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Morphological characters of the Romanogobio fish genus in the Croatian Danube River basin
No full textPrema sadašnjim spoznajama na području Republike Hrvatske obitavaju četiri vrste iz roda
Romanogobio, od kojih se 3 nalaze u dunavskom slijevu Hrvatske. Jedinke iz ovog istraživanja
determinirane su kao vrste Romanogobio kesslerii i Romanogobio vladykovi. Cilj je ovog
istraživanja bio odrediti njihove morfološke karakteristike te provjeriti postoje li razlike unutar
populacije i između populacija. Istraživanje je obuhvatilo 19 lokaliteta iz sedam rijeka. Kako bi se
utvrdile raznolikosti, provedene su morfometrijske i merističke analize, a potom su dobiveni
rezultati uspoređivani s literaturnim podacima vrsta istog roda u drugim područjima. Rezultati
morfometrijskih analiza pokazali su da postoje varijabilnosti unutar i između populacija, a
najzanimljivijim se pokazalo izdvajanje populacije vrste R. vladykovi iz Save. Merističke analize
pokazale su se adekvatnom metodom za identifikaciju ovih vrsta. Ovom analizom, također je
utvrđen isti broj ljusaka oko kaudalnog pedunkula vrsta R. vladykovi i R. kesslerii, što se ne
podudara s literaturnim podacima i upućuje na pogrešku u ključu koji se koristi za određivanje
vrste R. kesslerii te se time otvara potreba za daljnjim istraživanjem.According to current findings, on teritory of Republic of Croatia there are 4 species from genus
Romanogobio, 3 of which are located in Danube basin. Individuals studied in this research are
determined as species Romanogobio kesslerii and Romanogobio vladykovi. Aim of this research
was to describe their morphological characteristics and to conclude if there are any differences
among populations of each species and between populations of different species. Research has
covered 19 localities in 7 rivers. In order to determine differences, morphometric and meristic
analyses were made and then compared with literature data for same species in different areas.
Results of morphometric analysis confirmed that there are variability among and inbetwen
populations of species, with divergence of population R. vladykovi in Sava being the most
noticable. Meristics analysis have shown as adequate method of identification of this species. With
this analysis, same number of scales around caudal peduncle in species R. vladykovi and R. kesslerii
are confirmed which don't match with literature data and it points to mistake in identification key
of the species R. kessleri which opens a need for further research
Phytochemical content and antioxidant potential of petals and tepals of selected flowering plants
No full textBiljke su zauzele različite aspekte našega života, koristimo ih u kozmetici, medicini, kao
začine i hranu, kao bojila te u industriji ulja. Industrijska je praksa upotrebljavati određeni dio
biljke, dok se ostali dijelovi uglavnom zanemare i ne iskorištavaju. S ekološkog i
ekonomskog aspekta, takav način „djelomičnog“ iskorištavanja biljaka nije održiv. Cilj ovog
diplomskog rada bio je usporediti kvalitativni i kvantitativni sastav bioaktivnih spojeva, te
antioksidacijski potencijal etanolnih ekstrakata tepala/latica šafrana, šumskog sljeza, pravog
duhana, suncokreta i ljekovitog nevena kako bi se doprinijelo boljem razumijevanju
biopotencijala ovog biljnog materijala. Spektrofotometrijski je određen udio različitih skupina
bioaktivnih spojeva, te antioksidacijski kapacitet ekstrakata. Ekstrakti tepala šafrana sadrže
značajno veći udio ukupnih fenolnih spojeva, hidroksicimetnih kiselina, flavonola i
proantocijanidina u odnosu na ostale analizirane uzorke. 70%-tni etanolni ekstrakt duhana
sadrži više ukupnih flavonoida u odnosu na ostale istraživane cvjetnice. Najveći udio ukupnih
flavonoida u 40%-tnom etanolu imali su ekstrakti latica suncokreta. Značajno veći udio
karotenoida zabilježila sam kod ekstrakata latica nevena i suncokreta. U sve tri korištene
metode mjerenja antioksidacijskog kapaciteta u ekstraktima s 40%-tnim etanolom latice
suncokreta i sljeza imale su najviše vrijednosti, dok su u ekstraktima sa 70%-tnim etanolom
latice suncokreta bile najučinkovitije. Na temelju ovoga zaključujem da su latice suncokreta i
sljeza bogatije antioksidansima od ostalih uzoraka.Plants have occupied different aspects of our life, we use them in cosmetics, medicine, as
spices and food, as dyes and in oil the industry. Most of these plants are known for one of
their plant organs, and these are generally not flowers, petals and tepals. It is industrial
practice to use a certain part of the plant while the other parts are mostly ignored and not
used. From an ecological and economic point of view, „partial“ exploitation of plants is not
sustainable. The aim of this thesis was to compare the qualitative and quantitative
composition of bioactive compounds, and the antioxidant potential of ethanolic extracts of
tepals/petals of saffron, common mallow, real tobacco, sunflower and medicinal calendula in
order to contribute to a better understanding of the biopotential of this plant material. The
proportion of different groups of bioactive compounds and the antioxidant capacity of the
extracts were determined spectrophotometrically. Saffron tepal extracts contained a
significantly higher proportion of total phenolic compounds, hydroxycinnamic acids,
flavonols and proanthocyanidins compared to other analyzed samples. The 70% ethanol
extract of tobacco contained more total flavonoids compared to other investigated flowering
plants. Sunflower petal extracts had the highest proportion of total flavonoids in 40% ethanol.
