Playfulness in adulthood has been shown to be un-researched scientific issue. We believe that it is because of earlier non-recognition of this issue as a special field of study, but also the ...existence of a popular belief that the playful activities are reserved only for children. Just because of the lack of initiative and coherent researches that take into account playful activities in adulthood and characteristic of playfulness as a personal trait this research can be considered as the first research of that kind in the Republic of Serbia. The aim of this research is to determine adult perceptions of their playfulness and dominant cognitive qualities of playfulness. Adult Playfulness Trait Scale was used (APTS, Shen, Chick & Zin, 2014) to explore adult playfulness and inherent cognitive characteristic of this personal trait. Research sample consists of 1234 adult individuals aged from 18 to above 60 years from a cities and villages of Serbian area. The results of this research show that respondents recognize and highly value all tree sub-dimensions of playfulness trait: fun-seeking motivation, uninhibitedness and spontaneity. An important finding of this research is one that indicates on the characteristics of fun-seeking motivation sub-dimension as dominant one.
Lanthanide‐doped vanadate thin films offer (i) a promising platform for luminescence‐based noncontact temperature sensing; (ii) ratiometric/self‐referencing absolute measurements; (iii) exceptional ...repeatability and reversibility for multirun uses and a long life cycle; (iv) 2% K−1 maximum temperature sensitivity (among the highest recorded for inorganic nanothermometers); (v) a temperature resolution greater than 0.5 K; and (vi) the potential for high‐resolution 2D temperature mapping.
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•Er3+/Yb3+ co-doped GdVO4 nanocrystalline powder was prepared.•The nanocrystals were calibrated with the temperature based on fluorescence intensity ratio and lifetime.•Temperature ...calibration with fluorescence intensity ratio have higher relative sensitivity than the one based on lifetime.•The nanocrystals were used to monitor the temperature of an integrated circuit when operating and not.
The temperature sensing properties of an Er3+/Yb3+ co-doped GdVO4 nanocrystalline powder were studied. The down-conversion emission spectrum of the sample was observed under excitation at 457 nm. Two methods were used to calibrate the temperature of the sample: one based on the Fluorescence Intensity Ratio (FIR) technique and the other using the fluorescence lifetime of the thermally-coupled energy levels of Er3+. The relative sensitivities for each method were calculated and it was found out that the FIR-based temperature sensor has higher sensitivity (1.17% K−1) than the lifetime-based sensor (0.24% K−1). Furthermore, a temperature uncertainty of 0.37 K was obtained for the FIR-based sensor. The GdVO4 nanoparticles were also used to study the change in temperature of an electrical component when it is operating and not.
Photoactive materials called photosensitizers can be used for treatment of different types of cancer in combination with light source. In this paper, we have investigated pro-oxidant and antioxidant ...potentials of four graphene based nanomaterials (graphene oxide-GO, graphene quantum dots-GQDs, carbon quantum dots-CQDs and N-doped carbon quantum dots-N-CQDs) depending on the presence/absence of visible light source. Structural and optical properties of these materials and their potentials for reactive oxygen species generation/quenching are investigated by applying different microscopy and spectroscopy techniques (transmission electron microscopy, FTIR, UV–Vis, photoluminescence, electron paramagnetic resonance). Results show that all types of quantum dots has pro-oxidant and antioxidant potentials whereas GO demonstrated only moderate antioxidant effect. The best free radical scavenger is CQDs sample in the absence of light. CQDs are the best singlet oxygen generator under blue light irradiation as well. To check photo-cytotoxicity of these materials, photo-cytotoxic concentrations of the GO, GQDs, CQDs and N-CQDs were determined for three cellular lines: human rhabdomyosarcoma (RD), cell line derived from human cervix carcinoma Hep2c (HeLa) and fibroblast cell line from murine (L2OB). Cytotoxicity test has indicated that all samples are much less photocytotoxic than cis-diamminedichloroplatinum (cis-DPP). The production method and doping of quantum dots affect the photodynamic activity of tested samples very much.
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•Graphene oxide size and structure materials.•Crossover between pro-oxidant and antioxidant activities.•Fullerene like structure affects ROS generation/quenching.•Blue light dependent cytotoxicity toward cancer cells.
Herein, fine powders of yellow pigments based on BiVO4 were successfully prepared in two crystalline forms, tetragonal zircon-structured and monoclinic scheelite-structured, through a ethylene ...glycol-assisted method subjected to a thermal treatment at two different temperatures. The obtained materials were brightly colored with different hues of yellow, exhibited high reflection in the near-infrared region and showed visible luminescence under excitation by UV light. The new preparation method had a considerable effect on chromatic properties of the prepared scheelite-structured BiVO4 pigments. The sample with the most vivid and bright shade of yellow was found to have the L*a*b* and L*C*ab h*ab color coordinates of (87.28, 0.37, 91.53) and (87.28, 91.53, 89.79), which are indicative of exceptionally good chromatic properties superior and/or comparable to those of other inorganic yellow pigments, both commercially available and recently described. In addition, the NIR reflectance of this powder was very high (≥ 80%).
Nonaqueous reactions between titanium(IV) chloride and alcohols (benzyl alcohol or n-butanol) were used for the synthesis of anatase TiO2 particles, while rutile TiO2 particles were synthesized in ...aqueous media by acidic hydrolysis of titanium(IV) chloride. The X-ray diffraction measurements proved the exclusive presence of either the anatase or the rutile phase in prepared samples. The photoluminescence of both kinds of particles (anatase and rutile) with several well-resolved peaks extending in the visible spectral region was observed, and the quantum yield at room temperature was found to be 0.25%. Photon energy up-conversion from colloidal anatase and rutile TiO2 particles was observed at low excitation intensities. The energy of up-converted photoluminescence spans the range of emission of normal photoluminescence. The explanation of photon energy up-conversion involves mid-gap energy levels originating from oxygen vacancies.
