STUDY ON THE SYNTHESIS OF PUERARIN DERIVATIVES AND THEIR ANTI-VASCULAR DEMENTIA ACTIVITY

In this study, puerarin derivatives were designed by adding an active acetonitrile group that inhibits cyclooxygenase-2 (COX-2) in order to enhance the anti-vascular dementia drug activity. The acetonitrile group was linked to puerarin at the 7/4 'positions by a phenolic hydroxyl to give 7-mono-and 7, 4' di-substituted derivatives of puerarin. These structures were confirmed by 1H NMR spectroscopy and MS spectroscopy. We compared the affinity of puerarin derivatives and puerarin for cyclooxygenase-2 (COX-2) using molecular docking. In addition, the anti-vascular dementia activity of the developed puerarin derivatives was studied by water maze, novel object recognition, and the determination of inducible nitric oxide synthase (iNOS) enzyme activity at the cerebral cortex of mice. Experimental results showed that the puerarin derivatives have a good affinity for COX-2 with therapeutic effects against vascular dementia. The results of this study suggest that the protective effects of the puerarin derivatives against vascular dementia may be related to suppression of inflammation associated with ischemia-reperfusion injury through inhibition of COX-2

Spectral Efficiency Analysis of Multi-Cell Massive MIMO Systems with Ricean Fading

This paper investigates the spectral efficiency of multi-cell massive multiple-input multiple-output systems with Ricean fading that utilize the linear maximal-ratio combining detector. We firstly present closed-form expressions for the effective signal-to-interference-plus-noise ratio (SINR) with the least squares and minimum mean squared error (MMSE) estimation methods, respectively, which apply for any number of base-station antennas $M$ and any Ricean $K$-factor. Also, the obtained results can be particularized in Rayleigh fading conditions when the Ricean $K$-factor is equal to zero. In the following, novel exact asymptotic expressions of the effective SINR are derived in the high $M$ and high Ricean $K$-factor regimes. The corresponding analysis shows that pilot contamination is removed by the MMSE estimator when we consider both infinite $M$ and infinite Ricean $K$-factor, while the pilot contamination phenomenon persists for the rest of cases. All the theoretical results are verified via Monte-Carlo simulations.Comment: 15 pages, 2 figures, the tenth International Conference on Wireless Communications and Signal Processing (WCSP 2018), to appea

Pilot Power Allocation Through User Grouping in Multi-Cell Massive MIMO Systems

In this paper, we propose a relative channel estimation error (RCEE) metric, and derive closed-form expressions for its expectation $\rm {Exp}_{rcee}$ and the achievable uplink rate holding for any number of base station antennas $M$, with the least squares (LS) and minimum mean squared error (MMSE) estimation methods. It is found that RCEE and $\rm {Exp}_{rcee}$ converge to the same constant value when $M\rightarrow\infty$, resulting in the pilot power allocation (PPA) is substantially simplified and a PPA algorithm is proposed to minimize the average $\rm {Exp}_{rcee}$ per user with a total pilot power budget $P$ in multi-cell massive multiple-input multiple-output systems. Numerical results show that the PPA algorithm brings considerable gains for the LS estimation compared with equal PPA (EPPA), while the gains are only significant with large frequency reuse factor (FRF) for the MMSE estimation. Moreover, for large FRF and large $P$, the performance of the LS approaches to the performance of the MMSE, which means that simple LS estimation method is a very viable when co-channel interference is small. For the achievable uplink rate, the PPA scheme delivers almost the same average achievable uplink rate and improves the minimum achievable uplink rate compared with the EPPA scheme.Comment: 30 pages, 5 figures, submitted to IEEE Transactions on Communication

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日中台共同研究「現代中国と東アジアの新環境」 ②21世紀の日中関係 : 青年研究者の思索と対話翻訳：和田英男（わだひでお