We report the studies of structure and properties of a quasi-one-dimensional (quasi-1D) compound BaTiS3BaTiS3 under pressure. The poly-crystalline samples are synthesized by solid-state reaction method and single-crystalline samples are produced by chemical vapor transport method. The XRD measurement under ambient pressure confirms the hexagonal structure, which consists of face-sharing octahedral TiS6TiS6 chains along c-axis and displays a quasi-1D feature. When applying pressure, the synchrotron X-ray diffraction experiments show that the sample undergoes a phase transition from hexagonal phase to orthorhombic phase at around 10 GPa due to the zig-zag deformation of TiS6TiS6 chains, while the quasi-1D structure is reserved. At ambient pressure, BaTiS3BaTiS3 exhibits an insulating behavior with a band gap about 0.273 eV. When applying pressure, the sample undergoes a crossover from insulator to metal due to the enhancement of inter-chain electron hopping.

Niobium polyhydride was synthesized at high pressure and high temperature conditions by using diamond anvil cell combined with in situ high pressure laser heating techniques. High pressure electric transport experiments demonstrate that superconducting transition occurs with critical temperature (T-c) 42 K at 187 GPa. The shift of T-c as function of external applied magnetic field is in consistent to the nature of superconductivity while the upper critical field at zero temperature mu H-0(c2)(0) is estimated to similar to 16.8 T while the GL coherent length similar to 57 angstrom is estimated. The structure investigation using synchrotron radiation implies that the observed superconductivity may come from Fm-3m phase of NbH3.

The Low Energy X-ray Telescope (LE) is an important instrument of the Insight -Hard X-ray Modulation Telescope (Insight-HXMT), which performs scanning and point observation in the soft X-ray energy band (0.7-13 keV). Since its launch in 2017, it has conducted a large number of scientific observations and achieved significant astronomical discoveries. LE is composed of three detector boxes and an electronic control box. The data acquisition system of LE is designed to use periodic sampling, which solves the problem of unstable noise peaks. Data loss may occur when observing X-ray bursts, and periodic sampling provides a method of correcting light curves. In addition, in the South Atlantic Anomaly (SAA) or where the count rate of the particle monitor on the Insight-HXMT is very high, LE automatically switches into SAA operating mode, and only a small number of events are recorded. After data correction, the light curves can be estimated to expand the astronomical achievements of LE.

The grazing-incidence optics with Wolter-I type geometry is commonly used in X-ray astronomy. The manufacturing technologies are still under development for future space missions to fulfill the stringent performance requirements with reduced weight and cost, e.g. the planned enhanced X-ray Timing and Polarimetry Mission. To improve the manufacturing process, it is necessary to study the relationship between metrological characterization and angular resolution via ray-optics or wave-optics models. The model calculations produce inconsistent results depending on the characteristics of wide-band surface errors, which require validation before their application in the Wolter-I type optics. In this work, two samples of the single-reflection mirrors with an elliptical shape are produced to validate the models. The first sample uses the Aluminum alloy substrate and the second sample uses the Aluminum alloy coated with Nickel-Phosphorous as the substrate. Tungsten is coated on both substrates to increase the X-ray reflectivity. The metrological characterization is inspected using the Fizeau interferometer and 3D optical profiler. The X-ray calibration of the mirror is performed in the 100-m X-ray Test Facility of Institute of High Energy Physics using the Color X-ray Camera. Both ray-optics and wave-optics models are validated in a wide scope of applications from smooth to relatively rough surfaces. The proper treatments of the metrological data are required as input to the model calculations: the post-fit distribution of figure errors, the micro-roughness defined in a specific frequency band, and the smoothed power spectral density of the surface errors. The validated models can be further applied in Wolter-I optics to predict mirror performances or to provide precision processing requirements.

