SuFEx in Metal-Organic Frameworks: Versatile Postsynthetic Modification Tool

A new type of click reaction, sulfur(VI) fluoride exchange (SuFEx), has been utilized to prepare five postsynthetically modified UiO-67 series metal-organic frameworks (MOFs). The postsynthetic modification (PSM) via SuFEx can be achieved selectively for the sulfonyl fluoride (R-SO2F) without degrading the MOF structure as confirmed by X-ray crystallographic analysis. The present SuFEx method provides a straightforward tool for introducing new functionality inside MOFs. Introduction of an imidazolium group into the MOF afforded a heterogeneous catalyst for the benzoin condensation reaction. © 2018 American Chemical Societ

An n-heterocyclic-carbene-tetracyanoethylene zwitterion: Experimental and theoretical study on its formation and reactivity

The direct addition of tetracyanoethylene (TCNto the carbene center of 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPwas successfully demonstrated. The IPr-TCNE adduct, that is, zwitterion 1, clearly differs from the typical [2+1]-cycloaddition products obtained from the reaction of carbenes with olefins. The results obtained from experimental and theoretical studies suggest that adduct 1 disassembles into IPr and TCNE, which is followed by the addition of IPr to the nitrile carbon atom of TCNE and subsequent isomerization into a thermodynamically more stable singlet nitrene intermediate. This intermediate is then captured by an additional molecule of TCNE to afford another heterocycle. This study reveals a unique example of the reactivity between N-heterocyclic carbenes and olefins. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim11sciescopu

Detecting and Identifying Faulty IoT Devices in Smart Home with Context Extraction

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Facile Synthesis of Wafer-Scale Single-Crystal Graphene Film on Atomic Sawtooth Cu Substrate

© The Korean Vacuum Society. Wafer-scale single-crystal (SC) graphene film is highly required for industrial applications including electronic, photonic, and optoelectronic devices. While SC graphene film has been successfully synthesized on SC Cu (111) or H-Ge (110) substrates, preparation methods of SC growth substrate are still not practical. Here, we report the facile synthesis of wafer-scale SC graphene film on atomic sawtooth Cu substrate by means of chemical vapor deposition. Atomic sawtooth Cu substrates are prepared by melting Cu foils on W foils and solidifying them. The substrates are subsequently employed for synthesis of SC graphene without formation of grain boundaries. The electron diffraction patterns, visualized by transmission electron microscopy, reveal that graphene film has the same lattice orientation over the whole region. Furthermore, Raman mapping measurement demonstrates the homogeneity of the optical property of SC graphene films. Our method provides a new route for the synthesis of SC graphene, as well as other two-dimensional materials. © 2023, Korean Vacuum Society. All rights reserved.11Nscopuskc

Improved survival rates in patients with H1N1 acute respiratory failure in Korea between 2009 and 2016.

There was a pandemic of influenza A (H1N1) in 2009; in Korea, there was also an H1N1 epidemic in 2016. We aim to investigate whether survival had improved in the setting of recent advances in intensive care unit (ICU) management. We conducted a retrospective analysis of acute respiratory failure patients with H1N1 influenza pneumonia in 2016 and 2009 respectively at two tertiary referral hospitals in Korea. A total of 28 patients were treated in 2016, and 34 in 2009. There was no significant difference in SOFA scores on ICU admission day. In-hospital mortality was significantly lower in patients of 2016 compared to those of 2009 (18% vs. 44% P = 0.028). By multivariable analyses, the treatment year 2016 was associated with a greater likelihood of survival. Compared to the patients treated in 2009, those treated in 2016 were one seventh as likely to die after adjusting for other clinical variables (hazard ratio for mortality, 0.15; 95% confidence interval. 0.03-0.63, P = 0.010). Improved survival in patients who underwent extracorporeal membrane oxygenation treatment (in-hospital mortality, 17% vs. 60%, P = 0.242) and decreased tidal volumes during mechanical ventilation (median 5.4 mL/kg vs. median 9.2 mL/kg, P = 0.018) were observed in 2016 compared to 2009. Treatment outcomes for patients with H1N1 acute respiratory failure improved from 2009 to 2016 in two tertiary referral centers in South Korea

