Test/retest and inter‐test agreement of color aptitude measures

The color discrimination capacity of color vision normal observers can be assessed using color aptitude tests (CATs), although data on the test/retest reliability and inter‐test agreement of such tests using appropriate statistical measures is limited. In this study, 32 color vision normal observers twice performed each of five CATs, being the Farnsworth‐Munsell 100 hue test, HVC Color Vision Skills Test, inter‐Society Color Council Color Aptitude Test, the Nagel Anomaloscope (Nagel), and a custom designed two‐color discrimination test. Two methods of determining the Nagel matching range were used based on the initially accepted matching range or on repeated measures. The test/retest performance of each test was determined using the method outlined by Bland and Altman[Lancet 1986;1:307–310] and the inter‐test agreement was analyzed using the same method, after converting test scores into z score units. No test was found to have a significant systematic alteration in test performance between test and retest. Test/retest performance was generally poor, indicating that tests can only reliably classify observers into very broad performance bands. All tests failed to show inter‐test agreement, and our data indicate a primary reason for this: as test/retest performance is generally poor, inter‐test agreement must also be poor as no test can agree more with another test than it agrees with itself. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 224–231, 2015     

On‐line multivariate optimization of injection molding

An auxiliary process controller was designed, implemented, and validated for on‐line process and quality optimization. The objective function included terms related to the process variation, model uncertainty, and control energy. The controller architecture relied on characterized models including both process transfer functions and principal components analysis to perform on‐line optimization in parallel with the physical molding process. New process and quality observations were input to the controller to update the models and provided new settings for the machine controller. Experimentation included characterization with a D‐optimal design of experiments followed by a validation to measure the controller's performance with respect to controller stability, extrinsic material variation, cycle time reduction, and other common manufacturing goals. In every case, the controller was able to reduce the value of the objective function while also improving the part dimensions relative to tight tolerance specifications. While characterization experiments could be costly, the use of the resulting process models greatly speeds convergence and facilitates the consideration of various cost and quality terms in the objective function. POLYM. ENG. SCI., 55:2743–2750, 2015. © 2015 Society of Plastics Engineers     

Synthesis and functionalization of nanoengineered materials using click chemistry

The synthesis of nanoengineered materials with precise control over material composition, architecture and functionality is integral to advances in diverse fields, including biomedicine. Over the last 10 years, click chemistry has emerged as a prominent and versatile approach to engineer materials with specific properties. Herein, we highlight the application of click chemistry for the synthesis of nanoengineered materials, ranging from ultrathin films to delivery systems such as polymersomes, dendrimers and capsules. In addition, we discuss the use of click chemistry for functionalizing such materials, focusing on modifications aimed at biomedical applications.     

Electrochemical mass transfer measurements in a Y‐bifurcation model

A novel technique was used to fabricate nickel flow models of a straight pipe and a Y‐bifurcation. These were used to obtain integral mass transfer coefficients by the electrochemical technique. For the straight pipe, good agreement was obtained with previously reported mass transfer correlations. The use of an upstream anode in addition to the downstream anode led to higher mass transfer at the cathode with laminar flow because of the additional near‐wall ions produced by the upstream anode. With increasing Schmidt number, the effect of transition from laminar to turbulent flow on mass transfer was delayed to progressively higher Reynolds numbers because of the reduced mass transfer boundary layer thickness relative to the viscous sublayer. With the Y‐bifurcation, possible flow separation and the formation of a new mass transfer boundary layer in the daughter branches significantly influence the mass transfer behaviour.     

Spray deposited fluoropolymer/multi-walled carbon nanotube composite films with high dielectric permittivity at low percolation threshold

High performance perfluoro alkoxy (PFA) and chemical vapor deposition-grown multi-walled carbon nanotube (MWCNT) composite films with thicknesses of 30 μm were prepared using a scalable spray deposition technique. A homogeneous distribution of MWCNTs within the PFA matrix was confirmed by electron and optical microscopy. Dielectric and AC conductivity measurements showed a significant enhancement of dielectric permittivity for PFA/MWCNT films at low frequencies, and a very weak dependence of dielectric permittivity on temperature in the range 25-230 °C. Very low percolation threshold volume fractions of ca. 0.0043 and 0.0017 were attained for MWCNTs with two different aspect ratios, which have been explained by an inherent feature of spray route, a microcapacitor model and percolation theory. The combination of PFA/MWCNT composites and the spray deposition route provides a promising approach for the fabrication of industrial scale composite films with well-controlled dielectric properties for micro-electronic and high temperature applications.     

