Physical-layer security of optical communication based on chaotic optical encryption without an additional driving signal.

We propose and numerically demonstrate a scheme for physical-layer security based on chaotic phase encryption, where the transmitted carrier signal is used as the common injection for chaos synchronization, so there is no need for additional common driving. To ensure privacy, two identical optical scramblers consisting of a semiconductor laser and a dispersion component are used to observe the carrier signal. The results show that the responses of the optical scramblers are highly synchronized but are not synchronized with the injection. By properly setting the phase encryption index, the original message can be well encrypted and decrypted. Moreover, the legal decryption performance is sensitive to the parameter mismatch, since it can degrade the synchronization quality. A slight drop in synchronization induces an evident deterioration in decryption performance. Therefore, without perfectly reconstructing the optical scrambler, the original message cannot be decoded by an eavesdropper.

3D Foaming Printing Biomimetic Hierarchically Macro-Micronanoporous Hydrogels for Enhancing Cell Growth and Proliferation.

Hydrogel, recognized as a promising biomaterial for tissue engineering, possesses notable characteristics, including high water uptake, an interconnected porous structure, and excellent permeability. However, the intricate task of fabricating a hierarchically macro-micronanoporous structure, essential for providing adequate space for nutrient diffusion and cell growth within hydrogels, remains a formidable challenge. In response to these challenges, this study introduces a sustainable and straightforward three-dimensional (3D) foaming printing strategy to produce hierarchically macro-micronanoporous hydrogels (HPHs) without the utilization of porogens and post-etching process. This method entails the controlled generation of air bubbles within the hydrogels through the application of optimal mechanical stirring rates. Subsequent ultraviolet (UV) cross-linking serves to effectively stabilize the macropores within the HPHs. The resulting hierarchically macro-micronanoporous structures demonstrate a substantial improvement in the viability, adhesion, and proliferation of human umbilical vein endothelial cells (HUVECs) when incubated with the hydrogels. These findings present a significant advancement in the fabrication of hierarchically macro-micronanoporous hydrogels, with potential applications in the fields of tissue engineering and organoid development.

Preparation and characterization of hierarchically porous hybrid gels for efficient dye adsorption.

Water treatment faces significant challenges due to the increasing complexity of pollutants and the need for more efficient, sustainable treatment methods. However, current adsorbent materials often struggle with issues such as low adsorption capacity, slow kinetics, and poor reusability, limiting their practical application. In this study, we developed a novel hierarchical porous hybrid gel (HPHG) for water treatment to address the limitations of conventional adsorbents. The HPHG features a multi-level porous structure (from 48 ± 28 nm to 4385 ± 823 nm) that significantly enhances its porosity and specific surface area. We systematically investigated the relationship between the material's structure and its adsorption performance. Kinetic studies revealed a tendency towards a pseudo-second-order adsorption model, attributed to the material's unique structural features that facilitate rapid mass exchange channels inside HPHG and provide abundant active sites for pollutant adsorption. Reusability tests demonstrated that the material retained 85.4% of its initial adsorption capacity after five adsorption-desorption cycles, highlighting its potential for practical applications. This study provides valuable insights into structure-performance relationships in advanced water treatment materials, offering a promising approach for designing next-generation adsorbents with superior efficiency and sustainability.

Modeling and Balancing the Solvent Evaporation of Thermal Annealing Process for Metal Halide Perovskites and Solar Cells.

Triple-mesoscopic perovskite solar cells (PSCs) have attracted intensive attention due to the high stability, simple fabrication process, and low material cost. In this structure, the perovskite layer is hosted by a triple-mesoscopic scaffold of TiO2 /ZrO2 /carbon, and thus the crystal quality is sensitive to the thermal annealing process. Typically, the annealing process is conducted in a petri dish, for which the solvent evaporation of the perovskite precursor is slowed down, but not controllable and designable. To control the solvent evaporation, annealing chambers are first designed with different shape and vapor releasing channels. Then, physical simulations are performed by a finite element method, and it is found out that the chamber with a crowned top and releasing channels on the bottom sides can realize homogeneous distribution of the solvent vapor. To verify the simulation results, chambers are fabricated by 3D printing technique, for which the printing deviation can be as low as 100 µm. By balancing the solvent evaporation and release, the optimal solvent evaporation is achieved of the perovskite precursor in the triple-mesoscopic scaffold. This work offers a method to obtain homogeneous distribution of solvent vapor, and provides a new insight into understanding the influence of solvent evaporation during the thermal annealing process for PSCs.

Interfacial Energy Band Alignment Enables the Reduction of Potential Loss for Hole-Conductor-Free Printable Mesoscopic Perovskite Solar Cells.

Perovskite solar cells (PSCs) have achieved high efficiencies with diversified device architectures. In particular, printable mesoscopic PSC has attracted intensive research attention due to its simple fabrication process and superior stability. However, in the absence of hole conductors, the unfavorable energy band alignment between the perovskite and the carbon electrode usually leads to the reduction of device performance, especially the open-circuit voltage (VOC). Here, a p-type molecule, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), is utilized to post-treat the perovskite/carbon interface, which benefits the charge transfer and suppresses the charge recombination within the device. As a result, the post-treated device delivers a power conversion efficiency of 18.05% with an enhanced VOC of 1044 mV. This work provides a facile method for tuning the interfacial energy band alignment and improving performance of printable mesoscopic PSCs.

Investigating the iodide and bromide ion exchange in metal halide perovskite single crystals and thin films.

The anion exchange between MAPbX3 (X = I- or Br-) and MAX salts in a solution environment is investigated. We find that I- can enter MAPbBr3 single crystals (SC) in millimeter scale, while Br- can only penetrate the surface of MAPbI3 SC in a micrometer scale. Due to the lattice variation, the reaction is partially reversible.