Accepted
Abstract +
Quantum Sensing exploits quantum resources of well-controlled quantum systems to measure small signals with high sensitivity, and has great potential for both fundamental science and concrete applications. Interacting quantum systems have attracted growing interest in the field of precision measurement, owing to their potential to generate quantum-correlated states and to exhibit rich many-body dynamics. These features provide a novel avenue for exploiting quantum resources in sensing applications. While previous studies have demonstrated enhanced sensitivity using such systems, they have primarily focused on measuring a single physical quantity. The challenge of realizing simultaneous, high-precision measurements of multiple physical parameters using interacting quantum systems remains largely unexplored in experiments. In this study, we demonstrate a first realisation of interaction-based multiparameter sensing with the use of strongly interacting nuclear spins under ultra-low magnetic field conditions. We find that, as the interaction strength among nuclear spins becomes significantly larger than their Larmor frequencies, a different regime emerges where the strongly interacting spins can be simultaneously sensitive to all components of a multidimensional field, such as a three-dimensional magnetic field. Moreover, we observe that the strong interactions between nuclear spins can increase their quantum coherence times as long as several seconds, leading to enhanced measurement precision. Our sensor successfully achieves precision measurement of three-dimensional vector magnetic fields with a field sensitivity reaching the order of 10$^{-11}$T and an angular resolution as high as 0.2rad. Crucially, this approach eliminates the need for external reference fields, thereby avoiding calibration errors and technical noise commonly encountered in traditional magnetometry. Experimental optimization further boosts the sensitivity of the interacting spin-based sensor by up to five orders of magnitude compared to non-interacting or classical schemes. These results demonstrate the significant potential of interacting spin systems as a powerful platform for high-precision, multi-parameter quantum sensing. The techniques developed here pave the way for a new generation of quantum sensors that leverage intrinsic spin interactions to surpass conventional sensitivity limits, offering a promising route toward ultra-sensitive, calibration-free magnetometry in complex environments.
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Abstract +
This paper focuses on standardized fabrications of atomic vapor cells with multipass cells. For this purpose, we have built a vacuum system that enables sealing the mulipass-cavity-assisted cell under vacuum. Alkali atoms are prepared inside a glass holder, and the tip of the holder is broken by controlled collisions under vacuum. Atoms are then transferred to a cell glass body part by heating. Once enough atoms accumulate inside the glass part, buffer and quenching gases are filled into the system, and the glass body part is moved to contact with the silicon wafer which is bonded with a Herriott-cavity. The cavity part and the glass part are sealed together afterwards using the anodic bonding technique. The resulting vapor cells offer enhanced measurement sensitivity and improved device standardization, which allow seamless replacements of each other in practical applications. The performance of these cells are tested, including a test in a double-resonance alkali-metal atomic magnetometer. A magnetic field sensitivity of 95 fT/Hz1/2 is achieved at the frequency range of 10 to 20 Hz with a multipass cell filled with 400 Torr N2 and natural Rb atoms at 100 ℃. The technology and cells developed in this work are expected to have wide applications in atomic devices, especially in He magnetometers and nuclear-spin atomic co-magnetometers, which have special requirements for cell qualities.
, , Received Date: 2025-01-22
Abstract +
Perovskite quantum dots, as an emerging class of nanomaterial, have demonstrated significant potential applications in the field of optoelectronic energy conversion due to their unique optoelectronic properties. In particular, polarons play a crucial role in the optical and optoelectronic performance of perovskite quantum dots. Polaron formation, which involves the coupling of electrons with lattice phonons, can induce charge shielding effect and localization effect, thereby protecting charge carriers from scattering and recombiningd. This leads to longer carrier lifetimes and diffusion lengths, thereby enhancing the efficiency of optoelectronic energy conversion. In this study, a polaronic light absorption model is established using unitary transformation and the Larsen method, revealing the dependence of polaronic transition optical absorption on the electron-phonon coupling constant and effective mass in perovskite quantum dots. The results indicate that the vibration frequency, excited-state energy of polarons, and the transition spectral line frequency are closely related to the electron-phonon coupling strength and effective mass. Specifically, as the electron-phonon coupling constant increases, the vibration frequency and excited-state energy of polarons decrease, while the transition spectral line frequency increases. This finding not only elucidates the physical mechanism of polaronic optical absorption but also provides new insights and methods for optimizing the performance of perovskite quantum dot materials. Moreover, this research expands the application scope of perovskite quantum dots in fields such as photodetectors, light-emitting diodes (LEDs), and solar cells. For instance, in LEDs, the high photoluminescence quantum yield and tunable bandgap of perovskite quantum dots make them ideal luminescent materials. In solar cells, their excellent optoelectronic conversion efficiency and carrier transport properties can significantly enhance device performance. By further optimizing polaron-related characteristics, it is expected that the performance of perovskite quantum dots in these applications can be further improved.
