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In organic chemistry, organocatalysis is a form of catalysis in which the rate of a chemical reaction is increased by an organic catalyst. This "organocatalyst" consists of carbon , hydrogen , sulfur and other nonmetal elements found in organic compounds.
Hydrogen-bond catalysis is a type of organocatalysis that relies on use of hydrogen bonding interactions to accelerate and control organic reactions. In biological systems, hydrogen bonding plays a key role in many enzymatic reactions, both in orienting the substrate molecules and lowering barriers to reaction. [ 1 ]
Corrections of arrows of external iliac artery. Add muscular branches from deep femoral artery (after deleted an inexistent medial artery). 17:10, 22 June 2020: 550 × 830 (1.18 MB) Jmarchn: Add label for gastroduodenal artery. Better draw for epigastric arteries. Added temporal arteries (not labeled). 11:01, 21 June 2020: 550 × 830 (1.19 MB ...
Inside this layer is the tunica media, which is made up of smooth muscle cells, elastic tissue (also called connective tissue proper) and collagen fibres. [3] The innermost layer, which is in direct contact with the flow of blood, is the tunica intima. The elastic tissue allows the artery to bend and fit through places in the body.
Schreiner's thiourea, N,N'-bis3,5-bis(trifluormethyl)phenyl thiourea, combines all structural features for double H-bonding mediated organocatalysis: electron-poor; rigid structure; non-coordinating, electron withdrawing substituents in 3,4, and/or 5 position of a phenyl ring; the 3,5-bis(trifluoromethyl)phenyl-group is the preferred substituent
English: Microscopic anatomy of an artery. The outermost layer is known as tunica adventitia, and is composed of connective tissue made up of collagen fibers. Inside this layer is the tunica media, or media, which is made up of smooth muscle cells and elastic tissue (also called connective tissue proper).
The tunica media is made up of smooth muscle cells, elastic tissue and collagen.It lies between the tunica intima on the inside and the tunica externa on the outside.. The middle coat (tunica media) is distinguished from the inner (tunica intima) by its color and by the transverse arrangement of its fibers.
The tunica media may (especially in arteries) be rich in vascular smooth muscle, which controls the caliber of the vessel. Veins do not have the external elastic lamina, but only an internal one. The tunica media is thicker in the arteries rather than the veins. The outer layer is the tunica adventitia and the thickest layer in veins. It is ...