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Gastrulation is the stage in the early embryonic development of most animals, during which the blastula (a single-layered hollow sphere of cells), or in mammals the blastocyst, is reorganized into a two-layered or three-layered embryo known as the gastrula. [1]
Unit cell of Laves phase with MgZn 2 structure (Mg atoms are green). Laves polyhedron. Laves phases are intermetallic phases that have composition AB 2 and are named for Fritz Laves who first described them.
In birds, the organizer is known as Hensen's node, named after its discoverer Victor Hensen.; In other amniotes, it is known as the primitive node.; In amphibians, it is known as the Spemann-Mangold organizer, named after Hans Spemann and Hilde Mangold, who first identified the organizer in 1924.
The primitive streak is a structure that forms in the early embryo in amniotes. [1] In amphibians, the equivalent structure is the blastopore. [2] During early embryonic development, the embryonic disc becomes oval shaped, and then pear-shaped with the broad end towards the anterior, and the narrower region projected to the posterior.
The cephalic phase of digestion is the stage in which the stomach responds to the mere sight, smell, taste, or thought of food. About 20% of total acid secretion occurs before food enters the stomach.
Phase transitions commonly refer to when a substance transforms between one of the four states of matter to another. At the phase transition point for a substance, for instance the boiling point, the two phases involved - liquid and vapor, have identical free energies and therefore are equally likely to exist.
Donald Fleming and his team recently began their investigation of vibrational bonds, and as they had expected from the results of their experiments in 1989, the BrLBr reaction slowed at high temperatures, now using modern instrumental analysis from photo detachment electron spectroscopy, the vibrational bond was detected but lasted only a few milliseconds. [4]
Metastability is common in physics and chemistry – from an atom (many-body assembly) to statistical ensembles of molecules (viscous fluids, amorphous solids, liquid crystals, minerals, etc.) at molecular levels or as a whole (see Metastable states of matter and grain piles below). The abundance of states is more prevalent as the systems grow ...