The systematic discrepancies in both tsunami arrival time and leading negative phase(LNP)were identified for the recent transoceanic tsunami on 16 September 2015 in Illapel,Chile by examining the wave characteristics ...The systematic discrepancies in both tsunami arrival time and leading negative phase(LNP)were identified for the recent transoceanic tsunami on 16 September 2015 in Illapel,Chile by examining the wave characteristics from the tsunami records at 21 Deep-ocean Assessment and Reporting of Tsunami(DART)sites and 29 coastal tide gauge stations.The results revealed systematic travel time delay of as much as 22 min(approximately 1.7%of the total travel time)relative to the simulated long waves from the 2015 Chilean tsunami.The delay discrepancy was found to increase with travel time.It was difficult to identify the LNP from the near-shore observation system due to the strong background noise,but the initial negative phase feature became more obvious as the tsunami propagated away from the source area in the deep ocean.We determined that the LNP for the Chilean tsunami had an average duration of 33 min,which was close to the dominant period of the tsunami source.Most of the amplitude ratios to the first elevation phase were approximately 40%,with the largest equivalent to the first positive phase amplitude.We performed numerical analyses by applying the corrected long wave model,which accounted for the effects of seawater density stratification due to compressibility,self-attraction and loading(SAL)of the earth,and wave dispersion compared with observed tsunami waveforms.We attempted to accurately calculate the arrival time and LNP,and to understand how much of a role the physical mechanism played in the discrepancies for the moderate transoceanic tsunami event.The mainly focus of the study is to quantitatively evaluate the contribution of each secondary physical effect to the systematic discrepancies using the corrected shallow water model.Taking all of these effects into consideration,our results demonstrated good agreement between the observed and simulated waveforms.We can conclude that the corrected shallow water model can reduce the tsunami propagation speed and reproduce the LNP,which is observed for tsunamis that have propagated over long distances frequently.The travel time delay between the observed and corrected simulated waveforms is reduced to<8 min and the amplitude discrepancy between them was also markedly diminished.The incorporated effects amounted to approximately 78%of the travel time delay correction,with seawater density stratification,SAL,and Boussinesq dispersion contributing approximately 39%,21%,and 18%,respectively.The simulated results showed that the elastic loading and Boussinesq dispersion not only affected travel time but also changed the simulated waveforms for this event.In contrast,the seawater stratification only reduced the tsunami speed,whereas the earth’s elasticity loading was responsible for LNP due to the depression of the seafloor surrounding additional tsunami loading at far-field stations.This study revealed that the traditional shallow water model has inherent defects in estimating tsunami arrival,and the leading negative phase of a tsunami is a typical recognizable feature of a moderately strong transoceanic tsunami.These results also support previous theory and can help to explain the observed discrepancies.展开更多
Continual learning(CL)studies the problem of learning to accumulate knowledge over time from a stream of data.A crucial challenge is that neural networks suffer from performance degradation on previously seen data,kno...Continual learning(CL)studies the problem of learning to accumulate knowledge over time from a stream of data.A crucial challenge is that neural networks suffer from performance degradation on previously seen data,known as catastrophic forgetting,due to allowing parameter sharing.In this work,we consider a more practical online class-incremental CL setting,where the model learns new samples in an online manner and may continuously experience new classes.Moreover,prior knowledge is unavailable during training and evaluation.Existing works usually explore sample usages from a single dimension,which ignores a lot of valuable supervisory information.To better tackle the setting,we propose a novel replay-based CL method,which leverages multi-level representations produced by the intermediate process of training samples for replay and strengthens supervision to consolidate previous knowledge.Specifically,besides the previous raw samples,we store the corresponding logits and features in the memory.Furthermore,to imitate the prediction of the past model,we construct extra constraints by leveraging multi-level information stored in the memory.With the same number of samples for replay,our method can use more past knowledge to prevent interference.We conduct extensive evaluations on several popular CL datasets,and experiments show that our method consistently outperforms state-of-the-art methods with various sizes of episodic memory.We further provide a detailed analysis of these results and demonstrate that our method is more viable in practical scenarios.展开更多
Psoriasis is a chronic inflammatory skin disease characterized by erythema,scaling,and skin thickening.Topical drug application is recommended as the first-line treatment.Many formulation strategies have been develope...Psoriasis is a chronic inflammatory skin disease characterized by erythema,scaling,and skin thickening.Topical drug application is recommended as the first-line treatment.Many formulation strategies have been developed and explored for enhanced topical psoriasis treatment.However,these preparations usually have low viscosity and limited retention on the skin surface,resulting in low drug delivery efficiency and poor patient satisfaction.In this study,we developed the first water-responsive gel(WRG),which has a distinct water-triggered liquid-to-gel phase transition property.Specifically,WRG was kept in a solution state in the absence of water,and the addition of water induced an immediate phase transition and resulted in a high viscosity gel.Curcumin was used as a model drug to investigate the potential of WRG in topical drug delivery against psoriasis.In vitro and in vivo data showed that WRG formulation could not only extend skin retention but also facilitate the drug permeating across the skin.In a mouse model of psoriasis,curcumin loaded WRG(CUR-WRG)effectively ameliorated the symptoms of psoriasis and exerted a potent anti-psoriasis effect by extending drug retention and facilitating drug penetration.Further mechanism study demonstrated that the anti-hyperplasia,anti-inflammation,anti-angiogenesis,anti-oxidation,and immunomodulation properties of curcumin were amplified by enhanced topical drug delivery efficiency.Notably,neglectable local or systemic toxicity was observed for CUR-WRG application.This study suggests that WRG is a promising formulation for topically psoriasis treatment.展开更多
From the viewpoint of production engineering, microforming is considered as an effective process to fabricate various microparts. Several key problems in microforming processes were investigated. A new microforming ap...From the viewpoint of production engineering, microforming is considered as an effective process to fabricate various microparts. Several key problems in microforming processes were investigated. A new microforming apparatus with a high stiffness piezoelectric actuator as the punch driver was developed to produce microparts.To improve the forming abilities and locate the billets, a floating microdie was designed. The size effects of the billets and die cavities on the microforming abilities were studied with upsetting and coining tests, respectively.And the isothermal microforming process of microgears was performed with the developed microforming apparatus. Several analysis methods were used to evaluate the forming quality of the microparts.展开更多
