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Superior catalytic activity for dry reforming of methane: Ni-incorporated in silica supports by framework ligands
No full textThe dry reforming of methane (DRM) presents a promising approach to converting greenhouse gases into valuable syngas. However, catalyst deactivation due to sintering and carbon deposition remains a significant challenge. For stable DRM catalysts, this study introduces Ni-incorporated into ligand-controlled silica (NILS) catalysts through precise control of silica frameworks. The NILS series catalysts were synthesized by a combined sol-gel and re-precipitation method, in which catalyst structure, properties and performance controlled by silica framework precursors containing C1 to C4 carbon chains (tetramethyl orthosilicate (C1, TMOS), tetraethyl orthosilicate (C2, TEOS), tetrapropyl orthosilicate (C3, TPOS) and tetrabutyl orthosilicate (C4, TBOS). The most complex ligand (C4) enhanced catalyst properties by three key mechanisms: (1) uniform nano-sized nickel clusters formed through slower sol-gel reactions, (2) increased surface hydroxyl groups promoting metal-support interactions and (3) development of bimodal pore structures facilitating efficient mass transport. The TBOSderived catalyst (NILS-B) achieved exceptional stability, maintaining 95% CH4 and 97% CO2 conversions over 40 h at 800 degrees C without deactivation. This performance is attributed to synergistic effects of nano-sized Ni clusters, hydroxylated Ni species, and optimized pore structure. This study provides fundamental understanding of framework ligand effects and demonstrates a practical approach for designing stable Ni-SiO2 catalysts through simple one-pot synthesis without complex modifications or additional promoters.FALSEsciescopu
A dual-channel self-amplifying lateral flow immunoassay for the on-site ultrasensitive simultaneous detection of salivary cortisol and melatonin
No full textThe on-site simultaneous measurement of cortisol and melatonin is valuable for comprehensively assessing circadian rhythms and understanding their complex interplay under physiological conditions. However, no commercial point-of-care test currently enables the concurrent detection of these salivary hormones. Consequently, there is a significant demand for an on-site, user-friendly diagnostic platform. While the lateral flow immunoassay (LFI) is widely used in point-of-care testing, its sensitivity is insufficient for detecting salivary cortisol and melatonin. To overcome this limitation, the self-amplifying LFI (saLFI) developed previously for salivary cortisol detection, is extended to enable salivary melatonin detection in combination with a gold enhancement method. Two saLFIs are integrated into a single device using a dual-channel sample pad, creating a dual-channel self-amplifying lateral flow immunoassay (2ch-saLFI). This integrated dual-channel sample pad provides an equal distribution of the sample solution to two strips and two self-amplifying complexes. Consequently, the novel 2ch-saLFI enables the simultaneous on-site detection of both hormones from a single sample injection, delivering results within 30 min. The 2ch-saLFI demonstrates a high sensitivity, with detection limits of 5.39 and 0.476 pg mL- 1 for cortisol and melatonin, respectively (i.e., below typical physiological levels). Validation using 20 clinical samples provides a strong correlation with standard ELISA methods (R2 = 0.9017 for cortisol and 0.9101 for melatonin). Overall, the 2ch-saLFI represents the first point-of-care test enabling the onFALSEsciescopu
Enhanced plasma wave excitation in a tapered plasma channel through chirped laser beatwaves
No full textThe excitation of plasma waves by the beatwave of two-color laser beams within a tapered plasma channel has been investigated both analytically and through particle-in-cell (PIC) simulations. This study presents a promising approach for beatwave accelerators. The design aims to achieve a more stable and enhanced plasma wave amplitude, even under non-resonant conditions, compared to untapered channels. For the analytical description, we solved the plasma wave equation generated by two beating laser beams propagating through a tapered channel with a linear radial density profile. The study further validates its results by comparing the analytical predictions with PIC simulations of the beatwave phenomenon in the tapered channel. The findings confirm that this design significantly enhances plasma wave amplitude compared to untapered channels. In addition, we demonstrated that employing a chirped laser pulse with a fast rise time can significantly increase the strength of the plasma wave. © 2025 Author(s).TRUEsciescopu
Discovery of Novel BKCa Channel Activators as Smooth Muscle Relaxants and TPST2 Inhibitors as Immuno-Oncology Therapeutics