Co-Administration of Gagam-Sipjeondaebo-Tang and Ibuprofen Alleviates the Inflammatory Response in MPTP-Induced Parkinson’s Disease Mouse Model and RAW264.7 Macrophages

Parkinson’s disease (PD), a common neurodegenerative disease, is characterized by degeneration of dopaminergic neurons with neuroinflammation. Gagam-Sipjeondaebo-Tang (GST), a traditional herbal formula made of twelve medicinal herbs, is known to be effective in PD, and the use of ibuprofen has been associated with a lower risk of PD. The aim of this study was to evaluate whether the combined administration of GST and ibuprofen affects the inflammatory response of Parkinson’s disease. MPTP-induced parkinsonian mouse models were treated with GST or ibuprofen using oral gavage once a day for 5 days. The effects of GST were examined by measuring the TH level and expression of CD68 in the mice brain in addition to behavioral tests. The anti-inflammatory effect of GST on the LPS-treated RAW264.7 murine macrophages was examined using the NO assay. Inflammatory cytokines were analyzed using quantitative-PCR and flow cytometry. In the results, GST significantly improved the loss of dopaminergic neurons and alleviated PD-induced behavioral deficits. GST also decreased macrophage activation in the MPTP-induced PD mouse model. Interestingly, co-administration of GST and ibuprofen showed a synergistic effect in improving the loss of dopaminergic neurons and decreasing the activation of macrophages. Moreover, the NO level decreased in LPS-stimulated macrophages with this combined treatment. GST reduced iNOS, COX-2, IL-1β, and IL-6 levels, and co-administration with ibuprofen showed a synergistic effect. Furthermore, pretreatment of GST reduced the expression levels of MCP-1 and IL-12 p70 in LPS-stimulated RAW264.7 cells. These results can possibly suggest a future therapeutic approach for PD patients

An N-Heterocyclic-Carbene–Tetracyanoethylene Zwitterion: Experimental and Theoretical Study on Its Formation and Reactivity

The direct addition of tetracyanoethylene (TCNE) to the carbene center of 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) was successfully demonstrated. The IPr–TCNE adduct, that is, zwitterion 1, clearly differs from the typical [2+1]-cycloaddition products obtained from the reaction of carbenes with olefins. The results obtained from experimental and theoretical studies suggest that adduct 1 disassembles into IPr and TCNE, which is followed by the addition of IPr to the nitrile carbon atom of TCNE and subsequent isomerization into a thermodynamically more stable singlet nitrene intermediate. This intermediate is then captured by an additional molecule of TCNE to afford another heterocycle. This study reveals a unique example of the reactivity between N-heterocyclic carbenes and olefins.11Nsciescopu

Direct Observation of Redox Mediator-Assisted Solution-Phase Discharging of Li-O-2 Battery by Liquid-Phase Transmission Electron Microscopy

Li-O-2 battery is one of the important next-generation energy storage systems, as it can potentially offer the highest theoretical energy density among battery chemistries reported thus far. However, realization of its high discharge capacity still remains challenging and is hampered by the nature of how the discharge products are formed, causing premature passivation of the air electrode. Redox mediators are exploited to solve this problem, as they can promote the charge transfer from electrodes to the solution phase. The mechanistic understanding of the fundamental electrochemical reaction involving the redox mediators would aid in the further development of Li-O-2 batteries along with rational design of new redox mediators. Herein, we attempt to monitor the discharge reaction of a Li-O-2 battery in real time by liquid-phase transmission electron microscopy (TEM). Direct in situ TEM observation reveals the gradual growth of toroidal Li2O2 discharge product in the electrolyte with the redox mediator upon discharge. Moreover, quantitative analyses of the growth profiles elucidate that the growth mechanism involves two steps: dominant lateral growth of Li2O2 into disclike structures in the early stage followed by vertical growth with morphology transformation into a toroidal structure. © 2019 American Chemical Societ