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Sustainable Catalytic Synthesis of 2,5-Diformylfuran from Various Carbohydrates by Si Ae Kim;Kihyuk Sung;June Young Jang;Sohee Bang;Seung Uk Son;Hye-Young Jang Catalysts, 2022 https://doi.org/10.3390/catal12040360 Abstract Versatile homogeneous and heterogeneous catalysts that convert carbohydrates to 2,5-diformylfuran (DFF) are essential for the development of sustainable processes for producing high-value chemicals from biomass-derived carbohydrates. An efficient catalytic system consisting of Br−, disulfide, and dimethylsulfoxide (DMSO) promoted the sustainable and selective synthesis of DFF in modest-to-good yields from various carbohydrates, such as fructose, glucose, mannose, galactose, and sucrose. Heterogeneous catalysts containing Br− also facilitated this reaction with recyclable high yields. Keywords: biomass; carbohydrates; 2,5-diformylfuran; fructose; glucose
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12
- 작성자박은영
- 작성일2023-01-13
- 322
- 동영상동영상
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Highly Sensitive Two-Photon Lipid Droplet Tracker for In Vivo Screening of Drug Induced Liver Injury by Hyo Won Lee;In-Jeong Lee;Soo-Jin Lee;Yu Rim Kim;Hwan Myung Kim ACS Sensors, 2022 https://doi.org/10.1021/acssensors.1c02679 Abstract Lipid droplets (LDs) are lipid-abundant organelles found in most cell lines and primarily consist of neutral lipids. They serve as a repository of various lipids and are associated with many cellular metabolic processes, including energy storage, membrane synthesis, and protein homeostasis. LDs are prominent in a variety of diseases related to lipid regulation, including obesity, fatty liver disease, diabetes, and atherosclerosis. To monitor LD dynamics in live samples, we developed a highly selective two-photon fluorescent tracker for LDs (LD1). It exhibited outstanding sensitivity with a remarkable two-photon-action cross section (Φδmax > 600 GM), photostability, and low cytotoxicity. In human hepatocytes and in vivo mouse liver tissue imaging, LD1 showed very bright fluorescence with high LD selectivity and minimized background signal to evaluate the stages of nonalcoholic fatty liver disease. Interestingly, we demonstrated that the liver sinusoid morphology became narrower with increasing LD size and visualized the dynamics including fusion of the LDs in vivo. Moreover, real-time and dual-color TPM imaging with LD1 and a two-photon lysosome tracker could be a useful predictive screening tool in the drug development process to monitor impending drug-induced liver injury inducing drug candidates. KEYWORDS: lipid droplets fatty liver disease steatosis phospholipidosis in vivo imaging
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10
- 작성자박은영
- 작성일2023-01-13
- 319
- 동영상동영상
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Substrate-binding loop interactions with pseudouridine trigger conformational changes that promote catalytic efficiency of pseudouridine kinase PUKI by Sang-HoonKim;Minjeong Kim;Daechan Park;Sujeong Byun;Sangkee Rhee Journal of Biological Chemistry, 2022 https://doi.org/10.1016/j.jbc.2022.101869 Abstract Pseudouridine, one major RNA modification, is catabolized into uracil and ribose-5′-phosphate by two sequential enzymatic reactions. In the first step, pseudouridine kinase (PUKI) phosphorylates pseudouridine to pseudouridine 5′-monophosphate. High-fidelity catalysis of pseudouridine by PUKI prevents possible disturbance of in vivo pyrimidine homeostasis. However, the molecular basis of how PUKI selectively phosphorylates pseudouridine over uridine with >100-fold greater efficiency despite minor differences in their Km values has not been elucidated. To investigate this selectivity, in this study we determined the structures of PUKI from Escherichia coli strain B (EcPUKI) in various ligation states. The structure of EcPUKI was determined to be similar to PUKI from Arabidopsis thaliana, including an α/β core domain and β-stranded small domain, with dimerization occurring via the β-stranded small domain. In a binary complex, we show that Ser30 in the substrate-binding loop of the small domain mediates interactions with the hallmark N1 atom of pseudouridine nucleobase, causing conformational changes in its quaternary structure. Kinetic and fluorescence spectroscopic analyses also showed that the Ser30-mediated interaction is a prerequisite for conformational changes and subsequent catalysis by EcPUKI. Furthermore, S30A mutation or EcPUKI complexed with other nucleosides homologous to pseudouridine but lacking the pseudouridine-specific N1 atom did not induce such conformational changes, demonstrating the catalytic significance of the proposed Ser30-mediated interaction. These analyses provide structural and functional evidence for a pseudouridine-dependent conformational change of EcPUKI and its functional linkage to catalysis.
