Fotocatálise heterogênea de enterococcus faecalis e pseudomonas aeruginosa desencadeada pela ação da luz UV e branca em espátulas com revestimento de nanopartículas TiO2 e Ag

Nanotechnology, the science of minuscule, has developed products which are able t o manipulate atoms and molecules that could be applied in the sterilization process of dental instruments. Objetives: The objective of the present study was to evaluate the self-cleaning action of TiO2 and Ag nanoparticles coating on dental instruments by the photocataliys process under UV and visible light irradiation. Material and method: Microbiologic tests were done using dental cement spatulas coated with TiO2 and Ag nanoparticles (one or three layers), and contaminated with 10 mcrl of Pseudomonas aeruginosa and Enterococcus faecalis, respectively. After contamination, they were exposed to ultraviolet light and visible light for 120 minutes. Next, they were transferred to and stored in test tubes with BHI (Brain Heart Infusion) and incubated in 35 to 37 °C. Checking times for bacterial growth and for control and retrieval tests were done at: 24, 48, 72 and 96 hours. Result: The Pseudomonas aeruginosa was inactive after 120 minutes of ultraviolet light irradiation, thus confirming the heterogeneous photocatalytic activity of TiO2 and Ag. The Pseudomonas aeruginosa was not inactivated under visible light irradiation and the Enterococcus faecalis was not inactivated under UV and visible light irradiation of the dental cement spatulas coated with TiO2 and Ag nanoparticles in the readings to 96 hours, showing bacterial growth. Conclusion: There were no influence of one or three layers of TiO2 and Ag nanoparticles coating of the spatulas in the results. The heterogeneous photocatalysis activity of TiO2 and Ag under UV light irradiation was confirmed for Pseudomonas aeruginosa but not under visible light. Enterococcus faecalis did not confirmed the photocatalytics activity of TiO2 and Ag under UV light irradiation and visible lights irradiation.

Biomarker evaluation in fish after prolonged exposure to nano-TiO2: influence of illumination conditions and crystal phase

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeitos da luz visível associada à ftalocianina de cloro-alumínio na inativação da Borrelia anserina

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Multiwavelength visible and white light generation by upconversion emission in Ho/Tm/Yb triply doped fluorogermanate glass-ceramic

Energy transfer excited multiwavelength visible upconversion emission and white light generation is described in a single sample of PbGeO(3)-PbF(2)-CdF(2) glass-ceramic triply doped With Ho/Tm/Yb under single infrared laser excitation. Blue (475 nm), green (540 mn), and red (650 nm), upconversion luminescence signals are generated, and the emissions are assigned, respectively, to thulium ((1)G(4)-(3)H(6)), and holmium ((5)S(2);(5)F(4)) -> (5)I(8), (5)F(5) -> (5)I(8)) ions transitions, both excited via successive energy transfers from ytterbium ions. It is experimentally shown that with a proper combination of the rare earth ions contents, white light may be produced, with the simultaneous generation of fluorescence with controllable intensities at the wavelengths of the three primary colours in a single sample and using a single near-infrared excitation source.

Performance characteristics of UV and visible spectrophotometry methods for quantitative determination norfloxacin in tablets

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The role of structural order-disorder for visible intense photoluminescence in the BaZr0.5Ti0.5O3 thin films

The nature of the intense visible room temperature photoluminescence of BaZr0.5Ti0.5O3 non-crystalline thin films is discussed in the light of experimental results and theoretical calculations. The photoluminescence measurements reveal that the emission intensity changes with the degree of disorder in the BaZr0.5Ti0.5O3 lattice. First principles quantum mechanical techniques, based on density functional theory at B3LYP level, have been employed to study the electronic structure of a crystalline model and of structurally disordered models in order to detect the influence of disorder on the electronic structure. An analysis of the electronic charge distribution reveals local polarization in the disordered structures. The relevance of the present theoretical and experimental results on the photoluminescence behavior of BZT is discussed. (C) 2005 Elsevier B.V. All rights reserved.

