von Zglinicki T
Institute of Pathology, Charite, Berlin, Germany.
J Microsc. 1991 Jan;161(Pt 1):149-58. doi: 10.1111/j.1365-2818.1991.tb03079.x.
There are three techniques to measure local water fractions in the cryomicroscope. First, water content may be measured by a direct analysis of oxygen in bulk samples using a windowless detector. Secondly, mass thickness may be estimated in frozen-hydrated, then frozen-dried sections. This technique offers unrivalled spatial resolution, especially if the radiation dose in the frozen-hydrated state is kept low by the use of electron scattering techniques instead of an X-ray microanalytical background determination. External water content standards can be used instead of frozen-hydrated sections and the whole analysis can even be performed exclusively on frozen-dried sections at room temperature. Thirdly, local water fractions can be evaluated from X-ray microanalytical measurements of element concentrations per mass in the frozen-hydrated and frozen-dried state. Corrections necessary for the other techniques cancel out. However, the high radiation dose required for a fully quantitative analysis excludes the use of these methods in thin or ultrathin sections.
在低温显微镜中，有三种测量局部水含量的技术。首先，可以使用无窗口探测器通过对大量样品中的氧进行直接分析来测量含水量。其次，可以在冷冻水合、然后冷冻干燥的切片中估计质量厚度。这种技术提供了无与伦比的空间分辨率，特别是如果通过使用电子散射技术而不是X射线微分析背景测定来保持冷冻水合状态下的辐射剂量较低。可以使用外部水含量标准代替冷冻水合切片，甚至可以在室温下仅对冷冻干燥的切片进行整个分析。第三，可以根据冷冻水合和冷冻干燥状态下每质量元素浓度的X射线微分析测量来评估局部水含量。其他技术所需的校正相互抵消。然而，完全定量分析所需的高辐射剂量排除了在薄切片或超薄切片中使用这些方法。
