rt H1-Key to Launch First Fan Concert Next Month By world.kbs.co.kr Published On :: 2024-10-22 +09:00 H1-Key is set to embark on its first fan concert tour next month. The group will kick off the tour called “Find My KEY” in Hong Kong on Nov. 16 and will travel to other regions...[more...] Full Article Economy&It
rt How to Export Bookmarks From Chrome By computer.howstuffworks.com Published On :: Wed, 29 May 2024 12:43:11 -0400 You love your Chrome browser bookmarks but your computer is on the verge of dying. Is there any way you can save them so they appear on your new computer? Full Article
rt 3 Essential Steps for Mobile Privacy With Startpage By computer.howstuffworks.com Published On :: Tue, 16 Jul 2024 11:44:33 -0400 In today's digital age, safeguarding your mobile privacy is vital. Here are three easy steps, powered by Startpage, to keep your digital life secure. Full Article
rt How to Turn Off AMBER Alerts and Other Loud Notifications By electronics.howstuffworks.com Published On :: Fri, 19 Jul 2024 12:06:53 -0400 You may have been awakened in the night by loud blaring noise and an alert text on your phone. Who sends these alerts, and why are you getting them? Full Article
rt 11 Most Popular Sports in the World By entertainment.howstuffworks.com Published On :: Thu, 07 Nov 2024 10:25:02 -0500 Thrilling gameplay, dramatic storylines and top-notch talent are all important factors in ensuring a sport's popularity grows and fanbases thrive. The most popular sports in the world are all spectacles of athletic competition that attract large crowds in the stands and around the television. Full Article
rt Leo and Pisces Compatibility: Why Their Relationship Is Complex but Worth It By entertainment.howstuffworks.com Published On :: Sat, 09 Nov 2024 05:00:05 -0500 Explore Leo and Pisces compatibility, uncovering their strengths, weaknesses, and whether these zodiac signs can make their relationship work. Full Article
rt Exports Fall 17.8% for First 10 Days of November By world.kbs.co.kr Published On :: Mon, 11 Nov 2024 10:10:10 +0900 [Economy] : Exports fell more than 17 percent year-on-year in the first ten days of November because there were fewer working days. According to preliminary data from the Korea Customs Service on Monday, the country’s outbound shipments reached 14-point-nine billion U.S. dollars during the cited period, down ...[more...] Full Article Economy
rt Import Prices Jump 2.2% in October, Largest Gain in 6 Months By world.kbs.co.kr Published On :: Wed, 13 Nov 2024 09:13:48 +0900 [Economy] : The country’s import prices jumped more than two percent in October due to the won’s depreciation against the U.S. dollar and a rise in global oil prices. According to data from the Bank of Korea on Wednesday, the country’s import price index reached 137-point-61 in October, up two-point-two ...[more...] Full Article Economy
rt Gov’t May Expand Scope of E-7 Visa to Address Labor Shortage in Shipbuilding By world.kbs.co.kr Published On :: Wed, 13 Nov 2024 17:25:03 +0900 [Economy] : Prime Minister Han Duck-soo says the government will consult with the justice ministry and consider expanding the scope of the E-7 visa for professional workers, if the shipbuilding industry deems it necessary. Han made the remark during a news conference on Wednesday when asked how the government plans ...[more...] Full Article Economy
rt BGS releases 10K maps through updated maps portal - British Geological Survey By news.google.com Published On :: Tue, 16 May 2023 07:00:00 GMT BGS releases 10K maps through updated maps portal British Geological Survey Full Article
rt New report assesses deep geothermal energy in the UK - British Geological Survey By news.google.com Published On :: Mon, 17 Jul 2023 07:00:00 GMT New report assesses deep geothermal energy in the UK British Geological Survey Full Article
rt Small earthquake detected on Shropshire-Staffordshire border - BBC.com By news.google.com Published On :: Fri, 19 Apr 2024 07:00:00 GMT Small earthquake detected on Shropshire-Staffordshire border BBC.com Full Article
rt Product development: properties and resources - British Geological Survey By news.google.com Published On :: Wed, 23 Sep 2020 13:28:59 GMT Product development: properties and resources British Geological Survey Full Article
rt BGS maps portal - British Geological Survey By news.google.com Published On :: Thu, 24 Sep 2020 01:15:25 GMT BGS maps portal British Geological Survey Full Article
