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Non-linear Radical Additions-Coupling Polymerization of Monovinyl Monomers towards Polymer Networks: Theory, Tunability and Heritable Architecture

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Chinese Journal of Polymer Science 2022年第12期40卷 1623-1630,I0008页

作者： Li-mei ren Cheng-Lin Li Qi Wang MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science&Engineering Zhejiang UniversityHangzhou 310027China Current address:Zhejiang University-University of Edinburgh Institute Zhejiang University School of Medicineand Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang ProvinceZhejiang University School of MedicineHangzhou 310027China

Exploring new polymerization strategy for current available monomers is a big challenge in polymer science. Here we re-investigate radical polymerization of monovinyl monomer(MVM) initiated by uniform branched polyfunctional initiator(PFI), which is termed non-linear radical additions-coupling polymerization(NLRAs CP). In NLRAs CP, both addition and coupling reactions of radical contribute to the construction of the polymer chains, which leads to continuous growth of branch topology. Theoretical analysis of NLRAs CP predicts that the gelation is determined by the functionality of PFI(a), the extent of initiation of the PFI(q) and the termination factor of radical(φ). NLRAs CPs of styrene and methyl methacrylate promoted by Cu(0)/MeTren or Mn_(2)(CO)_(10)/visible light were conducted. After the cleavage of incorporated PFI fragment or junctions in the network, the network was transformed to linear chains having almost the same structure as segmental chains in the precursor network. This allows the reverse deducing the network structure from its cleaved products. It has been proven that NLRAs CP includes stepwise initiation of PFI, chain-growth of segmental chains and successive endlinking of macroradicals derived from PFI. The three parameters related to the gelation process, a, q and φ, were adjusted via binary PFI, the feed ratio of [Mn_(2)(CO)_(10)]/[PFI] and addition of non-homopolymerizable comonomer respectively. The minimum values of a and q, and the minimum amount of comonomer required for gelation were determined,which can be applied to estimate φ of various macroradicals. NLRAs CP opens a general and facile strategy for synthesis of a variety of polymer networks with heritable architecture by one-pot polymerization of various MVMs.

关键词： Non-linear radical additions-coupling polymerization Monovinyl monomer Polyfunctional initiator Polymer network Theory

Joint application of feature extraction based on EMD-AR strategy and multi-class classifier based on LS-SVM in EMG motion classification

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第8期8卷 1246-1255页

作者： YAN Zhi-guo WANG Zhi-zhong ren Xiao-mei Departmen of Biomedical Engineering Shanghai Jiao Tong University Shanghai 200030 China

This paper presents an effective and efficient combination of feature extraction and multi-class classifier for motion classification by analyzing the surface electromyografic(sEMG) signals. In contrast to the existing methods,considering the non-stationary and nonlinear characteristics of EMG signals,to get the more separable feature set,we introduce the empirical mode decomposition(EMD) to decompose the original EMG signals into several intrinsic mode functions(IMFs) and then compute the coefficients of autoregressive models of each IMF to form the feature set. Based on the least squares support vector machines(LS-SVMs) ,the multi-class classifier is designed and constructed to classify various motions. The results of contrastive experiments showed that the accuracy of motion recognition is improved with the described classification scheme. Furthermore,compared with other classifiers using different features,the excellent performance indicated the potential of the SVM techniques embedding the EMD-AR kernel in motion classification.

关键词： Electromyografic signal Empirical mode decomposition (EMD) Auto-regression model Wavelet packet transform Least squares support vector machines (LS-SVM) Neural network

Multifractal analysis of surface EMG signals for assessing muscle fatigue during static contractions

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第6期8卷 910-915页

作者： WANG Gang ren Xiao-mei LI Lei WANG Zhi-zhong Department of Biomedical Engineering Shanghai Jiao Tong University Shanghai 200240 China

This study is aimed at assessing muscle fatigue during a static contraction using multifractal analysis and found that the surface electromyographic （SEMG） signals characterized multiffactality during a static contraction. By applying the method of direct determination ofthef（a） singularity spectrum, the area of the multifractal spectrum of the SEMG signals was computed. The results showed that the spectrum area significantly increased during muscle fatigue. Therefore the area could be used as an assessor of muscle fatigue. Compared with the median frequency （MDF）--the most popular indicator of muscle fatigue, the spectrum area presented here showed higher sensitivity during a static contraction. So the singularity spectrum area is considered to be a more effective indicator than the MDF for estimating muscle fatigue.