, , Received Date: 2024-11-25
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With the state-of-the-art quantum measurement devices, such as atomic clocks, atomic gyroscopes, and atomic magnetometers, as their central components, the spatiotemporal evolution of atomic spin polarization in the atomic vapor cell has a major effect on both increasing the bandwidth of magnetometer and improving the accuracy of magnetic gradient measurements. However, the major factor impeding the further improvement of the performance of quantum measurement instrument is the inherent static nature of the traditional intra-vapor cell segmentation imaging technique, which makes it challenging to achieve the real-time capture of the dynamic evolution of atomic spin states. In this work, we suggest a dynamic spin imaging method for alkali metal atomic vapor cells with real-time modification of atomic spin polarization states in order to overcome this technological difficulty. In particular, to ensure that the laser can precisely act on the alkali metal atoms in various regions in the vapor cell, we employ a complex beam array management system to modify the on/off state of the laser beams at various positions in the spatial dimension in real time. In the meantime, we generate laser fields with particular spatial distribution and frequency characteristics by using frequency modulation techniques in the time series to accurately regulate the on-off frequency of each laser beam in the beam array. These laser beams cause dynamic changes in the atomic spin polarization state by interacting with alkali metal atoms at various points in the vapor cell. Through precise adjustment of the laser properties, we can see and study the dynamic evolution of the atomic spin-polarization state in real time. According to the experimental data, the technology outperforms the traditional static spin imaging techniques by achieving an excellent temporal resolution of 355 frames per second and a spatial resolution of 95.9 micrometers. The effective use of this method enables us to monitor and evaluate the dynamic aspects of magnetic field distribution with unprecedented precision, also greatly enhance our understanding of the dynamic characteristics of atomic spin polarization.
, , Received Date: 2024-10-11
Abstract +
In this paper, various nonlinear dynamic behaviors of distributed feedback semiconductor laser (DFB-SL) subjected to self-delayed optical and electrical feedback are studied numerically. The results show that the DFB-SL output presents a variety of nonlinear dynamic states such as single-period, quasi-period, and multi-period under different optical feedback intensities. When the external light feedback reaches a certain intensity, the laser output enters a chaotic regime. When the optical feedback intensity is small, a variety of nonlinear dynamic states will appear in the DFB-SL output under different electrical feedback intensities. When the optical feedback intensity is large, the single-period dynamic state cannot be obtained by changing the electrical feedback intensity. The optical feedback and electrical feedback delay time also have a significant influence on the nonlinearity of DFB-SL. When their time delays match, the relaxation oscillation of the laser is enhanced and exhibits a single-period state. And time mismatch may lead to chaos or instability. The bias current also affects the dynamic state, however, the direction of evolution of the dynamic states is not unidirectional as the current changes unidirectionally. When the DFB-SL is in a single-period state, changing the bias current will result in the change of the single-cycle oscillation frequency. These findings provide an important theoretical basis for applying the self-delayed feedback DFB-SL to microwave photonic signal processing and secure optical communication, as well as experimental means for conducting various nonlinear scientific researches.
, , Received Date: 2024-09-08
Abstract +
This paper reviews the physical principles, development history of related application research, current research status and prospects of the Josephson voltage standard (JVS) working at liquid helium temperatures. The JVS working at liquid helium temperature has advantages of high mobility and low-energy consumption, and has a broad application prospect. This paper describes the research status of Josephson voltage standards, focusing on the possibility of developing a JVS based on high-temperature superconductors, and the challenges in chip preparation. In addition, a newly developed preparation technology for Josephson junction, namely the focused helium ion beam, is introduced. It has advantages in the preparation of high consistent Josephson junction arrays in high consistency. Therefore, it is a possible technical route for exploring the realization of JVS working at liquid helium temperature in the future.
