Utilizing the idea of extra large dimensions, it has been suggested that the and gravity couplings unification can happen at a scale as low as 1 TeV. this paper, we explore this phenomenological possibility within string. In particular, we discuss how the proton decay bound can be satisfied Type I string theory. The string picture also suggests different scenarios gauge and gravitational couplings unification. The various scenarios are illustrated with a specific 4-dimensional N=1 supersymmetric chiral I string model with Pati-Salam-like gauge symmetry. We point out certain that should be generic in other Type I strings.
Shiu et al. (1998) studied this question.