Ulsan National Institute of Science and Technology

The “hotspots”, which are typically found in nanogaps between metal structures, are critical for the enhancement of the electromagnetic field. Surface‐enhanced Raman scattering (SERS), a technique known for its exceptional sensitivity and molecular detection capability, relies on the creation of these hotspots within nanostructures, where localized surface plasmon resonance (LSPR) amplifies Raman signals. However, creating adjustable nanogaps on a large scale remains challenging, particularly for applications involving biomacromolecules of various sizes. The development of tunable plasmonic nanostructures on flexible substrates represents a significant advance in the creation and precise control of these hotspots. This work introduces tunable nanogaps on flexible substrates, utilizing thermally responsive materials to allow real‐time control of gap width for different molecule sizes. Through advanced nanofabrication techniques, uniform, tunable nanogaps are achieved over large areas of wafer scale, enabling dynamic modulation of SERS signals. This approach results in an enhancement factor of over ≈10⁷, sufficient for single‐molecule detection, with a detection limit as low as 10⁻¹² m. The thermally tunable nanogaps provide a powerful tool for the precise detection of molecules and offer significant advantages for a wide range of sensing and analytical applications.

Recently, a strategy involving the engineering of chemokine receptors on immune cells was developed to optimize adoptive cell therapy (ACT) for solid tumors. Given the variability in chemokine secretion among different tumor types, identifying and modulating the appropriate chemokine receptors is crucial. In this study, we utilized extensive RNA sequencing data from both tumor tissues from The Cancer Genome Atlas and normal tissues from Genotype-Tissue Expression to investigate the expression profiles of chemokines. Through analysis, we identified eight chemokine receptors associated with increased chemokine levels in tumor tissues compared to normal tissues, making them promising candidates for enhancing ACT. Subsequent examination of tumor-infiltrating lymphocytes and chimeric antigen receptor-T cells revealed that five out of the eight candidate chemokine receptors did not exhibit elevated expression in T cells. Among five candidates, we demonstrated that CXCR5 is a particularly promising candidate for enhancing cell migration without compromising cell viability or cytotoxicity. In conclusion, our study underscores the potential of five chemokine receptors (CCR6, CCR9, CXCR1, CXCR5, and XCR1) as valuable targets for modulating ACT to enhance cell trafficking and potentially improve cancer therapy outcomes.

This work proposes a design methodology of a voltage controller for a dual-active-bridge (DAB) converter utilizing spread-spectrum modulation (SSM) to distribute EM noise based on a small-signal model and its analysis. When power electronic devices operate at a fixed switching frequency, high EM noise concentrates at the switching frequency and its harmonics. The SSM is a switching modulation technique that reduces the EM noise by varying the operating frequency to distribute noise according to the frequency domain. When the SSM is applied, the DAB converter operates with variable switching frequencies. Given that the output voltage of the DAB converter depends on the switching frequency, the SSM affects it. Accordingly, a controller must be designed based on the small-signal model that considers the frequency variation caused by the SSM. In this work, the controller for regulating the output voltage is designed using the small-signal model of the DAB converter utilizing the SSM, and the converter performance is verified through simulations and experimental measurements with a 3.3 kW prototype converter.

Smart adhesives with engineered mechanical structures have emerged as a transformative technology with broad applications in fields such as wearable healthcare devices, bioengineering, and soft robotics. By integrating advanced mechanical architectures like kirigami, tessellations, and multilayered designs, these adhesives exhibit enhanced surface and mechanical properties that lead to superior interfacial adhesion. Such designs offer critical advantages—improved stretchability, substrate conformability, and increased adhesion strength—over conventional adhesives. This review explores the range of engineered structures used in smart adhesives and demonstrates how these innovations address the limitations of traditional adhesives. Additionally, we discuss their applications in wearable healthcare devices, flexible electronics, and robotics.

