986 research outputs found
신규 전해액 첨가제인 bis(2-fluoroethyl) carbonate 도입에 따른 리튬 금속 전지의 장기 사이클 특성 향상
No full textBis(2-fluoroethyl) carbonate, Electrolyte additive, Li metal anode, Cycle performance, Li metal batteryⅠ. Introduction 1
1.1 Overview 1
Ⅱ. A bis(2-fluoroethyl) carbonate as a new electrolyte additive for enhancing the long-term cycle performance of Li-metal batteries 3
2.1 Introduction 3
2.2 Experiment 5
2.2.1 Synthesis of B-FEC 5
2.2.2 Characteristic of B-FEC 6
2.2.3 Preparation of electrode and electrolyte 6
2.2.4 Electrochemical measurements 6
2.2.5 Postmortem analysis 7
2.3 Results and discussion 7
2.3.1 Structural analysis of B-FEC 8
2.3.2 Molecular orbital energy levels of electrolyte components 8
2.3.3 Optimization of B-FEC amount 10
2.3.4 Electrochemical performance of B-FEC 12
2.3.5 Surface analysis of Li metal through XPS 17
2.3.6 SEM images of Li metal after cycling 18
2.4 Conclusion 20
References 21
Summary (in Korean) 24MasterdCollectio
Surface enhanced electron correlation on the trivial quasi-two-dimensional bulk insulator 1T-TaS2
No full text© 2022 American Physical Society.While the prototypical quasi-two-dimensional charge density wave system of 1T-TaS2 has been known as a Mott insulator with a possibility of quantum spin liquid, recent band-structure calculations and spectroscopic works in parallel suggested a metallic system or a spin-singlet insulator due to the interlayer coupling. Here, we carefully reinvestigate the out-of-plane electron dispersion, which reflects the interlayer electronic coupling, with angle-resolved photoelectron spectroscopy. We identify two distinct branches for the topmost valence band, which can be unambiguously related to the surface and the bulk layers with different band gaps. Density functional theory calculations clearly indicate a trivial band insulator due to the interlayer coupling for the bulk but the surface band gap affected substantially by the electron correlation. The surface-bulk electronic dichotomy consistently incorporates most of the theoretical and spectroscopic results reported so far and has wide implications for van der Waals materials with nontrivial interlayer interactions.11Nsciescopu
Control over a Wide Phase Diagram of 2D Correlated Electrons by Surface Doping; K/1T-TaS2
No full textWe demonstrate the systematic tuning of a trivial insulator into a Mott insulator and a Mott insulator into a correlated metallic and a pseudogap state, which emerge in a quasi-two-dimensional electronic system of 1T-TaS2 through strong electron correlation. The band structure evolution is investigated upon surface doping by alkali adsorbates for two distinct phases occurring at around 220 and 10 K by angle-resolved photoelectron spectroscopy. We find contrasting behaviors upon doping that corroborate the fundamental difference of two electronic states: while the antibonding state of the spin-singlet insulator at 10 K is partially occupied to produce an emerging Mott insulating state, the presumed Mott insulating state at 220 K evolves into a correlated metallic state and then a pseudogap state. The work indicates that surface doping onto correlated 2D materials can be a powerful tool to systematically engineer a wide range of correlated electronic phases.11Nsciescopu
COOL-NPU: Complementary Online Learning Neural Processing Unit
No full textThe authors propose a complementary online learning neural processing unit (COOL-NPU) to implement a highly accurate and high-energy-efficient online learning system. It reduces the energy consumption by combining the training methods of convolutional neural network (CNN) and spiking neural network (SNN) and eliminates the power overhead due to the redundant weight update by training trigger with SNN gradient. The proposed SNN core reduces the energy consumption of SNN-gradient generation by two-step encoding and reduces inference power by hierarchical cache with lookup table -mode. In addition, it supports neuron-level event-driven backward operation to maximize the effect of the training trigger. Fabricated with Samsung 28-nm CMOS technology, the COOL-NPU achieves 6.94 mJ/frame and 0.73 mAP for object detection, resulting in 47.7% energy reduction with a slight accuracy loss compared to previous state of the art.
