Sine Ydun Larsen (1943–2025)

Sine Larsen, former President and former General Secretary and Treasurer of the IUCr, is remembered.

Rajagopala Chidambaram (1936–2025)

Obituary for Rajagopala Chidambaram

Homophase bilayers: more than just the sum of their monolayers

Twisted homophase bilayers exhibit remarkable physical properties absent in their constituent monolayers. Quiquandon & Gratias [Acta Cryst. (2025), A81, 94–106] develop a crystallographic framework for rigorous description of the structure of bilayers, including systems without a coincidence lattice.

Crystallography of quasiperiodic moiré patterns in homophase twisted bilayers

The quasiperiodic nature of moiré patterns in homophase twisted bilayers is analyzed to understand the underlying basic periodicities and symmetries of homophase twisted bilayers built on any 2D structure.

Symmetric 3-periodic polycatenanes: catenated rings, polyhedra and rods

We describe 3-periodic, vertex- and arc-transitive, polycatenated structures formed from rings, polyhedra and rods. There are infinite families of infinite structures, and this report is restricted to those structures with units linked to three or six others.

A physical optics formulation of Bloch waves and its application to 4D STEM, 3D ED and inelastic scattering simulations

This article describes the re-formulation of Bloch waves using physical optics theory for more efficient simulation of large electron diffraction data sets.

Unit-cell parameters determination from a set of independent electron diffraction zonal patterns

We present an algorithm for unit-cell determination from a set of randomly oriented electron diffraction patterns and demonstrate its performance for two known structures (copper perchlorophthalocyanine and lysozyme) and one as-yet uncharacterized structure.

Deconvoluting thermomechanical effects in X-ray diffraction data using machine learning

Bayesian machine learning, trained by physics-based simulations, is used to separate the effects of temperature and mechanical loading within in situ diffraction data.

Isogonal 1-periodic polycatenanes (chains). Transitivity and intransitivity of links

A description is provided of infinite families of high-symmetry 1-periodic chains, including linked polygons as well as linked polyhedra. Examples of both Hopf-linked and Borromean-linked chains are presented.

Honeycombs – their variety, topology and symmetry

Several types of possible hexagonal double-layer honeycombs are described and analyzed from the point of view of their topology, symmetry and wax economy, including the newly discovered honeycomb with minimal use of wax.