The effect of adhesive systems on the pullout strength of a fiberglass-reinforced composite post system in bovine teeth

Purpose: To evaluate the pullout strength of a glass fiber-reinforced composite post (glass FRC) cemented with three different adhesive systems and one resin cement. The null hypothesis was that pullout strengths yielded by the adhesive systems are similar. Materials and Methods: Thirty bovine teeth were selected. The size of the specimens was standardized at 16 mm by sectioning off the coronal portion and part of the root. The specimens were divided into three groups, according to the adhesive system, which were applied following the manufacturers' instructions: G1, ScotchBond Multi-Purpose Plus; G2, Single Bond; G3, Tyrian SPE/One-Step Plus. The glass FRCs (Reforpost) were etched with 37% H3PO4 for 1 min and silanized (Porcelain Primer). Thereafter, they were cemented with the dual resin cement En-Force. The specimens were stored for 24 h, attached to an adapted device, and submitted to the pullout test in a universal testing machine (1 mm/min). The data were submitted to the one-way ANOVA and Tukey's test (α = 0.05). Results: G1 (30.2 ± 5.8 Kgf) displayed the highest pullout strength (p < 0.001) when compared to G2 (18.6 ± 5.8 Kgf) and G3 (14.3 ± 5.8 Kgf), which were statistically similar. Analysis of the specimens revealed that all failures occurred between the adhesive system and the root dentin (pullout of the post cement), regardless of group. Conclusion: The multiple-bottle, total-etch adhesive system provided higher pullout strength of the glass FRC when compared to the single-bottle, total-etch, and single-step self-etching adhesive systems. The null hypothesis was rejected (p < 0.001).

Fiberglass-reinforced glulam beams: Mechanical properties and theoretical model

The glued-laminated lumber (glulam) technique is an efficient process for making rational use of wood. Fiber-Reinforced Polymers (FRPs) associated with glulam beams provide significant gains in terms of strength and stiffness, and also alter the mode of rupture of these structural elements. In this context, this paper presents a theoretical model for designing reinforced glulam beams. The model allows for the calculation of the bending moment, the hypothetical distribution of linear strains along the height of the beam, and considers the wood has a linear elastic fragile behavior in tension parallel to the fibers and bilinear in compression parallel to the fibers, initially elastic and subsequently inelastic, with a negative decline in the stress-strain diagram. The stiffness was calculated by the transformed section method. Twelve non-reinforced and fiberglass reinforced glulam beams were evaluated experimentally to validate the proposed theoretical model. The results obtained indicate good congruence between the experimental and theoretical values.

Sistema de recirculação e rotina de manejo para larvicultura de camarões de água doce Macrobrachium rosenbergii em pequena escala

A recirculating system and a matching management schedule for small-scale freshwater prawn larviculture were described. The system comprised a 140 L larval culture tank in line with a 43 L biofilter filled with 24 L of calcareous substrate. Both the tank and biofilter were made of black colored fiberglass in a conical-cylindrical shape. The turnover rate of the water through the system was 24 times a day; water was pumped by airlift. Results of ten larvicultures showed that the system maintained temperature, dissolved oxygen, pH, salinity, ammonium and nitrite stable and suitable to Macrobrachium rosenbergii larvae. Survival and productivity varied from 60.5 to 72.4% and 37 to 72 post-larvae/L, respectively; both were compatible with results of commercial hatcheries. Therefore, this system may be very useful for research purposes or adapted for small-scale post-larvae production.

Efeito da utilização da levedura desidratada de álcool em dietas para tilápia-do-nilo

Este trabalho teve como objetivo avaliar o efeito da levedura desidratada de álcool (Saccharomyces cerevisae) como substituto do suplemento vitamínico, em dietas de tilápia-do-nilo (Oreochromis niloticus). Trezentos alevinos machos, sexualmente revertidos, com peso médio de 1,5 g, foram distribuídos igualmente em 20 aquários de fibra de vidro, equipados com filtro biológico. Cinco dietas isoprotéicas com 32% de proteína bruta na primeira fase (40 dias) e com 28% de proteína bruta na segunda fase (74 dias) foram fornecidas ad libitum, duas vezes ao dia. A dieta-controle não conti-nha levedura, e as demais apresentavam 10% de levedura. O delineamento foi inteiramente casualizado, com cinco tratamentos e quatro repetições. Não houve influência significativa dos tratamentos sobre o ganho de peso e taxa de crescimento específico. Foi observada, nos peixes alimentados com dietas sem suplemento vitamínico, alta mortalidade. Os peixes que receberam levedura apresentaram menor conteúdo corporal de proteína, e maior, de lipídeos. A levedura desidratada de álcool pode ser usada como fonte de vitaminas hidrossolúveis em dietas para alevinos de tilápia-do-nilo.

