Accepted
, , Received Date: 2025-10-15
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This work investigates the magnetocaloric effect-based green magnetic refrigeration technology, with a focus on Ni-Mn-Ga Heusler alloy as a promising magnetic refrigerant candidate. To elucidate the role of Mn-rich composition in regulating the magnetic and magnetocaloric properties, a multi-scale computational approach integrating first-principles calculations and Monte Carlo simulations is adopted. This method enables a detailed analysis of how Mn atoms occupying Ni and Ga sites influence the microstructure, atomic magnetic moments, exchange interactions, and macroscopic magnetocaloric response of the alloy. The results indicate that Mn site occupancy critically affects the magnetic performance: the occupation of Ni sites reduces the total magnetic moment and Curie temperature, thereby reducing the magnetic entropy change; in contrast, Mn occupying Ga sites significantly enhances both the total magnetic moment and the magnetic entropy change. Notably, the Ni8Mn7Ga1 alloy achieves a maximum magnetic entropy change of 2.32 J·kg–1·K–1 under a 2 T magnetic field, which significantly exceeds that of the stoichiometric Ni8Mn4Ga4 alloy. Further electronic structure analysis reveals that Mn content variation modulates the density of states near the Fermi level and optimizes orbital hybridization and ferromagnetic exchange interactions, thus adjusting the magnetic phase transition behavior. Critical exponent analysis confirms that the magnetic interactions are inherently long-range and tend toward mean-field behavior with compositional changes. By establishing a clear “composition-structure-magnetism-magnetocaloric performance” relationship on an atomic scale, this work provides theoretical foundations for designing high-performance, low-hysteresis magnetic refrigeration materials.
, , Received Date: 2025-07-09
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, , Received Date: 2025-08-29
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, , Received Date: 2025-09-04
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Multiple diagnostic techniques measured neutral gas temperatures in N2 plasma and Ar-N2 mixed plasma
, , Received Date: 2025-09-10
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Low-temperature inductively coupled radio-frequency plasma is a key plasma source in semiconductor fabrication, where the neutral gas temperature (Tg) is one of the critical parameters influencing chemical reactions and plasma characteristics. Precise control of Tg significantly influences processes such as thin-film deposition and reactive ion etching, with its synergistic interaction with plasma parameters (ne, Te) often determining process outcomes. Consequently, a thorough understanding of the evolution of Tg and its correlation with discharge parameters has become a critical issue for optimizing semiconductor manufacturing processes. To achieve more accurate measurements of neutral gas temperature, this work employs three temperature measurement techniques: spectroscopy, Bragg grating, and fiber optic sensing. These methods are used to systematically investigate the variation patterns of neutral gas temperature (Tg) in nitrogen plasma and nitrogen-argon mixed plasma under different radio-frequency power, gas pressure, and gas composition conditions. To elucidate the gas heating mechanism, this work combines Langmuir probe measurements of electron density, electron temperature, electron energy probability distribution with a global model simulation. The results show that as the RF power increases, the energy coupled to the plasma increases, the ionization reaction is enhanced, and the collision process and energy transfer between electrons and neutral particles increase, resulting in a monotonically increasing trend of Tg. When gas pressure initially increases, both electron density and background gas density rise together, enhancing heating efficiency and driving rapid Tg growth. However, beyond 3 Pa, electron mean free path shortens and electron density declines. In contrast, background gas density continues to increase, leading to slower Tg growth. In nitrogen/argon mixed system discharges, increasing the argon proportion significantly enhances the rate of Tg increase. This occurs because a higher argon ratio elevates the proportion of high-energy electrons and electron density, thereby strengthening ionization and neutral gas heating. At the same time, argon metastable atoms enhance the density of excited nitrogen particles through the Penning process, which promotes nitrogen molecular excitation to higher energy levels and further heats the gas. Additionally, we observe that the radial temperature distribution in pure nitrogen plasma shifts from parabolic to saddle-type with axial height increasing, due to intensified electron collision excitation near the coil under electromagnetic field effects. In this study, it is also found that the glass transition temperature at the radial edge remains virtually unchanged as atmospheric pressure increases. This is because, as pressure continues to rise, electrons beneath the coil struggle to migrate to the radial edge to collide with neutral particles, thereby limiting the heating of edge neutral particles.
