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The softening point is the temperature at which a material softens beyond some arbitrary softness. [1] It can be determined, for example, by the Vicat method (ASTM-D1525 or ISO 306), Heat Deflection Test (ASTM-D648) or a ring and ball method (ISO 4625 or ASTM E28-67/E28-99 or ASTM D36 or ASTM D6493 - 11 or JIS K 6863).
Vicat softening temperature or Vicat hardness is the determination of the softening point for materials that have no definite melting point, such as plastics. It is taken as the temperature at which the specimen is penetrated to a depth of 1 mm by a flat-ended needle with a 1 mm 2 circular or square cross-section.
World locations of Vicat. The company was established in 1853 by Joseph Vicat (1821–1902), son of Louis Vicat, who invented artificial cement in 1817. His cement plant was at Genevrey-de-Vif south of Grenoble . It used an argillaceous limestone that Joseph Vicat had established as suitable by chemical analysis. The company expanded in 1922 ...
A funnel (E) contains a sample of soil or leaf litter (D), and a heat source (F), in this case an electric lamp (G), heats the sample. Animals escaping from the desiccation of the sample descend through a filter (C) into a preservative liquid (A) in a receptacle (B).
Expansins characteristically cause wall stress relaxation and irreversible wall extension (). [15] This process is essential for cell enlargement. Expansins are also expressed in ripening fruit where they function in fruit softening, [16] and in grass pollen, [7] where they loosen stigmatic cell walls and aid pollen tube penetration of the stigmain germinating seeds for cell wall disassembly ...
In plant anatomy, there are two main types of sieve elements. Companion cells and sieve cells originate from meristems, which are tissues that actively divide throughout a plant's lifetime. They are similar to the development of xylem, a water conducting tissue in plants whose main function is also transportation in the plant vascular system. [1]
Oat phytochrome absorption spectrum (Devlin, 1969). Phytochromes are a class of photoreceptor proteins found in plants, bacteria and fungi.They respond to light in the red and far-red regions of the visible spectrum and can be classed as either Type I, which are activated by far-red light, or Type II that are activated by red light. [2]
Lacking photosynthetic pigments, leucoplasts are located in non-photosynthetic tissues of plants, such as roots, bulbs and seeds. They may be specialized for bulk storage of starch , lipid or protein and are then known as amyloplasts , elaioplasts , or proteinoplasts (also called aleuroplasts) respectively.