Alzheimer's disease,the primary cause of dementia,is characterized by neuropathologies,such as amyloid plaques,synaptic and neuronal degeneration,and neurofibrillary tangles.Although amyloid plaques are the primar...Alzheimer's disease,the primary cause of dementia,is characterized by neuropathologies,such as amyloid plaques,synaptic and neuronal degeneration,and neurofibrillary tangles.Although amyloid plaques are the primary characteristic of Alzheimer's disease in the central nervous system and peripheral organs,targeting amyloid-beta clearance in the central nervous system has shown limited clinical efficacy in Alzheimer's disease treatment.Metabolic abnormalities are commonly observed in patients with Alzheimer's disease.The liver is the primary peripheral organ involved in amyloid-beta metabolism,playing a crucial role in the pathophysiology of Alzheimer's disease.Notably,impaired cholesterol metabolism in the liver may exacerbate the development of Alzheimer's disease.In this review,we explore the underlying causes of Alzheimer's disease and elucidate the role of the liver in amyloid-beta clearance and cholesterol metabolism.Furthermore,we propose that restoring normal cholesterol metabolism in the liver could represent a promising therapeutic strategy for addressing Alzheimer's disease.展开更多
The excessive buildup of neurotoxicα-synuclein plays a pivotal role in the pathogenesis of Parkinson's disease,highlighting the urgent need for innovative therapeutic strategies to promoteα-synuclein clearance,p...The excessive buildup of neurotoxicα-synuclein plays a pivotal role in the pathogenesis of Parkinson's disease,highlighting the urgent need for innovative therapeutic strategies to promoteα-synuclein clearance,particularly given the current lack of disease-modifying treatments.The glymphatic system,a recently identified perivascular fluid transport network,is crucial for clearing neurotoxic proteins.This review aims to synthesize current knowledge on the role of the glymphatic system inα-synuclein clearance and its implications for the pathology of Parkinson's disease while emphasizing potential therapeutic strategies and areas for future research.The review begins with an overview of the glymphatic system and details its anatomical structure and physiological functions that facilitate cerebrospinal fluid circulation and waste clearance.It summarizes emerging evidence from neuroimaging and experimental studies that highlight the close correlation between the glymphatic system and clinical symptom severity in patients with Parkinson's disease,as well as the effect of glymphatic dysfunction onα-synuclein accumulation in Parkinson's disease models.Subsequently,the review summarizes the mechanisms of glymphatic system impairment in Parkinson's disease,including sleep disturbances,aquaporin-4 impairment,and mitochondrial dysfunction,all of which diminish glymphatic system efficiency.This creates a vicious cycle that exacerbatesα-synuclein accumulation and worsens Parkinson's disease.The therapeutic perspectives section outlines strategies for enhancing glymphatic activity,such as improving sleep quality and pharmacologically targeting aquaporin-4 or its subcellular localization.Promising interventions include deep brain stimulation,melatonin supplementation,γ-aminobutyric acid modulation,and non-invasive methods(such as exercise and bright-light therapy),multisensoryγstimulation,and ultrasound therapy.Moreover,identifying neuroimaging biomarkers to assess glymphatic flow as an indicator ofα-synuclein burden could refine Parkinson's disease diagnosis and track disease progression.In conclusion,the review highlights the critical role of the glymphatic system inα-synuclein clearance and its potential as a therapeutic target in Parkinson's disease.It advocates for further research to elucidate the specific mechanisms by which the glymphatic system clears misfoldedα-synuclein and the development of imaging biomarkers to monitor glymphatic activity in patients with Parkinson's disease.Findings from this review suggest that enhancing glymphatic clearance is a promising strategy for reducingα-synuclein deposits and mitigating the progression of Parkinson's disease.展开更多
The existence of the aeroengine casing,limited monitoring points,and multi-fault characteristics make obtaining the rotor’s vibration transmission characteristics challenging,resulting in difficulties accurately iden...The existence of the aeroengine casing,limited monitoring points,and multi-fault characteristics make obtaining the rotor’s vibration transmission characteristics challenging,resulting in difficulties accurately identifying the rotor unbalance.This paper utilizes a high-frequency composite sensor to monitor the engine’s blade tip clearance(BTC)and extracts unbalanced information from BTC signals for rotor dynamic balancing,while avoiding the need for the once per revolution(OPR)sensor.First,the vibration characteristics of the rotor-blade system under multi-fault conditions are investigated.Then,based on BTC measurement,a none OPR method and an unbalance identification method are proposed,in which the radial vibration of the blade tip in the BTC signals at different speeds is extracted and operated in the time domain to obtain the rotor unbalanced vibration,the signal is reconstructed,and cross-correlation analysis is used to accurately identify the magnitude and phase of the unbalanced signal.Finally,a rotor test bench is utilized for experimental verification.The results reveal that the dynamic balancing method based on the BTC signal can more precisely identify the rotor unbalance than the traditional rotor dynamic balancing method.The application of this technique will effectively improve engine health management and fault prediction.展开更多
