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Thais RD Paini,1 Joana YT Uchimura,1 Francielle Sato,2 Antonio Medina Neto,2 Eliana LT Shimauti,3 Mauro L Baesso,2 Mirian M Hidalgo,1 Marcia LA dos Santos,4 Isolde TS Previdelli,4 Renata C Pascotto1 1Department of Dentistry, State University of Maringa, Maringá, PR, Brazil; 2Department of Physics, State University of Maringa, Maringá, PR, Brazil; 3Department of Clinical Analysis and Biomedical Science, State University of Maringa, Maringá, PR, Brazil; 4Department of Statistics, State University of Maringa, Maringá, PR, BrazilCorrespondence: Renata C Pascotto, Department of Dentistry, State University of Maringa, Av. Mandacaru 1.550, Maringá, PR, 87080-000, Brazil, Tel +55 44 99820215, Fax +55 44 30319051, Email renatapascotto@gmail.comBackground: The use of discolored teeth is required to test whitening products, and it is difficult to obtain them, given their scarcity.Objective: To present a technique for in vitro darkening of extracted teeth simulating pulpal necrosis discoloration.Materials and Methods: Hemolysates I and II from human blood were subjected or not to laser irradiation (442 nm) for 1 h. The concentration of oxyhemoglobin (O2Hb) was analyzed by ultraviolet/visible spectroscopy, and the conversion of O2Hb to methemoglobin (MetHb) by transmission spectroscopy was assessed immediately and after 3 and 40 days. For darkening evaluation, bovine incisors were divided into two groups (n = 25), and their pulp chambers were filled with hemolysate solution II (HSII) and hemolysate II solution + laser (HSII+L). After storage in artificial saliva for 40 days at 37°C, color changes were measured by a colorimeter and ΔE was compared with the NBS parameters. Data were analyzed using a mixed linear model (α=5%).Results: HSII+L presented the lowest O2Hb and higher MetHb. The conversion of O2Hb to MetHb in HSII+L was 42% higher than in HSII. Both groups were effective in darkening the teeth, according to the NBS. Darkening stabilized from day 35. HSII promoted a marked color difference.Conclusion: The proposed technique was effective in darkening the extracted teeth simulating necrosis discoloration for in vitro models.Graphical Abstract: Keywords: teeth, blood, colorimetry, hemoglobin, spectroscopy

This study aims to evaluate the opalescence (OP) and color stability of composite resins over a period of 180 days and to compare composite resins’ OP with enamel’s OP. Twenty human enamel specimens (5.0 × 0.3 mm) and 9 specimens (10.0 × 1.0 mm) of 10 colors of 4 different composite resins (3 M ESPE, FGM, Ivoclar-Vivadent, Miscerium) and one brand of adhesive (3 M ESPE) were made. The results were obtained by measuring the reflectance and transmittance spectra in the visible region. After baseline measurement, composites and adhesive were analyzed after 2, 7, 30, 60, 120, and 180 days. The Lab color coordinates were used in the calculations of the OP parameter and color differences in the CIELab and CIEDE2000 methods. The data were analyzed statistically. The materials tested showed variation and an increase in OP over time. The OP found for enamel was 18.06 ± 2.99, and some resins showed higher results. There was a strong correlation between the coordinate b*T and the OP over time. Enamel Plus was the only one material that presented no color changes during all periods in both color analyses. Filtek Z350 XT, AT, and BT did not show differences in any time when analyzed by CIELAB. The OP of most composite resins changed during the period of 180 days and was different from the OP of tooth enamel. In general, composites demonstrated small color changes over the period tested, being this characteristic material dependent. Natural teeth present different optical properties. Composite resins restorations should present properties similar to natural teeth and it is important that characteristics like color and opalescence remain stable over time.

Objective To evaluate the early stages of the setting process of chemically activated restorative glass-ionomer cements (GICs). Material and methods Five GICs were evaluated (n = 5): Equia Forte (GC), Equia Forte HT (GC), Ketac Universal (3M ESPE), Maxxion R (FGM) and Riva Self Cure (SDI) by Thermography, Fourier Transform Infrared Attenuated Total Reflectance Spectroscopy (FTIR-ATR) and Gillmore needle indentation mechanical testing. The FTIR-ATR spectra showed the formation of metal carboxylates within the cements and enabled the stabilization time (ST) to be determined and the thermographic camera measured the temperature field images in the sample. Data were statistically analyzed by ANOVA and Tukey–Kramer (α = 5%). Results The Gillmore needle test showed that the order of hardening was opposite to the order of ST values determined by FTIR. The results with the thermographic camera showed two stages of temperature variation, which coincided with the evolution of specific infrared bands. The exception was Maxxion R, which showed only a single step change in temperature. Conclusion The early stages of the GIC setting reaction show temperature changes, both endothermic and exothermic, at specific times, confirming the occurrence of individual chemical reactions. The early setting involves reactions other than carboxylate formation. Significance: This study gives further detail of the early stages of the setting of GICs, and past research regarding the setting reaction of GIC.

Konjac glucomannan (KGM) is extracted from Amorphophallus konjac tuber and composed of β-1,4 linked D-mannose and D-glucose. We aimed to produce and characterize KGM-based powders manufactured from dried (55°C-KF55 and 75°C-KF75) konjac tubers and compare to a commercial konjac glucomannan (CKG) powder. Structural characteristics on molecular, compositional, and microstructure levels as well as rehydration properties were assessed. Both compositional analysis as well as FTIR and 13C MAS NMR spectral analysis demonstrated a higher amount of protein than KF55 sample. The ratio between the two monomer units (D-mannose and D-glucose) was 1.6:1 in KF75, whereas it was 1.4:1 and 1.2:1 for KF55 and CKG, respectively, indicating slightly higher Man:Glc ratios in the KF samples. Decreased rehydration properties and flow index behavior (in solution) were observed in the konjac flours. Thus, differences were significant; konjac flours also presented good functionality, thereby, a good alternative to be used as hydrocolloid in food formulations.

Palmarosa essential oil (PEO) is an alternative to synthetic fungicides to control the contamination by food-deteriorating fungi, such as Aspergillus nomius. Nonetheless, the low long-term stability and volatility hamper its utilization. Thus, this study aimed to develop nanostructured lipid carriers (NLCs) containing PEO to improve its stability and consequently prolong the activity against A. nomius. A mixture design was applied to find the best preparation conditions for antifungal activity. The characterization analyses included size measurements, zeta potential (ζ-potential), entrapment efficiency (EE), and antifungal activity (by inhibition of mycelial growth (IMG) and/or in situ test (pre-contaminated Brazil nuts) tests). The nanocarriers presented particle sizes smaller than 300 nm, homogeneous size distribution, ζ-potential of −25.19 to −41.81 mV, and EE between 73.6 and 100%. The formulations F5 and F10 showed the highest IMG value (98.75%). Based on the regression model, three optimized formulations (OFs) were tested for antifungal activity (IMG and in situ test), which showed 100% of inhibition and prevented the deterioration of Brazil nuts by A. nomius. The preliminary stability test showed the maintenance of antifungal activity and physicochemical characteristics for 90 days. These results suggest a promising system as a biofungicide against A. nomius.

The interaction of the steviol and its glycosides (SG), steviolbioside, and rebaudioside A, with bovine serum albumin (BSA) was studied by absorption and fluorescence spectroscopy techniques alongside molecular docking. The stevia derivatives quenched the fluorescence of BSA by a dynamic quenching mechanism, indicating the interaction between the stevia derivatives and BSA. The binding constant (Kb) of steviol was 100-1000-fold higher than those of SG. The stevia derivative/BSA binding reaction was spontaneous and involved the formation of hydrogen bonds and van der Waals interactions between steviol and steviolbioside with BSA, and water reorganization around the rebaudioside A/BSA complex. Molecular docking pointed out the FA1 and FA9 binding sites of BSA as the probable binding sites of steviol and SG, respectively. In conclusion, steviol enhanced hydrophobicity and small size compared to SG may favor its binding to BSA. As steviol and its glycosides share binding sites on BSA with free fatty acids and drugs, they may be competitively displaced from plasma albumin under various physiological states or disease conditions. These findings are clinically relevant and provide an insight into the pharmacokinetics and pharmacodynamics of the stevia glycosides.

Background Some composite resins contain luminophorous agents in order to reproduce tooth fluorescence. The objective of this study was to compare the fluorescence spectra emitted by composite resins with those of human enamel and dentin, and their emission behaviour after a 90-day natural aging period. Material and Methods Nine shades of the composite resins Z350XT/3M (XT), Opallis/FGM (OP) and Empress Direct/Ivoclar-Vivadent (ED) were analyzed. Five specimens (10.0 mm x 2.0mm) were fabricated for each shade. Enamel (5.0 mm x 0.30 mm) and dentin (5.0 mm x 1.0 mm) specimens were obtained from sound human third molars. Fluorescence spectra of human dentin and enamel as well as the composite specimens immediately after fabrication were measured at the excitation peaks of 375, 395 and 410 nm. To assess composite resin fluorescence intensity changes over time, measurements were conducted after 30, 60 and 90 days, at 395 nm. Differences in fluorescence intensity over time were analyzed with ANOVA and Tukey’s test (p

The world around us is composed of images that often need to be translated into words. This translation can take place in parts, converting regions of the image into textual descriptions what is also known as dense captioning. By doing so, the information present in this region is converted into words expressing the way objects relate to each other. Computational models have been proposed to perform this task in a similar way to human beings, mainly using deep neural networks. As the same region of the image can be described in several different forms, this study proposes to use the Abstract Meaning Representation (AMR) in the generation of descriptions for a given region. We hypothesize that by using AMR it would be possible to extract the meaning of the text and, as a consequence, improve the quality of the sentences produced by the models. AMR was investigated as a semantic representation formalism evolving the so far proposed models that are based only on purely natural language. The results show that the models trained with sentences in the form of AMR led to better descriptions and the performance achieved was superior in almost all evaluations.

Photodynamic therapy (PDT) may have topical indications. In those cases it is important for a topical photosensitizer to penetrate into the tissue to which it has been applied. This study aimed to compare the penetration of two different concentrations of erythrosine into intact and in vitro decayed dentin samples.This in vitro study evaluated erythrosine (0.3 and 5%) penetration into sound (intact) and decayed dentin. A total of 11 dentin discs were prepared and divided into two equal halves, in order to keep one half sound while the other half was submitted to sterilization and an in vitro demineralization model for 5 days. Before erythrosine application, the organic and inorganic composition of all samples was evaluated by Fourier Transform Raman spectroscopy, and after erythrosine application for 30 min, the penetration depth was determined by Photoacoustic spectroscopy technique.The results indicated that 0.3% erythrosine showed a higher penetration depth into sound dentin (p = 0.002); and 5% erythrosine higher penetration into decayed dentin (p 0.001). However considering clinical parameters, no statistically significant difference was found between any of the conditions tested.Erythrosine demonstrated ability to penetrate into dentin, irrespective of sound or decayed condition. Photoacoustic spectroscopy can be considered a method for estimating the penetration into hard tissues, and in conjunction with Raman spectroscopy, these are effective methods for evaluating the spectral response of dentin. Considering that erythrosine is capable of penetrating into decayed dentin, clinical trials are needed to test the effectiveness of this photosensitizer in Photodynamic therapy and Antimicrobial Photodynamic therapy.

Ethanol steam reforming for hydrogen production was evaluated using Cu–Ni/NbxOy catalyst prepared by ion exchange (IE), wet impregnation (WI) and co-precipitation (CP). The catalysts were characterized by textural analysis, chemisorption of H2 and N2O for metallic area determination, XDR (calcined and in situ reduced samples), TPR-H2, TPD-NH3, MET/EDX e TPO-O2. Differences in crystal structure and metal-support interaction have altered the reducibility of the catalysts, besides metal surface area and crystallite size of Cu and Ni. The catalytic tests, using ethanol:water molar ratio of 1:10, temperature of 450 and 500 °C, demonstrated high H2 yield and stability, except for the IE catalyst at 500 °C, which favored the ethylene formation by ethanol dehydration. The main route for H2 obtainment in all cases was ethanol decomposition. The temperature increasing up to 500 °C favored the by-product CH4 reforming. The weakest metal-support interaction on WI catalyst provided the fully reduced metal phase, however, support characteristics achieved by this preparation method led to the filamentous coke formation. TEM images showed that different crystalline structures of the support modified the mechanism of the reaction and consequently the type of coke deposited on the surface. The CP catalyst showed low coke deposition and no metal sintering, stoichiometric H2/CO2 ratio, less than 5% of CH4, and no CO, which makes it the best candidate for hydrogen production by ethanol steam reforming.

