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The dysfunction of α and β cells in pancreatic islets can lead to diabetes. Many questions remain on the subcellular organization of islet cells during the progression of disease. Existing three-dimensional cellular mapping approaches face challenges such as time-intensive sample sectioning and subjective cellular identification. To address these challenges, we have developed a subcellular feature-based classification approach, which allows us to identify α and β cells and quantify their subcellular structural characteristics using soft X-ray tomography (SXT). We observed significant differences in whole-cell morphological and organelle statistics between the two cell types. Additionally, we characterize subtle biophysical differences between individual insulin and glucagon vesicles by analyzing vesicle size and molecular density distributions, which were not previously possible using other methods. These sub-vesicular parameters enable us to predict cell types systematically using supervised machine learning. We also visualize distinct vesicle and cell subtypes using Uniform Manifold Approximation and Projection (UMAP) embeddings, which provides us with an innovative approach to explore structural heterogeneity in islet cells. This methodology presents an innovative approach for tracking biologically meaningful heterogeneity in cells that can be applied to any cellular system. [ABSTRACT FROM AUTHOR]

The beamline optics and endstations at branch B of the Versatile Soft X-ray (VerSoX) beamline B07 at Diamond Light Source are described. B07-B provides medium-flux X-rays in the range 45-2200 eV from a bending magnet source, giving access to local electronic structure for atoms of all elements from Li to Y. It has an endstation for high-throughput X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine-structure (NEXAFS) measurements under ultrahigh-vacuum (UHV) conditions. B07-B has a second endstation dedicated to NEXAFS at pressures from UHV to ambient pressure (1 atm). The combination of these endstations permits studies of a wide range of interfaces and materials. The beamline and endstation designs are discussed in detail, as well as their performance and the commissioning process. [ABSTRACT FROM AUTHOR]

The soft X-ray photoelectron momentum microscopy (PMM) experimental station at the UVSOR Synchrotron Facility has been recently upgraded by additionally guiding vacuum ultraviolet (VUV) light in a normal-incidence configuration. PMM offers a very powerful tool for comprehensive electronic structure analyses in real and momentum spaces. In this work, a VUV beam with variable polarization in the normal-incidence geometry was obtained at the same sample position as the soft X-ray beam from BL6U by branching the VUV beamline BL7U. The valence electronic structure of the Au(111) surface was measured using horizontal and vertical linearly polarized (s-polarized) light excitations from BL7U in addition to horizontal linearly polarized (p-polarized) light excitations from BL6U. Such highly symmetric photoemission geometry with normal incidence offers direct access to atomic orbital information via photon polarization-dependent transition-matrix-element analysis. [ABSTRACT FROM AUTHOR]

A first-of-its-kind, inductively driven micro-particle (Pellet) accelerator and injector have been developed and operated successfully in ADITYA-U circular plasma operations, which may ably address the critical need for a suitable disruption control mechanism in ITER and future tokamak. The device combines the principles of electromagnetic induction, pulse power technology, impact, and fracture dynamics. It is designed to operate in a variety of environments, including atmospheric pressure and ultra-high vacuum. It can also accommodate a wide range of pellet quantities, sizes, and materials and can adjust the pellets' velocities over a coarse and fine range. The device has a modular design such that the maximum velocity can be increased by increasing the number of modules. A cluster of lithium titanate/carbonate (Li2TiO3/Li2CO3) impurity particles with variable particle sizes, weighing ∼50–200 mg are injected with velocities of the order of ∼200 m s−1 during the current plateau in ADITYA-U tokamak. This leads to a complete collapse of the plasma current within ∼5–6 ms of triggering the injector. The current quench time is dependent on the amount of impurity injected as well as the compound, with Li2TiO3 injection causing a faster current quench than Li2CO3 injection, as more power is radiated in the case of Li2TiO3. The increase in radiation due to the macro-particle injection starts in the plasma core, while the soft x-ray emission indicates that the entire plasma core collapses at once. [ABSTRACT FROM AUTHOR]

This report is on the characterization of active Ti center in heterogeneous Ziegler-Natta catalysts by Soft X-ray Emission Spectrometry (SXES). Since titanium in the catalyst has various chemical bonds, it is important to grasp the chemical bond state. The outermost shell electrons are very important for understanding the chemical bond state. SXES is the only method that can easily observe outermost shell electrons with current analytical instruments. Here, a co-milled solid of MgCl2, TiCl4, and phthalate was used as a catalyst precursor, and three types of catalysts with significantly different catalytic activity levels were synthesized by changing the subsequent preparation process. The correlation between catalytic activity and the signal shape of Lα,β emission, which is the outermost shell electron of Ti in SXES analysis, was investigated. Lα,β emission was detected as broad signal. It could be observed that the high active catalyst had a relatively strong signal intensity at the high energy side. The shape changes were also checked when the catalyst solids were treated by triethylaluminum. By this treatment, the relative intensity of the high energy side signal enhanced further, suggesting that the triethylaluminum treatment induced the elimination of inactive Ti from the catalyst solid. By comparing with the solid 13C-NMR analyses data of the Ziegler-Natta catalyst described in our previous report, the high energy side signal of Ti Lα,β in SXES results implies the relationship with the NMR results for carbonyl function. [ABSTRACT FROM AUTHOR]

We quantise from first principles field theories living on the background of a bubble wall in the planar limit with particular focus on the case of spontaneous breaking of gauge symmetry. Using these tools, we compute the average momentum transfer from transition radiation: the soft emission of radiation by an energetic particle passing across the wall, with a particular focus on the longitudinal polarisation of vectors. We find these to be comparable to transverse polarisations in symmetry-breaking transitions with mild super-cooling, and dominant in broken to broken transitions with thin wall. Our results have phenomenological applications for the expansion of bubbles during first order phase transitions. Our general framework allows for the robust calculation of any particle processes of interest in such translation breaking backgrounds. [ABSTRACT FROM AUTHOR]

The accurate assessment of peanut seed plumpness is crucial for optimizing peanut production and quality. The current method is mainly manual and visual inspection, which is very time-consuming and causes seed deterioration. A novel imaging technique is used to enhance the detection of peanut seed fullness using a non-destructive soft X-ray, which is suitable for the analysis of the surface or a thin layer of a material. The overall grayscale of the peanut is similar to the background, and the edge of the peanut seed is blurred. The inaccuracy of peanut overall and peanut seed segmentation leads to low accuracy of seed plumpness detection. To improve accuracy in detecting the fullness of peanut seeds, a seed plumpness detection method based on level set and multi-threshold segmentation was proposed for peanut images. Firstly, the level set algorithm is used to extract the overall contour of peanuts. Secondly, the obtained binary image is processed by morphology to obtain the peanut pods (the peanut overall). Then, the multi-threshold OTSU algorithm is used for threshold segmentation. The threshold is selected to extract the peanut seed part. Finally, morphology is used to complete the cavity to achieve the segmentation of the peanut seed. Compared with optimization algorithms, in the segmentation of the peanut pods, average random index (RI), global consistency error (GCE) and variation of information (VI) were increased by 10.12% and decreased by 0.53% and 24.11%, respectively. Compared with existing algorithms, in the segmentation of the peanut seed, the average RI, VI and GCE were increased by 18.32% and decreased by 9.14% and 6.11%, respectively. The proposed method is stable, accurate and can meet the requirements of peanut image plumpness detection. It provides a feasible technical means and reference for scientific experimental breeding and testing grading service pricing. [ABSTRACT FROM AUTHOR]