Currently,it is still a challenge to develop an organic photosensitizer(PS)with outstanding near-infrared absorption,low O2dependence,precise tumor targeting and rapid clearance through the kidney to improve the overa...Currently,it is still a challenge to develop an organic photosensitizer(PS)with outstanding near-infrared absorption,low O2dependence,precise tumor targeting and rapid clearance through the kidney to improve the overall outcome of phototherapy.In this study,we have designed an organic PS(Nc PB)with an excellent near-infrared light absorption through a refined molecular strategy.Meanwhile,Nc PB was assembled into nanoparticles with different sizes(Nano Nc PB-1 and Nano Nc PB-0)by a supramolecular modulation strategy.As the results,the nanoparticle with an ultra-small size(Nano Nc PB-1)generated a large number of superoxide anion(O_(2)^(·-))in a low-O_(2)-dependent manner and release plenty of heat.Furthermore,the results of in vivo experiments demonstrated that Nano Nc PB-1 actively accumulated in tumor tissues and showed a 92%tumor inhibition after photodynamic and photothermal combination therapy.More importantly,Nano Nc PB-1 could be rapidly cleared from the body of mice via the renal pathway,which alleviates potential side effects of prolonged retention of PS in the circulation.展开更多
Bulb-type hydro turbines are commonly used in small-to medium-scale hydropower stations due to their compact design and adaptability to low-head conditions.However,long-termoperation often results in wear at the runne...Bulb-type hydro turbines are commonly used in small-to medium-scale hydropower stations due to their compact design and adaptability to low-head conditions.However,long-termoperation often results in wear at the runner rim,increasing tip clearance and triggering leakage flow and cavitation.These effects reduce hydraulic efficiency and accelerate blade surface erosion,posing serious risks to unit safety and operational stability.This study investigates the influence of tip clearance on cavitation performance in a 24 MW prototype bulb turbine.A three-dimensional numericalmodel is developed to simulate various operating conditions with different tip clearance values(3.0,4.5,and 6.0 mm)and cavitation numbers(σ=1.20–1.33).Internal flow characteristics—including pressure distribution,velocity fields,hydraulic efficiency,and pressure pulsation—are analyzed to elucidate the impact of tip clearance on cavitation development.Results show that underσ=1.2 and a 4.5 mm tip clearance,the pressure pulsation amplitude at the blade tip reaches 4870 Pa—approximately 1.5 times higher than that near the hub.At partial flowconditions,turbine efficiency decreases by up to 6.8%compared to the rated condition.Increasing the tip clearance from 1.5 to 6.0 mm expands the low-pressure area near the blade tip by around 32%,significantly intensifying cavitation.Frequency domain analysis reveals dominant pulsation frequencies between 10–20Hz,characterized by blade-passing features and a wave-clipping effect.These findings provide theoretical insight and quantitative evidence to support the optimization of tip clearance design and cavitation mitigation strategies in bulb turbines,aiming to improve both efficiency and operational stability.展开更多
Combining practical engineering projects, this article analyzes the design strategies for the reconstruction and expansion of insufficient clearance sections in highway interchanges. This includes an overview of the p...Combining practical engineering projects, this article analyzes the design strategies for the reconstruction and expansion of insufficient clearance sections in highway interchanges. This includes an overview of the project, a comparison of design options for insufficient clearance in interchanges, and the main design strategies for reconstruction and expansion. It is hoped that this analysis can provide a reference for the design of such road reconstruction and expansion projects.展开更多
