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Converting the Bulk Transition Metal Dichalcogenides Crystal into Stacked Monolayers via Ethylenediamine Intercalationby Yeojin Ahn, Gyubin Lee, Namgyu Noh, Chulwan Lee, Duc Duy Le, Sunghun Kim, Yeonghoon Lee, Jounghoon Hyun, Chan-young Lim, Jaehun Cha, Mingi Jho, Seonggeon Gim, Jonathan D. Denlinger, Chan-Ho Yang, Jong Min Yuk, Myung Joon Han, and Yeongkwan KimNano Letters 2023, 23, 21, 9733–9739; https://doi.org/10.1021/acs.nanolett.3c02268AbstractWe report the synthesis of ethylenediamine-intercalated NbSe2 and Li-ethylenediamine-intercalated MoSe2 single crystals with increased interlayer distances and their electronic structures measured by means of angle-resolved photoemission spectroscopy (ARPES). X-ray diffraction patterns and transmission electron microscopy images confirm the successful intercalation and an increase in the interlayer distance. ARPES measurement reveals that intercalated NbSe2 shows an electronic structure almost identical to that of monolayer NbSe2. Intercalated MoSe2 also returns the characteristic feature of the monolayer electronic structure, a direct band gap, which generates sizable photoluminescence even in the bulk form. Our results demonstrate that the properties and phenomena of the monolayer transition metal dichalcogenides can be achieved with large-scale bulk samples by blocking the interlayer interaction through intercalation.Keywords: transition metal dichalcogenides; MoSe2; NbSe2; intercalation; bulk; monolayer
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- 작성일2024-02-22
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Anhydrous Alum Inhibits α-MSH-Induced Melanogenesis by Down-Regulating MITF via Dual Modulation of CREB and ERKby Bong-Rim Shin, Uros Puc, Yu-Jin Park, Dong-Joo Kim, Chae-Won Lee, Woojin Yoon, Hoseop Yun, Chaeyoon Kim, Fabian Rotermund, Mojca Jazbinsek, O-Pil KwonAdvanced Science 2023, 10(34), 2304767; https://doi.org/10.1002/advs.202304767AbstractIn the development of new organic crystals for nonlinear optical and terahertz (THz) applications, it is very challenging to achieve the essentially required non-centrosymmetric molecular arrangement. Moreover, the resulting crystal structure is mostly unpredictable due to highly dipolar molecular components with complex functional substituents. In this work, new organic salt crystals with top-level macroscopic optical nonlinearity by controlling the van der Waals volume (VvdW), rather than by trial and error, are logically designed. When the VvdW of molecular ionic components varies, the corresponding crystal symmetry shows an observable trend: change from centrosymmetric to non-centrosymmetric and back to centrosymmetric. All non-centrosymmetric crystals exhibit an isomorphic P1 crystal structure with an excellent macroscopic second-order nonlinear optical response. Apart from the top-level macroscopic optical nonlinearity, new organic crystals introducing highly electronegative fluorinated substituents with strong secondary bonding ability show excellent performance in efficient and broadband THz wave generation, high crystal density, high thermal stability, and good bulk crystal growth ability.Keywords: crystal structure control; nonlinear optics; organic crystals; terahertz photonics; van der Waals volume
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- 작성일2024-02-22
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- 작성일2024-02-22
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Anhydrous Alum Inhibits α-MSH-Induced Melanogenesis by Down-Regulating MITF via Dual Modulation of CREB and ERKby Kyu-Ree In, Mi Ae Kang, Su Dong Kim, Jinho Shin, Sung Un Kang, Tae Jun Park, Seung-Joo Kim and Jong-Soo LeeInternational Journal of Molecular Sciences 2023, 24(19), 14662; https://doi.org/10.3390/ijms241914662AbstractMelanogenesis, the intricate process of melanin synthesis, is central to skin pigmentation and photoprotection and is regulated by various signaling pathways and transcription factors. To develop potential skin-whitening agents, we used B16F1 melanoma cells to investigate the inhibitory effects of anhydrous alum on melanogenesis and its underlying molecular mechanisms. Anhydrous alum (KAl(SO4)2) with high purity (>99%), which is generated through the heat-treatment of hydrated alum (KAl(SO4)2·12H2O) at 400 °C, potentiates a significant reduction in melanin content without cytotoxicity. Anhydrous alum downregulates the master regulator of