We report experimental discovery of tantalum polyhydride superconductor. It was synthesized under high-pressure and high-temperature conditions using diamond anvil cell combined with in situ high-pressure laser heating techniques. The superconductivity was investigated via resistance measurements at pressures. The highest superconducting transition temperature T c was found to be ∼ 30 K at 197 GPa in the sample that was synthesized at the same pressure with ∼ 2000 K heating. The transitions are shifted to low temperature upon applying magnetic fields that support the superconductivity nature. The upper critical field at zero temperature μ 0 H c2(0) of the superconducting phase is estimated to be ∼ 20 T that corresponds to Ginzburg–Landau coherent length ∼ 40 Å. Our results suggest that the superconductivity may arise from I 4 ¯ 3 d phase of TaH3. It is, for the first time to our best knowledge, experimental realization of superconducting hydrides for the VB group of transition metals.

Studies on polyhydrides are attracting growing attentions recently due to their potential high temperature superconductivity (SC). We here report the discovery of SC in hafnium polyhydrides at high pressures. The hafnium superhydrides are synthesized at high pressure and high temperature conditions using diamond anvil cell in combination with in-situ high pressure laser heating technique. The SC was investigated by in-situ high pressure resistance measurements in applied magnetic fields. A superconducting transition with onset Tc ~83 K was observed at 243 GPa. The upper critical field Hc2(0) was estimated to be 24 Tesla by GL theory and the consequent superconducting coherent length to be ~37 angstrom. Our results suggest that the superconducting phase is from C2/m-HfH14. This is the first 5d transition metal polyhydride superconductor with Tc above the liquid nitrogen temperature.

The observed diversity in Type Ia supernovae (SNe Ia) – the thermonuclear explosions of carbon-oxygen white dwarf stars used as cosmological standard candles – is currently met with a variety of explosion models and progenitor scenarios. To help improve our understanding of whether and how often different models contribute to the occurrence of SNe Ia and their assorted properties, we present a comprehensive analysis of seven nearby SNe Ia. We obtained one to two epochs of optical spectra with Gemini Observatory during the nebular phase (>200 days past peak) for each of these events, all of which had time-series of photometry and spectroscopy at early times (the first ∼8 weeks after explosion). We use the combination of early- and late-time observations to assess the predictions of various models for the explosion (e.g., double-detonation, off-center detonation, stellar collisions), progenitor star (e.g., ejecta mass, metallicity), and binary companion (e.g., another white dwarf or a non-degenerate star). Overall, we find general consistency in our observations with spherically-symmetric models for SN Ia explosions, and with scenarios in which the binary companion is another degenerate star. We also present an in-depth analysis of SN 2017fzw, a member of the sub-group of SNe Ia which appear to be transitional between the subluminous "91bg-like" events and normal SNe Ia, and for which nebular-phase spectra are rare.

Objective:The investigation and research on the application status of Hepatic Venous Pressure Gradient (HVPG) is very important to understand the real situation and future development of this technology in China.Methods:This study comprehensively investigated the basic situation of HVPG technology in China, including hospital distribution, hospital level, annual number of cases, catheters used, average cost, indications and existing problems.Results:According to the survey, there were 70 hospitals in China carrying out HVPG technology in 2021, distributed in 28 provinces (autonomous regions and municipalities directly under the central Government). A total of 4 398 cases of HVPG were performed in all the surveyed hospitals in 2021, of which 2 291 cases (52.1%) were tested by HVPG alone. The average cost of HVPG detection was (5 617.2±2 079.4) yuan. 96.3% of the teams completed HVPG detection with balloon method, and most of the teams used thrombectomy balloon catheter (80.3%).Conclusion:Through this investigation, the status of domestic clinical application of HVPG has been clarified, and it has been confirmed that many domestic medical institutions have mastered this technology, but it still needs to continue to promote and popularize HVPG technology in the future.

