Electron fluctuation induced resonance broadening in nano electromechanical systems: the origin of shear force in vacuum

This article presents a study of the poorly understood "shear-force" used in an important class of near-field instruments that use mechanical resonance feedback detection. In the case of a metallic probe near a metallic surface in vacuum, we show that in the 10-60 nm range there is no such a thing as a shear-force in the sense of the nonconservative friction force. Fluctuations of the oscillator resonance frequency, likely induced by local charge variations, could account for the reported effects in the literature without introducing a dissipative force.     

Impact of partial alcohol reduction in Syrah wine on perceived complexity and temporality of sensations and link with preference

Complexity is often stated as a mark of wine quality but there are no quantitative data supporting this assumption. The effect of partial alcohol reduction on the perceived complexity, temporality of sensations and liking of a Syrah wine was investigated.An Australian Syrah wine was partially dealcoholized using the reverse osmosis technique to obtain five wines with different alcohol content (13.5–8%). 71 French wine consumers evaluated their liking for these wines as well as the perceived intensity of overall complexity and eight items reported to be linked to perceived complexity in wine (familiarity, persistence, etc.) using continuous scales, anchored with pictures (Medel, Viala, Meillon, Urbano, & Schlich, 2009). In addition, eight trained panelists described temporality of sensations in the same wines with the Temporal Dominance of Sensations (TDS) method. The overall complexity scale was well understood by consumers with a significant discrimination of wines according to their alcohol content. Wines with higher alcohol content were perceived as more complex, persistent, strong and with many aromas. They were associated to more complex temporal sensory profiles, with many sensations that blend in-mouth along time.     

Emulsion copolymerization of styrene and n-butyl acrylate in presence of acrylic and methacrylic acids: Effect of pH on kinetics and carboxyl group distribution

The batch emulsion copolymerization of styrene with n-butyl acrylate in the presence of acrylic and methacrylic acids was investigated. Values of reaction rate and conversion observed at different pH values were examined. The effect of pH on the glass transition temperature of the polymers was also investigated and the results compared with model predictions. Its effect on the distribution of the carboxyl groups at different positions within the emulsion system (surface and core of particles, and in the aqueous phase) was also analyzed. Three methods were used to measure the number of carboxyl groups: conductimetry, organic phase potentiometry, and titration with a solution of sodium hydroxide in methanol. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2343–2355, 1997     

Accurate determination of the band-offset of a quantum semiconductor structure from its capacitance-voltage profile: Application to an InP/Ga0.47In0.53As/InP single quantum well

We discuss the possible analysis of an electron distribution obtained by capacitance-voltage profiling for the determination of the conduction band offset of a single quantum well. We show that, for this method which requires only relatively light experimental equipment, a nonconsuming computational time interpretation can be set up within a quite satisfactory degree of accuracy. As an application, we report the study of a lattice matched InP/Ga_0.47In_0.53As/InP quantum well for which we get ΔE_c = (200±10) meV, in good agreement with other measurements upon this system.     

Demonstration of celiac disease in Cuba

A study performed in 50 children carriers of celiac disease with ages between 8 months and 14 years of age, is presented; diagnosis was proved based on clinical picture, histological changes of jejunal mucosa, intestinal absorption tests and response to the suppression of gluten from the diet, with clinical, histological and biochemical control according to international criteria. It has been insisted on the familial study and the gluten overload test and its incidency in the black race. The development of public health has made it possible to demostrate the existence of this disease in our country.     

Structural characterization of TiNxOy/TiO2 single crystalline and nanometric multilayers grown by LP-MOCVD on (110)TiO2

TiO₂/TiN_xO_y superlattices were grown by Low Pressure-Metal-Organic Vapor Phase Epitaxy (LP-MOVPE) technique at deposition temperatures ranking from 650 to 750°C. The growth was performed on top of TiO₂(110) rutile substrates. Intense peaks observed in the X-rays rocking curves and θ-2θ diffraction patterns show the presence of crystalline epilayers. The TiN_xO_y layers were grown in a (200) cubic structure on the (110) quadratic TiO₂ epilayer structure. Transmission electron microscopy confirmed the XRD results and showed the formation of periodic and well structured epilayers.     

Susceptibility to LME of 316L and T91 steels by LBE: Effect of strain rate

The effect of liquid lead-bismuth eutectic on 316L and T91 steels at 160 °C has been studied as a function of strain rate, using a centre cracked in tension specimen adapted for the study of crack propagation. Brittle fracture, characterized by elongated river cracks on all the fracture surfaces, indicates that T91 is sensitive to the embrittlement by LBE. This embrittlement effect is very pronounced at low deformation rate (∼10⁻⁵ mm s⁻¹). A ductile-brittle transition is observed in the high strain rate range investigated. In the transitory regime, there is a competition between the growth of dimples and brittle cracking induced by the liquid metal. Ductility recovery is complete at the highest investigated deformation rate. The mechanical properties of the 316L steel are not clearly affected by the presence of LBE, in spite of a modification in the plastic deformation mode which strongly affects fracture surfaces.     

Modeling the powder compaction process using the finite element method and inverse optimization

This paper focuses on studying and adapting modeling techniques using the finite element method to simulate the rigid die compaction of metal powders. First, it presents the implementation of the cap constitutive model into ABAQUS FE software using the closest point projection algorithm. Then, an inverse modeling procedure was proposed to alleviate the problems raised by the interpretation of the experimental tests and to more accurately determine the material parameters. The objective function is formed, based on the discrepancy in density data between the numerical model prediction and the experiment. Minimization of the objective function with respect to the material parameters was performed using an in-house optimization software shell built on a modified Levenberg?CMarquardt method. Thus, an integrated simulation module consisting of an inverse optimization method and a finite element method was developed for modeling the powder compaction process as a whole. The simulation and identification module developed was applied to simulate the compaction of some industrial parts. The results reveal that the maximum absolute error between densities is 2.3%. It corresponds to the precision of the experimental method.     

Determination of the flow curve of complex fluids using the Rabinowitsch–Mooney equation in sensorless microrheometer

In this work, we present a way to make rheological measurements on a microfluidic chip. The originality of our approach relies on the determination of the flow curve of a fluid using the Rabinowitsch–Mooney equation. For this purpose, we use a parallel flow between a reference fluid and a studied fluid to measure the pressure drop inside the channel. Using a Newtonian fluid of known viscosity, knowing the flow rates of the two liquids and measuring the geometrical features of the two-phase flow allows determining the pressure drop in the channel. The Rabinowitsch–Mooney equation is used to calculate the local shear rate and shear stress at the wall for the studied sample. We validate our method for several complex fluids.     

Hot Wear Behavior of Steels 28NCDV10/Z20C13: Influence of Pre-Oxidation and Comparison with Al2O3, Al2O3-TiO2 Coatings

The purpose of this work is to investigate the influence of the preexistent oxide film on friction process between the forming tool and the tube, during the piercing in hot metal forming. A wear behavior of a low alloy steel (28NCDV10) is studied on a cylinder-ring tribometer. Two different atmospheres, which are air and steam, are employed for oxidizing the rings at 85O°C. The experimental results of rings without pre-oxidation exhibit a severe oxidation wear and metal transfer from the cylinder to the ring. While the oxidation of the rings, notably in the case of steam, shows a decrease in the wear rate. For a comparison with metallic materials, we considered some ceramic materials: A1₂O₃, Al₂O₃-TiO₂ We find that the metallic materials pre-oxidized in steam have a better behavior than all the other materials tested.