Results 1 - 10 of 368
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[en] Conventional screen stencils are known for having micron scale screen mesh, which restricts definition of the printed pattern, and subsequently, the development of fine line screen printing technology. In contrast, electrospun fiber membranes are characterized by a consistent mesh size, which have the ability to reduce down to hundreds of nanometers. In this study, we produced a screen stencil by combining electrospun PVA/EG fiber membrane with a commercial printing screen stencil. The fiber diameter, porosity, hydrophilicity, and thickness of the PVA/EG fiber membrane were controlled by the ethylene glycol content, crosslinking time, and spinning time. The effects of membrane’s morphology and structure on image definition of printed pattern were investigated. Results showed that the printed pattern depicted the higher definition when the electrospun fiber membrane had the higher porosity (83.67%), smaller fiber diameter (0.1859 μm) and uniform diameter distribution. With respect to hydrophilicity and thickness of membrane, both had stronger influence on the flux of printed paste, the better hydrophilicity and lower thickness membrane were, the darker color and higher definition images obtained. (paper)
[en] MoO2 nanospheres are successfully synthesized by a simple ethylene glycol-assisted hydrothermal route. The formation process is associated with the dissolution-recrystallization mechanism under the ethylene glycol reduction, resulting in a unique structure of that solid MoO2 nanospheres assembled by many ultrafine primary nanoparticles. Benefiting from the hierarchical structural features, the MoO2 nanospheres electrode displays a higher specific capacitance (204.7 and 197.4 Fg−1 at 1 and 6 A g−1, respectively) and exhibits a significant superior cycling stability (the specific capacitance maintains 90.6% after 1000 cycles at 1 A g−1). (paper)
[en] This paper examines the rheological behavior of water (60%vol.)–ethylene glycol (40%vol.) mixture in the presence of functionalized multi-walled carbon nanotubes. At the first, the viscosity of various samples was measured at shear rates ranging from 6.115 to 73.38 s−1 and temperature range of 25–50 °C. Then, using the experimental data, some correlations were proposed to predict the viscosity of the nanofluid. Viscosity measurements at different shear rates revealed that all nanofluid samples were non-Newtonian power law fluid. Findings showed that consistency index increased along with volume fraction, while it decreased with increasing temperature. Moreover, the values of power law index were always less than 1, indicating shear thinning behavior.
[en] The reduction of BODIPYs and dipyrrins to dipyrromethanes, via a reaction involving ethylene glycol and sodium methoxide, is reported. When benzyl alcohol is used in place of ethylene glycol, the addition of 2,4-dinitrophenylhydrazine to the reaction mixture after microwave irradiation results in the production of 1-benzylidene-2-(2,4-dinitrophenyl)hydrazone, indicating concomitant production of aldehyde alongside the dipyrromethane. (author)
[en] Highlights: • Measurement of dynamic viscosity of MgO-MWCNTs/EG nanofluid. • Presenting effects of temperature and hybrid particles volume fraction. • All nanofluid samples exhibited Newtonian behavior at all temperatures considered. • The classical models were unable to predict the dynamic viscosity of the nanofluid. • Suggesting a new correlation to estimate the dynamic viscosity of the nanofluid. In this paper, the effects of temperature and particles concentration on the dynamic viscosity of MgO-MWCNT/ethylene glycol hybrid nanofluid is examined. The experiments carried out in the solid volume fraction range of 0 to 1.0% under the temperature ranging from 30 °C to 60 °C. The results showed that the hybrid nanofluid behaves as a Newtonian fluid for all solid volume fractions and temperatures considered. The measurements also indicated that the dynamic viscosity increases with increasing the solid volume fraction and decreases with the temperature rising. The relative viscosity revealed that when the solid volume fraction enhances from 0.1 to 1%, the dynamic viscosity increases up to 168%. Finally, using experimental data, in order to predict the dynamic viscosity of MgO-MWCNT/ethylene glycol hybrid nanofluids, a new correlation has been suggested. The comparisons between the correlation outputs and experimental results showed that the suggested correlation has an acceptable accuracy.
