Synthesis of polymeric electrospun nanofibers for application in waterproof‐breathable fabrics

This study focuses waterproof‐breathable fabric development by applying electrospun web of polyurethane (PU), PAN, and PES directly onto the substrate fabric. Advantages of textile fabrics of elastomeric nanofibrous membranes over gortex specimen are the mass production feasibility, high elastomeric properties, more body comfort parameters, and fabric production without holes and needle traces formation. In this work, we identified the PU nanofibrous membrane as the best and useful web for application in waterproof‐breathable fabrics. Air permeability, water vapor transport rate, and resistance to water penetration average value for the prepared PU fibers web (sample of S1) were about 10 ml/s, 430 g/m²/24 h, 15 cm H₂O. To improve waterproof‐breathable characteristics of the membrane, the effects of electrospinning parameters on the fibers morphology and waterproof‐breathable characteristics were investigated. PU concentration of 12% (w/w) and electrospinning voltage of 12 kV were identified as optimal conditions to reach uniform and fine PU nanofibers formation without any beads. Air permeability, water vapor transport rate, and resistance to water penetration average value for the final sample were recorded as about 2.5 ml/s, 840 g/m²/24 h, and 44 cm H₂O, correspondingly. POLYM. ENG. SCI. 56:143–149, 2016. © 2015 Society of Plastics Engineers     

Variance‐based global sensitivity analysis for fuzzy random structural systems

There have been increasing advances in the sophisticated approaches like fuzzy randomness to handle different uncertainties in civil engineering; however, less attention has been paid to the formulation of a sensitivity analysis for fuzzy random structural systems. In this study, the main objective is to present the formulation of fuzzy Sobol sensitivity indices to quantify the influence of fuzzy random structural parameters. Meanwhile, uncertainty in derivation of limit states and acceptance criteria in collapse analysis is addressed briefly and treated using fuzzy model parameters. To show the application of the established sensitivity test, the collapse behavior of a steel moment frame subjected to sudden column removal is evaluated thoroughly. The proposed fuzzy sensitivity indices are determined for the problem and the overall influence of fuzzy acceptance criteria on the collapse assessment is shown using fragility analysis. The results show that the presented fuzzy sensitivity analysis can give detailed insight into the characteristics of fuzzy random systems, and the epistemic uncertainty in derivation of limit states can have significant effects on the reliability‐based collapse analysis. It is worth mentioning that to alleviate high computational demands in fuzzy probabilistic collapse analysis, a neural network metamodel is applied in conjunction with the genetic algorithm which is also of practical value to engineers and researchers.     

Vapor-liquid equilibrium of ethanol/ethyl acetate mixture in ultrasonic intensified environment

A vapor-liquid equilibrium (VLE) study was conducted on ethanol/ethylacetate mixture as a preliminary step towards developing an ultrasonic-assisted distillation process for separating azeotropic mixtures. The influence of ultrasonic intensity and frequency on the vapor-liquid equilibrium (VLE) of the mixture was examined using a combination of four ultrasonic intensities in range of 100–400W/cm² and three frequencies ranging from 25–68 kHz. The sonication was found to have significant impacts on the VLE of the system as it alters both the relative volatility and azeotrope point, with preference to lower frequency operation. A maximum relative volatility of 2.32 was obtained at an intensity of 300 W/cm2 and a frequency of 25 kHz coupled with complete elimination of ethanol-ethyl acetate azeotrope. Results from this work were also congruent with some experimental and theoretical works presented in the literature. These findings set a good beginning towards the development of an ultrasonic assisted distillation that is currently in progress.     

