2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/179461We construct non-tachyonic, non-supersymmetric orientifolds of Type 0B strings in ten, six and four space-time dimensions. Typically, these models have unitary gauge groups with charged massless fermionic and bosonic matter fields. However, generically there remains an uncancelled dilaton tadpole.23 pages, TeX; harvmac, references added, typos correctedHigh Energy Physics - Theorytext