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Electrochemical partial reduction of Ni(OH)_(2) to Ni(OH)_(2)/Ni via coupled oxidation of an interfacing NiAl intermetallic compound for robust hydrogen evolution

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journal of Energy Chemistry 2023年第7期82卷 560-571,I0012页

作者： young Hwa yun Kwangsoo Kim Changsoo Lee Byeong-Seon An ji Hee Kwon Sechan Lee Minjoong Kim jongsu Seo jong Hyeok Park Byung-hyun Kim hyun-Seok Cho Hydrogen Research Department Korea Institute of Energy Research152 Gajeong-roYuseong-guDaejeon 34129Republic of Korea Computational Science&Engineering Laboratory Korea Institute of Energy Research152 Gajeong-roYuseong-guDaejeon 34129Republic of Korea Analysis Center for Energy Research Korea Institute of Energy Research152 Gajeong-roYuseong-guDaejeon 34129Republic of Korea Department of Chemical and Biomolecular Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea

Ni-based porous electrocatalysts have been widely used in the hydrogen evolution reaction(HER)in alkaline water electrolysis,and the catalysts are produced by selective leaching of Al from Ni-Al *** is well known that chemical leaching of Ni-Al intermetallic compound(IMC)generates a high surface area in Ni(OH)_(2).However,the Ni(OH)_(2) produced by leaching the Ni-Al intermetallic compound retards the hydrogen evolution reaction,which is attributed to its weak hydrogen adsorption *** this study,we controlled the chemical state of Ni using plasma vapor deposition(PVD)followed by heat treatment,selective Al leaching,and electrochemical reduction.X-ray diffraction(XRD),scanning microscopy(SEM),transmission electron microscopy(TEM),and energy-dispersive X-ray spectroscopy(EDS)were used to confirm the phase evolution of the electrocatalysts during *** reveal that the heat-treated Ni-Al alloy with a thick Ni2Al3surface layer underwent selective Al leaching and produced biphasic interfaces comprising Ni(OH)_(2) and NiAl IMCs at the edges of the grains in the outermost surface *** oxidation of the interfacing NiAl IMCs facilitated the partial reduction of Ni(OH)_(2) to Ni(OH)_(2)/Ni in the grains during electrochemical reduction,as confirmed by X-ray photoelectron spectroscopy(XPS).An electrocatalyst containing partially reduced Ni(OH)_(2)/Ni exhibited an overpotential of 54 mV at 10 mA/cm^(2) in a half-cell measurement,and a cell voltage of 1.675 V at 0.4 A/cm2for single-cell operation.A combined experimental and theoretical study(density functional theory calculations)revealed that the superior HER activity was attributed to the presence of partially reduced metallic Ni with various defects and residual Al,which facilitated water adsorption,dissociation,and finally hydrogen evolution.

关键词： Raney nickel HERChemical leaching Intrinsic activity Partial reduction

Is the filamentary dark cloud GF 6 a star forming region?--Stability analysis and infrared properties

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Research in Astronomy and Astrophysics 2017年第12期17卷 77-88页

作者： jaeheon Kim hyun-Goo Kim Sang joon Kim Bo Zhang Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China Korea Astronomy and Space Science Institute Daejeon 34055Korea Department of Astronomy and Space Science Kyung Hee UniversityYongin 17104Korea

We present the results of mapping observations and stability analyses toward the filamentary dark cloud GF 6. We investigate the internal structures of a typical filamentary dark cloud GF 6 to know whether the filamentary dark cloud will form stars. We perform radio observations with both 12CO（j =1–0） and 13CO（j =1–0） emission lines to examine the mass distribution and its evolutionary *** 13CO gas column density map shows eight subclumps in the GF 6 region with sizes on a sub-pc scale. The resulting local thermodynamic equilibrium masses of all the subclumps are too low to form stars against the turbulent dissipation. We also investigate the properties of embedded infrared point sources to know whether they are newly formed stars. The infrared properties also indicate that these point sources are not related to star forming activities associated with GF 6. Both radio and infrared properties indicate that the filamentary dark cloud GF 6 is too light to contract gravitationally and will eventually be dissipated away.

