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Ramachandran Srinivasan (1933-2004)

[Srinivasan]Ramachandran Srinivasan, a well-known crystallographer, passed away on September 19, 2004. He had been associated with the Dept. of Crystallography and Biophysics, University of Madras for the past four decades. He was respected in India and abroad for his contributions to crystallography.

He was born on July 5, 1933 at Nannilam in Tamilnadu. His B.Sc. (Hon.) (1953) and M.Sc degrees (1954) were from the University of Madras. After completing his M.Sc. with distinction he joined the physics dept. of the University of Madras for a Ph.D. degree in X-ray Crystallography, under the guidance of G.N. Ramachandran.

Srinivasan was associated with G.N. Ramachandran during an exciting and productive period of theoretical crystallography and biophysics in India. In 1962 he visited the Cavendish Laboratory, University of Cambridge under a Commonwealth Fellowship Program. He became a full professor in 1964, one of the youngest professors in the history of the University of Madras. He became senior professor in the year 1972. He was the head of the Dept. of Crystallography and Biophysics from 1969 until his retirement in 1994. He was a visiting scientist at the Dept. of Biological Sciences, Purdue University in 1968 and he used this opportunity to write his famous book on “Fourier methods in crystallography”, which was co-authored by G.N. Ramachandran.

His research interests included theoretical crystallography, polytypism, structural biophysics, nuclear magnetic resonance, gemology and musicology. He published over 200 papers in national and international journals. He edited or wrote nine books and monographs.

He had a deep knowledge of Fourier transform theory and he used this knowledge to develop many new methods for recovering information (atomic sites) from imperfect electron density maps. He, along with G.N. Ramachandran and S. Parthasarathy, developed special Patterson and Fourier syntheses for use in crystal structure analysis. They showed that the phase angles have an overwhelming importance in revealing structure and that amplitudes play only a secondary role . His group proposed several weighting functions for the improvement of Fourier maps. These results are summarized in the monograph entitled “Fourier Methods in Crystallography” published in 1970 by John Wiley and Sons .

He was a pioneer in the application of staistical analysis of interactions to the solution of crystallographic problems. Useful results obtained by him included a test for centrosymmetry and derivation a probability distribution of structure factors from a pair of related crystals.

The probability distribution of Bijvoet differences, the statistical treatment of unobserved reflections in least squares refinement, and statistical tests for isomorphism in crystals are some of his other contributions to theoretical crystallography. He published 80 papers in the area of crystallographic statistics and a monograph with his colleague S.Parthasarathy, entitled “Some statistical applications in X-ray crystallography”.

He made significant contributions to the theory of anomalous dispersion. He was in one of the early groups of scientists who worked out the application of anomalous scattering to solve the phase problem. He pointed out that phases could be determined using multiple wavelength anomalous techniques as well as single wavelength anomalous scattering. He suggested that the phenomenon of isomorphism could be simulated with a single crystal by making use of the anomalous dispersion effect. This work lead to a review article on “Applications of X-ray anomalous scattering in structural studies” in Advances in Structural Research by Diffraction Methods (1972).

In the latter part of his career, he concentrated on structural biophysics. He proposed several new methods for characterization of biopolymers. The earlier method proposed by G.N. Ramachandran used two parameters, ϕ and φ, for characterizing a biopolymer. Srinivasan reduced this to one parameter and carried out extensive analysis of protein data based on this idea. He introduced a virtual bond concept for biopolymer characterization.

Srinivasan developed a solid state NMR laboratory from scratch and constructed a NMR spectrometer with the help of his students. His main contribution in this area was on line shape analysis using truncated moments, which finds use in motional studies in solid state NMR.

Srinivasan was a good administrator and commanded respect from his colleagues and subordinates. He steered the research program of the department for more than two decades after G.N. Ramachandran left the University of Madras. He maintained the eminence of the department and attracted significant funding from various agencies.

He was an elected fellow of the Indian Academy of Sciences (1968), Indian National Science Academy and Institute of Physics (London). He was a founding member of Tamil Nadu Academy of Sciences, and a committee member of the IUCr Teaching Commission, National Committee for Crystallography and the Indian Biophysical Society. He leaves behind a host of students, colleagues and friends whose lives he enriched for the past four decades. All will cherish his memory and his work will continue to inspire crystallographers the world over.

Vasantha Pattabhi