RESUMO

In this work, the frequency dependence of the known mechano-optical effect which occurs in the micellar isotropic phases (I) of mixtures of potassium laurate (KL), decanol (DeOH), and water is investigated in the range from 200mHz to 200Hz. In order to fit the experimental data, a model of superimposed damped harmonic oscillators is proposed. In this phenomenological approach, the micelles (microscopic oscillators) interact very weakly with their neighbors. Due to shape anisotropy of the basic structures, each oscillator i (i=1,2,3,...,N) remains in its natural oscillatory rotational movement around its axes of symmetry with a frequency ω_{0i}. The system will be in the resonance state when the frequency of the driving force ω reaches a value near ω_{0i}. This phenomenological approach shows excellent agreement with the experimental data. One can find f∼2.5, 9.0, and 4.0Hz as fundamental frequencies of the micellar isotropic phases I, I_{1}, and I_{2}, respectively. The different micellar isotropic phases I, I_{1}, and I_{2} that we find in the phase diagram of the KL-DeOH-water mixture are a consequence of possible differences in the intermicellar correlation lengths. This work reinforces the possibilities of technological applications of these phases in devices such as mechanical vibration sensors.

RESUMO

Objetivou-se com esta pesquisa avaliar três sistemas forrageiros constituídos por Coastcross-1 (CC) + 100kg de N/ha/ano + ervilhaca comum; CC + 100kg de N/ha/ano + trevo vesiculoso; e CC + 200kg de N/ha/ano. Durante o período experimental (345 dias), foram realizados treze pastejos. O delineamento experimental utilizado foi o inteiramente ao acaso, com três tratamentos (sistemas forrageiros), três repetições (piquetes) em parcelas subdividas no tempo (valores médios dos pastejos em cada estação do ano). Para avaliação, foram utilizadas vacas em lactação da raça Holandesa. Amostras de simulação de pastejo foram coletadas para análise de proteína bruta (PB), fibra em detergente neutro (FDN) e ácido (FDA), digestibilidade in situ da matéria seca (DISMS) e da matéria orgânica (DISMO) e os nutrientes digestíveis totais (NDT). Os valores médios para PB, FDN, FDA, DISMS, DISMO e NDT foram de 18,1; 16,7 e 17,6%; 57,8; 58,9 e 58,7%; 26,5; 26,5 e 26,7%; 79,6; 78,9 e 80,6%; 79,8; 79,1 e 80,6%; 72,1; 71,4 e 72,7%, respectivamente. Melhores resultados de valor nutritivo foram obtidos no inverno, em especial para o consórcio de Coastcross-1 com ervilhaca.

The aim of this research was to evaluate three grazing systems with Coastcross-1 (CC) + 100kg N/ha/year + common vetch; CC + 100kg N/ha/year + arrowleaf clover; and CC + 200kg N/ha/year. Thirteen grazing cycles were performed during the experimental period (345 days). The experimental design was completely randomized with three treatments (grazing systems), three replicates (paddocks) in completely split-plot time (average values of grazing season). Lactating Holstein cows were used in the evaluation. Forage mass and botanical composition were evaluated. Samples from the hand-plucking method were collected to analyze crude protein (CP), neutral detergent fiber (NDF) and acid (ADF), in situ digestibility of dry matter (ISDMD) and organic matter (ISOMD) and total digestible nutrients (TDN). The averages of CP, NDF, ADF, ISDMD, ISOMD and TDN were 18.1, 16.7 and 17.6 %; 57.8, 58.9 and 58.7 %; 26.5, 26.5 and 26.7 %; 79.6, 78.9 and 80.6 %; 79.8, 79.1 and 80.6 %; 72.1, 71.4 and 72.7 %, respectively. Better results for nutritive value were found during winter, especially on Coastcross-1 mixed with common vetch.

