Devices on aircraft are subjected to complex environmental excitations that pose risks to their operational safety.Passive vibration isolation techniques are extensively employed due to their advantage of not requirin...Devices on aircraft are subjected to complex environmental excitations that pose risks to their operational safety.Passive vibration isolation techniques are extensively employed due to their advantage of not requiring additional energy sources.This paper introduces a novel metallic vibration isolator based on zigzag structures.The proposed isolator features a compact design and can be manufactured using additive manufacturing techniques,allowing for the integration of structural and functional elements.Firstly,the vibration response of the single-degree-of-freedom(SDOF)system is analyzed.To achieve effective vibration reduction,it is crucial for the isolator's stiffness to be sufficiently low.Secondly,to obtain a structure with high compliance,the traversal algorithm and the finite element method(FEM)are applied.The results confirm that the zigzag structure is a reliable high-compliance configuration.Thirdly,the parametric geometric model of the zigzag structure is developed and its stiffness is calculated.Quasi-static compression experiments validate the accuracy of the calculations.Finally,a specific engineering example is considered,where a zigzag vibration isolator is designed and fabricated.Vibration experiments demonstrate that the zigzag isolator effectively reduces both the stiffness and the fundamental frequency of the vibration system,achieving a vibration isolation efficiency exceeding 60%.展开更多
This work discusses the strain and acceleration suppression of a flexible beam subjected to different supports analytically.As classical protection,the beam is mounted on a vertical linear spring together with a linea...This work discusses the strain and acceleration suppression of a flexible beam subjected to different supports analytically.As classical protection,the beam is mounted on a vertical linear spring together with a linear damper in parallel.This is called linear isolation.To enhance isolation performance,nonlinearity is employed in the boundary.In addition,quasi-zero isolation is established based on the non-linearly enhanced one by adjusting the installation length of the horizontal spring.To discuss their performance fully and fairly,the amplitude,the acceleration,the potential energy of the beam,the input work of the excitation,the dissipation work of the beam,and the dynamics stress along the beam are investigated based on the same parameters.The comparison shows that all these isolations can protect the beam with high efficiency,even when the basement excitation is tiny.Although the linear isolation and the nonlinearly enhanced one will arouse two resonance peaks on both sides of the primary resonance of the beam without isolation,the maximum amplitudes of them are reduced a lot.But for the low frequency excitation,the quasi-zero isolation has the best performance as it drives the primary resonance to the high frequency region.The simulation shows that the beam needs a relatively soft isolation to avoid the damage caused by the shock vibration,including the quasi-zero one.In general,the quasi-zero isolation shows the best performance.The nonlinearly enhanced one is the suboptimal choice.The present work shows the capacities of three isolations for a flexible beam by the steady-state response and the shock vibration.It provides design suggestions for the isolation of flexible beams.展开更多
Isolated power converters have emerged as an active research topic in power integrated circuit(IC)design.Reflecting this growing interest,ISSCC 2025 has featured a dedicated session on"Isolated Power and Gate Dri...Isolated power converters have emerged as an active research topic in power integrated circuit(IC)design.Reflecting this growing interest,ISSCC 2025 has featured a dedicated session on"Isolated Power and Gate Drivers".These converters enable safe and reliable power delivery across voltage domains and are widely used in renewable energy,electric vehicles,and telecommunications.Galvanic isolation prevents surge currents and ground loop issues in harsh high-voltage environments.As demand grows for compact,efficient,and high–power-density solutions,fully integrated architectures featuring on-chip transformers are increasingly favored over traditional module-based designs,offering>5 kV isolation with a smaller footprint and lower system cost[1].展开更多
The biological species concept defines species as groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups(Mayr,1942).Reproductive isolation,whether p...The biological species concept defines species as groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups(Mayr,1942).Reproductive isolation,whether prezygotic or postzygotic,plays a central role in maintaining species boundaries.However,hybridization between closely related taxa can challenge these boundaries and provide insight into speciation,gene flow,and evolutionary processes(Coyne and Orr,2004).展开更多
Gate drivers for high-voltage silicon carbide(SiC)converters require a reliable power supply with strong isolation and compact size.However,existing gate driver power supplies(GDPS)with the transformer structure make ...Gate drivers for high-voltage silicon carbide(SiC)converters require a reliable power supply with strong isolation and compact size.However,existing gate driver power supplies(GDPS)with the transformer structure make it difficult to enhance the isolation performance while keeping the small coupling capacitance and volume.This paper firstly presents a novel wireless GDPS with an improved Class-E inverter for high-voltage energy harvesting applications.The proposed design requires only one switch and reduces the input inductor significantly.Meanwhile,it solves the issue of harmful surge currents and maintains a zero-voltage-switching state when the load changes.Finally,a compact wireless GDPS prototype is developed and the insulation characteristics are studied.Results demonstrate that the proposed design achieves isolation voltage up to 17.7 kV with the smallest size volume and extra-low coupling capacitance of 1.83 pF.展开更多
Finding an optimal isolator arrangement for asymmetric structures using traditional conceptual design methods that can significantly minimize torsional response while ensuring efficient horizontal seismic isolation is...Finding an optimal isolator arrangement for asymmetric structures using traditional conceptual design methods that can significantly minimize torsional response while ensuring efficient horizontal seismic isolation is cumbersome and inefficient.Thus,this work develops a multi-objective optimization method to enhance the torsional resistance of asymmetric base-isolated structures.The primary objective is to simultaneously minimize the interstory rotation of the superstructure,the rotation of the isolation layer,and the interstory displacement of the superstructure without exceeding the isolator displacement limits.A fast non-dominated sorting genetic algorithm(NSGA-Ⅱ)is employed to satisfy this optimization objective.Subsequently,the isolator arrangement,encompassing both positions and categories,is optimized according to this multi-objective optimization method.Additionally,an optimization design platform is developed to streamline the design operation.This platform integrates the input of optimization parameters,the output of optimization results,the finite element analysis,and the multi-objective optimization method proposed herein.Finally,the application of this multi-objective optimization method and its associated platform are demonstrated on two asymmetric base-isolated structures of varying heights and plan configurations.The results indicate that the optimal isolator arrangement derived from the optimization method can further improve the control over the lateral and torsional responses of asymmetric base-isolated structures compared to conventional conceptual design methods.Notably,the interstory rotation of the optimal base-isolated structure is significantly reduced,constituting only approximately 33.7%of that observed in the original base-isolated structure.The proposed platform facilitates the automatic generation of the optimal design scheme for the isolators of asymmetric base-isolated structures,offering valuable insights and guidance for the burgeoning field of intelligent civil engineering design.展开更多
