Case Study: Color Control in the Automotive Industry

Numerous manufacturers are concerned with ensuring the homogeneity in the colors of different parts that compose their products. This quality objective of primary importance is especially challenging when the parts are sourced by different suppliers. The technical difficulties are accentuated when metallic or pearly paints are used since the presence of metallic chips in the paint causes a variation in the color according to the angle of observation. Also, the development of metametric colors increases these difficulties even more, as these colors are sensitive to different illumination sources. The present study relates to the production of colored car bumpers. By using a spectrocolorimeter and color samples, the process is improved to better respect the customer specifications. To achieve this, critical colors and significant parameters affecting colors are identified, design of experiments is used to optimize the process settings, and a correlation study allows further process improvement. The results achieved are impressive: the quality index used has been improved by 67% in only 6 months. This case study therefore illustrates how simple quality tools can be used in a rigorous search for process improvement toward total color mastering with zero defect objective.     

Aquaporin 1 Facilitated Hepatocellular Carcinoma SMMC7221 Cell Migration Associated with Water Permeability

The authors investigated the regulation of human aquaporin 1(hAQP1)and the involvement of aquaporin1(AQP1)in the migration of human hepatocellular carcinoma SMMC-7221 cells using RNA intereference technology.Firstly,two short hairpin RNA(shRNA)constructs in PBSU6 vector were reconstructed and their knockdown effects were identified in SMMC-7221 cells.Next,the involvement of endogenous hAQP1 in regulating the migration of SMMC-7221 cells was investigated via siRNA technology.HAQP1-shRNA can specifically inhibit AQP1 dependent osmotic water permeability.Meanwhile the migration of SMMC-7221 cells was inhibited remarkably after silencing AQP1 by performing transwell cell migration assay and in vitro wound healing assay.Furthermore,in the presence of an inhibitor HgCl2,the water permeability of the cell membrane was remarkably decreased,the expression of AQP1was upregulated after HgCl2 treatment and the cell movement was decreased at the moment.Increased AQP1 cannot attenuate cell migration ability when cell membrane loses its water permeability function.This demonstrates that the cell migration was remarkably related to the transporting water function of cell membrane.     

Stabilization of switched affine systems with disturbed state‐dependent switching laws

In this paper, we investigate the stabilization problem for a class of switched affine systems with a state‐dependent switching law. Since the states measurements are in general subject to perturbations and noises, we propose a robust switching‐law design method. Qualitative conditions for the stability of the closed‐loop switched system are given. Stability conditions are also formulated as Linear Matrix Inequalities (LMIs) to allow numerical implementations. Results are illustrated by numerical examples to show the efficiency of the method and its limits.     

Invertibility of a special class of mean filter operators

This paper presents a proof of the fact that if the (circulant) von Neumann mean filter operator is defined on a square coordinate set with iem rows and iem columns, then it fails to be invertible only if either the integer 5 divides iem or the integer 6 divides iem. This result answers a question posed by P. Gader, who proved that the usual 3×3 mean filter operator is invertible if and only if 3 does not divide iem.     

Synergistic effect of talc/calcined kaolin binary fillers on rigid PVC: Improved properties of PVC composites

This study aims to develop poly(vinyl chloride) (PVC) composites prepared by melt mixing by using a combination of talc and calcined kaolin as filler in order to improve the disadvantages of rigid PVC, which is widely used in industry, such as poor mechanical properties and low thermal stability. In addition, PVC/talc and PVC/calcined kaolin composites were also examined for comparison. The calcined kaolin is modified with urea to increase the surface area (chemical treatment), while the surface of both fillers is coated with stearic acid for good compatibility with PVC (mechanical treatment). Scanning electron microscopy micrographs showed homogeneous distribution of mechanically processed fillers. Attenuated total reflectance–Fourier-transform infrared spectroscopy analysis revealed successful coating of the fillers with stearic acid. Also, new bands were detected in the spectrum of urea-treated calcined kaolin, showing an effective chemical treatment. It has been observed that the treatment of fillers improves the mechanical properties of PVC. Thermogravimetric results showed that delaminated calcined kaolin increased the thermal stability of PVC composites. The results of this study proved that binary filler composites combine good properties of both (synergistic effect) and good filler dispersion can be obtained by using stearic acid and urea.     

