Photocatalytic activity of SrGd2O4 down and up-convertor systems

Issues with air and water pollution have become a worldwide problem. Photocatalysis is a technique that holds promise for resolving these urgent issues due to its sustainability, affordability, and environmental friendliness. Recently, anti-Stokes and Stokes luminescence materials have been identified as potentially efficient candidates for photocatalysis exploitation. Under irradiation, doping different Ln3+ ions in an inorganic host will induce designable down and up-conversion emissions beginning in the UV and extending to the NIR region. This investigation will examine the photocatalytic application of the chosen samples. All samples were successfully prepared via sol-gel assisted combustion method. X-ray Powder Diffraction pattern proved that all samples crystallize as a pure orthorhombic phase of SrGd2O4. Scanning and transmission electron microscopy was used for morphology characterization and it revealed the existence of porous agglomerated round-shaped particles favorable for photocatalytic application. Energy Dispersive X-ray Spectroscopy showed the presence of dopant ions and even distribution of all constituting elements. Under simulated solar light irradiation, the photocatalytic characteristics of down-convertors were investigated in the photocatalytic degradation of organic dye methyl orange (MO). During the experiment, a UV/Vis spectrometer was utilized to measure a drop in MO concentration in water solutions. Aliquots of the working solutions were taken at precise time intervals, and the results show that the dye breakdown rate was successful after 4 hours. Methylene blue (MB), as a test pollutant, was used to investigate its photocatalytic efficiency under irradiation of simulated sunlight of up-conversion samples. The obtained results were encouraging because more than 50% of the starting dye concentration was mineralized after 4 hours of exposure to the simulated Sun irradiation.XI Serbian Ceramic Society Conference - Advanced Ceramics and Application : new frontiers in multifunctional material science and processing : program and the book of abstracts; September 18-20, 2023; Belgrad

Protokoli u klasifikaciji krezubosti

This paper shall discuss the importance of protocol application in modern dentistry. Literature data that include recommendations and consensuses in dental practice point out to their presence in available literature, printed papers, reviewed journals and supplements in the form of expert group conclusions. It should be noted that the protocols most commonly rely on valid postulates of different branches of medicine, supported by specific conditions of the environment in which they are implemented. Additionally, in our settings, applicable dentistry protocols are the result of requirements that institutions and practices should fulfill according to renewable accreditation, as well as following recommendations given in the good clinical practice guidelines with different binding obligations levels. Certain protocols offer therapeutic modalities categorized into classes intended to help users to select appropriate treatments. The second part of this paper shall address one such protocol which classifies partially edentulous patients. The emphasis is on the partial edentulism classification recommended by The American College of Prosthodontists (ACP), which relies on four diagnostic criteria essential for therapeutic decision. Edentulous areas location and extent, abutment teeth health, occlusion model, and residual ridge characteristics represent the parameters which have defined the four classes of partial edentulism of different complexity. In this way, comprehensive approach to the clinical status of the patients has, for the first time been offered to the dental practitioners assuring, among others, higher uniformity of professional attitudes in selection of therapeutic modalities.U radu se diskutuje o značaju primene protokola u savremenoj stomatologiji. Literaturni podaci koji obuhvataju preporuke i konsenzuse u stomatološkoj praksi govore o njihovoj prisutnosti u dostupnim knjigama, štampanim radovima u recenziranim časopisima, i dodacima časopisa kao zaključci ekspertskih grupa. Treba primetiti da su protokoli najčešće oslonjeni na validne postulate različitih medicinskih grana, pomognuti specifičnim uslovima sredine u koju se implementiraju. Dodatno, u našim uslovima, protokoli u stomatologiji su rezultat zahteva koje institucije i prakse moraju da ispunjavaju shodno obnovljivoj akreditaciji, kao i poštovanja preporuka koje su date u vodičima dobre kliničke prakse različitog nivoa obaveznosti. Pojedini protokoli nude terapijske modalitete koji se kategorizuju u klase, pomažući korisnicima u izboru pravog tretmana. O jednom od takvih protokola koji klasifikuje krezube pacijente govori drugi deo rada. Akcenat je na primeni klasifikacije krezubosti koju je preporučio Američki koledž protetičara, a koja se oslanja na četiri dijagnostička kriterijuma, bitna za terapijsku odluku. Lokalizacija i veličina bezubih polja, stanje zdravlja zuba nosača, model okluzije i karakteristike rezidualnog grebena su parametri koji su definisali četiri klase krezubosti različite složenosti. Tako je, prvi put, stomatološkoj praksi ponuđen ozbiljan, sveobuhvatni pristup kliničkom statusu bolesnika, koji obezbeđuje, između ostalog, i uniformnije stručne stavove u izboru terapijskih modaliteta