OH−-free calcium aluminosilicate (CAS) glasses present interesting properties for optical and photonic device applications. Optical properties have direct relation with SiO2 content in the glass composition. However, there is an interval (10–25 wt%) of SiO2 content which was not capable forming glassy-phase in previous works. In this study, the glass-forming ability was investigated as a function of the SiO2 content within this specific interval. The proposal was to use glass frits as precursor material to overcome this difficulty. Glass frits were produced from CAS glasses with 7 and 34 wt% of SiO2. These compositions were chosen by having a well established production procedure. Using glass frits, samples with concentration of 10, 15, 20 and 25 wt% of SiO2 were produced. With the exception of 25 wt%, all the samples vitrified, X-ray diffraction measurements reveal the amorphous nature of the prepared glasses. Raman spectroscopy and differential thermal analysis show that the samples present formation of a single phase in each sample, and these phases are between the limit phases obtained in the 7 and 34 wt% samples. In addition, mechanical, thermal, optical and thermo-optical properties of the samples were accessed. The results show that glass frits method is an alternative solution for the glass production, and, the process does not affect the sample properties comparing with the standard procedure.

Noble metal embedded glasses have been studied as promising candidates for a variety of technological applications, mainly due to their ability to enhance rare earth luminescence properties. In this work, Ag:Eu-co-doped calcium boroaluminate glasses were prepared and submitted to further heat treatment to form different Ag species. The optical and luminescence properties were investigated in terms of heat treatment times. Absorption spectra showed a successful Eu and Ag ion incorporation in the host, as well as Ag nanoparticle precipitation induced by heat treatment. Upon UV-light excitation, the co-doped glasses exhibited an intense wide emission band centered at about 500 nm, attributed to molecule-like silver species, which combined with the Eu

Objective To investigate the chemical interactions between a high-viscosity glass ionomer cement (GIC) (KetacTM Molar Easymix, 3M ESPE, Seefeld, Bavaria, Germany) and human dentin. It was also analyzed the dynamics of GIC setting mechanism based on the time intervals required for the GIC and the GIC mixed with dentin to achieve stability. Material and Methods Each constituent of GIC – powder (P) and liquid (L) – and powdered dentin (D), as well as the associations P+L, D+L, and P+L+D in the concentrations of 29%, 50%, 65%, 78%, 82%, and 92% of GIC were analyzed with Fourier transform infrared (FTIR) and Raman spectroscopy. Results New optical absorption bands and/or Raman bands, which were not present in P, L, or D, were observed in the associations. The concentrations of 29% and 50% of GIC showed higher interaction, revealing that the amount of dentin influences the formation of new optical absorption or scattering bands. FTIR bands showed that the setting time to achieve bond stability was longer for the high-viscosity GIC (38±7 min) than for the sample with 29% of GIC (28±4 min). Conclusions The analysis revealed the formation of new compounds or molecular rearrangements resulting from the chemical interactions between GIC and dentin. Moreover, this study provides an effective method to evaluate the dynamics of the setting mechanism of GICs.

International audience; Noble metal embedded glasses have been studied as promising candidates for a variety of technological applications, mainly due to their ability to enhance rare earth luminescence properties. In this work, Ag:Eu-co-doped calcium boroaluminate glasses were prepared and submitted to further heat treatment to form different Ag species. The optical and luminescence properties were investigated in terms of heat treatment times. Absorption spectra showed a successful Eu and Ag ion incorporation in the host, as well as Ag nanoparticle precipitation induced by heat treatment. Upon UV-light excitation, the co-doped glasses exhibited an intense wide emission band centered at about 500 nm, attributed to molecule-like silver species, which combined with the Eu3+ characteristic emission reaches a white light resultant emission. A new excitation band for Eu3+ at 335 nm and a silver luminescence lifetime decrease suggest an energy transfer process from molecule-like Ag to Eu3+ as being responsible for the enhanced PL properties in these glasses. An appropriate combination of a violet LED with the sample emission provides a route to achieve the ideal white light CIE color parameters. The relevant quality color results qualify these glasses as phosphors with high potential for white light emitting devices.

To investigate the relationship between physicochemical interactions of resin luting cements with dentine and retention of fibre posts in root canals.Retention of fibre posts (RelyX Fiber Post) was assessed by the pull-out method. The diffusion zone of the cements and their chemical interaction with dentine were estimated by micro-Raman spectroscopy. Resin luting cements employing etch-and-rinse (Rely X Ultimate and Variolink II), self-etch (Rely X Ultimate and Panavia F2.0), or self-adhesive (RelyX Unicem 2) modes were investigated. Data were analyzed by analysis of variance followed by Tukey HSD tests.The retention of the fibre posts decreased in the following order: RelyX Ultimate, etch-and-rinse modeRelyX Unicem 2≥RelyX Ultimate, self-etch mode≥Panavia F2.0≥Variolink II (p0.05). One of the etch-and-rinse mode cements presented the deepest diffusion zone, while the other, along with the self-adhesive cement, produced the shallowest zone. Cements used in the self-etch mode showed intermediary diffusion into dentine (p0.05). All resin luting cements showed some degree of chemical interaction with dentine, the highest recorded for RelyX Ultimate used in the etch-and-rinse mode and the lowest for Panavia F2.0 (p0.05). The retention of fibre posts in the root canal could be attributed neither to the mode of interaction of the luting cements with dentine nor to their ability to diffuse into dentine.Chemical interaction between the resin luting cement and the dentine paired with adequate post pretreatment contribute positively to the retention of fibre posts.

This study focused on evaluating a technique for the psyllium husk mucilage (PHM) purification with simultaneous microencapsulation of curcumin. PHM was extracted with water and purified with ethanol. For the mucilage purification and simultaneous microencapsulation, an ethanolic solution of curcumin was used. After dehydration, the samples were analysed by instrumental techniques and evaluated for thermal stability. The presence of curcumin in the solution did not impair the yield of precipitated polysaccharide. Interactions of the dye and carbohydrates were confirmed by displacement of peaks in FT-IR and FT-Raman spectroscopy. The onset temperature of degradation of microcapsules was superior to that of curcumin. Thermal stability in solution at 90°C also improved. After 300 minutes of heating, the microcapsules had a remnant curcumin content exceeding 70%, while, in standard sample, the remaining curcumin content was 4.46%. Thus, the developed technique was successful on purification of PHM and microencapsulation of curcumin.

Curcumin was complexed with β-CD using co-precipitation, freeze-drying and solvent evaporation methods. Co-precipitation enabled complex formation, as indicated by the FT-IR and FT-Raman techniques via the shifts in the peaks that were assigned to the aromatic rings of curcumin. In addition, photoacoustic spectroscopy and X-ray diffraction, with the disappearance of the band related to aromatic rings, by Gaussian fitting, and modifications in the spectral lines, respectively, also suggested complex formation. The possible complexation had an efficiency of 74% and increased the solubility of the pure colourant 31-fold. Curcumin–β-CD complex exhibited a sunlight stability 18% higher than the pure colourant. This material was stable to pH variations and storage at −15 and 4°C. With an isothermal heating at 100 and 150°C for 2h, the material exhibited a colour retention of approximately 99%. The application of curcumin–β-CD complex in vanilla ice creams intensified the colour of the products and produced a great sensorial acceptance.

Pure and Co-doped ZnO nanoparticles were synthesized with different cobalt levels (1–10 mol%) via adapted sol–gel method using water as solvent and characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy and photoacoustic absorption spectroscopy. The results showed that all the samples have hexagonal wurtzite structure, with no evidence of any secondary phases until 10 mol% of the dopant. The average crystallite size of the samples was in the range of 25–50 nm, do not showing significant differences with the increase of the dopant level. However, the band gap energy of the nanoparticles decreases from 2.98 eV (pure ZnO) to 1.95 eV (10 mol% of Co). The photocatalytic activity of the samples was evaluated on the removal of methylene blue under visible light irradiation, which revealed an efficiency reduction by Co-doping ZnO. The antibacterial property was carried out indicating activity of the prepared samples against gram-positive bacteria.

Stability of potassium norbixinate and curcumin by microencapsulation with maltodextrin DE20 and freeze-drying was evaluated as a function of exposition to light, air, different pH, water solubility, and in food applications. The best results were obtained with microencapsulated potassium norbixinate 1:20, which, when vacuum-packed and in the presence of natural light, showed color retention of 78%, while microencapsulated curcumin 1:20 showed color retention of 71%. Differential scanning calorimetry and thermogravimetry provided an indication of interaction between colorants and maltodextrin. Photoacoustic spectroscopy (PAS) showed that free and microencapsulated colorants exhibited high rates of absorption throughout the measured spectral region. This work evidenced that the freeze-drying process is favorable for microencapsulation of curcumin by maltodextrin, providing improved solubility to the microencapsulated colorant. Both microencapsulated colorants showed relevant results for use in a wide range of pH and food applications. The PAS technique was useful for the evaluation of the stability of free and microencapsulated colorants.

This study evaluated the temperature and pressure effects in the extraction of the sunflower seed (Heliantus annuus L.) oil using as solvents carbon dioxide and propane. The experiments were performed at the temperature range of 30–60 °C and pressure range of 8–25 MPa. A factorial experimental design 22 with triplicate at the central point was effectuated in order to evaluate the influence of this two variable in the mass of oil extracted ratio by mass of solvent consumed. Analysis of oxidative stability and chemical composition of the oil were performed as well. The best extraction for sunflower seed oil was obtained with propane as solvent, because of the high extraction yield in comparison with carbon dioxide. The quantity of fatty acids detected in the samples of oil extracted with carbon dioxide and propane were similar and presented a high time of oxidative induction than the sample extracted with hexane. However, the oil extract obtained with propane showed a high concentration of vitamin E (α-tocopherol). To describe the extraction kinetic was used the Sovova mathematical model, which showed a high precision in all the conditions investigated.

This work describes the preparation of composite films of zinc oxide (ZnO) embedded in a covalent copolymer substrate of triethylene glycol dimethacrylate and poly(ethyleneglycol) diacrylate. The ZnO-embedded copolymer was produced in situ from the reaction of a doped precursor zinc bis(2-thenoyltrifluoroacetonate) [Zn(TTA)2] in a hydrazine hydrate reflux system. The in situ production of ZnO nanoparticles with excellent optical qualities embedded in the copolymer substrate was demonstrated to be an effective approach to fabricating new advanced materials for use as a protective barrier that blocks UV rays.

In this work, we have studied the optical and thermal properties of Nd-doped phosphate glass matrix. The studied samples have concentration ranging from 0.5 to 5 wt% of Nd 2 O 3 . Here we report the measurements of fluorescence quantum efficiency, η , obtained through the thermal lens technique using a reference sample. Also, the refractive index, n , specific heat, c p , mass density, and the thermal diffusivity and conductivity measurements were performed. The knowledge of these characteristics as a function of neodymium concentration is very important to design optical devices, especially high power solid state lasers.

In the present work, the rear photoacoustic signal technique is used to determine thermal properties of human nails. The aging process of the human nail is analyzed through its thermal diffusivity and specific heat and using these results, thermal conductivity and thermal effusivity is determined. The study in vitro of this natural polymer showed a minimum for thermal properties to age about 20 years and an increase and possible saturation of them for ages over 50 years. The minimum value found for thermal diffusivity was close to 10 x 10 -4 cm 2 s -1 with saturation near 18 x 10 -4 cm2 s -1 . Thermal conductivity and effusivity presents the same behavior.

