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A Certain Subclass of Analytic Functions with Bounded Positive Real Part

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Advances in Pure Mathematics 2013年第4期3卷 409-414页

作者： young jae sim Oh Sang Kwon Department of Mathematics Kyungsung UniversityBusanSouth Korea

For real numbers α and β such that 0≤α<1<β, we denote by T(α,β) the class of normalized analytic functions which satisfy , where U denotes the open unit disk. We find some relationships involving functions in the class T(α,β). And we estimate the bounds of coefficients and solve Fekete-Szego problem for functions in this class. Furthermore, we investigate the bounds of initial coefficients of inverse functions or bi-univalent functions.

关键词： Functions of Bounded Positive Real Part Fekete-Szego Problem Inverse Functions Bi-Univalent Functions

A Certain Subclass of Analytic Functions

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Advances in Pure Mathematics 2012年第4期2卷 291-295页

作者： young jae sim Oh Sang Kwon Department of Mathematics Kyungsung University Busan Korea (South)

In the present paper, we introduce a class of analytic functions in the open unit disc by using the analytic function qα(z)=3/(3+(α-3)z-αz2), which was investigated by Sokó? [1]. We find some properties including the growth theorem or the coefficient problem of this class and we find some relation with this new class and the class of convex functions.

关键词： Univalent Functions Convex Functions Subordination Order of Convexity

Modification strategies improving the electrochemical and structural stability of high-Ni cathode materials

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Journal of Energy Chemistry 2024年第9期96卷 185-205页

作者： Yoon Bo sim Hami Lee Junyoung Mun Ki jae Kim Department of Energy Science Sungkyunkwan UniversitySuwon 16419Republic of Korea School of Advanced Materials Science and Engineering Sungkyunkwan UniversitySuwon 16419Republic of Korea SKKU Institute of Energy Science and Technology(SIEST) Sungkyunkwan UniversitySuwon 16419Republic of Korea

With the increasing spotlight in electric vehicles,there is a growing demand for high-energy-density batteries to enhance driving ***,several studies have been conducted on high-energy-density LiNi_(x)Co_(y)Mn_(z)O_(2)***,there is a limit to permanent performance deterioration because of side reactions caused by moisture in the atmosphere and continuous microcracks during cycling as the Ni content to express high energy increases and the content of Mn and Co that maintain structural and electrochemical stabilization *** direct modification of the surface and bulk regions aims to enhance the capacity and long-term performance of high-Ni cathode ***,an efficient modification requires a study based on a thorough understanding of the degradation mechanisms in the surface and bulk *** this review,a comprehensive analysis of various modifications,including doping,coating,concentration gradient,and single crystals,is conducted to solve degradation issues along with an analysis of the overall degradation mechanism occurring in high-Ni cathode *** also summarizes recent research developments related to the following modifications,aims to provide notable points and directions for post-studies,and provides valuable references for the commercialization of stable high-energy-density cathode materials.

关键词： High energy density High-Ni cathode materials Degradation Structural stability Lithium-ion battery

MXene-based hybrid materials for electrochemical and photoelectrochemical H_(2) generation

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Journal of Energy Chemistry 2024年第6期93卷 111-125,I0004页

作者： Jun young Kim Seung Hun Roh Chengkai Xia Uk sim Jung Kyu Kim School of Material Science and Engineering North University of ChinaTaiyuan 030051China School of Chemical Engineering Sungkyunkwan University(SKKU)2066Seobu-roJangan-guSuwon 16419Republic of Korea Hydrogen Energy Technology Laboratory Korea Institute of Energy Technology(KENTECH)NajuJeollanamdo 58330Republic of Korea SKKU Advanced Institute of Nano Technology(SAINT) Sungkyunkwan University(SKKU)2066Seobu-roJangan-guSuwon 16419Republic of Korea

The conversion of solar energy to produce clean hydrogen fuel through water splitting is an emerging strategy for efficiently storing solar energy in the form of solar *** aligns with the increasing global demand for the development of an ideal energy alternative to fossil fuels that does not emit greenhouse ***(EC) and photoelectrochemical(PEC) water splitting technologies have garnered significant attention worldwide for advanced hydrogen solar fuel production in recent *** achieve sustainable green H_(2) production,it is essential to create efficient catalyst materials that are low-cost and can replace expensive noble metal-based *** characteristics make them an ideal catalyst material for the ***-dimensional MXenes with M_(n+1)X_(n) structure have been identified as a promising option for EC and PEC water splitting due to their superior hydrophilicity,metal-like conductivity,large surface area,and adjustable surface ***,we present a summary of recent advancements in the synthesis and performance enhancement methods for MXene hybrid materials in hydrogen production through EC and PEC water ***,we examine the challenges and insights associated with the rational design of MXene-based hybrid materials to facilitate efficient water splitting for sustainable solar fuel production.

