David Sayre (1924–2012) Crystallographer Who Pioneered Methods of X-Ray Imaging and Modern Computing

COMMENT OBITUARY David Sayre (1924–2012) Crystallographer who pioneered methods of X-ray imaging and modern computing.

avid Sayre, who died on 23 February, rise to what is now called Sayre’s equation. Franklin and DNA, about the outstanding was a pioneer in crystallography and Atomicity is the key concept behind the crystallographer and Sayre family friend diffraction imaging, a visionary in direct methods used for crystallography who had died of cancer at an early age. DX-ray microscopy and an architect of modern today, although Sayre did not share the After returning to IBM, Sayre became computing. A superb scientist, deep thinker 1985 chemistry Nobel prize awarded for interested in X-ray microscopy. His 1971 idea and wonderful mentor, he could have of how to fabricate Fresnel zone plates built a scientific empire. But that was for focusing X-rays became a reality not his style. He was driven by the through the use of IBM’s nanofabrica- desire to do pure and original science. tion technology and with the advent

Sayre was born on 2 March 1924 in of synchrotron radiation sources such IBM ARCHIVES New York. His father was an organic as the National Synchrotron Light chemist whose ancestors helped to Source at Brookhaven National Labo- found the town of Southampton, ratory in Upton, New York. X-ray New York, in the sixteenth century. microscopy based on zone plates is now His mother was the daughter of used in synchrotron-radiation facilities Jewish immigrants. Sayre was edu- worldwide. cated at Yale University in New Haven, Around 1990, Anne developed Connecticut, graduating in 1943 at the scleroderma, a debilitating disease, age of 19 with a bachelor’s degree in and David retired from work to care for physics. The Second World War was her. But he continued working to real- at its height, so Sayre worked on radar ize his 1952 dream: the reconstruction at the Radiation Laboratory at the of molecular structures without the use Massachusetts Institute of Technology of crystals. The idea came to fruition in Cambridge. almost 50 years later, with the publica- In 1946, guessing biology would be tion in 1999 of the first reconstruction the next exciting field, Sayre became a of a non-crystalline model object from graduate student in biology at the Uni its diffraction pattern (which was J.M.’s versity of Pennsylvania in Philadelphia PhD project). This paper established and then at Harvard University in coherent diffraction imaging (CDI), Cambridge. He was not initially inter- also called lensless imaging or diffrac- ested in what he was learning, but in tion microscopy, as the most promising 1947 Sayre came across an article about form of high-resolution X-ray imaging. X-ray crystallography that changed his CDI is now one of the fastest-growing life. He joined Raymond Pepinsky’s fields in X-ray science. crystallography laboratory at Auburn Anne died in 1998, and in the last University in Alabama, where he used decade of his life David suffered from a mathematical operation known as the it. In 1952, Sayre also realized that, even Parkinson’s disease. But he continued to Fourier transform to analyse the structures in the absence of regular crystal structure, participate in research and to offer advice. A of crystals probed with X-ray beams. information could be gleaned from the researcher with exceptional intuition, David That year, Sayre married Anne fine sampling of diffraction patterns. lived for science. His passing is a huge loss for Colquhoun, a fiction writer. She took a Sayre saw early on that solving complex all of us. ■ teaching position at the Tuskegee Institute, crystal structures would require substantial but her involvement in the school, which computational resources. In 1956 he joined Janos Kirz is distinguished professor enrolled black students, was controversial IBM’s Watson Research Center in New York, emeritus at Stony Brook University, New in the Deep South at that time, and and eventually became assistant manager York, and scientific adviser for the Advanced the Sayres soon left. They moved to Oxford, of the team that wrote the original Light Source, Lawrence Berkeley National UK, where Sayre completed his PhD in the FORTRAN compiler. He became corporate Laboratory, Berkeley, California 94720, lab of Dorothy Hodgkin in 1951. director of programming, and later head of USA. He was a collaborator and friend of Sayre produced his most profound papers the IBM programming research group. In David for nearly 40 years. Jianwei Miao is a during this period, solving the ‘phase 1969, he and his team proved the efficiency professor in the Department of Physics and problem’ in crystallography — the loss of of virtual memory in computing. Astronomy and the California NanoSystems phase information in the measurement of In 1972–73, Sayre took a sabbatical, Institute, University of California, Los diffraction intensity. In 1952, he proposed returning to Hodgkin’s lab and to crystal- Angeles, California 90095, USA. He worked atomicity — the fact that atoms are small and lography. It was during this time that one of with David on coherent diffraction imaging discrete points relative to the space between us (J.K.) met the Sayres, forming a lasting beginning in 1996, first as a student, then as a them — as a constraint for determining the friendship and collaboration. Anne Sayre collaborator and friend. phases of crystals of small molecules, giving also wrote the influential book Rosalind e-mail: [email protected]