Capsule oxide, primary

Figure 1. Primary capsule for point sources of 252Cf oxide (SR-Cf-XX)...

Phendimetrazine. Phendimetrazine is readily absorbed from the GI tract after an oral dose in humans. It exhibits a short plasma half-life = 1.9 h), primarily attributable to high clearance, and requires qid dosing to maintain adequate plasma levels (78). A special slow-release drug capsule has been developed that extends the half-life to 9.8 h. Two primary metabolites, phenmetrazine (61) and phendimetrazine N-oxide (62), are formed by N-dealkylation and N-oxidation and are cleared through the kidney (79). 

In comparison, Fe oxidation and deposition appear to be much less common in plumes. About half the Fe in the hydrothermal fluids combines with H2S and is rapidly transformed into Fe sulphides within a few seconds of release (e.g. Rudnicki Elderfield, 1993 James etal., 1995), and much of the Fe2+ that escapes sulphide precipitation is rapidly and spontaneously oxidized in well-oxygenated seawater making it difficult to evaluate the bacterial contribution to the redox transformations of hydrothermal Fe in plumes (Lilley etal., 1995 Winn etal., 1995). Nevertheless, high Fe/Mn particles and Fe-encrusted capsule forms have been observed in plumes at Axial Volcano (JDFR) the physicochemical characteristics of the capsules may be responsible for the passive or surface-enhanced deposition of iron (Cowen etal., 1999). Thiosulphate, the primary product of sulphide autooxidation, may also serve as a useful energy source, but this is yet to be documented in hydrothermal plumes (Winn etal., 1995 Cowen German, 2002). 

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