Synthesis and characterization od Sm3+, Eu3+, Ni2+ and Cu2+ doped titanium (IV) oxide nanoparticles

Predmet istraživanja ove doktorske disertacije obuhvata sintezu nanočestica TiO2 različitih oblika i veličina dopiranih jonima retkih zemalja (Eu3+ i Sm3+) i prelaznih metala (Ni2+ i Cu2+) novom metodom, kao i njihovu strukturnu, optičku i magnetnu karakterizaciju.Nanočestice TiO2 dopirane jonima Sm3+, Eu3+, Ni2+ i Cu2+ su sintetisane hidrotermalnom metodom uz upotrebu disperzije nanotuba Ti(IV) oksida u prisustvu jona dopanta kao prekursora. Primenjujući hidrotermalnu transformaciju nanotuba u prisustvu jona dopanta za sintezu dopiranih nanočestica TiO2 izbegavaju se problemi vezani za proces kristalizacije i tzv. samočišćenja dopiranih nanočestica koji se, poznato je, javljaju upotrebom molekulskih prekursora u sintezi, čime se utiče na efikasnost čitavog procesa. Generalno, sinteza dopiranih nanočestica TiO2 koje predstavljaju predmet istraživanja ove doktorske disertacije se odvijala u dva koraka. Naime, prvi korak predstavljala je sinteza prekursorskih nanotuba Ti(IV) oksida hidrotermalnim tretmanom disperzije komercijalnog praha TiO2. Praćen je uticaj promene uslova u kojima se odvija hidrotermalni postupak, kao i postsintetskog tretmana, na oblik, veličinu i kristalnu strukturu rezultujućih nanotuba. Drugi korak u postupku sinteze predstavljala je hidrotermalna transformacija sintetisanih nanotuba u prisustvu jona dopanta, u krajnji produkt tj. dopirane nanočestice TiO2. Primena ove metode omogućava sintezu nanočestica različitih veličina i oblika jednostavnom optimizacijom početnih uslova sinteze (promenom početne koncentracije nanotuba Ti(IV) oksida, pH vrednosti sredine, vremena trajanja hidrotermalnog tretmana i temperature).Rad se tematski može podeliti u dve celine:1. Sinteza i karakterizacija nanočestica TiO2 dopiranih jonima retkih zemalja (Eu3+ i Sm3+); Sinteza i karakterizacija nanočestica TiO2 dopiranih jonima prelaznih metala (Ni2+ i Cu2+)...The subject of this PhD thesis is the synthesis of rare earth (Eu3+ and Sm3+) and transition metal (Ni2+ and Cu2+) ions doped TiO2 nanoparticles of different shapes and sizes by a novel method and their structural, optical and magnetic characterization.Sm3+, Eu3+, Ni2+ and Cu2+ doped TiO2 nanoparticles were synthesized by hydrothermal method using dispersions of titania nanotubes in the presence of dopant ions, as precursors. Using hydrothermal transformation of nanotubes in the presence of dopant ions, the problems related to the nucleation stage and consequently self-purification of doped nanocrystals, that occur when molecular precursors used, could be avoided. Synthesis of doped TiO2 nanoparticles that are subject of this PhD thesis included a two-step procedure. Namely, the first step is the synthesis of precursor titania nanotubes by hydrothermal treatment of dispersion of commercial TiO2 powder. The effects of changes of the hydrothermal synthesis conditions on the shape, size and crystal structure of resulting nanotubes were investigated. The second step in the synthetic procedure is hydrothermal transformation of as synthesized nanotubes in the presence of dopant ions into the final product, i.e. doped TiO2 nanoparticles. The use of such synthetic procedure enables the formation of doped nanoparticles of different sizes and shapes, simply by optimization of the initial synthetic conditions (changes in concentration of nanotubes in dispersion, or pH value of dispersion, or duration of hydrothermal treatment and temperature).Subject of this work can be divided into two main units:1. Synthesis and characterization of rare earth ions (Eu3+ and Sm3+) doped TiO2 nanoparticles;2. Synthesis and characterization of transition metal ions (Ni2+ and Cu2+) doped TiO2 nanoparticles..