Metamorphic mechanism has the advantages of variable topology and variable degrees of freedom, which can realize the requirements of multi-conditions and multi-tasks, and has a good application prospect. The configura...Metamorphic mechanism has the advantages of variable topology and variable degrees of freedom, which can realize the requirements of multi-conditions and multi-tasks, and has a good application prospect. The configuration transformation is prominent feature of the metamorphic mechanism. The number of constraints or properties of the kinematic pairs provided by the metamorphic kinematic pairs will change under certain conditions, its dynamic performance is much more complex than that of traditional kinematic pairs with immutable constraints. However, the clearance model about traditional kinematic pairs with immutable constraints established by long-term research is difficult to be directly applied to the metachromatic kinematic pairs. Referring to the experience of the traditional kinematic pairs with immutable constraints, the continuous contact model of Metamorphic Groove pin pair with clearance is established. According to the traditional continuous contact model of the kinematic pairs with immutable constraints, the forces between the elements of kinematic pair of the mechanism with clearance and the ideal mechanism without clearance are regarded as the same, and the inertia force and inertia moment of the components are also calculated according to the acceleration of the ideal mechanism. The clearance is regarded as a massless virtual bar with length r. For the rotating pair part, the massless virtual bar length r is the difference between the radius of the shaft and the hole, and for the sliding pair part, the massless virtual bar length r is half of the difference between the height of the slider and the guide groove. According to the new mechanism without gap after adding the imaginary bar, kinetic energy and potential energy of the system are calculated for the two configurations of mechanism with metamorphic Groove pin pair with clearance. The kinetic energy and potential energy of the system are calculated according to the new mechanism without clearance after adding the massless virtual bar. The kinetic energy, potential energy and generalized force are substituted into the Lagrangian equation to obtain the motion equation of the metamorphic mechanism, which lays the foundation for the dynamic performance study of the mechanism with metamorphic groove pin pair with clearance.展开更多
Mechanical vibration sputum clearance is commonly used for airway clearance.However,existing handheld vibration-assisted expectorators confront several challenges including operator’s hand fatigue and a high risk of ...Mechanical vibration sputum clearance is commonly used for airway clearance.However,existing handheld vibration-assisted expectorators confront several challenges including operator’s hand fatigue and a high risk of cross-infection between medical staff and patients.To address these issues,this study presents a novel design for an intelligent percussion-based sputum clearance robot.The robot is designed to assist medical staff in providing percussion-based sputum clearance nursing for patients.Initially,the structure of the robot is designed based on the environmental conditions in the intensive care unit(ICU).To mitigate the impact of the vibrations generated by the vibration percussion head on the robotic arm operation,a fixture equipped with a vibration damper is designed to ensure that the robot’s standard functionality remains unaffected.Furthermore,a human back detection(HBD)framework constructed from multi-subtask modules is proposed to address the shortcomings of existing robotic systems in terms of human perception capabilities.These modules are designed to accurately identify and map the anatomical features of the human back.This effectively improves the capability of the robot to interact with the human body.Based on this framework,the robotic arm is controlled precisely to emulate the percussion strategies employed by physicians.Finally,extensive experiments are conducted in a real-world setting with multiple participants.The results indicate that the robot could provide percussion-based sputum clearance nursing that is practically equivalent to the operations by medical staff.展开更多
As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canist...As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canister,have grown increasingly complex.However,deficiencies still exist in the current launch modeling theory for BMLRS.In this study,a multi-rigid-flexible-body launch dynamics model coupling the launch platform and rocket was established using the multibody system transfer matrix method and the Newton-Euler formulation.Furthermore,considering the bending of the launch canister,a detection algorithm for slider-guide plane clearance contact was proposed.To quantify the contact force and friction effect between the slider and guide,the contact force model and modified Coulomb model were introduced.Both the modal and launch tests were conducted.Additionally,the modal convergence was verified.By comparing the modal experiments and simulation results,the maximum relative error of the eigenfrequency is 3.29%.thereby verifying the accuracy of the developed BMLRS dynamics model.Furthermore,the launch test validated the proposed plane clearance contact model.Moreover,the study investigated the influence of various model parameters on the dynamic characteristics of BMLRS,including launch canister bending stiffness,slider and guide material,slider-guide clearance,slider length and layout.This analysis of influencing factors provides a foundation for future optimization in BMLRS design.展开更多
