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Dat, L.D.,Thao, N.P.,Luyen, B.T.T.,Tai, B.H.,Jeong, M.H.,Woo, M.H.,Kim, Y.H. Pergamon Press 2016 Bioorganic & medicinal chemistry letters Vol.26 No.3
Chemical investigation of Acanthopanax koreanum leaves resulted in the isolation of 13 compounds (1-13), including six new (20,29)-dehydrolupane-type triterpenoids: 3α,11α,30-trihydroxylup-20(29)-en-23,28-dioic acid (1), 3α,11α,30-trihydroxylup-20(29)-en-28-oic acid (2), 3α,11α,30-trihydroxylup-23-al-20(29)-en-28-oic acid (3), 3α, 11α-dihydroxy-20-oxo-30-norlupane-23,28-dioic acid (5), (20S)-3α-hydroxy-30 oxolupane-23,28-dioic acid (8), (20S)-3β,7β,29-trihydroxy-lupane-23-al-28-oic acid (10), and one novel compound isolated for the first time, named 3α,20α,29-trihydroxylupane-23,28-dioic acid (9), together with six known compounds (4, 6, 7, and 11-13). Chemical structures of the isolated compounds were evaluated by analyzing and comparing spectroscopic data with those reported in the literature. These compounds were also evaluated for their tyrosinase inhibitory effects. Among them, compounds 3, 7, 9, and 12 showed significant inhibitory effects, with inhibitory concentrations of 50% (IC<SUB>50</SUB>) values ranging from 8.61 to 63.5μM.
Lim, H.,Min, D.S.,Yun, H.E.,Kim, K.T.,Sun, Y.N.,Dat, L.D.,Kim, Y.H.,Kim, H.P. Elsevier Sequoia 2017 Journal of Ethnopharmacology Vol.209 No.-
Ethnopharmacological relevance: Acanthopanax koreanum (Araliaceae) has been used in traditional medicine for enhancing vitality, rheumatism, and bone-related pains. But its activity on cartilage protection has not been known yet. Aim of the study: Matrix metalloproteinase (MMP)-13 has an important role in degrading cartilage materials under pathologic conditions such as arthritis. The present study was designed to find the inhibitory activity of impressic acid on MMP-13 expression and cartilage protective action. Materials and methods: 70% ethanol extract of Acanthopanax koreanum leaves and impressic acid, a major constituent isolated from the same plant materials, were examined on MMP-13 down-regulating capacity in IL-1β-treated human chondrocyte cell line (SW1353) and rabbit cartilage explants. Results: In IL-1β-treated SW1353 cells, impressic acid significantly and concentration-dependently inhibited MMP-13 expression at 0.5-10μM. Impressic acid was found to be able to inhibit MMP-13 expression by blocking the phosphorylation of signal transducer and activator of transcription-1/-2 (STAT-1/-2) and activation of c-Jun and c-Fos among the cellular signaling pathways involved. Further, impressic acid was found to inhibit the expression of MMP-13 mRNA (47.7% inhibition at 10μM), glycosaminoglycan release (42.2% reduction at 10μM) and proteoglycan loss in IL-1-treated rabbit cartilage explants culture. In addition, a total of 21 lupane-type triterpenoids structurally-related to impressic acid were isolated from the same plant materials and their suppressive activities against MMP-13 expression were also examined. Among these derivatives, compounds 2, 3, 16, and 18 clearly down-regulated MMP-13 expression. However, impressic acid was more potent than these derivatives in down-regulating MMP-13 expression. Conclusions: Impressic acid, its related triterpenoids, and A. koreanum extract have potential as therapeutic agents to prevent cartilage degradation by inhibiting matrix protein degradation.
Kohri, H.,Wang, S. Y.,Shiu, S. H.,Chang, W. C.,Yanai, Y.,Ahn, D. S.,Ahn, J. K.,Chen, J. Y.,Daté,, S.,Ejiri, H.,Fujimura, H.,Fujiwara, M.,Fukui, S.,Gohn, W.,Hicks, K.,Hosaka, A.,Hotta, T.,Hwang, American Physical Society 2018 Physical review. C Vol.97 No.1
<P>Differential cross sections and photon-beam asymmetries for the (gamma) over right arrowp -> pi(+) n reaction have been measured for 0.6 < cos theta(pi) < 1 and E-gamma = 1.5-2.95 GeV at SPring-8/LEPS. The cross sections monotonically decrease as the photon beam energy increases for 0.6 < cos theta(pi) < 0.9. However, the energy dependence of the cross sections for 0.9 < cos theta(pi) < 1 and E-gamma = 1.5-2.2 GeV (W = 1.9-2.2 GeV) is different, which may be due to a nucleon or Delta resonance. The present cross sections agree well with the previous cross sections measured by other groups and show forward peaking, suggesting significant t-channel contributions in this kinematical region. The asymmetries are found to be positive, which can be explained by rho exchange in the t channel. Large positive asymmetries in the small-vertical bar t vertical bar region, where the rho-exchange contribution becomes small, could be explained by introducing p-exchange interference with the s channel.</P>
Kohri, H.,Shiu, S. H.,Chang, W. C.,Yanai, Y.,Ahn, D. S.,Ahn, J. K.,Chen, J. Y.,Daté,, S.,Ejiri, H.,Fujimura, H.,Fujiwara, M.,Fukui, S.,Gohn, W.,Hicks, K.,Hosaka, A.,Hotta, T.,Hwang, S. H.,Imai, American Physical Society 2018 Physical Review Letters Vol.120 No.20
<P>Differential cross sections and photon-beam asymmetries for the gamma(->)p -> Pi(-)Delta(++)(1232) reaction have been measured for 0.7 < cos Theta(c.m.)(Pi) < 1 and E-gamma= 1.5-2.95 GeV at SPring-8/LEPS. The first-ever high statistics cross-section data are obtained in this kinematical region, and the asymmetry data for 1.5 < E-gamma(GeV) < 2.8 are obtained for the first time. This reaction has a unique feature for studying the production mechanisms of a pure uu quark pair in the final state from the proton. Although there is no distinct peak structure in the cross sections, a non-negligible excess over the theoretical predictions is observed at E-gamma= 1.5-1.8 GeV. The asymmetries are found to be negative in most of the present kinematical regions, suggesting the dominance of n exchange in the t channel. The negative asymmetries at forward meson production angles are different from the asymmetries previously measured for the photoproduction reactions producing a dd(-) or an ss quark pair in the final state. Advanced theoretical models introducing nucleon resonances and additional unnatural-parity exchanges are needed to reproduce the present data.</P>