I noted a significantly higher proportion of carotenoids in the extracts of marigold and
sunflower petals. In all three used methods of measuring antioxidant capacity, sunflower and
common mallow petals had the highest values in extracts with 40% ethanol, while sunflower
petals were the most effective in extracts with 70% ethanol. Based on this, I conclude that
sunflower and common mallow petals are richer in antioxidants than other samples
Indicator system of the Trophic Diatom Index of the Republic of Croatia
No full textFitobentos je biološki element kakvoće tekućica u Hrvatskoj, kojeg u metodologiji ocjene
ekološkog stanja predstavljaju dijatomeje, a korišteni indeks u metodologiji je Trofički indeks
dijatomeja Republike Hrvatske (TIDHR). Baza podataka višegodišnjeg monitoringa fitobentosa
u razdoblju od 2010.-2020. obuhvaća ukupno 581 mjernu postaju i sadrži 1169 podataka o
sastavu i relativnoj brojnosti dijatomeja. Od ukupno 959 vrsta dijatomeja u operativnoj listi,
indikatorske vrijednosti i težine trofičkog indeksa ima 545 vrsta. Broj vrsta koje nemaju
indikatorsku vrijednost i težinu je 415. Broj vrsta koje su zastupljene s više od 60 frustula (15
%) u uzorku, a nemaju indikatorske vrijednosti i težine, je ukupno 26. Prema ciljevima,
relativne učestalosti 26 vrsta u uzorcima korelirane su s okolišnim čimbenicima te je prikazana
njihova rasprostranjenost, ekološke značajke i mogućnosti uvođenja novih indikatorskih
veličina i težina. Za sve izračunate OEK-e korelacijom prikazan je odgovor na okolišne
čimbenike. Iako nisu dobivene značajne promijene u izračunima ekološkog stanja na
cjelokupnom setu podataka, ovo istraživanje doprinos je novim spoznajama o indikatorskom
sustavu Trofičkog indeksa dijatomeja Republike Hrvatske na način da je ukazalo na koje vrste
daljnja istraživanja i statističke obrade, trebaju biti usmjerene kako bi se unaprijedio
indikatorski sustav.Fitobentos is a biological water quality element of streams and rivers in Croatia, represented in
the assessment by diatoms. The index used in the methodology is the Trophic Diatom Index of
the Republic of Croatia (TIDHR). The database of phytobenthos monitoring for the period 2010-
2020 includes a total of 581 monitoring stations and contains 1169 data on the composition and
relative abundance of diatoms. Of the total 959 diatom species in the operational list, the
indicator values and weights of the TIDHR indicate 545 species. The number of species for
which indicator values and weights are not available is 415, and the number of species
represented in the sample with more than 60 frustules and no indicator values and weights is
26. Consistent with the main objectives of the study, the relative abundances of the 26 species
in the samples were correlated with environmental factors. Their distribution, ecological
characteristics, and the possibility of introducing new indicator values and weights were
indicated. For all calculated OEKs, the correlation shows the response to environmental factors.
Although no significant changes in ecological status were found for the whole data set, this
study contributes to new knowledge about the indicator system of the Trophic Diatom Index
of the Republic of Croatia and indicates what kind of further research and statistical processing
should be carried out to improve the indicator system
Diet of the largemouth bass (Micropterus salmoides) in the Baćina lakes
No full textPastrvski grgeč endem je Sjeverne Amerike, koji je zbog popularnosti u sportskom ribolovu
rasprostranjen po cijelom svijetu, a danas se nalazi na listi od 100 najinvazivnijih vrsta svijeta.
