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Polymetallic nodules, also called manganese nodules, are mineral concretions on the sea bottom formed of concentric layers of iron and manganese hydroxides around a core. As nodules can be found in vast quantities, and contain valuable metals, deposits have been identified as a potential economic interest. [ 1 ]
Manganese is a silvery-gray metal that resembles iron. It is hard and very brittle, difficult to fuse, but easy to oxidize. [11] Manganese and its common ions are paramagnetic. [12] Manganese tarnishes slowly in air and oxidizes ("rusts") like iron in water containing dissolved oxygen. [13]
Benign liver tumors generally develop on normal or fatty liver, are single or multiple (generally paucilocular), have distinct delineation, with increased echogenity (hemangiomas, benign focal nodular hyperplasia) or absent, with posterior acoustic enhancement effect (cysts), have distinct delineation (hydatid cyst), lack of vascularization or show a characteristic circulatory pattern ...
Nodular regenerative hyperplasia (NRH) is a rare liver disease, characterised by the growth of nodules within the liver, resulting in liver hyperplasia.While in many cases it is asymptomatic and thus goes undetected – or is only discovered incidentally while investigating some other medical condition – in some people it results in non-cirrhotic portal hypertension (NCPH).
Manganese may affect liver function, but the threshold of acute toxicity is very high. On the other hand, more than 95 percent of manganese is eliminated by biliary excretion. Any existing liver damage may slow this process, increasing its concentration in blood plasma. [17]
Manganese is also important in photosynthetic oxygen evolution in chloroplasts in plants. The oxygen-evolving complex (OEC) is a part of photosystem II contained in the thylakoid membranes of chloroplasts; it is responsible for the terminal photooxidation of water during the light reactions of photosynthesis , and has a metalloenzyme core ...
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Nodule is also used for widely scattered concretionary lumps of manganese, cobalt, iron, and nickel found on the floors of the world's oceans. This is especially true of manganese nodules. Manganese and phosphorite nodules form on the seafloor and are syndepositional in origin. Thus, technically speaking, they are concretions instead of nodules ...