This paper provides the detailed study of (nano)particle's size effect on structural and luminescent properties of LaPO4:Eu3+ synthesized by four different methods: high temperature solid-state, ...co-precipitation, reverse micelle and colloidal. These methods delivered monoclinic monazite-phase submicron particles (> 100nm), 4 × 20nm nanorods and 5nm spheres (depending on the annealing temperature), 2 × 15nm nanorods, and ultra-small spheres (2nm), respectively. The analysis of emission intensity dependence on Eu3+ concentration showed that quenching concentration increases with a decrease of the particle size. The critical distance for energy transfer between Eu3+ ions is found to be 18.2Å, and the dipole-dipole interaction is the dominant mechanism responsible for the concentration quenching of emission. With the increase in Eu3+ concentration, the unit-cell parameter slightly increases to accommodate larger Eu3+ ions at sites of smaller La3+ ions. Photoluminescent emission spectra presented four characteristic bands in the red spectral region: at 592nm (5D0→7F1), at 612nm (5D0→7F2), at 652nm (5D0→7F3) and at 684nm (5D0→7F4), while in small colloidal nanoparticles additional emission bands from host defects appear at shorter wavelengths. Intensities of f-f electronic transitions change with particles size due to small changes in symmetry around europium sites, while emission bandwidths increase with the reduction of particle size due to increased structural disorder. Judd-Ofelt analysis showed that internal quantum yield of Eu3+ emission is strongly influenced by particle's morphology.
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Defect-fluorite structured Eu3+-doped Y2Sn2O7 nanoparticles (30–40 nm) were successfully prepared through a facile co-precipitation method without any organic additives or templates followed by ...calcination in air. Luminescent properties of the as-prepared Y2-xEuxSn2O7 (0.02 ≤ x ≤ 0.6) nanophosphors were fully characterized from an experimental and theoretical point of view (excitation, emission, lifetime, critical concentration, temperature-dependent luminescence and thermal stability, type of interactions and the Judd-Ofelt analysis). The nanophosphors showed relatively sharp excitation bands from 360 to 530 nm and exhibited characteristic emission bands with the most intensive emission centered at 612 nm. In addition, Gd1.98Eu0.02Sn2O7 and Lu1.98Eu0.02Sn2O7 samples were prepared in order to study how substitution of RE3+ (Y3+ with Gd3+ and Lu3+ ions) influences on luminescent properties of RE1.98Eu0.02Sn2O7 and thermal stability of their luminescence. In order to understand better luminescent properties, the Judd–Ofelt analysis was applied to all the synthesized powders. The highest value of quantum efficiency, ~96%, was estimated for Lu1.98Eu0.02Sn2O7. To assess potential application in high-power LEDs, the temperature-dependent emission spectra of Y1.98Eu0.02Sn2O7, Gd1.98Eu0.02Sn2O7 and Lu1.98Eu0.02Sn2O7 nanophosphors were studied.
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•Eu3+-doped Y2Sn2O7, Gd2Sn2O7, Lu2Sn2O7 samples were prepared by co-precipitation method.•An average size of all synthesized samples were ranging from 30 to 40 nm.•The highest value of quantum efficiency (QE~96%) was obtained for Lu1.98Eu0.02Sn2O7.•The color coordinates of studied samples are close to commercial red phosphor.•Samples showed good thermal stability in the range of operating WLED temperatures.
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•Li+ co-doped powders have larger crystallite size and smaller lattice parameters.•Ho3+/Yb3+-doped GdVO4 exhibits dominant green DC emission.•Ho3+/Yb3+-doped GdVO4 exhibits dominant ...red UC emission.•7.5mol% Li+ co-doping results in more than double DC emission intensity.•10mol% Li+ co-doped powder enhances UC emission intensity by 2.2times.
We present the structural and luminescent properties of Ho3+/Yb3+-doped GdVO4 and Li+-co-doped GdVO4:Ho3+/Yb3+ powder phosphors. The materials were prepared by high-temperature solid state method with different concentrations (between 0.5 and 2mol%) of dopant Ho3+ emitting ions and different concentrations (between 5 and 20mol%) of sensitizer Yb3+ ions. The dopant ions provided the material with intense luminescence emission; green emissions (centered at 542nm from 5F4,5S2→5I8 electronic transition of Ho3+ ions) resulted upon ultraviolet excitation, and red (centered at 659nm from 5F5→5I8 electronic transition of Ho3+ ions) upon near-infrared excitation. The co-doped materials were obtained under identical experimental conditions by adding Li+ ions (5, 7.5, 10, and 15mol%). The powders co-doped with 7.5mol% Li+ ions showed a downconversion emission intensity more than twice as high as the samples without Li+ co-doping. In upconversion, an equal intensification of emission was achieved with co-doping with 10mol% Li+. The influences of Ho3+/Yb3+ concentration ratio and Li+ co-doping level on emission color and emission branching was investigated and analyzed for both downconversion and upconversion emission. Increasing Yb3+ concentration was found to increase the share of dominant emission (green) in downconversion, but decreased the share of dominant emission (red) in upconversion.
Synthesis of Eu(3+)- and Er(3+)/Yb(3+)-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol ...as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu(3+)-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er(3+)/Yb(3+)-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from (2)H11/2 → (2)I15/2 and (4)S3/2 → (4)I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K(-1), which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers.
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