Ultramicroscopy最新文献

Temperature distributions in MEMS microheaters during gas phase experiments in an environmental TEM 环境瞬变电磁法气相实验中MEMS微加热器的温度分布。

IF 2 3区工程技术 Q2 MICROSCOPY

Ultramicroscopy

Pub Date : 2026-04-01 Epub Date: 2026-02-01 DOI: 10.1016/j.ultramic.2026.114326

Amit Kumar , Zhongtao Ma , Julian Taubmann , Arash Nemati , Kristian Speranza Mølhave , Joerg R. Jinschek , Magnus Björnsson , Søren Bredmose Simonsen

Reliable sample temperature measurements are essential in environmental transmission electron microscope (ETEM) experiments. In this study, the effect of flowing gases on the temperature distribution at a MEMS microheater in gas phase is investigated. A computational fluid dynamics model is developed and compared with experimental data. The modeling results agree well with experimental measurements based on the melting temperature of Zn nanoparticles, confirming the model’s reliability. The results show that the temperature profile across the heating chip in the case with H₂ environment is less uniform compared to the case of vacuum and O₂. For example, at a set temperature of 900 °C in 3 mbar H₂, a temperature difference of 60 °C is observed between the central sample position compared to the surrounding arc-shaped heater which also is the temperature sensor, while the difference in the vacuum case is only 13 °C. Temperature is one of the key parameters in in-situ TEM experiments and, therefore, these findings are important in the design of ETEM experiments, especially when using MEMS microheaters with relatively large distances between TEM sample and microheater/sensor.

在环境透射电子显微镜实验中，可靠的样品温度测量是必不可少的。本文研究了气体流动对MEMS微加热器气相温度分布的影响。建立了计算流体力学模型，并与实验数据进行了比较。模拟结果与基于锌纳米颗粒熔化温度的实验测量结果吻合较好，验证了模型的可靠性。结果表明，与真空和O2环境相比，H2环境下加热芯片的温度分布不均匀；例如，在3mbar H2中设定温度为900°C时，与周围的弧形加热器（也是温度传感器）相比，中心样品位置的温差为60°C，而真空情况下的温差仅为13°C。温度是原位瞬变电磁法实验的关键参数之一，因此，这些发现对瞬变电磁法实验设计具有重要意义，特别是当使用MEMS微加热器时，TEM样品与微加热器/传感器之间的距离相对较大。

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引用次数: 0

Exploring the potential of simultaneous resonance in multi-frequency atomic force microscopy 探索同时共振在多频原子力显微镜中的潜力

IF 2 3区工程技术 Q2 MICROSCOPY

Ultramicroscopy

Pub Date : 2026-04-01 Epub Date: 2026-01-29 DOI: 10.1016/j.ultramic.2026.114321

Mostafa Ghanbari Kouchaksaraei, Arash Bahrami

We exploit simultaneous resonance phenomenon to improve performance of multifrequency atomic force microscopy. Simultaneous resonances, activated due to the nonlinear nature of the tip oscillations and intermodal couplings for a certain family of multi-frequency excitations, may be used to gather more information about the sample. To make simultaneous resonance occur, excitation frequencies are tuned in a way that two resonances take place simultaneously. We consider a non-contact atomic force microscope and model the three-dimensional probe-tip structure as an Euler–Bernoulli beam. Equation governing motion of the probe tip are obtained employing the Hamilton extended principle. Direct harmonic balance method is then used to solve this equation. It is found out, through extensive numerical simulations, that the present excitation scheme, which activates simultaneous resonance, improves both the resolution and the compositional contrast of images. Numerical investigations demonstrate that a small change in the Hamaker constant and the initial tip–sample distance leads to a significant change in the amplitude and/or phase shift of the simultaneous resonance. High sensitivity of the amplitude to the initial tip–sample distance can be utilized to increase the vertical resolution in environments with high and low quality factors. Also, simultaneous resonance phase shift sensitivity to the Hamaker constant is noticeably increased compared to that of the conventional multi-frequency atomic force microscopy. As a result, the compositional contrast is considerably enhanced.

