Background The effective orifice area(EOA)is utilized to characterize the hemodynamic performance of the transcatheter heart valve(THV).However,there is no consensus on EOA measurement of self-expanding THV.We aimed t...Background The effective orifice area(EOA)is utilized to characterize the hemodynamic performance of the transcatheter heart valve(THV).However,there is no consensus on EOA measurement of self-expanding THV.We aimed to compare two echocardiographic methods for EOA measurement following transcatheter self-expanding aortic valve implantation.Methods EOA was calculated according to the continuity equation.Two methods were constructed.In Method 1 and Method 2,the left ventricular outflow tract diameter(LVOTd)was measured at the entry of the prosthesis(from trailing-to-leading edge)and proximal to the prosthetic valve leaflets(from trailing-toleading edge),respectively.The velocity-time integral(VTI)of the LVOT(VTILVOT)was recorded by pulsed-wave Doppler(PW)from apical windows.The region of the PW sampling should match that of the LVOTd measurement with precise localization.The mean transvalvular pressure gradient(MG)and VTI of THV was measured by Continuous wave Doppler.Results A total of 113 consecutive patients were recruited.The mean age was 77.2±5.5 years,and 72 patients(63.7%)were male.EOA1 with the use of Method 1 was larger than EOA2(1.56±0.39 cm2 vs.1.48±0.41 cm2,P=0.001).MG correlated better with the indexed EOA1(EOAI1)(r=-0.701,P<0.001)than EOAI2(r=-0.645,P<0.001).According to EOAI(EOAI≤0.65 cm2/m2,respectively),the proportion of sever prosthesis-patient mismatch with the use of EOA1 was lower than EOA2(12.4%vs.21.2%,P<0.05).Compared with EOA2,EOA1 had lower interobserver and intra-observer variability(intra:0.5%±17%vs.3.8%±22%,P<0.001;inter:1.0%±9%vs.3.5%±11%,P<0.001).Conclusions For transcatheter self-expanding valve EOA measurement,LVOTd should be measured in the entry of the prosthesis stent(from trailing-to-leading edge),and VTILVOT should match that of the LVOTd measurement with precise localization.展开更多
A high-temperature and high-pressure valve is the key equipment of a wind tunnel system;it controls the generation of high-temperature and high-pressure gas.To reduce the adverse impact of high-temperature and high-pr...A high-temperature and high-pressure valve is the key equipment of a wind tunnel system;it controls the generation of high-temperature and high-pressure gas.To reduce the adverse impact of high-temperature and high-pressure gas on the strength of the valve body,a cooling structure is set on the valve seat.This can significantly reduce the temperature of the valve body and valve seat.The effects of its structure on the cooling characteristics and stress of the valve seat are studied,and six main parameters that can completely describe the geometry of the cooling structure are proposed.The central composite design method is used to select sample points,and the multi-objective genetic algorithm(MOGA)method is used for optimal structural design.A modification method according to the main parameters for the valve seat is proposed.The results show that the cooling structure weakens the pressure-bearing capability of the valve seat.Among the six main parameters of the valve seat,the distance from the end face of the lower hole to the Z-axis and the distance from the axis of the lower hole to the origin of the coordinates have the most obvious effects on the average stress of the valve seat.An optimum design value is proposed.This work can provide a reference for the design of high-temperature and high-pressure valves.展开更多
BACKGROUND The management of severe symptomatic aortic stenosis has been revolutionized by transcatheter aortic valve replacement(TAVR),offering a minimally invasive alternative to surgical aortic valve replacement(SA...BACKGROUND The management of severe symptomatic aortic stenosis has been revolutionized by transcatheter aortic valve replacement(TAVR),offering a minimally invasive alternative to surgical aortic valve replacement(SAVR).However,the compara-tive safety and efficacy of these interventions remain subjects of ongoing investigation.AIM To compare the clinical outcomes and safety of TAVR vs SAVR in patients with severe symptomatic aortic stenosis.METHODS A systematic review and meta-analysis were conducted according to PRISMA guidelines.Randomized controlled trials(RCTs)comparing TAVR and SAVR were identified from databases including PubMed,Scopus,and Web of Science up to May 31,2024.Data were extracted on clinical outcomes,including mortality,procedural compli-cations,and post-procedure adverse events.Risk ratios(RRs)with 95%CIs were calculated using a random-effects model.RESULTS A total of 10 RCTs were included.TAVR demonstrated a significantly lower risk of acute kidney