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5,857 result(s) for "Lee, Jong Min"
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Interstitial boron-triggered electron-deficient Os aerogels for enhanced pH-universal hydrogen evolution
Developing high-performance electrocatalysts for hydrogen evolution reaction (HER) is crucial for sustainable hydrogen production, yet still challenging. Here, we report boron-modulated osmium (B-Os) aerogels with rich defects and ultra-fine diameter as a pH-universal HER electrocatalyst. The catalyst shows the small overpotentials of 12, 19, and 33 mV at a current density of 10 mA cm −2 in acidic, alkaline, and neutral electrolytes, respectively, as well as excellent stability, surpassing commercial Pt/C. Operando X-ray absorption spectroscopy shows that interventional interstitial B atoms can optimize the electron structure of B-Os aerogels and stabilize Os as active sites in an electron-deficient state under realistic working conditions, and simultaneously reveals the HER catalytic mechanisms of B-Os aerogels in pH-universal electrolytes. The density functional theory calculations also indicate introducing B atoms can tailor the electronic structure of Os, resulting in the reduced water dissociation energy and the improved adsorption/desorption behavior of hydrogen, which synergistically accelerate HER. While noble metals can be active electrocatalysts for producing renewable H 2 , there are relatively few works examining osmium materials. Here, the authors prepare boron-doped osmium aerogels for H 2 evolution electrocatalysis plus examine the mechanism using computational and in situ characterization.
The challenges and opportunities of a global health crisis: the management and business implications of COVID-19 from an Asian perspective
On March 11, 2020, the World Health Organization (WHO) declared the coronavirus (COVID-19) outbreak a pandemic. As the evolution and implications of the COVID-19 crisis are still unfolding, we posit that exploring the experiences and strategic responses of Asian countries may shed light on ways to combat COVID-19 for the rest of the world. In this paper, we first articulate the importance of resilience, strategic agility, and entrepreneurship in the context of the fight against COVID-19. Then, with the focus on China, South Korea, and Singapore, we discuss the impact COVID-19 is having on economies and businesses, governmental support for businesses and societies, and implications for global supply chain disruptions. We hope that the global health system will recover quickly, and that the world economy will be revitalized with the contributions and collaboration of science (including social science), industry, and governments.
BiVO4‐Based Photoelectrochemical Water Splitting
Photoelectrochemical water splitting is one of the most promising and appealing strategies for converting sunlight into sustainable hydrogen energy and has received increasing attention. Among the potential photocatalysts, BiVO4 has attracted particular attention as a photoanode material because of its appropriate bandgap (2.4 eV) and favorable band‐edge position. Moreover, its carrier mobility and hole‐diffusion length are modest, and the photocurrent density is below the theoretical expectation (7.5 mA cm−2). Recently, diverse strategies have been developed to improve the performance of BiVO4‐based photoanodes with rapid progress. In this article, engineering strategies including facet tailoring, intrinsic and extrinsic doping, surface modification, are summarized, and remaining challenges and perspective for the future research are provided. A review on BiVO4‐based photoanodes toward PEC water splitting is presented. Strategies modulating the facet and surface of BiVO4 in promoting charge transfer, boosting charge separation, increasing surface reaction kinetic and optimized optical property are comprehensively discussed, along with the major challenges and perspective for future research to improve the efficiency and stability of BiVO4‐based photoanodes.