Psoriasis is a common chronic immune-mediated skin disease characterized by hyperproliferation and aberrant differentiation of keratinocytes and massive infiltration of inflammatory immune cells.Recent studies showed ...Psoriasis is a common chronic immune-mediated skin disease characterized by hyperproliferation and aberrant differentiation of keratinocytes and massive infiltration of inflammatory immune cells.Recent studies showed that Signal Transducer and Activator of Transcription 3(STAT3),which plays an important role in cell survival,proliferation,differentiation,angiogenesis,and immune responses,is constitutively activated in epidermal keratinocytes of human psoriatic skin lesions.In addition,STAT3 promotes the differentiation and expansion of T cells and facilitates cytokine production,thereby exacerbating the condition of psoriasis.Alantolactone(ALT)is a sesquiterpene lactone compound that could selectively suppress STAT3 activation,but its effectiveness and application in psoriasis treatment have not been determined.In this study,we developed ALT loaded chitosan/hyaluronic acid nanoparticles(CHALT),and investigated its therapeutic potential for psoriasis therapy.CHALT effectively abrogated the hyperproliferation by inducing ROS-mediated apoptosis with loss of mitochondrialmembrane potential,and also inhibited IL-6-induced STAT3 signaling activation and inflammatory reaction in HaCaT cell line.In an Imiquimod(IMQ)-induced psoriasis model,the topical treatment of psoriasis lesions with CHALT effectively attenuated the STAT3 hyperactivation within keratinocytes and ameliorated the symptoms of psoriasis.In addition,it was found that CHALT restricted the recruitment of immune cells.These results indicated that ALT-based nanoformulation CHALT holds great potential for psoriasis therapy.展开更多
At 12:15 on January 15,2022(Beijing time),a massive eruption of the Hunga Tonga-Hunga Ha'apai volcano produced violent atmospheric fluctuations,which in turn generated a global tsunami through an abrupt air pressu...At 12:15 on January 15,2022(Beijing time),a massive eruption of the Hunga Tonga-Hunga Ha'apai volcano produced violent atmospheric fluctuations,which in turn generated a global tsunami through an abrupt air pressure shock upon the sea surface.Two main components of tsunami waves,phase-locked waves and free gravity waves,were identified by significant differences in propagating speeds across the deep ocean.The phase-locked wave propagated through the ocean basin synchronously with the atmospheric Lamb wave at an average speed of approximately 306 m/s,followed by the free gravity wave at a slower speed.The locked wave reached the coast of eastern Taiwan Island at about 20:00 on January 15,in coincidence with the Lamb wave arrival.However,on the coast of Chinese mainland,tidal gauges did not record tsunami signals until at least 2 h after the Lamb wave arrivals.Theoretical analyses and numerical experiments both suggested that as a result of the incoming wave shoaling above the vast continental shelf of Chinese mainland,the locked wave was no longer trapped by the air pressure shock and gradually transformed into freely-propagating shallow water waves by slowing down its propagation.Due to the longlasting planetary atmospheric fluctuations circling the earth many times,the sea level oscillations continuously propagated onto the Chinese shelf,which resulted in the tsunami waves excited along the Chinese coasts for at least 36 h.The maximum wave amplitude recorded on the coast of eastern Taiwan Island was 44 cm at Wushi,while on the coasts of eastern and southern Chinese mainland,the maximum amplitudes were 22 cm at Shipu and 13 cm at Zhuhai.Fourier and wavelet analyses were performed to identify the major components of the tsunami waves on the Chinese coasts.The results indicated that eastern Taiwan Island was impacted mainly by the waves with periods of approximately 10-40 min.Chinese mainland was hit by the evolved shallow water waves and subsequent free waves,with periods of approximately 40-100 and 16-20 min,respectively.展开更多
Luminescence quench is common in overdoped upconversion nanoparticles.Various methods have been proposed to counteract the adverse effects of concentration quenching on luminescence,but in upconversion nanoparticles t...Luminescence quench is common in overdoped upconversion nanoparticles.Various methods have been proposed to counteract the adverse effects of concentration quenching on luminescence,but in upconversion nanoparticles that are highly doped with both sensitizers and activators,the factors that contribute to the diminishing of the emission cannot be summarized by a single cause.Herein,a core-shell design is used to spatially separate the sensitizer(Yb^(3+))and activator(Er^(3+))and to modulate the emission by changes in the distribution position as well as the concentration of the dopant ions in order to probe the factors affecting the luminescence.When the sensitizer ions are located in the core,the luminescence intensity of the nanoparticles is significantly weaker than that of the other distribution,which implies that the effect of sensitizer and activator on luminescence in the highly doped state has a different and more complex mechanism.The intensity of the emission is more affected by Yb^(3+)than Er^(3+),which includes not only the self-quenching of Yb^(3+),but also the dominance in the Yb^(3+)-Er^(3+)cross-relaxation.In this finding may provide new ideas for revealing the reasons for the diminished luminescence of highly doped upconversion nanoparticles and thus for enhancing luminescence.展开更多
Artificial intelligence is currently achieving impressive success in all fields.However,autonomous navigation remains a major challenge for AI.Reinforcement learning is used for target navigation to simulate the inter...Artificial intelligence is currently achieving impressive success in all fields.However,autonomous navigation remains a major challenge for AI.Reinforcement learning is used for target navigation to simulate the interaction between the brain and the environment at the behavioral level,but the Artificial Neural Network trained by reinforcement learning cannot match the autonomous mobility of humans and animals.The hippocampus–striatum circuits are considered as key circuits for target navigation planning and decision-making.This paper aims to construct a bionic navigation model of reinforcement learning corresponding to the nervous system to improve the autonomous navigation performance of the robot.The ventral striatum is considered to be the behavioral evaluation region,and the hippocampal–striatum circuit constitutes the position–reward association.In this paper,a set of episode cognition and reinforcement learning system simulating the mechanism of hippocampus and ventral striatum is constructed,which is used to provide target guidance for the robot to perform autonomous tasks.Compared with traditional methods,this system reflects the high efficiency of learning and better Environmental Adaptability.Our research is an exploration of the intersection and fusion of artificial intelligence and neuroscience,which is conducive to the development of artificial intelligence and the understanding of the nervous system.展开更多
The hippocampal formation of the brain contains a series of nerve cells related to environmental cognition and navigation.These cells can integrate their moment information and external perceptual information and acqu...The hippocampal formation of the brain contains a series of nerve cells related to environmental cognition and navigation.These cells can integrate their moment information and external perceptual information and acquire episodic cognitive memory.Through episodic cognition and memory,organisms can achieve autonomous navigation in complex environments.This paper mainly studies the strategy of robot episode navigation in complex environments.After exploring the environment,the robot obtains subjective environmental cognition and forms a cognition map.The grid cells information contained in the cognitive map can obtain the direction and distance of the target through vector calculation,which can get a shortcut through the inexperienced area.The synaptic connection of place cells in the cognitive map can be used as the topological relationship between episode nodes.When the target-oriented vector navigation encounters obstacles,the obstacles can be realized by setting closer sub-targets.Based on the known obstacle information obtained from boundary cells in the cognitive map,topological paths can be divided into multi-segment vector navigation to avoid encountering obstacles.This paper combines vector and topological navigation to achieve goal-oriented and robust navigation capability in a complex environment.展开更多