Advancements in murine modeling systems for ulcerative colitis have diversified our understanding of the pathophysiological factors involved in disease onset and progression.This has fueled the identification of molec...Advancements in murine modeling systems for ulcerative colitis have diversified our understanding of the pathophysiological factors involved in disease onset and progression.This has fueled the identification of molecular targets,resulting in a rapidly expanding therapeutic armamentarium.Subsequently,management strategies have evolved from symptomatic resolution to well-defined objective endpoints,including clinical remission,endoscopic remission and mucosal healing.While the incorporation of these assessment modalities has permitted targeted intervention in the context of a natural disease history and the prevention of complications,studies have consistently depicted discrepancies associated with ascertaining disease status through clinical and endoscopic measures.Current recommendations lack consideration of histological healing.The simultaneous achievement of clinical,endoscopic,and histologic remission has not been fully investigated.This has laid the groundwork for a novel therapeutic outcome termed disease clearance(DC).This article summarizes the concept of DC and its current evidence.展开更多
Objective:Augmented renal clearance(ARC),in contrast to renal dysfunction,refers to enhanced renal elimination of circulating solutes compared to the expected baseline.Although patients may present with normal serum c...Objective:Augmented renal clearance(ARC),in contrast to renal dysfunction,refers to enhanced renal elimination of circulating solutes compared to the expected baseline.Although patients may present with normal serum creatinine(Scr)levels,the incidence of ARC is high in intensive care unit(ICU)settings.ARC is associated with subtherapeutic exposure and treatment failure of renally cleared antibiotics.However,limited research exists on the incidence and risk factors of ARC in the ICU,and even fewer data are available specifically for neurological ICU(NICU).This study aims to determine the incidence and risk factors of ARC in neurocritically ill patients.Methods:We retrospectively analyzed all available Scr data of neurocritical care patients admitted to the NICU of the Second Xiangya Hospital of Central South University between December 2020 and January 2023.Creatinine clearance(CrCl)was calculated using the Cockcroft-Gault equation.ARC was defined as a CrCl≥130 mL/(min·1.73 m^(2))sustained for more than 50%of the duration of the NICU stay.A total of 208 neurocritically ill patients were assigned into an ARC group(n=52)and a non-ARC(N-ARC)group(n=156).Clinical characteristics were compared between the 2 groups.Variables with P<0.05 in univariate analysis were included in binary Logistic regression to identify independent risk factors for ARC.Results:The incidence of ARC among neurocritically ill patients was 25.00%.Of the 74 patients with normal CrCl,20(27.03%)gradually developed ARC during hospitalization.Compared with the N-ARC group,the patients of the ARC group were younger(P<0.001),with a higher proportion of females(P=0.048)and a lower admission mean arterial pressure(MAP)(P=0.034).Moreover,patients of the ARC group were commonly complicated with severe bacterial infections compared with the patients of the N-ARC group(P<0.001).In binary Logistic regression analysis,younger age(OR=0.903,95%CI 0.872 to 0.935)and severe bacterial infections(OR=6.270,95%CI 2.568 to 15.310)were significant predictors of ARC.Conclusion:ARC is relatively common in the NICU.A considerable number of patients with initially normal renal function developed ARC during hospitalization.Younger age and concurrent severe bacterial infection are important risk factors of ARC in neurocritically ill patients.展开更多
基金financially supported by the Science and Technology Innovation Program of Hunan Province,No.2022RC1220(to WP)China Postdoctoral Science Foundation,No.2022M711733(to ZZ)+2 种基金the National Natural Science Foundation of China,No.82160920(to ZZ)Hebei Postdoctoral Scientific Research Project,No.B2022003040(to ZZ)Hunan Flagship Department of Integrated Traditional Chinese and Western Medicine(to WP)。
文摘Alzheimer's disease,the primary cause of dementia,is characterized by neuropathologies,such as amyloid plaques,synaptic and neuronal degeneration,and neurofibrillary tangles.Although amyloid plaques are the primary characteristic of Alzheimer's disease in the central nervous system and peripheral organs,targeting amyloid-beta clearance in the central nervous system has shown limited clinical efficacy in Alzheimer's disease treatment.Metabolic abnormalities are commonly observed in patients with Alzheimer's disease.The liver is the primary peripheral organ involved in amyloid-beta metabolism,playing a crucial role in the pathophysiology of Alzheimer's disease.Notably,impaired cholesterol metabolism in the liver may exacerbate the development of Alzheimer's disease.In this review,we explore the underlying causes of Alzheimer's disease and elucidate the role of the liver in amyloid-beta clearance and cholesterol metabolism.Furthermore,we propose that restoring normal cholesterol metabolism in the liver could represent a promising therapeutic strategy for addressing Alzheimer's disease.