Strong surface impact will produce strong vibration,which will pose a threat to the safety of nearby buried pipelines and other important lifeline projects.Based on the verified numerical method,a comprehensive numeri...Strong surface impact will produce strong vibration,which will pose a threat to the safety of nearby buried pipelines and other important lifeline projects.Based on the verified numerical method,a comprehensive numerical parameter analysis is conducted on the key influencing factors of the vibration isolation hole(VIH),which include hole diameter,hole net spacing,hole depth,hole number,hole arrangement,and soil parameters.The results indicate that a smaller ratio of net spacing to hole diameter,the deeper the hole,the multi-row hole,the hole adoption of staggered arrangements,and better site soil conditions can enhance the efficiency of the VIH barrier.The average maximum vibration reduction efficiency within the vibration isolation area can reach 42.2%.The vibration safety of adjacent oil pipelines during a dynamic compaction projection was evaluated according to existing standards,and the measurement of the VIH was recommended to reduce excessive vibration.The single-row vibration isolation scheme and three-row staggered arrangement with the same hole parameters are suggested according to different cases.The research findings can serve as a reference for the vibration safety analysis,assessment,and control of adjacent underground facilities under the influence of strong surface impact loads.展开更多
BACKGROUND Frailty has become a significant public health issue.The recent increase in the number of frail older adults has led to increased attention being paid to psycho-logical care services in communities.The soci...BACKGROUND Frailty has become a significant public health issue.The recent increase in the number of frail older adults has led to increased attention being paid to psycho-logical care services in communities.The social isolation of pre-frail older adults can impact their psychological distress.AIM To explore the mediating effect of health literacy between social isolation and psychological distress among communitydwelling older adults with pre-frailty.METHODS This descriptive cross-sectional study was conducted with 254 pre-frail older individuals aged 60 years and over.Social isolation,health literacy,and psycholo-gical distress were comprehensively measured using the Lubben Social Network Scale-6,12-item Short-Form Health Literacy Questionnaire,and the Kessler Psy-chological Distress Scale-10.Data were evaluated using the SPSS 27.0 package program and the PROCESS macro tool.Descriptive statistical analyses,correlation analyses,and bootstrap mediation tests were used to assess associations between the variables.RESULTS The results showed that social isolation had an effect on health literacy among pre-frail older adults(β=0.240,P<0.001),social isolation impact on psycho-logical distress pre-frail older adults(β=-0.415,P<0.001);health literacy was identified effect on psychological distress among pre-frail older persons(β=-0.307,P<0.001).Health literacy partially mediated the relationship between social isolation and psychological distress among community-dwelling older adults with pre-frailty,with a mediation effect of-0.074,accounting for 17.83%of the total effect.展开更多
The multi-terminal direct current(DC)grid has extinctive superiorities over the traditional alternating current system in integrating large-scale renewable energy.Both the DC circuit breaker(DCCB)and the current flow ...The multi-terminal direct current(DC)grid has extinctive superiorities over the traditional alternating current system in integrating large-scale renewable energy.Both the DC circuit breaker(DCCB)and the current flow controller(CFC)are demanded to ensure the multiterminal DC grid to operates reliably and flexibly.However,since the CFC and the DCCB are all based on fully controlled semiconductor switches(e.g.,insulated gate bipolar transistor,integrated gate commutated thyristor,etc.),their separation configuration in the multiterminal DC grid will lead to unaffordable implementation costs and conduction power losses.To solve these problems,integrated equipment with both current flow control and fault isolation abilities is proposed,which shares the expensive and duplicated components of CFCs and DCCBs among adjacent lines.In addition,the complicated coordination control of CFCs and DCCBs can be avoided by adopting the integrated equipment in themultiterminal DC grid.In order to examine the current flow control and fault isolation abilities of the integrated equipment,the simulation model of a specific meshed four-terminal DC grid is constructed in the PSCAD/EMTDC software.Finally,the comparison between the integrated equipment and the separate solution is presented a specific result or conclusion needs to be added to the abstract.展开更多
A staircase provides the main escape way from a building in an emergency.Unfortunately,it may suffer severe damages or even collapse during an earthquake.For improving the seismic performance of staircases,this paper ...A staircase provides the main escape way from a building in an emergency.Unfortunately,it may suffer severe damages or even collapse during an earthquake.For improving the seismic performance of staircases,this paper proposes an innovative staircase isolator with the features of lightweight,costeffective and ease of construction and replacement,which is formed by suitable engineering plastic shims between rubber layers.A connection construction scheme is also proposed for the isolated staircase.Systematic performance tests have been carried out to characterize the isolator in terms of mechanic behavior and ultimate states.The test results show that mechanical properties of the proposed staircase isolator are excellent and suitable for staircase in building structure.In order to investigate the influence of staircase on building structural responses,time history analyses of a typical building structure without staircase(WS),with fixed staircase(FS)and with isolated staircase(IS)are conducted and compared within the environment of SAP2000.Results show that staircase isolation can effectively eliminate the diagonal bracing effect of staircase slab and make structural components uniformly stressed.When the novel isolator is employed for staircase in a building structure,there is no vulnerable position in staircase and the performance of staircase in building structure can be greatly enhanced.展开更多