White matter hyperintensities segmentation using the ensemble U-Net with multi-scale highlighting foregrounds
White matter hyperintensities (WMHs) are abnormal signals within the white matter region on the human brain MRI and have been associated with aging processes, cognitive decline, and dementia. In the current study, we proposed a U-Net with multi-scale highlighting foregrounds (HF) for WMHs segmentation. Our method, U-Net with HF, is designed to improve the detection of the WMH voxels with partial volume effects. We evaluated the segmentation performance of the proposed approach using the Challenge training dataset. Then we assessed the clinical utility of the WMH volumes that were automatically computed using our method and the Alzheimer's Disease Neuroimaging Initiative database. We demonstrated that the U-Net with HF significantly improved the detection of the WMH voxels at the boundary of the WMHs or in small WMH clusters quantitatively and qualitatively. Up to date, the proposed method has achieved the best overall evaluation scores, the highest dice similarity index, and the best F1-score among 39 methods submitted on the WMH Segmentation Challenge that was initially hosted by MICCAI 2017 and is continuously accepting new challengers. The evaluation of the clinical utility showed that the WMH volume that was automatically computed using U-Net with HF was significantly associated with cognitive performance and improves the classification between cognitive normal and Alzheimer's disease subjects and between patients with mild cognitive impairment and those with Alzheimer's disease. The implementation of our proposed method is publicly available using Dockerhub (https://hub.docker.com/r/wmhchallenge/pgs). [Display omitted]
Operando elucidation of hydrogen production mechanisms on sub-nanometric high-entropy metallenes
Precise morphological control and identification of structure-property relationships pose formidable challenges for high-entropy alloys, severely limiting their rational design and application in multistep and tandem reactions. Herein, we report the synthesis of sub-nanometric high-entropy metallenes with up to eight metallic elements via a one-pot wet-chemical approach. The PdRhMoFeMn high-entropy metallenes exhibit high electrocatalytic hydrogen evolution performances with 6, 23, and 26 mV overpotentials at −10 mA cm −2 in acidic, neutral, and alkaline media, respectively, and high stability. The electrochemical measurements, theoretical simulations, and operando X-ray absorption spectroscopy reveal the actual active sites along with their dynamics and synergistic mechanisms in various electrolytes. Specially, Mn sites have strong binding affinity to hydroxyl groups, which enhances the water dissociation process at Pd sites with low energy barrier while Rh sites with optimal hydrogen adsorption free energy accelerate hydride coupling, thereby markedly boosting its intrinsic ability for hydrogen production. High-entropy alloys are promising electrocatalysts for multistep and tandem reactions, yet its mechanism remains unclear. Here, the authors address this challenge by using in-situ XAS to reveal the multi-site hydrogen evolution mechanisms on high-entropy metallenes in wide pH electrolytes.
Long-lifetime water-washable ceramic catalyst filter for air purification
Particulate matter (PM) and volatile organic compounds (VOCs) are recognised as hazardous air pollutants threatening human health. Disposable filters are generally used for air purification despite frequent replacement and waste generation problems. However, the development of a novel regenerable and robust filter for long-term use is a huge challenge. Here, we report on a new class of facile water-washing regenerable ceramic catalyst filters (CCFs), developed to simultaneously remove PM (>95%) and VOCs (>82%) in single-pass and maximized space efficiency by coating the inner and outer filter channels with an inorganic membrane and a Cu 2 O/TiO 2 photocatalyst, respectively. The CCFs reveal four-fold increase in the maximum dust loading capacity (approximately 20 g/L) in relation to conventional filters (5 g/L), and can be reused after ten regeneration capability with simple water washing retaining initial PM and VOC removal performances. Thus, the CCFs can be well-suited for indoor and outdoor air purification for 20 years, which shows a huge increase in lifetime compared to the 6-month lifespan of conventional filters. Finally, we believe that the development and implementation of CCFs for air purification can open new avenues for sustainable technology through renewability and zero-waste generation. Disposable filters are generally used for air purification despite frequent replacement and waste generation problems. Here, a ceramic catalyst filter is introduced as a new class of filter that simultaneously removes PMs and VOCs as primary air pollutants and can be regenerated and used for long periods by simple water washing.
Contrast-enhanced T1-weighted image radiomics of brain metastases may predict EGFR mutation status in primary lung cancer
Identification of EGFR mutations is critical to the treatment of primary lung cancer and brain metastases (BMs). Here, we explored whether radiomic features of contrast-enhanced T1-weighted images (T1WIs) of BMs predict EGFR mutation status in primary lung cancer cases. In total, 1209 features were extracted from the contrast-enhanced T1WIs of 61 patients with 210 measurable BMs. Feature selection and classification were optimized using several machine learning algorithms. Ten-fold cross-validation was applied to the T1WI BM dataset (189 BMs for training and 21 BMs for the test set). Area under receiver operating characteristic curves (AUC), accuracy, sensitivity, and specificity were calculated. Subgroup analyses were also performed according to metastasis size. For all measurable BMs, random forest (RF) classification with RF selection demonstrated the highest diagnostic performance for identifying EGFR mutation (AUC: 86.81). Support vector machine and AdaBoost were comparable to RF classification. Subgroup analyses revealed that small BMs had the highest AUC (89.09). The diagnostic performance for large BMs was lower than that for small BMs (the highest AUC: 78.22). Contrast-enhanced T1-weighted image radiomics of brain metastases predicted the EGFR mutation status of lung cancer BMs with good diagnostic performance. However, further study is necessary to apply this algorithm more widely and to larger BMs.
