An integrated analysis for a coextrusion process

An integrated numerical approach is proposed to simulate the polymeric liquid flow in a bicomponent coextrusion die with a feedblock inlet system. The three-dimensional finite element method is applied to determine the fluid motion and the interfacial position of the two polymeric liquids before entering the die body, whereas the two-dimensional Hele-Shaw model is assumed to be applicable for fluid flow in the manifold and the slot section of the die body. An optimal design procedure is incorporated into the simulation and the dimensions of the manifold can be properly selected such that the die can deliver the composite liquid film with acceptable uniformity. A specially designed choker bar can also be inserted to reduce the flow non-uniformities caused by production variations. The contraction of the composite liquid film emanating from the die exit is also predicted under different draw ratios.     

Modification of wheat gluten with citric acid to produce superabsorbent materials

Wheat gluten was reacted with citric acid to produce natural superabsorbent materials able to absorb up to 78 times its weight in water. The properties of the modified gluten samples were characterized using Fourier Transform Infra‐red (FTIR) spectroscopy, thermogravimetric analysis, and water uptake. The reaction between gluten and citric acid was examined for gluten : citric acid ratios of 0.38 : 1 to 0.75 : 1 at temperatures from 100 to 130°C. More citric acid reacted for samples containing higher citric acid concentrations and at higher temperatures. FTIR analyses indicated the presence of carboxylate groups on the modified gluten samples, which resulted in modified samples having higher water uptake values than neat gluten. The sample with a gluten:citric acid ratio of 0.5 : 1 and reaction temperature of 120°C had the largest water uptake value. Also, all modified gluten samples had lower thermal stability than neat gluten. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Induced Pluripotent Stem Cell-Derived Conditioned Medium Promotes Endogenous Leukemia Inhibitory Factor to Attenuate Endotoxin-Induced Acute Lung Injury

The conditioned medium of induced pluripotent stem cells (iPSC-CM) can attenuate neutrophil recruitment and endothelial leakage of lipopolysaccharide (LPS)-induced acute lung injury (ALI). Therefore, we investigated the mechanisms by which iPSC-CM regulate the interaction between neutrophils and the endothelium in ALI. Murine iPSCs (miPSCs) were delivered intravenously to male C57BL/6 mice (8–12 weeks old) 4 h after intratracheal LPS injection. A miPSC-derived conditioned medium (miPSC-CM) was delivered intravenously to mice after intratracheal LPS injection. DMSO-induced HL-60 cells (D-HL-60, neutrophil-like cells) and human umbilical vein endothelial cells (HUVECs) were used as in vitro models to assess the interaction of neutrophils and endothelial cells. miPSC-CM diminished the histopathological changes in the lungs and the neutrophil count in bronchoalveolar lavage fluids of ALI mice. miPSC-CM attenuated the expression of adhesion molecules in the lungs of ALI mice. Human iPSC conditioned medium (hiPSC-CM) reduced the expression of adhesion molecules in a HUVEC and D-HL-60 co-culture after LPS stimulation, which decreased the transendothelial migration (TEM) of D-HL-60. A human angiogenesis factors protein array revealed that leukemia inhibitory factor (LIF) was not detected in the absence of D-HL-60 and hiPSC-CM groups. hiPSC-CM significantly promoted the production of endogenous LIF in in vitro models. Administration of an anti-LIF antibody not only reversed the effect of iPSC-CM in ALI mice, but also blocked the effect of iPSC-CM on neutrophils TEM in in vitro models. However, a controlled IgG had no such effect. Our study demonstrated that iPSC-CM promoted endogenous LIF to inhibit neutrophils TEM and attenuate the severity of sepsis-induced ALI.     

