Sandwich structures are vulnerable to multi-point impacts,and such impacts can result in a reduction in residual strength even catastrophic accident.Therefore,the multi-point impact behaviors of PMI foam sandwich stru...Sandwich structures are vulnerable to multi-point impacts,and such impacts can result in a reduction in residual strength even catastrophic accident.Therefore,the multi-point impact behaviors of PMI foam sandwich structure are investigated and studied using experimental and numerical coupled methods.Three impact energy levels and five Distances Between Impact Positions(DBIP)are considered in details,and representative impact characteristics are compared to reveal the association between Compression After Impact(CAI)strength and DBIP.Results indicate that the interference between the multi-point impact events has a dominant effect on CAI strength when DBIP is small,and the variation in bending stiffness induced by the boundary effect is the dominant factor affecting CAI strength when DBIP ranges from 20 mm to 60 mm.In addition,matrix damage represents the primary damage mode in multi-point impact,and the calculated ratio of energy absorbed by the top face sheet and honeycomb core,in relation to the total absorbed energy,serves as a clear indicator of the damage severity experienced by both components.This work is enlightening for the structural design of impact-resistant composites.展开更多
This paper proposes a new distributed coordinated control scheme based on heterogeneous roles for Unmanned Aerial Vehicle(UAV)swarm to achieve formation control.First,the framework of the distributed coordinated contr...This paper proposes a new distributed coordinated control scheme based on heterogeneous roles for Unmanned Aerial Vehicle(UAV)swarm to achieve formation control.First,the framework of the distributed coordinated control scheme is designed on the basis of Distributed Model Predictive Control(DMPC).Then,the effect of heterogeneous roles including leader,coordinator and follower is discussed,and the role-based cost functions are developed to improve the performance of coordinated control for UAV swarm.Furthermore,a group of coordination strategies are proposed for UAVs with different roles to achieve swarm conflict resolution.Numerical simulations demonstrate that the presented distributed coordinated control scheme is effective to formulate and maintain the desired formation for the UAV swarm.展开更多
Graphene Oxide(GO)-related hydrogels have been extensively studied in hard tissue repair,because GO can not only enhance the mechanical properties of polymers but also promote osteogenic differentiation of mesenchymal...Graphene Oxide(GO)-related hydrogels have been extensively studied in hard tissue repair,because GO can not only enhance the mechanical properties of polymers but also promote osteogenic differentiation of mesenchymal stem cells.However,simple GO-related hydrogels are not ideal for the repair of osteoporotic bone defects as the overactive osteoclasts in osteoporosis.Alendronate(Aln)is known to inhibit osteoclasts and may bind to GO through covalent connection.Therefore,delivering Aln in GO-related hydrogels may be effective to repair osteoporotic bone defects.Here,we developed a control-released system which is constructed by collagen(Col)-GO sponges loaded with Aln(Col-GO-Aln)for osteoporotic bone defect repair.In vitro,Col-GO-Aln sponges prolonged the release period of Aln,and the sponge containing 0.05%(w/v)GO released Aln faster than sponge with 0.2%GO.Furthermore,tartrate-resistant acid phosphatase(TRAP)and F-actin staining demonstrated that Col-GO-Aln sponges effectively inhibited osteoclastogenesis of monocyte-macrophages.In vivo,micro-CT scan showed that the volume of newborn bone in defect site by 0.05%GO sponge was nearly three times larger than that of other groups.Moreover,the CT and histological examinations of rat femur proved that Col-GO-Aln sponges decreased the number of osteoclasts and suppressed the systemic bone loss in osteoporotic rats.These findings reveal that the application of GO as carriers of anti-osteoporosis drugs is a viable treatment for osteoporosis.The results also underscore the potential of GO-related hydrogels with Aln-releasing capacity for bone regeneration in osteoporosis.展开更多