U Hrvatsku je unesen krajem 60-ih godina, a u Baćinskim jezerima je zabilježen 2019.
godine. Prehrana pastrvskog grgeča do sada nije istraživana, stoga je glavni cilj ovoga rada
bio odrediti kvalitativni i kvantitativni sastav prehrane ove vrste u Baćinskim jezerima. Uzorci
su prikupljani u razdoblju od 2019. do 2021. godine. Ukupno je prikupljeno 188 jedinki, a
uzorci probavila i sadržaja želuca su obrađeni u Laboratoriju za kralješnjake. Najučestalija
vrsta u sadržaju želudaca po brojnosti, masi i frekvenciji je kozica Palaemonetes antennarius.
Rezultati su pokazali kako su glavni tipovi hrane skupine riba razreda Actinopteri i rakovi
deseteronošci (Decapoda), a kukci (Insecta) slučajan su plijen u prehrani. Identificirane su
dvije endemske vrste Pomatoschistus canestrinii i Rutilus basak. Također, zabilježene su
vrste Atherina boyeri i Gambusia holbrooki, a uočen je i kanibalizam. Najučestalija među
piscivornim plijenom je porodica Gobiidae. Pastrvski grgeč u jezerima ima pozitivan
alometrijski rast. Sukladno dobivenim rezultatima prehrane i sposobnosti brze prilagodbe
novom staništu, pastrvski grgeč predstavlja prijetnju autohtonim zajednicama riba u
Baćinskim jezerima.Largemouth bass is endemic species to North America which is distributed all around the
world due to its popularity in sport fishing and is listed in 100 most invasive species in the
world. It was introduced in Croatia at the end of the 60s and recorded in 2019´ in Baćina
lakes. The main aim of this study was to determine qualitative and quantitative diet
composition. Samples (188 in total) were collected since year 2019 – 2021, and stomach
contents were processed in vertebrate laboratory. Most common species by the abundance,
weight and frequency occurrence in stomach content was grass shrimp Palaemonetes
antennarius. Results show groups of Actinopteri and Decapoda are main food prey and the
Insecta were accidental prey. Two endemic fish species were identified: Pomatoschistus
canestrinii and Rutilus basak. Species Atherina boyeri i Gambusia holbrooki were also
recorded, along with cannibalism. The most common family in piscivore diet found in
stomach content was Gobiidae. Largemouth bass in lakes has positive allometric grow.
Considering these results and the capability of quickly adjustment to new area, largemouth
bass presents a threat to the native species in Baćina lakes
Spomenice Prirodoslovno-matematičkog fakulteta Sveučilišta u Zagrebu
No full textSpomenice Prirodoslovno-matematičkog fakulteta Sveučilišta u Zagreb
Synthesis and properties of guanidine cocatalysts prepared by cycloadition reactions
No full textU sklopu ove disertacije razvijene su metode za sintezu novih polickličkih gvanidina. Pri
tome je istražen utjecaj strukture gvanidinske skupine i tipa dienofila na uspješnost reakcije
cikloadicije i moguća uloga protona kao zaštitne skupine. Derivati maleinske kiseline daju
smjesu egzo i endo produkata neovisno o primijenjenom sintetskom pristupu. Cikloadicija
furfuril-gvanidina na dimetil-acetilendikarboksilat daje ciljane produkte u dobrim prinosima
uz djelomičnu konverziju u tri- ili tetracikličke derivate. Objašnjena je i pojava aza-
Michaelove adicije kao nusreakcije uzrokovane nukleofilnošću aniona. Mehanizmi reakcija su
istraženi i DFT kvantno kemijskim proračunima.
Novim spojevima je ispitana kokatalitička aktivnost u aldolnoj reakciji kataliziranoj (S)-prolinom. Opaženo je povećanje selektivnosti i iskorištenja reakcije pri čemu se ističe rezultat od 98:2 omjer dijastereoizomera, uz enantiomerni suvišak >99,5 % i prinosom
od 97 % pri 0°C. Najbolji kokatalizator je ispitan u Knoevenagelovoj reakciji gdje je primijećena slaba
aktivnost, značajno manja nego kod strukturno sličnog 1,5,7-triazabiciklo[4.4.0]dec-1-ena.As part of this dissertation, methods for the synthesis of new polycyclic guanidines were
developed. The influence of the guanidine structure and the type of dienophile on the success
of the cycloaddition reaction and the possible role of protons as a protective group were
investigated. Maleic acid derivatives give a mixture of exo and endo products regardless of
the synthetic methods employed. The cycloaddition of furfuryl-guanidine to dimethyl
acetylenedicarboxylate produces the target products together with three- or tetracyclic
derivatives in good yields. Aza-Michael addition as a side reaction caused by the
nucleophilicity of anions is also explained. Reaction mechanisms were investigated by DFT
quantum chemical calculations.
