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Made available in DSpace on 2019-10-06T17:07:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-06-01 Made available in DSpace on 2019-10-06T17:07:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-06-01 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) Polymeric matrices containing luminescent particles find many applications like temperature sensor platforms. However, it is important to understand the impact of the particle immobilization on the polymer structural and optical properties in order to optimize its performance. Therefore, in this study, a new luminescent polymeric composite was fabricated by combining poly (vinylidene fluoride) (PVDF), buriti oil (BO) and Eu2O3 particles, evaluating the membrane luminescent properties before and after a cryo-treatment with liquid N2 in order to enhance the Eu(III) emission. Also, the influence of Eu2O3 particles and BO in the polymer structural, thermal, morphological and optical properties was evaluated. The composite membranes with bandgap lying between 5.60 and 5.90 eV were obtained as γ-PVDF phase after being dried at 100 °C, with spheroidal particles connected by necks. The PVDF membranes are very stable till temperatures as high as 370 °C, and the Eu2O3 particle addition increases the membrane thermal stability while the BO decreases the PVDF stability. The cryo-treatment with N2 increases the PVDF crystallinity, leading to the PVDF particles agglomeration. The PVDF/BO/Eu2O3 membrane exhibited the characteristic red emission from Eu(III) along with an unexpected BO emission. Finally, after the cryo-treatment, the Eu3+ emission increases while the BO emission vanishes, and due to this temperature sensitivity, the system shows potential to be applied in temperature sensor platforms. São Paulo State University (Unesp) School of Technology and Sciences São Paulo State University (Unesp) Institute of Biosciences Humanities and Exact Sciences São Paulo State University (Unesp) School of Technology and Sciences São Paulo State University (Unesp) Institute of Biosciences Humanities and Exact Sciences FAPESP: 2012/13876-9 CNPq: 2015/10394-1 CAPES: 2016/20421-9

Made available in DSpace on 2018-12-11T17:37:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-10-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Structural, morphological and spectroscopic characterization of the Eu3+-doped Y2(MoO4)3 red phosphor incorporated with Au nanoparticles (Au NPs) synthesized via Pechini's method is reported in the present study. In order to evaluate the Au NPs and Eu3+ ions influence on the molybdate structure, the Y2(MoO4)3, Y2(MoO4)3:Eu3+, Y2(MoO4)3/Au and Y2(MoO4)3:Eu3+/Au samples were produced and fully investigated. All samples obtained at relatively low temperature, i.e., 650 °C, show molybdate as the unique phase with high crystallinity assisted by both Eu3+ ions and Au NPs. Water molecules detected in the molybdate structure probably are distorting MoO4, YO6 and EuO6 polyhedra similarly to the Au NPs incorporated in the same lattice. These Au NPs are spherical-shaped with a diameter near to 46 nm and they are located on the molybdate particle surface. The Eu3+-doped phosphors, with or without the presence of Au NPs, exhibit intense red luminescence characteristic of the Eu3+ ion inserted in low-symmetry sites. However, the Au NPs increase the radiative emission rate and absolute quantum yield of the Eu3+ 5D0 emitter state due to the excitation field enhancement caused by the local surface plasmon resonance absorption effect of gold nanoparticles, which was confirmed by diffuse reflectance measurements. Finally, the Eu3+ quantum efficiency enhancement to 92% played by the gold nanoparticles and the high red color purity qualify the obtained phosphor for photonic applications. São Paulo State University (Unesp) School of Technology and Sciences São Paulo State University (Unesp) Institute of Biosciences Humanities and Exact Sciences São Paulo State University (Unesp) School of Technology and Sciences São Paulo State University (Unesp) Institute of Biosciences Humanities and Exact Sciences FAPESP: 2012/13876-9 FAPESP: 2015/10394-1 FAPESP: 2016/20421-9

Made available in DSpace on 2021-06-25T11:17:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-09-15 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) In the present study, we report the use of an electrochemical sensor for uric acid using a molecularly imprinted polymer (MIP) as a molecular recognition platform. The MIP was based on an azopolymer electropolymerized in the presence of uric acid used as a template molecule. The azo group of the polymer contributes to the quantifiable redox capacitance of the electrode surface, which can be probed by impedance/capacitance spectroscopy. Thus, the advantage of the developed sensor is its ability to perform direct measurements without a soluble redox probe. The molecularly imprinted polymer can sensitively transduce the recognition and binding of specific analytes by redox capacitance. Through electrochemical impedance spectroscopy (EIS) and electrochemical capacitive spectroscopy (ECS), unusual approaches were able to obtain different analytical curves with distinct characteristics, reaching a limit of detection of 0.160 μmol L−1. Department of Chemistry and Biochemistry School of Science and Technology – Sao Paulo State University (UNESP), Rua Roberto Simonsen 305 Department of Chemistry and Biochemistry School of Science and Technology – Sao Paulo State University (UNESP), Rua Roberto Simonsen 305 FAPESP: 2016/09017-1 CNPq: 301298/2017-3 CAPES: 88882.434480/2019-01

The contribution of new materials, involving composites and blends, has been reaching the most varied fields of science, as much of the scientific as technological point of view. This is due to the man's needs in applications, especially in medicine areas. Thus, this work shows the preparation and characterization of poly(vinylidene fluoride) (PVDF) and calcium carbonate (CaCO 3 ) composite films in order to analyse the incorporation of CaCO 3 in PVDF for future application in bony restoration and bony filling. The films were prepared by casting method, where the PVDF pellet shape was dissolved in dimethylacetamide (DMA) and in a separate container CaCO 3 /DMA emulsion was also made. Soon afterwards they were mixed in several proportions 100/00, 95/05, 85/15, 70/30 in weight and left to dry in greenhouse. Homogeneous and flexible films were obtained and structurally characterized by attenuated total reflection infrared spectroscopy (FT-IR/ATR), thermal analyses (DSC, TGA), X-ray diffractometry, optical and scanning electron microscopies. The results showed that the material was a composite with good thermal stability until around 400 °C, the crystallinity of PVDF was non-polar α-phase and the obtained films were porous, being these filled with CaCO 3 .

Nanostructured KSr 2 Nb 5 O 15 oxide was synthesized by the polymeric precursor method, a chemical synthesis route based on the Pechini’s method. The X-ray diffraction (XRD) pattern of the calcined powder at 1150 °C were performed in the angular range 5 ≤ 2 θ ≤ 120° with a 0.02° step and a fixed counting time of 30 s. The XRD data were analyzed by the Rietveld refinements using the FullProf software. The results showed a tetragonal system with the tetragonal tungsten bronze structure (TTB) type ( a = 12.4585 (2) A and c = 3.9423 (6) A, V = 611,90 (2) A 3 ). In this work, the sites occupancy by the K + and Sr 2+ cations on the TTB type structure were determined. The thermal parameters ( B ) were analyzed.

Fluoroindate glasses doped with Pr3+ or Nd3+ are promising materials for the development of fluoride fibers, amplifiers and lasers. The optical properties of an InF3SrF2ZnF2GdF3NaF composition pure and doped up to 3 mol% have been systematically studied. The extended UV transmission of this glass allows the identification of most of the 8 S → 6 P and 8 S → 6 I transitions of Gd ions. The optical transitions of Pr3+ and Nd3+ have been identified in absorption between 250 and 10 000 nm. Fluorescence and excitation spectra and lifetime have been measured at 300 K. Most of the transitions have been identified.