Catalytic isomerization of safflower oil with rhodium complexes

Cationic rhodium (I) complexes of the type [(NBD)RhL₂]⁺ ClO₄ ⁻ (NBD, norbornadiene; L, triphenyl phosphine or diphenyl phosphino ethane) have been studied as catalysts for the isomerization of methyl linoleate and safflower oil. The catalysts gave very good yields of conjugated products with both oil and methyl linoleate. Isomerization could be carried out under very mild conditions (55–65 C, 1 atm N₂). Although the catalyst undergoes transformation in the course of the reaction, it maintains its catalytic activity. In fact, the catalysts isolated from the reaction with safflower oil were recycled with practically no loss of activity.     

Assessment of groundwater resources in Kuwait using a finite difference model

Usable groundwater resources have strategic significance, given the arid climate of Kuwait. Assessment of groundwater resources through modelling is considered of paramount importance for sustained long‐term development of this resource. A conceptual model of the regional hydrogeology of the area has been developed based on the available data. Three aquifers were recognized within the Dammam Formation‐Kuwait Group sequence. VTDN software was used for numerical simulation of the groundwater flow in this aquifer system under steady‐state conditions. Calibration runs made to date suggest that the model is sensitive to the vertical coefficient of permeability of the aquitards and the horizontal transmissi‐vities of the aquifers. The water balance achieved shows that the contribution from the natural recharge from precipitation is insignificant.     

The effects of pressure and temperature on the catalytic oxidation of hydrogen sulfide in natural gas and regeneration of the catalyst to recover the sulfur produced

The influence of pressure up to 5600 kPa and temperature up to 175 °C on the oxidation of low concentrations of H₂S in natural gas was studied in a fixed bed reactor over an activated carbon catalyst. Operation of this system at 5600 kPa provides higher catalyst activity (virtually 100% H₂S conversion) over a longer period of time and with lower selectivity to SO₂ than when operated at atmospheric pressure. The desorption of sulfur from a loaded catalyst occurs first from the macropores (> 100 nm) of the catalyst which contain a substantial portion of the sulfur load and then from the micropores (< 100 nm). This study also indicated that the sulfur recovery process is both rapid and effective at 327°C.     

Oxidation of oleanolic acid ofAvicennia officinalis leaves to oleanonic acid in the natural environment of Sunderban mangrove ecosystem

Oleanolic acid, a major component pentacyclic triterpene in the leaves ofAvicennia officinalis was found to be oxidized to oleanonic acid in the natural environment of Sunderban mangrove forest.Presented in part at the All India Symposium on Marine Plants, held on Oct. 30–Nov. 1,1983 at National Institute of Oceanography Dona Paula, Goa India.     

Occurrence of wax esters and 1-O-alkyl-2,3-diacylglycerols in goat epididymal sperm plasma membrane

Two unusual lipid classes were detected by thin-layer chromatography in the neutral lipids derived from goat cauda-epididymal sperm plasma membrane. The lipids were identified as wax esters and 1-O-alkyl-2,3-diacylglycerols based on chromatographic properties, identity of their hydrolysis products, and infrared/¹H nuclear magnetic resonance spectral evidence. The membrane containedca. 3 and 5 μg/mg protein of wax esters and alkyldiacylglycerols, respectively. The relative proportions of wax esters and alkyldiacylglycerols in the total neutral lipids were 1.5% and 2.4%, respectively. The lipids contained fatty acids with chain lengths of C₁₄ to C₂₂. The major fatty acids of the wax esters were 14∶0, 16∶0, 16∶1ω7, 18∶0 and 18∶1ω9. The fatty acids in alkyldiacylglycerol were 16∶0, 18∶0, 22∶5ω3 and 22∶6ω3. Alkyldiacylglycerol was particularly rich in docosahexaenoic acid 22∶6ω3) representing 30% of the total fatty acids. The alcohols of wax ester were all saturated with C₂₀–C₂₉ carbon chains. The deacylated products derived from alkyldiacylglycerols were identified as hexadecyl, octadecyl and octadec-9′-enyl glycerol ethers.     

Fatty acids from Macoma sp. of bivalve mollusc

Fatty acids of the total lipids of flesh and hepatopancreas of Macoma sp. have been determined. The level of 20:5w3 (ca 17%), a biologically important fatty acid, was found to be considerably high. Other major component fatty acids were 16:0, 16:1, 18:1 and 22:4w6. High levels of 22:5w6 (8%), 22:5w3 (8%) and 22:6w3 (ca 15%) were found in flesh lipid. Nonsaponifiables were also high (28–30%). Alkyl ether acyl glycerols were found in flesh (1.3%) and hepatopancreas (3.8%).     

A parallel sorting algorithm for a novel model of computation

The computational complexity of a parallel algorithm depends critically on the model of computation. We describe a simple and elegant rule-based model of computation in which processors apply rules asynchronously to pairs of objects from a global object space. Application of a rule to a pair of objects results in the creation of a new object if the objects satisfy the guard of the rule. The model can be efficiently implemented as a novel MIMD array processor architecture, the Intersecting Broadcast Machine. For this model of computation, we describe an efficient parallel sorting algorithm based on mergesort. The computational complexity of the sorting algorithm isO(nlog² n), comparable to that for specialized sorting networks and an improvement on theO(n ^1.5) complexity of conventional mesh-connected array processors.