No full textTo address unmet medical needs in both smooth muscle disorders and cancer immunotherapy, this dissertation describes the identification and development of small-molecule modulators against two mechanistically distinct targets, the BKCa (large-conductance calcium-activated potassium) channel and the tyrosylprotein sulfotransferase 2 (TPST2) enzyme. As Part 1, we report the identification and optimization of novel BKCa channel activators based on a diphenyl ether scaffold. Starting from the screening hit compound 4d, structure–activity relationship (SAR) studies led to the discovery of compound 10b, which exhibited potent activity in cell-based assays (EC50 = 0.12 μM) and demonstrated in vivo efficacy in a spontaneous hypertensive rat (SHR) model of urinary incontinence. Furthermore, an orally bioavailable analog, compound 51b, showed dose-dependent efficacy in a citric acid-induced guinea pig cough model (ED50 = 11.8 mg/kg). The cryo-electron microscopy (cryo-EM) structures of the BKCa channel in complex with 10b and 51b were resolved at 2.8 Å and 3.4 Å, respectively, providing mechanistic insights into ligand-induced channel activation. As Part 2, we describe the discovery and biological evaluation of a novel TPST2 inhibitors. Optimization of the initial hit compound 44a yielded 77c, with an IC50 value of 946 nM. Through in silico docking analyses and molecular dynamic (MD) simulations, we proposed a putative binding mode of 77c for the TPST2 enzyme. In vivo, 77c suppressed tumor growth in the MC38 syngeneic mouse model and enhanced the efficacy of anti-PD-1 immune checkpoint therapy. These effects were accompanied by increased infiltration of effector CD8+ T cells and systemic immune activation, supporting its potential as a combination immunotherapy agent.DoctorABSTRACT 5
CONTENTS 6
LIST OF SCHEMES AND TABLES 24
LIST OF FIGURES 26
PART I. Discovery of Diphenyl Ether Derivatives as Novel BKCa Channel Activators 28
ABSTRACT 29
INTRODUCTION 30
MATERIALS AND METHODS 34
RESULTS AND DISCUSSION 74
CONCLUSION 111
REFERENCES 112
ABSTRACT IN KOREAN 119
PART 2. Discovery of (4-Phenyl-cyclohexyl)acetate-Based Tyrosylprotein Sulfotransferase 2 (TPST2) Inhibitors as Novel Immuno-Oncology Therapeutics 120
ABSTRACT 121
INTRODUCTION 122
MATERIALS AND METHODS 125
RESULTS AND DISCUSSION 196
CONCLUSION 246
REFERENCES 247
ABSTRACT IN KOREAN 251
ACKNOWLEDGMENTS 25
Investigation of enhanced thermal oxidative stability of nanoparticle organic hybrid materials for DAC
No full textA Dual-Branch Spatio-Temporal Feature Differencing Method for Robust rPPG Estimation
No full textRemote photoplethysmography (rPPG) is a non-contact technology that estimates physiological signals, such as Heart Rate (HR), by capturing subtle skin color changes caused by periodic blood volume variations using only a standard RGB camera. While cost-effective and convenient, it suffers from a fundamental limitation: performance degrades severely in dynamic environments due to susceptibility to noise, such as abrupt illumination changes or motion blur. This study presents a deep learning framework that combines two structural modifications to ensure robustness in dynamic environments, specifically modeling movement noise and illumination change noise. The proposed framework structurally cancels global disturbances, such as illumination changes or global motion, through a dual-branch pipeline that encodes the face and background in parallel after Video Color Magnification (VCM) and then performs differencing. Subsequently, it utilizes a structure that injects a Temporal Shift Module (TSM) into the Spatio-Temporal Feature Extraction (SSFE) block to preserve long- and short-term temporal correlations and smooth noise, even amidst short and irregular movements. We measured MAE, RMSE, and correlation on the standard dataset UBFC-rPPG under four noise conditions: clean, illumination change noise, Movement Noise, Both Noise and the real-world in-vehicle dataset MR-NIRP (Stationary and Driving). Experimental results showed that the proposed method achieved consistent error reduction and correlation improvement compared to the VS-Net baseline in the illumination change noise-only and combined noise environments (UBFC-rPPG) and in the high-noise driving scenario (MR-NIRP). It maintained competitive performance in motion-only noise. Conversely, a modest performance disadvantage was observed under clean conditions (UBFC) and quasi-clean stationary conditions (MR-NIRP), interpreted as a design trade-off focused on global noise cancellation and temporal smoothing. Ablation studies demonstrated that the dual-branch pipeline is the primary contributor under illumination change noise, while TSM is the key contributor under movement noise, and that the combination of both elements achieves optimal robustness in the most complex scenarios.TRUEsciescopu
Active metal cation exchanged in ZSM-5 for enhanced direct air capture of CO2