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8
- 작성자박은영
- 작성일2023-01-13
- 352
- 동영상동영상
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Effect of the Plasma Gas Type on the Surface Characteristics of 3Y-TZP Ceramic by Sung-Un Kang;Chul-Ho Kim;Hee-Kyung Kim;Ye-Won Yoon;Yu-Kwon Kim;Seung-Joo Kim International Journal of Molecular Sciences, 2022 https://doi.org/10.3390/ijms23063007 Abstract Plasma surface treatment can be an attractive strategy for modifying the chemically inert nature of zirconia to improve its clinical performance. This study aimed to clarify the effect of plasma gas compositions on the physicochemical surface modifications of 3 mol% yttria-stabilized zirconia (3Y-TZP). The cold, atmospheric plasma discharges were carried out by using four different plasma gases, which are He/O2, N2/Ar, N2, and Ar from an application distance of 10 mm for 60 s. Static contact angles were measured to define the surface free energy. Changes in elemental composition, surface crystallinity, and surface topography were assessed with X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM), respectively. A significant decrease in water contact angle was observed in all plasma groups with the lowest value of 69° in the N2/Ar group. CLSM and SEM investigations exhibited no morphological changes in all plasma groups. XPS revealed that a reduction in the surface C content along with an increase in O content was pronounced in the case of N2/Ar compared to others, which was responsible for high hydrophilicity of the surface. XRD showed that the changes in crystallite size and microstrain due to oxygen atom displacements were observed in the N2/Ar group. The N2/Ar plasma treatment may contribute to enhancing the bioactivity as well as the bonding performance of 3Y-TZP by controlling the plasma-generated nitrogen functionalities. Keywords: plasma gases; zirconium oxide; surface properties; nitrogen; wettability
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6
- 작성자박은영
- 작성일2023-01-13
- 314
- 동영상동영상
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4
- 작성자박은영
- 작성일2023-01-13
- 324
- 동영상동영상
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2
- 작성자박은영
- 작성일2023-01-13
- 315
- 동영상동영상
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Highly Stable Red-Emissive Ratiometric Probe for Monitoring beta-Galactosidase Activity Using Fluorescence Microscopy and Flow Cytometry by Lee, Hyo Won;Juvekar, Vinayak;Lee, Dong Joon;Kim, Sun Mi;Kim, Hwan Myung; Analytical Chemistry, 2021 https://doi.org/10.1021/acs.analchem.1c03453 Abstract β-Galactosidase (β-gal), well known as a useful reporter enzyme, is a potent biomarker for various diseases such as colorectal and ovarian cancers. We have developed a highly stable red-emissive ratiometric fluorescent probe (CCGal1) for quantitatively monitoring the β-gal enzyme activity in live cells and tissues. This ratiometric probe showed a fast emission color change (620–662 nm) in response to β-gal selectively, which was accompanied by high enzyme reaction efficacy, cell-staining ability, and outstanding stability with minimized cytotoxicity. Confocal fluorescence microscopy ratiometric images, combined with fluorescence-activated cell sorting flow cytometry, demonstrated that CCGal1 could provide useful information for the diagnosis, prognosis, and treatment of β-gal enzyme activity-related diseases such as colorectal and ovarian cancers. Further, it may yield meaningful strategies for designing and modifying multifunctional bioprobes with different biomedical applications.
