"In vitro" performance of 2-step, total etch adhesives modified by thiourethane additives

Orientadores: Lourenço Correr Sobrinho, Carmem Silvia PfeiferTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: Objetivo: avaliar as propriedades físicas e a resitência de união à microtração de adesivos experimentais contendo oligômeros de tiouretano (TU) e/ou partículas de carga funcionalizadas com TU. Materiais e métodos: uma matriz orgânica base contendo 60%BisGMA/40%HEMA (peso) +0,2% DMPA 1 (fotoiniciador) + 0,5% BHT(inbidor) - (BH-controle) foi formulada; o oligômero de TU PETMP-DEMODUR (tetrafuncional) foi sintetizado e adicionado em 20%(peso) à matriz orgânica dos grupos contendo TU (BH+ 20%TU); para os grupos contendo partículas de carga, estas foram funcionalizadas com metacrilato-MF ou com tiouretano-TF e adicionadas em 10%(vol). Os grupos experimentais foram: BH; BH+10%MF; BH+10%TF; BH+20%TU+10%MF; BH+20%TU+10%TF; BH+20%TU. Os grupos foram submetidos aos testes: resistência de união à microtração (RUMT) em 24 h e 6 meses em dentina hígida (n=6); resistência à flexão (RF) por três pontos em ambiente seco (n=6) e armazenadas em água por 7 dias (n=6); Cinética de polimerização (n=3) (grau de conversão-GC e taxa máxima de polimerização-Rpmax); Sorção e Solubilidade (SR/SL) (n=3); e, Viscosidade (V)(n=3). Para a RUMT, foi adicionado 40% etanol(vol) aos grupos experimentais. Os dados foram submetidos a ANOVA um fator e teste de Tukey (p0,5) e RF a seco (p>0,05), não houve diferença significativa entre os grupos. Os grupos contendo TU na matriz apresentaram os menores valores de RF (p0.05). For the comparison of storage time for the microtensile bond strength test, data were submitted to t test (p>0.05). For the microtensile bond strength test (p=0.13) and WS/SL (p>0.05), no significant difference was found between groups. For the YS and YM (p>0.05), the dry evaluation had no significant difference in YS, although for the YM BH+10%MF, BH+10%TF and BH+20%TU+10%MF had the highest values compared to BH, BH+20%TU+10%TF and BH+20%TU and in the wet evaluation, the groups containing TU in the matrix had the lowest values in YS and YM. The polymerization kinects for the groups containing TU in the matrix had the highest DC and no significant difference was found between groups for the DC at Rpmax. The Rpmax was higher for the BH+20%TU+10%MF, followed by BH and BH+10%TF, and the lowest Rpmax values were found for the BH+10%MF, BH+20%TU+10%TF and BH+20%TU. The groups containing TU in the matrix had the highest values for viscosity, being that the BH+20%TU+10%TF that has TU in the matrix and on the functionalized fillers had the highest values with statistical significant difference for the BH+20%TU+10%MF and BH+20%TU. The addition of TU in the matrix improved the final degree of conversion of the experimental adhesives and the bond strength maintained stable after 6 months of storage in water. With that, the addition of TU in the matrix of experimental adhesives improved the final Degree of conversion is a promising strategyDoutoradoMateriais DentariosDoutora em Materiais Dentários0878/2018CAPE

Influence of chemical degradation and abrasion on surface properties of nanorestorative materials

Aim: The aim of this in vitro study was to investigate the synergistic effect of chemical degradation (erosion) and three-body abrasion (mechanical degradation) on the surface roughness (Ra) and hardness (KHN) of two nanorestorative materials and two conventional materials. Methods: Discshaped specimens (5 mm in diameter, 2 mm thick) of Filtek Z350™ and TPH Spectrum™ composites and Ketac Nano™ and Vitremer™ light-curing glass ionomer cements, nanomaterials and conventional materials were prepared according to the manufacturer's instructions. After 24 h, polishing procedures were performed and initial measurements of Ra and KHN were taken in all specimens. The specimens were divided into 12 groups (n = 10) according to material and storage media: artificial saliva, orange juice, and Coca-Cola®. After 30 days of storage, the specimens were submitted to mechanical degradation and re-evaluated for Ra and KHN. Data were tested for significant differences by repeated-measure three-way ANOVA and Tukey's tests (p<0.05). Results: Erosion and abrasion wear significantly decreased hardness of all materials. Only Filtek Z350 roughness, however, was not affected by erosion and abrasion. All materials showed a significant increase in surface roughness after erosion and abrasion, except for Filtek Z350. After chemical and mechanical degradation, the KHN of all samples had decreased significantly. After mechanical degradation, the acidic drinks (Coca-Cola® and orange juice) were more aggressive than artificial saliva to all materials. Conclusions: A synergistic effect was observed by the increase in roughness for all materials, except for Filtek Z350; hardness values decrease for all materials, regardless of whether they were nanofilled or not. The RMGICs were more susceptible to degradation than the composites, considering both hardness and roughness surface parameters142100105sem informaçã

Component metadata management and publication for the grid

There is growing attention to component-oriented software design of Grid applications. Within this framework, applications are built by assembling together independently developed software components. Two main approaches are commonly used to manage, develop and publish software components: one is based on an Interface Description Language (IDL); the other is typical, for instance, of Java and is based on introspection and design conventions. In this paper, we compare them and we propose a third approach that merges the flexibility and fast learning curve of the latter, with the rigor of the former. Our proposal is meant to help the transition towards more modern tools, which is required to develop versatile Grid applications. © 2005 IEEE

Gallone Samples Archive: a resource for Cultural Heritage studies

A vast collection of samples from artworks. A unique resource for future research in the field of conservation: investigating samples, implementing more advanced techniques