The search for new energy sources has impulsed hydrocarbon production from methanol and ethanol over ZSM-5 zeolites. Iron incorporation by different methods has led to a variety of chemical applications. Thus, hydrocarbon production from ethanol was evaluated using a [Fe,Al]ZSM-5 zeolite which was synthesized without nitrogenated templates, using ethanol and crystallization seeds and partially substituting iron for aluminium in the reaction mixture. Characterization was done by X-ray diffraction (XRD), Fourier-transform infra-red spectroscopy (FTIR), temperature programmed reduction (TPR), temperature programmed desorption of ammonia (TPD), nitrogen adsorption, electron paramagnetic resonance (EPR) and photoacoustic spectroscopies. Iron content in the synthesized samples varied from 0.02 to 1.82%. The obtained samples were used for the ethanol transformation, producing hydrocarbons from ethene to aromatics. Maximum production of liquid hydrocarbons was achieved with the zeolite with 0.5% iron. The procedure for obtaining the acid form of the zeolites, involving ammonium exchange and calcinations, has changed the iron species, probably with extraction from the structure, migration and agglomeration.

Paracoccidioidomycosis is the most important systemic mycosis in Latin America. The main entrance of the fungus is the airway. It primarily occurs in the lung, but in its disseminated form may affect any organ. The liver is one of the organs afflicted by this disease and its homeostasis may be impaired. The aim of the present study was to evaluate the evolution of paracoccidioidomycosis in the liver of Swiss mice and correlate morphological factors with the expression of gp43 and with physicochemical analysis via FT-Raman of the infected organ. According to colony forming unit (CFU) and granuloma counting, the first and second weeks were the periods when infection was most severe. Tissue response was characterized by the development of organized granulomas and widespread infection, with yeasts located within the macrophages and isolated hepatocytes. The gp43 molecule was distributed throughout the hepatic parenchyma, and immunostaining was constant in all observed periods. The main physicochemical changes of the infected liver were observed in the spectral ranges between 1700-1530 cm(-1) and 1370-1290 cm(-1), a peak shifting center attributed to phenylalanine and area variation of -CH2 and -CH3 compounds associated to collagen, respectively. Over time, there was a direct proportional relationship between the number of CFUs, the number of granulomas and the physicochemical changes in the liver of mice infected with Paracoccidioides brasiliensis. The expression of gp43 was similar in all observed periods.

This study analyzed the diffusion of two resin luting agents (resin cements) into dentin, with the aim of presenting an analytical method for estimating the thickness of the diffusion zone. Class V cavities were prepared in the buccal and lingual surfaces of molars (n=9). Indirect composite inlays were luted into the cavities with either a self-adhesive or a self-etch resin cement. The teeth were sectioned bucco-lingually and the cement–dentin interface was analyzed by using micro-Raman spectroscopy (MRS) and scanning electron microscopy. Evolution of peak intensities of the Raman bands, collected from the functional groups corresponding to the resin monomer (C─O─C, 1113 cm(−1)) present in the cements, and the mineral content (P─O, 961 cm(−1)) in dentin were sigmoid shaped functions. A Boltzmann function (BF) was then fitted to the peaks encountered at 1113 cm(−1) to estimate the resin cement diffusion into dentin. The BF identified a resin cement–dentin diffusion zone of 1.8±0.4 μm for the self-adhesive cement and 2.5±0.3 μm for the self-etch cement. This analysis allowed the authors to estimate the diffusion of the resin cements into the dentin. Fitting the MRS data to the BF contributed to and is relevant for future studies of the adhesive interface.

This work is aimed to evaluate the application of photoacoustic spectroscopy (PAS) in the characterization of inclusion complexes of benzophenone-3 (BZ-3) and hydroxypropyl-β-cyclodextrin (HPCD) and to analyze the ex vivo percutaneous penetration of sunscreens and their reaction with the skin. The formation of inclusion complexes of BZ-3 and HPCD was performed by co-precipitation in stoichiometric ratios of 1:1 and 1:2. Thermal analysis and PAS characterized these inclusion complexes, and they indicated that the stoichiometric ratio of 1:2 was best. Sunscreen formulations were prepared and applied on the ears of rabbits. PAS suggested that the formulation with the complex resulted in lower penetration of BZ-3. Histological analysis demonstrated that the use of the formulation with BZ-3 was associated with an increase in the comedogenic effect and the presence of acanthosis, while no such effect was found in the formulation with the complex. The formulation with the BZ-3-HPCD complex is a promising strategy for improving the photoprotective effect of BZ-3. PAS can be used in the study of inclusion complexes with cyclodextrins and the evaluation of the percutaneous penetration of sunscreen formulations. Further tests are being conducted using PAS to monitor in vivo changes in the optical absorption spectra of formulations and to investigate their photostability.

Curdlan is a linear, neutral polysaccharide composed of repeated β-(1,3)-linked glucose residues, and is considered a food fiber. It is of special interest due to its gel formation properties, which allow it to be used as a gelling agent to improve the texture, water retention capacity and thermal stability of various food products. When heated, its aqueous suspension forms two types of gel: low-set gel, which is thermo-reversible and obtained by heating at temperatures between 55 and 60 °C, followed by cooling, and high-set gel, which is thermo-irreversible and obtained by heating at over 80 °C. Because of their high firmness and stability, curdlan gels are used in the manufacture of pasta, sauces, frozen and canned foods, and are biodegradable, edible and non-toxic to humans and the environment. Although curdlan is a linear polysaccharide, its conformational structure has a great influence on its dispersion and gelling properties. As the recovery of the medium and the purification of the polysaccharide can influence its conformational structure, the structural study of curdlan, as well as its physicochemical and technological properties, is essential for its more effective use in the food industry. Considering the interest in curdlan due to its dispersion, viscosity and gelling properties, the present study aimed to evaluate the structure, morphology and physical-chemical and technological properties of curdlan produced by Agrobacterium sp. IFO 13140, compared to commercial curdlan. A further objective of this study was the application of curdlan in foods, such as homemade pasta and yogurt. The strain of Agrobacterium sp. IFO 13140 acquired in lyophilized form was reactivated and added to the curdlan production medium using glucose as a carbon source. Two methodologies were used to recover the polysaccharide: pre-gelation and precipitation. In both methodologies the curdlan was solubilized with NaOH 3 mol/L solution. Subsequently it was neutralized with HCl 3 mol/L (pre-gelation) or with water (precipitation). The commercial curdlan was also subjected to the pre-gelation process and entitled pre-gelled commercial curdlan. The methodologies used to recover the curdlan were related to their functional properties. The commercial and pre-gelled commercial curdlans and the curdlan produced by Agrobacterium sp. IFO 13140 (recovered by both methods) were evaluated for their structure, morphology, physicochemical properties and dispersion and gelation capacity. After this step, the two curdlans submitted to the pre-gelation process were used for the preparation of the dispersions and gels. The mechanisms of formation of the curdlan gels were examined by FT-IR and FT-Raman spectroscopy, and their formation temperatures were evaluated by DSC and TGA analyzes. The curdlans submitted to the pre-gelation process, as well as the commercial curdlan, were evaluated for their technological properties of water absorption and oil and water solubility. Subsequently, they were applied in homemade pasta and yogurt in proportions of 1% and 1.5%, in relation to the quantities of flour and milk, respectively. The cooking characteristics and the texture profile of the pasta were evaluated. Rheology, texture and syneresis were evaluated from the yoghurt. FT-Raman analysis of the commercial and pre-gelled commercial curdlans and the curdlan produced by Agrobacterium sp. IFO 13140 (recovered by the pre-gelation and precipitation methods) revealed a structural similarity between all the samples, meaning that the curdlan produced by the microorganism has a similar structure to the commercial curdlan, and that the method used for the recovery of the polysaccharide does not influence its structure. However, scanning electron microscopy data revealed that both the drying method and the recovery method significantly affected the shape and size of the curdlan granules. The commercial (atomized) sample had large granules with concavities. The other samples (lyophilized) exhibited smaller particles. Also, the two curdlans submitted to the pre-gelation process had the smallest particle size, which may have influenced their improved dispersion in water. The results obtained in the physical-chemical analyzes revealed that the commercial curdlan had the highest carbohydrate content, followed by that produced by the microorganism and recovered by precipitation, demonstrating the greater purity of these samples. The curdlans submitted to the pre-gelation process presented a lower carbohydrate content, due to the salt incorporated in this process (calculated by the sodium content). When the characteristics of the dispersion and gelation of the curdlans were evaluated, the pre-gelled samples dispersed easily and homogenously in water, and developed a firm and homogenous gel. The commercial curdlan did not easily form a homogeneous dispersion or gel. The same was true for the curdlan produced by Agrobacterium sp. IFO 13140 recovered by precipitation, which did not gel due to the absence of sodium. Therefore, the thermal, rheological and gel strength analyzes were performed using the pre-gelled curdlans only. The commercial curdlan was compared with the pre-gelled curdlans in terms of the technological properties of absorption of water and oil and solubility in water, as well as application in foods. The FT-IR and FT-Raman analyses revealed a structural similarity between the commercial curdlan and the curdlan produced by Agrobacterium sp. IFO 13140. It was not possible to identify the structural variations resulting from the gel formation using the FT-IR technique. However, the FT-Raman technique did identify these variations, allowing variations related to the hydrogen bonding and hydrophobic interactions to be observed. The formation temperatures of both gels were determined by DSC. The samples revealed an endothermic peak between 40 and 55 °C, due to the swelling of the curdlan, and another peak between 70 and 80 °C due to hydrophobic interactions between the molecules. Additionally, rheology and gel strength analysis revealed that the curdlan produced by Agrobacterium sp. IFO 13140 had a greater thickening capacity than the pre-gelled commercial curdlan. However, the latter exhibited a greater gelling capacity, resulting in a gel with a 17% greater strength and a six times greater elastic modulus at 95 °C. This difference between the gelling properties of the curdlans is due to their different degrees of polymerization (DPn) or molecular mass, as while the commercial sample had a DPn of 334 ± 8, the sample produced by the microorganism had a DPn of 232 ± 10, corresponding to molecular masses of 54000 and 38000, respectively. When the water and oil absorption and water solubility properties of the commercial curdlan and the curdlans from the pre-gelation process were evaluated, the low water solubility and absorption of all the samples were confirmed. However, the curdlans submitted to the pre-gelation process presented high oil absorption values that were greater than those of water absorption, making these ingredients useful in the structural interactions of various foods. The use of curdlans submitted to the pre-gelation process in pasta and yoghurt improved the texture characteristics of these products. In the pasta, pre-gelled curdlans increased the cooked weight (about 10%) and significantly increased hardness, adhesiveness and gumminess. The commercial curdlan did not result in a significant improvement in any of the parameters of mass as, due to its difficulty with homogenization, it did not gel homogeneously after cooking. Similarly, when applied to the yogurt and subjected to heat treatment, the pre-gelled curdlans significantly increased the firmness and adhesiveness parameters and decreased the cohesiveness of the products, due to the structuring caused by the formation of the curdlan gel... Curdlana é um polissacarídeo linear, neutro, composto por repetidas unidades de glicose unidas por ligações β-(1,3), sendo considerada uma fibra alimentar. Possui especial interesse devido as suas propriedades de formação de gel, as quais permitem seu uso como agente gelificante para melhorar a textura, capacidade de retenção de água e estabilidade térmica de vários produtos alimentícios. Quando aquecida, sua suspensão aquosa forma dois tipos de gel: o gel low-set, o qual é termorreversível e obtido pelo aquecimento em temperaturas entre 55 e 60 °C, seguido de resfriamento, e o gel high-set, que é termo-irreversível e obtido pelo aquecimento acima de 80 °C. Devido a sua elevada firmeza e estabilidade, os géis de curdlana são utilizados na elaboração de massas, molhos, alimentos congelados e enlatados, além de serem biodegradáveis, comestíveis e não tóxicos para humanos e para o ambiente. Apesar de a curdlana ser um polissacarídeo linear, sua estrutura conformacional exerce grande influência nas suas propriedades de dispersão e gelificação. Uma vez que a forma de recuperação do meio e a purificação do polissacarídeo podem influenciar na sua estrutura conformacional, o estudo estrutural da curdlana, bem como das suas propriedades físico-químicas e tecnológicas, são essenciais para melhor adequar seu emprego na indústria de alimentos. Considerando o interesse na curdlana devido às suas propriedades de dispersão, viscosidade e gelificação, o presente trabalho objetivou avaliar a estrutura, morfologia e propriedades físico-químicas e tecnológicas da curdlana produzida por Agrobacterium sp. IFO 13140, comparativamente com a curdlana comercial. Também foi objetivo desta pesquisa a aplicação da curdlana em alimentos, como massa alimentícia caseira e iogurte. A cepa de Agrobacterium sp. IFO 13140 adquirida na forma liofilizada foi reativada e adicionada ao meio de produção de curdlana utilizando glicose como fonte de carbono. Duas metodologias foram utilizadas para a recuperação do polissacarídeo: a de pré-gelificação e a de precipitação. Em ambas as metodologias a curdlana foi solubilizada com solução de NaOH 3 mol/L. Posteriormente foi neutralizada com HCl 3 mol/L (pré-gelificação) ou com água (precipitação). A curdlana comercial também foi submetida ao processo de pré-gelificação e, então, denominada comercial pré-gelificada. As metodologias empregadas para recuperação da curdlana foram relacionadas com suas propriedades funcionais. As curdlanas comercial, comercial pré-gelificada e produzidas por Agrobacterium sp. IFO 13140 (recuperadas pelos dois métodos) foram avaliadas quanto a sua estrutura, morfologia, propriedades físico-químicas e capacidade de dispersão e gelificação. Após esta etapa, as duas curdlanas submetidas ao processo de pré-gelificação foram utilizadas para o preparo de dispersões e géis. Foram estudados os mecanismos de formação de géis de curdlana por espectroscopias de FT-IR e FT-Raman, bem como suas temperaturas de formação por análises térmicas de DSC e TGA. As curdlanas submetidas ao processo de pre-gelificação, assim como a curdlana comercial, foram avaliadas quanto as suas propriedades tecnológicas de absorção de água, óleo e solubilidade em água. Posteriormente, foram aplicadas em massa alimentícia caseira e iogurte nas proporções de 1% e 1,5%, em relação às quantidades de farinha e leite, respectivamente. As características de cozimento e o perfil de textura das massas foram avaliados. Dos iogurtes, foram avaliadas reologia, textura e sinérese. A análise de FT-Raman das curdlanas comercial, comercial pré-gelificada e produzida por Agrobacterium sp. IFO 13140 (recuperada pelos métodos de pré-gelificação e precipitação) revelou similaridade estrutural entre todas as amostras, o que significa que a curdlana produzida pelo micro-organismo tem estrutura similar à comercial e, também, que o método empregado para recuperação do polissacarídeo não influencia na sua estrutura. Entretanto, dados da microscopia eletrônica de varredura revelaram que tanto o método de secagem quanto o método de recuperação implicam significativamente na forma e no tamanho dos grânulos da curdlana. A amostra comercial (atomizada) apresentou grânulos grandes e com concavidades. As demais amostras (liofilizadas) exibiram partículas menores. Ainda, as duas curdlanas submetidas ao processo de pré-gelificação apresentaram o menor tamanho de partícula, o que pode ter influenciado na sua melhor dispersão em água. Os resultados obtidos nas análises físico-químicas revelaram que a curdlana comercial apresentou o maior teor de carboidratos, seguida da produzida pelo micro-organismo e recuperada por precipitação, demonstrando o maior grau de pureza dessas amostras. As curdlanas submetidas ao processo de pré-gelificação apresentaram menor teor de carboidratos devido ao sal incorporado no processo (estimado pelo teor de sódio). Quando avaliadas as características de dispersão e gelificação das curdlanas, as amostras pré-gelificadas formaram facilmente uma dispersão homogênea em água, além de desenvolverem gel firme e homogêneo. A curdlana comercial não formou dispersão homogênea com facilidade e nem gel homogêneo, assim como a curdlana produzida por Agrobacterium sp. IFO 13140 recuperada por precipitação, que não formou gel pela ausência de sódio. Desta forma, as análises térmicas, reológicas e de força de gel foram realizadas apenas com as curdlanas pré-gelificadas. A curdlana comercial foi comparada com as pré-gelificadas em relação às propriedades tecnológicas de absorção de água, de óleo e solubilidade em água, além da aplicação em alimentos. As análises de FT-IR e FT-Raman revelaram similaridade estrutural entre a curdlana comercial e a produzida por Agrobacterium sp. IFO 13140. Não foi possível identificar variações estruturais decorrentes da formação de gel pela técnica de FT-IR. Entretanto, a técnica de FT-Raman evidenciou essas variações, sendo possível observar variações relacionadas às ligações de hidrogênio e interações hidrofóbicas, que ocorrem com a formação dos géis low-set e high-set, respectivamente. As temperaturas de formação de ambos os géis foram determinadas por DSC. As amostras apresentaram um pico endotérmico entre 40 e 55 °C, decorrente do entumescimento da curdlana, e um pico entre 70 e 80 °C devido a interações hidrofóbicas entre as moléculas. Ainda, as análises de reologia e força do gel revelaram que a curdlana produzida por Agrobacterium sp. IFO 13140 mostrou capacidade espessante superior à curdlana comercial pré-gelificada. Porém, a última mostrou capacidade gelificante mais elevada, com gel de força 17% superior e módulo elástico seis vezes maior, a 95 °C. Esta grande diferença entre as capacidades gelificantes das curdlanas é devido aos seus distintos graus de polimerização (DPn) ou massa molecular, pois enquanto a amostra comercial apresentou DPn de 334 ± 8, a amostra produzida pelo micro-organismo apresentou DPn de 232 ± 10, os quais correspondem a massas moleculares de 54000 e 38000, respectivamente... 125 f