, , Received Date: 2025-01-15
Abstract +
A high-stability dual-frequency laser source is a key technology for achieving national ultra-precision measurement capability and also the foundation for supporting the quality of high-end equipment manufacturing. In this work, a high-stability dual-frequency laser source and its frequency difference stability evaluation system are both built based on a double acousto-optic modulation scheme. By investigating the mechanism of generating dual-frequency laser based on double acousto-optic modulation, a degradation model of frequency difference stability is constructed, and targeted technical improvements are implemented. The study shows that the frequency stability of the dual-frequency laser source and the stability of the frequency difference both affect the accuracy of heterodyne interference measurement. The frequency difference stability is determined by factors such as the stability of RF signal and the nonlinear distortion of the power amplifier. This study first optimizes the frequency difference stability to 7.5×10–10 for 1s operation and 1.2×10–9 for 1000s operation by designing a high-order harmonic filtering technique. Then, the DG 4202 RF generator is replaced with a rubidium-clock-based high-stability RF signal generator, thus further optimizing the frequency difference stability to 9×10–11 for 1s operation and 6×10–10 for 1000s operation. The influence of dual-frequency frequency difference stability on heterodyne interference measurement accuracy is reduced to the sub-femtometer level. And the frequency difference stability of the dual-frequency laser source fully meets the application requirements of picometer-level laser interference measurement. Combined with the most advanced frequency stabilization technology using ultra-stable cavity, our high-stability dual-frequency laser source can support heterodyne interference measurement with picometer or even femtometer-level accuracy, demonstrating significant potential for applications in fields such as ultra-precision measurements.
, , Received Date: 2025-01-07
Abstract +
Unidimensional Gaussian modulation continuous-variable quantum key distribution (UD CV-QKD) uses only one modulator to encode information. The UD CV-QKD has the advantages of low implementation cost and low random number consumption, making it attractive for the construction of future miniaturized and low-cost large-scale quantum communication networks. However, in the actual application of the protocol, the intensity fluctuation of the source pulsed light, device defects, and external environmental interference maybe lead to the generation of source intensity errors, thereby affecting the realistic security and performance of the protocol. To solve these problems, the security and performance of UD CV-QKD are studied in depth under source intensity errors in this work. The mechanism of source intensity errors influencing the protocol parameter estimation process is analyzed. To make it possible that the protocol can operate stably under various realistic conditions and ensure communication security, three practical assumptions about the sender’s abilities are made in this work, and corresponding data optimization processing schemes for these assumptions are proposed to reduce the negative influence of source intensity errors. Additionally, both source errors and finite-size effect are comprehensively considered to ensure the realistic security of the system. The simulation results indicate that the source intensity errors cannot be neglected and the maximum transmission distance of the system will be reduced by approximately 20 km for significant intensity fluctuations. Therefore, in the practical implementation of the protocol, the influence of source intensity errors must be fully considered, and the corresponding countermeasures should be taken to reduce or even eliminate these errors. This study provides theoretical guidance for securely implementing the UD CV-QKD in real-world environments.
, , Received Date: 2025-01-26
Abstract +
Germanium material holds great potential applications in low-power, high-mobility field-effect transistors because of their advantages of high electron and hole mobility, narrow bandgap, and compatibility with silicon CMOS technologies. The development of high-quality gate oxide processes is crucial in fabricating high-mobility Ge-based transistors, especially those with high dielectric constant for superior gate control and preferable gate stability. Rare-earth oxides represented by LaLuO3 have high dielectric constants and high crystallization temperatures, making them potential candidates for Ge-based MOSFET gate technology. In this work, a germanium (Ge)-based oxide dielectric LaLuO3 is fabricated utilizing a p-type Ge substrate with a (111) crystal orientation and a doping concentration of 1×1016 cm–3, and radio-frequency (RF) co-sputtering 2-inch 99.9% La2O3 and Lu2O3 targets. Systematical investigations are conducted to evaluate the effects of annealing process conditions on the characteristics of the LaLuO3/Ge MOS gate structure under three specifically designed annealing atmospheres, i.e. nitrogen, oxygen, and a nitrogen-oxygen mixed gas with an N2:O2 ratio of 0.999∶0.001. Meanwhile, the influence of annealing pressure is also explored. The results show that annealing in pure oxygen at atmospheric pressure can reduce the hysteresis of gate capacitance, but it can lead to the formation of interface layers. Correspondingly, annealing technique based on high-pressure and low-oxygen-content (0.1% O2) atmosphere is developed, which not only improves the LaLuO3/Ge interface quality and suppresses the oxygen vacancy generation, but also achieves an extremely low equivalent oxide thickness (EOT) of 1.8 nm and a hysteresis voltage of only 40 mV, resulting in an ideal LaLuO3/Ge MOS structure. This work thus provides a high-performance LaLuO3/Ge gate process solution for Ge MOSFETs.