Legged robots have better performance on discontinuous terrain than that of wheeled robots. However, the dynamic trotting and balance control of a quadruped robot is still a challenging problem, especially when the ro...Legged robots have better performance on discontinuous terrain than that of wheeled robots. However, the dynamic trotting and balance control of a quadruped robot is still a challenging problem, especially when the robot has multi-joint legs. This paper presents a three-dimensional model of a quadruped robot which has 6 Degrees of Freedom (DOF) on torso and 5 DOF on each leg. On the basis of the Spring-Loaded Inverted Pendulum (SLIP) model, body control algorithm is discussed in the first place to figure out how legs work in 3D trotting. Then, motivated by the principle of joint function separation and introducing certain biological characteristics, two joint coordination approaches are developed to produce the trot and provide balance. The robot reaches the highest speed of 2.0 m.s-1, and keeps balance under 250 Kg.m.s-1 lateral disturbance in the simulations. The effectiveness of these approaches is also verified on a prototype robot which runs to 0.83 m.s-1 on the treadmill, The simulations and experiments show that legged robots have good biological properties, such as the ground reaction force, and spring-like leg behavior.展开更多
Rare earth doped upconversion nanoparticles can be considered as the spice of research in the field of luminescence nanomaterials due to their unique optical properties such as near-infrared excitation.Enormous works ...Rare earth doped upconversion nanoparticles can be considered as the spice of research in the field of luminescence nanomaterials due to their unique optical properties such as near-infrared excitation.Enormous works have been reported about biomedical applications of 980 nm excited and Yb^3+-sensitized upconversion nanoparticles.However,980 nm excitation wavelength overlaps with the absorption band of water molecules in the biological environment,leading to overheating effect that can induce thermal damages of normal cells and tissues.Recently,Nd^3+-sensitized upconversion nanoparticles which can be excited with 808 nm has been widely investigated as alternative nanoparticles that can surmount this issue of overheating effect.Even though Nd^3+-sensitized upconversion nanoparticles can reduce the overheating effect by 20 fold as compared to Yb^3+-sensitized counterpart,there are several factors that reduce the upconversion luminescence intensity.In this review article,photon energy harvesting and transferring mechanisms in Nd^3+,Yb^3+and emitter ions co-doped upconversion nanoparticles under 808 nm excitation are briefly discussed.Factors that affect upconversion luminescence intensity and quantum yield of Nd^3+-sensitized upconversion nanoparticles are also addressed.Besides,some of the important strategies that have been recently utilized to boost upconversion luminescence intensity of Nd^3+sensitized upco nversion nanoparticles are tho roughly summarized.Lastly,the future challenges in the area and our perspectives are in sight.展开更多
The realization of a high-speed running robot is one of the most challenging problems in developing legged robots. The excellent performance of cheetahs provides inspiration for the control and mechanical design of su...The realization of a high-speed running robot is one of the most challenging problems in developing legged robots. The excellent performance of cheetahs provides inspiration for the control and mechanical design of such robots. This paper presents a three-dimensional model of a cheetah that predicts the locomotory behaviors of a running cheetah. Applying biological knowledge of the neural mechanism, we control the muscle flexion and extension during the stance phase, and control the positions of the joints in the flight phase via a PD controller to minimize complexity. The proposed control strategy is shown to achieve similar locomotion of a real cheetah. The simulation realizes good biological properties, such as the leg retraction, ground reaction force, and spring-like leg behavior. The stable bounding results show the promise of the controller in high-speed locomotion. The model can reach 2.7 m-s^-1 as the highest speed, and can accelerate from 0 to 1.5 m-s^-1 in one stride cycle. A mechanical structure based on this simulation is designed to demonstrate the control approach, and the most recently developed hindlimb controlled by the proposed controller is presented in swinging-leg experiments and jump-force experiments.展开更多
A CPG control mechanism is proposed for hopping motion control of biped robot in unpredictable environment. Based on analysis of robot motion and biological observation of animal's control mechanism, the motion contr...A CPG control mechanism is proposed for hopping motion control of biped robot in unpredictable environment. Based on analysis of robot motion and biological observation of animal's control mechanism, the motion control task is divided into two simple parts: motion sequence control and output force control. Inspired by a two-level CPG model, a two-level CPG control mechanism is constructed to coordinate the drivers of robot joint, while various feedback information are introduced into the control mechanism. Interneurons within the control mechanism are modeled to generate motion rhythm and pattern promptly for motion sequence control; motoneurons are modeled to control output forces of joint drivers in real time according to feedbacks. The control system can perceive changes caused by unknown perturbations and environment changes according to feedback information, and adapt to unpredictable environment by adjusting outputs of neurons. The control mechanism is applied to a biped hopping robot in unpredictable environment on simulation platform, and stable adaptive motions are obtained.展开更多
Manganese-zinc ferrite is a kind of very important magnetic ferrite material.The properties of wide absorption band,sensitivity to ultraviolet(UV)light and tumor H_(2)O_(2) promise it to be possibly used as a photothe...Manganese-zinc ferrite is a kind of very important magnetic ferrite material.The properties of wide absorption band,sensitivity to ultraviolet(UV)light and tumor H_(2)O_(2) promise it to be possibly used as a photothermal therapy(PTT),photodynamic therapy(PDT)and chemodynamic therapy(CDT)agent.Based on the unique advantages of rare-earth doped nanoparticles,an Er^(3+),Tm^(3+)co-doped upconversion-mediated nanosystem with manganese-zinc ferrite shell(named as UCNPS@M)was developed through a facile thermal co-decomposition method.The final nanosystems were surface-modified by using dopamine hydrochloride(DA)in order to warrant good biocompatibility(named as UCNPS@M@DA).Under irradiation of near-infrared(NIR)light,UCNPS emit both ultraviolet and visible light.The UV light is mostly abso rbed by manga nese-zinc ferrite shell to produce reactive oxygen species(ROS),which is essential to the potential PDT and CDT effect of nanosystems,and at the same time,Mn_(0.5)Zn_(0.5)Fe2O_(4) can further react with H_(2)O_(2) to promote the efficiency of OH-generation.It is expected that UCNPS@M@DA can act as upconversion luminescence imaging guidance due to the visible emission from UCNPS.In addition,the energy absorbed by the nanosystems can be transferred to heat to realize photothermal effect.Moreover,UCNPS@M@DA was successfully applied as a T_(1)/T_(2)-weighted magnetic resonance imaging(MRI)contrast agent due to the existence of Gd,Mn,and Fe elements.In light of the upconversion luminescence(UCL)imaging from the UCNPS as well as potential PTT,PDT,CDT effect mentioned above,this work provides a possibility to realize cancer multi-model bioimaging guided treatment by using an all-in-one diagnosis and therapy nanosystem through a simple yet powerful strategy.展开更多
