Experimental and theoretical studies of thiazoles as corrosion inhibitors for mild steel in sulphuric acid solution

The inhibition effects of 2-amino-5-mercapto-1,3,4-thiadiazole (2A5MT) and 2-mercaptothiazoline (2MT) on mild steel corrosion in 1.0 M H₂SO₄ were studied with potentiodynamic polarization, linear polarization resistance and electrochemical impedance spectroscopy techniques. It was shown that both 2A5MT and 2MT act as good corrosion inhibitors for mild steel protection. The high inhibition efficiencies were attributed to the simple blocking effect by adsorption of inhibitor molecules on the steel surface. The effects of the presence of extra NH₂ group and N atom in 2A5MT on the ability to act as corrosion inhibitors were investigated by theoretical calculations.     

Air permeability of electrospun polyacrylonitrile nanoweb

Ultrafine fibers were spun from polyacrylonitrile (PAN) solution in N,N‐dimethylformamide using a homemade electrospinning setup. Fibers with diameter ranging from 80 to 340 nm were obtained. Fiber size and fiber size distribution were investigated for various concentration, applied voltage, and tip‐to‐collector distance using image analysis. The diameters of the electrospun fibers increase when increasing the solution concentration and decrease slightly when increasing the voltage and needle tip‐to‐collector distance. Porosity and air permeability are vital properties in applications of electrospun nanofibrous structures. In this study, effects of process parameters on the porosity and air permeability of electrospun nanoweb were investigated as well. Results of statistical analysis showed that solution concentration and applied voltage have significant influences on pore diameters. It was concluded that nanofiber diameter played an important role on the diameter of pores formed by the intersections of nanofibers. A more realistic understanding of porosity was obtained and a quantitative relationship between nanoweb parameters and its air permeability was established by regression analysis. Two separate models were constructed for predicting air permeability in relation to process parameters. Optimization of electrospinning process for producing nanoweb with desirable air permeability is well achieved by these models. The models presented in this study are of high importance for their ability to predict the air permeability of PAN nanoweb both by process or structure parameters. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Modelling of rheological characteristics of various spaghetti types

Spaghetti enriched with resistant starch was produced to increase the dietary fibre intake of consumers. In the product base it was compared to bran and control spaghetti regarding to viscoelastic properties. Viscoelastic properties were tested by relaxation and creep tests by using TA-XT2i texture analyser. The viscoelastic properties gave structural information. Relaxation and creep data were analysed by generalized Maxwell (two- and three-termed), Peleg & Normand, Burgers and Peleg models, respectively. For relaxation three-termed Maxwell and for creep behaviour Burgers model represented viscoelastic behaviour satisfactorily. In general, bran spaghetti was found to have the lowest elasticity. All the samples started to loose their elasticity as cooking time proceeded and it became easy to deform them. Instrumentally, spaghetti with resistant starch was found to be better than bran enriched spaghetti.     

Removal of cationic dye from aqueous solution by adsorption onto crosslinked poly(4-vinylpyridine/crotonic acid) and its N-oxide derivative

In this study, crosslinked poly(4-vinylpyridine/crotonic acid) [poly(4-VPy/CrA)] and its N-oxide derivative were synthesized to compare the adsorption of cationic methylene blue (MB) dye on these materials. The adsorptive removal of MB from aqueous solution onto adsorbents was studied by using column adsorption method. Experimental results showed that MB was removed more effective by poly(4-VPy/CrA)–N-oxide than poly(4-VPy/CrA) resins. The percentage removal of MB increased with pH, and it was observed that basic pH was favorable for the adsorption of MB. The adsorption capacity for poly(4-VPy/CrA)–N-oxide resin was found to 19.96 mg/g. It was found that the adsorption isotherm of the MB-fitted Langmuir-type isotherm. For the adsorption of MB, the pseudo-second-order chemical reaction kinetics provides the best correlation with the experimental data. Ten adsorption–desorption cycles demonstrated that the resins were suitable for repeated use without considerable change in adsorption capacity.     

A Role-Based Service Level NFC Ecosystem Model

Near Field Communication (NFC) is a short range wireless communication technology allowing to communicate mobile devices within close proximity. It provides opportunity for service providers to offer various value added services to customers. NFC technology allows the usage of wide range of applications and eliminates the obligation to carry additional components other than the mobile device such as credit or payment cards, tickets, identification cards or keys. Despite its technological advantages over alternative ones, the NFC business ecosystems and services are yet to take off. The problems mainly arise with the business issues triggered by different and mostly conflicting needs of many actors in the ecosystem and several additional technical issues. In this study, by adopting a role-based service ecosystem modeling, we propose an NFC ecosystem model which perfectly specifies the roles in the ecosystem, and defines set of activities for each role, and communication structure. We analyzed NFC ecosystem in three phases as pre-installation, installation, and service usage. We have defined the activities and communication structure in the first two phases, and finally investigated the service usage phase in three different operating modes of NFC. After giving the details of the proposed ecosystem model, two use cases are given to validate the developed ecosystem model. We complete our study by discussing the requirement satisfaction.     

Fabrication and characterization of NiCoZn-M (M: Ag, Pd and Pt) electrocatalysts as cathode materials for electrochemical hydrogen production

Ag, Pd and Pt-modified alkaline leached NiCoZn composite coatings were prepared on a copper specimen by electrochemical technique. The chemical composition of layers before and after leaching as well as after noble metal modification was determined by energy dispersive X-ray spectroscopy (EDX). The surface morphologies of the composite coatings were examined with the help of scanning electron microscopy (SEM). The hydrogen evolution activity of the electrodes was studied in 1 M KOH solution. For this purpose, cathodic current-potential curves and electrochemical impedance spectroscopy (EIS) techniques were used. Furthermore, the change of hydrogen evolution activity of the electrodes as a function of operation time in alkaline solution was also investigated. Surface morphologies showed that the composite coatings prepared to have compact and porous surface. EDX analysis confirmed the presence of Ag, Pd and Pt metals over the NiCoZn layer. The co-deposition of nickel, cobalt and zinc on copper surface and subsequently alkaline leaching of zinc rendered cathode material very active in hydrogen evolution. The modification of alkaline leached NiCoZn ternary coating by deposition of small amounts of Ag, Pd and Pt can further enhance the hydrogen evolution performance of this Raney-type electrode when compared to NiCoZn individually. The order of hydrogen evolution activity of catalysts studied is Ni < NiCoZn < NiCoZn-Pd < NiCoZn-Ag < NiCoZn-Pt. The long-term electrolysis tests showed that the Pt-modified electrode has the better time stability than the others. The superiority of Pt-modified catalyst explained by well known intrinsic catalytic activity of Pt.     

Educational UTAUT-based virtual reality acceptance scale: a validity and reliability study

Virtual Reality - This study aims to fill a gap in current research on virtual reality (VR) by developing a valid and reliable educational VR acceptance scale based on the unified theory of...     

Development of educational virtual reality attitude scale: A validity and reliability study

Virtual Reality - The aim of the study is to address a gap in the literature by developing an educational virtual reality (edVR) attitude measurement instrument, which determines college...     

Modal analysis and improvement of lightweight wings for micro air vehicle (MAV) applications

Journal of Mechanical Science and Technology - Micro air vehicles (MAVs) are small portable flying machines designed to perform some specific tasks. Presently, the MAVs are being highly considered...     

The effect of learning analytics-based interventions in mobile learning on students' academic achievements,self-regulated learning skills,and motivations

Universal Access in the Information Society - This study examines the effects of using learning analytics (LA) in a mobile-based learning setting on students' self-regulated learning (SRL)...