High pressure living organisms

The different ratios of 52/53 produced by cycloadditions performed at atmospheric and high pressure, and the forma tion of the unusual trans adducts 53, have been explained by the facts that (i) Diels-Alder reactions under atmospheric pressure are thermodynamically controlled, and (ii) the anti-endo adducts 52 are converted into the short-lived syn-endo adducts 54 which tautomerize (via a dienol or its aluminum complexes) to 53. The formation of trans compounds 53 by induced post-cycloaddition isomerization makes the method more flexible and therefore more useful in organic synthesis. 

Piezophile An organism adapted to living in high-pressure environments, such as hydro-thermal vents... 

Osmotic pressure creates some critical problems for living organisms. Cells typically contain fairly high concentrations of solutes, that is, small organic molecules and ionic salts, as well as lower concentrations of macromolecules. Consequently, cells may gain or lose water because of the concentration of solute in their environment. If cells are placed in an isotonic solution (i.e., the concentration of solute and water is the same on both sides of the selectively permeable plasma membrane) there is no net movement of water in either direction across the membrane (Figure 3.14). For example, red blood cells are isotonic to... 

The very extensive use and high consumption of chlorinated hydrocarbons in plant protection resulted in a contamination of the whole environment. DDT (l,l,l-trichloro-2,2-bis(p-chlorophenyl)ethane) is very dangerous on account of its toxic effects on all the living organisms. It is remarkably resistant, and its residence time in the atmosphere is considered to be several decades. Due to its method of its application, the atmosphere serves as its largest reservoir. Its vapour pressure at 273 K is 2 x 10 Pa, which represents about 3 fig m. This concentration would correspond to a total amount in the troposphere of roughly 10 t. The other estimate is lower by about one half. From the atmosphere, it is removed only by the rain and the great majority is then transported into the oceans. It is nearly insoluble in sea water but is soluble in fats and thus, it is accumu-... 

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