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Made available in DSpace on 2019-10-06T15:44:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 Here, we report the luminescence properties of Yb3+/Pr3+ dual-doped fluorophosphate glasses containing silver clusters. Through the solubility of silver into the glass system as function of its initial concentration, charged species characterized as Ag+ and Agmn+ were formed and identified according to their absorption and emission spectral responses. By changing the transition metal concentration, multi-energy transfer mechanisms were observed between silver and Yb3+/Pr3+ co-doped glasses. The stabilization of silver species seems to be detrimental to the radiative processes of the rare earth ions under excitation at 444 nm (Pr3+3H4 → 3P0 absorption line). In other words, the main visible emissions of Pr3+ and the NIR emission of Yb3+ decrease with increment of Ag concentration. However, energy transfer occurs for large spectral range by the excitation of the silver species. In consequence, the visible and NIR emission could be activate in a broadband from ultraviolet to the blue part of the spectral region. These two observations highlight the competitive absorption processes and probabilities between the cationic elements and the interest to use the transition metal species as sensitizers to excite the rare earth elements. Institute of Chemistry - São Paulo State University - UNESP, CP 355 University of Bordeaux CNRS ICMCB UPR 9048, 87 Avenue du Dr. A. Schweitzer University of Bordeaux CNRS CEA CELIA UMR 5107, 351 Cours de la Liberation Institute of Chemistry - São Paulo State University - UNESP, CP 355

Made available in DSpace on 2021-06-25T10:21:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-05-25 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Glass-ceramics containing rare earth gallium garnets were obtained using glass compositions as reactional medium. This work reports on the synthesis, and structural, morphological, and optical characterizations of Er3+ and Tm3+-doped Yb3Ga5O12 crystals prepared from controlled cooling of heavy metal oxide glass melts. Micrometric cubic crystals were obtained by controlling the cooling of a rare earth-supersaturated glassy composition melted at high temperature. Crystals with sizes ranging between 5 and 150 µm were formed into the glass matrix. A gallium garnet phase corresponding to space group Ia-3d was identified by X-ray diffraction and confirmed by Rietveld simulations. The morphology of crystals was studied by optical and scanning electron microscopies, while chemical elements were mapped by electron dispersive X-Ray spectroscopy. The glass phase was studied by XRD, thermal analysis and Raman spectroscopy. The optical properties of both glass and glass-ceramic materials were evaluated by UV–Vis and luminescence spectroscopies. Micro-luminescence measurements confirmed that rare earths were incorporated into the crystalline phase. Intense upconversion emissions of Er3+ (550 and 660 nm) and Tm3+ (800 nm) were observed when the glass-ceramics were pumped at 980 nm. These new glass-ceramics are excellent candidates for the development of photonic devices. Institute of Chemistry – São Paulo State University – UNESP São Carlos Institute of Physics University of São Paulo University of Bordeaux CNRS ICMCB UPR 9048 University of Bordeaux CNRS ISM UPR 5803 Institute of Chemistry – São Paulo State University – UNESP FAPESP: 2013/07793-6 FAPESP: 2019/01223-0 CNPq: 502391/2014-6

Made available in DSpace on 2021-06-25T11:10:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-05-01 Ministero dell’Istruzione, dell’Università e della Ricerca Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) BiVO4 nanoparticles deposited onto TiO2 nanotube arrays (TNT) are used as heterostructured photoanodes in a compact-design photo-electrocatalytic (PEC) cell for solar-driven water splitting. No dopants, photosensitizers or other cocatalysts are added to enhance the catalytic activity but attention is focused on the relationship between TNT nanostructure (necessary for the novel compact-design PEC cell) and method of BiVO4 deposition. Three indicators are used to evaluate the catalytic performances: i) photocurrent density, ii) H2 production rate, and iii) solar-to-hydrogen efficiency (STH). Their dependence on photoanode characteristics (i.e. grade of TNT crystallinity) and operational parameters, such as anolyte concentration (NaOH in the range 0.1–1.0 M) and type of solar illumination (open spectrum or AM 1.5G filtered light), is analysed. While a linear relationship is observed between H2 production rate and photocurrent density, the behaviour of STH efficiency is more complex. An ordered and crystalline TNT film is necessary to maximize photocurrent density and H2 production rate, which can be further enhanced by depositing BiVO4. However, the methodology of BiVO4 deposition and the specific TNT nanoarchitecture have a marked influence in terms of light absorption, electronic conductivity and rate of reaction between photogenerated holes and OH−. This leads to an improvement or a depression of the photocatalytic behaviour as BiVO4 may in some cases favour charge recombination. Thus, understanding the role of the photoelectrodes in relation to the operational conditions may favour the preparation of scalable electrodes for improving performances of PEC cells in the generation of solar fuels. Departments of ChiBioFarAm and MIFT – University of Messina ERIC aisbl and CASPE/INSTM, V.le F. Stagno d'Alcontres, 31 Institute of Chemistry-Araraquara UNESP Rua Francisco Degni, 55, Bairro Quitandinha National Institute of Alternative Technologies for Detection Toxicological Evaluation and Removal of Micropollutants and Radioactive Substances (INCT-DATREM) São Paulo State University (Unesp) Institute of Chemistry Institute of Chemistry-Araraquara UNESP Rua Francisco Degni, 55, Bairro Quitandinha National Institute of Alternative Technologies for Detection Toxicological Evaluation and Removal of Micropollutants and Radioactive Substances (INCT-DATREM) São Paulo State University (Unesp) Institute of Chemistry Ministero dell’Istruzione, dell’Università e della Ricerca: 20179337R7 FAPESP: 2018/01934-0 FAPESP: 2018/16062-9

Made available in DSpace on 2021-06-25T11:03:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Bacterial cellulose (BC) is a biocompatible and nontoxic biopolymer that has been successfully used as a substrate for flexible organic light emitting diodes (OLEDs). Although BC membranes exhibit excellent mechanical properties and industrial scalability, they are semitransparent, which limits their performance. To improve the optical properties of BC membranes, methods such as the polymerization of different inorganic–organic hybrid materials and petrochemical derivative monomers have been considered; however, these methods require considerable time and effort. In this work, transparent BC membranes for conformable OLEDs substrates are fabricated by spray coating a solution of recycled petrochemical plastics, found in expanded foam package wastes, and d-limonene, which is a green solvent extracted from orange peels. This fabrication approach is highly scalable and can be considered a sustainable technique to develop high performance transparent substrates for photonic applications based on both recovered petrochemical polymers and naturally occurring biopolymers. In terms of the morphological and structural properties, the resulting transparent membranes exhibit a lower roughness than pristine BC. The resulting BC-PS composite is used as a substrate for OLED fabrication. The conformable OLEDs exhibit a current efficiency of up to 5 cd A−1 (16 000 cd m−2) and power density of ≈2.8 mW cm−2. Institute of Chemistry São Paulo State University – Unesp Departamento de Física Pontifícia Universidade Católica do Rio de Janeiro Grupo de Pesquisa em Biopolímeros e Biomateriais (BioPolMat) University of Araraquara (UNIARA) Department of Chemistry and Chemical Engineering Chalmers University of Technology Laboratório de Eletrônica Orgânica Departamento de Física Universidade Federal de Juiz de Fora UFJF Institute of Chemistry São Paulo State University – Unesp

One of the most important aspects to be evaluated when predicting the performance of refractory materials is their thermal shock resistance, especially considering the thermomechanical loads to which they are subjected. The methods currently used to predict thermal shock resistance behavior are based on Hasselman's studies, which take into account various experimental parameters. Thermal shock resistance can also be evaluated experimentally by applying thermal shock cycles and measuring the residual elastic modulus after each cycle. To predict and evaluate this resistance, test specimens of a commercial castable were cast, cured, dried and fired at 1000 °C and 1450 °C for five hours. Using Hasselman's parameters, the refractory fired at 1450 °C was predicted to present lower thermal shock resistance, which was confirmed by experimental thermal shock tests. The results indicated that the modulus of elasticity and modulus of rupture decreased by about 72% in specimens fired at 1000 °C, and by 82% in those fired at 1450 °C. Therefore, the specimens fired at 1450 °C showed lower thermal shock resistance. This finding underscores the importance of evaluating the behavior of castables with different microstructures resulting from different firing temperatures.

