Review on the knitted structures with auxetic effect

There are now different kinds of geometrical models for auxetic materials, such as re-entrant model, rotating model, nodule and fibril model, chiral model, liquid crystalline model, helical model and rod model for describing the angle-ply composites. Knitting technology, including plane and 3D warp knitting as well as weft knitting, is widely used in the manufacturing fields nowadays and has been adopted in fabric structure designing. Knitted fabrics with negative Poisson’s ratio have great potentials in both apparel and industries. The present article reviews the auxetic principles in general and in the specific context of knitted textile structures with auxetic potential made from conventional fibers.     

Changes in pH and water holding properties of Longissimus dorsi muscle during beef ageing

The effects of vacuum packaging, chilling rate (slow or fast), and fat cover thickness (≤ 4 mm or 7–8 mm) on pH and water-holding properties of longissimus dorsi muscle were assessed during beef ageing. The longissimus dorsi muscles were aged on the carcass or in vacuum packaging. Muscle samples were taken on days 0 (24 h post-mortem), 2, 4, 8, 12 and 16 to measure these properties. Ageing time significantly influenced muscle pH and cooking loss; however, interaction fat × chill × time affected press juice. The pH was also influenced by vacuum-packaged ageing. Press juice positively correlated with cooking loss and pH.     

Spherical Rhabdophane Sols. I: Rheology and Particle Morphology

The particle morphology, weight loss, and rheology of rhabdophane (LaPO₄· n H₂O) sols with either spherical or rod-shaped particles were characterized and compared. Some spherical particle sols were doped with aluminum. Particle size was characterized by light scattering and transmission electron microscopy (TEM). The additives that promote spherical particle formation also cause greater high temperature weight loss than similar rod-shaped particle sols. As expected, the shear-rate dependence of sol viscosity was much weaker for spherical particle sols. The viscosity for sols with both types of particles was modeled using particle aspect ratios and bound water layer thicknesses as variables. A bound water layer thickness of 3–5 nm was suggested by modeling, except in aluminum-doped sols, where a much larger thickness was suggested. Modeled aspect ratios were larger than those observed by TEM. Weakly bound agglomerates may be present in both types of sols.     

The Investigation of E-Learning System Design Quality on Usage Intention

ABSTRACT

A well-designed product increases customer value and leads to repeat usage. However, studies on the impact of website quality on customer usage fail to distinguish website competence from website capability, ignoring that website quality performance has impacts on other website quality attributes. We gather data from 314 undergraduate students and apply partial least square method to examine the design quality mechanisms and other factors that influence users’ experience. Our results indicate that offering personalized products or services is an important enabler toward enhancing users’ attitude and usage intention. Particularly, for IS education in the format of e-learning, our results suggest firms developing textbook technology platforms primarily focus on creating superior quality designs leading to capabilities that enhance user customization. The customization experience will lead to better satisfaction via both perceived usefulness and perceived ease-of-use.     

Photocatalytic degradation of N-nitrosodiethylamine from carbon capture plants using tungsten trioxide-based catalysts: Parametric and optimization study

This study reports the synthesis and characterization of tungsten trioxide-based catalysts for the photocatalytic degradation of N-nitrosodiethylamine (NDEA) in wastewater. Tungsten trioxide (WO₃) was synthesized using the thermal treatment method (TTM) and hard template replication method (HTRM) and impregnated with lanthanum (La), iron (Fe), chromium (Cr), and silver (Ag) to enhance its light absorption ability. The synthesized catalysts were characterized using various techniques, including UV-Vis spectroscopy, Brunauer–Emmett–Teller (BET), Barrett–Joyner surface area and porosity, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The experimental design approach used a response surface methodology (RSM) with a face-centered central composite design (FCCCD) technique. Catalyst loading (%), pH of solution, and catalyst concentration (g/L) were chosen as design factors, with the response variable being NDEA degradation efficiency (%). The obtained data were analyzed, and a quadratic model was chosen as the best fit with statistically significant model terms as observed from the analysis of variance (ANOVA). 3D interaction plots were generated to explain the effect of the various interaction terms of the quadratic model. The results showed that the pH of the solution was the major factor affecting NDEA degradation efficiency. The mean degradation efficiency of NDEA was 93.03% for Fe/WO₃, 88.90% for Ag/WO₃, 86.48% for La/WO₃, and 84.03% for Cr/WO₃. These findings demonstrate the potential of tungsten trioxide-based catalysts impregnated with various metals for the effective treatment of NDEA in wastewater through heterogeneous photocatalysis.     

