In the present modified version of magnetic float densitometer, an auto-circuit, comprising of 12V auto-on and 1.5V auto-off device, having a time delay of about 20 and 10 sec. respectively, is incorporated to regulate the electric currents in the solenoids. The currents in the main and pull down solenoids are simultaneously controlled by one switch only. This makes the magnetic float densitometer easy operating without affecting the mathematical working of the instrument.

The present study reports the effect of compression ratio on the performance and exhaust emissions of variable compression diesel engine using soyabean oil and it's methyl ester.Results show that brake specific fuel consumption , exhaust gas temperature and smoke density are increased but brake thermal efficiency is decreased both in Soyabean - diesel oil blend and esterified Soyabean oil compared to 100 % diesel operation at two different compression ratios.Engine used for the present work is 5 H.P. ,1500 rpm single cylinder diesel engine of compression ratio 16. Keywords: , , Esterification & Compression ratio ( CR )

4-hydroxybenzylidenecarbamide (ligand) has been synthesized by combination of 4-hydroxybenzaldehyde and urea. The ligand containing hydroxyl, imine and amide functional groups were characterized using IR, NMR spectroscopic techniques. The co-immobilization of cetyltrimethylammoniumbromide (CTAB) and ligand on glassy carbon electrode is achieved by drop coating technique. The ligandCTAB modified glassy carbon electrode is characterized by using ferro/ferricyanide redox system via electrochemical techniques such as cyclic voltammetry, chronoamperometry and chronocolumetry. Adsorption of these compounds onto glassy carbon electrode gives rise to stable redox probe for ferro/ferricyanide system. Active surface areas of bare GCE, CTAB/GCE, ligand/GCE and ligand-CTAB/GCE are calculated by using cyclic voltammetry and chronoamperometry techniques. The surface concentration of electroactive molecules on the different types of electrodes is calculated by using chronocoloumetry technique.