, , Received Date: 2025-01-17
Abstract +
Surface plasmons (SPs) are generated by the interaction of conduction electrons on the surface of a metallic medium with photons in light wave, and they have an important phenomenon called plasmon-induced transparency (PIT). The PIT effect is crucial for improving the performance of nano-optical devices by strengthening the interaction between light and matter, thereby enhancing coupling efficiency. As is well known, traditional PIT is mainly achieved through two main ways: either through destructive interference between bright and dark modes, or through weak coupling between two bright modes. Therefore, it is crucial to find a new excitation method to break away from these traditional approaches. In this work, we propose a single-layer graphene metasurface composed of longitudinal graphene bands and three transverse graphene strips , which can excite a tripe PIT through the synergistic effect between two single-PITs. We then leverage the synergistic effect between these two single-PITs to realize a triple-PIT. This approach breaks away from the traditional method of generating PIT through the coupling of bright and dark modes. The numerical simulation results are also obtained using the finite-difference time-domain, which are highly consistent with the results of the coupled-mode theory, thereby validating the accuracy of the results. In addition, by adjusting the Fermi level and carrier mobility of graphene, the dynamic transition from a five-frequency asynchronous optical switch to a six-frequency asynchronous optical switch is successfully achieved. The six-frequency asynchronous optical switch demonstrates exceptional performance: at frequency points of 3.77 THz and 6.41 THz, the modulation depth and insertion loss reach 99.31% and 0.12 dB, respectively, while at the frequency point of 4.58 THz, the dephasing time and extinction ratio are 3.16 ps and 21.53 dB, respectively. Additionally, when the tuning range is from 2.8 THz to 3.1 THz band, the triple-PIT system exhibits a remarkably high group index of up to 1212. These performance metrics exceed those of most traditional slow-light devices. Based on these results, the structure is expected to provide new theoretical ideas for designing high-performance devices, such as optical switches and slow-light devices.
, , Received Date: 2025-01-24
Abstract +
In SrTiO3-based oxide heterostructures, the mobility of the two-dimensional electron gas (2DEG) at the interface is relatively low at room temperature due to the influence of Ti 3d orbitals, which limits their applications in semiconductor devices. In contrast, the conduction band bottom of SnO2 is composed of Sn 5s orbitals, and it has been demonstrated that bulk SnO2 exhibits high carrier mobility at room temperature. Therefore, SnO2-based heterostructure interfaces have the potential to form 2DEG with high mobility at room temperature. In this paper, we construct a heterostructure (HfO2)7/(SnO2)13 with $2 \times 1$ supercell in (001) plane and systematically investigate the electronic structure of the heterostructure by using first-principles calculations. The calculation results show that the defect-free (HfO2)7/(SnO2)13 heterostructure has a band structure similar to that of a semiconductor, and there is no 2DEG near the interface of the heterostructure. However, the conduction band bottom is mainly contributed by non-degenerate Sn 5s orbitals in this situation. In the in-plane $2 \times 1$ supercell of the (HfO2)7/(SnO2)13 heterostructure, each layer contains 8 oxygen atoms (the thickness of 1 unit cell is defined as a layer). When an oxygen atom in a layer on the SnO2 side near the interface of the heterostructure is removed, the presence of the oxygen vacancy leads to the formation of a defect band below the conduction band. This will lead to hopping conductivity in the heterostructure. However, 2DEG still does not appear near the heterostructure interface. When the oxygen vacancy is located in the surface layer of the HfO2 in the supercell structure, the presence of the oxygen vacancy leads to the formation of a defect state in the surface. The electrons in the defect state are localized and do not contribute to conductivity. However, the defect band overlaps with the conduction band at the interface, causing the electrons on the surface of HfO2 to tunnel towards the interface. In this scenario, the 2DEG emerges in the vicinity of the heterostructure interface. In addition, for HfO2/SnO2 heterostructures with thinner HfO2 layers, such as HfO2 layer with a thickness of 7 unit cells (about 2.37 nm), the H atoms adsorbed on the HfO2 surface provide electrons for the heterostructure. Some of these electrons transfer to the conduction band near the interface, leading to the formation of a 2DEG in that region. Meanwhile, the remaining electrons stay on the surface, forming a conductive layer with a thickness of approximately 2 unit cells. As the thickness of the HfO2 layer increases, the probability of electrons transferring from the surface to the interface gradually decreases, resulting in a gradual decrease in the electron density at the interface.
