Synthesis and properties of amino acid functionalized water-soluble perylene diimides

Yongshan Ma,Xuemei Li,Xiaofeng Wei,Tianyi Jiang,Junsen Wu,Huixue Ren 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.7

We prepared amino acid functionalized water-soluble perylene diimides: N,N'-bi(L-glutamic acid)-perylene- 3,4;9,10-dicarboxylic diimide (1), N,N'-bi(L-phenylalanine acid)-perylene-3,4;9,10-dicarboxylic diimide (2), N,N'-bi(Lglutamic amine)-perylene-3,4;9,10-dicarboxylic diimide (3) and N,N'-bi(L-phenylalanine amine)-perylene-3,4;9,10- dicarboxylic diimide (4). The structures of 3 and 4 were confirmed by 1H NMR, FT-IR and MS. The maximal absorption bands of compound 1 and 2 in concentrated sulfuric acid were red-shifted for about 48 and 74 nm, respectively, compared with that of Perylene-3,4,9,10-tetracarboxylic acid dianhydride (PTCDA). Nearly no fluorescence was observed for compounds 1 and 2 in water, while compounds 3 and 4 were significantly water-soluble and had very high fluorescent quantum. The mechanism of the optical properties change was discussed, and the π-π stacking caused by H+ led to the changes of fluorescence spectrum and absorption spectrum. The calculated molecular orbital energies and the frontier molecular orbital maps of compounds 1-2 based on density function theory (DFT) calculations were reported. Owing to the high water-soluble, the perylene derivatives 3 and 4 were successfully applied as high-performance fluorochromes for living hela cells imaging.

Approximate Optimal Stabilization Control of Servo Mechanisms based on Reinforcement Learning Scheme

Yongfeng Lv,Xuemei Ren,Shuangyi Hu,Hao Xu 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.10

A reinforcement learning (RL) based adaptive dynamic programming (ADP) is developed to learn the approximate optimal stabilization input of the servo mechanisms, where the unknown system dynamics are approximated with a three-ayer neural network (NN) identifier. First, the servo mechanism model is constructed and a three-layer NN identifier is used to approximate the unknown servo system. The NN weights of both the hidden layer and output layer are synchronously tuned with an adaptive gradient law. An RL-based critic three-layer NN is then used to learn the optimal cost function, where NN weights of the first layer are set as constants, NN weights of the second layer are updated by minimizing the squared Hamilton-Jacobi-Bellman (HJB) error. The optimal stabilization input of the servomechanism is obtained based on the three-layer NN identifier and RL-based critic NN scheme, which can stabilize the motor speed from its initial value to the given value. Moreover, the convergence analysis of the identifier and RL-based critic NN is proved, the stability of the cost function with the proposed optimal input is analyzed. Finally, a servo mechanism model and a complex system are provided to verify the correctness of the proposed methods.

Modeling and Control of a New Spherical Robot with Cable Transmission

Lufeng Zhang,Xuemei Ren,Dongdong Zheng 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.3

This paper presents a new spherical robot with a cable transmission mechanism. Cable transmission mechanism replaces conventional gear train to eliminate the influence of gear backlash, reduce the robot mass, lower the costs on mechanical customization and can be arranged flexibly. By projection method, the 3D robot dynamic model with structural asymmetry is decoupled into balance subsystem and velocity subsystem, and the kinetics equations are established based on Newton-Euler’s law. For the balance control, an adaptive law is designed to estimate the upper bound instead of the exact value of the uncertainty caused by the structural asymmetry online firstly, then a finite-time adaptive hierarchical sliding mode control (FAHSMC) strategy is proposed based on the estimation result to minimize the convergence time. For the velocity control, a hierarchical sliding mode controller (HSMC) and a tracking differentiator (TD)-based nonlinear disturbance observer are designed, leading to enhanced disturbance rejection capability and a reduced steady-state error. Simulations and experiments on a real spherical robot are conducted to demonstrate the efficacy of the proposed control strategies.

Disturbance Observer-based Finite-time Optimal Synchronization Control for Multi-motor Driving Servo Systems

Shuangyi Hu,Xuemei Ren,Dongdong Zheng 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.1

In this paper, a disturbance observer-based finite-time optimal synchronization control strategy is proposed with an adaptive bias torque for multi-motor driving servo systems. Finite time disturbance observers are designed to estimate the system nonlinearity and external disturbance, which ensure the finite time convergence of observation errors. Meanwhile a virtual tracking control input is designed to guarantee the output tracking of the load subsystem and a generalized synchronization error is obtained for the motor subsystem. Based on the synchronization error system, an auxiliary exponential function with finite-time convergence property is introduced to obtain the sufficient conditions for optimal synchronization control, which avoids solving the complex HamiltonJacobi-Bellman function. Simulation and experimental results reveal the flexibility of the proposed control scheme.

