The Sample Section
The sample section of the main form displays information particular to a sample (usually a biological macromolecule) that is the subject of experiment in the ultracentrifuge. The section on the main form displays the vbar of the sample. Other information about the sample, if available, is displayed on or from the Sample Composition form. A previously saved record of sample information can be chosen by name from a list in the sample combo box. The choice of vbar used by Sednterp in its calculations is indicated by the one green underlined button.
The Direct Entry button enables the user to enter any value for vbar directly on the form. With direct entry, the vbar is not temperature corrected by Sednterp (This is indicated by the No Tc message that appears next to the vbar text box). The Standard button allows the user to enter a value for vbar at a particular temperature for the sample (preferably from an actual measurement you or someone else has made at some temperature, but perhaps from a standard table of physical constants). Values entered as standard are corrected for the temperature difference between the entered value and the experiment.
The Compute button calls up the Sample Composition form. On this form the composition of the sample is entered directly or indirectly from a file and the vbar will be computed.