehanizam za vožnju.This paper presents the procedure which goes into dimensioning and design of a overhead crane bridge with a lifting capacity of 140 tons for precise handling, additionally equipped with an auxiliary hoist with a lifting capacity of 15 tons. An introductory review of already existing possible solutions is followed up by a detailed calculation of box girders an the travel mechanism of the crane. The calculations are followed by the design elaboration of the overhead crane bridge along with the travel mechanism
Computational aerodynamic model of buildings with porous double-skin façades
No full textSustav dvostrukog pročelja se koristi s ciljem poboljšanja energetske učinkovitosti zgrade. Sustav se sastoji od unutarnjeg pročelja na koje je smješteno vanjsko pročelje, pri čemu razmak između dvaju pročelja može iznositi od nekoliko centimetara do dva metra. Posebnu vrstu sustava dvostrukog pročelja predstavlja sustav dvostrukog poroznog pročelja kod kojeg se poroznost postiže otvorima na vanjskom pročelju. Pri strujanju vjetra oko zgrade s dvostrukim poroznim pročeljem dolazi do strujanja zraka kroz otvore na vanjskom pročelju i između dvaju pročelja. Takvo strujanje uzrokuje raspodjelu tlaka na zgradi koja nije karakteristična za zgrade s jednostrukim pročeljem.
U ovom radu je provedena računalna analiza atmosferskog strujanja zraka oko modela zgrade s dvostrukim poroznim pročeljem za slučaj visoke poroznosti vanjskog pročelja. Modeli zgrade i poroznog pročelja, te značajke modela atmosferskog graničnog sloja, su preuzeti iz laboratorijskih mjerenja u zračnom tunelu. Ispitana su dva pristupa računalnom modeliranju strujanja vjetra. Prvi pristup je utemeljen na zadavanju volumenskog protoka fluida na ulazu u računalnu domenu, dok se drugi pristup temeljio na izravnom modeliranju strujanja homogenog atmosferskog graničnog sloja. Računalni model je razvijen u programskom paketu OpenFOAM, a prostorna diskretizacija računalne domene je izrađena pomoću programskog paketa CF-MESH+. Postignuti rezultati su uspoređeni s rezultatima laboratorijskih mjerenja.Double-skin façade systems have been commonly used to improve the energy efficiency of buildings. This type of façade systems consists of an internal façade onto which an external façade is placed, with the gap between the two façades ranging from a few centimeters to two meters. A special type of a double-skin façade system is the porous double-skin façade, where porosity is achieved using openings on the external façade. When the wind flows around buildings with this type of façade, air flow occurs through the openings on the external façade and between the two façades. This type of flow yields pressure distribution on the building that is not characteristic of buildings with a single façade.
In this study, the computational analysis of atmospheric air flows around the building model equipped with a porous double-skin façade was conducted for the case of high porosity of the external façade. The appearance of the building model and the porous façade, as well as the characteristics of the atmospheric boundary layer model, were adopted from the wind-tunnel experiments. Two approaches to computational modeling of the wind flow were addressed. The first approach involved specifying the volumetric flow of the fluid at the inlet to the computational domain, while the second approach was based on the direct modeling of the homogeneous atmospheric boundary layer. The computational model was developed using the OpenFOAM software package, while the spatial discretization of the computational domain was performed using the CF-MESH+ software package. The obtained results were compared with the results of laboratory experiments
Učinci povišene temperature vode i onečišćujućih tvari na nekoliko bioloških obilježja ličinki tulara
No full textUrbanization and inadequate wastewater treatment contaminate freshwater ecosystems with
complex chemicals, which, along with climate change, threaten freshwater insects. To assess
these impacts, we conducted a 21-day microcosm experiment simulating a simplified
freshwater food web containing moss and larvae of two caddisfly species, Drusus croaticus
and Allogamus uncatus. The experiment included control (C), increased temperature (T2 = C +
4 °C), emerging contaminants mixture (EC), and multiple stressor treatment (MS = EC + T2).