关键词： MXene Hybrid materials EC PEC HER OER Water splitting

Electrochemically Deposited CZTSSe Thin Films for Monolithic Perovskite Tandem Solar Cells with Efficiencies Over 17%

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Energy & Environmental Materials 2024年第1期7卷 147-152页

作者： Sun Kyung Hwang Ik jae Park Se Won Seo jae Hyun Park So Jeong Park Jin young Kim Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Korea Department of Applied Physics Sookmyung Women's UniversitySeoul 04310Korea Research Institute of Advanced Materials and Systems Sookmyung Women's UniversitySeoul 04310Korea Research Institute of Advanced Materials(RIAM) Seoul National UniversitySeoul 08826Korea

In spite of the high potential economic feasibility of the tandem solar cells consisting of the halide perovskite and the kesterite Cu2ZnSn(S,Se)4(CZTSSe),they have rarely been demonstrated due to the difficulty in implementing solution-processed perovskite top cell on the rough surface of the bottom ***,we firstly demonstrate an efficient monolithic two-terminal perovskite/CZTSSe tandem solar cell by significantly reducing the surface roughness of the electrochemically deposited CZTSSe bottom *** surface roughness(R_(rms))of the CZTSSe thin film could be reduced from 424 to 86 nm by using the potentiostatic mode rather than using the conventional galvanostatic mode,which can be further reduced to 22 nm after the subsequent ion-milling *** perovskite top cell with a bandgap of 1.65 eV could be prepared using a solution process on the flattened CZTSSe bottom cell,resulting in the efficient perovskite/CZTSSe tandem solar *** the current matching between two subcells involving the thickness control of the perovskite layer,the best performing tandem device exhibited a high conversion efficiency of 17.5%without the hysteresis effect.

关键词： CZTSSe monolithic tandem solar cells perovskite solution process surface roughness control

Dual in-situ observation of tribochemical and morphological evolution of single-layer WS_(2)and multi-layer WS_(2)/C coatings

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Friction 2024年第7期12卷 1580-1598页

作者： Yuzhen LIU jae-Ho HAN Shusheng XU young Chan JUNG Dae-Eun KIM State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Department of Mechanical Engineering Yonsei UniversitySeoul03722Republic of Korea Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai Yantai 264000China Yantai Zhongke Research Institute of Advanced Materials and Green Chemical Engineering Yantai 264000China

The outstanding tribological performance of transition metal dichalcogenides(TMDs)is attributed to their unique sandwich microstructure and low interlayer shear *** advantageous structure allows TMDs to demonstrate exceptional friction reduction ***,the incorporation of TMDs and amorphous carbon(a-C)in multi-layer structures shows excellent potential for further enhancing tribological and anti-oxidation *** carbon,known for its high ductility,chemical inertness,and excellent wear resistance,significantly contributes to the overall performance of these multi-layer *** gain an in-depth understanding of the tribological mechanism and evolution of TMDs’multi-layer coatings,a dual in-situ analysis was carried out using a tribometer equipped with a 3D laser microscope and a Raman *** innovative approach allowed for a comprehensive evolution of the tribological,topographical,and tribochemical characteristics of both single-layer WS_(2)and multi-layer WS_(2)/C coatings in real *** findings from the dual in-situ tribotest revealed distinct failure characteristics between the single-layer WS_(2)coating and the multi-layer WS_(2)/C *** single-layer WS_(2)coating predominantly experienced failure due to mechanical removal,whereas a combination of mechanical removal and tribochemistry primarily influenced the failure of the multi-layer WS_(2)/C *** tribological evolution process of these two coatings can be classified into four stages on the basis of their tribological behavior:the running-in stage,stable friction stage,re-deposition stage,and lubrication failure *** stage represents a distinct phase in the tribological behavior of the coatings and contributes to our understanding of their behavior during sliding.

关键词： In-situ analysis multi-layer coating tribology tribochemistry

Acoustofluidic separation of prolate and spherical micro-objects

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Microsystems & Nanoengineering 2024年第1期10卷 217-230页

作者： Muhammad Soban Khan Mushtaq Ali Song Ha Lee Keun young Jang Seong jae Lee Jinsoo Park Department of Mechanical Engineering Chonnam National University77 Yongbong-roBuk-guGwangju 61186Republic of Korea Department of Polymer Engineering The University of Suwon17 Wauan-gilBongdam-eupHwaseongGyeonggi 18323Republic of Korea