我们利用同步共振现象来提高多频原子力显微镜的性能。同时共振，由于尖端振荡的非线性性质和多模态耦合的某种多频率激励激活，可以用来收集更多关于样品的信息。为了使共振同时发生，需要调整激励频率，使两个共振同时发生。我们考虑非接触原子力显微镜，并将三维探针-尖端结构建模为欧拉-伯努利梁。利用哈密顿扩展原理，得到了控制探针尖端运动的方程。采用直接谐波平衡法求解该方程。通过大量的数值模拟发现，该激励方案激活了同步共振，提高了图像的分辨率和组成对比度。数值研究表明，Hamaker常数和初始尖端-样本距离的微小变化会导致同步共振的幅度和/或相移发生显著变化。在高质量因子和低质量因子环境下，利用振幅对初始尖样距离的高灵敏度可以提高垂直分辨率。同时，与传统的多频原子力显微镜相比，同步共振相移对Hamaker常数的灵敏度显着增加。因此，成分对比大大增强。

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引用次数: 0

Enhancing atomic force microscopy stability through second harmonic optical fibre cavity control 通过二次谐波光纤腔控制提高原子力显微镜的稳定性

IF 2 3区工程技术 Q2 MICROSCOPY

Ultramicroscopy

Pub Date : 2026-04-01 Epub Date: 2026-01-27 DOI: 10.1016/j.ultramic.2026.114324

Joana Nobre, Tiago Cordeiro, Tiago T. Robalo, Ana P. Carapeto, Mário S. Rodrigues

The interatomic potential is key to understanding all properties of materials. Yet, conventional atomic force microscopes do not usually measure the interatomic potential, because they lack control of the tip-sample distance. Here, we propose a simple methodology for measuring tip–surface interactions directly as a function of tip-sample distance, rather than deflection as a function of sample displacement. We use an AC interferometer to monitor the absolute tip displacement. When a force is applied on the tip a negative feedback loop displaces the cantilever anchoring point, deflecting the lever such that the tip position remains constant. This feedback loop actively maintains the tip at a distance from an optical fibre where the interferometer sensitivity is maximum. As a result, the tip-sample distance or the indentation is directly given by the sample motion and the tip does not jump-to-contact.

原子间势是理解材料所有性质的关键。然而，传统的原子力显微镜通常不能测量原子间电位，因为它们缺乏对尖端样品距离的控制。在这里，我们提出了一种简单的方法，可以直接测量尖端-表面相互作用作为尖端-样本距离的函数，而不是作为样本位移的函数的挠度。我们使用交流干涉仪来监测绝对尖端位移。当一个力被施加在尖端，负反馈回路取代悬臂锚固点，偏转杠杆，使尖端的位置保持不变。这个反馈回路主动地保持尖端与光纤的距离，在那里干涉仪的灵敏度是最大的。因此，尖端与样品之间的距离或压痕直接由样品的运动决定，而尖端不会跳跃接触。

引用次数: 0

Anisotropic redistribution of coherently de-channelled electrons around dislocations in gallium nitride revealed by 4D Scanning Transmission Electron Microscopy 四维扫描透射电镜研究氮化镓中位错周围相干去沟道电子的各向异性重分布。

IF 2 3区工程技术 Q2 MICROSCOPY

Ultramicroscopy

Pub Date : 2026-04-01 Epub Date: 2026-02-02 DOI: 10.1016/j.ultramic.2026.114327

Corrado Bongiorno , Antonio M. Mio , Gianfranco Sfuncia , Mario S. Alessandrino , Salvatore Adamo , Cettina Bottari , Corrado R. Spinella , Giuseppe Nicotra

In this study, we employ 4D Scanning Transmission Electron Microscopy (4D-STEM) to investigate the relationship between image contrast, convergent beam electron diffraction (CBED) patterns, and local lattice distortions near dislocations in 2H-GaN. Our findings reveal a pronounced anisotropic spreading of the CBED pattern, which correlates with the local distortion of atomic channels and, therefore, with the direction of the Burgers vector of the dislocation. This behavior is a consequence of electron beam channelling perturbation caused by low-curvature channels. Thanks to the 4D-STEM capabilities, an accurate analysis of the localized CBED patterns around a screw dislocation reveals that the characteristic two-lines contrast observed experimentally arise mainly from an angular redistribution of the coherent diffracted electrons reaching the annular detector. The enlargement of the diffraction pattern develops in opposite directions on the two side of the dislocation because reproduces the local bending of the channels. By exploiting this directional de-channeling, we demonstrate the ability to determine both the Burgers vector and therefore the character of dislocations in a well-aligned zone axis configuration. These results highlight the potential of 4D-STEM as a powerful tool for atomic-scale defect characterization in semiconducting materials.

