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We report the first detection of polarization angle orthogonal jumps, a phenomenon previously only observed from radio pulsars, from a fast radio burst (FRB) source FRB 20201124A. We find three cases of orthogonal jumps in over 2000 bursts, all resembling those observed in pulsar single pulses. We propose that the jumps are due to the superposition of two orthogonal emission modes that could only be produced in a highly magnetized plasma, and they are caused by the line of sight sweeping across a rotating magnetosphere. The shortest jump timescale is of the order of 1 millisecond, which hints that the emission modes come from regions smaller than the light cylinder of most pulsars or magnetars. This discovery provides convincing evidence that FRB emission originates from the complex magnetosphere of a magnetar, suggesting an FRB emission mechanism that is analogous to radio pulsars despite a huge luminosity difference between two types of objects.

We report the timing analysis of PSR J1846−0513, a pulsar discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in Commensal Radio Astronomy FAST Survey. The pulsar possesses a spin period of 23.36 ms and a spin-down rate ( $\dot{P}$ ) of 1.0106(3) × 10 ^−18 s s ^−1 , and it is located in an eccentric orbit ( e ∼0.208) with an orbital period of 0.61 days. The characteristic age and surface magnetic field of the pulsar are found to be 366.62 Myr and 4.9178 × 10 ^9 G, respectively, indicating that it is a recycled pulsar. Using over two years of timing data, we measure the periastron advance $\dot{\omega }$ = 0.8956(8) deg yr ^−1 . By assuming that this effect is purely relativistic, we have estimated the total mass M = 2.6287(35) M _⊙ and obtained an upper limit for the pulsar mass and a lower limit for the companion’s mass. Our results indicate that this is a double neutron star system.

We present phase-connected timing ephemerides, polarization pulse profiles, and Faraday rotation measurements of 12 pulsars discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in the Commensal Radio Astronomy FAST Survey. The observational data for each pulsar span at least 1 yr. Among them, PSR J1840+2843 shows subpulse drifting, and five pulsars are detected to exhibit pulse nulling phenomena. PSR J0640−0139 and PSR J2031−1254 are isolated millisecond pulsars (MSPs) with stable spin-down rates ( $\dot{P}$ ) of 4.8981(6) × 10 ^−20 s s ^−1 and 6.01(2) × 10 ^−21 s s ^−1 , respectively. Additionally, one pulsar (PSR J1602−0611) is in a neutron star−white dwarf (WD) binary system with an 18.23-day orbit and a companion of ≤0.65 M _⊙ . PSR J1602−0611 has a spin period, companion mass, and orbital eccentricity that are consistent with the theoretical expectations for MSP−helium WD (He WD) systems. Therefore, we believe that it might be an MSP−He WD binary system. The locations of PSR J1751−0542 and PSR J1840+2843 on the $P-\dot{P}$ diagram are beyond the traditional death line. This indicates that FAST has discovered some low- $\dot{E}$ pulsars, contributing new samples for testing pulsar radiation theories. We estimated the distances of these 12 pulsars based on NE2001 and YMW16 electron density models, and our work enhances the data set for investigating the electron density model of the Galaxy.

This study presents a comprehensive analysis of the spectral properties of 886 pulsars across a wide frequency range from 20 MHz–343.5 GHz, including a total of 86 millisecond pulsars (MSPs). The majority of the pulsars exhibit power-law behavior in their spectra, although some exceptions are observed. Five different spectral models, namely, simple power law, broken power law, low-frequency turnover, high-frequency cutoff, and double turnover, were employed to explore the spectral behaviors. The average spectral index for pulsars modeled with a simple power law is found to be −1.64 ± 0.80, consistent with previous studies. Additionally, significant correlations between the spectral index and characteristic parameters are observed, particularly in MSPs, while no strong correlation is observed in normal pulsars. Different models show variations in the most influential characteristic parameters associated with the spectral index, indicating diverse dominant radiation mechanisms in MSPs. Finally, this study identifies 22 pulsars of the gigahertz-peaked spectra type for the first time based on the Akaike information criterion.

