Carbendazim e modelos de biomembrana via filmes de Langmuir e Layer-by-Layer: mecanismos de interação e desenvolvimento de sensores

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação do Sistema Simplified Drum-Buffer-Rope em ambientes de produção para estoque

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Caracterização da liga Ti-30Ta após tratamento biomimético associado à incorporação de antibiótico

Surface treatments have been used to modify the surface of titanium alloys. The purpose of this study is to evaluate the surface of Ti-30Ta alloy after biomimetic approach associated to antibiotic incorporation. The ingots were obtained in arc melting furnace, treated and cold-worked by swaging. The surface treatment was performed in two steps: biomimetic treatment and antibiotic incorporation. For biomimetic treatment, first an alkaline treatment (NaOH 1M at 60ºC) was performed, followed by heat treatment and immersion in SBFx5 (Simulated Body Fluid) for a period of 24 hours. In order to incorporate the antibiotic, samples were immersed in a solution formed by drugs plus SBFx5 for 48 hours. The sample surfaces were analyzed by scanning electron microscopy (SEM), X-Ray diffraction (XRD), atomic force microscopy (AFM) and contact angle measurements. The release of antibiotic from coated implants was measured in phosphate buffer saline at pH 7.4 by using UV/VIS spectrometry. Results have shown changes on the surface after incorporating the drug, which is gradually co-precipitated with the Ca-P crystals, forming a uniform and rough layer on the metal surface

Cross-Layer Packet Size Optimization for Wireless Terrestrial, Underwater, and Underground Sensor Networks

In this paper, a cross-layer solution for packet size optimization in wireless sensor networks (WSN) is introduced such that the effects of multi-hop routing, the broadcast nature of the physical wireless channel, and the effects of error control techniques are captured. A key result of this paper is that contrary to the conventional wireless networks, in wireless sensor networks, longer packets reduce the collision probability. Consequently, an optimization solution is formalized by using three different objective functions, i.e., packet throughput, energy consumption, and resource utilization. Furthermore, the effects of end-to-end latency and reliability constraints are investigated that may be required by a particular application. As a result, a generic, cross-layer optimization framework is developed to determine the optimal packet size in WSN. This framework is further extended to determine the optimal packet size in underwater and underground sensor networks. From this framework, the optimal packet sizes under various network parameters are determined.

Minimun Riparian Buffer Width for Maintaining Water Quality and Habitat Along Stevens Creek

ABSTRACT Riparian buffer zones are important sites of biodiversity, sediment trapping, pollutant removal, and hydrologic regulation that have significant implications for both people and wildlife. Urbanization’s influence on and need for adequate water quality increases the need for careful planning in regards to riparian areas. Wildlife are key components in the ecosystem functions of riparian zones and require consideration in peri-urban planning as well. This study reviews relevant literature to determine the recommended minimum riparian buffer width for maintaining water quality and habitat along Stevens Creek in Lincoln, Nebraska. Only sources that listed a specific purpose related to water quality and habitat for their buffer width recommendations were considered. The study found that the baseline buffer width recommended for Stevens Creek that would be adequate for both water quality maintenance and basic habitat is 50 ft (15 m) per side. This number may be modified based on other factors such as slope, soil particle size, adjacent land use, the presence of certain wildlife communities, stream size, and stream order.

Caracterização da liga Ti-30Ta após tratamento biomimético associado à incorporação de antibiótico

Surface treatments have been used to modify the surface of titanium alloys. The purpose of this study is to evaluate the surface of Ti-30Ta alloy after biomimetic approach associated to antibiotic incorporation. The ingots were obtained in arc melting furnace, treated and cold-worked by swaging. The surface treatment was performed in two steps: biomimetic treatment and antibiotic incorporation. For biomimetic treatment, first an alkaline treatment (NaOH 1M at 60ºC) was performed, followed by heat treatment and immersion in SBFx5 (Simulated Body Fluid) for a period of 24 hours. In order to incorporate the antibiotic, samples were immersed in a solution formed by drugs plus SBFx5 for 48 hours. The sample surfaces were analyzed by scanning electron microscopy (SEM), X-Ray diffraction (XRD), atomic force microscopy (AFM) and contact angle measurements. The release of antibiotic from coated implants was measured in phosphate buffer saline at pH 7.4 by using UV/VIS spectrometry. Results have shown changes on the surface after incorporating the drug, which is gradually co-precipitated with the Ca-P crystals, forming a uniform and rough layer on the metal surface

Opto-electrical properties of single layer flexible electroluminescence device with ruthenium complex

In this work, a ruthenium hexafluorophosphate complex, [Ru(bpy)(3)](PF6)(2) in poly(methylmethacrylate) (PMMA) was employed to build a single layer light electrochemical cell on indium tin oxide polyester flexible substrate. The electroluminescence spectrum features a relatively broad band peaked near 625 run, with CIE (x,y) color coordinates of (0.61,0.39). The driving voltage is only 3 V, and for the maximum electrical current of 10 mA the brightness reaches 1 cd/m(2). Regarding the useful application of the device, its opto-electrical behavior under mechanical strain was studied considering the central curvature. In these situations, both electrical characterization in DC mode and luminance were analyzed. (C) 2007 Elsevier B.V. All rights reserved.

