Microhardness assessment of different commercial brands of resin composites with different degrees of translucence

Owing to improvements in its mechanical properties and to the availability of shade and translucence resources, resin composite has become one of the most widely used restorative materials in present day Dentistry. The aim of this study was to assess the relation between the surface hardness of seven different commercial brands of resin composites (Charisma, Fill Magic, Master Fill, Natural Look, Opallis, Tetric Ceram, and Z250) and the different degrees of translucence (translucid, enamel and dentin). Vickers microhardness testing revealed significant differences among the groups. Z250 was the commercial brand that showed the best performance in the hardness test. When comparing the three groups assessed within the same brand, only Master Fill and Fill Magic presented statistically significant differences among all of the different translucencies. Natural Look was the only one that showed no significant difference among any of the three groups. Charisma, Opallis, Tetric Ceram and Z250 showed significant differences among some of the tested groups. Based on the results found in this study, it was not possible to establish a relation between translucence and the microhardness of the resin composites assessed. Depending on the material assessed, however, translucence variation did affect the microhardness values of the resin composites

Utility perception on virtual learning environments used in Brazilian blended learning

This research aimed to use a data collection instrument, previously proposed, with the purpose of evaluating 11 different factors related to the perception of self-declared utility by users of a virtual learning environment and its information and communication technologies, as pedagogical resources used in the implementation of the blended learning methodology. Based on descriptive statistics and the application of the non-parametric test of Wilcoxon posts, a comparative assessment was carried out between the levels of utility perceived by 71 students and their teachers, in three curricular components of different undergraduate courses of a public university in the state from São Paulo. In addition, Cronbach's alpha coefficient was used to measure the reliability of the data collection instrument used in this research. At the end of this study, it was observed that, although the subjects included in the sample of this research present different levels of perception of utility for most of the factors analyzed, there is a certain degree of convergence in relation to the factors considered most relevant by both, that is, teachers and students attributed a greater perception of usefulness to factors such as interaction and complementarity between classroom and online content, and also to the general utility of information and communication technologies in the respective virtual learning environment. In the specific case of students, the interaction between teacher and student was also considered as one of the most important factors, in the three undergraduate courses analyzed

DETERMINAÇÃO DO ÂNGULO DE REPOUSO, VOLUME UNITÁRIO, EIXOS ORTOGONAIS E ESFERICIDADE DE TRIGO

O conhecimento das propriedades físicas de cereais é necessário para o dimensionamento de máquinas e equipamentos. O objetivo do presente estudo foi determinar o ângulo de repouso, tamanho e esfericidade das sementes de trigo. O experimento foi realizado no Laboratório do Núcleo de Tecnologia em Armazenagem, da Faculdade de Agronomia, Medicina Veterinária e Zootecnia do Campus Universitário de Cuiabá da Universidade Federal de Mato Grosso, em delineamento experimental inteiramente casualizado com sete variedades de trigo: (BRS 18; BRS 254; EP 011210; IAC 24; IAC 350; SUPERA; VI 98053) e três repetições. De acordo com o trabalho houve diferença nas propriedades físicas das diferentes cultivares de trigo. Havendo variação de 5,5 a 6,64 mm; 55,93 a 63,04 %; 17,75 a 20,86° para comprimento de sementes, esfericidade e ângulo de repouso respectivamente

Síntese de materiais mesoporosos com arranjo hexagonal ordenado de poros, modificados com grupos orgânicos de interesse