Background Artificial intelligence (AI) social chatbots represent a major advancement in merging technology with mental health, offering benefits through natural and emotional communication. Unlike task-oriented chatbots, social chatbots build relationships and provide social support, which can positively impact mental health outcomes like loneliness and social anxiety. However, the specific effects and mechanisms through which these chatbots influence mental health remain underexplored. Objective This study explores the mental health potential of AI social chatbots, focusing on their impact on loneliness and social anxiety among university students. The study seeks to (i) assess the impact of engaging with an AI social chatbot in South Korea, "Luda Lee," on these mental health outcomes over a 4-week period and (ii) analyze user experiences to identify perceived strengths and weaknesses, as well as the applicability of social chatbots in therapeutic contexts. Methods A single-group pre-post study was conducted with university students who interacted with the chatbot for 4 weeks. Measures included loneliness, social anxiety, and mood-related symptoms such as depression, assessed at baseline, week 2, and week 4. Quantitative measures were analyzed using analysis of variance and stepwise linear regression to identify the factors affecting change. Thematic analysis was used to analyze user experiences and assess the perceived benefits and challenges of chatbots. Results A total of 176 participants (88 males, average age=22.6 (SD 2.92)) took part in the study. Baseline measures indicated slightly elevated levels of loneliness (UCLA Loneliness Scale, mean 27.97, SD (11.07)) and social anxiety (Liebowitz Social Anxiety Scale, mean 25.3, SD (14.19)) compared to typical university students. Significant reductions were observed as loneliness decreasing by week 2 (t175=2.55, P=.02) and social anxiety decreasing by week 4 (t175=2.67, P=.01). Stepwise linear regression identified baseline loneliness (β=0.78, 95% CI 0.67 to 0.89), self-disclosure (β=–0.65, 95% CI –1.07 to –0.23) and resilience (β=0.07, 95% CI 0.01 to 0.13) as significant predictors of week 4 loneliness (R2=0.64). Baseline social anxiety (β=0.92, 95% CI 0.81 to 1.03) significantly predicted week 4 anxiety (R2=0.65). These findings indicate higher baseline loneliness, lower self-disclosure to the chatbot, and higher resilience significantly predicted higher loneliness at week 4. Additionally, higher baseline social anxiety significantly predicted higher social anxiety at week 4. Qualitative analysis highlighted the chatbot's empathy and support as features for reliability, though issues such as inconsistent responses and excessive enthusiasm occasionally disrupted user immersion. Conclusions Social chatbots may have the potential to mitigate feelings of loneliness and social anxiety, indicating their possible utility as complementary resources in mental health interventions. User insights emphasize the importance of empathy, accessibility, and structured conversations in achieving therapeutic goals. Trial Registration Clinical Research Information Service (CRIS) KCT0009288; https://tinyurl.com/hxrznt3t

We report a CNT/eGaIn composite that suppresses dissolutive wetting on platinum substrates. Minimizing CNT aggregation within eGaIn prevents gallium penetration, maintaining interconnect stability for up to 30 days. This composite...

Butadiene-functionalized graphitic nanoplatelet (BfGN) is synthesized using only graphite and 1,3-butadiene, without requiring any additional reactions. Due to the chemical affinity of the butadiene functional groups, the BfGN exhibits excellent dispersion in solvents (such as THF) and polymers (such as ABS resin). Consequently, BfGN&ABS_X nanocomposites, which can be easily fabricated via a solution casting process, show remarkable mechanical performance and thermal stability in comparison to pure ABS resin. Among BfGN&ABS_X nanocomposites, BfGN&ABS_1 nanocomposite exhibits the best performance. The tensile strength, Young’s modulus, and toughness of BfGN&ABS_1 nanocomposite is increased by 90.1%, 2.4%, and 2.8%, respectively, compared to the pure ABS resin. In terms of tensile strength, all BfGN&ABS_X nanocomposites show significant improvement due to the compatibility between ABS chains and BfGN. Therefore, graphitic nanoplatelet (GNP) prepared through mechanochemical reactions possess many outstanding properties. In particular, GNP functionalized with various groups exhibits remarkable compatibility with many polymers.