Made available in DSpace on 2018-12-11T16:42:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-11-01 Layer-by-Layer (LbL) films containing silk fibroin (SF) and the 40 aminoacid-long amyloid-β peptide (Aβ1-40) were prepared with the purpose of developing a new prototype of an electrochemical immunosensor. The film showed a satisfactory growth in quartz substrate and screen-printed carbon electrodes, as observed by UV-vis spectroscopy and cyclic voltammetric, respectively. The peptide immobilized in LbL films in junction with SF shows secondary structure induced, as shown by circular dichroism measurements, favoring the interaction SF/peptide LbL film with the specific antibody. Immunosensor showed a linear response in the presence of the antibody with concentrations from 0 to 10 ng mL- 1 both analyzed by current changes in 0.3 V and voltammogram area. This system can be applied as a new prototype for preliminary diagnosis of Alzheimer's disease. Instituto de Química Universidade Estadual Paulista Júlio de Mesquita Filho UNESP, Rua Professor Francisco Degni, 55 Instituto de Ciência e Tecnologia Universidade Federal de São Paulo UNIFESP, Rua Talim, 330 Instituto de Química Universidade Estadual Paulista Júlio de Mesquita Filho UNESP, Rua Professor Francisco Degni, 55

Made available in DSpace on 2018-12-11T17:23:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-11-05 A strain isolated from Kombucha tea was isolated and used as an alternative bacterium for the biosynthesis of bacterial cellulose (BC). In this study, BC generated by this novel bacterium was compared to Gluconacetobacter xylinus biosynthesized BC. Kinetic studies reveal that Komagataeibacter rhaeticus was a viable bacterium to produce BC according to yield, thickness and water holding capacity data. Physicochemical properties of BC membranes were investigated by UV–vis and Fourier transform infrared spectroscopies (FTIR), thermogravimetrical analysis (TGA) and X-ray diffraction (XRD). Additionally, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were also used for morphological characterization. Mechanical properties at nano and macroscale were studied employing PeakForce quantitative nanomechanical property mapping (QNM) and dynamic mechanical analyzer (DMA), respectively. Results confirmed that BC membrane biosynthesized by Komagataeibacter rhaeticus had similar physicochemical, morphological and mechanical properties than BC membrane produced by Gluconacetobacter xylinus and can be widely used for the same applications. Laboratório de Biopolimeros e Biomateriais (BIOPOLMAT) Centro Universitário de Araraquara, Araraquara Group ‘Materials + Technologieś (GMT) Department of Chemical and Environmental Engineering Engineering College of Gipuzkoa University of the Basque Country (UPV/EHU), Plaza Europa 1 Laboratório de Pesquisa Desenvolvimento & Inovação Apis Flora Ind. Coml. Ltda, Ribeirão Preto Institute of Chemistry-São Paulo StateUniversity-UNESP Institute of Chemistry-São Paulo StateUniversity-UNESP

This paper describes a study of shrinkage behavior in the liquid phase sintering of silicon carbide, SiC, using eutectic mixtures of Al 2 O 3 +Dy 2 O 3 and Al 2 O 3 +Yb 2 O 3 as liquid-forming additives. A volume fraction 10% of these mixtures was added to the SiC and homogenized in an attrition mill. Sintering was performed in a horizontal dilatometer at 1800 °C for 60 min, applying heating rates of 10, 20 and 30 °C/min. The results indicate that these heating rates affected neither shrinkage nor microstructure, from the standpoint of the complete sintering cycle. However, significant differences occurred during the non-isothermal sintering stage, leading to very different shrinkage results as a function of the heating rate. Higher heating rates produced lower shrinkage, and the work of final shrinkage occurred during the isothermal stage.

Bacterial cellulose (BC) produced by some bacteria, among them Gluconacetobacter xylinum, which secrets an abundant 3D networks fibrils, represents an interesting emerging biocompatible nanomaterial. Since its discovery BC has shown tremendous potential in a wide range of biomedical applications, such as artificial skin, artificial blood vessels and microvessels, wound dressing, among others. BC can be easily manipulated to improve its properties and/or functionalities resulting in several BC based nanocomposites. As example BC/collagen, BC/gelatin, BC/Fibroin, BC/Chitosan, etc. Thus, the aim of this review is to discuss about the applicability in biomedicine by demonstrating a variety of forms of this biopolymer highlighting in detail some qualities of bacterial cellulose. Therefore, various biomedical applications ranging from implants and scaffolds, carriers for drug delivery, wound-dressing materials, etc. that were reported until date will be presented.

Made available in DSpace on 2018-12-11T17:28:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-01-01 Six novel rare earth metal organic-frameworks with the general formula {[RE2(2,5-tdc)3(dmso)2]·H2O}n(RE = YIII, PrIII, NdIII, SmIII, ErIIIand TmIII; 2,5-tdc2− = 2,5-thiophenedicarboxylate anion; dmso = dimethylsulfoxide) were synthesized and their complete characterization, including single crystal X-ray diffraction, FTIR spectroscopy and thermal analysis (TG/DTA) are reported. Structure analysis reveals that REIIIions show distorted capped trigonal – prismatic geometry. The 2,5-tdc2−ligands connect four REIIIcenters, adopting (κ1– κ1) – (κ1– κ1) – μ4coordination mode, generating an interesting 3D network with potential application for gas adsorption. Photophysical properties were studied using excitation/emission spectra and the photoluminescence data show the near infrared (NIR) and visible (Vis) emission with the characteristic transitions:1D2 → 3F2for PrIII,4F3/2 → 4IJ(J = 9/2, 11/2 and 13/2) for NdIII,4G5/2 → 6HJ(J = 5/2, 7/2, 9/2 and 11/2) for SmIIIand4I13/2 → 4I15/2for ErIII. This study indicates that 2,5-tdc2−ligand is able to act as a sensitizer for emission in NIR and Vis region in these ions. Grupo de Materiais Inorgânicos Multifuncionais (GMIM) Instituto de Química Universidade do Estado do Rio de Janeiro Grupo de Química Inorgânica Supramolecular (GQUIS) Departamento de Química-ICE Universidade Federal de Juiz de Fora Laboratório de difração de raios X (LDRX) Departamento de Química Inorgânica Universidade Federal Fluminense Instituto de Química Universidade Estadual Paulista Júlio de Mesquita Filho UNESP Instituto de Química Universidade Estadual Paulista Júlio de Mesquita Filho UNESP

Made available in DSpace on 2018-12-11T17:27:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-06-05 Three different low molecular weight nematic liquid crystals (LCs) were used to impregnate bacterial cellulose (BC) film. This simple fabrication pathway allows to obtain highly transparent BC based films. The coating of BC film with different liquid crystals changed transmittance spectra in ultraviolet-visible region and allows to design UVC and UVB shielding materials. Atomic force microscopy results confirmed that liquid crystals coated BC films maintain highly interconnected three-dimensional network characteristic of BC film and simultaneously, transversal cross-section scanning electron microscopy images indicated penetration of liquid crystals through the three-dimensional network of BC nanofibers. Investigated BC films maintain nematic liquid crystal properties being switchable photoluminiscence as a function of temperature during repeatable heating/cooling cycles. Conductive response of the liquid crystal coated BC films was proved by tunneling atomic force microscopy measurement. Moreover, liquid crystal coated BC films maintain thermal stability and mechanical properties of the BC film. Designed thermoresponsive materials possessed interesting optical and conductive properties opening a novel simple pathway of fabrication liquid crystal coated BC films with tuneable properties. Group 'Materials + Technologies' (GMT) Department of Chemical and Environmental Engineering Polytechnic School University of the Basque Country (UPV/EHU), Plaza Europa 1 Laboratory of Photonic Materials Institute of Chemistry São Paulo State University - UNESP Laboratório de Química Medicinal e Medicina Regenerativa (QUIMMERA) Centro Universitário de Araraquara Laboratory of Photonic Materials Institute of Chemistry São Paulo State University - UNESP

This work attempts to obtain Dy3+-doped SiO2–Gd2O3 by sol–gel process, with a molar ratio of 70Si4+–30Gd3+ and Dy3+ concentrations of 0.1, 0.3, 0.5, and 1 mol%. Heat treatment at temperatures of 1000°C, 1100°C, 1200°C, and 1300°C have been performed. From XRD, the Gd2O3 cubic phase was observed at 1000°C and 1100°C, at 1200°C also were observed Gd2O3 monoclinic phase, predominant at 1300°C. The band-gap values vary between 4.4 and 5.3 eV, showing dependence on the crystalline phase. Under UV excitation, emission spectra show bands assigned to the Dy3+ transitions: 4F9/2→6H15/2 (484 nm), 4F9/2→6H13/2 (572 nm), and 4F9/2→6H11/2 (668 nm). The excitation at 275 nm has shown more effective. The ratio between the most intense emission bands (yellow/blue) show values around 0.84 and 1.63. CIE chromaticity diagrams show color coordinates at blue, yellow, and white regions, as a function of Dy3+ concentration and heat treatment. The lifetime values of excited state 4F9/2 were around 0.20 and 0.69 ms. The morphology of particles changed from spherical to coral-like shape as a function of heat treatment are observed. The sol–gel process showed to be an interesting route to obtain Dy3+-doped binary system materials.

