Electrospun Hemocompatible PU/ Gelatin-Heparin Nanofibrous Bilayer Scaffolds as Potential Artificial Blood Vessels

Heyun Wang,Jintang Guo,Yakai Feng,Haiyang Zhao,Ruofang Xiao,Jian Lu,Li Zhang 한국고분자학회 2012 Macromolecular Research Vol.20 No.4

Fabrication and Characterization of Electrospun Gelatin-Heparin Nanofibers as Vascular Tissue Engineering

Heyun Wang,Yakai Feng,Zichen Fang,Ruofang Xiao,Wenjie Yuan,Musammir Khan 한국고분자학회 2013 Macromolecular Research Vol.21 No.8

In this paper, heparin was introduced into electrospun gelatin nanofibrous scaffold for assessment as a controlled delivery device in vascular tissue engineering application. Hybrid gelatin-heparin fibers with smooth surfaces and no bead defects were produced from gelatin solutions with 18% w/v in acetic acid aqueous solution. A significant decrease in fiber diameter was observed when the heparin content was increased from 1 to 5 wt%. The properties of composite gelatin-heparin scaffolds were confirmed by Fourier transform infrared spectroscopy (FTIR)and differential scanning calorimetry (DSC) measurement. The gelatin-heparin fibrous scaffolds were also cross-linked using 1 wt% glutaraldehyde vapor-phase for 7 days. A sustained release of heparin could be achieved from gelatinheparin scaffolds over 14 days. The results of the biocompatibility in vitro tests carried out using human umbilical vein endothelial cells indicated good cell viability and proliferation on the gelatin-heparin scaffolds. The results demonstrated that the use of electrospun gelatin fibers as heparin carriers could be promising for vascular tissue applications.

Selective Protection Miniature Circuit Breaker Electromagnetic Actuator Design and Dynamic Optimization

Xianbing Wang,Heyun Lin,Shuhua Fang,Xiangao Wang,Jin Peng 한국자기학회 2019 Journal of Magnetics Vol.24 No.4

This paper first proposes an electromagnetic actuator design and dynamic optimization method for selective miniature circuit breaker (SMCB), and realizes good coordination of electromagnetic actuator force and energy characteristics. Based on short delay tripping mechanism force and magnetic field model, it builds Matlab and Adams co-simulation platform, simulates and analyzes the magnetic field distribution and force energy property under different electromagnetic topological structure, and establishes the permanent magnet electromagnetic structure model. Then, it builds multi-field coupled mathematical model, and studies multi-objective dynamic optimization design for electromagnetic actuator based on quantum particle swarm algorithm. Finally, it develops the 100A miniature circuit breaker. The experimental results show that the optimized electromagnetic actuator design can effectively control the miniature circuit breaker tripping action threshold and mechanical characteristics.

Contact Parameter Computation and Analysis of Air Circuit Breaker with Permanent Magnet Actuator

Shuhua Fang,Heyun Lin,S. L. Ho,Xianbing Wang,Ping Jin,Yunkai Huang,Shiyou Yang 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.3

An air circuit breaker (ACB) with novel double-breaker contact and permanent magnet actuator (PMA) is presented. Three-dimensional (3-D) finite element method (FEM) is employed to compute the electro-dynamic repulsion forces, including the Holm force and Lorentz force, which are acting on the static and movable contacts. The electro-dynamic repulsion forces of different contact pieces are computed, illustrating there is an optimal number of contact pieces for the ACB being studied. The electro-dynamic repulsion force of each contact, which varies from the outer position to the inner position, is also computed. Finally, the contacts of the double-breaker are manufactured according to the analyzed results to validate the simulations.

Contact Parameter Computation and Analysis of Air Circuit Breaker with Permanent Magnet Actuator

Fang, Shuhua,Lin, Heyun,Ho, S.L.,Wang, Xianbing,Jin, Ping,Huang, Yunkai,Yang, Shiyou The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.3

An air circuit breaker (ACB) with novel double-breaker contact and permanent magnet actuator (PMA) is presented. Three-dimensional (3-D) finite element method (FEM) is employed to compute the electro-dynamic repulsion forces, including the Holm force and Lorentz force, which are acting on the static and movable contacts. The electro-dynamic repulsion forces of different contact pieces are computed, illustrating there is an optimal number of contact pieces for the ACB being studied. The electro-dynamic repulsion force of each contact, which varies from the outer position to the inner position, is also computed. Finally, the contacts of the double-breaker are manufactured according to the analyzed results to validate the simulations.

Structurally ordered nanofiltration membranes prepared by spatially anchoring interfacial polymerization for highly efficient separation properties

Ao Sheng,Hao Wang,Haoji Jiang,Yaxin Zhao,Hao Li,Hao Jia,Zhong Wei,Heyun Wang 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.9

The incorporation of various nanofillers into the interfacial polymerization (IP) process is widely applied to prepare higher performance NF membranes. However, few studies have reported the influence of nanofillers on nanocomposite membrane formation in the IP process. Here, an optical microscope was employed to study the change rule in the 8-NH2-POSS/PSA nanocomposite membrane formation process due to the addition of 8-NH2-POSS nanoparticles. First, the addition of 8-NH2-POSS reduced the diffusion rate of the polyacrylamide hydrochloride (PAH) water phase on the surface against the oil phase because of the interaction with the PAH molecules. Furthermore, the 8-NH2- POSS/PSA nanocomposite membrane structure was more homogeneous and exhibited uniform pinhole defects distribution due to the interaction of the 8-NH2-POSS nanoparticles to the PAH segment. A significant separation performance was observed in the 8-NH2-POSS/PSA nanocomposite membrane due to the hydrophilicity and positive charge of the 8-NH2-POSS nanoparticles. The permeation flux and MgCl2 rejection of the 8-NH2-POSS/PSA nanocomposite membrane increased up to 50.5 L/m2 h at 0.5MPa and 94.8%, respectively, which corresponded to increases of 73.5% and 8.7% as compared to the pristine PSA membrane. 8-NH2-POSS/PSA nanocomposite membranes have great application potential in the water softening and treatment of divalent metals ions under acidic conditions.

Immobilized Bioactive Agents onto Polyurethane Surface with Heparin and Phosphorylcholine Group

Mingqi Tan,Yakai Feng,Heyun Wang,Li Zhang,Musammir Khan,Jintang Guo,Qingliang Chen,Jianshi Liu 한국고분자학회 2013 Macromolecular Research Vol.21 No.5

Heparin (HEP) and phosphorylcholine groups (PC) were grafted onto the polyurethane (PU) surface in order to improve biocompatibility and anticoagulant activity. After the surface grafting sites of PU were amplified with the primary amine groups of polyethylenimine (PEI), heparin was covalently linked onto the surface by the reaction between the amino group and the carboxyl group. PC groups were covalently immobilized on the PU-PEI surface through the reaction between the amino group and the aldehyde group of phosphorylcholine glyceraldehyde (PCGA). The surface density of primary amine groups was determined by a ninhydrin assay. The amino group density reached a maximum of 0.88 μmol/cm2 upon incorporation of 10 wt% PEI. The amount of heparin covalently immobilized on the PU-PEI surface was determined by the toluidine blue method. The grafting chemistry resulted in the comparatively dense immobilization of HEP (2.6 μg/cm2) and PC to the PU-PEI surfaces. The HEP and PC modified surfaces were characterized by water uptake (PU 0.15 mg/cm2, PU-PEI 3.54 mg/cm2, PU-HEP 2.04 mg/cm2, PU-PC 2.38 mg/cm2), water contact angle (PU 95.3º, PU-PEI 34.0º, PU-HEP 39.5º, PU-PC 37.2º), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS),atomic force microscopy (AFM), and scanning electron microscope (SEM). The results demonstrated that the PUPEI surface was successfully grafted with HEP and PC. The hydrophilicity and hemocompatibility of these grafted surfaces were significantly improved. These results suggested that the PU-HEP and PU-PC composite films are promising candidates for blood contacting tissue engineering.

Kinetics of Sn(Oct)2-Catalyzed Ring Opening Polymerization of ε-Caprolactone

Dan Wu,Yin Lv,Rui Guo,Jiahui Li,Aerman Habadati,Bowen Lu,Heyun Wang,Zhong Wei 한국고분자학회 2017 Macromolecular Research Vol.25 No.11

To evaluate the effects of different alcohols (primary, secondary, and two different tertiary alcohols) as initiators on the structure of polycaprolactone (PCL) in ring-opening polymerization (ROP), four experiments were conducted in toluene with tin(II) 2-ethylhexanoate (Sn(Oct)2) as the catalyst. The kinetics of ε-caprolactone (ε-CL) ROP at different temperatures and monomer concentrations were studied with n-butanol as the initiator and Sn(Oct)2 as the catalyst. The kinetic plot of ln(M0/Mt) vs. time (t) seems a linear, which indicates that the propagation rate is in the first order with respect to monomer concentration. When the reaction temperature increased, the reaction rate and the final relative maximum monomer conversions also increased. The molecular weight of PCL initially increased and then decreased as monomer conversion increased. This behavior can be attributed to the high viscosity of the system, which affected monomer diffusion and polymer chain propagation. In addition, prolonging reaction time caused inter-/intramolecular transesterification. However, when monomer concentration decreased, the reaction rate decreased. The actual activation energy of Sn(Oct)2-catalyzed ROP of ε-CL in toluene was -75 kJ/mol.