This paper summarizes the authors’ experimental study on the characterization system of composite behavior to withstand impact. The content includes: (1)The dent depth is the best parameter describing the impact dama...This paper summarizes the authors’ experimental study on the characterization system of composite behavior to withstand impact. The content includes: (1)The dent depth is the best parameter describing the impact damage state. (2) There exists the knee point phenomenon for damage resistance behavior (i.e. the relationship between impact energy or contact force and dent depth) and damage tolerance behavior (i.e. the relationship between dent depth and compressive failure strain or stress) of composite laminates. (3) The physical meaning of the knee point phenomenon is that the failure mechanisms change of damaged composites to fiber breakage in the first front plies from matrix crack and delamination. Some suggestions on the characterization system of composite behavior to withstand impact were proposed.展开更多
Background&Objective Knee osteoarthritis(OA)is a degenerative disease,which not only induces superficial cartilage defects and full-thickness cartilage defects,but also exacerbates the microenvironment of the knee...Background&Objective Knee osteoarthritis(OA)is a degenerative disease,which not only induces superficial cartilage defects and full-thickness cartilage defects,but also exacerbates the microenvironment of the knee joint and affects the mechano-chemical responses of the organ.As a growth/repair factor,mechanical growth factor(MGF)has the function of preventing OA,promoting cartilage regeneration and repairing damaged ligaments.activating transcription factor 2(ATF-2),a transcription factor,has the property of binding to cytokines,which makes it involved in the transcriptional regulation of various pathways in response to cellular stress,inflammatory cytokine and growth factors.At present,little is known about the effect of MGF on human osteoarthritis ligament fibroblasts(OA-LFs),and whether the approach can promote OA-LFs timely response to the mechanical injury and initiate signaling pathway for cell survival.Therefore,the purpose of this study is to investigate whether MGF promotes mechanical response to ligament fibroblasts in osteoarthritis knee cavity via ATF-2.Methods OA-LFs were seeded onto six-cell BioFlex plates and suffered from 12%static mechanical stretch[60 cycles/minute(1 Hz)]for 12 hours to mimic mechanical force mediated ligament injury.Meanwhile,OA-LFs were treated with MGF before and during mechanical stretch.Intracellular reactive oxygen species(ROS)and GRP78 mRNA expression were investigated to detect the cellular stress response of OA-LFs.The scratch test was performed to detect the migration ability of cells,gelatin zymography was used to examine the effect of MGF on the activity of matrix metalloproteinase 2(MMP-2)in OA-LFs,and cell deformation was detected by phalloidin-FITC staining after stretching.Quantitative real-time polymerase chain reaction(qRT-PCR)was used to screen the messenger RNA(mRNA)expression of ATF family members after OALFs treatment with MGF.Western blotting further proved that MGF is capable to activate the p-ATF-2.Results OA delays LFs response to mechanical injury,while MGF pretreatment can promote cells timely feedback the mechanically stimuli by inducing cellular stress.MGF treatment can alleviate the decline in cell migration ability caused by mechanical injury and further promote cell migration.In addition,MGF can reduce the activity of MM P-5 and alleviate the stretch-induced deformation of OA-LFs.Furthermore,the mRNA expression of ATF-2 up-regulated in a dose-dependent manner upon MGF treatment compared with control,while the expression of ATF-5 gene was down-regulated in a dose-dependent.Protein levels showed that the expression of p-ATF-2 increased with increasing MGF concentration.Conclusions Our study shows that MGF pretreatment of OA-LFs can respond quickly to mechanical damage and accelerate the ligament injury repair by promoting cell migration,decreasing the MMP-2 activity,and remitting the cell deformation.Therefore,MGF has potential as a therapeutic for OA patients.展开更多
目的基于磁共振mDIXON-Quant技术分析膝骨关节炎(knee osteoarthritis,KOA)髌下脂肪垫质子密度脂肪分数(proton density fat fraction,PDFF)改变,及其与KOA严重程度的相关性。材料与方法前瞻性招募44例KOA患者,共计对70例膝关节进行磁...目的基于磁共振mDIXON-Quant技术分析膝骨关节炎(knee osteoarthritis,KOA)髌下脂肪垫质子密度脂肪分数(proton density fat fraction,PDFF)改变,及其与KOA严重程度的相关性。材料与方法前瞻性招募44例KOA患者,共计对70例膝关节进行磁共振常规序列及mDIXON-Quant序列扫描,测量KOA患者髌下脂肪垫PDFF。膝关节采用全器官磁共振评分(whole-organ magnetic resonance imaging score,WORMS)评估受试KOA严重程度。分析各膝髌下脂肪垫PDFF与WORMS 11个特征独立评分及总评分的相关性。结果髌下脂肪垫PDFF与膝关节WORMS总评分、关节软骨完整性、边缘骨赘、关节面下骨磨损、关节面下骨髓异常、关节面下骨囊肿、内外侧半月板完整性、关节内游离体、关节周围囊肿/滑囊炎、前后交叉韧带完整性、滑膜炎/积液(r=-0.94、-0.85、-0.83、-0.80、-0.72、-0.52、-0.54、-0.39、-0.27、-0.27、-0.24,P均<0.05)WORMS评分均呈负相关性;与内外侧副韧带完整性(r=0.27,P=0.826)WORMS评分无显著相关性。观察者间一致性非常好ICC=0.793(P<0.001),95%可信区间为(0.667~0.875)。结论磁共振mDIXON-Quant技术可以定量评估KOA患者髌下脂肪垫PDFF改变,髌下脂肪垫PDFF随着KOA严重程度进展而下降。髌下脂肪垫PDFF可以作为反映KOA严重程度的客观评价指标。展开更多
基金The financial support from the National Natural Science Foundation of China under project No.10472107 is gratefully acknowledgedThe authors also wish to acknowledge the supports from the Aeronautical Science Foundation of China under project Nos. 04B23002 and 04B52009.
