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Modeling asymmetric fracture mechanics of Mg alloy wire in drawing process

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Journal of Magnesium and Alloys 2024年第5期12卷 2057-2069页

作者： Sunghoon Choi Jongwon Shin Joung Sik Suh Dongchoul Kim Department of Mechanical Engineering Sogang UniversitySeoul04107Republic of Korea Advanced Metals Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea

In this study,a numerical analysis was conducted on the ductile fracture of a 2-mm diameter Mg-1Zn-0.5Mn-0.5Sr-0.1Ca alloy wire during *** hexagonally close-packed crystal structure of Mg alloys causes asymmetric fracture behavior,especially in the compression *** aim of this study is to develop a comprehensive damage model for Mg alloy wire that accurately predicts ductile fracture,with a focus on the compression region.A novel experimental method was introduced to measure the ductile fracture of Mg alloy wires under different stress *** wire drawing process was simulated using the Generalized Incremental Stress-State dependent damage(GISSMO)Model and the Semi-Analytical Model for Polymers(SAMP)*** damage model's prediction and the experimental results were found to be in excellent agreement,especially in determining crack *** analysis established a safe zone diagram for die angle and reduction ratio,and experimental validation confirmed the feasibility of this *** proposed damage model can provide a practical and reliable analysis for optimizing the drawing process of Mg alloy wire.

关键词： Mg alloy Wire drawing Finite element method Damage model Safe zone diagram

Crystallographically vacancy‐induced MOF nanosheet as rational single‐atom support for accelerating CO_(2)electroreduction to CO

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Carbon Energy 2024年第8期6卷 49-62页

作者： Jin Hyuk Cho Joonhee Ma Chaehyeon Lee Jin Wook Lim Youngho Kim Ho Yeon Jang Jaehyun Kim Myung‐gi Seo Youngheon Choi Youn Jeong Jang Sang Hyun Ahn Ho Won Jang Seoin Back Jong‐Lam Lee Soo Young Kim Department of Materials Science and Engineering Korea UniversitySeoulRepublic of Korea Department of Chemical and Biomolecular Engineering Sogang UniversitySeoulRepublic of Korea Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH)PohangRepublic of Korea Department of Materials Science and Engineering Research Institute of Advanced MaterialsSeoul National UniversitySeoulRepublic of Korea Lotte Chemical R&D Center DaejeonRepublic of Korea Department of Chemical Engineering Hanyang UniversitySeoulRepublic of Korea School of Chemical Engineering and Material Science Chung‐Ang UniversitySeoulRepublic of Korea

To attain a circular carbon economy and resolve CO_(2)electroreduction technology obstacles,single‐atom catalysts(SACs)have emerged as a logical option for electrocatalysis because of their extraordinary catalytic *** SACs,metal–organic frameworks(MOFs)have been recognized as promising support materials because of their exceptional ability to prevent metal *** study shows that atomically dispersed Ni single atoms on a precisely engineered MOF nanosheet display a high Faradaic efficiency of approximately 100%for CO formation in H‐cell and three‐compartment microfluidic flow‐cell reactors and an excellent turnover frequency of 23,699 h−1,validating their intrinsic catalytic *** results suggest that crystallographic variations affect the abundant vacancy sites on the MOF nanosheets,which are linked to the evaporation of Zn‐containing organic linkers during ***,using X‐ray absorption spectroscopy and density functional theory calculations,a comprehensive investigation of the unsaturated atomic coordination environments and the underlying mechanism involving CO^(*)preadsorbed sites as initial states was possible and provided valuable insights.

关键词： 2‐dimensional material carbon dioxide reduction metal-organic frameworks single‐atom catalysts vacancy sites

The processed C-terminus of AvrRps4 effector suppresses plant immunity via targeting multiple WRKYs

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Journal of Integrative Plant Biology 2024年第8期66卷 1769-1787页

作者： Quang-Minh Nguyen Arya Bagus Boedi Iswanto Hobin Kang Jiyun Moon Kieu Anh Thi Phan Geon Hui Son Mi Chung Suh Eui-Hwan Chung Walter Gassmann Sang Hee Kim Division of Applied Life Science(BK21 Four Program) Plant Molecular Biology and Biotechnology Research CenterGyeongsang National UniversityJinju 52828Korea Department of Life Science Sogang UniversitySeoul 04107Korea Department of Plant Biotechnology Korea UniversitySeoul 02841Korea Division of Plant Science and Technology Christopher S.Bond Life Sciences Center and Interdisciplinary Plant GroupUniversity of MissouriColumbiaMissouri 65211USA Division of Life Science and Research Institute of Molecular Alchemy Gyeongsang National UniversityJinju 52828Korea

