Fluoride Anions in Self-Assembled Chiral Cage for the Enantioselective Protonation of Silyl Enol Ethers

Paladhi, Sushovan,Liu, Yidong,Kumar, B. Senthil,Jung, Min-Jung,Park, Sang Yeon,Yan, Hailong,Song, Choong Eui THE AMERICAN CHEMICAL SOCIETY 2017 ORGANIC LETTERS Vol.19 No.12

<P>The potential of Song's chiral oligoethylene glycol's (oligoEGs) as catalysts was explored in the enantioselective protonation of trimethylsilyl enol ethers in combination with alkali metal fluoride (KF and CsF) and in the presence of a proton source Highly enantioselective protonatigns of various silyl enol ethers of alpha-substituted tetralohes were achieved, producing chiral alpha-substituted-Jetralones in full conversion and with up to 99% ee. The established protocol was successfully exiended to the synthesis of biologically relevant chiral alpha-substituted chromanone and thiothromarione derivatives.</P>

Asymmetric Synthesis of Trisubstituted Tetrahydrothiophenes via in Situ Generated Chiral Fluoride-Catalyzed Cascade Sulfa-Michael/Aldol Reaction of 1,4-Dithiane-2,5-diol and α,β-Unsaturated Ketones

Duan, Mengying,Liu, Yidong,Ao, Jun,Xue, Lu,Luo, Shilong,Tan, Yu,Qin, Wenling,Song, Choong Eui,Yan, Hailong American Chemical Society 2017 ORGANIC LETTERS Vol.19 No.9

<P>A chiral, fluoride-catalyzed asymmetric cascade sulfaMichael/aldol condensation reaction of 1,4-dithiane-2,5-diol and a series of alpha,beta-unsaturated ketones is described to access chiral trisubstituted tetrahydrothiophene derivatives. The target products, including the spiro tetrahydrothiophene derivatives bearing a five-, six-, and seven-membered ring, were highly functionalized and showed high ee value. This established protocol realized a highly enantioselective reaction with a catalytic amount of KF and Song's chiral oligoEG via in situ generated chiral fluoride to construct useful heterocyclic skeletons with great complexity.</P>

Enantioselective Synthesis of <i>anti</i>–<i>syn</i>-Trihalides and <i>anti</i>–<i>syn</i>–<i>anti</i>-Tetrahalides via Asymmetric β-Elimination

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>

橋樑修建與士人參與

劉秋根(Liu Qiu-gen),宋燕鵬(Song Yan-peng) 경북대학교 아시아연구소 2009 아시아연구 Vol.- No.5

南宋時에 地方士人들은 적극적으로 대형교량의 건설과 重修활동에 참여하였다. 이들은 직접적으로 資金을 내어 參與하든지 아니면 社會에 影響力을 발휘하는 방식으로 參與하기도 하였다. 南宋時期다수의 士人들은 公益事業의 主體로써 참여하였는데, 政府施政能力의 萎縮이 士人로 하여금 地方의 橋樑건설과 重修활동에 참여할 수 있는 空間을 제공하였다. “富”에 대한 社會的觀念의 비평은 士人들의 橋樑건설과 重修참여에 輿論의 支持를 제공하였고, 佛教徒또한 士人이 橋樑건설과 重修활동에 참여하는 것을 모범으로 간주하였다. 士人이 橋樑修建에 참여함으로써 士人이 地方事務에 평소 관심을 가지고 있음을 보여주었다. 士人은 橋樑修建等의 活動에 참여함으로써 지방 輿論으로부터 好評을 받았을 뿐만 아니라, 社會事務에 대한 某種의 解釋과 支配權도 갖게 되었다. 이것은 새로운 基層社會勢力成長의 標誌라 할 수 있겠다. During the Southern Song Dynasty,Intellectual started to actively participate in large-scale bridge construction activities,and to participate in two ways of capital and social impact to exert their influence. The growing in strength of Intellectual groups provided the main of undertaking public welfare. The shrinking of government's administrative capability provided the space for Intellectual to participate in bridge construction activities. Social concepts of "the rich" were criticized provided public opinion support for Intellectual participating in bridge construction. Buddhists Set an example for Intellectual to participate in the activities of a bridge construction. Intellectual involved in the construction of the bridge reflects the Intellectual 's concern for local affairs. Through participation in activities such as bridge construction Intellectual received favorable public opinion, but also accessed to a certain extent of the interpretation of Social Affairs dominance. This had become a sign of new growth of grass-roots social forces.