The effects of matrix composition on the spectroscopic properties of calcium aluminosilicate glasses (CAS) doped with Erbium (Er) and Chromium (Cr) were studied in this work. Different matrix composition with silica ranging from 7 to 55 wt% were considered by keeping the amount of Er2O3 constant (0.5 wt%). In order to prevent the occurrence of OH-, sample synthesis was carried out under vacuum atmosphere condition. Samples containing these silica proportions are referred as low silica calcium aluminosilicate and calcium aluminosilicate, respectively. For the samples doped with Er, the lifetime of Er3+ (4I11/2) showed a significant decrease by increasing amount of silica, which was related to an increase of phonon energy. By comparing the experimental lifetime with those obtained theoretically by the Judd-Ofelt model, we observed a difference of three orders of magnitude, i.e., the values measured were about thousand times smaller than those predicted by the theoretical model. To calculate the probability of non-radiative transitions, we have established a system of equations taking into account the major interactions of calcium aluminosilicate glasses doped with Er3+. We found that the decay process from the 4I11/2 level of Er3+ is ruled by multiphonon relaxation process. With regard to study the effects of Cr, matrices with 7 and 34 wt% of silica were doped with 0.1 and 0.5 wt% of Cr2O3. Different valence states, namely Cr3+, Cr4+ and Cr6+ were observed in the samples. The presence of Cr6+ were observed in both compositions evidenced by the intense absorption band in the ultraviolet region, which is associated with charge transfer band. In CAS34 samples, we noted the formation of the (+3) valence state in octahedral symmetry with weak interaction with the crystal field. This valence state is the origin of the intense broadband emission centered at 860 nm. In the case of LSCAS samples, the valence state observed was Cr4+ in tetrahedral symmetry, resulting in an emission band at 1400 nm. As a final point, we verified that the formation of (+3) and (+4) valence states depends on the number of non-bridging oxygen (NBOs) in the host material. We think that silica concentration is the central issue accountable for the formation of different valences. Neste trabalho estudamos o efeito da composição da matriz nas propriedades espectroscópicas e luminescentes dos vidros aluminosilicato de cálcio (CAS) dopados com Er e Cr. Para o material dopado com 0,5% em massa de Er2O3, foram estudadas amostras com diferentes composições variando a quantidade de sílica (SiO2) de 7 a 55% (em massa). Estas amostras foram preparadas em forno a vácuo, a fim de eliminar a contribuição das Hidroxilas (OH-), no processo de relaxação não radiativa. Nas amostras dopadas com érbio, verificamos que o tempo de vida do nível 4I11/2 dos íons de Er3+, diminui significativamente com o aumento da quantidade de sílica, resultado esse relacionado com aumento da energia de fônons. A partir da comparação do tempo de vida experimental com os obtidos pelo cálculo do modelo de Judd-Ofelt, observamos uma diferença de três ordens de grandeza, sendo os valores medidos aproximadamente mil vezes menor que os previstos pelo modelo teórico. Modelamos um sistema de equação de taxas considerando as principais interações nos vidros aluminosilicato de cálcio dopados com Er3+ e calculamos a probabilidade de transição não radiativa. Verificamos que o decaimento a partir do nível 4I11/2 dos íons de Er3+ é governado pelo processo de relaxação multifônica. Para o estudo da dopagem com Cr foram preparadas amostras com 7% (LSCAS) e 34% (CAS34) de sílica dopadas com 0,1 e 0,5 % de Cr2O3. Identificamos a formação de diferentes estados de valência: Cr3+, Cr4+ e Cr6+. Verificamos a presença do Cr6+ em ambas as composições, o qual foi identificado pela intensa banda de absorção na região do ultravioleta, associada a banda de transferência de carga. Nas amostras CAS34, verificamos a formação do estado de valência (+3) em simetria octaédrica com fraca interação com o campo cristalino, responsável pela larga banda de emissão centrada em 860 nm. Nas amostras LSCAS identificamos a presença do Cr4+ em simetria tetraédrica, responsável pela emissão na região de 1400 nm. E, por fim, constatamos que a formação dos estados de valência (+3) e (+4) são dependentes do número de oxigênio não-ligados no material hospedeiro e acreditamos que a concentração de sílica é o fator responsável pela formação das diferentes configurações de valência. xiii, 89 [7] f

This work presents a study about the silver (Ag) incorporation in Calcium Boroaluminate (CaBAl) glasses, as well as the use of thermal treatment as a means of nucleation and growth of Ag nanoparticles (AgNPs) and their consequences on the luminescent properties of europium-doped CaBAl glasses. To ensure that the thermal treatment process does not result in optical quality loss and/or crystallization on the studied glasses, the glass transition temperature (Tg) (∼610 ◦C) was used as reference. Thus, the adopted temperatures were 550, 575 and 600 ◦C. Optical absorption results demonstrated the incorporation of Europium trivalent ions and the nucleation of Ag nanoparticles in the treated samples. By excitation/emission maps, it was possible to verify the existence of characteristic emission centers of Eu3+ transitions (5D0-7Fj , j = 1, 2, 3 e 4) and emission centers of silver optically active species, which have broad emission band covering almost the entire visible region in the electromagnetic spectrum. The emission spectra under excitation at 325 nm initially showed an increase in the emission intensity as function of thermal treatment time, due to the fact that the treatment can promote the formation of Ag0-Ag+ and Ag+-Ag+ pairs. However, the reduction of the emission intensities observed for longer treatment or higher temperatures indicates a competition between the AgNPs formation process and the formation of Ag pairs. Emission spectra under excitation at 442 nm, resonant with the surface plasmon resonance (SPR) band, indicated that the plasmon resonance effect, from AgNPS, provides a new excitation region for the silver pairs. An amplification of the emission intensity was observed and can be associated with the SPR effect and/or the energy transfer processes between AgNPs and optically active species.By the chromaticity coordinates (x, y) in the CIE 1931 diagram, the color correlation temperature (CCT) and color rendering index (CRI), it was verified that the Eu2O3-AgNO3-co-doped CaBAl glasses have promising characteristics for application in devices emitting white light and the choice of composition, as well as the conditions of thermal treatments can work as tools for tuning the color of emission. Neste trabalho é apresentado um estudo a respeito da incorporação da prata (Ag) na matriz vítrea Cálcio Boroaluminato (CaBAl), bem como da utilização de tratamento térmico como meio para nucleação e crescimento de nanopartículas de Ag (AgNPs) e suas consequências sobre as propriedades luminescentes desses vidros dopados com íons de Európio. A temperatura de transição vítrea (Tg) do vidro CaBAl (∼610 ◦C) foi utilizada como referência para a escolha das temperaturas de tratamentos para garantir que o processo não acarretasse na perda de qualidade óptica e/ou cristalização dos vidros estudados. Assim, as temperaturas adotadas foram 550, 575 e 600 ◦C. Resultados de absorção óptica evidenciaram a incorporação de íons de Európio na forma trivalente e a nucleação de nanopartículas de Ag para as amostras tratadas termicamente. Por meio de mapas de excitação/emissão verificou-se a existência de centros emissores característicos de transições do Eu3+ (5D0-7Fj , j = 1, 2, 3 e 4) e centros emissores característicos de espécies opticamente ativas da prata (Ag+, Ag0-Ag+ e Ag+-Ag+), os quais apresentam larga banda de emissão cobrindo quase toda região do visível no espectro eletromagnético. Os espectros de emissão sob excitação de 325 nm apresentaram inicialmente um aumento na intensidade de emissão em função do tempo de tratamento térmico, devido ao fato de que o tratamento pode promover a formação de pares Ag0-Ag+ e Ag+-Ag+. Porém, a redução das intensidades de emissão observadas para tratamentos mais longos ou em maiores temperaturas indicam uma competição entre o processo de formação de AgNPs e da formação de pares de Ag. Espectros de emissão sob excitação em 442 nm, ressoante a banda de ressonância de plásmons de superfície (RPS), indicaram que o efeito de ressonância de plásmons proveniente das AgNPs fornece uma nova região de excitação aos agregados de prata. Os espectros apresentaram amplificação da intensidade de emissão que pode estar associado ao efeito de RPS e/ou a processos de transferência direta de energia entre as AgNPs e as espécies opticamente ativas. A partir das coordenadas de cromaticidade (x,y) no diagrama CIE 1931, juntamente com os valores de temperatura de correlação de cor (CCT) e do índice de reprodução de cores (CRI) verificou-se que o vidro CaBAl co-dopado com AgNO3 e Eu2O3 apresentam características promissoras para aplicação em dispositivos emissores de luz branca e que, a escolha da composição, bem como a escolha das condições de tratamentos térmicos, podem funcionar como ferramentas para a sintonia da cor de emissão. 110 f

