Korea Atomic Energy Research Institute

Monitoring biogeochemical properties of groundwater in rock aquifers near radionuclide-generating facilities is essential for effective water management and protection. Geochemical and microbiological properties vary with depth, influencing subsurface redox and trophic conditions. However, many studies lack depth-discrete sampling and an understanding of depth-dependent biogeochemical properties. In this study, we conducted a depth-discrete sampling assessment of major and trace elements, along with microbial community composition, in deep granitic groundwater from boreholes to evaluate the geochemical and microbiological characteristics of groundwater within and near an underground research tunnel (URT). Boreholes DB1 and DB3 are located inside the URT, while the JH well is outside. A total of 25 groundwater samples were collected from these boreholes at depths of 0-500 m (DB1), 0-350 m (DB3), and 0-150 m (JH), using packer systems. The results showed that groundwater types changed with depth, ranging from Ca-HCO₃ to Na-HCO₃. Redox profiles did not consistently correlate with increasing depth, suggesting preferential groundwater flow through altered zones and faults. Compared to the DB wells, the JH well showed higher dissolved oxygen levels and a broader range of geochemical parameters, including pH, Cl^-, and NO₃^-. Consistent with these observations, 16S rRNA gene amplicon sequencing revealed higher microbial diversity in JH. The community composition also differed among the three wells, shaped by water-rock interactions (more intense in DB), redox conditions (reducing in DB vs. oxic in JH), and possible surface-induced contamination (in JH). Further analysis of JH groundwater samples collected with and without a packer system revealed clear depth-dependent variations in dissolved ions, radionuclide concentrations, and microbial community structures. Fluoride (F^-) and uranium (U) concentrations exceeded drinking water guidelines at specific depths but fell below these limits without depth-discrete sampling. These findings highlight the importance of depth-resolved assessment of groundwater chemistry and microbiology for effective groundwater quality management and for evaluating the suitability of deep geological repositories.

The threat of herpes zoster (HZ) is increasing, particularly in the elderly and immunocompromised individuals. Although two platform vaccines are currently available for HZ prevention, the low effectiveness of the live attenuated varicella-zoster virus vaccine (Zostavax®), and the high reactogenicity and limited supply of the AS01 adjuvant gE subunit vaccine (Shingrix®) indicate that, the development of more effective and safe vaccines is required. Compared to conventional vaccines, mRNA vaccines offer the advantages of faster production and generally do not require adjuvants. However, no authorized mRNA vaccine is currently available for HZ. Therefore, we aimed to prepare a gE mRNA vaccine and evaluate the immunogenicity compared with the two commercial vaccines in mice. The gE mRNA vaccine elicited a robust humoral immune response, as measured by an enzyme-linked immunosorbent assay and the fluorescent antibody to membrane antigen test. The mRNA vaccine binding antibody level was comparable to that of Shingrix® and significantly higher than that of Zostavax®. In contrast, in cellular immune responses, which were evaluated by ELISpot assays and intracellular cytokine staining assay, the VZV gE mRNA vaccine induced significantly higher responses than Zostavax® and Shingrix®. In addition, the antibody-dependent cellular phagocytosis activity of the gE mRNA vaccine was comparable to that of the commercial vaccines. However, the highest antibody-dependent cellular cytotoxicity response was achieved by Shingrix®, followed by gE mRNA and then Zostavax®. Our results demonstrate that the mRNA HZ vaccine candidate elicited robust immunogenicity, especially in cellular immunity, and shows a promising potential for HZ prevention.

Mixed-dimensional heterojunctions (HJs) between compound semiconductors and transition metal dichalcogenides (TMDCs) provide a versatile platform for modulating interfacial exciton dynamics. While compound semiconductors offer precise compositional control for bandgap tuning across wide spectral ranges, they exhibit weak exciton binding energies that limit exciton stability at room temperature. Mixed-dimensional HJs address this limitation by integrating compound semiconductors with TMDCs, whose strong quantum confinement and reduced dielectric screening enable the formation of stable interlayer excitons with enhanced light-matter coupling. Here, we demonstrate a mixed-dimensional heterojunction comprising trilayer MoS₂ interfaced with an Al₂O₃/InGaN/GaN single quantum well (QW), designed to investigate interlayer exciton behavior. Quantum confinement in the QW localizes carriers near the heterointerface, allowing direct observation of interlayer excitonic states. Low-temperature photoluminescence measurements revealed a distinct emission peak at 2.02 eV, indicating the formation of interlayer excitons at the heterointerface. This strategy offers a unique approach for engineering exciton dynamics in mixed-dimensional systems, with implications for optoelectronic devices that leverage tailored interfacial exciton dynamics.