Bending Analysis of Nonlocal Functionally Graded Beams

In this paper, we study the nonlocal linear bending behavior of functionally graded beams subjected to distributed loads. A finite element formulation for an improved first-order shear deformation theory for beams with five independent variables is proposed. The formulation takes into consideration 3D constitutive equations. Eringen's nonlocal differential model is used to rewrite the nonlocal stress resultants in terms of displacements. The finite element formulation is derived by means of the principle of virtual work. High-order nodal-spectral interpolation functions were utilized to approximate the field variables, which minimizes the locking problem. Numerical results and comparisons of the present formulation with those found in the literature for typical benchmark problems involving nonlocal beams are found to be satisfactory and show the validity of the developed finite element model

Dynamic organization of ligand-grafted nanoparticles during adsorption and surface compression at fluid-fluid interfaces

Monolayers of ligand-grafted nanoparticles at fluid interfaces exhibit a complex response to deformation due to an interplay of particle rearrangements within the monolayer, and molecular rearrangements of the ligand brush on the surface of the particles. We use grazing-incidence small-angle X-ray scattering (GISAXS) combined with pendant drop tensiometry to probe in situ the dynamic organization of ligand-grafted nanoparticles upon adsorption at a fluid–fluid interface, and during monolayer compression. Through the simultaneous measurements of interparticle distance, obtained from GISAXS, and of surface pressure, obtained from pendant drop tensiometry, we link the interfacial stress to the monolayer microstructure. The results indicate that, during adsorption, the nanoparticles form rafts that grow while the interparticle distance remains constant. For small-amplitude, slow compression of the monolayer, the evolution of the interparticle distance bears a signature of ligand rearrangements leading to a local decrease in thickness of the ligand brush. For large-amplitude compression, the surface pressure is found to be strongly dependent on the rate of compression. Two-dimensional Brownian dynamics simulations show that the rate-dependent features are not due to jamming of the monolayer, and suggest that they may be due to out-of-plane reorganization of the particles (for instance expulsion or buckling). The corresponding GISAXS patterns are also consistent with out-of-plane reorganization of the nanoparticles

Magnetic Surgical Instruments for Robotic Abdominal Surgery.

This review looks at the implementation of magnetic-based approaches in surgical instruments for abdominal surgeries. As abdominal surgical techniques advance toward minimizing surgical trauma, surgical instruments are enhanced to support such an objective through the exploration of magnetic-based systems. With this design approach, surgical devices are given the capabilities to be fully inserted intraabdominally to achieve access to all abdominal quadrants, without the conventional rigid link connection with the external unit. The variety of intraabdominal surgical devices are anchored, guided, and actuated by external units, with power and torque transmitted across the abdominal wall through magnetic linkage. This addresses many constraints encountered by conventional laparoscopic tools, such as loss of triangulation, fulcrum effect, and loss/lack of dexterity for surgical tasks. Design requirements of clinical considerations to aid the successful development of magnetic surgical instruments, are also discussed

Sistematização e identificação de direcionadores e demandas para a produção de bovinos de corte.

O objetivo desse trabalho foi sistematizar um método de priorização e identificar uma lista preliminar de direcionadores e demandas.Claudia Cristina Gulias Gomes, editora técnica

List Of Angiosperm Species In An Atlantic Forest Fragment Reveals Collection Gaps In Espírito Santo State, Brazil

This study presents a list of angiosperm species in an Atlantic Forest fragment in the southern portion of Espírito Santo state, Brazil, a region that represents a collection gap within the Atlantic Forest. The studied site is a relatively small fragment of 144 ha located within a conservation unit, the Mata das Flores State Park. The site belongs to a conservation priority area for the Atlantic Forest in Espírito Santo, and is under strong anthropic pressure. Of the 239 species listed here, 21 are new records for the state, eight are endemic, and 20 figure either in the country’s or the state’s Red Lists of endangered species. Rubiaceae and Piperaceae were the families with the highest number of species. We show that small fragments that were never inventoried before can reveal a relatively large number of threatened species and that collection gaps need to be filled in order to refine our understanding about conservation priorities within the Atlantic Forest Biome. © 2016 Check List and Authors.12111

Análise econômica de integração lavoura-pecuária no pampa gaúcho sob condições de risco.

Resumo.Fernando Flores Cardoso, Daniel Portella Montardo, José Carlos Ferrugem Moraes, Marcos Flávio Silva Borba, Sandro da Silva Camargo, editores técnicos

Surface Charge Measurement of SonoVue, Definity and Optison: A Comparison of Laser Doppler Electrophoresis and Micro-Electrophoresis

Microbubble (MB) contrast-enhanced ultrasonography is a promising tool for targeted molecular imaging. It is important to determine the MB surface charge accurately as it affects the MB interactions with cell membranes. In this article, we report the surface charge measurement of SonoVue, Definity and Optison. We compare the performance of the widely used laser Doppler electrophoresis with an in-house micro-electrophoresis system. By optically tracking MB electrophoretic velocity in a microchannel, we determined the zeta potentials of MB samples. Using micro-electrophoresis, we obtained zeta potential values for SonoVue, Definity and Optison of −28.3, −4.2 and −9.5 mV, with relative standard deviations of 5%, 48% and 8%, respectively. In comparison, laser Doppler electrophoresis gave −8.7, +0.7 and +15.8 mV with relative standard deviations of 330%, 29,000% and 130%, respectively. We found that the reliability of laser Doppler electrophoresis is compromised by MB buoyancy. Micro-electrophoresis determined zeta potential values with a 10-fold improvement in relative standard deviation

Stochastic computing based on volatile GeSe ovonic threshold switching selectors

Stochastic computing (SC) is a special type of digital compute strategy where values are represented by the probability of 1 and 0 in stochastic bit streams, which leads to superior hardware simplicity and error-tolerance. In this paper, we propose and demonstrate SC with GeSe based Ovonic Threshold Switching (OTS) selector devices by exploiting their probabilistic switching behavior. The stochastic bit streams generated by OTS are demonstrated with good computation accuracy in both multiplication operation and image processing circuit. Moreover, the bit distribution has been statistically studied and linked to the collective defect de/localization behavior in the chalcogenide material. Weibull distribution of the delay time supports the origin of such probabilistic switching, facilitates further optimization of the operation condition, and lays the foundation for device modelling and circuit design. Considering its other advantages such as simple structure, fast speed, and volatile nature, OTS is a promising material for implementing SC in a wide range of novel applications, such as image processors, neural networks, control systems and reliability analysis

Heart rate variability and early recurrence of atrial fibrillation after electrical cardioversion

The study evaluated the role of the autonomic nervous system in atrial fibrillation (AF) recurrence