PSR J2150+3427 is a 0.654 s pulsar discovered by the Commensal Radio Astronomy FAST Survey. From the follow-up observations, we find that the pulsar is in a highly eccentric orbit ( e = 0.601) with an orbital period of 10.592 days and a projected semimajor axis of 25.488 lt-s. Using 2.7 yr of timing data, we also measured the rate of periastron advance $\dot{\omega }$ = 0.0115(4) deg yr ^−1 . An estimate for the total mass of the system using the $\dot{\omega }$ gives M _tot = 2.59(13) M _⊙ , which is consistent with most of the known double neutron star (DNS) systems and one neutron star (NS)–white dwarf (WD) system named B2303+46. Combining $\dot{\omega }$ with the mass function of the system gives the masses of M _p < 1.67 and M _c > 0.98 M _⊙ for the pulsar and the companion star, respectively. This constraint, along with the spin period and orbital parameters, suggests that it is possibly a DNS system, and we cannot entirely rule out the possibility of an NS–WD system. Future timing observations will vastly improve the uncertainty in $\dot{\omega }$ , and are likely to allow the detection of additional relativistic effects, which can be used to modify the values of M _p and M _c . With a spin-down luminosity of $\dot{E}$ = 5.07(6) × 10 ^29 erg s ^−1 , PSR J2150+3427 is a very low-luminosity pulsar, with only the binary pulsar J2208+4610 having a smaller $\dot{E}$ .

Exploring the gas-solid compatibility between insulating gas and solids materials used in electrical equipment is of great significance for determining the long-term behavior of insulating gas trifluoromethanesulonyl fluoride (CF3SO2F). The gas-solid compatibility of CF3SO2F and its decomposition products with Ag, Zn, and ZnO common surfaces has been assessed based on first-principles calculations, with SF6 as the control group. CF3SO2F has excellent gas-solid compatibility with the solid surfaces by analyzing the adsorption configurations, adsorption energies, charge transfer, adsorption height, density of states, and ab initio molecular dynamics (AIMD) results. The external electric fields do not affect the excellent compatibility between CF3SO2F and the solid surfaces. Besides, the Ag(111) surface exhibits fine gas-solid compatibility with all decomposition products benefitting from its low surface energy. Originating in the existence of the three-center-four-electron (3c4e) π bond and F atoms with strong electronegativity in SO2F2, SO2F2 has poor compatibility with the Ag(110), (100), and Zn(001) surface. SO2, COF2, and HF gases may accelerate equipment failure due to the strong adsorption strength and poor compatibility with ZnO(100) and (110) surfaces. The results provide the theoretical guidance for the engineering application and long-term performance evaluation of CF3SO2F. [ABSTRACT FROM AUTHOR]

Shape and surface topography evaluation from measured orthogonal slope/gradient data is of considerable engineering significance since many full-field optical sensors and interferometers readily output such a data accurately. This has applications ranging from metrology of optical and electronic elements (lenses, silicon wafers, thin film coatings), surface profile estimation, wave front and shape reconstruction, to name a few. In this context, a new methodology for surface profile and stress field determination based on a recently introduced non-contact, full-field optical method called digital gradient sensing (DGS) capable of measuring small angular deflections of light rays coupled with a robust finite-difference-based least-squares integration (HFLI) scheme in the Southwell configuration is advanced here. The method is demonstrated by evaluating (a) surface profiles of mechanically warped silicon wafers and (b) stress gradients near growing cracks in planar phase objects. [ABSTRACT FROM AUTHOR]

In this study, we present a systematic analysis of the relation between the structural properties and magnetic anisotropies of as-grown and heat-treated polycrystalline Fe 1 − x Ga x (0.11 < x < 0.19) thin films deposited on glass and Si(100) substrates. The results show that the crystallographic texture of the films has a significant impact on the evolution of the magnetic anisotropies. The samples grown on glass do not exhibit a preferred texture while, for samples grown on Si(100), the appearance of a weak in-plane fourfold magnetic anisotropy is reported. Such anisotropy is enhanced and better defined in the heat treated samples. Via a phenomenological model we show that this anisotropy has a microstructural origin. These findings demonstrate the possibility of tuning magnetic anisotropies by growing on different substrates and/or performing thermal treatments, which in turn reinforces the possibility of developing smart magnetic switching materials for electronic applications. [ABSTRACT FROM AUTHOR]

The lowest-order shear horizontal (SH0) guided wave in a plate is crucial for nondestructive testing and structural health monitoring due to its nondispersive nature. However, mode conversion at the interface for the SH0 wave complicates the received information and increases the difficulty of signal analysis. In this work, an elastic metasurface is proposed to suppress mode conversion at the interface and to reflect the SH0 wave directionally. The metasurface comprises a series of rectangular elements with a specific phase gradient covering the 2 π phase range. The effectiveness of the proposed metasurface is confirmed through finite element simulations and experimental validation. The results indicate that the metasurface can significantly reduce the amplitude of the reflected lowest-order symmetric Lamb wave when compared to the reflection without the metasurface, while simultaneously allowing the reflected SH0 wave to propagate at the designed angle. Furthermore, the metasurface maintains its functionality for SH0 wave with incident angles varying from 0° to 25°. This study provides a viable approach for suppressing mode conversion and modulating the reflection behavior of SH0 wave, which is expected to find applications in nondestructive testing and structural health monitoring. [ABSTRACT FROM AUTHOR]

