A ratiometric fluorescence probe,NClO,for the rapid and selective detection of HClO had been designed and synthesized based on a 1,8-naphthalimide derivative.Probe NClO displayed a red emission(λmax=615 nm).In the pr...A ratiometric fluorescence probe,NClO,for the rapid and selective detection of HClO had been designed and synthesized based on a 1,8-naphthalimide derivative.Probe NClO displayed a red emission(λmax=615 nm).In the presence of HClO,the solution of probe NClO gave off a strong green fluorescence(λem,max=520 nm)with a rapid response(within seconds).This probe had been applied to image HClO in living cells and zebra fish.展开更多
A thermal–hydraulic model was developed to analyze the three-dimensional(3D)temperature field of a graphite-moderated channel-type molten salt reactor(GMC-MSR).This model solves the temperature distribution of both t...A thermal–hydraulic model was developed to analyze the three-dimensional(3D)temperature field of a graphite-moderated channel-type molten salt reactor(GMC-MSR).This model solves the temperature distribution of both the graphite moderator and fuel salt using a single convection–diffusion equation.Heat transfer at the interface between the fuel salt and graphite was addressed by introducing an additional thermal resistance component at the interface and modifying the anisotropic thermal conductivity of the fuel salt.The mass flow distribution in different flow passages was determined by adjusting the mass flow rate until a uniform pressure drop was achieved across all fuel channels.This thermal–hydraulic model,constructed on COMSOL Multiphysics,was verified by comparing its temperature results with those from the RELAP5 code across two demonstration cases.A steady-state thermal–hydraulic simulation of this model was performed to evaluate the conceptual design of a 2-MW experimental molten salt reactor(2MW-MSR).In addition,detailed discussions of the 3D temperature field,heat flux,and mass flow distribution of the 2MW-MSR were presented.This model allows for a comprehensive 3D thermal–hydraulic analysis of the GMC-MSR.Moreover,it only requires the solution of a single convection–diffusion equation,which makes it invaluable for GMC-MSR design.展开更多
In the core of a molten salt fast reactor(MSFR),heavy metal fuel and fission products can be dissolved in a molten fluoride salt to form a eutectic mixture that acts as both fuel and coolant.Fission energy is released...In the core of a molten salt fast reactor(MSFR),heavy metal fuel and fission products can be dissolved in a molten fluoride salt to form a eutectic mixture that acts as both fuel and coolant.Fission energy is released from the fuel salt and transferred to the second loop by fuel salt circulation.Therefore,the MSFR is characterized by strong interaction between the neutronics and the thermal hydraulics.Moreover,recirculation flow occurs,and nuclear heat is accumulated near the fertile blanket,which significantly affects both the flow and the temperature fields in the core.In this work,to further optimize the conceptual geometric design of the MSFR,three geometries of the core and fertile blanket are proposed,and the thermal-hydraulic characteristics,including the three-dimensional flow and temperature fields of the fuel and fertile salts,are simulated and analyzed using a coupling scheme between the open source codes OpenMC and OpenFOAM.The numerical results indicate that a flatter core temperature distribution can be obtained and the hot spot and flow stagnation zones that appear in the upper and lower parts of the core center near the reflector can be eliminated by curving both the top and bottom walls of the core.Moreover,eight cooling loops with a total flow rate of0.0555 m3 s-1 ensur an acceptable temperature distribusure an acceptable temperature distribution in the fertile blanket.展开更多
Background: The high mortality of pre-weanling piglets is a dominant challenge which severely restricts the development of pig industry. A number of factors including nutrients imbalance and temperature variation duri...Background: The high mortality of pre-weanling piglets is a dominant challenge which severely restricts the development of pig industry. A number of factors including nutrients imbalance and temperature variation during postnatal period of piglets have been reported to closely associated with the high mortality of postnatal piglets.This study aims to find out the relationship between fat deposition and survival of newborn piglets.Results: There were no differences in organ coefficient and bone density between the surviving and dead piglets(P > 0.05). The body weight and the fat deposition in the dead piglets were lower than the live individuals(P < 0.05).Consistently, the average sizes of white adipocytes in back and abdominal adipose tissues of dead piglets were smaller than the survivals(P < 0.05). The protein expression levels of adipocyte differentiation markers PPARγ and C/EBPα in the back and abdominal adipose tissues were lower in dead piglets compared to live piglets. The mRNA expressions of thermogenic markers PGC1α and PRDM16 in adipose tissues were decreased in the dead piglets(P < 0.05). The microarray of back fat samples from the surviving and dead piglets were conducted; two down-regulated genes namely AAMDC and CASTOR1 were identified from the dead piglets. According to quantitative real-time PCR(RT-PCR) analysis, the mRNA expression of AAMDC decreased, whereas CASTOR1 expression elevated in the dead piglets compared to the surviving piglets(P < 0.05).Conclusions: The fat deposition and adipocyte differentiation in the dead piglets are insufficient compared to the surviving piglets, which may attenuate the thermogenic ability of white adipose tissue(WAT). Our data indicate that fat deposition in newborn piglets is vital to their survival.展开更多
