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Fabrication of branch-like Aph@LDH-MgO material through organic-inorganic hybrid conjugation for excellent anti-corrosion performance

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Journal of Magnesium and Alloys 2023年第7期11卷 2469-2485页

作者： Maryam Chafiq Abdelkarim Chaouiki Rachid Salghi Young Gun ko Materials Electrochemistry Laboratory School of Materials Science and EngineeringYeungnam UniversityGyeongsan 38541Republic of Korea Laboratory of Applied Chemistry and Environment ENSAUniversity Ibn ZohrPO Box 1136Agadir80000Morocco

Layered double hydroxides(LDH)frameworks have shown significant enhancement in stability and reusability,and their tailorable architecture brings new insight into the development of the next generation of hybrid materials,which attracted considerable attention in many fields over the *** of the factors contributing to the widespread applicability of layered double hydroxides is their adaptable composition,which can accommodate a wide spectrum of potential anionic *** exceptional property makes the LDH system simple to adjust for various ***,most LDH systems are synthesized in situ in an autoclave at high temperatures and pressures that severely restrict the industrial use of such coating *** this study,LDH was directly synthesized on a magnesium alloy that had undergone plasma electrolytic oxidation(PEO)treatment in the presence of ethylenediaminetetraacetic acid,thereby avoiding the use of hydrothermal autoclave *** LDH system was compared with a hybrid architecture consisting of organic-inorganic *** organic layer was fabricated on top of the LDH film using 4-Aminophenol(Aph)compound,resulting in a smart hierarchical structure that can provide a robust Aph@LDH film with excellent anti-corrosion *** the molecular level,the conjugation characteristics and adsorption mechanism of Aph molecule were studied using two levels of theory as ***,Localized orbit locator(LOL)-πisosurface,electrostatic potential(ESP)distribution,and average local ionization energy(ALIE)on the molecular surface were used to highlight localization region,reveal the favorable electrophilic and nucleophilic attacks,and clearly explore the type of interactions that occurred around interesting ***,first-principles based on density functional theory(DFT)was applied to study the hybrid mechanism of Aph on LDH system and elucidate their mutual *** experimental and computational analyses suggest t

关键词： Magnesium alloy Surface modification LDH Organic-inorganic hybrid materials Inter-/intra-molecular interactions

Influences of Pr and Ta doping concentration on the characteristic features of FTO thin film deposited by spray pyrolysis

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Chinese Physics B 2015年第10期24卷 414-422页

作者： Güven Turgut Adem koqyigit Erdal Snmez Erzurum Technical University Science FacultyDepartment of Basic Sciences Igdir University Engineering FacultyDepartment of Electrical Electronic Engineering Ataturk University Kazim Karabekir Education FacultyDepartment of Physics

The Pr and Ta separately doped FTO（10 at.% F incorporated Sn O2） films are fabricated via spray pyrolysis. The microstructural, topographic, optical, and electrical features of fluorine-doped TO（FTO） films are investigated as functions of Pr and Ta dopant concentrations. The x-ray diffraction（XRD） measurements reveal that all deposited films show polycrystalline tin oxide crystal property. FTO film has（200） preferential orientation, but this orientation changes to（211） direction with Pr and Ta doping ratio increasing. Atomic force microscopy（AFM） and scanning electron microscopy（SEM） analyses show that all films have uniform and homogenous nanoparticle distributions. Furthermore, morphologies of the films depend on the ratio between Pr and Ta dopants. From ultraviolet-visible（UV-Vis） spectrophotometer measurements, it is shown that the transmittance value of FTO film decreases with Pr and Ta doping elements increasing. The band gap value of FTO film increases only at 1 at.% Ta doping level, it drops off with Pr and Ta doping ratio increasing at other doped FTO films. The electrical measurements indicate that the sheet resistance value of FTO film initially decreases with Pr and Ta doping ratio decreasing and then it increases with Pr and Ta doping ratio increasing. The highest value of figure of merit is obtained for 1 at.% Ta- and Pr-doped FTO film. These results suggest that Pr- and Ta-doped FTO films may be appealing candidates for TCO applications.

关键词： Pr-doped FTO Ta-doped FTO spray pyrolysis tin oxide thin films double doping

Cutting force signal pattern recognition using hybrid neural network in end milling

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中国有色金属学会会刊：英文版 2009年第B09期19卷 209-214页

作者： Song-Tae SEONG ko-Tae JO Young-Moon LEE Research and Development Department Gyeongbuk Hybrid Technology Institute School of Mechanical Engineering Yeongnam University School of Mechanical Engineering Kyungpo ok National University

Under certain cutting conditions in end milling, the signs of cutting forces change from positive to negative during a revolution of the tool. The change of force direction causes the cutting dynamics to be unstable which results in chatter vibration. Therefore, cutting force signal monitoring and classification are needed to determine the optimal cutting conditions and to improve the efficiency of cut. Artificial neural networks are powerful tools for solving highly complex and nonlinear problems. It can be divided into supervised and unsupervised learning machines based on the availability of a teacher. Hybrid neural network was introduced with both of functions of multilayer perceptron (MLP) trained with the back-propagation algorithm for monitoring and detecting abnormal state, and self organizing feature map (SOFM) for treating huge datum such as image processing and pattern recognition, for predicting and classifying cutting force signal patterns simultaneously. The validity of the results is verified with cutting experiments and simulation tests.

