Hamiltonian cycles in polyhedral maps

We present a necessary and sufficient condition for existence of a contractible, non-separating and non-contractible separating Hamiltonian cycle in the edge graph of polyhedral maps on surfaces. We also present algorithms to construct such cycles whenever it exists where one of them is linear time and another is exponential time algorithm.     

Thermal degradation kinetics and reaction models of 1,3,5-triamino-2,4,6-trinitrobenzene-based plastic-bonded explosives containing fluoropolymer matrices

In this article, thermal degradation behavior of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)-based plastic-bonded explosives (PBXs) bonded with a different fluoropolymer matrices namely indigenous poly(vinylidene fluoride-chlorotrifluoroethylene) (FKM), FK 800, fluoroplastic F-32L and fluororubber SKF 32 was investigated through non-isothermal thermogravimetric analysis (TG) technique under nitrogen atmosphere. It was observed that the mass loss of PBXs containing FKM and FK 800 matrices occurred in three steps. The mass loss of PBXs containing fluoroplastic F-32L and fluororubber SKF 32 occurred in two steps. Kinetics were investigated through non-isothermal TG at different heating rates for the first step of degradation by means of model-free Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) methods. The activation energies calculated by applying FWO method are in good agreement and very close to those obtained by KAS method. The results revealed that the effect of the polymer matrices on the thermal degradation reaction of TATB was significantly observed especially different outcomes of kinetic parameters. The reaction models for degradation were also studied by Criado method. The reaction models are probably best described by the power law and diffusion models.     

Measurements of atmospheric electrical conductivities during the total solar eclipse of 22 July, 2009

The effect of total solar eclipse on atmospheric conductivities has been studied. Continuous measurements of both types of positive and negative electrical conductivities and some meteorological parameters in conjunction with the total solar eclipse of 22 July, 2009 were made from 21 to 23 July, 2009 at Roorkee (29°52′ N, 77°53′ E, 275 m above sea level). Roorkee observed 90% maximum obscurity of eclipse since it was close to the path of totality. The event started from 05:28 AM IST and ended at 07:42 AM IST with the total eclipse at 06:30 AM IST. Considerable increase of both positive and negative conductivities were recorded during the eclipse with respect to those made on any other day. Increase in relative humidity and decrease in temperature were also observed during the period of eclipse.     

Dual-path handheld system for cornea and retina imaging using optical coherence tomography

Optical Review - A dual-path handheld system is proposed for cornea and retina imaging using spectral domain optical coherence tomography. The handheld sample arm is designed to acquire two images...     

Distribution of trace elements in flowing surface waters: Effect of seasons and anthropogenic practices in India

This study reports the distribution of Cr, Ni, Cu and Pb in waters, sediments, macrophytes and fish of the Yamuna River’s patch in Delhi (India). This is one of the most polluted stretches of rivers in the world. Water from this river is used fosr irrigation, industrial and domestic purposes, including drinking water. The effects of season and anthropogenic practices were identified. Almost zero dissolved oxygen and high levels of lead and phosphate indicate the polluted state of the aquatic system. The enrichment factors in sediments (with respect to reference site) vary in the range of 0.60–82.9% (Cr), 1.40–90.5% (Ni), 1.00–85.3% (Cu) and 3.80–86.6% (Pb). The toxic effects due to Ni and Pb could frequently be visible in aquatic life as their values fall above the probable effect level (36 mg Kg^?1 for Ni and 91.3 mg Kg^?1 for Pb). The metal contents in the macrophyte (Eichhornia crassipes) and the fish (Oreochromis niloticus) generally increase in the summer season. Cu and Pb accumulate preferentially in E. crassipes. The fish from these waters is unsuitable for human consumption as the levels of Cr, Cu and Pb are above the recommended limits. Significant spatial variations in parameters of water and sediments were confirmed via one-way analysis of variance. The Pearson’s correlation analysis suggests a common source of some of the metals. Principal component analysis highlighted domestic, and industrial waste and coal-fired thermal power plants as the metal sources. This study might act as a benchmark for other investigations focused on similarly affected surface aquatic systems due to agricultural and industrial activities.     

A convergent approach towards the synthesis of the 2-alkyl-substituted tetrahydroquinoline alkaloid (−)-cuspareine

A convergent approach towards the synthesis of the 2-alkyl-substituted tetrahydroquinoline alkaloid (?)-cuspareine via enantiospecific construction of the (R)-benzyl 2-formyl-3,4-dihydroquinoline-1(2H)-carboxylate. We have achieved an efficient enantiospecific synthesis of (?)-cuspareine starting from known key starting materials. The reactions employed for individual transformations are simple and high yielding, and the strategy could potentially be easily extended.