This study revisits the American option pricing problem by introducing a more realistic exercise assumption: investors may exercise not only when the underlying asset reaches the theoretical optimal boundary but also when it lies within a properly defined ϵ-optimal set. For perpetual options, closed-form pricing formulas are derived. For finite-maturity contracts, a numerical algorithm is developed to approximate the ϵ-optimal exercise strip, and a Crank-Nicolson finite difference scheme is adapted to determine the resulting price interval. This approach provides a flexible pricing framework that better reflects real investor behaviour and risk preferences.

Small-scale robots designed to operate on water surfaces face challenges in mobility, adaptability, and multifunctionality. This study introduces bio-inspired “S-aquabots” powered by a programmable Marangoni motor (PM-motor), enabling highly controllable propulsion, efficient fuel use, and silent motion. The robots mimic natural leaves, blending seamlessly into aquatic environments while achieving a 3.5-fold improvement in fuel efficiency compared to conventional designs. With flexible hybrid electronics, the S-aquabots perform complex maneuvers, transmit real-time video, and monitor environmental conditions. By combining biomimicry with advanced engineering, these devices open new possibilities for environmental monitoring, pollution control, and adaptive robotics in outdoor aquatic systems.

Perovskite solar cells (PSCs) are widely recognized for their outstanding power conversion efficiency, but their vulnerability to heat undermines long-term stability and practical use. This study introduces a crystal facet engineering strategy to enhance thermal conductivity and reduce performance loss under elevated temperatures. By orienting the perovskite film toward the (100) facet, the researchers improved heat transfer, lowered operating temperature, and achieved stable power output even during prolonged illumination. The resulting inverted solar cells reached 25.12% efficiency while maintaining over 90% of initial performance after extended aging. These findings highlight thermal management through facet orientation as a powerful route to reliable, high-efficiency solar energy technologies.

Hydrogen release at the electrode surface has long hindered the development of aqueous zinc metal batteries, a promising technology for grid-scale energy storage. While most studies have focused on hydrogen evolution during zinc plating, new evidence reveals that significant hydrogen is also generated during zinc stripping, driven by chemical corrosion of newly exposed zinc surfaces. Researchers now show that small organic additives, particularly cysteamine, can form a protective gradient solid electrolyte interphase that isolates water molecules from the electrode surface. This approach greatly reduces unwanted hydrogen generation and improves battery reversibility, achieving more than 4000 stable cycles with high Coulombic efficiency.

An international research team reveals consistent growth in PFAS research by conducting bibliometric analysis of 1,281 publications from 2003 to 2023. The study, conducted using analytical tools like CiteSpace and VOSviewer, identifies the United States, China, and Sweden as the leading contributors. It provides a comprehensive overview of PFASs in drinking water, highlighting that their entry into water supplies is governed by surface runoff, soil leaching, and atmospheric deposition. While traditional analysis relies on liquid chromatography–tandem mass spectrometry, new portable sensors are emerging. Current removal strategies—such as activated carbon, ion-exchange, membranes, and advanced oxidation processes—involve significant cost-performance trade-offs. Key persistent challenges include monitoring short-chain and novel ether PFASs, managing concentrated waste, and establishing unified regulatory standards. This study aims to guide future research and policy to accelerate the achievement of PFAS-free drinking water.

Dynamic manipulation of optical signals between on-chip and free-space optical fields are highly pursued in various applications. Towards this goal, scientists in China proposed an addressable on-chip metasurface network on lithium niobate platform to present dynamic waveguide-based holographic display with improved multiplexing capability. Such scalable platform will advance holographic displays, high-capacity optical communication, and integrated photonic information processing, leveraging the potential of thin-film lithium niobate technology with high integration, fast response and high scalability.

A review study by Professor Weifeng Zhang from the College of Resources and Environmental Sciences, China Agricultural University, pointed out that stabilized fertilizers added with urease or nitrification inhibitors provide an effective path to solve this contradiction. China has achieved technological breakthroughs in this field and become a major global producer. The related paper has been published in Frontiers of Agricultural Science and Engineering (DOI: 10.15302/J-FASE-2025635).