Gwangju Institute of Science and Technology

The development of heterogeneous metal oxide catalysts for transesterification reactions is crucial owing to their seamless reusability and environmental friendliness. In recent years, numerous studies have been conducted on rare-earth oxides, such as lanthanide metal oxides. Various metal oxides were screened for transesterification using a new fluorescence-based high-throughput screening (HTS) method with a pyrene excimer probe, bis(4-(1-pyrenyl)butyl) maleate (BPBM). Praseodymium(iv) oxide (PrO2) yielded the highest catalytic activity among the prepared metal oxides. Various substrates were successfully transesterified, and biodiesel was produced in a high yield (90%) from soybean oil through transesterification using the catalyst. The selected catalyst required minimal amounts for the transesterification of various organic substrates (0.7 mol%) and soybean oil (0.8 wt%).

High‐entropy nanoparticles (HENPs) present a vast opportunity for the development of advanced electrocatalysts. The optimization of their chemical compositions, including the careful selection and combination of elements, is critical to tailoring HENPs for specific catalytic processes. To reduce the extensive experimental effort involved in composition optimization, active learning techniques can be utilized to predict and suggest materials with enhanced electrocatalytic activity. In this study, sub‐2 nm high‐entropy catalysts incorporating eight transition metal elements are developed through an active learning workflow aimed at identifying optimal compositions. Using initial experimental data, the approach successfully guided the discovery of a new octonary HENP catalyst with state‐of‐the‐art performance in the hydrogen evolution reaction (HER). Catalyst performance is improved within the prediction uncertainty of the machine learning model. For the oxygen evolution reaction (OER), however, the initial model demonstrated limited predictive accuracy, leading to an assessment of the workflow's boundaries. These findings underscore how the integration of curated experimental data with active learning can accelerate electrocatalyst discovery, while also highlighting critical areas for further model refinement.

Developing high‐performance n‐type organic mixed ionic‐electronic conducting (OMIEC) polymers with simple structural motifs is still challenging. We show that high‐performance, low‐threshold‐voltage n‐type OMIEC polymers can be achieved using a simple diketopyrrolopyrrole unit flanked by thiazole groups, which is functionalized with glycolated side chains. Interestingly, the regiospecific sp2‐N position in the repeating unit's thiazole governs the polymer chains' solvation and molecular packing. This specific backbone chemistry enhances conjugation efficiency, reduces trap density, and improves electrochemical doping efficiency. Moreover, systematic variation of glycolated side‐chain lengths induces a sequential shift in molecular orientation—from edge‐on through bimodal to face‐on preferential alignment. This structural evolution achieves optimized ionic‐electronic transport balance, resulting in exceptional device metrics: a geometrically normalized transconductance of 31.9 S cm‐1, a figure‐of‐merit μC* of 96.3 F cm‐1 V‐1 s‐1, and a threshold voltage of 0.31 V, positioning these materials among the highest‐performing n‐type OMIECs. An organic complementary inverter made from the optimized n‐type OMIEC polymer and a reported p‐type polymer exhibits a voltage gain of 198 VV‐1, effectively amplifying the ECG signal and enhancing signal quality. This work establishes structure‐property guidelines for designing bioelectronic n‐type OMIECs.

Cellular senescence, a process that induces irreversible cell cycle arrest in response to diverse stressors, is a primary contributor to aging and age-related diseases. Currently, exposure to hydrogen peroxide is a widely used technique for establishing in vitro cellular senescence models; however, this traditional method is inconsistent, laborious, and ineffective in vivo. To overcome these limitations, we have developed a hydrogen peroxide-releasing hydrogel that can readily and controllably induce senescence in conventional 2-dimensional cell cultures as well as advanced 3-dimensional microphysiological systems. Notably, we have established 2 platforms using our hydrogen peroxide-releasing hydrogel for investigating senolytics, which is a promising innovation in anti-geronic therapy. Conclusively, our advanced model presents a highly promising tool that offers a simple, versatile, convenient, effective, and highly adaptable technique for inducing cellular senescence. This innovation not only lays a crucial foundation for future research on aging but also markedly accelerates the development of novel therapeutic strategies targeting age-related diseases.

Organic micropollutants in drinking water can pose a public health risk. Chemical analysis alone cannot capture the full range of contaminants or assess their associated risks, promoting the growing use of bioanalytical tools as a complementary approach. This study assessed a drinking water treatment plant in the Nakdong River basin, Korea, using in vitro bioassays targeting nine endpoints. The highest estrogen receptor (ERα) activity was observed in the influent and significantly decreased throughout treatment. Bioactivities related to xenobiotic metabolism (PAH, PPARγ, and PXR) and oxidative stress response (Nrf2) initially increased during pre-oxidation but decreased in later treatment stages. An increase in p53 activity was also noted during treatment. Both season and treatment processes were found to affect the bioactivity variation for most endpoints, based on correlation analysis. The bioactivities observed were consistent with those reported for treated drinking waters in other countries. PAH, PPARγ, PXR, and Nrf2 activities in the final treated waters exceeded some effect-based trigger (EBT) values, indicating potential risks, although uncertainty remain regarding the EBT values for PPARγ and PXR. Additionally, the bioanalytical equivalent concentrations of volatile disinfection byproducts detected after pre- and post-chlorination were lower than the measured Nrf2 activities by factors of 7.5 and 5.5, respectively. This study highlights the importance of monitoring of bioactive chemicals to safeguard public health and ecosystems, underscoring the value of in vitro bioassays in water quality assessment.

