Peripheral nerve injury is a common clinical problem and affects the quality of life of patients. Traditional restoration methods are not satisfactory. Researchers increasingly focus on the field of tissue engineering...Peripheral nerve injury is a common clinical problem and affects the quality of life of patients. Traditional restoration methods are not satisfactory. Researchers increasingly focus on the field of tissue engineering. The three key points in establishing a tissue engineering material are the biological scaffold material, the seed cells and various growth factors. Understanding the type of nerve injury, the construction of scaffold and the process of repair are necessary to solve peripheral nerve injury and promote its regeneration. This review describes the categories of peripheral nerve injury, fundamental research of peripheral nervous tissue engineering and clinical research on peripheral nerve scaffold material, and paves a way for related research and the use of conduits in clinical practice.展开更多
To realize full automation in machining process, Computer Numerically Controlled （CNC） machine tools have been implemented during the past decades. The CNC machine tools require less operator input, provide greater ...To realize full automation in machining process, Computer Numerically Controlled （CNC） machine tools have been implemented during the past decades. The CNC machine tools require less operator input, provide greater improvements in productivity, and increase the quality of the machined part. End milling is the most common metal removal operation encountered. It is widely used to mate with other part in die, aerospace, automotive, and machinery design as well as in manufacturing industries. Surface roughness is an important measure of the technological quality of a product and a factor that greatly influences manufacturing cost. The quality of the surface plays a very important role in the performance of milling as a good-quality milled surface significantly improves fatigue strength, corrosion resistance, or creep life. Consequently, the desired surface roughness value is usually specified for an individual part, and specific processes are selected in order to achieve the specified finish. Purpose of the study is to develop a technique to predict a surface roughness of the part to be machined according to technological parameters. Such technique could be achieved by making mathematical model of machining. In this study as machining process the milling process is chosen, especially for end milling operation. Additionally to the study, one of the key factors, which differ from similar studies, is that as surface parameters the 2D, 3D surface parameters are used. In this study, all the surface parameters are expressed as 2D, 3D parameters. The 2D, 3D surface parameters give more precise figure of the surface; therefore it is possible to evaluate the surface parameters more precisely according to technological parameters. The result of the study, mathematical model of end-milling is achieved and qualitative analysis is maintained. Achieved model could help technologists to understand more completely the process of forming surface roughness.展开更多
The nanotechnology can provide radical and systematic innovation in architecture. The extent to which, and the manner in which architects, engineers, researchers, builders and producers embrace this innovation will de...The nanotechnology can provide radical and systematic innovation in architecture. The extent to which, and the manner in which architects, engineers, researchers, builders and producers embrace this innovation will determine the future of architectural operations. The introduction of new materials and technologies in architecture has always led to linguistic and typological modifications. It was true even in the past, let＇s just think of the consequences of the industrial revolution. This paper presents some nano-materials for architecture, that can contribute to the energy efficiency of buildings： self-repairing concrete, insulation nano-coating, photo-catalytic cements, anti-stain coating. If we consider new materials and new technologies as a determining factor for a new architecture, then the innovations in the field of concrete, glass, lighting, prompted by nanotechnology, will also influence the language of architecture.展开更多
The magnetic reversal mechanism has been determined within a micromagnetic model reliably for a two-phased magnetic nanosystem, with the formulae for nucleation fields derived analytically. It is found that the nuclea...The magnetic reversal mechanism has been determined within a micromagnetic model reliably for a two-phased magnetic nanosystem, with the formulae for nucleation fields derived analytically. It is found that the nucleation field HN decreases uni- formly as the size of the soft phase Ls increases whereas it increases with the size of the hard phase Lh. The analysis shows that whilst the effect of Lh could be ignored in most cases, where the nucleation field is dominated by the Ls and the calculation could be significantly simplified, the overly simple inverse square law between Hu and the soft layer thickness Ls adopted by the previous researchers is not a good approximation. While nucleation is the beginning of the magnetic reversal, pinning is the dominant coercivity mechanism in both two-phased and single-phased magnetic materials, where the crystalline defects exist. Comparison with the experimental data confirms this conclusion, indicating that Brown＇s paradox results from the much lower effective anisotropy in both single-phased and composite materials, as speculated in the literature.展开更多
基金supported by the National Natural Science Foundation of China,No.31040043,31671248(to NH),No.81171146,81372044,30971526(to BGJ)the Chinese National Ministry of Science and Technology(973 Project),No.2014CB542201(to PXZ)+4 种基金the Ministry of Education Innovation Team,China,No.IRT1201(to PXZ)the Fostering Young Scholars of Peking University Health Science Center,China,No.BMU2017PY013(to PXZ)the Chinese National General Program of National Natural Science Fund,China(to PXZ)the Beijing City Science&Technology New Star Cross Project,China,No.2018019(to PXZ)the National Natural Science Foundation of China,No.31771322,31571235,51373023,21171019,31640045,31571236,31471144,31100860,31371210(to PXZ)
文摘Peripheral nerve injury is a common clinical problem and affects the quality of life of patients. Traditional restoration methods are not satisfactory. Researchers increasingly focus on the field of tissue engineering. The three key points in establishing a tissue engineering material are the biological scaffold material, the seed cells and various growth factors. Understanding the type of nerve injury, the construction of scaffold and the process of repair are necessary to solve peripheral nerve injury and promote its regeneration. This review describes the categories of peripheral nerve injury, fundamental research of peripheral nervous tissue engineering and clinical research on peripheral nerve scaffold material, and paves a way for related research and the use of conduits in clinical practice.
