Swedish biophysicist (born 1948)
Janos Hajdu (born 17 September 1948) is a Swedish/Hungarian scientist, who has made contributions to biochemistry, biophysics, and the science of X-ray free-electron lasers. He is a professor of molecular biophysics at Uppsala University and a leading scientist at the European Extreme Light Infrastructure ERIC in Prague.
Education.
Hajdu matriculated in 1967 from Eötvös József Gimnasium, a grammar school in Budapest. At the age of 16, he won a science prize, which allowed him to study and perform experiments in the Institute of Medical Chemistry of the Semmelweis University Medical School in Budapest (head: Brunó Ferenc Straub). His first publication was produced in this institute. In 1968, he was admitted to Eötvös Loránd University where he received an M.Sc. in chemistry (1973). He obtained a Ph.D. in biology in 1980, "Symmetry and Structural Changes in Oligomeric Proteins" and a D.Sc. in physics in 1993, "Macromolecular Structure, Function and Dynamics: X-Ray Diffraction Studies in Four Dimensions". He left Hungary in 1981.
Career and research.
Hajdu's first employment (1973) was with the Institute of Enzymology of the Hungarian Academy of Sciences (head: Brunó Ferenc Straub). In his early work, Hajdu exploited chemistry to determine the symmetry of multi-subunit protein complexes, and characterised structural transitions in these systems. Following an invitation by Louise Johnson Hajdu joined Johnson's crystallography team in Oxford in 1981, and spent 16 years in the Laboratory of Molecular Biophysics in Oxford (1981-1996), He was first a postdoctoral research fellow and later the head of an MRC laboratory at the Laboratory of Molecular Biophysics. in 1988, he was elected a lecturer of Christ Church, Oxford, teaching biochemistry and biophysics.
In 1981, the first dedicated Synchrotron Radiation Source came to life in Daresbury, and Hajdu and his colleagues were among the first users of the facility. The new synchrotron gave them the means to pursue a new direction in structural biology which was to not only determine the structure of proteins, but to observe them functioning. The very first time-resolved X-ray diffraction experiments produced 3D movies of catalysis in crystalline enzymes and revealed structural transitions in viruses. This was a path to understand the workings of molecular machineries, but radiation damage to the sample during exposure was a serious limitation. Hajdu realised there may be a way to outrun radiation damage processes by using extremely short and intense X-ray pulses (speed of light vs. the speed of the shock wave of damage formation). Experimental tests had to wait until the arrival of the first X-ray free-electron lasers, delivering femtosecond X-ray pulses with a peak brightness exceeding synchrotrons by a factor of ten billion. Funding for building such X-ray free-electron lasers faced hurdles.  
The turning point occurred in 1996, when Hajdu took up a chair at Uppsala University and set up a European research network to explore the physical limits of imaging. The project engaged an interdisciplinary approach, drawing upon structural sciences, plasma physics, optics and mathematics. Hajdu presented their findings to the US Department of Energy in 2000 as part of the scientific justification for building the first hard X-ray free-electron laser, the Linac Coherent Light Source (LCLS), at Stanford.
The proof of principle experiment was performed In 2006 with a soft X-ray free-electron laser in Hamburg where Hajdu with Henry N. Chapman and colleagues demonstrated experimentally that outrunning radiation damage is possible with a femtosecond X-ray pulse. The pulse turned the nano-patterned sample into a 60,000 K plasma, but not before a diffraction pattern of the virtually undamaged object could be recorded. The object was reconstructed to the diffraction-limited resolution. When the first hard X-ray free-electron laser (LCLS) was turned on in 2009, they also showed that “diffraction before destruction” or "observation before destruction" extends to the atomic scale launching the methods of serial nano-crystallography, ultrafast diffractive imaging, flash radiography, spectroscopy, and applications in fusion energy research 
Achievements.
 and in Europe (the European XFEL, Hamburg).
Awards.
Hajdu is Main Editor of the Journal of Applied Crystallography and Editorial Board Member of Nature's Scientific Data.
References.
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