Good environmental compatibility and excellent insulation performance make trifluoroiodomethane (CF3I) have the potential to replace SF6 in gas-insulated equipment. The gas–solid compatibility of CF3I, its main decomposed products (I2, C2F6, C3F8, C2F4, HF, CF3H, COF2), and environmental molecule H2O with the Al and Cu(111) surfaces is investigated based on first-principles calculations. The most stable adsorption configurations of Al and Cu(111) surfaces adsorbed by all gas molecules are constructed, and the interaction types between gas molecules and two metal surfaces are determined by adsorption energy (E ad), charge transfer, and charge density difference. The absolute E ad of CF3I and I2 adsorbed on Al(111) surfaces are 4.09 and 3.76 eV, respectively. In contrast, the absolute E ad of other gases adsorbed on Al(111) surfaces do not exceed 0.99 eV, indicating that CF3I and I2 have strong chemical interactions and poor gas–solid compatibility with Al(111) surfaces, while other gases exhibit good gas–solid compatibility with the Al surface. The absolute E ad of I2 (1.15 eV) adsorbed on Cu(111) surface is significantly larger than that of other gases-adsorbed systems (not exceeding 0.99 eV) including CF3I-adsorbed system, proving that the gas–solid compatibility of I2 with Cu(111) surfaces is worse than that of other gases. In addition, the reasons for the different compatibility of CF3I with Al and Cu(111) surfaces are analyzed in depth through the density of states. [ABSTRACT FROM AUTHOR]

Smart energy storage systems, such as electrochromic supercapacitor (ECSC) integrated technology, have drawn a lot of attention recently, and numerous developments have been made owing to their reliable performance. Developing novel electrode materials for ECSCs that embed two different technologies in a material is an exciting and emerging field of research. To date, the research into ECSC electrode materials has been ongoing with excellent efforts, which need to be systematically reviewed so that they can be used to develop more efficient ECSCs. This mini-review provides a general composition, main evaluation parameters and future perspectives for electrode materials of ECSCs as well as a brief overview of the published reports on ECSCs and performance statistics on the existing literature in this field. [ABSTRACT FROM AUTHOR]

Nanoclusters involve finite metal atoms are of great importance in chemical synthesis and catalysis due to their unique structure-dependent properties. Knowing how nanoclusters work in reaction conditions is no doubt one of the most important challenges, which requires deep insight into atomic-scale dynamics during the process. State-of-the-art in-situ transmission electron microscope (TEM) can realize the real-time study, which is expected to reveal insights into the underlying mechanisms of catalysis and design efficient catalysts. In this minireview, we aim to give a critical review and recent progress on nanocluster dynamics unveiled by in-situ and environmental TEM from two aspects: evolutions of metal single atoms and nanoclusters in high-temperature reaction conditions and the well-defined molecular clusters in confined space. We emphasize the cluster-environment interaction and the cluster structure–property relationships. In the end, we also summarize the present achievements and propose future challenges. We expect this review will fuel the excitement and stimulate research in the fields of cluster and catalysis. [ABSTRACT FROM AUTHOR]

The aim of this work is to overcome the problem of agglomeration and volumetric changes observed in reduced graphene oxide (rGO) and polyaniline (PANI) nanocomposites responsible for inferior capacitive performance. The synergistic effect of optimized rGO, PANI and tellurium (Te) ternary nanocomposite was investigated for the electrochemical performances for the energy storage devices. For this purpose, the electrochemical test was performed at low molar 0.1M H2SO4 concentration of aqueous electrolyte in a two-electrode cell assembly. The electrochemical studies showed that the specific capacitance of 564F g−1 is attained in rGO/PANI nanocomposite electrode cell whose capacitive performance showed an increase by adding different concentration of Te. The maximum specific capacitance of 895 F g−1 at 10 mV s−1 was observed in rGO/PANI/Te50 (GPT50) with negligible charge transfer resistance, knee frequency ∼466.63 Hz, low response time ∼17.39 s, high coulombic efficiency ∼92% and high energy and power densities of 41 Wh kg −1 and 3679 W kg −1 with cyclic stability of ∼91% after 5000 GCCD cycles respectively. The electrochemical performances result of the electrode material indicated that the combination of Te with rGO and PANI can be used to enhance the supercapacitor performances of the rGO/PANI nanocomposite electrodes. This novel composition has overall improved the electrochemical studies of the electrode materials and thus can be used as a suitable candidate for supercapacitor devices. [ABSTRACT FROM AUTHOR]

