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Preparation of PLGA Microspheres with Different Porous Morphologies

Chinese Journal of Polymer Science 2015年第1期33卷 128-136页

作者： Shu-ying Wang Xu-dong shi 甘志华王峰 State Key Laboratory of Chemical Resource Engineering Beijing Key Laboratory of Electrochemical Process and Technology for Materials Beijing University of Chemical Technology Institute of Chemistry Chinese Academy of Science State Key Laboratory of Organic-inorganic Composites Beijing Laboratory of Biomedical Materials Beijing University of Chemical Technology

Poly（D,L-lactide-co-glycolide）（PLGA） microspheres were prepared by emulsion solvent evaporation method. The influences of inner aqueous phase, organic solvent, PLGA concentration on the morphology of microspheres were studied. The results showed that addition of porogen or surfactants to the inner aqueous phase, types of organic solvents and polymer concentration affected greatly the microsphere morphology. When dichloromethane was adopted as organic solvent, microspheres with porous structure were produced. When ethyl acetate served as organic solvent, two different morphologies were obtained. One was hollow microspheres with thin porous shell under a lower PLGA concentration, another was erythrocyte-like microspheres under a higher PLGA concentration. Three types of microspheres including porous, hollow core with thin porous shell（denoted by hollow in brief） and solid structures were finally selected for in vitro drug release tests. Bovine serum albumin（BSA） was chosen as model drug and encapsulated within the microspheres. The BSA encapsulation efficiency of porous, hollow and solid microspheres was respectively 90.4%, 79.8% and 0. And the ultimate accumulative release was respectively 74.5%, 58.9% and 0. The release rate of porous microspheres was much slower than that of hollow microspheres. The experiment results indicated that microspheres with different porous structures showed great potentials in controlling drug release behavior.

关键词： PLGA Porous microsphere Morphology BSA Tissue engineering.

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Removal of phenol by activated alumina bed in pulsed high-voltage electric field

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Journal of Environmental Sciences 2007年第4期19卷 409-415页

作者： ZHU Li-nan MA Jun YANG shi-dong School of Municipal and Environmental Engineering Harbin Institute of Technology Harbin 150090 China

A new process for removing the pollutants in aqueous solution-activated alumina bed in pulsed high-voltage electric field was investigated for the removal of phenol under different conditions. The experimental results indicated the increase in removal rate with increasing applied voltage, increasing pH value of the solution, aeration, and adding Fe^2＋. The removal rate of phenol could reach 72.1% when air aeration flow rate was 1200 ml/min, and 88.2% when 0.05 mmol/L Fe^2＋ was added into the solution under the conditions of applied voltage 25 kV, initial phenol concentration of 5 mg/L, and initial pH value 5.5. The addition of sodium carbonate reduced the phenol removal rate. In the pulsed high-voltage electric field, local discharge occurred at the surface of activated alumina, which promoted phenol degradation in the thin water film. At the same time, the space-time distribution of gas-liquid phases was more uniform and the contact areas of the activated species generated from the discharge and the pollutant molecules were much wider due to the effect of the activated alumina bed. The synthetical effects of the pulsed high-voltage electric field and the activated alumina particles accelerated phenol degradation.

关键词： pulsed high-voltage electric field hybrid gas-liquid electrical discharge activated alumina phenol Fenton's reaction water treatment

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Numerical simulation of climate response to ultraviolet irradiation forcing

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Advances in Climate Change Research 2019年第3期10卷 133-142页

作者： XIAO Zi-Niu dong shi ZHONG Qi State Key Laboratory o f Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute o f Atmospheric PhysicsChinese Academy of SciencesBeijing100029China China Meteorological Administration Training Centre China Meteorological AdministrationBeijing100081China

Using the Whole Atmosphere Community Climate Model, sensitivity experiments are performed to identify the climate response to ultra violet (UV) irradiation forcing. In the experiment, total solar irradiance (TSI) and solar spectral irradiation (SSI) are adopted as solar input from the dataset (1610 2009) reconstructed by Lean. Results show that UV variability has a strong impact on the middle atmosphere. Ozone (0 3) distribution in the atmosphere is sensitive to UV irradiation variability. When UV irradiation is enhanced, the 0 3 content increases at altitudes from 30 km to 60 km and decreases at altitudes from 15 km to 30 km. The atmospheric temperature appears positive anomaly below the mesosphere. Anomalous warmth develops above 35 km with maximum warming anomaly apparent at the stratopause, consistent with the at mospheric distribution of 0 3, which indicates that the ozone heating mechanism plays an important role in wanning. The 0 3 and temperature respond in an opposite manner when the UV irradiation is reduced. Furthermore, the stronger UV forcing leads to a change in the temperature distribution because of the 0 3 heating mechanism. This condition then modulates the zonal wind in the stratosphere and upper troposphere. Although the tropospheric response is weak on a global scale, a notable local response occurs over mid high latitudes in the Northern Hemisphere (NH) during winter. Along with the enhanced zonal wind in the lower stratosphere near the North Pole, the positive phase of the Arctic Oscillation pattern appears over the NH, which causes a temperature increase over mid-latitude Asia. Finally, the behavior evident in the reanalysis data is compared with the results of the numerical experiments. The similar structure of the response fields means the results of simulation experiment is credible to some extent.