Most microfluidic separation techniques rely largely on object size as a separation *** ability to separate micro-objects based on their shape is crucial in various biomedical and chemical ***,we develop an ondemand,label-free acoustofluidic method to separate prolate ellipsoids from spherical microparticles based on traveling surface acoustic wave-induced acoustic radiation force and *** freely rotating non-spherical microobjects were aligned under the progressive acoustic field by the counterrotating radiation torque,and the major axis of the prolate ellipsoids was parallel to the progressive wave *** specific alignment of the ellipsoidal particles resulted in a reduction in the cross-sectional area perpendicular to the wave *** a consequence,the acoustic backscattering decreased,resulting in a decreased magnitude of the radiation *** the variation in radiation force,which depended on the micro-object morphology enabled the acoustofluidic shape-based *** conducted numerical simulations for the wave scattering of spherical and prolate objects to elucidate the working mechanism underlying the proposed method.A series of experiments with polystyrene microspheres,prolate ellipsoids,and peanut-shaped microparticles were performed for *** quantitative analysis of the separation efficiency,we confirmed the high purity and high recovery rate of the proposed acoustofluidic shapebased separation of *** a bioparticle,we utilize Thalassiosira eccentrica to perform shape-based separation,as the species has a variety of potential applications in drug delivery,biosensing,nanofabrication,bioencapsulation and immunoisolation.

关键词： separation spherical rotating

Significantly Improved High-Temperature Energy Storage Performance of BOPP Films by Coating Nanoscale Inorganic Layer

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Energy & Environmental Materials 2024年第2期7卷 30-38页

作者： Tiandong Zhang Hainan Yu young Hoon Jung Changhai Zhang Yu Feng Qingguo Chen Keon jae Lee Qingguo Chi School of Electrical and Electronic Engineering Harbin University of Science and TechnologyHarbin 150080China Department of Materials Science and Engineering Korea Advanced Institute of Science and TechnologyDaejeon 350701Korea

Biaxially oriented polypropylene(BOPP)is one of the most commonly used commercial capacitor films,but its upper operating temperature is below 105℃due to the sharply increased electrical conduction loss at high *** this study,growing an inorganic nanoscale coating layer onto the BOPP film's surface is proposed to suppress electrical conduction loss at high temperature,as well as increase its upper operating *** kinds of inorganic coating layers that have different energy band structure and dielectric property are grown onto the both surface of BOPP films,*** effect of inorganic coating layer on the high-temperature energy storage performance has been systematically *** favorable coating layer materials and appropriate thickness enable the BOPP films to have a significant improvement in high-temperature energy storage ***,when the aluminum nitride(AIN)acts as a coating layer,the AIN-BOPP-AIN sandwich-structured films possess a discharged energy density of 1.5 J cm^(-3)with an efficiency of 90%at 125℃,accompanying an outstandingly cyclic *** the discharged energy density and operation temperature are significantly enhanced,indicating that this efficient and facile method provides an important reference to improve the high-temperature energy storage performance of polymer-based dielectric films.

关键词： coating layer energy storage interfacial barrier polymer films

Long-term outcome of stem cell transplantation with and without anti-tumor necrotic factor therapy in perianal fistula with Crohn’s disease

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World Journal of Stem Cells 2024年第3期16卷 257-266页

作者： Min young Park Yong Sik Yoon jae Ha Park Jong Lyul Lee Chang Sik Yu Division of Colon and Rectal Surgery Department of SurgeryYonsei University College of MedicineSeoul 03722South Korea Division of Colon and Rectal Surgery Department of SurgeryUniversity of Ulsan College of MedicineAsan Medical CenterSeoul 05505South Korea

BACKGROUND Stem cell transplantation is a promising therapeutic option for curing perianal fistula in Crohn’s disease(CD).Anti-tumor necrotic factor(TNF)therapy combined with drainage procedure is effective as ***,previous studies are limited to proving whether the combination treatment of biologics and stem cell transplantation improves the effect of fistula *** This study aimed to evaluate the long-term outcomes of stem cell transplantation and compare Crohn’s perianal fistula(CPF)closure rates after stem cell transplantation with and without anti-TNF therapy,and to identify the factors affecting CPF closure and *** The patients with CD who underwent stem cell transplantation for treating perianal fistula in our institution between Jun 2014 and December 2022 were *** data were compared according to anti-TNF therapy and CPF *** A total of 65 patients were *** median age of females was 26 years(range:21-31)and that of males was 29(44.6%).The mean follow-up duration was 65.88±32.65 months,and complete closure was observed in 50(76.9%)*** closure rates were similar after stem cell transplantation with and without anti-TNF therapy(66.7%vs 81.6%at 3 year,P=0.098).The patients with fistula closure had short fistulous tract and infrequent proctitis and anorectal stricture(P=0.027,0.002,and 0.008,respectively).Clinical factors such as complexity,number of fistulas,presence of concurrent abscess,and medication were not significant for *** cumulative 1-,2-,and 3-year closure rates were 66.2%,73.8%,and 75.4%,*** Anti-TNF therapy does not increase CPF closure rates in patients with stem cell ***,both refractory and non-refractory CPF have similar closure rates after additional anti-TNF *** tract length,proctitis,and anal stricture are risk factors for non-closure in patients with CPF after stem cell transplantation.

关键词： Crohn’s disease Anus Fistula Stem cell transplantation Tumor necrosis factor-alpha inhibitors Infliximab