[en] Characteristics of instantaneous (I), vibration-average (V), and frozen (F) structures of liquid ethylene glycol (EG), monoethanolamine (MEA), and ethylenediamine (ED) are obtained by means of molecular dynamics in the temperature range of 273–453 K. Structures are described by plotting Voronoi polyhedra and Delaunay simplexes. The distributions of volumes of Voronoi polyhedra and the radii of the spheres of Delaunay simplexes were obtained in the temperature range of liquid phase EG, MEA, and ED. A comparative analysis of these characteristics of three studied liquids is performed with different averaging over time and space. It is shown that describing the structure of liquids according to Voronoi and Delaunay allows us to compare the characteristics of spatial networks of hydrogen bonds in them very clearly.
[en] Highlights: • Preparing MgO/EG-water (50:50) nanofluid samples with concentrations of 0.1–3%. • Measuring the viscosity of samples at shear rate range of 12.23–73.44 s−1. • Observing Newtonian and non-Newtonian behavior for the nanofluid samples. • Reporting effects of temperature and MgO concentration on rheological behavior. • Performing sensitivity analysis and proposing a correlation to predict viscosity. In this paper, the effect of dispersion of magnesium oxide nanoparticles on viscosity of a mixture of water and ethylene glycol (50–50% vol.) was examined experimentally. Experiments were performed for various nanofluid samples at different temperatures and shear rates. Measurements revealed that the nanofluid samples with volume fractions of less than 1.5% had Newtonian behavior, while the sample with volume fraction of 3% showed non-Newtonian behavior. Results showed that the viscosity of nanofluids enhanced with increasing nanoparticles volume fraction and decreasing temperature. Results of sensitivity analysis revealed that the viscosity sensitivity of nanofluid samples to temperature at higher volume fractions is more than that of at lower volume fractions. Finally, because of the inability of the existing model to predict the viscosity of MgO/EG-water nanofluid, an experimental correlation has been proposed for predicting the viscosity of the nanofluid.
[en] The main aim of the present study is to develop graphene-based ink and graphene hybrid-based ink with excellent stability, physical and electrical properties for flexible electronics. Graphene foam (GF) was used as the graphene-like material and inkjet printing technique was utilized in the fabrication of the conductive patterns. GF ink, GF/poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) hybrid ink and GF/silver nanoparticles (AgNPs) hybrid ink were prepared by using new mixed solvents of 2-propanol (IPA) and ethylene glycol (EG) at ratio of 1:1. Results showed that GF/PEDOT:PSS hybrid ink presented better stability and surface conductivity than those of GF ink and GF/AgNPs hybrid ink, in which the ink exhibited only 30% decrement from the initial concentration after a month and 100% improvement in the surface conductivity at 50 printed layers. Besides that, the conductive pattern made of GF/PEDOT:PSS hybrid ink exhibited gauge factor with the value of 4.3 which is capable to be used for low strain sensor application.
[en] This paper exposes the viscosity investigation of titanium dioxide (TiO2) based nanofluids. The viscosity measurements have been carried out for nanofluids of titanium dioxide suspended in 60:40 (by volume) water and ethylene glycol (EG) mixture. Titanium dioxide nanofluids were prepared in concentration ranges of 0.5 to 1.5 %. The viscosity measurement has been performed by the spindle rotation technique using Brookfield LVDV-111 Ultra Rheometer at temperatures of 30 to 80 °C. The results indicate that the viscosity of nanofluids increases with increase in volume concentration and decreases with increase in temperature. The relative viscosity is independent of temperature. The design correlation equation is fitted for the nanofluids mixtures in the range of 0 ≤ ø ≤1.5 % and 30≤ T ≤ 80 °C. (author)
[en] We developed and implemented an intelligent control system to be used in an extractive distillation column that produces anhydrous ethanol using ethylene glycol as solvent. The concept of artificial neural networks (ANN) was used to predict new setpoints after disturbances, and proved to be a fast and feasible solution. The developed control system receives data from temperature, flowrate and composition measurements of the azeotrope feed, and the ANN estimates the new set-points of the controllers to maintain 99.5 mol% of ethanol at the top and less than 0.1mol% at the bottom; feed composition was also estimated using an ANN. All ANN were trained to provide output data corresponding to an optimized operating condition. The results showed that the intelligent control system can predict a new operating condition for any disturbance in the column feed and presented superior performance when compared with the control system without ANN.