Wormholes are tunnels connecting different regions in space-time. They were obtained originally as a solution for Einstein's General Relativity theory and according to this theory they need to be filled by an exotic kind of anisotropic matter. In the present sense, by "exotic matter" we mean matter that does not satisfy the energy conditions. In this article we propose the modelling of wormholes within an alternative gravity theory that proposes an extra material (rather than geometrical) term in its gravitational action. Our solutions are obtained from well-known particular cases of the wormhole metric potentials, named redshift and shape functions, and yield the wormholes to be filled by a phantom fluid, that is, a fluid with equation of state parameter ω < −1. In possession of the solutions for the wormhole material content, we also apply the energy conditions to them. The features of those are carefully discussed.

We present a new approach for the f (R, T ) gravity formalism, by thoroughly exploring the extra terms of its effective energy-momentum tensor T eff μν , which we nameT μν , so that T eff μν = T μν +T μν , with T μν being the usual energy-momentum tensor of matter. Purely from the Bianchi identities, we obtain the conservation of both parts of the effective energy-momentum tensor, rather than the non-conservation of T μν , originally occurring in the f (R, T ) theories. In this way, the intriguing scenario of matter creation, which still lacks observational evidence, is evaded. One is left, then, with two sets of cosmological equations to be solved: the Friedmann-like equations along with the conservation of T μν and along with the conservation ofT μν . We present a physical interpretation for the conservation ofT μν , which can be related to the presence of stiff matter in the universe. The cosmological consequences of this approach are presented and discussed as well as the benefits of evading the matter energy-momentum tensor non-conservation.

No abstract

This study aimed to develop a chitosan-based hydrogel containing a mixture of flavonoids isolated from the leaves of Passiflora edulis Sims and to evaluate its stability, antioxidant properties, and wound healing effects on cutaneous lesions in diabetic rats. in vitro studies were carried out to evaluate the biocompatibility and flavonoid release from the chitosan hydrogel. in vivo wound healing studies were conducted on male Wistar rats, where the injured tissue was removed for histological analysis and determination of lipid peroxidation, superoxide dismutase activity, and glutathione peroxidase activity. From the histological analysis and macroscopic evaluation of the contraction of the wounds, it was observed that the formulation presented wound healing properties. In addition, treatment of the wound with the formulation stimulated the antioxidant defense system, suggesting a beneficial effect during the treatment of skin lesions in diabetic rats, especially in the first few days after wounding. According to these results, we can conclude that the chitosan hydrogel containing the flavonoid analyzed in this study has potential use as dressings in the treatment of wounds. K E Y W O R D S antioxidant, chitosan, flavonoid, hydrogel, Passiflora edulis, wound healing