Myocardial infarction (MI) stands as a prominent contributor to global mortality. Despite existing therapies, there are notable shortcomings in delivering optimal cardiac support and reversing pathological progression, particularly within early stages. Adenosine presents a promising therapeutic target; however, its clinical utility is impeded by inherent limitations. In this study, an advanced strategy using adenosine agonist is pioneered to ameliorate MI‐induced myocardial damage. Herein, an adenosine derivative 5′‐(N‐ethylcarboxamido) adenosine (NECA) is employed, and its therapeutic efficacy is evaluated via single local delivery into infarcted myocardium following MI. NECA displays remarkable benefits in endothelial cells and cardiomyocytes under both normoxic and hypoxic conditions. Likewise, single localized NECA delivery via newly developed NECA‐loaded micro‐depots demonstrates advanced improvement in cardiac function and prevention of myocardial damage in a MI mouse model, with notable promotion of angiogenesis and suppression in inflammation, oxidation, and apoptosis. Mechanistically, NECA exerts myocardial benefits via the enhancement of mitostasis by triggering AMP‐activated protein kinase α (AMPKα) phosphorylation and Peroxisome proliferator‐activated receptor gamma coactivator 1‐alpha(PGC‐1α) activation. These findings highlight the clinical significance of adenosine agonist NECA in cardiac support and recovery, with the single‐delivered depots providing an advanced intervention for individuals with critically severe MI in the early phase.

Lactate dehydrogenase A is a key enzyme in energy metabolism, with significant roles in cancer progression. Huang et al. identified LDHAα, a novel LDHA isoform derived from an alternative transcript initiated at AUG198, producing a protein 3 kDa larger than canonical LDHA. LDHAα exhibits enhanced glycolytic activity and promotes glucose uptake, lactate production, and tumor growth more effectively than LDHA. Regulated by c‐MYC and FOXM1, LDHAα is mainly cytoplasmic and serves as a potential cancer biomarker and therapeutic target. These findings highlight LDHAα's unique role in cancer metabolism and its potential for advancing targeted cancer therapies. Comment on: https://doi.org/10.1111/febs.17374. image

The ultrafast manipulation of molecular states by charge transfer is essential for characterizing and controlling molecular dynamics. In this study, we demonstrated exciton formation in a single molecule through ultrafast electron tunneling processes between a molecule and a metal tip of a scanning tunneling microscope (STM) using a phase-controlled terahertz (THz) pulse. The pronounced luminescence of the well-defined molecular system under the distinct carrier-envelope phase of the THz pulse revealed that sequential state-selective electron-tunneling processes to the frontier molecular orbitals promoted ultrafast exciton formation in the molecule at the STM junction. Furthermore, ultrafast control of exciton formation was achieved using phase- and delay-controlled THz pulse pairs, providing a route for the regulation of molecular dynamics and the emergence of new molecular functions.

Background β2‐Microglobulin (B2M) has garnered considerable interest as a potential pro‐ageing factor, leading to speculation about its involvement in muscle metabolism and the development of sarcopenia, a key component of ageing phenotypes. To explore this hypothesis, we conducted a comprehensive investigation into the impact of B2M on cellular and animal muscle biology, as well as its clinical implications concerning sarcopenia parameters in older individuals. Methods In vitro myogenesis was induced in mouse C2C12 myoblasts with 2% horse serum. For in vivo research, C57BL/6 mice aged 3 months were intraperitoneally given 250 μg of B2M daily, and muscular alterations were assessed one month later. Human blood samples were obtained from 158 participants who underwent assessments of muscle mass and function at an outpatient geriatric clinic affiliated with a teaching hospital. Sarcopenia and associated parameters were assessed using cut‐off values specifically tailored for the Asian population. The concentration of serum B2M was quantified through an enzyme‐linked immunosorbent assay. Results Recombinant B2M inhibited in vitro myogenesis by increasing intracellular reactive oxygen species (ROS) production. Furthermore, B2M significantly induced differential myotube atrophy via ROS‐mediated ITGB1 downregulation, leading to impaired activation of the FAK/AKT/ERK signalling cascade and enhanced nuclear translocation of FoxO transcription factors. Animal experiments showed that mice with systemic B2M treatment exhibited significantly smaller cross‐sectional area of tibialis anterior and soleus muscle, weaker grip strength, shorter grid hanging time, and decreased latency time to fall off the rotating rod, compared to untreated controls. In a clinical study, serum B2M levels were inversely associated with grip strength, usual gait speed and short physical performance battery (SPPB) total score after adjustment for age, sex, and body mass index, whereas sarcopenia phenotype score showed a positive association. Consistently, higher serum B2M levels were associated with higher risk for weak grip strength, slow gait speed, low SPPB total score, and poor physical performance. Conclusion These results provide experimental evidence that B2M exerted detrimental effects on muscle metabolism mainly by increasing oxidative stress. Furthermore, we made an effort to translate the results of in vitro and animal research into clinical implication and found that circulating B2M could be one of blood‐based biomarkers to assess poor muscle health in older adults.