The long-term spatiotemporal changes of surface biogenic elements in the Changjiang River Estuary and adjacent waters during the summer of 2008–2016 were analyzed in this study.The concentrations of dissolved inorgan...The long-term spatiotemporal changes of surface biogenic elements in the Changjiang River Estuary and adjacent waters during the summer of 2008–2016 were analyzed in this study.The concentrations of dissolved inorganic nitrogen(DIN),soluble reactive phosphate(PO_(4)^(3−))and silicate(SiO_(3)^(2−))were generally stable,with a slight decrease of DIN and PO_(4)^(3−),and a slight increase of SiO_(3)^(2−),which mainly occurred in the estuarine waters.The grey correlation analysis was carried out between biogenic elements and chlorophyll a(Chl-a).Results showed that compared with the absolute values of biogenic elements,the correlations between the concentration ratio of nitrogen to phosphorus(N/P),ratio of silicon to nitrogen(Si/N)and Chl-a were closer,indicating the important influence on phytoplankton by the structure of biogenic elements.The study area was generally in a state of potential P limitation,and could have potential impact on the phytoplankton community,triggering the shift of red tide dominant species from diatoms to dinoflagellates.展开更多
Bone metastasis,a life-threatening complication of advanced breast cancer,is often accompanied by debilitating pain(cancer-induced bone pain,CIBP)that severely impairs life quality and survival.The concurrent treatmen...Bone metastasis,a life-threatening complication of advanced breast cancer,is often accompanied by debilitating pain(cancer-induced bone pain,CIBP)that severely impairs life quality and survival.The concurrent treatment of bone metastases and CIBP remains a clinical challenge because the therapeutic options are limited.In this study,we construct a near-infrared light-activated nano-therapeutic system to meet this conundrum.In detail,sorafenib(SRF)and photosensitizer(chlorin e6,Ce6)are encapsulated into mesoporous hydroxyapatite nanoparticles(HANPs),which are further functionalized with hyaluronic acid(HA)to obtain HA-SRF/Ce6@HANPs system.The designed nanoplatform destroys tumor cells in vitro and in vivo via the synergism of SRF(interrupting the exchange of cystine/glutamate by inhibiting SLC7A11)and photodynamic therapy(PDT,inducing reactive oxygen species generation).The decrease in tumor burden and reduction of extracellular glutamate significantly attenuate CIBP in mice model with developing bone cancer.Moreover,the combination of HA-SRF/Ce6@HANPs and PDT inhibit osteoclasts activation,promote osteoblast differentiation and accelerate bone repair.Overall,the nanoagent with good biocompatibility may provide an effective therapy method for the concurrent treatment of breast cancer bone metastasis and CIBP.展开更多
The research aimed to study absorption and reduction of PM_(2.5)by different plant community structure,and explore which plant community can have better or best comprehensive absorption efficiency,thereby improving an...The research aimed to study absorption and reduction of PM_(2.5)by different plant community structure,and explore which plant community can have better or best comprehensive absorption efficiency,thereby improving and optimizing urban vegetation structure,further promoting improvement of urban air quality,improving people's quality of life,and ensuring a good living environment.In this paper,the method of quadrat survey commonly used in field survey was adopted to record the height,coverage,DBH and other indicators of statistical plants,and corresponding comprehensive value was calculated through these indexes.PM_(2.5)was measured at forest edge,4 and 8 m in the forest,with three repetitions.Subtraction amount of PM_(2.5)determined at different layers was analyzed,as well as its relationship with comprehensive value of community structure.The results showed that PM_(2.5)amount decreased significantly at forest edge,4 and 8 m in the forest,and better community structure had a positive effect on PM_(2.5)absorption.The higher the comprehensive indexes of community structure such as plant height,DBH(arbor),density and coverage,the better the ability of absorbing and reducing PM_(2.5).Therefore,it must pay attention to the diversity of plant species per unit area,to build a good plant community structure,which could better improve structure of local ecosystem,and play a good role in absorbing and reducing PM_(2.5)pollutants in the atmosphere.展开更多
In this work, monodispersed, well-shaped platinum (3.2 - 6.4 nm), rhodium (2.4 - 5.1 nm), palladium (3.2 - 5.3 nm) nanoparticles capped with poly(vinylpyrrolidone) were synthesized by a polyol reduction method in an e...In this work, monodispersed, well-shaped platinum (3.2 - 6.4 nm), rhodium (2.4 - 5.1 nm), palladium (3.2 - 5.3 nm) nanoparticles capped with poly(vinylpyrrolidone) were synthesized by a polyol reduction method in an ethylene glycol solution at temperature of 190℃. The influences of synthetic parameters on the size and morphology of the noble metal nanoparticles have been systematically investigated. The noble metal nanoparticles were characterized by means of UV-vis, laser scattering particle size distribution analysis (LSPSDA) and transmission electron microscopy (TEM). The experimental results showed that the particle size of metals nanoparticles, the morphology of which was spherical, increased with the raise of metal precursor concentration as well as the amount of PVP. The optimal molar ratio of PVP/metal and metal precursor concentration for the fabrication of Pt, Rh, and Pd nanoparticles with uniform distribution were 10 and 0.1 mM, respectively. The morphologies of the Rh nanoparticles with the size of 5.1 nm were polygons, including hexagons, pentagons, and triangles.展开更多
