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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.
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]
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).
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 ...
Cross section of celery stalk, showing vascular bundles, which include both phloem and xylem Detail of the vasculature of a bramble leaf Translocation in vascular plants. Vascular tissue is a complex conducting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem ...
Non-vascular plants , with their different evolutionary background, tend to have separate terminology. Although plant morphology (the external form) is integrated with plant anatomy (the internal form), the former became the basis of the taxonomic description of plants that exists today, due to the few tools required to observe. [2] [3]
The presence of vessels in xylem has been considered to be one of the key innovations that led to the success of the flowering plants. It was once thought that vessel elements were an evolutionary innovation of flowering plants, but their absence from some basal angiosperms and their presence in some members of the Gnetales suggest that this hypothesis must be re-examined; vessel elements in ...
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 ...