Economic‐Statistical Design of Acceptance Control Chart

Acceptance control charts are effective tools to monitor capable processes in which the fraction of the produced nonconforming items is very low. In these charts, some controlled changes in the process mean are allowed, and the production of a specified number of defectives is tolerated. Designing these acceptance control charts by considering the cost of sampling, detecting, and investigating out‐of‐control signals as well as the probable correction of assignable cause(s) can result in economic advantages. Moreover, the statistical properties of the control charts can be satisfied. In this article, an economic‐statistical model is developed to design acceptance control charts. An illustrative example is used to compare the results of economic versus economic‐statistical design of the acceptance control charts. In addition, a comprehensive sensitivity analysis is conducted on the basis of the parameters of the model. Copyright © 2012 John Wiley & Sons, Ltd.     

Silver recovery from radiographic film processing effluents by hydrogen peroxide: Modeling and optimization using response surface methodology

The recovery of silver from X-ray film processing effluents by precipitation using hydrogen peroxide as the precipitating agent was studied. Response surface methodology (RSM) and central composite design (CCD) were applied to achieve optimum conditions. Linear, square and interactions effects between parameters to study of a second order polynomial equation were obtained. Optimum condition included the volume of H₂O₂ 0.8 ml/min, pH=5.5, ethylene glycol 9 ml in the experimental condition. In these conditions silver recovery percentage was predicted as 92.8%. The experiment was conducted in triplicate under optimized conditions. Silver recovery percentage and average of precipitate were obtained as 91.5% and 423.19mg, respectively, which were close to the predicted amount achieved by the model.     

Preparation and Characterization of CaO/MgO Catalyst and Its Application for Transesterification of n-Butyl Acetate with Methanol

This work reports the synthesis and characterization of CaO/MgO mixed oxide with different CaO/MgO mass ratios prepared by the co-precipitation method in a basic medium and subsequent calcination of the precursors. These mixed-oxide materials were characterized by XRD, FT-IR, SEM, and BET. The alkalinity of samples was determined by CO₂ temperature-programmed desorption (CO₂-TPD). Results show that the CaO/MgO samples contained mixed crystalline phases of cubic CaO and hexagonal MgO species. Decreasing the CaO/MgO ratio resulted in low average pore diameter and enhanced BET surface area.

Transesterification of n-butyl acetate with methanol was studied using a CaO/MgO catalyst at atmospheric pressure and 95°C, a model reaction to evaluate the potential of these catalysts for biodiesel production. The highest activity was found for a CaO/MgO mass ratio of 8:2 with conversion percentage of 83. The effects of calcination temperature, reaction time, reaction temperature, methanol/n-butyl acetate molar ratio, and catalyst recycling were investigated.     

Optimization of L-Asparaginase Immobilization onto Calcium Alginate Beads

In this study, anti-leukemic enzyme L-asparaginase (E.C.3.5.1.1) from Escherichia coli ATCC 11303 was modified by the microencapsulation technique onto calcium alginate beads. Using response surface methodology (RSM), a three-level full factorial design, the values of concentration of sodium alginate, concentration of calcium chloride, and enzyme loading were investigated to obtain the highest residual L-asparaginase (L-ASNase) activity % (immobilized enzyme activity/free enzyme activity). The effects of the studied factors on immobilization were evaluated The predicted values by the model were close to the experimental values, indicating suitability of the model. The results presented that an increase in sodium alginate concentration increased the percent of residual activity of L-ASNase at any given calcium chloride concentration and the moderate amount of enzyme loading increased the percent residual activity. The optimal immobilization conditions were as follows: sodium alginate 1.98% (w/v), calcium chloride concentration 3.70% (w/v), and enzyme load 46.91% (v/v). The highest residual L-ASNase activity % obtained was 34.49%.     

Preparation and Characterization of Polyvinylpyrrolidone/ Magnetite Decorated Carboxylic Acid Functionalized Multi-walled Carbon Nanotube (PVP/MWCNT-Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>) Nanocomposite

Magnetite decorated carboxylic acid functionalized multi-walled carbon nanotube (MWCNT-Fe₃O₄) was successfully inserted in polyvinylpyrrolidone (PVP) matrix in the aqueous media, as a result of which magnetic polymer nanocomposite (PVP/MWCNT-Fe₃O₄) was formed. With application of SEM, the surface morphology of the produced PVP/MWCNT-Fe₃O₄ nanocomposite was compared with that of pure PVP. The diameter distribution of Fe₃O₄ decorated carboxylic acid functionalized multi-walled carbon nanotube was determined by image analysis of the SEM micrographs. In addition, the structural and thermal characterizations of PVP/MWCNT-Fe₃O₄ nanocomposite were performed by FT-IR, XRD, TGA, and DSC techniques. Moreover, magnetic characterization of the prepared nanocomposite was determined by VSM. The obtained results indicated that addition of MWCNT-Fe₃O₄ (5% w/w) to PVP improved the thermal properties of pure polyvinylpyrrolidone. According to the results of DSC analysis, the glass transition temperature of 160?°C was observed for the PVP/MWCNT-Fe₃O₄ (5% w/w) nanocomposite. The FT-IR spectra showed that an interaction was taking place between MWCNT-Fe₃O₄ and PVP. The strong interaction with ~31 cm^?1 red shift along with good complexation of carbonyl functional group of PVP with MWCNT-Fe₃O₄ was observed for PVP/MWCNT-Fe₃O₄ (5% w/w) nanocomposite as a result of a better distribution of carbon nanotubes in the PVP matrix.     