Whole-brain Functional Networks in Cognitively Normal, Mild Cognitive Impairment, and Alzheimer’s Disease
The conceptual significance of understanding functional brain alterations and cognitive deficits associated with Alzheimer's disease (AD) process has been widely established. However, the whole-brain functional networks of AD and its prodromal stage, mild cognitive impairment (MCI), are not well clarified yet. In this study, we compared the characteristics of the whole-brain functional networks among cognitively normal (CN), MCI, and AD individuals by applying graph theoretical analyses to [(18)F] fluorodeoxyglucose positron emission tomography (FDG-PET) data. Ninety-four CN elderly, 183 with MCI, and 216 with AD underwent clinical evaluation and FDG-PET scan. The overall small-world property as seen in the CN whole-brain network was preserved in MCI and AD. In contrast, individual parameters of the network were altered with the following patterns of changes: local clustering of networks was lower in both MCI and AD compared to CN, while path length was not different among the three groups. Then, MCI had a lower level of local clustering than AD. Subgroup analyses for AD also revealed that very mild AD had lower local clustering and shorter path length compared to mild AD. Regarding the local properties of the whole-brain networks, MCI and AD had significantly decreased normalized betweenness centrality in several hubs regionally associated with the default mode network compared to CN. Our results suggest that the functional integration in whole-brain network progressively declines due to the AD process. On the other hand, functional relatedness between neighboring brain regions may not gradually decrease, but be the most severely altered in MCI stage and gradually re-increase in clinical AD stages.
Effect of fascial closure using barbed sutures on incisional hernias in midline laparotomy for gynecological diseases: A multicenter randomized controlled trial (KGOG 4001)
To identify the effect of fascial closure using barbed sutures on the incidence of incisional hernia in patients undergoing elective midline laparotomy for gynecological diseases. In this multicenter, non-blind randomized controlled trial conducted from February to December 2021, patients with a BMI < 35 kg/m2 and aged >18 years, scheduled for midline laparotomy, were randomly assigned to receive either barbed (experimental) or non-barbed sutures (control) for fascial closure. The primary outcome was the cumulative incidence rate of incisional hernia up to 1-year post-surgery. Secondary outcomes included incisional hernia up to 2-years post-surgery, wound complications, and postoperative pain assessed by Brief Pain Inventory-Korean scores, and Numeric Rating Scale. Out of 174 patients (experimental, 86; control, 88), 36 were excluded due to dropout or loss to follow-up, leaving 138 patients (experimental, 67; control, 71) included in the analysis. The groups were balanced in terms of cancer surgeries, mean wound length, and mean surgery time. The cumulative incidence rates of incisional hernia up to 1-year (0.0% vs. 1.4%; p > 0.999) and 2-years (0.0% vs. 3.4%, p = 0.496) post-surgery did not differ significantly between the experimental and control groups. Additionally, no significant differences were observed in the incidence of wound dehiscence 4 weeks post-surgery, cumulative incidences of wound dehiscence and wound infection up to 4 weeks post-surgery, or postoperative pain scores between the groups. Fascial closure using barbed sutures resulted in no cases of incisional hernia up to 2-years post-surgery, but did not demonstrate a significant reduction in incisional hernia rates compared with the non-barbed suture. ClinicalTrials.gov NCT04643197.
Trimetallic Au@PdPb nanowires for oxygen reduction reaction
The development of highly efficient and stable Pd-based catalysts is crucial to improve their sluggish oxygen reduction reaction (ORR) kinetics in acid media. To improve ORR activity and utilization efficiency of Pd, an ideal catalyst should have ORR-favorable chemical environment, optimized geometric structure, and long periods of operation. In this work, we first synthesize a novel trimetallic Au@PdPb core-shell catalyst consisting of PdPb alloy nano-layers grown on the surface of ultrathin Au nanowires (NWs) by a two-step water-bath method. The Au@PdPb NWs have the merits of anisotropic one-dimensional nanostructure, high utilization efficiency of Pd atoms and doping of Pb atoms. Because of the structural and multiple compositional advantages, Au@PdPb NWs exhibit remarkably enhanced ORR activity with a high half-wave potential (0.827 V), much better than those of commercial Pd black (0.788 V) and bimetallic Au@Pd NWs (0.803 V). Moreover, Au@PdPb NWs display better electrocatalytic stability for the ORR than those of Pd black and Au@Pd NWs. This study demonstrates the validity of our approach for deriving highly ORR-active Pd-based catalysts by modifying their structure and composition.