在这项研究中，我们利用4D扫描透射电子显微镜（4D- stem）研究了2H-GaN中图像对比度、会聚束电子衍射（CBED）模式和位错附近局部晶格畸变之间的关系。我们的发现揭示了CBED模式明显的各向异性扩散，这与原子通道的局部畸变有关，因此与位错的Burgers矢量方向有关。这种行为是由低曲率通道引起的电子束通道扰动的结果。由于4D-STEM的能力，对螺旋位错周围的局部CBED模式的精确分析表明，实验观察到的特征双线对比主要来自于到达环形探测器的相干衍射电子的角度再分布。由于再现了通道的局部弯曲，衍射图样的扩大在位错的两侧沿相反的方向发展。通过利用这种定向去通道，我们展示了确定Burgers矢量的能力，从而确定了在对齐良好的层轴配置中的位错特征。这些结果突出了4D-STEM作为半导体材料中原子尺度缺陷表征的强大工具的潜力。

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引用次数: 0

Room-temperature focused ion beam preparation of sensitive organic-inorganic hybrid perovskites 室温聚焦离子束制备敏感有机-无机杂化钙钛矿。

IF 2 3区工程技术 Q2 MICROSCOPY

Ultramicroscopy

Pub Date : 2026-04-01 Epub Date: 2026-02-02 DOI: 10.1016/j.ultramic.2026.114325

Yu Chen , Yuan Lu , Xiangchen Hu , Yi Chen , Qixi Mi , Yi Yu

Radiation damage is problematic in focused ion beam (FIB) preparation of transmission electron microscopy (TEM) specimens, especially for extremely beam-sensitive materials such as organic-inorganic hybrid halide perovskites (OIHPs), where ion beam induced structural damage substantially hinders research on microstructure. While cryogenic FIB (cryo-FIB) can effectively preserve specimens’ crystallinity, the operational complexity and high cost of cryo-FIB, as well as the low-temperature phase transitions of perovskites, significantly limit its application. Here, we demonstrate a systematically optimized room-temperature preparation protocol for OIHPs to preserve its structure. Through systematic optimization of FIB parameters (acceleration voltage, beam current, and milling angle) and concurrent consideration of electron irradiation during FIB processing in the dual-beam FIB system, the electron irradiation induced intragranular cracking and lamella bending in OIHPs were effectively suppressed. This enables the successful preparation of large-area, orientation-specific high-quality lamella with great crystallinity and uniformity, and without phase transition, from bulk OIHP samples. The sharp electron diffraction spots and low-dose aberration-corrected high-resolution TEM images validated the artifact-free TEM specimens.

在聚焦离子束（FIB）制备透射电子显微镜（TEM）样品时，辐射损伤是一个问题，特别是对于极端光束敏感的材料，如有机-无机杂化卤化物钙钛矿（OIHPs），离子束引起的结构损伤严重阻碍了微观结构的研究。低温FIB （cryo-FIB）虽然可以有效地保持样品的结晶度，但其操作的复杂性和高昂的成本，以及钙钛矿的低温相变，极大地限制了其应用。在这里，我们展示了一个系统优化的室温制备方案，以保持oihp的结构。在双束FIB系统中，通过对FIB参数（加速电压、束流、铣削角）的系统优化，并在FIB加工过程中同时考虑电子辐照，有效地抑制了电子辐照引起的oihp晶内开裂和片层弯曲。这使得从大块OIHP样品中成功制备具有高结晶度和均匀性且无相变的大面积、定向高质量片层成为可能。清晰的电子衍射斑点和低剂量像差校正的高分辨率TEM图像验证了无伪影的TEM样品。

