Fourth-generation light sources

New fourth-generation synchrotron radiation facilities bring large gains in X-ray source brightness, but also challenges in making full use of their potentials. Some of these challenges have been faced at X-ray free-electron laser facilities.

Introduction to the virtual thematic issue on room-temperature biological crystallography

Room-temperature biological crystallography has seen a resergence in recent years and a collection of articles recently published in IUCrJ, Acta Cryst. D Structural Biology and Acta Cryst. F Structural Biology Communications, have been collected together to produce a virtual special issue at https://journals.iucr.org/special_issues/2022/RT/.

On `Flexible design in the stomatopod dactyl club'

This commentary discusses loose versus tight control of biomineralization products and how this evolved flexibility. Concomitant improved functionality may be more widespread than commonly thought.

JINXED: just in time crystallization for easy structure determination of biological macromolecules

In this work, a method is developed and tested to obtain protein crystals on-the-fly, before immediately probing them with X-rays. The resulting crystals proved to be useful for serial crystallography using the CFEL TapeDrive and yielded high-quality datasets with useful resolution to 1.71 Å.

On the angular anisotropy of the randomly averaged magnetic neutron scattering cross section of nanoparticles

A discussion on the angular anisotropy of the two-dimensional magnetic small-angle neutron scattering cross section of randomly oriented nanoparticles is provided, and it is shown by means of micromagnetic simulations that this quantity is, in general, anisotropic.

Investigation of the milling characteristics of different focused-ion-beam sources assessed by three-dimensional electron diffraction from crystal lamellae

An analysis of the effect on diffraction quality that arises from milling crystals of lysozyme with argon and xenon plasma focused ion beams is presented. This is compared with crystals milled using a gallium source. Upper and lower bounds for the thickness of the milling damage layer are estimated.

Flexible design in the stomatopod dactyl club

The stomatopod dactyl club has a complex structure featuring an impact region, periodic regions and striated regions. The side region of the club contains both periodic and striated parts. The side region is considered to be mineralized by inorganic amorphous phases. This work shows that these phases crystallize to calcite, generating a macroporous structure early in the biomineralization process. This phase transition is common, but does not occur in every club. Thus, the appearance of the macroporous calcite structure must reflect a natural flexible design allowing for structural plasticity, such that the club remains functionally viable even upon large changes in the mineral phase microstructure.

Fast extraction of three-dimensional nanofiber orientation from WAXD patterns using machine learning

A machine-learning (ML) based framework can help to unveil the nanofiber orientation in hierarchically structured biological materials with the advantages of fast speed and automation. It promises to meet the analysis demand of extensive amounts of related data online and in real time in near-future next-generation synchrotrons.

Classification of perovskite structural types with dynamical octahedral tilting

Here, a new class of dynamically distorted perovskite structures is proposed. Based on a complete table of all possible structures, experimental data are re-examined and space group relationships are explained. A list of characteristic features of dynamically distorted perovskite structures is also provided.

Hierarchical packing of racemic metallo­supra­molecular cages with Ni(II)-based triple-stranded helicate building blocks

Racemic metallosupramolecular cages were fabricated from homochiral Ni(II)-based triple-stranded helicate building blocks. In hierarchical crystal packing, methyl groups of a cage can be accommodated in cone-shaped metal cluster metallocavitands of adjacent cages in the form of host–guest interactions.

Crystal engineering of ionic cocrystals comprising Na/K salts of hesperetin with hesperetin molecules and solubility modulation

Synthesis and property evaluation of ionic cocrystals and salts of the weakly acidic nutraceutical compound hesperetin support the reliability of crystal engineering approaches based on the PhOH⋯PhO⁻ supramolecular heterosynthon and the effectiveness of cocrystallization in tackling low aqueous solubility of a weakly ionisable compound.

Low-density preference of the ambient and high-pressure polymorphs of DL-menthol

The ambient-pressure DL-menthol polymorph α compressed above 0.40 GPa becomes metastable but more dense than the high-pressure polymorph β.

Structural analysis of the Toll-like receptor 15 TIR domain

The intracellular TIR domain of TLR15 is likely to assemble into a unique dimer with distinct structures for the BB and DD loops and αC2 helix.

Chaotic advection mixer for capturing transient states of diverse biological macromolecular systems with time-resolved small-angle X-ray scattering

A chaotic advection mixer is employed to expand the range of reactions that can be probed with time-resolved solution scattering.

Bone mineral properties and 3D orientation of human lamellar bone around cement lines and the Haversian system. Corrigendum

Corrigendum to the article by Grünewald et al. [IUCrJ (2023). 10, 189–198].