, , Received Date: 2025-06-25
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,
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This work successfully developed a novel high-performance detector based on rare-earth-doped cesium lead chloride (CsPbCl3) inorganic scintillation crystals, targeting the critical demand for GHz-rate capabilities in ultrafast radiation detection at advanced light sources. The Ba2+-doped CsPbCl3 crystals, grown via the vertical Bridgman method, exhibit sub-nanosecond fluorescence rise times, with the pure crystal measuring ~209.6 ps and optimized doped crystals achieving ~50-75 ps. The crystals also feature nanosecond-scale decay times and enhanced light yield through defect engineering. By integrating this core scintillator with a microchannel plate photomultiplier tube (MCP-PMT) featuring sub-nanosecond transit time and a self-developed 2.5 GHz high-speed acquisition system, a complete ultrafast detection system was constructed. Rigorous testing using an optically generated equivalent GHz pulse train demonstrated that the system can clearly resolve consecutive fluorescence pulses with an average peak interval of only 0.79 ns, successfully achieving a high-repetition-rate detection capability of 1.26 GHz. Field application at the Shanghai Synchrotron Radiation Facility's soft X-ray free-electron laser (SXFEL) showed that its X-ray pulse response width is narrower than 4 ns, far superior to the >24 ns response of a reference LYSO:Ce crystal. These results validate the detector's exceptional sub-nanosecond time resolution and GHz-rate pulse discrimination, providing a reliable technical solution for ultrafast time-resolved diagnostics and photon beam loss monitoring in next-generation scientific facilities.
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The characteristics of grain boundaries (GBs) and their mechanical responses under external loading are pivotal in governing the strength and plasticity of polycrystalline ceramics. In this study, first-principles calculations were employed to investigate the stability of Σ5 {310}[001] GBs in (HfNbTaTiZr)C high-entropy carbide ceramic (HECCs) and its constituent binary transition-metal carbides (TMCs), as well as their mechanical behavior under shear and tensile deformation. The results showed that the Σ5{310}[001] GBs in all systems were classified into "Open GB" and "Compact GB" based on their morphologies, with the Open GB exhibiting lower GB formation energy and thus greater structural stability. Under shear deformation, all carbides display shear-coupled GB migration, except for the Open GBs in group IVB TMCs, where the formation of C-C bonds induces supercell failure through the rupture of TM-C bonds. Furthermore, the initial migration stress of Open GB in the HECC is higher than that in binary TMCs, highlighting the strengthening effect introduced by multicomponent GBs. Under tensile deformation, binary TMCs containing Compact GB primarily fail through graphitization, whereas the HECC exhibits both graphitization and intergranular fracture. For Open GB, group IVB TMCs yield due to increased excess volume of GB, while group VB TMCs undergo intergranular fracture; both failure mechanisms coexist in the HECC. Notably, the HECC containing Compact GBs exhibits yield strength comparable to the peak strength of binary TMCs, surpassing the "weakest-link" limit typically associated with ideal condition (0 K and defect-free). Overall, this work elucidates the synergistic roles of GB and multicomponent effects in governing mechanical responses in HECC, suggesting that the interplay between multicomponent effects and defects may underlie the exceptional mechanical performance of high-entropy materials. These findings provide theoretical guidance for GB engineering and mechanical optimization in HECCs, and they offer insights into exploring their mechanical behavior under complex defect interactions.