Extreme ultraviolet (EUV) light is difficult to focus due to strong absorption of most materials. Photon sieves (PS), rather than Fresnel zone plates (FZP), can focus EUV to smaller spot and suppress the higher orders of secondary maxima by several orders of magnitude. The number of pinholes used in PS is far more than that of transparent rings used in FZP, providing a great flexibility to manipulate structured focusing in EUV. In this work we investigate the Fermat-spiral PS to produce focused vortices with different topological charges. Experiment at the wavelength of 46.9 nm is carried out and multi-planar coherent diffractive imaging is used to retrieve the phase map of the focused EUV vortices. These results show the enormous potential of PS for manipulating EUV light. This study not only provides a compact, affordable substitute to focusing vortices where transmissive optics materials are unavailable, but also provides a route of converting various complex light manipulation ranging from visible light to EUV and soft x-ray. [ABSTRACT FROM AUTHOR]

Joule heating is one of the main energy inputs into the thermosphere‐ionosphere system. Precise modeling of this process is essential for any space weather application. Existing thermosphere‐ionosphere models tend to underestimate the actual Joule heating rate quite significantly. The Thermosphere‐Ionosphere‐Electrodynamics General‐Circulation‐Model applies an empirical scaling factor of 1.5 for compensation. We calculate vertical profiles of Joule heating rates from approximately 2,220 hr of measurements with the EISCAT incoherent scatter radar and the corresponding model runs. We investigate model runs with the plasma convection driven by both the Heelis and the Weimer model. The required scaling of the Joule heating profiles is determined with respect to the Kp index, the Kan‐Lee merging electric field EKL, and the magnetic local time. Though the default scaling factor of 1.5 appears to be adequate on average, we find that the required scaling varies strongly with all three parameters ranging from 0.46 to ∼20 at geomagnetically disturbed and quiet times, respectively. Furthermore, the required scaling is significantly different in runs driven by the Heelis and Weimer model. Adjusting the scaling factor with respect to the Kp index, EKL, the magnetic local time, and the choice of convection model would reduce the difference between Joule heating rates calculated from measurement and model plasma parameters. Plain Language Summary: The vast majority of the energy input to the Earth system originates from the sun. This includes the absorption of various types of radiation, for example, ultraviolet radiation in the ozone layer or visible light and infrared radiation at the surface. In the upper atmosphere above about 80 km altitude, the absorption of extreme ultraviolet radiation and soft X‐rays plays a major role. However, other processes also contribute significantly to the heating of this region, for example, the energy dissipation in the form of electric currents flowing along electric fields, also known as Joule heating. Joule heating is highly variable and can be drastically enhanced especially during solar storms, which can have potentially disastrous effects on satellites. Accurate modeling, and therefore also prediction, of Joule heating is not possible at the moment since thermosphere‐ionosphere models have to scale the Joule heating empirically to fit the actual values. We investigate how the required scaling changes under different geophysical conditions. Key Points: The constant Joule heating scaling factor in TIE‐GCM is inadequate to compensate for the underestimation under various geomagnetic conditionsJoule heating rates calculated from 2,220 hr of EISCAT measurements are compared to TIE‐GCM runs driven with the Heelis and Weimer convection modelsThe required scaling factor varies significantly with the Kp index, the Kan‐Lee merging electric field, and the magnetic local time [ABSTRACT FROM AUTHOR]

Imaging has been an important strategy for exploring space weather. The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) is a joint Chinese Academy of Sciences (CAS) and European Space Agency (ESA) mission, aiming at studying the interaction between Earth's magnetosphere and solar wind near the subsolar point via soft X-ray imaging. As the boundary of Earth's magnetosphere, magnetopause is a significant detection target to mirror solar wind's change for the SMILE mission. In preparation for inverting three-dimensional magnetopause, we proposed an OESA-UNet model to detect the magnetopause position. The model obtains magnetopause with a U-shaped structure, in an end-to-end manner. Inspired by attention mechanisms, these blocks are integrated into ours. OESA-UNet captures low and high-level feature maps by adjusting the receptive field for precise localization. Adaptively pre-processing the image provides a prior for the network. Availability metrics are designed to determine whether it can serve three-dimensional inversion. Lastly, we provided ablation and comparison experiments by qualitative and quantitative analysis. Our recall, precision, and f1 score are 93.8%, 92.1%, and 92.9%, respectively, with an average angle deviation of 0.005 under the availability metrics. Results indicate that OESA-UNet outperforms other methods. It can better serve the purpose of magnetopause tracing from an X-ray image. [ABSTRACT FROM AUTHOR]

Vanadium nitride (VN) is a transition-metal nitride with remarkable properties that have prompted extensive experimental and theoretical investigations in recent years. However, there is a current paucity of experimental research investigating the temperature-dependent electronic structure of single-crystalline VN. In this study, high-quality VN(111) films were successfully synthesized on α -Al 2 O 3 (0001) substrates using magnetron sputtering. The crystal and electronic structures of the VN films were characterized by a combination of high-resolution X-ray diffraction, low-energy electron diffraction, resonant soft X-ray absorption spectroscopy, and ultraviolet photoelectron spectroscopy. The electrical transport measurements indicate that the superconducting critical temperature of the VN films is around 8.1 K. Intriguingly, the temperature-dependent photoelectron spectroscopy measurements demonstrate a weak temperature dependence in the electronic structure of the VN films, which is significant for understanding the ground state of VN compounds. [ABSTRACT FROM AUTHOR]

Extreme Ultraviolet (EUV) radiation is a short-wavelength light source that has important applications in many fields, such as optical communication, particle manipulation, and ultrahigh resolution imaging. However, the highly absorptive nature of EUV light makes it challenging to design suitable focusing optics, such as focal splitters, to properly manipulate the energetic light. Here, we propose modified spiral photon sieves to transform EUV laser light into azimuthally splitting focusing. A genetic algorithm was used to design and optimize the azimuthally focal splitters. A capillary discharge EUV laser at 46.9 nm was used to verify the effectiveness of our proposed method, and PMMA targets were used to record the focused laser spot. The profile of the recorded patterns measured by atomic force microscopy shows that the focal spots in the experiment are diffraction-limited and agreed with the theoretical analysis. The proposed technique provides a new way for manipulating EUV light and further extends the applications ranging from EUV to soft x rays. [ABSTRACT FROM AUTHOR]

