A scalable processing method was used to fabricate graphite fiber composites with single-walled carbon nanotubes (SWCNTs) and the microstructures and properties of the fabricated laminates were investigated. SWCNTs were sprayed onto the surface of graphite/epoxy prepreg using an air spray. Interlaminar shear strength (ILSS) tests showed that the air spray processing had minimal effect on the quality of the laminates. Scanning electron microscopy (SEM) studies showed that SWCNTs are distributed uniformly in the plane of the laminate but not in the thickness direction due to low resin flow during cure. At high concentrations (>1.0 wt%), combination of a rather thick band of SWCNTs and low resin flow caused lack of resin inside of SWCNT bundles. The properties positively affected are in-plane shear strength, interlaminar fracture toughness (mode I), compressive strength, and electrical conductivity. Those properties showed improvement particularly when a lower concentration of SWCNTs was used. Fractography study using SEM showed altered crack propagation and crack bridging due to the presence of SWCNTs. The out-of-plane electrical conductivity was improved by 144% for 2 wt% SWCNT samples compared to samples without SWCNTs.

In this study, the liquid–vapor mixture model was used for a numerical study of natural convective flow in a cryogenic tank with a capacity of 4.9 m³ under various conditions of heat flux and filling level to understand the early stages of convective flow phenomena and the consequent thermal stratification of cryogenic liquid. Two cryogens—liquefied natural gas (LNG) and liquefied nitrogen (LN₂)—were compared to observe their effects. LN₂ exhibited faster vaporization owing to its lower heat of vaporization. It was observed that higher heat flux and lower filling level led to faster vaporization and relatively vigorous heat transfer, showing early thermal stratification.

Carbon fiber-reinforced epoxy (CF/EP) composites are attractive materials for hydrogen storage tanks due to their high strength-to-weight ratio and outstanding chemical resistance. However, cryogenic temperatures (CTs) have a substantial impact on the tensile strength and interfacial bonding of CF/EP materials, producing problems for their long-term performance and safety in hydrogen storage tank applications. This review paper investigates how low temperatures affect the tensile strength, modulus, and fracture toughness of CF/EP materials, as well as the essential interfacial interactions between carbon fibers (CFs) and the epoxy matrix (EP) in cryogenic environments. Material toughening techniques have evolved significantly, including the incorporation of nano-fillers, hybrid fibers, and enhanced resin formulations, to improve the durability and performance of CF/EP materials in cryogenic conditions. This review also assesses the hydrogen barrier properties of various composites, emphasizing the importance of reducing hydrogen permeability in order to retain material integrity. This review concludes by highlighting the importance of optimizing CF/EP composite design and fabrication for long-term performance and safety in hydrogen storage systems. It examines the prospects for using CF/EP composites in hydrogen storage tanks, as well as future research directions.

Microneedle array electrodes (MNE) showed immense potential for the sensitive monitoring of the bioelectric signals by penetrating the stratum corneum with high electrical impedance. In this paper, we introduce a rigid parylene coated microneedle electrode array and portable electrocardiography (ECG) circuit for monitoring of ECG reducing the motion artifacts. The developed MNE showed stability and durability for dynamic and long-term ECG monitoring in comparison to the typical silver-silver chloride (Ag/AgCl) wet electrodes. The microneedles showed no mechanical failure under the compression force up-to 16 N, but successful penetration of skin tissue with a low insertion force of 5 N. The electrical characteristics of the fabricated MNE were characterized by impedance spectroscopy with equivalent circuit model. The designed wearable wireless ECG monitoring device with MNE proved feasibility of the ECG recording which reduces the noise of movement artifacts during dynamic behaviors.

Developing high-performance polymer liners and their composites is essential for ensuring the safety and efficiency of type IV high-pressure hydrogen storage tanks. This review provides a thorough analysis of recent innovations in hydrogen gas barrier materials, fabrication techniques, and molecular modeling approaches to minimize hydrogen gas permeation. It examines key polymeric materials, such as polyamide 6 (PA6) and high-density polyethylene (HDPE), and emerging nanofiller reinforcements, such as graphene and montmorillonite clay. Additionally, it discusses manufacturing methods in relation to their effects on liner integrity and permeability. Molecular modeling techniques, especially molecular dynamics simulations, are emphasized as powerful tools for understanding hydrogen transport mechanisms and optimizing the interactions between polymers and fillers. Despite these notable advancements, challenges remain in achieving ultra-low hydrogen gas permeability, long-term stability, and scalable production methods. Future research should focus on developing multifunctional hybrid fillers, enhancing computational modeling frameworks, and designing novel polymer architectures specifically tailored for hydrogen storage applications.