Ivana Zekovic

Ivana Zekovic
University of Belgrade · Vinca Institute of Nuclear Science

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34
Publications
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537
Citations

Publications

Publications (34)
Article
Phosphors for luminescence thermometry La 1− x Ga 0.99 O 3 :Cr 0.01 , Nd x were synthesised by the solid-state method, structurally characterised using powder X-ray diffraction data, and investigated by ambient and variable-temperature optical measurements.
Article
The introduction of additional functionalities to materials is exceptionally important as it opens new applications for them. Aluminum, one of the most abundant and important materials, is coated with luminescent Sm2+‐doped γ‐aluminium oxide to impart thermometric functionality. Considering the potential industrial applications, two of the most wid...
Article
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A promising way to improve the performance of luminescent materials is to combine them with noble metal nanoparticles. Herein, a set of silver/europium-doped lanthanum orthophosphate (Ag/La 0.95 Eu 0.05 PO 4) nanostructures with different concentrations of silver nanoparticles were prepared and investigated. The presented overlap between the strong...
Article
The Judd-Ofelt model, already verified for the luminescence intensity ratio (also called fluorescence intensity ratio, FIR) thermometry from the emission spectra, is modified and tested for the double-excitation (also called ground-state-absorption, GSA) thermometry. The adapted model has been tested on Lu2O3:Eu³⁺, with a 99.9% match of the tempera...
Article
When activated by Dy3+, Na0.25K0.25Bi0.50TiO3 (NKBT), piezoelectric powders show strong luminescence in the blue and yellow spectral range. Emissions of this material can be effectively utilized for both luminescence intensity ratio and lifetime-based readouts of temperature. Photoluminescence measurements over a temperature range of 293–483 K show...
Article
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The emission of Er 3+ provides three combinations of emission bands suitable for ratiometric luminescence thermometry. Two combinations utilize ratios of visible emissions (2 H 11/2 → 4 I 15/2 at 523 nm/ 4 S 3/2 → 4 I 15/2 at 542 nm and 4 F 7/2 → 4 I 15/2 at 485 nm/ 4 S 3/2 → 4 I 15/2 at 545 nm), while emissions from the third combination are locat...
Article
Full-text available
Fluorescence excitation-emission matrices were measured for 111 samples of different types of beer and studied by the parallel factor analysis (PARAFAC). The 5-component PARAFAC model was found to suitably describes the beer fluorescence, accounting for 99.4% of the fluorescence variance in the measured set of samples, and providing the completely...
Article
The interaction of partially reduced graphene oxide (prGO) and Huh7.5.1 liver cancer cells was investigated by means of DUV fluorescence bioimaging. The prGO sample was obtained by the reduction (to a certain extent) of the initially prepared graphene oxide (GO) nanosheets with hydrazine. The fluorescence of the GO nanosheets increases with time of...
Article
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Honey is a frequent target of adulteration through inappropriate production practices and origin mislabelling. Current methods for the detection of adulterated honey are time and labor consuming, require highly skilled personnel, and lengthy sample preparation. Fluorescence spectroscopy overcomes such drawbacks, as it is fast and noncontact and req...
Chapter
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Parallel factor analysis (PARAFAC) of food fluorescence has found many applications in food science, such as in non-contact and non-destructive food characterization, the detection of food adulteration, and the authentication of geographical and botanical origins of food products. This Chapter presents a theoretical background of the PARAFAC method...
Article
This paper presents parallel factor analysis (PARAFAC) of fluorescence of cereal flours. Excitation-emission matrices (EEM’s) of different cereal flours (wheat, corn, rye, rice, oat, spelt, barley and buckwheat) were measured in a front-face configuration over the ultraviolet–visible spectral range. EEM’s showed that flours strongly fluoresce in tw...
Article
Full-text available
Objective: The aim of this study was to evaluate changes of color and fluorescence of resin based composite exposed to beer. Materials and methods: 84 samples (13 mm in diameter and 1.5 mm thick) of microhybrid composite Gradia Direct(TM) extra bleach white were immersed in 5 different beers (dark and light) or distilled water. Color and fluores...
Article
The paper presents the results of the experimental and theoretical study of 3,3′-disulfopropyl-5,5′-dichlorothiacyanine sodium salt (TC) adsorption and J-aggregation on the surface of citrate-capped silver nanoparticles (AgNPs) with an average particle size 10 nm. Various nanospectroscopy techniques such as UV-vis, TEM, AFM, DLS, ζ potential, and f...
Article
Objective The aim of this study was to evaluate changes of color and fluorescence of resin based composite exposed to beer. Materials and Methods 84 samples (13 mm in diameter and 1.5 mm thick) of microhybrid composite Gradia DirectTM extra bleach white were immersed in 5 different beers (dark and light) or distilled water. Color and fluorescence...
Article
Full-text available
Fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC) and Partial least squares Discriminant Analysis (PLS DA) were used for characterization and classification of honey. Excitation emission spectra were obtained for 95 honey samples of different botanical origin (acacia, sunflower, linden, meadow, and fake honey) by recording e...
Article
Full-text available
In recent years, the potential of Fourier-transform infrared spectroscopy coupled with different chemometric tools in food analysis has been established. This technique is rapid, low cost, and reliable and requires little sample preparation. In this work, 130 Serbian unifloral honey samples (linden, acacia, and sunflower types) were analyzed using...