rt Earthquake hits Midlands as British Geological Survey confirm magnitude - Birmingham Live By news.google.com Published On :: Fri, 19 Apr 2024 07:00:00 GMT Earthquake hits Midlands as British Geological Survey confirm magnitude Birmingham Live Full Article
rt Scientific report published - British Geological Survey By news.google.com Published On :: Tue, 05 Jul 2022 11:38:32 GMT Scientific report published British Geological Survey Full Article
rt Natural flood management: is geology more important than trees? - British Geological Survey By news.google.com Published On :: Thu, 23 Nov 2023 08:00:00 GMT Natural flood management: is geology more important than trees? British Geological Survey Full Article
rt BGS leads update to maps of the Earth’s magnetic field - British Geological Survey By news.google.com Published On :: Thu, 04 Apr 2024 07:00:00 GMT BGS leads update to maps of the Earth’s magnetic field British Geological Survey Full Article
rt Did you feel the earth move? Mini-earthquake recorded on Shropshire/Staffordshire border - Express & Star By news.google.com Published On :: Mon, 14 Oct 2024 07:00:00 GMT Did you feel the earth move? Mini-earthquake recorded on Shropshire/Staffordshire border Express & Star Full Article
rt BGS breaks ground on geothermal heating system in Keyworth HQ, UK - ThinkGeoEnergy - Geothermal Energy News By news.google.com Published On :: Tue, 05 Mar 2024 08:00:00 GMT BGS breaks ground on geothermal heating system in Keyworth HQ, UK ThinkGeoEnergy - Geothermal Energy News Full Article
rt New research supports conservation of fallow deer across Europe - British Geological Survey By news.google.com Published On :: Tue, 16 Apr 2024 10:05:04 GMT New research supports conservation of fallow deer across Europe British Geological Survey Full Article
rt Small earthquake recorded under Powys town - Powys County Times By news.google.com Published On :: Sun, 29 Sep 2024 07:00:00 GMT Small earthquake recorded under Powys town Powys County Times Full Article
rt BGS joins new initiative supporting technical career paths - British Geological Survey By news.google.com Published On :: Mon, 23 Sep 2024 09:08:49 GMT BGS joins new initiative supporting technical career paths British Geological Survey Full Article
rt Forty years and counting: new topsoil data provides most extensive snapshot of environmental pollution effects - British Geological Survey By news.google.com Published On :: Tue, 01 Oct 2024 07:00:00 GMT Forty years and counting: new topsoil data provides most extensive snapshot of environmental pollution effects British Geological Survey Full Article
rt New community launched to support effective management of the subsurface - British Geological Survey By news.google.com Published On :: Thu, 03 Oct 2024 13:27:24 GMT New community launched to support effective management of the subsurface British Geological Survey Full Article
rt Quake it off: Taylor Swift concerts shake Edinburgh - British Geological Survey By news.google.com Published On :: Thu, 13 Jun 2024 07:00:00 GMT Quake it off: Taylor Swift concerts shake Edinburgh British Geological Survey Full Article
rt Exploiting fourth-generation synchrotron radiation for enzyme and photoreceptor characterization By journals.iucr.org Published On :: (Time-resolved) macromolecular crystallography at the new ESRF-ID29 beamline is described. Full Article text
rt Crystal structure of nickel orthovanadate (Ni3V2O8) at 299 (3) K and 1323 (8) K: an X-ray diffraction study By journals.iucr.org Published On :: The structure of Ni3V2O8 was studied using X-ray diffraction at temperatures of 299 and 1323 K. No phase transition at high temperature is observed. The variation in V—O bond length is small as compared with the Ni—O bond due to its high rigidity. Full Article text
rt Synthesis and structural study of the partially disordered complex hexagonal phase δ1-MnZn9.7 By journals.iucr.org Published On :: A detailed structural characterization of the δ1-MnZn9.7 phase is presented. Full Article text
rt Symmetry, magnetic transitions and multiferroic properties of B-site-ordered A2MnB'O6 perovskites (B' = [Co, Ni]) By journals.iucr.org Published On :: A comparative description is presented of the symmetry and the magnetic structures found in the family of double perovskites A2MnB'O6 (mainly B' = Co and some Ni compounds for comparative purposes). Full Article text
