Flat optics can shape light with ultrathin nanostructures, but single-layer devices are often limited by fixed in-plane designs. In a new Review, scientists summarize how stacking two or more nonlocal flat-optical layers introduces new interlayer degrees of freedom, including spacing, translation, twist, and lattice mismatch. These knobs enable tunable resonances, high-Q states, moiré flat bands, optical vortices, beam steering, chirality, and programmable nonlinear emission.

The team developed an off-axis bright- and dark-field OCT system with a custom-designed high-precision objective lens. By simultaneously collecting scattered signals at dual angles, the system achieves multi-angle nondestructive detection of subsurface defects in reaction-sintered SiC. Experimental validation demonstrates superior imaging depth, contrast, and defect recognition accuracy. This work provides a crucial technical solution for quality control of large-aperture high-precision optical components, with promising prospects for aerospace, defense, and civilian optical inspection applications.

Over the past 20 years, microrobots have moved from scientific vision toward biomedical reality. A perspective article by Bradley J. Nelson from ETH Zurich reviews how microrobots, typically ranging from about a millimeter down to a few microns in size, are being developed as intelligent microscale machines for future precision medicine. Inspired by the motility and adaptability of microorganisms, these systems are designed to function in low-Reynolds-number environments, where viscous forces dominate and conventional macroscale actuation principles are no longer applicable. The article discusses the physical constraints of microscale locomotion, major propulsion mechanisms, fabrication and material strategies, embodied intelligence, biomedical applications, and remaining translational challenges. It further suggests that advances in biocompatible materials, high-resolution imaging, magnetic navigation, and AI-driven control may support the future transition of microrobots from laboratory prototypes to clinically relevant tools for next-generation precision medicine.

Thermal energy storage systems rely on molten salt, but uneven flow and overheating often harm efficiency. A new study in Engineering introduces a twisted cloverleaf U‑tube paired with molten salt‑based nanofluids to improve heat transfer. Numerical tests show this design enhances fluid mixing and temperature uniformity. Optimized with Cu nanoparticles, it reaches a high performance criterion while controlling pressure drop, offering a practical upgrade for heat exchangers.

As renewable energy reshapes power grids, coal-fired plants need greater flexibility. A new study in Engineering presents a flue gas-driven molten-salt heat exchanger that avoids steam system limits and simplifies setup. Tested at 300 kW, it runs stably, controls temperature evenly, and has been scaled to 10 MW for a 350 MWe power plant. This practical technology improves ramping performance while cutting energy use and investment costs.

Wondering whether China can hit its carbon emission peak by 2030? A new probabilistic study in Engineering offers clear answers. It uses advanced modeling to measure uncertainties in energy use and renewable growth, revealing key thresholds for non‑fossil capacity and total energy consumption. The findings show how policy choices shape climate goals and provide practical insights for China’s low‑carbon transition.

To speed up low-carbon energy transition, MIT scientists have created a new digital twin system called MFRNet for industrial biomass combustion devices. This framework cuts reliance on costly 3D simulation data and combines field reconstruction and multi-objective optimization in one model. It accurately predicts emissions and helps find optimal operating conditions, offering a practical, data-efficient way to run cleaner and more efficient industrial combustion systems.

Coal-fired power units often face unstable combustion and high emissions under low-load operation. A new purification-combustion technology developed by Chinese researchers offers a reliable solution. Tests on a 200 kW system show efficient coal activation, high ash removal, and MILD combustion. The technology achieves ultra-low NOₓ emissions and combustion efficiency over 99.6%, supporting cleaner and more flexible coal use in modern power systems.