A longstanding limitation of imaging with serial block-face scanning electron microscopy is specimen surface charging. This charging is largely due to the difficulties in making biological specimens and the resins in which they are embedded sufficiently conductive. Local accumulation of charge on the specimen surface can result in poor image quality and distortions. Even minor charging can lead to misalignments between sequential images of the block-face due to image jitter. Typically, variable-pressure SEM is used to reduce specimen charging, but this results in a significant reduction to spatial resolution, signal-to-noise ratio and overall image quality due to the large number of gas molecules present in the entire specimen chamber.
In collaboration with Carl Zeiss Microscopy (www.zeiss.com), NCMIR researchers developed a new technology to solve this problem, greatly improving the performance of serial blockface scanning EM (SBEM) using the Gatan 3View. This technology allows for the focused and highly synchronized delivery of nitrogen gas to the sample blockface during the imaging cycle to eliminate charging, greatly extending the utility of the volume imaging technique for even the most-charge-prone samples.
Serial Box 12-2017
At 3:52 p.m. on April 11, 2017, an employee was on the operator's station atop t he Weiler E1250A material transfer vehicle, serial number 1063, to push a Wester n dump truck, model 4964F, loaded with asphalt. The employee was on the roof of a building guiding a coworker who was laying a second asphalt coating down on a 2-lane road. The coworker had the dump truck's bed raised to it's highest leve l of approximately 21 feet. The employee signaled to the coworker to lower the bed as it passed under some overhead power lines; however, the upper portion of the bed had already hit them. The power lines were pulled forward approximately 15-18 feet and broke. The employee was electrocuted when the primary power lin e fell on top of the employee. 2ff7e9595c
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