检索结果-南通市图书馆

Effect of ammonia gas etching on growth of vertically aligned carbon nanotubes/nanofibers

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 130-134页

作者： Sang-Gook KIM Sooh-Yung KIM hyung-woo lee Department of Mechanical Engineering Massachusetts Institute of Technology 77 Massachusetts Ave Cambridge MA 02139 USA National Core Research Center for Hybrid Materials Solution Pusan National University

The etching effect of ammonia (NH3) on the growth of vertically aligned nanotubes/nanofibers (CNTs) was investigated by direct-current plasma enhanced chemical vapor deposition (DC-PECVD). NH3 gas etches Ni catalyst layer to form nanoscale islands while NH3 plasma etches the deposited amorphous carbon. Based on the etching effect of NH3 gas on Ni catalyst, the differences of growing bundles of CNTs and single strand CNTs were discussed; specifically, the amount of optimal NH3 gas etching is different between bundles of CNTs and single strand CNTs. In contrast to the CNT carpet growth, the single strand CNT growth requires shorter etching time (5 min) than large catalytic patterns (10 min) since nano dots already form catalyst islands for CNT growth. Through removing the plasma pretreatment process, the damage from being exposed at high temperature substrate occurring during the plasma generation time is minimized. High resolution transmission electron microscopy (HTEM) shows fishbone structure of CNTs grown by PECVD.

关键词：碳纳米管垂直排列纳米纤维等离子体增强化学气相沉积生长氨气高分辨透射电子显微镜等离子蚀刻

Highly efficient and stable solid-state fiber dye-sensitized solar cells with Ag-decorated SiO_(2) nanoparticles

在线全文

学校读者我要写书评

暂无评论

Nano Research 2021年第8期14卷 2728-2734页

作者： Jae Ho Kim Seok-Ju Yoo Daseul lee Jin woo Choi Sang-Cheol Han Tae In Ryu hyung woo lee Myunghun Shin Myungkwan Song Materials Center for Energy Convergence Korea Institute of Materials Science(KIMS)797Changwon-daeroSungsan-guChangwonGyeongsangnam-do51508Republic of Korea CEN Nano.Co.Ltd. Nano Convergence CenterMuan-roBuduk-myeonMiryang-siGyeongsangnam-do50404Republic of Korea Accident Coordination and Training Division National Institute of Chemical Safety(NICS)90Gajeongbuk-roYuseong-guDaejeon34114Republic of Korea Department of Nanoenergy Engineering and Research Center of Energy Convergence Technology Pusan National UniversityBusandaehak-ro 63-2Geumjeong-guBusan 46241Republic of Korea School of Electronics and Information Engineering Korea Aerospace University Goyang-cityGyeonggi-do10540Republic of Korea

Fiber-shaped dye-sensitized solar cells(FDSSCs)represent promising futuristic flexible or wearable power sources,owing to their simple fabrication process,light weight,weavability,and *** with strategies on changing the properties of semiconductor materials,the effects of incorporating silver-embedded SiO_(2) nanoparticles(Ag@SiO_(2)NPs)on the photoanodes of solid-state FDSSCs(SS-FDSSCs)are *** power conversion efficiency(PCE)of SS-FDSSCs with Ag@SiO_(2) NPs reaches 5.38%,which is comparable to the reference(3.98%).The PCEs remain at 95%between-16.9 and 91.7℃,indicating the operational stability of SS-FDSSCs within this temperature *** fabricated SS-FDSSCs,whose radii were 2 mm,maintains more than 90%of their efficiency over 500 bending cycles and 10 washing cycles.

关键词： dye-sensitized solar cells fiber-shaped solar cells SiO_(2)nanoparticles plasmonic effect solid-state electrolyte

Distribution of electric field for carbon nanotube assembly: Experiments (II)

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 121-125页

作者： Soongeun KWON Soo-Hyun KIM Kwang-ho KIM Myung-chang KANG hyung-woo lee Department of Mechanical Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon 305-701 Korea National Core Research Center for Hybrid Materials Solution Pusan National University