Staphylococcus aureus (S. aureus) is a bacterial pathogen for humans and animals. These bacteria can resist against many antibiotics and this resistance constitute an alarming worldwide human health threat due to the ...Staphylococcus aureus (S. aureus) is a bacterial pathogen for humans and animals. These bacteria can resist against many antibiotics and this resistance constitute an alarming worldwide human health threat due to the morbidity and mortality. Phage therapy is one of the alternative treatments. The aim of this study was to isolate and characterize lytic phages of S. aureus from different wastewater sources in Bobo-Dioulasso, Burkina Faso. Eight strains of S. aureus were isolated from different clinical samples and were used to isolate phages. The isolation and host range of phages were done by the spot test. Phages were purified by the double-layer method. Similar phages after the determination of the host range were characterized using restriction enzymes. A total of 27 phages were obtained after isolation and purification. Nine of the 27 isolates reported a broad host range (≥67%). The results of enzymatic digestion allowed to consider that all phage isolates that presented the same host range and the same genetic fingerprint are the same phage strain;whereas phages that presented the same host range and different genetic fingerprints are different phage strains. Thus, a total of 15 distinct phages isolates specific to S. aureus were characterized. This study highlighted the abundance and lytic capacity of phages isolated from wastewater from Bobo-Dioulasso’s environment against clinical strains of S. aureus. The lytic capacity of these Staphyphages could be an effective alternative tool to combat bacteria multi-resistance.展开更多
Hypertension, often called the “silent killer”, is a major risk factor for heart attacks and strokes in the elderly. Its effective management is crucial to prevent damage to the heart, brain, and kidneys. Isolated s...Hypertension, often called the “silent killer”, is a major risk factor for heart attacks and strokes in the elderly. Its effective management is crucial to prevent damage to the heart, brain, and kidneys. Isolated systolic hypertension (ISH) is particularly critical in the elderly population. Cardiovascular risk factors, including pulse pressure and wave velocity, are closely associated with systolic blood pressure and influenced by arterial stiffness and wave reflections. Managing ISH is complex due to the potential negative effects of certain medications and individual variability in treatment response. This paper will address these issues, evaluating antihypertensive drugs, combination therapy, personalized treatment plans, and updated guidelines for managing ISH.展开更多
Objective:This study investigated the outcomes of microsurgical subinguinal varicocelectomy(MSV)on semen and hormonal parameters in cases with isolated sperm defects(oligozoospermia,asthenozoospermia,or teratozoosperm...Objective:This study investigated the outcomes of microsurgical subinguinal varicocelectomy(MSV)on semen and hormonal parameters in cases with isolated sperm defects(oligozoospermia,asthenozoospermia,or teratozoospermia).Methods:A retrospective review of charts of patients who underwent MSV for clinically palpable varicocele between January 1,2011 and January 1,2019 at Hamad Medical Corporation was undertaken.All patients diagnosed with isolated oligozoospermia,asthenozoospermia,or teratozoospermia in the preoperative semen analysis were included.Men with multiple sperm defects,genetic abnormalities,azoospermia,history of genitourinary infection,exposure to chemotherapy or radiotherapy,or prior use of peri-operative fertility treatment were excluded.Data extracted from the electronic medical records included(collected before MSV and up to 6 months postoperatively):demographics(age),clinical data(fertility-related medical history and surgical interventions),family history(consanguinity and infertility),physical examination findings from general and local genital exam(varicocele side and grade),laboratory data such as semen analysis,sperm DNA fragmentation tests,and hormone levels(follicle-stimulating hormone,luteinizing hormone,total testosterone,estradiol,and prolactin),and imaging(scrotal color Doppler ultrasound).Results:A total of 331 patients with isolated sperm defects were included.Postoperatively,83.3%of patients showed an improvement in sperm concentration with a median increase of 7 millions/mL.Postoperatively,76.7%of isolated asthenozoospermic patients showed an improvement in total motility and 66.0%had an improvement in progressive motility with median increases of 15.0%and 7.5%,respectively.Postoperatively,70.0%of the teratozoospermic patients showed an improvement in normal sperm morphology with a median increase of 6%.No changes were observed in other semen or hormone parameters that were examined.Conclusion:MSV is a valid and effective treatment modality for patients with isolated sperm defects that significantly corrects their respective semen abnormality and improves their chances of natural conception.展开更多
Traditional linear vibration isolators struggle to combine high load-bearing capacity with low-frequency vibration isolation, whereas nonlinear metastructure isolators can effectively fulfill both functions. This pape...Traditional linear vibration isolators struggle to combine high load-bearing capacity with low-frequency vibration isolation, whereas nonlinear metastructure isolators can effectively fulfill both functions. This paper draws inspiration from the Quasi-Zero Stiffness (QZS) characteristics resulting from the buckling deformation of beams, and proposes a gear-based QZS structure by arranging beams in a circular array. We investigated the static mechanical behavior under different structural parameters, loading angles, and gear combinations through experiments and simulations, and demonstrated the mechanical performances could be effectively programmed. Subsequent vibration isolation tests on the double gears prove superior vibration isolation performance at low frequency while maintaining high load-bearing capacities. Additionally, a key contribution of our work is the development of a mathematical model to characterize the buckling behavior of the unit beam within the gear structure, with its accuracy validated through finite element analysis and experimental results. The gear’s modulus, number of teeth, and pressure angle are selected according to standard series, allowing the gear can be seamlessly integrated into existing mechanical systems in critical fields such as aerospace, military, and etc.展开更多
Traffic-induced ground vibrations cause significant problems for residents and nearby structures.Reducing the effect of these vibrations on the neighboring environment is a key challenge,particularly in urban areas.Th...Traffic-induced ground vibrations cause significant problems for residents and nearby structures.Reducing the effect of these vibrations on the neighboring environment is a key challenge,particularly in urban areas.This study presents both numerical and experimental investigations of the performance of mass scatters for screening ground vibrations.A three-dimensional numerical model is validated and extended to conduct a comparative study on the efficiency of three geotechnical methods of isolation.These methods include trench barriers,waveimpeding blocks(WIBs),and mass scatters.The results showed that mass scatters represent an efficient way of scattering ground vibrations,and their efficiency is mainly related to the weights of mass scatters and their natural frequency,which control the dynamic soil response in the frequency domain.Rigid trench barriers are less effective than soft ones,and their efficiency is more pronounced regarding the WIB.Soft barriers with a depth of an order of half of the wavelength can decrease the vibration levels by up to 50%,which is comparable to the performance of enormous mass scatters.The dimensions of WIBs must be chosen according to the wavelength of incident waves and the cutoff frequency of the topsoil layer.Considering the significant wavelength of traffic-induced vibration,the use of trench barriers or WIBs becomes impractical and expensive;therefore,mass scatters appear to be an efficient and practical solution.展开更多