基金supported by the National Natural Science Foundation of China,No.81971031(to ZL)the National Key Research and Development Program of China,No.2022YFE0210100(to JFC)+7 种基金the National Natural Science Foundation of China(Original Exploration Project),No.82151308(to JFC)the National Natural Science Foundation of China(Research Fund for International Senior Scientists),No.82150710558(to JFC)Science&Technology Initiative STI2030-Major Projects,No.2021ZD0203400(to JFC)Key Research and Development Program of Zhejiang Province,No.2023C03079(to JFC)Scientific Research Starting Foundation of Oujiang Laboratory(Zhejiang Laboratory for Regenerative Medicine,Vision and Brain Health),No.OJQDSP2022007(to JFC)Project of State Key Laboratory of Ophthalmology,Optometry and Visual Science,Wenzhou Medical University,No.J01-20190101(to JFC)Scientific Research Starting Foundation of Wenzhou Medical University,No.QTJ12003(to JFC)Department of Science and Technology of Zhejiang Province,No.2023ZY1011(to JFC)。
文摘The excessive buildup of neurotoxicα-synuclein plays a pivotal role in the pathogenesis of Parkinson's disease,highlighting the urgent need for innovative therapeutic strategies to promoteα-synuclein clearance,particularly given the current lack of disease-modifying treatments.The glymphatic system,a recently identified perivascular fluid transport network,is crucial for clearing neurotoxic proteins.This review aims to synthesize current knowledge on the role of the glymphatic system inα-synuclein clearance and its implications for the pathology of Parkinson's disease while emphasizing potential therapeutic strategies and areas for future research.The review begins with an overview of the glymphatic system and details its anatomical structure and physiological functions that facilitate cerebrospinal fluid circulation and waste clearance.It summarizes emerging evidence from neuroimaging and experimental studies that highlight the close correlation between the glymphatic system and clinical symptom severity in patients with Parkinson's disease,as well as the effect of glymphatic dysfunction onα-synuclein accumulation in Parkinson's disease models.Subsequently,the review summarizes the mechanisms of glymphatic system impairment in Parkinson's disease,including sleep disturbances,aquaporin-4 impairment,and mitochondrial dysfunction,all of which diminish glymphatic system efficiency.This creates a vicious cycle that exacerbatesα-synuclein accumulation and worsens Parkinson's disease.The therapeutic perspectives section outlines strategies for enhancing glymphatic activity,such as improving sleep quality and pharmacologically targeting aquaporin-4 or its subcellular localization.Promising interventions include deep brain stimulation,melatonin supplementation,γ-aminobutyric acid modulation,and non-invasive methods(such as exercise and bright-light therapy),multisensoryγstimulation,and ultrasound therapy.Moreover,identifying neuroimaging biomarkers to assess glymphatic flow as an indicator ofα-synuclein burden could refine Parkinson's disease diagnosis and track disease progression.In conclusion,the review highlights the critical role of the glymphatic system inα-synuclein clearance and its potential as a therapeutic target in Parkinson's disease.It advocates for further research to elucidate the specific mechanisms by which the glymphatic system clears misfoldedα-synuclein and the development of imaging biomarkers to monitor glymphatic activity in patients with Parkinson's disease.Findings from this review suggest that enhancing glymphatic clearance is a promising strategy for reducingα-synuclein deposits and mitigating the progression of Parkinson's disease.
