Buyers' trust and mistrust in e-commerce platforms: a synthesizing literature review

Information Systems and e-Business Management - Electronic markets have grown substantially, and they are considered an effective form of retail in recent years. Despite such growth, lack of...     

Optimisation of experimental conditions for binding of divalent iron to bioactive casein phosphopeptides

Casein phosphopeptides (CPPs) are mineral‐binding bioactive peptides derived from enzymatic digestion of casein. They have been shown to increase iron bioavailability due to increasing iron solubility at the alkaline pH of the intestine. Thus, they are potentially applicable as an advantageous preparation for iron fortification of food. This study aimed to characterise a commercially available CPP and determines optimum experimental conditions for binding it with ferrous iron. The effect of three variables – pH (5–7.5), mass ratio of iron to CPP (MR) (0.04–0.16) and holding time (40–80 min) – on the CPP's iron content was investigated using the central composite design (CCD) in response surface methodology (RSM), and a quadratic model was developed. The optimisation in this survey was based on the maximum response. Among all the regression's terms, the main and quadratic effects of pH represented the most significant influences on the iron content (P‐value <0.05). The obtained optimum conditions were as follows: pH 6.5, MR 0.14 and holding time 72 min, resulting in binding 68.66 mg iron per gram of the CPP. The quantity of iron bound to the CPP depended considerably on the experimental conditions and proved the importance of optimisation.     

CoSe nanoparticles prepared by the microwave-assisted polyol method as an alcohol and formic acid tolerant oxygen reduction catalyst

CoSe catalyst supported on nanoporous carbon was synthesized by microwave heating of glycerol solutions of Co(II) acetate and sodium selenite. The electrocatalytic behavior of the CoSe/C for oxygen reduction reaction (ORR) and its tolerance to several alcohols and formic acid were investigated by rotating disk electrode voltammetry and the results were compared with those of Pt/C. The results indicate that CoSe/C is a highly selective electrocatalyst towards ORR and shows a very high degree of tolerance to the presence of formic acid, methanol, ethanol, 2-propanol and ethylene glycol in acid medium. For a 20 wt.% CoSe/C, the onset potential and the magnitude of the current for ORR were almost the same with or without the presence of these fuels. In contrast, the Pt/C catalyst exhibited a mixed potential due to the simultaneous oxidation of the fuels and reduction of oxygen, which in turn caused the onset potential for the ORR to shift cathodically by ca. 500 mV in the presence of these fuels. Electrochemical measurements showed that the synthesized CoSe/C catalyst had a four-electron transfer mechanism for ORR. It is expected that this low cost electrocatalyst with its almost full tolerance and multi-fuel capability can find application in conventional and mixed-reactant fuel cells fueled with low molecular weight alcohols or formic acid.     

Spherical and Cylindrical Ion Acoustic Shock Structures in Plasmas with q-Nonextensive Electron Velocity Distribution

The propagation of ion acoustic shock waves in cylindrical and spherical geometries has been investigated. The plasma system consists of cold ions, nonextensive electrons and thermal positrons. Spherical and cylindrical Korteweg–de Vries–Burger equations have been derived by reductive perturbation method and their shock behavior is studied by employing finite difference method. It is found that shock waves can be produced in this medium. The important effects of the q-nonextensive electron on the properties of ion acoustic waves are discussed. Furthermore, it is observed that the positron concentration, ratio of electron to positron temperature, geometry parameter and the plasma kinematic viscosity significantly modifies the shock structure.     

Inconsistent transliteration of Iranian university names: a hazard to Iran’s ranking in ISI Web of Science

Today, university ranking has turned into a critical issue in the world. Each university is identified with a surface form under which the whole performance of that university is assessed. This article intends to provide a clear picture of the inconsistencies observed in recording Iranian university titles by their affiliated authors and to clarify the negative impact of such inconsistencies in positioning Iranian universities in global university ranking systems. To collect various surface forms of Iranian university names, use was made of ISI Web of Science through keywords Cu = Iran and py = 2000–2009. Only MSRT universities were considered. Two M.A. experts listed all variant forms of a single university under that name. The form publicized in a university’s website was considered as its entry name. The major sources of variation identified were as follows: Acronyms, misspellings, abbreviations, space variations, syntactic permutation, application of vowels/consonants and vowel/consonant combinations, /a/vs./aa/, Tashdid, Kasra ezafe, redundancy, downcasing, voiceless glottal stop sound /?/, shortening and deletion of titles. It was found that at its present shape Iranian universities are not receiving the rank they really deserve simply because authors affiliated to a university use university title forms inconsistently. It was recommended that authors follow the surface form publicized by universities in their websites, use the help of an editor in their works, and not be credited for their articles in case the forms deviate from those publicized through the websites. A spell checker, as an add-ins software is highly needed to homogenize Iranian university surface forms by replacing the variants by the dominant form proposed.     

