Axisymmetric flow over a backward-facing step in an annular pipe

The incompressible flow of a Newtonian fluid over a backward-facing step is investigated numerically. The geometry is an annular pipe in which the radius of the inner cylinder decreases suddenly. Keeping the radial expansion ratio fixed axisymmetric flows are computed for outlet radius ratios from 0.1 to 1 (ratio of the inner to the outer outlet radius). The Reynolds number at which the flow separates from the outer cylinder decreases as the outlet radius ratio decreases for constant inlet geometry. The growth with Reynolds number of the recirculation zone on the inner outlet cylinder just behind the step is strongly reduced when the recirculation zone on the outer cylinder is established. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A Comvewiemt Synthesis of 1-Aminopolycycloalkames and Their Tosylate Salts

Syntheses of oridgehead 4-amino-l-bromopentacy-clo[4.3.0.0^2.5 O^3,8.O^4,7]nonan-9-one ethyl ene acetal (6), 4-iodocubyl-l-ammonium tosylate (8) and 1-adamantane ammonium tosylate (10) are described.     

Generalized uncertainty principle, modified dispersion relations and the early universe thermodynamics

In this paper, we study the effects of Generalized Uncertainty Principle (GUP) and Modified Dispersion Relations (MDRs) on the thermodynamics of ultra-relativistic particles in early universe. We show that limitations imposed by GUP and particle horizon on the measurement processes, lead to certain modifications of early universe thermodynamics.     

A sustainable exergy model for energy–water nexus in the hot regions: integrated combined heat,power and water desalination systems

Journal of Thermal Analysis and Calorimetry - Water scarcity is a worldwide concern for Earth citizens. Finding new methods for water concentration is essential for the extension of life. The water...     

Graphene sheet for improving the electrocatalytic activity of a benzofuran derivative modified electrode for determination of epinephrine in the presence of serotonin

A nanocomposite system based on coumarin derivative and graphene sheet was used to prepare a new electrochemical sensor. The objective of the mentioned nanocomposite was to investigate novel electrochemical properties enabling the quantification of epinephrine (Ep). Cyclic voltammetry was used to study the redox properties of the mentioned modified electrode at different scan rates. Henceforward, the electrocatalytic oxidation of Ep at the surface of the modified electrode was considered. The data has shown excellent catalytic activity of the modified electrode for the electrooxidation of Ep, which leads to a reduction of overpotential for more than 238 mV. According to differential pulse voltammetry (DPV), the oxidation of Ep showed a dynamic range between 0.1 and 1000.0 μM and the detection limit (3s) of 0.011 μM. Besides, DPV was used for the determination of Ep at the mentioned modified electrode in the presence of serotonin.     

Reverse Micelle Surfactant System Comprising the 1-decanoyl-rac-glycerol and the Lauryldimethylamine-N-oxide: Structure and Dynamics of Confined Water

Russian Journal of Physical Chemistry A - A mixture of two surfactants 1-decanoyl-rac-glycerol (MAG) and lauryldimethylamine-N-oxide (LDA) in pentane solvent was investigated by molecular dynamics...     

Methane dehydrogenation on Cu and Ni surfaces with low and moderate oxygen coverage

First-principles density functional theory calculations are carried out to evaluate energy barriers and mechanisms for the dehydrogenation reactions of CH₄ on clean and oxygen-covered surfaces of Cu (111) and Ni (111) with low and moderate oxygen coverage. In the presence of oxygen, two possible pathways have been evaluated. The more likely pathway, which is further analyzed, is that CH₄ loses an H to the surface O. Results from this pathway agree with previous findings showing that oxygen promotes CH₄ dissociation on Cu (111) and hinders that on Ni (111). In addition, our results show lower energy barriers on Cu with higher oxygen coverages up to 0.38 monolayer. However, such an increase in oxygen coverage did not show any favorable effect for CH₄ dissociation on Ni (111). The findings are analyzed through electronic factors revealed by charge analysis and density of states.