X-ray Research Articles

Temporal and spatial resolution of magnetosome degradation at the subcellular level in a 3D lung carcinoma model.

Magnetic nanoparticles offer many exciting possibilities in biomedicine, from cell imaging to cancer treatment. One of the currently researched nanoparticles are magnetosomes, magnetite nanoparticles of high chemical purity synthesized by magnetotactic bacteria. Despite their therapeutic potential, very little is known about their degradation in human cells, and even less so of their degradation within tumours. In an effort to explore the potential of magnetosomes for cancer treatment, we have explored their degradation process in a 3D human lung carcinoma model at the subcellular level and with nanometre scale resolution. We have used state of the art hard X-ray probes (nano-XANES and nano-XRF), which allow for identification of distinct iron phases in each region of the cell. Our results reveal the progression of magnetite oxidation to maghemite within magnetosomes, and the biosynthesis of magnetite and ferrihydrite by ferritin.

Rational Design of A-Site Cation for High Performance Lead-Free Perovskite X-Ray Detectors.

Design of hypotoxic lead-free perovskites, e.g. Bismuth(Bi)-based perovskites, is much beneficial for commercialization of perovskite X-ray detectors due to their strong radiation absorption. Nevertheless, the design principles governing the selection of A-site cations for achieving high-performance X-ray detectors remain elusive. Here, seven molecules (methylamine MA, amine NH3, dimethylbiguanide DGA, phenylethylamine PEA, 4-fluorophenethylamine p-FPEA, 1,3-propanediamine PDA, and 1,4-butanediamine BDA) and calculated their dipole moments and interaction strength with metal halide (BiI3) are selected. The first-principles calculations and related spectroscopy measurements confirm that organic molecules (DGA) with large dipole moments can have strong interactions with perovskite octahedron and improve the carrier transport between the organic and inorganic clusters. Consequently, zero-dimensional single crystal (SC) (DGA)BiI5∙H2O is synthesized. The (DGA)BiI5∙H2O SCs demonstrate an exceptional carrier mobility-lifetime product of 6.55×10-3cm2V-1, resulting in the high sensitivity of 5879.4µCGyair -1cm-2, featuring a low detection limit (4.7nGyairs-1) and remarkable X-ray irradiation stability even after 100 days of aging at a high electric field (100Vmm-1). Furthermore, the (DGA)BiI5∙H2O SCs for imaging, achieving a notable spatial resolution of 5.5lpmm-1 are applied. This investigation establishes a pathway for systematically screening A-site cations to design low-dimensional SCs for high-performance X-ray detection.

Targeting proliferating cell nuclear antigen enhances ionizing radiation-induced cytotoxicity in prostate cancer cells.