ECG compression method based on adaptive quantization of main wavelet packet subbands

In this study, a new compression algorithm for ECG signal is proposed based on selecting important subbands of wavelet packet transform (WPT) and applying subband-dependent quantization algorithm. To this end, first WPT was applied on ECG signal and then more important subbands are selected according to their Shannon entropy. In the next step, content-based quantization and denoising method are applied to the coefficients of the selected subbands. Finally, arithmetic coding is employed to produce compressed data. The performance of the proposed compression method is evaluated using compression rate (CR), percentage root-mean-square difference (PRD) as signal distortion, and wavelet energy-based diagnostic distortion (WEDD) as diagnostic distortion measures on MIT-BIH Arrhythmia database. The average CR of the proposed method is 29.1, its average PRD is <2.9 % and WEDD is <3.2 %. These results demonstrated that the proposed method has a good performance compared to the state-of-the-art compression algorithms.     

Metal‐Organic‐Framework‐Coated Optical Fibers as Light‐Triggered Drug Delivery Vehicles

Physical delivery of anticancer drugs in controlled anatomic locations can complement the advances being made in chemo‐selective therapies. To this end, an optical fiber catheter is coated in a thin layer of metal organic framework UiO‐66 and the anticancer drug 5‐Fluorouracil (5‐FU) is deposited within the pores. Delivery of light of appropriate wavelength through the fiber catheter is found to trigger the release of 5‐FU on demand, offering a new route to localized drug administration. The system exhibits great potential with as much as 110 × 10^?6 m of 5‐FU delivered within 1 min from one fiber.     

Ultrasound-Assisted Osmotic Treatment of Model Food Impregnated with Pomegranate Peel Phenolic Compounds: Mass Transfer,Texture, and Phenolic Evaluations

Food impregnation with nutraceutical components due to the health beneficial property is of great importance for food processing industry. In this study, osmotic dehydration was used to impregnate model food with phenolics extracted from pomegranate peel. Intermittent acoustic treatment was applied to enhance mass transfer. This process was carried out at three sucrose concentrations of 40, 50, and 60% and two levels of power ultrasound, 50 and 100% in an experimental setup, which was equipped with a pump circulating osmotic solution frequently. Results showed that increase in sucrose concentration resulted in an increase in the amounts of water loss and solutes gain. Additionally, application of higher power ultrasound led to higher values of water loss and solid gain. Mass transfer modeling using Azuara model predicts water loss and solid gain values at equilibrium. Results revealed the good correlation of experimental values with the model (due to the R² values greater than 0.94). The microstructure of samples was investigated using scanning electron microscopy (SEM). Images revealed pores and cavities made by ultrasound waves as the result of spongy effects. Texture profile analysis (TPA) was applied for the determination of hardness, springiness, and gumminess of the samples. Results also showed significant effects of the sucrose concentration and ultrasound power on textural properties. Measurements of total phenolic content and antiradical activity, which were carried out by a colorimetric method and antiradical scavenging assay, EC50, respectively indicated that osmotic dehydration is a possible way for uptaking phenolic compounds of pomegranate peel presented in osmotic solution into food matrices.     

Solution combustion synthesis of FeCr2O4 powders for pigment applications: Effect of fuel type

Solution combustion synthesis of iron chromite was reported using iron(III) nitrate nonahydrate and chromium(III) nitrate nonahydrate as starting materials, as well as glycine, urea, citric acid, and ethylene glycol as fuels. The influence of fuel type on the structure, molecular, microstructure as well as chromatic properties of samples was investigated. The X-ray diffraction (XRD) patterns showed that unlike themodynamical prediction, glycine fuel led to strongest combustion and consequent highest XRD peak intensities and lower lattice parameters. Moreover, the change of fuel type and mixing of fuels affected XRD data. Fourier transform infrared analysis showed that the band position of Cr–O and Fe–O bonds were shifted to higher frequencies by using of fuels with weaker combustion reactions. In addition, scanning electron micrographs showed that different morphologies of FeCr₂O₄ particles were obtained depending on the fuel type and ratios. Energy-dispersive X-ray spectroscopy analysis of the samples showed that oxygen concentration of samples was less than that of stoichiometric ratio of FeCr₂O₄ due to local reducing atmosphere. Furthermore, chromatic properties of the powders showed that the pigment synthesized with glycine fuel has a better and lighter grayish brown color than the other ones and can be used as a suitable industrial candidate to create a brown color in the ceramic glaze.