关键词： ISM:clouds ISM:molecules radio lines:ISM infrared:ISM Instabilities Turbulence

Let-7 miRNA and CDK4 siRNA co-encapsulated in Herceptin-conjugated liposome for breast cancer stem cells

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Asian journal of Pharmaceutical Sciences 2020年第4期15卷 472-481页

作者： jeong hyun Shin Dae Hwan Shin jin Seok Kim College of Pharmacy Sookmyung Women’s UniversitySeoul 04310Republic of Korea College of Pharmacy Chungbuk National UniversityCheongju 28160Republic of Korea

Recently,breast cancer stem cells(BCSCs)have rapidly emerged as a novel target for the therapy of breast cancer as they play critical roles in tumor growth,maintenance,metastasis,and ***-7 miRNA is known to be downregulated in a variety of cancers,especially BCSCs,whereas CDK4 being overexpressed in human epidermal growth factor receptor 2(HER-2)overexpressing tumor *** this study,let-7 miRNA and CDK4-specific siRNA were chosen as therapeutic agents and co-encapsulated in Herceptinconjugated cationic liposomes for breast cancer *** size,zeta potential,and encapsulation efficacy of mi/siRNA-loaded PEGylated liposome conjugated with Herceptin(Her-PEG-Lipo-mi/siRNA)were 176 nm,28.1 mV,and 99.7%±0.1%,*** cellular uptake(86%)was observed by fluorescence microscopy when SK-BR-3 cells were treated with Her-PEG-Lipo-mi/***,the increased amount of let-7a mRNA and decreased amount of cellular CDK4 mRNA were observed by qRT-PCR when SK-BR-3 cells were treated with Her-PEG-Lipo-mi/siRNA,which was even more so when SK-BR-3 stem cells were used(197 vs 768 times increase for let-7a,62%vs 68%decrease for CDK4).Growth inhibition(65%)andmigration arrest(0.5%)of the cellswere achieved by the treatment of the cells with Her-PEG-Lipo-mi/siRNA,but not withmi/siRNA complex or other *** conclusion,an efficient liposomal delivery system for the combination of miRNA and siRNA to target the BCSCs was developed and could be used as an efficacious therapeuticmodality for breast cancer.

关键词： Let-7 miRNA CDK4 siRNA Liposomes Breast cancer stem cells

Inhibition behavior of Tragia involucrata L. phenolic compounds against acidic medium corrosion in low carbon steel surface

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Chinese journal of Chemical Engineering 2019年第3期27卷 717-725页

作者： Ill-Min Chung Seung-hyun Kim Venkatesan Hemapriya Kathirvel Kalaiselvi Mayakrishnan Prabakaran Department of Crop Science College of sanghr Life Science Konkuk University Department of Chemistry PSGR Krishnammal College for Women

The antioxidant and anticorrosive effect of Tragia involucrate L.(T. involucrate L.) was evaluated to aid in finding new compounds which can be used for various purposes. The total phenolic(TPC) and flavonoid content(TFC),antioxidant activity(DPPH, reducing potential and phosphomolybdenum), and electrochemical measurements,Fourier transform infrared(FT-IR), UV–visible(UV–vis) spectral analysis, scanning electron microscopy/energydispersive X-ray spectroscopy(SEM–EDX) and atomic force microscopy(AFM) were done to analyze the potency and also the inhibition efficiency of T. involucrate L. against 1 mol·L^(-1) HCl on low carbon steel. The TPC(145.21 mg GAE·g^(-1)), TFC(52.32 mg QCE·g^(-1)) and antioxidant activities were found to be significant. The electrochemical studies performed by AC impedance measurements showed significant changes in impedance spectra without causing any change in Nyquist plots. An increase in charge transfer resistance(Rct) values, a blockage in active sites exhibiting cathodic and anodic inhibition shows the action of inhibitor on low carbon steel. This was later confirmed by FT-IR and UV–vis which showed variation in absorption band at 270 nm and273 nm(before immersion) and 208 and 281 nm(after immersion). The same was tested again by SEM–EDX through altered strength of iron and oxygen bands and using AFM by analyzing the change in average roughness values of low carbon steel before(61.65 nm) and after(97.87 nm) exposure to blank acid without inhibitor, while it was shifted to 81.58 nm in acid with inhibitor. All these results showed strong evidence adding values to T. involucrate L. plant extract in inhibiting corrosion on low carbon steel and by promoting antioxidant importance of the extract which helps in scavenging free radicals.

关键词： Tragia involucrate L Antioxidant Corrosion Adsorption Electrochemistry SEM–EDX–AFM

Promoting dynamic recrystallization and improving strength and ductility of Mg-7Bi alloy through Al addition

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journal of Magnesium and Alloys 2024年第8期12卷 3339-3356页

作者： Gun Woong An Sang-Cheol jin hyun ji Kim Sumi jo Sung Hyuk Park Department of Materials Science and Metallurgical Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Graduate School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

