Current Issue : October-December Volume : 2025 Issue Number : 4 Articles : 5 Articles
Bio-inspired joints play a pivotal role in legged robots, directly determining their motion capabilities and overall system performance. While shape memory alloy (SMA) actuators present superior power density and silent operation compared to conventional electromechanical drives, their inherent nonlinear hysteresis and restricted strain capacity (typically less than 5%) limit actuation range and control precision. This study proposes a bio-inspired joint integrating an antagonistic actuator configuration and differential dualdiameter pulley collaboration, achieving amplified joint stroke (±60°) and bidirectional active controllability. Leveraging a comprehensive experimental platform, precise reference input tracking is realized through adaptive fuzzy control. Furthermore, an SMA-driven bioinspired leg is developed based on this joint, along with a motion retargeting framework to map human motions onto the robotic leg. Human gait tracking experiments conducted on the leg platform validate its motion performance and explore practical applications of SMA in robotics....
The synthesis of calcium carbonate (CaCO3) nanoparticles has gained an increasing interest due to their improved properties and diverse industrial applications. Among various synthesis techniques, the mechanochemical synthesis process has emerged as a promising route for nano-CaCO3 synthesis. A high-energy ball mill is required for synthesizing nano- CaCO3, whereas post-milling heat treatment facilitates completing the reaction that remains incomplete during milling. Post-milling heat treatment may also influence the properties of synthesized CaCO3, which has not yet been thoroughly investigated. This study investigated the influence of post-milling heat treatment on the polymorphs, micromorphology, and particle size distribution of CaCO3. The results indicated that the heat treatment of the as-milled powder enhanced the homogeneity of crystal polymorphs while maintaining the particle sizes within the nano-range (<100 nm). X-ray diffraction (XRD) analysis identified two polymorphs (vaterite and calcite) in samples obtained from different milling intensities. However, after heat treatment, all vaterite transformed into calcite. A bimodal particle size distribution was observed in CaCO3 nanoparticles and was influenced by both the milling and heating intensities. It was observed that 60 min heat applied to 30 min as-milled powder was enough to produce nano-CaCO3 (<50 nm) where the percentage of larger particles (<250 nm) became negligible (~1%). Micromorphology images confirmed the transformation of crystal polymorphs and the reduction in particle size....
In Gen-IV nuclear reactors, structural materials must endure unprecedented levels of neutron irradiation and hydrogen exposure, posing significant challenges for traditional Nibased alloys. This study evaluates Ni–graphene nanocomposites (NGNCs) as a promising solution, leveraging their inherent radiation tolerance and hydrogen diffusion suppression. Using molecular dynamics simulations, we investigate how Ni/graphene interfaces influence mechanical properties under combined hydrogen permeation and displacement damage. Key parameters, such as hydrogen concentration, displacement damage level, strain rate, and temperature, are systematically varied to assess their impact on stress– strain behavior (including Young’s modulus and tensile strength), with comparisons to single-crystal nickel. Our findings reveal that NGNCs exhibit distinct mechanical responses characterized by serrated stress–strain curves due to interfacial slip. Hydrogen and irradiation effects are complex: low hydrogen levels can increase Young’s modulus, while higher concentrations and irradiation generally degrade strength, with NGNCs being more affected than single-crystal nickel. Additionally, NGNCs show enhanced thermal stability but increased strain rate sensitivity. These results provide critical insights for designing materials that balance reinforcement with environmental resilience in nuclear applications....
This work introduces a new type of water evaporation-driven nanogenerator (S-WEG) utilizing the natural mineral sepiolite, which capitalizes on its hierarchical nanoporous architecture and intrinsic hydrophilicity to harvest energy from ambient humidity through capillary-driven evaporation. The S-WEG, fabricated via a facile drop-coating drying method, demonstrates remarkable mechanical flexibility and sustained operational reliability. Our results demonstrate that by optimizing evaporation height and width, the S-WEG can generate a short-circuit current of ~0.6 μA and an open-circuit voltage of ~0.9 V. Through series and parallel configurations of multiple S-WEG units, the current and voltage outputs can be effectively amplified to power small-scale electronics....
Arsenic contamination in water demands effective, low-cost removal methods. This study introduces nanomagnetite-coated biochar derived from pecan nutshells for efficient arsenic adsorption. Utilizing a solvothermal method, uniform magnetite crystals were grown on biochar in a controlled process at 200 ◦C. The resulting bioadsorbent, characterized by XRD, SEM, and FTIR, exhibited a narrow size distribution and consistently high arsenic removal rates (97.30–98.76%). Biochar with varied particle sizes, synthesized at a short reaction time (6 h), showed the highest removal efficiency of arsenic (98.76%) and adsorption capacity (7.974 mg/g). This approach offers a sustainable for arsenic remediation, and ease of magnetic separation....
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