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All isotopes of bismuth are radioactive; however, the most abundant isotope, ²⁰⁹Bi, possesses an extraordinarily long half-life of 1.9 × 10¹⁹ yr, rendering it effectively stable for practical applications. Bismuth is an attractive heavy element for the construction of inorganic–organic hybrid polymers because of its distinctive properties, including a high atomic refractive index, strong X-ray attenuation, and pronounced heavy-atom effects. In addition, representative bismuth compounds are relatively inexpensive and exhibit low toxicity. However, a major challenge lies in the intrinsic weakness of Bi–C bonds, necessitating careful molecular design to achieve stable bismuth-containing functional polymers. This Focus Review highlights recent advances in the synthesis of such polymers and discusses their unique properties, including a high refractive index, effective X-ray shielding, and characteristic phosphorescence.
High entropy TiZrHf0.5Nb0.5CoNiCu alloys with amorphous (Am) and Am + B2 mixed phases were synthesized in the melt-spun ribbons with different thicknesses of 32 mu m to 102 mu m. The as-spun structure consists of an Am phase for the ribbons with thicknesses below 80 mu m and changes to Am + B2 phases for the ribbons with larger thicknesses. The B2 phase has a spherical morphology and its diameter and volume fraction are 0.5-5 mu m and approximately 5 % for the ribbon with a thickness of 102 mu m. No difference in alloy composition between amorphous and B2 phases is recognized. The Am phase crystallizes through two stages: Am-* Am' + B2-* B2 +Cu10Zr7 +bcc-Nb. The B2 precipitates have extremely fine particle sizes of approximately 20-30 nm, and their volume fraction is as large as approximately 60 %-70 %. The tensile yield and fracture strengths of the amorphous + B2 phase ribbon (102 mu m in thickness) are 950 and 1523 MPa, respectively, and its plastic elongation is 1.64 %, indicating that remarkable strain-hardening occurs for the mixed phase alloy. The reason for the strain-hardening seems to originate from the strain-induced precipitations of B19' in B2 phase and B2 and B19' in Am matrix as well as at the Am/B2 interface. The highest hydrogen permeability for the Am alloy sheet of 32 mu m in thickness was 7.00 x 10-9 mol m-1 s-1 Pa-1/2 at 673 K, indicating that the hydrogen permeation amount in a unit time is comparable to that for the commercial Pd-Ag alloy sheet with a thickness of 100 mu m. The knowledge that the HE Am and Am + B2 alloys exhibit good tensile mechanical properties with distinct strain-hardening caused by the strain-induced precipitation as well as rather good hydrogen permeation ability encourages the future practical use of HE Am and Am + B2 mixed phase alloys. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.
Modular self-reconfigurable robots (MSRRs) offer structural adaptability for diverse tasks and environments. However, simulating such robots presents challenges in handling dynamic topology and closed-loop connections. PhysX, a modern high-performance physics engine widely adopted in robotics simulators including Isaac Sim, provides efficient and stable simulation through its articulation system for tree-structured robots. Yet, this articulation mechanism inherently prohibits closed-loop topologies, which are common in MSRRs. To address this, we propose a hybrid simulation and control framework for MSRRs. First, we propose the Soft-Constraint Joint (SCJ), a constraint mechanism implemented via articulation-excluded joints that enables loop formation and dynamic module connection without violating articulation assumptions. Second, we present a modular control architecture where each controller module encapsulates motion logic and can be automatically activated based on physical configuration. The proposed framework supports stable and scalable simulation of modular robots with seamless integration of perception, reconfiguration, and control. Experiments validate the effectiveness of the framework in handling multiple robot morphologies and in achieving reliable sim-to-real transfer.
We report the fabrication and evaluation of VOx and W-doped VOx thin films via the chemical solution deposition method, with a focus on their pH response characteristics. VOx and W-doped VOx thin films were prepared from precursor solutions under different conditions. The deposited films were employed as extended electrodes in extended-gate field-effect transistor (EGFET)-type pH sensors. Their pH response and sensitivity were evaluated over a range of neutral to basic conditions. Although the single-phase VOx film exhibited instability under alkaline conditions, the W-doped VOx film demonstrated significantly enhanced stability and achieved highly sensitive pH responses that exceeded the Nernst limit.
