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RISS 인기검색어
- 검색키워드
- 저자 : Dongmei Song (검색결과 4 건)
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Tan, Yu,Luo, Shilong,Li, Dongmei,Zhang, Nan,Jia, Shiqi,Liu, Yidong,Qin, Wenling,Song, Choong Eui,Yan, Hailong American Chemical Society 2017 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.139 No.18
<P>Structural motifs containing contiguous halide bearing stereocenters are common in natural products as well as bioactive molecules. A few successful examples have been reported in the area of asymmetric vicinal dihalogenation of alkenes for accessing dihalogenated products; in this report, an alternative generation method of contiguous halide-bearing stereocenters alpha,beta,gamma,delta relative to carbonyl group in excellent enantioselectivity is proposed by utilizing a Song's oligoEG catalyst-catalyzed asymmetric beta-elimination. According to this methodology, a wide range of anti-syn-trihalides and anti-syn-anti-tetrahalides with high levels of enantioselectivity were synthesized. The synthetic utility of the contiguous halide-bearing stereocenters was demonstrated by several transformations. The results of high-resolution mass spectrometry indicated that the favorable interaction between catalyst and one of the enantiomers of racemic contiguously multihalogenated ketone contributed to the original enantioselectivity of dehydrohalogenation. A deuterium kinetic isotope effect experiment revealed that this beta-elimination reaction proceeds by the E2 mechanism. This strategy opens a new pathway for the asymmetric synthesis of contiguous halide bearing stereocenters of great complexity.</P>
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Liu, Yidong,Liu, Song,Li, Dongmei,Zhang, Nan,Peng, Lei,Ao, Jun,Song, Choong Eui,Lan, Yu,Yan, Hailong American Chemical Society 2019 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.141 No.2
<P>The development and characterization of enantioselective catalytic kinetic resolution of allylic alcohols through asymmetric isomerization with chiral BINOL derivatives-based alkoxides as bifunctional Brønsted base catalysts were described in the study. A number of chiral BINOL derivatives-based alkoxides were synthesized, and their structure-enantioselectivity correlation study in asymmetric isomerization identified a promising chiral Brønsted base catalyst, which afforded various chiral secondary allylic alcohols (ee up to 99%, <I>S</I> factor up to >200). In the mechanistic study, alkoxide species were identified as active species and the phenol group of BINOL largely affected the high reactivity and enantioselectivity via hydrogen bonding between the chiral Brønsted base catalyst and substrates. The strategy is the first successful synthesis strategy of various chiral secondary allylic alcohols through enantioselective transition-metal-free base-catalyzed isomerization. The applicability of the strategy had been demonstrated by the synthesis of the bioactive natural product (+)-veraguensin.</P> [FIG OMISSION]</BR>
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Xiaoxiao Zhao,Yujie Zhou,Hui Song,Like Guan,Guanbin Zheng,Zhehu Jin,Dongmei Shi,Yuzi Li,Yonghe Guo,Guo-Ping Shi,Xian Wu Cheng 연세대학교의과대학 2011 Yonsei medical journal Vol.52 No.6
Purpose: Several studies have compared the effects of coronary stenting and coronary-artery bypass grafting (CABG) on left main coronary artery (LMCA) disease. However, there are limited data on the long-term outcomes of these two interventions in diabetic patients. Materials and Methods: We evaluated 56 patients with LMCA stenosis who underwent drug-eluting stent (DES) implantation and 116 patients who underwent CABG in a single hospital in China between January 2004 and December 2006. We compared long-term major adverse cardiac events (death; a “serious outcome” composite of death, myocardial infarction, or stroke; and target-vessel revascularization). Results: In-hospital (30-day) mortality was 0% for the DES group and 3.4% for the CABG group (p=0.31). There was no difference between the two groups in terms of risk of death [hazard ratio for stenting group, 0.49; 95% confidence interval (CI), 0.13-1.63; p=0.55] or risk of serious outcome (hazard ratio for DES group, 1.11; 95% CI, 0.39-1.45; p=0.47). The target-vessel revascularization rate was higher in the DES group than in the CABG group (hazard ratio, 3.67; 95% CI, 1.24-11.06; p=0.018). Conclusion: In this cohort of diabetic patients with LMCA stenosis, there was no difference in composite endpoints between patients receiving DESs and those undergoing CABG. However, stenting was associated with higher rates of target-vessel revascularization than CABG. DES implantation in diabetic patients with LMCA disease was found to be at least as safe as CABG.
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Xiaoming Chen,Xide Lai,Qiuqin Gou,Dongmei Song 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.3
The matching between the guide vane (GV) and runner is essential for the stable and efficient operation of hydraulic turbines. To investigate the compatibility between GV and runner, we have conducted the numerical calculations of a moderate low-specific-speed Francis turbine at 25 operating points within the operating range of 130-190 m head and 3-19° GV outflow angle. The energy characteristics, flow field characteristics, and static pressure variation of turbines with different GV profile types have been comparatively analyzed. The results show that moderate low-specific-speed Francis turbines with symmetrical and negative curvature GV demonstrate higher efficiency under medium to high head, 55-100 % rated output operating conditions. Under small opening and medium head conditions, the static pressure in the blade leading edge is smaller, and the low-pressure area is larger for the Francis turbine with positive curvature GV. When the GV opening increases, the relationship between the comparative values of static-pressure and low-pressure areas reverses. The turbine with positive curvature GV is more favorable for increasing static-pressure and narrow low-pressure areas, which can reduce the cavitation damage. Our study provides guidelines to optimize the design of GVs and runner for hydraulic turbines.
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