Made available in DSpace on 2018-12-11T17:26:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-02-24 New binuclear lanthanide (III) complexes of general formula [Ln2(hcin)6(phen)2] (where Ln = Eu 1; Gd 2; Tb 3; hcin = hydrocinnamate anion; phen = 1,10-phenanthroline) were synthesized and fully characterized by elemental analysis, vibrational spectroscopy (infrared and Raman), thermal analysis (TGA/DTA), CP/MAS 13C NMR and powder X-ray diffraction. The crystal description based on powder X-ray diffraction data reveals that all compounds are isostructural and that each lanthanide ion is nine coordinated by oxygen and nitrogen atoms to form distorted tricapped trigonal-prismatic coordination polyhedron. The photoluminescence behavior was studied based on the excitation and emission spectra and luminescence decay curves. The emission spectra of Eu(III) and Tb(III) complexes are composed of intense and typical red and green emissions, respectively. Phosphorescence data of Gd(III) complex showed that the triplet states (T1) of ligands have higher energy than the main emitting states of Eu(III) and Tb(III) indicating the possibility of intramolecular energy transfer for these metal ions. To elucidate the energy transfer process in the Eu(III) complex, spectroscopic properties as Ωλ intensity parameters (λ = 2 and 4), radiative (Arad) and nonradiative (Anrad) decay rates and quantum efficiency (η) of [Eu2(hcin)6(phen)2] were determined. Such spectroscopic properties were compared with [Eu2(hcin)6(bpy)2] complex properties recently reported. The high emission quantum efficiency (η = 72%) for Eu(III) complex 1 showed that it is a potential candidate as emitter in photonic systems. Instituto de Química Universidade Do Estado Do Rio de Janeiro Departamento de Química-ICE Universidade Federal de Juiz de Fora Instituto de Química Universidade Estadual Paulista Júlio de Mesquita Filho UNESP Instituto de Química Universidade Estadual Paulista Júlio de Mesquita Filho UNESP

Made available in DSpace on 2018-12-11T17:26:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-02-01 This work reports on the Yb3+ ion addition effect on the near infrared emission and infrared-to-visible up conversion from planar waveguides based on Er3+-Yb3+ co-doped Nb2O5 nanocrystals embedded in SiO2-based nanocomposite prepared by a sol-gel process with controlled crystallization in situ. Planar waveguides and xerogels containing Si/Nb molar ratio of 90:10 up to 50:50 were prepared. Spherical-like orthorhombic or monoclinic Nb2O5 nanocrystals were grown in the amorphous SiO2-based host depending on the niobium content and annealing temperature, resulting in transparent glass ceramics. Crystallization process was intensely affected by rare earth content increase. Enhancement and broadening of the NIR emission has been achieved depending on the rare earth content, niobium content and annealing temperature. Effective Yb3+→Er3+ energy transfer and a high-intensity broad band emission in the near infrared region assigned to the Er3+ ions 4I13/2→4I15/2 transition, and longer 4I13/2 lifetimes were observed for samples containing orthorhombic Nb2O5 nanocrystals. Intense green and red emissions were registered for all Er3+-Yb3+ co-doped waveguides under 980 nm excitation, assigned to 2H11/2→4I15/2 (525 nm),4S3/2→4I15/2 (545nm) and 4F9/2→4I15/2 (670 nm) transitions, respectively. Different relative green and red intensities emissions were observed, depending upon niobium oxide content and the laser power. Upconversion dynamics were determined by the photons number, evidencing that ESA or ETU mechanisms are probably occurring. The 1931 CIE chromaticity diagrams indicated interesting color tunability based on the waveguides composition and pump power. The nanocomposite waveguides are promising materials for photonic applications as optical amplifiers and WDM devices operating in the S, C, and L telecommunication bands; and as upconverter materials for visible upconversion lasers, biomedical applications, energy conversion for solar cells and others. Departamento de Química Faculdade de Filosofia Ciências e Letras de Ribeirão Preto Universidade de São Paulo, Av. Bandeirantes, 3900 Grupo de Pesquisa em Química de Materiais - (GPQM) Departamento de Ciências Naturais Universidade Federal de São João Del Rei Campus Dom Bosco, Praça Dom Helvécio, 74 Grupo Física de Materiais Instituto de Física Universidade Federal de Goiás Campus II, C.P. 131 Institute of Chemistry- São Paulo State University- UNESP PSL Research University Chimie ParisTech - CNRS Institut de Recherche de Chimie Paris Sorbonne Universités UPMC Univ Paris 06 Institute of Chemistry- São Paulo State University- UNESP

Made available in DSpace on 2018-12-11T17:26:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-02-01 Nanostructured films prepared by Layer-by-Layer technique and containing silk fibroin, antigenic peptide NS5A-1 derived from hepatitis C virus (HCV) NS5A protein and YVO4:Eu3+ luminescent nanoparticles, were utilized in sensing of hepatitis C. Detection system exploits the biorecognition between the antibody anti-HCV and the antigenic peptide NS5A-1 through changes in luminescence properties. Films deposition was monitored by UV-vis Absorption and Fluorescence Spectroscopy measurements at each bilayer deposited. The Eu3+ luminescence properties were evaluated in the presence of anti-HCV for optical detection of specific antibody and anti-HIV used as negative control. Significant changes in luminescence were observed in the presence of anti-HCV concentrations. A new immunosensor platform is proposed for optical detection of hepatitis C. Institute of Chemistry São Paulo State University UNESP, CP355 Institute of Science and Technology Federal University of São Paulo UNIFESP Institute of Chemistry São Paulo State University UNESP, CP355

Made available in DSpace on 2018-12-11T17:23:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-01-01 Nickel polyphosphate coacervates have been prepared through the coacervation process of sodium polyphosphate and Ni2+ chloride solutions by the addition of different solvents with low molecular weight. The great potential of nickel polyphosphate coacervates as a material precursor was demonstrated by preparation of nickel polyphosphate glass-ceramics. Structural and spectroscopic properties were analyzed by thermal analysis, X-ray powder diffraction, Raman spectroscopic and UV-VIS techniques. Raman spectra for the nickel polyphosphate coacervates and nickel polyphosphate coacervates glass-ceramics samples shows that the addition of solvents leads to a depolymerization of the polyphosphate chains, resulting in an increase of shorter chains species based on pyrophosphates. The identification and quantification of Ni2P4012, β-Ni2P2O7 and δ-Ni2P2O7 crystalline phases present in the nickel polyphosphate glass-ceramics were carried out by X-ray powder diffraction using the Rietveld method. Quantitative phase analyses of the three polymorph forms were also evaluated. Based on interpretation of reflectance spectroscopy and Rietveld refinement, Ni2+ ions may occupy distorted octahedral and tetrahedral sites. LAVIE Department of Chemistry Federal University of São Carlos-UFSCar, CP 676 Institute of Chemistry Universidade Estadual Paulista-Unesp, P. O. Box 355 Laboratório de Biopolímeros e Biomateriais (BioPolMat) Centro Universitário de Araraquara (UNIARA) Núcleo de Espectroscopia e Estrutura Molecular-NEEM Departamento de Química Instituto de Ciências Exatas Universidade Federal de Juiz de Fora-UFJF Institute of Chemistry Universidade Estadual Paulista-Unesp, P. O. Box 355