Associated with persistent oxidative stress,altered inflammatory responses,poor angiogenesis and epithelization,wound healing in diabetic patients is impaired.N-acetylcysteine(NAC)is reported to resist excess reactive...Associated with persistent oxidative stress,altered inflammatory responses,poor angiogenesis and epithelization,wound healing in diabetic patients is impaired.N-acetylcysteine(NAC)is reported to resist excess reactive oxygen species(ROS)production,prompt angiogenesis and maturation of the epidermis.Studies have revealed that graphene oxide(GO)can regulate cellular behavior and form cross-links with naturally biodegradable polymers such as collagen(COL)to construct composite scaffolds.Here,we reported a COL-based implantable scaffold containing a mixture of GO capable of the sustained delivery of NAC to evaluate the wound healing in diabetic rats.The morphological,physical characteristics,biocompatibility and NAC release profile of the GO-COL-NAC(GCN)scaffold were evaluated in vitro.Wound healing studies were performed on a 20mm dorsal full-skin defect of streptozotocin(STZ)-induced diabetic rats.The injured skin tissue was removed at the 18th day post-surgery for histological analysis and determination of glutathione peroxidase(GPx),catalase(CAT)and superoxide dismutase(SOD)activity.In diabetic rats,we confirmed that the GCN scaffold presented a beneficial effect in enhancing the wound healing process.Additionally,due to the sustained release of NAC,the scaffold may potentially induce the antioxidant defense system,upregulating the expression levels of the antioxidant enzymes in the wound tissue.The findings revealed that the antioxidant biocompatible composite collagen dressing could not only deliver NAC in situ for ROS inhibition but also promote the wound healing process.This scaffold with valuable therapy potential might enrich the approaches for surgeon in diabetic wound treatment in the future.展开更多
Surface modification using bioactive molecules is frequently performed to improve the biological properties of medical metal biomaterial titanium(Ti)implants.Developmental evidence suggests that mesenchymal stem cell-...Surface modification using bioactive molecules is frequently performed to improve the biological properties of medical metal biomaterial titanium(Ti)implants.Developmental evidence suggests that mesenchymal stem cell-derived extracellular vesicles(MSC-EVs)served as potent bioactive component.As a subset of MSC EV,adipose-derived stem cel-derived extracellular vesicles(ADSC-EVs)could be obtained from abundant adipose tissue.Meanwhile,it possesses multiple re-generative properties and might be used to endow biological activities to medical Ti implant.Here,we present a simple ADSC-EV coating strategy based on physisorption of fibronectin.This ADSC-EV functionalized Ti implants(EV-Ti)revealed enhanced osteoblast compatibility and osteoinduc-tive activity.Cell spreading area of EV-Ti group was 1.62-and 1.48-fold larger than that of Ti group after 6 and 12 h of cell seeding,respectively.Moreover,EV-Ti promoted alkaline phosphatase,col-lagen 1 and osteocalcin gene expression in osteoblast by 1.51-,1.68-and 1.82-fold compared with pristine Ti,respectively.Thus,the MSC-EVs modification method reported here provide a clinically translatable strategy to promote the bioactivity of Ti implants.展开更多
This paper reviews our recent progress on silicon （Si） pn junction light emitting diodes with locally doping engineered carrier potentials. Boron implanted Si diodes with dislocation loops have electroluminescence ...This paper reviews our recent progress on silicon （Si） pn junction light emitting diodes with locally doping engineered carrier potentials. Boron implanted Si diodes with dislocation loops have electroluminescence （EL） quantum efficiency up to 0.12%, which is two orders of magnitude higher than those without dislocations. Boron gettering along the strained dislocation lines produces locally p-type spike doping at the dislocations, which have potential wells for bounding spatially indirect excitons. Thermal dissociation of the bound excitons releases free carriers, leading to an anomalous increase of the band to band luminescence with increasing tempera- ture. Si light emitting diodes with external quantum efficiency of 0.2% have been also demonstrated by implementation of pnpn modulation doping arrays.展开更多
Schisandrin B(Sch B),the major lignans isolated from Schisandra chinensis,exerts high arntioxidant activities.However,it is unknown whether SchB protects neural cell against Aβinduced cellular apoptosis.This study ai...Schisandrin B(Sch B),the major lignans isolated from Schisandra chinensis,exerts high arntioxidant activities.However,it is unknown whether SchB protects neural cell against Aβinduced cellular apoptosis.This study aims to investigate the neuroprotective action of SchB on cellular model of AD,and revealed the underlying mechanisms.展开更多