Proliferating cell nuclear antigen (PCNA) is essential for DNA replication and repair, cell growth, and survival. PCNA also enhances androgen receptor (AR) signaling in prostate cancer (PC) cells. We identified a PCNA interaction protein (PIP) box at the N-terminal domain of AR and developed a small peptide PCNA inhibitor R9-AR-PIP containing AR PIP-box. We also identified a series of small molecule PCNA inhibitors (PCNA-Is) that bind directly to PCNA and interrupt PCNA functions. The present study investigated the effects of the PCNA inhibitors on the sensitivity of PC cells to X-ray radiation. The effects of targeting PCNA on radio sensitivity of PC cells were investigated in four lines of castration-resistant PC (CRPC) cells with different AR expression statuses. The cells were treated with the PCNA inhibitors and X-ray radiation alone or in combination. The effects of the treatment on expression of AR target genes, DNA damage response, DNA damage, homologous recombination repair (HRR), and cytotoxicity were evaluated. We found that the androgen response element (ARE) occupancy of the DNA damage response gene PARP1 by AR is significantly attenuated by PCNA-I1S or R9-AR-PIP combined with X-ray radiation, while X-ray radiation alone does not enhance the ARE occupancy. PCNA-I1S or R9-AR-PIP alone significantly inhibits occupancy of the AR-occupied regions (AROR) in PRKDC and XRCC2 genes. R9-AR-PIP and PCNA-I1S inhibit expression of AR-Vs target gene cyclin A2 and show the additive effects with radiation in AR-positive CRPC cells. Targeting PCNA by PCNA-I1S and R9-AR-PIP downregulates expression of DNA damage response genes EXO1, Rad54L, Rad51, and/or PARP1 and shows the additive effects with radiation as compared with their respective controls in AR-positive CRPC LNCaP-AI, 22Rv1, and R1-D567 cells, but not in AR-negative PC-3 cells. R9-AR-PIP and PCNA-I1S elevate the levels of phospho-DNA-PKcs(S2056) and γH2AX, indicating DNA damage in response to radiation in AR-positive cells. The HRR is significantly attenuated by PCNA inhibitors PCNA-I1S, R9-AR-PIP, and T2AA in all four CRPC cells examined, and inhibited by Enzalutamide (Enz) only in 22RV1 cells. The cytotoxicity induced by X-ray radiation in androgen-dependent LNCaP cells is enhanced by Enz and a lower concentration of R9-AR-PIP in the colony formation assay. R9-AR-PIP at higher concentration reduces the colony formation and has an additive effect with X-ray radiation in all AR expressing cells, regardless of AR-FL and AR-Vs, but does not significantly alter the colony formation in AR-negative PC-3 cells. PCNA-I1S attenuates colony formation and has an additive effect with ionizing radiation in all four CRPC cells, regardless of AR expression status. These data provide a strong rationale for the therapy studies using PCNA-I1S or R9-AR-PIP in combination with X-ray radiation against CRPC tumors in preclinical models.

The Solar Aspect System of the Hard X-ray Imager Onboard ASO-S

The Solar Aspect System of the Hard X-ray Imager Onboard ASO-S

In-situ Investigation of Damage Evolution and Mechanism in Composite Propellants under Monochromatic X-ray Irradiation

In-situ Investigation of Damage Evolution and Mechanism in Composite Propellants under Monochromatic X-ray Irradiation

High Bioavailability of Spinach Folate Evaluated by Functional Biomarkers in a Folate Depletion-Repletion Mouse Model.

The bioavailability of natural folates is 50% lower than that of synthetic folic acid (FA); however, it remains unclear whether this value is universally applicable to all foods. Therefore, the present study investigated the bioavailability of folate from spinach using multiple biomarkers in a folate depletion-repletion mouse model. Mice were fed a folate-deficient diet for 4 wk and subsequently divided into three groups: folate-deficient, FA, and spinach folate. The folate repletion group received either FA or spinach folate at 2 mg/kg diet for 9 d. On the 7th day of repletion, half of each group underwent low-dose total body X-ray irradiation to induce chromosomal damage in bone marrow. Folate bioavailability biomarkers included measurements of folate levels in plasma, liver, and bone marrow along with an analysis of plasma homocysteine levels and chromosome damage, both of which are functional biomarkers of body folate. The consumption of a folate-deficient diet led to decreased tissue folate levels, increased plasma homocysteine levels, and chromosomal damage. Repletion with spinach folate restored folate levels in plasma, liver, and bone marrow to 69, 13, and 68%, respectively, of FA levels. Additionally, spinach folate repletion reduced plasma homocysteine levels and chromosome damage to 83% and 93-117%, respectively, of FA levels. Collectively, the present results demonstrated that the bioavailability of spinach folate exceeded 83% of FA, particularly when assessed using functional biomarkers.

The induction of drug uptake transporter OATP1A2 by radiation is mediated by non-receptor tyrosine kinase YES-1.