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In recent years, with the advancement of attosecond pulse generation and polarization-shaping techniques, vortex structures with Archimedean spiral features observed in photoelectron momentum distributions have attracted broad attention in the study of ultrafast electron dynamics in atoms and molecules. This paper provides a systematic review of the generation mechanisms, dynamical behavior, and application prospects of electron vortices in attosecond photoionization. Theoretical studies reveal that electron vortices originate from quantum interference between photoelectron wave packets with different magnetic quantum numbers. Their number of spiral arms and spatial distributions are highly sensitive to the laser pulse polarization, time delay, chirp, and the orbital symmetry of the target system. Experimentally, by combining polarization-shaped pulses with high-resolution photoelectron imaging techniques, a variety of vortex structures have been successfully observed and verified. Beyond their fundamental interest, electron vortices demonstrate significant application potential in interference metrology, carrier-envelope phase retrieval, electron displacement and time-delay measurements, and further open new avenues for molecular orbital imaging and quantum-state control. Finally, this paper outlines future research directions and potential applications of electron vortices in strong-field ionization, molecular dissociation, and related areas.
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The nitrogen-vacancy (NV) center in diamond has rapidly evolved into one of the most versatile and dynamic solid-state quantum platforms, spanning condensed matter physics, emerging quantum technologies, nanoscience, and life sciences. This prominence stems from its unique combination of properties: millisecond-scale spin coherence at room temperature, atomic-scale spatial resolution, non-invasive and non-destructive operation, remarkable chemical stability, excellent biocompatibility, and the tunable coupling strength to multiple physical fields. Its electron spin can be efficiently initialized by laser illumination and precisely manipulated via microwave resonance, enabling high-sensitivity detection of magnetic and electric fields, temperature, stress, and spin signals—with some experiments already achieving single-nuclear-spin or single-electron-charge resolution. In this review, we begin with a concise overview of the fundamental properties of the NV center, clarifying the influence of spin-orbit coupling, hyperfine interactions, and other key effects on its energy level structure. We then systematically outline the fabrication methods for creating NV centers with high spatial control and spectral quality. Finally, we provide a detailed exposition of how NV centers are employed for nanoscale sensing and measurement across various physical domains, highlighting both established protocols and recent experimental advances. Through this structured presentation, the review aims to offer a coherent and updated resource for researchers exploring the interdisciplinary potential of diamond NV centers.
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The dynamic interaction of microbubbles in an ultrasonic field is a core scientific issue for precise manipulation in acoustofluidics and the efficient application of ultrasonic cavitation. Existing microbubble generation technologies (e.g., ultrasonic cavitation and laser-induced nucleation) generally suffer from limitations such as non-uniform bubble sizes, random spatial distribution, and the difficulty of balancing high-precision control with high-throughput repeatability. Furthermore, multi-bubble dynamics theory currently lacks systematic experimental support under multi-parameter coupling (e.g., initial radius, spacing, and orientation angle). In this study, we propose an experimental method using low-intensity ultrasound with a hydrophobic surface as a stable bubble source to release surface microbubbles, which subsequently migrate towards the acoustic pressure antinode. Using high-speed imaging technology, we systematically observed and analyzed the mutual translational behavior of coupled twin bubbles within the aggregation region, identifying four translational modes with distinct characteristics. The results indicate that the bubble aggregation region is precisely located at the acoustic pressure antinode, and the bubble area fraction within this region increases significantly with increasing dimensionless power. The four identified translational modes, which are strongly coupled with radial oscillation, consist of a "velocity bouncing-collision" process. Modes I and III manifest as accelerated collisions driven by velocity bouncing and radial contraction, while Modes II and IV manifest as decelerated collisions induced by velocity bouncing and radial expansion. Statistical analysis of the twin-bubble translational collision data demonstrates that as power increases, the amplitude of radial oscillation increases, the number of velocity bounces decreases, and the translational collision process accelerates significantly. Moreover, at higher power levels, Modes III and IV tend to degenerate towards Modes I and II. The initial radius ratio, initial spacing, and collision Reynolds number are key parameters regulating the translational modes. Modes I and II dominate when the initial radius ratio deviates from 1 and the initial spacing exceeds 350 μm, whereas Modes III and IV are more likely to occur when the initial radius ratio approaches 1 and the initial spacing is less than 200 μm. The orientation angle has no significant effect on the modes. The predictions of the twin-bubble theoretical model show good agreement with the experimental data, validating the precise regulation mechanism of radial oscillation on bubble translational behavior. These insights into the translational motion laws of twin bubbles in low-intensity ultrasonic fields provide a crucial experimental basis for the dynamic modeling of multi-bubble systems and hold significant implications for the optimal design of acoustofluidic devices, targeted microbubble delivery, and the optimization of ultrasonic cavitation applications.