This study presents the design and test of a novel ultra-simplified flexure-based spring-mass device (NUFSMD) with high sensitivity for relative gravimeters. The NUFSMD is mainly composed of a highly sensitive spring based on flexure hinges (SFH) and a cantilever beam. When the change of gravity causes SFH to rotate, an amplified displacement can be obtained on the tail of the cantilever beam. The displacement is measured by a capacitive displacement sensor. The change of gravitational acceleration can be calculated based on the output of the sensor. A theoretical analysis of the working principle of the NUFSMD is established. A prototype NUFSMD is machined from 304 stainless steel and a series of experiments are carried out. The effectiveness of gravity measurement is demonstrated by finite element simulations and experiments. The experimental results show that the sensitivity of the NUFSMD is about 15.27 μGal nm−1, and the resolution is about 1.83 μGal. The designed NUFSMD shows outstanding performance. And the sensitivity and resolution of the NUFSMD can be further improved by increasing the number of flexible hinges connected in series. Compared with the existing spring-mass devices in high-precision relative gravimeters, the significant advantage of the NUFSMD is that it is simple in structure and easy to machine, which helps to greatly improve performance. Firstly, it is simple in structure, so it can be machined in one piece, which considerately contributes to stability and precision. Secondly, it is easy to machine, so it can be machined from high-performance but difficult-to-machine materials to improve its performance. Thirdly, there are a few parameters that need to be traded off for miniaturization because of the simple structure, so it is easy to be miniaturized to adapt to narrow measurement space. Therefore, it is expected to greatly improve the performance of the existing spring-mass device in relative gravimeters. [ABSTRACT FROM AUTHOR]

The microsphere profile of probe tips has to be measured and compensated to improve the measurement accuracy of micro-coordinate measuring machines (micro-CMMs) to less than several hundred nanometers. A high-precision radius and sphericity measurement method for the microsphere of the CMM probe tip is proposed in this article. Different circumferences of the tested microsphere are measured, and the true radius of any measuring point on the surface can be obtained after separating the runout errors. Then the sphericity of the tested microsphere can be evaluated by the minimum zone sphere method. A corresponding measuring system is developed based on the analysis of the primary error model and mechanical model, and verification experiments are conducted using a ruby microsphere (A-5000-7801, Renishaw Corporation) as the reference, whose claimed diameter and sphericity are 700 µm and 130 nm, respectively. Six groups of repeated experiments are performed, and 18 000 measurement points on 15 circumferences are recorded in each group of experiments. Results show that the average radius of the tested microsphere is 350.003 µm, and the average sphericity error is 208 nm with a standard deviation of 5.3 nm. Finally, the expanded uncertainty of the measurement results of the developed system is calculated as 209 nm (k = 1.96, normal distribution). The proposed method and system can be used in the precision measurements and compensations for probe tips of micro-CMMs and other parts, such as microspheres used in micro-bearings and micro-manufacturing machines. [ABSTRACT FROM AUTHOR]

This study reports a clean and damage-free transfer method that enables the ultrafast transfer of two-dimensional (2D) transition metal dichalcogenides (TMDs) onto desired substrates with a remarkably high yield. We employ a water-soluble sodium salt as both a transfer sacrificial layer for facile transfer and a catalytic layer for the growth of high-quality large-area MoS2 using liquid-phase chemical vapor deposition via a catalyzed kinetic growth. We show that the pristine structural and electrical properties of the grown MoS2 can be reliably preserved by avoiding detrimental effects during the prolonged harsh-environment transfer process. We demonstrate the technological versatility of the proposed transfer method by fabricating as-transferred MoS2-based back-gated field-effect transistors (FETs). The MoS2 FETs exhibit excellent charge mobility as high as 28.7 cm2 V−1 s−1 and an on–off ratio up to ∼107 at room temperature, indicating no performance degradation after the transfer process. The proposed transfer method offers universal applicability for various 2D TMDs, mechanical supporting polymers, and target substrates, thus facilitating the facile fabrication of 2D TMD-based electronics and optoelectronics. [ABSTRACT FROM AUTHOR]