关键词： Ultraviolet Ozone Climate variability Numerical simulation

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Micro mechanical properties of n-Al2O3/Ni composite coating by nanoindentation

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中国有色金属学会会刊：英文版 2004年第z1期14卷 115-119页

作者： WANG Hong-mei XU Bin-shi MA shi-ning dong shi-yun LI Xiao-ying National Key Laboratory for Remanufacturing Academy of Armored Force Engineering Beijing 100072 China National Key Laboratory for RemanufacturingAcademy of Armored Force Engineering Beijing 100072 China National Key Laboratory for RemanufacturingAcademy of Armored Force Engineering Beijing 100072 China National Key Laboratory for RemanufacturingAcademy of Armored Force Engineering Beijing 100072 China School of Metallurgy and Materials The University of Birmingham Birmingham B152TT UK

A new type of nano test system was introduced, the test principle and the indentation data analysis method were described. It was used to test the micro mechanical properties, such as hardness, elastic modulus and indentation creep property of n-Al2O3/Ni composite coating on steel prepared by brush plating, and the variety of mechanical properties with coating thickness was researched. The results show that the mechanical properties are basically identical within the whole coating, the hardness and modulus decrease in the defect fields, especially within the dendritic crystals, whereas the mechanical properties are not influenced greatly at the interspaces among dendritic crystals. The average hardness and elastic modulus of n-Al2O3/Ni coating are 6.34 GPa and 154 GPa respectively, and the hardness is 2.4 times higher than that of steel and the indentation creep curve of n-Al2O3/Ni coating is similar to that of the uniaxial compression creep, and the creep rate of steady-state is about 0. 104 nm/s. These results will supply useful data for process improvement, new type material development and application expansion.

关键词： nanoindentation hardness elastic modulus creep property nano composite coating

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Preparation of Porous Polylactide Microspheres and Their Application in Tissue Engineering

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Chinese Journal of Polymer Science 2018年第6期36卷 712-719页

作者： Xu-dong shi Pei-Jian Sun Zhi-Hua Gan Key Laboratory of Polymer Ecomaterials Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China The GAS Key Laboratory of Engineering Plastics Institute of ChemistryChinese Academy of Sciences(CAS)Beijing 100190China State Key Laboratory of Organic-inorganic Composites College of Life Science and TechnologyBeijing University of Chemical TechnologyBeijing 100029China

In this study, porous polylactide（PLA） microspheres with different structures were prepared through the multiple emulsion solvent evaporation method. By changing organic solvents（ethyl acetate and chloroform） and adding effervescent salt NH4 HCO3 in the inner water phase, microspheres with porous capsular, matrix, microcapsular and multivesicular structures were prepared. The protein encapsulation and release, and the cell growth behavior of porous microspheres were further explored. Under the same inner water phase, microspheres prepared with chloroform had higher protein encapsulation efficiency and less protein release rate as compared with those prepared with ethyl acetate. Cell experiments showed that the relatively rough surface of microspheres prepared with chloroform was more favorable for the cell growth in comparison with the smooth surface of microspheres prepared with ethyl acetate. This study shows a simple and effective method to control the protein release and cell growth behaviors of polymer microspheres by tuning their porous structure.

关键词： Polylactide Porous microspheres Drug release Cell Tissue engineering

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Simulation and analysis of co-phasing errors of the segmented primary mirror tiled by hexagonal segments in LOT

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Research in Astronomy and Astrophysics 2021年第10期21卷 37-45页

作者： shi-dong Shen Xiang-Qun Cui Yong Zhang National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology Chinese Academy of SciencesNanjing 210042China CAS Key Laboratory of Astronomical Optics&Technology Nanjing Institute of Astronomical Optics&TechnologyNanjing 210042China University of the Chinese Academy of Sciences Beijing 100049China

In this paper,co-phasing errors of a segmented primary mirror tiled by hexagonal segments are successfully calculated for the 12-meter Large aperture Optical/infrared Telescope(LOT).Co-phasing errors including out-of-plane errors are simulated separately and comprehensively based on several software simulation *** simulation results show that the Strehl Ratio(SR)of LOT is larger than 0.8 when the RMS value of tip-tilt obeying a normal distribution is less than 0.018 arcsec,and the SR of LOT is larger than 0.8 when the RMS value of piston obeying a normal distribution is less than 40 ***,simulation results of Zemax show that the SR of LOT is larger than 0.8 when the RMS value of tip-tilt obeying a normal distribution is less than 0.02 arcsec,and the SR of LOT is larger than 0.8 when the RMS value of piston obeying a normal distribution is less than 40 *** simulation results successfully lay a solid foundation for LOT(especially the segmented primary mirror with active optics).

