A synchronous control of relative attitude and position is required in separated ultraquiet spacecraft, such as drag-free, disturbance-free, and distributed spacecraft. Thus, a twistorbased synchronous sliding mode co...A synchronous control of relative attitude and position is required in separated ultraquiet spacecraft, such as drag-free, disturbance-free, and distributed spacecraft. Thus, a twistorbased synchronous sliding mode control is investigated in this paper to solve the control problem of relative attitude and position among separated spacecraft modules. The twistor-based control design and the stability proof are implemented using the Modified Rodrigues Parameter（MRP）.To evaluate the effectiveness of the proposed control method, this paper presents a case study of separated spacecraft flying control considering the mass uncertainty and external disturbances. In addition, a simulation study of the Proportional-Derivative（PD） control is also presented for comparison. The results indicate that the twistor-based sliding mode controller can ensure global asymptotic stability. The states converge fast with ultra-precision and ultra-stability in both the attitude and position. Moreover, the proposed twistor-based sliding mode control system is robust to the mass uncertainty and external disturbances.展开更多
The visualization of the central nervous system(CNS)has proposed stringent criteria for fluorescent probes,as the inevitable production of reactive oxygen species(ROS)or heat generated from most photoluminescent probe...The visualization of the central nervous system(CNS)has proposed stringent criteria for fluorescent probes,as the inevitable production of reactive oxygen species(ROS)or heat generated from most photoluminescent probes upon excitation can disturb the normal status of relatively delicate CNS cells.In this work,a red-emitting fluorogen with aggregation-induced emission(AIE)characteristics,known as DTF,was chosen as the model fluorogen to investigate whether the side effects of ROS and heat could be suppressed through easy-to-operate processes.Specifically,DTF was encapsulated with different amphiphilic matrices to yield AIE nanoprobes,and their photoluminescent properties,ROS production,and photothermal conversion rates were examined.BSA@DTF NPs possessed 1.3-fold brightness compared to that of DSPE-PEG@DTF NPs and F127@DTF NPs but its ROS generation efficiency is markedly decreased to only 2.4%of that produced by F127@DTF NPs.Meanwhile,BSA@DTF NPs showed a negligible photothermal effect.These features make BSA@DTF NPs favorable for long-term live cell imaging,particularly for fluorescent imaging of CNS cells.BSA@DTF NPs were able to sustain the normal state of HT-22 neuronal cells with continuous illumination for at least 25 min,and they also preserved the cytoskeleton of microglia BV-2 cells as the untreated control group.This work represents a successful but easy-to-operate process to suppress the ROS generation of redemissive AIEgen,and it highlights the importance of minimizing the ROS generation of the fluorescent probes,particularly in the application of long-term imaging of CNS cells.展开更多
Pursuit of improved living quality has stimulated great demand for high-performance conformal healthcare devices in modern human society.However,manufacturing of efficient,comfortable and stretchable biomedical appara...Pursuit of improved living quality has stimulated great demand for high-performance conformal healthcare devices in modern human society.However,manufacturing of efficient,comfortable and stretchable biomedical apparatus faces huge challenges using traditional materials.Liquid metals(LMs)show remarkable potential to solve this problem due to their extraordinary biocompatibility,stretchability,thermal and electrical conductivity.In recent years,tremendous explorations have attempted to make stretchable biomedical devices with LMs.Herein,we review the stretchable LMbased biomedical devices on the topics of disease treatment and human function augmenting.The representative and up-to-date neural interfaces,alloy cement,e-vessels,soft heaters,exoskeletons,and e-skins are summarized.The existing issues of LMs applied for biomedical devices are also discussed.This review can provide guidance for the follow-up research in LM-based biomedical devices.展开更多
High-sensitivity piezoelectric ceramics with high piezoelectric constants(d33)values are of significant research value,because they facilitate the miniaturization,lowpower,and high-efficiency characteristics of transd...High-sensitivity piezoelectric ceramics with high piezoelectric constants(d33)values are of significant research value,because they facilitate the miniaturization,lowpower,and high-efficiency characteristics of transducer devices.However,the development of traditional piezoelectric ceramics relies on the modulation of intrinsic parameters with both limited and blind performance enhancements.In contrast,a performance-driven metamaterials creation model provides new ideas for the development of structure-functionintegrated high-performance piezoelectric materials.In this study,the effects of the d33 were systematically investigated in species ranging from two-dimensional straight rod(SR)structures to 3D dot-matrix(Octa)structures,and from simple dot-matrix structures to complex triply periodic minimal surface(TPMS)structures and hybrid structures(Octa&SR).It was found that the metastructure design,characterized by both a high polarization charge conversion rate and a low compression modulus(stiffness),constituted an effective means for enhancing d33.The SR structure demonstrated the optimal polarization charge conversion rate,the Fks-Shellular(FksS)structure in the TPMS structures exhibited low stiffness values,and the Octa&SR structure exhibited both properties.Notably,all three structures exhibited exceptional piezoelectric properties.Moreover,the FksS structure demonstrated a substantial d33(194 pC/N)enhancement of 24%compared with that of the conventional solid structure,while exhibiting isotropic and stress-insensitive properties with optimal structure-function integration.Overall,this study elucidates a mechanism for the design of structures exhibiting desirable piezoelectric properties,thereby providing a novel concept for the future development of high-performance and high-failure-strength piezoelectric materials.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51675430,11402044,and U1537213)
文摘A synchronous control of relative attitude and position is required in separated ultraquiet spacecraft, such as drag-free, disturbance-free, and distributed spacecraft. Thus, a twistorbased synchronous sliding mode control is investigated in this paper to solve the control problem of relative attitude and position among separated spacecraft modules. The twistor-based control design and the stability proof are implemented using the Modified Rodrigues Parameter（MRP）.To evaluate the effectiveness of the proposed control method, this paper presents a case study of separated spacecraft flying control considering the mass uncertainty and external disturbances. In addition, a simulation study of the Proportional-Derivative（PD） control is also presented for comparison. The results indicate that the twistor-based sliding mode controller can ensure global asymptotic stability. The states converge fast with ultra-precision and ultra-stability in both the attitude and position. Moreover, the proposed twistor-based sliding mode control system is robust to the mass uncertainty and external disturbances.