文摘To realize full automation in machining process, Computer Numerically Controlled （CNC） machine tools have been implemented during the past decades. The CNC machine tools require less operator input, provide greater improvements in productivity, and increase the quality of the machined part. End milling is the most common metal removal operation encountered. It is widely used to mate with other part in die, aerospace, automotive, and machinery design as well as in manufacturing industries. Surface roughness is an important measure of the technological quality of a product and a factor that greatly influences manufacturing cost. The quality of the surface plays a very important role in the performance of milling as a good-quality milled surface significantly improves fatigue strength, corrosion resistance, or creep life. Consequently, the desired surface roughness value is usually specified for an individual part, and specific processes are selected in order to achieve the specified finish. Purpose of the study is to develop a technique to predict a surface roughness of the part to be machined according to technological parameters. Such technique could be achieved by making mathematical model of machining. In this study as machining process the milling process is chosen, especially for end milling operation. Additionally to the study, one of the key factors, which differ from similar studies, is that as surface parameters the 2D, 3D surface parameters are used. In this study, all the surface parameters are expressed as 2D, 3D parameters. The 2D, 3D surface parameters give more precise figure of the surface; therefore it is possible to evaluate the surface parameters more precisely according to technological parameters. The result of the study, mathematical model of end-milling is achieved and qualitative analysis is maintained. Achieved model could help technologists to understand more completely the process of forming surface roughness.
文摘The nanotechnology can provide radical and systematic innovation in architecture. The extent to which, and the manner in which architects, engineers, researchers, builders and producers embrace this innovation will determine the future of architectural operations. The introduction of new materials and technologies in architecture has always led to linguistic and typological modifications. It was true even in the past, let＇s just think of the consequences of the industrial revolution. This paper presents some nano-materials for architecture, that can contribute to the energy efficiency of buildings： self-repairing concrete, insulation nano-coating, photo-catalytic cements, anti-stain coating. If we consider new materials and new technologies as a determining factor for a new architecture, then the innovations in the field of concrete, glass, lighting, prompted by nanotechnology, will also influence the language of architecture.
基金support from the National Natural Science Foundation of China (Grant Nos. 10747007 and 11074179)the Scientific Research Foundation for the Returned Overseas Chinese Scholars, the Ministry of Education
文摘The magnetic reversal mechanism has been determined within a micromagnetic model reliably for a two-phased magnetic nanosystem, with the formulae for nucleation fields derived analytically. It is found that the nucleation field HN decreases uni- formly as the size of the soft phase Ls increases whereas it increases with the size of the hard phase Lh. The analysis shows that whilst the effect of Lh could be ignored in most cases, where the nucleation field is dominated by the Ls and the calculation could be significantly simplified, the overly simple inverse square law between Hu and the soft layer thickness Ls adopted by the previous researchers is not a good approximation. While nucleation is the beginning of the magnetic reversal, pinning is the dominant coercivity mechanism in both two-phased and single-phased magnetic materials, where the crystalline defects exist. Comparison with the experimental data confirms this conclusion, indicating that Brown＇s paradox results from the much lower effective anisotropy in both single-phased and composite materials, as speculated in the literature.