Developing new materials to act as host for rare earth ions is still on the upswing. Even though luminescent properties of these ions are significantly influenced by the local environment in which they are inserted, the structural studies of these matrices and its influence on the optical properties, are rarely considered. This thesis aimed to apply models to study the structural of amorphous networks as well as the modifications induced via both heat treatment processes and high-pressure solicitation. This work describes calcium aluminosilicate glasses undoped and Eu-doped in which 1% of total matrix mass was replaced by Eu2O3. For the first time, the average angles distribution and the restoring force of T-O-T linkages were determined for this glassy system. By using in situ Raman spectroscopy, we have found that inter-tetrahedral angles decrease with pressure and the reduction rate for CAS65 was doubled compared to LSCAS and CAS34 samples. Furthermore, the transformation of the pristine glass into glass-ceramic is becoming increasingly common. Such materials may present more suitable morphology, which can increase the luminescence efficiency of the ions inserted therein. These systems are stable against short wavelength irradiation and high temperatures. They have a much higher thermal conductivity than the materials used up to now. We have checked for alternative methods, over the simple heat treatment, to produce glass-ceramics from these pristine glasses. Specifically, we have obtained homogeneously crystallized matrices using a press-type Belt. Physical and chemical properties as density, hardness and Young's modulus were determined. We have found, for instance, an increase in hardness and the luminescent properties in the glass-ceramics host, especially the emission quantum efficiency, which increased from 45 to 60 % after the simultaneous high pressure and temperature process. We have compared the structure of the hosts by using crystal field parameterization, according to the fluorescence line-narrowing model. A busca por materiais que possam atuar como matrizes na incorporação de elementos terras raras segue em constante ascensão. Embora as propriedades luminescentes desses íons estejam intimamente ligadas ao ambiente químico local em que são inseridos, estudos estruturais dessas matrizes, bem como suas influências sobre as propriedades ópticas, são raramente consideradas. Neste trabalho de tese empregamos modelos na análise estrutural de redes do tipo amorfa, bem como as respectivas modificações induzidas via ambos processos de tratamento térmico e aplicação de alta pressão. Para isso, uma série de amostras vítreas aluminossilicatos de cálcio foram preparadas na sua forma base (sem dopante) e com 1%, em massa, de óxido de Európio. Determinamos, pela primeira vez, a distribuição média dos ângulos e da força das ligações T-O-T (T= Si ou Al) que formam a rede desses vidros. Os resultados mostraram que ambos aumentam com a substituição de óxido de alumínio por sílica. Com a espectroscopia Raman in situ, verificamos que esses ângulos diminuíram com a pressão e que a taxa de redução no caso da amostra CAS65 foi o dobro da LSCAS e CAS34. Adicionalmente, a conversão do vidro inicial à uma vitro-cerâmica vem se tornando cada vez mais frequente. Esses materiais podem apresentar morfologia mais adequada no sentido de aumentar a eficiência da luminescência dos íons neles inseridos. São sistemas estáveis contra a radiação de comprimento de onda curto e temperaturas elevadas e apresentam condutividade térmica maior do que os materiais utilizados usualmente. Verificamos a potencialidade de métodos alternativos, ao tratamento térmico simples, para produzir vitro-cerâmicas. Em particular, obtivemos matrizes homogeneamente cristalizadas utilizando uma prensa do tipo Belt. Propriedades físicas e químicas, como densidade, dureza e módulo de Young, foram determinadas. Verificamos, por exemplo, aumento na dureza e nas propriedades luminescentes das vitro-cerâmicas. Mediante medidas de luminescência constatamos que eficiência quântica de emissão aumentou de 45 para 60%. Finalmente, comparamos a estrutura das matrizes via parametrização de campo cristalino e constatamos a presença de duas distribuições de sítios nessas matrizes. v, 126 f

A eficácia de métodos convencionais de transmissão, utilizados para medir absorção de materiais altamente transparentes, é geralmente limitada pela reflexão e espalhamento de luz. A espectroscopia de Lente Térmica, por outro lado, não é sensível a esses fenômenos, e tem sido amplamente usada na determinação de baixas absorções ópticas. Neste trabalho, estudamos uma configuração de Lente Térmica de duplo feixe (onda contínua cw), desenvolvida recentemente, e suas aplicações. Essa configuração otimiza a técnica de Lente Térmica, e aumenta significativamente a sensibilidade de medida. Foram realizados alguns cálculos computacionais e testes experimentais dessa configuração, e os resultados foram comparados com os de outra configuração, tradicionalmente utilizada, denominada de feixe duplo no modo-descasado. Várias aplicações foram feitas para líquidos e sólidos. Como resultado, obtivemos o espectro de absorção da água pura entre 350 e 528 nm, que indicou um valor mínimo de aproximadamente 1,5 &#8226 10-5 cm-1 em torno de 380 nm, que é mais baixo do que todos os valores da literatura. Coeficientes tão baixos quanto 2 &#8226 10-7 cm-1 podem ser medidos para a água, com 1W de potência, utilizando essa configuração otimizada. Estimamos um limite de detecção de ~ 6 &#8226 10-9 cm-1 (P = 1 W) para o solvente CCl4, que corresponde (até onde sabemos) ao menor valor já encontrado na literatura para líquidos, utilizando-se laser cw. Quanto à detecção de traços de impurezas, o limite para o Cr (III) em solução aquosa foi de ~ 40 ppb (ng/mL) em 514 nm, que corresponde a aproximadamente metade da concentração máxima ideal de Cr (III) em águas potáveis e naturais. Foram obtidos alguns resultados preliminares para a variação do caminho óptico com a temperatura (ds/dT), em sólidos com diferentes geometrias. Para a sílica fundida (quartzo vítreo) Suprasil, determinamos um limite superior para o coeficiente de absorção, cujos valores, 1 &#8226 10-6 cm-1 (em 493 nm) e 1 &#8226 10-5 cm-1 (em 355 nm), também são menores do que os resultados da literatura nessa região do espectro. A alta sensibilidade da técnica permitiu obter a absorção, em 1064 nm, das matrizes de materiais laser dopados com Nd3+, sendo (1,8 &#177 0,1) &#8226 10-3 cm-1 para o vidro Q-98 (Kigre), e (5 &#177 1 &#8226 10-4 cm-1 para o cristal Nd:YAG. Realizamos também medidas de eficiência quântica de fluorescência em nanocristais semicondutores (CdSe/ZnS) suspensos em THF e tolueno, com resultado aproximadamente 5 vezes mais preciso do que o obtido por técnica convencional de fluorescência. As principais vantagens da configuração otimizada, em relação à tradicional, são: um procedimento experimental simples, boa precisão nas medidas de difusividade térmica e, principalmente, a alta sensibilidade da técnica. As desvantagens são: um tempo de medida mais longo, e a necessidade de amostras maiores. The efficiency of conventional transmission methods used to measure absorption of hightransparent materials is usually limited by light scattering and reflection. On the other hand, Thermal Lens spectroscopy is insensible to such phenomena and has been widely applied to determinate low optical absorptions. In this thesis, we have studied a recently developed dualbeam (continuous wave - cw) Thermal Lens configuration as well as its practical applications. This configuration optimizes the technique and significantly improves the measurement sensitivity. Some computational calculations and experimental tests of this approach were carried out. The results were compared with those obtained using a traditional configuration, named Mode-mismatched Dual-beam Thermal Lens. Several applications were made for liquids and solids. As a result, we obtained the absorption spectrum for pure water in the range of 350 to 528 nm, which indicated a minimal value of approximately 1,5 &#8226 10-5 cm-1 around 380 nm, that is lower than those found in literature. Absorption coefficients as small as 2 &#8226 10-7 cm-1, can be measured for water, using 1W of excitation power, with this optimized configuration. We have estimated a detection limit of ~ 6 &#8226 10-9 cm-1 (P = 1 W) for CCl4 solvent, which corresponds (to the best of our knowledge) to the smallest value found in the literature for liquids using cw laser. With regard to the chemical trace analysis, the detection limit was ~ 40 ppb (ng/mL) at 514 nm for Cr (III) in aqueous solutions, which is nearly half of the maximum desired Cr (III) concentration in drinking and natural waters. Some preliminary results for the temperature coefficient of the optical path length (ds/dT) were obtained at solids with different geometries. For the fused-silica (vitreous quartz) Suprasil, we have determined an upper limit for the absorption coefficient, whose values, 1 &#8226 10-6 cm-1 at 493 nm, and 1 &#8226 10-5 cm-1 at 355 nm, also are lower than the values found in literature in this spectrum region. The high sensitivity of the technique allowed us to measure the absorption (at 1064 nm) of matrices of Nd3+ doped laser materials: (1,8 &#177 0,1) &#8226 10-3 cm-1 for Q-98 glass (Kigre), and (5 &#177 1) &#8226 10-4 cm-1 for Nd:YAG crystal. We carried out as well measurements of fluorescence quantum yield of semiconductor nanocrystals (CdSe/ZnS) suspended in THF and toluene solvents, whose result was approximately 5 times more accurate than that obtained with the conventional fluorescence technique. The main advantages of the optimized configuration are: a simple experimental procedure, a good accuracy for thermal diffusivity measurements, and most important the high sensitivity of the technique. The drawbacks are: a longer time of measurements, and the requirement of larger samples.