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引用次数: 0

Open gas-cell transmission electron microscopy at 0.5 Å information limit 打开气细胞透射电子显微镜在0.5 Å信息限制

IF 2 3区工程技术 Q2 MICROSCOPY

Ultramicroscopy

Pub Date : 2026-04-01 Epub Date: 2026-02-02 DOI: 10.1016/j.ultramic.2026.114328

Idan Biran , Frederik Dam , Sophie Kargo Kaptain , Ruben Bueno Villoro , Maarten Wirix , Christian Kisielowski , Peter C.K. Vesborg , Jakob Kibsgaard , Thomas Bligaard , Christian D. Damsgaard , Joerg R. Jinschek , Stig Helveg

Transmission electron microscopy (TEM) has reached ∼ 0.5 Å information limit in high vacuum conditions, enabling single-atom sensitive imaging of nanomaterials. Extending this capability to gaseous environments would allow for similar visualizations of nanomaterial dynamics under chemically reactive conditions. Here, we examine a new TEM system that obtains 0.5 Å information limit at pressures up to 1 mbar, demonstrated using nanocrystalline Au immersed in N₂. The system features an open gas-cell with a four-stage differential pumping system, a 5^th order aberration corrector for broad-beam TEM, a monochromatized electron beam, an ultra-stable microscope platform, Nelsonian low electron dose-rate illumination, and direct electron detection. Young’s fringe experiments and exit wave phase imaging confirm the atomic resolution and indicate a possible location-dependent vibrational blur at a surface termination. Thus, this platform advances in situ and operando TEM studies of gas-surface interactions in diverse fields, including catalysis, corrosion, and crystal growth.

透射电子显微镜（TEM）在高真空条件下达到了~ 0.5 Å信息限制，使纳米材料的单原子敏感成像成为可能。将这种能力扩展到气体环境将允许在化学反应条件下对纳米材料动力学进行类似的可视化。在这里，我们研究了一种新的TEM系统，在高达1mbar的压力下获得0.5 Å信息限制，演示使用浸入N2的纳米晶Au。该系统具有一个开放的气池，带有四级差分泵系统，宽光束TEM的五阶像差校正器，单色电子束，超稳定的显微镜平台，Nelsonian低电子剂量率照明和直接电子检测。杨的条纹实验和出口波相位成像证实了原子分辨率，并指出在表面末端可能存在与位置相关的振动模糊。因此，该平台推进了不同领域气体表面相互作用的原位和操作TEM研究，包括催化、腐蚀和晶体生长。

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引用次数: 0

The effect of pattern quality on measurements of stress heterogeneity and geometrically necessary dislocation density by high-angular resolution electron backscatter diffraction 图案质量对高角分辨电子背散射衍射测量应力非均匀性和几何必要位错密度的影响

IF 2 3区工程技术 Q2 MICROSCOPY

Ultramicroscopy

Pub Date : 2026-04-01 Epub Date: 2026-02-07 DOI: 10.1016/j.ultramic.2026.114330

Harison S. Wiesman , David Wallis

We examine the effect of pattern quality on the output of high-angular resolution electron backscatter diffraction (HR-EBSD) analyses. Band contrast, as a proxy for pattern quality, was varied by adjusting the number of frames averaged per electron backscatter pattern during data collection. The same region in a deformed sample of the mineral olivine was mapped six times varying the number of frames averaged between 1 and 30 between each map. Each data set was analyzed with HR-EBSD, producing maps of intragranular stress heterogeneity and geometrically necessary dislocation (GND) density. As the number of frames averaged increased, the noise in stress and GND density decreased, revealing more substructure in the mapped region. The worst pixels, with low band contrast, are the most improved by increased frame averaging, whereas those with high band contrast are largely unaffected. Additionally, the probability distribution of stresses narrows as high-stress noise is reduced with increased pattern quality, which also affects estimates of dislocation density from statistical analysis of the stress distributions. As regions with high stress and/or high GND density are typically of interest in HR-EBSD maps and are often associated with low band contrast, frame averaging may be used as a tool to improve the quality of these analyses. Most importantly, however, is that comparisons are made between HR-EBSD datasets with similar mean band contrast in future studies to ensure that observed differences are microstructural in origin and not an artefact of data collection.

