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307. The size and diffusion effect of gold on silicon nanowire sidewall faceting.

Author

Seo, Deok-Won, Kim, Gil-Sung, Lee, Chan-Yang, Lee, Seung-Yong, Hyung, Jung-Hwan, Choi, Chel-Jong, and Lee, Sang-Kwon

Subjects
CRYSTALS, NANOWIRES, GOLD, THIN film research, THERMAL conductivity
Abstract

Single crystalline silicon nanowires (SiNWs) were grown using a gold (Au)-catalyzed vapor-liquid-solid (VLS) approach. In this study, we examine the influence of the size of Au catalyst droplets on the size of SiNWs and discuss the effect of Au diffusion and surface passivation on SiNW sidewall faceting and roughening in the VLS process. To simultaneously cover a variety of sizes of SiNWs on the same substrate, 2-nm-thick Au film was used on Si (111) substrate as a catalyst, since it is known that Au thin film-based seed offers relatively less control of the NW size, due to the randomness of the film breakup at reaction temperature. We then found that the grown SiNWs have two main types of surface morphologies on the sidewall of the nanowires (NWs). One type had a small and coarse surface morphology with no Au-Si droplets at the top of the NWs. The other type had a long and smooth surface and still had Au-Si droplets at the end. The fact that resulting SiNWs have two main different surface morphologies can be explained by three reasons: the size difference of Au-Si droplets, Au diffusion to the surface of the SiNWs, and surface passivation on the SiNW surface. Furthermore, we proposed a combined VLS and vapor-solid (VS) growth model to describe the creation of the facets and roughening of the sidewall of the NWs. Our results point toward the exciting possibility that the proposed well-controlled and coarse-surfaced SiNWs could be promising thermoelectric materials with low thermal conductivity, since the thermal conductivity is greatly reduced at the rough surface due to the enhancement of phonon scattering. [ABSTRACT FROM AUTHOR]

Published
2012
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309. Deliberately Designed Atomic-Level Silver-Containing Interface Results in Improved Rate Capability and Utilization of Silver Hollandite for Lithium-Ion Storage

Author

Smith, Paul F., primary, Brady, Alexander B., additional, Lee, Seung-Yong, additional, Bruck, Andrea M., additional, Dooryhee, Eric, additional, Wu, Lijun, additional, Zhu, Yimei, additional, Takeuchi, Kenneth J., additional, Takeuchi, Esther S., additional, and Marschilok, Amy C., additional

Published
2017
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313. Anti-Inflammatory and Immune-Regulatory Effects of Subcutaneous Perillae fructus Extract Injections on OVA-Induced Asthma in Mice

Author

Hyun Lee, Lee Seung Yong, Yun-Kyoung Yim, Jung-Eun Kim, Kwoneui Hong, Kwang Suk Park, Seung-Kyoung Ko, and Young Il Kim

Subjects
OVA-induced asthma, medicine.drug_class, Immunoglobulin E, Anti-inflammatory, Immune system, Acupuncture, Medicine, Original Articles - Basic Science, Interleukin 5, Asthma, Lung, biology, business.industry, lcsh:Other systems of medicine, respiratory system, medicine.disease, lcsh:RZ201-999, herbal acupuncture, respiratory tract diseases, perillae fructus, medicine.anatomical_structure, Complementary and alternative medicine, Acupuncture point, ST36, Immunology, biology.protein, business
Abstract

Perillae fructus(perilla seed) is a traditional medicinal herb used to treat bronchial asthma in Oriental medical clinics. ST36 is one of the most widely used acupuncture points, particularly for immune system regulation. Injection of an herbal extract into an acupuncture point (herbal acupuncture) is a therapeutic technique combining both acupuncture and herbal treatment.Perillae fructusextract was injected subcutaneously (Perillae fructusherbal acupuncture; PF-HA) at acupoint ST36 of OVA-induced asthmatic mice. The lung weight, bronchoalveolar fluid (BALF) cell count, the number of CCR3+, CD11b+, CD4+ and CD3e+/CD69+ cells in the lung, and the level of IgE, IL-4, IL-5 and IL-13 in BALF and serum were then measured. RT-PCR was used to measure the mRNA expression of IL-4, IL-5, IL-13 and TNF-α in the lung. Lung sections were analyzed histologically. PF-HA significantly reduced lung weight, the number of inflammatory cells in the lung and BALF, the levels of IgE and Th2 cytokines in BALF and serum, mRNA expression of Th2 cytokines in the lung, and pathological changes in lung tissue. Our results suggest that PF-HA may have an anti-inflammatory and immune-regulatory effect on bronchial allergic asthma by restoring the Th1/Th2 imbalance in the immune system and suppressing eosinophilic inflammation in airways.

