Large eddy simulation of free-shear flows using an algebraic model

Large eddy simulation of the free-shear flows has been performed using an algebraic subgrid stress model. The test cases considered are the temporal planar jet and mixing layer. The results are compared with that of the Smagorinsky, dynamic Smagorinsky, mixed models and the DNS data. For the mean flow quantities none of the models perform exceptionally better over the others. However, both the algebraic and mixed models predict better statistics for the turbulent quantities than the linear models. The results also demonstrate the capability of the algebraic model in depicting backscatter of energy explicitly, which is consistent in both the cases considered.     

Countercurrent water-heating system with a heat exchanger in a solar energy collector loop

The counter current heat exchanger theory with periodic inlet temperatures has been applied to analyze the thermal performance of a water heating system. The theoretical results obtained are in agreement with the experimental data reported in the literature.     

Surface modification of AFM silicon probes for adhesion and wear reduction

Tip wear of silicon probes used for an atomic force microscope (AFM) is a critical issue. Wear can result in an increase of tip radius and adhesion between tip and sample, thus reducing the image resolution and introducing artifacts. In order to reduce adhesion, friction, and wear so as to reduce tip related artifacts, liquid lubricant (Z-TETRAOL), self-assembled monolayers (pentafluorophenyltriethoxysilane (PFPTES)), and fluorocarbon polymer (Fluorinert™) were applied on the silicon probe. A comprehensive investigation of adhesion, friction, and wear of the uncoated/coated tips in both ambient air and various humidity levels as well as the influence of the coatings on the image resolution was performed. Experiments showed that the coatings reduced the adhesion, friction, and wear of the silicon tip, improved the initial image resolution, and exhibited less deterioration as compared to that of uncoated tip in the long-term test.     

Nanotribological characterization of human hair and skin using atomic force microscopy

Healthy hair and skin is highly desired. Characterization of their morphological, frictional, and adhesive properties (tribological properties) is essential to enhance understanding of hair and skin and to advance the science. Literature on the tribological characterization of hair and skin is scarce to date. The paper presents nanotribological data and analysis on hair (Caucasian, Asian, and African hair at virgin, chemo-mechanically damaged, and treated conditions) and synthetic hair and skin, as well as roughness data of human skin replica. Roughness statistics are presented to characterize the vertical and spatial surface parameters. Average coefficient of friction values were determined for each ethnicity and hair type, and are discussed. The directionality dependence of friction is also discussed. Magnitude and spatial distribution of adhesive force are used to estimate thickness and distribution of the conditioner film.     

Electrostatic ion trap and Fourier transform measurements for high-resolution mass spectrometry

We report on the development of an electrostatic ion trap for high-resolution mass spectrometry. The trap works on purely electrostatic fields and hence trapping and storing of ions is not mass restrictive, unlike other techniques based on Penning, Paul, or radio frequency quadrupole ion traps. It allows simultaneous trapping and studying of multiple mass species over a large mass range. Mass spectra were recorded in "dispersive" and "self-bunching" modes of ions. Storage lifetimes of about 100 ms and mass resolving power of about 20,000 could be achieved from the fifth harmonic Fourier transform spectrum of Xe ions recorded in the self-bunching mode.     

A feedback glucose control strategy for type II diabetes mellitus based on fuzzy logic

Most patients with severe Type II diabetes mellitus, characterised by both insulin resistance and β‐cell failure, eventually require insulin therapy. According to the nonlinear dynamics of homeostasis of blood glucose, proportional‐integral (PI) controller, modified by penalising the feedback error using a fuzzy inference system has been developed to maintain normoglycaemia in a simulated patient using a closed‐loop insulin infusion pump. The simulation employs a compartment model proposed by Vahidi et al. [Vahidi et al., Biochem. Eng. J. 2011, 55(1), 7–16]. The results demonstrate that the fuzzy‐based PI controller is superior to a conventional PI controller for the regulation of blood glucose by insulin infusion for Type II diabetic patients. © 2012 Canadian Society for Chemical Engineering     

Influence of Reaction Conditions on Diacid Formation During Au-Catalyzed Oxidation of Glycerol and Hydroxymethylfurfural

The selective oxidation of glycerol and 5-hydroxymethylfurfural (HMF) to diacids over supported gold catalysts (Au/C and Au/TiO₂) in liquid water at mild temperatures was a strong function of the added base such as NaOH. Use of hydrotalcite as a solid base in place of NaOH in the HMF reaction medium facilitated the production of diacid over Au/TiO₂, but extensive leaching of magnesium suggested that hydrotalcite was consumed stoichiometrically in the reaction. Production of diacids from glycerol oxidation over supported Au catalysts was promoted by operating in a continuous flow reactor and by increasing the catalyst loading in a semi-batch reactor. Trace inhibitors formed by conversion of the product monoacid are proposed to account for the generally low selectivity to diacids over gold catalysts.     

Correction to: Optimization of Parameters for Maximum Tensile Strength of Friction Stir Welded AA6082/Si3N4 and AA6082/SiC Composite Joints

Silicon - The original version of this paper was unfortunately published with an error in the order of authors and their corresponding affiliations. The correct data is shown above.