关键词： Muscle fatigue Surface electromyographic (SEMG) signals Multifractal Static contraction

Mechanical Properties of Micro-regions in Cement-based Material based on the PeakForce QNM Mode of AFM

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Journal of Wuhan University of Technology(Materials Science) 2019年第4期34卷 893-899页

作者： ren mei SHI Tao College of Management Zhejiang University of Technology Hangzhou 310023China College of Civil Engineering and Architecture Zhejiang University of TechnologyHangzhou 310023China Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology of Zhejiang Province Hangzhou 310023China Department of Civil and Environmental Engineering Northwestern UniversityEvanstonIL 60208USA

In this paper, the cement paste and the mortar were tested using the PF-QNM technique. It is shown that the PF-QNM technique is very powerful to characterize the mechanical properties of micro-and nanostructures in the cement-based materials. It does not have strict requirements for test environment and it does not damage the surface of the material. High-resolution images can be obtained very easily, and they can be analyzed statistically. The test results show that PF-QNM analysis can test not only the mechanical properties of the cement paste, but also investigate the interfacial regions in the cement-based material, including the variation in the mechanical properties of interface regions and the extension of the interfacial regions. During the test, care must be taken to choose the size of test area;indeed, a test area too small is not representative but too large leads to lack of stability. The recommended side is a square with a length of in the range 10-30 μm.

关键词： PF-QNM peakforce tapping AFM cement pastes mortar Young's modulus interface micro-and nano-structure nanoindentation

HYDRAULIC CHARACTERIZATIONS OF TORTUOUS FLOW IN PATH DRIP IRRIGATION EMITTER

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Journal of Hydrodynamics 2006年第4期18卷 449-457页

作者： LI Yun-kai YANG Pei-ling ren Shu-mei XU Ting-wu College of Hydraulic and Civil Engineering China Agricultural University Beijing 100083 China International College at Beijing China Agricultural University Beijing 100083 China

At present, the tortuous emitter has the most advanced performances in drip irrigation. But the theories and methods for designing its flow path have been strictly confidential and the researches on the function of practical guidance have seldom been published. Seven types of most representative tortuous emitting-pipes currently used in agricultural irrigation regions of China were chosen for investigating the geometric parameters of the flow path by means of combining high-precision microscope and AutoCAD technology. By the measurement platform developed by the authors for hydraulic performances of emitters, the free discharge rates from the 7 types of emitters were measured at 9 pressure levels of 1.5 m, 3.0 m, 5.0 m, 7.0 m, 9.0 m, 10.0 m, 11.0 m, 13.0 m and 15.0 m. Then the discharge-pressure relationship, manufacturing variation coefficient, average velocity on the cross-section of flow path and the critical Reynolds number for the flow regime transformation within the paths were analyzed in detail. The results show that both pressure-ascending work pattern and pressure-descending work pattern have some impacts on the discharge rates of tortuous emitters, but the impact level is not significant. The target pressure could be approached by repetitive applications of the two work patterns during pressure regulation. The operation under low pressures has some impacts on the hydraulic performances of emitters, but the impact level is also not significant. The classical model of the discharge-pressure relationship is suitable for the pressure range of 1.5 m -15.0 m. The Reynolds number for fluids within the 7 types of tortuous emitters ranges from Re=105 to Re =930. The critical Reynolds number for the flow regime transformation is smaller than that for the routine dimension flow path. The variation coefficient of emitter discharge rates is slightly fluctuating around a certain value within the whole pressure range.

