This in vitro study evaluated the effects of the infiltration of F^- and Ca²⁺ ions into human enamel by electrokinetic flow (EKF) on the enamel microhardness and F^- content. Sound human enamel ground sections of unerupted third molars were infiltrated with de-ionized water by EKF and with F^- ion by EKF respectively. All samples were submitted to two successive transverse acid-etch biopsies (etching times of 30 s and 20 min) to quantify F^- ion infiltrated deep into enamel. Remarkably, sound enamel showed a large increase in microhardness (MH) after infiltration of NaF (p < 0.00001) and CaCl₂ (p = 0.013) by EKF. Additionally, NaF-EKF increased the remineralization in the lesion body of artificial enamel caries lesions compared to controls (p < 0.01). With the enamel biopsy technique, at both etching times, more F^- ions were found in the EKF-treated group than the control group (p << 0.05), and more fluoride was extracted from deeper biopsies in the NaF-EKF group. In conclusion, our results show that EKF treatment is superior in transporting Ca²⁺ and F⁻ ions into sound enamel when compared to molecular diffusion, enhancing both the mineralization of sound enamel and the remineralization of artificial enamel caries.

This in vitro study evaluated the effects of the infiltration of F^- and Ca²⁺ ions into human enamel by electrokinetic flow (EKF) on the mechanical property and F^- content of enamel. Sound human enamel ground sections of unerupted third molars were infiltrated with de-ionized water by EKF and with F^- ion by EKF respectively. All samples were submitted to two successive transverse acid-etch biopsies (etching times of 30 s and 20 mins) to quantify F^- ion infiltrated deep into enamel. Remarkably, sound enamel showed a large increase in microhardness (MH) after infiltration of NaF (p < 0.00001) and CaCl₂ (p = 0.013) by EKF. NaF-EKF increased AEC-LB remineralization compared to controls (p < 0.01). With enamel biopsy technique, at both etching times, more F^- ions were found in EKF-treated group than the control group (p << 0.05) and more fluoride was extracted from deeper biopsies in the NaF-EKF group. In conclusion, our results show that EKF treatment is a superior in transporting Ca²⁺ and F^- ions into sound enamel when compared to molecular diffusion, enhancing the mineralization of sound and carious human enamel.

In-transit additive manufacturing (AM) offers the potential to continue point-of-need production while a host transportation platform remains in motion. Although fabrication has been demonstrated aboard moving maritime platforms, comparable experimental evidence during sustained transit aboard land-based platforms—specifically heavy wheeled vehicles—remains limited. This review examines whether differences in platform dynamic environments may contribute to this asymmetry through interactions between environmental excitation, installed-system dynamics, and fabrication response. A structured narrative synthesis integrates evidence from additive manufacturing, structural dynamics, transportation vibration, and environmental qualification, focusing on maritime vessels and heavy wheeled vehicles as representative platforms, with material extrusion as the principal analytical case. Maritime environments combine low-frequency global vessel motion with higher-frequency machinery, propulsion, hydrodynamic, and transient excitation, whereas heavy wheeled vehicles exhibit suspension- and body-related response alongside broadband road-induced vibration and transient events. Representative material-extrusion structural modes span approximately 10–80 Hz, creating opportunities for spectral coincidence with both environments through distinct excitation mechanisms. Such overlap indicates potential dynamic amplification rather than deterministic degradation, since response also depends on excitation magnitude, damping, transmissibility, boundary conditions, and process-specific disturbance coupling. An environment–structure–process framework is proposed to support vibration-aware characterization and qualification of in-transit AM systems.

Additive manufacturing (AM) is increasingly considered for deployment in dynamic operating environments where environmental vibration and motion may influence fabrication quality and process stability. However, understanding of vibration effects remains largely process-specific, limiting comparison across AM technologies. This structured comparative review examines vibration–process interactions across the seven AM process families using three dimensions: disturbance coupling, material state and consolidation behaviour, and the temporal distribution of vulnerability. The final evidence base comprised 85 records, including 46 providing direct vibration–process evidence and 39 providing supporting mechanistic or contextual evidence. Only five studies directly investigated external or environmental vibration, indicating that deployment-relevant evidence remains limited and uneven across AM process families. Cross-process synthesis identified two principal vulnerability archetypes: continuously sensitive processes, where opportunities for disturbance coupling persist throughout fabrication, and stage-dependent processes, where vulnerability is concentrated within discrete process stages. The available evidence demonstrates multiple process-specific pathways through which mechanical excitation can interact with AM fabrication but does not support universal vibration tolerance thresholds or a general ranking of process sensitivity. The resulting framework provides a basis for vibration-aware qualification and future experimental investigation of AM systems intended for dynamic deployment environments.

Additive manufacturing (AM) is increasingly being considered for deployment in dynamic operating environments to enable distributed, on-demand manufacturing closer to the point of need. However, sustained environmental vibration presents challenges to print quality, process stability, and operational reliability, particularly for material-extrusion systems intended for in-transit operation. This scoping review maps evidence on vibration-induced effects, vibration characteristics, and mitigation strategies relevant to in-transit AM using the PRISMA-ScR framework. Systematic searches of Web of Science, ScienceDirect, and IEEE Xplore identified 24 studies for evidence synthesis. Of these, 19 (79.2%) examined externally imposed vibration or motion, while 11 (45.8%) investigated real or simulated operational/dynamic conditions. Vibration-related performance was found to depend on interactions among excitation characteristics, transmission behaviour, AM-system structural dynamics, and manufacturing-process sensitivity rather than excitation magnitude alone. Process stability, surface quality, and dimensional accuracy were the principal reported effects, while passive isolation was comparatively under-represented. No included study investigated sustained AM during realistic wheeled-vehicle operation over terrain. The findings therefore support treating terrestrial in-transit AM as a coupled source–path–receiver problem requiring integrated characterisation of environmental excitation, transmission, printer response, and manufacturing performance to establish system-specific vibration tolerance and mitigation requirements.