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0
- 작성자박은영
- 작성일2022-01-20
- 550
- 동영상동영상
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Light intensity dependence of organic solar cell operation and dominance switching between Shockley-Read-Hall and bimolecular recombination losses by Ryu, Shinyoung;Ha, Na Young;Ahn, Y. H.;Park, Ji-Yong;Lee, Soonil Scientific Reports, 2021 https://doi.org/10.1038/s41598-021-96222-w Abstract IWe investigated the variation of current density–voltage (J–V) characteristics of an organic solar cell (OSC) in the dark and at 9 different light intensities ranging from 0.01 to 1 sun of the AM1.5G spectrum. All three conventional parameters, short-circuit currents (Jsc), open-circuit voltage (Voc), and Fill factor (FF), representing OSC performance evolved systematically in response to light intensity increase. Unlike Jsc that showed quasi-linear monotonic increase, Voc and FF showed distinctive non-monotonic variations. To elucidate the origin of such variations, we performed extensive simulation studies including Shockley–Read–Hall (SRH) recombination losses. Simulation results were sensitive to defect densities, and simultaneous agreement to 10 measured J–V curves was possible only with the defect density of 5×1012 cm−3. Based on analyses of simulation results, we were able to separate current losses into SRH- and bimolecular-recombination components and, moreover, identify that the competition between SRH- and bimolecular-loss currents were responsible for the aforementioned variations in Jsc, Voc, and FF. In particular, we verified that apparent demarcation in Voc, and FF variations, which seemed to appear at different light intensities, originated from the same mechanism of dominance switching between recombination losses.
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-2
- 작성자박은영
- 작성일2022-01-20
- 468
- 동영상동영상
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-4
- 작성자박은영
- 작성일2022-01-20
- 453
- 동영상동영상
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A Novel Carbon-Assisted Chemical Vapor Deposition Growth of Large-Area Uniform Monolayer MoS2 and WS2 by Bae, Jeonghwan;Yoo, Youngdong Nanomaterials, 2021 https://doi.org/10.3390/nano11092423 Abstract Monolayer MoS2 can be used for various applications such as flexible optoelectronics and electronics due to its exceptional optical and electronic properties. For these applications, large-area synthesis of high-quality monolayer MoS2 is highly desirable. However, the conventional chemical vapor deposition (CVD) method using MoO3 and S powder has shown limitations in synthesizing high-quality monolayer MoS2 over a large area on a substrate. In this study, we present a novel carbon cloth-assisted CVD method for large-area uniform synthesis of high-quality monolayer MoS2. While the conventional CVD method produces thick MoS2 films in the center of the substrate and forms MoS2 monolayers at the edge of the thick MoS2 films, our carbon cloth-assisted CVD method uniformly grows high-quality monolayer MoS2 in the center of the substrate. The as-synthesized monolayer MoS2 was characterized in detail by Raman/photoluminescence spectroscopy, atomic force microscopy, and transmission electron microscopy. We reveal the growth process of monolayer MoS2 initiated from MoS2 seeds by synthesizing monolayer MoS2 with varying reaction times. In addition, we show that the CVD method employing carbon powder also produces uniform monolayer MoS2 without forming thick MoS2 films in the center of the substrate. This confirms that the large-area growth of monolayer MoS2 using the carbon cloth-assisted CVD method is mainly due to reducing properties of the carbon material, rather than the effect of covering the carbon cloth. Furthermore, we demonstrate that our carbon cloth-assisted CVD method is generally applicable to large-area uniform synthesis of other monolayer transition metal dichalcogenides, including monolayer WS2. Keywords: carbon-assisted CVD; growth mechanism; monolayer; MoS2; WS2
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-6
- 작성자박은영
- 작성일2022-01-20
- 506
- 동영상동영상
