Evaluation of mixing profiles for a new micromixer design strategy

The relationship between mixing history and reaction performance in microreactors using computational fluid dynamics (CFD) simulations is identified. In the idealized, simplified mixing model, mixing proceeds linearly and only the mixing time determined the reaction performance. However, in the case of realistic models where mixing proceeds unequally, the partial rapid progression of mixing, more than the mixing time, significantly impacts the reaction. The use of the fluid segment size distribution to capture this effect is proposed. The effective Damköhler number derived from the fluid segment size distribution predicted the reaction yield well. To demonstrate the utility of the mixing profile design strategy, we fabricated a novel micromixer with multiple partial rapid mixing zones. This micromixer achieved excellent results both in a CFD simulation and an experiment. © 2015 American Institute of Chemical Engineers AIChE J, 62: 1154–1161, 2016     

Multi-objective topology optimization of multi-component continuum structures via a Kriging-interpolated level set approach

This paper explores a framework for topology optimization of multi-component sheet metal structures, such as those often used in the automotive industry. The primary reason for having multiple components in a structure is to reduce the manufacturing cost, which can become prohibitively expensive otherwise. Having a multi-component structure necessitates re-joining, which often comes at sacrifices in the assembly cost, weight and structural performance. The problem of designing a multi-component structure is thus posed in a multi-objective framework. Approaches to solve the problem may be classified into single and two stage approaches. Two-stage approaches start by focusing solely on structural performance in order to obtain optimal monolithic (single piece) designs, and then the decomposition into multiple components is considered without changing the base topology (identical to the monolithic design). Single-stage approaches simultaneously attempt to optimize both the base topology and its decomposition. Decomposition is an inherently discrete problem, and as such, non-gradient methods are needed for single-stage and second stage of two-stage approaches. This paper adopts an implicit formulation (level-sets) of the design variables, which significantly reduces the number of design variables needed in either single or two stage approaches. The number of design variables in the formulation is independent from the meshing size, which enables application of non-gradient methods to realistic designs. Test results of a short cantilever and an L-shaped bracket studies show reasonable success of both single and two stage approaches, with each approach having different merits.     

Pose-Invariant Facial Expression Recognition Using Variable-Intensity Templates

In this paper, we propose a method for pose-invariant facial expression recognition from monocular video sequences. The advantage of our method is that, unlike existing methods, our method uses a simple model, called the variable-intensity template, for describing different facial expressions. This makes it possible to prepare a model for each person with very little time and effort. Variable-intensity templates describe how the intensities of multiple points, defined in the vicinity of facial parts, vary with different facial expressions. By using this model in the framework of a particle filter, our method is capable of estimating facial poses and expressions simultaneously. Experiments demonstrate the effectiveness of our method. A recognition rate of over 90% is achieved for all facial orientations, horizontal, vertical, and in-plane, in the range of ±40 degrees, ±20 degrees, and ±40 degrees from the frontal view, respectively. Electronic Supplementary Material  The online version of this article () contains supplementary material, which is available to authorized users.     

Performances of metal fluoride added carbon anodes with pre-electrolysis for electrolytic synthesis of NF3

Metal fluoride added carbon anodes treated by pre-electrolysis were investigated for electrolytic production of nitrogen trifluoride (NF₃) in molten NH₄F·KF·4HF at 100 °C. The conditions for pre-electrolysis were first optimized using a graphite sheet anode as a model anode. The formation of fluorine-graphite intercalation compounds (fluorine-GICs) with semi-covalent C–F bonds, (C_xF)_n, on the MgF₂ and CaF₂ added carbon anode surface was accelerated by pre-electrolysis at potentials less than 4.0 V. Critical current densities (CCD) on the MgF₂ added carbon anodes pre-electrolyzed under various conditions were determined, and the highest CCD was 290 mA cm⁻² obtained for that pre-electrolyzed at 3.5 V for 500 C cm⁻². This anode was successfully used in the electrolysis at 100 mA cm⁻² for 290 h and the maximum NF₃ current efficiency was 55%. From these results, it was concluded that the metal fluoride added carbon anode treated by pre-electrolysis has a high potential for electrolytic production of NF₃ at higher current density.     

Rate acceleration of Diels–Alder reactions utilizing a fluorous micellar system in water

A fluorous micellar system in water has been created to produce a large interfacial area between these media that retains substrates, effectively facilitating intermolecular Diels–Alder reactions due to repulsion effects from both media. Because LiFOS functioned not only as a surfactant but also as a supporting electrolyte, an electrochemical approach could be introduced to evaluate the rate acceleration effects. The measurement of the particle size distribution of the fluorous micelles clearly supported these evaluations.     