The purpose of this study was to evaluate in vitro the variation of fluorescent composite resins, after 90 days of natural aging, and compare the fluorescent resin composites' spectrum with enamel and human dentin. There were made 20 enamel specimens (5,0mmx0,30mmX0,03mm) and 20 dentin specimens (5,0mmx1,0mm) from third healthy human molars and 5 specimens (10,0mmx2,0mm) for each one of the resin's composites from brands such as, Z350XT/3M ESPE, Opallis/FGM and Empress Direct/Ivoclar-Vivadent, in shades EA2, DA2 and achromatic enamel. The fluorescence was measured by the PerkinElmer LS 55 spectrometer fluorometer, with the excitation of 395 nm for the longitudinal evaluation of the composite resins with 375, 395 and 410 nm for the comparison of the enamel and human dentin, with the reading of the emission from 400 to 900 nm, and the analyzed data by the graphic program Origin 8.0. The percentage variation between evaluation times was subjected to the test t of student, with the level of significance of 5%. After 90 days, the resins Z350XT showed an increase in fluorescence, while the resins Opallis and Empress Direct showed a decrease in relation to the initial time, with greater variation ocurring in the first 30 days, where the intensity of the fluorensce of all composite resins, with the exception of Opallis-EA2 varied significantly with relation to the initial time (p-value

Along the continuous interesting increasing in the various fields industries in luminescent materials, also growing the need to obtain luminescent materials that shows more efficiency. The aim of this work is the study of Eu-doped calcium aluminosilicate glasses luminescent properties as a function of silica matrix content. The first step of this work was to develop the experimental setup and acquisition software routine, following the samples optical excitation and emission measurements performance. The developed routine allows the control and data acquisition to obtain luminescence spectra, both emission and excitation mode. Contour plots of the excitation/emission were obtained from emission spectral which were used to analyze luminescent properties of the system. The results showed for low silica concentration the luminescence is mainly due to trivalent ion emission, while the Eu2+ emission intensity increasing significantly as a function of rising silica content, as well as, the emission band shift towards lower wavelength. These results were attributed to the decreasing of glasses optical basicity, which occurs due to silica addition influencing in the europium ion interaction with crystal field. Com um aumento continuo no interesse de indústrias das mais diversas áreas em materiais luminescentes, cresce a necessidade de se obter materiais luminescentes que possam ser aplicados com maior eficiência. Com este propósito, nosso trabalho tem como principal foco o estudo das propriedades luminescentes de vidros aluminosilicato de cálcio dopadas com európio em função das diferentes quantidades de sílica da matriz. O primeiro passo do trabalho foi a montagem e instrumentação e pôr fim a realização das medidas de excitação e emissão ópticas. Para a instrumentação foi desenvolvida uma rotina para controle e aquisição de dados que permite a obtenção de espectros de luminescência tanto no modo de emissão quanto de excitação. A partir dos espectros de emissão foram montados os mapas de excitação/emissão, os quais foram utilizados para a análise das propriedades luminescentes do sistema. Os resultados mostraram que para baixa concentração de sílica na matriz, a luminescência é predominantemente resultado da emissão do íon trivalente, enquanto a intensidade da emissão referente ao Eu2+ aumenta significativamente quando há um aumento na concentração de sílica, assim como, o deslocamento da banda de emissão para menores comprimentos de onda. Estes resultados estão relacionados a diminuição da basicidade óptica dos vidros que ocorre devido a adição de sílica, o que influência diretamente a interação entre os íons de európio e o campo ligante da matriz. 80 f

In this paper we investigated the influence of the manufacturing conditions and composition on the valence change of europium (Eu) and energy transfer in Erbium - Ytterbium (Er-Yb) co-doped calcium aluminosilicate glasses. Two series of samples with 2.5wt% of europium and different silica concentrations were prepared, in air and vacuum respectively. One co-doped 0,5wt%Er-5wt%Yb aluminosilicate samples serie was prepared in vacuum with different silica concentration. Luminescence, X-ray absorption (XANES) and Electron Paramagnetic Resonance (EPR) techniques were used to investigate europium doped samples. Besides, optical absorption spectroscopy, luminescence and fluorescence lifetime were carried out on Er-Yb co-doped system. The emission spectra of the europium doped samples prepared in vacuoum showed the coexistence of Eu2+ and Eu3+. We found an increase of the emission intensity attributed to Eu2+ and the displacement of the emission peak to shorter wavelengths with silica increasing. XANES and EPR results indicated that the ratio Eu2+/Eu3+ increase as silica is added to sample composition, which has been attributed to reduction of the non-bridging oxygens (NBO) in the glass. The EPR spectrum curves indicate change in Eu2+ symmetry and crystal field interaction intensity with amount of silica. The emission spectra of air europium prepared samples showed Eu3+ emissions. A broad absorption band around 350 nm assigned to Yb2+ was observed in the samples with higher amount of silica. The energy transfer efficiency process ytterbium to erbium increased about 20% as the amount of silica increase. The Luminescence and fluorescence lifetime results indicated that higher silica concentrations, above 35 wt%, there is a decrease of non-radiative multi-phonon relaxations suggesting energy trasnsfer back to Yb. Neste trabalho investigamos a influência das condições de preparo e da composição de vidros aluminosilicato de cálcio na formação de diferentes valências do európio (Eu) e na transferência de energia em vidros co-dopados com érbio e itérbio (Er-Yb). Duas séries de amostras com 2,5% em massa de Eu2O3 e diferentes concentrações de sílica foram preparadas, em ar e vácuo. Uma série de amostras com diferentes concentrações de sílica e 5%Yb2O3-0,5%Er2O3 foram preparadas em vácuo. As técnicas de luminescência, Absorção de Raios-X (XANES) e Ressonância Paramagnética Eletrônica (RPE) foram utilizadas para a investigação das amostras com európio e absorção óptica, luminescência e tempo de vida para investigação das amostras co-dopadas Er-Yb. Os espectros de emissão das amostras com európio preparadas em vácuo apresentaram a coexistência de Eu2+ e Eu3+. Verificamos o aumento da intensidade da emissão atribuída ao Eu2+ bem como o deslocamento do pico de emissão para menores comprimentos de onda com o aumento da sílica. Os resultados de XANES e RPE mostraram o aumento na razão Eu2+/Eu3+ com aumento da sílica, o que foi atribuído à redução do número de oxigênios não ligados (NBO) no vidro. Alterações na forma do espectro de RPE indicam mudança na simetria e intensidade de interação do Eu2+ com o campo cristalino, sendo mais simétrico e mais intenso quanto menor a quantidade de sílica. Os espectros de emissão das amostras com európio preparadas em ar mostraram a predominância das emissões atribuídas ao Eu3+. Através da absorção óptica das amostras co-dopadas Er-Yb verificamos a presença de picos atribuídos a ambos os íons indicando a eficiência da co-dopagem. Com aumento da sílica observamos o surgimento de uma larga banda de absorção em torno de 350 nm atribuída ao Yb2+. A eficiência de transferência de energia do Itérbio para o Érbio apresentou aumento de cerca de 20% entre as amostras com menor e maior quantidade de sílica. Os resultados de luminescência e tempo de vida indicam que para concentrações de sílica maiores que 35% há uma diminuição das relaxações não radiativas por multifônons sugerindo a transferência de energia de volta para o Yb. 101 f

In recent years there has been a growing concern with the environment, boosting the global scientific community to search more efficient technologies and seek alternatives to the main processes of modern society that are sources of environmental degradation. One such process is the current method of refrigeration. Among the possible alternatives, the magnetic refrigeration has emerged as the most promising. It is based on the so called magnetocaloric effect (MCE), that is, the adiabatic temperature variation or the isothermal entropy change experimented by a magnetic material when it is submitted to magnetic field variation. One of the methods of investigation and characterization of the magnetocaloric materials is the acoustic detection technique. In this approach, still little explored in the literature, the temperature variation experienced by the magnetocaloric sample under a modulated magnetic field is captured acoustically. In this thesis, a magnetoacoustic setup was built and applied to the study of thermal cycling in three magnetocaloric materials: the Gd, the alloy Gd5,09Ge2,03Si1,88 as cast and an unpublished compound annealed Gd4,7Nd0,3Si4,0. Bulk and powder samples were analyzed and it was verified a significant difference between the heating and cooling curves which acted even in second-order transitions. Two causes were discovered: the moisture present in the atmospheric air when it is used as transducer and a reorientation of the particles when the powder samples transits from ferromagnetic to paramagnetic or vice versa. If no precaution is taken, errors can exceed 50 %. Thus, here is presented a methodology to drying the magnetoacoustic system in order to completely eliminate the influence of moisture. Solving the problem of particles movement we propose to use a leaked rod, having on its bottom end a screen clipping of a fine mesh, pressed against the powder sample in order to restrict it. Furthermore, by means of the Gd4,7Nd0,3Si4,0 compound it was determined how to distinguish the conventional MCE of the inverse one through a 180 degrees signal phase inversion. A parallel study aiming to process the Gd5,09Ge2!03Si1 83 alloy in a manufacturing route similar to powder metallurgy also developed in this thesis. Six ranges of particle size were evaluated and through two completely different techniques were possible to establish a minimum particle size of 40 um where the MCE is not drastically affected. Moreover, contrasting the cooling capacity with the transition enthalpy of the powders we concluded that a maximization of MCE occurs in particle size between 45 and 63 µm. Nos últimos anos tem havido uma crescente preocupação com 0 meio ambiente, impulsionando a comunidade cientifica mundial a pesquisar tecnologias mais eficientes, bem como buscar alternativas aos principais processos da sociedade moderna que se constituem fontes de degradação ambiental. Um desses processos é o hodierno método de refrigeração. Dentre as possíveis alternativas, a refrigeração magnética tem surgido como a mais promissora. Ela se fundamenta no chamado Efeito Magnetocalérico (EMC), isto é, a correspondente variação de temperatura adiabática ou a variação de entropia isotérmica sofrida por um material magnético quando este é submetido a uma variação de Campo magnético. Um dos métodos de investigação e caracterização dos materiais magnetocaléricos (MC) é a técnica de detecção acústica, na qual a variação de temperatura sofrida pela amostra MC ao ser submetido a um Campo magnético modulado é captada acusticamente. Nesta tese, uma montagem magnetoacustica foi construída e aplicada ao estudo da ciclagem térmica em três materiais MC: o Gd, a Iiga Gd5,09Ge2,03Si1_88 como fundida e um composto ainda não publicado, Gd4_7Nd0,3Si4,0 tratado termicamente. Amostras tanto em volume como em p6 foram analisadas e verificou-se uma diferença significativa entre as curvas de aquecimento e resfriamento, a qual atuava mesmo em transições de segunda ordem. Descobriram-se duas causas: a umidade presente no transdutor acústico quando ar atmosférico é utilizado e uma reorientação das partículas em amostras em p6 quando estas transitam de ferro para paramagnética ou vice versa. Se nenhuma cautela for tomada, os erros podem ser superiores a 50 %. Apresenta-se aqui uma metodologia de secagem do sistema magnetoacustico para a completa eliminação da influência da umidade. Solucionando o problema da movimentação das partículas prop6em-se pressionar contra a amostra uma haste de fixação vazada tendo em sua extremidade inferior um recorte de tela com trama menor ou da mesma ordem da maioria das partículas. Além disso, determinou-se como distinguir o EMC convencional do inverso mediante uma inversão de 180 graus da fase do sinal observada no composto Gd4'7Nd0_3Si4_0. Um estudo paralelo também desenvolvido nesta tese visou o processamento do material Gd5,09Ge2,03Si1,88 em uma rota de fabricação similar a metalurgia do pé. Seis faixas de tamanho de partícula foram avaliadas e através de duas técnicas completamente distintas foi possível estabelecer um limite mínimo de tamanho de partícula de 40 um em que o EMC não seja drasticamente afetado. Ainda mais, contrastando a capacidade de refrigeração e a entalpia de transição dos pés conclui-se que uma maximização do EMC ocorre em partículas com tamanho entre 45 e 63 µm. viii, 186 f