关键词： drip irrigation emitters tortuous flow pathhydraulic performances flow characteristics

Modeling for heterogeneous multi-stage information propagation networks and maximizing information

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Chinese Physics B 2019年第2期28卷 454-463页

作者： ren-Jie mei Li Ding Xu-Ming An Ping Hu School of Electrical Engineering and Automation Wuhan UniversityWuhan 430072China

In this paper, we propose a heterogeneous multi-stage model to study the effect of social reinforcement on information propagation. Both heterogeneity of network components and the heterogeneity of individual reinforcement thresholds are considered. An information outbreak condition is derived, according to which the outbreak scale and individual density of each state under specific propagation parameters can be deduced. Monte Carlo experiments are conducted in Facebook networks to demonstrate the outbreak condition, and we find that social reinforcement effects generally inhibit the propagation of information though it contributes to the emergence of certain hot spots simultaneously. Additionally, by applying Pontryagin's Maximum Principle, we derive the optimal control strategy in the case of limited control resources to maximize the information propagation. Then the forward–backward sweep method is utilized to verify its performance with numerical simulation.

关键词： heterogeneous network social reinforcement multi-stage optimal resource allocation

Hydrothermal Synthesis, Characterization and Catalytic Properties of Nanoporous MoO_ 3/ZrO_ 2 Mixed Oxide

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Chemical Research in Chinese Universities 2006年第3期22卷 364-367页

作者： SHI Wei LIU Hai-yan ren Dong-mei MA Zhuo SUN Wen-dong Faculty of Chemistry Northeast Normal University Changchun 130024 P. R. China

A nanoporous MoO3/ZrO2 mixed oxide was hydrothermally synthesized by hydrolyzing zirconium isopropoxide in the presence of a cationic surfactant, eetyltrimethylammonium bromide（CTAB）. The crystal structure and the acidity of the obtained nanoporous MoO3/ZrO2 mixed oxide were determined by means of XRD, N2 adsorption-desorption and NH3-TPD, respectively. The isobutane/butene alkylation over the MoO3/ZrO2 catalyst was carried out in a fixed bed reactor. The results reveal that ZrO2 in MoO3/ZrO2 exists mainly in the tetragonal phase, and the catalyst samples possess large specific surface areas as well as moderate acidity for isobutane/butene alkylation. Compared with samples prepared by impregnation and sol-gel processes, MoO3/ZrO2 mixed oxide samples prepared in this work have a better catalytic activity.

关键词： MoO3/ZrO2 Hydrothermal synthesis Solid acid catalyst Alkylation

Envelope Solitons Perturbed by Stochastic Noise

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Communications in Theoretical Physics 2009年第11期52卷 897-900页

作者： ren Xi-mei ZENG Shang-You ZHAO De-Jiang TANG Yi Faculty of Materials Optoelectronics and Physics Xiangtan University Xiangtan 411005 China

We perform langevin dynamics simulation for envelope solitons in an FPU-β lattice,with the nearestneighborinteraction and quartic *** get the motion equations of our discrete system by adding noiseand damping to the set of deterministic motion *** define'half-time'as the time when the amplitude of theenvelope soliton decreases by half due to *** then the mass,center and half-time of the perturbed envelopesoliton are numerically simulated,beginning with the discrete envelope soliton at *** show successfully hownoise affects behavior of the envelope soliton.

关键词： envelope soliton noise damping

First total synthesis of marine alkaloid hyrtiosulawesine

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Chinese Chemical Letters 2010年第11期21卷 1307-1309页

作者： Pu Yong Zhang Sheng Biao Wan Su mei ren Tao Jiang School of Medicine and Pharmacy Key Laboratory of Marine DrugsMinistry of EducationOcean University of ChinaQingdao 266003China

Hyrtiosulawesine was isolated from Indonesian specimens of the marine sponges Hyrtios erectus and *** in *** report here the first total synthesis of hyrtiosulawesine using an efficient and convenient synthetic strategy which could be widely used in the synthesis of otherβ-carboline *** structures of new compounds were confirmed by 1H NMR,13C NMR and HRMS.

关键词： β-Carboline Hyrtiosulawesine Pictet-Spengler reaction Tryptamine Total synthesis