Organic anion transporting polypeptides (OATP, gene symbol SLCO) are well-recognized key determinants for the absorption, distribution, and excretion of a wide spectrum of endogenous and exogenous compounds including many antineoplastic agents. It was therefore proposed as a potential drug target for cancer therapy. In our previous study, it was found that low-dose X-ray and carbon ion irradiation both up-regulated the expression of OATP family member OATP1A2 and in turn, led to a more dramatic killing effect when cancer cells were co-treated with antitumor drugs such as methotrexate. In the present study, the underlying mechanism of the phenomenon was explored in breast cancer cell line MCF-7. It was found that the non-receptor tyrosine kinase YES-1 was temporally coordinated with the change of OATP1A2 after irradiation. The over-expression of YES-1 significantly increased OATP1A2 both at the mRNA and protein level. The signal transducer and activator of transcription 3 (STAT3) pathway is likely the downstream target of YES-1 since phosphorylation and nuclear accumulation of STAT3 were both enhanced after over-expressing YES-1 in MCF-7 cells. Further investigation revealed that there are two possible binding sites of STAT3 localized at the upstream sequence of SLCO1A2, the encoding gene of OATP1A2. Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) analysis suggested that these two sites bound to STAT3 specifically and the over-expression of YES-1 significantly increased the association of the transcription factor with the putative binding sites. Finally, inhibition or knock-down of YES-1 attenuated the induction effect of radiation on the expression of OATP1A2. Significance Statement The current study found that the effect of X-rays on YES-1 and OATP1A2 is temporally coordinated. YES-1 phosphorylates and increases the nuclear accumulation of STAT3, which in turn binds to the upstream regulatory sequences of SLCO1A2, the coding gene for OATP1A2. Hence, inhibitors of YES-1 may suppress the radiation induction effect on OATP1A2.

Soft X-ray emission from the classical nova AT 2018bej

Soft X-ray emission from the classical nova AT 2018bej

The Effect of X-ray Radiation on Malondialdehyde Levels in Radiology Workers in Selected Hospitals in Indonesia

The Effect of X-ray Radiation on Malondialdehyde Levels in Radiology Workers in Selected Hospitals in Indonesia

Irradiation-driven mass transfer for massive companion stars in supersoft X-rays sources

Supersoft X-ray sources (SSSs) have been proposed as one of the progenitors for Type Ia supernovae. However, the exact origin of the quasi-periodic variability in the optical light curve remains a mystery. In this work, our goal is to investigate the effect of the feedback of an evolved main-sequence companion star on X-ray irradiation and find whether periodic X-ray irradiation of the companion star could reproduce periodic mass transfer. Using the Modules for Experiments in Stellar Astrophysics (MESA) code, we modeled the evolutionary track of the companion star under the influence of supersoft X-ray irradiation, and we calculated the resulting mass transfer rate. We find that the supersoft X-ray heating of the companion star can result in the expansion of the companion, causing it to greatly overflow its Roche lobe and thereby increasing the mass transfer rate. The periodic X-ray irradiation on the companion stars leads to periodic changes in the mass transfer rate. For a given companion star, higher irradiation efficiencies result in a higher mass transfer rate. Additionally, the mass transfer rate increases as the mass of the companion star decreases for a given irradiation efficiency. The companion star undergoing thermal timescale mass transfer is periodically irradiated by the X-rays from the WD, which can lead to periodic enhancement of the mass transfer rate. The mechanism could be the origin of the quasi-periodic optical light curve in supersoft X-ray sources.

Unveiling Mass Transfer in Solar Flares: Insights from Elemental Abundance Evolutions Observed by Chang’E-2 Solar X-Ray Monitor

Understanding how elemental abundances evolve during solar flares helps shed light on the mass and energy transfer between different solar atmospheric layers. However, prior studies have mostly concentrated on averaged abundances or specific flare phases, leaving a gap in exploring the comprehensive observations throughout the entire flare process. Consequently, investigations into this area are relatively scarce. Exploiting the Solar X-Ray Monitor data obtained from the Chang’E-2 lunar orbiter, we present two comprehensive soft X-ray spectroscopic observations of flares in active regions, AR 11149 and 11158, demonstrating elemental abundance evolutions under different conditions. Our findings unveil the inverse first ionization potential (IFIP) effect during flares for Fe for the first time, and reaffirm its existence for Si. Additionally, we observed a rare depletion of elemental abundances, marking the second IFIP effect in flare decay phases. Our study offers a CSHKP model-based interpretation to elucidate the formation of both the FIP and IFIP effects in flare dynamics, with the inertia effect being incorporated into the ponderomotive force fractionation model.