We analysed caddisfly mortality, body weight, locomotor activity (distance moved), and
compared species-specific effect of selected stressors. ECs exposure increased average body
weight in both species with contrasting effects on locomotor activity, increasing larval average
distance moved in D. croaticus but reducing it in A. uncatus. T2 treatment caused the highest
mortality for D. croaticus larvae, while the mortality of A. uncatus larvae was similar in all
treatments. MS treatment significantly impacted D. croaticus larvae behaviour, leading to
reduced larval average distance moved compared to other treatments, highlighting the
complexity of multiple stressor interactions. The observed interspecies variability emphasizes
the importance of considering species-specific characteristics in ecological risk assessments.
These findings offer insights into how multiple stressors may impact caddisfly populations,
crucial members of aquatic ecosystems.Urbanizacija i neadekvatna obrada otpadnih voda onečišćuju slatkovodne ekosustave smjesama
onečišćivača, koji s klimatskim promjenama ugrožavaju slatkovodne kukce. U svrhu procjene
tih utjecaja, proveli smo 21-dnevni eksperiment stimulirajući pojednostavljenu slatkovodnu
hranidbenu mrežu s mahovinom i ličinkama dviju vrsta tulara, Drusus croaticus i Allogamus
uncatus. Eksperiment je uključivao kontrolnu skupinu (C), tretman s povišenom temperaturom
(T2 = C + 4 °C), smjesom onečišćivača (EC) te višestrukim stresorima (MS = EC + T2).
Analizirali smo smrtnost, srednju tjelesnu težinu, lokomotornu aktivnost (srednja prijeđena
udaljenost) tulara te usporedili učinak odabranih stresora specifično na svaku vrstu. Izloženost
smjesi onečišćivača povećala je prosječnu tjelesnu težinu u obje vrste, s kontrastnim učincima
na lokomotornu aktivnost, povećavajući prosječnu prijeđenu udaljenost ličinki D. croaticus te
je smanjujući za ličinke A. uncatus. Povišena temperatura (T2) uzrokovala je najveću smrtnost
ličinki D. croaticus, dok je smrtnost ličinki A. uncatus bila slična u svim tretmanima. Tretman
višestrukim stresorima značajno je utjecao na ponašanje ličinki D. croaticus, smanjujući
prosječnu prijeđenu udaljenost u usporedbi s kontrolnom skupinom i drugim tretmanima,
naglašavajući složenost interakcija višestrukih stresora. Uočena varijabilnost među vrstama
naglašava važnost razmatranja karakteristika specifičnih za pojedinu vrstu. Naša otkrića
pružaju uvid u utjecaj višestrukih stresora na populacije tulara, ključne članove vodenih
ekosustava
Development and validation of ultra-performance liquid chromatography method for the analysis of cinnarizine degradation products
No full textKemijska stabilnost aktivnih farmaceutskih sastojaka utječe na sigurnost i učinkovitost lijekova. U sklopu ovog diplomskog rada razvijena je, a zatim i validirana stabilitetno-indikativna metoda tekućinske kromatografije ultravisoke djelotvornosti uz detektor s diodnim nizom za praćenje kemijske stabilnosti cinarizina. Kako bi se razvila prikladna stabilitetno-indikativna analitička metoda najprije je provedena prisilna razgradnja na uzorcima cinarizina. Provedena je razgradnja pod utjecajem hidrolitičkih uvjeta (u neutralnom, kiselom i bazičnom mediju) pri temperaturi od 80 °C, razgradnja pod utjecajem oksidativnih uvjeta te fotolitička razgradnja cinarizina u otopini pri sobnoj temperaturi. Strukturna karakterizacija razgradnih produkata provedena je korištenjem spregnutog sustava tekućinska kromatografija ultravisoke djelotovornosti – spektrometrija masa visokog razlučivanja, uz eksperimente tandemne spektrometrije masa na ionima od interesa pri različitim vrijednostima kolizijskih potencijala.The chemical stability of active pharmaceutical ingredients affects the safety and effectiveness of drugs. As part of this thesis, a stability-indicative method of ultra-high efficiency liquid chromatography with a diode array detector for monitoring the chemical stability of cinnarizine was developed and then validated. To develop a suitable stability-indicative analytical method, forced degradation was performed on cinnarizine samples. Degradation under the influence of hydrolytic conditions (in neutral, acidic, and basic media) at a temperature of 80 °C, degradation under the influence of oxidative conditions and photolytic degradation of cinnarizine in solution at room temperature were carried out. Structural characterization of degradation products was carried out using a coupled system of ultra-high performance liquid chromatography – high resolution mass spectrometry, with tandem mass spectrometry experiments on ions of interest at different values of collision potentials
