Small-angle X-ray or neutron scattering (SAXS/SANS) analysis of large unilamellar vesicles (LUVs) is often limited by high-dimensional bilayer models and the lack of dedicated, statistically rigorous workflows. Here, we introduce SAS_MoCa , an open-source Python package that integrates a compositional scattering density profile (SDP) description of lipid bilayers with a separated form factor (SFF) treatment of vesicle size and polydispersity, and couples these highly parameterized models to an adaptive thermodynamic simulated annealing algorithm formulated within a constrained Bayesian framework. SAS_MoCa enables users to incorporate quantitative prior information from, e.g. , previous SAXS/SANS studies, dynamic light scattering, NMR or molecular simulations, and returns full posterior parameter distributions, uncertainties (reported as medians and median absolute deviations) and correlations even from single SAXS curves. Validation on SAXS-only data of LUVs of varying compositions demonstrates that the method yields reproducible structural parameters with uncertainties comparable to those from joint SAXS/contrast-variation SANS analyses. The modular architecture of SAS_MoCa facilitates extension to additional lipid systems and future joint SAXS/SANS or SANS-only applications.
PrimeXP is an open-source Python/OpenGL interactive molecular graphics and analysis program, ostensibly for small-molecule crystallography, that was inspired by George Sheldrick's classic XP program. It uses a hybrid interface, pairing a bash-like terminal for command entry and feedback with a fully interactive graphical display. PrimeXP includes a wide array of tools to render multi-level electron-density maps, evaluate solvent-accessible and interstitial void spaces, and generate high-resolution, publication-quality diagrams (including ellipsoid, polyhedron and Bürgi-style `peanut' displacement surfaces). With its emphasis on visual feedback, PrimeXP provides experts with powerful analytical tools while offering students an intuitive learning environment. The program runs on Mac, Linux and Windows.
This study presents a comprehensive modelling simulation of the neutron transmission optics through the beam shaping collimator at the modernized neutron radiography (NRAD) facility located on a radial beam at the SAFARI-1 nuclear research reactor in South Africa. A Monte Carlo N -particle transport weight-window surface assessment revealed an anisotropic source profile. This has been implemented via a Monte Carlo particle list into McStas and compared with the case for an isotropic source, to determine the optimal pinhole position along the collimator length. A 2 mm-length pinhole located 1.9 m from the core box (equivalently aperture-to-detector distance L ≃ 6.13 m to a detector positioned 3.5 m from the biological shield) delivers a uniform beam (∼28.3 cm diameter) with ∼20% spatial variation. L / D targets of ∼800, ∼400 and ∼250 are achieved for pinhole diameters D = 8, 15 and 25 mm, respectively. A composite radiation filter consisting of a 100 mm-length Al 2 O 3 single crystal followed by a 50 mm-length Bi single crystal improves the beam quality to ∼98.1% thermal neutrons and leads to an ∼99.6% reduction in gamma beam content. Under these conditions an average flux of ∼2.6 × 10 7 n cm −2 s −1 is achievable for L / D = 205, while an average flux of ∼1.9 × 10 6 n cm −2 s −1 is achievable for L / D = 766 on a 20 × 20 cm 2 detector. It is shown that by extending the outlet-collimator exit to a position closer to the sample position the beam penumbra and environmental background are reduced, leading to more favourable conditions for the beam shutter and facility shielding designs. The results indicate that substantially better technical performance and thermal neutron beam quality in conjunction with minimized unwanted beam contamination and background contributions will be achieved with the modernized NRAD facility.
An integrated hardware–software platform for three-dimensional electron diffraction has been developed using the JUNGFRAU 1M charge-integrating hybrid pixel detector. The system combines the field-programmable gate array based Jungfraujoch backend with the JFGui graphical interface, providing centralized control of the detector, electron microscope and data-processing software. This workflow enables synchronized data acquisition, live visualization and instantaneous post-processing with established crystallographic programs, including XDS , DIALS and SHELX . Applications to L-histidine and dioctyl perylene tetracarboxylic diimide crystals are presented, including charge-density evaluation employing the recently developed iSFAC (ionic scattering factors) model. The workflow supports continuous-rotation measurements at speeds up to 10° s −1 , allowing acquisition of a ∼130° rotation in approximately 15 s and enabling higher-throughput measurements. Comparative measurement at 100 and 200 keV beam energies revealed the trade-off between real-space contrast and diffraction resolution. These developments establish a complete and efficient practical workflow of 3D ED coupled with instrumental evaluation, providing a robust route toward quantitative electron crystallography.
CView is a free, open-source desktop application for the visualization and analysis of inorganic crystal structures, written in Rust with a GTK4/Cairo front end and targeted at computational materials researchers preparing or interpreting plane-wave density-functional-theory calculations. It reads and writes the file formats most commonly encountered in such workflows — CIF, VASP POSCAR and CHGCAR, Quantum ESPRESSO input files, extended XYZ, and the sectioned .pot/.sys input format of the spin-polarized relativistic Korringa–Kohn–Rostoker Green's-function code, including native support for the chemical-disorder occupation blocks that describe coherent-potential-approximation alloys. CView provides, in a single graphical interface, ball-and-stick and coordination-polyhedron rendering with two-tier ghost-atom generation; bond-valence-sum analysis using the bvparm2020 parameter set with full periodic-image summation; space-group determination through the moyo Rust crystal-symmetry library, whose conventions follow spglib ; automatic Bravais classification and Setyawan–Curtarolo high-symmetry k -path construction built from the standardized primitive cell; Voronoi construction of the first Brillouin zone through half-space intersection of the reciprocal lattice; powder X-ray diffraction simulation; slab generation along arbitrary Miller indices; CHGCAR charge-density visualization with user-selected ( hkl ) slices and isolines; and probe-accessible void analysis with Shannon ionic radii for screening candidate intercalation ions in cathode materials. All three-dimensional content is rendered through Cairo as resolution-independent vector graphics, so that figures exported as PDF or SVG from the interactive viewer drop directly into a publication without rasterization artefacts. CView is distributed under the MIT licence as pre-built .deb, .rpm, .dmg and .exe packages.