Structure and luminescence properties of EuF3 and SrF2:Eu nanoparticles after microwave plasma annealing in "methane-hydrogen".

Recently, progress has been made in fabricating diamond-based scintillators with integrated rare-earth luminescent particles. These luminescent particles are integrated into the bulk of diamond during their synthesis by chemical vapor deposition (CVD). However, the growth conditions include a chemically aggressive plasma environment and elevated temperatures, which results in the partial degradation of particles and a decrease in the intensity of their luminescence. Here, we investigate the effect of thermal annealing of luminescent EuF3 and SrF2:Eu powders in microwave plasma that simulates the growth conditions of polycrystalline diamond. It was found that silicon substrates act as efficient reducing agents that lead to the partial reduction of trivalent europium to divalent europium. When annealing occurs on a diamond substrate, the reduction processes proceed at a significantly slower rate. The observed luminescence spectra showed both Eu2+ and Eu3+ luminescence bands, which allows for a targeted tuning of the luminescence spectrum of europium in composites and can be used to fabricate detectors and visualizers of X-ray radiation using a visible signal from the desired combination of Eu2±/Eu3± ions. During plasma annealing in pure hydrogen at moderate temperatures (600 °C), an intensive hydrogenation of particles is observed. Such hydrogen plasma treatment of fluorides may be considered a promising route to fabricate hydrides of various metals.

Accretion Properties of Soft X-Ray Transient XTE J1856+053 during Its 2023 Outburst

Soft X-ray transients (SXTs) are a subclass of the low-mass X-ray binaries that occasionally show a sudden rise in their soft X-ray luminosity; otherwise, they remain in an extremely faint state. We investigate the accretion properties of the SXT XTE J1856+053 during its 2023 outburst obtained by NICER and NuSTAR data in July. We present detailed results on the timing and spectral analysis of the X-ray emission during the outburst. The power spectral density shows no quasi-periodic oscillation features. The source’s spectrum on July 19 can be well fitted with a multicolor blackbody component, a power-law component, and a reflection component with a broadened iron emission line. NICER spectra can be well fitted by considering a combination of a blackbody and a power law. The source exhibits a transition within just 5 days from a soft state to an intermediate state during the outburst decline phase. The inner accretion disk has a low inclination angle (∼18°). The spectral analysis also suggests a high-spin (a > 0.9) black hole as the central accreting object.

Indirect detector for ultra-high-speed X-ray micro-imaging with increased sensitivity to near-ultraviolet scintillator emission.

Ultra-high-speed synchrotron-based hard X-ray (i.e. above 10 keV) imaging is gaining a growing interest in a number of scientific domains for tracking non-repeatable dynamic phenomena at spatio-temporal microscales. This work describes an optimized indirect X-ray imaging microscope designed to achieve high performance at micrometre pixel size and megahertz acquisition speed. The entire detector optical arrangement has an improved sensitivity within the near-ultraviolet (NUV) part of the emitted spectrum (i.e. 310-430 nm wavelength). When combined with a single-crystal fast-decay scintillator, such as LYSO:Ce (Lu2-xYxSiO5:Ce), it exploits the potential of the NUV light-emitting scintillators. The indirect arrangement of the detector makes it suitable for high-dose applications that require high-energy illumination. This allows for synchrotron single-bunch hard X-ray imaging to be performed with improved true spatial resolution, as herein exemplified through pulsed wire explosion and superheated near-nozzle gasoline injection experiments at a pixel size of 3.2 µm, acquisition rates up to 1.4 MHz and effective exposure time down to 60 ps.