Neste trabalho, duas organosílicas com estruturas de poros ordenados foram obtidas através de rotas distintas. As características texturais e estruturais dessas organosílicas foram estudadas por difração de raios X, microscopia eletrônica de transmissão e isotermas de adsorção/dessorção de N2. A presença dos componentes orgânicos foi avaliada por espectroscopia de absorção na região do infravermelho, termogravimetria e análise elementar. A primeira organosílica foi obtida através da modificação química da superfície de uma sílica do tipo SBA-15 sintetizada no nosso laboratório, com o grupo orgânico 3-mercaptopropil, usando o método grafting, sendo posteriormente utilizada na adsorção de paládio (II) através da coordenação do metal com o grupo mercapto de forma estequiométrica. A presença de paládio foi identificada por microscopia eletrônica de varredura acoplada à espectroscopia de dispersão de elétrons como também por espectrometria de absorção atômica. A segunda organosilica foi obtida através da condensação simultânea de tetraetilortosilicato com um precursor bisililado contendo o grupo catiônico 4,4-bipiridinio, sintetizado em nosso laboratório, na presença de um agente direcionador de estrutura. Quatro amostras desse material com variadas proporções orgânico/inorgânico foram sintetizadas. As alterações nas propriedades texturais e estruturais foram estudadas em função do aumento do conteúdo orgânico. O acréscimo na quantidade de grupo orgânico iônico produz uma diminuição na ordenação estrutural dos poros e, ao mesmo tempo, converte poros com diâmetro de 6,3 nm em poros com diâmetro em torno 3,5 nm, todos com distribuição unimodal.In this work, two organosilicas with ordered pore structures were obtained by two distinct routes. The textural and structural characteristics of these organosilicas were studied by X-ray diffraction, transmission electron microscopy, and N2 adsorption/desorption isotherms. The presence of organic components was evaluated by infrared spectroscopy, thermogravimetry, and CHN elemental analysis. The first organosilica was obtained by chemical modification of SBA-15 surface synthesized on our lab, with 3-mercaptopropyl organic group by grafting method, which was afterwards used for Palladium adsorption by the stoichiometric coordination of the metal with the mercapto group. The presence of palladium was identified by scanning electron microscopy coupled with electron dispersive spectroscopy detector, as well as, by atomic absorption spectrometry. The second organosilica was obtained by simultaneous condensation of tetraethylorthosilicate with a bisililated precursor containing the organic 4,4-bipyridinium cationic group, synthesized in our laboratory, in the presence of a structure directing agent. Four samples with varied organic/inorganic proportions were synthesized. Textural and structural changes were studied in relation to organic content increasing. The growing of ionic organic group amount produces a decreasing in the ordering of pore structure, and, at the same time, converts pores of 6.3 nm of diameter into pores with 3.5 nm, both with narrow distribution

Correlation between the infestation level of Sitophilus zeamais Motschulsky, 1855 (Coleoptera, Curculionidae) and the quality factors of stored corn, Zea mays L. (Poaceae)

This experiment was carried out in order to evaluate the effect of Sitophilus zeamais on physical, physiological and sanitary quality of stored corn. Samples of 500 g of the hybrid OC-705, in three replicates, were conditioned in glasses covered with a screened lid, and kept in chamber at 25±2ºC, 70±5% RH and 12 h of photophase, for 150 days. The infestation levels were 0, 5, 15 and 50 adults/replicate, for the storage periods of 30, 60, 90, 120 and 150 days. The moisture content, classification, weight loss, germination and internal infestation were evaluated monthly. Significant inverse correlations were verified between the number of insects and both the germination and the weight loss; also between the internal infestation and the germination and the standard type. The presence of S. zeamais showed a positive correlation with the weight loss, what means that the internal and external infestations contribute to the reduction of physiological and physical quality of corn seeds. The mean dry matter loss was 0,36%/day, corresponding to a consumption of 0,0001%/insect/month. As the result of those damages, the product suffered reduction of the commercial grade in 30 days, with significant loss in all quality factors

Influence of surfactants on the effectiveness of bleaching gels

This study evaluated the influence of surfactants on the effectiveness of 35% hydrogen peroxide (HP) and 10% carbamide peroxide (CP) bleaching gels. One hundred and forty bovine teeth were used, which were stained by immersion in a coffee, red wine, and tobacco mixture for 7 days. At the end of this process, the color measurement at baseline was taken with the Vita Easyshade spectrophotometer. The teeth were divided into seven groups: (a) negative control (NC), (b) positive control for HP (PC-35), (c) HP + Tween 20 (T20-35), (d) HP + laurel sodium sulfate (LSS-35), (e) positive control for CP (PC-10), (f) CP + Tween 20 (T20-10), and (g) CP + laurel sodium sulfate (LSS-10). Group NC was kept in artificial saliva for 21 days. Groups PC-35, T20-35, and LSS 35 received three applications of bleaching gel for 10 min; the process was repeated after 7 days. Groups PC-10, T20-10, and LSS-10 received the gel for 8 h per day for 14 days. After the bleaching process, the final color was measured. The analysis of variance and Tukey tests showed statistically significant differences for the parameters of a dagger L, a dagger b, and a dagger E of the HP gels with surfactant and positive control group (PC-35). Within the limits of this in vitro study, the addition of surfactants to HP bleaching gel increased the bleaching effectiveness

