Comportamento dinâmico não-linear de um sistema mecânico com vibrações associadas a uma transição brusca na rigidez

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Structure and thermal behavior of PMMA-polysilsesquioxane organic-inorganic hybrids

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ti-Mo alloys employed as biomaterials: Effects of composition and aging heat treatment on microstructure and mechanical behavior

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

TENSILE AND CREEP BEHAVIOR OF GEOSYNTHETICS USING CONFINED-ACCELERATED TESTS

A major aspect in geosynthetics creep analysis is the load level applied to the specimen, usually referred as a percentage of the geosynthetic ultimate tensile strength (UTS). Since both tensile and creep standard tests are performed with in-isolation specimens, they may not reproduce the possibly significant effect of soil-geosynthetic interaction. A new creep testing machine was recently developed and successfully addressed this concern. However, further developments allowed tensile tests to be performed in the same conditions used in nonconventional creep ones. This paper presents the results of nonconventional tensile tests performed with a woven biaxial polyester geogrid. They were used to define its UTS in the same conditions employed in creep tests performed with the new equipment. Despite changes in tensile curves shapes were found, the UTS from confined, accelerated and confined-accelerated tensile tests were quite similar to those obtained with standard tensile test procedure.

Rheological, mechanical, and bioadhesive behavior of hydrogels to optimize skin delivery systems

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

P-I class metalloproteinase from Bothrops moojeni venom is a post-proline cleaving peptidase with kininogenase activity: Insights into substrate selectivity and kinetic behavior

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Synthesis, characterization, and thermal behavior of palladium(II) complexes containing 4-iodopyrazole

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Synthesis and thermal behavior study of complexes of the type [Pd(mu-X)(4-eb-p-phen)](2) (X = Cl, Br, I, N-3, NCO, SCN) and 4-eb-p-phen [bis(4-ethylbenzyl)p-phenylenediimine]

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A virtual experiment for the detection of specific features in the frequency response of a coupled nonlinear and linear oscillator

This paper presents an investigation into some practical issues that may be present in a real experiment, when trying to validate the theoretical frequency response curve of a two degree-of-freedom nonlinear system consisting of coupled linear and nonlinear oscillators. Some specific features, such as detached resonance curves, have been theoretically predicted in multi degree-of-freedom nonlinear oscillators, when subject to harmonic excitation, and the system parameters have been shown to be fundamental in achieving such features. When based on a simplified model, approximate analytical expression for the frequency response curves may be derived, which may be validated by the numerical solutions. In a real experiment, however, the practical achievability of such features was previously shown to be greatly affected by small disturbances induced by gravity and inertia, which led to some solutions becoming unstable which had been predicted to be stable. In this work a practical system configuration is proposed where such effects are reduced so that the previous limitations are overcome. A virtual experiment is carried out where a detailed multi-body model of the oscillator is assembled and the effects on the system response are investigated.

Anuran skin and basking behavior: the case of the treefrog Bokermannohyla alvarengai (Bokermann, 1956)

We investigated the morphology of the skin and the biochemistry of the lipids in the skin secretion of Bokermannohyla alvarengai, a montane treefrog that is known to bask regularly, motionless in full sunlight for extended periods of time. Our primary goal was to identify structural and biochemical modifications that might assist this frog species to accommodate the conflicting demands for heat exchange and water balance while basking. The modulation of heat exchange in basking B. alvarengai involves changes in skin coloration. We found that this response was supported by a prominent monolayer of large iridophores, whose light reflectance property is adjusted by the response of intervening melanophores. Mucosubstances and lipid compounds, mainly consisted of saturated fatty acids and presumably secreted from granular glands, were detected on the skin of B. alvarengai. These compounds formed an extra-epidermal layer over the animal's dorsal surface that might assist in the prevention of excessive water loss through evaporation. Additionally, we found well-developed skin folds at the ventral region of the frogs that lead to an increment of surface area. This feature combined with the extensive hypervascularization, also noticed for the skin of B. alvarengai, may play an important role in water reabsorption. The suite of structural and biochemical modifications identified for the integument of B. alvarengai seems to conjugate aspects relevant to both, heat exchange and water balance, allowing for this species to explore basking as an efficient thermoregulatory strategy. J. Morphol. 276:1172-1182, 2015. © 2015 Wiley Periodicals, Inc.