Made available in DSpace on 2020-12-12T02:40:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-09-05 Higher Education Commission, Pakistan Universidade Estadual Paulista Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Bismuth vanadate (BiVO4, BV) is a promising visible-light responsive semiconductor photocatalyst able to harvest sunlight energy for photoelectrochemical and photochemical applications such as pollutants degradation and oxygen evolution from water. However, the fast recombination of photogenerated electrons and holes and poor electron transport properties remain as the bottlenecks in the way of efficient utilization of BV for such applications. Aiming to address these issues, we prepared Ag/Ag2O-loaded BV particles using a facile chemical deposition method employing an alkaline solution of glycerol for partial reduction (formation of Ag0) and deposition of Ag+ (as Ag2O) from AgNO3 solution. The as-prepared BV/Ag/Ag2O Z-scheme photocatalysts were characterized by SEM, TEM, DRS, XPS, XRD, Raman spectroscopy and electrochemical measurements. XRD and XPS analysis confirmed the formation of heterojunction photocatalysts of the type BV/Ag/Ag2O that show light absorption in an extended region of the visible spectrum as compared to pure BV. Compared to pristine BV (kobs. = 0.016 min-1), the synergy between the components in the resulting BV/Ag/Ag2O photocatalysts led to a dramatic increase (around 28 times) in photoactivity (kobs. > 0.45 min-1), as measured by photodegradation of crystal violet (CV) and Rhodamine B (RhB) employing commercial low-cost blue LEDs or natural sunlight. The enhanced photoactivity is attributed to the extended absorption of visible light and improved adsorption of dyes by the composite photocatalysts and the formation of BV/Ag/Ag2O Z-scheme heterojunction characterized by better charge carriers’ separation. Such a photocatalytic system highlights: (i) high efficiency aspect (since the emission of LEDs matches the absorption edge of BV) (ii) practicality aspects (the use of low-power, DC-operated LED photoreactor and natural sunlight) and (iii) economical aspects (low-cost and longer life-time of LEDs). Institute of Physics Federal University of Mato Grosso do Sul Institute of Chemistry São Paulo State University (UNESP) Institute of Chemical Sciences University of Peshawar, PO Box 25120 Institute of Chemistry of São Carlos University of São Paulo Institute of Chemistry São Paulo State University (UNESP) CNPq: 310066/2017-4 CNPq: 427835/2016-0 CNPq: 486342/2013-1

Made available in DSpace on 2020-12-12T02:28:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Polyurethane coatings derived from crambe and castor oil formulated with different proportions of additives were modified with tannin and applied on AA2024-T3 coupons. The coatings were characterized by water uptake and attenuated total reflectance Fourier transform infrared spectroscopy (FTIR-ATR). The thickness of the coatings was determined by scanning electron microscopy (SEM) and adhesion was evaluated by the ASTM D3359 standard. The barrier properties and corrosion protection ability were assessed by open circuit potential (EOCP) and electrochemical impedance spectroscopy (EIS). The self-healing ability of the coatings was studied by localized impedance spectroscopy (LEIS) and by the scanning vibrating electrode technique coupled with the scanning ion-selective electrode technique (SVET/SIET). The measurements demonstrate that tannin-modified coatings provide effective corrosion protection due to polymer healing and the results give important highlights concerning the mechanism of corrosion inhibition. Universidade Estadual Paulista-UNESP Instituto de Química Centro de Química Estrutural-CQE DEQ Instituto Superior Técnico Universidade de Lisboa, Av. Rovisco Pais Universidade Estadual Paulista-UNESP Instituto de Química FAPESP: 2015/10554-9 FAPESP: 2018/09040-9

Made available in DSpace on 2020-12-11T10:42:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Army Research Laboratory Air Force Office of Scientific Research MCTI-SisNano Rede Agronano (Embrapa) This paper presents a one-step method for patterning and reducing graphene oxide functionalized in silk fibroin using femtosecond laser induced forward transfer (LIFT). Such approach renders fibroin, a natural biopolymer with excellent biocompatibility, chemical stability, and mechanical properties, improved electrical conductivity in a controlled and localized way. Composite films based on silk fibroin and graphene oxide/reduced graphene oxide were fabricated by spin coating at room temperature. The films composition was characterized by micro-Raman spectroscopy demonstrating the presence of graphene oxide in the silk fibroin matrix. The influence of pulse energy on the fs laser transfer process was investigated, yielding a threshold energy of 24.0 nJ. Additionally, the laser-induced reduction of graphene oxide attained by LIFT was determined by Raman spectroscopy and further confirmed by an increase in the electrical conductivity. The approach presented here proved to be an efficient route to simultaneously produce micrometric patterns of graphene oxide/silk fibroin composite (with line widths on the order of 1 mu m), and reduction of graphene oxide, opening new opportunities for the development of green composites for electronics devices, including for instance microfluidic sensors, capacitors and LEDs. Univ Sao Paulo, Sao Carlos Inst Phys, BR-13560970 Sao Carlos, SP, Brazil Sao Paulo State Univ, Araraquara Inst Chem, BR-14800060 Araraquara, SP, Brazil Embrapa Instrumentacao, Nanotechnol Natl Lab Agr LNNA, BR-13560970 Sao Carlos, SP, Brazil Univ Fed Sao Carlos, Ctr Exact Sci & Technol, PPGQ, Dept Chem, BR-13565905 Sao Carlos, SP, Brazil Sao Paulo State Univ, Araraquara Inst Chem, BR-14800060 Araraquara, SP, Brazil FAPESP: 2018/1283-7 FAPESP: 2016/11591-8 FAPESP: 2013/03487-8 FAPESP: 2017/12174-4 FAPESP: 2017/10582-8 CAPES: 001 Army Research Laboratory: W911NF-17-1-0123 Air Force Office of Scientific Research: FA9550-12-1-0028

Made available in DSpace on 2018-12-11T17:38:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-12-20 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Surface-enhanced Raman scattering (SERS) is one of the most sensitive methods for the detection of adsorbed molecules on the nanostructured coinage-metal surface. The enhancements in the order of 104–106 are routinely observed. Such an effect makes SERS spectroscopy a technique applicable to the study the adsorption of analytes in the submonolayer regime. Novel SERS sensors require novel substrates with high activity for great sensibility detection of different molecules applied in many fields, such as detections of narcotics, explosives, and molecules with biological interest. In this work, silver nanoparticles embedded in niobium lead-pyrophosphate glasses (Pb2P2O7-Nb2O5-Na2O) were prepared by ion exchange process, where silver ions were introduced into glass surface by Ag+/Na+ ion exchange (NaNO3:AgNO3 batch), and reduced to metallic silver by heat treatment at glass transition temperature (ca. 480 °C). The new substrate was characterized by Raman spectroscopy, optical absorption, transmission electron microscopy (TEM) and atomic force microscopy (AFM). Its application in SERS was demonstrated by studying the adsorption of 2,2-bipyridine (bpy) on the glass surface, which has marker bands for the coordination of the adsorbate with silver atoms. The optimal surface features in terms of SERS enhancement were also discussed and the sensing ability of this new substrate was demonstrated. São Carlos Institute of Chemistry – IQSC University of São Paulo – USP Institute of Chemistry São Paulo State University – UNESP Materials Engineering Department – DEMA Federal University of São Carlos – UFSCar Department of Chemistry Federal University of Juiz de Fora – UFJF Institute of Chemistry São Paulo State University – UNESP FAPESP: 2013/07793-6 FAPESP: 2016/16900-9 CNPq: 502391/2014-6

An amphiphilic derivative of chitosan containing quaternary ammonium and myristoyl groups, herein named as ammonium myristoyl chitosan (DMCat), was synthesized by reacting glycidyltrimethylammonium chloride (GTMAC) and myristoyl chitosan (DMCh). The success of the modification was confirmed using Fourier-transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (NMR) spectroscopy. The average degrees of alkylation and quaternization ( D Q &macr, ) were determined by using 1H NMR and conductometric titration. The zeta potential of the micelles was higher than 28 mV while its average size and encapsulation efficiency ranged from 280 nm to 375 nm and 68% to 100%, respectively. The in vitro cytotoxicity of the unloaded and curcumin (CUR)-loaded micelles was tested against Caco-2 and HT29-MTX intestinal epithelial cell lines. The results showed no cytotoxic effect from loaded and unloaded micelles as compared to free CUR. In the permeability test, it was observed that both types of micelles, i.e., DMCh and DMCat, improved CUR permeability. Additionally, higher permeability was verified for both systems in Caco-2/HT29-MTX:Raji B because of the mucoadhesive character of chitosan and its ability to open tight junctions. The results indicated that DMCat micelles, due to the physico-chemical, improved characteristics may be a promising carrier to encapsulate CUR aiming cancer therapy.