Pathogens generate and secrete effector proteins to the host plant cells during pathogenesis to promote virulence and *** the plant carries resistance(R)proteins that recognize pathogen effectors,effector-triggered immunity(ETI)is activated,resulting in a robust immune response and hypersensitive response(HR).The bipartite effector AvrRps4 from Pseudomonas syringae *** has been well studied in terms of avirulence *** planta,AvrRps4 is processed into two *** Cterminal fragment of AvrRps4(AvrRps4^(C))induces HR in turnip and is recognized by the paired resistance proteins AtRRS1/AtRPS4 in ***,we show that AvrRps4^(C)targets a group of Arabidopsis WRKY,including WRKY46,WRKY53,WRKY54,and WRKY70,to induce its virulence ***,AvrRps4^(C)suppresses the general binding and transcriptional activities of immune-positive regulator WRKY54 and WRKY54-mediated ***4^(C)interferes with WRKY54's binding activity to target gene SARD1 in vitro,suggesting WRKY54 is sequestered from the SARD1 promoter by AvrRps4^(C).Through the interaction of Avr Rps4^(C)with four WRKYs,AvrRps4 enhances the formation of homo-/heterotypic complexes of four WRKYs and sequesters them in the cytoplasm,thus inhibiting their function in plant ***,our results provide a detailed virulence mechanism of AvrRps4 through its C-terminus.

关键词： AvrRps4 bacterial effector effector-triggered immunity immune response suppression transcription factor WRKY

Unraveling the Harmonious Coexistence of Ruthenium States on a Self-Standing Electrode for Enhanced Hydrogen Evolution Reaction

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ENERGY & ENVIRONMENTAL MATERIALS 2024年第6期7卷 303-311页

作者： Ma, Joonhee Cho, Jin Hyuk Lee, Chaehyeon Kang, Moon Sung Choi, Sungkyun Jang, Ho Won Ahn, Sang Hyun Back, Seoin Kim, Soo Young Korea Univ Dept Mat Sci & Engn Seoul 02841 South Korea sogang Univ Inst Emergent Mat Dept Chem & Biomol Engn Seoul 04107 South Korea Pusan Natl Univ Coll Nanosci & Nanotechnol Dept Cogno Mechatron Engn Busan 46241 South Korea Seoul Natl Univ Res Inst Adv Mat Dept Mat Sci & Engn Seoul 08826 South Korea Chung Ang Univ Sch Chem Engn & Mat Sci Seoul 06974 South Korea

The development of cost-effective, highly efficient, and durable electrocatalysts has been a paramount pursuit for advancing the hydrogen evolution reaction (HER). Herein, a simplified synthesis protocol was designed to achieve a self-standing electrode, composed of activated carbon paper embedded with Ru single-atom catalysts and Ru nanoclusters (ACP/RuSAC+C) via acid activation, immersion, and high-temperature pyrolysis. Ab initio molecular dynamics (AIMD) calculations are employed to gain a more profound understanding of the impact of acid activation on carbon paper. Furthermore, the coexistence states of the Ru atoms are confirmed via aberration-corrected scanning transmission electron microscopy (AC-STEM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS). Experimental measurements and theoretical calculations reveal that introducing a Ru single-atom site adjacent to the Ru nanoclusters induces a synergistic effect, tuning the electronic structure and thereby significantly enhancing their catalytic performance. Notably, the ACP/RuSAC+C exhibits a remarkable turnover frequency (TOF) of 18 s-1 and an exceptional mass activity (MA) of 2.2 A mg-1, surpassing the performance of conventional Pt electrodes. The self-standing electrode, featuring harmoniously coexisting Ru states, stands out as a prospective choice for advancing HER catalysts, enhancing energy efficiency, productivity, and selectivity. A self-standing electrode with the coexistence of Ru single atoms and Ru nanoclusters is designed for the hydrogen evolution reaction (HER). Additional acid activation process induces defects, anchoring more Ru ions on the substrate. Detailed experimental and computational investigations suggest that the electronic coupling effect between different Ru states significantly enhanced the overall HER performance. image

关键词： electrocatalysis electronic coupling effect hydrogen evolution reaction self-standing electrode CARBON ELECTROREDUCTION CATALYSTS PAPER

Generation of tumor spheroids using a droplet-based microfluidic device for photothermal therapy

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Microsystems & Nanoengineering 2020年第1期6卷 796-805页

作者： Jong Min Lee Ji Wook Choi Christian D.Ahrberg Hyung Woo Choi Jang Ho Ha Seok Gyu Mun Sung Joon Mo Bong Geun Chung Department of Mechanical Engineering Sogang UniversitySeoulKorea Division of Chemical Industry Yeungnam University CollegeDaeguRepublic of Korea Research Center Sogang UniversitySeoulKorea Department of Biomedical Engineering Sogang UniversitySeoulKorea