Analysing the influence mechanism of the riblet protrusion height on turbulent drag components is more beneficial in organising the vortical structure over the riblet surface.Therefore, the Large Eddy Simulation(LES) ...Analysing the influence mechanism of the riblet protrusion height on turbulent drag components is more beneficial in organising the vortical structure over the riblet surface.Therefore, the Large Eddy Simulation(LES) is used to investigate the vortex structure over the riblet surface with different protrusion heights. Then, the variations of Reynolds stress and viscous shear stress in a turbulent channel are analysed. As a result, the drag reduction rate increases from3.4% when the riblets are completely submerged in the turbulent boundary layer to 7.9% when the protrusion height is 11.2. Further analysis shows that the protrusion height affects the streamwise vortices and the normal diffusivity of spanwise and normal vortices, thus driving the variation of Reynolds stress. Compared with the smooth surface, the vorticity strength and the number of streamwise vortices are weakened near the wall but increase in the logarithmic layer with increased protrusion height. Meanwhile, the normal diffusivity of spanwise vorticity decreases with the increase of protrusion height, and the normal diffusivity of normal vorticity is the smallest when the protrusion height is 11.2. Moreover, the protrusion height affects the velocity gradient of the riblet tip and riblet valley, thus driving the variation of viscous shear stress. With the increase of protrusion height, the velocity gradient of the riblet tip increases dramatically but decreases in the riblet valley.展开更多
We present the effect of disorder on the optical conductivity of two-dimensional inhomogeneous superconductors by applying the kernel polynomial method to solve the Bogoliubov-de Gennes equations. By means of the latt...We present the effect of disorder on the optical conductivity of two-dimensional inhomogeneous superconductors by applying the kernel polynomial method to solve the Bogoliubov-de Gennes equations. By means of the lattice size scaling of the generalized inverse participation ratio, we find that the localization length of the quasiparticle decreases significantly with the increase of the disorder strength. Meanwhile, the weak disorder can readily restrain the Drude weight, while the superconducting gap has the tendency to suppress the low-energy optical conductivity. We also employ the Lanczos exact diagonalization method to study the competition between the on-site repulsive interactions and disorder. It is shown that the screening effect of repulsive interactions significantly enhances the Drude weight in the normal phase.展开更多
Acupuncture is a traditional Chinese medicine therapy originated in China.In recent years,acupuncture is widely used in the field of neurological diseases,especially in the acute stage of stroke.Its mechanism of actio...Acupuncture is a traditional Chinese medicine therapy originated in China.In recent years,acupuncture is widely used in the field of neurological diseases,especially in the acute stage of stroke.Its mechanism of action is becoming clearer;one of the possible mechanisms is its bidirectional benign regulation.展开更多
Leonurus is one of the commonly used clinical drugs in traditional Chinese medicine.In recent years,leonurus has been widely used for cerebrovascular diseases.With the deepening of research,the effect of its main comp...Leonurus is one of the commonly used clinical drugs in traditional Chinese medicine.In recent years,leonurus has been widely used for cerebrovascular diseases.With the deepening of research,the effect of its main component,leonurine,on the central nervous system has become clearer,and its mechanism has been confirmed and explained from many aspects.For reference,this paper discusses the latest research on the neuroprotective effect of leonurine on ischemic stroke at home and abroad in recent years.展开更多
To overcome the limitations of traditional exoskeletons in complex outdoor terrains,this study introduces a novel lower limb exoskeleton inspired by the snow leopard’s forelimb musculoskeletal structure.It features a...To overcome the limitations of traditional exoskeletons in complex outdoor terrains,this study introduces a novel lower limb exoskeleton inspired by the snow leopard’s forelimb musculoskeletal structure.It features a non-fully anthropomorphic design,attaching only at the thigh and ankle with a backward-knee configuration to mimic natural human knee movement.The design incorporates a single elastic element at the hip for gravity compensation and dual elastic elements at the knee for terrain adaptability,which adjust based on walking context.The design’s effectiveness was assessed by measuring metabolic cost reduction and motor output torque under various walking conditions.Results showed significant metabolic cost savings of 5.8–8.8%across different speeds and a 7.9%reduction during 9°incline walking on a flat indoor surface.Additionally,the spring element decreased hip motor output torque by 7–15.9%and knee torque by 8.1–14.2%.Outdoor tests confirmed the design’s robustness and effectiveness in reducing motor torque across terrains,highlighting its potential to advance multi-terrain adaptive exoskeleton research.展开更多
The study of exoskeletons has been a popular topic worldwide.However,there is still a long way to go before exoskeletons can be widely used.One of the major challenges is control,and there is no specific research tren...The study of exoskeletons has been a popular topic worldwide.However,there is still a long way to go before exoskeletons can be widely used.One of the major challenges is control,and there is no specific research trend for controlling exoskeletons.In this paper,we propose a novel exoskeleton control strategy that combines Active Disturbance Rejection Control(ADRC)and Deep Reinforcement Learning(DRL).The dynamic model of the exoskeleton is constructed,followed with the design of the ADRC.To automatically adjust the control parameters of the ADRC,the Twin-Delayed Deep Deterministic Policy Gradient(TD3)is utilized.Then a reward function is defined in terms of the joint angle,angular velocity,and their errors to the desired values,to maximize the accuracy of the joint angle.In the simulations and experiments,a conventional ADRC,and ADRC based on Genetic Algorithm(GA)and Particle Swarm Optimization(PSO)were carried out for comparison with the proposed control method.The results of the tests show that TD3-ADRC has a rapid response,small overshoot,and low Mean Absolute Error(MAE)and Root Mean Square Error(RMSE)followed with the desired,demonstrating the superiority of the proposed control method for the self-learning control of exoskeleton.展开更多