Panax notoginseng is a traditional Chinese medicine containing various constituents,including the saponins,polysaccharides,polyacetylenes,amino acids,etc.It has beneficial functions,such as the anti-inflammatory,antit...Panax notoginseng is a traditional Chinese medicine containing various constituents,including the saponins,polysaccharides,polyacetylenes,amino acids,etc.It has beneficial functions,such as the anti-inflammatory,antitumor,hepatoprotective,and anti-aging effects.Among these,P.notoginseng polysaccharides(PNPs)have been exploited because of their extensive pharmacological effects,being ranked as one of the current research hotspots,especially for the functional foods and medical practice.In this review,the literature related to PNPs in the past 20 years was surveyed and analyzed using both the China National Knowledge Infrastructure(CNKI)and Web of Science(WOS)databases.The visualization diagram shows that current studies on PNPs mainly focus on the antioxidant and immunomodulatory activities and structural characterization.In addition,the extraction,separation,purification,chemical analysis,structural characteristics,bioactivities,and applications of PNPs are outlined,in detail,aimed to provide valuable information for the further study,development,and utilization regarding PNPs.展开更多
BACKGROUND Sleep disorders are common health problems in the elderly.The effect of social isolation on sleep duration and sleep quality remains unclear in the Chinese community-dwelling elderly.AIM To explore the asso...BACKGROUND Sleep disorders are common health problems in the elderly.The effect of social isolation on sleep duration and sleep quality remains unclear in the Chinese community-dwelling elderly.AIM To explore the associations of social isolation with sleep duration and sleep quality in community-dwelling elderly people.METHODS A total of 7762 community-dwelling elderly people aged 60 years and older in Ningbo were recruited from June 2022 to August 2022.Data were collected using a questionnaire.Multivariate logistic regression was used to analyze the associations of social isolation with sleep duration and sleep quality.The KHB mediating effect model was used to test the mediating effect of depression and anxiety on these associations.RESULTS Among the participants,2656(34.2%)had abnormal sleep duration(<6 hours or>8 hours),1115(14.4%)had poor sleep quality,and 917(11.8%)had social isolation.After adjusting for confounding factors,compared with the elderly without social isolation,the odds ratios(95%CI)of abnormal sleep duration and poor sleep quality in the elderly with social isolation were 1.49(1.29-1.73)and 1.32(1.09-1.59),respectively.Depression partially mediated the associations of social isolation with sleep duration and sleep quality,accounting for 5.68%and 9.87%of the mediating effect,respectively.CONCLUSION Social isolation was found to be associated with sleep duration and sleep quality in community-dwelling elderly people.More attention should be paid to social isolation in the elderly.展开更多
Hydro-pneumatic near-zero frequency(NZF)vibration isolators have better performance at isolating vibration with low frequencies and heavy loadings when the nonlinear fluidic damping is introduced and the pressurized g...Hydro-pneumatic near-zero frequency(NZF)vibration isolators have better performance at isolating vibration with low frequencies and heavy loadings when the nonlinear fluidic damping is introduced and the pressurized gas pressure is properly adjusted.The nonlinear characteristics of such devices make their corresponding dynamic research involve chaotic dynamics.Chaos may bring negative influence and disorder to the structure and low-frequency working efficiency of isolators,which makes it necessary to clarify and control the threshold ranges for chaos generation in advance.In this work,the chaotic characteristics for a class of hydro-pneumatic NZF vibration isolators under dry friction,harmonic,and environmental noise excitations are analyzed by the analytical and numerical methods.The parameter ranges for the generation of chaos are obtained by the classical and random Melnikov methods.The chaotic characteristics and thresholds of the parameters in the systems with or without noise excitation are discussed and described.The analytical solutions and the influence of noise and harmonic excitation about chaos are tested and further analyzed through many numerical simulations.The results show that chaos in the system can be induced or inhibited with the adjustment of the magnitudes of harmonic excitation and noise intensity.展开更多
BACKGROUND Atrial fibrillation(AF)is the most common cardiac arrhythmia worldwide,hosting numerous serious possible complications such as stroke and heart failure.In the past two decades,managing rhythm control was mo...BACKGROUND Atrial fibrillation(AF)is the most common cardiac arrhythmia worldwide,hosting numerous serious possible complications such as stroke and heart failure.In the past two decades,managing rhythm control was more successful via pulmonary vein isolation(PVI)ablation,generally performed via transfemoral access.Patients with anatomical variations may necessitate a dose of creativity and evidence-based techniques.To our knowledge,we present the first PVI case in a patient with AF via right internal jugular(IJ)vein access using pulse field ablation.CASE SUMMARY A 76-year-old male with an extensive medical history notable for type 2 diabetes and severe peripheral vascular disease requiring vascular bypass surgery is identified to have paroxysmal AF.Given functional decline and worsening arrhythmia burden refractory to oral antiarrhythmics,an initial PVI ablation was attempted but failed as the catheter could not be advanced secondary to bilateral iliac vein occlusions.This necessitated a novel approach and a subsequent PVI ablation via the right IJ vein was successful without any complications.The success of this case highlights the feasibility of an IJ approach for PVI in patients where traditional access is not possible.This case can be used as a reference for other practitioners who may face similar challenges when attempting to perform PVI for AF or similar procedures requiring access to similar anatomical locations.CONCLUSION The success of this case highlights the feasibility of an IJ approach for PVI when traditional access is impossible.展开更多
基金supported by the National Key Research and Development Program of China(Nos.2023YFB4603900,2023YFB4603901)the National Natural Science Foundation of China(No.52275255)。
文摘Devices on aircraft are subjected to complex environmental excitations that pose risks to their operational safety.Passive vibration isolation techniques are extensively employed due to their advantage of not requiring additional energy sources.This paper introduces a novel metallic vibration isolator based on zigzag structures.The proposed isolator features a compact design and can be manufactured using additive manufacturing techniques,allowing for the integration of structural and functional elements.Firstly,the vibration response of the single-degree-of-freedom(SDOF)system is analyzed.To achieve effective vibration reduction,it is crucial for the isolator's stiffness to be sufficiently low.Secondly,to obtain a structure with high compliance,the traversal algorithm and the finite element method(FEM)are applied.The results confirm that the zigzag structure is a reliable high-compliance configuration.Thirdly,the parametric geometric model of the zigzag structure is developed and its stiffness is calculated.Quasi-static compression experiments validate the accuracy of the calculations.Finally,a specific engineering example is considered,where a zigzag vibration isolator is designed and fabricated.Vibration experiments demonstrate that the zigzag isolator effectively reduces both the stiffness and the fundamental frequency of the vibration system,achieving a vibration isolation efficiency exceeding 60%.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.12002195 and 12372015)the National Science Fund for Distinguished Young Scholars(Grant No.12025204)the Program of Shanghai Municipal Education Commission(Grant No.2019-01-07-00-09-E00018).
