跟读练习: Introduction to focused ion beam scanning electron microscopy (FIB-SEM) - 通过YouTube学习英语口语
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Hi, I'm Kedar Narayan, a group leader at the Center for Molecular Microscopy, or CMM, at the National Cancer Institute and Frederick National Laboratory for Cancer Research.
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Hi, I'm Kedar Narayan, a group leader at the Center for Molecular Microscopy, or CMM, at the National Cancer Institute and Frederick National Laboratory for Cancer Research.
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Imaging three-dimensional objects in 2D can be limiting, yielding an incomplete or even a misleading picture.
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And so, at the CMM, we apply cutting-edge electron microscopy, or EM, technologies to image biological samples at the highest possible resolutions.
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My group specializes in the imaging of cells and tissues, that is, larger volumes, in 3D and at nanoscale resolutions.
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In this short video, I'm going to give you a flavor of an imaging technique that we employ in our lab, Focused Ion Beam Scanning Electron Microscopy, or FibSem.
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FibSem, as you will see, is a powerful 3D-EM imaging approach, and in this specific example, we highlight a correlative light microscopy and FibSem, or CLEM-FibSem workflow.
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CLEM-FibSem combines the advantages of light and electron microscopy to generate image reconstructions of targeted features of interest in 3D at resolutions of tens of nanometers.
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So here you have a group of cells of which a subset is fluorescently labeled.
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These cells are grown on a gridded cover slip, a glass substrate on which an alphanumeric code has been etched.
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You can now image these cells either live or after fixation using fluorescence microscopy and also record their x-y coordinates using the gridded pattern.
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Once this step is completed, the cells can be fixed, stained, dehydrated, and resin-embedded in situ.
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When the gridded coverslip is removed, the alphanumeric pattern is transferred to the resin surface in relief, with the cells embedded just beneath that surface.
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In other words, you now know exactly where to find your cells of interest.
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At this point, the cell sample is transferred to the FibSem instrument.
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This Martian looking surface is a close up of the resin where you expect to find your targeted cell.
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The resin embedded cell is protected by a patterned platinum and carbon pad deposited by the focused ion beam or fib, which appears as a rapidly moving blue beam in this movie.
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Remarkably, the same focused ion beam that deposits the platinum and carbon pad can now be used to mill a trench in front of the targeted cell.
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The tightly controlled fib inches towards the cell, ablating away the resin, and eventually reveals the cell itself in cross-section.
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The scanning electron imaging beam, shown here as a yellow band, now rasters over the polished resin surface, and a detector records a high-resolution backscatter electron signal.
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This process is repeated over and over.
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As the fib moves forward and mills away a few more nanometers of the resin, the SEM images the newly exposed section of the cell to generate the next image, and so on and so on.
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Typically, we generate SEM images at 3 to 5 nanometer pixel size in the imaging plane, and 3 to 15 nanometer fib step size, meaning that this automated loop is often repeated several thousand times to generate a highly information-rich ultra-structural image stack covering entire mammalian cells.
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These images are then registered using the notch marks in the pad and converted to an isotropic image volume that allows you to visualize architectural features throughout the bulk of the cell sample.
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The final step is segmentation.
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Here we show the extraction and rendering of the plasma membrane of the cell.
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Fibsem imaging reveals that the membrane extensions in the cell that looked like spaghetti in 2D cross-section are actually veils when visualized in three dimensions.
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FibSem imaging can be applied to a wide variety of systems to confirm observations, generate hypotheses, and most fun of all, make unexpected discoveries in cell biology.
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If you'd like to know more, you can contact me, Kedhar Narayan, at the Center for Molecular Microscopy at the National Cancer Institute and Frederick National Laboratory for Cancer Research.
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You can also visit cmm.nci.nih.gov.
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背景与背景信息
在此视频中，演讲者Kedar Narayan是国家癌症研究所和弗雷德里克国家癌症研究实验室分子显微镜中心的组长。他介绍了一种前沿的电子显微镜技术，Focused Ion Beam Scanning Electron Microscopy（FIB-SEM），并探讨了3D成像与生物样品的高分辨率成像的重要性。该技术能够帮助科学家们更清晰地理解细胞结构，并为细胞生物学研究提供重要信息。
日常交流的五个关键短语
- “高分辨率成像” - 强调图像的重要性和清晰度。
- “细胞样品” - 关注于生物学研究中的重要组成部分。
- “嵌入树脂” - 描述样品处理过程中的技术步骤。
- “聚焦离子束” - 该技术的核心，介绍其功能和应用。
- “三维重建” - 提高思维方式和解决问题的能力。
逐步跟读指南
为了解决这个视频的难度，您可以按照以下步骤进行英语影子跟读练习：
- 准备工作：首先，观看视频并仔细聆听演讲者的声音和语调，记下您不懂的单词或短语。
- 分段理解：将视频内容分为几个小段，每段理解后再进行跟读，这样能够减轻学习负担。
- 慢速跟读：初次跟读时可以放慢速度，确保准确发音，适时停顿，重复跟随视频。
- 模仿语调：注意演讲者的语音语调、重音和情感表达，努力模仿出相同的效果。
- 录音回听：将自己的声音录下来，与原视频进行对比，找出发音和表达上的差异。这样可以帮助您提高英语发音，引导您更好地进行英语口语练习。
通过这种逐步影子跟读的方式，您不仅能够提高您的英语口语水平，还能更深入地理解生物学领域的专业知识，发现更多意外的学习乐趣。无论是进行英语影子跟读还是提高英语口语练习，这都是您提升语言能力的有效途径。
什么是跟读法？
跟读法 (Shadowing) 是一种有科学依据的语言学习技巧，最初开发用于专业口译员的培训，并由多语言者Alexander Arguelles博士普及。这个方法简单而强大：您在听英语母语原声的同时立即大声重复——就像是一个延迟1-2秒紧跟说话者的影子。与被动听力或语法练习不同，跟读法强迫您的大脑和口腔肌肉同时处理并模仿真实的讲话模式。研究表明它能显着提高发音准确性，语调，节奏，连读，听力理解和口语流利度——使其成为雅思口语备考和真实英语交流最有效的方法之一。