Manual

Global Nonlinear Least-Squares Equilibrium Analysis:

After importing experimental data into the Global Fitting Control panel, you need to select a model to be fit. Models in UltraScan are indexed, the index for each model, which is used in naming associated datafiles, is listed here. Clicking on the "Select Model" button you can select from a number of predefined models as well as define your own models. After selecting a model, an information page will be shown, which will indicate the equation used for this model, and identify all parameters used. Parameters with a (*) can be floated so that an optimum value will be determined by the nonlinear least squares fitting algorithm. Simply click on the "OK" button to continue. Three of the model selections require additional user input:

• Fixed Molecular Weight Distribution: This model considers a linear combination of predefined exponential terms, each term defining a separate molecular weight. By default, the data will be fit with a generalized linear least squares algorithm, which simply adjusts the amplitude of exponential term. Good fits are usually accomplished with 3 - 5 terms, spread out through the range of component molecular weights present in the sample. Using the dialog shown below:
  

  you can define the number of exponential terms (Number of MW Slots), the lower limit of the molecular weight range, the upper limit of the molecular weight range, and enter a partial specific volume (vbar) value for each term. You can define a common vbar value for all terms by clicking on the "Use common vbar value?" checkbox. If you want to define separate vbar values, you can turn this checkbox off, and define the individual values in the model control window, more information is available in part 5, Parameter Controls

• User-Defined Monomer - Nmer Equilibrium: In this model you will need to specify the stoichiometry of the first association stage. After selecting this model, please enter the value in the dialog shown below:
  

• User-Defined Monomer - Nmer - Mmer Equilibrium: In this model you will need to specify the stoichiometry of the first and second association stage. After selecting this model, please enter the value in the dialog shown below:
  

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Model Selection

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