To improve the wear resistance of aluminum alloy frictional parts, Ti B2particles reinforced Ni-base alloy composite coatings were prepared on aluminum alloy 7005 by laser cladding. The microstructure and tribological...To improve the wear resistance of aluminum alloy frictional parts, Ti B2particles reinforced Ni-base alloy composite coatings were prepared on aluminum alloy 7005 by laser cladding. The microstructure and tribological properties of the composite coatings were investigated. The results show that the composite coating contains the phases of Ni Al, Ni3Al, Al3Ni2, TiB2, TiB, TiC, CrB, and Cr23C6.Its microhardness is HV0.5855.8, which is 15.4 % higher than that of the Ni-base alloy coating and is 6.7 times as high as that of the aluminum alloy. The friction coefficients of the composite coatings are reduced by 6.8 %–21.6 % and 13.2 %–32.4 % compared with those of the Ni-base alloy coatings and the aluminum alloys, while the wear losses are 27.4 %–43.2 % less than those of the Ni-base alloy coatings and are only 16.5 %–32.7 % of those of the aluminum alloys at different loads. At the light loads ranging from 3 to 6 N, the calculated maximum contact stress is smaller than the elastic limit contact stress. The wear mechanism of the composite coatings is micro-cutting wear, but changes into multi-plastic deformation wear at 9 N due to the higher calculated maximum contact stress than the elastic limit contact stress. As the loads increase to 12 N, the calculated flash temperature rises to 332.1 °C.The composite coating experiences multi-plastic deformation wear, micro-brittle fracture wear, and oxidative wear.展开更多
In recent years,sEMG(surface electromyography)signals have been increasingly used to operate wearable devices.The development of mechanical lower limbs or exoskeletons controlled by the nervous system requires greater...In recent years,sEMG(surface electromyography)signals have been increasingly used to operate wearable devices.The development of mechanical lower limbs or exoskeletons controlled by the nervous system requires greater accuracy in recognizing lower limb activity.There is less research on devices to assist the human body in uphill movements.However,developing controllers that can accurately predict and control human upward movements in real-time requires the employment of appropriate signal pre-processing methods and prediction algorithms.For this purpose,this paper investigates the effects of various sEMG pre-processing methods and algorithms on the prediction results.This investigation involved ten subjects(five males and five females)with normal knee joints.The relevant data of the subjects were collected on a constructed ramp.To obtain feature values that reflect the gait characteristics,an improved PCA algorithm based on the kernel method is proposed for dimensionality reduction to remove redundant information.Then,a new model(CNN+LSTM)was proposed to predict the knee joint angle.Multiple approaches were utilized to validate the superiority of the improved PCA method and CNN-LSTM model.The feasibility of the method was verified by analyzing the gait prediction results of different subjects.Overall,the prediction time of the method was 25 ms,and the prediction error was 1.34±0.25 deg.By comparing with traditional machine learning methods such as BP(backpropagation)neural network,RF(random forest),and SVR(support vector machine),the improved PCA algorithm processed data performed the best in terms of convergence time and prediction accuracy in CNN-LSTM model.The experimental results demonstrate that the proposed method(improved PCA+CNN-LSTM)effectively recognizes lower limb activity from sEMG signals.For the same data input,the EMG signal processed using the improved PCA method performed better in terms of prediction results.This is the first step toward myoelectric control of aided exoskeleton robots using discrete decoding.The study results will lead to the future development of neuro-controlled mechanical exoskeletons that will allow troops or disabled individuals to engage in a greater variety of activities.展开更多
This paper describes a novel gait pattern recognition method based on Long Short-Term Memory(LSTM)and Convolutional Neural Network(CNN)for lower limb exoskeleton.The Inertial Measurement Unit(IMU)installed on the exos...This paper describes a novel gait pattern recognition method based on Long Short-Term Memory(LSTM)and Convolutional Neural Network(CNN)for lower limb exoskeleton.The Inertial Measurement Unit(IMU)installed on the exoskeleton to collect motion information,which is used for LSTM-CNN input.This article considers five common gait patterns,including walking,going up stairs,going down stairs,sitting down,and standing up.In the LSTM-CNN model,the LSTM layer is used to process temporal sequences and the CNN layer is used to extract features.To optimize the deep neural network structure proposed in this paper,some hyperparameter selection experiments were carried out.In addition,to verify the superiority of the proposed recognition method,the method is compared with several common methods such as LSTM,CNN and SVM.The results show that the average recognition accuracy can reach 97.78%,which has a good recognition eff ect.Finally,according to the experimental results of gait pattern switching,the proposed method can identify the switching gait pattern in time,which shows that it has good real-time performance.展开更多
基金supported by the National Natural Science Foundation of China(No.U1608222)the State Key Laboratory of Fine Chemicals(No.KF1606)the financial support from Fundamental Research Funds for the Central Universities of Central South University(No.2018zzts109)
文摘A ratiometric fluorescence probe,NClO,for the rapid and selective detection of HClO had been designed and synthesized based on a 1,8-naphthalimide derivative.Probe NClO displayed a red emission(λmax=615 nm).In the presence of HClO,the solution of probe NClO gave off a strong green fluorescence(λem,max=520 nm)with a rapid response(within seconds).This probe had been applied to image HClO in living cells and zebra fish.