Surface acoustic waves (SAWs) are excited by femtosecond extreme ultraviolet (EUV) transient gratings (TGs) in a room-temperature ferrimagnetic DyCo5 alloy. TGs are generated by crossing a pair of EUV pulses from a free electron laser with the wavelength of 20.8 nm matching the Co M-edge, resulting in a SAW wavelength of Λ = 44 nm. Using the pump-probe transient grating scheme in reflection geometry, the excited SAWs could be followed in the time range of −10 to 100 ps in the thin film. Coherent generation of TGs by ultrafast EUV pulses allows to excite SAW in any material and to investigate their couplings to other dynamics, such as spin waves and orbital dynamics. In contrast, we encountered challenges in detecting electronic and magnetic signals, potentially due to the dominance of the larger SAW signal and the weakened reflection signal from underlying layers. A potential solution for the latter challenge involves employing soft x-ray probes, albeit introducing additional complexities associated with the required grazing incidence geometry. [ABSTRACT FROM AUTHOR]

A microbunching instability (MBI) driven by beam collective effects can deteriorate electron beam quality in advanced x-ray free electron lasers. In this paper, we demonstrate a scheme to suppress microbunching instability by adjusting the compression ratio of two-stage bunch compressor in linear accelerator of the Shanghai soft X-ray Free-Electron Laser User Facility (SXFEL-UF). The calculation of the microbunching instability gain and the mechanism of MBI suppression scheme can be revealed by the theoretical model in this paper. Numerical simulations are presented to verify the analytical results. Furthermore, benefit by the high temporal resolution of transverse deflecting structure (TDS), beam experiments for direct analysis of MBI were carried out at SXFEL-UF. Theoretical calculations as well as simulation and consistent experimental results illustrate that the suppression of microbunching instability can be achieved by increasing the first stage compression ratio of the linac in the SXFEL-UF. The feasible theme provides a promising beam optimization method for future X-FEL facilities. [ABSTRACT FROM AUTHOR]

Hepatitis C virus (HCV) is an enveloped RNA virus. One of the hallmarks of HCV infection is a rearrangement of the host cell membranes, known as the 'membranous web'. Full‐field cryo soft X‐ray tomography (cryo‐SXT) in the water‐window energy range (284–543 eV) was performed on the MISTRAL beamline to investigate, in whole unstained cells, the morphology of the membranous rearrangements induced in HCV replicon‐harbouring cells in conditions close to the living physiological state. All morphological alterations could be reverted by a combination of sofosbuvir/daclatasvir, which are clinically approved antivirals (direct‐acting antivirals; DAAs) for HCV infection. Correlatively combining cryo‐SXT and 2D synchrotron‐based infrared microscopy provides critical information on the chemical nature of specific infection‐related structures, which allows specific patterns of the infection process or the DAA‐mediated healing process to be distinguished. [ABSTRACT FROM AUTHOR]

Hard x-ray photoelectron spectroscopy (HAXPES) is a powerful technique to characterize the chemical and electronic structures of materials. In energy conversion devices, often composed of a stack of thin layers and thus containing multiple buried interfaces, the increased probing depth of HAXPES, compared to conventional x-ray photoelectron spectroscopy, makes it a technique of choice to ultimately reveal a more comprehensive device-relevant picture. In this contribution, we provide a brief review of recent HAXPES experiments conducted at the High Kinetic Energy Photoelectron Spectrometer endstation located at the BESSY II KMC-1 beamline at Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, focusing on three different prominent sample material systems widely used in energy conversion devices: (1) Cu-chalcogenides, (2) metal oxides, and (3) halide perovskites. The findings revealed by these studies highlight the advantage of knowledge-based heterointerface design in energy conversion devices, building interface models based on direct measurements targeting the entire structure as only possible by HAXPES. We conclude by giving an update on the new and enhanced HAXPES experimental capabilities starting to be offered by the Energy Materials In-situ Laboratory Berlin facility. [ABSTRACT FROM AUTHOR]

Symbiotic stars are long-period interacting binaries where the compact object, most commonly a white dwarf, is embedded in the dense stellar wind of an evolved companion star. Ultraviolet and soft X-ray emission of the accretion disc and the nuclear-burning white dwarf plays a major role in shaping the ionization balance of the surrounding wind material, giving rise to the rich line emission. In this paper, we employ two-dimensional photoionization calculations based on the cloudy code to study the ionization state of the circumbinary material in symbiotic systems and to predict their emission-line spectra. Our simulations are parametrized via the orbital parameters of the binary and the wind mass-loss rate of the donor star, while the mass accretion rate, temperature and luminosity of the white dwarf are computed self-consistently. We explore the parameter space of symbiotic binaries and compute luminosities of various astrophysically important emission lines. The line ratios are compared with traditional diagnostic diagrams used to distinguish symbiotic binaries from other types of sources, and it is shown how the binary system parameters shape these diagrams. In the significant part of the parameter space, the wind material is nearly fully ionized, except for the 'shadow' behind the donor star, so the white dwarf emission is typically freely escaping the system. [ABSTRACT FROM AUTHOR]

FeNi film was fabricated on Cu/MgO (001) substrates using thermal evaporation technique of a FeNi target to realize the formation of an L10‐FeNi phase. The magnetic anisotropy of FeNi film was systematically investigated by means of X‐ray absorption spectroscopy (XAS) and X‐ray magnetic circular dichroism (XMCD) techniques. Our L‐edge XAS and XMCD analysis is performed for 30‐nm FeNi film grown on Cu/MgO (001) substrate. The present experimental results of XAS and XMCD indicate that ~5% Fe atoms are oxidized. Our findings also showed that the orbital magnetic moment of Fe has a significant incident X‐ray angle dependence that exhibits a maximum value at the out‐of‐plane direction corresponding perpendicular to the plane. The origin of anisotropy is successfully explained by element‐specific XMCD technique. The enhancement in magnetic anisotropy energy (MAE) is due to orbital magnetic moments of Fe through spin–orbit interaction. The uniaxial anisotropy energy showed quantitatively good agreement with the volume MAE. [ABSTRACT FROM AUTHOR]

Context. Pre-main sequence stars are variable sources. The main mechanisms responsible for their variability are variable extinction, unsteady accretion, and rotational modulation of both hot and dark photospheric spots and X-ray-active regions. In stars with disks, this variability is related to the morphology of the inner circumstellar region (≤0.1AU) and that of the photosphere and corona, all impossible to be spatially resolved with present-day techniques. This has been the main motivation for the Coordinated Synoptic Investigation of NGC 2264, a set of simultaneous observations of NGC 2264 with 15 different telescopes. Aims. In this paper, we focus on the stars with disks. We analyze the X-ray spectral properties extracted during optical bursts and dips in order to unveil the nature of these phenomena. Stars without disks are studied in a companion paper. Methods. We analyze simultaneous CoRoT and Chandra/ACIS-I observations to search for coherent optical and X-ray flux variability in stars with disks. Then, stars are analyzed in two different samples. In stars with variable extinction, we look for a simultaneous increase of optical extinction and X-ray absorption during the optical dips; in stars with accretion bursts, we search for soft X-ray emission and increasing X-ray absorption during the bursts. Results. We find evidence for coherent optical and X-ray flux variability among the stars with variable extinction. In 9 of the 24 stars with optical dips, we observe a simultaneous increase of X-ray absorption and optical extinction. In seven dips, it is possible to calculate the NH/AVV ratio in order to infer the composition of the obscuring material. In 5 of the 20 stars with optical accretion bursts, we observe increasing soft X-ray emission during the bursts that we associate to the emission of accreting gas. It is not surprising that these properties are not observed in all the stars with dips and bursts, since favorable geometric configurations are required. Conclusions. The observed variable absorption during the dips is mainly due to dust-free material in accretion streams. In stars with accretion bursts, we observe, on average, a larger soft X-ray spectral component not observed in non-accreting stars. [ABSTRACT FROM AUTHOR]