Polyamidoxime functionalized with phosphate groups by plasma technique for effective U(VI) adsorption

Dadong Shao,Xiaolin Wang,Xuemei Ren,Sheng Hu,Jun Wen,Zhaoyi Tan,Jie Xiong,Abdullah M. Asiri,Hadi M. Marwani 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.67 No.-

Finding poly(amidoxime) (PAO) based adsorbent with better performance in U(VI) extraction from seawater is a hot research topic. By employing plasma treatment, the bi-functionalized adsorbents containing amidoxime and phosphate (labelled as PO4/PAO) were successfully synthesized. The obtained PO4/PAO was characterized and applied for the potential extraction of U(VI) from aqueous solution. The results show that −PO4 enhanced the hydrophilicity of PAO. PO4/PAO possesses good selective sorption ability for U(VI) and excellent reusability. The findings is helpful to understand optimizing performance of PAO based adsorbents for uranium extraction from seawater.

Study on complex flow law near polymer flooding wellbores and adaptability evaluation of shaped charges

Jianguang Wei,Xidong Ren,Hongyan Shao,Yuanyuan Ma,Xuemei Liu,Xuesong Lin 한국자원공학회 2016 Geosystem engineering Vol.19 No.5

The flow law near polymer flooding wellbores under the condition of perforation is very complex and there are many types of shaped charges. In this study, a non-Darcy flow model near polymer flooding wellbores was given, and a flow experiment was carried out to measure the resistance coefficient, residual resistance coefficient, and flow viscosity of the polymer solution in porous media under the conditions of different permeability and different polymer molecular weight. According to the results of numerical simulation, this paper calculated the flow efficiency of different types of shaped charges and evaluated the adaptability of different charges under polymer flooding condition. The results of this study have an important significance for guiding the optimization of shaped charges and the optimization design of perforating parameters.

Experimental study of TiO2 hollow microspheres removal on elemental mercury in simulated flue gas

Jiang Wu,Xian Li,Jian-Xing Ren,Xuemei Qi,Ping He,Bu Ni,Chong Zhang,Chengzhen Hu,Jun Zhou 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.32 No.-

TiO2 hollow sphere was synthesized by hydrothermal method using trifluoroacetic acid (TFA) andTi(SO4)2 as raw materials, and it was applied to photocatalytic oxidization of elemental mercury (Hg0) inthe simulated flue gas. The prepared samples were well characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectronspectroscopy (XPS), UV–vis diffuse reflectance spectra (UV-vis DRS) and nitrogen adsorption/desorption. The results showed that only anatase phase TiO2 hollow sphere was obtained. The average diameter ofTiO2 hollow spheres was about 800 nm and the shell thickness was about 200–400 nm. When M, themolar ratio of TFA to Ti(SO4)2, was higher than a certain value, the photocatalytic activity of preparedTiO2 hollow spheres began to reduce. When M = 2, addition TFA content was the best quantity, which gotthe best TiO2 hollow spheres and provided the most appropriate F decomposed from TFA during thesample preparation, which was helpful to its photocatalytic ability. In the experimental temperaturerange, the photocatalytic oxidation efficiency decreased with the increasing of reaction temperature, andthe intensity of UV irradiation had an important effect on the photocatalytic reaction. When UVirradiation intensity was 303.45 mW cm 2 and reaction temperature was 55 8C, TiO2 hollow spheresample prepared at M = 2 had the highest photocatalytic ability and the mercury removal efficiencyreached up to 82.75%.

Adaptive Parameter Identification for Nonlinear Sandwich Systems with Hysteresis Nonlinearity Based Guaranteed Performance

Linwei Li,Huanlong Zhang,Fengxian Wang,Xuemei Ren 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.2

The paper presents an adaptive identification algorithm via data filtering and improved prescribed performance function for Sandwich systems with hysteresis nonlinearity. By developing a filter in which the filter is simple and easy to realize online and several variables, the estimation error vector can be derived. To improve the transient performance of estimator, a modified prescribed performance function is proposed to constrain the estimation error data through the usage of the predefined domain. For the constrained estimation error condition, the error transformation technique is utilized to simplify the design of the estimator thanks to that the restricted condition is transformed into unconstrained condition. To achieve the convergence of the parameter estimation and assure the predetermined property, a fresh adaptive law is developed. Moreover, the theoretical analysis indicates that the error can converge to a small region based on martingale difference theorem. According to the numerical verification and experimental results, the advantage and practicability of the invented estimator are inspected by comparing the estimators with unconstrained condition.