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June 2023 ESRFnews

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Boaz Pokroy has spent almost all his 27-year academic life at the Technion, and it s easy to see why. Situated in Haifa, the Israel Institute of Technology is unique in its joint emphasis on both basic and applied sciences. But the Technion is not Pokroy s only scientific home: he has another at the ESRF, where he has been coming as a user for over two decades, since his Master s degree in materials science and engineering. There is no doubt that the ESRF is the best synchrotron in the world, he says. Its capabilities, its versatility, its user support I don t think anyone would disagree with that.

As a scientist who specialises in biomineralisation, Pokroy regularly visits the ID22 high-resolution powder X-ray diffraction beamline, for its powerful and rapid identification of unknown biominerals; he also uses the ID16A nanoimaging and ID16B nanoanalysis beamlines, the microfocus beamline ID13, and ID02 for time- resolved X-ray scattering. Almost all these have drastically benefited from the incredibly high brilliance and coherence of the EBS source, he says.

In 2017, Pokroy led a large team at the Technion, the ESRF and elsewhere in reporting a long-awaited characterisation of the properties of a biomineral in the skeleton of the brittle star, Ophiomastix wendtii, using ID22, ID16B, ID13 and several laboratory imaging methods. The study revealed the biomineralisation of a material that is used by the brittle star in an array of microlenses to detect shadows and hide from predators. Remarkably, despite being formed from calcite, which is usually a brittle mineral, the glassy lenses are made very tough by nano- scale precipitates and their layered organisation (Science 358 6368, Nat. Commun. 10 4559).

Pokroy draws inspiration from other types of biological material, too. He is

currently interested in waxes found on the surface of various plant leaves, from the lotus, which often looks pristine despite growing in slow-moving, muddy rivers, to the humble broccoli, which (as many people will have observed) refuses to stay wet when run under a tap. This water-repelling, hydrophobic nature of waxes is very useful: it allows plants to self-clean in rainfall, as well as resist attack from viruses and bacteria, which struggle to form their usual surface biofilms. Scientists would like to mimic these waxes synthetically, as they could provide an alternative to crop herbicides for diseases such as powdery mildew. Backed by a grant from the European Research Council, Pokroy is investigating the make-up and orientation of wax crystals, in house and at the ESRF, to learn how they form. Often their orientations are not the most stable ones, he explains. That tells us that to copy them, we have to grow them fast, out of equilibrium by thermal evaporation, or spraying with a volatile solvent.

Different roles Israel has been a scientific associate of the ESRF for 25 years. For the past four years, Pokroy has been its representative on the ESRF s Science Advisory Committee, helping to continue this partnership, and providing for him personally an insight into the competing demands on light-source administration as well as research from areas very different to his own. One of his favourite other roles is advising graduate students, the importance of which can too easily be forgotten, he says. I like to bring as many students as possible to the ESRF, he adds. Of course, here you can teach them technically how to work the beamlines, but it is also a fantastic place for them to learn how to think scientifically. 

Jon Cartwright

Israel has been an ESRF scientific associate for 25 years. The support of Boaz Pokroy, Israel s representative on the Science Advisory Committee, is just as unwavering.

A strong partnership

BOAZ POKROY IN BRIEF BORN: Haifa, Israel (1974). EDUCATION: BA chemistry, BSc Materials science and engineering, Technion Israel Institute of Technology (2000); MSc Materials science and engineering (2003); PhD Materials science and engineering (2006). CAREER: Postdoc, Bell Laboratories, New Jersey, US (2007); Postdoc, Harvard, Massachusetts, US (2007 2009); Assistant Professor, Technion (2009 2015); Associate Professor (2015 2020); Professor (2020 ).

I like to bring as many students as possible to the

ESRF... it is a fantastic place for them to learn how to

think scientifically