Extend IRT chemistry simulations for PBS buffer and additional salts

[MarcBHahn]

Dear Topas-nBio team,
I extended the pH dependent simulation in the IRT method to include effects of common phosphate buffered saline for pH values around 7.2, as it is normally used.
Therefore, I took your implementation of the HSO4 as basis and extended upon that.
Additionally I added parameters to include the effects of mono, di and trivalent salts to include their effects into the calculation of the ionic strength of the solvent.
It's still needs some further testing, but please let me know if I can improve something already in terms of coding style, sturcture etc, to make it properly fit into the overall structure of the IRT implementation.
Best Marc

[JoseRamosMendez]

Thanks Marc! Looking good. Do you have a use-case example we could add to either the examples folder or https://github.com/topas-nbio/TOPAS-nBio-regression?

[MarcBHahn]

Thanks Marc! Looking good. Do you have a use-case example we could add to either the examples folder or https://github.com/topas-nbio/TOPAS-nBio-regression?

Hi Jose, as soon as I find some time to go through the literature and compile a set of rate constants for the phosphate buffer components I will add an example as well.