Mid-Z dopant in ablator is very important in point design targets. In this paper, we develop a method to evaluate the soft x-ray transport of doped material with one dimensional planar target. The targets are designed as sandwich, so that the mid-layer is heated by M band, shock and thermal wave. The transmission fluxes from heated targets are measured with band-pass x-ray diodes. The Si and Ge dopants are evaluated with this method. The experimental results show that 1-1.6 keV x-ray transmission flux through Si-sandwich is higher than that through Ge-sandwich all the time. Also, the comparison of opacities shows that the opacity of Si is lower than that of Ge in the range of 1-1.6 keV, which is consistent with the experimental results. [ABSTRACT FROM AUTHOR]

Understanding the lateral variations in the elemental and chemical state of constituents induced by electrochemical reactions at nanoscales is crucial for the advancement of electrochemical materials science. This requires in situ studies to provide observables that contribute to both modeling beyond the phenomenological level and exactly transducing the functionally relevant quantities. A range of X-ray coherent diffraction imaging (CDI) approaches have recently been proposed for imaging beyond the diffraction limit with potentially dramatic improvements in time resolution with chemical sensitivity. In this paper, we report a selection of ptychography results obtained in situ during the electrodeposition of a metal-polymer nanocomposite. Our selection includes dynamic imaging during electrochemically driven growth complemented with absorption and phase spectroscopy with high lateral resolution. We demonstrate the onset of morphological instability feature formation and correlate the chemical state of Mn with the local growth rate controlled by the current density distribution resulting from morphological evolution. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a new method to calibrate the absolute sensitivity of a soft X-ray streak camera (SXRSC). The calibrations are done in the static mode by using a small laser-produced X-ray source. A calibrated X-ray CCD is used as a secondary standard detector to monitor the X-ray source intensity. In addition, two sets of holographic flat-field grating spectrometers are chosen as the spectral discrimination systems of the SXRSC and the X-ray CCD. The absolute sensitivity of the SXRSC is obtained by comparing the signal counts of the SXRSC to the output counts of the X-ray CCD. Results show that the calibrated spectrum covers the range from 200 eV to 1040 eV. The change of the absolute sensitivity in the vicinity of the K-edge of the carbon can also be clearly seen. The experimental values agree with the calculated values to within 29% error. Compared with previous calibration methods, the proposed method has several advantages: a wide spectral range, high accuracy, and simple data processing. Our calibration results can be used to make quantitative X-ray flux measurements in laser fusion research. [ABSTRACT FROM AUTHOR]

The soft X-ray (SXR) emission provides valuable insight into processes happening inside of hightemperature plasmas. A standard method for deriving the local emissivity profiles of the plasma from the line-of-sight integrals measured by pinhole cameras is the tomographic inversion. Such an inversion is challenging due to its ill-conditioned nature and because the reconstructed profiles depend not only on the quality of the measurements but also on the inversion algorithm used. This paper provides a detailed description of several tomography algorithms, which solve the inversion problem of Tikhonov regularization with linear computational complexity in the number of basis functions. The feasibility of combining these methods with the minimum Fisher information regularization is demonstrated, and various statistical methods for the optimal choice of the regularization parameter are investigated with emphasis on their reliability and robustness. Finally, the accuracy and the capability of the methods are demonstrated by reconstructions of experimental SXR profiles, featuring poloidal asymmetric impurity distributions as measured at the ASDEX Upgrade tokamak. [ABSTRACT FROM AUTHOR]

Two-thirds of long duration gamma-ray bursts (GRBs) show soft X-ray absorption in excess of the Milky Way. The column densities of metals inferred from UV and optical spectra differ from those derived from soft X-ray spectra, at times by an order of magnitude, with the latter being higher. The origin of the soft X-ray absorption excess observed in GRB X-ray afterglow spectra remains a heavily debated issue, which has resulted in numerous investigations on the effect of hot material both internal and external to the GRB host galaxy on our X-ray afterglow observations. Nevertheless, all models proposed so far have either only been able to account for a subset of our observations (i.e. at z > 2), or they have required fairly extreme conditions to be present within the absorbing material. In this paper, we investigate the absorption of the GRB afterglow by a collisionally ionised and turbulent interstellar medium (ISM). We find that a dense (3 cm-3) collisionally ionised ISM could produce UV/optical and soft X-ray absorbing column densities that differ by a factor of 10. However the UV/optical and soft X-ray absorbing column densities for such sightlines are 2-3 orders of magnitude lower in comparison to the GRB afterglow spectra. For those GRBs with a larger soft X-ray excess by up to an order of magnitude, the contribution in absorption from a turbulent ISM as considered here would ease the required conditions of additional absorbing components, such as the GRB circumburst medium and intergalactic medium. [ABSTRACT FROM AUTHOR]

Various types of targetry are used nowadays in laser matter interaction experiments. Such targets are characterized using different methods capable of acquiring information about the targets such as density, spatial distribution, and temporal behavior. In this mini-review paper, a particular type of target will be presented. The targets under consideration are gas puff targets of various and novel geometries. Those targets were investigated using extreme ultraviolet (EUV) and soft X-ray (SXR) imaging techniques, such as shadowgraphy, tomography, and pinhole camera imaging. Details about characterization of those targets in the EUV and SXR spectral regions will be presented. [ABSTRACT FROM AUTHOR]

θ Car is a bright well studied B0 type star in a close binary (P orb = 2.2 d) with an unseen companion. The system has enjoyed extensive spectroscopic characterization at multiple wavelengths, revealing narrow X-ray lines, a soft X-ray tail, and chemical peculiarities. The star was recently observed in high-cadence photometric time-series by the NASA TESS satellite. In this paper, we investigate the photometric variability and demonstrate that it is likely associated with surface brightness inhomogeneities rather than orbital modulation. We investigate the potential distribution of surface features required to produce the observed variability, and report a new rotational period of P rot = 2.2034 d to be commensurate with the orbital period. [ABSTRACT FROM AUTHOR]