In this work, we have studied the Judd Ofelt theory in order to use it as a tool for spectroscopic characterization for glasses produced by our group. We have analyzed the main aspects of model approximations, which has as purpose to explain the transitions in the 4f layer of the Rare Earth ions under the action of the glassy matrix crystal field, which by the selection rules of quantum mechanics are forbidden. We studied the application of the Judd Ofelt theory in the luminescent properties analysis of the calcium aluminosilicate glasses doped with 0,5wt% of Erbium (Er3+), varying its silica concentration from 7wt% to 55wt%. We have focused on the ion Er3+ transition region at 1535 nm, widely used in the production of laser and optic fiber. This region is called "third window" of optical transmission. Using ions by cubic centimeters measures, index of refraction, absorption spectrum and application of Judd Ofelt theory we achieved 94% for the quantum efficiency of the state 4I13/2 (E ~ 6667cm-1 → λ= 1,5 μm) of this glasses. The result is in agreement with the properties of the dopant, as the stability in ionic form Er3+ not showing other valencia state, and also by the minimal energy lose in its meta state 4I13/2. Como objetivo principal deste trabalho estudamos a teoria de Judd Ofelt para utilizá-la como mais uma ferramenta de caracterização espectroscópica dos vidros produzidos por nosso grupo, analisamos os principais aspectos das aproximações feitas nesse modelo, que tem o propósito de explicar as transições que ocorrem na camada 4f dos íons Terra Rara sob a ação do campo cristalino da matriz vítrea que, pelas regras de seleção da mecânica quântica, não poderiam ocorrer. Neste trabalho nos concentramos em aplicar a teoria de Judd Ofelt na análise das propriedades luminescentes dos vidros aluminosilicatos de cálcio com a dopagem do íon Érbio (Er3+) em 0,5% em massa variando a concentração de sílica no intervalo de 7 a 55% em massa. Nosso estudo se concentrou na transição do íon Er3+ na região de 1535 nm, muito utilizada na produção de lasers e cabos de fibra óptica, região essa chamada de "terceira janela" de transmissão óptica. Usando o cálculo do número de íons por centímetro cúbico, índice de refração, espectro de absorção e a aplicação da teoria de Judd Ofelt obtivemos cerca de 94% para a eficiência quântica do estado 4I13/2 (E ~ 6667cm-1 → λ= 1,5 μm) desses vidros. Resultado que é coerente com as propriedades do dopante utilizado, como a estabilidade na sua forma iônica Er3+ não apresentando outros estados de valência, e também pela perda mínima de energia em seu meta estado 4I13/2. 87 f

To evalute the Opalescence Parameter (OP), reflectance spectra (R(λ )), transmittance spectra (T(λ)) and attenuation coefficient (٥(λ )) of composite resins, immeaditly after preparation and after 2, 7, 30, 60, 120 and 180 days of storage and compare with the results obtained for human enamel. For this purpose, 20 samples of enamel (5.0 mm x 0.3 mm) and 9 samples (10.0 mm x 1.0 mm) were made up of 10 different shades of commercial composite resins available on the national market: Empress Direct (Ivoclar Vivadent), Enamel Plus HRI (Miscerium), Filtek Z350 XT (3M Espe), Llis (FGM) and Opallis (FGM). As a control group, 9 samples of adhesive Ambar (FGM) were fabricated. The reading of the spectra R(λ) and T(λ) was performed by spectrophotometry, using the integrating sphere. The ٥(λ) was calculated in terms of (R(λ)) and (T(λ)) and OP was calculated as the difference between the yellow-blue coordinates (Δb*) and red-green coordinates (Δa*) between the reflected and transmitted light, using color scale CIE L*a*b* (1976). The data were statistically analyzed (ANOVA and Tukey). Results: Only one of the resins had statistically similar values of OP to the enamel during the study period. The resins showed high value of OP, which for some brands remained stable and others increased over time. For resins that had increased their OP, there was a shift to yellow for both T(λ) and for R(λ). The OP does not have clinical applicability, in other words, resins with high values of opalescence not necessarily reproduce a greater reflection of cool colors and greater transmission of warm colors. Avaliar o parâmetro de opalescência (OP) e os espectros de refletância (R(λ)), transmitância (T(λ)) e o coeficiente de atenuação (٥(λ)), de resinas compostas, imediatamente após a sua confecção e após 2, 7, 30, 60, 120 e 180 dias de armazenamento e comparar com os resultados obtidos para o esmalte humano. Para tanto, foram confeccionados 20 corpos de prova (CP) de esmalte (5,0 x 0,3 mm) e 9 CP (10,0 mm x 1,0 mm) de 10 diferentes tonalidades de marcas comerciais de resinas compostas disponíveis no mercado nacional: Empress Direct (Ivoclar Vivadent), Enamel Plus HRI (Miscerium), Filtek Z350 XT (3M Espe), Llis (FGM) e Opallis (FGM). Como grupo controle, foram confeccionados 9 CP do adesivo Ambar (FGM). A leitura dos espectros de R(λ)) e T(λ) foi realizada por espectrofotometria, com a utilização de esfera integradora. O ٥(λ) foi calculado em termos de R(λ) e T(λ) e OP foi calculado como a diferença entre as coordenadas azul-amarelo (Δb*) e as coordenadas verde-vermelho (Δa*), entre a luz refletida e a transmitida. Os dados obtidos foram analisados estatisticamente (ANOVA e Tukey). Apenas uma das resinas apresentou valores de OP semelhantes estatisticamente ao esmalte durante todo o período avaliado. As resinas apresentaram alto valor do OP, que para algumas marcas se manteve estável e para outras aumentou com o passar do tempo. Para as resinas que tiveram seu OP aumentado, houve deslocamento para a cor amarela tanto para T(λ ) como para R(λ ). O OP não apresenta aplicabilidade clínica, ou seja, resinas com altos valores de opalescência não reproduzem necessariamente uma maior reflexão de tons frios e maior transmissão de cores quentes. 70 f

In this work we have studied the spectroscopic properties of calcium aluminosilicate glass at different compositions doped with europium and also doped with different concentrations of Eu2O3. We have prepared to sets of samples, in the first one the silica content was varied from 7 to 65 wt%, keeping the ratio CaO/Al2O3 constant and the amount of Eu2O3 at 2.5 wt%. For the second set, four different compositions of the calcium aluminosilicate glass were doped 0.1, 0.5, 1.0 and 2,5 wt% of Eu2O3. The samples were studied using spectroscopic techniques such as transmittance, luminescence, time resolved luminescence, excitation/emission contour plot and lifetime. The results showed that, with increasing of the silica content the absorption band assigned to the Eu2+ eg energy level shifts to lower wavelength, and the intensity of the luminescence band assigned to the Eu2+ increase substantially, suggesting an increment in the Eu2+/ Eu3+ ratio, and also this luminescence band shifts to lower wavelength. These behaviours were attributed to decrement of the glass optical basicity as the silica content increase, which affects the interaction between the glass matrix and the europium ions. The time resolved luminescence showed that the Eu2+ emission disappears after a few microseconds; however the Eu3+ emission disappears after a couple milliseconds. The Eu2+ luminescence lifetime is in the order of 1 us, increasing with the silica content. For the samples doped with different Eu2O3 concentrations, no shifts on the absorption band were observed. It was observed that the Eu3+ luminescence intensity increases monotonically with the increment of the ion concentration, however for the Eu2+ ion the luminescence intensity presents different behaviours for different excitations, for the excitation at 350 nm the luminescence intensity decreases with the increment of the Eu2O3 content and for the excitation at 465 nm first the luminescence intensity increases and then decreases. With the increment of the Eu2O3 content, it was observed a shift of the luminescence band to higher wavelength; this shift was attributed to the increment in the energy transfer process that occurs because of the electric dipole-dipole interaction between the Eu2+ ions. Our results shown that, these glasses are excellent candidates to tunable visible light even also white light generators Neste trabalho estudamos as propriedades espectroscópicas de vidros aluminosilicatos de cálcio dopados com európio com diversas composições e concentrações de európio. Foram preparadas duas séries de amostras. Para a primeira variamos a concentração de sílica entre 7 e 65%, em peso, mantendo a razão CaO/Al2O3 e a quantidade de dopante de 2,5% constantes, para a segunda escolhemos quatro matrizes e as dopamos com concentrações de európio de 0,1; 0,5; 1,0 e 2,5%. As amostras foram estudadas por meio de análises espectroscópicas como absorção óptica, luminescência, luminescência resolvida no tempo, mapas de excitação/emissão e tempo de vida. Os resultados mostraram que com o aumento da concentração de sílica ocorre um deslocamento da banda de absorção atribuída ao nível eg do Eu2+ para menores comprimentos de onda, e que a intensidade da luminescência do Eu2+ aumenta significativamente, sugerindo um aumento da razão Eu2+/Eu3+, e também se desloca para menores comprimentos de onda. Estes resultados foram associados à diminuição da basicidade óptica dos vidros que ocorre com o incremento de sílica, o que afeta a interação entre a matriz e os íons de európio. As medidas de luminescência resolvida no tempo mostram que a emissão do Eu2+ desaparece em poucos microssegundos, enquanto a do Eu3+ desaparece em alguns milissegundos. O tempo de vida do európio divalente é da ordem de 1?s, aumentando com a concentração de sílica. Para as amostras dopadas com diferentes concentrações de európio não observamos deslocamentos das bandas de absorção. Verificamos que a emissão do európio trivalente aumenta de forma monotônica com o aumento da concentração do íon, já o európio divalente apresenta comportamentos diferentes para excitações diferentes, com a excitação em 350nm a intensidade da emissão diminui com o aumento de európio e para a excitação em 465nm a emissão aumenta e depois volta a diminuir. Com o aumento da concentração do európio verificamos um deslocamento da banda de emissão para maiores comprimentos de onda, este deslocamento foi atribuído ao aumento de processos de transferência de energia que ocorrem devido a interações do tipo dipolo-dipolo elétrico entre íons de európio divalente. Nossos resultados mostram que estes vidros são excelentes candidatos a geradores sintonizáveis de luz visível e até de luz branca. 80 f

For many years, the Photothermal Phenomena Group (GEFF) of the Physics Department (DFI) of Maringá State University (UEM) has been making effective the obtaining of Aluminosilicate Glasses. Over these years, a lot of works was produced in order to present results achieved in this field. However, the process of nucleation and crystal growth of vitreous systems weren't accurately investigated. Hence, the aim of this dissertation has two sides. On the one hand, to analyze the mechanisms and parameters of crystallization in the syntheses of Calcium Aluminosilicates glasses. The other, to get transparent glass-ceramics by means of controlled crystallization of the precursors glasses CAS and LSCAS through a scheduled heat-treatment. In this work, were prepared and characterized a number of four samples of the glassy systems CaO-Al2O3-SiO2-MgO. In addition to examining the behavior of the samples in relation to heat-treatments, whenever as possible, the data obtained for CAS glasses were compared with the LSCAS, in order to check the changes in the properties studied. Although the main study was based on the results of thermal analysis, other techniques (X-Ray Diffraction, Absorption and Emission Spectroscopy, Confocal Raman Microscopy) were used in order to obtain additional information about the effect of heat-treatments on these samples. The results showed that in this glass system the surface crystallization was more favorable than the bulk (internal), which generally need nucleating agent. In the CAS matrix the ion of neodymium acted as a facilitator of crystallization. The data from differential thermal analysis allowed the determination of the characteristic transition temperatures (Tg, Tx and Tp) and the determination of the activation energy (E) of the samples, very important parameter in the study of the nucleation process. Two methods were applied for determining the temperature at which the nucleation rate is maximal. By confocal Raman microscopy it was estimated that the crystallized region is 20-30μm. Finally, this dissertation presents an extensive bibliography for who wishes to begin studies on the crystallization of glassy systems. Há vários anos, o Grupo de Estudos dos Fenômenos Fototérmicos (GEFF) do Departamento de Física (DFI) da Universidade Estadual de Maringá (UEM) vem efetivando a obtenção de vidros Aluminosilicato de Cálcio. Ao longo desses anos, uma gama de trabalhos foi produzida a fim de apresentar resultados atingidos nesse domínio. No entanto, os processos de nucleação e crescimento de cristais desses sistemas vítreos não foram precisamente investigados. Sendo assim, o escopo da presente dissertação somam duas vertentes. De um lado, analisar os mecanismos e parâmetros de cristalização na síntese dos vidros Aluminosilicatos de Cálcio. Do outro, a possível obtenção de vitrocerâmicas trasparentes via cristalização controlada dos vidros precursores CAS e LSCAS, por meio de tratamentos térmicos adequados. Nesse trabalho, preparou-se e caracterizou-se uma série de quatro amostras do sistema vítreo CaO-Al2O3-SiO2-MgO. Além de analisar o comportamento das amostras em relação aos tratamentos, sempre que possível, os dados obtidos para os vidros CAS foram comparados com os vidros LSCAS, a fim de verificar as alterações das propriedades investigadas. Embora o estudo principal fundamentou-se nos resultados de Análise Térmica, outras técnicas (Difração de Raios-X, Espectroscopia de Absorção e Emissão, Microscopia Raman Confocal) foram utilizadas com intuito de obter informações adicionais ao efeito dos tratamentos térmicos nessas amostras. Os resultados mostraram que nesse sistema vítreo a cristalização superficial foi mais favorável que a volumétrica (interna), que geralmente necessita do agente nucleador. Nas matrizes CAS o íon de neodímio atuou, de forma bastante sutil, como um agente facilitador da cristalização. Dados procedentes de análise térmica diferencial permitiu a determinação das temperaturas características de transição (Tg, Tx e Tp), bem como o cálculo da energia de ativação (E) das amostras, parâmetro muito importante no estudo dos processos de nucleação. Dois métodos para a determinação da temperatura na qual a taxa de nucleação é máxima foram aplicados. Por Microscopia Raman Confocal estimou-se que a região cristalizada é de 20-30μm. Finalmente, essa dissertação apresenta, uma ampla bibliografia para quem deseja iniciar os estudos sobre a cristalização de sistemas vítreos. ix, 78 f