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Optical frequency combs serve as a core technology for optical clocks and frequency transfer, and their linewidth directly impacts the precision of frequency measurements. Consequently, linewidth compression has been a major research focus in the field of frequency combs. The noise of laser has a significant impact on the performance of the carrier-envelope offset frequency (fceo), and different mode-locking mechanisms of the laser result in distinct noise properties. Additionally, intensity fluctuations in the pump source also affect the phase noise of the laser.
In this work, a polarization-maintaining figure-9 mode-locked laser (F9L) is established by incorporating dispersion management technology, with the repetition rate continuously tunable in the range of 197.8-200.65 MHz. Compared with a previously developed nonlinear polarization rotation (NPR) mode-locked laser of the same repetition rate, the F9L exhibited superior phase noise performance. Within the 1 Hz-1 MHz integration range, the phase noise of NPR and F9L is 222.4 ps and 18.5 ps, respectively. Based on the F9L, an all-polarization-maintaining optical frequency comb system was built. The spatial light from the laser is coupled into the fiber through a collimator, and the average output power after a bidirectional pumping amplifier reaches 395 mW. Amplifier-output pigtail fiber length was controlled to manipulate the evolution of higher-order solitons. When the output fiber length is trimmed to 41 cm, the pulse width is measured to be 78 fs after Gaussian fitting. The pulsed light was launched into a section of highly nonlinear fiber, generating a supercontinuum spectrum that fully covers the 1000-2000 nm. A carrier-envelope offset frequency (fceo) signal with a signal-to-noise ratio of 47 dB was successfully obtained with a common path f-2f interferometer.
Under driving by the same LDC8020 pump source, the free-running fceo linewidths of the NPR and F9L mode-locked lasers were measured as 221.5 kHz and 11.4 kHz, respectively. Additionally, the effects of pump current noise and the angle of the 1/8 waveplate inside the F9L cavity on the fceo linewidth were systematically studied. For the pump current noise analysis, two types of current sources with different noise levels, namely Thorlabs LDC8020 (20 μA RMS) and Thorlabs CLD1015 (10 μA RMS), were employed. When the F9L was driven by the lower-noise CLD1015 current source, the free-running fceo linewidth was further narrowed to 6.6 kHz, and the multi-peak structure in the spectrum was eliminated, demonstrating the positive role of optimizing pump current noise in linewidth compression. Regarding the waveplate angle, experiments were conducted at angles of 45°, 55°, and 65°. It was found that an appropriate waveplate angle (55° in this case) balanced the modulation depth and intracavity loss, effectively suppressing amplified spontaneous emission (ASE) quantum noise and minimizing phase noise, thereby achieving the optimal fceo linewidth. Finally, the standard frequency deviations of the repetition rate and fceo were 0.376 mHz and 0.263 mHz, respectively, under two consecutive days of locking.
In this work, a polarization-maintaining figure-9 mode-locked laser (F9L) is established by incorporating dispersion management technology, with the repetition rate continuously tunable in the range of 197.8-200.65 MHz. Compared with a previously developed nonlinear polarization rotation (NPR) mode-locked laser of the same repetition rate, the F9L exhibited superior phase noise performance. Within the 1 Hz-1 MHz integration range, the phase noise of NPR and F9L is 222.4 ps and 18.5 ps, respectively. Based on the F9L, an all-polarization-maintaining optical frequency comb system was built. The spatial light from the laser is coupled into the fiber through a collimator, and the average output power after a bidirectional pumping amplifier reaches 395 mW. Amplifier-output pigtail fiber length was controlled to manipulate the evolution of higher-order solitons. When the output fiber length is trimmed to 41 cm, the pulse width is measured to be 78 fs after Gaussian fitting. The pulsed light was launched into a section of highly nonlinear fiber, generating a supercontinuum spectrum that fully covers the 1000-2000 nm. A carrier-envelope offset frequency (fceo) signal with a signal-to-noise ratio of 47 dB was successfully obtained with a common path f-2f interferometer.