The cocatalytic activity of the new compounds was tested in aldol reaction catalyzed by (S)-proline.
An increase in the selectivity and yield of the reaction was observed, with the best
result of 98:2 diastereoisomer ratio, with an enantiomeric excess of >99.5% and a yield of
97% at 0 °C. The best cocatalyst was tested in the Knoevenagel reaction where a poor
activity, significantly lower than for 1,5,7-triazabicyclo[4.4.0]dec-1-ene, was observed
Neural networks and statistical learning
No full textPrvo poglavlje započinjemo s principima rada neurona i bioloških neuronskih mreža. Nakon dane motivacije, započinjemo s njihovim matematičkim modeliranjem umjetnim neuronskim mrežama. Prvo se susrećemo s McCulloch-Pittsovim neuronom - prvim matematičkim modelom neurona. Kako ima određene nedostatke, uvodimo perceptron kao općenitiji model umjetnog neurona. Uz perceptrona dolazi algoritam perceptronskog učenja te ADALINE algoritam učenja. Nadalje, uvodimo višeslojni perceptron kao matematički model bioloških neuronskih mreža te predstavljamo tzv. "Backpropagation" algoritam učenja.Drugo poglavlje formalizira problem učenja jezikom Teorije Vjerojatnosti. Problem učenja smatramo pronalaskom optimalnih parametara umjetne neuronske mreže. Svaka umjetna neuronska mreža, kao parametarska funkcija, generira određenu klasu funkcija koje dobivamo variranjem njenih parametara. Cilj drugog poglavlja je odgovoriti na pitanje ima li smisla tražiti optimalne parametre modela unutar dane klase funkcija koju sam model generira. Pokazuje se da je odgovor potvrdan. Naime, postoji metrika zvana Vapnik-Chervonenkisova dimenzija, pridružena proizvoljnoj klasi funkcija, čija konačnost u potpunosti karakterizira naučivost same klase. Ovaj rezultat je iskazan kao Osnovni Teorem Statističkog Učenja. Na samom kraju pokazujemo kako sve klase funkcija koje generiraju umjetne neuronske mreže definirane u prvom poglavlju imaju konačnu Vapnik-Chervonenkisovu dimenziju.We start the first chapter by explaining the workings of neurons and biological neural networks. After providing some motivation, we begin their mathematical modelling with artificial neural networks. We define the McCulloch-Pitts neuron -- the first mathematical model of a neuron. As it has certain limitations, we introduce the perceptron as a more general model of an artificial neuron. Along with the perceptron come the perceptron learning algorithm and the ADALINE learning algorithm. Furthermore, we introduce the multilayer perceptron as a mathematical model of biological neural networks and present the so-called "Backpropagation" learning algorithm. The second chapter formalizes the problem of learning in the language of Probability Theory. We consider the learning problem as the search for the optimal parameters of an artificial neural network. Each artificial neural network, as a parametric function, generates a certain class of functions that we obtain by varying its parameters. The goal of the second chapter is to answer the question of whether it makes sense to search for the optimal model parameters within a given class of functions generated by the model itself. It turns out that the answer is yes. Namely, there is a metric called the Vapnik-Chervonenkis dimension, associated with an arbitrary class of functions, whose finiteness completely characterizes the learnability of said class. This result is stated as the Fundamental Theorem of Statistical Learning. At the very end, we show how all classes of functions generated by artificial neural networks defined in the first chapter have a finite Vapnik-Chervonenkis dimension
Spatial distribution and density of dolines of the Biokovo Nature Park
No full textPonikve su zatvoren udubine u krškom reljefu te su najkarakterističniji oblici u kršu. U radu je analiziran prostorni raspored i gustoća ponikava Parka prirode Biokovo. Podaci o lokacijama ponikava su preuzeti vektorizacijom podataka s topografskih karate VGI 1:25000, a morfometrijski podaci reljefa su dobiveni analizama digitalnog modela reljefa (DEM) rezolucije 5 x 5 m. Analizirana je gustoća ponikava po svakom od razreda nadmorske visine, nagiba padina, ekspozicije padina i vertikalne raščlanjenosti reljefa. Provedena je analiza korelacije gustoće ponikava i morfometrijskih parametara na razini manje prostorne skale koja obuhvaća neposrednu okolinu ponikava i na razini veće prostorne skale koja obuhvaća cijelu površinu Parka prirode. U radu je analiziran i uspoređen prostorni raspored i gustoća ponikava s geološkom građom. Provedena je korelacija gustoće ponikava s gustoćom rasjeda kao i korelacija gustoće ponikava s udaljenosti od rasjeda. Analizirano je određeno područje na kojem su korištena dva načina definiranja granica ponikava, te su na temelju toga izračunate