In this work we prepared calcium aluminosilicate glasses with 34wt% of SiO2 (CAS) doped with different Tm2O3concentrations. The samples were prepared under vacuum condition in order to eliminate the existence of OH- molecules. This was performed in a specially constructed furnace to operate at high temperatures, about 1600°C. The CAS glasses were characterized in conjunction with low silica calcium aluminosilicate (LSCAS) glass doped with different Tm3+ ions concentrations.The aim was to investigate the influence of the SiO2 concentration on the optical and thermal properties of the CAS and LSCAS glasses doped with ions Tm3+. The characterization was realized using various methods, such as luminescence and lifetime measurements with excitation at 350nm and 465nm . Thermal Lens Spectroscopy was also performed with excitation at 465nm , to determine the fraction of energy converted into heat in both CAS and LSCAS glasses. The results showed that the increase of silica content results in lower cross relaxation processes between the 3H4 3F4: 3H6 3F4 Tm3+ levels as compared to those of the LSCAS glasses. This observation was confirmed through the increase in the ~800nm emission and reduction in that at ~1.8μm for the CAS in relation to LSCAS glasses. In conclusion, the results of this work showed that LSCAS is a better formulation when high emission at ~1.8μm is intended. Neste trabalho foram preparados vidros aluminosilicato de cálcio (CAS) com 34% em massa de SiO2 dopados com diferentes concentrações de Tm2O3. As amostras foram preparadas a vácuo, com a finalidade de se eliminar a existência de moléculas OH-, o quefoi realizado em um forno especialmente construído para operar em altas temperaturas, até aproximadamente 1600°C. Os vidros CAS foram caracterizados comparando-se suas propriedades com as dos vidros aluminosilicato de cálcio com baixa concentração de sílica (LSCAS), dopados com diferentes concentrações de Tm2O3. O objetivo principal foi investigar a influência da concentração de SiO2 nas propriedades ópticas e térmicas dos vidros CAS e LSCAS dopados com íons Tm3+. As medidas foram realizadas utilizando diversos métodos como luminescência e tempo de vida com excitação em 350nm e 465nm . Também foram realizadas medidas com a espectroscopia de Lente Térmica utilizando excitação em 465nm , para determinar a taxa de geração de calor nos dois vidros, CAS e LSCAS. Os resultados mostram que o aumento de sílica faz com que os íons Tm3+ no vidro apresentem menor mecanismo de relaxação cruzada entre os níveis 3H4 3F4: 3H6 3F4 se comparado ao vidro LSCAS. Esta observação foi confirmada a partir do aumento da emissão em ~ 800nm e da redução daquela em ~1,8 μm no vidro CAS em relação ao medido para o LSCAS. Em conclusão, os resultados deste trabalho mostraram que o Vidro LSCAS é mais adequado para se obter alta taxa de emissão em ~1,8μm. 80 f

In this work we presented an extension to Shen-Pedreira's model for thermal lens spectroscopy technique to study the dynamical processes of photochemical reaction. The aim of this work is show that the thermal lens spectroscopy could be used for the qualitative analysis of the photochemical reactions. In addition, we showed that the use of two different wavelengths for the excitation laser is a possible additional tool for determinate the presence of the photochemical reaction. We applied this dual-wavelength on/off excitation thermal lens approach to identify and quantify the photochemical behavior of the [Fe(TPTZ)2]+2 solution as a function the pH. We verify that the addition of chloride acid (HCl) in the solution reduced the activation barrier followed the Arrhenius correlation. Our results suggest that the dual-wavelength on-off Thermal lens technique may be contributed to the understanding of dynamics photo induced processes in complexes reaction. Neste trabalho apresentamos uma extensão do modelo de Shen-Pedreira para a técnica de espectroscopia de lente térmica aplicada no estudo da dinâmica de processos reação fotoquímica. O objetivo deste trabalho é mostrar que a espectroscopia de lente térmica pode ser usado para a análise qualitativa das reações fotoquímicas. Além disso, mostramos que a utilização de dois diferentes comprimentos de onda para o laser de excitação é uma possível ferramenta adicional para determinar a presença da reação fotoquímica. Nós aplicamos esta abordagem usando transientes "on-off" com dois comprimento de onda para identificar e quantificar o comportamento fotoquímico da solução de [Fe (TPTZ)2]+2 em função do pH. Verificamos que a adição de ácido clorídrico (HCl) na solução reduziu a barreira de ativação seguindo a correlação de Arrhenius. Nossos resultados sugerem que o espectroscopia de lente térmica utilizando diferentes comprimentos de ondas para excitação pode contribuír para a compreensão da dinâmica foto-induzidas em reações complexas. vii, 71 f

In this work, the structural and physical properties of the (0.6)BiFeO3-(0.4)PbTiO3 + x% La compounds, synthesized by high-energy ball milling, were investigated as a function of La concentration for understanding the structure/property relations in these materials. The X-ray and neutron diffraction results revealed potentialities for performing structural tuning by adding La in these materials. In fact, a structural phase transition, from tetragonal to romboedral, as well as the coexistence of both symmetries for 3% of La, was observed with the increase of the La content. In fact, the Rietveld refinement analyses indicated that the romboedral phase changes from R3m to R3c for 5 % of La. The transmission electron microscopic studies revealed narrow ferroelectric domain-walls in tetragonal (90° domainswalls) and romboedral (180° domain-walls) symmetries. The morphotropic phase boundary, which would be the interface between two symmetries in a same particle, was not observed in the sample studied in this work. The time dependency of the electrical resistivity, i. e., the equilibrium electrical resistivity, was analyzed and the results reveal that the La doping controls the formation of charge carriers in these materials. The "electric polarization vectors", per unit cell, were determined by using the mean average position of the cations and anions, obtained from the Rietveld refinement, and indicated polarized unit cells for all studied compositions. However, only those samples with 3% and 5% of La showed a measurable macroscopic ferroelectric behavior. In summary, the whole set of results indicate a strong correlation between ferroic properties and structure in all studied samples, and that these correlations can be changed by atomic, chemical and structural changes promoted by the La doping. Finally, the determination of the magnetoelectric response suggests that these compounds can potentiality used in advanced technological applications in multifunctional devices. Neste trabalho, as propriedades físicas e estruturais dos compostos (0,6)BiFeO3-(0,4)PbTiO3 + x% La, sintetizados por moagem em altas energias, foram investigadas em função da concentração de La com o intuito de compreender as relações estrutura/propriedade nesses materiais. Os resultados obtidos por difração de raios X e nêutrons revelaram a possibilidade de uma sintonização estrutural dos materiais estudados, por meio da adição de La. De fato, uma transição da simetria tetragonal para a simetria romboédrica, com o aumento da concentração de La, assim como a coexistência dessas duas simetrias para 3 % de La, foi observada. As análises por refinamento estrutural Rietveld indicaram que a simetria romboédrica muda do grupo espacial R3m para o R3c em amostras com 5 % de La. Os estudos por microscopia eletrônica de transmissão revelaram paredes de domínios ferroelétricos muito estreitas nas estruturas com simetria tetragonal (domínios de 90°) e romboédrica (domínios de 180°). O contorno de fases morfotrópico, que seria a interface entre duas simetrias estruturais presentes em uma mesma partícula, não foi observado na amostra estudada neste trabalho. A resistividade elétrica foi analisada e os resultados revelam que a dopagem com La controla a formação dos portadores de carga elétrica nesses materiais. Os "vetores momento de dipolo elétrico", por cela unitária, foram calculados a partir da posição média de cátions e ânions obtidas por refinamento estrutural Rietveld, e indicam que todas as composições têm suas celas unitárias polarizadas. Contudo, somente as amostras dopadas com 3 % e 5 % de La apresentam o comportamento ferroelétrico macroscópico mensurável. Em suma, o conjunto de resultados coletados neste trabalho indicou uma forte correlação entre as propriedades ferroicas e a estrutura das amostras estudadas, e que essa correlação pode ser alterada por meio das alterações atômicas, químicas e estruturais promovidas pela adição de La. Por fim, a determinação da resposta magnetoelétrica desses compostos nos permite inferir que os mesmos possuem um grande potencial para aplicações tecnonlógicas em dispositivos multifuncionais. xv, 182 f

In this work, Thermal Mirror spectroscopy (TMS), thermal relation calorimetry and Photothermal deflection spectroscopy (PDS) were used to detect and characterize the phase transition of the NiTi, normally known as Nitinol. The phases martensite, in ambient temperature, and austenite, in high temperature, were confirmed by X-ray diffraction. For comparison, the characteristics temperatures of the transition martensite-austenite were determined using the conventional techniques: DSC and the dilatometry, and compared with the obtained by Photothermal techniques. For the Thermal Mirror (TM), the behaviors of parameters θET and the thermal diffusivity, showed significant changes at the phase transition region, allowing the determination of their temperatures characteristics. Nevertheless, the behavior of these parameters is in agreement as expected comparing with the results obtained by the conventional techniques, quantitatively this obtained values, mainly for the thermal conductivity, show significant discrepancies, suggesting the necessity of consider the finite size of the sample, and the possibility effects of the anisotropy of the thermal and mechanical parameters on the model to describe the behavior of the superficial deformation induced by the local heat form the excitation beam. The thermal diffusivity behavior in the phase transition region obtained by TM, was confirmed using the Photothermal deflection spectroscopy modified. So far as we know, this is the first time that those techniques are applied for the metal material study in function of the temperature, in particular for the first order phase transition determination. Neste trabalho utilizamos as técnicas de Espelho Térmico (ET), Calorimetria de Relaxação Térmica e Deflexão Fototérmica (DF) para detectar e caracterizar a transição de fase da liga NiTi, comumente chamado de Nitinol. As fases martensita, (B19') em temperatura ambiente e austenita (B2) em alta temperatura foram confirmadas pela difratometria de raios-X (DRX). Para efeito de comparação, as temperaturas características da transição martensita-austenita foram determinadas utilizando técnicas convencionais: DSC e dilatometria, e confrontadas com as obtidas pelas técnicas fototérmicas. Para o ET o comportamento, tanto do parâmetro θET quanto da difusividade térmica, mostram significativas alterações na região de transição de fase, permitindo a determinação de suas temperaturas características. No entanto, apesar de qualitativamente o comportamento destes parâmetros apresentarem boa concordância com o esperado pela comparação com os resultados obtidos pelas técnicas convencionais, quantitativamente os valores obtidos, principalmente para a condutividade térmica, mostram discrepâncias bastante significativas, sugerindo a necessidade de se considerar o tamanho finito da amostra, bem como possíveis efeitos da anisotropia dos parâmetros térmicos e mecânicos no modelo para descrever o comportamento da deformação superficial induzido pelo aquecimento localizado do feixe de excitação. Por fim, o comportamento da difusividade térmica durante a transição de fase, obtidos pelo ET, foi confirmado utilizando a técnica de Deflexão Fototérmica modificada. Até onde sabemos, esta é a primeira vez que estas técnicas são empregadas para o estudo de materiais metálicos em função da temperatura, em particular para a determinação de transições de fase de primeira ordem. 76 f