sterane


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sterane

[′sti‚rān]
(organic chemistry)
A cycloalkane derived from a sterol.
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Variations in the sterane carbon number distributions of marine source rock derived crude oils through geological time.
"The combined Neoproterozoic demosponge sterane record, showing 24-ipc and 26-mes steranes co-occurring in ancient rocks, is unlikely attributed to an isolated branch or extinct stem-group of demosponges," Love said.
Batterman, "PAHs (polycyclic aromatic hydrocarbons), nitro-PAHs, and hopane and sterane biomarkers in sediments of southern Lake Michigan, USA," Science of the Total Environment, vol.
The ratio of pristane (Pr) and phytane (Ph) value is 6.35 in the Wenchang source rocks from well 243 with low content of 4-methyl sterane (Figure 10), which means that the source rocks were formed in a shallow water environment.
Cholesterol is a polycyclic amphipathic molecule derived from a sterane backbone (Figure 1).
Biomarker maturity indicators, such as sterane maturity index ([C.sup.29][alpha][alpha][alpha]20R/(S + R) and [C.sub.29][alpha][beta][beta]([alpha][alpha][alpha] + [alpha][beta][beta])), are usually used to assess the maturity of oil [17-19].
The Tertiary coals are characterised by dominant odd carbon numbered w-alkanes (N-[C.sub.23] to n-[C.sub.33]), high Pr/Ph ratio (6-8), high [T.sub.m]/[T.sub.s] ratio (8-16), and predominant regular sterane [C.sub.29].
Methylprednisolone (Medrol) and prednisolone (Delta Cortef, Sterane) are also frequently used.
In this study, a quality spectrum that represents the relative strength of biomarkers in crude oil and source rocks (e.g., sterane m/z 217, m/z 372, m/z 386; hopane m/z 191, m/z 370, m/z 398; n-alkane m/z 85) was identified.
Among maturity-related parameters, [C.sub.29] [alpha][alpha][alpha] sterane 20S/(20S + 20R) ratios range from 0.47 to 0.58 (Table 3), being mostly close to the equilibrium value of 0.55, suggesting that the source rocks are mature to overmature, commensurate with the [R.sub.0] or [R.sub.b] values.
In terms of the sterane composition, the Triassic mudstone source rocks have relatively high abundance of pregnane and homopregnanes, as indicated by a pregnane/[alpha][alpha][alpha][C.sub.29]R regular sterane ratio of nearly 1.0.