paracrystal
(ˈpærəkrɪstəl)
[f. para-1 + crystal n. and a.]
An assemblage of particles that has some degree of order but is not a true crystal.
| 1933 Trans. Faraday Soc. XXIX. 1019 On addition of acetone to a cold saturated solution in acetic ester of phytosterin valerate the latter..separates out as a paracrystal. 1953 S. E. Luria Gen. Virol. v. 94 In the needles, which should more correctly be called ‘paracrystals’, the individual rods are oriented sidewise with great regularity. 1956 Nature 10 Mar. 473/1 The great regularity of plant viruses is shown even more strikingly by their ability to form crystals (or paracrystals) which give good X-ray photographs. 1970 Jrnl. Biochem. (Tokyo) LXVIII. 885/1 Paracrystals are formed by side-by-side association of F-actin particles in the presence of an excess amount of MgCl2. |
Hence paraˈcrystalline a., of the nature of a paracrystal; ˌparacrystaˈllinity.
| 1933 Trans. Faraday Soc. XXIX. 1027 An especially strong paracrystallinity is to be ascribed to the paracrystalline sperm heads of Sepia officinalis. 1950 W. J. Moore Physical Chem. xiv. 408 The compound ethyl⁓anisol-paraäminocinnamate passes through three distinct paracrystalline phases between 83° and 139°. 1964 G. H. Haggis et al. Introd. Molecular Biol. xi. 283 The haemoglobin in cells which had taken up the sickle shape was in para-crystalline, or tactoid form. 1974 Amer. Jrnl. Anat. CXXXIX. 135 Paracrystalline aggregates of microtubules were observed by electron microscopy in some cells of the anterior pituitary glands from ten untreated chinchillas. |