Under driving by the same LDC8020 pump source, the free-running fceo linewidths of the NPR and F9L mode-locked lasers were measured as 221.5 kHz and 11.4 kHz, respectively. Additionally, the effects of pump current noise and the angle of the 1/8 waveplate inside the F9L cavity on the fceo linewidth were systematically studied. For the pump current noise analysis, two types of current sources with different noise levels, namely Thorlabs LDC8020 (20 μA RMS) and Thorlabs CLD1015 (10 μA RMS), were employed. When the F9L was driven by the lower-noise CLD1015 current source, the free-running fceo linewidth was further narrowed to 6.6 kHz, and the multi-peak structure in the spectrum was eliminated, demonstrating the positive role of optimizing pump current noise in linewidth compression. Regarding the waveplate angle, experiments were conducted at angles of 45°, 55°, and 65°. It was found that an appropriate waveplate angle (55° in this case) balanced the modulation depth and intracavity loss, effectively suppressing amplified spontaneous emission (ASE) quantum noise and minimizing phase noise, thereby achieving the optimal fceo linewidth. Finally, the standard frequency deviations of the repetition rate and fceo were 0.376 mHz and 0.263 mHz, respectively, under two consecutive days of locking.
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Near-field thermophotovoltaic (NFTPV) devices enable direct and efficient conversion of thermal radiation into electricity, showing great potential in waste heat recovery and nanoscale energy systems. To enhance conversion efficiency, we propose an NFTPV system based on an hBN/BP/InSb heterostructure, where hexagonal boron nitride (hBN) serves as the emitter, black phosphorus (BP) acts as a tunable interlayer, and indium antimonide (InSb) functions as the photovoltaic cell. The anisotropic surface plasmon polaritons (SPPs) in BP strongly couple with the hyperbolic phonon polaritons (HPPs) in hBN, thereby forming hybrid surface modes that enhance photon tunneling and achieve effective spectral matching with the interband transition of InSb, leading to a substantial increase in near-field radiative heat transfer. Based on fluctuational electrodynamics and detailed balance analysis combined with the transfer matrix method, we systematically evaluated four structural configurations—InSb-hBN, InSb/BP-hBN, InSb-BP/hBN, and InSb/BP-BP/hBN—and examined the influence of vacuum gap distance and BP carrier density on device performance. Among them, the InSb/BP-hBN configuration exhibits the highest performance, with an output power density of 1.2×106 W/m2 and a conversion efficiency approaching 60% of the Carnot limit at a 10 nm gap and 900 K emitter temperature. Furthermore, theoretical analysis reveals that the spatial position of BP critically determines the photon tunneling probability, thereby governing variations in output power and efficiency among different configurations. As the free electron concentration increases from 5×1012 cm-2 to 5×1013 cm-2, the hybridization between SPPs and HPPs changes markedly, leading to distinct enhancement behaviors of radiative energy above and below the InSb bandgap. These findings clarify the mechanism by which SPPs-HPPs hybridization enhances NFTPV performance, offering new insights and design strategies for next-generation high-efficiency thermophotovoltaic devices.