No full textZeolites have proved their potential as cost-effective adsorbents for CO2 capture; further development is worth optimizing their performance for large-scale direct air capture (DAC) applications. In this study, ZSM-5 zeolites were prepared and exchanged with alkali cations (Na and K) and alkaline earth cations (Mg, Ca and Ba) to investigate their performances for the CO2 capture from atmospheric air in the DAC system. We found that the cation charge density is critical to determining the DAC capacity of ZSM-5 zeolites. In detail, ZSM-5 with a low cation charge density (e.g., K+ with a charge density of 0.39) struggles to effectively capture CO2 at low concentrations since CO2 adsorption relies on electrostatic interactions with quadrupole CO2 by cation charge density. Conversely, an excessively high cation charge density has a detrimental effect as adsorption sites become shielded by H2O and CO2 on cations (e.g., Ca2+ and Mg2+ with charge densities of 2.06 and 7.28, respectively), reducing the accessible CO2 capacity. Consequently, Ba-ZSM-5, featuring Ba2+ with a moderate charge cation density of 0.81, exhibits the highest DAC capacity (500 ppm CO2 in the air at RH 13%, 0.4 mmol g−1), with fast kinetics and stable reproducibility, appealing that appropriate cation charge density is critical to imparting the high DAC capacity of ZSM-5 zeolites. In addition, DRIFTS results confirmed the moisture swing adsorption behavior, in which the adsorbed CO2 is desorbed directly by water over Ba-ZSM-5. These results provide valuable insights for the design of zeolites-based DAC systems. © 2024 Elsevier B.V.FALSEsciescopu
Cost-Effective Electrode Fabrication Method Using Hydroxypropyl Methylcellulose Binder for Proton Exchange Membrane Water Electrolysis
No full textThis study explores improving proton exchange membrane water electrolysis (PEMWE) by achieving both cost-effectiveness and enhanced efficiency through the replacement of the costly and environmentally challenging Nafion ionomer with hydroxypropyl methylcellulose (HPMC) as an anode binder. HPMC, an eco-friendly and cost-effective material, was cross-linked with citric acid to form a durable hydrogel that enhances water and proton transport within the catalyst layer. Using the cross-linked HPMC binder allowed a reduction in cost to 1/54 compared to Nafion ionomer, while the performance of the cross-linked HPMC electrodes remained comparable to Nafion electrodes. After investigating with varying temperatures to determine the appropriate cross-linking temperature, it is suggested that 140 °C was the most suitable. The cross-linked HPMC demonstrated superior hydrophilicity and ionic conductivity compared to the Nafion ionomer, demonstrating its potential as a viable alternative. Initial performance in the single cell revealed that the HPMC-based anode outperformed the Nafion-based anode, with a voltage of 1.782 V vs 1.796 V at 2 A/cm2. However, despite this improved initial performance, the higher voltage decay rate of the HPMC binder (0.305 mV/h vs 0.250 mV/h) over 200 h indicates the need for further elaboration on its long-term durability. These findings suggest that the cross-linked HPMC holds promise as a cost-effective and efficient binder for PEMWE anodes, with the potential for further optimization for durability. © 2025 American Chemical Society.FALSEsciescopu
Preferential cage occupation of CH4 into clathrate hydrate for selective CH4 enrichment from hydrogen-natural gas blends
No full textHydrogen (H2) energy, recognized as a viable alternative source for decarbonization, requires effective transport solutions. Blending hydrogen into natural gas pipelines, forming hydrogen-natural gas blends (HNGB), offers a promising bridging technology toward a low-carbon future. However, high-purity methane (CH4) separation remains crucial for existing natural gas infrastructure. Thus, this study explores gas hydrates as a potential CH4 enrichment media, with employing thermodynamic promoters, tetrahydrofuran (THF), 1,3-dioxolane (DIOX), and 1,3-dioxane (Dioxane), to alleviate thermodynamic formation conditions. Since promoters occupy large cages, promoters inevitably limit CH4 occupancy. Hence, the tuning effect, which can allow CH4 in empty large cages by adjusting promoter concentration, was proposed as a novel approach to enhance CH4 selectivity. In this study, we adjusted promoter concentrations from 5.6 mol% to 4.0 mol% to investigate CH4 selectivity via tuning effect from simulated HNGB, CH4 (80%) + H2 (20%) under conditions of 284.15 K and 7.0 MPa. Thermodynamic stability analysis revealed that THF exhibited the superior promotion effect. Synchrotron XRD confirmed that all promoters at varying concentrations formed sII hydrate. Furthermore, Raman and 13C solid-state NMR analyses provided evidence of enhanced CH4 occupancy in the sII-L, with DIOX (4.0 mol%) achieving a CH4 purity of 99.30 mol% in the hydrate phase. These findings demonstrate that tuning effect can increase CH4 selectivity within the hydrate phase, presenting a promising approach for CH4 enrichment from HNGB. Therefore, we believe that our findings can provide valuable insights into potential hydrate-based separation technology, especially for CH4 enrichment for future transition toward sustainable energy systems.FALSEsciescopu