rt Morphological control for hollow rod crystals of a photochromic diarylethene on spherulites by surface properties of substrates By journals.iucr.org Published On :: 1,2-Bis(3,5-dimethyl-2-thienyl)perfluorocyclopentene formed its own spherulites by sublimation onto the hydrophilic surfaces of the (0001) planes of α-quartz and sapphire substrates. The formation of different morphologies of these spherulites was attributed to the surface properties of each substrate. Depending on the morphology of the spherulites, hollow rod crystals with cross sections of different sizes and shapes and branching structures were generated on the surfaces of the spherulites. Full Article text
rt Morphological control for hollow rod crystals of a photochromic diarylethene on spherulites by surface properties of substrates By journals.iucr.org Published On :: 2024-10-31 Sublimation methods utilizing the surface properties of substrates can address the challenge of controlling hollow morphologies in rod crystals. Spherulites were formed on the hydrophilic surface of the (0001) planes of α-quartz and sapphire substrates by sublimation of 1,2-bis(3,5-dimethyl-2-thienyl)perfluorocyclopentene (1a). Various types of hollow morphologies, distinguished by the size and shape of their cross sections and by the presence or absence of branching structures, were formed separately on α-quartz and sapphire substrates. Such precise control of the hollow morphologies was attributed to the wettability of each substrate, leading to the formation of spherulites of 1a. In addition, it was indicated that the formation process of the surface morphologies of spherulites was associated with the hollow morphologies of rod crystals of 1a. Full Article text
rt Crystal structure of nickel orthovanadate (Ni3V2O8) at 299 (3) K and 1323 (8) K: an X-ray diffraction study By journals.iucr.org Published On :: 2024-10-23 Nickel orthovanadate is a promising material with potential applications in energy storage and photocatalytic devices. The crystal structure of Ni3V2O8 at 299 (3) K and 1323 (8) K was studied using X-ray powder diffraction. The sample was a single-phase orthorhombic kagome-staircase-Ni3(VO4)2-type structure (space group Cmca) at both temperatures. The phase purity and morphology was studied using energy-dispersive X-ray spectroscopy and scanning electron microscopy. The refined unit-cell parameters at 299 (3) K are a = 5.93384 (4) Å, b = 11.38318 (7) Å and c = 8.23818 (5) Å, and at 1323 (8) K are a = 6.02077 (7) Å, b = 11.48838 (7) Å and c = 8.32611 (9) Å. The obtained results indicate thermal expansion anisotropy, with a largest expansivity along a. Variations in Ni—O and V—O bonds with temperature are observed. The variation in the Ni—O bond is about one order higher in magnitude than that of the V—O bond, signifying the high rigidity of V—O bonds. The unit-cell size variations with rising effective ionic volume of the divalent A ion in the A3B2O8 family [A = Ni, Mg, Zn, Co, Mn (experimental data) and also A = Cu, Cd (theoretical data), B = V or As] are analyzed. Based on experimental and theoretical data, trends within the family are observed and the unit-cell size for reported solid solution of nickel (87%) and copper (13%) mixture in (Ni1–xCux)3V2O8 are predicted. Predictions are also provided for some hypothetical A3B2O8 ternary compound and solid solutions. Full Article text
rt Synthesis and structural study of the partially disordered complex hexagonal phase δ1-MnZn9.7 By journals.iucr.org Published On :: 2024-10-02 A detailed structural analysis of the Zn-rich δ1-MnZn9.7 phase using single-crystal X-ray diffraction is presented. The δ1 phase has been synthesized by the high-temperature synthetic route. The structure crystallizes in space group P63/mmc (Pearson symbol hP556) with unit-cell parameters: a = b = 12.9051 (2) Å and c = 57.640 (1) Å. The 556 atoms are distributed over 52 Wyckoff positions in the hexagonal unit cell: seven ordered Mn sites, 37 ordered Zn sites and eight positionally disordered Zn sites. The structure predominantly consists of Frank–Kasper polyhedra (endohedral icosahedra Zn12 and icosioctahedron Zn16) and four distinct types of glue Zn atoms. The structure comprises a 127-atom supercluster (Mn13Zn114), a 38-atom extended Pearce cluster (Mn3Zn35), a 46-atom L-tetrahedron (Mn4Zn42), a Friauf polyhedron (Zn17), a disordered icosahedral cluster (MnZn12) and four glue Zn atoms. Positionally disordered Zn sites around an Mn site can be visualized as the superimposition of three differently oriented Zn12 icosahedra. Full Article text
