Synthesis of quinine and quinidine using sulfur ylide-mediated asymmetric epoxidation as a key step

The epoxidation of meroquinene aldehyde with a chiral sulfur ylide as the key step in the synthesis of quinine and quinidine is described. The epoxidation reactions proceed under reagent control with high selectivity and good yield. The effect of sulfide and ylide substituents on the stereochemical outcome of the reaction is discussed.     

Analysis of refractometric fiber optic state-of-charge (SOC) monitoring sensor for lead acid battery

In situ monitoring of the state of charge (SOC) of lead acid battery is important to understand the residual electrical energy. Usage of battery reduces the charge content of the active electrolyte which in turn changes its refractive index. This paper reports refractometric fiber optic sensor developed for on-line monitoring of SOC. The SOC is monitored during discharging phases of the battery using the developed fiber optic sensor probe along with terminal voltage, temperature and depth of discharge using a LABVIEW based data acquisition system. The paper gives the working principle, design and construction details, results and calibration of the fiber optic sensor (FOS) probe. The in situ monitoring capability of the developed FOS is demonstrated in comparison with the contemporary off-line methods of specific gravity and terminal voltage measurements.     

Comparative evaluation of three alpha-hydroxycarboxylic acids for the separation of lanthanides by dynamically modified reversed-phase high-performance liquid chromatography

The resolution for the three homologues of alpha-hydroxycarboxylic acids viz. lactic acid, alpha-hydroxyisobutyric acid (alpha-HIBA) and alpha-hydroxy-alpha-methylbutyric acid (alpha-H-alpha-MBA), was compared for the individual separation of 14 lanthanide elements under identical experimental conditions. Alpha-HIBA was found to be the best for separation of heavier lanthanides (Tb to Lu) while alpha-H-alpha-MBA led to a better separation for lighter lanthanides (La to Eu). All the 14 lanthanides were separated by gradient HPLC employing both alpha-HIBA and alpha-H-alpha-MBA so that there was reasonable resolution among all the peaks and the separation was completed in a short time.     

A palladium catalysed cyclisation-carbonylation of bromodienes: control in carbonylation over facile beta-hydride elimination

Conditions have been found for the efficient palladium mediated cyclisation-carbonylation of bromodienes to give gamma,lambda-unsaturated acids.     

Highly selective aziridination of imines using trimethylsilyldiazomethane and applications of C-silylaziridines in synthesis

Trimethylsilyldiazomethane has been found to add directly to N-sulfonyl (Ts and SES) imines to afford aziridines in good yields and high cis stereoselectivities. The silyl group can be substituted by treatment with a fluoride source and electrophiles again with high selectivity. Complete regioselectivity is observed in ring opening of these aziridines with nucleophiles.     

New concepts in early failure modelling

The problem of early failure modelling has been discussed comprehensively. Present models have been discussed and new models are suggested. A drawback of failure rate not being finite at t = 0 for some of the present models is eliminated in the suggested models.     

Reliability Evaluation by Network Decomposition

The method evaluates the reliability of large computer communication systems by systematic decomposition of the probabilistic graph of the system into two parts using an appropriate cutset. A technique is evolved for determining the conditional success events using both the node removal and connection multiplication methods for path enumeration. An example is solved to show the versatility of the method. The results of the example are verified by using an existing algorithm. The suggested method is general and computationally economical.