, , Received Date: 2025-01-31
Abstract +
Stimulated Brillouin scattering lidar (SBS-LiDAR) technology possesses significant advantages such as high resolution, high signal-to-noise ratio, and strong anti-interference capacity, making it highly promising for simultaneous measurements of temperature, salinity, and sound velocity in seawater. Stimulated Brillouin scattering (SBS) is a nonlinear dynamic process characterized by temporal variations in its occurrence location, peak intensity, and spectral shape. Through numerical simulations of Stokes pulse, the conditions for SBS generation can be quantitatively determined, thereby establishing a theoretical foundation for optimizing lidar systems and enhancing their detection capabilities. Existing studies on Stokes pulses typically focus on specific experimental configurations under varying parameters, including medium properties, pump laser characteristics, and ambient environmental factors. There are still significant discrepancies in reported conclusions regarding the relationship between incident energy levels and pulse width variations, particularly in water-based environments where systematic research on the Stokes scattering pulse characteristics is clearly insufficient. In this study, a distributed noise model is used to theoretically simulate and analyze the time-domain signals of SBS in water at different laser wavelengths, pulse widths, and focal lengths. The characteristics of Stokes pulses generated by focused and non-focused configurations are investigated. The results indicate that under the same conditions, shorter incident wavelength produces significantly higher peak power of Stokes scattering light. The Stokes scattering light exhibits significant energy-dependent behavior: at low input energy, short pulse generates stronger scattering signal due to enhanced nonlinear interaction efficiency, while at high input energy, longer pulse exhibits excellent performance by maintaining temporal coherence. The larger focal length results in lower peak power but better pulse fidelity. As the incident energy increases, the pulse width of Stokes scattering light in the non-focused configuration exhibits a continuous increase. In contrast, for the focused configuration, the pulse width initially decreases and then increases, exhibiting an optimal compression value influenced by temperature and energy. At lower temperatures, the Stokes pulse width exhibits excellent compression performance near the threshold energy. Therefore, reducing secondary peak interference and suppressing spectral broadening are critical technical challenges that must be systematically addressed for short-range SBS-Lidar applications. In low-temperature detection scenarios, dynamic attenuation control becomes essential to prevent thermal stress-induced damage to photodetectors. These findings are of great significance in enhancing the performance of SBS-LiDAR system.