X-ray films remain a key asset for high-resolution x-ray spectral imaging in high-energy-density experiments conducted at the National Ignition Facility (NIF). The soft x-ray Opacity Spectrometer (OpSpec) fielded at the NIF has an elliptically shaped crystal design that measures x rays in the 900–2100 eV range and currently uses an image plate as the detecting medium. However, Agfa D4 and D3sc x-ray films' higher spatial resolution provides increased spectral resolution to the data over the IP-TR image plates, driving the desire for regular use of x-ray film as a detecting medium. The calibration of Agfa D4 x-ray film for use in the OpSpec is communicated here. These calibration efforts are vital to the accuracy of the NIF opacity measurements and are conducted in a previously un-studied x-ray energy range under a new film development protocol required by NIF. The absolute response of Agfa D4 x-ray film from 705 to 4620 eV has been measured using the Nevada National Security Site Manson x-ray source. A broader range of energies was selected to compare results with previously published data. The measurements were taken using selected anodes, filters, and applied voltages to produce well-defined energy lines. [ABSTRACT FROM AUTHOR]

Synchrotron radiation can induce sample damage, whether intended or not. In the case of sensitive samples, such as biological ones, modifications can be significant. To understand and predict the effects due to exposure, it is necessary to know the ionizing radiation dose deposited in the sample. In the case of aqueous samples, deleterious effects are mostly induced by the production of reactive oxygen species via water radiolysis. These species are therefore good indicators of the dose. Here the application of a microfluidic cell specifically optimized for low penetrating soft X‐ray radiation is reported. Sodium benzoate was used as a fluorescent dosimeter thanks to its specific detection of hydroxyl radicals, a radiolytic product of water. Measurements at 1.28 keV led to the determination of a hydroxyl production yield, G(HO.), of 0.025 ± 0.004 µmol J−1. This result is in agreement with the literature and confirms the high linear energy transfer behavior of soft X‐rays. An analysis of the important parameters of the microfluidic dosimetry cell, as well as their influences over dosimetry, is also reported. [ABSTRACT FROM AUTHOR]

The mutual optical intensity (MOI) model is extended to the simulation of the interference pattern produced by extreme ultraviolet lithography with partially coherent light. The partially coherent X‐ray propagation through the BL08U1B beamline at Shanghai Synchrotron Radiation Facility is analysed using the MOI model and SRW (Synchrotron Radiation Workshop) method. The fringe intensity at the exposure area is not uniform but has similar envelope lines to Fresnel diffraction, which is explained by the diffraction from the finite grating modelled as a single aperture. By balancing the slit size and photon stop size, the fringe visibility, photon flux and intensity slope can be optimized. Further analysis shows that the effect of pink light on the aerial images is negligible, whereas the third‐harmonic light should be considered to obtain a balance between high fringe visibility and high flux. Two grating interference exposure experiments were performed in the BL08U1B beamline. The aerial image depth showed that the polymethyl methacrylate photoresist depth was determined by the X‐ray coherence properties. [ABSTRACT FROM AUTHOR]

In this work, we report the electronic and magnetic properties of epitaxial BiFeO3 (BFO) thin film deposited on SrTiO3 (001) substrate via the chemical solution deposition technique. These properties of pure BFO thin films were characterized by X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism techniques (XMCD). The large magnetization at Fe-edge could be due to annealing in nitrogen. Annealing in nitrogen atmosphere increases the grain size and porosity which lead to create more oxygen vacancy. The presence of oxygen vacancies which compensate the bismuth vacancies created due to bismuth volatilization. The origin of large orbital momentum in BFO thin film is also discussed. The O K-edge spectra display large spectral variation depending on the polarization vector E. The structural distortion at oxygen octahedral induces large anisotropy due to Fe 3d–O 2p hybridization. The hybridized Fe 3d orbitals contribute a much larger orbital momentum in BFO thin film. [ABSTRACT FROM AUTHOR]

IGR J17091−3624 is a transient galactic black hole which has a distinct quasi-periodic variability known as 'heartbeat', similar to the one observed in GRS 1915 + 105. In this paper, we report the results of ∼125 ks AstroSat observations of this source during the 2016 outburst. For the first time, a double-peaked QPO (DPQ) is detected in a few time segments of this source with a difference of δ f   ∼ 12 mHz between the two peaks. The nature of the DPQ was studied based on hardness ratios and using the static as well as the dynamic power spectrum. Additionally, a low-frequency (25–48 mHz) 'heartbeat' single-peak QPO (SPQ) was observed at different intervals of time along with harmonics (50–95 mHz). Broad-band spectra in the range 0.7–23 keV, obtained with Soft X-ray Telescope and Large Area X-ray Proportional Counter , could be fitted well with combination of a thermal Comptonization and a multicolour disc component model. During AstroSat observation, the source was in the soft-intermediate state (SIMS) as observed with Swift /XRT. We present a comparative study of the 'heartbeat' state variability in IGR J17091−3624 with GRS 1915 + 105. Significant difference in the timing properties is observed although spectral parameters (Γ ∼ 2.1–2.4 and T max ∼ 0.6–0.8 keV) in the broad energy band remain similar. Spectral properties of segments exhibiting SPQ and DPQ are further studied using simple phase-resolved spectroscopy which does not show a significant difference. Based on the model parameters, we obtain the maximum ratio of mass accretion rate in GRS 1915 + 105 to that in IGR J17091−3624 as ∼25: 1. We discuss the implications of our findings and comment on the physical origin of these exotic variabilities. [ABSTRACT FROM AUTHOR]

We developed a 2-mm-thick CdTe double-sided strip detector (CdTe-DSD) with a 250 μ m strip pitch, which has high spatial resolution with a uniform large imaging area of 10 cm 2 and high energy resolution with high detection efficiency in tens to hundreds keV. The detector can be employed in a wide variety of fields for quantitative observations of hard X-ray and soft gamma-ray with spectroscopic imaging, for example, space observation, nuclear medicine, and non-destructive elemental analysis. This detector is thicker than the 0.75-mm-thick one previously developed by a factor of ∼ 2.7, thus providing better detection efficiency for hard X-rays and soft gamma rays. The increased thickness could potentially enhance bias-induced polarization if we do not apply sufficient bias and if we do not operate at a low temperature, but the polarization is not evident in our detector when a high voltage of 500 V is applied to the CdTe diode and the temperature is maintained at − 20 °C during one-day experiments. The "Depth Of Interaction" (DOI) dependence due to the CdTe diode's poor carrier-transport property is also more significant, resulting in much DOI information while complicated detector responses such as charge sharings or low-energy tails that exacerbate the loss in the energy resolution. In this paper, we developed 2-mm-thick CdTe-DSDs, studied their response, and evaluated their energy resolution, spatial resolution, and uniformity. We also constructed a theoretical model to understand the detector response theoretically, resulting in reconstructing the DOI with an accuracy of 100 μ m while estimating the carrier-transport property. First, we evaluated the energy resolution using 22Na, 133Ba, and 57Co reconstructing the DOI effect from the energy correlation on both the anode and cathode sides. We obtained an energy resolution of 4.3 keV (FWHM) at 356 keV. Second, we formulated a theoretical detector-response model that reproduced the experimental data. Using the model, we determined the mobility-lifetime products of carriers μ τ e , h = (4 ± 1) × 1 0 − 3 , (1. 15 ± 0. 05) × 1 0 − 4 [cm 2 /V] with the space charge density of n s p = − 6. 0 × 1 0 10 [1/cm − 3 ] and then reconstructed the DOI with an accuracy of 100 μ m. Finally, we evaluated the spatial resolution and demonstrated to resolve patterns of 250- μ m -width slits with an X-ray test chart. We found no positional variation in the detector response. We realized the detector that has high energy resolution and high 3D spatial resolution with a uniform large imaging area. [ABSTRACT FROM AUTHOR]

