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Suppression of gold nanoparticle agglomeration and its separation via nylon membranes

Chinese Journal of Chemical Engineering 2017年第7期25卷 931-937页

作者： Ayyavoo Jayalakshmi In-Chul kim young-Nam Kwon School of Urban and Environmental Engineering Ulsan National Institute of Sdence and TechnologyUlsan 689-798Korea KIST-UNIST UIsan Center for Convergent Materials UNIST(Ulsan National Institute of Science and Technology)Korea Environment and Resources Research Center Korea Research Institute Chemical TechnologyDaejeon 305-606Korea

Use of ultraporous nylon membrane is one of the most widely employed techniques for removal of hard and soft nanoparticles in the semiconductor industry, and the accurate determination of membrane pore size is necessary in order to avoid manufacturing defects caused by contamination. The gold nanoparticle has several benefits for the evaluation of polymeric membranes; however, the nanoparticles agglomerate easily on the nylon membrane and make it difficult to evaluate the membrane precisely. The properties of 2-amino-2-hydroxymethyl-1,3-propanediol(ADP) ligand in gold nanoparticle solution were systematically investigated, and ADP was utilized for improved evaluation of the nylon membranes. Nylon membrane used in this study was prepared by phase inversion techniques. Ultrathin dense layer on top of the membrane surface and Darcy structures in the microporous membrane support were observed. The gold particle rejection was carried out at various p H values from 4 to14 and higher rejection was observed at p H 4 and 8. The suppression of gold colloid agglomeration using ADP and monodispersity of gold colloids was also analyzed by confocal laser scanning microscopy(CLSM), transmission electron microscopy(TEM), and scanning electron microscopy(SEM). van der Waals interaction energy of the particles was reduced in the addition of ADP. The presence of ADP ligand in the gold solutions prevented the agglomeration of gold nanoparticles and reduced the adsorption of the particles on the nylon membrane surface,leading to precise evaluation of membrane pore sizes.

关键词： Particle size Electron microscopy Gold colloid flock Semiconductor

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Long-term result of endoscopic Histoacryl （N-butyl-2-cyanoacrylate）injection for treatment of gastric varices

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World Journal of Gastroenterology 2011年第11期17卷 1494-1500页

作者： Eun Jung Kang Soung Won Jeong Jae young Jang Joo young Cho Sae Hwan Lee Hyun Gun kim Sang Gyune kim young Seok kim young Koog Cheon young Deok Cho Hong Soo kim Boo Sung kim Institute for Digestive Research Department of Internal MedicineSoonchunhyang University College of MedicineSeoul HospitalSeoul 140-743South Korea

AIM:To evaluate the long-term efficacy and safety of endoscopic obliteration with Histoacryl  for treatment of gastric variceal bleeding and ***:Between January 1994 and March 2010 at SoonChunHyang University Hospital,a total of 127 patients with gastric varices received Histoacryl  injections *** hundred patients underwent endoscopic Histoacryl  injections because of variceal bleeding,the other 27 patients received such injections as a prophylactic ***:According to Sarin classification,56 patients were GOV1,61 patients were GOV2 and 10 patients were *** of the varices were large(F2 or F3,111 patients).The average volume of Histoacryl  per each session was 1.7±1.3 cc and mean number of sessions was 1.3±0.6.(1 session-98 patients,2 sessions-25 patients,≥3 sessions-4 patients).Twenty-seven patients with high risk of bleeding(large or fundal or RCS+or Child C) received Histoacryl  injection as a primary prophylactic *** these patients,hepatitis B virus was the major etiology of cirrhosis,25 patients showed GOV1 or 2(92.6%)and F2 or F3 accounted for 88.9%(n=24).The rate of initial hemostasis was 98.4%and recurrent bleeding within one year occurred in 18.1%of *** hemostasis during episodes of rebleeding was achieved in 73.9%of *** survival was 50 mo (95%CI 30.5-69.5).Major complications occurred in 4 patients(3.1%).The rebleeding rate in patients with hepatocellular carcinoma or GOV2 was higher than in those with other *** of the 27 subjects who were treated prophylactically experienced treatment-related *** survival rates of the 127 patients at 6 mo,1,3,and 5 years were 92.1%,84.2%,64.2%,and 45.3%,*** 6 mo cumulative survival rate of the 27 patients treated prophylactically was 75%.CONCLUSION:Histoacryl  injection therapy is an effective treatment for gastric varices and also an effective prophylactic treatment of gastric varices which