Throat cancer treatment involves surgical removal of the tumor,leaving patients with facial disfigurement as well as temporary or permanent loss of voice.Surface electromyography(sEMG)generated from the jaw contains l...Throat cancer treatment involves surgical removal of the tumor,leaving patients with facial disfigurement as well as temporary or permanent loss of voice.Surface electromyography(sEMG)generated from the jaw contains lots of voice information.However,it is difficult to record because of not only the weakness of the signals but also the steep skin curvature.This paper demonstrates the design of an imperceptible,flexible epidermal sEMG tattoo-like patch with the thickness of less than 10μm and peeling strength of larger than 1N cm−1 that exhibits large adhesiveness to complex biological surfaces and is thus capable of sEMG recording for silent speech recognition.When a tester speaks silently,the patch shows excellent performance in recording the sEMG signals from three muscle channels and recognizing those frequently used instructions with high accuracy by using the wavelet decomposition and pattern recognization.The average accuracy of action instructions can reach up to 89.04%,and the average accuracy of emotion instructions is as high as 92.33%.To demonstrate the functionality of tattoo-like patches as a new human–machine interface(HMI)for patients with loss of voice,the intelligent silent speech recognition,voice synthesis,and virtual interaction have been implemented,which are of great importance in helping these patients communicate with people and make life more enjoyable.展开更多
The continuously growing importance of information storage,transmission,and authentication impose many new demands and challenges for modern nano-photonic materials and information storage technologies,both in securit...The continuously growing importance of information storage,transmission,and authentication impose many new demands and challenges for modern nano-photonic materials and information storage technologies,both in security and storage capacity.Recently,luminescent lanthanide-doped nanomaterials have drawn much attention in this field because of their photostability,multimodal/multicolor/narrowband emissions,and long luminescence lifetime.Here,we report a multimodal nanocomposite composed of lanthanide-doped upconverting nanoparticle and EuSe semiconductor,which was constructed by utilizing a cation exchange strategy.The nanocomposite can emit blue and white light under 365 and 394 nm excitation,respectively.Meanwhile,the nanocomposites show different colors under 980 nm laser excitation when the content of Tb3+ions is changed in the upconversion nanoparticles.Moreover,the time-gating technology is used to filter the upconversion emission of a long lifetime from Tb3+or Eu3+,and the possibilities for modulating the emission color of the nanocomposites are further expanded.Based on the advantage of multiple tunable luminescence,the nanocomposites are designed as optical modules to load optical information.This work enables multi-dimensional storage of information and provides new insights into the design and fabrication of next-generation storage materials.展开更多
In this paper a bio-inspired approach of velocity control for a quadruped robot running with a bounding gait on compliant legs is set up. The dynamic properties ofa sagittal plane model of the robot are investigated. ...In this paper a bio-inspired approach of velocity control for a quadruped robot running with a bounding gait on compliant legs is set up. The dynamic properties ofa sagittal plane model of the robot are investigated. By analyzing the stable fixed points based on Poincare map, we find that the energy change of the system is the main source for forward velocity adjustment. Based on the analysis of the dynamics model of the robot, a new simple linear running controller is proposed using the energy control idea, which requires minimal task level feedback and only controls both the leg torque and ending impact angle. On the other hand, the functions of mammalian vestibular reflexes are discussed, and a reflex map between forward velocity and the pitch movement is built through statistical regression analysis. Finally, a velocity controller based on energy control and vestibular reflexes is built, which has the same structure as the mammalian nervous mechanism for body posture control. The new con- troller allows the robot to run autonomously without any other auxiliary equipment and exhibits good speed adjustment capa- bility. A series simulations and experiments were set to show the good movement agility, and the feasibility and validity of the robot system.展开更多
Combining treatment and diagnosis,called theranostics,which is achieved within single nanoparticle is an ultimate goal of many studies.Herein,we developed a new nanotheranostic agent-Nd^(3+)-sensitized upconversion na...Combining treatment and diagnosis,called theranostics,which is achieved within single nanoparticle is an ultimate goal of many studies.Herein,we developed a new nanotheranostic agent-Nd^(3+)-sensitized upconversion nanoparticles core for dual modal imaging(i.e.,upconversion luminescence imaging and magnetic resonance imaging) and antimony nanoshell for photothermal therapy(PTT).The core-shellshell upconversion nanoparticles(NaYF_(4):Yb,Er@NaYF_(4):Yb,Nd@NaGdF_(4):Nd,named as UCNP) were firstly synthesized using thermal decomposition method and then were coated by antimony shell over the surface of UCNP using simple cost and time effective new method.Furthermore,the surface of UCNP@Sb nanostructures was modified with DSPE-PEG in order to enhance the water solubility and biocompatibility.The final nanotheranostic agent,named as UCNP@Sb-PEG,exhibits very low toxicity,good biocompatibility,very good photothermal therapeutic effect,and efficient upconversion luminescence(UCL) imaging of HeLa cells under only one laser(808 nm) irradiation.The antimony shell is quenching the upconversion emission in pristine nanotheranostic agent,but interestingly,the UCL intensity of the agent recovers progressively under 808 nm laser irradiation due to light induced degradability of antimony shell.Besides,high longitudinal relaxivity(r_(1)) obtained from the experiment approves excellent potential of the nanotheranostic agent for T_(1)-weighted magnetic resonance imaging application.展开更多
Pulse diagnosis is an irreplaceable part of traditional Chinese medical science.However,application of the traditional pulse monitoring method was restricted in the modernization of Chinese medical science since it wa...Pulse diagnosis is an irreplaceable part of traditional Chinese medical science.However,application of the traditional pulse monitoring method was restricted in the modernization of Chinese medical science since it was difficult to capture real signals and integrate obscure feelings with a modern data platform.Herein,a novel multichannel pulse monitoring platform based on traditional Chinese medical science pulse theory and wearable electronics was proposed.The pulse sensing platform simultaneously detected pulse conditions at three pulse positions(Chi,Cun,and Guan).These signals were fitted to smooth surfaces to enable 3-dimensional pulse mapping,which vividly revealed the shape of the pulse length and width and compensated for the shortcomings of traditional single-point pulse sensors.Moreover,the pulse sensing system could measure the pulse signals from different individuals with different conditions and distinguish the differences in pulse signals.In addition,this system could provide full information on the temporal and spatial dimensions of a person’s pulse waveform,which is similar to the true feelings of doctors’fingertips.This innovative,cost-effective,easily designed pulse monitoring platform based on flexible pressure sensor arrays may provide novel applications in modernization of Chinese medical science or intelligent health care.展开更多
基金The National Key Research and Development Program of China under contract Nos 2018YFC1407000 and2016YFC1401500the National Natural Science Foundation of China under contract Nos 41806045 and 51579090。