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A new time-scale EPT62 has been constructed based on the observations of 62 millisecond pulsars in the Version A of second data release from the International Pulsar Timing Array (IPTA). Timing noise was analysed carefully for each pulsar and then weighted generalised least square algorithm through Cholesly transformatin was carried out to extract clock error of referenced international atomic time-scale (TAI). The EPT62 spans 29 years and the lock difference EPT62-TAI is given in the Fig. 1. The clock fifference between terrestrial time TT(BIPM2015) and TAI is also shown in the Fig.1. EPT62-TAI and TT(BIPM2015)-TAI show generally similar trends except early few data ponts. Because available observational data are much sparse before MJD 50215 the corresponding EPT62-TAI data points in this period have lager errorbar. The frequency difference data between primary and secondary frequency standards (psfs) and TAI were published in real-time by the Bureau International des Poids et Mesures (BIPM) to supply frequency standard defining SI second for constructing time-scale. The combined smoothing filter was employed to combine clock difference EPT62-TAI and frequency difference between frequency standards and TAI. Then pulsar time and atomic frequency standards combined time-scale (CPA) was derived through the combined smoothing filter. The clock difference CPA-TAI is shown with black curve in the Fig. 1. For the frequency difference curves of psfs-TAI clock difference before and after combined smoothing see Fig. 5 in the text. The constructing process of the CPA was discribed. The property of the CPA was compared in detail with terrestrial time TT(BIPMxxxx). The CPA combined long term frequecy stabily of the EPT62 and acuracy of the atomic frequency standards. In general the property of the CPA is compatible to TT(BIPMxxxx). The comparison of fractional frequecy stability σz curves for EPT62-TAI, CPA-TAI and TT(BIPM2015)-TAI is shown in the Fig. 4 in the text. The CPA can also be used as terrestrial time as TT(BIPMxxxx). Terrestrial time TT(BIPMxxxx) is available one year later whereas CPT may be computed and kept in “real-time” in the future. Finally a brief discussion and some conclusions are given.
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Quantum nonlocality, as an invaluable quantum resource, plays an indispensable key role in numerous quantum information processing tasks. Accurate characterization and effective detection of nonlocality have always been important and challenging topics in theoretical research and experimental exploration of quantum information. How to precisely identify and verify the phenomenon of quantum nonlocality in complex many-body quantum systems, and how to design more efficient detection methods for nonlocality, have become important scientific issues that need to be solved urgently. This paper is dedicated to the detection of multipartite quantum nonlocality, with a focus on exploring how to achieve the detection of multipartite quantum nonlocality using the Svetlichny inequality. Firstly, the maximum quantum violation of the Svetlichny inequality is discussed. Through construction, a quantum state $\rho_0$ and a set of observables $\mathcal{A}_0$ are obtained, which achieve the maximum quantum violation of the Svetlichny inequality. It is also demonstrated how to construct other quantum states and sets of observables to achieve its maximum violation, thereby clarifying that the quantum states and sets of observables that achieve the maximum quantum violation of the Svetlichny inequality are not unique. Secondly, in order to find more quantum states and sets of observables that violate the Svetlichny inequality, the corresponding Hamiltonian was constructed using the Svetlichny operator. This core issue of finding quantum states that violate the Svetlichny inequality was ingeniously transformed into solving the ground state of this Hamiltonian. Leveraging the powerful function approximation capability of neural networks, neural network quantum states were constructed. Two optimization algorithms, the Nelder-Mead simplex method and Quantum Variational Monte Carlo (VMC), were respectively adopted to optimize the network parameters in order to find the ground state energy and ground state of the Hamiltonian, thereby achieving the violation of the Svetlichny inequality and ultimately detecting nonlocal states. To ensure the efficiency and accuracy of the detection method, this paper conducts a comparative study of different optimization methods. By comparing the Nelder-Mead simplex method with the VMC method, it is found that the VMC method is more suitable for nonlocality detection based on neural network quantum states in terms of efficiency and accuracy, providing reliable computational support for the detection of many-body quantum nonlocality and the violation of the Svetlichny inequality. To verify the validity and universality of the proposed method, the nonlocality of multipartite quantum pure states were detected using neural network quantum states and the VMC method under different Hamiltonians. The results demonstrate that this method successfully captures violations of the Svetlichny inequality in many-body quantum systems, thereby achieving effective detection of multipartite quantum nonlocality. This fully confirms the validity and universal potential of the VMC method in nonlocality detection based on neural network quantum states. This study not only verifies the theoretical and technical feasibility of the detection of multipartite quantum nonlocality based on neural network quantum states and the VMC method, but also provides valuable new insights for the field of nonlocality detection. More importantly, it opens up a new research avenue for solving complex quantum many-body problems using neural networks.
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