Image analysis in the electron microscopy of cellulose protofibrils II. Digital correlation methods
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Electron micrographs of parallel arrays of negatively stained ramie cellulose protofibrils were analyzed using the two-dimensional digital autocorrelation function (ACF). The method is based upon the statistical analysis of images in real space. The ACF shows strong parallel streaks of high correlation, and the lateral distance between adjacent streaks allows the mean interfibrillar distance to be estimated as 3.7 nm. The intensity profile along the streaks shows a weak modulation with peaks occurring at integral multiples of 3 or 6 nm. These results provide direct evidence that there is a regular axial texture in the protofibrils, and corroborate the conclusions previously drawn from optical diffraction analysis. Using the difference vectors found in the ACF it has been possible to reduce the picture noise level by linear integration, thereby obtaining an enhanced image. A preliminary result obtained in this way suggests that the projected protofibril morphology associated with the observed axial periodicity is a ribbon-like zigzag structure. Possible applications of the method for future work are discussed.
Key wordsImage analysis cellulose protofibrils electron microscopy digital autocorrelation function
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- 1.Tsuji M, Manley RStJ (1984) Coll & Polym Sci 262:236Google Scholar
- 2.Hosemann R, Bagchi SN (1962) Direct Analysis of Diffraction by Matter North-Holland, AmsterdamGoogle Scholar
- 3.Vainshtein BK (1966) Diffraction of X-rays by Chain Molecules Elsevier, AmsterdamGoogle Scholar
- 6.Frank J (1980) (ed) Hawkes PW, Computer Processing of Electron Microscope Images, Springer-Verlag, New York, Chapt 5Google Scholar
- 7.Scherzer O (1949) J Appl Phys 20:20Google Scholar
- 8.Frank J, Shimkin B, Dowse H (1981) Ultramicrosc 6:343Google Scholar
- 10.Nathan R (1971) (eds) Barer R, Cosslett VE, Advances in Optical and Electron Microscopy, Vol 4, Academic Press, London and New York, p 180Google Scholar
- 11.Tsuji M, Roy SK, Manley RStJ (1985) J Polym Sci, Polym Phys Ed 23:1127Google Scholar
- 12.Frank J (1974) J Phys D, Appl Phys 7:L75Google Scholar
- 13.Frank J (1982) Optik 63:67Google Scholar