Small flexural oscillations of an initially stretched circular cylinder

Small flexural oscillations of a circular cylinder initially subjected to a finite extension or compression are studied. The resulting equations are solved for Mooney materials. An approximate frequency expression is calculated for a cylinder with small radius.     

Weakly non-linear waves in a fluid-filled elastic tube with variable prestretch

In the present work, by utilizing the non-linear equations of motion of an incompressible, isotropic thin elastic tube subjected to a variable prestretch both in the axial and the radial directions and the approximate equations of motion of an incompressible inviscid fluid, which is assumed to be a model for blood, we studied the propagation of weakly non-linear waves in such a medium, in the long wave approximation. Employing the reductive perturbation method we obtained the variable coefficient KdV equation as the evolution equation. By seeking a travelling wave solution to this evolution equation, we observed that the wave speed is variable in the axial coordinate and it decreases for increasing circumferential stretch (or radius). Such a result seems to be plausible from physical considerations.     

First principles calculations of Cd and Zn chalcogenides with modified Becke–Johnson density potential

In this work, we present first principles calculations based on a full potential linear augmented plane-wave method (FP-LAPW) to calculate structural and electronic properties of CdX and ZnX (X = S, Se, Te) based II–VI chalcogenides. First principles calculations using the local density approximation (LDA) and the related generalized gradient approximation (GGA) lead to a severe underestimate of the band gap. The proposed model uses various exchange–correlation potentials (LSDA, GGA and MBJLDA) to determine band gaps and structural properties of semiconductors. We show that using modified Becke–Johnson (MBJLDA) density potential leads to a better agreement with experimental data for band gaps of Cd and Zn based semiconductors.     

New soliton solutions of Davey–Stewartson equation with power-law nonlinearity

This study is related to new soliton solutions of Davey–Stewartson equation (DSE) with power-law nonlinearity. The generalized Kudryashov method which is one of the analytical methods has been used for finding exact solutions of this equation. By using this method, dark soliton solutions of DSE have been found. Also, by using Mathematica Release 9, some graphical representations have been done to analyze the motion of these solutions.     

Interactions of nonlinear ion-acoustic waves in a collisionless plasma

In the present work, based on a one-dimensional model, the interaction of two solitary waves propagating in opposite directions in a collisionless plasma is investigated by use of the extended Poincaré–Lighthill–Kuo (PLK) method. It is shown that bi-directional solitary waves are propagated and the head-on collision of these two solitons occur. The phase shifts and the trajectories of these two solitons after the collision are obtained.     

UV radiation curing of epoxidized palm oil-cycloaliphatic diepoxide system induced by cationic photoinitiators for surface coatings

Epoxidized palm oil (EPO) can be cured with ultraviolet (UV) radiation using either radical, cationic or hybrid initiation. Cationic curing system has been chosen in this study due to the fact that epoxy groups present in EPO can be utilized directly to form cross links. Curing was carried out in a 20 cm wide UV IST machine. Triaryl sulphonium salts and ferrocenium salt were used as cationic photo initiators. Formulations were developed based on selected grades of EPO. Other materials employed included different types and concentrations of photo initiators, monomers and photo-sensitizer. The effect of post-cure conditions was also studied. The properties of the cured film, namely, pendulum hardness, percentage of gel content and tensile strength were determined. It was found that triarylsulphonium hexafluorophosphate exhibited low solubility in EPO. Addition of a vinyl ether monomer to the formulation did not enhance pendulum hardness and gel content of the cured films. Post-cure temperature had no significant effect on the properties of the cured film. The FTIR studies showed evidence of the ring opening of the epoxide groups present in the formulation.     

The effect of opacifier properties on thermal conductivity of vacuum insulation panel with fumed silica

Journal of Thermal Analysis and Calorimetry - The reduction of radiation heat transfer in VIPs is an important issue. In VIPs, the radiation heat transfer is reduced by the use of opacifier....     

In-line coupling capillary electrochromatography with amperometric detection for analysis of explosive compounds

Amperometric detection at a bare gold electrode has been in-line coupled with capillary electrochromatography (CEC) for analysis of nitroaromatic and nitroamine explosives in contaminated soils and ground water. The CEC column packed with 3 microm C18 particles performed best using a mobile phase containing 70-80% methanol, 30 or 20% water, 5 mM sodium dodecyl sulfate (SDS) and 10mM 2-(N-morpholino)ethanesulfonic acid (MES). In contrast, the separation column packed with 1.5 km C18 particles exhibited the best separation when only 30% methanol was added to a mobile phase containing 70% water, 7 mM SDS, and 10 mM MES. The detection, based on electrochemical reduction of the explosives (-0.7 or -1 V vs. Ag/AgCl, depending upon the level of methanol in the mobile phase), was compatible with such mobile phases. The detection limits for 13 explosives ranged from 100 to 200 ppb, i.e., about twofold better than those obtained with electrokinetic chromatography (EKC)/amperometric detection. From an operational viewpoint, exhaustive column conditioning was a prerequisite and care should be taken to prevent bubble formation and current breakdown during the course of separation. The CEC column equipped with amperometric detection successfully measured explosives in ground water and extracts prepared from contaminated soils and the results obtained agreed well with those of the U.S. Environmental protection Agency (EPA) method.