文摘This work discusses the strain and acceleration suppression of a flexible beam subjected to different supports analytically.As classical protection,the beam is mounted on a vertical linear spring together with a linear damper in parallel.This is called linear isolation.To enhance isolation performance,nonlinearity is employed in the boundary.In addition,quasi-zero isolation is established based on the non-linearly enhanced one by adjusting the installation length of the horizontal spring.To discuss their performance fully and fairly,the amplitude,the acceleration,the potential energy of the beam,the input work of the excitation,the dissipation work of the beam,and the dynamics stress along the beam are investigated based on the same parameters.The comparison shows that all these isolations can protect the beam with high efficiency,even when the basement excitation is tiny.Although the linear isolation and the nonlinearly enhanced one will arouse two resonance peaks on both sides of the primary resonance of the beam without isolation,the maximum amplitudes of them are reduced a lot.But for the low frequency excitation,the quasi-zero isolation has the best performance as it drives the primary resonance to the high frequency region.The simulation shows that the beam needs a relatively soft isolation to avoid the damage caused by the shock vibration,including the quasi-zero one.In general,the quasi-zero isolation shows the best performance.The nonlinearly enhanced one is the suboptimal choice.The present work shows the capacities of three isolations for a flexible beam by the steady-state response and the shock vibration.It provides design suggestions for the isolation of flexible beams.
基金supported in part by the National Natural Science Foundation of China under Grant U23A20353.
文摘Isolated power converters have emerged as an active research topic in power integrated circuit(IC)design.Reflecting this growing interest,ISSCC 2025 has featured a dedicated session on"Isolated Power and Gate Drivers".These converters enable safe and reliable power delivery across voltage domains and are widely used in renewable energy,electric vehicles,and telecommunications.Galvanic isolation prevents surge currents and ground loop issues in harsh high-voltage environments.As demand grows for compact,efficient,and high–power-density solutions,fully integrated architectures featuring on-chip transformers are increasingly favored over traditional module-based designs,offering>5 kV isolation with a smaller footprint and lower system cost[1].
基金supported by the National Natural Science Foundation of China(No.32161143024,31970405)Iran National Science Foundation,Iran-China(INSF-NSFC)joint project(No.4002006).
文摘The biological species concept defines species as groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups(Mayr,1942).Reproductive isolation,whether prezygotic or postzygotic,plays a central role in maintaining species boundaries.However,hybridization between closely related taxa can challenge these boundaries and provide insight into speciation,gene flow,and evolutionary processes(Coyne and Orr,2004).
基金Chongqing Technological Innovation and Application Development Major Project,Grant/Award Number:CSTB2024TIAD-STX0024.
文摘Gate drivers for high-voltage silicon carbide(SiC)converters require a reliable power supply with strong isolation and compact size.However,existing gate driver power supplies(GDPS)with the transformer structure make it difficult to enhance the isolation performance while keeping the small coupling capacitance and volume.This paper firstly presents a novel wireless GDPS with an improved Class-E inverter for high-voltage energy harvesting applications.The proposed design requires only one switch and reduces the input inductor significantly.Meanwhile,it solves the issue of harmful surge currents and maintains a zero-voltage-switching state when the load changes.Finally,a compact wireless GDPS prototype is developed and the insulation characteristics are studied.Results demonstrate that the proposed design achieves isolation voltage up to 17.7 kV with the smallest size volume and extra-low coupling capacitance of 1.83 pF.
基金National Natural Science Foundation of China under Grant No.52278490。
文摘Finding an optimal isolator arrangement for asymmetric structures using traditional conceptual design methods that can significantly minimize torsional response while ensuring efficient horizontal seismic isolation is cumbersome and inefficient.Thus,this work develops a multi-objective optimization method to enhance the torsional resistance of asymmetric base-isolated structures.The primary objective is to simultaneously minimize the interstory rotation of the superstructure,the rotation of the isolation layer,and the interstory displacement of the superstructure without exceeding the isolator displacement limits.A fast non-dominated sorting genetic algorithm(NSGA-Ⅱ)is employed to satisfy this optimization objective.Subsequently,the isolator arrangement,encompassing both positions and categories,is optimized according to this multi-objective optimization method.Additionally,an optimization design platform is developed to streamline the design operation.This platform integrates the input of optimization parameters,the output of optimization results,the finite element analysis,and the multi-objective optimization method proposed herein.Finally,the application of this multi-objective optimization method and its associated platform are demonstrated on two asymmetric base-isolated structures of varying heights and plan configurations.The results indicate that the optimal isolator arrangement derived from the optimization method can further improve the control over the lateral and torsional responses of asymmetric base-isolated structures compared to conventional conceptual design methods.Notably,the interstory rotation of the optimal base-isolated structure is significantly reduced,constituting only approximately 33.7%of that observed in the original base-isolated structure.The proposed platform facilitates the automatic generation of the optimal design scheme for the isolators of asymmetric base-isolated structures,offering valuable insights and guidance for the burgeoning field of intelligent civil engineering design.