Synthesis of sulfonated organic–inorganic hybrids through the radical copolymerization of vinyl sulfonate esters and vinyl trialkoxysilanes

Novel organic–inorganic hybrids with sulfonic acid groups were prepared using random copolymers composed of vinyl sulfonate esters and vinyl trialkoxysilanes. Five vinyl sulfonate esters with different substituent groups were employed as protecting monomers for the production of the poly(vinyl sulfonic acid) component, and three vinyl trialkoxysilanes were used as cross-linkable monomers. Free radical and reversible addition-fragmentation chain transfer (RAFT) copolymerizations were performed for the production of random copolymers with two different functional groups. The selective deprotection of the sulfonate esters of the copolymers proceeded smoothly and resulted in the formation of copolymers with lithium vinyl sulfonate units and cross-linkable trialkoxysilane units. The co-condensation of the trialkoxysilane moieties in the deprotected copolymers with cross-linkers yielded transparent hybrid films that contained lithium sulfonate groups without aromatic rings or ester linkages.     

Determination of optical purity and absolute configuration of natural 12‐hydroxystearic acid by the 1H NMR anisotropy method

The enantiopure of (R)‐(?) MαNPA was allowed to react with racemic 18‐(tert‐butyldimethylsilyloxy)‐5‐octadecayne‐7‐ol which was derived from dodecane‐1,12‐diol, yielding diastereomeric esters mixture. These racemic esters were easily separated by HPLC on silica‐gel. The absolute configurations of the first‐eluted diastereomeric esters from the separated esters were determined using ¹H NMR anisotropy method. Analysis on ¹H NMR spectra and HPLC elution time of the synthesized esters and those of MαNP ester derived from natural methyl‐12‐hydroxystealate showed that the absolute configuration of natural 12‐hydroxystearic acid was R form, and the enantiomeric excess was over 99%.     

Responsiveness of electric resistance of polymer-grafted carbon black/alumina gel composite against solvent vapor and solute in solution

The carbon black/alumina gel composites were prepared by sol-gel reaction of aluminum isopropoxide in the presence of polymer-grafted carbon black. The electric resistance of the alumina gel composite from polymer-grafted carbon black was very sensitive to vapor of good solvent for grafted polymer on carbon black: the electric resistance of the alumina gel composite suddenly decreased in solvent vapor and returned to initial resistance when it was transferred into dry air. The effect of surface area and particle size of carbon black on the responsiveness was also investigated. In addition, the electric resistance of the alumina gel composite was found to respond to water and methanol in n-hexane and diethyl ether.     

Environmental stress cracking of poly(acrylonitrile-butadiene-styrene)

The environmental stress cracking (ESC) of acrylonitrile-butadiene-styrene (ABS) copolymer caused by a non-ionic surfactant (poly-oxyethylene alkylether) was studied by constant-load tensile creep tests and edge crack tension (ECT) tests. The fracture surfaces were investigated by a scanning electron microscope (SEM) and the morphology of the crack tip was investigated by a transmission electron microscope (TEM). It was found that the results of the creep tests performed in the non-ionic surfactant were very different from those performed in air. SEM images of the fracture surfaces showed that there were three different mechanisms of fracture and that specimens had a tendency to rupture by ESC when the stress was small. The results of the ECT tests and the TEM images showed that the change in the mechanism of the fracture was attributable to the change of morphology at the crack tip.     

Effect of conformational changes and differences of proteins on frictional properties of poly(vinyl alcohol) hydrogel

In this study, albumin or γ-globulin, both of which are included in natural synovial fluid, was used as an additive into lubricants to investigate the ability to reduce the friction for poly(vinyl alcohol) hydrogel in mixed lubrication. It was found from a measurement in circular dichroism that albumin contains a large amount of α-helix structure and γ-globulin contains a large amount of β-sheet structure. The lubricant containing only albumin showed low friction compared to the lubricant containing only γ-globulin. The effect of protein boundary film was clarified by changing lubricant. Albumin kept the friction low after changing from γ-globulin used at initial rubbing, but γ-globulin increased the friction after changing from albumin at initial rubbing. From a sliding distance of 600 m, albumin showed lower friction but γ-globulin showed higher friction. Therefore, in the case of friction decreasing, γ-globulin forms a tight adsorbed layer and subsequently albumin forms a layer with low shearing strength. Hence, it is important to apply the adsorption layer of γ-globulin at the bottom and make a layered structure composed of albumin and γ-globulin to reduce both friction and wear.