Aim:Currently,prepectoral breast reconstruction(PBR)is widely used in clinical practice,but its safety lacks high-level epidemiological evidence.This meta-analysis intended to clarify the safety of PBR for clinicians....Aim:Currently,prepectoral breast reconstruction(PBR)is widely used in clinical practice,but its safety lacks high-level epidemiological evidence.This meta-analysis intended to clarify the safety of PBR for clinicians.Methods:The study followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines.Two independent reviewers systematically searched six databases from 1 January 2000 to 27 March 2020 to identify eligible studies.Statistical analysis was performed using R GUI 3.6.3,and a random effects model was used to calculate the proportion with 95%confidence intervals(CIs).Subgroup analysis was conducted based on body mass index,proportion of patients receiving preoperative radiotherapy,surgical technique,and follow-up time.Results:In total,19 studies involving 1686 cases and 2551 breasts were included.The percentage of surgical success was 96.2%,while the total complication rate was 15.4%(95%CI:10.6%-20.9%),hematoma rate was 4.3%(95%CI:2.3%-6.9%),infection rate was 3.4%(95%CI:2.0%-5.1%),and capsular contracture rate was 0.9%(95%CI:0.1%-2.6%).The results of the subgroup analysis show that:(1)the incidence of capsular contracture was higher in patients with lower weight,while other complications were minimal;(2)compared with the patients who underwent two-stage expander-assisted PBR,those with direct to-implant PBR had lower incidences of surgical complications;(3)preoperative radiotherapy could be a risk factor for various postoperative complications;and(4)with the extension of follow-up time,the incidence of long-term complications increases.Conclusion:This present work confirmed that PBR is a safe and reliable therapy with a higher success rate and a relatively lower rate of complications.Overall,PBR can be used as an alternative for sub-pectoral breast reconstruction.展开更多
基金Supported by the National Key R&D Program of China(2023YFB3709602,2023YFB3709603)National Natural Science Foundation of China(12372141)the Key R&D Program in Shaanxi Province(2024GH-ZDXM-27).
文摘Sandwich structures are vulnerable to multi-point impacts,and such impacts can result in a reduction in residual strength even catastrophic accident.Therefore,the multi-point impact behaviors of PMI foam sandwich structure are investigated and studied using experimental and numerical coupled methods.Three impact energy levels and five Distances Between Impact Positions(DBIP)are considered in details,and representative impact characteristics are compared to reveal the association between Compression After Impact(CAI)strength and DBIP.Results indicate that the interference between the multi-point impact events has a dominant effect on CAI strength when DBIP is small,and the variation in bending stiffness induced by the boundary effect is the dominant factor affecting CAI strength when DBIP ranges from 20 mm to 60 mm.In addition,matrix damage represents the primary damage mode in multi-point impact,and the calculated ratio of energy absorbed by the top face sheet and honeycomb core,in relation to the total absorbed energy,serves as a clear indicator of the damage severity experienced by both components.This work is enlightening for the structural design of impact-resistant composites.
基金co-supported by the National Natural Science Foundation of China(Nos.61803009,61903084)Fundamental Research Funds for the Central Universities of China(No.YWF-20-BJ-J-542)the National Science Foundation of Jiangsu Province,China(No.BK20180358).
文摘This paper proposes a new distributed coordinated control scheme based on heterogeneous roles for Unmanned Aerial Vehicle(UAV)swarm to achieve formation control.First,the framework of the distributed coordinated control scheme is designed on the basis of Distributed Model Predictive Control(DMPC).Then,the effect of heterogeneous roles including leader,coordinator and follower is discussed,and the role-based cost functions are developed to improve the performance of coordinated control for UAV swarm.Furthermore,a group of coordination strategies are proposed for UAVs with different roles to achieve swarm conflict resolution.Numerical simulations demonstrate that the presented distributed coordinated control scheme is effective to formulate and maintain the desired formation for the UAV swarm.