The Synthesis and Characterization of Yb3+ and Ho3+ Doped SrGd2O4

In this investigation, samples of SrGd2O4 doped with different concentration of Yb3+ (2, 4, 6 at%) ions and constant concentration of Ho3+ (1 at%) were prepared. As for synthesis we chose combustion method assisted with glycine as a fuel and citric acid as a chelator. All samples were burned in the furnace at 500 °C for 1.5h and afterwards additionally thermally treated for 2.5 h at 1000 °C. X-ray diffraction (XRD) showed peaks that correspond to the pure orthorhombic lattice of SrGd2O4, space group Pnma (JCPDS Card No.:01-072-6387). FE-SEM micrographs revealed agglomerated phenomenon with spherical shape and diameter around 200 nm. Energy dispersive X-ray spectroscopy (EDS) verified uniform distribution of all constituting elements in particles. Powders optical characterization include measurement of up-conversion (UC) emission spectra after excitation at 980 nm, as well as up-converted intensity dependence on excitation power. Dominant green emission 5F4, 5S2 → 5 I8 was found in all samples, with the most intense emission with 2 at% of Yb3+ and dependence of intensity of UC emission on excitation power confirmed that green emission is facilitated by energy transfer mechanism with two photons.COIN 2022 : Poster Session

Ispitivanje fotokatalitičkih osobina Er3+ i Yb3+ dopiranog nanopraha stroncijum-gadolinijum-oksida

Cilj ovog istraživanja je da se po prvi put ispita fotokatalitička razgradnja metilen plavog na prahovima SrGd2O4 dopiranim istom koncentracijom Er3+ (0.5 at%) i različitim koncentracijama Yb3+ (1, 2.5 and 5 at%). Difrakcija rendgenskim zracima potvrdila je da uzorci kristališu u čistoj ortorombičnoj fazi. Skenirajuća elektronska mikroskopija je korišćena za ispitivanje morfologije i pokazala je da postojanje poroznih aglomerata sačinjenih od manjih čestica sferičnog oblika. Energetski disperzivna spektroskopija pokazala je prisustvo dopanata kao i uniformnu raspodelu svih elemenata u materijalu. Za izračunavanje energetskog procepa korišćena je metoda UV-VIS difuzione refleksione spektroskopije, kojom je dobijena vrednost od 4,3 eV, kao i još četri dodatne vrednosti na nižim energijama. Fotokatalitička razgradnja metilen plavog praćena je metodom UV-VIS apsorpcione spektroskopije. Dobijeni su zadovoljavajući rezultati jer je pri određenim reakcionim uslovima nakon eksperimenta u trajanju od 4 h pod dejstvom simulirane sunčeve svetlosti, potvrđena razgrađnja više od 50% od ukupne početne koncentracije boje

Antigenotoxic effects of royal jelly in the sex linked recessive lethal test with Drosophila melanogaster

The antitoxic and antimutagenic effect of royal jelly was assayed by a standard testing procedure on Drosophila melanogaster. The similarity of metabolic pathways between Drosophila and mammals makes the test widely applicable for detecting the impact of various potential promutagens and antimutagenic effects could be recognized accordingly. The flies were treated with the potent mutagen MMS, alone and combined with royal jelly. The frequency of sterile males and sex linked recessive lethal mutations increased significantly after MMS treatment and decreased after combined treatment. The results strongly indicate that, in addition to its well documented action on development, life-span and reproductive ability, royal jelly has an antimutagenic potential as well.Antigenotoksični i antimutageni efekat pčelinjeg mleča ispitivan je korišćenjem standardne procedure testiranja pomoću Drosophilae melanogaster. Sličnost metaboličkih puteva između Drosophila i sisara čini ovaj test široko primenljivim u otkrivanju uticaja različitih potencijalnih mutagena i promutagena, a analogno tome se može ispitivati i mogući antimutageni potencijal substanci. Mušice odgovarajućeg genotipa tretirane su jakim mutagenom, metil-metan-sulfonatom (MMS), samostalno i u kombinaciji sa mlečom. Učestalost sterilnih mužjaka i polno vezanih recesivnih letalnih mutacija rasla je značajno nakon tretmana sa MMS i opadala nakon kombinovanog tretmana. Dobijeni rezultati značajno ukazuju da uz već potvrđeni uticaj na razviće, dužinu života i reproduktivnu sposobnost, mleč ima i antimutageni potencijal.Projekat ministarstva br. 152

