NEWS

7June 2022 ESRFnews

The roots of wheat crops absorb nanoplastics and become thicker as a result, scientists at ESRF beamlines have discovered. The findings are a step towards understanding whether nanoplastics have an effect on human health. Nanoplastics end up in the

environment during the erosion of larger plastic pollution, and are sometimes produced by humans directly, for example in certain cosmetics. Their behaviour is different to that of microplastics, but their size and varied composition makes them hard to study. Now, an international team of scientists from the Madrid Institute for Rural, Agricultural and Food Research and Development in Spain, ETH Zürich in Switzerland, the mediation company Xploraytion in Berlin, Germany, ISTerre in Grenoble, France, and the ESRF have added palladium atoms to nanoplastics. As a result, the particles could be tracked with X-ray fluorescence, infrared spectroscopy and X-ray computed tomography at the ESRF beamlines ID21, ID19 and ID16B. In wheat plants grown in a solution

of nutrients and nanoplastics in water, the scientists discovered that after

Wheat absorbs nanoplastic

four weeks the cell walls of the plant roots had thickened, apparently as a defence mechanism. It s as if the roots are trying to create a barrier so that the nanoplastics can t go through , says Hiram Castillo Michel, scientist at ID21 and study co-author. Further experiments at ETH Zürich confirmed that the nanoplastics had migrated to the stem of the plants (J. Hazard. Mater. 430 128356). Ultimately, the nanoparticles may end up in the grain of the plant, Castillo Michel adds. And we might eat them.

LAAAMP student brings crocodile to BM05 Gideon Chinamatira, a post-graduate student at Wits University in South Africa, was delayed for months trying to reach the ESRF due to COVID-19 lockdowns. Now he has finally made it despite having to pass through customs with a prehistoric crocodile. You walk around airports with this case and every time you get stopped you need to explain that you re carrying a precious fossil for scanning at the ESRF, he says. It makes you feel special.

Chinamatira is the latest student to arrive at the ESRF under Lightsources for Africa, the Americas, Asia, Middle East and Pacific (LAAAMP), a training project for scientists from countries where synchrotron sources are not available. He has been working on his fossil, which is of Early Jurassic origin, at the BM05 beamline for phase- contrast X-ray tomography. When you get here, you realise that this is the next step in tomography, he says. When I go back, I ll be able to better guide the scientists that come to the lab on proposal applications to take their samples to the ESRF s tomography beamlines.

The goal of LAAAMP is that, by learning about synchrotron techniques, the scientists will be ready to help in the construction and development of a synchrotron source in their countries in the future. Since 2017, the project has awarded more than 100 researchers with the opportunity to train for two months at many of the world s leading synchrotron light sources.

Chinamatira s grant was requested by Kudakwashe Jakata, a post- doctoral researcher in tomography at BM05 who studied at Wits University. He is now supervising Chinamatira. The LAAAMP project is great for allowing students to discover what a synchrotron is and how it differs from a lab-based computed-tomography apparatus, he says.

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Virtual X-ray tomography cross- section of the root from a wheat plant grown in a nano- plastic solution. Red regions correspond to higher density cell walls.

Pressure record broken Work led by the University of Bayreuth in Germany, and performed at the ESRF, has demonstrated that it is possible to study matter at three times the pressure that exists at the centre of the Earth. This experimental terapascal regime is a result of a unique diamond anvil cell, laser heating and use of the ESRF s ID11 beamline. The cell, designed at the University

of Bayreuth, contained a pair of diamonds with tips, or culets, that were toroidal in profile. Between these the scientists placed second-stage anvils made of nanodiamonds. With laser heating, samples of rhenium- nitrogen compounds trapped in the cells maintained terapascal pressures. Spatially resolved X-ray diffraction at ID11 revealed a previously unknown material, in which the rhenium behaved in a manner chemically similar to iron (Nature 605 274). Our first experiments took place

before the EBS upgrade at the ESRF and we needed about a week to measure one cell, says Leonid Dubrovinsky at

the University of Bayreuth. We did a very similar experiment after the upgrade, and we got even better data in a matter of hours. The benefit of the EBS is very clear. Having set the new pressure

record, the scientists are hoping to answer questions about the composition of large planets such as Neptune and Uranus, or extraterrestrial super-Earths . For this, they will complement ID11 data with measurements from the ESRF s upgraded ID27 beamline and the forthcoming ID18, where spectroscopy experiments in the terapascal regime should be possible.

Study author Saiana Khandarkhaeva of the University of Bayreuth at work on the ID11 beamline.

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