Current in vitro models of 3D tumor spheroids within the microenvironment have emerged as promising tools for understanding tumor progression and potential drug responses. However, creating spheroids with functional vasculature remains challenging in a controlled and high‐throughput manner. Herein, a novel open 3D‐microarray platform is presented for a spheroid‐endothelium interaction (ODSEI) chip, capable of arraying more than 1000 spheroids on top of the vasculature, compartmentalized for single spheroid‐level analysis of drug resistance, and allows for the extraction of specific spheroids for further analysis. As proof of concept, the crosstalk between breast cancer spheroids and vasculature is monitored, validating the roles of endothelial cells in acquired tamoxifen resistance. Cancer spheroids exhibited reduced sensitivity to tamoxifen in the presence of vasculature. Further analysis through single‐cell RNA sequencing of extracted spheroids and protein arrays elucidated gene expression profiles and cytokines associated with acquired tamoxifen resistance, particularly involving the TNF‐α pathway via NF‐κB and mTOR signaling. By targeting the highly expressed cytokines (IL‐8, TIMP1) identified, tamoxifen resistance in cancer spheroid can be effectively reversed. In summary, the ODSEI chip allows to study spheroid and endothelial interaction in various contexts, leading to improved insights into tumor biology and therapeutic strategies.

In the field of wearable electronics and human–machine interfaces, there is a growing need for highly sensitive and adaptable sensors capable of detecting a wide range of stimuli with high precision. Traditional sensors often lack the versatility to adjust their sensitivity for different applications. Inspired by the mechanosensory system of spiders, a shape‐reconfigurable crack‐based sensor with ultrahigh and tunable strain sensitivity based on the precise control of nanocrack formation on a shape memory polymer substrate is demonstrated. This design incorporates a line‐patterned substrate composed of a thermoplastic polyurethane (TPU) matrix and thermo‐responsive shape memory polymer, poly(lactic acid) (PLA), to form parallel nanocracks in a thin platinum film. This design achieves an ultrahigh gauge factor of 2.7 × 10⁹ at 2% strain, significantly surpassing conventional sensors. The shape memory property of the TPU/PLA substrate enables tunable strain sensitivity according to the desired strain range, eliminating the need for multiple sensors. The sensor demonstrates exceptional capabilities in detecting subtle strains (as low as 0.025%), monitoring biological signals, and sensing acoustic waves (100–20 000 Hz) with a response time of 0.025 ms. This work represents a significant advancement toward strain sensors with both ultrahigh and tunable sensitivity.

Seawater batteries (SWBs) have emerged as a next‐generation battery technology that does not rely on lithium, a limited resource essential for lithium‐ion batteries. Instead, SWBs utilize abundant sodium from seawater, offering a sustainable alternative to conventional battery technologies. Previous studies have demonstrated the feasibility of achieving high energy densities in SWB anodes using vertically aligned electrodes. However, the use of tin anode materials with high volumetric energy density has encountered reversibility challenges due to the electrical isolation of tin particles caused by severe pulverization during charging and discharging. In this study, the reversibility of vertically arranged tin electrodes is improved by promoting desodiation of pulverized tin particles through the use of sodium‐pyrene (Na‐Pyr) as a redox mediator. The Na‐Pyr redox‐mediated electrolyte, combined with vertically aligned tin electrodes, demonstrates reversible capacities of 6 mAh cm⁻² over 80 cycles in SWBs. Furthermore, it is shown that arranging the electrodes vertically to maximize the area can achieve a high areal capacity of up to 40 mAh cm⁻². The combination of the Na‐Pyr redox mediator and vertical tin electrode, with its excellent electrochemical performance, is promising as a practical anode material for enabling SWBs to achieve high energy density.

Efficient separation of hydrogen isotopes, especially deuterium (D2), is pivotal for advancing industries such as nuclear fusion, semiconductor processing, and metabolic imaging. Current technologies, including cryogenic distillation and Girdler sulfide processes, suffer from significant limitations in selectivity and cost‐effectiveness. Herein, we introduce a novel approach utilizing an imidazolium‐based Metal–Organic Framework (MOF), JCM‐1, designed to enhance D2/H2 separation through temperature‐dependent gate‐opening controlled by ion exchange. By substituting NO3⁻ ions in JCM‐1(NO3⁻) with Cl⁻ ions to form JCM‐1(Cl⁻), we precisely modulate the gate‐opening threshold, achieving a significant enhancement in isotope selectivity. JCM‐1(NO3⁻) exhibited a D2/H2 selectivity (SD2/H2) of 14.4 at 30 K and 1 bar, while JCM‐1(Cl⁻) achieved an exceptional selectivity of 27.7 at 50 K and 1 mbar. This heightened performance is attributed to the reduced pore aperture and higher gate‐opening temperature resulting from the Cl⁻ exchange, which optimizes the selective adsorption of D2. Our findings reveal that JCM‐1 frameworks, with their finely tunable gate‐opening properties, offer a highly efficient and adaptable platform for hydrogen isotope separation. This work not only advances the understanding of ion‐exchanged MOFs but also opens new pathways for targeted applications in isotope separation and other gas separation processes.