Gesso sintético e pinos transcorticais na redução de fratura de tíbia em uma bezerra

Relata-se um caso de fratura de tíbia em uma bezerra de sete meses de idade, 200kg de peso, apresentando fratura fechada, cominutiva em diáfise. A fixação externa foi preferida como método de imobilização óssea, utilizando-se pinos transcorticais e gesso sintético. Obteve-se eficiente imobilização da fratura, com rápida recuperação do animal, dispendendo-se pouco tempo para o pós-operatório (52 dias). A técnica demonstrou ser de fácil realização e passível de ser executada a campo.

Inflammatory responses of Nile tilapia Oreochromis niloticus to Streptococcus agalactiae: effects of vaccination and yeast diet supplement

This study evaluated the effects of dietary supplementation with 0.3% Saccharomyces cerevisiae yeast cell wall and of vaccination against Streptococcus agalactiae on the cellular component of acute inflammation induced in the coelomic cavity of Nile tilapia Oreochromis niloticus and on survival of the fish after challenge. A total of 84 tilapia of mean (+/- SD) weight 125.0 +/- 1.5 g were distributed among twelve 310 l fiberglass tanks according to a 2 x 2 x 3 factorial design in the following manner: with and without supplementation; 2 stimulations (oily solution without S. agalactiae vaccine and vaccination); 15 d later all fish were intracoelomically challenged with 10(8) CFU ml(-1) of a homologous strain of S. agalactiae, and evaluated after 6, 24 and 48 h, with 7 replicates. The fish received the non-supplemented or supplemented diet for a total of 77 d. The vaccination was performed on the 60th day, intracoelomically, as a single injection of 0.5 ml of the vaccine containing 10(8) CFU ml(-1). Fifteen days later, all the fish were challenged with S. agalactiae by means of an intracoelomic inoculation of 10(8) CFU ml(-1). No mortality was observed among the supplemented fish. The fish that were fed the non-supplemented diet and immunized with the bacterium presented a mortality rate of 28.5%. Among the non-supplemented and non-immunized fish, the mortality rate was 38.09%. Supplementation, in both vaccinated and non-vaccinated fish, induced larger accumulations of thrombocytes, lymphocytes and macrophages at the inflammatory focus. The results suggest that supplementation with 0.3% yeast cell wall, in both vaccinated and non-vaccinated fish, improved the inflammatory response of the fish and protected against the challenge. Vaccination increased the defense response, but the effect was stronger when associated with supplementation with S. cerevisiae.

Parafusos bioabsorvíveis na reparação de fraturas experimentais de sesamóides proximais em eqüinos

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

Digestibilidade de alimentos protéicos e energéticos para fêmeas de beta

Foram avaliados os coeficientes de digestibilidade aparente de MS, PB, energia bruta (EB) e EE de alimentos protéicos (farelo de soja e farinha de peixe) e energéticos (fubá de milho e farelo de trigo) para beta (Betta splendens). Fêmeas adultas foram alojadas em gaiolas e mantidas em dois aquários de fibra de vidro (30 peixes/aquário) para alimentação e dois para coleta de fezes, ambos de formato cônico e com capacidade para 30 L. Os resultados dos coeficientes de digestibilidade aparente de MS, PB, EB e EE foram, respectivamente, de 69,43; 72,52; 67,91 e 55,50% para farelo de soja; 60,67; 51,15; 75,55 e 58,26% para farinha de peixe; 63,88; 87,16; 77,61 e 50,40% para fubá de milho; e 61,06; 93,37; 58,17 e 65,51% para farelo de trigo. Os resultados obtidos neste estudo permitem otimizar a formulação de dietas práticas balanceadas, economicamente viáveis para a espécie.