Published
2010

328. Cu Diffusion‐Driven Dynamic Modulation of the Electrical Properties of Amorphous Oxide Semiconductors

Author

Yeon, Han‐Wool, primary, Jo, Janghyun, additional, Song, Hochul, additional, Kang, Youngho, additional, Na, Sekwon, additional, Yoo, Hyobin, additional, Lee, Seung‐Yong, additional, Cho, Haelim, additional, Kang, Ho‐Young, additional, Jung, Jung‐Kyu, additional, Han, Seungwu, additional, Kim, Miyoung, additional, and Joo, Young‐Chang, additional

Published
2017
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346. Enhanced photoluminescence due to Bi 3+ → Eu 3+ energy transfer and re-precipitation of RE doped homogeneous sized Y 2 O 3 nanophosphors

Author

Jadhav, Abhijit P., primary, Thi Dinh, Thuy Duong, additional, Khan, Sovann, additional, Lee, Seung Yong, additional, Park, Jong-Ku, additional, Park, Sung Wook, additional, Oh, Ju Hyun, additional, Moon, Byung Kee, additional, Jang, Kiwan, additional, Yi, Soung Soo, additional, Kim, Jung Hwan, additional, Cho, So-Hye, additional, and Jeong, Jung Hyun, additional

Published
2016
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348. The Role of Zr Doping in Stabilizing Li[Ni0.6Co0.2Mn0.2]O2 as a Cathode Material for Lithium‐Ion Batteries.

Author

Choi, Jonghyun, Lee, Seung‐Yong, Yoon, Sangmoon, Kim, Kyeong‐Ho, Kim, Miyoung, and Hong, Seong‐Hyeon

Subjects
LITHIUM-ion batteries, CATHODES, SCANNING transmission electron microscopy, DIFFUSION kinetics, CHEMICAL stability, DENSITY functional theory, ENERGY density
Abstract

Ni‐rich layered LiNi1−x−yCoxMnyO2 systems are the most promising cathode materials for high energy density Li‐ion batteries (LIBs). However, Ni‐rich cathode materials inevitably suffer from rapid capacity fading and poor rate capability owing to structural instability and unstable surface side reactions. Zr doping has proven to be an effective method to enhance the cycle and rate performances by stabilizing the structure and increasing the Li+ diffusion rate. Herein, effects of Zr‐doping on the structural stability and Li+ diffusion kinetics are thoroughly investigated in LiNi0.6Co0.2Mn0.2O2 (LNCM) cathode material using atomic‐resolution scanning transmission electron microscopy imaging, XRD Rietveld refinement, and density functional theory calculations. Zr doping mitigates the degree of cation mixing, decreases the structural transformation, and facilitates Li+ diffusion resulting in improved cyclic performance and rate capability. Based on the obtained results, an atomistic model is proposed to explain the effects of Zr doping on the structural stability and Li+ diffusion kinetics in LNCM cathode materials. [ABSTRACT FROM AUTHOR]

Published
2019
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349. Controlled Dehydrochlorination of Poly(vinyl chloride) for Fabrication of Membranes with Polyacetylene-Like Structure: XPS Analysis and Ion Exchange Membrane Discussion.

Author

Park, Eun Ji, Lee, Seung Yong, Canlier, Ali, and Hwang, Taek Sung

Abstract

Poly(vinyl chloride) (PVC) can be dehydrochlorinated by strong bases, e.g. tert-butoxide and hydroxide, to attain polyacetylene-like highly conjugated polymer chains. Dehydrochlorinated PVC (DHPVC) can be further functionalized by additional reactions to obtain ion exchange membranes, battery membranes, semiconductors, etc. However DHPVC resin is not available for membrane casting because of its low solubility. Therefore dehydrochlorination was performed directly on PVC membranes in this research. The extent of dehydrochlorination and the length of conjugation were controlled by adjusting conditions such as base/PVC ratio and solvent type. X-ray photoelectron spectrometry and elemental analysis were used to detect Cl, C, O, and H contents of the products. A calculation method that uses parameters of atomic approximations, was proposed to mathematically express trends of "degrees of dechlorination, dehydrochlorination, unsaturation, and substitution" with respect to the amount of base used. Up to 64.5% unsaturation and 96.6% dechlorination of PVC membranes were achieved. In addition, theoretical ion exchange capacity (IECtheo) was defined with a suggestion that charged functional groups can be attached to the polymer backbone by double bonds, allowing ion exchange membranes to be manufactured. By tailoring the degree of unsaturation in dehydrochlorinated species, theoretically up to 18 meq/g of IEC would be reached if all double bonds would be functionalized. Scanning electron microscopy analysis showed that tert-butoxide products had a porous structure. FTIR and UV-Visible spectroscopy results verified the formation of long polyene sequences. Dehydrochlorination may be a legitimate method for recycling PVC waste into functional membrane materials. [ABSTRACT FROM AUTHOR]

Published
2019
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350. Shapes of ZnO Nanostructures Grown in the Aqueous Solutions

Author

Park Jong-Ku, Park Hoon, Jang Yeon-Ik, Ahn Jae-Pyoung, and Lee Seung-Yong

Subjects
Materials science, Nanostructure, Aqueous solution, Chemical engineering, Hexagonal crystal system, Zinc compounds, Nanorod, Nanotechnology, Chemical reaction, Ambient pressure
Abstract

ZnO nanostructures with various shapes were synthesized under ambient pressure condition by a wet chemical reaction method. Nanorods of ZnO with hexagonal cross-section and their aggregates with radiate shape were synthesized. Precursor concentration affected considerably the shape evolution of ZnO nanorods. Low precursor concentration was proved to be more preferable to the growth of ZnO nanorods, which is attributed to the intrinsic characteristics of chemical reaction in the synthesis of ZnO from zinc compounds.

Published
2005

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