Conditions giving rise to intense visible room temperature photoluminescence in SrWO4 thin films: the role of disorder

The nature of intense visible photoluminescence at room temperature of SrWO4 (SWO) non-crystalline thin films is discussed in the light of experimental results and theoretical calculations. The SWO thin films were synthesized by the polymeric precursors method. Their structural properties have been obtained by X-ray diffraction data and the corresponding photoluminescence (PL) spectra have been measured. The UV-vis optical spectra measurements suggest the creation of localized states in the disordered structure. The photoluminescence measurements reveal that the PL changes with the degree of disorder in the SWO thin film. To understand the origin of visible PL at room temperature in disordered SWO, we performed quantum-mechanical calculations on crystalline and disordered SWO periodic models. Their electronic structures are analyzed in terms of DOS, hand dispersion and charge densities. We used DFT method with the hybrid non-local B3LYP approximation. The polarization induced by the symmetry break and the existence of localized levels favors the creation of trapped holes and electrons, giving origin to the room temperature photoluminescence phenomenon in the SWO thin films. (c) 2004 Elsevier B.V. All rights reserved.

First principles calculations on the origin of violet-blue and green light photoluminescence emission in SrZrO3 and SrTiO3 perovskites

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lanthanide-Containing Light-Emitting Organic-Inorganic Hybrids: A Bet on the Future

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efficient UV-visible upconversion luminescence and thermal effects in terbium-ytterbium codoped fluorogermanate vitroceramic

Cooperative energy-transfer upconversion luminescence in Tb 3+/Yb 3+-codoped PbGeO 3-PbF 2-CdF 2 vitroceramic and its precursor glass under resonant and off-resonance infrared excitation, is investigated. Bright UV-visible emission signals around 384, 415, 438 nm, and 473-490, 545, 587, and 623 nm, identified as due to the 5D 3( 5G 6 → 7F J(J=6,5,4) and 5D 4 → 7F J(J=6,5,4,3) transitions, respectively, were readily observed. The results indicate that cooperative energy-transfer between ytterbium and terbium ions followed by excited-state absorption are the dominant upconversion excitation mechanisms herein involved. The comparison of the upconversion process in a vitroceramic sample and its glassy precursor revealed that the former present much higher upconversion efficiency. The dependence of the upconversion emission upon pump power, temperature, and doping content is also examined.

LED light attenuation through human dentin: A first step toward pulp photobiomodulation after cavity preparation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Decoration of Ti/TiO2 Nanotubes with Pt Nanoparticles for Enhanced UV-Vis Light Absorption in Photoelectrocatalytic Process

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Sprayed films of europium complexes toward light conversion devices

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação da termociclagem sobre a estabilidade de cor de diferentes matizes de resina composta

The objective was to evaluate the effect of thermocycling on the color variation of three different composite resins . We studied was Resin Enamel on 3 levels : ( Esthetic X , Opallis and Venus ) ; Resin Dentin in three levels : ( Esthetic X , Opallis and Venus ) and Thermocycling on level 1 : ( 3,000 cycles ) ; variable was the change of color gauged by spectrophotometry . 60 specimens , subdivided into 6 groups were made : GI - Esthetic X Enamel ; GII - Esthetic X dentin ; GIII - Opallis Enamel ; GIV - Opallis dentin ; GV - Enamel and GVI Venus - Venus dentin . The specimens were prepared with a matrix to standardize samples . The inserts of incrementally resins and polymerized with a halogen light Ultralux unit ( Dabi Atlante , Brazil ) with a power of 450mW / cm ² . After fabrication , underwent color reading with a UV Visible Spectrophotometer reflection , UV -2450 ( Shimadzu , Kyoto , Japan ) , with the changes calculated by the system CIE L * a * b * . Then isolates were stored in artificial saliva at 35 ° C ± 2 ° C during 3 months containers being subjected to the effects of thermal cycling for 3000 cycles over the range of 5C to 55C . Again subjected to chromatic evaluation. For the analysis of the results of color change of the studied resins was applied ANOVA two factors at 5 % . The results showed a statistically equal resins enamel GI and GV ( p = 0.79 ) ; the same was not observed for GI and G III resins , where the color change was higher for resin G III ( p = 0.0000002 ) . The same was observed between G III and GV , where the resin enamel G III showed a statistically superior to the color change ( p = 0.0000005 ) Average . Resins to dentin was there a statistical equality between the materials studied . We conclude that the resins studied change in color and resin enamel G III was the most suffered major color changes after aging by thermocycling .