关键词： Gastric varix Prophylaxis Histoacryl  (Nbutyl-2-cyanoacrylate) Histoacryl  injection Treatment of gastric varix

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Byte Frequency Based Indicators for Crypto-Ransomware Detection from Empirical Analysis

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Journal of Computer Science & Technology 2022年第2期37卷 423-442页

作者： Geun Yong kim Joon-young Paik Yeongcheol kim Eun-Sun Cho Department of Computer Science and Engineering Chungnam National UniversityDaejeon 34134South Korea School of Computer Science and Technology Tiangong UniversityTianjin 300387China

File entropy is one of the major indicators of crypto-ransomware because the encryption by ransomware increases the randomness of file ***,entropy-based ransomware detection has certain limitations;for example,when distinguishing ransomware-encrypted files from normal files with inherently high-level entropy,misclassification is very *** addition,the entropy evaluation cost for an entire file renders entropy-based detection impractical for large *** this paper,we propose two indicators based on byte frequency for use in ransomware detection;these are termed EntropySA and DistSA,and both consider the interesting characteristics of certain file subareas termed“sample areas”(SAs).For an encrypted file,both the sampled area and the whole file exhibit high-level randomness,but for a plain file,the sampled area embeds informative structures such as a file header and thus exhibits relatively low-level randomness even though the entire file exhibits high-level *** and DistSA use“byte frequency”and a variation of byte frequency,respectively,derived from sampled *** indicators cause less overhead than other entropy-based detection methods,as experimentally proven using realistic ransomware *** evaluate the effectiveness and feasibility of our indicators,we also employ three expensive but elaborate classification models(neural network,support vector machine and threshold-based approaches).Using these models,our experimental indicators yielded an average Fl-measure of 0.994 and an average detection rate of 99.46%for file encryption attacks by realistic ransomware samples.

关键词： computer security cryptography machine learning ransomware

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Fabrication of heteroatom-doped cobalt oxide yolk-shell microsphere using recycled solution from waste materials and their excellent electrochemical properties as an anode material for lithium-ion batteries

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Rare Metals 2024年第10期43卷 4934-4947页

作者： Yeong Beom kim chanho kim Seung-Hyun kim Yun chan Kang Dongju Lee Gi Dae Park Department of Advanced Materials Engineering Chungbuk National UniversityChungbuk 28644Korea Department of Materials Science and Engineering Korea UniversitySeoul 136-713Korea Research Institute YKSintering Co.Ltd.Chungbuk 28581Korea

Heteroatom-doped transition metal oxides have attracted great attention as advanced anode materials for lithium-ion batteries due to their high theoretical capacity and superior ***,the limited resource availability has led to a substantial rise in prices for valuable metals such as Ni and Co,posing a significant challenge for their *** address this issue,recycling of these metals from waste materials have gained prominence,and particularly the recovery of Co has been mostly focused on its economic ***,we introduced a novel recycling strategy for fabrication of heteroatomdoped CoO_(x)(comprising mainly Co_(3)O_(4)with a minor CoO phase)anode with a yolk–shell structure for lithium-ion batteries,by separating Co from cemented tungsten carbide *** employing a simple leaching process and subsequent spray pyrolysis,the yolk–shell structured microsphere comprising CoO_(x)was successfully ***,the presence of other waste metals in the leachate facilitated multi-heteroatom doping during ***,the introduction of various dopants into CoO_(x)induced oxygen vacancy formation,thereby enhancing the electrochemical properties of the CoO_(x)*** a result,compared with the phase-pure(undoped)CoO_(x)yolk–shell,the heteroatom-doped CoO_(x)yolk–shell exhibited robust cycling stability(602 mAh·g^(-1)for 200 cycles at 1 A·g^(-1))and excellent rate capability(210 mAh·g^(-1)at 10 A·g^(-1)).