rt Polymorph sampling with coupling to extended variables: enhanced sampling of polymorph energy landscapes and free energy perturbation of polymorph ensembles By journals.iucr.org Published On :: 2024-10-15 A novel approach to computationally enhance the sampling of molecular crystal structures is proposed and tested. This method is based on the use of extended variables coupled to a Monte Carlo based crystal polymorph generator. Inspired by the established technique of quasi-random sampling of polymorphs using the rigid molecule constraint, this approach represents molecular clusters as extended variables within a thermal reservoir. Polymorph unit-cell variables are generated using pseudo-random sampling. Within this framework, a harmonic coupling between the extended variables and polymorph configurations is established. The extended variables remain fixed during the inner loop dedicated to polymorph sampling, enforcing a stepwise propagation of the extended variables to maintain system exploration. The final processing step results in a polymorph energy landscape, where the raw structures sampled to create the extended variable trajectory are re-optimized without the thermal coupling term. The foundational principles of this approach are described and its effectiveness using both a Metropolis Monte Carlo type algorithm and modifications that incorporate replica exchange is demonstrated. A comparison is provided with pseudo-random sampling of polymorphs for the molecule coumarin. The choice to test a design of this algorithm as relevant for enhanced sampling of crystal structures was due to the obvious relation between molecular structure variables and corresponding crystal polymorphs as representative of the inherent vapor to crystal transitions that exist in nature. Additionally, it is shown that the trajectories of extended variables can be harnessed to extract fluctuation properties that can lead to valuable insights. A novel thermodynamic variable is introduced: the free energy difference between ensembles of Z' = 1 and Z' = 2 crystal polymorphs. Full Article text
rt Automated selection of nanoparticle models for small-angle X-ray scattering data analysis using machine learning By journals.iucr.org Published On :: 2024-02-29 Small-angle X-ray scattering (SAXS) is widely used to analyze the shape and size of nanoparticles in solution. A multitude of models, describing the SAXS intensity resulting from nanoparticles of various shapes, have been developed by the scientific community and are used for data analysis. Choosing the optimal model is a crucial step in data analysis, which can be difficult and time-consuming, especially for non-expert users. An algorithm is proposed, based on machine learning, representation learning and SAXS-specific preprocessing methods, which instantly selects the nanoparticle model best suited to describe SAXS data. The different algorithms compared are trained and evaluated on a simulated database. This database includes 75 000 scattering spectra from nine nanoparticle models, and realistically simulates two distinct device configurations. It will be made freely available to serve as a basis of comparison for future work. Deploying a universal solution for automatic nanoparticle model selection is a challenge made more difficult by the diversity of SAXS instruments and their flexible settings. The poor transferability of classification rules learned on one device configuration to another is highlighted. It is shown that training on several device configurations enables the algorithm to be generalized, without degrading performance compared with configuration-specific training. Finally, the classification algorithm is evaluated on a real data set obtained by performing SAXS experiments on nanoparticles for each of the instrumental configurations, which have been characterized by transmission electron microscopy. This data set, although very limited, allows estimation of the transferability of the classification rules learned on simulated data to real data. Full Article text
