Modeling educational usage of Facebook

The purpose of this study is to design a structural model explaining how users could utilize Facebook for educational purposes. In order to shed light on the educational usage of Facebook, in constructing the model, the relationship between users' Facebook adoption processes and their educational use of Facebook were included indirectly while the relationship between users' purposes in using Facebook and the educational usage of Facebook was included directly. In this study, data is collected from Facebook users with an online survey developed by the researchers. The study group consists of 606 Facebook users whose answers were examined by using a structural equation model. The analyses of the 11 observed and 3 latent variables provided by the model showed that 50% of educational usage of Facebook could be explained by user purposes along with the adoption processes of Facebook. It was also found that Facebook adoption processes could explain 86% of all user purposes. Finally, while Facebook adoption processes explained 45% of its educational usage, it could explain 50% of variance in educational usage of Facebook when the user purposes were added into the analyses.     

The wetting characteristics and surface tension of some ni-based alloys on yttria,hafnia, alumina,and zirconia substrates

Sessile drop experiments were carried out in order to measure surface tensions and to investigate wetting characteristics of some Ni-based alloys on various ceramic substrates. The liquid-vapor surface tension (γ_LV) was found to be 1.764 N/m for pure Ni, 1.45 ± 0.11 N/m for Ni-20 pct Cr, 1.29 ± 0.06 N/m for Ni-20 pct Cr-1 pct Al, and 1.31 ± 0.09 N/m for Ni-20 pct Cr-4 pct Al. The commercial alloys UD520, UD718, UD720, and WASPALOY* showed non-wetting behavior on zirconia but wetting tendency on alumina substrates. Ni-20 pct Cr-1 pct Al showed non-wetting behavior on alumina, hafnia, and yttria substrates whereas Ni-20 pct Cr and Ni-20 pct Cr-4 pct Al were observed to be non-wetting on hafnia but wetting on yttria and alumina substrates. All the systems that exhibited wetting behavior were found to be non-wetting in the beginning; however, wet-ting improved with time. The wetting characteristics were apparently related to impurification of droplets during measurements, which is reflected in the solidification structure, rather than to the presence of oxides on the surface.     

The effect of methyl-tri-n-butylammonium methylsulfate and graphite nanoplates on production of antistatic acrylic polymer

Methyl-tri-n-butylammonium methylsulfate (BIL) was incorporated into acrylic resin to improve antistatic property of acrylic polymer (AP). In order to avoid reduction in the mechanical properties of acrylic film and to reach higher electrical conductivity values, the combination of graphite nanoplates (Gr) and BIL was used. The effects of incorporation of BIL and Gr into AP on UV-blocking properties and UV transmittance data of acrylic films were measured. After 120 days, AP containing 5 wt% BIL and 0.01 wt% Gr, and AP+15 wt% BIL exhibited antistatic property. While BIL incorporation into acrylic resin deteriorated the mechanical properties, 0.01 wt% Gr incorporation increased the tensile strength by 83%.     

Synthesis and characterization of metal ion-imprinted polymers

In this study, ion-imprinted polymeric materials from an aqueous solution were prepared to remove metal ions \((\hbox {M}^{2+})\) like \(\hbox {Ni}^{2+}\), \(\hbox {Co}^{2+}\), etc. To prepare ion-imprinted polymers (IIPs), acrylic acid derivatives (XA) like acrylamide (AAm), methacrylic acid and itaconic acid were chosen as monomers. Metal ions formed binary chelate complexes with the help of 8-hydroxyquinoline (8-HQ). The solution containing functional monomers and the binary complex were polymerized with the help of various cross-linkers [ethylene glycol dimethylacrylate (EGDMA) or trimethylpropane trimethacrylate (TMPTMA)] and the target ion was removed from this polymer through an applicable method to produce IIPs. Furthermore, the control polymers (CPs) were synthesized through the same method without using metal ion. Characterization of the polymeric materials was investigated through spectroscopic (FTIR/ATR), thermal (TGA, DSC) and surface (SEM and XRD) analyses. Functional monomers, cross-linkers and the target ion’s species were changed during preparation of IIPs to observe their effect on imprinting of the target ion. Adsorption of the target ion to the prepared IIPs and the factors affecting the adsorption like concentration, pH, temperature, mass, etc. were studied.     

Mesoscopic structure and swelling properties of crosslinked polyethylene glycol in water

In this paper, we present our efforts in modeling and simulation of polyethylene glycol crosslinked with an isocyanate tHDI. The polymer, by its nature, is hydrophilic and has strong hydrogen bond interactions with water. The simulations are performed at coarse-grained scale by using a dissipative particle dynamics (DPD) simulation method. The effect of hydrogen bond between water and polymer beads on the structure of the crosslinked hydrophilic polymer structure is studied. The polymer is observed to phase separate with water in the absence of hydrogen bonds in DPD simulations. In the reverse case, where hydrogen bonds are explicitly included in DPD simulations, polymer mixes with water. This behavior is investigated by plotting the density profiles. Moreover, the volumetric swelling behavior in mixtures with different water contents is estimated from simulations and extrapolated by a polynomial fit to compare with experiments. It is observed that the predicted swelling ratio is in good agreement with the experimental measurements.     

