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On the role of surface diffusion in determining the shape or morphology of noble-metal nanocrystals
Xia, Xiaohu,Xie, Shuifen,Liu, Maochang,Peng, Hsin-Chieh,Lu, Ning,Wang, Jinguo,Kim, Moon J.,Xia, Younan National Academy of Sciences 2013 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.110 No.17
<P>Controlling the shape or morphology of metal nanocrystals is central to the realization of their many applications in catalysis, plasmonics, and electronics. In one of the approaches, the metal nanocrystals are grown from seeds of certain crystallinity through the addition of atomic species. In this case, manipulating the rates at which the atomic species are added onto different crystallographic planes of a seed has been actively explored to control the growth pattern of a seed and thereby the shape or morphology taken by the final product. Upon deposition, however, the adsorbed atoms (adatoms) may not stay at the same sites where the depositions occur. Instead, they can migrate to other sites on the seed owing to the involvement of surface diffusion, and this could lead to unexpected deviations from a desired growth pathway. Herein, we demonstrated that the growth pathway of a seed is indeed determined by the ratio between the rates for atom deposition and surface diffusion. Our result suggests that surface diffusion needs to be taken into account when controlling the shape or morphology of metal nanocrystals.</P>
Kuo-Feng Hua,A-Ching Chao,Ting-Yu Lin,Wan-Tze Chen,Yu-Chieh Lee,Wan-Han Hsu,Sheau-Long Lee,Hsin-Min Wang,Ding-I. Yang,Tz-Chuen Ju 고려인삼학회 2022 Journal of Ginseng Research Vol.46 No.4
Background: Huntington's disease (HD) is a neurodegenerative disorder caused by the expansion oftrinucleotide CAG repeat in the Huntingtin (Htt) gene. The major pathogenic pathways underlying HDinvolve the impairment of cellular energy homeostasis and DNA damage in the brain. The protein kinaseataxia-telangiectasia mutated (ATM) is an important regulator of the DNA damage response. ATM isinvolved in the phosphorylation of AMP-activated protein kinase (AMPK), suggesting that AMPK plays acritical role in response to DNA damage. Herein, we demonstrated that expression of polyQ-expandedmutant Htt (mHtt) enhanced the phosphorylation of ATM. Ginsenoside is the main and most effectivecomponent of Panax ginseng. However, the protective effect of a ginsenoside (compound K, CK) in HDremains unclear and warrants further investigation. Methods: This study used the R6/2 transgenic mouse model of HD and performed behavioral tests,survival rate, histological analyses, and immunoblot assays. Results: The systematic administration of CK into R6/2 mice suppressed the activation of ATM/AMPK andreduced neuronal toxicity and mHTT aggregation. Most importantly, CK increased neuronal density andlifespan and improved motor dysfunction in R6/2 mice. Conversely, CK enhanced the expression of Bcl2protected striatal cells from the toxicity induced by the overactivation of mHtt and AMPK. Conclusions: Thus, the oral administration of CK reduced the disease progression and markedlyenhanced lifespan in the transgenic mouse model (R6/2) of HD.
Choi, Sang-Il,Xie, Shuifen,Shao, Minhua,Odell, Jonathan H.,Lu, Ning,Peng, Hsin-Chieh,Protsailo, Lesia,Guerrero, Sandra,Park, Jinho,Xia, Xiaohu,Wang, Jinguo,Kim, Moon J.,Xia, Younan American Chemical Society 2013 Nano letters Vol.13 No.7
<P>Nanoscale Pt–Ni bimetallic octahedra with controlled sizes have been actively explored in recent years owning to their outstanding activity for the oxygen reduction reaction (ORR). Here we report the synthesis of uniform 9 nm Pt–Ni octahedra with the use of oleylamine and oleic acid as surfactants and W(CO)<SUB>6</SUB> as a source of CO that can promote the formation of {111} facets in the presence of Ni. Through the introduction of benzyl ether as a solvent, the coverage of both surfactants on the surface of resultant Pt–Ni octahedra was significantly reduced while the octahedral shape was still attained. By further removing the surfactants through acetic acid treatment, we observed a specific activity 51-fold higher than that of the state-of-the-art Pt/C catalyst for the ORR at 0.93 V, together with a record high mass activity of 3.3 A mg<SUB>Pt</SUB><SUP>–1</SUP> at 0.9 V (the highest mass activity reported in the literature was 1.45 A mg<SUB>Pt</SUB><SUP>–1</SUP>). Our analysis suggests that this great enhancement of ORR activity could be attributed to the presence of a clean, well-preserved (111) surface for the Pt–Ni octahedra.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2013/nalefd.2013.13.issue-7/nl401881z/production/images/medium/nl-2013-01881z_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl401881z'>ACS Electronic Supporting Info</A></P>