Search Results (440)

This review develops a materials-to-clinic framework for patient-specific, functionally graded (FG) NiTi shape memory alloy (SMA) rods as a complementary paradigm for scoliosis correction that targets durable alignment with motion preservation. The article synthesizes the thermomechanical basis of NiTi (thermoelastic martensitic transformation, near constant superelastic plateau, and hysteretic damping) while leveraging additive manufacturing (AM) capabilities to spatially program transformation temperatures (e.g., A_f), effective stiffness, and geometric inertia along the rod. Consolidated process–structure–property linkages are provided for the PBF-LB, DED, and BJAM routes, together with contamination and composition-control strategies (mitigation of Ni volatilization; management of O/C uptake; gradient heat treatments) and segment-level quality assurance (DSC mapping, micro-CT, EBSD/indentation, and bench bending/torsion in physiologic media). Building on clinical curve classification, the methodology formalizes a grading mask and target moment vector that drive multi-objective optimization of the segmental A_f, relative density/architecture, and cross-section, followed by route-specific build plans and acceptance tolerances. A phenomenological constitutive description provides the forward map from local design variables to temperature-dependent moment–curvature loops for finite element verification and uncertainty control. Surgical handling and activation policies are codified (cold shaping in martensite and controlled intra-/postoperative warming within tissue-safe bounds), and a translational roadmap is outlined, encompassing prospective calibration of classification-to-design mappings, AM process maps with in situ monitoring, digital twin planning, and long-horizon fatigue/corrosion protocols. The proposed graded structures provide an adaptive transformation temperature gradient and tunable mechanical response, representing an important design direction toward 3D-printed, patient-specific SMA rods for durable, adjustable, and efficient scoliosis correction. Full article

Nickel–titanium (NiTi) shape memory alloys offer transformative functionality for biomedical and aerospace systems, yet their adoption in additive manufacturing (AM) remains constrained by powder reactivity, compositional sensitivity, and the high energy of feedstock production. This work establishes a unified, data-driven evaluation of how powder-state evolution during reuse and ultrasonic plasma atomization (UPA) affects both functional behavior and environmental performance. Virgin, reused, and UPA-recycled NiTi powders were systematically characterized based on particle-size distribution (PSD), SEM morphology, sphericity, oxygen content (ONH), and differential scanning calorimetry (DSC), and these results were coupled with a process-level life-cycle assessment (LCA) spanning cradle-to-gate feedstock generation. Reused powder showed finer but broadened PSD, surface oxidation, and elevated transformation temperatures; these degradation mechanisms limited its reuse despite reducing energy demand by ~30% relative to virgin powder. UPA provided a more effective regeneration pathway: UPA-recycled NiTi recovered high sphericity and smooth particle surfaces while lowering cradle-to-gate energy from 100 ± 10 to 50 ± 5 MJ·kg⁻¹ (≈50%) and reducing CO₂-equivalent emissions by ≈45%, with ~95% material recovery. Although the UPA condition exhibited a higher oxygen content in this study due to system-level atmosphere limitations, prior work indicates that optimized inert-gas control can suppress oxidation, suggesting clear avenues for improvement. Sustainability Index analysis confirmed UPA as the most favorable route, integrating reductions in energy demand and emissions with recovery of powder morphology and reconditioning of thermal transformation behavior. More broadly, the ability of UPA to promote compositional and microstructural redistribution highlights its potential to deliberately re-tune or “reprogram” transformation temperatures for application-specific requirements when alloying and processing atmospheres are carefully managed. Full article