文摘This paper summarizes the authors’ experimental study on the characterization system of composite behavior to withstand impact. The content includes: (1)The dent depth is the best parameter describing the impact damage state. (2) There exists the knee point phenomenon for damage resistance behavior (i.e. the relationship between impact energy or contact force and dent depth) and damage tolerance behavior (i.e. the relationship between dent depth and compressive failure strain or stress) of composite laminates. (3) The physical meaning of the knee point phenomenon is that the failure mechanisms change of damaged composites to fiber breakage in the first front plies from matrix crack and delamination. Some suggestions on the characterization system of composite behavior to withstand impact were proposed.
基金supported by the National Natural Science Foundation of China ( 11532004,31270990, 31600762)Innovation and Attracting Talents Program for College and University( “111”Project) ( B06023)
文摘Background&Objective Knee osteoarthritis(OA)is a degenerative disease,which not only induces superficial cartilage defects and full-thickness cartilage defects,but also exacerbates the microenvironment of the knee joint and affects the mechano-chemical responses of the organ.As a growth/repair factor,mechanical growth factor(MGF)has the function of preventing OA,promoting cartilage regeneration and repairing damaged ligaments.activating transcription factor 2(ATF-2),a transcription factor,has the property of binding to cytokines,which makes it involved in the transcriptional regulation of various pathways in response to cellular stress,inflammatory cytokine and growth factors.At present,little is known about the effect of MGF on human osteoarthritis ligament fibroblasts(OA-LFs),and whether the approach can promote OA-LFs timely response to the mechanical injury and initiate signaling pathway for cell survival.Therefore,the purpose of this study is to investigate whether MGF promotes mechanical response to ligament fibroblasts in osteoarthritis knee cavity via ATF-2.Methods OA-LFs were seeded onto six-cell BioFlex plates and suffered from 12%static mechanical stretch[60 cycles/minute(1 Hz)]for 12 hours to mimic mechanical force mediated ligament injury.Meanwhile,OA-LFs were treated with MGF before and during mechanical stretch.Intracellular reactive oxygen species(ROS)and GRP78 mRNA expression were investigated to detect the cellular stress response of OA-LFs.The scratch test was performed to detect the migration ability of cells,gelatin zymography was used to examine the effect of MGF on the activity of matrix metalloproteinase 2(MMP-2)in OA-LFs,and cell deformation was detected by phalloidin-FITC staining after stretching.Quantitative real-time polymerase chain reaction(qRT-PCR)was used to screen the messenger RNA(mRNA)expression of ATF family members after OALFs treatment with MGF.Western blotting further proved that MGF is capable to activate the p-ATF-2.Results OA delays LFs response to mechanical injury,while MGF pretreatment can promote cells timely feedback the mechanically stimuli by inducing cellular stress.MGF treatment can alleviate the decline in cell migration ability caused by mechanical injury and further promote cell migration.In addition,MGF can reduce the activity of MM P-5 and alleviate the stretch-induced deformation of OA-LFs.Furthermore,the mRNA expression of ATF-2 up-regulated in a dose-dependent manner upon MGF treatment compared with control,while the expression of ATF-5 gene was down-regulated in a dose-dependent.Protein levels showed that the expression of p-ATF-2 increased with increasing MGF concentration.Conclusions Our study shows that MGF pretreatment of OA-LFs can respond quickly to mechanical damage and accelerate the ligament injury repair by promoting cell migration,decreasing the MMP-2 activity,and remitting the cell deformation.Therefore,MGF has potential as a therapeutic for OA patients.
文摘目的基于磁共振mDIXON-Quant技术分析膝骨关节炎(knee osteoarthritis,KOA)髌下脂肪垫质子密度脂肪分数(proton density fat fraction,PDFF)改变,及其与KOA严重程度的相关性。材料与方法前瞻性招募44例KOA患者,共计对70例膝关节进行磁共振常规序列及mDIXON-Quant序列扫描,测量KOA患者髌下脂肪垫PDFF。膝关节采用全器官磁共振评分(whole-organ magnetic resonance imaging score,WORMS)评估受试KOA严重程度。分析各膝髌下脂肪垫PDFF与WORMS 11个特征独立评分及总评分的相关性。结果髌下脂肪垫PDFF与膝关节WORMS总评分、关节软骨完整性、边缘骨赘、关节面下骨磨损、关节面下骨髓异常、关节面下骨囊肿、内外侧半月板完整性、关节内游离体、关节周围囊肿/滑囊炎、前后交叉韧带完整性、滑膜炎/积液(r=-0.94、-0.85、-0.83、-0.80、-0.72、-0.52、-0.54、-0.39、-0.27、-0.27、-0.24,P均<0.05)WORMS评分均呈负相关性;与内外侧副韧带完整性(r=0.27,P=0.826)WORMS评分无显著相关性。观察者间一致性非常好ICC=0.793(P<0.001),95%可信区间为(0.667~0.875)。结论磁共振mDIXON-Quant技术可以定量评估KOA患者髌下脂肪垫PDFF改变,髌下脂肪垫PDFF随着KOA严重程度进展而下降。髌下脂肪垫PDFF可以作为反映KOA严重程度的客观评价指标。
