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

Obituary for Rajagopala Chidambaram

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.

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.

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.

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

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.

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

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.

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.