Wind direction prediction for yaw control of wind turbines

Song, D.,Yang, J.,Liu, Y.,Su, M.,Liu, A.,Joo, Y. H. Korean Institute of Electrical Engineers 2017 International Journal of Control, Automation, and Vol.15 No.4

<P>Depending on historical signals from wind direction sensors, conventional yaw control methods provide general performance and may be optimized by taking advantage of wind direction prediction. This paper presents two wind direction prediction methods based on time series models. The first method adopts a univariate ARIMA (auto-regressive integrated moving average) model, while the second one uses a hybrid model that integrates the ARIMA model into a Kalman Filter (KF). Since the predicted results are used to optimize yaw control of wind turbines, six prediction models are developed using three types of mean wind directions. Finally, industrial data is used to develop, validate and test the proposed models. From obtained results, it is shown that the hybrid models outperform other ones in terms of three performance indexes and different types of wind direction time series.</P>

Thermal-hydraulic research on rod bundle in the LBE fast reactor with grid spacer

Liu Jie,Song Ping,Zhang Dalin,Wang Shibao,Lin Chao,Liu Yapeng,Zhou Lei,Wang Chenglong,Tian Wenxi,Qiu Suizheng,Su G.H. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.7

The research on the flow and heat transfer characteristics of lead bismuth(LBE) is significant for the thermal-hydraulic calculation, safety analysis and practical application of lead-based fast reactors(LFR). In this paper, a new CFD model is proposed to solve the thermal-hydraulic analysis of LBE. The model includes two parts: turbulent model and turbulent Prandtl, which are the important factors for LBE. In order to find the best model, the experiment data and design of 19-pin hexagonal rod bundle with spacer grid, undertaken at the Karlsruhe Liquid Metal Laboratory (KALLA) are used for CFD calculation. Furthermore, the turbulent model includes SST k u and k ε; the turbulent Prandtl includes Cheng-Tak and constant (Prt ¼1.5,2.0,2.5,3.0). Among them, the combination between SST k u and Cheng-Tak is more suitable for the experiment. But in the low Pe region, the deviation between the experiment data and CFD result is too much. The reason may be the inlet-effect and when Pe is in a low level, the number of molecular thermal diffusion occupies an absolute advantage, and the buoyancy will enhance. In order to test and verify versatility of the model, the NCCL performed by the Nuclear Thermal-hydraulic Laboratory (Nuthel) of Xi'an Jiao tong University is used for CFD to calculate. This paper provides two verification examples for the new universal model

Noncontrast Computed Tomography-Based Radiomics Analysis in Discriminating Early Hematoma Expansion after Spontaneous Intracerebral Hemorrhage

Song Zuhua,Guo Dajing,Tang Zhuoyue,Liu Huan,Li Xin,Luo Sha,Yao Xueying,Song Wenlong,Song Junjie,Zhou Zhiming 대한영상의학회 2021 Korean Journal of Radiology Vol.22 No.3