Inhibition of human cholinesterases by O-alkyloximes
No full textAcetilkolinesteraza (AChE) i butirilkolinesteraza (BChE) su enzimi koji kataliziraju hidrolizu acetilkolina i njihova inhibicija jedna je od glavnih strategija u liječenju Alzheimerove bolesti (AB). No, budući da je AB multifaktorijalna bolest, noviji pristup liječenju je razvoj lijekova s višestrukim učinkom koji bi istovremeno djelovali na više mogućih uzročnika bolesti. U sklopu ovog diplomskog rada testirano je 20 O-alkiloksima kao inhibitora ljudskih AChE i BChE, a za nekolicinu spojeva procijenjena je sposobnost vezanja u periferno mjesto AChE i sposobnost inhibicije β-amiloidne samoagregacije. Svi ispitani spojevi reverzibilno su inhibirali obje kolinesteraze u mikromolarnom području, s konstantama inhibicije Ki u rasponu 0,30 – 360 μmol dm–3. Najjačim inhibitorom AChE pokazao se spoj 20 (Ki = 6 μmol dm–3), dok je BChE najjače inhibirao spoj 15 (Ki = 0,30 μmol dm–3). Gotovo svi ispitivani O-alkiloksimi pokazali su se selektivnim inhibitorima BChE u odnosu na AChE. Sposobnost vezanja u periferno mjesto AChE i moguće sprječavanje nastajanja neurotoksičnog kompleksa AChE-β-amiloid pokazali su spojevi 2, 18, 19 i 20. Kao inhibitori β-amiloidne samoagregacije istaknuli su se spojevi 18 i 20. Za sve spojeve je in silico procijenjena sposobnost prolaska kroz krvno-moždanu barijeru te je pokazano da bi mogli prijeći krvno-moždanu barijeru pasivnim transportom.Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are enzymes that catalyze the hydrolysis of acetylcholine, and their inhibition is one of the main strategies in the treatment of Alzheimer's disease (AD). But, AD is a multifactorial disease so a new approach to treatment is development of multi-target directed ligands that would simultaneously act on several possible causes of the disease. As part of this thesis, 20 O-alkyloximes were tested as inhibitors of human AChE and BChE, and some of them were also tested for ability to bind to the peripheral site of AChE and to inhibit β-amyloid self-aggregation. All tested compounds reversibly inhibited both cholinesterases with inhibition constants Ki in the range of 0,30 – 360 μmol dm–3. The most potent AChE inhibitor was compound 20 (Ki = 6 μmol dm–3), while that of BChE was compound 15 (Ki = 0,30 μmol dm–3). Tested O-alkyloximes were generally more selective inhibitors of BChE than of AChE. Compounds 2, 18, 19 and 20 showed the ability to bind to the peripheral site of AChE and possible attenaution of formation of the neurotoxic AChE-β-amyloid complex. Compounds 18 and 20 proved to inhibit β-amyloid self-aggregation. All compounds were evaluated in silico for ability to pass the blood-brain barrier and all of them should be able to pass the blood-brain barrier by passive transport
Gamma-radiolytic degradation of nabumetone in water
No full textNabumeton je jedan od nesteroidnih lipofilnih protuupalnih lijekova. Farmakološko djelovanje ostvaruje putem metabolita 6-metoksi-2-naftiloctene kiseline, koji je inhibitor enzima ciklooksigenaze. Međudjelovanjem ionizirajućeg zračenja i tvari nastaju reaktivne kratkoživuće čestice, oksidirajuće i reducirajuće vrste, koje neselektivnim reakcijama reagiraju s farmaceuticima te ih mogu prevesti u za okoliš neškodljive produkte. U sklopu ovog diplomskog rada, za kvantitativno određivanje nabumetona korištena je tekućinska kromatografija visoke djelotvornosti i UV/Vis spektrofotometrija. Djelotvornost razgradnje praćena je u vodenim otopinama pri različitim koncentracijama nabumetona, različitim dozama