rt Permissible domain walls in monoclinic ferroelectrics. Part II. The case of MC phases By journals.iucr.org Published On :: 2024-04-29 Monoclinic ferroelectric phases are prevalent in various functional materials, most notably mixed-ion perovskite oxides. These phases can manifest as regularly ordered long-range crystallographic structures or as macroscopic averages of the self-assembled tetragonal/rhombohedral nanodomains. The structural and physical properties of monoclinic ferroelectric phases play a pivotal role when exploring the interplay between ferroelectricity, ferroelasticity, giant piezoelectricity and multiferroicity in crystals, ceramics and epitaxial thin films. However, the complex nature of this subject presents challenges, particularly in deciphering the microstructures of monoclinic domains. In Paper I [Biran & Gorfman (2024). Acta Cryst. A80, 112–128] the geometrical principles governing the connection of domain microstructures formed by pairing MAB type monoclinic domains were elucidated. Specifically, a catalog was established of `permissible domain walls', where `permissible', as originally introduced by Fousek & Janovec [J. Appl. Phys. (1969), 40, 135–142], denotes a mismatch-free connection between two monoclinic domains along the corresponding domain wall. The present article continues the prior work by elaborating on the formalisms of permissible domain walls to describe domain microstructures formed by pairing the MC type monoclinic domains. Similarly to Paper I, 84 permissible domain walls are presented for MC type domains. Each permissible domain wall is characterized by Miller indices, the transformation matrix between the crystallographic basis vectors of the domains and, crucially, the expected separation of Bragg peaks diffracted from the matched pair of domains. All these parameters are provided in an analytical form for easy and intuitive interpretation of the results. Additionally, 2D illustrations are provided for selected instances of permissible domain walls. The findings can prove valuable for various domain-related calculations, investigations involving X-ray diffraction for domain analysis and the description of domain-related physical properties. Full Article text
rt Bond topology of chain, ribbon and tube silicates. Part II. Geometrical analysis of infinite 1D arrangements of (TO4)n− tetrahedra By journals.iucr.org Published On :: 2024-04-29 In Part I of this series, all topologically possible 1-periodic infinite graphs (chain graphs) representing chains of tetrahedra with up to 6–8 vertices (tetrahedra) per repeat unit were generated. This paper examines possible restraints on embedding these chain graphs into Euclidean space such that they are compatible with the metrics of chains of tetrahedra in observed crystal structures. Chain-silicate minerals with T = Si4+ (plus P5+, V5+, As5+, Al3+, Fe3+, B3+, Be2+, Zn2+ and Mg2+) have a grand nearest-neighbour 〈T–T〉 distance of 3.06±0.15 Å and a minimum T⋯T separation of 3.71 Å between non-nearest-neighbour tetrahedra, and in order for embedded chain graphs (called unit-distance graphs) to be possible atomic arrangements in crystals, they must conform to these metrics, a process termed equalization. It is shown that equalization of all acyclic chain graphs is possible in 2D and 3D, and that equalization of most cyclic chain graphs is possible in 3D but not necessarily in 2D. All unique ways in which non-isomorphic vertices may be moved are designated modes of geometric modification. If a mode (m) is applied to an equalized unit-distance graph such that a new geometrically distinct unit-distance graph is produced without changing the lengths of any edges, the mode is designated as valid (mv); if a new geometrically distinct unit-distance graph cannot be produced, the mode is invalid (mi). The parameters mv and mi are used to define ranges of rigidity of the unit-distance graphs, and are related to the edge-to-vertex ratio, e/n, of the parent chain graph. The program GraphT–T was developed to embed any chain graph into Euclidean space subject to the metric restraints on T–T and T⋯T. Embedding a selection of chain graphs with differing e/n ratios shows that the principal reason why many topologically possible chains cannot occur in crystal structures is due to violation of the requirement that T⋯T > 3.71 Å. Such a restraint becomes increasingly restrictive as e/n increases and indicates why chains with stoichiometry TO<2.5 do not occur in crystal structures. Full Article text