关键词：切削力信号混合神经网络模式识别铣床人工神经网络切削条件信号监测监督学习

Chemokine-mimetic plerixafor derivative for tumorspecific delivery of nanomaterials

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Nano Research 2018年第4期11卷 2159-2172页

作者： Seungbeom ko Gayong Shim Jinyoung Kim Yu-Kyoung Oh College of Pharmacy and Research Institute of Pharmaceutical Sciences Seoul National University 1 Kwanak-ro Kwanak-gu Seoul 08826 Republic of Korea

Here, we report that chemokine-mimetic plerixafor derivatives could govern tumor-specific delivery and functional effects of nanomaterials. Reduced graphene oxide （rGO） nanosheets were used as a model functional nanomaterial, and plerixafor-conjugated lipid （PL/rGO） or a benzylcyclam derivative of plerixafor- conjugated lipid （BPL/rGO） was physically adsorbed onto the surface of rGO. The cellular uptake of surface-modified rGO was dependent on overexpression of the CXCR4 chemokine receptor on cancer cells. In KB cells, the binding affinity of BPL/rGO for CXCR4 was 6.8-fold greater than that of PL/rGO. Notably, cellular uptake patterns correlated with in vitro photothermal anticancer efficacy. The tumor distribution of BPL/rGO was higher than that of PL/rGO and plain rGO in mice bearing CXCR4-overexpressing tumors, whereas the distribution of the various rGO forms was similar in mice harboring CXCR4-negative tumors. Moreover, complete photothermal tumor ablation was observed in BPL/rGO- treated mice bearing CXCR4-positive KB cell tumors, but not in CXCR4-negative MCF-7 cell tumors. These results provide evidence that BPL can be used to enhance the delivery of nanomaterials to CXCR4-overexpressing tumors. Chemokine-mimetic BPL can be further applied for nanomaterial-based delivery of photosensitizers, anticancer drugs, or diagnostic tumor imaging agents in CXCR4-overexpressing cancer patients.

关键词： chemokine-mimetic plerixafor derivatives chemokine receptor nanomaterial photothermal therapy

3D attitude measurement by means of spread spectrum modulated ultrasonic wave

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仪器仪表学报 2007年第4期28卷 590-596页

作者： Shinji Ohyama Hiroshi Iwasawa Sang Il ko Junya Takayama Graduate School of Science and Engineering Tokyo Institute of Technology2-12-1O-okayamaMeguro-ku Tokyo 152-8552Japan

Local position and attitude measurement methods are necessary for the navigation of autonomous robots and the other applications. In this paper, a 3D attitude measurement method is proposed. This method uses the spread spectrum modulated ultrasonic wave for the measurement of the pseudo-distance of each pathway between transmitter and receiver elements that are arranged in an array. The relative attitude between transmitter and receiver unit could be calculated from the relationship between these pseudo-distances. The use of spread spectrum modulation enables the high accuracy, noise tolerance, and coexistence of multiple transmitter devices by code division multiple access (CDMA) between transmitter and receiver elements. A pair of transmitter and receiver prototype for proposed method was manufactured, and the fundamental performance was examined in experiments. As a result, accuracy of σ=0.78 mm in the pseudo-distance measurement of each pathway between transmitter and receiver elements was confirmed, and about 0.01 rad resolution in the attitude measurement was also confirmed.

关键词：姿态测量准距离伸展光谱超声波

Tetramethylammonium Iodide Additive for Enhancing the Charge Carrier Mobilities of Diketopyrrolopyrrole-Based Conju-gated Polymer in Ambipolar Organic Field-Effect Transistors

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Chinese Journal of Chemistry 2023年第9期41卷 1028-1036页

作者： Waner He Qian Liu Sultan Otep Hidetoshi Matsumoto Sergei Manzhos Prashant Sonar Aung ko ko Kyaw Tsuyoshi Michinobu Department of Materials Science and Engineering Tokyo Institute of TechnologyTokyo 152-8552Japan Guangdong University Key Laboratory for Advanced Quantum Dot Displays Department of Electrical and Electronic EngineeringSouthern University of Science and TechnologyShenzhenGuangdong 518055China Center for Materials Science School of Chemistry and PhysicsFaculty of ScienceQueensland University of TechnologyBrisbaneQLD 4000Australia School of Materials and Chemical Technology Tokyo Institute of TechnologyTokyo 152-8552Japan

Diketopyrrolopyrrole(DPP)is one of the most promising building blocks for constructing polymer semiconductors with high charge-carrier mobilities in organic field-effect transistors(OFETs).In this study,a novel DPP-based conjugated polymer,PDPPy-BDD,was designed and *** ambipolar field-effect transistor characteristics were realized with the average hole and electron mobilities of 3.5×10^(-3)and 3.07×10^(-2)cm^(2)V^(-1)s^(-1),*** the hole and electron mobilities could be successfully en-hanced by using a tetramethylammonium iodide(NMe4l)*** an enhancement was attributed to the formation of stronger interchainπ-πstackings,the weakening of the face-on packing orientation in the thin film state,and the higher channel conductivi-ties in the OFETs.