基金National Natural Science Foundation of China under Grant Nos.52078386 and 52308496SINOMACH Youth Science and Technology Fund under Grant No.QNJJ-PY-2022-02+2 种基金Young Elite Scientists Sponsorship Program under Grant No.BYESS2023432Fund of State Key Laboratory of Precision Blasting and Hubei Key Laboratory of Blasting Engineering,Jianghan University under Grant No.PBSKL2023A9Fund of China Railway Construction Group Co.,Ltd.under Grant No.LX19-04b。
文摘Strong surface impact will produce strong vibration,which will pose a threat to the safety of nearby buried pipelines and other important lifeline projects.Based on the verified numerical method,a comprehensive numerical parameter analysis is conducted on the key influencing factors of the vibration isolation hole(VIH),which include hole diameter,hole net spacing,hole depth,hole number,hole arrangement,and soil parameters.The results indicate that a smaller ratio of net spacing to hole diameter,the deeper the hole,the multi-row hole,the hole adoption of staggered arrangements,and better site soil conditions can enhance the efficiency of the VIH barrier.The average maximum vibration reduction efficiency within the vibration isolation area can reach 42.2%.The vibration safety of adjacent oil pipelines during a dynamic compaction projection was evaluated according to existing standards,and the measurement of the VIH was recommended to reduce excessive vibration.The single-row vibration isolation scheme and three-row staggered arrangement with the same hole parameters are suggested according to different cases.The research findings can serve as a reference for the vibration safety analysis,assessment,and control of adjacent underground facilities under the influence of strong surface impact loads.
基金Supported by the Scientific Research Fund of Zhejiang Provincial Education Department,No.Y202351104and Huzhou Science and Technology Plan Project,No.2023GZ67。
文摘BACKGROUND Frailty has become a significant public health issue.The recent increase in the number of frail older adults has led to increased attention being paid to psycho-logical care services in communities.The social isolation of pre-frail older adults can impact their psychological distress.AIM To explore the mediating effect of health literacy between social isolation and psychological distress among communitydwelling older adults with pre-frailty.METHODS This descriptive cross-sectional study was conducted with 254 pre-frail older individuals aged 60 years and over.Social isolation,health literacy,and psycholo-gical distress were comprehensively measured using the Lubben Social Network Scale-6,12-item Short-Form Health Literacy Questionnaire,and the Kessler Psy-chological Distress Scale-10.Data were evaluated using the SPSS 27.0 package program and the PROCESS macro tool.Descriptive statistical analyses,correlation analyses,and bootstrap mediation tests were used to assess associations between the variables.RESULTS The results showed that social isolation had an effect on health literacy among pre-frail older adults(β=0.240,P<0.001),social isolation impact on psycho-logical distress pre-frail older adults(β=-0.415,P<0.001);health literacy was identified effect on psychological distress among pre-frail older persons(β=-0.307,P<0.001).Health literacy partially mediated the relationship between social isolation and psychological distress among community-dwelling older adults with pre-frailty,with a mediation effect of-0.074,accounting for 17.83%of the total effect.
基金supported in part by Natural Science Foundation of Jiangsu Province under Grant BK20230255Natural Science Foundation of Shandong Province under Grant ZR2023QE281.
文摘The multi-terminal direct current(DC)grid has extinctive superiorities over the traditional alternating current system in integrating large-scale renewable energy.Both the DC circuit breaker(DCCB)and the current flow controller(CFC)are demanded to ensure the multiterminal DC grid to operates reliably and flexibly.However,since the CFC and the DCCB are all based on fully controlled semiconductor switches(e.g.,insulated gate bipolar transistor,integrated gate commutated thyristor,etc.),their separation configuration in the multiterminal DC grid will lead to unaffordable implementation costs and conduction power losses.To solve these problems,integrated equipment with both current flow control and fault isolation abilities is proposed,which shares the expensive and duplicated components of CFCs and DCCBs among adjacent lines.In addition,the complicated coordination control of CFCs and DCCBs can be avoided by adopting the integrated equipment in themultiterminal DC grid.In order to examine the current flow control and fault isolation abilities of the integrated equipment,the simulation model of a specific meshed four-terminal DC grid is constructed in the PSCAD/EMTDC software.Finally,the comparison between the integrated equipment and the separate solution is presented a specific result or conclusion needs to be added to the abstract.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2017YFC0703600)the National Natural Science Foundation of China(Grant Nos.51278138,51978185)+1 种基金Yangcheng Scholar’s Program of Guangzhou Municipal Department of Education(Grant No.1201541630)Innovation Research Program for the Postgraduates of Guangzhou University(Grant No.2017GDJC-D16).
文摘A staircase provides the main escape way from a building in an emergency.Unfortunately,it may suffer severe damages or even collapse during an earthquake.For improving the seismic performance of staircases,this paper proposes an innovative staircase isolator with the features of lightweight,costeffective and ease of construction and replacement,which is formed by suitable engineering plastic shims between rubber layers.A connection construction scheme is also proposed for the isolated staircase.Systematic performance tests have been carried out to characterize the isolator in terms of mechanic behavior and ultimate states.The test results show that mechanical properties of the proposed staircase isolator are excellent and suitable for staircase in building structure.In order to investigate the influence of staircase on building structural responses,time history analyses of a typical building structure without staircase(WS),with fixed staircase(FS)and with isolated staircase(IS)are conducted and compared within the environment of SAP2000.Results show that staircase isolation can effectively eliminate the diagonal bracing effect of staircase slab and make structural components uniformly stressed.When the novel isolator is employed for staircase in a building structure,there is no vulnerable position in staircase and the performance of staircase in building structure can be greatly enhanced.