基金supported by the Key Program of National Natural Science Foundation of China(No.92160203)National Natural Science Foundation of China(No.92360306).
文摘The existence of the aeroengine casing,limited monitoring points,and multi-fault characteristics make obtaining the rotor’s vibration transmission characteristics challenging,resulting in difficulties accurately identifying the rotor unbalance.This paper utilizes a high-frequency composite sensor to monitor the engine’s blade tip clearance(BTC)and extracts unbalanced information from BTC signals for rotor dynamic balancing,while avoiding the need for the once per revolution(OPR)sensor.First,the vibration characteristics of the rotor-blade system under multi-fault conditions are investigated.Then,based on BTC measurement,a none OPR method and an unbalance identification method are proposed,in which the radial vibration of the blade tip in the BTC signals at different speeds is extracted and operated in the time domain to obtain the rotor unbalanced vibration,the signal is reconstructed,and cross-correlation analysis is used to accurately identify the magnitude and phase of the unbalanced signal.Finally,a rotor test bench is utilized for experimental verification.The results reveal that the dynamic balancing method based on the BTC signal can more precisely identify the rotor unbalance than the traditional rotor dynamic balancing method.The application of this technique will effectively improve engine health management and fault prediction.
基金the National Natural Science Foundation of China(Nos.T2322004 and 22078066)。
文摘Currently,it is still a challenge to develop an organic photosensitizer(PS)with outstanding near-infrared absorption,low O2dependence,precise tumor targeting and rapid clearance through the kidney to improve the overall outcome of phototherapy.In this study,we have designed an organic PS(Nc PB)with an excellent near-infrared light absorption through a refined molecular strategy.Meanwhile,Nc PB was assembled into nanoparticles with different sizes(Nano Nc PB-1 and Nano Nc PB-0)by a supramolecular modulation strategy.As the results,the nanoparticle with an ultra-small size(Nano Nc PB-1)generated a large number of superoxide anion(O_(2)^(·-))in a low-O_(2)-dependent manner and release plenty of heat.Furthermore,the results of in vivo experiments demonstrated that Nano Nc PB-1 actively accumulated in tumor tissues and showed a 92%tumor inhibition after photodynamic and photothermal combination therapy.More importantly,Nano Nc PB-1 could be rapidly cleared from the body of mice via the renal pathway,which alleviates potential side effects of prolonged retention of PS in the circulation.
基金Funded by the National Natural Science Foundation of China(52066011)Jiuquan Science and Technology Plan Project University-Level Key Project(2024XJKXM03)Foundation of Key Laboratory of Solar Power System(Grant No.2024SPKL03).
文摘Bulb-type hydro turbines are commonly used in small-to medium-scale hydropower stations due to their compact design and adaptability to low-head conditions.However,long-termoperation often results in wear at the runner rim,increasing tip clearance and triggering leakage flow and cavitation.These effects reduce hydraulic efficiency and accelerate blade surface erosion,posing serious risks to unit safety and operational stability.This study investigates the influence of tip clearance on cavitation performance in a 24 MW prototype bulb turbine.A three-dimensional numericalmodel is developed to simulate various operating conditions with different tip clearance values(3.0,4.5,and 6.0 mm)and cavitation numbers(σ=1.20–1.33).Internal flow characteristics—including pressure distribution,velocity fields,hydraulic efficiency,and pressure pulsation—are analyzed to elucidate the impact of tip clearance on cavitation development.Results show that underσ=1.2 and a 4.5 mm tip clearance,the pressure pulsation amplitude at the blade tip reaches 4870 Pa—approximately 1.5 times higher than that near the hub.At partial flowconditions,turbine efficiency decreases by up to 6.8%compared to the rated condition.Increasing the tip clearance from 1.5 to 6.0 mm expands the low-pressure area near the blade tip by around 32%,significantly intensifying cavitation.Frequency domain analysis reveals dominant pulsation frequencies between 10–20Hz,characterized by blade-passing features and a wave-clipping effect.These findings provide theoretical insight and quantitative evidence to support the optimization of tip clearance design and cavitation mitigation strategies in bulb turbines,aiming to improve both efficiency and operational stability.
