Osteochondral （OC） lesions are characterized by defects in two different zones, the cartilage region and subchondral bone region. These lesions are frequently associated with mechanical instability, as well as osteo...Osteochondral （OC） lesions are characterized by defects in two different zones, the cartilage region and subchondral bone region. These lesions are frequently associated with mechanical instability, as well as osteoarthritic degenerative changes in the knee. The lack of spontaneous healing and the drawbacks of the current treatments have increased the attention from the scientific community to this issue. Different tissue engineering approaches have been attempted using different polymers and different scaffolds＇ processing. However, the current conventional techniques do not allow the full control over scaffold fabrication, and in this type of approaches, the tuning ability is the key to success in tissue regeneration. In this sense, the researchers have placed their efforts in the development of solid free-form （SFF） techniques. These techniques allow tuning different properties at the micro-macro scale, creating scaffolds with appropriate features for OC tissue engineering. In this review, it is discussed the current SFF techniques used in OC tissue engineering and presented their promising results and current challenges.展开更多
Lie symmetry reduction of some truly ＂variable coefficient＂ wave equations which are singled out from a class of （1 ＋ 1）-dimensional variable coefficient nonlinear wave equations with respect to one and two-dimen...Lie symmetry reduction of some truly ＂variable coefficient＂ wave equations which are singled out from a class of （1 ＋ 1）-dimensional variable coefficient nonlinear wave equations with respect to one and two-dimensional algebras is carried out. Some classes of exact solutions of the investigated equations are found by means of both the reductions and some modern techniques such as additional equivalent transformations and hidden symmetries and so on. Conditional symmetries are also discussed.展开更多
Field research in this paper was carried out in Baiyinxil State-owned Rangeland （SOR）, which is 55 kms southeast of Xilingol City in Xilingol League, Inner Mongolia Autonomous Region （IMAR）. The area established t...Field research in this paper was carried out in Baiyinxil State-owned Rangeland （SOR）, which is 55 kms southeast of Xilingol City in Xilingol League, Inner Mongolia Autonomous Region （IMAR）. The area established the first grassland nature reserve in China as well as the first SOR in IMAR. By reviewing its 60 years of development, the paper analyzes local herders＇ ecological ideology （the cycle made of human-grassland-livestock and none of which could be neglected） and the modern nation-state＇s policy implementation in ecological resettlement, institutional changes, and livestock cross-breeding. The purpose of the research is to discuss three pairs of socio-ecological relationships in Inner Mongolia grassland： between population flow and regional development, traditional ideology and grassland management ideology, as well as the competition between local knowledge and modern science and technology. The author argues that grassland management is a cyclical process and the deterioration of grassland ecology in IMAR is simply a reflection of the imbalance of three key elements （human-institution-cattle） in maintaining grassland ecology.展开更多
文摘Osteochondral （OC） lesions are characterized by defects in two different zones, the cartilage region and subchondral bone region. These lesions are frequently associated with mechanical instability, as well as osteoarthritic degenerative changes in the knee. The lack of spontaneous healing and the drawbacks of the current treatments have increased the attention from the scientific community to this issue. Different tissue engineering approaches have been attempted using different polymers and different scaffolds＇ processing. However, the current conventional techniques do not allow the full control over scaffold fabrication, and in this type of approaches, the tuning ability is the key to success in tissue regeneration. In this sense, the researchers have placed their efforts in the development of solid free-form （SFF） techniques. These techniques allow tuning different properties at the micro-macro scale, creating scaffolds with appropriate features for OC tissue engineering. In this review, it is discussed the current SFF techniques used in OC tissue engineering and presented their promising results and current challenges.
基金Supported by the National Key Basic Research Project of China under Grant No.2010CB126600the National Natural Science Foundation of China under Grant No.60873070+2 种基金Shanghai Leading Academic Discipline Project No.B114the Postdoctoral Science Foundation of China under Grant No.20090450067Shanghai Postdoctoral Science Foundation under Grant No.09R21410600
文摘Lie symmetry reduction of some truly ＂variable coefficient＂ wave equations which are singled out from a class of （1 ＋ 1）-dimensional variable coefficient nonlinear wave equations with respect to one and two-dimensional algebras is carried out. Some classes of exact solutions of the investigated equations are found by means of both the reductions and some modern techniques such as additional equivalent transformations and hidden symmetries and so on. Conditional symmetries are also discussed.
文摘Field research in this paper was carried out in Baiyinxil State-owned Rangeland （SOR）, which is 55 kms southeast of Xilingol City in Xilingol League, Inner Mongolia Autonomous Region （IMAR）. The area established the first grassland nature reserve in China as well as the first SOR in IMAR. By reviewing its 60 years of development, the paper analyzes local herders＇ ecological ideology （the cycle made of human-grassland-livestock and none of which could be neglected） and the modern nation-state＇s policy implementation in ecological resettlement, institutional changes, and livestock cross-breeding. The purpose of the research is to discuss three pairs of socio-ecological relationships in Inner Mongolia grassland： between population flow and regional development, traditional ideology and grassland management ideology, as well as the competition between local knowledge and modern science and technology. The author argues that grassland management is a cyclical process and the deterioration of grassland ecology in IMAR is simply a reflection of the imbalance of three key elements （human-institution-cattle） in maintaining grassland ecology.