Determination of the activity concentration of 137Cs and 40K in blueberry-based products consumed in Serbia

The aim of the study is the investigation of the activity concentration of 137Cs and 40K in blueberry-based products that are available on the market in the Republic of Serbia. Samples were bought in stores during September 2017 and in total, ten packaged juices, two jams, two sweets and a fresh wild blueberry were measured. The activity concentrations of 137Cs in blueberry-based juices, jams and sweets varied from <MDA to 4.1 Bq/kg, <MDA to 21 Bq/kg and 0.6 Bq/kg to 28 Bq/kg, respectively. The average activity concentration of 137Cs in fresh wild blueberry was 4.1 Bq/kg. In Serbia, the recommended activity concentration of 137Cs in juices and sweets is 15 Bq/kg and 150 Bq/kg in fresh blueberries. The tested samples of juices, jams, fresh wild blueberry and one of the sweets meet the set criteria for 137Cs while one sweets sample exceeds the limit. The activity concentrations of 40K in juices, jams and sweets varied from 3.5 to 55 Bq/kg, 13.9 to 19.2 Bq/kg and 17.2 to 227 Bq/kg, respectively. The average activity concentration of 40K in fresh wild blueberry was 32 Bq/kg. With the obtained result the annual effective dose equivalent due to ingestion of blueberry-based products for adults was calculated, and for 137Cs in blueberry-based juices, jams, sweets and fresh wild blueberry varied from 0.2 to 2.5 Sv, 2.8 Sv, 0.4 to 17.0 Sv and 2.5 Sv, respectively. The annual effective dose equivalent for 40K in blueberry-based juices, jams, sweets and fresh wild blueberry varied from 1.0 to 16.0 Sv, 1.2 Sv, 5.0 to 66.0 Sv, and 9.3 Sv, respectively. © 2019 RAD Association. All rights reserved.Conference of 6th International Conference on Radiation and Applications in Various Fields of Research, RAD 2018 ; Conference Date: 18 June 2018 Through 22 June 2018; Conference Code:14955

Attitudes of Teacher Education Students and Class Teachers to Distance Education

The educational system of the Republic of Croatia saw the transition from classroom to distance education starting on March 13, 2020 due to the pandemic of the new, infectious coronavirus COVID-19. The pandemic caused a sudden transition to distance education and a number of difficulties in the implementation of online education, therefore a study was conducted to determine the attitudes of students, who are future class teachers, and practitioner-teachers to distance education in which they participated. The results of the research show significant differences in the perception of the transition from classroom to distance education, revealing it was more difficult for practitioner-teachers to organize and implement online education. The research determined attitudes to distance education and attitudes to television-based education. The obtained research results can be used to improve distance education, which will be carried out as needed, alternating with classroom teaching

The Impact of E-Learning on Student Selfresponsibility in Doing Their Homework

U skladu s globalnim društvenim promjenama u središtu odgojno-obrazovnog procesa treba biti aktivan i samoodgovoran učenik kako tijekom nastave, tako i pri izvršavanju samostalnih izvannastavnih zadaća. Upravo taj suvremeni učenik, od kojeg se očekuje aktivnost i samoodgovornost, okružen je tehnološkim dostignućima koja mu omogućuju brzo dobivanje informacija, komuniciranje, izradu dobivenih zadaća i dobivanje povratnih informacija pa je čest korisnik informacijske i komunikacijske tehnologije. Neovisno o širokom spektru mogućnosti primjene IKT-e, on ju ipak češće koristi za socijalne interakcije na različitim društvenim mrežama, a rijetko, odnosno samo ako je upućen na pojedine računalne sadržaje, koristi ju u obrazovne svrhe. Stoga je nužno implementirati IKT ne samo u nastavni proces u školam, već ih koristiti pri oblikovanju različitih zadaća za učenike koji će oni elektroničkim putem primati, samostalno rješavati, slati na provjeru te dobivati povratnu informaciju. Upravo s ciljem utvrđivanja utjecaja primjene sustava e-učenja na samoodgovornost učenika općenito, a posebice pri izvršavanju domaćih zadaća prirode i biologije, provedeno je istraživanje na uzorku od osam osnovnoškolskih razrednih odjela podijeljenih u dvije skupine: eksperimentalnu, koja je učila na sustavu e-učenja, i kontrolnu, koja je bila uključena u suvremene oblike aktivnog učenja. Domaće zadaće za učenike obiju skupina bile su istovjetne, a razlikovao se način dobivanja uputa za zadaću, izvršavanja i predaje uradaka, e-oblikom ili tradicionalno. Iako analiza rezultata riješenosti domaćih zadaća učenika obiju skupina pokazuje podjednaku uspješnost, ipak je uočena potpuna samoodgovornost učenika koji su učili na sustavu Moodle. Dobiveni rezultati istraživanja prikazani u ovom radu ukazuju kako učenje na sustavu Moodle ima veći utjecaj na samoodgovornost učenika pri obavljanju domaćih zadaća te stoga mogu poslužiti učiteljima praktičarima kao poticaj za primjenu sustava e-učenja u nastavnom procesu općenito, a posebice za samostalne aktivnosti učenika poput domaćih zadaća.Following the global social changes, the center of the educational process should be reserved for a student who is active and self-responsible, both in classroom and while carrying out her/his individual extracurricular tasks. Precisely the contemporary student, who is expected to be active and responsible, is surrounded by technological advances that enable her/him to quickly obtain information, communicate, carry out the given tasks and get feedback, therefore she/he becomes a frequent user of information and communication technology. Despite the wide range of ICT applications, this technology is more commonly used for social interactions on various social networks, and rarely for educational purposes, i.e. only if students had been previously referred to a specific digital content. Therefore, it is necessary to implement information and communication technology and e-learning not only in the teaching process in schools, but to use them in designing different tasks which students will receive, complete, send for correction, and receive feedback electronically. In order to determine the impact of the application of e-learning on student self-responsibility in general, and in particular in completing homework assignments in Science and Biology classes, a study was conducted on a sample of eight primary school classes divided into two groups: the experimental, using fully online e-learning resources, and the control group, using modern forms of active learning. The homework assignments for the students of both groups were the same, while the way of receiving homework assignments, carrying them out and submitting them was different, either in e-surrounding or traditionally. Although the analysis of the results of the homework assignments done by the students of both groups shows equal student success, the study registers a complete self-responsibility of the students involved in e-learning via Moodle platform. The research findings presented in this paper indicate that Moodle e-learning has a greater impact on student self-responsibility in doing their homework, and can therefore serve as a stimulus for teachers practitioners to apply e-learning systems in the teaching process in general, and in particular for independent student activities such as homework assignments