关键词： Recycling Heteroatom doping Cobalt oxide Anode Lithium-ion batteries

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Effect of Ca addition on the microstructure and mechanical properties of heat-treated Mg-6.0Zn-1.2Y-0.7Zr alloy

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Journal of Magnesium and Alloys 2021年第5期9卷 1636-1648页

作者： young Gil Jung Wonseok Yang Yong Joo kim Shae.K.kim young Ok Yoon Hyunkyu Lim Do Hyang kim Advanced Materials and Process R&D Department Korea Institute of Industrial Technology156Gaetbeol-roIncheon 21999Republic of Korea Department of Metallurgical Engineering Yonsei University50Yonsei-roSeoulSeodaemun-gu 03722Republic of Korea

In this study,the effects of Ca addition on the microstructure,thermal properties,and mechanical properties of a Mg-6.0Zn-1.2Y-0.7Zr(ZWK611)alloy at room temperature and 150℃ were *** an increase in the Ca content,the ignition resistance of the ZWK611 alloy improved and the grains became *** as-cast ZWK611 alloy consisted mainly of the dendriticα-Mg matrix and I-phase(Mg_(3)Zn_(6)Y)at the grain *** the other hand,theτ-(Ca_(2)Mg_(6)Zn_(3))and I-phases were formed in the Ca-added ZWK611 *** fraction of theτ-phase increased with an increase in the Ca *** the solid-solution treatment,these phases remained partially at the grain boundaries of the Ca-added ZWK611 alloys and an additional W-phase(Mg_(3)Zn_(3)Y)was *** phases remaining at the grain boundaries restricted the grain growth through the grain boundary pinning *** aging treatment resulted in the formation of MgZn'precipitates in theα-Mg matrix of the *** precipitates were more uniformly distributed in the Ca-added alloys than in the alloys without ***,the heat treatment-induced precipitation improved the tensile and creep properties of the T6-treated *** T6-treated ZWK611+0.7Ca alloy exhibited the best mechanical properties at room temperature and 150℃ among all the tested alloys.

关键词： Mg-Zn-Y alloys Heat-treatment Precipitate Mechanical properties Thermal analysis

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Chemical surface tuning of zinc metal anode toward stable,dendrite-less aqueous zinc-ion batteries

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Journal of Energy Chemistry 2023年第11期86卷 1-8,I0001页

作者： Pranav Kulkarni Sun-Sik kim Hyun young Jung Department of Energy Engineering Gyeongsang National UniversityJinju-siGyeongnam 52725South Korea Department of Energy System Engineering Gyeongsang National UniversityJinju-siGyeongnam 52725South Korea

The commercialization of Zn batteries is confronted with urgent challenges in the metal anode,such as dendrite formation,capacity loss,and cracking or ***,surface interfacial engineering of the Zn anode is introduced for achieving safety and dendritic-free cycling for high-performance aqueous Zn batteries through a simple but highly effective chemical etching-substitution *** chemical modification induces a rough peak-valley surface with a thin fluorine-rich interfacial layer on the Zn anode surface,which regulates the growth orientation via guiding uniform Zn plating/stripping,significantly enhances accessibility to aqueous electrolytes and improves wettability by reducing surface *** a result,such a synergetic surface effect enables uniform Zn plating/stripping with low polarization of 29 m V at a current density of 0.5 m A cm^(-2) with stable cyclic performance up to 1000 ***,a full cell composed of a fluorine-substituted Zn anode coupled with aβ-MnO_(2)or Ba-V_(6)O_(13)cathode demonstrates improved capacity retention to 1000 cycles compared to the pristine-Zn *** proposed valley deposition model provides the practical direction of surface-modified interfacial chemistries for improving the electrochemical properties of multivalent metal anodes via surface tuning.