zračenja te različitim vrijednostima pH. Također, praćen je i utjecaj različitih "hvatača" radikala, anorganskih iona te otapala. Spregnuti sustav tekućinske kromatografije ultravisoke djelotvornosti i spektrometrije masa visokog razlučivanja korišten je za analizu razgradnih produkata nabumetona. Na temelju rezultata analize tandemnom spektrometrijom masa, pretpostavljene su strukture i sheme fragmentacije razgradnih produkata nabumetona.Nabumetone is one of the non-steroidal anti-inflammatory drugs, characterized by its non-acidic and lipophilic properties. Its pharmacological effects are achieved through the metabolite 6-methoxy-2-naphthylacetic acid, which is an inhibitor of the cyclooxygenase enzyme. Interaction of ionizing radiation and the substance results in the formation of reactive short- lived particles, oxidizing and reducing species, which, through non-selective reactions, react with pharmaceuticals and can transform them into environmentally benign products. In this work, high performance liquid chromatography and UV/Vis spectrophotometry were used for the quantification of nabumetone. The degradation efficiency was monitored in aqueous solutions at different initial concentrations of nabumetone, different radiation doses, and different pH values. Additionally, the impact of various radical scavengers, inorganic ions, and solvents was observed. A coupled system of ultra-high-performance liquid chromatography and high-resolution mass spectrometry was used for the analysis of nabumetone degradation products. Based on the results of tandem mass spectrometry analysis, structures and fragmentation schemes of nabumetone degradants were proposed
Evolution of rhythmic topography of the Lopata beach (Island of Dugi otok)
No full textU ovom radu analiziran je mehanizam nastanka ritmične topografije na žalu Lopata (Dugi otok). Ritmičnu topogafiju čine mnogobrojne pravilno razmaknute grupacije sedimenta sličnih oblika. Za vrijeme terenskog rada u rujnu 2023. godine fotografiran je sediment duž žala unutar kojeg je uočen detritus vrste Posidonia oceanica. S pomoću fotografija sedimenta izračunata je veličina zrna u programu ImageJ i definirana njegova zaobljenost. Prikupljeni su podaci o brzini jugoistočnog vjetra te s pomoću njih izračunata visina i period vala u moru ograničenog privjetrišta i ograničenog trajanja puhanja vjetra. Žalo Lopata fotografirano je dronom u razdoblju od studenog 2020. do travnja 2021. godine. Fotografije su obrađene metodom digitalne fotogrametrije u programu AgiSoft Metashape te su potom od novonastalih digitalnih elevacijskih modela izrađene konturne i razlikovne karte modela u programu Surfer. Ritmična topografija na žalu Lopata postojana je na dvije razine; na nižoj razini su oblici manjih dimenzija i sitnijeg sedimenta, a na višoj razini su oblici većih dimenzija i krupnijeg sedimenta. Jugoistočan vjetar uvjetuje visinu valova koja je bitna za stvaranje oblika ritmične topografije, a mehanizam nastanka može se povezati s refrakcijom valova koji dolaze na žalo Lopata.This thesis analyses the mechanism of rhythmic topography genesis on beach Lopata (island Dugi otok). Rhythmic topography consists of many evenly distributed sediment groups of similar shapes. The sediment on the beach was photographed in September of 2023. Detritus of Posidonia oceanica was recorded among the sediment. Sediment particle roundness was evaluated and size calculated using program ImageJ. Wave height and period were calculated using the speed of southeastern wind. The beach Lopata was also photographed with a drone from November of 2020 to April of 2021. These photos were edited using digital photogrammetry program AgiSoft Metashape and Surfer. Rhythmic topography of beach Lopata is recorded in two levels; lower altitude level consists of smaller and more frequent rhythmic pattern and finer sediment; higher altitude level consists of bigger and wider rhythmic pattern and sediment particles of larger size. Rhythmic topography of beach Lopata appears due to the refraction of waves which are created by the southeastern wind during storms