Ferroelectric Domain and Switching Dynamics in Curved In2Se3: First Principle and Deep Learning Molecular Dynamics Simulations

Complex strain status can exist in 2D materials during their synthesis process, resulting in significant impacts on the physical and chemical properties. Despite their prevalence in experiments, their influence on the material properties and the corresponding mechanism are often understudied due to the lack of effective simulation methods. In this work, we investigated the effects of bending, rippling, and bubbling on the ferroelectric domains in In2Se3 monolayer by density functional theory (DFT) and deep learning molecular dynamics (DLMD) simulations. The analysis of the tube model shows that bending deformation imparts asymmetry into the system, and the polarization direction tends to orient towards the tensile side, which has a lower energy state than the opposite polarization direction. The energy barrier for polarization switching can be reduced by compressive strain according DFT results. The dynamics of the polarization switching is investigated by the DLMD simulations. The influence of curvature and temperature on the switching time follows the Arrhenius-style function. For the complex strain status in the rippling and bubbling model, the lifetime of the local transient polarization is analyzed by the autocorrelation function, and the size of the stable polarization domain is identified. Local curvature and temperature can influence the local polarization dynamics following the proposed Arrhenius-style equation. Through cross-scale simulations, this study demonstrates the capability of deep-learning potentials in simulating polarization for ferroelectric materials. It further reveals the potential to manipulate local polarization in ferroelectric materials through strain engineering

Near-infrared photodynamic and photothermal co-therapy based on organic small molecular dyes

Abstract Near-infrared (NIR) organic small molecule dyes (OSMDs) are effective photothermal agents for photothermal therapy (PTT) due to their advantages of low cost and toxicity, good biodegradation, and strong NIR absorption over a wide wavelength range. Nevertheless, OSMDs have limited applicability in PTT due to their low photothermal conversion efficiency and inadequate destruction of tumor regions that are nonirradiated by NIR light. However, they can also act as photosensitizers (PSs) to produce reactive oxygen species (ROS), which can be further eradicated by using ROS-related therapies to address the above limitations of PTT. In this review, the synergistic mechanism, composition, and properties of photodynamic therapy (PDT)–PTT nanoplatforms were comprehensively discussed. In addition, some specific strategies for further improving the combined PTT and PDT based on OSMDs for cancer to completely eradicate cancer cells were outlined. These strategies include performing image-guided co-therapy, enhancing tumor infiltration, increasing H2O2 or O2 in the tumor microenvironment, and loading anticancer drugs onto nanoplatforms to enable combined therapy with phototherapy and chemotherapy. Meanwhile, the intriguing prospects and challenges of this treatment modality were also summarized with a focus on the future trends of its clinical application. Graphical Abstrac

Micro-/nano-structured flexible electronics for biomedical applications

Flexible electronics are attracting considerable attention due to their promising performance including conductivity, stain- or pressure-sensing performance, skin-affinity, flexibility, etc. In particular, the structural design has promoted their properties and brought advanced functions, which make them valuable in biomedical applications including health monitoring, therapeutic applications and implantable devices. Herein, a review on the recent progress of flexible electronics with micro-/nano-structures is provided, involving the manufacturing technologies and applications in biomedical fields. Following these two sections, remaining challenges and the perspectives on future directions are also proposed

Carbon Nanotube Reinforced Poly-p-Phenylene Terephthalamide Fibers for Toughness Improvement:A Molecular Dynamics Study

Poly-p-phenylene terephthalamide (PPTA) fibers, such as DuPont's Kevlar fiber, are widely used in various fiber-reinforced composites due to their outstanding tensile stiffness, strength, and energy absorption capacity. To further improve the strength of PPTA-based fibers, it is necessary to investigate the molecular deformation mechanisms of these fibers while being coupled with nanoreinforcements. In this work, molecular dynamics method is used to predict the mechanical performance of carbon nanotubes (CNTs) reinforced Kevlar fibers, based on the molecular modeling of crystal interfaces in the microstructure of Kevlar fiber with the help of surface-modified CNTs, the tensile strength of Kevlar fibers can be increased by 27.8–39.7%. Furthermore, the mechanism of binding stability of CNTs is investigated by modifying the functional groups of CNTs, in which the hydrogen bonds (H-bonds) interaction plays an important role.</p