A transmission diffraction grating is a useful tool for studying spectra in the soft X-ray and extreme ultraviolet range, created by the radiation of small–sized sources, such as laser produced plasma, vacuum spark, Z-pinch, X-pinch, etc. In almost all such experiments, a distance between the source and the grating is much larger than the size of the source, so the incident wave can be considered plane with sufficient accuracy, the distance from the recording detector to the grating is also much larger than the size of the grating and, therefore, Fraunhofer diffraction takes place here and the presence of a focusing element is not required. The interpretation of the results obtained using such a grating is difficult due to the fact that different diffraction orders overlap in the registered diffraction pattern. Therefore, there is a problem of reconstruction the true spectrum from an experimental diffraction pattern. In this paper, this problem is solved by approximating the function of the radiation intensity recorded on the diffraction pattern by a polynomial. In this case, due to the properties of the transmission diffraction grating, the desired function describing the spectrum being reconstructed is also a polynomial, which can be calculated according to the developed algorithm. Both the direct conversion of the spectrum into the diffraction pattern and the reverse conversion of the diffraction pattern into the spectrum do not change the radius of convergence, since multiplication is carried out by multipliers uniformly bounded from above and below. It follows from this that minor errors in the definition of the function describing the diffraction pattern cannot lead to significant errors in the reconstructed spectrum. [ABSTRACT FROM AUTHOR]

• Image recognition of cracks inside maize seeds based on soft X-rays. • Image enhancement of soft X-ray images was implemented with effective results. • The YOLOv8 model was used and optimized and compared. The current investigation on image recognition and internal crack detection of maize seeds primarily relies on visible light imaging. However, due to the low transmissivity of plant cells, even with image enhancement measures, the clarity of internal cracks in the images and the subsequent feature extraction process can be a trade-off. Soft X-rays possess exceptional penetration capability and offer better safety and convenience compared to hard X-rays, making them highly suitable for visualizing internal structures within plant tissues like maize seeds. In this paper, a non-invasive Imaging Technique for Image Enhancement is proposed, combining wavelet thresholding denoising, image standardization, bilateral filtering, and laplacian sharpening. This method is based on soft X-rays and successfully achieves image recognition of cracks present inside Zhengdan 958 maize seeds using an optimized YOLOv8 model. It effectively addresses challenges related to the limited light transmission of maize seeds, difficulty in crack localization, and algorithm generalization issues. The optimized YOLOv8 model demonstrates an average precision (AP) value that is 3.1% higher than that of the original model. Furthermore, by applying image enhancement, the AP value increases by 1.8%. The proposed method exhibits an average recognition accuracy of 99.66% for intact or broken seeds, an average precision of 99.87%, an average recognition recall of 99.48%, and an average single-frame image detection time of 7.49 ms in the single seed detection experiment. [ABSTRACT FROM AUTHOR]

The Korea fourth-generation storage ring (Korea-4GSR) has a low electron beam emittance of 60 p.m.-rad, and provides a photon beam that is 100 times brighter and 100 times more coherent than the third-generation Pohang Light Source (PLS-II). However, the new source imposes a higher heat load on beamline optics. In particular, the first mirror (M1), which receives the broad-bandwidth white beam will be distorted by the thermal load from X-ray beam and the heat bump will degrade the beam quality. For the thermal analysis of M1, a method is developed to solve the thermal deformation with temperature gradient and absorbed power density. To implement the method in the analysis of heat load effect on M1, a benchmark study was performed on beamline 8A at PLS-II. In this paper, we describe the thermal analysis of M1 in Korea-4GSR after verifying our simulation method in a benchmark study. [ABSTRACT FROM AUTHOR]

Free-electron lasers are capable of producing high-quality radiation in a wide wavelength range and at very high power and brilliance. To reach improved performance especially regarding coherence, bandwidth and wavelength stability, different seeding techniques are often required. However, a successful implementation of seeding typically demands a very high-quality electron beam, in terms of energy distribution and emittance. Techniques like Echo-Enabled Harmonic Generation (EEHG) and High-Brightness SASE (HB-SASE) require, or are significantly enhanced, by a flat distribution of particles in the longitudinal phase space. In this paper we describe how the initially chirped longitudinal phase space in the proposed Soft X-ray Laser (SXL) at the MAX IV laboratory can be tailored by first overcompressing and then de-chirping the electron pulse. We also show that it is possible to retain the properties of the electron bunch and how such an enhanced distribution can drive HB-SASE "seeding", resulting in a significantly reduced bandwidth and a better wavelength stability. [ABSTRACT FROM AUTHOR]

The article addresses how to create inductance-free plasma and use it to excite soft x-ray lasers. The method employs a bifilar phenomenon in which one part of the pulsed current flows via the plasma column while the other part runs in the opposite direction via the closely placed external conductor. The electromagnetic fields formed by the plasma and return conductor are adjusted by lowering the distance between them to neutralize the magnetic field of the bifilar. Because the net transient magnetic field is drastically reduced, the plasma-conductor mutual inductance is near zero during current rise and decay. The inductance-free (L ∼ 2 nH) 35 cm-long Z pinches in a 3.1 mm-diameter argon-filled alumina capillary with current rise and decay times of 15 ns, dI/dt > 1012 A/s, and amplitudes up to 17 kA were predicted, realized, and verified to be suitable for pumping soft x-ray Ar+8 lasers. Without the bifilar phenomenon, the 35 cm Z pinches obey a 200 nH inductance that restricts the rise and decay durations of currents to 150 ns. The 35 cm Z pinches with 2 nH inductance generated 46.9 nm laser pulses with up to 4 μJ of energy and a beam divergence of 2 mrad at a low operating voltage of 35–45 kV, compared to 0.1–0.8 MV for similar lasers. The bifilar method could find applications in many research and technological fields, where the rise and decay times of discharge currents play a key role. [ABSTRACT FROM AUTHOR]

