Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The oscillating stability of coral reef seawater pH has been maintained at around physiological pH values over the past 300 years (Pelejero et al., 2005). The stability mechanism of its pH has been interpreted in terms of the buffering dissolution/formation reaction of CaCO(3) as well as the proton consumption/generation reaction in CaCO(3)-saturated water. Here the pH-dependent solubility product [HCO(3)(-)][Ca(2+)] has been derived on the basis of the actual pH-dependent reactions for the atmospheric CO(2)/CO(2 (aq.))/HCO(3)(-)/CO(3)(2-)/Ca(2+)/CaCO(3) system. Overbasic pH peaks appeared between pH approximately 8 and approximately 9.5 during sodium hydroxide titration, as a result of simultaneous CaCO(3) formation and proton generation. The spontaneous and prompt water pH recovery from the acidic to the physiological range has been confirmed by the observation of acid/base time evolution, because of simultaneous CaCO(3) dissolution and proton consumption. The dissolution/formation of CaCO(3) in water at pH 7.5-9 does not take place without a proton consumption/generation reaction, or a buffering chemical reaction of HCO(3)(-)+Ca(2+)right arrow over left arrowCaCO(3)+H(+). SEM images of the CaCO(3) fragments showed that the acid water ate away at the CaCO(3) formed at physiological pH values. Natural coral reefs can thus recover the physiological pH levels of seawater from the acidic range through partial dissolution of their own skeletons.
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PMID:Buffering dissociation/formation reaction of biogenic calcium carbonate. 1791 15

In this work, the removal of arsenic from aqueous solution by using FeSO4 with CaCO3 was investigated. Arsenic removal was significantly improved in the presence of CaCO3, compared with Ca(OH)2, giving an arsenic removal rate of 99.64% with the Fe/As molar ratio of 2:1 and Ca/Fe molar ratio of 1.5:1. With both FeSO4+Ca(OH)2 (FSCH) and FeSO4+CaCO3 (FSCC), several analytical methods including SEM-EDS, XRD, FTIR, and TG-DSC etc. were performed to characterize the sediments. The sediment from FSCC has much larger particle size, six time faster filtration speed and only one-third volume compared with that from traditional FSCH, allowing a very easy handling of the precipitate sludge, another clear advantage of using CaCO3. Moreover, much less fine and sticky CaSO4 was generated in the FSCC sludge than that from FSCH.
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PMID:Enhanced arsenic removal from water and easy handling of the precipitate sludge by using FeSO4 with CaCO3 to Ca(OH)2. 3112 93