High-efficiency hard x-ray blazed diffraction via refraction by nanometer-scale prism arrays

High-efficiency hard x-ray blazed diffraction via refraction by nanometer-scale prism arrays

X-Ray Variability in the Symbiotic Binary RT Cru: Principal Component Analysis

Hard X-ray-emitting (δ-type) symbiotic binaries, which exhibit a strong hard X-ray excess, have posed a challenge to our understanding of accretion physics in degenerate dwarfs. RT Cru, which is a member of the δ-type symbiotics, shows stochastic X-ray variability. Timing analyses of X-ray observations from XMM-Newton and NuSTAR, which we consider here, indicate hourly fluctuations, in addition to a spectral transition from 2007 to a harder state in 2012 seen with Suzaku observations. To trace the nature of X-ray variability, we analyze the multimission X-ray data using principal component analysis (PCA), which determines the spectral components that contribute most to the flickering behavior and the hardness transition. The Chandra HRC-S/LETG and XMM-Newton EPIC-pn data provide the primary PCA components, which may contain some variable emission features, especially in the soft excess. Additionally, the absorbing column (first order with 50%), along with the source continuum (20%), and a third component (9%)—which likely accounts for thermal emission in the soft band—are the three principal components found in the Suzaku XIS1 observations. The PCA components of the NuSTAR data also correspond to the continuum and possibly emission features. Our findings suggest that the spectral hardness transition between the two Suzaku observations is mainly due to changes in the absorbing material and X-ray continuum, while some changes in the thermal plasma emission may result in flickering-type variations.

Exploring the Complex Ionization Environment of the Turbulent DM Tau Disk

Ionization drives important chemical and dynamical processes within protoplanetary disks, including the formation of organics and water in the cold midplane and the transportation of material via accretion and magnetohydrodynamic flows. Understanding these ionization-driven processes is crucial for understanding disk evolution and planet formation. We use new and archival Atacama Large Millimeter/submillimeter Array observations of HCO+, H13CO+, and N2H+ to produce the first forward-modeled 2D ionization constraints for the DM Tau protoplanetary disk. We include ionization from multiple sources and explore the disk chemistry under a range of ionizing conditions. Abundances from our 2D chemical models are postprocessed using non-LTE radiative transfer, visibility sampling, and imaging, and are compared directly to the observed radial emission profiles. The observations are best fit by a modestly reduced cosmic-ray ionization rate (ζ CR ∼10−18 s−1) and a hard X-ray spectrum (hardness ratio = 0.3), which we associate with stellar flaring conditions. Our best-fit model underproduces emission in the inner disk, suggesting that there may be an additional mechanism enhancing ionization in DM Tau’s inner disk. Overall, our findings highlight the complexity of ionization in protoplanetary disks and the need for high-resolution multiline studies.

Overview and current challenges at the Calibration Laboratory of the Paul Scherrer Institute

The Calibration Laboratory of the Paul Scherrer Institute (PSI) is a secondary calibration laboratory accredited by the Swiss Accreditation Service (SAS) in accordance with ISO 17025. It also acts as a verification body authorized by the Swiss Federal Institute of Metrology (METAS). The Laboratory is equipped with X-ray, gamma and neutron irradiation facilities, providing characterized reference radiation fields for gamma 137Cs, 60Co, narrow spectrum X-rays from N-15 to N-300 and neutron radionuclide sources 252Cf, 252Cf (D2O-moderated) and 241Am-Be. The laboratory performs routine calibrations, organizes intercomparison measurements for individual monitoring services in Switzerland, and participates in various research projects, e.g., by performing irradiations in reference fields. For this reason, the proper characterization of reference radiation fields is of utmost importance for ensuring high quality irradiations and calibrations of personal dosemeters and radiation protection instruments. In this contribution, we provide an overview of the irradiation facilities at the Calibration Laboratory at PSI and discuss the challenges of characterizing reference radiation fields. In particular, we will discuss the factors affecting the determination of the distance between the source and irradiated dosemeters and detectors, as well as issues related to 252Cf decay and contribution of 250Cf. We will also demonstrate the use of Monte-Carlo simulations in determining the optimal position of the source and irradiation facility within the irradiation room.