Caesium-137 and potassium-40 in blueberry-based products on the market in Serbia

VI International Conference on Radiation in Various Fields of Research : RAD 2018 : book of abstracts; June 18-22, 2018; Ohrid, Macedoni

Efekat organske proizvodnje mleka na neke parametre kvaliteta mleka

In recent years there is growing interest of consumers for the consumption of organic milk, because of its favorable content of fatty acids that has a positive effect on human health. The aim of this study was to examine the content of fatty acids, vitamins A, C and α - tocopherol in milk which was obtained in different production systems, organic and conventional. The samples of conventional and organic milk were collected from farms located in Vojvodina, throughout all seasons. The prepared samples were analyzed using gas chromatography with mass spectrometry and high - performance liquid chromatography. The results proved that the milk produced in accordance with the principles of organic production had a higher content of polyunsaturated and omega-3 fatty acids compared with conventional milk (p lt 0.01) during the whole examination period, while the greatest differences were perceived in the pasture season. Also, organic milk had a higher content of vitamins A, C and α - tocopherol compared with the conventionally produced milk, although there was no statistically significant difference.Poslednjih godina raste interes potrošača za konzumiranje organskog mleka, zbog povoljnijeg sadržaja masnih kiselina koje imaju pozitivan efekat na zdravlje ljudi. Cilj ovog rada je bio da se ispita sadržaj masnih kiselina, vitamina A, C i α-tokoferola u mleku koje je dobijeno u različitim sistemima proizvodnje, organskom i konvencionalnom. Uzorci konvencionalnog i organskog mleka sakupljani su na farmama u Vojvodini tokom čitave godine. Analiza uzoraka je vršena primenom metoda gasne hromatografije i tečne hromatografije. Rezultati su pokazali da je mleko proizvedeno po principima organske proizvodnje tokom celog perioda praćenja imalo veći sadržaj polinezasićenih i omega-3 masnih kiselina u odnosu na konvencionalno mleko (p lt 0,01), s tim što su najveće razlike bile u sezoni paše. Sadržaj vitamina A, C i α -tokoferola bio je veći u organskom mleku od sadržaja u mleku iz konvencionalne proizvodnje, mada nije utvrđena statistička značajnost ovih razlika

Radioactivity in monocalcium phosphate and complete feed mixtures for pigs

Mineral additives, such as monocalcium phosphate, that are commonly used on pig farms, are obtained by processing phosphate mineral ore, and can contain high levels of 238U. Since ingestion is the main route of radioactive contamination of both animals and humans, the goal of this paper is to measure specific activity of natural and artificial radionuclides in monocalcium phosphate and complete feed mixtures for pigs. Mineral additives with high levels of natural radionuclides can contaminate complete feed mixtures making them unsuitable for use. Samples were collected from three different farms, and in total fifteen samples of monocalcium and forty five samples of complete feed mixture were measured. Samples of monocalcium phosphate show the 238U activity concentration of 13.2-2097Bq/kg. Other naturally occurring radionuclides are measured in monocalcium and the results give: 21.4-25.5 Bq/kg for 40K, 1.5 -12.1 Bq/kg for226Ra, 1.5-2.9 Bq/kg for 232Th, and 1.5-10.8 Bq/kg for 214Bi. These radionuclides are further measured in complete feed mixtures and only one sample shows elevated concentrations of 238U (3.1 Bq/kg) and 226Ra (3.5 Bq/kg). Potassium-40 is detected in all samples, with the specific activity range 208-329 Bq/kg, while other naturally occurring radionuclides and artificial radioceasium are below the detection limits