Conductive Cotton Fabrics Coated with Myristic Acid/Zinc Oxide Nanoparticles

This research mainly deals with enhancement of electrical conductivity performance of cotton fabrics using zinc oxide nanoparticles. The application of nano-zinc oxide/myristic acid onto 100% cotton plain fabrics was performed by dipping process. The effect of myristic acid and zinc oxide nanoparticles on cotton fabrics was analyzed by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Electrical conductivity, UV protection performance, and hydrophilic properties of the cotton fabrics were also investigated. The surface resistivity of the cotton fabric noticeably dropped off by applying nano-zinc oxide/myristic acid. Furthermore, electrical conductivity of the coated cotton fabrics was maintained till 15 weeks. Surface hydrophilicity of cotton fabrics decreased with increasing myristic acid content. The changes in decomposition temperatures and crystallinity can be ignorable after application of myristic acid/nano-zinc oxide.     

Investigation of shipyard wastewater treatment using electrocoagulation process with Al electrodes

In this study, shipyard oily wastewater treatment was investigated by electrocoagulation (EC) using aluminum electrodes in a batch reactor by evaluating different operation conditions. The maximum chemical oxygen demand (COD) removal efficiency of 88.83% was obtained at current density of 3 mA/cm². The removal efficiency was gradually improved with increasing current density and decreased with increasing COD concentration. However, initial pH value was not determinant factor for this process. Total energy and electrode cost were calculated as $0.88 per m³ treated wastewater. The result of this research shows that EC process seems to be an efficient method for the oily wastewater treatment.     

Collaboration Environments for Construction: Implementation Case Studies

Although emerging technologies offer the construction industry many opportunities for computer supported collaboration environments, the companies adopting these technologies usually fail in achieving the full benefits from their implementations. The reason for this is found to be focusing too much on the technical factors and ignoring or underestimating the factors related to change, implementation, human and organizational factors, and the roles of the management and end users. Each new information technology (IT) implementation involves some change for the organization and the employees, and is therefore a source of resistance and confusion unless special attention is paid to managing this change. This paper aims to review the related theoretical concepts and previous work on success factors for collaboration environment implementations and failure reasons for IT, and to present the current approaches adopted by construction organizations implementing collaboration environments. In order to achieve these aims, the results of an extensive literature review on general causes of failure in IT implementations are presented, and the key areas to focus on during IT design and implementation are highlighted and explained. The results of exploratory case studies are summarized to show the current IT implementation and collaborative working approaches in the United Kingdom construction industry and interpreted using a systems thinking approach. The paper then concludes with some insights into how construction organizations can improve the implementation of collaboration systems.     

Equilibrium and kinetics studies for adsorption of direct blue 71 from aqueous solution by wheat shells

This paper deals with the application of wheat shells (WS), an agricultural by-product, for the removal of direct blue 71 (DR) from aqueous solution. The characteristics of WS surface, such as surface area, Bohem titration and scanning electron microscopy (SEM) were obtained. The removal of direct blue 71 onto WS from aqueous solution was investigated by using parameters, such as pH, temperature, adsorbent dose, contact time and initial concentration. The adsorption process attains equilibrium within 36 h. The extent of dye removal decreased with increasing adsorbent dosage and also increased with increasing contact time, temperature, in solution concentration. Optimum pH value for dye adsorption was determined between 6 and 8. The experimental data were analysed by the Langmuir and Freundlich models of adsorption. It was found that the Langmuir equation fit better than the Freundlich equation. Maximum adsorption capacity (Q(m)) was calculated as at different temperatures (293, 303 and 313 K) 40.82, 45.66 and 46.30 mgg(-1), respectively. In addition, the adsorption data obtained at different temperatures of DR by WS were applied to pseudo first-order, pseudo second-order and Weber-Morris equations, and the rate constants of first-order adsorption (k(1)), the rate constants of second-order adsorption (k(2)) and intraparticle diffusion rate constants (k(3)) at these temperatures were calculated, respectively. The rates of adsorption were found to conform to pseudo second-order kinetics with good correlation (R(2)>or=0.9904). Also, free energy of adsorption (DeltaG degrees), enthalpy (DeltaH degrees), and entropy (DeltaS degrees) changes were determined to predict the nature of adsorption. Furthermore, the results indicate that WS could be employed as a low-cost alternative to other adsorbents in the removal of direct blue 71 from aqueous solution.     

Influence of some aromatic amino acids on the swelling behavior of acrylamide/maleic acid hydrogel

Summary Influence of some aromatic amino acids (histidine, phenylalanine and tryptophan) on the swelling behavior of acrylamide/maleic acid hydrogel (AAm/MA) prepared by γ-radiation was investigated. Swelling tests of AAm/MA hydrogel were made in buffer solutions and amino acid solutions at various pH at 37°C. The pH values are ionization of α-carboxyl groups (pK'₁), α-amino groups (pK'₂) and, isoelectric points (pI) of amino acids. The swelling of AAm/MA hydrogel increased when pH values of solutions were increased. The value of equilibrium swelling of AAm/MA hydrogel was 1035% at pH 10 buffer, while it was 880% at pH 2 buffer. The values of equilibrium swelling of AAm/MA hydrogel in phenylalanine, tryptophan and histidine solutions varied among 1130–1245% at pH 10, while they were among 790–975% at pH 2. The rate constant of swelling, diffusional exponent, network parameter and, diffusion and intrinsic diffusion coefficient were calculated by swelling kinetics. Diffusion of the penetrants into the hydrogel was found to be non-Fickian character. The diffusion coefficients of the hydrogel varied between 3.33×10⁻⁶– 7.71×10⁻⁶ cm ²s⁻¹, while the intrinsic diffusion coefficients waried between 4.03×10⁻⁶– 8.48×10⁻⁶ cm ²s⁻¹. Received: 22 December 1997/Revised version: 3 March 1998/Accepted: 5 March 1998