This study investigated the influence of the addition of Al to a Mg-7Bi(B7,wt%)alloy,particularly its recrystallization behavior during extrusion and its resulting mechanical *** addition of 2 wt%Al to the B7 alloy resulted in a lower grain size,a reduction in the number density of fine Mg3Bi2 particles,and a higher area fraction of relatively coarse Mg3Bi2 particles in the extrusion *** microstructural changes increased the nucleation sites for recrystallization,reduced the Zener pinning effect,and enhanced particle-stimulated nucleation,all of which promoted dynamic recrystallization behavior during *** a result,the area fraction of recrystallized grains in the extruded alloy increased from 77%to 94%.The extruded B7 alloy exhibited a strongfiber texture,whereas the extruded Mg-7Bi-2Al(BA72)alloy had a weak-texture,which was attributed to the minimal presence of unrecrystallized grains and the dispersed orientation of the recrystallized *** tensile yield strength(TyS)of the extruded BA72 alloy was higher than that of the extruded B7 alloy(170 and 124 MPa,respectively),which resulted from the enhanced grain-boundary and solid-solution strengthening *** tensile elongation(EL)of the BA72 alloy also exceeded that of the B7 alloy(20.3%and 6.1%,respectively),the result of the uniform formation of fine twins under tension in the former and the formation of a few coarse twins among the unrecrystallized grains in the ***,the addition of a small amount of Al to the B7 alloy significantly improved both the strength and ductility of the extruded alloy,resulting in a remarkable increase in the product of the TyS and EL from 756 to 3451 MPa%and expanding its potential range of applications as a lightweight extruded structural component.

关键词： Mg-7Bi alloy Al addition Extrusion Recrystallization Microstructure

Combined Insights from Leachate Structure and Microstructure Characteristics for Eating Quality of Convenience Rice Processed by Super-Heated and Pressurized Steam Technologies

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Rice science 2024年第4期31卷 475-488,I0035,I0036页

作者： Mingyo HA Hyo-young jEONG ju Hun LEE hyun-jung CHUNG Division of Food and Nutrition Chonnam National UniversityGwangju 61186South Korea Department of Biotechnology College of Life Sciences and BiotechnologyKorea UniversitySeoul 02841South Korea Division of Food Science&Culinary Arts Shinhan UniversityGyeonggi 11644South Korea

Convenience rice has become widely popular due to its easy availability for cooking. This study investigated the starch structure and composition of leachate and the microstructure of reheated convenience rice using novel processing technologies: super-heated steaming(SHS), auto-electric cooking(AEC), and pressurized-steam cooking(PSC). Additionally, the effect of two different target water contents(58% and 63%) was also evaluated. The PSC_63% sample had the highest total solids and amylopectin amount in the leachate. The amylopectin amount in the leachate differed significantly based on the targeted water content. Morphological characterization revealed that the swelling of starch and the coated layer on the surface of rice grains were most pronounced in the PSC_63% sample due to the pressure processing. The textural hardness of the AEC_58% sample was much higher than that of the other samples. The PSC_63% sample had the highest textural adhesiveness value, which can be attributed to the highest amylopectin amount in the leachate. Sensory characterization showed that the PSC_63% sample had the highest glossiness, whiteness, moistness, and overall acceptability. The principal component analysis score plots presented substantial differences in the leachate and textural and sensory characteristics of reheated convenience rice among the different processing technologies.

关键词： reheated convenience rice starch structure leachate multi-scale structure eating quality processing technology

Emission of particulate and gaseous pollutants from household laser processing machine

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journal of Environmental Sciences 2021年第5期33卷 148-156页

作者： hyun Sik Ko Sang Bin jeong Sooyeol Phyo jiwon Lee jae Hee jung Department of Mechanical Engineering Sejong UniversitySeoul 05006Republic of Korea Center for Environment Healthand Welfare ResearchKorea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea Graduate School of Energy and Environment Korea UniversitySeoul 02841Republic of Korea Department o f Materials Science and Engineering Korea UniversitySeoul 02841Republic of Korea

Indoor air quality(IAQ) directly affects the health of occupants. Household manufacturing equipment(HME) used for hobbies or educational purposes is a new and unexplored source of air pollution. In this study, we evaluated the characteristics of particulate and gaseous pollutants produced by a household laser processing equipment(HLPE). Various target materials were tested using a commercial HLPE under various operating conditions of laser power and sheath air flow rate. The mode diameters of the emitted particles gradually decreased as laser power increased, while the particle number concentration(PNC) and particle emission rate(PER) increased. In addition, as the sheath air flow rate quadrupled from 10 to 40 L/min, the mode diameter of the emitted particles decreased by nearly 25%, but the effect on the PNC was insignificant. When the laser induced the target materials at 53 m W, the mode diameters of particles were 2.0 × 10^(4) particles/cm^(3). Particularly, analyses of sampled aerosols indicated that harmful substances such as sulfur and barium were present in particles emitted from leather. The carcinogenic gaseous pollutants such as acrylonitrile, acetaldehyde, 1,3-butadiene, benzene, and C 8 aromatics(ethylbenzene) were emitted from all target materials. In an actual indoor environment, the PNC of inhalable ultrafine particles(UFPs) was > 5 × 10^(4) particles/cm^(3) during 30 min of HLPE operation. Our results suggest that more meticulous control methods are needed, including the use of less harmful target materials along with filters or adsorbents that prevent emission of pollutants.