Photo and electroluminescence behavior of Tb(ACAC)(3)phen complex used as emissive layer on organic light emitting diodes

This work shows the luminescence properties of a rare-earth organic complex, the Tb(ACAC)(3)phen. The results show the (5)D(4)->(7)F(3,4,5,6) transitions with no influence of the ligand. The photoluminescence excitation spectrum is tentatively interpreted by the ligands absorption. An organic light emitting diode (CLED) was made by thermal evaporation using TPD (N,N`-bis(3-methylphenyl)N,N`-diphenylbenzidine) and Alq3 (aluminum-tris(8-hydroxyquinoline)) as hole and electron transport layers, respectively. The emission reproduces the photoluminescence spectrum of the terbium complex at room temperature, with Commission Internationale de l`Eclairage - CIE (x,y) color coordinates of (0.28,0.55). No presence of any bands from the ligands was observed. The potential use of this compound in efficient devices is discussed. (C) 2008 Elsevier B.V. All rights reserved.

Development and characterization of light-emitting diodes (LEDs) based on ruthenium complex single layer for transparent displays

In this work, two ruthenium complexes, [Ru(bpy)(3)](PF6)(2) and [Ru(ph2phcn)(3)](PF6)(2) in poly(inethylinethacrylate) matrix were employed to build single-layer light-emitting electrochemical cells by spin coating on indium tin oxide substrate. In both cases the electroluminescence spectra exhibit a relatively broad band with maxima near to 625 rim and CIE (x, y) color coordinates of (0.64, 0.36), which are comparable with the photoluminescence data in the same medium. The best result was obtained with the [Ru(bpy)(3)](PF6)(2) device where the optical output power approaches 10 mu W at the band maximum with a wall-plug efficiency higher than 0.03%. The lowest driving voltage is about 4 V for an electrical current of 20 mA. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A two-layer approximation to the Brazil Current-Intermediate Western Boundary Current System between 20 degrees S and 28 degrees S

It has been shown that the vertical structure of the Brazil Current (BC)-Intermediate Western Boundary Current (IWBC) System is dominated by the first baroclinic mode at 22 degrees S-23 degrees S. In this work, we employed the Miami Isopycnic Coordinate Ocean Model to investigate whether the rich mesoscale activity of this current system, between 20 degrees S and 28 degrees S, is reproduced by a two-layer approximation of its vertical structure. The model results showed cyclonic and anticyclonic meanders propagating southwestward along the current axis, resembling the dynamical pattern of Rossby waves superposed on a mean flow. Analysis of the upper layer zonal velocity component, using a space-time diagram, revealed a dominant wavelength of about 450 km and phase velocity of about 0.20 ms(-1) southwestward. The results also showed that the eddy-like structures slowly grew in amplitude as they moved downstream. Despite the simplified design of the numerical experiments conducted here, these results compared favorably with observations and seem to indicate that weakly unstable long baroclinic waves are responsible for most of the variability observed in the BC-IWBC system. (C) 2009 Elsevier Ltd. All rights reserved.

A Comparative Wet Collapse Buckling Study for the Carcass Layer of Flexible Pipes

When there is a failure on the external sheath of a flexible pipe, a high value of hydrostatic pressure is transferred to its internal plastic layer and consequently to its interlocked carcass, leading to the possibility of collapse. The design of a flexible pipe must predict the maximum value of external pressure the carcass layer can be subjected to without collapse. This value depends on the initial ovalization due to manufacturing tolerances. To study that problem, two numerical finite element models were developed to simulate the behavior of the carcass subjected to external pressure, including the plastic behavior of the materials. The first one is a full 3D model and the second one is a 3D ring model, both composed by solid elements. An interesting conclusion is that both the models provide the same results. An analytical model using an equivalent thickness approach for the carcass layer was also constructed. A good correlation between analytical and numerical models was achieved for pre-collapse behavior but the collapse pressure value and post-collapse behavior were not well predicted by the analytical model. [DOI: 10.1115/1.4005185]