Despite their simplicity,monolayer cell cultures are not able to accurately predict drug behavior in vivo due to their inability to accurately mimic cell-cell and cell-matrix *** contrast,cell spheroids are able to reproduce these interactions and thus would be a viable tool for testing drug ***,the generation of homogenous and reproducible cell spheroids on a large scale is a labor intensive and slow process compared to monolayer cell ***,we present a droplet-based microfluidic device for the automated,large-scale generation of homogenous cell spheroids in a uniform *** the microfluidic system,the size of the spheroids can be tuned to between 100 and 130μm with generation frequencies of 70 *** demonstrated the photothermal therapy(PTT)application of brain tumor spheroids generated by the microfluidic device using a reduced graphene oxide-branched polyethyleneimine-polyethylene glycol(rGO-BPEI-PEG)nanocomposite as the PTT ***,we generated uniformly sized neural stem cell(NSC)-derived neurospheres in the droplet-based microfluidic *** also confirmed that the neurites were regulated by ***,this droplet-based microfluidic device could be a powerful tool for photothermal therapy and drug screening applications.

关键词： fluid viable simplicity

Identities for degenerate Bernoulli polynomials and Korobov polynomials of the first kind

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Science China Mathematics 2019年第5期62卷 999-1028页

作者： Taekyun Kim Dae San Kim Department of Mathematics Kwangwoon University Department of Mathematics Sogang University

In this paper, we derive five basic identities for Sheffer polynomials by using generalized Pascal functional and Wronskian matrices. Then we apply twelve basic identities for Sheffer polynomials, seven from previous results, to degenerate Bernoulli polynomials and Korobov polynomials of the first kind and get some new identities. In addition, letting λ→ 0 in such identities gives us those for Bernoulli polynomials and Bernoulli polynomials of the second kind.

关键词： generalized Pascal functional matrix Wronskian matrix degenerate Bernoulli polynomial Krobov polynomial of the first kind

Some identities of Bell polynomials

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Science China Mathematics 2015年第10期58卷 2095-2104页

作者： KIM Dae San KIM Taekyun Department of Mathematics Sogang University Department of Mathematics Kwangwoon University

We investigate Bell polynomials, also called Touchard polynomials or exponential polynomials, by using and without using umbral calculus. We use three different formulas in order to express various known families of polynomials such as Bernoulli polynomials, poly-Bernoulli polynomials, Cauchy polynomials and falling factorials in terms of Bell polynomials and vice versa. In addition, we derive several properties of Bell polynomials along the way.

关键词： Bell-polynomial umbral calculus poly-Bernoulli polynomial higher-order Bernoulli polynomial Cauchy polynomial

q-Bernoulli polynomials and q-umbral calculus

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Science China Mathematics 2014年第9期57卷 1867-1874页

作者： KIM Dae San KIM Tae Kyun Department of Mathematics Sogang University Department of Mathematics Kwangwoon University

In this paper,we investigate some properties of q-Bernoulli polynomials arising from q-umbral *** find a formula for expressing any polynomial as a linear combination of q-Bernoulli polynomials with explicit ***,we es... 详细信息

关键词： q-Bernoulli polynomial q-umbral calculus

Language Model Using Differentiable Neural Computer Based on Forget Gate-Based Memory Deallocation

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Computers, Materials & Continua 2021年第7期68卷 537-551页

作者： Donghyun Lee Hosung Park Soonshin Seo Changmin Kim Hyunsoo Son Gyujin Kim Ji-Hwan Kim Department of Computer Science and Engineering Sogang UniversitySeoul04107Korea

A differentiable neural computer(DNC)is analogous to the Von Neumann machine with a neural network controller that interacts with an external memory through an attention *** DNC’s offer a generalized method for task-specific deep learning models and have demonstrated reliability with reasoning *** this study,we apply a DNC to a language model(LM)*** LM task is one of the reasoning problems,because it can predict the next word using the previous word ***,memory deallocation is a problem in DNCs as some information unrelated to the input sequence is not allocated and remains in the external memory,which degrades ***,we propose a forget gatebased memory deallocation(FMD)method,which searches for the minimum value of elements in a forget gate-based retention *** forget gatebased retention vector indicates the retention degree of information stored in each external memory *** experiments,we applied our proposed NTM architecture to LM tasks as a task-specific example and to rescoring for speech recognition as a general-purpose *** LM tasks,we evaluated DNC using the Penn Treebank and enwik8 LM *** it does not yield SOTA results in LM tasks,the FMD method exhibits relatively improved performance compared with DNC in terms of *** the speech recognition rescoring tasks,FMD again showed a relative improvement using the LibriSpeech data in terms of word error rate.

关键词： Forget gate-based memory deallocation differentiable neural computer language model forget gate-based retention vector