Shiu, S. H.,Kohri, H.,Chang, W. C.,Ahn, D. S.,Ahn, J. K.,Chen, J. Y.,Daté,, S.,Ejiri, H.,Fujimura, H.,Fujiwara, M.,Fukui, S.,Gohn, W.,Hicks, K.,Hotta, T.,Hwang, S. H.,Imai, K.,Ishikawa, T.,Joo, American Physical Society 2018 Physical Review C Vol.97 No.1
<P>We report the measurement of the gamma p -> K+Lambda and gamma p -> K+Sigma(0) reactions at SPring-8. The differential cross sections and photon-beam asymmetries are measured at forward K+ production angles using linearly polarized tagged-photon beams in the range of E-gamma = 1.5-3.0 GeV. With increasing photon energy, the cross sections for both gamma p -> K+Lambda and gamma p -> K+Sigma(0) reactions decrease slowly. Distinct narrow structures in the production cross section have not been found at E gamma = 1.5-3.0 GeV. The forward peaking in the angular distributions of cross sections, a characteristic feature of t-channel exchange, is observed for the production of Lambda in the whole observed energy range. A lack of similar feature for Sigma(0) production reflects a less dominant role of t-channel contribution in this channel. The photon-beam asymmetries remain positive for both reactions, suggesting the dominance of K* exchange in the t channel. These asymmetries increase gradually with the photon energy, and have a maximum value of +0.6 for both reactions. Comparison with theoretical predictions based on the Regge trajectory in the t channel and the contributions of nucleon resonances indicates the major role of t-channel contributions as well as non-negligible effects of nucleon resonances in accounting for the reaction mechanism of hyperon photoproduction in this photon energy regime.</P>
Interference Effect betweenϕandΛ(1520)Production Channels in theγp→K+K−pReaction near Threshold
Ryu, S. Y.,Ahn, J. K.,Nakano, T.,Ahn, D. S.,Ajimura, S.,Akimune, H.,Asano, Y.,Chang, W. C.,Chen, J. Y.,Daté,, S.,Ejiri, H.,Fujimura, H.,Fujiwara, M.,Fukui, S.,Hasegawa, S.,Hicks, K.,Horie, K.,Ho American Physical Society 2016 Physical Review Letters Vol.116 No.23
<P>The phi-Lambda(1520) interference effect in the gamma p -> K(+)K(-)p reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between phi and Lambda(1520) production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when K+K- pairs are observed at forward angles but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the root s = 2.1 GeV bump structure in forward differential cross sections for phi photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange, or rescattering processes via other hyperon states.</P>
CASCADE STATE CONTROL OF ROBUST AC-DRIVES
R.Schonfeld,D.H.Dat,H.Lorenz,Ng.Ph.Quang 전력전자학회 1992 ICPE(ISPE)논문집 Vol.1992 No.4
Powerful processors enable to use the state-control in practical applications. To control AC-Drives, the cascade state control is used (Fig. 1) ?<br/> The torque proportional current component is the output value of the outer control loop and the leading value of the inner control loop. This signal is limited. The advantages of this structure, compared to traditional controlmethods are<br/> - very fast torque inpression, based on current-state-control<br/> - robustness against changings of rotor flux coupling<br/> - torque control in the full range of torquelimitation<br/> - aperiodic motion control via an elastically coupled mechanical transmission system<br/> - limitation of the application of sensors by use of state- and disturbance-observers<br/> - robustness against parameter-changings and nonlinearities of the mechanical transmission system<br/> - use of an effective selfcommissioning strategy under respect of the laws of matrix-algebra<br/> - use of an unificated hardware and a unificated software structure for induction motors and synchronous motors<br/> The theoretical analysis is based on discrete state equations. The discretisation of the state equations is combined with a linearisation of the problem. We get useful algorithm to adapt the controllermatrix to the observermatrix automatically.<br/>
Mizutani, K.,Niiyama, M.,Nakano, T.,Yosoi, M.,Nozawa, Y.,Ahn, D. S.,Ahn, J. K.,Chang, W. C.,Chen, J. Y.,Daté,, S.,Gohn, W.,Hamano, H.,Hashimoto, T.,Hicks, K.,Hiraiwa, T.,Hotta, T.,Hwang, S. H.,I American Physical Society 2017 Physical Review C Vol.96 No.6
<P>Differential cross sections at t = t(min) and decay asymmetries for the gamma p -> phi p reaction have been measured using linearly polarized photons in the range 1.5 to 2.9 GeV. These cross sections were used to determine the Pomeron strength factor. The cross sections and decay asymmetries are consistently described by the t-channel Pomeron and pseudoscalar exchange model in the E-gamma region above 2.37 GeV. In the lower energy region, an excess over the model prediction is observed in the energy dependence of the differential cross sections at t = t(min). This observation suggests that additional processes or interference effects between Pomeron exchange and other processes appear near the threshold region.</P>