我们研究了图案质量对高角分辨率电子背散射衍射（HR-EBSD）分析输出的影响。波段对比度，作为图案质量的代理，通过调整数据收集期间每个电子背散射图案的平均帧数来改变。在一个变形的橄榄石矿物样本中，同一区域被绘制了六次，每次绘制的帧数平均在1到30之间。每个数据集都使用HR-EBSD进行分析，生成晶内应力非均质性和几何必要位错（GND）密度图。随着平均帧数的增加，应力噪声和GND密度降低，映射区域显示出更多的子结构。低波段对比度的最差像素，通过增加帧平均可以得到最大程度的改善，而那些高波段对比度的像素则基本不受影响。此外，随着图案质量的提高，高应力噪声降低，应力的概率分布也会缩小，这也会影响从应力分布的统计分析中估计的位错密度。由于高应力和/或高GND密度的区域通常是HR-EBSD图中感兴趣的区域，并且通常与低频带对比度相关，因此可以使用帧平均作为提高这些分析质量的工具。然而，最重要的是，在未来的研究中，对具有相似平均波段对比度的HR-EBSD数据集进行比较，以确保观察到的差异是微观结构的起源，而不是数据收集的人工产物。

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引用次数: 0

A universal FIB approach for contamination- and damage-free plan-view TEM lamellae using NaCl sacrificial layers 使用NaCl牺牲层对无污染和无损伤的平面透射电镜片层进行FIB分析

IF 2 3区工程技术 Q2 MICROSCOPY

Ultramicroscopy

Pub Date : 2026-04-01 Epub Date: 2026-01-13 DOI: 10.1016/j.ultramic.2026.114319

Chen Liu , Jingkai Xu , Qingxiao Wang , Tianchao Guo , Maolin Chen , Dongxing Zheng , Husam N. Alshareef , Xixiang Zhang

The preparation of high-quality plan-view transmission electron microscopy (TEM) lamellae is essential for investigating the in-plane properties of thin films. However, current focused ion beam (FIB) techniques are limited by ion-beam damage, surface contamination, and time-consuming workflows. Here, we introduce NaCl microcrystals as a sacrificial protective layer, which effectively shields the surface from ion irradiation and can be completely removed by simple dissolution in water, leaving a pristine surface. Building on this, we established a universal and streamlined FIB workflow for plan-view lamellae fabrication from thin films that eliminates the need for conventional Pt/C deposition and avoids custom hardware, relying solely on standard commercial components. Using a classic metal multilayer and an ultrathin epitaxial oxide film as representative model systems, we demonstrate that the prepared plan-view lamellae exhibit large uniform areas, preserved film structures, and contamination-free surfaces, enabling reliable surface-sensitive TEM analyses. This time-efficient and user-friendly approach offers a powerful solution for the contamination- and damage-free preparation of plan-view TEM lamellae across diverse thin-film systems, paving the way for in-depth investigations of their in-plane properties.

制备高质量的平面透射电子显微镜（TEM）薄片对于研究薄膜的平面内性质至关重要。然而，目前的聚焦离子束（FIB）技术受到离子束损伤、表面污染和耗时工作流程的限制。在这里，我们引入了NaCl微晶体作为牺牲保护层，它可以有效地保护表面免受离子照射，并且可以通过简单的溶解在水中完全去除，留下原始的表面。在此基础上，我们建立了一个通用的、简化的FIB工作流程，用于从薄膜中制造平面视图片层，消除了传统Pt/C沉积的需要，避免了定制硬件，完全依赖于标准的商业组件。使用经典的金属多层和超薄外延氧化膜作为代表性模型系统，我们证明了制备的平面视图片层具有大的均匀区域，保留了薄膜结构和无污染表面，从而实现了可靠的表面敏感TEM分析。这种时间效率高、用户友好的方法为跨不同薄膜系统的平面视图透射电镜片的无污染和无损伤制备提供了强有力的解决方案，为深入研究其平面内特性铺平了道路。

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引用次数: 0

Fabrication and characterization of boron-terminated tetravacancies in monolayer hBN using STEM, EELS and electron ptychography 利用STEM、EELS和电子型图技术在单层hBN中制备和表征硼端四空位