关键词： Dendrite free Peak-Valley surface Zinc-ion batteries Surface modification Fluorinated interface

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Liquid crystal-powered Mie resonators for electrically tunable photorealistic color gradients and dark blacks

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Light(Science & Applications) 2022年第6期11卷 1098-1108页

作者： Trevon Badloe Joohoon kim Inki kim Won-Sik kim Wook Sung kim young-Ki kim Junsuk Rho Department of Mechanical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Department of Biophysics Institute of Quantum BiophysicsSungkyunkwan UniversitySuwon 16419Republic of Korea Department of Intelligent Precision Healthcare Convergence Sungkyunkwan UniversitySuwon 16419Republic of Korea Department of Chemical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Department of Electrical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea POSCO-POSTECH-RIST Convergence Research Center for Flat Optics and Metaphotonics Pohang 37673Republic of Korea National Institute of Nanomaterials Technology(NINT) Pohang 37673Republic of Korea

Taking inspiration from beautiful colors in nature,structural colors produced from nanostructured metasurfaces have shown great promise as a platform for bright,highly saturated,and high-resolution *** plasmonic and dielectric materials have been employed to produce static colors that fulfil the required criteria for high-performance color printing,however,for practical applications in dynamic situations,a form of tunability is *** of the additive color palette of red,green,and blue enable the expression of further colors beyond the three primary colors,while the simultaneous intensity modulation allows access to the full color ***,we demonstrate an electrically tunable metasurface that can represent saturated red,green,and blue pixels that can be dynamically and continuously controlled between on and off states using liquid *** use this to experimentally realize ultrahigh-resolution color printing,active multicolor cryptographic applications,and tunable pixels toward high-performance full-color reflective displays.

关键词： saturated printing colors

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Construction of a High‑Performance Composite Solid Electrolyte Through In‑Situ Polymerization within a Self‑Supported Porous Garnet Framework

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Nano-Micro Letters 2024年第5期16卷 56-70页

作者： An‑Giang Nguyen Min‑Ho Lee Jaekook kim chan‑Jin Park Department of Materials Science and Engineering Chonnam National University77 Yongbong‑roBuk‑guGwangju 61186South Korea

Composite solid electrolytes(CSEs)have emerged as promising candidates for safe and high-energy–density solid-state lithium metal batteries(SSLMBs).However,concurrently achieving exceptional ionic conductivity and interface compatibility between the electrolyte and electrode presents a significant challenge in the development of high-performance CSEs for *** overcome these challenges,we present a method involving the in-situ polymerization of a monomer within a self-supported porous Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZT)to produce the *** synergy of the continuous conductive LLZT network,well-organized polymer,and their interface can enhance the ionic conductivity of the CSE at room ***,the in-situ polymerization process can also con-struct the integration and compatibility of the solid electrolyte–solid electrode *** synthesized CSE exhibited a high ionic conductivity of 1.117 mS cm^(-1),a significant lithium transference number of 0.627,and exhibited electrochemical stability up to 5.06 V ***/Li+at 30℃.Moreover,the Li|CSE|LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cell delivered a discharge capacity of 105.1 mAh g^(-1) after 400 cycles at 0.5 C and 30℃,corresponding to a capacity retention of 61%.This methodology could be extended to a variety of ceramic,polymer electrolytes,or battery systems,thereby offering a viable strategy to improve the electrochemical properties of CSEs for high-energy–density SSLMBs.

