Single Er3+, Yb3+: KGd3F10 Nanoparticles for Nanothermometry

Among several optical non-contact thermometry methods, luminescence thermometry is the most versatile approach. Lanthanide-based luminescence nanothermometers may exploit not only downshifting, but also upconversion (UC) mechanisms. UC-based nanothermometers are interesting for biological applications: they efficiently convert near-infrared radiation to visible light, allowing local temperatures to be determined through spectroscopic investigation. Here, we have synthesized highly crystalline Er3+, Yb3+ co-doped upconverting KGd3F10 nanoparticles (NPs) by the EDTA-assisted hydrothermal method. We characterized the structure and morphology of the obtained NPs by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and dynamic light scattering. Nonlinear spectroscopic studies with the Er3+, Yb3+: KGd3F10 powder showed intense green and red emissions under excitation at 980 and 1,550 nm. Two- and three-photon processes were attributed to the UC mechanisms under excitation at 980 and 1,550 nm. Strong NIR emission centered at 1,530 nm occurred under low 980-nm power densities. Single NPs presented strong green and red emissions under continuous wave excitation at 975.5 nm, so we evaluated their use as primary nanothermometers by employing the Luminescence Intensity Ratio technique. We determined the temperature felt by the dried NPs by integrating the intensity ratio between the thermally coupled H-2(11/2)-> I-4(15/2) and S-4(3/2)-> I-4(15/2) levels of Er3+ ions in the colloidal phase and at the single NP level. The best thermal sensitivity of a single Er3+, Yb3+: KGd3F10 NP was 1.17% at the single NP level for the dry state at 300 K, indicating potential application of this material as accurate nanothermometer in the thermal range of biological interest. To the best of our knowledge, this is the first promising thermometry based on single KGd3F10 particles, with potential use as biomarkers in the NIR-II region

A natureza e fins das contraordenações fiscais

Mestrado em FiscalidadeDesde os registos mais antigos que os tributos surgem como uma fonte de receita, cujo contributo se destinava à proteção e progressão dos povos. Na Idade Média, os vassalos pagavam altos tributos aos senhores feudais, com o intuito de ver garantida a sua segurança e subsistência em caso de guerra, bem como a possibilidade da progressão do feudo onde todos habitavam. Numa perspetiva pessoal, o atual Estado Português pode ser considerado um Puro Estado Fiscal, dado que se encontra cada vez mais dependente da receita fiscal para garantir a subsistência do seu circuito económico. Deste modo, e tendo em consideração esta dependência, a Autoridade Tributária não deve deixar impune quem, na sua perfeita idoneidade cívica, moral ou profissional, seja incumpridor das suas obrigações para com o Fisco Português, ou ainda quem, por recurso a atos menos lícitos, procure induzir a redução do seu dever contributivo, através do não pagamento dos tributos devidos aos cofres do Estado. Tendo como horizonte de atuação a Constituição da República Portuguesa, todos os cidadãos de um Estado livre, sejam eles contribuintes ou não, dispõem de direitos e deveres. Salienta-se o dever de contribuir, através do pagamento dos respetivos tributos. O incumprimento dos deveres fiscais, previstos nos códigos tributários, originará infrações fiscais que, consoante a sua natureza, e tipologias quantitativas, serão consideradas contraordenacionais ou criminais, estando todos sujeitas a punições diversas: multas, coimas, sanções acessórias ou penas de prisão.Since the begining of the civilazations, taxes always presented a source of revenue intended for the protection and progression of the peoples. In the Middle Ages, the vassals paid taxes to their feudal lords, with the intention that they would guarantee their security and subsistence in case of war, together, with the responsability of the progression of the land where all of them lived. Currently, the Portuguese State, in my opinion, could be considerate, a pure Tax State, given that, it´s increasingly dependent of the Tax Revenue to guarantee the subsistence of it´s economic circuit. In this way, and taking account the financial Fiscal State dependence, the Tax Authority can´t leave unpunished those who, in their perfect suitability, breach their fiscal obligations towards the Portuguese Tax Authority, or who, through recourse to acts less legals, try to induce the reduction of their tax liability, through non-payment of taxes due to the state coffers. Taking into account the Constitution of the Portuguese Republic, all people of a Free State, whether as citizens or taxpayers, have rights and duties, being one of the most important constitutional duty, the contribution through the payment of their taxes. Failure with tax obligations, provided in the tax law codes, should result in tax offenses which, depending of the nature of their acts, and their typologies, will be considered as non-criminal or criminal, being all subject to punishment from fines, ancillary sanctions or even imprisonment.info:eu-repo/semantics/publishedVersio

Optimal scheduling of industrial combined heat and power plants under time-sensitive electricity prices

