The beneficial effect of ginsenosides extracted by pulsed electric field against hydrogen peroxide-induced oxidative stress in HEK-293 cells

Di Liu,Ting Zhang,Zhifei Chen,Ying Wang,Shuang Ma,Jiyun Liu,Jingbo Liu 고려인삼학회 2017 Journal of Ginseng Research Vol.41 No.2

Background: Ginsenosides are the main pharmacological components of Panax ginseng root, which are thought to be primarily responsible for the suppressing effect on oxidative stress. Methods: 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and oxygen radical absorption capacity were applied to evaluate the antioxidant activities of the ginsenosides. Human embryonic kidney 293 (HEK-293) cells were incubated with ginsenosides extracted by pulsed electric field (PEF) and solvent cold soak extraction (SCSE) for 24 h and then the injury was induced by 40mM H2O2. The cell viability and surface morphology of HEK-293 cells were studied using MTS assay and scanning electron microscopy, respectively. Dichloro-dihydro-fluorescein diacetate fluorescent probe assay was used to measure the level of intracellular reactive oxygen species. The intracellular antioxidant activities of ginsenosides were evaluated by cellular antioxidant activity assay in HepG2 cells. Results: The PEF extracts displayed the higher 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and stronger oxygen radical absorption capacity (with an oxygen radical absorption capacity value of 14.48 4.04mM TE per mg/mL). The HEK-293 cell model also suggested that the protective effect of PEF extracts was dose-dependently greater than SCSE extracts. Dichloro-dihydro-fluorescein diacetate assay further proved that PEF extracts are more active (8% higher than SCSE extracts) in reducing intracellular reactive oxygen species accumulation. In addition, scanning electron microscopy images showed that the HEK-293 cells, which were treated with PEF extracts, maintained more intact surface morphology. Cellular antioxidant activity values indicated that ginsenosides extracted by PEF had stronger cellular antioxidant activity than SCSE ginsenosides extracts. Conclusion: The present study demonstrated the antioxidative effect of ginsenosides extracted by PEF in vitro. Furthermore, rather than SCSE, PEF may be more useful as an alternative extraction technique for the extraction of ginsenosides with enhanced antioxidant activity.

The beneficial effect of ginsenosides extracted by pulsed electric field against hydrogen peroxide-induced oxidative stress in HEK-293 cells

Liu, Di,Zhang, Ting,Chen, Zhifei,Wang, Ying,Ma, Shuang,Liu, Jiyun,Liu, Jingbo The Korean Society of Ginseng 2017 Journal of Ginseng Research Vol.41 No.2

Background: Ginsenosides are the main pharmacological components of Panax ginseng root, which are thought to be primarily responsible for the suppressing effect on oxidative stress. Methods: 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and oxygen radical absorption capacity were applied to evaluate the antioxidant activities of the ginsenosides. Human embryonic kidney 293 (HEK-293) cells were incubated with ginsenosides extracted by pulsed electric field (PEF) and solvent cold soak extraction (SCSE) for 24 h and then the injury was induced by $40{\mu}M$ $H_2O_2$. The cell viability and surface morphology of HEK-293 cells were studied using MTS assay and scanning electron microscopy, respectively. Dichloro-dihydro-fluorescein diacetate fluorescent probe assay was used to measure the level of intracellular reactive oxygen species. The intracellular antioxidant activities of ginsenosides were evaluated by cellular antioxidant activity assay in HepG2 cells. Results: The PEF extracts displayed the higher 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and stronger oxygen radical absorption capacity (with an oxygen radical absorption capacity value of $14.48{\pm}4.04{\mu}M\;TE\;per\;{\mu}g/mL$). The HEK-293 cell model also suggested that the protective effect of PEF extracts was dose-dependently greater than SCSE extracts. Dichloro-dihydro-fluorescein diacetate assay further proved that PEF extracts are more active (8% higher than SCSE extracts) in reducing intracellular reactive oxygen species accumulation. In addition, scanning electron microscopy images showed that the HEK-293 cells, which were treated with PEF extracts, maintained more intact surface morphology. Cellular antioxidant activity values indicated that ginsenosides extracted by PEF had stronger cellular antioxidant activity than SCSE ginsenosides extracts. Conclusion: The present study demonstrated the antioxidative effect of ginsenosides extracted by PEF in vitro. Furthermore, rather than SCSE, PEF may be more useful as an alternative extraction technique for the extraction of ginsenosides with enhanced antioxidant activity.

Visualizing the National Security Information Science Knowledge Network in China

Liu Di,Hua Minchao 아시아사회과학학회 2020 Jornal of Asia Social Science Vol.1 No.3

In order to better understand the development process and role of national security information in the field of national security research, this paper analyzes the scientific atlas of national security information from the perspective of overall national security concept, and concludes that the disciplines involved in studying national security issues under overall national security concept include ideological and political theory courses, national security science, security management, national security information science, etc., It points out that the continuous integration of related disciplines promotes the emergence of national security information science as a separate discipline, and points out the research trend of national security information under overall national security concept.

