The existence of long-lived nuclear spin states in four-spin systems is explored by solution-state NMR experiments. Long-lived states are proved to exist in three different natural product molecules, each containing either a AA'BB' or a AA'XX' proton spin system. The measured state lifetimes are between four and eight times the spin-lattice relaxation time constants.

Casting is considered as a major manufacturing process. Thermal analysis of a solidifying medium is of great importance for appropriate design of casting processes. The conventional governing equation of a solidifying medium is based on the Fourier heat conduction law, which does not account for the phase-lag between the heat flux and the temperature gradient. In this paper, the concept of phas...

A scaling theory is applied in order to calculate the temperature dependence of the staggered magnetic susceptibility associated with the anti-ferromagnetism observed in high-temperature superconductors. In a logarithmic approximation, only a summation of the leading square logarithmic terms are taken into account, assuming the parquet approximation. We show that scaling theory can be applied t...

periodontal ligament is a thin layer of soft tissue that connects root of a tooth to the surrounding alveolar bone. these ligaments play an important role in initiating tooth movement when loads are applied to teeth with orthodontic appliances. the majority of such soft tissues exhibit as viscoelastic bodies or have a time-dependent behavior. due to the viscoelastic behavior of the periodontal ...