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The opening of the ID24-DCM branch to the user community is planned for February 2023. The commissioning went very well and has demonstrated the unprecedented potential of the ESRF DCM, both in terms of energy and position stability.

Finally, the high-pressure XRD beamline ID27 is now almost in full user operation. Outstanding experiments have been already performed, including combined 2D XRD and X-ray fluorescence mapping of hot materials in the multi-megabar regime, high flux pink beam studies of melts and coherent Bragg diffraction imaging of nano- grains under high pressure.

The research presented in this chapter comes from a wide variety of research areas. It features contributions from Earth and environmental sciences. G. Weck et al. have performed in-situ X-ray diffraction in the laser-heated diamond anvil cell at ID27, revealing that superionic ice could occupy a large part of the interiors of the planets Uranus and Neptune (page 14). Using the same beamline (ID27) and methodology, R. Pierru et al. have investigated the melting behaviour of micron-sized mineral samples at pressures and temperatures up to 140 GPa and 6000 K (page 15). Also, at ID27, F. Miozzi et al. have explored the crystallisation pathways for planets accreting in oxygen- poor environments that potentially segregate C-rich cores (page 16). G.S. Pokrovski et al. have employed in- situ high-resolution X-ray absorption spectroscopy at BM16 (page 18), combined with quantum-chemistry simulations, to provide direct evidence for dissolved gold complexes with the [HS]− and [S3 ]− ligands. At BM30, M. Louvel et al. have shown that Rare Earth Elements (REE)- carbonate complexes can promote high REE concentrations in geological fluids (page 20) a new mechanism to concentrate these critical metals in the Earth s crust.

In this issue of the Highlights, one will also find reports in the fields of biology and chemistry. E. Girard et al. have

investigated the excited states of the Ras oncogene protein involved in many cancers at ID15B and ID27 (page 21). M. Ceppatelli et al. have synthesised crystalline arsenic nitride (AsN) under high-pressure and high-temperature conditions by direct chemical reaction of arsenic and molecular nitrogen at ID27 (page 23). By combining X-ray absorption and emission spectroscopy at BM23 and ID26 (page 24), A. Yu. Molokova et al. have shed light on the details of SO2 poisoning of Cu-exchanged chabazite catalyst. Using a similar method powered by wavelet transforms and machine-learning-assisted extended X-ray absorption fine structure fitting at BM23 (page 26), A. Martini et al. have revealed the influence of the zeolite composition on mobile Cu-complexes formed in key catalysts under NH3-SCR-relevant conditions.

Finally, research examples conducted in the fields of physics and materials science are featured. At the nuclear resonance beamline ID18, using a combination of spectroscopy, microscopy and grazing-incidence nuclear resonance scattering experiments, D.G. Merkel et al. have revealed the 3D structure of tailored individual magnetic domains in FeRh thin films (page 28). Again, at ID18, R.A. Baulin et al. have employed polarisation analysis of the reflected radiation in Mössbauer reflectivity to shed new light on the magnetic state of iron in thin films and multilayers (page 29). At ID27, P. Németh et al. have probed the complex structure of diamonds formed at extreme pressures and temperatures during an asteroid impact (page 31). The results may open opportunities for engineering carbon materials with unique mechanical and electronic properties. At ID15B, A. Pakhomova et al. have characterised four clathrate hydrates of acetone (page 32). They showed that clathrates hosting polar molecules are not as exotic as previously thought and could be stabilised at high-pressure conditions through hydrogen bonding.

M. MEZOUAR