To address the growing problem of electromagnetic pollution, the development of intelligent, multifunctional electromagnetic shielding materials is essential. The objective of this work is to fabricate an intelligent, low-reflection and high-absorption electromagnetic shielding composite via direct ink writing. In this study, epoxy resin (EP) was employed as the matrix, with nickel powder (Ni), multi-walled carbon nanotubes (MWCNTs), and silver powder (Ag) serving as functional fillers. Direct-ink printing enabled the fabrication of uniformly structured composites and layered gradient-structured composites. By precisely varying the filler content through layer-by-layer printing, the gradient-structured composite exhibited an increasing electrical conductivity gradient and a decreasing magnetic permeability gradient along the direction of electromagnetic wave incidence. Comprehensive characterization of microstructure, electrical, magnetic, and dielectric properties, and electromagnetic shielding effectiveness revealed that the uniformly structured composites exhibited higher total shielding effectiveness (SE_T) and reflection coefficient (R) with increased electrical conductivity. The layered gradient-structured composite achieved an electrical conductivity of 5.44 S/m and an SE_T of 17.74 dB, with the R value reduced to 0.53. Compared to the highly conductive homogeneous composite used in the bottom layer (R = 0.87), this represents a reduction in reflectivity of approximately 39.1%, thereby mitigating secondary pollution from excessive reflection. Under a DC voltage of 200 V, all composites recovered their original shape within 63 s, with shape fixity (R_f) and recovery (R_r) ratios exceeding 92%. This strong shape memory capability supports conformal coating on complex devices and facilitates material recycling, offering a practical foundation for next-generation multifunctional electromagnetic shielding materials. Full article

This paper reviews the current state of research on the seismic behavior of precast segmental bridge piers, systematically elucidating their performance under different connection configurations in the context of accelerated bridge construction and resilience demands. Additionally, it compiles commonly used research methodologies and strategies for enhancing seismic performance. The evidence indicates that emulative precast segmental piers can closely match monolithic cast-in-place structures, with reported peak lateral strengths typically within about 10% and comparable yield and peak displacements, whereas non-emulative systems generally provide superior self-centering with smaller residual displacements. Experimental studies, theoretical analyses, and numerical simulations have all proven effective in characterizing the mechanical behavior of these piers; each approach has distinct advantages, and a synergistic integration of methods is recommended for comprehensive evaluation. Measurable improvements in seismic performance have been reported through hybrid connection systems, innovative detailing, supplementary energy-dissipating devices, and the use of high-performance materials such as ultra-high-performance concrete (UHPC), engineered cementitious composites (ECC), fiber-reinforced polymers (FRP), and shape memory alloys (SMA); for example, representative tests reported about a 30% increase in energy dissipation at drift ratios exceeding 3%, and SMA-based reinforcement has been reported to reduce residual drift by roughly 67% relative to steel reinforcement. Finally, future research directions are proposed to support the wider adoption of precast bridge piers in high-seismicity regions, including addressing challenges related to performance degradation under multi-hazard coupling conditions, insufficient design criteria for connections, and the need for rapid post-earthquake repair and resilience. Full article

Wine represents one of the most complex food matrices from a sensory perspective, as its appreciation emerges from the interaction between chemical composition, perceptual mechanisms, and contextual influences. Contemporary research in oenology and sensory science increasingly recognizes wine evaluation as an integrated perceptual event shaped by cognition, memory, and affect, rather than a simple response to aroma or flavor cues. Live music is widely used in hospitality settings to enhance consumer experience; however, its specific influence on wine appreciation and emotional responses remains insufficiently explored, particularly in real-world contexts. This study investigates how two contrasting musical atmospheres—melancholic/relaxing and upbeat/motivational—modulate hedonic evaluations and emotional profiles during public wine tastings, compared with a no-music condition. Data were collected across five live tasting events (5 Wednesdays of Emotions) using structured questionnaires that included hedonic ratings and multidimensional emotional measures. Statistical analyses were conducted using non-parametric tests, meta-analytic p-value combination, and cumulative link mixed models for ordinal data. The presence of music significantly enhanced overall wine appreciation compared to the silent condition, although the magnitude and direction of the effect varied across individuals and musical styles. Upbeat/motivational music generally produced stronger and more consistent increases in liking than melancholic/relaxing music. Emotional responses—particularly positive surprise—emerged as key mediators of hedonic improvement and showed strong associations with overall liking. Preference profiling revealed distinct response patterns, indicating that auditory modulation of wine perception is not uniform across consumers. These findings support a crossmodal interpretation in which music shapes wine appreciation primarily through emotion-based and expectancy-related mechanisms rather than through direct sensory enhancement. By demonstrating these effects in ecologically valid tasting environments, the study highlights the role of auditory context as a meaningful component of multisensory wine experiences. Full article

