No, it is not possible for an atom to consist of both a particle and an antiparticle simultaneously. Atoms are composed of a nucleus, which contains protons and neutrons, surrounded by electrons. Protons and neutrons are made up of quarks, which are not considered antiparticles. Electrons are elementary particles, and they are not their own antiparticles.
Particle-antiparticle pairs, such as electrons and positrons, can exist separately, but they cannot coexist within the same atom. When a particle and its corresponding antiparticle meet, they can annihilate each other, converting their mass into energy, typically in the form of photons. This process is not compatible with the stable existence of an atom.
Furthermore, the concept of a "membrane" hindering the connection between a particle and its antiparticle within an atom does not align with our understanding of atomic structure and interactions. The behavior of particles and antiparticles is governed by the laws of quantum field theory, which do not involve the presence of physical barriers or membranes within an atom that selectively allow or hinder connections between them.
In summary, atoms do not consist of both a particle and an antiparticle simultaneously, and the idea of a membrane hindering their connection within an atom does not align with our current understanding of particle physics and atomic structure.