文摘Combining practical engineering projects, this article analyzes the design strategies for the reconstruction and expansion of insufficient clearance sections in highway interchanges. This includes an overview of the project, a comparison of design options for insufficient clearance in interchanges, and the main design strategies for reconstruction and expansion. It is hoped that this analysis can provide a reference for the design of such road reconstruction and expansion projects.
文摘Metamorphic mechanism has the advantages of variable topology and variable degrees of freedom, which can realize the requirements of multi-conditions and multi-tasks, and has a good application prospect. The configuration transformation is prominent feature of the metamorphic mechanism. The number of constraints or properties of the kinematic pairs provided by the metamorphic kinematic pairs will change under certain conditions, its dynamic performance is much more complex than that of traditional kinematic pairs with immutable constraints. However, the clearance model about traditional kinematic pairs with immutable constraints established by long-term research is difficult to be directly applied to the metachromatic kinematic pairs. Referring to the experience of the traditional kinematic pairs with immutable constraints, the continuous contact model of Metamorphic Groove pin pair with clearance is established. According to the traditional continuous contact model of the kinematic pairs with immutable constraints, the forces between the elements of kinematic pair of the mechanism with clearance and the ideal mechanism without clearance are regarded as the same, and the inertia force and inertia moment of the components are also calculated according to the acceleration of the ideal mechanism. The clearance is regarded as a massless virtual bar with length r. For the rotating pair part, the massless virtual bar length r is the difference between the radius of the shaft and the hole, and for the sliding pair part, the massless virtual bar length r is half of the difference between the height of the slider and the guide groove. According to the new mechanism without gap after adding the imaginary bar, kinetic energy and potential energy of the system are calculated for the two configurations of mechanism with metamorphic Groove pin pair with clearance. The kinetic energy and potential energy of the system are calculated according to the new mechanism without clearance after adding the massless virtual bar. The kinetic energy, potential energy and generalized force are substituted into the Lagrangian equation to obtain the motion equation of the metamorphic mechanism, which lays the foundation for the dynamic performance study of the mechanism with metamorphic groove pin pair with clearance.
基金Supported by National Key R&D Program of China(Grant No.2021YFC0122700).
文摘Mechanical vibration sputum clearance is commonly used for airway clearance.However,existing handheld vibration-assisted expectorators confront several challenges including operator’s hand fatigue and a high risk of cross-infection between medical staff and patients.To address these issues,this study presents a novel design for an intelligent percussion-based sputum clearance robot.The robot is designed to assist medical staff in providing percussion-based sputum clearance nursing for patients.Initially,the structure of the robot is designed based on the environmental conditions in the intensive care unit(ICU).To mitigate the impact of the vibrations generated by the vibration percussion head on the robotic arm operation,a fixture equipped with a vibration damper is designed to ensure that the robot’s standard functionality remains unaffected.Furthermore,a human back detection(HBD)framework constructed from multi-subtask modules is proposed to address the shortcomings of existing robotic systems in terms of human perception capabilities.These modules are designed to accurately identify and map the anatomical features of the human back.This effectively improves the capability of the robot to interact with the human body.Based on this framework,the robotic arm is controlled precisely to emulate the percussion strategies employed by physicians.Finally,extensive experiments are conducted in a real-world setting with multiple participants.The results indicate that the robot could provide percussion-based sputum clearance nursing that is practically equivalent to the operations by medical staff.
基金supported by National Natural Science Foundation of China(Grant No.92266201).