文摘The systematic discrepancies in both tsunami arrival time and leading negative phase(LNP)were identified for the recent transoceanic tsunami on 16 September 2015 in Illapel,Chile by examining the wave characteristics from the tsunami records at 21 Deep-ocean Assessment and Reporting of Tsunami(DART)sites and 29 coastal tide gauge stations.The results revealed systematic travel time delay of as much as 22 min(approximately 1.7%of the total travel time)relative to the simulated long waves from the 2015 Chilean tsunami.The delay discrepancy was found to increase with travel time.It was difficult to identify the LNP from the near-shore observation system due to the strong background noise,but the initial negative phase feature became more obvious as the tsunami propagated away from the source area in the deep ocean.We determined that the LNP for the Chilean tsunami had an average duration of 33 min,which was close to the dominant period of the tsunami source.Most of the amplitude ratios to the first elevation phase were approximately 40%,with the largest equivalent to the first positive phase amplitude.We performed numerical analyses by applying the corrected long wave model,which accounted for the effects of seawater density stratification due to compressibility,self-attraction and loading(SAL)of the earth,and wave dispersion compared with observed tsunami waveforms.We attempted to accurately calculate the arrival time and LNP,and to understand how much of a role the physical mechanism played in the discrepancies for the moderate transoceanic tsunami event.The mainly focus of the study is to quantitatively evaluate the contribution of each secondary physical effect to the systematic discrepancies using the corrected shallow water model.Taking all of these effects into consideration,our results demonstrated good agreement between the observed and simulated waveforms.We can conclude that the corrected shallow water model can reduce the tsunami propagation speed and reproduce the LNP,which is observed for tsunamis that have propagated over long distances frequently.The travel time delay between the observed and corrected simulated waveforms is reduced to<8 min and the amplitude discrepancy between them was also markedly diminished.The incorporated effects amounted to approximately 78%of the travel time delay correction,with seawater density stratification,SAL,and Boussinesq dispersion contributing approximately 39%,21%,and 18%,respectively.The simulated results showed that the elastic loading and Boussinesq dispersion not only affected travel time but also changed the simulated waveforms for this event.In contrast,the seawater stratification only reduced the tsunami speed,whereas the earth’s elasticity loading was responsible for LNP due to the depression of the seafloor surrounding additional tsunami loading at far-field stations.This study revealed that the traditional shallow water model has inherent defects in estimating tsunami arrival,and the leading negative phase of a tsunami is a typical recognizable feature of a moderately strong transoceanic tsunami.These results also support previous theory and can help to explain the observed discrepancies.
基金supported in part by the National Natura Science Foundation of China(U2013602,61876181,51521003)the Nationa Key R&D Program of China(2020YFB13134)+2 种基金Shenzhen Science and Technology Research and Development Foundation(JCYJ20190813171009236)Beijing Nova Program of Science and Technology(Z191100001119043)the Youth Innovation Promotion Association,Chinese Academy of Sciences。
文摘Continual learning(CL)studies the problem of learning to accumulate knowledge over time from a stream of data.A crucial challenge is that neural networks suffer from performance degradation on previously seen data,known as catastrophic forgetting,due to allowing parameter sharing.In this work,we consider a more practical online class-incremental CL setting,where the model learns new samples in an online manner and may continuously experience new classes.Moreover,prior knowledge is unavailable during training and evaluation.Existing works usually explore sample usages from a single dimension,which ignores a lot of valuable supervisory information.To better tackle the setting,we propose a novel replay-based CL method,which leverages multi-level representations produced by the intermediate process of training samples for replay and strengthens supervision to consolidate previous knowledge.Specifically,besides the previous raw samples,we store the corresponding logits and features in the memory.Furthermore,to imitate the prediction of the past model,we construct extra constraints by leveraging multi-level information stored in the memory.With the same number of samples for replay,our method can use more past knowledge to prevent interference.We conduct extensive evaluations on several popular CL datasets,and experiments show that our method consistently outperforms state-of-the-art methods with various sizes of episodic memory.We further provide a detailed analysis of these results and demonstrate that our method is more viable in practical scenarios.
基金This research was supported by National Natural Science Foundation of China(Grant No.81903551)Natural Science Foundation of Zhejiang Province(Grant No.LYY22H300001)+3 种基金Wenzhou Municipal Science and Technology Bureau(Grant No.ZY2019007)Zhejiang postdoctoral scientific research project(Grant No.ZJ2021024)Wenzhou Municipal Key Laboratory of Pediatric Pharmacy(Grant No.WZEY02)Excellent Young Scientist Training Program fund from Wenzhou Medical University.
文摘Psoriasis is a chronic inflammatory skin disease characterized by erythema,scaling,and skin thickening.Topical drug application is recommended as the first-line treatment.Many formulation strategies have been developed and explored for enhanced topical psoriasis treatment.However,these preparations usually have low viscosity and limited retention on the skin surface,resulting in low drug delivery efficiency and poor patient satisfaction.In this study,we developed the first water-responsive gel(WRG),which has a distinct water-triggered liquid-to-gel phase transition property.Specifically,WRG was kept in a solution state in the absence of water,and the addition of water induced an immediate phase transition and resulted in a high viscosity gel.Curcumin was used as a model drug to investigate the potential of WRG in topical drug delivery against psoriasis.In vitro and in vivo data showed that WRG formulation could not only extend skin retention but also facilitate the drug permeating across the skin.In a mouse model of psoriasis,curcumin loaded WRG(CUR-WRG)effectively ameliorated the symptoms of psoriasis and exerted a potent anti-psoriasis effect by extending drug retention and facilitating drug penetration.Further mechanism study demonstrated that the anti-hyperplasia,anti-inflammation,anti-angiogenesis,anti-oxidation,and immunomodulation properties of curcumin were amplified by enhanced topical drug delivery efficiency.Notably,neglectable local or systemic toxicity was observed for CUR-WRG application.This study suggests that WRG is a promising formulation for topically psoriasis treatment.
基金The authors gratefully acknowledge the financial support of the National High-Tech Research and Development of China (No. 2004AA404260);the Science Foundation for Distingguished Young Scholars of Heilongjiang Province (No. JC-05-11) ;the Program for New Century Excellent Talents in University (No. NCET-04-0322).
文摘From the viewpoint of production engineering, microforming is considered as an effective process to fabricate various microparts. Several key problems in microforming processes were investigated. A new microforming apparatus with a high stiffness piezoelectric actuator as the punch driver was developed to produce microparts.To improve the forming abilities and locate the billets, a floating microdie was designed. The size effects of the billets and die cavities on the microforming abilities were studied with upsetting and coining tests, respectively.And the isothermal microforming process of microgears was performed with the developed microforming apparatus. Several analysis methods were used to evaluate the forming quality of the microparts.