Long-Term Stability at High Temperatures for Birefringence in PAZO/PAH Layer-by-Layer Films

Optical memories with long-term stability at high temperatures have long been pursued in azopolymers with photoinduced birefringence. In this study, we show that the residual birefringence in layer-by-layer (LbL) films made with poly[1-[4-(3-carboxy-4 hydroxyphenylazo)benzene sulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) alternated with poly(allylamine hydrochloride) (PAH) can be tuned by varying the extent of electrostatic interactions with film fabrication at different pHs for PAH. The dynamics of both writing and relaxation processes could be explained with a two-stage mechanism involving the orientation of the chromophores per se and the chain movement. Upon calculating the activation energies for these processes, we demonstrate semiquantitatively that reduced electrostatic interactions in films prepared at higher pH, for which PAH is less charged, are responsible for the longer stability at high temperatures. This is attributed to orientation of PAZO chromophores via cooperative aggregation, where the presence of counterions hindered relaxation.

Quality Metric to Assess Video Streaming Service over TCP considering Temporal Location of Pauses

There is a wide range of video services over complex transmission networks, and in some cases end users fail to receive an acceptable quality level. In this paper, the different factors that degrade users' quality of experience (QoE) in video streaming service that use TCP as transmission protocol are studied. In this specific service, impairment factors are: number of pauses, their duration and temporal location. In order to measure the effect that each temporal segment has in the overall video quality, subjective tests. Because current subjective test methodologies are not adequate to assess video streaming over TCP, some recommendations are provided here. At the application layer, a customized player is used to evaluate the behavior of player buffer, and consequently, the end user QoE. Video subjective test results demonstrate that there is a close correlation between application parameters and subjective scores. Based on this fact, a new metrics named VsQM is defined, which considers the importance of temporal location of pauses to assess the user QoE of video streaming service. A useful application scenario is also presented, in which the metrics proposed herein is used to improve video services(1).

Suppression of vortex-induced vibration using moving surface boundary-layer control

Experimental results of flow around a circular cylinder with moving surface boundary-layer control (MSBC) are presented. Two small rotating cylinders strategically located inject momentum in the boundary layer of the cylinder, which delays the separation of the boundary layer. As a consequence, the wake becomes narrower and the fluctuating transverse velocity is reduced, resulting in a recirculation free region that prevents the vortex formation. The control parameter is the ratio between the tangential velocity of the moving surface and the flow velocity (U-c/U). The main advantage of the MSBC is the possibility of combining the suppression of vortex-induced vibration (VIV) and drag reduction. The experimental tests are preformed at a circulating water channel facility and the circular cylinders are mounted on a low-damping air bearing base with one degree-of-freedom in the transverse direction of the channel flow. The mass ratio is 1.8. The Reynolds number ranges from 1600 to 7500, the reduced velocity varies up to 17, and the control parameter interval is U-c/U = 5-10. A significant decreasing in the maximum amplitude of oscillation for the cylinder with MSBC is observed. Drag measurements are obtained for statically mounted cylinders with and without MSBC. The use of the flow control results in a mean drag reduction at U-c/U = 5 of almost 60% compared to the plain cylinder. PIV velocity fields of the wake of static cylinders are measured at Re = 3000. The results show that the wake is highly organized and narrower compared to the one observed in cylinders without control. The calculation of the total variance of the fluctuating transverse velocity in the wake region allows the introduction of an active closed-loop control. The experimental results are in good agreement with the numerical simulation studies conducted by other researchers for cylinders with MSBC. (C) 2012 Elsevier Ltd. All rights reserved.

Numerical study of Mach number and thermal effects on sound radiation by a mixing layer

Mach number and thermal effects on the mechanisms of sound generation and propagation are investigated in spatially evolving two-dimensional isothermal and non-isothermal mixing layers at Mach number ranging from 0.2 to 0.4 and Reynolds number of 400. A characteristic-based formulation is used to solve by direct numerical simulation the compressible Navier-Stokes equations using high-order schemes. The radiated sound is directly computed in a domain that includes both the near-field aerodynamic source region and the far-field sound propagation. In the isothermal mixing layer, Mach number effects may be identified in the acoustic field through an increase of the directivity associated with the non-compactness of the acoustic sources. Baroclinic instability effects may be recognized in the non-isothermal mixing layer, as the presence of counter-rotating vorticity layers, the resulting acoustic sources being found less efficient. An analysis based on the acoustic analogy shows that the directivity increase with the Mach number can be associated with the emergence of density fluctuations of weak amplitude but very efficient in terms of noise generation at shallow angle. This influence, combined with convection and refraction effects, is found to shape the acoustic wavefront pattern depending on the Mach number.