关键词： Indoor air quality(IAQ) Emission Laser processing Ultrafine particles(UFPs) Volatile organic compounds(VOCs)

Development of vehicle-recognition method on water surfaces using LiDAR data:SPD^(2)(spherically stratified point projection with diameter and distance)

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Defence Technology（防务技术） 2024年第6期36卷 95-104页

作者： Eon-ho Lee Hyeon jun jeon jinwoo Choi hyun-Taek Choi Sejin Lee The Department of Mechanical Engineering Kongju National University1223-24 Cheonan-daeroCheonan 31080Republic of Korea Ocean System Engineering Research Division Korea Research Institute of Ships and Ocean Engineering(KRISO)Daejeon 34103Republic of Korea The Division of Mechanical&Automotive Engineering Kongju National University1223-24 Cheonan-daeroCheonan 31080Republic of Korea

Swarm robot systems are an important application of autonomous unmanned surface vehicles on water *** monitoring natural environments and conducting security activities within a certain range using a surface vehicle,the swarm robot system is more efficient than the operation of a single object as the former can reduce cost and save *** is necessary to detect adjacent surface obstacles robustly to operate a cluster of unmanned surface *** this purpose,a LiDAR(light detection and ranging)sensor is used as it can simultaneously obtain 3D information for all directions,relatively robustly and accurately,irrespective of the surrounding environmental *** the GPS(global-positioning-system)error range exists,obtaining measurements of the surface-vessel position can still ensure stability during platoon *** this study,a three-layer convolutional neural network is applied to classify types of surface *** aim of this approach is to redefine the sparse 3D point cloud data as 2D image data with a connotative meaning and subsequently utilize this transformed data for object classification ***,we have proposed a descriptor that converts the 3D point cloud data into 2D image *** use this descriptor effectively,it is necessary to perform a clustering operation that separates the point clouds for each *** developed voxel-based clustering for the point cloud ***,using the descriptor,3D point cloud data can be converted into a 2D feature image,and the converted 2D image is provided as an input value to the *** intend to verify the validity of the proposed 3D point cloud feature descriptor by using experimental data in the ***,we explore the feasibility of real-time object classification within this framework.

关键词： Object classification Clustering 3D point cloud data LiDAR(light detection and ranging) Surface vehicle

Sub-2 nm mixed metal oxide for electrochemical reduction of carbon dioxide to carbon monoxide

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journal of Energy Chemistry 2023年第9期84卷 303-310页

作者： Devina Thasia Wijaya Andi Haryanto hyun Woo Lim Kyoungsuk jin Chan Woo Lee Department of Chemistry Kookmin UniversitySeoul 02707Republic of Korea Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea Department of Chemistry Korea UniversitySeoul 02841Republic of Korea

Mixed metal oxide(MMO) represents a critical class of materials that can allow for obtaining a dynamic interface between its components:reduced metal and its metal oxide counterpart during an electrocatalytic ***,a synthetic method utilizing a MOF-derived micro/mesoporous carbon as a template to prepare sub-2 nm MMO catalysts for CO_(2) electro reduction is *** from the zeolite imidazolate framework(ZIF-8),the pyrolyzed derivatives were used to synthesize sub-2 nm Pd-Ni MMO with different *** Ni-rich(Pd_(20)-Ni_(80)/ZC) catalyst exhibits unexpectedly superior performance for CO production with an improved Faradaic efficiency(FE) of 95.3% at the current density of 200 mA cm^(-2) at-0.56 V *** hydrogen electrode(RHE) compared to other Pd-Ni compositions.X-ray photoelectron spectroscopy(XPS) analysis confirms the presence of Ni^(2+) and Pd^(2+) in all compositions,demonstrating the presence of *** functional theory(DFT) calculation reveals that the lower CO binding energy on the surface of the Pd_(20)-Ni_(80) cluster eases CO desorption,thus increasing its *** work provides a general synthetic strategy for MMO electrocatalysts and can pave a new way for screening multimetallic catalysts with a dynamic electrochemical interface.

关键词： Carbon dioxide reduction Mixed metal oxide Nanoalloy Carbon monoxide Metal-organic framework