Effect of Au ions on structural,optical, magnetic,dielectric, and antibacterial properties of TiO2 dip-coated thin films

Physical properties of the TiO₂ and Au-doped TiO₂ films fabricated by sol–gel dip-coating route are investigated. The diffraction peaks of XRD spectra confirmed the formation of anatase phase. Crystallite size was found to be decreased by increasing dopant concentration from 12.02 to 10.10 nm. All the thin films annealed in air exhibit significant room-temperature ferromagnetism displaying anatase phase that can be employed in spintronic devices. The saturation magnetization increases from 6.8 to 10.35 emu/cm³ with the increase in Au concentration. The coercivity values vary between 360.82 and 478.515 Oe and remnant magnetization ranges between 0.46 and 0.71 emu/cm³. Dielectric parameters obeyed Maxwell-Wagner model and Koop’s theory and were explained by hopping mechanism. Small values of dielectric constant made them favorable for high-frequency devices. The band gaps of the undoped and Au-doped TiO₂ thin films is in the range 3.5 to 3.38 eV, which are lesser than those of reported pure TiO₂ (3.7 eV) that is favorable for enhancing solar cells efficiency. Au-doped TiO₂ leads to an optimum antimicrobial agent. The photocatalysts having 5 wt% Au exhibit the highest photoactivities. The degradation of methylene blue under sunlight made them promising materials for water treatment.

     

Review on polyphosphazenes-based materials for bone and skeleton tissue engineering

The skeleton performs motley of functions. Defected bones and metameric loss of bone are often resulted due to innate abnormalities and accidental injuries. An assessment is made on the diversity of chemistry of phosphazene with an inflection on new developments and their importance in tissue engineering. Tissue engineering mostly uses polymers that can biodegrade in porous/permeable scaffolds form for treating damaged tissues and skeleton. Demand of these polymers is increasing as timely substrates for tissue regeneration in contrast to the mostly used polyethylene terephalate, polyorthoesters, and poly(α-amino acids). Polyphosphazenes as biodegradable polymers have great potential for applications of tissue engineering. Due to biodegradability of P–N backbone, vast diversity of structure and high functional density polyphosphazenes provides many advantages for the formation of biologically compatible macromolecules. However, the nature of the side group determines the degradation ability of such polymers. These biodegradable polymers (polyphosphazenes) provide harmless and pH neutral substances because phosphates and ammonia have high buffer capacity. This review article focuses on the biocompatible polyphosphazenes and their utilization as regeneration of tissues, skeleton, and bones with a particular focus on materials that contains only polyphosphazenes, blends of polyphosphazene, and composites made from polyphosphazene.     

Dependence on the Chromium Content of the High-Temperature Oxidation Behavior of Ta-Rich Nickel-Based Cast Alloys

The high-temperature stability of primary tantalum carbides is a problem of importance for chromium-rich cast alloys, based on cobalt or nickel. The focus of this study was nickel-based alloys, as these alloys are particularly sensitive to a lack of TaC in the as-cast state and by dissolution due to high-temperature exposure. In this work, a possible way for promoting the formation of many TaC precipitates by changing from the usual 30 wt% chromium content was investigated. Five alloys with Cr content varying from 10 to 50 wt% were prepared and then subjected to microstructure characterization and to oxidation tests. In contrast with what was expected, decreasing the Cr content in comparison with the Ni–30Cr–0.4C–6Ta reference alloy did not succeed in obtaining more TaC precipitates, but instead had the opposite effect. Concerning the high-temperature oxidation behavior at 1127 and 1237 °C, loss of resistance was observed only for a Cr content at the lower level of 10 wt%. It was noticed that a subscale CrTaO₄ developed during oxidation and seemed to promote oxide spallation during cooling.     

Three dimensional study for evaluating of air flow movements and thermal comfort in a model room: Experimental validation

This paper presents the results of a three dimensional study for evaluating the temperature profiles and air flow movement in a model room with a numerical model based on the Euler equations. Numerical results obtained for two scenarios of ventilation and air conditioning are compared with the predictions of a Navier-Stokes model. These numerical results are validated by experimental results measured in the model room. A comparison of the local thermal comfort indices PMV and PPD obtained experimentally and numerically is also presented. Results show that the Euler model is able to predict adequately total thermal comfort in the model room. Furthermore, the use of Euler equations allows a reduction of computational time in the order of 50% compared to the Navier-Stokes modeling.