Made available in DSpace on 2018-12-11T17:37:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-11-01 The various synthesis conditions to obtain a material based on SiO2-TiO2 co-doped with Er3+/Yb3+/Eu3+ were investigated, searching for those that present the greatest potential to improve the efficiency of solar cells. Conditions adjusted included heat-treatment temperatures, concentrations of matrix, and concentrations of dopants. Raman spectroscopy results demonstrated the effect of the annealing temperatures on the TiO2 phase transition and the crystalline phase of the materials, which interfere with the photoluminescence of the materials. The band gap of the materials was evaluated by diffuse reflectance and it decreased due to the doping. The materials were able to absorb UV and IR energy and emit in the visible region, verified by the down conversion, up conversion and the double excitation of the materials. The results showed that the materials may be used as a strategy to use a greater portion of the solar spectrum, improving solar cell efficiency. Grupo de Pesquisa em Química de Materiais – (GPQM) Departamento de Ciências Naturais Universidade Federal de São João Del Rei Campus Dom Bosco, Praça Dom Helvécio, 74 São Carlos Institute of Chemistry – IQSC University of São Paulo – USP Instituto de Química UNESP, P.O. Box 355 Department of Chemistry and Physics University of Tennessee at Martin Desenvolvimento de Materiais Inorgânicos com Terras Raras – (DeMITeR) Instituto de Química – (IQ), Universidade Federal de Uberlândia – (UFU) Av. João Naves de Ávila, 2121, Bairro Santa Mônica Instituto de Química UNESP, P.O. Box 355

Made available in DSpace on 2018-11-26T16:01:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-09-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Lanthanide (Ln(3+))-doped suitable matrices exhibit unique luminescent properties which are important for applications in optoelectronic devices. Most of the Ln(3+)-based luminescent materials are, however, prepared in powder form using suitable robust inorganic host matrices. These matrices, often, experience lack of flexibility which is important for many applications such as LEDs and wearable devices, among others. To address this aspect, we report the preparation of flexible and highly transparent luminescent membranes based on poly-dimethylsiloxane- hydroxyurethanes (PDMSUr) as the hybrid framework and Europium-polyoxometalate (Eu (PW11)(2)) complex as the luminescent component. The PDMSUr, besides acting as green, transparent and flexible matrix, is found to increase the emission decay lifetime (from 1.5 ms to 3.0 ms) when Eu(PW11)(2) is incorporated in the hybrid matrix. Moreover, upon UV excitation, the matrix exhibits a broader emission around 450 nm which, together with the characteristic emission of Eu3+ ions, leads to the generation of white light. Univ Sao Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Carlos, SP, Brazil Univ Estadual Paulista, Inst Quim, BR-14800060 Araraquara, SP, Brazil Univ Peshawar, Inst Chem Sci, Peshawar 25120, KP, Pakistan CNRS ENSCM UM, Inst Charles Gerhardt Montpellier, UMR 5253, 8 Rue Ecole Normale, F-34296 Montpellier 05, France Univ Estadual Paulista, Inst Quim, BR-14800060 Araraquara, SP, Brazil CAPES: PROEX 1480648 FAPESP: 2015/18733-0 FAPESP: 2015/22875-4

Made available in DSpace on 2018-12-11T16:52:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-08-01 In this work, Er3+-containing fluoroindate glasses were synthesized by the conventional melt-quenching method varying Er3+ content from 0.1 to 7 mol%. The series of fluoroindate glass were investigated according to their luminescent properties. Upon excitation at 1550 nm, all glass samples showed green, red and near-infrared emissions centered at 550, 667 and 978 nm. Energy transfer upconversion (ETU) is the main mechanism responsible for the upconverted emissions and involves neighbour erbium ions. The highest near-infrared emission intensity at 1000 nm is observed for the glass sample containing 7 mol% of Er3+, which was used to evaluate the photovoltaic response of monocrystalline and monofacial silicon solar cell. This approach represents a beneficial strategy to stud spectral modification in upconverter materials. Institute of Chemistry São Paulo State University – UNESP São Carlos Institute of Chemistry University of São Paulo Institute of Chemistry São Paulo State University – UNESP

Made available in DSpace on 2018-12-11T16:54:32Z (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 Minas Gerais (FAPEMIG) Financiadora de Estudos e Projetos The evolution of research on luminescent phosphors led to research on materials doped with rare earth ions (RE3+), not only because of their photoluminescent properties, but also for their potential applications in photonics. The search for new photoluminescent materials has led to an investigation of the photoluminescence of RE3+ present in an aluminum oxide (Al2O3) matrix. This oxide has a transparent window on the short ultraviolet to near infrared, excellent mechanical properties and good chemical stability. Within this context, this work aims to obtain Al2O3: Er3+/Yb3+. The preparation of Al2O3: Er3+/Yb3+ involved two synthesis processes. For the co-precipitation process, rings of aluminum cans were used as precursors, and for the sol-gel process, the precursor used was tri-sec-butoxide aluminum. From the XRD results, high heat-treatment temperatures were observed to favor the formation of the α-Al2O3 phase and low temperatures were observed to favor the formation the γ-Al2O3 phase. The analysis of the photoluminescence emission spectra when excited at 980 nm, showed the up-conversion phenomenon with an emission in the visible region. The emission spectra also showed emission between 1400 and 1650 nm, with a maximum at about 1530 nm. The materials exhibit efficient energy absorption in the infrared region, with light emission in the visible region. Furthermore, the spectra show an intense emission in the infrared region assigned to the 4I13/2 → 4I15/2 transition of Er3+, demonstrating excellent potential to be used in optical amplifier device at the third telecommunications window. Grupo de Pesquisa em Química de Materiais – (GPQM) Departamento de Ciências Naturais Universidade Federal de São João del-Rei Campus Dom Bosco, Praça Dom Helvécio, 74 Instituto de Química UNESP, P.O. Box 355 Research Group of Materials Chemistry Universidade Federal de Alfenas, Campus de Poços de Caldas Departamento de Química Faculdade de Filosofia Ciências e Letras de Ribeirão Preto USP, Avenida Bandeirantes, 3900 Department of Chemistry and Physics University of Tennessee at Martin Desenvolvimento de Materiais Inorgânicos com Terras Raras - DeMITeR Instituto de Química – (IQ) Universidade Federal de Uberlândia – (UFU), Av. João Naves de Ávila, 2121 – Bairro Santa Mônica Instituto de Química UNESP, P.O. Box 355 FAPEMIG: CEX - RED-00010-14

Made available in DSpace on 2018-12-11T17:34:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01 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 Goiás Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) We synthesized pure and Eu3+ doped Al6Ge2O13 samples by an easy and low-cost sol-gel route using the GeO2, Al(NO3)3·9H2O and Eu(NO3)3·6H2O as precursors, tetramethylammonium hydroxide and ethanol as solvents. The Al6Ge2O13 crystalline phase possesses orthorhombic structure and is a potential host for rare earth ions, especially due to high aluminum concentration. Homogeneous and transparent sols and gels were obtained. The samples containing 1 mol% of Eu3+ were heat-treated at 1000 °C to eliminate organic compounds, providing high optical quality and structural purity. All materials were characterized by thermogravimetric and differential thermal analysis, X-ray diffraction, Fourier transform infrared spectroscopy, high resolution transmission electron microscopy, selected area electron diffraction, diffuse reflectance spectra in the ultraviolet–visible–near infrared regions and photoluminescence measurements. High purity of Eu3+ doped Al6Ge2O13 orthorhombic phase and well crystallized grain dimensions of around 100 nm was obtained with high red photoluminescence emission. The decay lifetime of 5D0 level from Eu3+ (the emission at 612 nm) was determined, being between 0.97 and 2.12 ms, and an average quantum efficiency of 54% was determined (considering the average experimental lifetime of 1.77 ms). Moreover, it was calculated and analyzed some parameters of Judd-Ofelt theory applied to Eu3+ emissions from Al6Ge2O13 host. The results show that Eu3+ doped Al6Ge2O13 crystalline compounds have large potential to be used in displays and LED devices. Grupo Física de Materiais Instituto de Física Campus II Universidade Federal de Goiás-UFG, CP 131 Departamento de Química Faculdade de Filosofia Ciências e Letras de Ribeirão Preto Universidade de São Paulo-USP, Av. Bandeirantes 3900 Institute of Chemistry São Paulo State University-UNESP, CP 355 Institute of Chemistry São Paulo State University-UNESP, CP 355