Customized fiber glass posts. Fatigue and fracture resistance

Purpose: To evaluate the root fracture strength of human single-rooted premolars restored with customized fiberglass post-core systems after fatigue simulation. Methods: 40 human premolars had their crowns cut and the root length was standardized to 13 mm. The teeth were endodontically treated and embedded in acrylic resin. The specimens were distributed into four groups (n=10) according to the restorative material used: prefabricated fiber post (PFP), PFP+accessory fiber posts (PFPa), PFP+unidirectional fiberglass (PFPf), and unidirectional fiberglass customized post (CP). All posts were luted using resin cement and the cores were built up with a resin composite. The samples were stored for 24 hours at 37 degrees C and 100% relative humidity and then submitted to mechanical cycling. The specimens were then compressive-loaded in a universal testing machine at a crosshead speed of 0.5 mm/minute until fracture. The failure patterns were analyzed and classified. Data was submitted to one-way ANOVA and Tukey's test (alpha= 0.05). Results: The mean values of maximum load (N) were: PFP - 811.4 +/- 124.3; PFPa - 729.2 +/- 157.2; PFPf - 747.5 +/- 204.7; CP - 762.4 +/- 110. Statistical differences were not observed among the groups. All groups showed favorable restorable failures. Fiberglass customized post did not show improved fracture resistance or differences in failure patterns when compared to prefabricated glass fiber posts. (Am J Dent 2012;25:35-38).

Fibras reforçadas por resina (FRC) em Ortodontia. Versatilidade clínica: parte 2

As fibras de vidro e de polietileno podem ser utilizadas na prática ortodôntica em diversas situações clínicas, nos casos com ou sem extrações dentárias. Este artigo tem como objetivo mostrar algumas das aplicações clínicas nas quais as fibras contribuíram de forma significativa para a realização dos tratamentos ortodônticos, simplificando-os e aumentando a eficiência clínica. As fibras foram utilizadas principalmente em segmentos de ancoragem e na substituição da banda pela colagem da associação fibra/tubo nos molares.

Exigência Protéica e Relação Energia/Proteína para Alevinos de Piracanjuba (Brycon orbignyanus)

O objetivo do presente estudo foi determinar a exigência protéica e correspondente relação energia/proteína em dietas para alevinos de piracanjuba, Brycon orbignyanus. Seis dietas semi-purificadas isocalóricas foram formuladas para conter 3.000 kcal de energia metabolizável (EM)/kg e concentrações de proteína bruta (PB) de 24, 26, 29, 32, 36 e 42%. Para essas concentrações, as relações E/P das dietas foram de 12,3; 11,6; 10,4; 9,2; 8,5 e 7,1 kcal EM/g PB, respectivamente. As fontes de proteína, lipídios e carboidratos digestíveis foram, respectivamente, caseína/gelatina, óleo de fígado de bacalhau/óleo de soja e dextrina. Após condicionamento de cinco dias, as dietas foram fornecidas, até a saciedade, em duas alimentações diárias, a 162 alevinos (27 peixes/dieta), que apresentaram 8,38 ± 0,09 g de peso médio inicial, distribuídos em 18 tanques de fibra-de-vidro de 100 L, conectados a um sistema de recirculação de água. A temperatura média da água foi de 26,3°C, com extremos de 23,7 e 30,2°C. Após 90 dias, a concentração de proteína na dieta que proporcionou ganho em peso máximo aos peixes foi 29% PB, com relação E/P igual a 10,4 kcal EM/g PB. As dietas com concentrações de PB iguais a 32, 36 e 42% não se mostraram superiores para conversão alimentar, taxa de eficiência protéica, valor produtivo da proteína e retenção de energia bruta. A deposição corporal de proteína e gordura não sofreu influência da concentração de PB da dieta

Fósforo na alimentação de pacu (Piaractus mesopotamicus)