Shape memory polymer (SMP) has broad applications in various industries, including automotive, aerospace, and medical, as it can maintain a given shape and return to its original form upon exposure to external stimuli such as heat, magnetic fields, or light. However, the intrinsic limitation of epoxy results in the low thermal conductivity of SMP, which reduces the difference in temperature (ΔT) between the glass transition temperature (T_g) and the actuation temperature, thereby negatively affecting the performance of shape recovery. In this study, the thermal stability and curing characteristics of SMP fabricated by blending Bisphenol-A epoxy with two types of amine curing agents were analyzed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) to establish optimal fabrication conditions. Subsequently, carbon-based fillers, graphite and 60 μm long carbon fibers, were added to fabricate shape memory polymer composites (SMPCs). The curing and mechanical properties of the SMPCs were subsequently evaluated, and the shape recovery characteristics were found to be optimal at a filler content of 3 wt%. The recovery time for the SMPC with graphite was 25 s, representing a 68.75% improvement in shape recovery time from the SMP. Furthermore, the addition of carbon fibers, with improved dispersion, led to the highest increases in tensile strength and impact strength of 24.71% and 59.36%, respectively. Full article

The paper continues the authors’ efforts to characterize and control the shape memory effect (SME) occurring in 3D printed specimens of recycled polyethylene terephthalate (rPET) and polyethylene terephthalate glycol (rPETG). Lamellar and “dog-bone” configuration specimens were 3D printed in the form of stratified composites with five different rPET/rPETG ratios, 100:0, 60:40, 50:50, 40:60, and 0:100, and two different angles between the specimen’s axis and the deposition direction, 0° and 45°. The lamellar specimens were used for: (i) free-recovery SME-investigating experiments, which monitored the variation of the displacement, of the free end of specimens which were bent at room temperature (RT), vs. temperature, during heating, (ii) differential scanning calorimetry (DSC), which emphasized heat flow variation vs. temperature, during glass transition and (iii) dynamic mechanical analysis (DMA), which recorded storage modulus vs. temperature in the glass transition interval. Dog-bone specimens were subjected to tensile failure and loading-unloading tests, performed at RT. The broken gauges were metallized with an Au layer and analyzed by scanning electron microscopy (SEM). The results showed that the specimens printed with 0° raster developed larger free-recovery SME strokes, the largest one corresponding to the specimen with rPET/rPETG = 40:60, which experienced the highest storage modulus increase, 872 MPa, and maximum value, 1818 MPa, during heating. The straight lamellar composite specimens experienced a supplementary shape recovery when bent at RT and heated, in such a way that their upper surface became concave, at the end of heating. Most of the specimens 3D printed at 0° raster developed stress failure plateaus, which were associated with the formation of delamination areas on SEM fractographs, while the specimens printed with 45° raster angle experienced necking failures, associated with the formation of crazing areas. The results suggested that 3D printed stratified rPET-rPETG composites, with dedicated spatial configurations, have the potential to serve as executive elements of light actuators for low-temperature operation. Full article

This work investigates the NiTi shape memory alloys fabricated via laser powder-directed energy deposition (LP-DED). The properties of NiTi alloys produced by powder metallurgy or additive manufacturing routes are strongly influenced by the type of feedstock material employed. Two powder feedstocks were used for DED fabrication: a blended mixture of elemental nickel and titanium powders with a nominal chemical composition of Ni56Ti44 (wt.%) and a pre-alloyed NiTi powder containing 55.75 wt.% Ni. Samples fabricated from both types of powders were subjected to microstructural characterization, phase composition analysis, and mechanical and corrosion testing. It was found that DED processing on a non-preheated CP-Ti substrate is prone to warping and that samples deposited from the elemental Ni and Ti powder mixture exhibited pronounced inhomogeneity of microstructure and mechanical properties along the build direction, accompanied by the formation of the Ti₂Ni secondary phase. The absence of a superelastic plateau was observed in the corresponding stress–strain response. On the contrary, the samples deposited from the pre-alloyed NiTi powder exhibited a microstructure composed of B2 and B19′ phases and already demonstrated a clear superelastic response in the as-built condition during tensile loading. Based on the tensile test results, this NiTi material was used only for superelasticity testing. The superelastic behavior was further enhanced by post-deposition heat treatment, which significantly increased the recovery rate from 53% to 89%. Full article