基金supported by the National Natural Science Foundation of China(No.12075169)。
文摘A thermal–hydraulic model was developed to analyze the three-dimensional(3D)temperature field of a graphite-moderated channel-type molten salt reactor(GMC-MSR).This model solves the temperature distribution of both the graphite moderator and fuel salt using a single convection–diffusion equation.Heat transfer at the interface between the fuel salt and graphite was addressed by introducing an additional thermal resistance component at the interface and modifying the anisotropic thermal conductivity of the fuel salt.The mass flow distribution in different flow passages was determined by adjusting the mass flow rate until a uniform pressure drop was achieved across all fuel channels.This thermal–hydraulic model,constructed on COMSOL Multiphysics,was verified by comparing its temperature results with those from the RELAP5 code across two demonstration cases.A steady-state thermal–hydraulic simulation of this model was performed to evaluate the conceptual design of a 2-MW experimental molten salt reactor(2MW-MSR).In addition,detailed discussions of the 3D temperature field,heat flux,and mass flow distribution of the 2MW-MSR were presented.This model allows for a comprehensive 3D thermal–hydraulic analysis of the GMC-MSR.Moreover,it only requires the solution of a single convection–diffusion equation,which makes it invaluable for GMC-MSR design.
基金supported by the Chinese TMSR Strategic Pioneer Science and Technology Project(No.XDA02010000)the Frontier Science Key Program of the Chinese Academy of Sciences(No.QYZDY-SSW-JSC016)。
文摘In the core of a molten salt fast reactor(MSFR),heavy metal fuel and fission products can be dissolved in a molten fluoride salt to form a eutectic mixture that acts as both fuel and coolant.Fission energy is released from the fuel salt and transferred to the second loop by fuel salt circulation.Therefore,the MSFR is characterized by strong interaction between the neutronics and the thermal hydraulics.Moreover,recirculation flow occurs,and nuclear heat is accumulated near the fertile blanket,which significantly affects both the flow and the temperature fields in the core.In this work,to further optimize the conceptual geometric design of the MSFR,three geometries of the core and fertile blanket are proposed,and the thermal-hydraulic characteristics,including the three-dimensional flow and temperature fields of the fuel and fertile salts,are simulated and analyzed using a coupling scheme between the open source codes OpenMC and OpenFOAM.The numerical results indicate that a flatter core temperature distribution can be obtained and the hot spot and flow stagnation zones that appear in the upper and lower parts of the core center near the reflector can be eliminated by curving both the top and bottom walls of the core.Moreover,eight cooling loops with a total flow rate of0.0555 m3 s-1 ensur an acceptable temperature distribusure an acceptable temperature distribution in the fertile blanket.
基金supported by the National Key R&D Program of China(2018YFD0500601,2017YFD0500501)the National Natural Science Foundation of China(31722054,31472101 and 31528018)+2 种基金College of Animal Science and Technology "Young Talents Program" in China Agricultural University(2017DKA001)the 111 Project(B16044)the Developmental Fund for Animal Science by Shenzhen Jinxinnong Feed Co.,Ltd
文摘Background: The high mortality of pre-weanling piglets is a dominant challenge which severely restricts the development of pig industry. A number of factors including nutrients imbalance and temperature variation during postnatal period of piglets have been reported to closely associated with the high mortality of postnatal piglets.This study aims to find out the relationship between fat deposition and survival of newborn piglets.Results: There were no differences in organ coefficient and bone density between the surviving and dead piglets(P > 0.05). The body weight and the fat deposition in the dead piglets were lower than the live individuals(P < 0.05).Consistently, the average sizes of white adipocytes in back and abdominal adipose tissues of dead piglets were smaller than the survivals(P < 0.05). The protein expression levels of adipocyte differentiation markers PPARγ and C/EBPα in the back and abdominal adipose tissues were lower in dead piglets compared to live piglets. The mRNA expressions of thermogenic markers PGC1α and PRDM16 in adipose tissues were decreased in the dead piglets(P < 0.05). The microarray of back fat samples from the surviving and dead piglets were conducted; two down-regulated genes namely AAMDC and CASTOR1 were identified from the dead piglets. According to quantitative real-time PCR(RT-PCR) analysis, the mRNA expression of AAMDC decreased, whereas CASTOR1 expression elevated in the dead piglets compared to the surviving piglets(P < 0.05).Conclusions: The fat deposition and adipocyte differentiation in the dead piglets are insufficient compared to the surviving piglets, which may attenuate the thermogenic ability of white adipose tissue(WAT). Our data indicate that fat deposition in newborn piglets is vital to their survival.
