Mapping the potential energy surfaces for ring-closing metathesis reactions of prototypical dienes by electronic structure calculations

The potential energy surfaces for ring-closing metathesis reactions of a series of simple alpha,omega-dienes which lead to 5-10 membered ring products, have been explored using density functional theory methods. We have investigated both the conformational aspects of the hydrocarbon chain during the course of the reactions, as well as the stationary structures on the corresponding potential energy surfaces. Extensive conformational searches reveal that the reaction proceeds via the conformation that would be expected for the cycloalkene product, though most unexpectedly, cyclohexene forms via complexes in boat-like conformations. The M06-L density functional has been used to map out the potential energy surfaces, and has identified metallocyclobutane fragmentation as being generally the highest barrier along the pathway. The structural variations along the pathway have been discussed for the reactant hydrocarbons of differing chain length to identify points at which cyclisation events may begin to affect reaction rates. Our study provides an excellent starting point from which to begin to learn about the way RCM reaction outcomes are controlled by diene structur

Live food organisms – Artemia Part II - Artemia cyst and biomass production

The brine shrimp, Artemia a crustacean which is naturally found in hypersaline waters throughout most of the world, has become the most important source of live-feed for the last twenty years. All its life stages such as cysts after decapsulation, freshly hatched nauplii, juveniles, preadults and adults, are used as live-feed according to the feed-size requirement of the predator. Artemia decapsulated cysts and freshly hatched nauplii form as ideal food for the larvae of cultured fish and crustaceans in their hatchery phase while juveniles, pre adults and adults form as suitable diet for prawn/fish juveniles in their nursery phase

Changing dimensions of single European market : implications for the non-member countries : a case study on India's textile and clothing exports

The implications of the single European market on India's exports of textile and clothing industries to the EU can be summarised in the following four statements: 1. The trade creation effect has been witnessed for many of India’s textile and clothing exports. It is the consumption effects, rather than the efficiency related effects, that stimulated the trade creation effect for India's exports to the EU. The benefits of the trade creation for India's textile exports are absolute as India continued to maintain its role as a leading textile exporting nation to the EU. Since India's textile exporters did not witness any intense competition from the geographically adjacent non-member countries, or from the distant non-member countries, the Indian textile exporters continued to reap the benefits of the trade creation effect in the single European market. Even the leading distant non-member countries, which are traditional exporters like China, did not pose greater competition to India's textile exports to the EU. 2. There has been a trade diversion effect in selected product categories. This is particularly true in the case of garment exports. The arrival of the imports from Central and East European countries constituted direct competition to India's exports to the EU. There has also been an intense competition among the garment exporting countries. This is particularly true in the case of the geographically adjacent non-member countries. These countries exploit the maximum benefits offered to them by the EU's OPT with these countries. This is facilitated by the member countries' preference to keep their textile industries at home. 3. There has not been any trade suppression effect witnessed in the EU for India's textile and clothing exports. Though the traditional arguments of customs union theory expected the trade suppression effect to be witnessed in the enlarged market, this has not been witnessed in the European textile and clothing industries. Two reasons could explain the lack of trade suppression effect in the EU. The member countries' success in the OPT dissuade them from resorting to the domestic production of the same goods, which could be successfully produced and imported from the geographically adjacent non-member countries. Though there have been protectionist tendencies in many of the member countries to insulate their textile and clothing industries against low-cost imports, they have not resulted in the trade suppression effect in the EU. Even though the member countries witness a decline in their textile and clothing industries consistently, there has not been any effort to replace low-cost imports by domestic production. This is mainly because of the liberal trade regime, imposed on the developed member countries under the multilateral trade negotiations, which make trade in this industry more competitive. 4. However there has been the trade contraction effect witnessed in one particular product category. The trade in silk woven fabrics witnessed an overall fall in its trade both within and without the EU. But this could not be attributed to the formation of the single European market. The developed member countries' changing fabric preference from silk towards artificial fabric could be attributed to the fall in the EU's overall trade in this product category. Nevertheless the EU's trade contraction effect did not have any adverse effect on India's exports because India is the leading exporter in this product category (accounting for about 46 per cent of extra-EU imports in 1999)

Live food organisms – Artemia Part I. Artemia cysts and their utilization

Extensive literature reveals that only very few organisms have been utilized as live feed of which the brine shrimp Artemia, is the most important one. In the growing aquaculture industry, a great demand exists for Arteinia cysts which form as dried inert food source. In these cysts embryos, after development upto gastrula stage, are kept in diapause. The cysts are brownish in colour and mi^asure about 0.3 mm in diameter. When dehydrated, they are biconcave in shape

Direct Evidence of Mg Incorporation Pathway in Vapor-Liquid-Solid Grown p-type Nonpolar GaN Nanowires

Doping of III-nitride based compound semiconductor nanowires is still a challenging issue to have a control over the dopant distribution in precise locations of the nanowire optoelectronic devices. Knowledge of the dopant incorporation and its pathways in nanowires for such devices is limited by the growth methods. We report the direct evidence of incorporation pathway for Mg dopants in p-type nonpolar GaN nanowires grown via vapour-liquid-solid (VLS) method in a chemical vapour deposition technique for the first time. Mg incorporation is confirmed using X-ray photoelectron (XPS) and electron energy loss spectroscopic (EELS) measurements. Energy filtered transmission electron microscopic (EFTEM) studies are used for finding the Mg incorporation pathway in the GaN nanowire. Photoluminescence studies on Mg doped GaN nanowires along with the electrical characterization on heterojunction formed between nanowires and n-Si confirm the activation of Mg atoms as p-type dopants in nonpolar GaN nanowires.Comment: 29 pages, 6 figures, journa