We present a magnetic configuration of a compound solar eruption observed on 2012 March 10, from NOAA AR 11429 near the disk center, which displayed a soft X-ray sigmoid before the eruption. We constructed a series of magnetic field models, including double-decker flux rope configurations, using the flux rope insertion method. This produces three-dimensional coronal magnetic field models constrained by the photospheric magnetogram and observed EUV coronal structures. We used different combinations of flux rope paths. We found that two flux ropes sharing the same path at different heights quickly experience a partial merging in the initial iteration of the magnetofrictional relaxation process. Different paths with less than 30% overlap allowed us to construct stable double-decker structures. The high spatial and temporal resolution of the Solar Dynamics Observatory/Atmospheric Imaging Assembly facilitated the selection of a best-fit model that matches the observations best. Moreover, by varying fluxes in this validated nonlinear force-free field double-decker configuration, we successfully reproduce all three scenarios of eruptions of double-decker configurations: (i) eruption due to the instability of higher flux rope; (ii) eruption due to rising lower flux rope and merging with higher flux rope; and (iii) eruption due to the instability of both flux ropes. This demonstrates that magnetofrictional simulation can capture the large-scale magnetic structure of eruptions for a realistic field configuration at eruption onset. [ABSTRACT FROM AUTHOR]

Novel ultrafast x-ray sources based on high harmonic generation and at x-ray free electron lasers are opening up new opportunities to resolve complex ultrafast processes in condensed phase systems with exceptional temporal resolution and atomic site specificity. In this perspective, we present techniques for resolving charge localization, transfer, and separation processes in organic semiconductors and organic photovoltaic devices with time-resolved soft x-ray spectroscopy. We review recent results in ultrafast soft x-ray spectroscopy of these systems and discuss routes to overcome the technical challenges in performing time-resolved x-ray experiments on photosensitive materials with poor thermal conductivity and low pump intensity thresholds for nonlinear effects. [ABSTRACT FROM AUTHOR]

Major solar eruptions can accelerate protons up to relativistic energies. Solar relativistic ions arriving at 1 au may cause a solar particle event detectable by the worldwide network of neutron monitors (NMs), a ground-level enhancement (GLE) event. Using the newly computed NM yield function, we have fitted the 15 historic GLEs. Moments of the fitted proton distributions are used for the analysis. Profiles of the proton net flux are very diverse, while some profiles are similar. For this study, we select two events with similar time profiles, GLE 60 (2001 April 15) and GLE 65 (2003 October 28), and ask what makes these GLEs similar. We compare the GLEs with their progenitor solar flares and coronal mass ejections (CMEs). We find a close relationship between the rise and peak of the GLE, on the one hand, and the solar flare and the metric radio emissions from extended coronal sources at the base of the CME, on the other hand. The GLE decay time, the rate of the proton spectrum evolution, and the CME speed are proportional to the duration of the soft X-ray flare. We compare the two GLEs with GLE 59 (2000 July 14) analyzed by Klein et al. and with the deka-MeV nucleon−1 proton and helium data from the ERNE instrument on the Solar and Heliospheric Observatory spacecraft. The comparison indicates that a single solar eruption can produce more than one component of solar energetic particles, differently contributing at different energies and locations. [ABSTRACT FROM AUTHOR]

The acrylic-based heat-cured soft denture lining material is the most commonly used in relining dentures. This material has poor thermomechanical properties which is a disadvantage. This research aimed to study the effect of the addition of modified metallic nanoparticles on glass transition, modulus of elasticity, and coefficient of thermal expansion and contraction of the acrylic soft liner. Alumina nanoparticles were first modified by a silane coupling agent and then added to a soft denture liner powder in different weight percentages (0, 0.5, 1, and 1.5 wt%) using a probe ultrasonication machine for mixing. 120 samples of acrylic-based soft liner were constructed and divided into four groups G1-G4 (n = 30). Each group was in turn subdivided into 3 subgroups (n = 10) according to the test performed. The mean value, SD, Kruskal-Wallis test, and Dunn's Multiple Comparison tests were used to analyze the results statistically. Incorporating 0.5% by weight alumina nano-fillers into acrylicbased heat-cured soft denture lining material, increased the glass transition temperature significantly (p ≤ 0.01). Additionally, it significantly reduced the coefficient of thermal expansion and contraction, especially at 30 °C, compared to the control group. The E-modulus was also reduced, especially at 50 °C, compared to the control group. According to the reported results, the polymer nanocomposites possess distinctive material properties that distinguish them from unmodified acrylic-base soft denture lining materials. Nanocomposites have more thermal and mechanical stability than unmodified acrylicbase soft denture lining material especially when incorporating 0.5 wt% Al2O3. [ABSTRACT FROM AUTHOR]

We study the possible origin of long-lasting soft X-ray flares on the AD Leo star, which were observed onboard the Extreme Ultraviolet Explorer (EUVE) spacecraft for the period of 1993-2000 [1]. These flares have relatively long rise and decay times of the radiation intensity ( τ ≈ 10 s and τ ≈ 5 · 10, respectively), as well as a relatively large emission measure EM ≈ 10cm, which exceeds by 1-3 orders of magnitude the emission measure of soft X-ray flares on the Sun. Assuming that the radiation appears in magnetic loops and basing on the observed values of the emission measure and radiation decay time, the authors of [1] determined the typical length $$ \overline{l}\approx 1.5\cdot {10}^{10} cm $$ , electron number density $$ \overline{n}\approx 3\cdot {10}^{11}c{m}^{-3} $$ , and plasma temperature $$ \overline{T}\approx 2.5\cdot 107 $$ K of the loops. This paper considers plasma heating due to dissipation of the electric currents in the coronal magnetic loops of the star induced by the photospheric convection. The large inductance of the loop as an equivalent electric circuit determines the long time of the current rise in the source and explains the observed time of plasma heating and the rise time of the X-ray radiation intensity. It is shown that the parameters of the X-ray sources in the AD Leo atmosphere agree with the parameters calculated under the assumption of simultaneous emission of a great number of loops (about 50) with electric currents greater than 10 A, which exceeds the electric currents in the solar coronal magnetic loops by 1-3 orders of magnitude. Such an exceeding can be related to the higher photospheric convection velocities on the late-type stars compared with the Sun. [ABSTRACT FROM AUTHOR]

In this paper, the variation of the pulse duration was investigated for the highly saturated capillary discharge Ne-like Ar 46.9 nm soft X-ray laser. The evolutions of the pulse duration along the axis of capillary were measured for the 3.2- and 4.0-mm-inner-diameter alumina capillaries. Then, the simulations for the evolution of pulse duration were conducted with consideration of the saturation effect of laser amplification, showing good consistency with the experimental results. The analysis was performed on the variation of pulse duration over plasma length, indicating that the variation of the gain-length product caused the evolution of the pulse duration. Meanwhile, the evolutions of pulse durations were measured for different initial Ar pressures for both capillaries, showing the pulse durations were wider near the optimum pressure. Based on the simulations and the experimental results, it is concluded that the variations of the pulse duration of the soft X-ray laser were mainly due to the effect of gain-length product. [ABSTRACT FROM AUTHOR]