基金The National Research Program of China under contract No.2017YFC1405300.
文摘The long-term spatiotemporal changes of surface biogenic elements in the Changjiang River Estuary and adjacent waters during the summer of 2008–2016 were analyzed in this study.The concentrations of dissolved inorganic nitrogen(DIN),soluble reactive phosphate(PO_(4)^(3−))and silicate(SiO_(3)^(2−))were generally stable,with a slight decrease of DIN and PO_(4)^(3−),and a slight increase of SiO_(3)^(2−),which mainly occurred in the estuarine waters.The grey correlation analysis was carried out between biogenic elements and chlorophyll a(Chl-a).Results showed that compared with the absolute values of biogenic elements,the correlations between the concentration ratio of nitrogen to phosphorus(N/P),ratio of silicon to nitrogen(Si/N)and Chl-a were closer,indicating the important influence on phytoplankton by the structure of biogenic elements.The study area was generally in a state of potential P limitation,and could have potential impact on the phytoplankton community,triggering the shift of red tide dominant species from diatoms to dinoflagellates.
基金financially supported by the National Natural Science Foundation of China(No.82001189)The Project Tackling of Key Scientific and Technical Problems of Henan Provine(No.232102311163).
文摘Bone metastasis,a life-threatening complication of advanced breast cancer,is often accompanied by debilitating pain(cancer-induced bone pain,CIBP)that severely impairs life quality and survival.The concurrent treatment of bone metastases and CIBP remains a clinical challenge because the therapeutic options are limited.In this study,we construct a near-infrared light-activated nano-therapeutic system to meet this conundrum.In detail,sorafenib(SRF)and photosensitizer(chlorin e6,Ce6)are encapsulated into mesoporous hydroxyapatite nanoparticles(HANPs),which are further functionalized with hyaluronic acid(HA)to obtain HA-SRF/Ce6@HANPs system.The designed nanoplatform destroys tumor cells in vitro and in vivo via the synergism of SRF(interrupting the exchange of cystine/glutamate by inhibiting SLC7A11)and photodynamic therapy(PDT,inducing reactive oxygen species generation).The decrease in tumor burden and reduction of extracellular glutamate significantly attenuate CIBP in mice model with developing bone cancer.Moreover,the combination of HA-SRF/Ce6@HANPs and PDT inhibit osteoclasts activation,promote osteoblast differentiation and accelerate bone repair.Overall,the nanoagent with good biocompatibility may provide an effective therapy method for the concurrent treatment of breast cancer bone metastasis and CIBP.
基金Supported by the Project of Shenzhen Science and Technology Innovation Committee(JCYJ20150831190958804)the Project of Shenzhen Human Settlements Committee(B41620320).
文摘The research aimed to study absorption and reduction of PM_(2.5)by different plant community structure,and explore which plant community can have better or best comprehensive absorption efficiency,thereby improving and optimizing urban vegetation structure,further promoting improvement of urban air quality,improving people's quality of life,and ensuring a good living environment.In this paper,the method of quadrat survey commonly used in field survey was adopted to record the height,coverage,DBH and other indicators of statistical plants,and corresponding comprehensive value was calculated through these indexes.PM_(2.5)was measured at forest edge,4 and 8 m in the forest,with three repetitions.Subtraction amount of PM_(2.5)determined at different layers was analyzed,as well as its relationship with comprehensive value of community structure.The results showed that PM_(2.5)amount decreased significantly at forest edge,4 and 8 m in the forest,and better community structure had a positive effect on PM_(2.5)absorption.The higher the comprehensive indexes of community structure such as plant height,DBH(arbor),density and coverage,the better the ability of absorbing and reducing PM_(2.5).Therefore,it must pay attention to the diversity of plant species per unit area,to build a good plant community structure,which could better improve structure of local ecosystem,and play a good role in absorbing and reducing PM_(2.5)pollutants in the atmosphere.