, , Received Date: 2025-01-18
Abstract +
The divertor detachment and heat flux control under high-confinement H-mode conditions in tokamaks represent critical physical challenges in current magnetic confinement fusion research. Understanding the influence of detachment on H-mode boundary transport physics, particularly its compatibility with core confinement, is central to resolving divertor detachment physics. In this study, experimental results on divertor detachment and core confinement compatibility in H-mode plasma from the HL-2A tokamak are presented. On the objective MHD framework for integrated tasks (OMFIT) integrated modeling platform, a novel neural network-based fast integrated modeling method for the divertor target region is developed by integrating a new edge neural network module (Kun-Lun Neural Networks, KLNN) to enhance divertor, scrape-off-layer and edge pedestal fast prediction capability. For the first time, this method is used to conduct integrated simulations of divertor detachment and core confinement compatibility in HL-2A discharge #39007 under high-confinement mode. The simulation results are validated with experimental measurements, demonstrating that they are well consistent. Further analysis reveals that in HL-2A H-mode detachment scenarios, turbulent transport in the core region ($ 0.1 < \rho \leqslant 0.5 $) with high poloidal wave numbers $ ({k}_{\theta }{\rho }_{{\mathrm{s}}} > 1 $) is dominated by ion temperature gradient (ITG) mode, while electron-driven turbulence prevails in the region $ (0.5 < \rho \leqslant 0.7) $. In the boundary region, electron turbulence dominates at low normalized poloidal wave numbers ($ {k}_{\theta }{\rho }_{{\mathrm{s}}} < 2 $), whereas ITG modes become predominant at higher wave numbers ($ {k}_{\theta }{\rho }_{{\mathrm{s}}} > 2 $), accompanied by minor electron turbulence contributions. The research results of this work provide a certain foundation for integrated simulation and experimental verification in the study of core-edge coupling physics in tokamak devices and some insights for understanding detachment-compatible H-mode scenarios in the next-step fusion devices.
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Abstract +
Identifying key nodes in complex networks or evaluating the relative node importance with respect to others using quantitative methods is a fundamental issue in network science. To address the limitations of existing approaches—namely the subjectivity in assigning weights to importance indicators and the insufficient integration of global and local structural information—this paper proposes an entropy-weighted multi-channel convolutional neural network framework (EMCNN). First, a parameter-free entropy-based weight allocation model is constructed to dynamically assign weights to multiple node importance indicators by computing their entropy values, thereby mitigating the subjectivity inherent in traditional parameter-setting methods and enhancing the objectivity of indicator fusion. Second, global and local structural features are decoupled and reconstructed into separate channels to form multi-channel feature maps, which significantly enhance the representational capacity of the network structure. Third, by leveraging the feature extraction capabilities of convolutional neural networks and the integration power of attention mechanisms, the framework extracts deep representations of nodes from the multi-channel feature maps, while emphasizing key structural information through attention-based weighting, thus enabling more accurate identification and characterization of node importance. To validate the effectiveness of the proposed method, extensive experiments are conducted on nine real-world networks using the SIR spreading model, assessing performance in terms of correlation, accuracy, and robustness. The Kendall correlation coefficient is employed as the primary evaluation metric to measure the consistency between predicted node importance and actual spreading influence. Additionally, experiments are performed on three representative synthetic networks to further test the model’s generalizability. Experimental results demonstrate that EMCNN consistently and effectively evaluates node influence under varying transmission rates, and significantly outperforms mainstream algorithms in both correlation and accuracy. These findings highlight the method’s strong generalization ability and broad applicability in key node identification tasks within complex networks.
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Abstract +
Magnetic high-entropy alloy (HEA) is prospective in the application of energy conversion, hysteresis motor, electromagnetic control mechanism and other related fields. In this study, AlCoCrCuFeNi HEA was prepared by selective laser melting (SLM) with different process parameters, and the phase composition, microstructure, magnetic properties and micromechanical behavior were studied systematically. The results show that the SLMed alloys mainly consist of a BCC matrix phase with a small amount of approximately spherical FCC precipitated nanophase. The nanohardness decreases with the increase of laser power and fluctuates in a certain range with the change of scanning speed, but the whole samples show excellent micromechanical properties. Besides, it was found the roomtemperature nanoindentation creep deformation mechanism of AlCoCrCuFeNi HEAs was mainly controlled by dislocation motion, which is different from the traditional classical creep theory. Both SLMed alloys exhibit typical semi-hard magnetic properties. The saturation magnetization is affected slightly by the SLM process parameters and remains at about 43 A·m2/kg because all samples have a similar content of ferromagnetic elements (Fe,Co and Ni). However, the coercivity increases from 1.72 kA/m to 2.71 kA/m with the increase of laser power (P), and decreases from 2.37 kA/m to 1.98 kA/m with the increase of scanning speed (v), which can be attributed to the different effect of porosity and internal stress on the pinning of domain walls under different process parameters (P and v). This work provides a theoretical basis and experimental direction for further study on optimizing comprehensive magnetic properties and room temperature creep mechanism of SLMed high-entropy alloy.
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