Silica aerogel/epoxy nanocomposites: Mechanical,vibrational, and morphological properties

The present study was an attempt to examine the effects that adding silica aerogel (SA) nanoparticles to epoxy would exert on its mechanical, vibrational, and morphological properties. Neat epoxy was consecutively combined with 1, 2, and 4 wt% of SA nanoparticles. A number of tests of mechanical properties were then performed on the samples, including tests of tensile, bending, compressive, dynamic mechanical thermal, hardness, and Izod impact. Vibration and water uptake tests were also conducted on the samples. The highest modulus and strength values were found in the nanocomposite sample with 4 wt% of SA, and the highest toughness and elongation values were detected in the sample with 1 wt% of SA. Furthermore, adding the SA nanoparticles to the epoxy improved the energy absorption and hardness of the epoxy matrix. The findings from the tests of dynamic mechanical thermal and vibration properties demonstrated that, with an increase in the nanoparticles content in the samples, the values of storage modulus and natural frequency increased while the values of tan δ and damping ratios decreased. A comparison between the values of natural frequency from the vibration test and the values from the Euler–Bernoulli beam theory showed a good agreement between the theoretical and experimental results.     

Bioavailability of nutraceuticals: Role of the food matrix,processing conditions,the gastrointestinal tract,and nanodelivery systems

Nowadays, many consumers prefer foods with a high content of nutraceuticals that contribute to the prevention or healing of chronic diseases. Therefore, in recent years, more and more researchers have studied the bioefficiency, safety, and toxicity of nutraceutical‐enriched foods. The key stage of nutraceutical bioefficiency is oral bioavailability, which involves the following processes: the release of nutraceuticals from food matrices or nanocarriers in gastrointestinal fluids, the solubilization of nutraceuticals and their interaction with other components of gastrointestinal fluids, the absorption of nutraceuticals by the epithelial layer, and the chemical and biochemical transformations into epithelial cells. These processes are endogenous factors that greatly influence the bioavailability of nutraceuticals. In addition to endogenous factors, the bioavailability of nutraceuticals is also affected by exogenous factors, such as: physicochemical properties of nutraceuticals, food matrix, food processing and storage, and so forth. Both the endogenous and exogenous factors are comprehensively analyzed in this review. Thus, the physicochemical and enzymatic processes involved in food digestion are described, highlighting the role of each stage of gastrointestinal tract (mouth, stomach, and intestine) in nutraceuticals bioaccessibility. The structure and functions of the mucus and epithelial layers, the mechanisms involved in the active and passive transport of nutraceuticals through the cell membrane, and phase I and phase II metabolism reactions are also discussed. Finally, this review focuses on several types of bioactive‐loaded nanocarriers such as lipid‐based, surfactant‐based, and biopolymeric nanocarriers that improve the bioavailability of nutraceuticals.     

Comparison of chitosan–gelatin composite and bilayer coating and film effect on the quality of refrigerated rainbow trout

The effect of chitosan–gelatin coating and film on the rancidity development in rainbow trout (Oncorhynchus mykiss) fillets during refrigerated storage (4 ± 1 °C) was examined over a period of 16 days. Composite and bilayer coated and film wrapped fish samples were analysed periodically for microbiological (total viable count, psychrotrophic count) and chemical (TVB-N, POV, TBARS, FFA) characteristics. The results indicated that chitosan–gelatin coating and film retained their good quality characteristics and extend the shelf life of fish samples during refrigerated storage .The coating was better than the film in reducing lipid oxidation of fillets, but there was no significant difference between them in control of bacterial contamination.     

Antibiotic resistance of Salmonella isolated from hog, beef, and chicken carcass samples from provincially inspected abattoirs in Ontario