基金inancially supported by the National Natural Science Foundation of China (81903551)Zhejiang Province Natural Science Foundation (LQ19H300001)Excellent Young Scientist Training Program fund from Wenzhou Medical University
文摘Psoriasis is a common chronic immune-mediated skin disease characterized by hyperproliferation and aberrant differentiation of keratinocytes and massive infiltration of inflammatory immune cells.Recent studies showed that Signal Transducer and Activator of Transcription 3(STAT3),which plays an important role in cell survival,proliferation,differentiation,angiogenesis,and immune responses,is constitutively activated in epidermal keratinocytes of human psoriatic skin lesions.In addition,STAT3 promotes the differentiation and expansion of T cells and facilitates cytokine production,thereby exacerbating the condition of psoriasis.Alantolactone(ALT)is a sesquiterpene lactone compound that could selectively suppress STAT3 activation,but its effectiveness and application in psoriasis treatment have not been determined.In this study,we developed ALT loaded chitosan/hyaluronic acid nanoparticles(CHALT),and investigated its therapeutic potential for psoriasis therapy.CHALT effectively abrogated the hyperproliferation by inducing ROS-mediated apoptosis with loss of mitochondrialmembrane potential,and also inhibited IL-6-induced STAT3 signaling activation and inflammatory reaction in HaCaT cell line.In an Imiquimod(IMQ)-induced psoriasis model,the topical treatment of psoriasis lesions with CHALT effectively attenuated the STAT3 hyperactivation within keratinocytes and ameliorated the symptoms of psoriasis.In addition,it was found that CHALT restricted the recruitment of immune cells.These results indicated that ALT-based nanoformulation CHALT holds great potential for psoriasis therapy.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFC3003800)the Asian Cooperation Fund Project(Grand No.99950410)。
文摘At 12:15 on January 15,2022(Beijing time),a massive eruption of the Hunga Tonga-Hunga Ha'apai volcano produced violent atmospheric fluctuations,which in turn generated a global tsunami through an abrupt air pressure shock upon the sea surface.Two main components of tsunami waves,phase-locked waves and free gravity waves,were identified by significant differences in propagating speeds across the deep ocean.The phase-locked wave propagated through the ocean basin synchronously with the atmospheric Lamb wave at an average speed of approximately 306 m/s,followed by the free gravity wave at a slower speed.The locked wave reached the coast of eastern Taiwan Island at about 20:00 on January 15,in coincidence with the Lamb wave arrival.However,on the coast of Chinese mainland,tidal gauges did not record tsunami signals until at least 2 h after the Lamb wave arrivals.Theoretical analyses and numerical experiments both suggested that as a result of the incoming wave shoaling above the vast continental shelf of Chinese mainland,the locked wave was no longer trapped by the air pressure shock and gradually transformed into freely-propagating shallow water waves by slowing down its propagation.Due to the longlasting planetary atmospheric fluctuations circling the earth many times,the sea level oscillations continuously propagated onto the Chinese shelf,which resulted in the tsunami waves excited along the Chinese coasts for at least 36 h.The maximum wave amplitude recorded on the coast of eastern Taiwan Island was 44 cm at Wushi,while on the coasts of eastern and southern Chinese mainland,the maximum amplitudes were 22 cm at Shipu and 13 cm at Zhuhai.Fourier and wavelet analyses were performed to identify the major components of the tsunami waves on the Chinese coasts.The results indicated that eastern Taiwan Island was impacted mainly by the waves with periods of approximately 10-40 min.Chinese mainland was hit by the evolved shallow water waves and subsequent free waves,with periods of approximately 40-100 and 16-20 min,respectively.
基金support from the National Natural Science Foundation of China(No.22275120)the Science and Technology Commission of Shanghai Municipality(No.22520711600).
文摘Luminescence quench is common in overdoped upconversion nanoparticles.Various methods have been proposed to counteract the adverse effects of concentration quenching on luminescence,but in upconversion nanoparticles that are highly doped with both sensitizers and activators,the factors that contribute to the diminishing of the emission cannot be summarized by a single cause.Herein,a core-shell design is used to spatially separate the sensitizer(Yb^(3+))and activator(Er^(3+))and to modulate the emission by changes in the distribution position as well as the concentration of the dopant ions in order to probe the factors affecting the luminescence.When the sensitizer ions are located in the core,the luminescence intensity of the nanoparticles is significantly weaker than that of the other distribution,which implies that the effect of sensitizer and activator on luminescence in the highly doped state has a different and more complex mechanism.The intensity of the emission is more affected by Yb^(3+)than Er^(3+),which includes not only the self-quenching of Yb^(3+),but also the dominance in the Yb^(3+)-Er^(3+)cross-relaxation.In this finding may provide new ideas for revealing the reasons for the diminished luminescence of highly doped upconversion nanoparticles and thus for enhancing luminescence.
基金funded by National Key R&D Program of China to Fusheng Zha with Grant numbers 2020YFB13134Natural Science Foundation of China to Fusheng Zha with Grant numbers U2013602,52075115,51521003,61911530250.
文摘Artificial intelligence is currently achieving impressive success in all fields.However,autonomous navigation remains a major challenge for AI.Reinforcement learning is used for target navigation to simulate the interaction between the brain and the environment at the behavioral level,but the Artificial Neural Network trained by reinforcement learning cannot match the autonomous mobility of humans and animals.The hippocampus–striatum circuits are considered as key circuits for target navigation planning and decision-making.This paper aims to construct a bionic navigation model of reinforcement learning corresponding to the nervous system to improve the autonomous navigation performance of the robot.The ventral striatum is considered to be the behavioral evaluation region,and the hippocampal–striatum circuit constitutes the position–reward association.In this paper,a set of episode cognition and reinforcement learning system simulating the mechanism of hippocampus and ventral striatum is constructed,which is used to provide target guidance for the robot to perform autonomous tasks.Compared with traditional methods,this system reflects the high efficiency of learning and better Environmental Adaptability.Our research is an exploration of the intersection and fusion of artificial intelligence and neuroscience,which is conducive to the development of artificial intelligence and the understanding of the nervous system.
基金National Natural Science Foundation of China,61773139,Fusheng Zha51521003,Fusheng Zha+6 种基金52075115,Fusheng ZhaU2013602,Fusheng Zha61911530250,Fusheng ZhaShenzhen Science and Technology Research and Development Foundation,JCYJ20190813171009236,Fusheng ZhaShenzhen Science and Technology Program,KQTD2016112515134654,Fusheng ZhaSelf-Planned Task of State Key Laboratory of Robotics and System(HIT),SKLRS202001B,Fusheng ZhaSKLRS202110B,Fusheng Zha.
文摘The hippocampal formation of the brain contains a series of nerve cells related to environmental cognition and navigation.These cells can integrate their moment information and external perceptual information and acquire episodic cognitive memory.Through episodic cognition and memory,organisms can achieve autonomous navigation in complex environments.This paper mainly studies the strategy of robot episode navigation in complex environments.After exploring the environment,the robot obtains subjective environmental cognition and forms a cognition map.The grid cells information contained in the cognitive map can obtain the direction and distance of the target through vector calculation,which can get a shortcut through the inexperienced area.The synaptic connection of place cells in the cognitive map can be used as the topological relationship between episode nodes.When the target-oriented vector navigation encounters obstacles,the obstacles can be realized by setting closer sub-targets.Based on the known obstacle information obtained from boundary cells in the cognitive map,topological paths can be divided into multi-segment vector navigation to avoid encountering obstacles.This paper combines vector and topological navigation to achieve goal-oriented and robust navigation capability in a complex environment.