Assuntos

RESUMO

Objetivou-se com esta pesquisa avaliar três sistemas forrageiros constituídos por Coastcross-1 (CC) + 100kg de N/ha/ano + ervilhaca comum; CC + 100kg de N/ha/ano + trevo vesiculoso; e CC + 200kg de N/ha/ano. Durante o período experimental (345 dias), foram realizados treze pastejos. O delineamento experimental utilizado foi o inteiramente ao acaso, com três tratamentos (sistemas forrageiros), três repetições (piquetes) em parcelas subdividas no tempo (valores médios dos pastejos em cada estação do ano). Para avaliação, foram utilizadas vacas em lactação da raça Holandesa. Amostras de simulação de pastejo foram coletadas para análise de proteína bruta (PB), fibra em detergente neutro (FDN) e ácido (FDA), digestibilidade in situ da matéria seca (DISMS) e da matéria orgânica (DISMO) e os nutrientes digestíveis totais (NDT). Os valores médios para PB, FDN, FDA, DISMS, DISMO e NDT foram de 18,1; 16,7 e 17,6%; 57,8; 58,9 e 58,7%; 26,5; 26,5 e 26,7%; 79,6; 78,9 e 80,6%; 79,8; 79,1 e 80,6%; 72,1; 71,4 e 72,7%, respectivamente. Melhores resultados de valor nutritivo foram obtidos no inverno, em especial para o consórcio de Coastcross-1 com ervilhaca.(AU)

The aim of this research was to evaluate three grazing systems with Coastcross-1 (CC) + 100kg N/ha/year + common vetch; CC + 100kg N/ha/year + arrowleaf clover; and CC + 200kg N/ha/year. Thirteen grazing cycles were performed during the experimental period (345 days). The experimental design was completely randomized with three treatments (grazing systems), three replicates (paddocks) in completely split-plot time (average values of grazing season). Lactating Holstein cows were used in the evaluation. Forage mass and botanical composition were evaluated. Samples from the hand-plucking method were collected to analyze crude protein (CP), neutral detergent fiber (NDF) and acid (ADF), in situ digestibility of dry matter (ISDMD) and organic matter (ISOMD) and total digestible nutrients (TDN). The averages of CP, NDF, ADF, ISDMD, ISOMD and TDN were 18.1, 16.7 and 17.6 %; 57.8, 58.9 and 58.7 %; 26.5, 26.5 and 26.7 %; 79.6, 78.9 and 80.6 %; 79.8, 79.1 and 80.6 %; 72.1, 71.4 and 72.7 %, respectively. Better results for nutritive value were found during winter, especially on Coastcross-1 mixed with common vetch.(AU)

Assuntos

RESUMO

Topological defects can appear whenever there is some type of ordering. Its ubiquity in nature has been the subject of several studies, from early Universe to condensed matter. In this work, we investigated the annihilation dynamics of defects and antidefects in a lyotropic nematic liquid crystal (ternary mixture of potassium laurate, decanol and deionized-destillated water) using the polarized optical light microscopy technique. We analyzed Schlieren textures with topological defects produced due to a symmetry breaking in the transition of the isotropic to nematic calamitic phase after a temperature quench. As result, we obtained for the distance D between two annihilating defects (defect-antidefect pair), as a function of time t remaining for the annihilation, the scaling law D âˆ t(α), with α = 0.390 and standard deviation σ = 0.085. Our findings go in the direction to extend experimental results related to dynamics of defects in liquid crystals since only thermotropic and polymerics ones had been investigated. In addition, our results are in good quantitative agreement with previous investigations on the subject.

Assuntos

RESUMO

We report on the dynamical behavior of defects of strength s=±1/2 in a lyotropic liquid crystal during the annihilation process. By following their positions using time-resolved polarizing microscopy technique, we present statistically significant evidence that the relative velocity between defect pairs is Gaussian distributed, antipersistent, and long-range correlated. We further show that simulations of the Lebwohl-Lasher model reproduce quite well our experimental findings.

Assuntos

RESUMO

We investigate the electrical response of Milli-Q deionized water by using a fractional diffusion equation of distributed order with the interfaces (i.e., the boundary conditions at the electrodes limiting the sample) governed by integrodifferential equations. We also consider that the positive and negative ions have the same mobility and that the electric potential profile across the sample satisfies Poisson's equation. In addition, the good agreement between the experimental data and this approach evidences the presence of anomalous diffusion due to the surface effects in this system.

RESUMO

The response of bovine bone to the presence of an implant is analysed with the aim of simulating bone remodelling in a developing model of a polymeric intramedullary interlocking nail for veterinary use. A 3-D finite element model of the femur diaphysis is built based on computed tomography images and using a CAD-based modelling pipeline. The bone remodelling process after the surgery is analysed and compared with the healthy bone. The remodelling law assumes that bone adapts to the mechanical environment. For the analyses a consistent set of loads is determined for the bovine walk cycle. The remodelling results reproduce the morphologic features of bone and provide evidence of the difference on the bone behaviour when comparing metallic and polymeric nails. Our findings indicate that an intramedullary polymeric nail has the advantage over the metallic one of improving long-term bone healing and possibly avoiding the need of the implant removal.