melanogenesis, microphthalmia-associated transcription factor (MITF), which targets key genes involved in melanogenesis, thereby inhibiting α-melanocyte-stimulating hormone (α-MSH)-induced melanogenesis. Phosphorylation of the cAMP response element-binding protein, which acts as a co-activator of MITF gene expression, is attenuated by anhydrous alum, resulting in compromised MITF transcription. Notably, anhydrous alum promoted extracellular signal-regulated kinase phosphorylation, leading to the impaired nuclear localization of MITF. Overall, these results demonstrated the generation and mode of action of anhydrous alum in B16F1 cells, which constitutes a promising option for cosmetic or therapeutic use.Keywords: anhydrous alum; melanogenesis; MITF; CREB; ERK
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Cu(triNHC)-catalyzed polymerization of glycidol to produce ultralow-branched polyglycerolby Kihyuk Sung, Jinsu Baek, Soonyoung Choi, Byeong-Su Kim, Sang-Ho Lee, In-Hwan Lee and Hye-Young JangRSC Advances 2023, 13(34), 24071-24076; https://doi.org/10.1039/D3RA04422JAbstractWe have successfully synthesized a novel form of polyglycerol with an unprecedentedly low degree of branching (DB = 0.08–0.18), eliminating the need for glycidol protection. Leveraging the remarkable efficiency and selectivity of our Cu(triNHC) catalyst, comprising copper(I) ions and NHC ligands, we achieved a highly selective polymerization process. The proposed Cu-coordination mechanisms presented the formation of linear L1,3 units while effectively suppressing dendritic units. Consequently, our pioneering approach yielded polyglycerol with an ultralow DB and exceptional yields. To comprehensively assess the physical properties and topology of the synthesized polyglycerol, we employed 1H diffusion-ordered spectroscopy, size-exclusion chromatography, and matrix-assisted laser desorption/ionization-time of flight spectrometry. Remarkably, the ultralow-branched cyclic polyglycerol (DB = 0.08) synthesized at 0 °C showcased extraordinary characteristics, exhibiting the lowest diffusion coefficient and the highest molecular weight. This achievement establishes the significant potential of our polyglycerol with a low degree of branching, revolutionizing the field of biocompatible polymers.
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Recent advances in organelle-specific two-photon small-molecule fluorescent probes for bioanalysis in live tissuesby Hyo Won Lee, Vinayak Juvekar, Dong Joon Lee, Hwan Myung KimTrAC Trends in Analytical Chemistry 2023, 165, 117128; https://doi.org/10.1016/j.trac.2023.117128AbstractBiological events occur in specific cellular organelles to perform specialized roles in cells and collaborate with other organelles. Various methods have been used to study organelle dynamics, including two-photon microscopy. This technique uses two near-infrared photons as an excitation source to generate high-resolution images over an extended period with minimal photo-toxicity and background noise. This review highlighted the design strategies, photo-physical properties, and bioimaging applications of recent two-photon probes for organelles in live samples. In this review, we focused on the development of two-photon probes specifically localized in the endoplasmic reticulum, Golgi, lipid droplets, lysosomes, plasma membrane, and mitochondria. The summary was limited to research from 2017 onwards.Keywords: Bioanalysis; Live tissues; Organelles; Two-photon microscopy; Two-photon probes
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Results on bar-core partitions, core shifted Young diagrams, and doubled distinct coresby Hyunsoo Cho, JiSun Huh, Hayan Nam, Jaebum SohnDiscrete Mathematics 2023, 346(7), 113387; https://doi.org/10.1016/j.disc.2023.113387AbstractSelf-conjugate core partitions, bar-core partitions, core shifted Young diagrams (or CSYDs), and doubled distinct core partitions have been studied independently. In this paper, we show that doubled distinct cores and CSYDs are special cases of bar-core partitions. From this fact together with the abacus construction, we find path interpretations of bar-cores, CSYDs, and doubled distinct cores on (s, t)-cores and (s,s+d,s+2d)-cores, respectively. As a result, we get the number of these core partitions.Keywords: Bar-core partitions; Core shifted young diagrams; Doubled distinct core partitions; Simultaneous core partitions; Free Motzkin paths
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