基金Acknowledgment This work was supported by the National Hi-tech Research and Development Program of China (863 Program, Grant No. 2011AA040701), and the National Natural Science Foundation of China (No. 61375097, No. 61175107)
文摘Legged robots have better performance on discontinuous terrain than that of wheeled robots. However, the dynamic trotting and balance control of a quadruped robot is still a challenging problem, especially when the robot has multi-joint legs. This paper presents a three-dimensional model of a quadruped robot which has 6 Degrees of Freedom (DOF) on torso and 5 DOF on each leg. On the basis of the Spring-Loaded Inverted Pendulum (SLIP) model, body control algorithm is discussed in the first place to figure out how legs work in 3D trotting. Then, motivated by the principle of joint function separation and introducing certain biological characteristics, two joint coordination approaches are developed to produce the trot and provide balance. The robot reaches the highest speed of 2.0 m.s-1, and keeps balance under 250 Kg.m.s-1 lateral disturbance in the simulations. The effectiveness of these approaches is also verified on a prototype robot which runs to 0.83 m.s-1 on the treadmill, The simulations and experiments show that legged robots have good biological properties, such as the ground reaction force, and spring-like leg behavior.
基金Projects supported by the National Natural Science Foundation of China(21571125,51872183,51672171)National Key R&D Program of China(2016YFE0114800)
文摘Rare earth doped upconversion nanoparticles can be considered as the spice of research in the field of luminescence nanomaterials due to their unique optical properties such as near-infrared excitation.Enormous works have been reported about biomedical applications of 980 nm excited and Yb^3+-sensitized upconversion nanoparticles.However,980 nm excitation wavelength overlaps with the absorption band of water molecules in the biological environment,leading to overheating effect that can induce thermal damages of normal cells and tissues.Recently,Nd^3+-sensitized upconversion nanoparticles which can be excited with 808 nm has been widely investigated as alternative nanoparticles that can surmount this issue of overheating effect.Even though Nd^3+-sensitized upconversion nanoparticles can reduce the overheating effect by 20 fold as compared to Yb^3+-sensitized counterpart,there are several factors that reduce the upconversion luminescence intensity.In this review article,photon energy harvesting and transferring mechanisms in Nd^3+,Yb^3+and emitter ions co-doped upconversion nanoparticles under 808 nm excitation are briefly discussed.Factors that affect upconversion luminescence intensity and quantum yield of Nd^3+-sensitized upconversion nanoparticles are also addressed.Besides,some of the important strategies that have been recently utilized to boost upconversion luminescence intensity of Nd^3+sensitized upco nversion nanoparticles are tho roughly summarized.Lastly,the future challenges in the area and our perspectives are in sight.
基金Acknowledgments This work is supported by the National Hi-tech Research and Development Program of China (863 Program, Grant no. 2011AA0403837002), the National Natural Science Foundation of China (No. 61005076, No. 61175107), and the Self-Planned Task (No. SKLRS201006B) of the State Key Laboratory of Ro- botics and System (HIT).
文摘The realization of a high-speed running robot is one of the most challenging problems in developing legged robots. The excellent performance of cheetahs provides inspiration for the control and mechanical design of such robots. This paper presents a three-dimensional model of a cheetah that predicts the locomotory behaviors of a running cheetah. Applying biological knowledge of the neural mechanism, we control the muscle flexion and extension during the stance phase, and control the positions of the joints in the flight phase via a PD controller to minimize complexity. The proposed control strategy is shown to achieve similar locomotion of a real cheetah. The simulation realizes good biological properties, such as the leg retraction, ground reaction force, and spring-like leg behavior. The stable bounding results show the promise of the controller in high-speed locomotion. The model can reach 2.7 m-s^-1 as the highest speed, and can accelerate from 0 to 1.5 m-s^-1 in one stride cycle. A mechanical structure based on this simulation is designed to demonstrate the control approach, and the most recently developed hindlimb controlled by the proposed controller is presented in swinging-leg experiments and jump-force experiments.
基金This research was financially supported by the National High Technology Research and Development Program 863 of China (Grant No. 2008AA04Z211), the National Natural Science Foundation of China (Grant No.60901074, Grant No.61175107) and State Key Laboratory of Robotics and System (Grant No. SKLRS 200901A02).
文摘A CPG control mechanism is proposed for hopping motion control of biped robot in unpredictable environment. Based on analysis of robot motion and biological observation of animal's control mechanism, the motion control task is divided into two simple parts: motion sequence control and output force control. Inspired by a two-level CPG model, a two-level CPG control mechanism is constructed to coordinate the drivers of robot joint, while various feedback information are introduced into the control mechanism. Interneurons within the control mechanism are modeled to generate motion rhythm and pattern promptly for motion sequence control; motoneurons are modeled to control output forces of joint drivers in real time according to feedbacks. The control system can perceive changes caused by unknown perturbations and environment changes according to feedback information, and adapt to unpredictable environment by adjusting outputs of neurons. The control mechanism is applied to a biped hopping robot in unpredictable environment on simulation platform, and stable adaptive motions are obtained.
基金Project supported by the National Natural Science Foundation of China(51872183)"Shuguang Program"supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(19SG38)the National Basic Research Program of China(2016YFA0201600)。
文摘Manganese-zinc ferrite is a kind of very important magnetic ferrite material.The properties of wide absorption band,sensitivity to ultraviolet(UV)light and tumor H_(2)O_(2) promise it to be possibly used as a photothermal therapy(PTT),photodynamic therapy(PDT)and chemodynamic therapy(CDT)agent.Based on the unique advantages of rare-earth doped nanoparticles,an Er^(3+),Tm^(3+)co-doped upconversion-mediated nanosystem with manganese-zinc ferrite shell(named as UCNPS@M)was developed through a facile thermal co-decomposition method.The final nanosystems were surface-modified by using dopamine hydrochloride(DA)in order to warrant good biocompatibility(named as UCNPS@M@DA).Under irradiation of near-infrared(NIR)light,UCNPS emit both ultraviolet and visible light.The UV light is mostly abso rbed by manga nese-zinc ferrite shell to produce reactive oxygen species(ROS),which is essential to the potential PDT and CDT effect of nanosystems,and at the same time,Mn_(0.5)Zn_(0.5)Fe2O_(4) can further react with H_(2)O_(2) to promote the efficiency of OH-generation.It is expected that UCNPS@M@DA can act as upconversion luminescence imaging guidance due to the visible emission from UCNPS.In addition,the energy absorbed by the nanosystems can be transferred to heat to realize photothermal effect.Moreover,UCNPS@M@DA was successfully applied as a T_(1)/T_(2)-weighted magnetic resonance imaging(MRI)contrast agent due to the existence of Gd,Mn,and Fe elements.In light of the upconversion luminescence(UCL)imaging from the UCNPS as well as potential PTT,PDT,CDT effect mentioned above,this work provides a possibility to realize cancer multi-model bioimaging guided treatment by using an all-in-one diagnosis and therapy nanosystem through a simple yet powerful strategy.
