跟讀練習: Introduction to focused ion beam scanning electron microscopy (FIB-SEM) - 通過影片學習英語口語
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29 句
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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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背景與背景資訊
在此影片中，演講者Kedar Narayan是國家癌症研究所和弗雷德里克國家癌症研究實驗室分子顯微鏡中心的組長。他介紹了一種前沿的電子顯微鏡技術，Focused Ion Beam Scanning Electron Microscopy（FIB-SEM），並探討了3D成像與生物樣品的高解析度成像的重要性。該技術能夠幫助科學家們更清晰地理解細胞結構，併為細胞生物學研究提供重要資訊。
日常交流的五個關鍵短語
- “高解析度成像” - 強調影像的重要性和清晰度。
- “細胞樣品” - 關注於生物學研究中的重要組成部分。
- “嵌入樹脂” - 描述樣品處理過程中的技術步驟。
- “聚焦離子束” - 該技術的核心，介紹其功能和應用。
- “三維重建” - 提高思維方式和解決問題的能力。
逐步跟讀指南
為了解決這個影片的難度，您可以按照以下步驟進行英語影子跟讀練習：
- 準備工作：首先，觀看影片並仔細聆聽演講者的聲音和語調，記下您不懂的單詞或短語。
- 分段理解：將影片內容分為幾個小段，每段理解後再進行跟讀，這樣能夠減輕學習負擔。
- 慢速跟讀：初次跟讀時可以放慢速度，確保準確發音，適時停頓，重複跟隨影片。
- 模仿語調：注意演講者的語音語調、重音和情感表達，努力模仿出相同的效果。
- 錄音回聽：將自己的聲音錄下來，與原影片進行對比，找出發音和表達上的差異。這樣可以幫助您提高英語發音，引導您更好地進行英語口語練習。
通過這種逐步影子跟讀的方式，您不僅能夠提高您的英語口語水平，還能更深入地理解生物學領域的專業知識，發現更多意外的學習樂趣。無論是進行英語影子跟讀還是提高英語口語練習，這都是您提升語言能力的有效途徑。
什麼是跟讀法？
跟讀法 (Shadowing) 是一種有科學依據的語言學習技巧，最初開發用於專業口譯員的培訓，並由多語言者Alexander Arguelles博士普及。這個方法簡單而強大：您在聽英語母語原聲的同時立即大聲重複——就像是一個延遲1-2秒緊跟說話者的影子。與被動聽力或語法練習不同，跟讀法強迫您的大腦和口腔肌肉同時處理並模模擬實的講話模式。研究表明它能顯著提高發音準確性，語調，節奏，連讀，聽力理解和口語流利度——使其成為雅思口語備考和真實英語交流最有效的方法之一。