Unraveling the Origins of an Extreme Solar Eruptive Event with Hard X-Ray Imaging Spectroscopy

Hard X-ray (HXR) observations are crucial for understanding the initiation and evolution of solar eruptive events, as they provide a key signature of flare-accelerated electrons and heated plasma. The potential of high-cadence HXR imaging for deciphering the erupting structure, however, has not received adequate attention in an era of extreme ultraviolet (EUV) imaging abundance. An extreme solar eruptive event on 2022 September 5 observed on the solar far side by both Parker Solar Probe and Solar Orbiter provides the opportunity to showcase the power of HXR imaging in the absence of high-cadence EUV imaging. We investigate the evolution of flare energy release through HXR timing, imaging, and spectral analyses using data from the Spectrometer/Telescope for Imaging X-rays (STIX) on board Solar Orbiter. STIX provides the highest cadence imaging of the energy release sites for this far-side event and offers crucial insight into the nature of energy release, timing of flare particle acceleration, and evolution of the acceleration efficiency. We find that this is a two-phase eruptive event, rather than two distinct eruptions, as has been previously suggested. The eruption begins with an initial peak in flare emission on one side of the active region (AR), marking the rise/destabilization of a loop system followed by notable episodes of energy release across the AR and an eruptive phase associated with a very fast coronal mass ejection, type III radio bursts, and solar energetic particles. We demonstrate that high-cadence HXR imaging spectroscopy is indispensable for understanding the formation of powerful, space-weather relevant eruptions.

Connexin 43 regulates pyroptosis by influencing intracellular calcium levels in X-ray induced vascular endothelial cell damage.

Our prior research has established that X-ray exposure induces pyroptosis in human umbilical vein endothelial cells (HUVECs), with Cx43 playing a regulatory role in this process. However, the precise mechanism by which Cx43 regulates pyroptosis remains unclear. The objective of this study is to assess the involvement of the calcium signaling pathway in Cx43-mediated regulation of X-ray-induced pyroptosis in HUVECs. HUVECs were exposed to 10 Gy X-ray radiation either alone or combined with Cx43 overexpression or knockdown. Calcium ions (Ca2+) were stained using Fluo-4/AM and analyzed via flow cytometry and confocal microscopy. Pyroptosis was assessed through flow cytometry by staining with FLICA (fluorescent-labeled inhibitor of caspase) and propidium iodide (PI). Calcium signaling was inhibited using BAPTA/AM, 2-APB, or nifedipine. Protein expression levels were assessed by western blotting. X-ray irradiation induced an increase in intracellular calcium levels in HUVECs in a dose- and time-dependent manner. The results demonstrated that regulating calcium release with BAPTA/AM, 2-APB, or nifedipine significantly reduced pyroptosis. Also, the overexpression of Cx43 significantly attenuated the increase in intracellular calcium. Conversely, Cx43 knockdown via siRNA significantly increased the intracellular calcium levels. Also, interfering with calcium signaling using BAPTA/AM, 2-APB, or nifedipine reduced the raised pyroptosis levels induced by Cx43 knockdown. Individual HUVECs exposed to high-dose X-ray irradiation exhibited an increase in intracellular calcium, leading to pyroptosis. Also, upregulating Cx43 expression reduced the pyroptosis levels by inhibiting intracellular calcium concentration. This study introduces new concepts for identifying targets for the prophylaxis and therapy of radiation-induced damage.