An important trend in extreme ultraviolet and soft X-ray free-electron laser (FEL) development in recent years has been the use of seeding by an external laser, aimed to improve the coherence and stability of the generated pulses. The high-gain harmonic generation seeding technique was first implemented at FERMI and provided FEL radiation with high coherence as well as intensity and wavelength stability comparable to table-top ultrafast lasers. At FERMI, the seed laser has another very important function: it is the source of external laser pulses used in pump–probe experiments allowing one to achieve a record-low timing jitter. This paper describes the design, performance and operational modes of the FERMI seed laser in both single- and double-cascade schemes. In addition, the planned upgrade of the system to meet the challenges of the upgrade to echo-enabled harmonic generation mode is presented. [ABSTRACT FROM AUTHOR]

SwissFEL is a compact, high-brilliance, soft and hard X-ray free electron laser (FEL) facility that started user operation in 2019. The facility is composed of two parallel beam lines seeded by a common linear accelerator (LINAC), and a two-bunch photo-injector. For the injector, an innovative dual-photocathode laser scheme has been developed based on state-of-the-art ytterbium femtosecond laser systems. In this paper, we describe the performance of the SwissFEL photocathode drive lasers (PCDLs), the pulse-shaping capabilities as well as the versatility of the systems, which allow many different modes of operation of SwissFEL. The full control over the SwissFEL electron bunch properties via the unique architecture of the PCDLs will enable in the future the advent of more-advanced FEL modes; these modes include, but are not restricted to, the generation of single or trains of sub-femtosecond FEL pulses, multi-color FEL and finally, the generation of fully coherent X-ray pulses via laser-based seeding. [ABSTRACT FROM AUTHOR]

This paper presents a statistical analysis of soft X-ray flares during the period January 1986 to June 2017 covering the last three solar cycles (SCs) 22, 23, and 24. We have analyzed the distribution of flare number, the relationship between the occurrence rate of soft X-ray flares and solar activity, and the duration of different intensity class (B, C, M, and X) solar flares during the period of investigation. The total occurrence rates of M and X class flares are 10.33%, 6.77%, and 5.45% in SCs 22, 23, and 24, respectively, which indicates that SC 22 is an SC with frequent large flares. Meanwhile, the M and X class flares are mainly concentrated in solar maximum (71.13%) in SC 22. The correlation coefficients between the annual number of flares and solar F10.7 index, X-ray flux in 0.1–0.8 nm, and EUV flux in 0.1–50 nm in SC 24 (0.91, 0.88, and 0.96) are greater than that in SCs 23 (0.87, 0.85, and 0.86) and 22 (0.88 and 0.81). The median values of the duration of M and X class flares are 39.00 and 71.50 minutes in SC 22, 21.00 and 26.50 minutes in SC 23, and 19.00 and 24.00 minutes in SC 24. The duration of M and X class flares in SC 22 is obviously longer than that in SCs 23 and 24. In addition, the duration of flares increases with the increase of flare intensity. [ABSTRACT FROM AUTHOR]

Background: Asiaticoside (AS) is extracted from the traditional herbal medicine Centella asiatica, and has angiogenic, antioxidant, anti-inflammatory, and wound-healing effects. We investigated the effects of AS on skin flap survival. Methods: Dorsal McFarlane flaps were harvested from 36 rats and divided into two groups: an experimental group treated with 40 mg/kg AS administered orally once daily, and a control group administered normal saline in an identical manner. On day 2, superoxide dismutase (SOD) and malondialdehyde (MDA) levels, and production of the cytokines tumor necrosis factor-α and interleukin (IL)-6 were evaluated. On day 7, tissue slices were stained with hematoxylin and eosin. The expression of vascular endothelial growth factor (VEGF), IL-6, and IL-1β were immunohistochemically evaluated. Microcirculatory flow was measured using laser Doppler flowmetry. Flap angiography, using the lead oxide-gelatin injection technique, was performed with the aid of a soft X-ray machine. Results: The AS group exhibited greater mean flap survival area, improved microcirculatory flow, and higher expression levels of SOD and VEGF compared with the control group. However, MDA levels and the inflammatory response were significantly reduced. Conclusions: AS exhibits promise as a therapeutic option due to its effects on the viability and function of random skin flaps in rats. [ABSTRACT FROM AUTHOR]

The knowledge of how magnetization looks inside a ferromagnet is often hindered by the limitations of the available experimental methods which are sensitive only to the surface regions or limited in spatial resolution. Here we report a vector tomographic reconstruction based on soft X-ray transmission microscopy and magnetic dichroism data, which has allowed visualizing the three-dimensional magnetization in a ferromagnetic thin film heterostructure. Different non-trivial topological textures have been resolved and the determination of their topological charge has allowed us to identify a Bloch point and a meron-like texture. Our method relies only on experimental data and might be of wide application and interest in 3D nanomagnetism. Although magnetic tomography has been used in the past to determine the 3D magnetization of materials its application to thin films remains challenging. Here the authors reconstruct the magnetization of a thin film, enabling the measurement of topological charges of magnetic singularities. [ABSTRACT FROM AUTHOR]

The paper presents the results of processing of data on the soft X-ray solar radiation obtained by the PINGVIN-M instrument aboard the KORONAS-FOTON spacecraft in July 2009. The high sensitivity of the device, combined with effective compensation for the magnetospheric background over most of the orbit, made it possible to study in detail the evolution of X-ray radiation from the active region and its X-ray bursts—from microflares to class-C bursts. The analyzed data refer to the period of deep minimum solar activity, during which there was only one active region emitting in the soft X-ray range on the solar disk. This made it possible to study the characteristics of soft X-ray radiation in this region without additional background with a device that records radiation from the entire solar disk, which significantly increases the reliability of the estimates of the parameters of the time and energy spectra of X-ray radiation derived from experimental data. [ABSTRACT FROM AUTHOR]

The Dual-zone Aperture X-ray Solar Spectrometer (DAXSS) was flown on 2018 June 18 on the NASA 36.336 sounding rocket flight and obtained the highest resolution to date for solar soft X-ray (SXR) spectra over a broad energy range. This observation was during a time with quiescent (nonflaring) small active regions on the solar disk and when the 10.7 cm radio flux (F10.7) was 75 solar flux units (1 sfu = 10–22 W m−2 Hz−1). The DAXSS instrument consists of a LASP-developed dual-zone aperture and a commercial X-ray spectrometer from Amptek that measures solar full-disk irradiance from 0.5 to 20 keV with a resolving power of 20 near 1 keV. This paper discusses the novel design of the spectrometer and the instrument characterization techniques. Additionally, the solar measurements obtained from the 2018 sounding rocket flight are analyzed using CHIANTI spectral models to fit the temperatures, emission measures, and relative elemental abundances of the solar corona plasma. The abundance of iron was found to be 35% higher than expected in the quiescent Sun's corona suggesting either that our spectral models require additional sophistication or that the underlying atomic database may require updates. Future long-term systematic observations of this spectral range are needed to provide further insight into the sources of coronal heating through modeling the changes of relative elemental abundances during developments of active regions and solar flaring events. [ABSTRACT FROM AUTHOR]