This paper focuses on the anomaly detection for ionospheric total electron content (TEC) before earthquakes. In this paper, a novel unsupervised approach is proposed. First, interval-based method is employed to granulate the TEC series. Justifiable granularity principle is utilized to construct interval information granules (IGs) for representing TEC series. Second, high-order difference method is introduced to construct rectangle IGs and cube IGs for obtaining the new representation of TEC. Third, corresponding similarity measurement method is designed to calculate the anomaly score of each IG, which is the evaluation criterion for detecting the anomalies. Finally, experimental results using real TEC datasets validate the effectiveness of the proposed approach. Compared with the existing major approaches, because the proposed approach can capture more morphological details and variation trend of TEC series, it can achieve a higher detection accuracy. [ABSTRACT FROM AUTHOR]

Here, we prepared a magnetic nanocomposite system composed of a cluster of magnetite nanoparticles coated with silica shell (MSNPs) with an average diameter of 140 ± 20 nm and conjugated with CD9 antibody (AntiCD9) using different strategies including adsorption or chemical conjugation of antibody molecules to either aminated MSNPs (AMSNPs) or carboxylated MSNPs (CMSNPs). Then, MSNPs were employed to isolate exosomes from ultracentrifuge-enriched solution, PC3 cell-culture medium, or exosome-spiked simulated plasma samples. Quantitative tests using nanoparticle-tracking analysis confirmed antibody-covalently conjugated MSNPs, i.e. the AntiCD9-AMSNPs and AntiCD9-CMSNPs enabled >90% recovery of exosomes. Additionally, the exosomes isolated with AntiCD9-CMSNPs showed higher recovery efficiency compared to the AntiCD9-AMSNPs. For both nanoadsorbents, lower protein impurities amounts were obtained as compared to that of exosomes isolated by ultracentrifugation and Exocib kit. The mean diameter assessment of the isolated exosomes indicates that particles isolated by using AntiCD9-AMSNPs and AntiCD9-CMSNPs have smaller sizes (136 ± 2.64 nm and 113 ± 11.53 nm, respectively) than those obtained by UC-enriched exosomes (140.9 ± 1.6 nm) and Exocib kit (167 ± 10.53 nm). Such promising results obtained in the isolation of exosomes recommend magnetic nanocomposite as an efficient tool for the simple and fast isolation of exosomes for diagnosis applications. [ABSTRACT FROM AUTHOR]

Coherent diffraction imaging (CDI) is a high-resolution technique that does not require x-ray lenses. With advances in scientific technology, such as synchrotron radiation, x-ray free-electron lasers, and coherent electron sources, CDI has been applied to diverse fields, such as biology, medicine, and semiconductors, as a high-resolution, nondestructive measure. With the rapid increase in demand for these applications, enhancing the efficiency of processing high-volume data has become a significant challenge for promotion. In this study, we proposed an algorithm that combines Kramers–Kronig (KK) relations with oversampling smoothness (OSS). The results were evaluated by introducing an error coefficient. We found that the error of the KK-OSS algorithm is always reduced by approximately 50% compared with the error reduction (ER) algorithm, hybrid input–output (HIO) algorithm, and OSS in real space. In the diffraction space, the error in the KK-OSS can be decreased to 0.11. With 100 iterations, KK-OSS spent 218.3 s on reconstructing most of the sample information, while ER was 258.1 s, HIO algorithm took 296.7 s and the reconstruction was still a random value. In Fraunhofer diffraction, it cost KK-OSS 58.8 s to reconstruct, while OSS took 61.9 s. Therefore, this method can reduce the reconstruction error, shorten the reconstruction time, and improve the efficiency compared with the ER, HIO, and OSS algorithms using a random phase as the initial value. [ABSTRACT FROM AUTHOR]

A dual-band quasi-single-layer absorber based on multimode resonance is proposed. Different from the traditional multi-substrate or multi-resonator composite structure, by virtue of stub- and slot-loaded technologies, only one single-substrate printed resonator is utilized to achieve multi-mode resonant characteristics for two absorption bands. The bandwidth of the two absorption bands can be adjusted by structural parameters. Through the detailed analysis of the surface current distribution in different modes, the generation principle of the multi-mode dual-band characteristic is revealed. Finally, the dual-band absorber is fabricated and measured, achieving dual-band absorptions in the frequency range of 7.64–10.8 GHz and 15.04–17.32 GHz with fractional bandwidth of 34.3% and 14.1%, respectively. The advantages of low-profile simple structure and controlled dual bandwidth make it very suitable for radar detection and stealth fields. [ABSTRACT FROM AUTHOR]