Sorption and transport of methanol in poly(ethylene terephthalate)

This paper reports the sorption and diffusion characteristics of methanol vapor in polyethylene terephthalate (PET). Amorphous PET, semicrystalline, biaxially oriented annealed and non-annealed samples have been studied for equilibrium sorption and kinetics of methanol. At activities of methanol less than 0.30, uptake shows Fickian kinetics and isotherm follows the Dual Mode model. Diffusion coefficients increase with penetrant concentration and are of the order of 10⁻¹⁰ cm²/s. Hysteresis during desorption and increase in solubility during resorption suggest methanol induced conditioning effects which may have detrimental effects on the barrier efficacy of PET. At activities greater than 0.30, swelling and relaxation effects occur and the isotherms show Flory-Huggins behavior for all three samples. Uptake follows two-stage kinetics fit by the Berens-Hopfenberg model. Greater polymer chain stability due to annealing reduces the extent of relaxation and improves the barrier efficacy over amorphous and non-annealed, oriented PET. For amorphous PET, at 80% activity and above, an induction time is observed which is absent in the semicrystalline films, suggesting strong relaxation effects in the amorphous phase of PET.     

Elimination of current non-uniformity in carbon nanotube field emitters

Activation of abnormal emitting sites in Carbon Nano Tube (CNT) field emitters and their elimination is reported. CVD grown, patterned CNT was used as cathode for field emission studies. We encountered the problem of current non-uniformity in CNT cathode. This non-uniformity was attributed to abnormally active emitting sites during voltage ramp-up. The sudden increase in current resulted in region of positive slope in F–N curve, which can’t be explained by conventional F–N theory. Also the grown CNTs can be a mixture of metallic and semi conducting nature, which may cause deviation from the conventional F–N theory. We could eliminate abnormally active sites by electric field treatment, thereby increasing current uniformity and stability. The work is underway to understand the deviation in FN curve at high fields.     

An exact solution to the unsteady free-convection boundary-layer flow past an impulsively started vertical surface with newtonian heating

An exact solution of the unsteady free-convection boundary-layer flow of an incompressible fluid past an infinite vertical plate with the flow generated by Newtonian heating and impulsive motion of the plate is presented. The resulting governing equations are nondimensionalized and their solutions are obtained in a closed form with the help of the Laplace transform technique. A parametric study of the roles of all involved parameters is conducted and a representative set of numerical results for the velocity, temperature, and skin friction is illustrated graphically. The physical aspects of the problem are discussed. Published in Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 5, pp. 102–107, September–October, 2007.     

Geometric discord and measurement-induced nonlocality for well known bound entangled states

We employ geometric discord and measurement induced nonlocality to quantify quantumness of some well-known bipartite bound entangled states, namely the two families of Horodecki’s ( $2\otimes 4, 3\otimes 3$ and $4\otimes 4$ dimensional) bound entangled states and that of Bennett et al.’s in $3\otimes 3$ dimension. In most of the cases our results are analytic and both the measures attain relatively small value. The amount of quantumness in the $4\otimes 4$ bound entangled state of Benatti et al. and the $2\otimes 8$ state having the same matrix representation (in computational basis) is same. Coincidently, the $2m\otimes 2m$ Werner and isotropic states also exhibit the same property, when seen as $2\otimes 2m^2$ dimensional states.     

Comment on “Groverian entanglement measure and evolution of entanglement in search algorithm for n(= 3, 5)-qubit systems with real coefficients” (volume 6, number 4, August 2007), by Arti Chamoli and C. M. Bhandari

We point out that the main results—the analytic expressions for the Groverian measure of entanglement, in the above mentioned paper are erroneous. The technical mistake of the paper is discussed. It is shown by an explicit example that the formula for calculating the Groverian measure yields ${G(|\psi\rangle)=0}We point out that the main results—the analytic expressions for the Groverian measure of entanglement, in the above mentioned paper are erroneous. The technical mistake of the paper is discussed. It is shown by an explicit example that the formula for calculating the Groverian measure yields G(|y?)=0{G(|\psi\rangle)=0} for some entangled states.     

Microstructural,Optical and Magnetic Study of Ni–Zn Nanoferrites

Journal of Superconductivity and Novel Magnetism - NixZn1-xFe2O4 (x?=?0.0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1.0) nanoferrites were synthesized using the citrate precursor method with...     

A two-unit cold standby system with three modes and correlated failures and repairs

The economic parameters are studied for a two-unit cold standby system with three modes and failure and repair times having bivariate exponential density as their joint distribution. The system is studied at suitable regenerative epochs to obtain these economic parameters. Explicit results have also been obtained for the case when failure and repair times are independent. Two important parameters of the system, i.e. MTSF and availability, have been studied graphically to observe the effect on them of correlation.     

Multibeam WDM-FSO System: An Optimum Solution for Clear and Hazy Weather Conditions

Free space optics has revolutionized the telecom industry through its exquisite data transfer capability and cost effectiveness. It proves out to be an excellent solution to the last mile problem and arduous digging of grounds for laying fiber optic cables. But atmospheric turbulences and obscure weather conditions limit the extensive use of this technology. This paper analyses the use of multibeam technology in enduring the effect of hazy weather on the FSO link by comparing it with the single beam technology. The results obtained from the multibeam system for clear and hazy weather conditions have been validated by using MATLAB codes.

     

Synthesis of Chevrel phase $$(\hbox {Cu}_{1.8}\hbox {Mo}_{6}\hbox {S}_{8})$$ in composite with molybdenum carbide for hydrogen evolution reactions

Sustainable hydrogen generation from water electrolysis using renewable energy sources is the most promising pathway for future energy and hydrogen economy. Here, the Chevrel phase \((\hbox {Cu}_{1.8}\hbox {Mo}_{6}\hbox {S}_{8})\) was synthesized in composite with \(\hbox {Mo}_{2}\hbox {C}\) and good hydrogen evolution activity in acidic media has been demonstrated. Bundles of nanowires were formed in the templated synthesis route. The composites were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and elemental analysis. Detailed electrochemical analysis reveals that MCS-Cu50 composite exhibits higher hydrogen evolution reaction (HER) activity with \(71.4\,\hbox {mA}\,\mathrm{cm}^{-2}\) current density at an overpotential of 400 mV. It requires 250 mV overpotential to produce \(10\,\hbox {mA}\,\mathrm{cm}^{-2}\) current density for HER.     

Looking back,and ahead: The Panama Convention after 30 years

The pullout feature returns with history and future practice surrounding the Panama Convention. Helena Tavares Erickson, Preeti Gupta and Philip Sutter, of New York, provide tips for corporate counsel facing actions under the controlling arbitration treaty for U.S. companies doing business in Latin America.