Vacuum stability in gauge theories

The vacuum behaviour in a quantum SU(2) gauge theory is investigated by calculating the one-loop contributions to the effective action in a covariant constant background field. It is found that the vacuum is stable against decay, for a particular nonzero value of the electric field, indicating a dynamical symmetry breaking.     

Temperature programmed desorption (TPD) of carbon monoxide from cobalt surfaces

Three different binding states of CO on cobalt surfaces have been identified by TPD studies. The energetics of these adsorption states and their relevance in Fischer-Tropsch synthesis are considered.

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CO - . -.

     

Chemical examination of Tylophora asthmatica—V Structure of tylophorinine

Tylophorinine, the minor alkaloid of Tylophora asthmatica, has been oxidized to yield 2,3,6-trimethoxyphenanthrene-9,10-dicarboxylic acid. A synthesis of the corresponding imide has been achieved. Desoxytylophorinine, obtained by hydrogenolysis of the alkaloid, has been synthesized. These results in conjunction with other degradation experiments have enabled the assignment of the structure XIV to tylophorinine.     

A differential thermal analysis study of homoionised bentonites

Homoionised bentonites were prepared from commercial bentonites with hydrochloric acid. The Atterberg limits and the DTA curves were determined for the homoionised and commercial bentonites. This study shows that DTA can be used as a method for differentiation between clays containing mono- and divalent cations.The authors thank Prof. K. S. Sankaran, Department of Civil Engineering, I. I. T., Madras, for his encouragement during the course of this work.