单词 | micella |
释义 | micellan. Now rare. 1. a. Biology and Biochemistry. Originally (following the terminology of C. Nägeli): a submicroscopic particle consisting of a number of molecules surrounded by a layer of water and forming part of an organized structure such as a starch granule or cell wall. Now historical. ΘΚΠ the world > life > biology > substance > [noun] > other types of fibroin1861 micella1881 digest1918 bone-seeker1947 target tissue1960 biomineral1972 1881 Encycl. Brit. XII. 12/1 Nägeli concluded that these structures [sc. plant cell-walls] were made up of crystalline doubly refracting particles or micellæ, each consisting of numerous atoms and impermeable by water, although each of the micellæ is surrounded by a thinner or thicker layer of water. 1882 S. H. Vines tr. J. von Sachs Text-bk. Bot. (ed. 2) ii. i. 664 (note) It will be noted that the Atom, Molecule, and Pleon are chemical ideas, whereas the Micella and Micellar Aggregate are purely physical. 1894 W. Somerville & H. M. Ward tr. R. Hartig Text-bk. Dis. Trees iv. 287 In a living condition the micellæ of the protoplasm are surrounded by water. 1908 W. R. Fisher Schlich's Man. Forestry (ed. 2) V. 67 Consider the cell wall as composed of mycellae; when it is absolutely dry, adjoining mycellae..have no spaces between them. 1918 Biochem. Jrnl. 12 351 He [sc. Nägeli] supposed that gels consisted of molecular complexes or micellae with crystalline properties, separated by skins of water and forming meshes (or interstices) in which the water was contained by molecular attraction. 1947 Ann. N.Y. Acad. Sci. 47 783 Under the influence of Nägeli's general theory of biological submicroscopical units, these hypothetical particles in the muscle have been called micellae. b. Chiefly Botany = micelle n. 2. ΚΠ 1929 Amer. Naturalist 63 421 The distribution of the micellae in a mass of cellulose has been compared to that of bricks in a wall. 1931 K. H. Meyer in New Phytologist 30 9 In the case of substances of the cellulose and chitin type it can be shown that complex chains of main valencies (bundles) are combined to crystallites which may be termed micellae. 1965 P. Bell & D. Coombe tr. Strasburger's Textbk. Bot. (new ed.) i. i. 53 (caption) Diagram illustrating the micellar structure of cell walls... Linear macromolecules are grouped to form micellae or crystallites. 2. Chemistry and Biochemistry. = micelle n. 1. ΘΚΠ the world > matter > chemistry > physical chemistry > colloid > [noun] > micelle micelle1901 micella1926 1926 H. S. Hatfield tr. H. Freundlich Colloid & Capillary Chem. 371 For the micella of the gold sol we must take into account the fact that foreign substances enter into its structure, which largely determine its chemical properties. 1935 C. J. Wiggers Physiol. Health & Dis. li. 802 Colloids in a sol state exert a small osmotic pressure, but this varies in uncontrollable fashion owing to the fact that colloidal molecules or aggregates called micellae vary considerably. 1999 European Jrnl. Biochem. 265 221 Nonspecific oligomers of cytotoxin up to the hexamer, induced by oxidative crosslinking or detergent micellae, were based on intermolecular disulfide bridges. This is a new entry (OED Third Edition, December 2001; most recently modified version published online March 2022). < n.1881 |
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