文摘Staphylococcus aureus (S. aureus) is a bacterial pathogen for humans and animals. These bacteria can resist against many antibiotics and this resistance constitute an alarming worldwide human health threat due to the morbidity and mortality. Phage therapy is one of the alternative treatments. The aim of this study was to isolate and characterize lytic phages of S. aureus from different wastewater sources in Bobo-Dioulasso, Burkina Faso. Eight strains of S. aureus were isolated from different clinical samples and were used to isolate phages. The isolation and host range of phages were done by the spot test. Phages were purified by the double-layer method. Similar phages after the determination of the host range were characterized using restriction enzymes. A total of 27 phages were obtained after isolation and purification. Nine of the 27 isolates reported a broad host range (≥67%). The results of enzymatic digestion allowed to consider that all phage isolates that presented the same host range and the same genetic fingerprint are the same phage strain;whereas phages that presented the same host range and different genetic fingerprints are different phage strains. Thus, a total of 15 distinct phages isolates specific to S. aureus were characterized. This study highlighted the abundance and lytic capacity of phages isolated from wastewater from Bobo-Dioulasso’s environment against clinical strains of S. aureus. The lytic capacity of these Staphyphages could be an effective alternative tool to combat bacteria multi-resistance.
文摘Hypertension, often called the “silent killer”, is a major risk factor for heart attacks and strokes in the elderly. Its effective management is crucial to prevent damage to the heart, brain, and kidneys. Isolated systolic hypertension (ISH) is particularly critical in the elderly population. Cardiovascular risk factors, including pulse pressure and wave velocity, are closely associated with systolic blood pressure and influenced by arterial stiffness and wave reflections. Managing ISH is complex due to the potential negative effects of certain medications and individual variability in treatment response. This paper will address these issues, evaluating antihypertensive drugs, combination therapy, personalized treatment plans, and updated guidelines for managing ISH.
文摘Objective:This study investigated the outcomes of microsurgical subinguinal varicocelectomy(MSV)on semen and hormonal parameters in cases with isolated sperm defects(oligozoospermia,asthenozoospermia,or teratozoospermia).Methods:A retrospective review of charts of patients who underwent MSV for clinically palpable varicocele between January 1,2011 and January 1,2019 at Hamad Medical Corporation was undertaken.All patients diagnosed with isolated oligozoospermia,asthenozoospermia,or teratozoospermia in the preoperative semen analysis were included.Men with multiple sperm defects,genetic abnormalities,azoospermia,history of genitourinary infection,exposure to chemotherapy or radiotherapy,or prior use of peri-operative fertility treatment were excluded.Data extracted from the electronic medical records included(collected before MSV and up to 6 months postoperatively):demographics(age),clinical data(fertility-related medical history and surgical interventions),family history(consanguinity and infertility),physical examination findings from general and local genital exam(varicocele side and grade),laboratory data such as semen analysis,sperm DNA fragmentation tests,and hormone levels(follicle-stimulating hormone,luteinizing hormone,total testosterone,estradiol,and prolactin),and imaging(scrotal color Doppler ultrasound).Results:A total of 331 patients with isolated sperm defects were included.Postoperatively,83.3%of patients showed an improvement in sperm concentration with a median increase of 7 millions/mL.Postoperatively,76.7%of isolated asthenozoospermic patients showed an improvement in total motility and 66.0%had an improvement in progressive motility with median increases of 15.0%and 7.5%,respectively.Postoperatively,70.0%of the teratozoospermic patients showed an improvement in normal sperm morphology with a median increase of 6%.No changes were observed in other semen or hormone parameters that were examined.Conclusion:MSV is a valid and effective treatment modality for patients with isolated sperm defects that significantly corrects their respective semen abnormality and improves their chances of natural conception.
基金supported in part by National Key R&D Program of China under Grant 2024YFB4708600National Natural Science Foundation of China under Grant 52305304+3 种基金Jilin Youth Growth Technology Project under Grant 20230508147RCthe Science and Technology Research Project of Jilin Provincial Education Department(No.JJKH20231193KJ)supported in part by the National Natural Science Foundation of China under Grant 52021003 and Grant 52205565in part by the Natural Science Foundation of Jilin Province under Grant 20210101053JC.
文摘Traditional linear vibration isolators struggle to combine high load-bearing capacity with low-frequency vibration isolation, whereas nonlinear metastructure isolators can effectively fulfill both functions. This paper draws inspiration from the Quasi-Zero Stiffness (QZS) characteristics resulting from the buckling deformation of beams, and proposes a gear-based QZS structure by arranging beams in a circular array. We investigated the static mechanical behavior under different structural parameters, loading angles, and gear combinations through experiments and simulations, and demonstrated the mechanical performances could be effectively programmed. Subsequent vibration isolation tests on the double gears prove superior vibration isolation performance at low frequency while maintaining high load-bearing capacities. Additionally, a key contribution of our work is the development of a mathematical model to characterize the buckling behavior of the unit beam within the gear structure, with its accuracy validated through finite element analysis and experimental results. The gear’s modulus, number of teeth, and pressure angle are selected according to standard series, allowing the gear can be seamlessly integrated into existing mechanical systems in critical fields such as aerospace, military, and etc.
文摘Traffic-induced ground vibrations cause significant problems for residents and nearby structures.Reducing the effect of these vibrations on the neighboring environment is a key challenge,particularly in urban areas.This study presents both numerical and experimental investigations of the performance of mass scatters for screening ground vibrations.A three-dimensional numerical model is validated and extended to conduct a comparative study on the efficiency of three geotechnical methods of isolation.These methods include trench barriers,waveimpeding blocks(WIBs),and mass scatters.The results showed that mass scatters represent an efficient way of scattering ground vibrations,and their efficiency is mainly related to the weights of mass scatters and their natural frequency,which control the dynamic soil response in the frequency domain.Rigid trench barriers are less effective than soft ones,and their efficiency is more pronounced regarding the WIB.Soft barriers with a depth of an order of half of the wavelength can decrease the vibration levels by up to 50%,which is comparable to the performance of enormous mass scatters.The dimensions of WIBs must be chosen according to the wavelength of incident waves and the cutoff frequency of the topsoil layer.Considering the significant wavelength of traffic-induced vibration,the use of trench barriers or WIBs becomes impractical and expensive;therefore,mass scatters appear to be an efficient and practical solution.