The emergence of antimicrobial-resistant Salmonella organisms, especially Salmonella Typhimurium DT104, has been reported in many countries, including the United States and Canada. The purposes of this study were to determine the antimicrobial resistance patterns of Salmonella isolated from hog, beef, and chicken carcasses from provincially inspected abattoirs in Ontario and to determine the agreement between the agar dilution method and the microbroth dilution method for measurement of antimicrobial resistance of the isolates. Antimicrobial resistance of Salmonella isolates from hogs (n = 71), beef (n = 24), and chicken (n = 295) to amikacin, ampicillin, cephalothin, chloramphenicol, ciprofloxacin, gentamicin, streptomycin, sulfamethoxazole, and tetracycline was determined using the two methods. None of the 390 isolates were resistant to ciprofloxacin at levels of 0.125 microg/ml. All chicken and hog isolates were sensitive to amikacin, whereas all beef isolates were sensitive to both amikacin and gentamicin. Multiple antimicrobial resistance (resistance to more than one antimicrobial) was found in 29% of bovine isolates and 42% of porcine isolates using both methods for testing and in 42% by the agar dilution and 33% by the microbroth dilution methods in the chicken isolates. Overall, there was good agreement between the two test methods for resistance to most of the antimicrobials, with disagreement found in the results in 1.3% of the isolates for ampicillin and sulfamethoxazole, 8.2% for streptomycin, 5.6% for cephalothin, and 1.0% of the isolates for tetracycline. The lack of agreement between the two test methods was found mostly among the chicken isolates.     

Thermal,mechanical, and corrosion resistance properties of vinyl ester/clay nanocomposites for the matrix of carbon fiber‐reinforced composites exposed to electron beam

Vinyl ester/clay nanocomposites with 1, 3, and 5% nanoclay contents were prepared. X‐ray diffractography patterns and Scanning Electron micrographs showed that nanocomposites with the exfoliated structure were formed. Thermogravimetric analysis, water absorption test, and Tafel polarization method, respectively, revealed the improvements in thermal resistance, water barrier properties, and corrosion resistance properties of the samples with an increase in the amount of the incorporated nanoclay. Tensile tests showed that nanoclay also enhanced the mechanical properties of the polymer, so that the tensile strength of the samples with 5% nanoclay was more than 3 times higher than tensile strength of pure vinyl ester samples. Overall, the best properties were observed for the samples containing 5% nanoclay. Pure vinyl ester and nanocomposite with 5% nanoclay content were exposed to the electron beam radiation and their mechanical properties improved up to 500 kGy irradiation dose. Finally, pure vinyl ester and vinyl ester/nanoclay (5%) matrixes were reinforced with carbon fiber and the effect of electron beam irradiation on their mechanical properties was examined. The tensile strength and the modulus of the samples initially increased after exposure to the radiation doses up to 500 kGy and then a decrease was observed as the irradiation dose rose to 1000 kGy. Moreover, nanoclay moderated the effect of the irradiation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42393.     

Thermal,mechanical, and barrier properties of polyethylene/surlyn/organoclay nanocomposites blown films prepared by different mixing methods

(Low‐density polyethylene) (LDPE)/clay nanocomposites were prepared by melt blending in a twin‐screw extruder by using different mixing methods. Zinc‐neutralized carboxylate ionomer was used as a compatibilizer. Blown films of the nanocomposites were then prepared. The effect of mixing method on the clay dispersion and properties of the nanocomposites was evaluated by wide‐angle X‐ray diffraction analysis, mechanical properties, thermal properties, and barrier properties. The structure and properties of nanocomposites containing different amounts of nanoclay prepared by selected mixing techniques were also investigated. It was found that melt compounding of Surlyn/clay masterbatch with pure LDPE and Surlyn (two‐step‐a method) results in better dispersion and intercalation of the nanofillers than melt mixing of LDPE/Surlyn/clay masterbatch with pure LDPE and surlyn (two‐step‐b method) and direct mixing of LDPE with clay. The films containing ionomer have good barrier properties. A wide‐angle X‐ray diffraction pattern indicates that intercalation of polymer chains into the clay galleries decreases by increasing the clay content. Barrier properties and tensile modulus of the films were improved by increasing the clay content. In addition, tensile strength increased in the machine direction, but it decreased in the transverse direction by increasing the clay content. DSC results showed that increasing the clay content does not show significant change in the melting and crystallization temperatures. The results of thermogravimetric analysis showed that the thermal stability of the nanocomposites decreased by increasing the clay content more than 1 wt%. J. VINYL ADDIT. TECHNOL., 21:60–69, 2015. © 2014 Society of Plastics Engineers