Objetivou-se avaliar o uso de fósforo na dieta de juvenis de pacu (Piaractus mesopotamicus) sobre a qualidade da água, o desempenho zootécnico, o rendimento corporal e a composição química da carcaça. Foram utilizados 100 juvenis com peso médio inicial de 25,9±1,32 g, distribuídos em delineamento inteiramente ao acaso, em 20 tanques de fibra de vidro, com cinco tratamentos e quatro repetições. Os peixes foram alimentados quatro vezes ao dia, às 8; 11; 14 e 17 h, com dietas extrusadas contendo 0,40; 0,55; 0,70; 0,85 e 1,0% de fósforo total. Não foram observadas diferenças nos parâmetros de qualidade de água, com exceção da concentração de ortofosfato na água, que apresentou aumento linear. Os parâmetros de desempenho zootécnico, rendimento corporal e composição química da carcaça não diferiram entre os níveis de suplementação de fósforo na dieta. A utilização de 0,40% de fósforo total atende às exigências de fósforo de juvenis de pacu (Piaractus mesopotamicus), além de disponibilizar menor concentração de ortofosfato da água.

Relação Cálcio/Fósforo Disponível em Rações para Tilápia do Nilo (Oreochromis niloticus)

The objective of this work was to evaluate the effect of Ca: available P (P-a) ratio in the diets on performance and bone mineral depositions of juvenile Nile tilapia (2.5 +/- 0.5g). Seven isoproteic and isoenergetic diets (28% CP and 3100 Kcal of DE/Kg of diet), with similar crude fiber and sulfur aminoacids content, were used. The diets had 0.50 and 0.25; 0.50 and 0.50; 0.50 and 0.75; 0.80 and 0.40; 0.80 and 0.80; and 0.80 and 1.20% of Ca and P-a which corresponded to Ca/P-a ratios of 2:1;1:1 and 1:1.5, respectively. An additional control diet, with low levels of Ca and Pa (0.02 and 0.12%, respectively) was used. A completely randomized design with a 2'3 factorial arrangement (Ca level and Ca:P-a ratio) on treatments, plus the additional control diet and three replications was used. Five fishes per aquaria were randomly allotted to 21 fiberglass aquaria (80L). The temperature of the water was maintained close to 26degreesC, and the oxygen, pH and ammonia levels of the water were monitored. The results showed that it was necessary a minimum dietary level of 0.25% of P-a for a satisfactory bone mineral depositions, and that the best performance results were achieved using diets with Ca: P-a ratios between 1:1 and 1:1.5.

Unsaturated polyester based composites reinforced with curauá fiber - Preliminary studies

Curauá fiber processing characterization has been performed throughout the different processing steps. Unsaturated polyester has been used as matrix in the production of curauá reinforced composite samples. Compression molding process has been used to prepare the samples. Tensile strength, impact resistance, flexural strength, Young's modulus and elongation at break have been accessed for curauá composites in comparison with fiberglass composites. Mechanical properties were found not to attend the company's internal standards specification. However, the work has shown some alternatives to solve these problems such as the modification of equipment characteristics and resin formulation, the necessity of incorporation of a higher content of fiber and the possibility of using a new type of filler. Copyright © 2000 Society of Automotive Engineers, Inc.

Natural fiber reinforced unsaturated polyester composites - An approach on compression molding

This work has been performed at Tapetes Sao Carlos-Brazil with the cooperation of the DaimlerChrysler Research Center Team in Ulm - Germany. The objective of the present paper is to report the results obtained with natural fiber reinforced unsaturated polyester (UP) composites, concerning surface quality measurements. The fibers that have been chosen for this work were sisal and curaua. The samples were produced by compression molding technique and afterwards submitted to three different tests, namely: a) thermal aging; b) water absorption and c) artificial weathering. The surface parameters measured before and after the tests were gloss, haze, short and long-waviness. The results have shown that after the tests there is a high loss of gloss, a high increase in haze, and a high increase in short and long-waviness as well. Curaua reinforced composites had a slightly better behavior when compared with sisal reinforced composites. The effect of the presence of filler and the addition of thermoplastic polyester (TP) on the material behavior has not been evidently detected. This result shows that the conventional technology/methods applied to UP-Fiberglass systems cannot be transferred to natural fibers without any modification. The fiber-matrix interaction and its response to the presence of additives must be fully understood before a successful processing route can be developed for painted natural fibers reinforced UP. Copyright © 2001 Society of Automotive Engineers, Inc.