IF 2 3区工程技术 Q2 MICROSCOPY

Ultramicroscopy

Pub Date : 2026-04-01 Epub Date: 2025-12-26 DOI: 10.1016/j.ultramic.2025.114305

Dana O. Byrne , Stephanie M. Ribet , Demie Kepaptsoglou , Quentin M. Ramasse , Colin Ophus , Frances I. Allen

Tetravacancies in monolayer hexagonal boron nitride (hBN) with consistent edge termination (boron or nitrogen) form triangular nanopores with electrostatic potentials that can be leveraged for applications such as selective ion transport and neuromorphic computing. In order to quantitatively predict the properties of these structures, an atomic-level understanding of their local electronic and chemical environments is required. Moreover, robust methods for their precision manufacture are needed. Here we use electron irradiation in a scanning transmission electron microscope (STEM) at a high dose rate to drive the formation of boron-terminated tetravacancies in monolayer hBN. Characterization of the defects is achieved using aberration-corrected STEM, monochromated electron energy-loss spectroscopy (EELS), and electron ptychography. Z-contrast in STEM and chemical fingerprinting by core-loss EELS enable identification of the edge terminations, while electron ptychography gives insight into structural relaxation of the tetravacancies and provides evidence of enhanced electron density around the defect perimeters indicative of bonding effects.

具有一致边缘终止（硼或氮）的单层六方氮化硼（hBN）中的四空位形成具有静电电位的三角形纳米孔，可用于选择性离子传输和神经形态计算等应用。为了定量地预测这些结构的性质，需要对它们的局部电子和化学环境有一个原子水平的了解。此外，还需要可靠的精密制造方法。在这里，我们在扫描透射电子显微镜（STEM）中使用高剂量率的电子照射来驱动单层hBN中硼端四空位的形成。缺陷的表征是使用像差校正的STEM，单色电子能量损失谱（EELS）和电子型图实现的。STEM中的z对比和核心损耗EELS的化学指纹识别可以识别边缘末端，而电子型图可以深入了解四空位的结构松弛，并提供缺陷周围电子密度增强的证据，表明键合效应。

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引用次数: 0

A spatial-spectral feature fusion attention residual network for automated bacterial classification via atomic force microscopy 基于原子力显微镜的空间-光谱特征融合注意残差网络细菌自动分类。

IF 2 3区工程技术 Q2 MICROSCOPY

Ultramicroscopy

Pub Date : 2026-04-01 Epub Date: 2026-02-02 DOI: 10.1016/j.ultramic.2026.114323

Hao Luan , Yinan Wu , Yifan Bai , Yuting Wu , He Chen

Bacterial classification commonly relies on the specialized knowledge and the laborious procedure. To address the issue, a spatial–spectral feature fusion attention residual network (SFFA-Net) is designed to achieve automated bacterial classification in this paper. Specifically, a bacterial image dataset generated by the atomic force microscopy is first established for high-precision network training. Subsequently, the SFFA-Net is built via designing a residual network to perform feature extraction and encode the discriminative representations of the specimens. On this basis, the twin-branch feature extraction module is designed to extract two-dimensional and three-dimensional features, respectively. Subsequently, the improved squeeze and excitation attention blocks are introduced to focus on the key areas of the feature maps to improve the classification accuracy. Besides, an auxiliary classifier is designed to further enhance the model performance by bringing in additional supervision signals. The superiority of the proposed method is verified through comparative experiments.

细菌分类通常依赖于专业知识和繁琐的程序。为了解决这一问题，本文设计了一个空间-光谱特征融合注意残差网络（SFFA-Net）来实现细菌的自动分类。具体而言，首先建立了由原子力显微镜生成的细菌图像数据集，用于高精度网络训练。随后，通过设计残差网络构建SFFA-Net，进行特征提取，并对样本的判别表示进行编码。在此基础上，设计双分支特征提取模块，分别提取二维和三维特征。随后，引入改进的挤压和激励注意块，聚焦特征图的关键区域，提高分类精度。此外，设计了一个辅助分类器，通过引入额外的监督信号来进一步提高模型的性能。通过对比实验验证了该方法的优越性。

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引用次数: 0