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- 저자 : Li Chengfeng (검색결과 6 건)
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Li Chengfeng,Lyu Qishen,Li Zheng,Yang Shuliang,Sun Yong,Tang Xing,Zeng Xianhai,Lin Lu 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.9
The hydrogenation of biomass-based furan compounds is an important step for the catalytic valorization of biobased chemicals. In this work, Ru-based catalysts supported on different supports, such as HY, MgO and Amberlyst-15, were prepared and estimated for the hydrogenation of dimethyl 2,5-furandicarboxylate (FDMC). Among them, Ru/HY provided a desirable yield of 99.4% for tetrahydrofuran-2,5-dicarboxylic acid dimethyl ester (THFDMC) under 90 °C and 3 MPa H2. Based on catalyst characterization, Ru/HY could offer more surface Ru0 species and carbon radical intermediates than other catalysts, which could largely favor the activation of hydrogen and then promote the hydrogenation of FDMC over Ru/HY.
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( Li Zhang ),( Xinya Xu ),( Shujun Chen ),( Yuli Kang ),( Xiuxiu Wang ),( Chengfeng Zhang ),( Leihong Xiang ) 대한피부과학회 2019 Annals of Dermatology Vol.31 No.4
Background: Vitiligo is a common acquired pigmentary disease caused by destruction of epidermal melanocytes in underlying autoimmune response. Few studies have been focused on the role of chemokines in non-segmental vitiligo (NSV) concomitant with autoimmune thyroid disease (AITD) and alopecia areata (AA). Objective: The aim of this study was to determine the best serum biomarker for predictive role in the progression of vitiligo and to evaluate the influence of AA and/or AITD on vitiligo by using the biomarker. Methods: This prospective cohort study recruited 45 NSV patients: 14 without either AITD or AA, 12 with AITD, 11 with AA, and 8 with both AITD and AA. Serum levels of CXCL1, CXCL8, CXCL9, CXCL10, CXCL12, CXCL13, and CXCL16 were analyzed by ELISA. CXCR3 mRNA expression was detected on PBMCs by RT-PCR. Improvement was evaluated using repigmentation scales. Results: Serum CXCL10 levels, along with the expression of CXCR3 mRNA were higher in NSV patients with AITD or AA alone than in those without AITD or AA. Moreover, serum CXCL10 levels, along with the expression of CXCR3 mRNA were higher in NSV patients with both AITD and AA than in those with AITD or AA alone. Poorer repigmentation was observed in NSV patients with both AA and AITD than in those with AA or AITD alone. Conclusion: CXCL10 could be a biomarker to predict the progression of NSV. Dermatologists should pay much attention to those NSV patients concomitant with AITD and/or AA, for comorbidity might lead to more active autoimmune reaction. (Ann Dermatol 31(4) 393∼402, 2019)
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A FAST NUMERICAL METHOD FOR SOLVING A REGULARIZED PROBLEM ASSOCIATED WITH OBSTACLE PROBLEMS
Yuan, Daming,Li, Xi,Lei, Chengfeng Korean Mathematical Society 2012 대한수학회지 Vol.49 No.5
Kirsi Majava and Xue-Cheng Tai [12] proposed a modified level set method for solving a free boundary problem associated with unilateral obstacle problems. The proximal bundle method and gradient method were applied to solve the nonsmooth minimization problems and the regularized problem, respectively. In this paper, we extend this approach to solve the bilateral obstacle problems and employ Rung-Kutta method to solve the initial value problem derived from the regularized problem. Numerical experiments are presented to verify the efficiency of the methods.
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A fast numerical method for solving a regularized problem associated with obstacle problems
DaMing Yuan,Xi Li,ChengFeng Lei 대한수학회 2012 대한수학회지 Vol.49 No.5
Kirsi Majava and Xue-Cheng Tai [12] proposed a modified level set method for solving a free boundary problem associated with unilateral obstacle problems. The proximal bundle method and gradient method were applied to solve the nonsmooth minimization problems and the regularized problem, respectively. In this paper, we extend this approach to solve the bilateral obstacle problems and employ Rung-Kutta method to solve the initial value problem derived from the regularized problem. Numerical experiments are presented to verify the efficiency of the methods.
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Bai, Jiahai,Piao, Jiasi,Gao, Jie,He, Jing,Du, Qingyang,Li, Chengfeng The Korean Ceramic Society 2019 한국세라믹학회지 Vol.56 No.4
Porous alumina ceramics with addition of 0, 5, 10, 15, and 20 wt% Al(H<sub>2</sub>PO<sub>4</sub>)<sub>3</sub> were sintered at 1300, 1350, and 1400℃. The effects of the Al(H<sub>2</sub>PO<sub>4</sub>)<sub>3</sub> addition on crystal phases, water absorption, open porosity, pore size distribution, microstructures, and flexural strength were studied extensively. The experimental results revealed that only characteristic peaks of corundum were indexed in the XRD patterns of the as-prepared porous ceramics. The water absorption and open porosity of the porous Al<sub>2</sub>O<sub>3</sub> ceramics increased remarkably with an increase in Al(H<sub>2</sub>PO<sub>4</sub>)<sub>3</sub> addition. The flexural strength first increased to a maximum value when 5 wt% Al(H<sub>2</sub>PO<sub>4</sub>)<sub>3</sub> was added and then decreased as additional Al(H<sub>2</sub>PO<sub>4</sub>)<sub>3</sub> was further added. SEM images showed that the average Al<sub>2</sub>O<sub>3</sub> grain size in the porous ceramics changed in an opposite way as the flexural strength. The porous Al<sub>2</sub>O<sub>3</sub> ceramics with 10 wt% Al(H<sub>2</sub>PO<sub>4</sub>)<sub>3</sub> addition exhibited comparable flexural strength to the ceramics without Al(H<sub>2</sub>PO<sub>4</sub>)<sub>3</sub> addition, although the latter had much higher porosity.
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Cheng Feng,Li Jianbo,Ding Zhixin,Lin Gao 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.3
The dynamic structural responses are sensitive to the time-frequency content of seismic waves, and seismic input motions in time-history analysis are usually required to be compatible with design response spectra according to nuclear codes. In order to generate spectra-compatible input motions while maintaining the intrinsic non-stationarity of seismic waves, an improved time-domain approach is proposed in this paper. To maintain the nonstationary characteristics of the given seismic waves, a new time-frequency envelope function is constructed using the Hilbert amplitude spectrum. Based on the intrinsic mode functions (IMFs) obtained from given seismic waves through variational mode decomposition, a new corrective time history is constructed to locally modify the given seismic waves. The proposed corrective time history and time-frequency envelope function are unique for each earthquake records as they are extracted from the given seismic waves. In addition, a dimension reduction iterative technique is presented herein to simultaneously superimpose corrective time histories of all the damping ratios at a specific frequency in the time domain according to optimal weights, which are found by the genetic algorithm (GA). Examples are presented to show the capability of the proposed approach in generating spectra-compatible time histories, especially in maintaining the nonstationary characteristics of seismic records. And numerical results reveal that the modified time histories generated by the proposed method can obtain similar dynamic behaviors of AP1000 nuclear power plant with the natural seismic records. Thus, the proposed method can be efficiently used in the design practices
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