Driving rate effects in avalanche-mediated, first-order phase transitions

We have studied the driving rate and temperature dependence of the power-law exponents that characterize the avalanche distribution in first-order phase transitions. Measurements of acoustic emission in structural transitions in Cu-Zn-Al and Cu-Al-Ni are presented. We show how the observed behaviour emerges within a general framework of competing time scales of avalanche relaxation, driving rate, and thermal fluctuations. We have confirmed our findings by numerical simulations of a prototype model.Comment: 4 pages, 3 figure

Time- and angle-resolved photoemission spectroscopy on bidimensional semiconductors with a 500 kHz extreme ultraviolet light source

This thesis describe the developement of a high-repetion rate time- and angle-resolved photoemission experimental setup. First, the work describes the light source developed for the experiment, based on ultrafast Ytterbium lasers and optical paramentric chirped pulse amplification. In the second part the light source is frequency upconverted to the extreme-ultravioled using the process high-harmonic generation. Finally, the experimental setup is described and applied to studies of ultrafast carrier dynamics in the 2D semiconductor tungsten diselenide

Revealing the role of electrons and phonons in the ultrafast recovery of charge density wave correlations in 1TT-TiSe2_2

Using time- and angle-resolved photoemission spectroscopy with selective near- and mid-infrared photon excitations, we investigate the femtosecond dynamics of the charge density wave (CDW) phase in 1$T$-TiSe$_2$, as well as the dynamics of CDW fluctuations at 240 K. In the CDW phase, we observe the coherent oscillation of the CDW amplitude mode. At 240 K, we single out an ultrafast component in the recovery of the CDW correlations, which we explain as the manifestation of electron-hole correlations. Our momentum-resolved study of femtosecond electron dynamics supports a mechanism for the CDW phase resulting from the cooperation between the interband Coulomb interaction, the mechanism of excitonic insulator phase formation, and electron-phonon coupling.Comment: 9 pages, 6 figure

Psyllium como substituto de glúten

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Ciências da Saúde, Programa de Pós-Graduação em Nutrição Humana, 2006.A doença celíaca (DC) é uma enteropatia imunomediada, que apresenta intolerância permanente ao glúten ingerido, a qual atualmente tem como única forma de tratamento a retirada do glúten da dieta. Após o início da dieta os indivíduos portadores de DC apresentam dificuldade na aquisição e também no preparo de alimentos isentos de glúten, o que dificulta a adesão ao tratamento. Além disso, os alimentos modificados para esse tipo de patologia apresentam prejuízos nas características sensoriais e, para compensar tecnologicamente a retirada do glúten, acrescenta-se grande quantidade de lipídios a essas preparações, o que conduz ao ganho excessivo de peso dos indivíduos em tratamento. Nesse contexto, o presente trabalho tem como objetivo avaliar o efeito da substituição do glúten pelo psyllium (Plantago ovata) nas características sensoriais de preparações isentas de glúten; comparar as características químicas, nutricionais, tecnológicas e sensoriais das preparações modificadas. Foram selecionadas cinco preparações - pão, pizza, bolo, biscoito e macarrão - privilegiando além da isenção de glúten, a redução calórica e lipídica dos produtos, conforme desejo manifestado pelos celíacos por meio de sua associação - Acelbra. Os dados da análise sensorial para os produtos modificados em massas para pão, biscoito, bolo, macarrão, pizza indicam que os produtos apresentaram boa aceitação tanto pelos portadores como pelos não portadores de DC. Em termos de composição química, os produtos obtidos com as massas modificadas para pão, biscoito, macarrão, bolo e pizza apresentaram redução da fração de lipídios de 42,3%; 54,8%; 85,4%; 50,0% e 41,0% respectivamente e também do valor do valor energético de 32,1%; 4,0%; 26,5% e 15,6% respectivamente. Dessa forma amplia-se a oferta de produtos para portadores dessa patologia, dentro de uma visão de alimentação saudável, proporcionando melhoria na qualidade de vida desses indivíduos

A Search Engine Architecture Based on Collection Selection

In this thesis, we present a distributed architecture for a Web search engine, based on the concept of collection selection. We introduce a novel approach to partition the collection of documents, able to greatly improve the effectiveness of standard collection selection techniques (CORI), and a new selection function outperforming the state of the art. Our technique is based on the novel query-vector (QV) document model, built from the analysis of query logs, and on our strategy of co-clustering queries and documents at the same time. Incidentally, our partitioning strategy is able to identify documents that can be safely moved out of the main index (into a supplemental index), with a minimal loss in result accuracy. In our test, we could move 50\% of the collection to the supplemental index with a minimal loss in recall. By suitably partitioning the documents in the collection, our system is able to select the subset of servers containing the most relevant documents for each query. Instead of broadcasting the query to every server in the computing platform, only the most relevant will be polled, this way reducing the average computing cost to solve a query. We introduce a novel strategy to use the instant load at each server to drive the query routing. Also, we describe a new approach to caching, able to incrementally improve the quality of the stored results. Our caching strategy is effectively both in reducing computing load and in improving result quality. By combining these innovations, we can achieve extremely high figures of precision, with a reduced load w.r.t.~full query broadcasting. Our system can cover 65\% results offered by a centralized reference index (competitive recall at 5), with a computing load of only 15.6\%, \ie a peak of 156 queries out of a shifting window of 1000 queries. This means about 1/4 of the peak load reached when broadcasting queries. The system, with a slightly higher load (24.6\%), can cover 78\% of the reference results. The proposed architecture, overall, presents a trade-off between computing cost and result quality, and we show how to guarantee very precise results in face of a dramatic reduction to computing load. This means that, with the same computing infrastructure, our system can serve more users, more queries and more documents