Diels-Alder adducts from safflower oil fatty acids

Methyl esters of alkali-isomerized safflower oil fatty acids after elaidinization with sulfur were treated with styrene in the presence of hydroquinone, with or without solvents. A combination of column chromatography and gas liquid chromatography techniques was employed for the estimation of the methyl esters of unreacted fatty acids, Diels-Alder adduct and polymers in the reaction products. Maximum yield of the Diels-Alder adduct (26.6%) was obtained when the elaidinized methyl esters of the fatty acids were treated with 1.5 moles of styrene per mole of linoleic acid in safflower oil fatty acids at 200–210 C for 6 hr. The methyl ester of the adduct was isolated in about 90% purity from the reaction product by vacuum distillation followed by solvent fractionation. The butyl ester of the adduct and the epoxy derivative of the methyl ester adduct were prepared and characterized.     

Special Features in Powder Preparation, Pressing, and Sintering of Uranium Dioxide

Nuclear ceramic grade UO₂ powders are usually prepared by the wet chemical ammonium diuranate route. The powders are pressed and sintered before incorporation into nuclear fuel assemblies. The processing is complex at all stages and the specifications are stringent. In powder preparation, slow addition of the precipitating reagent at a low temperature is recommended. The conditions for the drying of the precipitate, calcination and reduction are chosen to result in an agglomerate free, fine and porous powder that does not require milling or binder addition and is capable of being compacted and sintered to desired density with a homogeneous microstructure. The pressing conditions are chosen to give compacts that are free from defects such as cracking, chipping and end-capping. Sintering conditions are such that desintering, bloating, weathering and nitriding are avoided. Some insights that have been gained in powder preparation, pressing and sintering are presented in this paper. The relationship between powder characteristics and pressing and sintering properties is described.     

Diels-Alder Adducts from Safflower Oil Fatty Acid Methyl Esters Using Aldehyde Dienophiles

The Diels-Alder reaction between alkali conjugated and elaidinised safflower oil fatty acid methyl esters and acrolein, crotonaldehyde and cinnamaldehyde was studied under various experimental conditions. A combination of column chromatography and gas liquid chromatography techniques was employed for the estimation of the methyl ester of the unreacted fatty acids, Diels-Alder adducts and polymeric and other materials in the reaction products. The maximum yields of the Diels-Alder adducts with acrolein, crotonaldehyde and cinnamaldehyde were 40.2, 44.4 and 52.2 per cent respectively when the reaction is carried out at 240°C for 6–8 hours using 2 moles of dienophile. The methyl esters of the adducts were isolated in about 90 per cent purity from the reaction products by distillation under reduced pressure followed by solvent fractionation.     

Strengthening mechanisms in alloys

Metals can be strengthened by methods appropriately combined to meet the operating conditions. In this ‘alloy design’, effort, we are guided by semi-quantitative relations that have been developed over the years and which relate the efficacy of the strengthening methods to the deformation modes. In this paper, the basic concepts are expanded with specific reference to dislocation glide, diffusional creep, grain boundary sliding and high strain rate deformation.     

Analysis of a replicated data base

In this paper we study the performance characteristics of a replicated data base under two different updating policies. In the synchronous case requests for any replications of the data base can be processed only if no copies of data base are being updated due to a previous write request, whereas in the non-synchronous case read requests are allowed to be processed at any time if there is a free data base copy. We formulate a queueing theoretic model of the system assuming a Poisson arrival process for both read and write requests. This model is then solved using the matrix geometric solution method and the relevant performance metrics are derived and analyzed.