Assuntos

RESUMO

In this work, we analyze the defect and antidefect distribution in the nematic calamitic phase of a lyotropic liquid crystal [the ternary mixture formed by potassium laurate (KL), decanol (DeOH), and water]. We obtain defects with wedge disclinations of strength +/-1/2, and the scaling exponent determined by the defect-antidefect correlation was 0.29+/-0.07. This value is in good agreement with the theoretical value of 14 obtained by the Kibble mechanism. The constant of the scaling relation of the defect and antidefect distribution is also discussed. We compare our results with the values obtained by Digal [Phys. Rev. Lett. 83, 5030 (1999)] who used a thermotropic liquid crystal.

RESUMO

In this work, through the Z-scan technique, we report on measurements of the nonlinear refractive index (n{2}) in discotic and calamitic nematic phases at room temperature in lyotropic mixtures of potassium laurate, decanol and D(2)O . This technique presents high sensitivity when compared to conventional interferometry. The nonlinear optical birefringence (Deltan{2}) of these nematic phases was also determined. The sign and absolute value of this relevant nonlinear parameter are discussed in terms of structural changes in the micellar configuration which takes place in each nematic lyotropic phase.

RESUMO

PURPOSE: To compare the results of equations for estimate of the indirect maximal oxygen consumption with obtained them in test ergoespirometric in young individuals. METHODS: Fifty-two individuals of the masculine sex were submitted to the test of effort with it analyzes direct of gases in treadmill for the determination of the maximum consumption of oxygen (VO2máx). The progressive protocol was used with load increment to each one minute. The obtained results were compared ace equations of Jackson et al and the one of Mathews et al. For the statistical analysis of the results the test of multiple comparisons corrected by the test of Bonferrone was applied. The significance level was of p < 0.05. RESULTS: The average of age was of (21.06 +/- 2.75) years; body mass (70.85 +/- 9.15); thin mass (62.69 +/- 6.86); fat mass (8.30 +/- 4.77); percentile of fat (11.34 +/- 5.45) and maximun heartrate of (191.73 +/- 7.84). The equations of Jackson et al (VO2máx = 49.29 +/- 2.95) for a standard mistake of (EPE = 0.41) and Mathews et al (VO2máx = 37.43 +/-. 2.14) with a (EPE = 0,31) presenting tendency in underestimating the consumption of oxygen for the sample that was of (VO2máx = 55.34 +/- 8.34) for a (EPE = 1.16), being observed significant difference in relation to measure of the VO2máx obtained in test of effort (p < 0.05), for the value of Wilks'E = 0.044; F (2.500) = 539.27; p = 0.001. CONCLUSION: The equations didn't present a power of reliable estimate for the studied population.

Assuntos

RESUMO

In this report the temperature dependence of the coefficient of electronic polarizability (straight phi(i)) is determined by means of the thermal expansion coefficient (beta) and ordinary/extraordinary refractive indexes measurements near the calamitic nematic-isotropic phase transition in a lyotropic mixture of sodium decylsulphonate, decanol, and water. These parameters (straight phi(i) and beta) were related to the extraordinary and ordinary refractive indexes via the temperature derivative of the Vuks's equation. The results showed that near the nematic-isotropic phase transition, the measured value of straight phi(i) was found to be about two orders of magnitude smaller than that obtained for thermotropic, showing a remarkable difference in the molecular electronic polarizability strength between lyotropic and thermotropic liquid crystals.

RESUMO

The orientational properties of an isotropic dense liquid composed by anisotropic molecules, such as a liquid crystal in an isotropic phase, is studied. Using a Langevin-like equation it will be shown that the rotational motion of each molecule can be divided in two elements describing two kinds of physical motion. The first describes the Brownian rotational motion and another the coherent rotation induced by the external fields. It will be shown that, even at the isotropic phase, an order parameter describing the mean degree of alignment of the molecules around a given point can be defined. This order parameter also separates the order coming from the coherent motion from the order generated by the anisotropy in the thermal fluctuations. At the end the proposed model is compared with an experiment and it is shown that the coherent motion is enough to explain the experimental results.