Utilização de um espectrofotómetro experimental para a medição simultânea de cor e brilho em medicina dentária : estudo preliminar comparativo

Dissertação para obtenção do grau de Mestre no Instituto Universitário Egas MonizIntrodução: O sucesso estético de uma restauração está diretamente relacionado com as suas propriedades óticas e a sua avaliação, na prática clínica, é atualmente subjetiva. Objetivos: Avaliar e comparar a cor e o brilho de 2 resinas compostas diretas, com auxílio de espectrofotómetro e brilhómetro. Avaliar a eficácia do novo instrumento experimental para medições óticas.. Materiais e métodos: Foram testadas 2 resinas compostas: 3MTM FiltekTM Supreme XTE (nanoparticulada) e 3MTM Filtek Z250 (microhíbrida). Foram confecionados 12 discos de cada resina em estudo, tanto na cor A1 (n=6) como na cor A4 (n=6). Os 6 discos de cada cor foram alocados aleatoriamente em 2 subgrupos, em que em 3 discos foi realizado a fotopolimerização sobre uma matriz de Mylar, sem modificações adicionais, e nos outros 3 foi aplicado o protocolo de polimento com uma lixa de papel (320 grit SiC). No final, foi feita a avaliação da cor e do brilho de todas as amostras, com auxílio dos equipamentos padrão comerciais - SpectroShadeTM Micro e Glossmeter Micro-Gloss 60º Nº4501 – e por um novo instrumento experimental de medição biaxial da cor e brilho (SARSPEC Flex), de modo a comparar os valores obtidos. Os dados laboratoriais foram analisados com recurso ao programa SPSS 28.0, com um nível de significância 5%. Resultados: A variação da resina composta não teve impacto significativo na refletância e nos parâmetros L*, a* e b* (p>0,05). A variação da cor teve resultados significativos nos parâmetros L* e b* (p<0,01), mas não sobre a refletância (p=0,885) ou sobre o parâmetro a* (p=0,068). Os diferentes acabamentos de superfície têm apenas um impacto significativo sobre a refletância (p=0,004) menos à exceção do parâmetro a* (p=0,897). Por último, o aparelho SARSPEC Flex inovador, em comparação com os aparelhos comerciais de medição de cor e brilho obteve diferenças significativas em todos os parâmetros analisados (p<0,001). Conclusões: O SARSPEC Flex apesar de ser um instrumento inovador, com medição biaxial da cor e do brilho, ainda é muito experimental, sendo necessário desenvolver mais estudos de forma a promover melhores resultados.Introduction: The aesthetic success of a restoration is directly related to its optical properties and its evaluation, in clinical practice, is currently subjective. Objectives: Evaluate and compare the color and brightness of 2 direct composite resins, with the aid of spectrophotometer and brilhometer. Evaluate the effectiveness of the new instrument for optical measurements. Materials and Methods: Two composite resins were tested: 3MTM FiltekTM Supreme XTE (nanoparticle) and 3MTM Filtek Z250 (microhybrid). 12 discs of each resin under study were made, both in color A1 (n=6) and in color A4 (n=6). The 6 discs of each color were randomly allocated in 2 subgroups, in which in 3 discs, light curing was performed on a Mylar matrix, without additional modifications, and in the other 3 the polishing protocol was applied with a 320 grit SiC paper. In the end, the color and brightness of all samples were evaluated, with the aid of standard commercial equipment - SpectroShadeTM Micro and Glossmeter Micro-Gloss 60º Nº4501 - and by a new experimental instrument for biaxial color and gloss measurement (SARSPEC Flex), to compare the values obtained. Laboratory data were analyzed using the SPSS 28.0 program, with a significance level of 5%. Results: The variation of the composite resin had no significant influence on reflectance and parameters L*, a* and b* (p>0.05). The color variation had significant results in the parameters L* and b* (p<0.01), but not on the reflectance (p=0.885) or on the a* parameter (p=0.068). The different surface finishes have only a significant influence on reflectance (p=0.004) minus a* parameter (p=0.897). The SARSPEC Flex compared to the commercial color and gloss measuring devices obtained significant differences in all parameters analyzed (p<0.001). Conclusion: The SARSPEC Flex, despite being an innovative instrument, with biaxial measurement of color and brightness, is still very experimental. More research is needed to foster better results

Flexitests ::pédagogies actives en psychologie expérimentale

Flexitests est une application web permettant à des étudiants1 sans compétences informatiques de concevoir et développer des tests de psychologie. Cette application rend possible de nouvelles approches pédagogiques pour des enseignements de neurosciences comportementales, en permettant notamment aux étudiants de passer des tests standards ou en leur proposant de créer leurs propres tests

Spectral Signal-to-Noise Ratio and Resolution Assessment of 3D Reconstructions

Measuring the quality of three-dimensional (3D) reconstructed biological macromolecules by transmission electron microscopy is still an open problem. In this article, we extend the applicability of the spectral signal-to-noise ratio (SSNR) to the evaluation of 3D volumes reconstructed with any reconstruction algorithm. The basis of the method is to measure the consistency between the data and a corresponding set of reprojections computed for the reconstructed 3D map. The idiosyncrasies of the reconstruction algorithm are taken explicitly into account by performing a noise-only reconstruction. This results in the definition of a 3D SSNR which provides an objective indicator of the quality of the 3D reconstruction. Furthermore, the information to build the SSNR can be used to produce a volumetric SSNR (VSSNR). Our method overcomes the need to divide the data set in two. It also provides a direct measure of the performance of the reconstruction algorithm itself; this latter information is typically not available with the standard resolution methods which are primarily focused on reproducibility alone

The Versatility of the Helicobacter pylori Vacuolating Cytotoxin VacA in Signal Transduction and Molecular Crosstalk

By modulating important properties of eukaryotic cells, many bacterial protein toxins highjack host signalling pathways to create a suitable niche for the pathogen to colonize and persist. Helicobacter pylori VacA is paradigm of pore-forming toxins which contributes to the pathogenesis of peptic ulceration. Several cellular receptors have been described for VacA, which exert different effects on epithelial and immune cells. The crystal structure of VacA p55 subunit might be important for elucidating details of receptor interaction and pore formation. Here we discuss the multiple signalling activities of this important toxin and the molecular crosstalk between VacA and other virulence factors

Status and Prospects of ZnO-Based Resistive Switching Memory Devices

In the advancement of the semiconductor device technology, ZnO could be a prospective alternative than the other metal oxides for its versatility and huge applications in different aspects. In this review, a thorough overview on ZnO for the application of resistive switching memory (RRAM) devices has been conducted. Various efforts that have been made to investigate and modulate the switching characteristics of ZnO-based switching memory devices are discussed. The use of ZnO layer in different structure, the different types of filament formation, and the different types of switching including complementary switching are reported. By considering the huge interest of transparent devices, this review gives the concrete overview of the present status and prospects of transparent RRAM devices based on ZnO. ZnO-based RRAM can be used for flexible memory devices, which is also covered here. Another challenge in ZnO-based RRAM is that the realization of ultra-thin and low power devices. Nevertheless, ZnO not only offers decent memory properties but also has a unique potential to be used as multifunctional nonvolatile memory devices. The impact of electrode materials, metal doping, stack structures, transparency, and flexibility on resistive switching properties and switching parameters of ZnO-based resistive switching memory devices are briefly compared. This review also covers the different nanostructured-based emerging resistive switching memory devices for low power scalable devices. It may give a valuable insight on developing ZnO-based RRAM and also should encourage researchers to overcome the challenges