Article
Full-text available
Novel optical spectroscopy and imaging methods may be valuable in the early detection of cancer. This paper reports differences in the luminescence responses of pigmented skin lesions (melanomas and nevi) and apparently normal non-pigmented human skin, based on analyses of synchronous luminescence spectroscopy measurements. Measurements were perfor...
Article
Front-face synchronous fluorescence spectroscopy combined with chemometrics is used to classify honey samples according to their botanical origin. Synchronous fluorescence spectra of three monofloral (linden, sunflower, and acacia), polyfloral (meadow mix), and fake (fake acacia and linden) honey types (109 samples) were collected in an excitation...
Article
In this study, the thermal behavior of modified urea-formaldehyde (UF) resin with nanosilica (nano-SiO2), wood flour (WF), and their mixture of SiO2/WF was investigated. Five modified UF hybrid composite materials with 0.8 F/U ratio with different filler were synthesized using the same procedure. The thermal behavior of materials was studied using...
Article
Full-text available
Opalized white tuff (OWT) with 40 μ m average particle size and 39.3 m(2)/g specific surface area has been introduced into polyisoprene rubber (NR). Their reinforcing effects were evaluated by comparisons with those from precipitated silica (PSi). The cure characteristic, apparent activation energy of cross-link (E ac) and reversion (E ar), and mec...
Article
Full-text available
Over the years various optical spectroscopic techniques have been widely used as diagnostic tools in the discrimination of many types of malignant diseases. Recently, synchronous fluorescent spectroscopy (SFS) coupled with chemometrics has been applied in cancer diagnostics. The SFS method involves simultaneous scanning of both emission and excitat...
Article
Full-text available
Synchronous fluorescence spectroscopy, a technique that measures both the absorption and the emission properties of a sample in a single measurement, was used for the analysis and classification of intact cereal flours (wheat, corn, rye, buckwheat, rice, and barley). Total synchronous fluorescence spectra recorded in constant wavelength mode show c...
Article
Full-text available
Excitation-emission matrices (EEM) and total synchronous fluorescence spectra (SFS) of normal and malignant breast tissue specimens are measured in UV-VIS spectral region to serve as data inputs in development of Support Vector Machine (SVM) based breast cancer diagnostics tool. Various input data combinations are tested for classification accuracy...
Article
Full-text available
Fluorescence excitation-emission spectroscopy was used to investigate specimens of normal and malignant human breast tissues. Measurements were performed in two spectral regions: in the excitation range from 335nm to 400nm and emission range from 430nm to 625 nm, and in the excitation range from 400nm to 470nm and emission range from 500nm to 640 n...
Article
In this work we explored the possibility of obtaining nanocrystalline (Y0.5Lu0.5)2O3 powders, doped with europium and co-doped with praseodium, employing polymer complex solution synthesis. Polyethylene glycol, with average molecular weight 200, served both as a fuel and dispersing medium for nanocrystals formation. We investigated structure, morph...
Article
In this work we explored the possibility of obtaining nanocrystalline (Y 0.5 Lu 0.5) 2 O 3 powders, doped with europium and co-doped with praseodium, employing polymer complex solution synthesis. Polyethylene glycol, with average molecular weight 200, served both as a fuel and dispersing medium for nanocrystals formation. We investigated structure,...
Article
Full-text available
Supervised self-organizing map, a type of artificial neural network, is applied for classification of human breast tissue samples utilizing data obtained from fluorescence landscape measurements. Female breast tissue samples were taken soon after the surgical resection, identified and stored at -80 °C until fluorescence measurements. From fluoresce...
Article
The synthesis of nanophosphors for various applications and the improvement of their working parameters constitute one of the most topical problems of nowadays technology. Zinc-silicate has been extensively used as host material for phosphors in cathode ray tubes, and nowadays for phosphors in electroluminescent devices. In this work we present nov...
Article
Full-text available
The synthesis of nanophosphors for various applications and the improvement of their working parameters constitute one of the most topical problems of nowadays technology. Zinc-silicate has been extensively used as host material for phosphors in cathode ray tubes, and nowadays for phosphors in electroluminescent devices. In this work we present nov...
Article
The synthesis of nanophosphors for various applications and the improvement of their working parameters constitute one of the most topical problems of nowadays technology. Zinc-silicate has been extensively used as host material for phosphors in cathode ray tubes, and nowadays for phosphors in elec-troluminescent devices. In this work we present no...
Article
Full-text available
Investigation done on Y2SiO5 nanoparticles doped with Eu3+ ions obtained with the alkoxy sol-gel route is presented in this paper. We investigate the optical and thermal properties of obtained material during the conversion of the gel into nanocrystalline form. Fourier transform infrared spectroscopy and fluorescence spectroscopy of Eu3+ ions are u...
Conference Paper
Full-text available
Investigation done on Y(2)SiO(5) nanoparticles doped with Eu(3+) ions obtained with the alkoxy sol-gel route is presented in this paper. We investigate the optical and thermal properties of obtained material during the conversion of the gel into nanocrystalline form. Fourier transform infrared spectroscopy and fluorescence spectroscopy of Eu(3+) io...

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