In geometry, a rhombohedron (also called a rhombic hexahedron or, inaccurately, a rhomboid) is a special case of a parallelepiped in which all six faces are congruent rhombi. It can be used to define the rhombohedral lattice system, a honeycomb with rhombohedral cells. A rhombohedron has two opposite apices at which all face angles are equal; a prolate rhombohedron has this common angle acute, and an oblate rhombohedron has an obtuse angle at these vertices. A cube is a special case of a rhombohedron with all sides square.
HINT:
In this Dossier
- ⭐ Core Definition: Rhombohedral
- Rhombohedral in the context of Hexasulfur
- Rhombohedral in the context of Lipid polymorphism
Rhombohedral in the context of Hexasulfur
Hexasulfur is an inorganic chemical with the chemical formula S6. This allotrope was first prepared by M. R. Engel in 1891 by treating thiosulfate with HCl. Cyclo-S6 is orange-red and forms a rhombohedral crystal. It is called ρ-sulfur, ε-sulfur, Engel's sulfur and Aten's sulfur. Another method of preparation involves the reaction of a polysulfane with sulfur monochloride:
View the full Wikipedia page for HexasulfurRhombohedral in the context of Lipid polymorphism
In biophysics and colloidal chemistry, polymorphism is the ability of lipids to aggregate in a variety of ways, giving rise to structures of different shapes, known as "phases". This can be in the form of spheres of lipid molecules (micelles), pairs of layers that face one another (lamellar phase, observed in biological systems as a lipid bilayer), a tubular arrangement (hexagonal), or various cubic phases (Fd3m, Im3m, Ia3m, Pn3m, and Pm3m being those discovered so far). More complicated aggregations have also been observed, such as rhombohedral, tetragonal and orthorhombic phases.
It forms an important part of current academic research in the fields of membrane biophysics (polymorphism), biochemistry (biological impact) and organic chemistry (synthesis).
View the full Wikipedia page for Lipid polymorphism