RISS 학술연구정보서비스

검색
다국어 입력

http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.

변환된 중국어를 복사하여 사용하시면 됩니다.

예시)
  • 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
  • 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
닫기
    인기검색어 순위 펼치기

    RISS 인기검색어

      검색결과 좁혀 보기

      선택해제
      • 좁혀본 항목 보기순서

        • 원문유무
        • 원문제공처
        • 등재정보
        • 학술지명
          펼치기
        • 주제분류
        • 발행연도
          펼치기
        • 작성언어
        • 저자
          펼치기

      오늘 본 자료

      • 오늘 본 자료가 없습니다.
      더보기
      • 무료
      • 기관 내 무료
      • 유료
      • KCI등재
      • KCI등재

        Metabolism of dl-Praeruptorin A in Rat Liver Microsomes using HPLC-Electrospray Ionization Tandem Mass Spectrometry

        Hang Ruan,Xuan Zhu,Zhen Zhang,Xin-fang Liang,Yan Fu,Mei-qin Su,Qi-lin Liu,Xiu-min Wang 대한약학회 2011 Archives of Pharmacal Research Vol.34 No.8

        dl-Praeruptorin A (Pd-Ia) is the major active constituent of the traditional Chinese medicine Peucedanum praeruptorum Dunn. Recently it has been identified as a novel agent in the treatment and prevention of cardiovascular diseases. Accordingly, we investigated the metabolism of Pd-Ia in rat liver microsomes. The involvement of cytochrome P450 (CYP) and CYP isoforms were identified using a CYP-specific inhibitor (SKF-525A), CYP-selective inhibitors (α-naphthoflavone, metyrapone, fluvastatin, quinidine, disulfiram, ketoconazole and ticlopidine) and CYP-selective inducers (phenobarbital, dexamethasone and β-naphthoflavone). Residual concentrations of the substrate and metabolites were determined by HPLC, and further identified by their mass spectra and chromatographic behavior. These experiments showed that CYP450 is involved in Pd-Ia metabolism, and that the major CYP isoform responsible is CYP3A1/2, which acts in a concentration-dependent manner. Four Pd-Ia metabolites (M1, M2, M3, and M4) were detected after incubation with rat liver microsomes. Hydroxylation was the primary metabolic pathway of Pd-Ia, and possible chemical structures of the metabolites were identified. Further research is now needed to link the metabolism of Pd-Ia to its drug-drug interactions.

      • KCI등재

        Planning and Execution of Dynamic Whole-body Locomotion for a Wheeled Biped Robot on Uneven Terrain

        Yaxian Xin,Jiuhong Ruan,Yibin Li,Hui Chai,Xuewen Rong 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.4

        To improve the adaptability of the wheeled biped robot (WBR) to uneven terrain, firstly an integrated modeling method for wheeled-legs is proposed. The under-actuated part is effectively restrained by defining the interaction force between the WBR and the trunk. The mapping relationship between the wheeled leg’s end force and the joint torques in the balanced state is built. Based on this premise, a control framework that does not rely on external sensors is proposed, and the trunk pose is used as the task space to plan the generalized force output of the wheeled legs and calculate the joint torques. Since the joint space position is not constrained, the leg wheels will be based on the terrain conditions and are adaptively stretched and adjusted back and forth. To further improve the terrain adaptability, a slope estimator and a stabilizer are constructed to deal with the attitude fluctuation caused by the sudden change of terrain. The control framework is proved to verify by simulations and experiment.

      • KCI등재

        Remarkable impact of amino acids on ginsenoside transformation from fresh ginseng to red ginseng

        Zhi Liu,Xin Wen,Chong-Zhi Wang,Wei Li,Wei-Hua Huang,Juan Xia,Chang-Chun Ruan,Chun-Su Yuan 고려인삼학회 2020 Journal of Ginseng Research Vol.44 No.3

        Background: Amino acids are one of the major constituents in Panax ginseng, including neutral aminoacid, acidic amino acid, and basic amino acid. However, whether these amino acids play a role in ginsenosideconversion during the steaming process has not yet been elucidated. Methods: In the present study, to elucidate the role of amino acids in ginsenoside transformation fromfresh ginseng to red ginseng, an amino acids impregnation pretreatment was applied during thesteaming process at 120 C. Acidic glutamic acid and basic arginine were used for the acid impregnationtreatment during the root steaming. The ginsenosides contents, pH, browning intensity, and free aminoacids contents in untreated and amino acidetreated P. ginseng samples were determined. Results: After 2 h of steaming, the concentration of less polar ginsenosides in glutamic acidetreatedP. ginseng was significantly higher than that in untreated P. ginseng during the steaming process. However,the less polar ginsenosides in arginine-treated P. ginseng increased slightly. Meanwhile, free aminoacids contents in fresh P. ginseng, glutamic acid-treated P. ginseng, and arginine-treated P. ginsengsignificantly decreased during steaming from 0 to 2h. The pH also decreased in P. ginseng samples at hightemperatures. The pH decrease in red ginseng was closely related to the decrease in basic amino acidslevels during the steaming process. Conclusion: Amino acids can remarkably affect the acidity of P. ginseng sample by altering the pH value. Theywere the main influential factors for the ginsenoside transformation. These results are useful in elucidatingwhy andhowsteaming induces the structural change of ginsenoside in P. ginseng and also provides an effectiveand green approach to regulate the ginsenoside conversion using amino acids during the steaming process.

