Fundamental interactions and quantum behavior in unified field theory

The concept of unified field theory is discussed. Two nonlinear field models with world volume type action are considered, namely extremal space-time film model and Born- Infeld nonlinear electrodynamics. The natural appearance of two long-range fundamental interactions, electromagnetism and gravitation, in these field models is discussed. The quantum behavior of the interacting solitons-particles is considered. The concept of quasi-bounding quantization in nonlinear field models is introduced.