基金great support from Prof.Yulin Deng.This work was supported by funding from the National Natural Science Foundation of China(21904076,22075199,52103228)China Postdoctoral Science Foundation(2022M710377)Beijing Institute of Technology Research Fund Program for Young Scholars(XSQD-202123008).
文摘The visualization of the central nervous system(CNS)has proposed stringent criteria for fluorescent probes,as the inevitable production of reactive oxygen species(ROS)or heat generated from most photoluminescent probes upon excitation can disturb the normal status of relatively delicate CNS cells.In this work,a red-emitting fluorogen with aggregation-induced emission(AIE)characteristics,known as DTF,was chosen as the model fluorogen to investigate whether the side effects of ROS and heat could be suppressed through easy-to-operate processes.Specifically,DTF was encapsulated with different amphiphilic matrices to yield AIE nanoprobes,and their photoluminescent properties,ROS production,and photothermal conversion rates were examined.BSA@DTF NPs possessed 1.3-fold brightness compared to that of DSPE-PEG@DTF NPs and F127@DTF NPs but its ROS generation efficiency is markedly decreased to only 2.4%of that produced by F127@DTF NPs.Meanwhile,BSA@DTF NPs showed a negligible photothermal effect.These features make BSA@DTF NPs favorable for long-term live cell imaging,particularly for fluorescent imaging of CNS cells.BSA@DTF NPs were able to sustain the normal state of HT-22 neuronal cells with continuous illumination for at least 25 min,and they also preserved the cytoskeleton of microglia BV-2 cells as the untreated control group.This work represents a successful but easy-to-operate process to suppress the ROS generation of redemissive AIEgen,and it highlights the importance of minimizing the ROS generation of the fluorescent probes,particularly in the application of long-term imaging of CNS cells.
基金the National Key Research and Development Program(2022YFE0121000)the National Natural Science Foundation of China(62288102)+2 种基金Natural Science Foundation of Shaanxi(Grant No.5110210130)Key Research and Development Program of Shaanxi(Grant No.5140220004)Fundamental Research Funds for the Central Universities(Grant Nos.G2022WD01007 and D5000230125).
文摘Pursuit of improved living quality has stimulated great demand for high-performance conformal healthcare devices in modern human society.However,manufacturing of efficient,comfortable and stretchable biomedical apparatus faces huge challenges using traditional materials.Liquid metals(LMs)show remarkable potential to solve this problem due to their extraordinary biocompatibility,stretchability,thermal and electrical conductivity.In recent years,tremendous explorations have attempted to make stretchable biomedical devices with LMs.Herein,we review the stretchable LMbased biomedical devices on the topics of disease treatment and human function augmenting.The representative and up-to-date neural interfaces,alloy cement,e-vessels,soft heaters,exoskeletons,and e-skins are summarized.The existing issues of LMs applied for biomedical devices are also discussed.This review can provide guidance for the follow-up research in LM-based biomedical devices.
基金supported by the National Natural Science Foundation of China(U22A20129,52562013)the National Key R&D Program of China(2021YFB3701500)+1 种基金the Natural Science Basic Research Program of Shaanxi Province(2025JC-YBMS-431)the Basic Research Strengthening Program of China 173 Program(2021-JCJQ-JJ-0015)。
文摘High-sensitivity piezoelectric ceramics with high piezoelectric constants(d33)values are of significant research value,because they facilitate the miniaturization,lowpower,and high-efficiency characteristics of transducer devices.However,the development of traditional piezoelectric ceramics relies on the modulation of intrinsic parameters with both limited and blind performance enhancements.In contrast,a performance-driven metamaterials creation model provides new ideas for the development of structure-functionintegrated high-performance piezoelectric materials.In this study,the effects of the d33 were systematically investigated in species ranging from two-dimensional straight rod(SR)structures to 3D dot-matrix(Octa)structures,and from simple dot-matrix structures to complex triply periodic minimal surface(TPMS)structures and hybrid structures(Octa&SR).It was found that the metastructure design,characterized by both a high polarization charge conversion rate and a low compression modulus(stiffness),constituted an effective means for enhancing d33.The SR structure demonstrated the optimal polarization charge conversion rate,the Fks-Shellular(FksS)structure in the TPMS structures exhibited low stiffness values,and the Octa&SR structure exhibited both properties.Notably,all three structures exhibited exceptional piezoelectric properties.Moreover,the FksS structure demonstrated a substantial d33(194 pC/N)enhancement of 24%compared with that of the conventional solid structure,while exhibiting isotropic and stress-insensitive properties with optimal structure-function integration.Overall,this study elucidates a mechanism for the design of structures exhibiting desirable piezoelectric properties,thereby providing a novel concept for the future development of high-performance and high-failure-strength piezoelectric materials.