关键词： Diketopyrrolopyrrole Pyridine Charge transport Conjugated polymers Organic field-effect transistors Semiconductors Tetramethylammonium iodide Thin films

Magnetic resonance spectroscopy in Leigh-MELAS overlap syndrome

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World Journal of Pediatrics 2019年第3期15卷 306-308页

作者： Ara.ko Young-Mock Lee Department of Pediatrics Pusan National University Children’S HospitalPusan National University School of MedicineYangsanKorea Research Institute for Convergence of Biomedical Science and Technology Pusan National University Yangsan HospitalYangsanRepublic of Korea Department of Pediatrics Gangnam Severance HospitalYonsei University College of Medicine201 1 Eonju—roGangnam—guSeoul 06273South Korea

A 4-year-old boy presented with insidious psychomotor regression at the age of 12 *** MRI revealed symmetric lesions in the bilateral basal ganglia (Fig.1a),whereas brain magnetic resonance spectroscopy (MRS) revealed no abnormalities (***).Muscle biopsy revealed ragged red fibers,megaconia,and mitochondrial respiratory chain complex I *** investigation confirmed the ND3 mitochondrial mutation 10191T>*** was diagnosed with Leigh *** years later,he experienced *** revealed new focal diffusion-restricted lesions in multiple cortices (Fig.2a),and MRS revealed an inverted doublet lactate peak (Fig.2b).He was finally diagnosed with Leigh-MELAS overlap syndrome.

关键词： Magnetic resonance spectroscopy Leigh-MELAS overlap syndrome

Tribological properties of hierarchical micro-dimples produced on a cylindrical surface by dual-frequency texturing

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Friction 2023年第2期11卷 246-258页

作者： Saood ALI Rendi KURNIAWAN Park Gun CHUL Tae Jo ko School of Mechanical Engineering Yeungnam UniversityGyeongsan-si 712749Republic of Korea

An experimental investigation was performed for investigating the tribological performance of micro-dimple surface texture patterns on a cylindrical surface in a realistic operating environment of starved lubrication. Micro-dimples were generated by a dual-frequency surface texturing method, in which a high-frequency (16.3 kHz) three-dimensional (3D) vibration and a low-frequency (230 Hz) one-dimensional (1D) vibration were applied at the tool tip simultaneously, resulting in the generation of the hierarchical micro-dimples in a single step. Rotating cylinder-on-pin tribological tests were conducted to compare the tribological performance of the non-textured reference specimen and micro-dimple samples. The effect of surface textures generated with various shape parameters (long drop and short drop), dimension parameters (length and surface texture density), and operation parameters (load and sliding velocity) on the tribological performance was evaluated. Stribeck curves indicate that the hierarchical micro-dimples exhibit a lower coefficient of friction than the reference specimen in the high contact-pressure regions. It is also observed that variation in the length of a micro-dimple, the shape effect, is the major factor affecting the friction response of the textured surfaces. The generation of additional hydrodynamic pressure and lift effect by hierarchical structures is the main reason for the improved performance of hierarchical micro-dimple surfaces.

关键词： dual-frequency surface texturing hierarchical surfaces tribology starved lubrication three-dimensional elliptical vibration transducer

SHEAR STRESS ANALYSIS OF TIMOSHENko'S BEAM WITH MULTIPLY CONNECTED CROSS SECTION

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Acta Mechanica Solida Sinica 2001年第1期14卷 48-57页

作者： Li Zhaoxia.ko Janming Ni Yiqing College of Civil Engineering Southeast University Nanjing 210018 China Department of Civil and Structural EngineeringThe Hong Kong Polytechnic University Kowloon Hong Kong Department of Civil and Structural EngineeringThe Hong Kong Polytechnic University Kowloon Hong Kong

In this paper, a finite element method is developed to numericallyevaluate the shear coefficient of Timoshenko's beam with multiplyconnected cross section. With focus on analyzing shear stressesdistributed at the neutral axis of the beam, an improved definitionof the shear coeffi- cient is presented. Based on this definition, aGalerkin-type finite element formulation is proposed to analyze theshear stresses and shear deflections. Numerical solutions of theexamples for some typical cross-sections are compared with thetheoretical results. The shear coefficient of tower sections of theTsing Ma Bridge is calculated by use of the proposed approach, sothat the finite element modeling of The bridge can be developed withthe accurate values of the sectional properties.

关键词： Timoshenko's beam multiply connected cross section shear coefficient elasticity