Microwave assisted Wolff rearrangement: A facile method for the synthesis of Fmoc-β-amino acids

The Wolff rearrangement of α-diazoketones, derived from Fmoc-α-amino acids, under no base conditions on exposure to microwave irradiation for 40 to 60 sec to Fmoc-β-amino acids with retention of configuration in good yield (91-95%) is described

N-Silylation of amines and amino acid esters under neutral conditions employing TMS-Cl in the presence of zinc dust

An expedient synthetic approach to N-silylamines has been developed. The protocol, using TMS-Cl/zinc dust instead of BSA, is useful for the conversion of amines or amino acid esters to the corresponding silyl derivatives, followed by acylation with an acyl chloride or Fmoc-amino acid chloride to give the corresponding amide or peptide. This procedure, affording products in good to excellent yields, is also efficient for the coupling of sterically hindered amino acids like α,α-dialkylamino acids and NMe-amino acids. Further, the use of an equimolar quantity of organic base, such as Et 3N/pyridine, is circumvented. © 2005 Published by Elsevier Ltd

Direct synthesis of Fmoc protected amino acid hydroxamates from acid chlorides mediated by magnesium oxide

The synthesis of Fmoc protected amino acid hydroxamates using Fmoc-amino acid chlorides and magnesium oxide is described. The method is simple and efficient, results in complete conversion, and gives good yields and satisfactory purity. © 2003 Elsevier Science Ltd. All rights reserved

On the occurrence of Acanthaster planci (the crown-of-thorns) at Minicoy Atoll.

The predation of coral-polyps by the multi-armed star fish Acanthaster planci is identified during the last two decades as a major biological factor that causes large scale death to reef corals at several parts of the Indo-Pacific. During a recent visit by a team of scientists from Central Marine Fisheries Research Institute,the presence of this star fish in the lagoon of Minicoy Atoll was noticed in November, 1979.Many control measures of star fishes have been practised elsewhere in the Pacific. However, hand-picking of the adults with the aid of pointed spears and killing them with formalin or ammonia solution is the most eifective.Careful search among the corals is required, since the crown-of-thorns hide under the crevices during day time

Primary productivity in the nearshore waters of Vizhinjam, Trivandrum

Primary productivity and related aspects in the Vizhinjam Bay and adjacent open sea were investigated from April 1983 to March 1984. The rate of production was estimated by determining O by the light and dark bottle method. The gross production in Vizhinjam Bay ranged from 114 to 672 mg C/m3/day and in the open sea station it varied from 185 to 739 mgC/m3/day. The range in the net production was from 32 to 429 mg C/m3/day in the Bay and from 114 to 411 mg C/m3/day in the open sea station. High values of phosphate were recorded in September and October in the Bay and during August- November in the open sea. The nitrite and nitrate values were low when compared to those reported earlier from Vizhinjam Bay. The monthly variations in surface production were not significantly related to either temperature or salinity. The correlation between primary production and nutrient concentration was discussed

Fmoc-amino acid azides in peptide synthesis

Fmoc-amino acid azides can be prepared from the corresponding acid chlorides and sodium azide. All the compounds made have been obtained as solids in good yield and purity. They are found to be shelf stable at room temperature for longer periods. Their storage at room temperature does not lead to the formation of isocyanates. Employing them as coupling agents, the synthesis of a few dipeptides is described

Zooplankton in relation to hydrography and pelagic fisheries in the inshore waters of Vizhinjam, Trivandrum

The seasonal fluctuations in the total plankton biomass and in the abundance of major zooplankters in the Vizhinjam Bay and the adjacent open sea were studied for two years from February 1980 to January 1982 in relation to the hydrography and the pelagic fisheries of the region. Copepods formed the major component of the zooplankton community for the greater part of the year. The other dominant groups were decapod larvae, cladocerans and chaetognaths. During certain months copepods were outnumbered by cladocerans, which swarmed during monsoon months only. Decapod larvae, appendicularians, fish eggs, fish larvae and Lucifer exhibited a sharp decline during south-west monsoon period. The revival started with the north-east monsoon and these groups attained their peak abundance in different months. The total zooplankton volume did not exhibit significant relationship with any of the hydrographic parameters investigated. The peak periods in the zooplankton biomass were found to coincide with the peak seasons of pelagic fisheries in both the years of collection. The importance of zooplankters in the study of the pelagic ecosystem in general and the fisheries in particular is pointed out

Hydrological features of the Arabian sea off the Northern and central west coast of India During 1964 winter

The hydrographic features prevailing along the northern and central west coast of India during the early part of winter 1964 are discussed. A weak northward gradient in temperature north of 17°N and an eastward gradient south of it is noticed. The thermocline is found at shallower depths in the northern regions. A steady increase in the salinity is observed northward, the maximum being off Bombay. North of 17°N the flow is mainly eastwards which deflects towards south with increase in depth. At SO m a continuous weak southward drift is noticed. More or less uniform distribution is foimd in the dissolved oxygen content at surface and 20 m depth, but at 50 m depth eastward gradients are noticed. Sharp decrease in dissolved oxygen values occur from the top of the thermocline and the oxygen minimum layer is conspicuous in all the sections. The nature of the isotherms and the isolines of oxygen indicate the presence of upwelling in the region off Bombay. The total phosphorus content is much less in the region between 15°N and 18°N with higher values further south and north of these latitudes. The patterns of distribution of dissolved oxygen and total phosphorus contents show an inverse relationship. A westward gradient in the phosphorus values is seen at 50 m depth

Adsorption of Crystal Violet Dye from Aqueous Solution Using Ricinus Communis

Carbon prepared from Ricinus Communis Pericarp (RCP) was used to remove a crystal violet dye from aqueous solution by an adsorption technique under varying conditions of agitation time, dye concentration, adsorbent dose and pH. Adsorption is influenced by pH, dye concentration, carbon concentration and contact time. Equilibrium was attained with in 60 min. Adsorption followed both Langmuir and Freundlich isotherm models. The adsorption capacity was found to be 48.0 mg/g at an initial pH of 6.8±0.2 for the particle size of 125–250 μm