ISSUE 180: APRIL - JUNE, 2005

LOCAL CHAPTER ACTIVITIES
The Darashaw Nosherwanji Wadia Medal Lecture (2004)
Professor Asoke Mookherjee, FNA, delivered The Darashaw Nosherwanji Wadia Medal Lecture, 2004 on “Relationship between ‘reserve’ and ‘Clarke Value’ of ore metals- A mirage?” at Jadavpur University, Kolkata, on the 15th February, 2005.Professor Mookherjee in his lecture critically evaluated the once highly debated notion that there is a linear relationship between logarithms of ore reserves of commonly used metals in the world and logarithm of their Clarke Values(average bulk crustal abundance). This apparent correlation is somewhat surprising since Clarke Values are fundamental geochemical attribute of the crust, while ‘reserves’ of metals are a time-, place, and technology-dependent concept.Professor Mookherjee observed that the controversy arose because of two factors: first, inappropriate parameters were sought to be correlated, and, secondly, several crucial aspects of ore reserve inventory were not taken into account.		  
Professor K Rangadhama Rao Memorial Lecture
Professor N. Chandrakumar, FNA delivered Professor K. Rangadhama Rao Memorial lecture entitled ‘Coherence Transformations and their Applications in NMR Spectroscopy and Imaging’. The summary of his recent research in developing NMR coherence transformations for a variety of applications including spectroscopy, imaging and quantum computing is as follows:
                                       The state of a spin ensemble is characterized by a density operator whose diagonal elements correspond to relative populations, while off-diagonal elements represent coherences. NMR experiments create coherences whose precession reflects the parameters of the spin system, eg.,shifts and couplings. Coherence transformations are brought by resonant radio frequency pulses, which effect unitary transformations; relaxations, which are dissipative processes, represent non-unitary transformations of the spin system. Bounds on coherence transfer amplitudes under unitary transformations may be set up in terms of eigen value arrays of the respective source and target states.The one-dimensional INADEQUATE BR sequence resulted in 41.4% improved sensitivity compared to normal 1D INADEQUATE. Which is also more efficient in practice than INADEQUATE CR in 1D mode, having but half the duration the latter and half the number of pulses. The CR and BR sequences both transform double quantum coherence with single transition selectivity; however, the BR sequence also has superior ‘bandwidth’ to variations in the coupling constant J. Experimental demonstrations of the performance of the sequences included.He described briefly the application of coherence transformation to molecule selective two- and threedimensional imaging with distinctive contrast; this method also results in improved resolution per unit applied field gradient in the phase encode directions. Next described was DISSECT sequence, for diagonal suppressed correlation spectroscopy in the in vivo context. The J cross-polarization experiment was then described, for molecule selective imaging employing heteronuclear couplings. It was shown that multi-spin correlations could play a significant role in these experiments for spin systems with three or more coupled spins; the resulting image pixel intensities could actually exceed unitary bounds obtained by neglecting multi-spin correlations. Applications of these experiments, designed around the PRAWN family of pulse equences, were demonstrated to plant seedlings in vivo. The sequences with very low power deposition easily satisfy SAR requirements. Finally, the application of rotating frame coherence transformations to initialization, gating and readout in the context of NMR quantum computing were described. In particular, the SWAP operation was shown to be performed by isotropic mixing in half the gating time required by refocused INEPT, resulting additionally in significantly reduced decoherence effects. It was also shown that the result of an operation such as SWAP may be readily read out in 1D fashion rather than the conventional 2D fashion,and can be further improved in sensitivity available per unit time by application of Hadamard type multiplex strategies.
 

Professor Ashok Mookherjee (R) is receiving the Wadia Medal from Professor Supriya Roy with Profesor Samir Bhattacharya on his left
Instead of average concentration in the bulk continental crust, it will be better to use average abundance in the upper continental crust, since the latter is the repository of all ores and abundance values of several elements differ by factors of 2-5 in the two regimes. Secondly, ‘reservebase’ is a much more appropriate choice than ‘reserve’ as the other parameter for correlation.
                    At least four crucial factors of reserve inventory have been totally ignored: the recycling perspective of reserves already formed; extremely variable ‘enrichment factor’ required by different metals to be concentrated into ore;differential adaptability and insularity of some metals;recovery of some metals only as byproducts.

If all these aspects are considered, it can be shown that the upper continental crust Clarke Values exerts a very strong first order control on the reserve base of metals. A second order control imposed by the differential preservation potentials of their habitats is superposed that
shifts the distribution patterns along parallel lines implying dominant persistence of the primary control.

Professor Satyendranath Bose Medal (2004)
The award ceremony for the Indian National Science Academy S.N. Bose Medal to Professor Ashoke Sen FNA,FRS was held at the Harish-Chandra Research Institute, Allahabad on 18th April 2005.

 


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