Alloy ratio effect of Pd/Pt nanoparticles on carbon nanotubes for catalysing methanol-tolerant oxygen reduction

Pd₁Pt₃, Pd₁Pt₁, and Pd₃Pt₁ nanoparticles supported on multi-wall carbon nanotubes (CNTs) were prepared by the self-regulation reduction of sodium n-dodecyl sulphate and used as catalysts in oxygen reduction reactions (ORRs). The crystal properties of these alloy nanoparticles on the CNT were measured by X-ray diffraction spectroscopy (XRD) and high-resolution transmission electron microscopy (HRTEM). The angle shifting of the XRD peak and the lattice spacing of the nanoparticles measured by HRTEM increased with an increase in Pd amount, indicating a regulable Pd-Pt ratio for the alloy nanoparticle composition. Rotating ring-disk electrode (RRDE) measurements indicate that the number of electrons catalysed by the Pd₁Pt₃/CNT, Pd₁Pt₁/CNT, and Pd₃Pt₁/CNT nanocatalysts in the ORRs were 3.98, 3.97, and 3.93, respectively. These results show that these ORRs occur via a 4-electron pathway. Linearly scanned voltammetry in the electrolyte with methanol revealed that Pd₃Pt₁/CNT has high methanol tolerance during ORRs.     

Water absorbance and thermal properties of sulfated wheat gluten films

Wheat gluten films of various thicknesses formed at 30–70°C were treated with cold sulfuric acid to produce sulfated gluten films. Chemical, thermal, thermal stability, and water uptake properties were characterized for neat and sulfated films. The sulfated gluten films were able to absorb up to 30 times their weight in deionized water. However, this value dropped to 3.5 when the film was soaked in a 0.9% (w/w) NaCl solution. The films were also soaked 4 times in deionized water, and each soaking resulted in a reduced water uptake capacity. The temperature of film formation had no effect on the final water uptake properties. Also, thinner films had higher concentrations of sulfate groups than thicker films; this resulted in higher water uptake values. In addition, sulfated gluten films had comparable glass‐transition temperatures but lower thermal stabilities than the neat gluten films. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Remote,condition-based maintenance for web-enabled robotic system

The current trends in industry include an integration of information and knowledge-base network with a manufacturing system, which coined a new term, e-manufacturing. From the perspective of e-manufacturing any production equipment and its control functions do not exist alone, instead becoming a part of the holistic operation system with distant monitoring, remote quality control, and fault diagnostic capabilities. The key to this new paradigm is the accessibility to a remotely located system and having the means of responding to a changing environment, which is better suited for today's rapidly changing environment. Within the framework of the web-enabled robotic system, this paper focuses on the remote maintenance schemes with an emphasis on condition-based maintenance strategies. Real-time monitoring of robot harmonic drive systems and operational status have been attained over the Web. A mathematical modeling of system availability has been derived in order to account for other failures that might occur in the subsystems of the robot. Compared to the schedule-based maintenance strategies, the proposed approach shows great potential for improving overall production efficiency, while reducing the cost of maintenance.     

Analysis of the dielectric characteristics for polycrystalline Ba0.65Sr0.35TiO3 (II) – d.c. field dependence with a modified bias equation

The effect of direct-current (d.c.) biasing on the dielectric properties of Ba_0.65Sr_0.35TiO₃ (BST) with various grain sizes (0.87 μm to 5.43 μm) have been studied in the paraelectric state. The leakage current of BST samples is proportional to the biasing field. Specimens with larger grains exhibit higher leakage current under biasing. The bias equation used in the literature to predict the d.c. field dependence of permittivity is modified by introducing a bias exponent parameter β. This modified bias equation gives a better fit to the experimental results both in this study and in the literature. Similar trends of α (representing the distribution of relaxation times), β, and the variance of lattice distortion with grain sizes suggests that β is a material parameter. It is concluded that the temperature dependence, the frequency response and d.c. field effect for the dielectric characteristics of Ba_0.65Sr_0.35TiO₃ are all suppressed by the transition broadening.     

Scrapping small lots in a low-yield and high-price scenario

Some wafers in a lot may become spoiled after they are processed at a workstation; such a lot is called a small lot. In a low yield and high price scenario, scrapping small lots may increase revenue and profit; yet, this notion has seldom been examined. This study presents a model for formulating the decision-making problem of scrapping small lots. A genetic algorithm is used to solve the problem when the solution space is large. An exhaustive search method is used when the solution space is small. Some numerical examples are used to evaluate the outcome of scrapping small lots. The profit obtained by the proposed scrapping method may be up to 23% higher than that obtained without scrapping.