rt Laboratory X-ray powder micro-diffraction in the research of painted artworks By journals.iucr.org Published On :: This review summarizes the methodological aspects of laboratory X-ray powder micro-diffraction and demonstrates the assets of the method in the research of painted artworks for evaluation of their provenance or diagnosing their degradation. Full Article text
rt Optimizing crucible geometry to improve the quality of AlN crystals by the physical vapor transport method By journals.iucr.org Published On :: The growth quality of AlN single crystals was improved by optimizing the crucible structure for Al vapor transport with the help of finite element simulation. Full Article text
rt The effects of low boron incorporation on the structural and optical properties of BxGa1−xN/SiC epitaxial layers By journals.iucr.org Published On :: The effect of boron in BxGa1−xN/SiC heteroepitaxy was established by X-ray diffraction reciprocal-space maps on symmetric 0002 and asymmetric 11 {overline 2} 4 reflections. The density of screw and edge threading dislocations was quantified in the framework of the mosaic model. Full Article text
rt The effects of low boron incorporation on the structural and optical properties of BxGa1−xN/SiC epitaxial layers By journals.iucr.org Published On :: 2024-11-04 BGaN epilayers with boron contents up to 5.6% were grown on SiC substrates by metal–organic chemical vapor deposition. The effects of boron incorporation on the structural and optical properties were studied by high-resolution X-ray diffraction (XRD), atomic force microscopy (AFM), Raman spectroscopy and photoluminescence (PL) spectroscopy. XRD reciprocal-space maps around the symmetric 0002 and asymmetric 11 {overline 2} 4 reflections allowed evaluation of the lattice constants and lattice mismatch with respect to the underlying substrate. XRD rocking curves and AFM measurements indicated the mosaic microstructure of the epilayer. The impact of boron content on crystallite size, tilt and twist is evaluated and the correlation with threading dislocation density is discussed. The deterioration of optical properties with increasing boron content was assessed by Raman and PL spectroscopy. Full Article text
rt Optimizing crucible geometry to improve the quality of AlN crystals by the physical vapor transport method By journals.iucr.org Published On :: 2024-10-16 In the conventional crucible structure for AlN crystal growth by physical vapor transport, owing to the long molecular transport path of Al vapor and the disruption of the gas flow by the presence of a deflector, the Al vapor easily forms polycrystals in the growth domain. The result is increased internal stress in the crystals and increased difficulty in growing large-sized crystals. On this basis, with the help of finite element simulations, a novel crucible structure is designed. This crucible not only optimizes the gas transport but also increases the radial gradient of the AlN crystal surface, making the enhanced growth rate in the central region more obvious. The thermal stresses between the deflector and the crystal are also reduced. High-quality AlN crystals with an FWHM of 79 arcsec were successfully grown with this structure, verifying the accuracy of finite element simulation of the growth of AlN crystals. Our work has important guiding significance for the growth of high-quality AlN crystals. Full Article text
rt Laboratory X-ray powder micro-diffraction in the research of painted artworks By journals.iucr.org Published On :: 2024-11-08 Painted artworks represent a significant group of cultural heritage artifacts, which are primarily admired because of their aesthetic quality. Nevertheless, the value of each particular painting depends also on what is known about it. Material investigation of paintings is one of the most reliable sources of information. Materials in painted artworks (i.e. panel, easel and miniature paintings, wall paintings, polychromed sculptures etc.) represent an extensive set of inorganic and organic phases, which are often present in complicated mixtures and exhibit characteristics reflecting their geological genesis (mineral pigments), manufacturing technology (artificial pigments), diverse biological nature (binders