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Figure 3
Charts of PEG concentrations versus relative frequency for the various sized PEGs. The PEG concentrations have been grouped into 5% ranges and each bin is described by the upper value of the concentration range, thus the bin `0–5%' is labeled `5%' on the graph. The `relative frequency' is the count of the number of occurrences of a PEG at a given concentration divided by the total number of conditions containing that PEG. Only those PEGs that are found at least 30 times are shown; the number of usages is recorded in parentheses after the PEG name. The assignment of the different PEGs to four classes (Liquid, Low MW, Mid MW and High MW) was mostly for clarity of the graphical representation, but seems to capture groups of PEGs that behave somewhat similarly. There is a clear trend for the larger PEGs to be used at a specific concentration, whereas the liquid PEGs have no clear usage maximum and appear to be used both as additives and as precipitating agents (i.e. used both at low concentrations and at high concentrations).

Journal logoBIOLOGICAL
ISSN: 1399-0047
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