The cryo-EM revolution: fueling the next phase

Cryo-EM has seen unabated growth and adoption in the last three years. Continued support at institutional, regional and national levels is essential to sustain its evolution.

Interpreting the cryo-EM map

Beckers et al. [IUCrJ (2019), 6, 18–33] propose a general approach to visualization of cryo-EM maps. Their method overcomes some of the challenges inherent in the conventional approach for depicting maps using a single isosurface threshold.

A Bayesian approach to beam-induced motion correction in cryo-EM single-particle analysis

A Bayesian approach to estimate the trajectories of particle motion in electron cryo-microscopy single-particle analysis is presented.

Thresholding of cryo-EM density maps by false discovery rate control

The interpretation of cryo-EM density by atomic models remains a daunting task owing to the identification of appropriate threshold levels at low signal-to-noise ratios in high-resolution shells and weak structural features. It is shown that transforming cryo-EM densities to confidence maps followed by false discovery rate-based thresholding provides a robust way to interpret cryo-EM structures.

Structure-factor amplitude reconstruction from serial femtosecond crystallography of two-dimensional membrane-protein crystals

Three-dimensional intensities were reconstructed from serial crystallography data using two-dimensional crystals.

Computational design of symmetrical eight-bladed β-propeller proteins

Two artificial β-propeller proteins with eight identical blades were designed, purified and crystallized. X-ray crystallography confirmed the perfectly symmetrical structures of these highly stable proteins.

Direct air capture of CO­₂ – topological analysis of the experimental electron density (QTAIM) of the highly insoluble carbonate salt of a 2,6-pyridine-bis­(iminoguanidine), (PyBIGH₂)(CO₃)(H₂O)₄

Low-temperature X-ray and neutron diffraction experiments are used to characterize the electron-density distribution and intermolecular interactions in the insoluble carbonate salt of a 2,6-pyridine-bis(iminoguanidine), a potential CO₂ sequestering agent. The importance of the hydrogen-bonding ability of the cation to the anion–water structure is discussed.

K-paracelsian (KAlSi₃O₈·H₂O) and identification of a simple building scheme of dense double-crankshaft zeolite topologies

The synthesis and structure refinement of a dense zeolite with a one-dimensional channel system is reported.

SPIND: a reference-based auto-indexing algorithm for sparse serial crystallography data

SPIND is an auto-indexing algorithm developed for sparse-pattern diffraction data. It is generally applicable to multiple crystallographic data types including serial crystallographic data collected from X-ray free-electron lasers (XFEL), synchrotron light sources or transmission electron diffraction data collected on a transmission electron microscope (TEM), and can also be extended to ultrafast electron diffraction data. The algorithm and comparative studies on experimental serial femtosecond protein crystallography data sets demonstrate its ability to maximize data efficiency by making use of sparse patterns that are discarded by other indexing programs.

Framework disorder and its effect on selective hysteretic sorption of a T-shaped azole-based metal–organic framework

The effect of framework (pore) disorder on gas sorption of azole-based isoreticular Cu(II) MOFs with rtl (rutile) topology and characteristic 1D tubular pore channels is investigated for the first time.

Deformation pathway and defect generation in crystals: a combined group theory and graph theory description

This work provides a new theoretical approach based on group theory and graph theory to capture the intrinsic properties of crystalline materials upon deformation.

Incommensurate structures of the [CH₃NH₃][Co(COOH)₃] compound

The temperature evolution of [CH₃NH₃][Co(COOH)₃] on a single crystal and the crystal structure determination of intermediate incommensurate phases of [CH₃NH₃][Co(COOH)₃] by means of neutron diffraction are presented.

Structure model of γ-Al₂O₃ based on planar defects

The defect structure of γ-Al₂O₃ produced from boehmite is described with the aid of antiphase and rotational boundaries. The type of structure defects is deduced from the selected-area electron-diffraction patterns. The defect density is quantified from the anisotropic broadening of diffraction lines in powder X-ray diffraction patterns using a computer routine based on the Debye scattering equation.

Synthesis of new Ln₄(Al₂O₆F₂)O₂ (Ln = Sm, Eu, Gd) phases with a cuspidine-related structure

The success and effects of fluorination on the starting Ln₄(Al₂O₇□)O₂ (Ln = Sm, Eu, Gd) cuspidine-related structure were investigated. The incorporation of fluoride in this structure resulted in the conversion of the isolated tetrahedral dialuminate Al₂O₇ groups to chains of distorted square-based pyramids.

A jumping crystal predicted with molecular dynamics and analysed with TLS refinement against powder diffraction data

A phase transition in a jumping crystal is predicted using molecular dynamics. The resulting structure and the dynamics of the transition are verfied by TLS refinement against powder diffraction data.

Microbatch under-oil salt screening of organic cations: single-crystal growth of active pharmaceutical ingredients

The under-oil crystallization method was successfully adopted for the crystallization of organic salts. Compared with the previously reported vapour-diffusion-based nano-crystallization technique, the under-oil method generated single crystals of more different salts for all studied compounds.