or dyes) or secondary changes (degradation or intentional later interventions). The analyses of paintings are often made challenging by the heterogeneous nature and minute size of micro-samples or, in some cases, even by the impossibility of sampling due to the preciousness, fragility or small dimensions of the artwork. This review demonstrates the successful implementation of laboratory X-ray powder micro-diffraction for material investigation of paintings, illustrating its efficiency for mineralogical analysis of (i) earth-based materials indicating the provenance of paintings, (ii) copper-based pigments pointing to their origin, and (iii) products of both salt corrosion and saponification enabling one to reveal the deterioration and probable original appearance of artworks. Full Article text
rt Influence of device configuration and noise on a machine learning predictor for the selection of nanoparticle small-angle X-ray scattering models By journals.iucr.org Published On :: 2024-09-23 Small-angle X-ray scattering (SAXS) is a widely used method for nanoparticle characterization. A common approach to analysing nanoparticles in solution by SAXS involves fitting the curve using a parametric model that relates real-space parameters, such as nanoparticle size and electron density, to intensity values in reciprocal space. Selecting the optimal model is a crucial step in terms of analysis quality and can be time-consuming and complex. Several studies have proposed effective methods, based on machine learning, to automate the model selection step. Deploying these methods in software intended for both researchers and industry raises several issues. The diversity of SAXS instrumentation requires assessment of the robustness of these methods on data from various machine configurations, involving significant variations in the q-space ranges and highly variable signal-to-noise ratios (SNR) from one data set to another. In the case of laboratory instrumentation, data acquisition can be time-consuming and there is no universal criterion for defining an optimal acquisition time. This paper presents an approach that revisits the nanoparticle model selection method proposed by Monge et al. [Acta Cryst. (2024), A80, 202–212], evaluating and enhancing its robustness on data from device configurations not seen during training, by expanding the data set used for training. The influence of SNR on predictor robustness is then assessed, improved, and used to propose a stopping criterion for optimizing the trade-off between exposure time and data quality. Full Article text
rt Deep learning to overcome Zernike phase-contrast nanoCT artifacts for automated micro-nano porosity segmentation in bone By journals.iucr.org Published On :: 2024-01-01 Bone material contains a hierarchical network of micro- and nano-cavities and channels, known as the lacuna-canalicular network (LCN), that is thought to play an important role in mechanobiology and turnover. The LCN comprises micrometer-sized lacunae, voids that house osteocytes, and submicrometer-sized canaliculi that connect bone cells. Characterization of this network in three dimensions is crucial for many bone studies. To quantify X-ray Zernike phase-contrast nanotomography data, deep learning is used to isolate and assess porosity in artifact-laden tomographies of zebrafish bones. A technical solution is proposed to overcome the halo and shade-off domains in order to reliably obtain the distribution and morphology of the LCN in the tomographic data. Convolutional neural network (CNN) models are utilized with increasing numbers of images, repeatedly validated by `error loss' and `accuracy' metrics. U-Net and Sensor3D CNN models were trained on data obtained from two different synchrotron Zernike phase-contrast transmission X-ray microscopes, the ANATOMIX beamline at SOLEIL (Paris, France) and the P05 beamline at PETRA III (Hamburg, Germany). The Sensor3D CNN model with a smaller batch size of 32 and a training data size of 70 images showed the best performance (accuracy 0.983 and error loss 0.032). The analysis procedures, validated by comparison with human-identified ground-truth images, correctly identified the voids within the bone matrix. This proposed approach may have further application to classify structures in volumetric images that contain non-linear artifacts that degrade image quality and hinder feature identification. Full Article text