关键词： methods:analytical techniques:miscellaneous telescopes

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Adaptive triangular mesh coarsening with centroidal Voronoi tessellations

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第4期10卷 535-545页

作者： Zhen-yu SHU Guo-zhao WANG Chen-shi dong Institute of Computer Graphics and lmage Processing Department of Mathematics Zhejiang University Hangzhou 310027 China Laboratory of Information and Optimization Technologies Ningbo Institute of Technology Zhejiang University Ningbo 315100 China

We present a novel algorithm for adaptive triangular mesh coarsening. The algorithm has two stages. First, the input triangular mesh is refined by iteratively applying the adaptive subdivision operator that performs a so-called red-green split. Second, the refined mesh is simplified by a clustering algorithm based on centroidal Voronoi tessellations (CVTs). The accuracy and good quality of the output triangular mesh are achieved by combining adaptive subdivision and the CVTs technique. Test results showed the mesh coarsening scheme to be robust and effective. Examples are shown that validate the method.

关键词： Triangular mesh Mesh coarsening Surface subdivision Centroidal Voronoi tessellations (CVTs)

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Initial pre-stress finding procedure and structural performance research for Levy cable dome based on linear adjustment theory

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第9期8卷 1366-1372页

作者： ZHANG Li-mei CHEN Wu-jun dong shi-lin Space Structures Research Center Shanghai Jiao Tong University Shanghai 200030 China

The cable-strut structural system is statically and kinematically indeterminate. The initial pre-stress is a key factor for determining the shape and load carrying capacity. A new numerical algorithm is presented herein for the initial pre-stress finding procedure of complete cable-strut assembly. This method is based on the linear adjustment theory and does not take into account the material behavior. By using this method,the initial pre-stress of the multi self-stress modes can be found easily and the cal-culation process is simplified and efficient also. Finally,the initial pre-stress and structural performances of a particular Levy cable dome are analyzed comprehensively. The algorithm has proven to be efficient and correct,and the numerical results are valuable for practical design of Levy cable dome.

关键词： Linear adjustment theory Cable-strut structure Initial pre-stress Levy cable dome Structural performances analysis

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Cuttings transport: Back reaming analysis based on a coupled layering-sliding mesh method via CFD

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Petroleum Science 2023年第6期20卷 3673-3686页

作者： Na Zhu shi-dong Ding Xiao-Lei shi Wen-Jun Huang De-Li Gao MOE Key Laboratory of Petroleum Engineering China University of PetroleumBeijing102249China SINOPEC Research Institute of Petroleum Engineering Co.Ltd No.197 Baisha RoadChangping DistrictBeijing102206China

Inadequate hole cleaning is one of the main reasons for inefficient operations in extended-reach *** mechanism of cuttings transport under the back reaming operation,which is frequently adopted to remove the cuttings,has been investigated in this *** this end,a coupled layering-sliding mesh method with the Eulerian-Granular approach has been established *** dynamic layering method has been employed to simulate the axial motion of the pipe,whereas the sliding mesh method has been used to simulate the pipe *** back reaming operation of a connector-furnished pipe has been simulated,and the sensitive parameter analysis has been *** results thus obtained demonstrate that the increase in the initial bed height,inclination,and the diameter and length of the connector causes a significant increase in the cuttings *** addition,the cuttings concentration is observed to decrease significantly with the pipe rotation ***,two main factors contribute towards the cuttings accumulation around the connector,namely,the difference in the cross-sectional area and the pushing effect of the connector—like a“bulldozer”.The“bulldozer”effect of the connector dominates when the tripping velocity is significant compared to the velocity of the ***,the effect of the difference in the cross-sectional area becomes the leading factor for cuttings ***“bulldozer”effect of the connector causes a more severe impact on hole *** both cases,increasing the tripping velocity only mildly affects the cuttings *** is therefore suggested that the tripping velocity should be slower than that of the sand during the back reaming ***,increased fluid velocity might lead to a higher accumulated cuttings concentration around the connector when the cuttings bed has not entirely passed through the connector.A significant flow rate can be safely applied after the cuttings have passe

关键词： Drill cuttings transport Back reaming Layering-sliding mesh Hole cleaning Connector

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Feedback Stabilization for a Class of Second Order Singular Distributed Parameter System in Hilbert Space

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Acta Mathematicae Applicatae Sinica 2015年第1期31卷 89-100页

作者： Feng LIU Guo-dong shi Zhao-qiang GE School of Mathematics and Physics Jiangsu University of Technology School of Information Science and Engineering Changzhou University Department of Applied Mathematics Xi’an Jiaotong University

Feedback stabilization for a class of second order singular distributed parameter system with multi- inputs is discussed via functional analysis and operator theory in Hilbert space, the solutions of the problem and the constructive expressions of the solutions are given by the generalized inverse of bounded linear operator. This research is theoretically important for studying the stability of the singular distributed parameter system.

关键词： feedback stabilization second order singular distributed parameter system multi-inputs Hilbert space

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