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B.E. Warren Diffraction Physics Award
Committee
The following have been appointed to Warren Award Committee:
Chair: Jerry B. Cohen, Dept. of Mater. Science and Engineering,
Northwestern University, Evanston, IL 60208. Bernard Wuensch,
Dept. Mater. Sci, MIT, Cambridge, MA, David L. Price, Argonne
National Lab., 9700 Cass Ave., Argonne, IL, Lieselotte Templeton,
1244 Brewster Dr., El Cerrito, CA 94530-2524.
New Homepage for Small Molecule SIG
The new home for the Small Molecule SIG Web Page is: http://www.che.uc.edu/krause/smallmolec.html
ACA Summer School Dates
The dates for next year's ACA Summer School in Athens, Georgia
are July 7 to July 19, 2000.
Gary Newton
George E. Brown, Jr.
Representative George E. Brown, Jr. (D-California) died July
15, 1999. The ACA presented its Public Service Award to Rep.
Brown at its Arlington Meeting in recognition of his support
for science in Congress. Rep. Brown joined the House Science
Committee in 1965 and had served both as Chairman and Ranking
Democratic Member of that committee. His efforts on behalf of
science and scientists will be missed.
ICDD Elects Distinguished Fellow
The International Centre for Diffraction Data is pleased to announce
that Professor Doctor Walter Eysel (Mineralogisches Institut
der Universit at Heidelberg, Germany) has been elected to join
the ICDD list of Distinguished Fellows. Professor Eysel has been
recognized by the ICDD Board of Directors for his sustained,
outstanding work in the field of powder diffraction.
The European Crystallography Prize
The European Crystallographic Association (ECA) announces the
establishment of the European Crystallography Prize to recognize
a significant achievement or discovery in crystallography in
the past 5-10 years. Nominees should be affiliated or identified
with the European crystallographic community, including South
Africa, as broadly defined in the charter of the ECA.
Nominations for the prize should include a statement of the contribution
for which the prize is to be awarded, reprints of relevant published
papers, a short curriculum vitae of the nominee, and the signatures
of at least three additional nominators, preferably with letters
supporting the nomination.
Nominations should be postmarked no later than 15 December 1999
and should be sent to:
Professor Paul T. Beurskens, ECA Secretary,
Lab. voor Kristallografie, University of Nijmegen,
Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
The inaugural prize, including a monetary award and certificate
of recognition, will be presented at the opening ceremony of
the 19th European Crystallography Meeting (ECM-19) to be held
in Nancy, France, 25-31 August 2000.
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Plastic Toys for Crystallographers
The vital role played by cosine strips for summing Fourier series
in the period 1930-1950 has rightly been emphasized by Bob Gould
and Ron Stenkamp (ACA Newsletter, Spring, 1999). But before summing
a Fourier, one has to correct intensities for various factors
(in order to obtain |F|'s from I's), and then calculate structure
factors (in order to obtain phased F's). In 1951, my PhD supervisor,
Gerhard Schmidt, and I devised analogue devices (constructed
in Perspex (AMER. Plexiglass)) to reduce the drudgery of these
calculations. Schmidt (Acta Cryst., 4, 186-187
(1951)) designed a circular trigonometric slide rule to carry
out calculations of cos 2_(hxi + lzi), one of the trigonometric
parts of the structure factor for the favored space group P21/c.
The last sentence of his paper reads "Two hundred F's of
the form cos 2_(hxi + lzi) of 26 atoms have been computed in
16 working hours." I do not recall whether this was one
or two graduate-student workdays, but I do remember that Schmidt
did his fair share of the donkey work. The crystal was tetrabenznapthalene,
and our early paper (Herbstein & Schmidt, J. Chem. Soc,
3314-3319 (1954)) has been followed by a (rather) more modern
analysis (Herbstein, Acta Cryst., B35, 1661-1670
(1979)). The trigonometric slide rule was very useful in calculating
the molecular-plane section through the three-dimensional electron
density map of _-phenazine (Herbstein & Schmidt, Acta
Cryst., 9, 399-412 (1955)).
My particular contribution was to provide a way of obtaining
the value of the rotation factor correction. A couple of years
earlier G. H. Goldschmidt and G. J. Pitt (J. Sci. Instrum.
25, 397-298 (1948)) had devised a scaled rule to obtain,
with the aid of a large-scale plot of the reciprocal lattice,
the Lorentz-polarization correction for intensities measured
from three-dimensional Weissenberg photographs. The rotation
factor correction was obtained, somewhat inconveniently, from
a separate device. My 'genius' (one half page in Acta Cryst,
4, 185 (1951)) was to recognize, using a formula given
by G. Tunell (Amer. Min. 24, 338 (1939)), that
the Goldschmidt-Pitt device could be simply modified to give
the rotation factor together with the Lp-factor, thus
eliminating the need for a separate accessory. Neither of these
devices enjoyed the popular success of the strips, but I was
inordinately proud of my contribution, the first paper I published
entirely on my own. Developments elsewhere soon made our two
plastic toys obsolete, but, as Jack Dunitz has remarked, "Those
of us who survived look back on it as a heroic age".
Frank Herbstein |
