HVEM OPERATION AND IMPROVEMENTS

HVEM 操作和改进

• 批准号: 7954577
• 负责人: DAVID BARNARD
• 金额: $ 2.23万
• 依托单位: WADSWORTH CENTER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-02-01 至 2010-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7954577
• 关键词: Americas; Biological; Cells; Computer Retrieval of Information on Scientific Projects Database; Data Collection; Dose; Electrons; Funding; Grant; Housing; Image; Imagery; Institution; Japan; Length; Operative Surgical Procedures; Plastics; Research; Research Personnel; Resolution; Resources; Series; Services; Source; Specimen; Staging; Staining method; Stains; System; Thick; Time; United States National Institutes of Health; Work; abstracting; design; electron tomography; high voltage electron microscopy; irradiation; three dimensional structure; tomography

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. ABSTRACT: The Albany HVEM is the last in the Americas, and one of only two in the world, that is capable of 1000 keV operation and is dedicated to biological studies (the other is in Okazaki, Japan). The HVEM is used primarily for collaborative and service (CS) projects involving the study of the 3-D structure of biological specimens prepared as whole cell mounts or thick plastic sections. Specimens as thick as 5mm can be used when selective stains are employed. Thick specimens can be studied by analysis of stereo-pair images or by electron tomography. The penetrating power of HVEM is ideal for this work because at 60o tilt during a tomographic tilt series, the effective section thickness is twice the 0o thickness, and it is three times thicker at 70o. The instrumental resolution of the HVEM is about 0.5 nm. The HVEM is equipped with a number of specialized specimen stages suitable for tomography, as well as an energy-dispersive x-ray microanalysis system. An in-house designed intensified video-rate CCD TV system can be used to observe the image with very low electron irradiation, for focusing and following the image during tomographic data collection. There are two important benefits of the HVEM for electron tomography of thick sections that are often not appreciated. First, the HVEM has a large focal length and so a large depth of focus. Thus, stained plastic sections as thick as 5000 nm can be tilted to 60 degrees without noticeable blurring at the edges of the image, while some blurring is seen in IVEM images of tilted, 250-nm-thick stained plastic sections. Second, the electron dose with thick stained plastic sections is typically three times lower with the HVEM than with the IVEM, since the latter needs a very small objective aperture to achieve adequate depth of focus for tilted thick sections.

该副本是利用众多研究子项目之一 由NIH/NCRR资助的中心赠款提供的资源。子弹和 调查员（PI）可能已经从其他NIH来源获得了主要资金， 因此，可以在其他清晰的条目中表示。列出的机构是 对于中心，这不一定是调查员的机构。 抽象的： 奥尔巴尼HVEM是美洲的最后一个，也是世界上仅有的两个能够进行1000 keV操作并且致力于生物学研究的两个人（另一种是在日本的冈田）。 HVEM主要用于协作和服务（CS）项目，涉及对整个细胞架或厚塑料部分制备的生物标本的3-D结构的研究。 当使用选择性污渍时，可以使用像5mm厚的样品。 可以通过分析立体对图像或电子断层扫描来研究厚标本。 HVEM的穿透力是这项工作的理想选择，因为在层析成像系列中60o倾斜时，有效的截面厚度是0o厚度的两倍，并且在70o时厚三倍。 HVEM的仪器分辨率约为0.5 nm。 HVEM配备了许多适用于断层扫描的专业试样阶段，以及能量分散的X射线微分析系统。 内部设计的加强视频速率CCD电视系统可用于以非常低的电子辐照观察图像，以在层析成像数据收集过程中进行聚焦和遵循图像。 HVEM对厚部分的电子断层扫描有两个重要的好处，通常不欣赏。 首先，HVEM具有较大的焦距，因此焦点很大。 因此，染色的塑料切片厚至5000 nm可以倾斜至60度，而不会在图像的边缘上显着模糊，而在倾斜的250 nm厚的染色塑料截面的IVEM图像中则看到一些模糊。 其次，HVEM的电子剂量通常比IVEM低三倍，因为后者需要一个很小的客观孔径才能实现足够的焦点深度以使倾斜的厚部分。