The Competences of Biology Teachers regarding the Application of Information and Communication Technologies in the Educational Process

Profesionalni razvoj učitelja treba biti u samom središtu obrazovne politike svake države jer je njihova kompetentnost jedan od glavnih činitelja koji djeluju na razinu obrazovnih postignuća učenika. Stoga je izuzetno važno imati osposobljene učitelje za osmišljavanje raznovrsnih nastavnih scenarija i primjenu suvremenih tehnologija kojima bi omogućili učenicima stjecanje znanja i razvijanje kompetencija potrebnih za zdrav i održiv život u 21. stoljeću. Sa svrhom ustvrđivanja kako i u kolikoj su mjeri učitelji biologije osposobljeni za primjenu informacijsko-komunikacijskih tehnologija, a posebice e-učenja u sustavu Moodle u nastavnom procesu, izvršeno je pilot-istraživanje na uzorku od 65 učitelja biologije Splitsko-dalmatinske županije. Dobiveni će rezultati o stanju u nastavi biologije poslužiti kao poticaj za kritičko promišljanje i preoblikovanje inicijalnog obrazovanja budućih učitelja i profesionalnog usavršavanja učitelja praktičara biologije.The professional training of teachers should be in the very center of the educational policy of each country, since teachers’ competence is one of the major factors that affect the level of students’ educational achievements. Therefore, it is of paramount importance to have qualified teachers to enable the design of various teaching scenarios and the implementation of modern technologies that would enable students to acquire knowledge and develop competences required for a healthy and sustainable life in the 21st century. In order to determine how and to what extent biology teachers are trained for the application of ICT technologies in the teaching process, and especially E-learning within the Moodle system, pilot research was carried out on a sample of 65 Biology teachers of Split-Dalmatia County. The results obtained display the situation in teaching Biology and will be used as a stimulus for critical consideration and the transformation of the education of future teachers, as well as for the further professional development of practicing teachers of Biology

Stavovi studenata učiteljskog studija i učitelja razredne nastave o nastavi na daljinu

Prelazak s učioničke nastave na nastavu na daljinu u cijelom odgojno-obrazovnom sustavu Republike Hrvatske započeo 13. ožujka 2020. godine zbog pandemije novog zaraznog koronavirusa COVID-19. Navedeno je uvjetovalo nagli prelazak na nastavu na daljinu i niz poteškoća tijekom njene realizacije pa je stoga provedeno istraživanje kojem je cilj bio utvrditi stavove studenta, budućih učitelja razredne nastave, i učitelja praktičara o nastavi na daljinu u kojoj su sudjelovali. Rezultati provedenoga istraživanja pokazuju značajne razlike u percepciji prelaska s učioničke nastave na nastavu na daljinu koja je učiteljima praktičarima bila teža za organizirati i realizirati. Istraživanjem su utvrđeni stavovi o nastavi na daljinu te stavovi o nastavi na televiziji. Dobiveni rezultati istraživanja mogu poslužiti za unapređenje nastave na daljinu koja će se provoditi po potrebi izmjenjujući se s nastavom u učionici

Photoluminescence properties of Eu3+ doped TiO2 nanoparticles

Eu3+ doped TiO2 nanoparticles were synthesized during extended hydrothermal treatment of TiO2 nanotubes dispersion in the presence of Eu(NO3)3. Eu3+ ions occupy two different sites of titania nanoparticles having different binding energies: core octahedral sites and undercoordinated surface sites. Photoluminescence spectra of Eu3+ doped TiO2 nanoparticles independently of dopant concentration consist of three characteristic peaks located at λ=543, 596, and 617 nm attributed to the intra-4f transitions of Eu3+ ion. Removal of excess of Eu3+ ions from the surface and from the undercoordinated surface sites applying post synthetic dialysis of the sample affects its photoluminescence spectrum. The peak intensity at λ=617 nm (5D0→7F2 transition) decreases after dialysis. Such “self-purification” process of nanoparticles is a consequence of fact that dopant ions which substitute Ti atoms in the undercoordinated coordination environment of reconstructed surfaces are weakly bound to the anatase lattice