The National Strong Motion Observation Network System （NSMONS） of China is briefly introduced in this paper. The NSMONS consists of permanent free-field stations, special observation arrays, mobile observatories and...The National Strong Motion Observation Network System （NSMONS） of China is briefly introduced in this paper. The NSMONS consists of permanent free-field stations, special observation arrays, mobile observatories and a network management system. During the Wenchuan Earthquake, over 1,400 components of acceleration records were obtained from 460 permanent free-field stations and three arrays for topographical effect and structural response observation in the network system from the main shock, and over 20,000 components of acceleration records from strong aftershocks occurred before August 1, 2008 were also obtained by permanent free-field stations of the NSMONS and 59 mobile instruments quickly deployed after the main shock. The strong motion recordings from the main shock and strong aftershocks are summarized in this paper. In the ground motion recordings, there are over 560 components with peak ground acceleration （PGA） over 10 Gal, the largest being 957.7 Gal. The largest PGA recorded during the aftershock exceeds 300 Gal.展开更多
Over 800 accelerograms recorded by 272 ground-level stations during the Wenchuan earthquake are used to analyze the influence of rupture distance, local site conditions and azimuth on peak ground accelerations （PGAs...Over 800 accelerograms recorded by 272 ground-level stations during the Wenchuan earthquake are used to analyze the influence of rupture distance, local site conditions and azimuth on peak ground accelerations （PGAs）. To achieve a better understanding of the characteristics of ground motions, the spatial distributions of the EW, NS and UD components of PGAs are obtained. Comparisons between the EW and NS components, the fault-normal and fault-parallel components, and the vertical and horizontal components of PGAs are performed, and the regression formula of the vertical-to-horizontal ratio of PGAs is developed. The attenuation relationship of peak horizontal accelerations （PHAs） is compared with several contemporary attenuation relationships. In addition, an analysis of residuals is conducted to identify the potential effects of rupture distance, azimuth and site conditions on the observed values of PHAs. The analysis focuses on medium-hard soil site conditions, as they provided most of the data used in this study.展开更多
The incorporation of hydroxyapatite(HAP)into poly-L-lactic acid(PLLA)matrix serving as bone scaffold is expected to exhibit bioactivity and osteoconductivity to those of the living bone.While too low degradation rate ...The incorporation of hydroxyapatite(HAP)into poly-L-lactic acid(PLLA)matrix serving as bone scaffold is expected to exhibit bioactivity and osteoconductivity to those of the living bone.While too low degradation rate of HAP/PLLA scaffold hinders the activity because the embedded HAP in the PLLA matrix is difficult to contact and exchange ions with body fluid.In this study,biodegradable polymer poly(glycolic acid)(PGA)was blended into the HAP/PLLA scaffold fabricated by laser 3D printing to accelerate the degradation.The results indicated that the incorporation of PGA enhanced the degradation rate of scaffold as indicated by the weight loss increasing from 3.3%to 25.0%after immersion for 28 days,owing to the degradation of high hydrophilic PGA and the subsequent accelerated hydrolysis of PLLA chains.Moreover,a lot of pores produced by the degradation of the scaffold promoted the exposure of HAP from the matrix,which not only activated the deposition of bone like apatite on scaffold but also accelerated apatite growth.Cytocompatibility tests exhibited a good osteoblast adhesion,spreading and proliferation,suggesting the scaffold provided a suitable environment for cell cultivation.Furthermore,the scaffold displayed excellent bone defect repair capacity with the formation of abundant new bone tissue and blood vessel tissue,and both ends of defect region were bridged after 8 weeks of implantation.展开更多
基金NSFC Under Grant No. 90715038MOST of China Under Grant No. 2006BAC13B02
文摘The National Strong Motion Observation Network System （NSMONS） of China is briefly introduced in this paper. The NSMONS consists of permanent free-field stations, special observation arrays, mobile observatories and a network management system. During the Wenchuan Earthquake, over 1,400 components of acceleration records were obtained from 460 permanent free-field stations and three arrays for topographical effect and structural response observation in the network system from the main shock, and over 20,000 components of acceleration records from strong aftershocks occurred before August 1, 2008 were also obtained by permanent free-field stations of the NSMONS and 59 mobile instruments quickly deployed after the main shock. The strong motion recordings from the main shock and strong aftershocks are summarized in this paper. In the ground motion recordings, there are over 560 components with peak ground acceleration （PGA） over 10 Gal, the largest being 957.7 Gal. The largest PGA recorded during the aftershock exceeds 300 Gal.
基金National Natural Science Foundation of China Under Grant No. 90715038, 50878199 and 50808166National Basic Research Program of China Under Grant No. 2007CB714200
文摘Over 800 accelerograms recorded by 272 ground-level stations during the Wenchuan earthquake are used to analyze the influence of rupture distance, local site conditions and azimuth on peak ground accelerations （PGAs）. To achieve a better understanding of the characteristics of ground motions, the spatial distributions of the EW, NS and UD components of PGAs are obtained. Comparisons between the EW and NS components, the fault-normal and fault-parallel components, and the vertical and horizontal components of PGAs are performed, and the regression formula of the vertical-to-horizontal ratio of PGAs is developed. The attenuation relationship of peak horizontal accelerations （PHAs） is compared with several contemporary attenuation relationships. In addition, an analysis of residuals is conducted to identify the potential effects of rupture distance, azimuth and site conditions on the observed values of PHAs. The analysis focuses on medium-hard soil site conditions, as they provided most of the data used in this study.
基金This work was supported by the following funds:(1)The Natural Science Foundation of China(51905553,51935014,81871494,81871498)(2)Hunan Provincial Natural Science Foundation of China(2019JJ50774,2019JJ50588)+5 种基金(3)The Provincial Key R&D Projects of Jiangxi(20201BBE51012)(4)JiangXi Provincial Natural Science Foundation of China(20192ACB20005)(5)Guangdong Province Higher Vocational Colleges&Schools Pearl River Scholar Funded Scheme(2018)(6)The Project of Hunan Provincial Science and Technology Plan(2017RS3008)(7)The Project of State Key Laboratory of High Performance Complex Manufacturing,Central South University(8)Shenzhen Science and Technology Plan Project(JCYJ20170817112445033).
文摘The incorporation of hydroxyapatite(HAP)into poly-L-lactic acid(PLLA)matrix serving as bone scaffold is expected to exhibit bioactivity and osteoconductivity to those of the living bone.While too low degradation rate of HAP/PLLA scaffold hinders the activity because the embedded HAP in the PLLA matrix is difficult to contact and exchange ions with body fluid.In this study,biodegradable polymer poly(glycolic acid)(PGA)was blended into the HAP/PLLA scaffold fabricated by laser 3D printing to accelerate the degradation.The results indicated that the incorporation of PGA enhanced the degradation rate of scaffold as indicated by the weight loss increasing from 3.3%to 25.0%after immersion for 28 days,owing to the degradation of high hydrophilic PGA and the subsequent accelerated hydrolysis of PLLA chains.Moreover,a lot of pores produced by the degradation of the scaffold promoted the exposure of HAP from the matrix,which not only activated the deposition of bone like apatite on scaffold but also accelerated apatite growth.Cytocompatibility tests exhibited a good osteoblast adhesion,spreading and proliferation,suggesting the scaffold provided a suitable environment for cell cultivation.Furthermore,the scaffold displayed excellent bone defect repair capacity with the formation of abundant new bone tissue and blood vessel tissue,and both ends of defect region were bridged after 8 weeks of implantation.