ABSTRACT We studied the 2018 outburst of the black hole transient H 1743 − 322 with a series of Insight-HXMT, NICER, and NuSTAR observations, covering the 1–120 keV band. With our broad-band X-ray spectral modelling, we confirm that the source remained in the low/hard state throughout the month-long outburst, although it became marginally softer at peak flux. We detected Type-C quasi-periodic oscillations (QPOs) and followed the evolution of their properties. The QPO frequency increased from ∼0.1 to ∼0.4 Hz during the rising phase of the outburst and decreased again in the decline. Continuum X-ray flux, power-law photon index, QPO frequency, and QPO root-mean-square amplitude were positively correlated. The QPO amplitude was slightly higher in the soft X-ray band (typical values of 12–16 per cent, compared with 8–10 per cent in the hard band). Our spectral-timing results shed light on the initial rising phase in the low/hard state, which has rarely been monitored with such high cadence, time resolution, and broad-band coverage. Combining spectral and timing properties, we find that ‘failed’ (hard state only) and ‘successful’ outbursts follow the same initial evolutionary track, although the former class of outburst never reaches the threshold for a transition to softer (thermally dominated) accretion regimes.

We present a spectral study of the black hole candidate MAXI J1348−630 during its 2019 outburst, based on monitoring observations with Insight-HXMT and Swift. Throughout the outburst, the spectra are well fitted with power-law plus disk-blackbody components. In the soft-intermediate and soft states, we observed the canonical relation L∝Tin4 between disk luminosity L and peak color temperature T in, with a constant inner radius R in (traditionally identified with the innermost stable circular orbit). At other stages of the outburst cycle, the behavior is more unusual, inconsistent with the canonical outburst evolution of black hole transients. In particular, during the hard rise, the apparent inner radius is smaller than in the soft state (and increasing), and the peak color temperature is higher (and decreasing). This anomalous behavior is found even when we model the spectra with self-consistent Comptonization models, which take into account the upscattering of photons from the disk component into the power-law component. To explain both anomalous trends at the same time, we suggest that the hardening factor for the inner-disk emission was larger than the canonical value of ≈1.7 at the beginning of the outburst. A more physical trend of radii and temperature evolution requires a hardening factor evolving from ≈3.5 at the beginning of the hard state to ≈1.7 in the hard-intermediate state. This could be evidence that the inner disk was in the process of condensing from the hot, optically thin medium and had not yet reached a sufficiently high optical depth for its emission spectrum to be described by the standard optically thick disk solution.

The Spectroscopy Focusing Array (SFA) onboard the enhanced X-ray Timing and Polarimetry observatory (eXTP) uses Silicon Drift Detectors (SDDs) at the focal plane. A simulation of the corresponding detectors is performed in this work to model the instrument responses, including the spectral and timing behaviors. It relies on the solution of the Poisson equations and the charge carrier dynamics to predict the detector performances at different X-ray incident positions. The notable features of the instrument responses are reproduced with reasonable accuracy. The simulation can be used for a variety of studies in the space mission, such as the understanding of the calibration data during on-ground tests and the verification of the scientific requirements with a certain instrument configuration. As an example, the flux limits of scientific observations are estimated in this work taking into account the pile-up and dead-time effects.

Multiwavelength variability studies of active galactic nuclei can be used to probe their inner regions that are not directly resolvable. Dust reverberation mapping (DRM) estimates the size of the dust emitting region by measuring the delays between the infrared (IR) response to variability in the optical light curves. We measure DRM lags of Zw229-015 between optical ground-based and Kepler light curves and concurrent IR Spitzer 3.6 and 4.5 mu m light curves from 2010 to 2015, finding an overall mean rest-frame lag of 18.3 +/- 4.5 d. Each combination of optical and IR light curve returns lags that are consistent with each other within la, which implies that the different wavelengths are dominated by the same hot dust emission. The lags measured for Zw229-015 are found to be consistently smaller than predictions using the lag-luminosity relationship. Also, the overall IR response to the optical emission actually depends on the geometry and structure of the dust emitting region as well, so we use Markov chain Monte Carlo modelling to simulate the dust distribution to further estimate these structural and geometrical properties. We find that a large increase in flux between the 2011-2012 observation seasons, which is more dramatic in the IR light curve, is not well simulated by a single dust component. When excluding this increase in flux, the modelling consistently suggests that the dust is distributed in an extended flat disc, and finds a mean inclination angle of 49(-13)(+3) deg.