Effects of dental bleaching on the color, translucency and fluorescence properties of enamel and dentin

The objective of this study was to evaluate the color, translucency and fluorescence of bovine enamel and dentin submitted to different bleaching modalities. Pairs of enamel and dentin discs (3 mm in diameter) were obtained from 150 bovine teeth. In 75 of the pairs, one specimen had the enamel removed (Dentin Group). The dentin was removed from one specimen of the remaining 75 pairs (Enamel Group) and the other specimen was left unaltered (Enamel + Dentin). The evaluation of color, translucency and fluorescence was performed with a spectrophotometer using the CIE L* a* b*. Each group was subdivided into three subgroups: Control, composed of specimens that were not bleached, and two experimental subgroups, bleached with either 10% carbamide peroxide (CP10%) or 35% hydrogen peroxide (HP35%). The CP10% bleaching gel was applied 2 h/day for 14 days. The HP35% bleaching agent was applied using two applications of 30 min each, with a one week interval between each application. When not being bleached, the specimens were immersed in artificial saliva. The color, translucency and fluorescence ratings were assessed using spectrophotometry 7 days after the treatment. Regarding color, significant differences were found between bleaching techniques in the groups Enamel and Enamel + Dentin, with a higher color difference for HP35%. Bleaching did not change the translucency of the dental tissues. There were significant differences for fluorescence for the HP35% subgroups of Dentin and Enamel + Dentin, and for the CP10% subgroup of Enamel. Dental bleaching changed the color and fluorescence of the dental tissues, however translucency was not affected

Embryonic development and larval stages of Steindachneridion parahybae (Siluriformes: Pimelodidae): implications for the conservation and rearing of this endangered Neotropical species

Steindachneridion parahybae is a freshwater catfish endemic to the Paraíba do Sul River and is classified as an endangered Neotropical species. An increasing number of conservation biologists are incorporating morphological and physiological research data to help conservation managers in rescue these endangered species. This study investigated the embryonic and larval development of S. parahybae in captivity, with emphasis in major events during the ontogeny of S. parahybae. Broodstocks were artificially induced to reproduce, and the extrusion occurred 200-255 degree-hours after hormonal induction at 24°C. Larval ontogeny was evaluated every 10 minutes under microscopic/stereomicroscopic using fresh eggs samples. The main embryogenic development stages were identified: zygote, cleavage, including the morula, blastula, gastrula phase, organogenesis, and hatching. The extruded oocytes showed an average diameter of 1.10 ± 0.10 mm, and after fertilization and hydration of eggs, the average diameter of eggs increased to about 1.90 ± 0.60 mm, characterized by a large perivitelline space that persisted up to embryo development, the double chorion, and the poles (animal and vegetative). Cell division started about 2 minutes after fertilization (AF), resulting in 2, 4, 8 (4 x 2 arrangement of cells), 16 (4 x 4), 32 (4 x 8) and 64 (2 x 4 x 8) cells. Furthermore, the blastula and gastrula stages followed after these cells divisions. The closed blastopore occurred at 11 h 20 min AF; following the development, the organogenetic stages were identified and subdivided respectively in: early segmentation phase and late segmentation phase. In the early segmentation phase, there was the establishment of the embryonic axis, and it was possible to distinguish between the cephalic and caudal regions; somites, and the optic vesicles developed about 20 h AF. Total hatching occurred at 54 h AF, and the larvae average length was 4.30 ± 0.70 mm. Gradual yolk sac reduction was observed during the first two days of larval development. The first feeding occurred at the end of the second day. During the larval phase, cannibalism, heterogeneous larval growth and photophobia were also observed. This information will be important in improving the artificial reproduction protocols of S. parahybae in controlled breeding programs.<br>Steindachneridion parahybae é um bagre de água doce, endêmico do rio Paraíba do Sul e é classificado como espécie neotropical ameaçada. Um número crescente de biólogos conservacionistas estão incorporando dados de pesquisas morfológicas e fisiológicas para ajudar os gestores de conservação no resgate destas espécies ameaçadas de extinção. Este estudo investigou o desenvolvimento embrionário e larval de S. parahybae em cativeiro, com ênfase nos principais eventos durante a ontogenia de S. parahybae. Reprodutores foram artificialmente induzidos à reprodução e a extrusão ocorreu com 200-255 horas-graus após a indução hormonal a 24°C. A ontogenia larval foi avaliada a cada 10 minutos sob microscópio/ estereomicroscópio, utilizando-se amostras de ovos recém coletados. Os principais estágios de desenvolvimento embrionário foram identificados: zigoto, clivagem, incluindo as fases, mórula, blástula e gástrula, organogênese e eclosão. Os ovócitos extrusados apresentaram uma média de diâmetro de 1,10 ± 0,10 mm e depois da fertilização e hidratação dos ovos, a média de diâmetro dos ovos aumentou para 1,90 ± 0,60 mm, caracterizado pelo grande espaço vitelínico que persistiu até o desenvolvimento do embrião, duplo córion e os polos (animal e vegetal). A divisão celular iniciou-se aproximadamente dois minutos após a fertilização (AF), resultando em 2, 4, 8 (4 x 2 arranjo das células), 16 (4 x 4), 32 (4 x 8) e 64 (2 x 4 x 8) células. Adicionalmente, seguiram as fases de blástula e gástrula depois das divisões celulares. O fechamento do blastóporo ocorreu às 11 h 20 min AF; seguindo o desenvolvimento, os estágios de organogênese foram identificados e subdivididos, respectivamente em: fase de divisão inicial e fase de divisão avançada. Na fase de divisão inicial, depois do estabelecimento do eixo do embrião, foi possível distinguir as regiões cefálica e caudal; os somitos e as vesículas ópticas se desenvolveram com aproximadamente 20 h AF. A eclosão total ocorreu com cerca de 54 h AF e o comprimento médio foi de 4,30 ± 0,70 mm. A redução gradual do saco vitelínico foi observada durante os primeiros dois dias de desenvolvimento larval. A primeira alimentação ocorreu no final do segundo dia. Durante a fase larval, canibalismo, crescimento larval heterogêneo e fotofobia também foram observados. Estas informações serão importantes para aperfeiçoar o protocolo de reprodução artificial em S. parahybae em programas de reprodução controlada