dubine, površine i volumeni ponikava. Analiza pokazuje značajnu korelaciju općih morfometrijskih obilježja reljefa te pojave i gustoće ponikava.Dolines are closed depressions in karst relief and are the most characteristic forms in karst landscapes. This study analyzes the spatial distribution and density of dolines in the Biokovo Nature Park. Data on the locations of dolines were obtained through vectorization using 1:25000 scale topographic maps, and morphometric relief data were derived from analyses using a 5x5 m resolution digital elevation model (DEM). The density of dolines was analyzed across different classes of elevation, slope gradient, slope aspect, and vertical dissection of the relief. A correlation analysis was conducted between the density of dolines and morphometric parameters at a smaller spatial scale involving the immediate surroundings of the dolines and at a larger spatial scale covering the entire area of the Nature Park. The paper analyzed and compared the spatial distribution and density of dolines with geological structure. Correlation was conducted between the density of dolines and fault density, as well as the correlation between the density of dolines and the distance from faults. A specific area was analyzed where two methods of defining the boundaries of dolines were used, and based on this, the depths, areas, and volumes of the dolines were calculated. The analysis shows a significant influence of relief morphometry on the occurrence and density of dolines
Novel Measurement of the Neutron Magnetic Form Factor from A=3 Mirror Nuclei
No full textThe electromagnetic form factors of the proton and neutron encode information on the spatial structure of their charge and magnetization distributions. While measurements of the proton are relatively straightforward, the lack of a free neutron target makes measurements of the neutron’s electromagnetic structure more challenging and more sensitive to experimental or model-dependent uncertainties. Various experiments have attempted to extract the neutron form factors from scattering from the neutron in deuterium, with different techniques providing different, and sometimes large, systematic uncertainties. We present results from a novel measurement of the neutron magnetic form factor using quasielastic scattering from the mirror nuclei 3H and 3He, where the nuclear effects are larger than for deuterium but expected to largely cancel in the cross-section ratios. We extracted values of the neutron magnetic form factor for low-to-modest momentum transfer, 0.6<2<2.9 GeV2, where existing measurements give inconsistent results. The precision and 2 range of these data allow for a better understanding of the current world’s data and suggest a path toward further improvement of our overall understanding of the neutron’s magnetic form factor
Climate change as a topic in physics teaching: Greenhouse effect
No full textNastava fizike treba povezivati temeljne principe s primjenama na aktualne teme današnjice. Klimatske promjene su jedan od glavnih problema suvremenog društva. Zbog toga je važno da se učenici što bolje upoznaju s ovom tematikom, a dio njih motivira u smjeru suvremenih zanimanja u STEM područjima koja su vezana uz rješavanje tih problema. Zbog sporih izmjena kurikuluma, školsko obrazovanje je nedovoljno usmjereno prema toj problematici. Učinak staklenika jedan je od ključnih koncepata za razumijevanje klimatskih promjena te je potrebno razvijati nastavne sadržaje kojima bi se približio učenicima, ali i nastavnicima. Pravilnom shvaćanju ovog fenomena treba doprinijeti nastava fizike, pri čemu se naglasak stavlja na interakciju elektromagnetskih valova sa Sunca i Zemlje uz utjecaj na globalne temperature. U ovom radu razrađujemo ideje kako kroz pokuse uvesti ovu temu u nastavu fizike.The teaching of physics should connect basic principles with applications to current topics of today. Climate change is one of the main problems of modern society. That is why it is important that students get to know this topic as well as possible, and some of them are motivated in the direction of modern professions in STEM fields that are related to solving these problems. Due to slow curriculum changes, school education is insufficiently focused on this issue. The greenhouse effect is one of the key concepts for understanding climate change, and it is necessary to develop teaching content to bring it closer to students and teachers. The teaching of physics should contribute to the correct understanding of this phenomenon, where the emphasis is placed on the interaction of electromagnetic waves from the Sun and the Earth with the influence on global temperatures. In this thesis, we develop ideas on how to introduce this topic into physics classes through experiments