In-vitro evaluation of thermoplastic starch/ beta-tricalcium phosphate nano-biocomposite in bone tissue engineering

Thermoplastic starch (TPS), as a natural based polymer, is known to have the capability to be used in biological applications due to its biocompatibility and biodegradability. In this study, mechanical properties of TPS are enhanced by incorporating bioactive β-tricalcium phosphate (β-TCP) particles for bone tissue engineering applications. Starch-based nanocomposites containing 3, 5, and 10 wt% of β-TCP nanoparticles (TT3, TT5, TT10) were made using a co-rotating twin-screw extruder. Dynamic light scattering (DLS) and X-ray diffraction (XRD) techniques were employed to analyze the nanocomposites. Moreover, degradability, swelling degree, and biomineralization in a simulated body fluid (SBF) were studied. To investigate the dispersion of β-TCP nanoparticles in the composite and biomineralization of the nanocomposites after incubation in SBF, scanning electron microscopy (SEM) and energy dispersive X-Ray analysis (EDX) were performed. Evaluation of mechanical properties of TPS and nanocomposites demonstrated that increase in β-TCP content enhanced mechanical properties. Besides, the bioactivity of these three nanocomposite materials was proven by nucleation of hydroxyapatite on the samples’ surface after incubation in simulated body fluid (SBF). Cytotoxicity test was done as well. Results of the current study have paved the way for the application of TPS/β-TCP composite as bone tissue engineering material.     

Synergistic effect between CuCr2O4 nanoparticles and plasticizer on mechanical properties of EP/PU/CuCr2O4 nanocomposites: Experimental approach and molecular dynamics simulation

In this research, copper chromite (CuCr₂O₄) nanoparticles (NPs) were synthesized by the sol–gel auto-combustion method. The effects of CuCr₂O₄ NPs and polyurethane (PU) on the tensile strength of the epoxy (EP) resin were studied by considering different weight percentages (wt%). The response surface methodology (RSM) coupled with central composite design (CCD) (RSM/CCD) methods were also used to optimize the Young's modulus, yield strength, and ultimate tensile strength of the EP/PU/CuCr₂O₄ nanocomposites. The composition structure and morphology of the EP/PU/CuCr₂O₄ nanocomposites were determined using the Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction, UV–vis diffuse reflection, Scanning Electron Microscopy, X-ray energy dispersive spectroscopy, and thermogravimetric analysis. It was also shown that the RSM/CCD methods could be utilized effectively to find the optimum process variables in the tensile test of the EP/PU/CuCr₂O₄ nanocomposites. Moreover, the tensile test revealed that the presence of the CuCr₂O₄ NPs in the EP/PU matrix improved the mechanical properties. Best results were obtained with the 0.76 wt% of the CuCr₂O₄ NPs and the 2.6 wt% PU in the epoxy resin. The molecular dynamic simulation was used to illustrate the effect of the NPs on the interaction energy and mechanical properties of this nanocomposite. The calculated interaction energy for the EP/PU/CuCr₂O₄ nanocomposites was −437.96 Kcal/mol. The results showed that Young's modulus had relative agreement with the experimental results.     

New polynomial strain energy function; application to rubbery circular cylinders under finite extension and torsion

In this article, a strain energy density function is proposed in terms of the principal invariants of the left Cauchy‐Green strain tensor for Rubber‐like materials. This model due to its mathematical structure lies in the category of polynomial hyperelastic models. To compare the performance of the proposed model with the Rivlin set, some test data of rubber‐like materials with pure homogeneous deformations are used. It is shown that the proposed model has better agreement with the test data compared to the selected model. As an application of the proposed model, it is used to obtain a closed form solution for analysis of rubbery solid circular cylinders with S‐shaped and semi J‐shaped mechanical behavior under the torsion superimposed on the axial extension. Moreover, the results predicted from the proposed model are compared to classic models to investigate the results accuracy for simplification done. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41718.     

Mechanical and thermal properties of toughened PA6/HDPE/SEBS‐g‐MA/Clay nanocomposite

Preparation and morphology of Polyamide 6 (PA6)/high density polyethylene (HDPE)/Styrene/Ethylene–Butylene/Styrene grafted with maleic anhydride (SEBS‐g‐MA)/Modified clay nanocomposites were studied. Mixing was performed using melting process in an extruder co‐rotating twin screw. After etching the materials with boiling toluene and THF at room temperature, the morphology of sample checked by scanning electron microscopy (SEM) analyses. X‐ray diffraction (XRD) used for evaluation of the effects of organo‐clay addition in the structure of nanocomposites. XRD traces showed that the characteristic (001) peak of the nanocomposites shifted to the lower degree region. XRD and SEM results showed more uniformly distribution and dispersion of HDPE in the PA6 matrix. Better sample morphology obtained, regarding less distance, and more uniformity between nanoparticles. The mechanical properties like tensile strength, impact strength, hardness and thermal properties of these toughened nanocomposites are discussed in terms of the nanoclay, SEBS‐g‐MA contents and morphology. Adding nanoclay improved hardness of nanocomposites product but reduced toughness and thermal properties. Meanwhile the presence of SEBS‐g‐MA as a compatibilizer improved toughness, thermal properties, hardness property, and the balance properties are achieved. POLYM. ENG. SCI., 55:29–33, 2015. © 2014 Society of Plastics Engineers