rt Enhancing electrospray ionization efficiency for particle transmission through an aerodynamic lens stack By journals.iucr.org Published On :: 2024-02-02 This work investigates the performance of the electrospray aerosol generator at the European X-ray Free Electron Laser (EuXFEL). This generator is, together with an aerodynamic lens stack that transports the particles into the X-ray interaction vacuum chamber, the method of choice to deliver particles for single-particle coherent diffractive imaging (SPI) experiments at the EuXFEL. For these experiments to be successful, it is necessary to achieve high transmission of particles from solution into the vacuum interaction region. Particle transmission is highly dependent on efficient neutralization of the charged aerosol generated by the electrospray mechanism as well as the geometry in the vicinity of the Taylor cone. We report absolute particle transmission values for different neutralizers and geometries while keeping the conditions suitable for SPI experiments. Our findings reveal that a vacuum ultraviolet ionizer demonstrates a transmission efficiency approximately seven times greater than the soft X-ray ionizer used previously. Combined with an optimized orifice size on the counter electrode, we achieve >40% particle transmission from solution into the X-ray interaction region. These findings offer valuable insights for optimizing electrospray aerosol generator configurations and data rates for SPI experiments. Full Article text
rt Ultrashort large-bandwidth X-ray free-electron laser generation with a dielectric-lined waveguide By journals.iucr.org Published On :: 2024-02-09 Large-bandwidth pulses produced by cutting-edge X-ray free-electron lasers (FELs) are of great importance in research fields like material science and biology. In this paper, a new method to generate high-power ultrashort FEL pulses with tunable spectral bandwidth with spectral coherence using a dielectric-lined waveguide without interfering operation of linacs is proposed. By exploiting the passive and dephasingless wakefield at terahertz frequency excited by the beam, stable energy modulation can be achieved in the electron beam and large-bandwidth high-intensity soft X-ray radiation can be generated. Three-dimensional start-to-end simulations have been carried out and the results show that coherent radiation pulses with duration of a few femtoseconds and bandwidths ranging from 1.01% to 2.16% can be achieved by changing the undulator taper profile. Full Article text
rt Investigation of structural and reflective characteristics of short-period Mo/B4C multilayer X-ray mirrors By journals.iucr.org Published On :: 2024-02-09 The results of a study of the structural and reflective characteristics of short-period multilayer X-ray mirrors based on Mo/B4C at wavelengths 1.54 Å, 9.89 Å and 17.59 Å are presented. The period of the samples varied in the range 8–35 Å. The average widths of the interfaces were ∼3.5 and 2.2 Å at one and the other boundaries, with a tendency for weak growth with any decrease in the period. The interlayer roughness was ∼1 Å. The research results indicate promising prospects for the use of multilayer Mo/B4C mirrors for synchrotron applications. Full Article text
rt High-pressure X-ray photon correlation spectroscopy at fourth-generation synchrotron sources By journals.iucr.org Published On :: 2024-04-10 A new experimental setup combining X-ray photon correlation spectroscopy (XPCS) in the hard X-ray regime and a high-pressure sample environment has been developed to monitor the pressure dependence of the internal motion of complex systems down to the atomic scale in the multi-gigapascal range, from room temperature to 600 K. The high flux of coherent high-energy X-rays at fourth-generation synchrotron sources solves the problems caused by the absorption of diamond anvil cells used to generate high pressure, enabling the measurement of the intermediate scattering function over six orders of magnitude in time, from 10−3 s to 103 s. The constraints posed by the high-pressure generation such as the preservation of X-ray coherence, as well as the sample, pressure and temperature stability, are discussed, and the feasibility of high-pressure XPCS is demonstrated through results obtained on metallic glasses. Full Article text