Objective: To determine whether noncontrast computed tomography (NCCT) models based on multivariable, radiomics features, and machine learning (ML) algorithms could further improve the discrimination of early hematoma expansion (HE) in patients with spontaneous intracerebral hemorrhage (sICH). Materials and Methods: We retrospectively reviewed 261 patients with sICH who underwent initialNCCT within 6 hours of ictus and follow-up CT within 24 hours after initial NCCT, between April 2011 and March 2019. The clinical characteristics, imaging signs and radiomics features extracted from the initial NCCT images were used to construct models to discriminate early HE. A clinical-radiologic model was constructed using a multivariate logistic regression (LR) analysis. Radiomics models, a radiomics-radiologic model, and a combined model were constructed in the training cohort (n = 182) and independently verified in the validation cohort (n = 79). Receiver operating characteristic analysis and the area under the curve (AUC) were used to evaluate the discriminative power. Results: The AUC of the clinical-radiologic model for discriminating early HE was 0.766. The AUCs of the radiomics model for discriminating early HE built using the LR algorithm in the training and validation cohorts were 0.926 and 0.850, respectively. The AUCs of the radiomics-radiologic model in the training and validation cohorts were 0.946 and 0.867, respectively. The AUCs of the combined model in the training and validation cohorts were 0.960 and 0.867, respectively. Conclusion: NCCT models based on multivariable, radiomics features and ML algorithm could improve the discrimination of early HE. The combined model was the best recommended model to identify sICH patients at risk of early HE.

Electrospun porous lithium manganese phosphate-carbon nanofibers as a cathode material for lithium ion batteries

Liu, L.,Song, T.,Han, H.,Park, H.,Xiang, J.,Liu, Z.,Feng, Y.,Paik, U. Royal Society of Chemistry 2015 Journal of Materials Chemistry A Vol.3 No.34

Active Damping Stability Control Method Based on Voltage Compensation for IPMSM Drives with Small DC-Link Capacitor

Song Jian,Song Wen-Xiang,Liu Zhan-Jun,Ma Shao-Cai 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

Aiming at the unstable phenomena such as high DC-link voltage ripple that occur in the interior permanent magnet synchronous motor drive system of the small DC-link capacitor when the rotor speed is high or the load power is large, this paper proposes an active damping control method based on voltage compensation. The method starts from the mathematical model of the driving system, based on the characteristic equation of the driving system, and according to the Rouse stability criterion, the driving system is stabilized by applying a virtual resistance to change the coefficient of the characteristic equation. The proposed method only needs a bandpass filter to extract the DC-link voltage ripple, which is then compensated to the motor stator voltage axis by the damping coefficient. In order to obtain high damping performance, considering the time constant and the delay of the control loop, the theoretical design basis for a reasonable value of the damping coefficient is given, and the influence of the proposed method on the performance of the drive system is evaluated. Simulation and experimental results verify the effectiveness of the proposed method.

Geochemical and S isotopic studies of pollutant evolution in groundwater after acid in situ leaching in a uranium mine area in Xinjiang

Liu Zhenzhong,Tan Kaixuan,Li Chunguang,Li Yongmei,Zhang Chong,Song Jing,Liu Longcheng 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.4

Laboratory experiments and point monitoring of reservoir sediments have proven that stable sulfate reduction (SSR) can lower the concentrations of toxic metals and sulfate in acidic groundwater for a long time. Here, we hypothesize that SSR occurred during in situ leaching after uranium mining, which can impact the fate of acid groundwater in an entire region. To test this, we applied a sulfur isotope fractionation method to analyze the mechanism for natural attenuation of contaminated groundwater produced by acid in situ leaching of uranium (Xinjiang, China). The results showed that δ34S increased over time after the cessation of uranium mining, and natural attenuation caused considerable, area-scale immobilization of sulfur corresponding to retention levels of 5.3%–48.3% while simultaneously decreasing the concentration of uranium. Isotopic evidence for SSR in the area, together with evidence for changes of pollutant concentrations, suggest that area-scale SSR is most likely also important at other acid mining sites for uranium, where retention of acid groundwater may be strengthened through natural attenuation. To recapitulate, the sulfur isotope fractionation method constitutes a relatively accurate tool for quantification of spatiotemporal trends for groundwater during migration and transformation resulting from acid in situ leaching of uranium in northern China.