This study examines how the sense of home for people with dementia is shaped not only by physical settings but by dynamic atmospheric compositions emerging through memory, sensation, and everyday practices. Building on a preliminary literature mapping that identified three dimensions of home in later-life care environments—safe space, small world, and connection—we developed a multisensory co-design toolkit combining key-element cards and curated olfactory prompts. The study was conducted in a dementia-friendly residential care facility in Italy. Nine residents with mild–moderate dementia (aged 75–84) participated in two group sessions and six individual sessions, facilitated by two design researchers with care staff present. Data consist of audio-recorded and transcribed interviews, guided olfactory sessions, and researcher fieldnotes. Across sessions, participants articulated “small worlds” as micro-environments composed of meaningful objects, bodily comfort, routines, and sensory cues that supported emotional regulation and identity continuity. Olfactory prompts, administered through a low-intensity and participant-controlled protocol, supported scene-based autobiographical recall for some participants, often eliciting memories of domestic rituals, places, and relationships. Rather than treating home-like design as a fixed architectural style, we interpret home as continuously re-made through situated sensory–temporal patterns and relational practices. We translate these findings into atmospheric design directions for dementia care: designing places of self and refuge, staging accessible material memory devices, embedding gentle olfactory micro-worlds within daily routines, and approaching atmosphere as an ongoing process of co-attunement among residents, staff, and environmental conditions. The study contributes a methodological and conceptual framework for multisensory, narrative-driven approaches to designing home-like environments in long-term care. Full article

To develop a cost-effective shape memory alloy fiber-reinforced engineered cementitious composite (SMAF-ECC) with excellent mechanical properties, polypropylene (PP) fibers were used to partially replace polyvinyl alcohol (PVA) fibers to prepare the ECC matrix, and superelastic shape memory alloy fibers (SMAFs) were incorporated to fabricate a novel SMAF-ECC. Uniaxial tensile tests were systematically performed to characterize the tensile mechanical properties of the composites, focusing on the effects of SMAF volume content and diameter. The results indicate that the optimal base ECC mix proportion is 0.8 vol.% PP fibers and 1.2 vol.% PVA fibers, achieving an ultimate tensile strain of 4.88% (only a 4.69% reduction compared to pure PVA-ECC) while significantly reducing material cost without sacrificing superior ductility. SMAF volume content and diameter notably influence the tensile performance of SMAF-ECC, with the specimen containing 0.2 mm diameter SMAFs at 0.2 vol.% exhibiting the best performance: initial cracking stress, ultimate tensile stress, and ultimate tensile strain are enhanced by 16.79%, 20.85%, and 2.87%, respectively, compared to pure ECC. This study provides a theoretical basis and parametric guidance for the engineering popularization and application of cost-effective SMAF-ECCs. Full article

Biocompatible poly(lactic acid) (PLA) was plasticized with poly(ethylene glycol) (PEG) added at concentrations of 10, 15, and 20 wt.% relative to PLA, and then processed into gyroid triply periodic minimal surface (TPMS) scaffolds using fused filament fabrication (FFF) 3D printing. The influence of PEG concentration and gyroid structure (50% infill density) on thermal transitions, crystallinity, and low–temperature shape-memory performance was systematically investigated. The shape-memory effect (SME) of the PLA–based scaffolds was tailored through compositional control and structural design. Shape recovery under thermal activation at 40 °C and 50 °C was examined to reveal the correlation between composition and structure in governing low–temperature shape-memory behavior. The optimal composition (PLA/10 PEG, 50% gyroid infill) achieved shape recovery with a recovery ratio (R_r) of 97 ± 1% at 40 °C within 6 ± 1 min, demonstrating optimal shape-memory activation close to physiological temperature. Structural and morphological changes were characterized using ATR–FTIR, Raman spectroscopy, DSC, XRD, and SEM, providing comprehensive insight into the plasticization of the PLA matrix and its impact on structure–property relationships relevant to bone tissue engineering. Full article