基金supported by the National Key R&D Program of China(2019YFA0110500)the National Natural Science Foundation of China(81701922,81873941).
文摘Graphene Oxide(GO)-related hydrogels have been extensively studied in hard tissue repair,because GO can not only enhance the mechanical properties of polymers but also promote osteogenic differentiation of mesenchymal stem cells.However,simple GO-related hydrogels are not ideal for the repair of osteoporotic bone defects as the overactive osteoclasts in osteoporosis.Alendronate(Aln)is known to inhibit osteoclasts and may bind to GO through covalent connection.Therefore,delivering Aln in GO-related hydrogels may be effective to repair osteoporotic bone defects.Here,we developed a control-released system which is constructed by collagen(Col)-GO sponges loaded with Aln(Col-GO-Aln)for osteoporotic bone defect repair.In vitro,Col-GO-Aln sponges prolonged the release period of Aln,and the sponge containing 0.05%(w/v)GO released Aln faster than sponge with 0.2%GO.Furthermore,tartrate-resistant acid phosphatase(TRAP)and F-actin staining demonstrated that Col-GO-Aln sponges effectively inhibited osteoclastogenesis of monocyte-macrophages.In vivo,micro-CT scan showed that the volume of newborn bone in defect site by 0.05%GO sponge was nearly three times larger than that of other groups.Moreover,the CT and histological examinations of rat femur proved that Col-GO-Aln sponges decreased the number of osteoclasts and suppressed the systemic bone loss in osteoporotic rats.These findings reveal that the application of GO as carriers of anti-osteoporosis drugs is a viable treatment for osteoporosis.The results also underscore the potential of GO-related hydrogels with Aln-releasing capacity for bone regeneration in osteoporosis.
基金This study received financial support by the National Key R&D Program of China(2019YFA0110500)the National Natural Science Foundation of China(82020108020,81873941 and 81701922).
文摘Associated with persistent oxidative stress,altered inflammatory responses,poor angiogenesis and epithelization,wound healing in diabetic patients is impaired.N-acetylcysteine(NAC)is reported to resist excess reactive oxygen species(ROS)production,prompt angiogenesis and maturation of the epidermis.Studies have revealed that graphene oxide(GO)can regulate cellular behavior and form cross-links with naturally biodegradable polymers such as collagen(COL)to construct composite scaffolds.Here,we reported a COL-based implantable scaffold containing a mixture of GO capable of the sustained delivery of NAC to evaluate the wound healing in diabetic rats.The morphological,physical characteristics,biocompatibility and NAC release profile of the GO-COL-NAC(GCN)scaffold were evaluated in vitro.Wound healing studies were performed on a 20mm dorsal full-skin defect of streptozotocin(STZ)-induced diabetic rats.The injured skin tissue was removed at the 18th day post-surgery for histological analysis and determination of glutathione peroxidase(GPx),catalase(CAT)and superoxide dismutase(SOD)activity.In diabetic rats,we confirmed that the GCN scaffold presented a beneficial effect in enhancing the wound healing process.Additionally,due to the sustained release of NAC,the scaffold may potentially induce the antioxidant defense system,upregulating the expression levels of the antioxidant enzymes in the wound tissue.The findings revealed that the antioxidant biocompatible composite collagen dressing could not only deliver NAC in situ for ROS inhibition but also promote the wound healing process.This scaffold with valuable therapy potential might enrich the approaches for surgeon in diabetic wound treatment in the future.
基金This work was supported by the National Key R&D Program of China(2019YFA0110500)the National Natural Science Foundation of China(No.81873941,81701922 and 81701912).