FOLLOW-UP OBSERVATIONS TOWARD PLANCK COLD CLUMPS WITH GROUND-BASED RADIO TELESCOPES

LIU, TIE,WU, YUEFANG,MARDONES, DIEGO,KIM, KEE-TAE,MENTEN, KARL M.,TATEMATSU, KEN,CUNNINGHAM, MARIA,JUVELA, MIKA,ZHANG, QIZHOU,GOLDSMITH, PAUL F,LIU, SHENG-YUAN,ZHANG, HUA-WEI,MENG, FANYI,LI, DI,LO, NA The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2

The physical and chemical properties of prestellar cores, especially massive ones, are still far from being well understood due to the lack of a large sample. The low dust temperature (< 14 K) of Planck cold clumps makes them promising candidates for prestellar objects or for sources at the very initial stages of protostellar collapse. We have been conducting a series of observations toward Planck cold clumps (PCCs) with ground-based radio telescopes. In general, when compared with other star forming samples (e.g. infrared dark clouds), PCCs are more quiescent, suggesting that most of them may be in the earliest phase of star formation. However, some PCCs are associated with protostars and molecular outflows, indicating that not all PCCs are in a prestellar phase. We have identified hundreds of starless dense clumps from a mapping survey with the Purple Mountain Observatory (PMO) 13.7-m telescope. Follow-up observations suggest that these dense clumps are ideal targets to search for prestellar objects.

Hierarchical hollow urchin-like structured MnO2 microsphere/carbon nanofiber composites as anode materials for Li-ion batteries

Di Liu,최원묵 한국물리학회 2019 Current Applied Physics Vol.19 No.6

In this work, novel hollow urchin-like MnO2 microspheres (u-MnO2), consisting of a hollow core with nanotubes, are synthesized by a simple hydrothermal process. The morphology of the MnO2 structures could be tuned from round particles to a hierarchical hollow urchin structure by controlling the hydrothermal reaction time, with no need for surfactant or templates. The nanostructures of the obtained u-MnO2 are characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The X-ray diffraction (XRD) pattern of the u-MnO2 reveals a tetragonal structure of α-MnO2. The carbon nanofibers (CNFs) are uniformly deposited on u-MnO2 to improve the electrical conductivity and to utilize the hierarchical architecture of u-MnO2. As the anode electrode of Li-ion batteries, the u-MnO2/CNFs nanocomposites exhibit discharge capacity of 988 mAh·g−1 after 100 cycles with a good rate capability. The superior electrochemical performances of the u- MnO2/CNFs nanocomposites can be attributed to the hierarchical urchin-like structures and the superior electrical conductivity of the nanocomposites, which can facilitate fast electron and ion transport and accommodate a large volume change during charge/discharge.

Elucidating Bottlenecks to the Efficient Preparation of AB₅-Hexamer Mucosal Adjuvant Protein LTm by Genetic Engineering

( Di Liu ),( Fabiao Hu ),( Wenpeng Wang ),( Dong Wu ),( Xiujuan He ),( Wenyun Zheng ),( Haipeng Liu ),( Xingyuan Ma ) 한국미생물생명공학회(구 한국산업미생물학회) 2017 Journal of microbiology and biotechnology Vol.27 No.8

Escherichia coli heat-labile enterotoxin (LT) and its non-toxic mutant (LTm) are well-known powerful mucosal adjuvants and immunogens. However, the yields of these adjuvants from genetically engineered strains remain at extremely low levels, thereby hindering their extensive application in fundamental and clinical research. Therefore, efficient production of these adjuvant proteins from genetically engineered microbes is a huge challenge in the field of molecular biology. In order to explore the expression bottlenecks of LTm in E. coli, we constructed a series of recombinant plasmids based on various considerations and gene expression strategies. After comparing the protein expression among strains containing different recombinant plasmids, the signal sequence was found to be critical for the expression of LTm and its subunits. When the signal sequence was present, the strong hydrophobicity and instability of this amino acid sequence greatly restricted the generation of subunits. However, when the signal sequence was removed, abundantly expressed subunits formed inactive inclusion bodies that could not be assembled into the hexameric native form, although the inclusion body subunits could be refolded and the biological activity recovered in vitro. Therefore, the dilemma choice of signal sequence formed bottlenecks in the expression of LTm. These results reveal the expression bottlenecks of LTm, provide guidance for the preparation of LTm and its subunits, and certainly help to promote efficient preparation of this mucosal adjuvant protein.