Continuous Coating of Oxide Fiber Tows Using Liquid Precursors: Monazite Coatings on Nextel 720™

Seven different aqueous or ethanolic precursors were used to continuously coat monazite (LaPO₄) on Nextel 720™ fiber tows. Immiscible liquid displacement was used to minimize bridging of coating between filaments. Precursor viscosities, densities, and concentrations were measured, and solids were characterized by DTA/TGA and X-ray. Coatings were cured in-line at 1200°-1400°C and characterized for thickness, microstructure, and composition by optical microscopy, SEM, and TEM. Tensile strengths of the coated fibers varied with the precursor used and were 25% to >50% lower than those of the as-received fiber. The coating stoichiometry and coating thickness of a particular precursor did not correlate with tensile strength. Median coating thicknesses were typically ∼50–100 nm for precursors with 40–80 g/L monazite, much larger than thicknesses predicted by theory for 12 mm diameter monofilaments. There were significant thickness variations from filament to filament, but usually little variation in composition or microstructure. Amorphous AlPO₄ layers formed from phosphate-rich precursors. Factors that could affect coating characteristics and tensile strength reduction were discussed.     

In situ Y2Si2O7 coatings on Hi-Nicalon-S SiC fibers: Phase formation and fiber strength

Y₂Si₂O₇ coatings were formed on Hi-Nicalon-S SiC fibers by reaction of solution-derived YPO₄ coatings with glass SiO₂ scales formed by fiber oxidation. Two oxidation methods were used: pre-oxidation, where fibers were oxidized prior to YPO₄ coating, or post-oxidation, where fibers were first coated with YPO₄ and then oxidized. Fibers with YPO₄/SiO₂ films were heat-treated in argon at 1200°C for 20 hours to react YPO₄ and SiO₂ to Y₂Si₂O₇. The effects of SiO₂ to YPO₄ film thicknesses on fiber strength and on the Y₂Si₂O₇formation kinetics were investigated. An optimized process to obtain single-phase continuous Y₂Si₂O₇ coatings on Hi-Nicalon-S fibers with low loss in fiber strength is suggested.     

Evolution of Texture in Rhabdophane-Derived Monazite Coatings

Microstructure and texture development of fiber coatings of rhabdophane-sol-derived monazite was studied. As-deposited textures and orientation relationships during phase transformations were determined by TEM. Monazite coatings had a crystallographic texture relict from that of as-deposited rhabdophane, with layers of rod-shaped particles that changed orientation by 90° across layers. Heat treatment at 1200°C of minicomposites with these coated fibers caused considerable monazite grain coarsening, and disappearance of the texture.     

Spherical Rhabdophane Sols. II: Fiber Coating

A rhabdophane (LaPO₄·nH₂O) sol with fine spherical particles was used to coat Nextel™ 720 fiber tows continuously with monazite (LaPO₄). The coatings are compared with those made previously from rod-shaped particles. The coated fibers were heat-treated at 1000°–1300°C for 1, 10, and 100 h. The effect of heat treatment temperature and time on coating microstructure was characterized by scanning electron microscopy and transmission electron microscopy, and the strengths of the coated fibers were measured after coating and heat treatment. Grain shapes and grain growth rates were measured. Coating thickness uniformity was quantified by a fit to a truncated extreme-value distribution. Coating hermeticity was evaluated by analysis of grain growth rates. The spherical particles promote more rapid coating densification and local hermeticity, but introduce problems with sintering shrinkage cracking that are not present in coatings derived from rod-shaped particles.