CHARACTERIZATION OF FROZEN-HYDRATED SPECIMENS BY EELS

这项测量水的技术是我们去年发明的。 冰冻水化的薄壁生物样品的分布 电子能量损失谱(EELS)得到了进一步发展。 这种方法依赖于量化化合价的细微变化。 电子激发光谱作为组成的函数。它涉及到 确定单次散射强度，计算振子 优势，并将多重最小二乘拟合应用于参考 水和有机成分的光谱。这项技术现在已经被 扩展到光谱成像，以便二维水分分布 可以从水合的冰冻切片中获得。的自动处理 光谱图像数据已经实现，减少 计算时间正在调查中。这项技术的应用 (例如，分析快速冷冻的肝细胞的水分含量和 冷冻保存的胚胎)正在进行中。

The technique originated by us last year for measuring water distributions in thin, frozen-hydrated biological specimens by means of electron energy loss spectroscopy (EELS) has been further developed. This approach depends on quantifying subtle changes in the valence electron excitation spectrum as a function of composition. It involves determining the single-scattering intensities, calculating oscillator strengths, and applying multiple least squares fitting to reference spectra for water and organic constituents. The technique has now been extended to spectrum-imaging, so that two-dimensional water distributions can be obtained from hydrated cryosections. Automated processing of the spectrum-image data has been implemented, and ways of reducing the computation time are being investigated. Applications of the technique (e.g., analyzing the water content of rapidly-frozen hepatocytes and cryopreserved embryos) are in progress.