Objective: To investigate the impact of a reduced portacaval shunt on hepatic myelopathy (HM) in patients with cirrhosis after a transjugular intrahepatic portosystemic shunt (TIPS). Methods: Patients who developed HM after receiving TIPS at the First Affiliated Hospital of Xi'an Jiaotong University from January 2013 to June 2018 were retrospectively analyzed. HM severity was quantified by clinical spasticity index (CSI) and Fugl-Meyer Assessment (FMA) of the lower extremity. Clinical manifestations were combined with grades Ⅰ-Ⅳ. HM patients were divided into drug treatment (group A) and flow restriction group (group B) according to different treatment methods. The changes in CSI and FMA of the lower extremity after treatment were statistically analyzed in the two groups. P<0.05 was considered a statistically significant difference. Results: A total of 421 cases of cirrhosis who underwent TIPS were enrolled. Among them, 30 developed HM, with 22 in group A and 8 in group B. The incidence of HM after TIPS surgery was about 7.13%. After treatment, CSI was gradually increased and FMA of lower extremity was gradually decreased in group A, while vice-versa in group B. CSI in the two groups were differed significantly at 6, 12, 18, and 24 months after treatment (P<0.05), while the difference in FMA of the lower extremity was statistically significant at 12, 18, and 24 months after treatment (P<0.05). CSI was decreased and FMA of lower extremity was increased after treatment in patients with group A HM grade I. CSI, and FMA of lower extremity changes were statistically significant (P<0.05) when compared with patients with HM grades Ⅱ-Ⅳ. The incidence of hepatic encephalopathy was significantly lower in group B than that in group A (P=0.034), but there was no statistically significant difference between the two groups in the incidence of gastrointestinal bleeding, ascites, infection, MELD score and mortality. Conclusion: A reduced portacaval shunt can improve HM in patients with liver cirrhosis after TIPS, and drug therapy alone is effective for patients with early HM grade I.

The High Energy (HE) X-ray telescope on board the Hard X-ray Modulation Telescope (Insight-HXMT) can serve as a wide field of view (FOV) gamma-ray monitor with high time resolution (mu s) and large effective area (up to thousands cm(2)). We developed a pipeline to search for gamma-ray bursts (GRBs), using the traditional signal-to-noise ratio (SNR) method for blind search and the coherent search method for targeted search. By taking into account the location and spectrum of the burst and the detector response, the targeted coherent search is more powerful to unveil weak and sub-threshold bursts, especially those in temporal coincidence with gravitational wave (GW) events. Based on the original method in literature, we further improved the coherent search to filter out false triggers caused by spikes in light curves, which are commonly seen in gamma-ray instruments (e.g. Fermi/GBM, POLAR). We show that our improved targeted coherent search method could eliminate almost all false triggers caused by spikes. Based on the first two years of Insight-HXMT IHE data, our targeted search recovered 40 GRBs, which were detected by either Swift/BAT or Fermi1GBM but too weak to be found in our blind search. With this coherent search pipeline, the GRB detection sensitivity of Insight-FIXMTIHE is increased to about 1.5E-08 erg cm(-2) (200 keV-3 MeV). We also used this targeted coherent method to search Insight-HXMTIHE data for electromagnetic counterparts of LIGO-Virgo GW events (including O2 and O3a runs). However, we did not find any significant burst associated with GW events.