      • KCI등재

        Chloride diffusivity of concrete: probabilistic characteristics at meso-scale

        Zichao Pan,Xin Ruan,Airong Chen 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.13 No.2

        This paper mainly discusses the influence of the aggregate properties including grading, shape, content and distribution on the chloride diffusion coefficient, as well as the initiation time of steel corrosion from a probabilistic point of view. Towards this goal, a simulation method of random aggregate structure (RAS) based on elliptical particles and a procedure of finite element analysis (FEA) at meso-scale are firstly developed to perform the analysis. Next, the chloride diffusion coefficient ratio between concrete and cement paste ??app??cp is chosen as the index to represent the effect of aggregates on the chloride diffusion process. Identification of the random distribution of this index demonstrates that it can be viewed as actually having a normal distribution. After that, the effect of aggregates on ??app??cp is comprehensively studied, showing that the appropriate properties of aggregates should be decided by both of the average and the deviation of ??app??cp . Finally, a case study is conducted to demonstrate the application of this mesoscopic method in predicting the initiation time of steel corrosion in reinforced concrete (RC) structures. The mesoscopic probabilistic method developed in this paper can not only provide more reliable evidences on the proper grading and shape of aggregates, but also play an important role in the probability-based design method.

      • KCI등재

        Extreme value modeling of structural load effects with non-identical distribution using clustering

        Junyong Zhou,Xin Ruan,Xuefei Shi,Chudong Pan 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.74 No.1

        The common practice to predict the characteristic structural load effects (LEs) in long reference periods is to employ the extreme value theory (EVT) for building limit distributions. However, most applications ignore that LEs are driven by multiple loading events and thus do not have the identical distribution, a prerequisite for EVT. In this study, we propose the composite extreme value modeling approach using clustering to (a) cluster initial blended samples into finite identical distributed subsamples using the finite mixture model, expectation-maximization algorithm, and the Akaike information criterion; (b) combine limit distributions of subsamples into a composite prediction equation using the generalized Pareto distribution based on a joint threshold. The proposed approach was validated both through numerical examples with known solutions and engineering applications of bridge traffic LEs on a long-span bridge. The results indicate that a joint threshold largely benefits the composite extreme value modeling, many appropriate tail approaching models can be used, and the equation form is simply the sum of the weighted models. In numerical examples, the proposed approach using clustering generated accurate extrema prediction of any reference period compared with the known solutions, whereas the common practice of employing EVT without clustering on the mixture data showed large deviations. Real-world bridge traffic LEs are driven by multi-events and present multipeak distributions, and the proposed approach is more capable of capturing the tendency of tailed LEs than the conventional approach. The proposed approach is expected to have wide applications to general problems such as samples that are driven by multiple events and that do not have the identical distribution.

      • KCI등재

        A 2-D numerical research on spatial variability of concrete carbonation depth at meso-scale

        Zichao Pan,Xin Ruan,Airong Chen 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.15 No.2

        This paper discusses the spatial variability of the carbonation depth caused by the mesoscopic structure of the concrete and the influence of the spatial variability on the thickness of the concrete cover. To conduct the research, a method to generate the random aggregate structure (RAS) based on polygonal particles and a simplified numerical model of the concrete carbonation at meso-scale are firstly developed. Based on the method and model, the effect of the aggregate properties including shape, content and gradation on the spatial variability of the carbonation depth is comprehensively studied. The results show that a larger degree of the spatial variability will be obtained by using (1) the aggregates with a larger aspect ratio; (2) a larger aggregate content; (3) the gradation which has more large particles. The proper sample size and model size used in the analysis are also studied. Finally, a case study is conducted to demonstrate the influence of the spatial variability of the carbonation depth on the proper thickness of the concrete cover. The research in this paper not only provides suggestions on how to decrease the spatial variability, but also proposes the method to consider the effect of the spatial variability in designing the thickness of the concrete cover.