基金supported by the National Key R&D Program of China(2022YFC3501805)the Science and Technology Program of Tianjin in China(23ZYJDSS00030)+2 种基金the National Natural Science Foundation of China(82374030)the Science&Technology Development Fund of Tianjin Education Commission for Higher Education(2021KJ127)Tianjin Outstanding Youth Fund(23JCJQJC00030).
文摘Panax notoginseng is a traditional Chinese medicine containing various constituents,including the saponins,polysaccharides,polyacetylenes,amino acids,etc.It has beneficial functions,such as the anti-inflammatory,antitumor,hepatoprotective,and anti-aging effects.Among these,P.notoginseng polysaccharides(PNPs)have been exploited because of their extensive pharmacological effects,being ranked as one of the current research hotspots,especially for the functional foods and medical practice.In this review,the literature related to PNPs in the past 20 years was surveyed and analyzed using both the China National Knowledge Infrastructure(CNKI)and Web of Science(WOS)databases.The visualization diagram shows that current studies on PNPs mainly focus on the antioxidant and immunomodulatory activities and structural characterization.In addition,the extraction,separation,purification,chemical analysis,structural characteristics,bioactivities,and applications of PNPs are outlined,in detail,aimed to provide valuable information for the further study,development,and utilization regarding PNPs.
基金Supported by Ningbo Medical and Health Brand Discipline,No.PPXK2024-07and Ningbo Top Medical and Health Research Program,No.2022030410.
文摘BACKGROUND Sleep disorders are common health problems in the elderly.The effect of social isolation on sleep duration and sleep quality remains unclear in the Chinese community-dwelling elderly.AIM To explore the associations of social isolation with sleep duration and sleep quality in community-dwelling elderly people.METHODS A total of 7762 community-dwelling elderly people aged 60 years and older in Ningbo were recruited from June 2022 to August 2022.Data were collected using a questionnaire.Multivariate logistic regression was used to analyze the associations of social isolation with sleep duration and sleep quality.The KHB mediating effect model was used to test the mediating effect of depression and anxiety on these associations.RESULTS Among the participants,2656(34.2%)had abnormal sleep duration(<6 hours or>8 hours),1115(14.4%)had poor sleep quality,and 917(11.8%)had social isolation.After adjusting for confounding factors,compared with the elderly without social isolation,the odds ratios(95%CI)of abnormal sleep duration and poor sleep quality in the elderly with social isolation were 1.49(1.29-1.73)and 1.32(1.09-1.59),respectively.Depression partially mediated the associations of social isolation with sleep duration and sleep quality,accounting for 5.68%and 9.87%of the mediating effect,respectively.CONCLUSION Social isolation was found to be associated with sleep duration and sleep quality in community-dwelling elderly people.More attention should be paid to social isolation in the elderly.
基金Project supported by the National Natural Science Foundation of China(Nos.12172340 and12411530068)the Shenzhen Science and Technology Program(No.JCYJ20240813114012016)+2 种基金the High-Level Talent Introduction Plan of Guangzhou Citythe Fundamental Research Funds for the Central Universities-China University of Geosciences(Wuhan)(No.G1323524005)the Young Top-Notch Talent Cultivation Program of Hubei Province。
文摘Hydro-pneumatic near-zero frequency(NZF)vibration isolators have better performance at isolating vibration with low frequencies and heavy loadings when the nonlinear fluidic damping is introduced and the pressurized gas pressure is properly adjusted.The nonlinear characteristics of such devices make their corresponding dynamic research involve chaotic dynamics.Chaos may bring negative influence and disorder to the structure and low-frequency working efficiency of isolators,which makes it necessary to clarify and control the threshold ranges for chaos generation in advance.In this work,the chaotic characteristics for a class of hydro-pneumatic NZF vibration isolators under dry friction,harmonic,and environmental noise excitations are analyzed by the analytical and numerical methods.The parameter ranges for the generation of chaos are obtained by the classical and random Melnikov methods.The chaotic characteristics and thresholds of the parameters in the systems with or without noise excitation are discussed and described.The analytical solutions and the influence of noise and harmonic excitation about chaos are tested and further analyzed through many numerical simulations.The results show that chaos in the system can be induced or inhibited with the adjustment of the magnitudes of harmonic excitation and noise intensity.
文摘BACKGROUND Atrial fibrillation(AF)is the most common cardiac arrhythmia worldwide,hosting numerous serious possible complications such as stroke and heart failure.In the past two decades,managing rhythm control was more successful via pulmonary vein isolation(PVI)ablation,generally performed via transfemoral access.Patients with anatomical variations may necessitate a dose of creativity and evidence-based techniques.To our knowledge,we present the first PVI case in a patient with AF via right internal jugular(IJ)vein access using pulse field ablation.CASE SUMMARY A 76-year-old male with an extensive medical history notable for type 2 diabetes and severe peripheral vascular disease requiring vascular bypass surgery is identified to have paroxysmal AF.Given functional decline and worsening arrhythmia burden refractory to oral antiarrhythmics,an initial PVI ablation was attempted but failed as the catheter could not be advanced secondary to bilateral iliac vein occlusions.This necessitated a novel approach and a subsequent PVI ablation via the right IJ vein was successful without any complications.The success of this case highlights the feasibility of an IJ approach for PVI in patients where traditional access is not possible.This case can be used as a reference for other practitioners who may face similar challenges when attempting to perform PVI for AF or similar procedures requiring access to similar anatomical locations.CONCLUSION The success of this case highlights the feasibility of an IJ approach for PVI when traditional access is impossible.