文摘Surface modification using bioactive molecules is frequently performed to improve the biological properties of medical metal biomaterial titanium(Ti)implants.Developmental evidence suggests that mesenchymal stem cell-derived extracellular vesicles(MSC-EVs)served as potent bioactive component.As a subset of MSC EV,adipose-derived stem cel-derived extracellular vesicles(ADSC-EVs)could be obtained from abundant adipose tissue.Meanwhile,it possesses multiple re-generative properties and might be used to endow biological activities to medical Ti implant.Here,we present a simple ADSC-EV coating strategy based on physisorption of fibronectin.This ADSC-EV functionalized Ti implants(EV-Ti)revealed enhanced osteoblast compatibility and osteoinduc-tive activity.Cell spreading area of EV-Ti group was 1.62-and 1.48-fold larger than that of Ti group after 6 and 12 h of cell seeding,respectively.Moreover,EV-Ti promoted alkaline phosphatase,col-lagen 1 and osteocalcin gene expression in osteoblast by 1.51-,1.68-and 1.82-fold compared with pristine Ti,respectively.Thus,the MSC-EVs modification method reported here provide a clinically translatable strategy to promote the bioactivity of Ti implants.
基金Aeknowledgements This work was partially supported by the Major State Basic Research Development Program of China （No. 2007CB613403） and the National Natural Science Foundation of China （Grant No. 60977036）. The authors would like to thank G. Schnabel, H. Felsmann, C. Neisser, I. Winkler, U. Lucchesi and M. Missbach for their assistance in the sample preparation.
文摘This paper reviews our recent progress on silicon （Si） pn junction light emitting diodes with locally doping engineered carrier potentials. Boron implanted Si diodes with dislocation loops have electroluminescence （EL） quantum efficiency up to 0.12%, which is two orders of magnitude higher than those without dislocations. Boron gettering along the strained dislocation lines produces locally p-type spike doping at the dislocations, which have potential wells for bounding spatially indirect excitons. Thermal dissociation of the bound excitons releases free carriers, leading to an anomalous increase of the band to band luminescence with increasing tempera- ture. Si light emitting diodes with external quantum efficiency of 0.2% have been also demonstrated by implementation of pnpn modulation doping arrays.
文摘Schisandrin B(Sch B),the major lignans isolated from Schisandra chinensis,exerts high arntioxidant activities.However,it is unknown whether SchB protects neural cell against Aβinduced cellular apoptosis.This study aims to investigate the neuroprotective action of SchB on cellular model of AD,and revealed the underlying mechanisms.
基金supported by the National Key R&D Program of China(2019YFA0110500)the National Natural Science Foundation of China(No.81873941 to Jiaming Sun,No.81901977 to Ran An,No.81701912 to Yun Xia)Natural Science Foundation of Hubei Province(No.2016CFB133 to Ke Guo,No.2019CFB561 to Nengqiang Guo).
文摘Aim:Currently,prepectoral breast reconstruction(PBR)is widely used in clinical practice,but its safety lacks high-level epidemiological evidence.This meta-analysis intended to clarify the safety of PBR for clinicians.Methods:The study followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines.Two independent reviewers systematically searched six databases from 1 January 2000 to 27 March 2020 to identify eligible studies.Statistical analysis was performed using R GUI 3.6.3,and a random effects model was used to calculate the proportion with 95%confidence intervals(CIs).Subgroup analysis was conducted based on body mass index,proportion of patients receiving preoperative radiotherapy,surgical technique,and follow-up time.Results:In total,19 studies involving 1686 cases and 2551 breasts were included.The percentage of surgical success was 96.2%,while the total complication rate was 15.4%(95%CI:10.6%-20.9%),hematoma rate was 4.3%(95%CI:2.3%-6.9%),infection rate was 3.4%(95%CI:2.0%-5.1%),and capsular contracture rate was 0.9%(95%CI:0.1%-2.6%).The results of the subgroup analysis show that:(1)the incidence of capsular contracture was higher in patients with lower weight,while other complications were minimal;(2)compared with the patients who underwent two-stage expander-assisted PBR,those with direct to-implant PBR had lower incidences of surgical complications;(3)preoperative radiotherapy could be a risk factor for various postoperative complications;and(4)with the extension of follow-up time,the incidence of long-term complications increases.Conclusion:This present work confirmed that PBR is a safe and reliable therapy with a higher success rate and a relatively lower rate of complications.Overall,PBR can be used as an alternative for sub-pectoral breast reconstruction.
