In metals and compounds there exist small regions in which the phases of electron-pair waves are coherent. These regions are called superconducting domains (SD). At temperatures lower than Tc, these regions connect with each other and form a superconductor. The electron-pairs are partially bound pairs formed by electromagnetic interactions. Coherence gives rise to solitary waves and the Josephson effect. Ideal conductivity and the Meissner effect follow from these. The different effects of lattice vibrations on low and high-Tc superconductors are explained as well.

This paper shows that exact calculation for the transition probability in quantum mechanics gives rise to breaking the Fermi golden rule, and energy conservation, and gives two examples.

Taking the two-local-spin-mediated interaction (TLSMI) as pairing interaction, this paper explains six important experimental findings in YBa2Cu3O7-δ (Y123), and makes some predictions. The main prediction is that there is very high temperature supercon-ductivity in extra-underdoped Y123.

This paper summarizes the experimental features of the gap anisotropy in the high-Tc cuprates, and usc the composite d wave to explain these features.

Pathria's approach has been used to deal with the properties of the finite cubic system of 4He under constant pressure. The analytic expressions for the total number of particles N and the total pressure p near the critical point are obtained for mixture, antiperiodic, Neumann, and periodic boundary conditions. Influences of various boundary conditions upon low-temperature and critical characters of finite systems are discussed. For five boundary conditions, the relationship between the superfluid transition temperature T' and the size of the finite system Lo has been obtained. The results of this paper can be used in the case of superconductivity. Besides, from this work and others, we have obtained the formula for the phase-transition temperature T' in a finite system, t=σLo-b; here b is described as the finiteness constant, and σ is determined by the boundary conditions, the properties of the system, and the interaction between the system and the walls of the container.