Made available in DSpace on 2018-11-26T22:40:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-10-01. Added 1 bitstream(s) on 2019-10-09T18:27:55Z : No. of bitstreams: 1 S0103-50532018001002054.pdf: 1875083 bytes, checksum: d412309b2dfc7b515b1a8e8b893b7ce1 (MD5) 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) LMF/LNNano, Brazil Immunosensors based on impedance spectroscopy for diagnosing hepatitis C are reported where the sensing units were made with the antigenic peptide PPLLESWKDPDYVPPWHG (NS5A-1) derived from the NS5A protein of the hepatitis C virus (HCV) immobilized in layer-by-layer (LbL) films with silk fibroin (SF) and deposited on gold interdigitated electrodes. The electrical response of the sensing units varied upon immersion into solutions containing the antibody anti-HCV owing to the biomolecular recognition of NS5A-1. This was associated with morphological changes on the LbL films caused by adsorption of NS5A-1 and inferred from atomic force microscopy images. Buffer solutions with different anti-HCV concentrations down to 2 ng mL(-1) could be clearly distinguished by analyzing the impedance spectroscopy data with a multidimensional projection technique. The specificity toward anti-HCV antibodies was confirmed in control experiments where no significant changes in the electrical response were measured by exposing the sensing units to solutions containing an anti-human immunodeficiency virus (HIV) antibody. The high sensitivity and selectivity of the units made with LbL films demonstrate the feasibility of measuring electrical impedance as an immunosensing strategy to detect hepatitis C. Univ Estadual Paulista, Inst Quim, BR-14800060 Araraquara, SP, Brazil Univ Fed Mato Grosso do Sul, Inst Fis, CP-549, BR-79070900 Campo Grande, MS, Brazil Univ Sao Paulo, Inst Ciencias Matemat & Comp, BR-13566590 Sao Carlos, SP, Brazil Univ Sao Paulo, Inst Fis Sao Carlos, BR-13566590 Sao Carlos, SP, Brazil Univ Fed Sao Paulo, Inst Ciencia & Tecnol, BR-12231280 Sao Jose Dos Campos, SP, Brazil Univ Estadual Paulista, Inst Quim, BR-14800060 Araraquara, SP, Brazil CAPES: 26 LMF/LNNano, Brazil: LMF 12298

The fluorine motional dynamics in fluorosilicate glasses and glass-ceramics of the SiO2–PbF2–CdF2 system was investigated by complex impedance spectroscopy and 19F nuclear magnetic resonance (NMR) spectroscopy, and the coordination environment of a Cu2+ paramagnetic probe was examined by electron paramagnetic resonance (EPR) spectroscopy. Glass-ceramics were obtained by heat treatment of glass at a temperature between the glass-transition (Tg) and the onset of crystallization (Tx). Ionic conductivity of about 1.6 × 10–4 S/cm was obtained at 500 K for glass. The conductivity of the glass-ceramics was found to be lower than that obtained for the glass. The temperature dependence of the 19F NMR spin–lattice relaxation times was investigated between 300 and 770 K. The 19F NMR results of glass exhibit the qualitative features associated with fluorine mobility, namely, the presence of a relaxation rate maximum below Tg. The NMR relaxation data of the glass-ceramics were analyzed assuming two fluorine dynamics. ...

Made available in DSpace on 2018-12-11T16:38:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-07-14 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Abstract This work reports on the synthesis of Eu3+-doped Gd2O3 using PEG as an organic molecular precursor with 1, 3, 5, 7 e 10 mol% of Eu3+. TGA and DTA analysis of the precursors obtained shows that the final materials are obtained at thermal treatment above 700 °C. Based on this information all materials were obtained after heat treatment at 900, 1000 and 1100 °C during 4 h in an oven under air atmosphere. XRD analysis showed that the materials obtained after heat-treatment presents a cubic crystalline structure assigned to the Gd2O3. Crystallite size and microstrain were evaluated using the Scherrer's equation and Williansom-Hall method, respectively, as a function of heat-treated temperature and Eu3+ concentration. Raman spectroscopy also showed the formation of the Gd2O3 phase, however, the absence of bands around 117 cm-1 in the spectra with higher Eu3+ concentration indicates that the insertion of this one in the host matrix promotes the breakdown of some chemical bonds of the matrix. Intense photoluminescence emission in the visible region with maximum localized around 611 nm under excitation at 255 nm with xenon lamp and with X-ray source were observed. The emissions observed were attributed to the intraconfigurational f-f transitions of Eu3+. The lifetime values of the 5D0 excited state were between 2.84 and 2.89 ms, indicating the location of Eu3+ in crystalline systems. This result demonstrates the potential application of the materials in systems for absorption in the ultraviolet region, solar cells, devices generated images and scintillation systems. Grupo de Pesquisa em Química de Materiais - (GPQM), Departamento de Ciências Naturais, Universidade Federal de São João Del Rei, Campus Dom Bosco, Praça Dom Helvécio, 74 Instituto de Química, UNESP, P.O. Box 355 Instituto de Química, UNESP, P.O. Box 355

Bacterial cellulose (BC) and silk fibroin (SF) are natural biopolymers successfully applied in tissue engineering and biomedical fields. In this work nanocomposites based on BC and SF were prepared and characterized by scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). In addition, the investigation of cytocompatibility was done by MTT, XTT and Trypan Blue dye technique. Cellular adhesion and proliferation were detected additionally. The evaluation of genotoxicity was realized by micronucleus assay. In vitro tests showed that the material is non-cytotoxic or genotoxic. SEM images revealed a greater number of cells attached at the BC/SF:50% scaffold surface than the pure BC one, suggesting that the presence of fibroin improved cell attachment. This could be related to the SF amino acid sequence that acts as cell receptors facilitating cell adhesion and growth. Consequently, BC/SF:50% scaffolds configured an excellent option in bioengineering depicting its potential for tissue regeneration and cultivation of cells on nanocomposites.

Made available in DSpace on 2018-11-26T15:27:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-11-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Photochromic ormosil-phosphotungstate hybrid materials were prepared by immobilizing phosphotungstic acid, H3PW12O40, (HPW) in hybrid organic-inorganic ormosil matrices via sol-gel route, and the effect of addition of TiO2 nanoparticles (NPs) on the photochromic response of HPW was studied. For measurement of the photochromic response and the bleaching kinetics, the resulting sol-gel-derived ormosil-phosphotungstate hybrid materials with and without TiO2 NPs were coated as thin films on glass substrate by dip coating. The hybrid films were characterized by scanning electron microscopy, Fourier transform infrared absorption spectroscopy, Raman spectroscopy and X-ray fluorescence spectroscopy. The addition of small amounts of TiO2 was found to increase the photochromic response of the hybrid materials by as much as 277 % which is attributed to a possible interfacial electron transfer from the photoexcited TiO2 to HPW. These highly UV-sensitive coatings can find useful applications in UV dosimeters and smart windows. [GRAPHICS] . Univ Sao Paulo, Escola Engn Sao Carlos, BR-13560970 Sao Carlos, SP, Brazil Univ Sao Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Carlos, SP, Brazil Univ Peshawar, Inst Chem Sci, Peshawar 25120, Pakistan Univ Estadual Paulista, Inst Quim, BR-14801970 Araraquara, Brazil Univ Estadual Paulista, Inst Quim, BR-14801970 Araraquara, Brazil FAPESP: 2011/08120-0

This study aimed to evaluate the potential of bacterial cellulose-hydroxyapatite (BC-HA) composites associated with osteogenic growth peptide (OGP) or pentapeptide OGP(10-14) in bone regeneration in critical-size calvarial defects in mice. In this study, the BC-HA, BC-HA-OGP, and BC-HA-OGP(10-14) membranes were analyzed at 3, 7, 15, 30, 60, and 90 days. In each period, the specimens were evaluated by micro-computed tomography (µCT), descriptive histology, gene expression of bone biomarkers by qPCR and VEGFR-2 (vascular endothelial growth factor) quantification by ELISA. Three days post-operative, Runx2, Tnfrsf11b and Bglap bone biomarkers were upregulated mainly by BC-HA OGP and BC-HA OGP(10-14) membranes, suggesting an acceleration of the osteoblast differentiation/activity with the use of these biomaterials. At 60 and 90 days, a high percentage of bone formation was observed by µCT for BC-HA and BC-HA OGP(10-14) membranes. High expression of some bone biomarkers, such as Alpl, Spp1, and Tnfrsf11b, was also observed for the same membranes on days 60 and 90. In conclusion, the BC-HA membrane promoted a better bone formation in critical-size mice calvarial defects. Nevertheless, incorporation of the peptides at the concentration of 10(-9) mol L(-1) did not improve bone regeneration potential in the long-term.