The TOP-SCOPE Survey of <i>Planck</i> Galactic Cold Clumps: Survey Overview and Results of an Exemplar Source, PGCC G26.53+0.17

Liu, Tie,Kim, Kee-Tae,Juvela, Mika,Wang, Ke,Tatematsu, Ken’ichi,Francesco, James Di,Liu, Sheng-Yuan,Wu, Yuefang,Thompson, Mark,Fuller, Gary,Eden, David,Li, Di,Ristorcelli, I.,Kang, Sung-ju,Lin, Yuxin Published by the University of Chicago Press for t 2018 The Astrophysical journal Supplement series Vol.234 No.2

<P>The low dust temperatures (< 14 K) of Planck Galactic cold clumps (PGCCs) make them ideal targets to probe the initial conditions and very early phase of star formation. 'TOP-SCOPE' is a joint survey program targeting similar to 2000 PGCCs in J = 1-0 transitions of CO isotopologues and similar to 1000 PGCCs in 850 mu m continuum emission. The objective of the 'TOP-SCOPE' survey and the joint surveys (SMT 10 m, KVN 21 m, and NRO 45 m) is to statistically study the initial conditions occurring during star formation and the evolution of molecular clouds, across a wide range of environments. The observations, data analysis, and example science cases for these surveys are introduced with an exemplar source, PGCC G26.53+0.17 (G26), which is a filamentary infrared dark cloud (IRDC). The total mass, length, and mean line mass (M/L) of the G26 filament are similar to 6200 M-circle dot, similar to 12 pc, and similar to 500 M-circle dot pc(-1), respectively. Ten massive clumps, including eight starless ones, are found along the filament. The most massive clump as a whole may still be in global collapse, while its denser part seems to be undergoing expansion owing to outflow feedback. The fragmentation in the G26 filament from cloud scale to clump scale is in agreement with gravitational fragmentation of an isothermal, nonmagnetized, and turbulent supported cylinder. A bimodal behavior in dust emissivity spectral index (beta) distribution is found in G26, suggesting grain growth along the filament. The G26 filament may be formed owing to large-scale compression flows evidenced by the temperature and velocity gradients across its natal cloud.</P>

A Novel Torque Ripple Suppression Scheme of Switched Reluctance Motors Based on Unipolar Sinusoidal Current Excitation

Liu Jian,Wang Guofeng,Liu Di,Fan Yunsheng,Sheng Linhao 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.4

This paper presents a novel control strategy for switched reluctance motors under unipolar sinusoidal excitation to minimize torque ripple at medium and low speeds. This strategy focuses on enhancing both the accuracy of the conversion process and the performance of current tracking. For the conversion scheme, a modifi ed back propagation neural network that considers the magnetic saturation characteristic is proposed. The lightweight network structure of this conversion allows for seamless integration into the unipolar sinusoidal excitation strategy, enabling fast and accurate online calculation of the q-axis current. Additionally, to improve the current tracking capability, an improved predictive current controller is designed, with a Luenberger disturbance observer incorporated to address predictive model mismatch. The stability of the system is proven in the discrete-time domain using the Jury criterion. Experimental results demonstrate that the proposed method can eff ectively suppress both torque ripple and disturbances, achieving good overall performance.

중국 스포츠관광 활성화를 위한 탐색적 연구

Liu Di,강순화 한국비교정부학회 2023 한국비교정부학보 Vol.27 No.3

(Purpose) Sports tourism is a new industry that combines the tourism industry and the sports industry, and the phenomenon of globalized culture and the development status of the tourism industry have an important impact on the development of the national economy. The purpose of this study was to analyze the development status of sports tourism in China and the mechanism of sports tourism development and to present directions that can contribute to the development of sports tourism. (Design/methodology/approach) This study used the literature data research method, collected data related to the Chinese tourism industry and sports industry from 2010 to 2019 through the China Tourism Yearbook, China Statistics Bureau, and the National Sports Bureau platform, and analyzed the development trend and combined development status of Chinese sports tourism. (Findings) As a result of the study, the conditions of Chinese sports tourism development were mainly analyzed in terms of the natural environment, economic conditions, activation of various events, policy support, and infrastructure conditions. (Research implications or Originality) China is a country rich in population and resources, but the level of development of sports tourism is certainly lagging behind that of Western countries. Therefore, this study summarized the current development process of sports tourism in China, suggested ways to promote the development of sports tourism in China, and sought ways suitable for the development of tourism in China.

Direct azidation of isotactic polypropylene and synthesis of ‘grafted to’ derivatives thereof using azide–alkyne cycloaddition chemistry

Liu, Di,Bielawski, Christopher W John Wiley Sons, Ltd 2017 Polymer international Vol.66 No.1

<P><B>Abstract</B></P><P>Azido‐functionalized isotactic polypropylene was prepared via the direct CH azidation of a commercially available polymer using a stable azidoiodinane. Including imidazole or benzimidazole in the reaction mixture was found to significantly improve the yields of the post‐polymerization modification. Although chain cleavage was observed, the methodology afforded high‐molecular‐weight (<I>M</I><SUB>w</SUB> > 100 kDa) functionalized polypropylene containing up to 3 mol% of azido groups and enabled access to polypropylene‐<I>graft</I>‐poly(ethylene glycol) copolymers via azide–alkyne cycloaddition chemistry. © 2016 Society of Chemical Industry</P>