The Composition of Crude Corn Oil Recovered after Fermentation via Centrifugation from a Commercial Dry Grind Ethanol Process

A study was conducted to examine the chemical composition of corn oil obtained after fermentation of corn to make fuel ethanol via centrifugation and compare its composition to that of corn germ oil (commercial corn oil) and experimental corn oils. The levels of free fatty acids in the post fermentation corn oil were high (11–16%), as previously reported. The levels of free phytosterols and hydroxycinnamate steryl esters (similar to oryzanol in rice bran oil) were higher than those of corn germ oil and were comparable to those of ethanol-extracted corn kernel oil. The levels of tocopherols were lower in post-fermentation oil than in either corn germ oil or ethanol extracted corn kernel oil. The levels of lutein and zeaxanthin in post-fermentation were much higher than those in corn germ oil and were comparable to those in ethanol-extracted corn kernel oil. Overall, exposure to all upstream processes of a fuel ethanol plant, including high-temperature liquefaction, saccharification and fermentation appeared to have the most notable effect on tocopherols, but it had little effect on the levels of free phytosterols, hydroxycinnamate steryl esters, lutein and zeaxanthin. It may be desirable to recover these valuable functional lipids prior to using the post-fermentation corn oil for industrial applications such as making biodiesel if a cost-effective recovery process can be developed.     

A comparison of seven filling to packing switchover methods for injection molding

The effectiveness of seven methods for controlling switchover from the filling to packing stage were investigated, including: (1) screw position, (2) injection time, (3) machine pressure, (4) nozzle pressure, (5) runner pressure near the sprue, (6) cavity pressure near the gate, and (7) cavity temperature at the end of flow. The activation threshold for each of the seven switchover methods was iteratively determined so as to produce similar part weights relative to a standard process. A design of experiments was implemented for each of the seven switchover methods that perturbs the process settings by an amount equal to six standard deviations of the standard process so as to replicate the expected long‐term process variation. The results suggest that conventional switchover methods (e.g., screw position) had lower short‐term variation, but other methods were more robust with respect to rejecting long‐term process variation. The merits of different dimensional measurements for quality control are also discussed relative to the society of the plastics industry (SPI) standard tolerances. POLYM. ENG. SCI., 50:2031–2043, 2010. © 2010 Society of Plastics Engineers     

Nanomechanical characterization of Sn–Ag–Cu/Cu joints—Part 2: Nanoindentation creep and its relationship with uniaxial creep as a function of temperature

In the first part of this study we reported the use of nanoindentation to evaluate the mechanical properties of microphases formed within Sn–Ag–Cu-based solder joints as a function of temperature. In this second part, the use of nanoindentation has been extended to study the creep behaviour of these phases in the temperature range 25–175 °C. The data for nanoindentation creep has been compared with that reported for bulk creep behaviour of similar alloys. A methodology has been developed based on finite-element analysis that accounts for (i) the increasing volume of creeping material beneath the indenter as indentation progresses; and (ii) the variation of indentation stress during indentation as the area of indentation increases. Using this approach, nanoindentation creep data is reconciled with bulk creep data.     

Interfacial tension and the behavior of microemulsions and macroemulsions of water and carbon dioxide with a branched hydrocarbon nonionic surfactant

Measurements of interfacial tensions for 2-ethyl-hexanol-(propylene oxide)∼_4.5-(ethylene oxide)∼₈ (2EH-PO_4.5-EO₈) at the planar water-CO₂ interface and the surfactant distribution coefficient are utilized to explain microemulsion and macroemulsion phase behavior from 24 to 60 °C and 6.9 to 27.6 MPa. A CO₂ captive bubble technique has been developed to measure the interfacial tension γ at a known surfactant concentration in the aqueous phase, with rapid equilibration at the water-CO₂ interface. The surface pressure (γ_o − γ) decreases modestly with density at constant temperature as CO₂ solvates the surfactant tails more effectively, but changes little with temperature at constant density. The area per surfactant at the CO₂-water interface determined from the Gibbs adsorption equation decreases from 250 A²/molecule at 24 °C and 6.9 MPa, to 200 A²/molecule at 27.6 MPa. It was approximately twofold larger than that at the water-air interface, given the much smaller γ_o driving force for surfactant adsorption. For systems with added NaCl, γ decreases with salinity at low CO₂ densities as the surfactant partitions from water towards the W-C interface. At high densities, salt drives the surfactant from the W-C interface to CO₂ and raises γ. Compared with most hydrocarbon surfactants, this dual tail surfactant is unusually CO₂-philic in that it partitions primarily into the CO₂ phase versus the water phase at CO₂ densities above 0.8 g/ml, and produces γ values below 1 mN/m. With this small γ, a middle phase microemulsion and a C/W microemulsion were formed at low temperatures and high CO₂ densities, whereas macroemulsions were formed at other conditions.