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Song, Bing,Yi, Sangheon,Jia, Hongjuan,Nahm, Wook-Hyun,Kim, Jin-Cheul,Lim, Jaesoo,Lee, Jin-Young,Sha, Longbin,Mao, Limi,Yang, Zhongyong,Nakanishi, Toshimichi,Hong, Wan,Li, Zhen Elsevier 2018 Journal of Asian earth sciences Vol.151 No.-
<P><B>Abstract</B></P> <P>To understand historical climate change in western Pacific coastal areas, a sediment core (SOJ-2) from the stable sedimentary environment of the Songjiho Lagoon on the east coast of South Korea was obtained for centennial-resolution palynological analysis. The ages of the SOJ-2 core is well controlled by carbon 14 dating with high-resolution accelerator mass spectrometry (AMS), and the results indicated a general warm to cold climate trend from the mid-Holocene to the present, which can be divided into two different stages: a warmer stage between 6842 and 1297 cal yr BP and a colder stage from 1297 cal yr BP to the present, with fluctuations during these stages. The climate was wetter from 6842 to 6227 cal yr BP and 4520 to 1297 cal yr BP and was drier from 6227 to 4520 cal yr BP. The climate changed to cold and dry during the period from 1297–425 cal yr BP. The impact of human activity on the climate began at approximately 1297 cal yr BP and became pronounced starting in 425 cal yr BP. The general cooling trend may represent a response to decreasing solar insolation; however, the relative dryness or wetness of the climate may have been co-determined by westerlies and the East Asian summer monsoon (EASM). The climate had a teleconnection with the North Atlantic region, resulting from changes in solar activity. Nevertheless, EI Niño–Southern Oscillation (ENSO) activity played an important role in impacting the EASM changes in western Pacific coastal areas.</P> <P><B>Highlights</B></P> <P> <UL> <LI> There is a centennial resolution climate record from 6842 cal yr BP to present. </LI> <LI> The general cooling trend was probably triggered by decreasing solar insolation. </LI> <LI> The precipitation was co-determined by westerlies and the East Asian Summer Monsoon. </LI> <LI> The ENSO activity may be an important factor for East Asian Summer Monsoon change. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Six new dammarane-type triterpene saponins from Panax ginseng flower buds and their cytotoxicity
Li, Ke-Ke,Li, Sha-Sha,Xu, Fei,Gong, Xiao-Jie The Korean Society of Ginseng 2020 Journal of Ginseng Research Vol.44 No.2
Background: Panax ginseng has been used for a variety of medical purposes in eastern countries for more than two thousand years. From the extensive experiences accumulated in its long medication use history and the substantial strong evidence in modern research studies, we know that ginseng has various pharmacological activities, such as antitumor, antidiabetic, antioxidant, and cardiovascular system-protective effects. The active chemical constituents of ginseng, ginsenosides, are rich in structural diversity and exhibit a wide range of biological activities. Methods: Ginsenoside constituents from P. ginseng flower buds were isolated and purified by various chromatographic methods, and their structures were identified by spectroscopic analysis and comparison with the reported data. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H- tetrazolium bromide method was used to test their cytotoxic effects on three human cancer cell lines. Results: Six ginsenosides, namely 6'-malonyl formyl ginsenoside F<sub>1</sub> (1), 3β-acetoxyl ginsenoside F<sub>1</sub> (2), ginsenoside Rh<sub>24</sub> (6), ginsenoside Rh<sub>25</sub> (7), 7β-hydroxyl ginsenoside Rd (8) and ginsenoside Rh<sub>26</sub> (10) were isolated and elucidated as new compounds, together with four known compounds (3-5 and 9). In addition, the cytotoxicity of these isolated compounds was shown as half inhibitory concentration values, a tentative structure-activity relationship was also discussed based on the results of our bioassay. Conclusion: The study of chemical constituents was useful for the quality control of P. ginseng flower buds. The study on antitumor activities showed that new Compound 1 exhibited moderate cytotoxic activities against HL-60, MGC80-3 and Hep-G2 with half inhibitory concentration values of 16.74, 29.51 and 20.48 μM, respectively.
아라미드 종이의 특성에 대한 표면 개질 과정 조건의 영향
Li Zheng Sha,Hui Fang Zhao 한국고분자학회 2013 폴리머 Vol.37 No.2
Surface modification of meta-aramid fibers was performed by phosphoric acid treatment. Surface morphology and element composition of untreated and treated fibers were analyzed by scanning electron microscope (SEM) and Xray photoelectron spectroscopy (XPS). Effects of surface modification on the mechanical strength of aramid papers made from meta-aramid fibers and fibrid were investigated. Surface modification conditions were optimized by response surface analysis (RSA). Results show that phosphoric acid treatment increases the surface roughness and oxygen content of aramid fibers. They improve the interface bonding strength between aramid fibers and fibrid, which improves the tensile strength of aramid papers. The results of response surface analysis indicate that the tensile strength of aramid papers increases by 47.5% and reaches the maximum when meta-aramid fibers are treated with 21.1wt% phosphoric acid solution at 39.3℃ for 36.7 min.
A Real Time Algorithm for Seismic Data Compression
Li, Sha-bai,Liu, Qi-yuan 한국지진연구소 1996 SAFE Vol.2 No.1
A new real time algorithm of seismic data compression, including the segment normalized logical compression and so called "one taken from two samples", is presented for broad band, high dynamic seismic recordings. This algorithm was tested by numerical simulation and observed data. Its results demonstrate that total errors in recovery data are less than 1 % of original data in time domain, 0.5% in frequency domain, when using these two methods together. Its compression ratio is greater than 3.
3-D Deformation Behavior Simulation of Cable Stitch Based on Particle System in Weft Knitted Fabrics
Sha Sha,Lei Luo,Zhongmin Deng,Dapeng Yuan,Bin Li,Xuewei Jiang,Hui Tao,Qufu Wei 한국섬유공학회 2018 Fibers and polymers Vol.19 No.9
The static simulation of weft knitting can be efficiently realized by graphics simulation techniques, but there still remains a challenge for mechanical models. The lack of practical mechanical models significantly limit the realistic deformation behaviors of complex cable stitches, which lead to a great different between the simulation effect and the actual fabric. In order to obtain the deformation behavior and volumetric performance of cable stitch, loop models were built based on an improved particle system in this work. Compared with plain weft knitted, the offset value of bonding points of cable stitches were measured. By analyzing the relationship between the deformation of loops and the displacement of the particles, the deformation behavior of cable stitch was simulated. Velocity-Verlet integration was introduced to simulate cable stitches and the stable results were obtained. The results show that these models and algorithm displayed the accurate deformation behavior of cable stitches, as demonstrated by qualitative comparisons to measure the deformations of actual samples.
Jiang Li,Xia-Bing Li,Sha Sha Ma,Juan Liu,Ben Hao Li,Bao-Lin Li 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.8
A novel chiral ionic liquid containing proline moiety was synthesized. It can be used as a highly efficient and recyclable chiral organocatalyst for Michael addition of cyclohexanone with (E)-β-nitroalkenes in methanol at room temperature. The Michael addition affords the corresponding products in satisfactory yields of isolated products (78–98%) with high diastereoselectivities and excellent enantioselectivities (up to 98% dr and up to 99% ee). The catalyst can be recycled up to five times without any decrease in yields and stereoselectivities.