In this paper, the synthesis of three new metal-organic frameworks of lanthanides (LnMOFs) {[Ln2(2,5-tdc)3(dmso)2]·H2O}n (Ln=Ho (1); Gd (2); Eu (3); 2,5-tdc=2,5-thiophenedicarboxylate anion; dmso=dimethylsulfoxide), and their complete characterization, including single crystal X-ray diffraction, FTIR spectroscopy and thermogravimetric analysis are reported. In especial, photophysical properties of Eu(III) complex have been studied in detail via both theoretical and experimental approaches. Crystal structure of (1) reveals that each lanthanide ion is seven-coordinated by oxygen atoms in an overall distorted capped trigonal – prismatic geometry. The 2,5-tdc2− ligands connect four Ln(III) centers, adopting (κ1–κ1)–(κ1–κ1)–μ4 coordination mode, generating an 8-connected uninodal 3D network. In addition, theoretical studies for Eu(III) complex were performed using the Sparkle model for lanthanide complexes.

In this work, transparent organic–inorganic nanocomposites membranes have been prepared by casting process using carboxymethylcellulose (CMC) as organic matrix and synthetic clay (laponite) as reinforcement inorganic filler. Pristine CMC and CMC-laponite nanocomposites films were prepared using different clay-to-polymer ratios and all the obtained membranes are optically transparent on the UV–vis range. Field emission scanning electron microscopy (FE-SEM) images of the nanocomposite films evidenced a homogeneous dispersion of clay in the polymer matrix. As result, mechanical properties of the membranes are deeply affected by the presence of clay, increasing the Young’s modulus and tensile strength values when clay content is increased. On the other hand, maximum strain values decrease when clay concentration is over 10 wt% in comparison to pristine CMC membrane. Thermal properties of CMC films are also influenced by the presence of clay platelets. The main weight loss step of the nanocomposites is shifted toward higher temperatures when compared to pristine CMC membrane, indicating that laponite particles are capable of protecting the polymer chains from thermal and oxidative decomposition. Water vapor permeability (Pw) trend also reveals a decrease in these values for the nanocomposites when clay concentration is high, achieving its minimum permeability at 17 wt% of clay content (which corresponds a decrease of 42% on Pw value in comparison to pristine CMC membrane).

International audience; Glasses in the binary system (100-x)Pb2P2O7-xMoO3, with x = 10 – 80 mol%, were synthesized by conventional melt-quenching technique. Thermal analysis, linear optical absorption, refractive index measurements, Raman scattering and nonlinear (NL) optical experiments were performed to characterize the samples. The dependence of MoO3 content on thermal, structural and optical properties was investigated. Molybdenum oxide increases both the glass transitions temperature and thermal stability against devitrification up to 50mol% due to formations of P-O-Mo linkages and the glass network connectivity increases. The nonlinear optical properties were studied at 1064 nm and 532 nm with pulses of ≈17 ps. The NL refractive index measured was +10-19 m2/W at both wavelengths for samples with different relative concentrations of the constituent compounds. At 1064 nm we determined that the two-photon absorption coefficient, , is smaller than the minimum that we can measure (

This work reports on the preparation of materials based on Yb3+/Er3+ co-doped SiO2-Gd2O3 via sol-gel process. The 0.4mol%of Er3+ ions was fixed and the amount of Yb3+ ions changed as 1.8, 5 and 9mol%in order to evaluate the photoluminescence properties as a function of the Yb3+ ions concentration. The prepared xerogels were heat-treated at 900, 1000 and 1100?C for 8 h. X-ray diffraction analyses of the heat-treated materials confirmed the formation of the Gd2O3 cubic phase embedded in the SiO2 host, demonstrating the effective incorporation of RE3+ ions in the structure. The Scherrer?s equation verified that the sizes of Gd2O3 nanocrystallite are between 31 and 69 nm and directly dependent on the heat-treatment temperature. Under excitation at 980 nm all materials showed upconversion phenomena, and the intensities of the emissions in the green and red regions showed to be directly dependent on power pump of laser, quantity of Yb3+ ions and heat-treatment temperature. The materials also showed emission in the infrared region with the maximum around 1530 nm, assigned to the transition of 4I13/2 ? 4I15/2 of the Er3+ ions, region known as technological C-telecom band used in optical amplification.

The preparation of Tm 3+ /Yb 3+ /Ho 3+ co-doped CeO 2 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 CeO 2 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.

Highly transparent biocomposite based on bacterial cellulose (BC) mat modified with poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) block copolymer (EPE) were fabricated in situ during biosynthesis of bacterial cellulose in a static culture from Gluconacetobacter xylinum. The effect of the addition to the culture medium of water-soluble EPE block copolymer on structure, morphology, crystallinity, and final properties of the novel biocomposites was investigated at nano- and macroscale. High compatibility between components was confirmed by ATR-FTIR indicating hydrogen bond formation between the OH group of BC and the PEO block of EPE block copolymer. Structural properties of EPE/BC biocomposites showed a strong effect of EPE block copolymer on the morphology of the BC mats. Thus, the increase of the EPE block copolymer content lead to the generation of spherulites of PEO block, clearly visualized using AFM and MO technique, changing crystallinity of the final EPE/BC biocomposites investigated by XRD. Generally, EPE/BC biocomposites maintain thermal stability and mechanical properties of the BC mat being 1 wt % EPE/BC biocomposite material with the best properties. Biosynthesis of EPE/BC composites open new strategy to the utilization of water-soluble block copolymers in the preparation of BC mat based biocomposites with tunable properties.

Herein we report on the crystallized nanoparticles based on Eu 3+ -doped Y 2 O 3 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 °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 °C for 4 h, and the visualization of the cubic structure was obtained. The centered cubic crystalline structure of Y 2 O 3 was obtained and the photoluminescence properties of Eu 3+ ion in Y 2 O 3 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.

Zidovudine (AZT) is the antiretroviral drug most frequently used for the treatment of Acquired Immunodeficiency Syndrome. Its low oral bioavailability demands the development of innovative strategies to overcome the first pass metabolism. The nasal route is an option for enhanced therapeutic efficacy and to reduce the extent of the first-pass effect. In this article, AZT loaded chitosan nanoparticles were prepared by a modified ionotropic gelation method with sodium tripolyphosphate. The increase proportion of CS (NP1 10:01 (w/w)) promoted the formation of smaller nanoparticles (260 nm), while raising the proportion of TPP (NP2 5:1 w/w) increased the nanoparticles size (330 nm). The incorporation of AZT increased the nanoparticles size for both AZT-loaded nanoparticles AZT-loaded NP1 (406 nm) and AZT-loaded NP2 (425 nm). The incorporation of AZT into NP1 did not change the electrophoretic mobility, however, in AZT-loaded NP2 there was a significant increase. The positive surface of the nanoparticles is very important for the mucoadhesive properties due interaction with the sialic groups of the mucin. Nuclear resonance magnetic data showed that the higher concentration of chitosan in the nanoparticles favored the interaction of few phosphate units (pyrophosphate) by ionic interaction Scanning electron microscopy, revealed that the nanoparticles are nearly spherical shape with porous surface. The entrapment efficiency of AZT, was 17.58% ± 1.48 and 11.02% ± 2.05 for NP1 and NP2, respectively. The measurement of the mucoadhesion force using mucin discs and nasal tissue obtained values of NP1 = 2.12 and NP2 = 4.62. In vitro permeation study showed that the nanoparticles promoted an increase in the flux of the drug through the nasal mucosa. In view of these results, chitosan nanoparticles were found to be a promising approach for the incorporation of hydrophilic drugs and these results suggest that the CS-containing nanoparticles have great potential for nasal AZT administration.