文摘In this work, monodispersed, well-shaped platinum (3.2 - 6.4 nm), rhodium (2.4 - 5.1 nm), palladium (3.2 - 5.3 nm) nanoparticles capped with poly(vinylpyrrolidone) were synthesized by a polyol reduction method in an ethylene glycol solution at temperature of 190℃. The influences of synthetic parameters on the size and morphology of the noble metal nanoparticles have been systematically investigated. The noble metal nanoparticles were characterized by means of UV-vis, laser scattering particle size distribution analysis (LSPSDA) and transmission electron microscopy (TEM). The experimental results showed that the particle size of metals nanoparticles, the morphology of which was spherical, increased with the raise of metal precursor concentration as well as the amount of PVP. The optimal molar ratio of PVP/metal and metal precursor concentration for the fabrication of Pt, Rh, and Pd nanoparticles with uniform distribution were 10 and 0.1 mM, respectively. The morphologies of the Rh nanoparticles with the size of 5.1 nm were polygons, including hexagons, pentagons, and triangles.
基金the National Natural Science Foundation of China(No. 52176032)the Natural Science Foundation of Tianjin Municipal Science and Technology Commission, China(No. 22JCQNJC00050)the National Science and Technology Major Project, China(No.2017-Ⅱ-0005-0016)
文摘Analysing the influence mechanism of the riblet protrusion height on turbulent drag components is more beneficial in organising the vortical structure over the riblet surface.Therefore, the Large Eddy Simulation(LES) is used to investigate the vortex structure over the riblet surface with different protrusion heights. Then, the variations of Reynolds stress and viscous shear stress in a turbulent channel are analysed. As a result, the drag reduction rate increases from3.4% when the riblets are completely submerged in the turbulent boundary layer to 7.9% when the protrusion height is 11.2. Further analysis shows that the protrusion height affects the streamwise vortices and the normal diffusivity of spanwise and normal vortices, thus driving the variation of Reynolds stress. Compared with the smooth surface, the vorticity strength and the number of streamwise vortices are weakened near the wall but increase in the logarithmic layer with increased protrusion height. Meanwhile, the normal diffusivity of spanwise vorticity decreases with the increase of protrusion height, and the normal diffusivity of normal vorticity is the smallest when the protrusion height is 11.2. Moreover, the protrusion height affects the velocity gradient of the riblet tip and riblet valley, thus driving the variation of viscous shear stress. With the increase of protrusion height, the velocity gradient of the riblet tip increases dramatically but decreases in the riblet valley.
文摘We present the effect of disorder on the optical conductivity of two-dimensional inhomogeneous superconductors by applying the kernel polynomial method to solve the Bogoliubov-de Gennes equations. By means of the lattice size scaling of the generalized inverse participation ratio, we find that the localization length of the quasiparticle decreases significantly with the increase of the disorder strength. Meanwhile, the weak disorder can readily restrain the Drude weight, while the superconducting gap has the tendency to suppress the low-energy optical conductivity. We also employ the Lanczos exact diagonalization method to study the competition between the on-site repulsive interactions and disorder. It is shown that the screening effect of repulsive interactions significantly enhances the Drude weight in the normal phase.
文摘Acupuncture is a traditional Chinese medicine therapy originated in China.In recent years,acupuncture is widely used in the field of neurological diseases,especially in the acute stage of stroke.Its mechanism of action is becoming clearer;one of the possible mechanisms is its bidirectional benign regulation.
基金supported by the General Project of Beijing Natural Science Funds-Study on the Effect of Naoshuning,a Traditional Chinese Medicine,for Activating Blood,Promoting Blood Circulation,Removing Water,and Dredging the Internal Organs,on Nerve Regeneration and Its Mechanism in Acute Ischemic Stroke(Fund Number:7182156).
文摘Leonurus is one of the commonly used clinical drugs in traditional Chinese medicine.In recent years,leonurus has been widely used for cerebrovascular diseases.With the deepening of research,the effect of its main component,leonurine,on the central nervous system has become clearer,and its mechanism has been confirmed and explained from many aspects.For reference,this paper discusses the latest research on the neuroprotective effect of leonurine on ischemic stroke at home and abroad in recent years.
基金sponsored by the Fundamental Research Funds for the Central Universities[N2329001].
文摘To overcome the limitations of traditional exoskeletons in complex outdoor terrains,this study introduces a novel lower limb exoskeleton inspired by the snow leopard’s forelimb musculoskeletal structure.It features a non-fully anthropomorphic design,attaching only at the thigh and ankle with a backward-knee configuration to mimic natural human knee movement.The design incorporates a single elastic element at the hip for gravity compensation and dual elastic elements at the knee for terrain adaptability,which adjust based on walking context.The design’s effectiveness was assessed by measuring metabolic cost reduction and motor output torque under various walking conditions.Results showed significant metabolic cost savings of 5.8–8.8%across different speeds and a 7.9%reduction during 9°incline walking on a flat indoor surface.Additionally,the spring element decreased hip motor output torque by 7–15.9%and knee torque by 8.1–14.2%.Outdoor tests confirmed the design’s robustness and effectiveness in reducing motor torque across terrains,highlighting its potential to advance multi-terrain adaptive exoskeleton research.
基金funded by Zhiyuan Laboratory(Grant NO.ZYL2024017a).