Modulating wall shear stress gradient via equilateral triangular channel for in situ cellular adhesion assay
No full textThis study introduces an equilateral triangular channel (ETRIC), a novel microfluidic channel with an equilateral triangular cross-section, for cell adhesion assay by modulating the wall shear stress (WSS) gradient. The channel can generate a parabolic WSS gradient perpendicular to the flow direction at a single flow rate, and cell detachment can be in situ screened in response to spatially different levels of WSS. The existence of a simple form of exact solution for the velocity field inside the entire ETRIC region enables the easy design and modulation of the WSS levels at the bottom surface; therefore, the detachment of the cells can be investigated at the pre-defined observation window in real time. The exact solution for the velocity field was validated by comparing the analytical velocity profile with those obtained from both numerical simulation and experimental particle image velocimetry. The parabolic WSS gradient can be generated stably and consistently over time at a steady-state condition and easily modulated by changing the flow rate for the given ETRIC geometry. The WSS gradient in the ETRIC is in a symmetric parabolic form, and this symmetry feature doubles the experimental data, thereby efficiently minimizing the number of experiments. Finally, a WSS gradient ranging from 0 to 160 dyn/cm(2) was generated through the present ETRIC, which enables not only to measure the adhesion strength but also to investigate the time-dependent detachment of NIH-3T3 cells attached on the glass. Published by AIP Publishing.1121sciescopu
Jiwon Han, violin
No full textProgram for recital offered in partial fulfillment of the requirements for the degree of Master of Music. With Haeun Yim, piano
Correction to “Ultrafast Cation Exchange in Supra-Quantum Dots through Nanoporous Internal Structure”
No full textThe author list should be “Hyunmi Doh, Juwon Park, Junhwa Lee, Jiwon Bang, Sanghwa Jeong, Wonseok Lee, Ho Jin, and Sungjee Kim”, with an addition of a co-author, Junhwa Lee. Hyunmi Doh, Juwon Park, and Junhwa Lee contributed equally to this work. This change was agreed to by all authors and is reflected in the authorship of this correction.11Nsciescopu
Nanohybrid magnetic liposome functionalized with hyaluronic acid for enhanced cellular uptake and near-infrared-triggered drug release
No full textThe aim of this work is to prepare and evaluate a novel lipid-polymer hybrid liposomal nanoplatform (hyaluronic acid-magnetic nanoparticle-liposomes, HA-MNP-LPs) as a vehicle for targeted delivery and triggered release of an anticancer drug (docetaxel, DTX) in human breast cancer cells. We first synthesize an amphiphilic hyaluronic acid hexadecylamine polymer (HA-C-16) to enhance the targeting ability of the hybrid liposome. Next, HA-MNP-LPs are constructed to achieve an average size of 189.93 +/- 2.74 nm in diameter. In addition, citric acid-coated magnetic nanoparticles (MNPs) are prepared and embedded in the aqueous cores while DTX is encapsulated in the hydrophobic bilayers of the liposomes. Experiments with coumarin 6 loaded hybrid liposomes (C6/HA-MNP-LPs) show that the hybrid liposomes have superior cellular uptake in comparison with the conventional non-targeting liposomes (C6/MNP-LPs), and the result is further confirmed by Prussian blue staining. Under near-infrared laser irradiation (NIR, 808 nm), the HA-MNP-LPs aqueous solution can reach 46.7 degrees C in 10 min, and the hybrid liposomes released over 20% more drug than the non-irradiated liposomes. Using a combination of photothermal irradiation and chemotherapy, the DTX-loaded hybrid liposomes (DTX/HA-MNP-LPs) significantly enhance therapeutic efficacy, with the IC50 value of 0.69 +/- 0.10 mu g/mL, which is much lower than the values for DTX monotherapy. Consequently, the prepared hybrid nanoplatform may offer a promising drug delivery vehicle with selective targeting and enhanced drug release in treating CD44-overexpressing cancers. (C) 2017 Elsevier B.V. All rights reserved.1
Electrical Tuning of the Excitonic Insulator Ground State of Ta2NiSe5
No full textWe demonstrate that the excitonic insulator ground state of Ta2NiSe5 can be electrically controlled by electropositive surface adsorbates. Our studies utilizing angle-resolved photoemission spectroscopy reveal intriguing wave-vector-dependent deformations of the characteristic flattop valence band of this material upon potassium adsorption. The observed band deformation indicates a reduction of the single-particle band gap due to the Stark effect near the surface. The present study provides the foundation for the electrical tuning of the many-body quantum states in excitonic insulators. © 2019 American Physical Society11sciescopu
Measuring Cell Adhesion Strength by Applying Shear Stress Gradient through the Microfluidic Device Having Equilateral Triangle Channel
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