This work reports on the infrared-to-visible CW frequency upconversion from planar waveguides based on Er3+-Yb3+-doped 100-xSiO(2)-xTa(2)O(5) obtained by a sol-gel process and deposited onto a SiO2-Si substrate by dip-coating. Surface morphology and optical parameters of the planar waveguides were analyzed by atomic force microscopy and the m-line technique. The influence of the composition on the electronic properties of the glass-ceramic films was followed by the band gap ranging from 4.35 to 4.51 eV upon modification of the Ta2O5 content. Intense green and red emissions were detected from the upconversion process for all the samples after excitation at 980 nm. The relative intensities of the emission bands around 550 nm and 665 nm, assigned to the H-2(11/2) -> I-4(15/2), S-4(3/2) -> I-4(15/2), and F-4(9/2) -> I-4(15/2) transitions, depended on the tantalum oxide content and the power of the laser source at 980 nm. The upconversion dynamics were investigated as a function of the Ta2O5 content and the number of photons involved in each emission process. Based on the upconversion emission spectra and 1931CIE chromaticity diagram, it is shown that color can be tailored by composition and pump power. The glass ceramic films are attractive materials for application in upconversion lasers and near infrared-to-visible upconverters in solar cells.FAPESPFAPESPCAPESCAPESCNPqCNP

Unusual broadening of the NIR luminescence of Er3+-doped Nb2O5 nanocrystals embedded in silica host: Preparation and their structural and spectroscopic study for photonics applications

This paper reports on the preparation of novel sol-gel erbium-doped SiO2-based nanocomposites embedded with Nb2O5 nanocrystals fabricated using a bottom-up method and describes their structural, morphological, and luminescence characterization. To prepare the glass ceramics, we synthesized xerogels containing Si/Nb molar ratios of 90:10 up to 50:50 at room temperature, followed by annealing at 900, 1000, or 1100 degrees C for 10 h. We identified crystallization accompanying host densification in all the nanocomposites with orthorhombic (T-phase) or monoclinic (M-phase) Nb2O5 nanocrystals dispersed in the amorphous SiO2 phase, depending on the niobium content and annealing temperature. A high-intensity broadband emission in the near-infrared region assigned to the I-4(13/2) --> I-4(15/2) transition of the Er3+ ions was registered for all the nanocomposites. The shape and the bandwidth changed with the Nb2O5 crystalline phase, with values achieving up to 81 nm. Er3+ ions were located mainly in Nb2O5-rich regions, and the complex structure of the different Nb2O5 polymorphs accounted for the broadening in the emission spectra. The materials containing the T-phase, displayed higher luminescence intensity, longer I-4(13/2) lifetime and broader bandwidth. In conclusion, these nanostructured materials are potential candidates for photonic applications like optical amplifiers and WDM devices operating in the S, C, and L telecommunication bands. (C) 2014 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

A technique to produce thin cucurbit[6]uril films

We report a methodology to obtain thin films of cucurbit[6]uril, starting from ammoniacal solutions. This technique is very useful for the obtention of modified electrodes or other substrates for sensor purposes. Cucurbit[6]uril is insoluble in most media, and film formation was impossible until now

Color tunability in green, red and infra-red upconversion emission in Tm3+/Yb3+/Ho3+ co-doped CeO2 with potential application for improvement of efficiency in solar cells

The preparation of Tm3+/Yb3+/Ho3+ co-doped CeO2 prepared by the precipitation method using ammonium hydroxide as a precursor is presented. By X-ray diffraction the materials show the phase-type of fluorite structure and the crystallite sizes were calculated by the Scherrer's equation. No other phase was observed evincing that the rare earth ions were inserted into the fluorite phase as substitutional or interstitial dopants. The microstrain calculated by the Williamson-Hall method do not show significant changes in their values, indicating that the inclusion of rare earths does not causes structural changes in the CeO2 used as a host matrix. All material showed intense upconversion emission at red and green region under excitation with diode laser at 980 nm. The color of emission changes from green to red with increasing excitation power pump. The materials showed suitable photoluminescent properties for applications as a laser source, solar cells, and great emitter at 800 nm. (C) 2014 Elsevier B.V. All rights reserved

Spherical-shaped Y2O3:Eu3+ nanoparticles with intense photoluminescence emission

Herein we report on the crystallized nanoparticles based on Eu3+-doped Y2O3 with 5 mol% using citric acid as precursor. The heating temperatures were evaluated in order to obtain the best crystallized nanoparticles with size around 12 nm and with highest red intense photoluminescence emission. Nanocrystallite size was calculated by Scherrer's equation based on diffractogram of the material heated at 750 degrees C for 4 h, obtaining size around 8 nm. The low photoluminescence intense emissions were attributed to the presence of quenchers remaining from precursors used in the synthesis. In general the photoluminescence properties were evaluated based on emission and excitation spectra profile. Rietveld refinement was performed based on the diffractogram of the material annealed at 750 degrees C for 4 h, and the visualization of the cubic structure was obtained. The centered cubic crystalline structure of Y2O3 was obtained and the photoluminescence properties of Eu3+ ion in Y2O3 host lattice was verified as being dependent on the temperature of heating and C-2 and S-6 site of symmetry present in the cubic structure. CIE chromaticity diagram was obtained with x and y being 0.682 and 0.316, respectively, for material with the highest relative photoluminescence intensity. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq