Papers by Author: H. Sun

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Authors: Jin Wang, P. Li, H. Sun, Ping Yang, Y.X. Leng, Ji Yong Chen, Nan Huang
Abstract: We report a study involving chitosan chains immobilized on poly (ethylene terephthalate) (PET) films by plasma and ultraviolet (UV) grafting modification. The surface structure of the modified PET is determined by means of attenuated total reflection Fourier transform infraed spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The results show that the chains of chitosan are successfully grafted on the surface of PET. Platelet adhesion evaluation in vitro is conducted to examine the blood compatibility in vitro. Scanning electron microscopy (SEM) and optical microscopy reveal that the amounts of adhered, aggregated and morphologically changed platelets are reduced on the chitosan-immobilized PET films. The number of platelet adhered on the modified film is reduced by almost 48% compared to the amount of platelets on the untreated film. Our result thus shows that chitosan immobilized on the PET surface improves blood compatibility.
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Authors: Ji Liang Mo, Min Hao Zhu, J. An, H. Sun, Yong Xiang Leng, Nan Huang
Abstract: CrN coatings were deposited on cemented carbide substrates by filtered cathodic vacuum arc technique (FCVA). The effect of different deposition parameters: nitrogen partial pressure, substrate-bias voltage and preheating of the substrate, on the structural and mechanical properties of the coating was investigated. X-ray diffraction analysis was used to determine the structure and composition of the coatings. The tribological behaviour and wear properties of the coatings against Si3N4 ball at different normal loads were studied under reciprocating sliding condition. The results showed that a smooth and dense CrN coating with good properties can be obtained provided a pure Cr interlayer was pre-deposited. The optimal deposition parameters were the nitrogen partial pressure of 0.1 Pa, substrate-bias voltage of -100 V. Preheating of the substrate was no good for improving the properties of the coating. The FCVA CrN coating showed high hardness and good wear resistance, which was probably attributed to its smooth surface and dense microstructure. The wear mechanism of the CrN coating was a combination of abrasion and oxidation. However, the coating flaked off at high normal load due to the deficient adhesion strength of the coating to the substrate.
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Authors: Chang Jiang Pan, Jin Wang, H. Sun, Nan Huang
Abstract: In this paper, polyethylene glycol (PEG) of various different molecular weights was grafted onto PET films using plasma surface grafting modification. The surface structure of PEG-grafted PET films was analyzed by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS), suggesting that the surface structure and composition of PET films changes due to the presence of PEG. Blood compatibility was characterized by in vitro platelet adhesion experiments and coagulation factors. The tests of platelet adhesion and coagulation factors in vitro suggest that PEG grafted onto polymer surfaces can improve the blood compatibility of PET films remarkably. The modified PET films were pre-coated with albumin and fibrinogen respectively; platelet adhesion tests in vitro then indicated that samples pre-coated with albumin have better blood compatibility than with fibrinogen, resulting in the conclusion that the albumin can improve blood compatibility. The contact angle of PEG-grafted films was measured by the sessile drop method and the surface free energy and interface free energy were induced. It is indicated that the PEG-grafted PET films have the characteristic of preferentially adsorbing albumin.
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Authors: Feng Juan Jing, Nan Huang, Jun Ying Chen, Yong Xiang Leng, H. Sun
Abstract: Aminopropyltriethoxysilane (APTE) was covalently interacted with hydroxyl on the surface of Ti-O films prepared by magnetron sputtering, and albumin and heparin were immobilized on the APTE-coated surface with addition of 1-ethyl-3- (3-dimethyl aminopropyl) carbodiimide (EDC) as cross-link agent. X-ray photoelectron spectroscopy (XPS) was used to investigate the modified surface. Contact angle results indicate that there was an increase in the contact angle to the surface of APTE-coated Ti-O films, and a decrease in the contact angle to the surface of albuminand heparin-immobilized surfaces. Blood platelet adhesion in vitro was improved significantly after immobilization of albumin and heparin on Ti-O films. Endothelial cell (EC) culture tests showed that EC could grow on the surface of Ti-O films immobilized with albumin and heparin, but the growth and proliferation behavior of endothelial cells was not as good as on naked Ti-O films. This investigation showed that the surface of bio-inert inorganic materials immobilized with biological molecules is feasible and effective for improving the blood compatibility.
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Authors: Jun Ying Chen, Yong Xiang Leng, Sh.N. Ge, Ping Yang, Jin Wang, H. Sun, Guo Jiang Wan, An Sha Zhao, Nan Huang
Abstract: In the work reported here, titanium oxide film were synthesized using magnetron sputtering from a high-purity Ti metal target while sustaining a differential oxygen partial pressure of from 0.02 to 0.30 Pa. The biological behavior of endothelial cells grown on the film surface was studied by in vitro human umbilical vein endothelial cell (HUVEC) culture investigation. Our studies revealed that the adherence, growth, and proliferation of endothelial cells on different Ti-O film surfaces were strongly affected by the oxygen partial pressure. The biocompatibility mechanisms of ECs on Ti-O film surfaces were explored using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), a-step profilometry, scanning electron microscopy (SEM), and atomic force microscopy (AFM). We conclude that the various film characteristics such as structure, composition and surface morphology due to the different oxygen partial pressures significantly influence the biological behavior of EC.
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Authors: H. Sun, R.C. Woodward, R. Street
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Authors: Yan Wei Zhao, B. Wu, W.L. Wang, Ying Li Ma, W.A. Wang, H. Sun
Abstract: The investigation of the performance of the Particle Swarm Optimization (PSO) method for Vehicle Routing Problem with Time Windows is the main theme of the paper. “Exchange minus operator” is constructed to compute particle’s velocity. We use Saving algorithm, Nearest Neighbor algorithm, and Solomon insertion heuristics for parameter initialization and apply the “Routing first and Cluster second” strategy for solution generation. By PSO, customers are sorted in an ordered sequence for vehicle assignment and Nearest Neighbor algorithm is used to optimize every vehicle route. In our experiments, two different PSO algorithms (global and local), and three construct algorithms are investigated for omparison. Computational results show that global PSO algorithm with Solomon insertion heuristics is more efficiency than the others.
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Authors: Feng Wen, Nan Huang, H. Sun, Ping Yang, Jin Wang
Abstract: Amorphous hydrogenated carbon (a-C:H) thin films were deposited on silicon wafers and Ti6Al4V substrate using plasma ion immersion implantation and deposition (PIII-D) at room temperature (R.T.). The composition and structure of a-C:H films were employed by X-ray photoelectron spectra (XPS) and Raman spectra. Nano-indenter tests measured the hardness of the films. In addition, wettability and bloodcompatibility were investigated. In this paper, the effects of hydrogen content on structure, mechanical properties, surface wettability and haemocompatibility were discussed.
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Authors: An Sha Zhao, Ping Yang, Yong Xiang Leng, H. Sun, Jin Wang, Guo Jiang Wan, Nan Huang
Abstract: Platelet adhesion and activation restrict the clinical applicability of blood-contacting biomaterial because platelet-biomaterial interaction can result in the formation of a haemostatic plug or thrombus. In this study we used LDH (lactate dehydrogenase) tests to evaluate the adsorption behavior of platelets on material surfaces. Enzyme immunoassay (EIA) was applied to evaluate platelet activation using a special monoclonal antibody directly binding to the Pselectin on the activated platelet membrane. The results show compared with the conventional detecting tools of platelet adhesion / activation such as optical microscopy. LDH (lactate dehydrogenase) testing and EIA (enzyme immunoassay) are surface-sensitive methods for the investigation of various aspects of platelet adsorption and activation on different biomaterials.
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