文摘As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canister,have grown increasingly complex.However,deficiencies still exist in the current launch modeling theory for BMLRS.In this study,a multi-rigid-flexible-body launch dynamics model coupling the launch platform and rocket was established using the multibody system transfer matrix method and the Newton-Euler formulation.Furthermore,considering the bending of the launch canister,a detection algorithm for slider-guide plane clearance contact was proposed.To quantify the contact force and friction effect between the slider and guide,the contact force model and modified Coulomb model were introduced.Both the modal and launch tests were conducted.Additionally,the modal convergence was verified.By comparing the modal experiments and simulation results,the maximum relative error of the eigenfrequency is 3.29%.thereby verifying the accuracy of the developed BMLRS dynamics model.Furthermore,the launch test validated the proposed plane clearance contact model.Moreover,the study investigated the influence of various model parameters on the dynamic characteristics of BMLRS,including launch canister bending stiffness,slider and guide material,slider-guide clearance,slider length and layout.This analysis of influencing factors provides a foundation for future optimization in BMLRS design.
文摘Advancements in murine modeling systems for ulcerative colitis have diversified our understanding of the pathophysiological factors involved in disease onset and progression.This has fueled the identification of molecular targets,resulting in a rapidly expanding therapeutic armamentarium.Subsequently,management strategies have evolved from symptomatic resolution to well-defined objective endpoints,including clinical remission,endoscopic remission and mucosal healing.While the incorporation of these assessment modalities has permitted targeted intervention in the context of a natural disease history and the prevention of complications,studies have consistently depicted discrepancies associated with ascertaining disease status through clinical and endoscopic measures.Current recommendations lack consideration of histological healing.The simultaneous achievement of clinical,endoscopic,and histologic remission has not been fully investigated.This has laid the groundwork for a novel therapeutic outcome termed disease clearance(DC).This article summarizes the concept of DC and its current evidence.
基金supported by the Natural Science Foundation of Hunan Province(2023JJ60087)the Clinical Medical Technology Innovation Guidance Project of Hunan Province(2021SK53501),China。
文摘Objective:Augmented renal clearance(ARC),in contrast to renal dysfunction,refers to enhanced renal elimination of circulating solutes compared to the expected baseline.Although patients may present with normal serum creatinine(Scr)levels,the incidence of ARC is high in intensive care unit(ICU)settings.ARC is associated with subtherapeutic exposure and treatment failure of renally cleared antibiotics.However,limited research exists on the incidence and risk factors of ARC in the ICU,and even fewer data are available specifically for neurological ICU(NICU).This study aims to determine the incidence and risk factors of ARC in neurocritically ill patients.Methods:We retrospectively analyzed all available Scr data of neurocritical care patients admitted to the NICU of the Second Xiangya Hospital of Central South University between December 2020 and January 2023.Creatinine clearance(CrCl)was calculated using the Cockcroft-Gault equation.ARC was defined as a CrCl≥130 mL/(min·1.73 m^(2))sustained for more than 50%of the duration of the NICU stay.A total of 208 neurocritically ill patients were assigned into an ARC group(n=52)and a non-ARC(N-ARC)group(n=156).Clinical characteristics were compared between the 2 groups.Variables with P<0.05 in univariate analysis were included in binary Logistic regression to identify independent risk factors for ARC.Results:The incidence of ARC among neurocritically ill patients was 25.00%.Of the 74 patients with normal CrCl,20(27.03%)gradually developed ARC during hospitalization.Compared with the N-ARC group,the patients of the ARC group were younger(P<0.001),with a higher proportion of females(P=0.048)and a lower admission mean arterial pressure(MAP)(P=0.034).Moreover,patients of the ARC group were commonly complicated with severe bacterial infections compared with the patients of the N-ARC group(P<0.001).In binary Logistic regression analysis,younger age(OR=0.903,95%CI 0.872 to 0.935)and severe bacterial infections(OR=6.270,95%CI 2.568 to 15.310)were significant predictors of ARC.Conclusion:ARC is relatively common in the NICU.A considerable number of patients with initially normal renal function developed ARC during hospitalization.Younger age and concurrent severe bacterial infection are important risk factors of ARC in neurocritically ill patients.