The distribution effect of electric field on the alignment and attachment of carbon nanotubes (CNTs) were investigated. The experimental results were compared with the simulation results according to three different shaped electrodes. In previous simulation, the round shaped electrodes were expected to be more effective for aligning and attaching a single CNT between two electrodes than conical or rectangular shaped electrodes. To verify the simulation results, three different shaped electrodes were introduced and a single multi-walled carbon nanotube (MWNT) was attached. The optimal conditions for aligning and attaching MWNTs such as the frequency, applied voltage and concentration of MWNTs solution were investigated. Through repeated experiments, frequency of 100 kHz-10 MHz, applied voltage of 0.3-1.3 Vrms/μm, concentration of 5 μg/mL in MWNTs solution were obtained as a possible condition range to attach MWNTs. Under these conditions, the yield of MWNTs attachment between two electrodes was up to 70%. In previous simulation, furthermore, it was verified that the size of the stable or quasi-stable region made CNTs aligned and attached on different shaped electrodes from the comparison of the experimental and simulation results. Most single MWNT attachment was accomplished on the round shaped electrodes.

关键词：多壁碳纳米管电场分布实验组装单壁碳纳米管稳定区域 MWNT 最佳条件

Dielectrophoretic assembly of semiconducting single-walled carbon nanotube transistor

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 126-129页

作者： Se-Hun KWON Young-Keun JEONG Soongeun KWON Myung-Chang KANG hyung-woo lee National Core Research Center for Hybrid Materials Solution Pusan National University Department of Mechanical Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon 305-701 Korea

A novel burning technique for making a semiconducting single-walled carbon nanotubes (SWNTs) transistor assembled by the dielectrophoretic force was suggested. The fabrication process consisted of two steps. First, to align and attach a bundle of SWNTs between the source and drain, the alternating (AC) voltage was applied to the electrodes. When a bundle of SWNTs was connected between two electrodes, some of metallic nanotubes and semi-conducing nanotubes existed together. The second step is to burn the metallic SWNTS by applying the voltage between two electrodes. With increasing the voltage, more current flowed through the metallic SWNTs, thus, the metallic SWNTs burnt earlier than the semiconducting one. This technique enables to obtain only semi-conducting SWNTs connection in the transistor. Through the I—V characteristic graph, the moment of metallic SWNTs burning and the characteristic of semi-conducing nanotubes were verified.

关键词：碳纳米管晶体管单壁碳纳米管束半导体燃烧技术制造过程 SWNTs 管连接特性图

Characteristic evaluation of Al_2O_3/CNTs hybrid materials for micro-electrical discharge machining

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 28-32页

作者： Hyun-Seok TAK Chang-Seung HA Ho-Jun lee hyung-woo lee Young-Keun JEONG Myung-Chang KANG National Core Research Center for Hybrid Materials Solution Pusan National University Department of Electrical Engineering Pusan National University

The characteristic evaluation of aluminum oxide (Al2O3)/carbon nanotubes (CNTs) hybrid composites for micro-electrical discharge machining (EDM) was described. Alumina matrix composites reinforced with CNTs were fabricated by a catalytic chemical vapor deposition method. Al2O3 composites with different CNT concentrations were synthesized. The electrical characteristic of Al2O3/CNTs composites was examined. These composites were machined by the EDM process according to the various EDM parameters, and the characteristics of machining were analyzed using field emission scanning electron microscope (FESEM). The electrical conductivity has a increasing tendency as the CNTs content is increased and has a critical point at 5% Al2O3 (volume fraction). In the machining accuracy, many tangles of CNT in Al2O3/CNTs composites cause violent spark. Thus, it causes the poor dimensional accuracy and circularity. The results show that conductivity of the materials and homogeneous distribution of CNTs in the matrix are important factors for micro-EDM of Al2O3/CNTs hybrid composites.

关键词：加工特性混合材料微细电火花加工混杂复合材料场发射扫描电子显微镜微放电催化化学气相沉积法碳纳米管

Distribution of electric field for carbon nanotube assembly: Simulation (I)

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 117-120页

作者： Soon-Geun KWON Soo-Hyun KIM Kwang-Ho KIM Myung-Chang KANG hyung-woo lee Department of Mechanical Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon 305-701 Korea National Core Research Center for Hybrid Materials Solution Pusan National University

The distribution of electric field for the alignment and attachment of carbon nanotubes (CNTs) was simulated. To be attached at the desired place, the aligned and attracted CNTs should be stayed in the desired area called the stable region or the quasi-stable region for an instant where the change of electric field is minimized. Since the conical electrode has the very narrow sized quasi-stable region, few CNTs can be attached. The rectangular electrodes have a wide stable region, so lots of CNTs can be attached. The results indicate that the round electrode which has a proper sized quasi-stable region is more effective for aligning and attaching a single CNT than the conical or rectangular shaped electrodes.

