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November 2020 issue
Cover illustration: Reconstruction of human pancreatic tissue, showing the islet of Langerhans, a cluster of cells important in endocrine (hormone-producing) function: (upper left) cut through the reconstruction volume, (upper right) segmentation into different tissue components,(lower left) spatial arrangments of the cluster, (lower right) validation of segmentation and selection of cells for further analysis; scalebar: 50 µm. The sample was collected during a pancreatic tumor surgery. The paper by Frohn, Pinkert-Leetsch, Missbach-Güntner, Reichardt, Osterhoff, Alves and Salditt (pages 1707-1719) demonstrates how phase contrast tomography combining parallel and cone beam recording geometries can help to perform quantitative 3D analysis for virtual histopathology.
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international union of crystallography
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research papers
The circular symmetry in the wavefront of an X-ray free-electron laser beam focused with Be compound refractive lenses is explored in order to derive the wavefront from a single Ronchigram.
Free-electron laser X-ray beam-induced lattice disorder is investigated by measuring shot-to-shot evolution of near-Bragg coherent diffuse scattering from single-crystal germanium. It is shown that X-ray photon correlation analysis of sequential speckle measurements can be used to monitor the nature and extent of the lattice displacement rearrangement.
Soft X-ray optical systems are widely used in synchrotron radiation, X-ray microscopes, etc. Here, a third-order aberration analytical analysis method for soft X-ray optical systems with orthogonal and coplanar arrangement of the main planes of elements is proposed. It will provide an analytical measure in design and optimization of this kind of optical system.
The phase distribution, intensity and spot size at the focal plane of partially coherent light are analyzed by optimizing the size and position of an aperture.
A new design of a magnet-merged APPLE-Knot undulator with low on-axis heat load and high polarization is presented.
Severe aberrations arise in off-plane diffraction from a plane grating with constant groove density when the incident beam is uncollimated. It is shown that they can be eliminated downstream of the grating by the use of astigmatic focusing.
An investigation of the damping wiggler effect to reduce the emittance in the Pohang Accelerator Laboratory (PAL), a fourth-generation storage ring (4GSR) that uses a multi-bend achromat, is presented.
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The knife-edge imaging-based wavefront-sensing technique is used for wavefront error characterization of Be X-ray lenses with and without corrector plate. Different 3D printed corrector plates are proposed to achieve pseudo-perfect compensation of wavefront errors of Be X-ray lenses.
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The use of spatial filtering with a horizontal slit near the source to enlarge the horizontal coherence in an experimental station and produce a diffraction-limited round focus at an insertion device beamline for X-ray photon correlation spectroscopy experiments is illustrated. This scheme has now been in use since 2019 for the 8-ID beamline at the Advanced Photon Source, sharing the undulator beam with two separate beamlines, 8-ID-E and 8-ID-I at 7.35 keV, with increased partially coherent flux, reduced horizontal spot sizes on samples, and good speckle contrast.
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A theoretical approach is proposed to describe the performance degradation caused by imperfect X-ray optical elements.
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X-ray rocking curve imaging is used to study the smallest achievable Bragg-plane slope errors in the best presently available synthetic diamond crystals and how they compare with those of perfect silicon crystals
New high-resolution cadmium–zinc–telluride drift strip detectors have been developed with excellent room-temperature energy resolution of 0.8% FWHM at 662 keV.
This paper reports measurement results and an experimental demonstration of a new backside-illuminated scientific CMOS sensor for soft X-ray experiments at the SOLEIL synchrotron.
The physical absorbed dose enhancement due to the presence of gold and bismuth nanoparticles by synchrotron X-ray beams was measured in PRESAGE dosimeters.
A facile method for calibrating the absolute scattering intensity at the carbon K absorption edge, taking advantage of X-ray fluorescence produced at that edge, is presented. The method is verified by measuring the Flory–Huggins interaction parameter between two segments of a block copolymer melt.
A new dual-exponential impulse shaping method is proposed, and its deployment in hardware to test its performance is shown.
Systematic analysis on interfaces of Cr/Ti multilayers has been performed. The near-normal-incidence reflectivity increases from 4.48% to 15.75% at a wavelength of 2.73 nm using co-deposition of B4C.
A bent crystal Laue analyser combined with total reflection fluorescence X-ray absorption fine structure is a promising technique for in situ surface analysis of highly dispersed systems even in the presence of solution.
Contrast can be recovered by selectively binning the detector in a double-pulse X-ray speckle visibility spectroscopy experiment where an angular misalignment and imperfect overlap would otherwise destroy the contrast.
Experimentally obtained optical constants of the nickel near L-edge energy region show signatures of different excitations which are absent in the available databases. These excitations are explained using charge transfer effects and core-hole interactions in valence and core excited states.
Local structure changes of luminescent Ag zeolite-A and -X are analysed by in situ XAFS. The relation between the behaviour of the Ag cluster in the cavity of zeolite and the intensity of the photoluminescence is given.
A comparative theoretical analysis of the free-electron laser (FEL) radiation in main FEL experiments is given. It is shown that an elliptic undulator with field harmonics and electron–photon phase-shifting yields significantly higher harmonic power than that from a planar undulator with phase-shifting.
The heating effects of hard X-rays from synchrotron sources are simulated by coupling the Monte Carlo method with the Fourier heat equation. The temperature behaviours simulated are found to be critically dependent on the filling mode of the electron storage ring and on the distribution of the energy density absorbed by the material.
Geometric determination of direction of dislocations using synchrotron X-ray transmission topography
A geometric method for resolving dislocation directions in synchrotron X-ray topography is described.
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The design, construction and assembly details for an X-ray transparent triaxial deformation cell for 4D investigations of rock deformation and coupled chemical–mechanical processes in the geosciences are presented. The portability and flexibility of the cell are demonstrated by deployment on four different synchrotron beamlines.
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Ptychography has been developed and routinely employed as an at-wavelength metrology method on a low coherence dipole magnet beamline.
Zernike phase-contrast full-field transmission X-ray nanotomography for 400 micrometre-sized samples
A method for sub-millimetre field-of-view full-field X-ray tomography at a resolution of hundreds of nanometres is presented.
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First results from a 10 µm MURA coded aperture optic for a full-field X-ray fluorescence microscope are presented.
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This paper presents propagation-based phase-contrast tomography in two configurations at the beamline endstation GINIX, demonstrated on the application of 1 mm human pancreatic tumor tissue biopsies.
short communications
A new scheme is proposed and demonstrated to generate a two-color X-ray free-electron laser consisting of broadband and narrowband beams.
Thermal load in pulse train mode can be a haunting factor that undermines the brightness and coherence of self-seeded X-ray free-electron lasers. The pulse-to-pulse thermal load effects on the seed quality and some instructive information for the tuning process are studied and presented.
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A fast X-ray focusing polycapillary alignment method was implemented and tested using a compact short-pulse laser-driven broadband X-ray source.
computer programs
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An open source Python software package, developed for data analysis for spectral K-edge subtraction imaging and wide-field energy-dispersive X-ray absorption spectroscopy imaging, is reported.
THORONDOR is a Python software realized for the analysis of multiple NEXAFS spectra collected in situ. It allows the correction and normalization of the acquired spectra through a fast and intuitive interface. Moreover, it offers a sophisticated toolbox for the fitting of the NEXAFS rising-edge peaks.
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