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Measurements are reported on the inter-diffusion coefficients of benzene, thiophen, pyridine, piperidine and ietrahydrothiophen vapours in binary systems with hydrogen, nitrogen and oxygen. Previously published results on diffusion coefficients for cyclohexane and on the viscosities of the vapours together with new viscosity measurements for piperidine and tetrahydro-thiophen have been combined with the diffusion data to evaluate collision diameters for this family of cyclic molecules.Assuming collision diameters obtained from viscosity, a Lennard-Jones 12 : 6 potential has been applied to the measured diffusion coefficients to obtain a value of thc intcraction parameter €12 referring to interactions between unlike molecules. Comparjson of values of €12 with those calculaied from viscosity measurements using the usual combining rules for intermolecular potentials reveals discrepancies for all these binary systems.A more exact form of the combining rules has been derived and used to calculate €12. Agreement between parameters based on viscosity and diffusion is improved in the cases of the measurements with nitrogen and oxygen. These now yield self-consistent values for diffusion from which other collision processes may be calculated quite accurately. Even with the more exact combining rules, most of the cyclic molecules still show abnormally large diameters in collisions with hydrogen, described as the " hydrogen effect ".Measurements of the inter-diffusion coefficients of various hydrocarbons with hydrogen, nitrogen or oxygen have been previously reported,l covering a range of paraffin hydrocarbons from C5 to Clo and a number of unsaturated C6 hydrocarbons. The diffusion coefficients can be expressed in terms of kinetic theory as functions of the mass, temperature, a collision diameter cr, and an attraction potential E . Depending upon the particular form of interaction potential assumed to act between molecular centres, corresponding values of the collision diameter can be calculated. Gas kinetic theory indicates that the correct form of intermolecular potential should be one in which the same value of the collision diameter satisfies the equations for all the diffusion coefficients and also satisfies the equations for viscosity.From the previous work it has been found that the use of conventional intermolecular potentials, such as the rigid sphere or the Lennard-Jones 12 : 6 potential, cannot be made to satisfy the experimental results for viscosity and all the diffusion data. An outstanding discrepancy is that collision diameters calculated from diffusion measurements on hydrogen+ hydrocarbon systems usually appear to be anomalously large on the basis of the two-parameter 12 : 6 potential. This discrepancy has been termed the " hydrogen effect " and may be due to the small mass of the hydrogen and hence its anomalous energy transfer effects.The present research deals with a group of molecules, benzene, pyridine and thiophen and their fully hydrogenated derivatives whose cyclic structures are more compact than...

Dispersion of sound has been com pared for ethylene and tetradeutero-ethylene. Relaxation times of 0.26 and 0.14 u s for these molecules follow the general trend with molecular frequencies predicted by theory. A quantitative account of th e observed ratio 1:2 of relaxation times can best be given by introducing the notion of ‘complex collisions’ and by abandoning the concept that the rate of activation of the lowest vibrational mode fully controls the rate of activation of higher modes. Small amounts of C 2 D 4 or C 2 D 2 H 2 act as energy transfer catalysts for ethylene. Both H 2 O and D 2 O likewise act as catalysts, approximately to the same extent. Theoretical interpretations of these findings are discussed.

A study was conducted at a native chicken cum pig farm in Kanyakumari District, Tamil Nadu, India, to evaluate its economic feasibility. The native chicken unit yields regular income to the farmer, where the adult chickens, eggs, and day-old chicks are sold to local households on a demand basis at a premium prize. The poultry unit operates at a yearly benefit-cost ratio (BCR) of 3.92, which is attributed to the scavenging nature of the native birds, thereby reducing feed costs. The birds scavenge on maggots produced in the manure pit of the piggery unit, which satisfy the protein requirements of the birds. On the other hand, the piggery unit provides supplementary income to the farmer. The pigs are maintained on swill feed with no additional feed cost. The study demonstrates the feasibility of similar integrated farms with significant production and economic potential.