Zeta file formats

File formats used by Zeta

Introduction

Zeta Library and thus also programs using it: Zeta Command Line and Zeta for Windows use several standard formats to read and write data they need for their calculations. These formats have been designed to be portable across different platforms, so they are all simple text files. This way, they are also human readable, so no special software is needed to edit them. However, some programs using Zeta Library (such as Zeta for Windows) offer a graphical user interface, where all the settings can be edited, so there is no need to edit the configuration files manually.

Please note that since it doesn't use the Zeta Library, Zeta for DOS doesn't use the formats described below.

Input file format

The input files for zeta potential calculation are text files consisting of 1 to 4 columns of data separated by whitespace. Each line consists of an optional label (which is the first column and can be any string not containing whitespace) followed by 1 or 3 columns of numbers (double precision - 15 significant digits) being measured mobility values or apparent zeta mobilities displayed by zetameter. Programs using Zeta Library usually require you to specify which of the above input types you want to use (see the documentation section of the appropriate program for details). If a single number is given, it is the value measured at the stationary level. If three numbers are given, they are values measured at the three levels of the cell, which are specified in the device settings. Before calculation starts, they are converted to stationary level mobilities which is then used for calculation (parabola method).

Parameters

The file format used to save the values of parameters of the measured system is similar to the format used by many applications to save their settings ("INI-file format"). The file consists of one section ([Parameters]) and a number of keys. For each key, its value is specified after the = sign. Whitespace between key name, the = sign, the value and at the beginning and end of line is ignored. However, for key names consisting of several words, the spacing must match the pattern exactly, so for example the keys "a key" and "a key" will be treated as different. For key names, case is irrelevant. Comments are started with a # or ; and continue until the end of line. A sample file (these are the parameters for water at 25 degrees Celsius) might look like this:

[Parameters]
#this is a comment
Anion conductivity=0.00763
Cation conductivity=0.00735
;this is also a comment
Dielectric constant=78.54
Ionic strength=0.001
Particle radius=1e-006 ;this is a comment, too
  Temperature =       298.16   #additional whitespace is OK
Viscosity=0.0008904

The parameter names are rather self-explanatory. The units used are as follows:

Anion conductivity	m²/Ohm/mol
Cation conductivity	m²/Ohm/mol
Dielectric constant	1
Ionic strength	mol/dm³
Particle radius	m
Temperature	Kelvin
Viscosity	Ns/m²

Note that the "INI-style" format allows the parameters to be saved inside a larger file. Actually you could just add a [Parameters] section to any configuration file and be able to read them from and save them into that file without damaging the other settings saved in that file. Comments will also be preserved. Standard methods (supplied by Zeta Library) for reading and saving parameters from and to files can handle parameters saved in larger files.

Device settings

The format for saving the device settings is very similar to the format used for parameters. Please refer to the "Parameters" section for details concerning file structure. The two formats differ only in the section and key names used. A sample device settings file could be:

[Device]
Aspect ratio=5
Lower level=20
Lower wall=0
Middle level=50
Upper level=80
Upper wall=100

The "Aspect ratio" is the aspect ratio of the electrophoretic cell in which the measurment is taking place. The other 5 values are used to determine the relative positions of the 3 points where measurments are taken (they are relevant only if parabola method is used). Since only positions relative to the size of the cell are used (that is ([Lower | Middle | Upper] level)/(Upper wall - Lower wall)), the choice of units is left to the user. You may consider using percentages as in the example file above, but you might as well wish to use positions measured in centimeters or any other units. Since "Lower wall" does not necessarily have to be 0, you can use positions measured relative to some point other the the bottom of the cell.