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Meng-Meng Lv,Ming-Hui Tan,Li-Wen Lu,Rong-Hua Zhang,Zhi-Yong Guo,Cheng-Xiong Liu,Jin Yang,Kun Zou,Peter Proksch 한국생약학회 2018 Natural Product Sciences Vol.24 No.3
Two new polyketides, chinoketides A and B (1 - 2) with a known compound xylarphthalide A (3), were isolated from the solid medium of the endophytes from the leaves of the relic plant Distylium chinense with the "black-box" co-culture method, and the structures of two new compounds were elucidated by NMR, MS and CD spectra. And the absolute configurations of chinoketides A (1) and B (2) were determined as 2R,3R,8S and 5R,6S by calculating their ECD spectra to compare with the experimental CD spectra. Finally, the antimicrobial activities were evaluated to Erwinia carotovora sub sp. Carotovora (Jones) Bersey et al, and the results showed that compounds 1 - 3 displayed the antimicrobial activities with MIC value at 20.5, 30.4 and 10.2 mg/mL.
Hybrid model- and signal-based chatter detection in the milling process
Meng-Kun Liu,Minh-Quang Tran,Chunhui Chung,Yi-Wen Qui 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1
Chatter causes machining instability and reduces productivity in the metal cutting process. It has negative effects on the surface finish, dimensional accuracy, tool life and machine life. Chatter identification is therefore necessary to control, prevent, or eliminate chatter and to determine the stable machining condition. Previous studies of chatter detection used either model-based or signal-based methods, and each of them has its drawback. Model-based methods use cutting dynamics to develop stability lobe diagram to predict the occurrence of chatter, but the off-line stability estimation couldn’t detect chatter in real time. Signal-based methods apply mostly Fourier analysis to the cutting or vibration signals to identify chatter, but they are heuristic methods and do not consider the cutting dynamics. In this study, the modelbased and signal-based chatter detection methods were thoroughly investigated. As a result, a hybrid model- and signal-based chatter detection method was proposed. By analyzing the residual between the force measurement and the output of the cutting force model, milling chatter could be detected and identified efficiently during the milling process.
Kun Dou,Lingtao Meng,Qing Liu,Bo Liu,Yunhua Huang 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.3
During continuous casting process of low carbon micro-alloyed steel containing vanadium, the evolution of strand surface microstructure and the precipitation of secondary phase particles (mainly V(C, N)) are significantly influenced by cooling rate. In this paper, influence of cooling rate on the precipitation behavior of proeutectoid α-ferrite at the γ-austenite grain boundary and in the steel matrix are in situ observed and analyzed through high temperature confocal laser scanning microscopy. The relationship between cooling rate and precipitation of V(C, N) from steel continuous casting bloom surface microstructure is further studied by scanning electron microscopy and electron dispersive spectrometer. Relative results have shown the effect of V(C, N) precipitation on α-ferrite phase transformation is mainly revealed in two aspects: (i) Precipitated V(C, N) particles act as inoculant particles to promote proeutectoid ferrite nucleation. (ii) Local carbon concentration along the γ-austenite grain boundaries is decreased with the precipitation of V(C, N), which in turn promotes α-ferrite precipitation.
Effects of Lactobacillus plantarum SCS2 on blood glucose level in hyperglycemia mice model
Xiao Meng,Yu Qian,Li-Shi Jiang,Jin-Mei Kang,Yan Chen,Juan Wang,Shu-Kun Liu,Zhen-Ming Che,Xin Zhao 한국응용생명화학회 2016 Applied Biological Chemistry (Appl Biol Chem) Vol.59 No.1
In this study, the hyperglycemia mice model was established with 1-week high sugar and fat diet plus with 70 mg/kg body weight of streptozotocin injection for 3 days. Sixty male Kunming mice of 3 weeks old in a specific-pathogen-free grade were divided into six groups randomly, which includes normal group (NG), prevention group (PG), treatment group for low dose (TGL), middle dose (TGM), high dose (TGH), and model group (MG). NG and MG mice were fed with sterile physiological saline (10 mL/kg body weight). PG mice were fed with the concentration of 6.0 × 109 CFU/mL L. plantarum SCS2 suspensions from the second to third week. TGL, TGM, and TGH mice were fed with the concentration of 2.0 × 109, 4.0 × 109, and 6.0 × 109 CFU/mL L. plantarum SCS2 suspensions (10 mL/kg body weight), respectively from fourth to tenth week. The results showed that the fasting and postprandial 2 h blood glucose levels of TGH mice were reduced by L. plantarum SCS2 significantly (p < 0.05) as compared with MG. The body weight of TGH mice came to normal level at tenth week. Content of K+ in plasma of TGH mice was increased and contents of Na+ and Cl− in the plasma of TGH mice were decreased as compared with MG. Meanwhile, content of glycogen in TGH mice was reduced. However, the effect of L. plantarum SCS2 on the prevention of hyperglycemia in PG mice was not significant as compared with NG mice during the experiment. These results suggested that L. plantarum SCS2 showed a hypoglycemic effect on hyperglycemic mice model.