Made available in DSpace on 2018-11-26T17:41:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-11-15 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Bacterial cellulose (BC) has been extensively exploited for applications in materials science, biomedical and technological fields. The BC production demands culture media rich in carbon sources. Agro-forestry residues constitute an interesting source of nutrients for microorganism, but they are frequently wasted. For cashew crop, exudate is periodically extracted from the tree trunks to increase the production of cashew nut, the most valuable product from cashew trees that produces about 700 g of exudate/year, which remains wasted. Here, we associated the nutritional properties of residues from cashew tree with the need of carbon sources for BC, in attempt to valorize the residue and to decrease the costs of BC production. The carbon source from Hestrin Schramm culture medium was totally or partially replaced by cashew tree residues and the BC production was evaluated. The produced BC membrane in static medium was characterized by FTIR, SEM and TGA and the kinetics of production was determined, suggesting the cashew tree residues as a potential carbon source for BC production. Univ Araraquara Uniara, Lab Biopolimeros & Biomat BIOPOLMAT, Rua Carlos Gomes 1217, BR-14801320 Araraquara, SP, Brazil Univ Fed Piaui, Ctr Ciencias Nat, Lab Interdisciplinar Mat Avancados, Campus Univ Uninga, BR-64049550 Teresina, PI, Brazil Univ Fed Grande Dourados UFGD, Dept Quim, Fac Ciencias Exatas & Tecnol FACET, Rodovia Dourados Itahum,Km 12,Cidade Univ, BR-79804970 Dourados, MS, Brazil Univ Estadual Poulista Julio de Mesquita Filho, Inst Quim Araraquara, Dept Quim Geral & Inorgan, Rua Prof Francisco Degni,55 Jardim Quitandinha, BR-14800060 Araraquara, SP, Brazil Univ Estadual Poulista Julio de Mesquita Filho, Inst Quim Araraquara, Dept Quim Geral & Inorgan, Rua Prof Francisco Degni,55 Jardim Quitandinha, BR-14800060 Araraquara, SP, Brazil CAPES: 1514505

SummaryBackground Bacterial cellulose (BC) is a versatile material produced by microorganisms in the form of a membranous hydrogel, totally biocompatible, and endowed with high mechanical strength. Its high water-holding capacity based on its highly porous nanofibrillar structure allows BC to incorporate and to release substances very fast, thus being suitable for the preparation of skincare masks. Aims The preparation and characterization of cosmetic masks based on BC membranes and active cosmetics. Methods The masks were prepared by the simple incorporation of the cosmetic actives into BC membranes, used as a swelling matrix. The masks were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), sensory tests, and skin moisture tests on volunteers. Results The results of sensory tests revealed the good performance of BC, being considered effective by the panel of volunteers, specially for adhesion to the skin (7.7 at the score scale), and improvement of the skin moisture (the hydration effect increased 76% in 75% of the volunteers that used vegetable extract mask formulation [VEM]), or a decrease in skin hydration (80% of the volunteers showed 32.6% decrease on skin hydration using propolis extract formulation [PEM] treatment), indicating the BC nanofiber membranes can be used to skincare applications. Conclusion The results demonstrate the BC can be used as an alternative support for cosmetic actives for skin treatment.

In this work we explored the fabrication of flexible and transparent hybrids of silk fibroin (SF) and epoxy-modified siloxane for photonic applications. It is well-known that regenerated SF solutions can form free-standing films with high transparency. Although SF has a restricted number of chemically reactive side groups, the main issues of as-cast pristine SF films regard the high solubility into aqueous media, brittleness, and low thermal stability. The design of SF films with enhanced functionality but high transparency triggers new opportunities on a broader range of applications in biophotonics. Here we present a simple, functional, yet remarkably versatile hybrid material derived from silica sol-gel process based on SF protein and (3-glycidyloxypropyl)trimethoxysilane (GPTMS), an organically modified silicon-alkoxide owning a reactive terminal epoxy group. Specifically, we investigated the effect of the addition of GPTMS into SF solutions on the processability, morphology, crystallinity, and mechanical and optical properties of the resulting hybrid films. Highly transparent (ca. 90%) and flexible free-standing hybrid films were achieved. Cell viability assays revealed that the hybrid films are noncytotoxic to rat osteoblast cells even at high GPTMS content (up to 70 wt %). The hybrid films showed enhanced thermal stability and were rich in organic (epoxy) and inorganic (silanol) functional groups according to the content of GPTMS. We also evaluated the successful preparation of high-quality optical red emissive SF hybrid films by loading YVO

Made available in DSpace on 2018-12-11T17:15:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01 Bacterial cellulose/carboxymethylcelullose (BC/CMC) biocomposites with different DS-CMC (DS from 0.7 to 1.2) were developed in order to evaluate their impact as a drug delivery system. Biocomposites were loaded with methotrexate (MTX) as an alternative for the topical treatment of psoriasis. Scanning electron microscopy and atomic force microscopy showed that the CMC coated the cellulose nanofibers, leading to the decrease of the elastic modulus as the DS of CMC increased. BC/CMC0.9 exhibited the lower liquid uptake (up to 11 times lower), suggesting that the more linear structure of the intermediate substitute CMC grade (0.9) was able to interact more strongly with BC, resulting in a denser structure. All samples showed a typical burst release effect in the first 15 min of test, however the BC/CMC0.9 biocomposite promoted a slight lowering of MTX release rates, suggesting that the DS of CMC can be considered the key factor to modulate the BC properties. University of Araraquara – U NIARA Institute of Chemistry São Paulo State University – UNESP Interdisciplinary Laboratory of Advanced Materials Centro de Ciências da Natureza- CNN Federal University of Piaui – UFPI Group ‘Materials + Technologies’ (GMT) Department of Chemical and Environmental Engineering Engineering College of Gipuzkoa University of the Basque Country (UPV/EHU) Department of Drugs and Pharmaceuticals School of Pharmaceutical Sciences SãoPaulo State University – UNESP Institute of Chemistry São Paulo State University – UNESP Department of Drugs and Pharmaceuticals School of Pharmaceutical Sciences SãoPaulo State University – UNESP

Made available in DSpace on 2018-11-28T15:26:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-05-01 Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) FINEP (CT-INFRA) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) New glass compositions were investigated in this specific proportion (90-x)TeO2-10GeO(2)-xPbF(2) in order to study the influence of lead fluoride content on the thermal, structural and optical properties. Glass samples with x = 5 to 30% were prepared by melt-quenching method. Thermal characterizations by DSC allowed to identify a clear decrease of the glass transition temperature as well as a very distinct crystallization behavior for higher PbF2 contents. Raman spectroscopy suggests a progressive PbF2 incorporation with conversion of TeO4 to TeO3 units related with the modifier behavior of PbF2 in the glass network. X-ray diffraction patterns of crystallized samples support these results since crystalline TeO2 was detected for lower PbF2 contents whereas lead tellurite Pb2Te3O7 was identified for the most lead fluoride concentrated sample. UV-Vis-MR absorption spectra are in agreement with a progressive increase of the optical bandgap with lead fluoride concentration. Emission spectra of Eu3+ doped samples also pointed out a progressive structural change around Eu3+ ions with more symmetric sites. Finally, experimental lifetimes, Judd-Ofelt parameters and quantum efficiencies were obtained from these samples and exhibited a strong dependency of the lead fluoride contents, suggesting that these new fluorotellurite glasses are interesting hosts for rare earth ions. (C) 2017 Elsevier B.V. All rights reserved. Univ Fed Alfenas, Grp Quim Mat, Campus Pocos de Caldas, Pocos De Caldas, MG, Brazil Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Quim, Av Bandeirantes 3900, BR-14040901 Ribeirao Preto, SP, Brazil Univ Estadual Paulista, Inst Quim, Araraquara, SP, Brazil Univ Estadual Paulista, Inst Quim, Araraquara, SP, Brazil FAPEMIG: CEX-APQ-01410-12 CNPq: 552225/2011-8