文摘The study of exoskeletons has been a popular topic worldwide.However,there is still a long way to go before exoskeletons can be widely used.One of the major challenges is control,and there is no specific research trend for controlling exoskeletons.In this paper,we propose a novel exoskeleton control strategy that combines Active Disturbance Rejection Control(ADRC)and Deep Reinforcement Learning(DRL).The dynamic model of the exoskeleton is constructed,followed with the design of the ADRC.To automatically adjust the control parameters of the ADRC,the Twin-Delayed Deep Deterministic Policy Gradient(TD3)is utilized.Then a reward function is defined in terms of the joint angle,angular velocity,and their errors to the desired values,to maximize the accuracy of the joint angle.In the simulations and experiments,a conventional ADRC,and ADRC based on Genetic Algorithm(GA)and Particle Swarm Optimization(PSO)were carried out for comparison with the proposed control method.The results of the tests show that TD3-ADRC has a rapid response,small overshoot,and low Mean Absolute Error(MAE)and Root Mean Square Error(RMSE)followed with the desired,demonstrating the superiority of the proposed control method for the self-learning control of exoskeleton.
基金financially supported by the Research Program of General Armament Department of China (No. 2012500)
文摘To improve the wear resistance of aluminum alloy frictional parts, Ti B2particles reinforced Ni-base alloy composite coatings were prepared on aluminum alloy 7005 by laser cladding. The microstructure and tribological properties of the composite coatings were investigated. The results show that the composite coating contains the phases of Ni Al, Ni3Al, Al3Ni2, TiB2, TiB, TiC, CrB, and Cr23C6.Its microhardness is HV0.5855.8, which is 15.4 % higher than that of the Ni-base alloy coating and is 6.7 times as high as that of the aluminum alloy. The friction coefficients of the composite coatings are reduced by 6.8 %–21.6 % and 13.2 %–32.4 % compared with those of the Ni-base alloy coatings and the aluminum alloys, while the wear losses are 27.4 %–43.2 % less than those of the Ni-base alloy coatings and are only 16.5 %–32.7 % of those of the aluminum alloys at different loads. At the light loads ranging from 3 to 6 N, the calculated maximum contact stress is smaller than the elastic limit contact stress. The wear mechanism of the composite coatings is micro-cutting wear, but changes into multi-plastic deformation wear at 9 N due to the higher calculated maximum contact stress than the elastic limit contact stress. As the loads increase to 12 N, the calculated flash temperature rises to 332.1 °C.The composite coating experiences multi-plastic deformation wear, micro-brittle fracture wear, and oxidative wear.
文摘In recent years,sEMG(surface electromyography)signals have been increasingly used to operate wearable devices.The development of mechanical lower limbs or exoskeletons controlled by the nervous system requires greater accuracy in recognizing lower limb activity.There is less research on devices to assist the human body in uphill movements.However,developing controllers that can accurately predict and control human upward movements in real-time requires the employment of appropriate signal pre-processing methods and prediction algorithms.For this purpose,this paper investigates the effects of various sEMG pre-processing methods and algorithms on the prediction results.This investigation involved ten subjects(five males and five females)with normal knee joints.The relevant data of the subjects were collected on a constructed ramp.To obtain feature values that reflect the gait characteristics,an improved PCA algorithm based on the kernel method is proposed for dimensionality reduction to remove redundant information.Then,a new model(CNN+LSTM)was proposed to predict the knee joint angle.Multiple approaches were utilized to validate the superiority of the improved PCA method and CNN-LSTM model.The feasibility of the method was verified by analyzing the gait prediction results of different subjects.Overall,the prediction time of the method was 25 ms,and the prediction error was 1.34±0.25 deg.By comparing with traditional machine learning methods such as BP(backpropagation)neural network,RF(random forest),and SVR(support vector machine),the improved PCA algorithm processed data performed the best in terms of convergence time and prediction accuracy in CNN-LSTM model.The experimental results demonstrate that the proposed method(improved PCA+CNN-LSTM)effectively recognizes lower limb activity from sEMG signals.For the same data input,the EMG signal processed using the improved PCA method performed better in terms of prediction results.This is the first step toward myoelectric control of aided exoskeleton robots using discrete decoding.The study results will lead to the future development of neuro-controlled mechanical exoskeletons that will allow troops or disabled individuals to engage in a greater variety of activities.
基金supported by the Pre-research project in the manned space field.Project Number 020202,China.
文摘This paper describes a novel gait pattern recognition method based on Long Short-Term Memory(LSTM)and Convolutional Neural Network(CNN)for lower limb exoskeleton.The Inertial Measurement Unit(IMU)installed on the exoskeleton to collect motion information,which is used for LSTM-CNN input.This article considers five common gait patterns,including walking,going up stairs,going down stairs,sitting down,and standing up.In the LSTM-CNN model,the LSTM layer is used to process temporal sequences and the CNN layer is used to extract features.To optimize the deep neural network structure proposed in this paper,some hyperparameter selection experiments were carried out.In addition,to verify the superiority of the proposed recognition method,the method is compared with several common methods such as LSTM,CNN and SVM.The results show that the average recognition accuracy can reach 97.78%,which has a good recognition eff ect.Finally,according to the experimental results of gait pattern switching,the proposed method can identify the switching gait pattern in time,which shows that it has good real-time performance.
