Natural aging-free Fe-Mn-Al-Ni-Mo single-crystal shape memory alloys via bifunctional Mo-segregation engineering

Fe-Mn-Al-Ni based shape memory alloys (SMAs) are able to exhibit superelasticity in a wide range of temperatures, and their superelastic stresses are extremely low temperature dependent, which holds potential applications in inclement fields such as deep space. However, the difficulty in obtaining large single crystals and the shortcoming of natural aging in this alloy system are hindering their practical application. Based on this, an ultra-large Fe-Mn-Al-Ni-Mo single-crystal SMA with nearly zero natural aging effect was successfully fabricated in this work via bifunctional Mo-segregation engineering. Firstly, at elevated temperatures, the grain boundary segregation of Mo atoms in this alloy effectively facilitated the abnormal grain growth during cyclic heat treatment. Based on this, a large-scale Fe-Mn-Al-Ni-Mo singlecrystal bar with a diameter of approximately 15.5 mm and a length of approximately 95 mm was obtained. Meanwhile, the Mo atoms with a low diffusion coefficient effectively hindered the coarsening of coherent B2 nanoprecipitates during natural aging. This led to the Fe-Mn-Al-Ni-Mo single crystals close to [001] orientation to exhibit a huge superelastic strain of 8.5% even after 1.5 years of natural aging. In contrast, B2 nanoprecipitates in the Mo-free Fe-Mn-Al-Ni SMA grew from ~7.7 to ~10.1 nm after natural aging for 1.5 years. This study provides a unique insight into the development of high-performance functional alloys using elemental segregation engineering

Multidimensional analysis of human outdoor comfort: Integrating just-in-time adaptive interventions (JITAIs) in urban digital twins

How can bidirectional information exchange be enhanced in urban digital twins, and support human-centric data and processes? Their key characteristic is the nearly real-time exchange of information, allowing adjustments to physical environments based on simulations and analytics within virtual models. Yet, achieving such interaction remains challenging, particularly regarding device deployment and infrastructure development. Embracing the concept of humans as sensors, this work develops a two-way framework based on the emerging concept of just-in-time adaptive interventions (JITAIs), exploring how urban digital twins can play a role in understanding and enhancing human comfort outdoors. Human comfort outdoors is inherently spatio-temporal and personalised, influenced by multisensory perception. The JITAIs framework involves collecting human comfort data and delivering interventions tailored to contextual and personal conditions. Thus, bidirectional information exchange will be established between humans and urban environments, thereby closing the loop in urban digital twins. A three-week campus experiment with 14 participants demonstrates this framework in two phases: (1) collecting comfort perception data and (2) delivering tailored interventions based on comfort perception and contextual features. End-of-day surveys reveal that 18.4% of responses indicated no behaviour change influenced by JITAIs, while 53.1% acknowledged their role in improving the understanding of outdoor comfort. The JITAIs framework is still nascent, but demonstrates an instance to close information loop in urban digital twins, as well as paves the way for future research. This novel work will facilitate human-centric urban digital twins and their multidisciplinary applications, such as planning comfortable walking routes

Critical edition of the Ladder of John Sinaites based on the Sinaitic manuscript branch

No abstract available

Influence of moisture on coal apparent permeability and CO2 sequestration capacity: Coupled effects of hygroscopic swelling and water film

Moisture is spread throughout the coal seams, significantly influencing coalbed methane extraction efficiency and CO2 sequestration capacity. However, existing research often neglects the impact of moisture on gas migration behavior. This study develops an apparent permeability evolution model for binary gases based on the three competing mechanisms of effective stress, gas-induced matrix strain and thermal swelling, and considering the dual role of water on fracture aperture. On this basis, the thermo-hydro-mechanical coupled gas mass transfer theory is constructed. The theory was utilized to obtain the relationship between gas-induced matrix strain and fracture water film thickness under varying water content conditions. And the mechanism of moisture’s role in characterizing the evolution of apparent permeability, CH4 recovery and CO2 storage is further discussed. Results indicate that moisture significantly suppresses the competitive adsorption behavior of binary gases within coal seams, leading to a notable reduction in matrix strain. Simultaneously, increased water content intensifies the development of water film along fracture walls. Additionally, through fixed-point monitoring method, it was elucidated that the apparent permeability of coalbeds showed a more obvious decreasing trend with the increase of water content, but the evolution of dramatic showed a significant decrease. Meanwhile, both CH4 recovery and CO2 cumulative storage capacities also exhibit a downward trajectory as water content levels increase. Inspired by these observations, the principles and advantages of intermittent pressurized CO2 injection are discussed, offering novel theoretical insights to support CO2 sequestration methods in deep, water-bearing coalbeds

Tenascin-c functionalised self-assembling peptide hydrogels for critical-sized bone defect reconstruction

Critical-sized bone defects are unable to heal spontaneously and receive poor clinical prognosis due to limitations in modern treatment strategies. Next-generation therapies are applying biomaterials incorporating BMP-2 to effectively promote and support bone regeneration, but adverse effects are linked to uncontrolled BMP-2 egress from the biomaterial. Implementing extracellular matrix proteins to biomaterials is a favourable approach to alleviate these drawbacks, and self-assembling peptide hydrogels are rapidly emerging as modulable and versatile biomaterials. Here, we describe the creation of a tenascin-c-functionalised peptide hydrogel designed to regenerate critical-sized bone defects. A recombinant fragment of tenascin-c spanning from the 3rd to 5th fibronectin-like domains is integrated into the fibre network. We demonstrate that this nascent construct effectively retains BMP-2 to differentiate mesenchymal stem cells into mature osteoblasts and achieves complete unionisation of murine critical-sized bone defects under low BMP-2 dose. All in all, we demonstrate tenascin-c as a suitable candidate to functionalise biomaterials intended for bone engineering applications and the promising potential of self-assembling peptide hydrogels in treating critical-sized bone defects

Fragments

No abstract available