Radical S‐adenosyl methionine enzymes catalyze a diverse repertoire of post‐translational modifications in protein and peptide substrates. Among these, an exceptional and mechanistically obscure example is the installation of α‐keto‐β‐amino acid residues by formal excision of a tyrosine‐derived tyramine unit. The responsible spliceases are key maturases in a widespread family of natural products termed spliceotides that comprise potent protease inhibitors, with the installed β‐residues being crucial for bioactivity. Here, we established the in vitro activity of the model splicease PcpXY to interrogate the mechanism of non‐canonical protein splicing. Identification of shunt and coproducts, deuterium labeling studies, and density functional theory energy calculations of hypothesized intermediates support a mechanism involving hydrogen abstraction at tyrosine Cα as the initial site of peptide radical formation and release of 4‐hydroxybenzaldehyde as the tyrosine‐derived coproduct. The data illuminate key features of this unprecedented radical‐mediated biotransformation yielding ketoamide pharmacophores that are also present in peptidomimetic therapeutics.

This study aimed to optimize the operating conditions and enhance the reaction rates of a hydrate-based gas separation process to facilitate environmentally friendly CO₂ capture from fuel gas (CO₂ + H₂) generated by natural gas reforming. Thermodynamic hydrate promoters, particularly tetrahydrofuran at 5.6 mol% and tetrabutylammonium bromide (TBAB) at 3.7 mol%, were used to alleviate strict equilibrium conditions and improve gas separation efficiency. To mitigate the effects of CO₂ solubility, the gas-to-water ratio was maintained at 0.1. In addition, the influence of memory water on accelerating gas hydrate formation was explored by monitoring the hydrate formation behavior and changes in gas composition under isobaric condition based on the re-measured phase equilibrium data. The results showed that while the memory effect significantly reduced the induction time for hydrate formation, it did not influence the growth behavior or CO₂ selectivity of the gas hydrates. Memory effect played a critical role in TBAB solution, particularly above the temperature required for pure clathrate formation. This study provides valuable insight into the roles of thermodynamic promoters and memory effects on the thermodynamic stability, induction time, and gas capture efficacy of gas hydrates, thereby contributing to the development of more efficient and environmentally sustainable gas separation technologies.

The biodegradable polymer poly(lactic acid) (PLA) is brittle. PLA‐based composites reinforced by indium selenide (InSe) particles or flakes are prepared; each is found to have outstanding plasticity. InSe nanosheets are prepared by sonication of solid InSe in N‐methyl pyrrolidone, followed by washing/dispersion in ethanol, and subsequent drying. These InSe nanosheets, or in separate studies InSe particles, are mixed with PLA to make composite materials. The PLA composite materials are 3D‐printed into “dogbone” samples that are tensile‐loaded. The optimum dogbone specimen is 1.5 times stronger and 5.5 times tougher than neat PLA specimens prepared in the same way. To the best of our knowledge, this concurrent improvement in tensile strength and toughness has not been achieved before in PLA with any filler type. Finite element analysis, together with experimental analysis of (i) fracture surfaces, (ii) the PLA crystal structure, and (iii) the internal structure by micro‐CT scanning, suggests that the exceptional mechanical performance is due to the intrinsic properties of InSe and, particularly, the emergence of crack shielding and crack deflection at the interfaces of PLA and InSe flakes. These findings indicate that PLA–InSe composites may offer opportunities to broaden the applications of PLA composites, including as load‐bearing materials.