基金This work was partially supported by the National Natural Science Foundation of China(No.U1713218)the National Key R&D Program of China(No.2018YFB1307700).
文摘Throat cancer treatment involves surgical removal of the tumor,leaving patients with facial disfigurement as well as temporary or permanent loss of voice.Surface electromyography(sEMG)generated from the jaw contains lots of voice information.However,it is difficult to record because of not only the weakness of the signals but also the steep skin curvature.This paper demonstrates the design of an imperceptible,flexible epidermal sEMG tattoo-like patch with the thickness of less than 10μm and peeling strength of larger than 1N cm−1 that exhibits large adhesiveness to complex biological surfaces and is thus capable of sEMG recording for silent speech recognition.When a tester speaks silently,the patch shows excellent performance in recording the sEMG signals from three muscle channels and recognizing those frequently used instructions with high accuracy by using the wavelet decomposition and pattern recognization.The average accuracy of action instructions can reach up to 89.04%,and the average accuracy of emotion instructions is as high as 92.33%.To demonstrate the functionality of tattoo-like patches as a new human–machine interface(HMI)for patients with loss of voice,the intelligent silent speech recognition,voice synthesis,and virtual interaction have been implemented,which are of great importance in helping these patients communicate with people and make life more enjoyable.
基金The research was funded by the National Natural Science Foundation of China(Grant No.51872183)"Shuguang Program"supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(No.19SG38).
文摘The continuously growing importance of information storage,transmission,and authentication impose many new demands and challenges for modern nano-photonic materials and information storage technologies,both in security and storage capacity.Recently,luminescent lanthanide-doped nanomaterials have drawn much attention in this field because of their photostability,multimodal/multicolor/narrowband emissions,and long luminescence lifetime.Here,we report a multimodal nanocomposite composed of lanthanide-doped upconverting nanoparticle and EuSe semiconductor,which was constructed by utilizing a cation exchange strategy.The nanocomposite can emit blue and white light under 365 and 394 nm excitation,respectively.Meanwhile,the nanocomposites show different colors under 980 nm laser excitation when the content of Tb3+ions is changed in the upconversion nanoparticles.Moreover,the time-gating technology is used to filter the upconversion emission of a long lifetime from Tb3+or Eu3+,and the possibilities for modulating the emission color of the nanocomposites are further expanded.Based on the advantage of multiple tunable luminescence,the nanocomposites are designed as optical modules to load optical information.This work enables multi-dimensional storage of information and provides new insights into the design and fabrication of next-generation storage materials.
文摘In this paper a bio-inspired approach of velocity control for a quadruped robot running with a bounding gait on compliant legs is set up. The dynamic properties ofa sagittal plane model of the robot are investigated. By analyzing the stable fixed points based on Poincare map, we find that the energy change of the system is the main source for forward velocity adjustment. Based on the analysis of the dynamics model of the robot, a new simple linear running controller is proposed using the energy control idea, which requires minimal task level feedback and only controls both the leg torque and ending impact angle. On the other hand, the functions of mammalian vestibular reflexes are discussed, and a reflex map between forward velocity and the pitch movement is built through statistical regression analysis. Finally, a velocity controller based on energy control and vestibular reflexes is built, which has the same structure as the mammalian nervous mechanism for body posture control. The new con- troller allows the robot to run autonomously without any other auxiliary equipment and exhibits good speed adjustment capa- bility. A series simulations and experiments were set to show the good movement agility, and the feasibility and validity of the robot system.
基金Project supported by the National Natural Science Foundation of China(51872183)"Shuguang Program"supported by Shanghai Education Development Foundation+1 种基金Shanghai Municipal Education Commission(19SG38)the National Basic Research Program of China(2016YFA0201600)。
文摘Combining treatment and diagnosis,called theranostics,which is achieved within single nanoparticle is an ultimate goal of many studies.Herein,we developed a new nanotheranostic agent-Nd^(3+)-sensitized upconversion nanoparticles core for dual modal imaging(i.e.,upconversion luminescence imaging and magnetic resonance imaging) and antimony nanoshell for photothermal therapy(PTT).The core-shellshell upconversion nanoparticles(NaYF_(4):Yb,Er@NaYF_(4):Yb,Nd@NaGdF_(4):Nd,named as UCNP) were firstly synthesized using thermal decomposition method and then were coated by antimony shell over the surface of UCNP using simple cost and time effective new method.Furthermore,the surface of UCNP@Sb nanostructures was modified with DSPE-PEG in order to enhance the water solubility and biocompatibility.The final nanotheranostic agent,named as UCNP@Sb-PEG,exhibits very low toxicity,good biocompatibility,very good photothermal therapeutic effect,and efficient upconversion luminescence(UCL) imaging of HeLa cells under only one laser(808 nm) irradiation.The antimony shell is quenching the upconversion emission in pristine nanotheranostic agent,but interestingly,the UCL intensity of the agent recovers progressively under 808 nm laser irradiation due to light induced degradability of antimony shell.Besides,high longitudinal relaxivity(r_(1)) obtained from the experiment approves excellent potential of the nanotheranostic agent for T_(1)-weighted magnetic resonance imaging application.
基金This work was funded by the National Natural Science Foundation of China(Nos.61773372,62173240 and 62073229)the National Key Research and Development Program of China(2018YFB1307700)the Jiangsu Province Outstanding Youth Foundation(No.BK20160058)。
文摘Pulse diagnosis is an irreplaceable part of traditional Chinese medical science.However,application of the traditional pulse monitoring method was restricted in the modernization of Chinese medical science since it was difficult to capture real signals and integrate obscure feelings with a modern data platform.Herein,a novel multichannel pulse monitoring platform based on traditional Chinese medical science pulse theory and wearable electronics was proposed.The pulse sensing platform simultaneously detected pulse conditions at three pulse positions(Chi,Cun,and Guan).These signals were fitted to smooth surfaces to enable 3-dimensional pulse mapping,which vividly revealed the shape of the pulse length and width and compensated for the shortcomings of traditional single-point pulse sensors.Moreover,the pulse sensing system could measure the pulse signals from different individuals with different conditions and distinguish the differences in pulse signals.In addition,this system could provide full information on the temporal and spatial dimensions of a person’s pulse waveform,which is similar to the true feelings of doctors’fingertips.This innovative,cost-effective,easily designed pulse monitoring platform based on flexible pressure sensor arrays may provide novel applications in modernization of Chinese medical science or intelligent health care.