Functionalization of Polypropylene with Chiral Monomer for Improving Hemocompatibility

Year: 2017 Volume: 11 Issue: 2 182 - 188 Pages

• Authors:
• Xiaodong Xu
• Dan Zhao
• Xiujuan Chang
• Chunming Li
• Huiyun Zhou
• Xin Li
• Qiang Shi
• Shifang Luan
• Jinghua Yin

Abstract: Polypropylene (PP) is one of the most commonly used plastics because of its low density, outstanding mechanical properties, and low cost. However, its drawbacks such as low surface energy, poor dyeability, lack of chemical functionalities, and poor compatibility with polar polymers and inorganic materials, have restricted the application of PP. To expand its application in biomedical materials, functionalization is considered to be the most effective way. In this study, PP was functionalized with a chiral monomer, (S)-1-acryloylpyrrolidine-2-carboxylic acid ((S)-APCA), by free-radical grafting in the solid phase. The grafting degree of PP-g-APCA was determined by chemical titration method, and the chemical structure of functionalized PP was characterized by FTIR spectroscopy, which confirmed that the chiral monomer (S)-APCA was successfully grafted onto PP. Static water contact angle results suggested that the surface hydrophilicity of PP was significantly improved by solid phase grafting and assistance of surface water treatment. Protein adsorption and platelet adhesion results showed that hemocompatibility of PP was greatly improved by grafting the chiral monomer.

• Keywords:
• Functionalization
• polypropylene
• chiral monomer
• hemocompatibility.

A Video-based Algorithm for Moving Objects Detection at Signalized Intersection

Year: 2010 Volume: 4 Issue: 6 1091 - 1096 Pages

• Authors:
• Juan Li
• Chunfu Shao
• Chunjiao Dong
• Dan Zhao
• Yinhong Liu

Abstract: Mixed-traffic (e.g., pedestrians, bicycles, and vehicles) data at an intersection is one of the essential factors for intersection design and traffic control. However, some data such as pedestrian volume cannot be directly collected by common detectors (e.g. inductive loop, sonar and microwave sensors). In this paper, a video based detection algorithm is proposed for mixed-traffic data collection at intersections using surveillance cameras. The algorithm is derived from Gaussian Mixture Model (GMM), and uses a mergence time adjustment scheme to improve the traditional algorithm. Real-world video data were selected to test the algorithm. The results show that the proposed algorithm has the faster processing speed and more accuracy than the traditional algorithm. This indicates that the improved algorithm can be applied to detect mixed-traffic at signalized intersection, even when conflicts occur.

• Keywords:
• detection
• intersection
• mixed traffic
• moving objects.