The effects of stocking density in physiological parameters and growth of the endangered teleost species piabanha, Brycon insignis (Steindachner, 1877)

This study investigated the effects of stocking density on the growth and fatty acid (FA) of Brycon insignis metabolism. Fingerlings (360) were distributed into eight ponds at two stocking densities (105 and 210 g/m(3)). The analysis of growth showed that the condition factor (K) and the coefficient of variation (CV) for body mass were not affected by stocking density. However, final body mass and length, specific growth rate (SGR), and weight gain (WG) were higher in the low stocking density group, which also presented a higher feed efficiency (FE) and survival (S). By contrast, muscle protein levels were higher in the high stocking density group. The plasma and muscle lipid content were not affected by stocking density, but fish reared at lower stocking density presented higher lipid concentration in the liver, with no differences in hepatosomatic index values. Even with the differences observed in metabolic and growth parameters, plasma cortisol was not affected by stocking density. The FA profile in the muscle and liver neutral fraction were not affected by stocking density, but the FA in the polar fractions differed between the two stocking densities. In the liver, total polyunsaturated fatty acids (PUFA) and PUFA n - 3 increased in higher stocking density, mainly due to an increase in docosahexaenoic acid (DHA). In addition, PUFA n - 6 were also increased in the higher stocking density group, mainly due to an increase in arachidonic acid (AA) and docosadienoic acid (22:2n - 6). In the muscle polar fraction, the saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) decreased in the animals from the higher stocking density group, and this reduction was compensated by an increase in PUFA n - 3 and PUFA n - 6, mainly the FA with 20-22 carbons (20:4n - 6: 22:4:n - 6; 22:5n - 6, 22:5n - 3, and 22:6n - 3). A different profile was observed for the C18 PUFAs, mainly 18:2n - 6 and 18:4n - 6, which were higher in the lower density stocking group. The data suggest that when living in high stocking density, B. insignis differentially utilizes the hepatic lipids as energy source and remodels the membrane fatty acids, with higher amounts of DHA in the polar muscle fraction compensated for by a decrease in MUFA. The zootechnical and physiological indices reveal that the lower stocking density group achieve overall better performance. (C) 2010 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP[2005/51302-0