Yb3+/Tm3+ doped SrGd2O4 as photoluminescent and photocatalytic material

In this work we present new up-conversion materials, consisted of SrGd2O4 doped with different concentration of Yb3+ (2, 4, 6 at%) ions and constant concentration of Tm3+ (1 at%), prepared by the combustion method. X-ray powder diffraction (XRPD) showed that assynthesized nanoparticles have orthorhombic structure (Pnma), assigned to the JCPDS Card No:01-072-6387. Scanning electron microscopy (SEM) revealed that obtained nanostructure is composed of porous agglomerated nanoparticles, while energy dispersive spectroscopy (EDS) confirmed presence and uniform distribution of all constituting elements accross the sample. Luminescent properties were evaluated and discovered two blue emission bands at 450 nm and 474 nm, and one red emission band at 650 nm. The sample co-doped with 4 at% Tm3+ showed the most intense photoluminescent emission, and because of that was used in the photocatalytic exiperiment. UV-VIS Diffuse Reflectance Spectroscopy was performed in order to examine materials bandgap, and value of 4.3 eV was obtained as well as the additional values from the bands at lower energies, which indicate potentially good photocatalytic properties. X-ray photoelectron spectroscopy (XPS) revealed presence of OHgroups on the surface which also have positive impact on the photocatalytic performances of the material. UV-VIS Absorption Spectroscopy was used to measure changes of the methylene blue concentration during the photocatalytic degradation process. After 4 h of exposure to the simulating Sun irradiation, the results indicate successful dye decomposition rate. Reaction parameters (MB concentration and catalyst mass) were altered in order to achieve the best photocatalytic performances of this newly synthesized materials.Twenty-First Young Researchers’ Conference - Materials Science and Engineering: Program and the Book of Abstracts; November 29 – December 1, 2023, Belgrade, Serbi

Determination of phenol content and antioxidant activity of leek (Allium Porrum L.) extract

From molecules to Functionalised Materials : Intensive Lecture Course : March 16-20, Skopje, Republic of Macedonia, 2011

Influence of host lattice on luminescence properties of up-conversion Ln2MoO6 (Ln=Y, Gd) powders co-doped with Er3+/Yb3+ synthesized at high temperatures

Luminescent materials emit radiation when exposed to various types of excitation (ultraviolet radiation, X-rays, electron beam, etc.) and can be comprised of a host lattice with dopant as an activator. One of the extensively investigated luminescent materials is monoclinic Ln2 MoO6 due to its high thermal stability. In this study, we investigated Ln2MoO 6 with different concentrations of Er 3+ /Yb3+ concentrations synthetized at temperatures up to 1200o C. The obtained powders were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence spectroscopy (PL). The results revealed that all powders are single phase Ln2 MoO6 , with particle size in the nano range at lower treatment temperatures (up to 800 o C) and in the micro range at higher calcination temperatures (up to 1200 o C). Both Y 2 MoO 6 :Yb3+ /Er 3+ and Gd2 MoO 6 : Yb3+ /Er 3+ show double emitting luminescence two green emission bands at 525 and 546 nm (2 H 11/2 , 4 S 3/2 → 4 I 15/2 ) as well as a red emission band at 657 nm ( 4 F 9/2 → 4 I 15/2 ). It can be concluded that increase of Yb3+ concentration leads to change of the green to red ratio showing the ability for fine-tuning of the color output.IMEC2022 - 1st International Conference on Innovative Materials in Extreme Conditions, 22-23 March 2022, Belgrade, Serbi

Influence of Yb3+ concentration on structural and luminescent properties of Tm3+ doped SrGd2O4

Here, samples of SrGd2O4 doped with different concentration of Yb3+ (2, 4, 6 at.%) ions and constant concentration of Tm3+ (1 at.%) were prepared. For preparation of samples, combustion method assisted with glycine as a fuel and citric acid as a chelator was chosen. All samples were heated in the furnace at 500 °C for 1.5 h and additionally thermally treated for 2.5 h at 1000 °C. X-ray diffraction (XRD) revealed that all peaks are assigned to the pure orthorhombic lattice of SrGd2O4, space group Pnma (JCPDS Card No.:01-072-6387). Field emission scanning electron microscopy (FE-SEM) showed agglomerated spherical particles with size around 150 nm. Energy dispersive spectroscopy confirmed uniform distribution of constitutive elements through the samples. Up-conversion emission properties were evaluated from photoluminescent emission spectra and intensity dependence on excitation power after excitation at 980 nm. Dominant blue emission with appropriate transition 1G4 → 3H6 is detected in all samples, for which three photons are required.VI Serbian Ceramic Society Conference : program and the book of abstracts; June 28-29, 2022; Belgrad

Photocatalytic application of SrGd2O4 nanoparticles doped with rare earth

Program and book of abstracts / 2nd International Conference on Innovative Materials in Extreme Conditions i. e. (IMEC2024), 20-22 March 2024 Belgrade, Serbia