Thermal Responsive Shape Memory Polymers for Biomedical Applications

Summary: Shape memory polymers (SMPs) are a type of polymeric materials that can be programmed to memorize a less-constrained shape/configuration, subsequently assume a strained temporary shape/configuration, and then revert to the memorized shape/configuration upon triggering by an external stimulus(Lendlein & Kelch, 2002). Such responsiveness to stimuli is reminiscent of the adaptive responses universally observed in living organisms. Based on the nature of the external stimulus, SMPs can be categorized into light-responsive SMPs, chemical-responsive SMPs, magnetic field-responsive SMPs, and thermal-responsive SMPs, etc. Thermal-responsive SMPs are one of the most studied systems and will be the focus of this chapter

Manipulating non-Hermitian skin effect via electric fields

In non-Hermitian systems, the phenomenon that the bulk-band eigenstates are accumulated at the boundaries of the systems under open boundary conditions is called non-Hermitian skin effect (NHSE), which is one of the most iconic and important features of a non-Hermitian system. In this work, we investigate the fate of NHSE in the presence of electric fields by analytically calculating the dynamical evolution of an initial bulk state and numerically computing the spectral winding number, the distributions of eigenstates, as well as the dynamical evolutions. We show abundant manipulation effects of dc and ac fields on the NHSE, and that the physical mechanism behind these effects is the interplay between the Stark localization, dynamic localization and the NHSE. In addition, the finite size analysis of the non-Hermitian system with a pure dc field shows the phenomenon of size-dependent NHSE. We further propose a scheme to realize the discussed model based on an electronic circuit. The results will help to deepen the understanding of NHSE and its manipulation

Dissipation induced extended-localized transition

Mobility edge (ME), representing the critical energy that distinguishes between extended and localized states, is a key concept in understanding the transition between extended (metallic) and localized (insulating) states in disordered and quasiperiodic systems. Here we explore the impact of dissipation on a quasiperiodic system featuring MEs by calculating steady-state density matrix and analyzing quench dynamics with sudden introduction of dissipation, and demonstrate that dissipation can lead the system into specific states predominantly characterized by either extended or localized states, irrespective of the initial state. Our results establish the use of dissipation as a new avenue for inducing transitions between extended and localized states, and for manipulating dynamic behaviors of particles