To address poor seismic performance, large residual displacement, and insufficient self-centering capacity of prefabricated frame joints in building industrialization, this study proposes a novel self-centering prefabricated frame joint reinforced with shape memory alloy fiber (SMAF)–engineered cementitious composite (ECC) composites (SMAF-ECC). A validated finite element model of the proposed joint was established using ABAQUS, with comparative analyses conducted against conventional reinforced concrete (RC) and ECC-strengthened (RC-E) joint models to explore the effect of SMAF volume content on seismic performance. Results show that replacing the joint core zone concrete with SMAF-ECC significantly enhances the joint’s seismic and self-centering capabilities, reducing residual displacement and optimizing hysteretic behavior. SMAF volume content is a key factor affecting performance, with an optimal value identified and excessive content leading to fiber agglomeration and degraded self-centering ability. This study provides a feasible solution to improve the seismic resilience of prefabricated frame joints, laying a foundation for the application of SMAF-ECC in prefabricated structures. Full article

Background: Soft actuation relies on materials that are lightweight, flexible, and responsive to external stimuli. In biomedical applications, miniaturization and biocompatibility are key requirements for developing smart devices. Thermoplastic polyurethane (TPU) is particularly attractive due to its elasticity, processability, and biocompatibility; however, an improvement in its shape-recovery performance would significantly enhance its suitability for actuation systems. This study aims to develop TPU-based shape memory polymer (SMP) composites with improved functional behavior for biomedical applications. Methods: TPU was modified with aluminum nanoparticles (AlNPs) and multi-walled carbon nanotubes (MWCNTs), incorporated individually (1 wt.% and 3 wt.%) and in hybrid combinations (MWCNT:AlNP ratios of 2:1, 5:1, and 10:1). Samples were produced by compression molding and characterized through thermal, mechanical, electrical, and shape-recovery tests, supported by morphological analysis. Results: AlNPs moderately improved thermal conductivity, while MWCNTs significantly enhanced electrical conductivity and doubled the recovery force compared with neat TPU. Hybrid composites showed intermediate properties, with the 5:1 MWCNT:AlNP ratio offering the best balance between recovery force and activation speed. Conclusions: The synergistic combination of MWCNTs and AlNPs effectively enhances TPU’s multifunctional behavior, demonstrating strong potential for soft actuation in biomedical devices. Full article

Ionomers are promising materials because ionic interactions and their reversible clustering provide sensitivity to stimuli and facilitate energy dissipation, polymer miscibility, and ion transport. The existence of a wide variety of interacting ionic groups and their associated macromolecular structures provides the basis for considering the supramolecular organization of ionic polymeric materials as a factor determining the emergence of specific properties. The main structural elements of ionomers are ionic clusters, and the properties of ionomers are determined by their sizes and size distribution. Ionomers are attractive for use in composites, actuators, coatings, dyed textiles, adhesives, shape-memory and self-healing materials, water purification membranes, and ion-exchange membranes for fuel cells and batteries. This paper presents a review of the macromolecular structure and supramolecular organization of ionomers and their properties, depending on the basis of their ionic functionalization. The ionic functions of ionomers are determined primarily by the type of ion (cations or anions) that serves as the basis for their functionalization. Ionomers containing both anionic and cationic pendant ions are considered, with attention given to the influence of the nature of the counterions used on the properties of ionomers. Full article

Over the last decade, laser powder bed fusion (LPBF) received increased attention as a method of producing complex-shaped products from various materials. Recent results indicate the potential of this technology for the production of intermetallic NiTi alloys with shape memory. Several studies have demonstrated a strong influence of the LPBF process conditions on the resulting material properties, i.e., the martensitic phase transformation temperatures, reversible/irreversible strain after cyclic loading, phase composition, chemical composition, etc. However, the mechanisms of functional properties altering during LPBF consolidation remain unexplored in the present state-of-the-art. This study aims to advance the knowledge about tailoring material properties of NiTi under laser influence. In this work, thin-walled samples were manufactured from pre-alloyed NiTi powder via LPBF in a wide window of laser power and scanning speed, excluding hatch spacing by employing a single track-based scanning strategy to reveal the pure effect of the laser’s influence. NiTi samples were characterized by various methods such as differential scanning calorimetry, X-ray diffraction, and mechanical tests. Established relationships between NiTi properties and the LPBF process conditions provide the basis for the development of NiTi production protocols with controlled functional properties. Full article