High blood pressure and sedentary behavior in adolescents are associated even after controlling for confounding factors

The aim of this study was to determine whether high blood pressure (HBP) is associated with sedentary behavior in young people even after controlling for potential confounders (gender, age, socioeconomic level, tobacco, alcohol, obesity and physical activity). In this epidemiological study, 1231 adolescents were evaluated. Blood pressure was measured with an oscillometric device and waist circumference with an inextensible tape. Sedentary behavior (watching television, computer use and playing video games) and physical activity were assessed by a questionnaire. We used mean and standard deviation to describe the statistical analysis, and the association between HBP and sedentary behavior was assessed by the chi-squared test. Binary logistic regression was used to observe the magnitude of association and cluster analyses (sedentary behavior and abdominal obesity; sedentary behavior and physical inactivity). HBP was associated with sedentary behaviors [odds ratio (OR) = 2.21, 95% confidence interval (CI) = 1.41-3.96], even after controlling for various confounders (OR = 1.68, CI = 1.03-2.75). In cluster analysis the combination of sedentary behavior and elevated abdominal obesity contributed significantly to an increased likelihood of having HBP (OR = 13.51, CI 7.21-23.97). Sedentary behavior was associated with HBP, and excess fat in the abdominal region contributed to the modulation of this association.

On-plant larval movement and feeding behavior of fall armyworm (Lepidoptera: Noctuidae) on reproductive corn stages

Spodoptera frugiperda J.E. Smith (fall armyworm) is considered one of the most destructive pests of corn throughout the Americas. Although this pest has been extensively studied, little is known about its larval movement and feeding behavior on reproductive compared to vegetative corn stages. Thus, we conducted studies with two corn stages (R1 and R3) and four corn plant zones (tassel, above ear, ear zone, and below ear) in the field at Concord, NE (USA), and in the field and greenhouse at Botucatu, SP (Brazil), to investigate on-plant larval movement. The effects of different corn tissues (opened tassel, closed tassel, silk, kernel, and leaf), two feeding sequence scenarios (closed tassel-leaf-silk-kernel and leaf-silk-kernel), and artificial diet (positive control) on larval survival and development were also evaluated in the laboratory. Ear zone has a strong effect on feeding choice and survival of fall armyworm larvae regardless of reproductive corn stage. Feeding site choice is made by first-instar. Corn leaves of reproductive plants were not suitable for early instar development, but silk and kernel tissues had a positive effect on survival and development of fall armyworm larvae on reproductive stage corn.

Synthesis, characterization and thermal behavior of heterobimetallic carbonyl compounds of the type [W(CO)(4)(bipy)(CuX)] (X=Cl, N-3, ClO4 and BF4)

Four new heterobimetallic metal carbonyls were synthesized by the reaction of [W(CO)4(bipy)] (1) with copper(I) compounds leading to species with the general formula [W(CO)4(bipy)(CuX)] (X = Cl, N3, ClO4, BF4) (2-5). The metal carbonyl compounds were characterized by elemental analysis, infrared and UV -visible electronic spectroscopy and thermogravimetric analysis. The IR data for 2-5 show carbonyl stretching band patterns similar to compound 1 ; ie they exhibit the same number of bands. The UV - vis results show a dissociation reaction generating the starting compound 1 and CuX as consequence of a weak interaction between 1 and CuX. Thermal decomposition mechanisms as well as the thermal stability are influenced by the CuX fragments. The thermal stability decreases in the order [W(CO)4(bipy)] > [W(CO)4(bipy)(CuCl)] > [W(CO)4(bipy) (CuBF4)]. The X-ray results show the formation of WO3, CuWO4, Cu2O and CuO as final decomposition products.

Synthesis, characterization and thermal behavior of cyclopalladated compounds of the type [Pd{C6H4CH2N(CH3)(2)}(mu-X)](2) (X= Cl, NCO, SCN, CN)

The dimeric compound [Pd(dmba)(μ-Cl)]2 (1) (dmba = N,N-dimethylbenzylamine) reacts with KX, in methanol/acetone, affording the analogous dimeric pseudohalide-bridged species [Pd(dmba)(X)]2 [X = NCO(2), SCN(3), CN(4)]. The compounds were characterized by elemental analysis, infrared spectroscopy, NMR and thermogravimetric analysis. The IR data for 2-4 showed bands typical of coordinated pseudohalide ligands indicating clearly the occurrence of the exchange reaction. Their thermal behavior was investigated and suggested that their thermal stability is influenced by the bridging ligand. The thermal stability decreased in the order [Pd(dmba)(μ-SCN)]2>[Pd(dmba)(μ-Cl)] 2>[Pd(dmba)(;u-NCO)]2>[Pd(dmba)(μ-CN)]2. The X-ray results showed the formation of PdO as final decomposition product. © 1999 Elsevier Science Ltd. All rights reserved.