Bearing capacity of H-section beam wrapped with ceramsite concrete
Xuechun Liu,Kun Meng,Ailin Zhang,Tao Zhu,Cheng Yu 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.5
In this study, an H-section steel beam with circular holes in a web wrapped with ceramsite concrete (SBWCC) was studied. Static load-bearing capacity tests and finite element analysis were performed on two groups of specimens with different sections. The H-section steel and wrapped ceramsite concrete were well bonded. The load-bearing capacity of the SBWCC was 10% larger than that of the pure H-section steel beam without holes in the web, except for its dead weight. The stiffness of the SBWCC was slightly larger than that of the pure H-section steel beam without holes. The wrapped ceramsite concrete avoided the elastic local instability of the steel beam flange and web. Based on the finite element model verified by experiments, the influences of hole diameter, hole spacing, and U-shaped stirrups on the flexural capacity of the specimens were analyzed. The formulas for the load-bearing capacities and short-term stiffness of the SBWCC were proposed and verified by tests and finite element analysis.
Ruyan Liu,Yin Chi,Shengyun Chen,Qinghui Jiang,Xiaoyu Meng,Kun Wu,Shengjia Li 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.4
Pervious concrete has been widely used in parking lots and other lightweight streets. Performances of pervious concrete are strongly dependent on its pore structure characteristics. This paper investigates the relationship among porosity, permeability, compressive strength, durability and the pore structure characteristics of pervious concrete. The influences of basalt fiber and fine aggregate on the pervious concrete are also discussed. Pervious concrete specimens with different pore structures were prepared by combining basalt aggregate with size of 5-10 mm and 10-15 mm at different proportion. The pore structure characteristics such as area porosity, pore sizes, and pore distribution of pervious concrete were obtained and analyzed using image analysis method. Experimental results showed that the pore structure characteristics of pervious concrete have effects on its mechanical and durability behaviors. Homogeneous pore distribution and large distances between pores increase the compressive strength and improve freeze-thaw durability of pervious concrete. Due to the difference in the internal pore structure of pervious concretes, specimens with similar volumetric porosities had different permeability coefficients. A series of numerical models were regenerated through a MATLAB code using pore structural parameters derived from the image analysis method, then the numerical models were fed to ANSYS for meshing and further simulation. The comparison of the simulation and experimental results showed close accuracy, which verified the applied simulation analysis method based on image analysis technology.
Jie Liu,Shuang Li,Fan Yang,Tianyu Li,Rui Li,Yousuf Waheed,Chen Meng,Shulin Li,Kun Liu,Yanshan Tong,Haisheng Xu,Chuankuo Tian,Xinglei Zhou 대한내과학회 2024 The Korean Journal of Internal Medicine Vol.39 No.3
Background/Aims: Roxadustat, an oral medication for treating renal anemia, is a hypoxia-inducible factor prolyl hydroxylase inhibitor used for regulating iron metabolism and promoting erythropoiesis. To investigate the efficacy and safety of roxadustat in patients undergoing peritoneal dialysis (PD) with erythropoietin hyporesponsiveness. Methods: Single-center, retrospective study, 81 PD patients (with erythropoietin hyporesponsiveness) were divided into the roxadustat group (n = 61) and erythropoiesis-stimulating agents (ESAs) group (n = 20). Hemoglobin (Hb), total cholesterol, intact parathyroid hormone (iPTH), brain natriuretic peptide (BNP), related indicators of cardiac function and high-sensitivity C-reactive protein (hs-CRP) were collected. Additionally, adverse events were also recorded. The follow-up period was 16 weeks. Results: The two groups exhibited similar baseline demographic and clinical characteristics. At baseline, the roxadustat group had a mean Hb level of 89.8 ± 18.9 g/L, while the ESAs group had a mean Hb level of 95.2 ± 16.0 g/L. By week 16, the Hb levels had increased to 118 ± 19.8 g/L (p < 0.05) in the roxadustat group and 101 ± 19.3 g/L (p > 0.05) in the ESAs group. The efficacy of roxadustat in improving anemia was not influenced by baseline levels of hs-CRP and iPTH. Cholesterol was decreased in the roxadustat group without statin use. An increase in left ventricular ejection fraction and stabilization of BNP were observed in the roxadustat group. Conclusions: For PD patients with erythropoietin hyporesponsiveness, roxadustat can significantly improve renal anemia. The efficacy of roxadustat in improving renal anemia was not affected by baseline levels of hs-CRP0 and iPTH.
Mechanical Study on the Effect of Granular Friction in a Granular System under Biaxial Compression
Fan-Jing Meng,Kun Liu 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.10
The in uence of granular friction on the mechanical behaviors of a granular system is a typical research realm that is still not yet fully understood because of the complexities and the discreteness of the granular system. In this study, a two-dimensional model of a granular system with biaxial compression is established by using the discrete element method (DEM). Using this DEM model, we investigate the macroscopic mechanical behaviors, the microscopic mechanical responses and the force chain distributions of a granular system in uenced by granular friction. Simulation results show that the granular friction has a prominent in uence on the stress-strain response, dilatancy behaviors, and peak strength of the granular system. The microscopic mechanical behaviors of the coordination number, the sliding fraction, and the mean mobilized friction coecient of the granular system are also shown to be markedly in uenced by the granular friction. The force chains in the granular system form an inhomogeneous distribution, and their intensities increase with increasing granular friction.