Influência da Qualidade das Lâminas no Desempenho Mecânico à Flexão de Painéis Compensados de Hevea brasiliensis

After concluding the main phase of commercial exploration of latex (about 30 years ago), rubber wood plantations can be utilized as an alternative source of wood for sawmills and other wood based products with more aggregate value; tendency already confirmed in countries of southeastern Asia. The main purpose of this research was to evaluate the influence of dynamic modulus of elasticity veneers on the mechanical performance in the bending of plywood made from Hevea brasiliensis. For this study, rubber tree veneers were sorted in three classes of dynamic modulus of elasticity: low (from 4887-7323 MPa), medium (from 8200-8948 MPa) and high (from 10979-13010 MPa). Panels were produced according to five treatments with different veneer classes and arrangements. Results showed significant effect of the treatments in the mechanical performance in the bending of panels. Panels with better mechanical performance were produced exclusively with medium and high dynamic modulus of elasticity. Panels made with low modulus of elasticity veneers presented lower mechanical performance even when combined with high modulus of elasticity veneers.

Comparação dos parâmetros de biossorção dos elementos terras-raras lantânio e neodímio utilizando biomassas de fungos filamentosos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A gestão da comunicação e da informação nas empresas contemporâneas sob a ótica da responsabilidade social

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Viabilidade econômica e financeira da utilização do excedente de energia elétrica co-gerada em uma usina de açúcar e álcool da Alta paulista

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Proposta de uma abordagem de análise para a implantação de plataformas logísticas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modelo de previsão de priorização de peça de reposição

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento de estratégias de alimentação para produção de ramnolipídios por Pseudomonas aeruginosa LBI 2A1 em biorreator

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

Métodos de extração da lignina do bagaço da cana-de-açúcar do Noroeste do Estado de São Paulo

Pós-graduação em Química - IBILCE

Revegetation on a Removed Topsoil: Effect on Aggregate Stability

The construction of a large reservoir on the Parana River (Selviria, MS, Brazil) disturbed the soil of an extensive agricultural area in which between 5 and 8m of topsoil were removed. In this area, a restoration process was carried out using revegetation with green manure without or with amendments (for 4 years), crops (2 years), and Brachiaria decumbens cultivation for 6 years. The following treatments were used: control plots, T0 (residual subsoil) and T1 (soil tillage without culture); plots with green manure and without amendments: T2 (velvet bean) and T3 (pigeon pea); plots with green manure and with amendments: T4 (limed + velvet bean), T5 (limed + pigeon pea); T6 (limed + gypsum + velvet bean) and T7 (limed + gypsum + pigeon-pea). They were arranged in randomized blocks. After 13 years of rehabilitation process, when the soil was cultivated with brachiaria, the structural stability in three depths was evaluated. Organic-matter content and others chemical properties did not show any relationship with the stability of aggregates of the experimental area as measured by mean weight diameter (MWD). Significant differences between depths were found for MWD and the other parameters measured. Nevertheless, there were no significant differences observed between treatments, independent of the adopted system of revegetation. By taking an absolute value of MWD, the stability of superficial layer was observed in the following sequence: T7 T5 T6 T1 T2 T3 T4 T0. The control plot (T0) gave the lowest value of MWD (1.76mm) in relation to the plots in restoration process. Treatment T7 was the most effective in recovering the stability of aggregates (2.63mm). However, treatments T5 and T6 displayed a similar value. After 13 years of revegetation practices, a slight recovery of the stability was observed, although this is still lower than stability in soils of similar edaphic conditions in the original topsoil of experimental area.

Evaluation of the propylene glycol association on some physical and chemical properties of mineral trioxide aggregate

Duarte MAH, Alves de Aguiar K, Zeferino MA, Vivan RR, Ordinola-Zapata R, Tanomaru-Filho M, Weckwerth PH, Kuga MC. Evaluation of the propylene glycol association on some physical and chemical properties of mineral trioxide aggregate. International Endodontic Journal, 45, 565570, 2012. Abstract Aim To evaluate the influence of propylene glycol (PG) on the flowability, setting time, pH and calcium ion release of mineral trioxide aggregate (MTA). Methodology Mineral trioxide aggregate was mixed with different proportions of PG, as follows: group 1: MTA + 100% distilled water (DW); group 2: MTA + 80% DW and 20% PG; group 3: MTA + 50% DW and 50% PG; group 4: MTA + 20% DW and 80% PG; group 5: MTA + 100% PG. The ANSI/ADA No. 57 was followed for evaluating the flowability and the setting time was measured by using ASTM C266-08. For pH and calcium release analyses, 50 acrylic teeth with root-end cavities were filled with the materials (n = 10) and individually immersed in flasks containing 10 mL deionized water. After 3 h, 24 h, 72 h and 168 h, teeth were placed in new flasks and the water in which each specimen was immersed had its pH determined by a pH metre and the calcium release measured by an atomic absorption spectrophotometer with a calcium-specific hollow cathode lamp. Data were analysed by using one-way anova test for global comparison and by using Tukeys test for individual comparisons. Results The highest value of flowability was observed with MTA + 20% DW and 80% PG and the lowest values were found with MTA + 100% DW. They were significantly different compared to the other groups (P < 0.05). The presence of PG did not affect the pH and calcium release. The MTA + 100% PG favoured the highest (P < 0.05) pH and calcium release after 3 h. Increasing the PG proportion interfered (P < 0.05) with the setting time; when used at the volume of 100% setting did not occur. Conclusion The addition of PG to MTA-Angelus increased its setting time, improved flowability and increased the pH and calcium ion release during the initial post-mixing periods. The ratio of 80% DW 20% PG is recommended.

Evaluation of pH and Calcium Ion Release of Root-end Filling Materials Containing Calcium Hydroxide or Mineral Trioxide Aggregate

Introduction: To evaluate calcium ion release and pH of Sealer 26 (S26) (Dentsply, Rio de Janeiro, RJ, Brazil), white mineral trioxide aggregate (MTA), Endo CPM Sealer (CPM1) (EGEO SRL Bajo licencia MTM Argentina SA, Buenos Aires, Argentina), Endo CPM Sealer in a thicker consistency (CPM 2), and zinc oxide and eugenol cement (ZOE). Methods: Material samples (n = 10) were placed in polyethylene tubes and immersed in 10 mL of distilled water. After 3, 6,12,24, and 48 hours and 7,14, and 28 days, the water pH was determined with a pH meter, and calcium release was assessed by atomic absorption spectrophotometry. An empty tube was used as the control group. Results: The control group presented a pH value of 6.9 at all studied periods and did not show the presence of calcium ion. S26 presented greater hydroxyl ion release up to 12 hours (p < 0.05). From 24 hours until 28 days, S26, MTA, CPM1, and CPM2 had similar results. in ail periods, ZOE presented the lowest hydroxyl ion release. CPM1, followed by CPM2, released the most calcium ions until 24 hours (p < 0.05). Between 48 hours and 7 days, CPM1 and CPM2 had the highest release. A greater calcium ion release was observed for CPM2, followed by CPM1 at 14 days and for S26, CPM1, and CPM2 at 28 days. ZOE released the least calcium ions in all periods. Conclusion: Sealer 26, MTA, and Endo CPM sealer at normal or thicker consistency release hydroxyl and calcium ions. Endo CPM sealer may be an alternative as root-end filling material. (J Endod 2009;35:1418-1421)