We report the energy-resolved broadband timing analysis of the black hole X-ray transient MAXI J1631-479 during its 2019 outburst from February 11 to April 9, using data from the Insight−Hard X-ray Modulation Telescope (Insight-HXMT), which caught the source from its hard-intermediate state to the soft state. Thanks to the large effective area of Insight-HXMT at high energies, we are able to present the energy dependence of fast variability up to ∼100 keV. Type-C quasi-periodic oscillations (QPOs) with a frequency varying between 4.9 and 6.5 Hz are observed in the 1–100 keV energy band. While the QPO fractional rms increases with photon energy from 1 keV to ∼10 keV and remains more or less constant from ∼10 keV to ∼100 keV, the rms of the flat-top noise first increases from 1 keV to ∼8 keV and then drops to less than 0.1% above ∼30 keV. We suggest that the disappearance of the broadband variability above 30 keV could be caused by the nonthermal acceleration in the Comptonizing plasma. At the same time, the QPOs could be produced by the precession of either a small-scale jet or a hot inner flow model.

Fast radio bursts (FRBs) are short pulses observed in the radio band from cosmological distances1. One class of models invokes soft gamma-ray repeaters (SGRs), or magnetars, as the sources of FRBs2. Some radio pulses have been observed from some magnetars3, but no FRB-like events have been detected in association with any magnetar burst, including one giant flare4. Recently, a pair of FRB-like bursts (termed FRB 200428) separated by 29 milliseconds were detected from the general direction of the Galactic magnetar SGR J1935+2154 (refs. 5,6). Here, we report the detection of a non-thermal X-ray burst in the 1–250 keV energy band with the Insight-HXMT satellite7, which we identify as having been emitted from SGR J1935+2154. The burst showed two hard peaks with a separation of 34 milliseconds, broadly consistent with that of the two bursts in FRB 200428. The delay time between the double radio peak and the X-ray peaks is about 8.62 s, fully consistent with the dispersion delay of FRB 200428. We thus identify the non-thermal X-ray burst to be associated with FRB 200428, whose high-energy counterpart is the two hard X-ray peaks. Our results suggest that the non-thermal X-ray burst and FRB 200428 share the same physical origin in an explosive event from SGR J1935+2154. Insight-HXMT detected a double-peaked X-ray burst from Galactic magnetar SGR J1935+2154, consistent with two fast radio bursts (FRBs) observed from the same object within seconds. This coincidence suggests a common physical origin, and gives insight into the mechanism behind the origin of FRBs.

We report on the Insight-HXMT observations of the new black hole X-ray binary MAXI J1820+070 during its 2018 outburst. Detailed spectral analysis via the continuum fitting method shows an evolution of the inferred spin during its high soft sate. Moreover, the hardness ratio, the non-thermal luminosity and the reflection fraction also undergo an evolution, exactly coincident to the period when the inferred spin transition takes place. The unphysical evolution of the spin is attributed to the evolution of the inner disc, which is caused by the collapse of a hot corona due to condensation mechanism or may be related to the deceleration of a jet-like corona. The studies of the inner disc radius and the relation between the disc luminosity and the inner disc radius suggest that, only at a particular epoch, did the inner edge of the disc reach the innermost stable circular orbit and the spin measurement is reliable. We then constrain the spin of MAXI J1820+070 to be a*=0.2^+0.2_-0.3. Such a slowly spinning black hole possessing a strong jet suggests that its jet activity is driven mainly by the accretion disc rather than by the black hole spin.

We investigate the absorption and emission features in observations of GX 301-2 detected with Insight-HXMT/LE in 2017-2019. At different orbital phases, we found prominent Fe Kalpha, Kbeta and Ni Kalpha lines, as well as Compton shoulders and Fe K-shell absorption edges. These features are due to the X-ray reprocessing caused by the interaction between the radiation from the source and surrounding accretion material. According to the ratio of iron lines Kalpha and Kbeta, we infer the accretion material is in a low ionisation state. We find an orbital-dependent local absorption column density, which has a large value and strong variability around the periastron. We explain its variability as a result of inhomogeneities of the accretion environment and/or instabilities of accretion processes. In addition, the variable local column density is correlated with the equivalent width of the iron Kalpha lines throughout the orbit, which suggests that the accretion material near the neutron star is spherically distributed.