Photoluminescence quantum yield (PLQY) losses in inorganic perovskite nanocrystals (PeNCs) due to ligand desorption hamper high external quantum efficiencies (EQE) in corresponding perovskite light‐emitting devices (PeLEDs). Their low PLQYs derive mainly from ligand desorption during device fabrication. Post‐synthesis treatments contribute to inefficiently adsorbed ligands due to their unfavorable chemical environments. Here the acid/base dynamics of treatments are investigated by applying a chemoselective and aprotic‐driven ligand exchange strategy that favors neutral environments, in lieu of traditional acid‐mediated strategies. Mild ligand‐extracting reagents (LERs) are utilized to gently extract native anchoring ligands with their cations, while their anions temporarily passivate the PeNC's surface, ensuring steady colloidal stability. By applying tri‐ethyloxonium tetrafluoroborate (TET) as the LER, PeNCs films displayed PLQYs as high as 92.8%. When paired with the widely‐employed di‐dodecyldimethylammonium bromide (DDAB) ligand, PeLED devices based on TET‐treated PeNCs exhibited a maximum EQE of 22.94% for emissions at λ = 512 nm. The work highlights the versatility of ligand exchange processes by assessing their overall governing factors.

A novel method to determine when the laser ablation crater reaches the interface between layers in real time during the high-resolution laser processing of multilayer thin films is reported. Femtosecond laser-induced breakdown spectroscopy (LIBS; wavelength = 343 nm, pulse duration = 550 fs) was adopted to predict the interface location during laser ablation with lateral (~ 3 μm) and depth (~ 250 nm) resolutions typically required for thin-film products in the industry. Rather than identifying the intersection of the intensity profiles of the upper and lower layers, the laser shot at which the LIBS signal intensity of the lower-layer material exceeded the noise level was monitored in the proposed method. A procedure for estimating the noise level excluding non-noise peaks from the measured LIBS spectrum was introduced. It was shown that the proposed method can accurately predict when the ablation crater reaches the interface between layers by using a single LIBS spectrum even when the LIBS signal intensity fluctuates highly owing to the low pulse energy to achieve the desired spatial resolutions. Averaging of the LIBS spectra was not necessary to reduce noise, as is generally the case with noisy LIBS data. The accuracy of the proposed method was verified experimentally by examining the cross-section of an ablation crater produced with a focused ion beam. This revealed that the center of the ablation crater reached the interface, and a shallow layer near the top of the lower film was ablated at the laser shot number predicted by the proposed method.

Solid‐state refrigeration based on the electrocaloric (EC) effect has recently been applied to thermal management for humans and electronics due to its low power consumption, zero carbon emissions, and compact size. However, the temperature span of the EC device is limited by the adiabatic temperature change (ΔTad) of the caloric materials. Moreover, significant ΔTad performance in high‐temperature environments, such as strong sunlight or parasitic heat sources, has yet to be demonstrated. In this study, a novel radiative heat sink/source‐integrated electrocaloric (R‐iEC) thermal regulation system is presented that overcomes the inherent heat dissipation limitations of the EC devices by using outer space as a reliable and sustainable heat sink. To effectively dissipate parasitic heat, a nonmetallic thermally conductive radiative cooler (TCRC) is implemented with a high thermal conductivity of 1.1 W mK⁻¹ and exceptional spectral features, including solar reflectivity of ≈96% and emissivity of ≈95% in the atmospheric window region. The R‐iEC system fortified with TCRC demonstrates superior heat dissipation compared to conventional radiative coolers, providing an additional cooling heat flux of 87 W m⁻². Under high‐temperature conditions with heat fluxes exceeding 770 W m⁻², this improvement results in a maximum heat dissipation performance of 240 W m⁻², surpassing that of conventional metal heat sinks.

We demonstrate a diode-pumped Ti:sapphire laser capable of producing high-energy femtosecond pulses via cavity dumping. Four spectrally combined diodes were used to pump the Ti:sapphire laser directly, which was mode-locked using a semiconductor saturable absorber mirror. At a repetition rate of 100 kHz using a cavity dumper, 172 nJ and 95 fs pulses were generated, corresponding to a pulse peak power of 1.8 MW. The signal-to-noise ratio at the 100 kHz dumped frequency exhibited an extinction ratio exceeding 55 dB relative to the carrier. To the best of the authors’ knowledge, this is the highest pulse energy obtained using a direct diode-pumped Ti:sapphire laser.