关键词：碳纳米管电场分布数值模拟组装电场变化圆锥形稳定电极

In situ infrared, Raman and X-ray spectroscopy for the mechanistic understanding of hydrogen evolution reaction

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第3期90卷 632-651,I0014页

作者： Andi Haryanto Kyounghoon Jung Chan woo lee Dong-Wan Kim Department of Chemistry Kookmin UniversitySeoul 02707Republic of Korea School of Civil Environmental and Architectural EngineeringKorea UniversitySeoul 02841Republic of Korea

Hydrogen production by water reduction reactions has received considerable attention because hydrogen is considered a clean-energy carrier,key for a sustainable energy *** methods have been widely used to study the reaction mechanism of the hydrogen evolution reaction(HER),but the calculation results need to be supported by experimental results and direct evidence to confirm the mechanistic *** this review,we discuss the fundamental principles of the in situ spectroscopic strategy and a theoretical model for a mechanistic understanding of the *** addition,we investigate recent studies by in situ Fourier transform infrared(FTIR),Raman spectroscopy,and X-ray absorption spectroscopy(XAS) and cover new findings that occur at the catalyst-electrolyte interface during *** spectroscopic strategies provide practical ways to elucidate catalyst phase,reaction intermediate,catalyst-electrolyte interface,intermediate binding energy,metal valency state,and coordination environment during HER.

关键词： Hydrogen evolution reaction Infrared spectroscopy Raman spectroscopy X-ray absorption spectroscopy Reaction mechanism

Effects of honing treatment on AIP-TiN and TiAlN coated end-mill for high speed machining

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 83-87页

作者： Jae-Young HEO Sung-Hak CHO Tae-Jin JE Kwang-Ho KIM hyung-woo lee Myung-Chang KANG National Core Research Center for Hybrid Materials Solution Pusan National University Nano Machining Laboratory Korea Institute of Machinery and Material (KIMM) 171 Jang-dong Yuseong-Gu Daejeon 305-343 Korea

The objective of this work is to compare the tool performance of TiN and TiAlN coated carbides end-mills deposited by an arc ion plating (AIP) method, using honing treatment to polish the cutting edge surface sleekly. The curve of surface roughness versus honing time showed a rapid improvement initially and thereafter became steady, manifesting a saturation effect. The optimal honing time related to surface roughness was determined to be approximately 20 s. As the surface roughness increased, the critical loads reduced. At an average surface roughness (Ra) of 0.028 μm, the highest critical loads of TiN and TiAlN coating layers were 98 and 114 N, respectively. Tool performances of uncoated and coated tools were conducted under high speed machining (HSM) of AISI D2 cold-worked die steel (62 HRC). Consequently, the TiAlN coated end-mill using honing treatment showed excellent tool life under HSM conditions.

关键词： TiAlN涂层高速加工 TiN 珩磨治疗 AIP 表面粗糙度时间曲线

Extracellular vesicles for neural regeneration after spinal cord injury

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第3期19卷 491-492页

作者： Young-Ju Lim wook-Tae Park Gun woo lee Department of Orthopedic Surgery Yeungnam University Medical CenterYeungnam University College of MedicineDaeguKorea

What is spinal cord injury:Spinal cord injury(SCI)is the damage to the structure of the bundles of cells and nerves that communicate signals from the brain to the body and *** pathology of SCI includes both primary and secondary injuries(Morales et al.,2016).Physical forces such as compression,shearing,contusion,and tearing are major causes of primary injury in *** are two main processes in primary injury:acute and *** acute phase includes traumatic disruption of axons and hemorrhage of the blood vessels around the spinal *** injury to the vessels can lead to increased edema within the neural and cord tissues,susceptibility to infiltration by microglia and astrocytes,excitotoxicity,and ***,disruption of the blood-spinal cord barrier results in the release of inflammatory cytokines from specific cells and vessels.

关键词： acute injuries nerves