We consider almost η-Ricci solitons in (ε)-para Sasakian manifolds satisfying certain curvature conditions. In the gradient case we give an estimation for the norm of the Ricci curvature tensor and express the scalar curvature of the manifold in terms of the two functions that define the soliton. We also prove that if the Ricci operator is of Codazzi type, then the gradient η-Ricci soliton is expanding if M is spacelike or shrinking if M is timelike.

We study lightlike hypersurfaces of para-Sasakian manifolds tangent to the characteristic vector field. In particular, we define invariant lightlike hypersurfaces and screen semi-invariant lightlike hypersurfaces, respectively, and give examples. Integrability conditions for the distributions on a screen semi-invariant lightlike hypersurface of para-Sasakian manifolds are investigated. We obtain a para-Sasakian structure on the leaves of an integrable distribution of a screen semi-invariant lightlike hypersurface.

In the present paper we study 3-dimensional normal almost paracontact metric manifolds admitting Ricci solitons and gradient Ricci solitons. We give an example of 3-dimensional normal almost paracontact metric manifold. It is shown that if in a 3-dimensional normal almost paracontact metric manifold with α, β = constant the metric is Ricci soliton, where potential vector field V is collinear with the characteristic vector field ξ, then the manifold is η-Einstein. We also prove that an η-Einstein 3-dimensional normal almost paracontact metric manifold with α, β = constant and V = ξ admits a Ricci soliton. Furthermore, we show that if a 3-dimensional normal almost paracontact metric manifold admits a Ricci soliton (g, ξ, λ) then the Ricci soliton is shrinking.

Our aim in this paper is to investigate some special types of lightlike submanifolds in metallic semi-Riemannian manifolds. We study invariant lightlike submanifolds and screen semi-invariant lightlike hypersurfaces of metallic semi-Riemannian manifolds and give examples. We obtain some conditions for the induced connection to be a metric connection and present integrability conditions for the distributions involved in the definitions of such types.

In this paper we study some soliton types on a quasi-Sasakian 3-manifold with respect to the Schouten-van Kampen connection. .............................................. .................................................................................................................................................................................................................................................................................................