      • SCIESCOPUSKCI등재

        Remarkable impact of amino acids on ginsenoside transformation from fresh ginseng to red ginseng

        Liu, Zhi,Wen, Xin,Wang, Chong-Zhi,Li, Wei,Huang, Wei-Hua,Xia, Juan,Ruan, Chang-Chun,Yuan, Chun-Su The Korean Society of Ginseng 2020 Journal of Ginseng Research Vol.44 No.3

        Background: Amino acids are one of the major constituents in Panax ginseng, including neutral amino acid, acidic amino acid, and basic amino acid. However, whether these amino acids play a role in ginsenoside conversion during the steaming process has not yet been elucidated. Methods: In the present study, to elucidate the role of amino acids in ginsenoside transformation from fresh ginseng to red ginseng, an amino acids impregnation pretreatment was applied during the steaming process at 120℃. Acidic glutamic acid and basic arginine were used for the acid impregnation treatment during the root steaming. The ginsenosides contents, pH, browning intensity, and free amino acids contents in untreated and amino acid-treated P. ginseng samples were determined. Results: After 2 h of steaming, the concentration of less polar ginsenosides in glutamic acid-treated P. ginseng was significantly higher than that in untreated P. ginseng during the steaming process. However, the less polar ginsenosides in arginine-treated P. ginseng increased slightly. Meanwhile, free amino acids contents in fresh P. ginseng, glutamic acid-treated P. ginseng, and arginine-treated P. ginseng significantly decreased during steaming from 0 to 2h. The pH also decreased in P. ginseng samples at high temperatures. The pH decrease in red ginseng was closely related to the decrease in basic amino acids levels during the steaming process. Conclusion: Amino acids can remarkably affect the acidity of P. ginseng sample by altering the pH value. They were the main influential factors for the ginsenoside transformation. These results are useful in elucidating why and how steaming induces the structural change of ginsenoside inP. ginseng and also provides an effective and green approach to regulate the ginsenoside conversion using amino acids during the steaming process.

      • SCIEKCI등재

        Atrial fibrillation in critically ill patients who received prolonged mechanical ventilation: a nationwide inpatient report

        ( Zhen Lin ),( Hedong Han ),( Wei Guo ),( Xin Wei ),( Zhijian Guo ),( Shujie Zhai ),( Shuai Li ),( Yiming Ruan ),( Fangyuan Hu ),( Dongdong Li ),( Jia He ) 대한내과학회 2021 The Korean Journal of Internal Medicine Vol.36 No.6

        Background/Aims: To evaluate temporal trends of atrial fibrillation (AF) prevalence in critically ill patients who received prolonged mechanical ventilation (MV) in the United States. Methods: We used the 2008 to 2014 National Inpatient Sample to compute the weighted prevalence of AF among hospitalized adult patients on prolonged MV. We used multivariable-adjusted models to evaluate the association of AF with clinical factors, in-hospital mortality, hospitalization cost, and length of stay (LOS). Results: We identified 2,578,165 patients who received prolonged MV (21.27% of AF patients). The prevalence of AF increased from 14.63% in 2008 to 24.43% in 2014 (p for trend < 0.0001). Amongst different phenotypes of critically ill patients, the prevalence of AF increased in patients with severe sepsis, asthma exacerbation, congestive heart failure exacerbation, acute stroke, and cardiac arrest. Older age, male sex, white race, medicare access, higher income, urban teaching hospital setting, and Western region were associated with a higher prevalence of AF. AF in critical illness was a risk factor for in-hospital death (odds ratio, 1.13; 95% confidence interval, 1.11 to 1.15), but in-hospital mortality in critically ill patients with AF decreased from 11.6% to 8.3%. AF was linked to prolonged LOS (2%, p < 0.0001) and high hospitalization cost (4%, p < 0.0001). LOS (-1%, p < 0.0001) and hospitalization cost (-4%, p < 0.0001) decreased yearly. Conclusions: The prevalence of comorbid AF is increasing, particularly in older patients. AF may lead to poorer prognosis, and high-quality intensive care is imperative for this population.

      • Tailoring fabric geometry of plain-woven composites for simultaneously enhancing stiffness and thermal properties

        Xiao-Yi Zhou,Neng-Wei Wang,Wen Xiong,Xin Ruan,Shao-Jin Zhang 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.42 No.4

        This paper proposes a numerical optimization method to design the mesoscale architecture of textile composite for simultaneously enhancing mechanical and thermal properties, which compete with each other making it difficult to design intuitively. The base cell of the periodic warp and fill yarn system is served as the design space, and optimal fibre yarn geometries are found by solving the optimization problem through the proposed method. With the help of homogenization method, analytical formulae for the effective material properties as functions of the geometry parameters of plain-woven textile composites were derived, and they are used to form the inverse homogenization method to establish the design problem. These modules are then put together to form a multiobjective optimization problem, which is formulated in such a way that the optimal design depends on the weight factors predetermined by the user based on the stiffness and thermal terms in the objective function. Numerical examples illustrate that the developed method can achieve reasonable designs in terms of fibre yarn paths and geometries.

      연관 검색어 추천

      이 검색어로 많이 본 자료

      활용도 높은 자료

      해외이동버튼