关键词： Scalable tape-casting method Self-supported porous Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12) Composite solid electrolyte LiF-and B-rich interphase layers

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Stabilizing lithium deposition within bimodal porous SiO_(2)-TiO_(2) microspheres as 3D host structure

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Nano Research 2024年第11期17卷 10179-10188页

作者： Noeul kim Jae Hun Choi Min kim Dae Soo Jung Yun chan Kang Department of Materials Science and Engineering Korea University Anam-Dong Seongbuk-Gu Seoul 136-713 Republic of Korea Energy Storage Materials Center Korea Institute of Ceramic Engineering and Technology Soho-ro Jinju-si Gyeongnam-do 52851 Republic of Korea

Three-dimensional (3D) host materials for lithium metal anodes (LMAs) have gained attention because they can mitigate volume expansion and local current density through their large surface area and suppress the dendritic growth of lithium. Recent research on 3D host materials has focused on conductive materials;however, the benefits of 3D host materials cannot be fully utilized because lithium deposition begins at the top of the structure. Herein, we fabricate SiO_(2)-TiO_(2) composite microspheres with bimodal pore structures (bi-SiTiO) by simple spray pyrolysis. These microspheres effectively store lithium within the structure from the bottom of the electrode while preventing lithium dendrite formation. Focused ion beam-scanning transmission electron microscopy (FIB-STEM) analysis reveals that the lithiophilic properties of composite microspheres enhanced their effectiveness in storing lithium, with small pores acting as “lithium-ion sieves” for a uniform lithium-ion flux and large pores that provide sufficient volume for lithium deposition. The bi-SiTiO composite microspheres exhibit a high Coulombic efficiency of 98.5% over 200 cycles at 2.0 mA·cm^(−2) when operated in a lithium half-cell. With a high lithium loading of 5.0 mAh·cm^(−2), the symmetrical cell of the bi-SiTiO electrode sustains more than 900 h. A full cell coupled with an LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) (NCM811) cathode also exhibits enhanced electrochemical properties in terms of cycling stability and rate capability.

关键词： lithium metal battery spray pyrolysis three-dimensional(3D)host materials bimodal pore structure lithiophilic materials

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Evolution of microstructure and tensile properties of cold-drawn hyper-eutectoid steel wires during post-deformation annealing

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Journal of Materials Science & Technology 2020年第6期41卷 1-11页

作者： Majid Jafari chan-Woo Bang Jong-chan Han Kyeong-Min kim Seon-Hyeong Na chan-Gyung Park Byeong-Joo Lee Department of Materials Science and Engineering POSTECH Pohang 37673 South Korea

Manufacturing temperatures of severely cold-drawn hyper-eutectoid steel wires are sufficiently high to influence the mobility of dislocations and alloy elements,thereby affecting the materials’mechanical ***,we describe the evolution of microstructure and tensile strength of the as-drawn 3.45 GPa steel wire during post-deformation annealing for 30 min at 150-450℃.Annealing at 150℃raised the strength to 3.77 GPa by age-hardening through activation of dislocations pinning by carbon,while further temperature rising up to 450℃caused a severe loss of *** was proved that annealing at 300 and 450℃destabilizes the lamellar microstructure,promoting the formation of carbon-deficient(Fe,Mn,Cr)3 C-type cementite particles with preferentially rounded and partially faceted *** at 450℃yielded the accumulation of Mn and Cr at the ferrite/particle interfaces,and their concentrations at the interfaces were dependent on the interface structure;i.e.,lower concentrations at rounded interfaces(formed through capillarity–driven coarsening of the spheroidized cementite),and higher concentrations at faceted interfaces(that are initially existing in the as-drawn state).Our proof-of-principle observations,supported by thermodynamic calculations and kinetic assessments,provide a pathway for understanding the changes in microstructural and tensile properties during manufacturing of the hyper-eutectoid steel wires.

关键词： Three-dimensional atom probe(3DAP) High resolution transmission electron microscopy(HRTEM) Nano-grained low-carbon steel Annealing Tensile behavior

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