Search results for "CONTACT"

Reactive Coatings in Glass Capillaries: Preparation of Temperature- and Light-Responsive Surfaces and Accurate Determination of Wettability Switching

2015

Heterogeneous nucleation of a droplet pinned at a chemically inhomogeneous substrate: A simulation study of the two-dimensional Ising case

2018

Heterogeneous nucleation is studied by Monte Carlo simulations and phenomenological theory, using the two-dimensional lattice gas model with suitable boundary fields. A chemical inhomogeneity of length b at one boundary favors the liquid phase, while elsewhere the vapor is favored. Switching on the bulk field Hb favoring the liquid, nucleation and growth of the liquid phase starting from the region of the chemical inhomogeneity are analyzed. Three regimes occur: for small fields, Hb bcrit, the critical droplet radius is so large that a critical droplet having the contact angle θc required by Young's equation in the region of the chemical inhomogeneity does not yet "fit" there since the base…

Failure Map of Composite Laminate Mechanical Joint

2007

The aim of this research is to investigate the pin/hole contact stress of a composite laminate and failure modes when submitted to tensile bearing tests. The limit loads and failure modes are evaluated as a function of pin diameter and hole position. Analyzing the joint geometry effect on the fracture mechanisms, a failure map is obtained, identifying three regions of typical failure modes of mechanically fastened joints. A theoretical approach is proposed to identify the field of each fracture mode to obtain a simple experimental methodology to support the design of a particular joint laminate. In addition, a simplified numerical model is proposed to evaluate near the hole the stress/stra…

2021

Controlling thermal transport at the nanoscale is vital for many applications. Previously, it has been shown that this control can be achieved with periodically nanostructured two-dimensional phononic crystals for the case of suspended devices. Here, we show that thermal conductance can also be controlled with three-dimensional phononic crystals, allowing the engineering of the thermal contact of more varied devices without the need for suspension in the future. We show the experimental results obtained at sub-Kelvin temperatures for two different period three-dimensional crystals and for a bulk control structure. The results show that the conductance can be enhanced with the phononic cryst…

Capacitance study of thin film SnO2:F/p-type a-Si:H heterojunctions

2011

Abstract We characterized SnO 2 :F/p-type a-Si:H heterojunctions by current-voltage (I-V) and capacitance-voltage (C-V) measurements at room temperature to determine the junction parameters. Samples with circular geometry and different diameters were characterized. The current scales with the junction area, and the current density J as a function of the voltage V is a slightly asymmetric curve with a super-linear behaviour (cubic law) for high voltages. Using a transmission line model valid for devices with circular geometry, we studied the effects of the SnO 2 :F resistivity on the measured capacitance when the SnO2:F layer works as an electrical contact. The measured C-V curve allows us t…

In vitro power profiles of daily disposable contact lenses

2012

Abstract Purpose To evaluate and compare the distribution of refractive power within the optic zone of different soft contact lenses and to investigate the effect of lens decentration on the power profiles. Methods The Nimo TR1504 instrument was used to measure the optical power across different aperture diameters (from 1.5 mm to 5.5 mm in steps of 0.5 mm) of four daily disposable contact lenses: DAILIES TOTAL1, Proclear 1-Day, SofLens daily disposable and 1-DAY ACUVUE MOIST. Measurements were performed using a wet cell. Power data were evaluated when contact lenses were in its centered position and after inducing different amounts of lens decentration (from 0.2 mm to 1.0 mm in steps of 0.2…

True and Apparent Oxygen Permeabilities of Contact Lenses

1992

We studied the passage of oxygen through some commercially available contact lenses. Oxygen diffusion coefficients were determined by the time-lag method and a 201T Redher permeometer was used to measure the oxygen permeability and transmissibility by the polarographic method. The measurements were carried out at room temperature with 0.09% sodium chloride physiologic solution. The following types of lenses were tested: (1) 12 lenses of cellulose acetate butyrate (CAB) of a mean thickness of 0.194 mm (observed Dk approximately 6.3 barrers) (1 barrier is equivalent to 10(-11) cm3 of O2 (STP).cm2/cm3.s.mm Hg). (2) 13 lenses of a cross-linked polyhydroxyethyl methacrylate (2-HEMA), manufacture…

Biological oxygen apparent transmissibility of hydrogel contact lenses with and without organosilicon moieties.

2003

The instrument oxygen transmissibility (IOT) of organosilicon hydrogels, measured by electrochemical procedures, is 5-10 times larger than that of conventional hydrogels. A method is described that allows the estimation of the oxygen tension at the lens-cornea interface for closed- and open-eyelids situations by combining the IOT of the hydrogels and corneal parameters such as corneal thickness, corneal permeability and oxygen flux across the cornea. From these results the biological oxygen apparent transmissibility (BOAT) is obtained, an important parameter which an multiplication with the pressure of oxygen on the external part of the lens gives the oxygen flux onto the cornea. Contact le…

Multiwall carbon-nanotube interconnects: radial effects on physical models and resistance calculations for various metal substrates

2010

Based on a model with singular attractive potential of equidistant conductive cylinders, we illustrate an approach to calculate the electron spectrum of metallic multiwall carbon nanotubes (MW CNT) with an arbitrary number of coaxial layers. We compute the number of electrically active channels, N ch , in the ideal case when all MW CNT shells are contacted to the electrodes, starting from the one-electron spectrum. The dependence of N ch on the temperature and on both the innermost and outermost shells radii allows us to discuss the potential performances of MW CNT interconnects, affecting the power dissipation of integrated circuits. Our description improves over the isolated shells model,…

CO2 to Liquid Fuels: Photocatalytic Conversion in a Continuous Membrane Reactor

2018

The photocatalytic reduction of CO, into value-added chemicals using sunlight is a promising approach to promote energy-bearing products, mitigating the adverse effects of anthropogenic CO2 emissions. In this work, exfoliated C3N4 was incorporated into Nafion matrix and used in a continuous photocatalytic reactor for converting CO2 into liquid fuels. Comprehensive structural and morphological diffuse reflectance spectroscopy (DRS), FT-IR, ATR-IR, and SEM measurements were performed for C3N4-loaded Nafion membrane and then compared with those of a Nafion membrane without any catalyst. The synergic effect of C3N4 organic catalyst embedded in a Nafion dense matrix and a continuous operating mo…