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Radio occultation analysis of signal delay by the tandem FORMOSAT-3/COSMIC used as atmospheric sounding.. Radio occultation (RO) is a remote sensing technique used for measuring the physical properties of a planetary atmosphere or ring system.
In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula −OH and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry , alcohols and carboxylic acids contain one or more hydroxy groups.
The conversion between hydroxyl value and other hydroxyl content measurements is obtained by multiplying the hydroxyl value by the factor 17/560. [2] The chemical substance may be a fat, oil, natural or synthetic ester, or other polyol. [3] ASTM D 1957 [4] and ASTM E222-10 [5] describe several versions of this method of determining hydroxyl value.
The mechanism of the ligation reaction was first elucidated in the laboratory of I. Robert Lehman. [4] [5] Two fragments of DNA may be joined by DNA ligase which catalyzes the formation of a phosphodiester bond between the 3'-hydroxyl group (-OH) at one end of a strand of DNA and the 5'-phosphate group (-PO4) of another.
In water, the dimerization reaction of hydroxyl radicals can form hydrogen peroxide, while in saline systems the reaction of the hydroxyl radicals with chloride anions forms hypochlorite anions. The action of radiation upon underground water is responsible for the formation of hydrogen which is converted by bacteria into methane. [23] [24]
The rate of reaction with the hydroxyl radical often determines how long many pollutants last in the atmosphere, if they do not undergo photolysis or are rained out. For instance, methane, which reacts relatively slowly with hydroxyl radicals, has an average lifetime of >5 years and many CFCs have lifetimes of 50+ years.
The pH at which the reaction is quenched depends on the analysis method. For detection by NMR, the pH may be moved to around 4.0–4.5. For detection by mass spectrometry, the pH is dropped to the minimum of the exchange curve, pH 2.6. In the most basic experiment, the reaction is allowed to take place for a set time before it is quenched.
Regioselective dimethoxytritylation of the primary 5'-hydroxyl group of thymidine in the presence of a free secondary 3'-hydroxy group as a result of steric hindrance due to the dimethoxytrityl group and the ribose ring (Py = pyridine). [2] Steric hindrance is a consequence of steric effects. Steric hindrance is the slowing of chemical ...