injury(RR:0.33;95%CI:0.25–0.44),major bleeding(RR:0.37;95%CI:0.30–0.46),and new-onset atrial fibrillation(RR:0.44;95%CI:0.34–0.57)compared to SAVR.However,TAVR was associated with higher risks of new permanent pacemaker implantation(RR:3.49;95%CI:2.77–4.39),major vascular complications(RR:2.47;95%CI:1.91–3.21),and paraval-vular leaks(RR:4.15;95%CI:3.14–5.48).Mortality at 30 days was comparable(RR:0.95;95%CI:0.78–1.15),but long-term mortality was slightly higher with TAVR in some analyses(RR:1.23;95%CI:1.01–1.49).Rates of stroke(RR:0.97;95%CI:0.81–1.17)and myocardial infarction(RR:0.91;95%CI:0.67–1.24)were similar between the groups.CONCLUSION TAVR offers a less invasive option with significant benefits in reducing acute kidney injury,major bleeding,and new-onset atrial fibrillation,making it particularly advantageous for high-risk surgical candidates.However,higher risks of permanent pacemaker implantation,vascular complications,and paravalvular leaks highlight the need for individualized patient selection and shared decision-making to optimize outcomes.展开更多
Background There is scarce data about comparisons between geriatric assessment tools in patients with aortic stenosis(AS).We aimed to describe the geriatric profile of patients with AS undergoing transcatheter aortic ...Background There is scarce data about comparisons between geriatric assessment tools in patients with aortic stenosis(AS).We aimed to describe the geriatric profile of patients with AS undergoing transcatheter aortic valve implantation(TAVI)and to analyze the ability of different tools for predicting clinical outcomes in this context.Methods This was a single center retrospective registry including patients with AS undergoing TAVI and surviving to hospital discharge.The primary endpoint was all-cause mortality or need for urgent readmission one year after TAVI.Results A total of 377 patients were included(mean age of 80.4 years).Most patients were independent or mildly dependent,with an optimal cognitive status.The proportion of frailty ranged from 17.6%to 49.8%.A total of 20 patients(5.3%)died and 110/377 patients(29.2%)died or were readmitted during follow up.Overall,most components of the geriatric assessment showed an association with clinical outcomes.Disability for instrumental activities showed a significant association with mortality and a strong association with the rate of mortality or readmission.The association between frailty and clinical outcomes was higher for short physical performance battery(SPPB),essential frailty toolset(EFT)and the frailty index based on comprehensive geriatric assessment(IF-VIG)and lower for Fried criteria and FRAIL scale.Conclusions AS patients from this series presented a good physical performance,optimal cognitive status and a reasonably low prevalence of frailty.The best predictive ability was observed for disability for instrumental activities and frailty as measured by the EFT,SPPB and the IF-VIG.展开更多
The proliferation of wearable biodevices has boosted the development of soft,innovative,and multifunctional materials for human health monitoring.The integration of wearable sensors with intelligent systems is an over...The proliferation of wearable biodevices has boosted the development of soft,innovative,and multifunctional materials for human health monitoring.The integration of wearable sensors with intelligent systems is an overwhelming tendency,providing powerful tools for remote health monitoring and personal health management.Among many candidates,two-dimensional(2D)materials stand out due to several exotic mechanical,electrical,optical,and chemical properties that can be efficiently integrated into atomic-thin films.While previous reviews on 2D materials for biodevices primarily focus on conventional configurations and materials like graphene,the rapid development of new 2D materials with exotic properties has opened up novel applications,particularly in smart interaction and integrated functionalities.This review aims to consolidate recent progress,highlight the unique advantages of 2D materials,and guide future research by discussing existing challenges and opportunities in applying 2D materials for smart wearable biodevices.We begin with an in-depth analysis of the advantages,sensing mechanisms,and potential applications of 2D materials in wearable biodevice fabrication.Following this,we systematically discuss state-of-the-art biodevices based on 2D materials for monitoring various physiological signals within the human body.Special attention is given to showcasing the integration of multi-functionality in 2D smart devices,mainly including self-power supply,integrated diagnosis/treatment,and human–machine interaction.Finally,the review concludes with a concise summary of existing challenges and prospective solutions concerning the utilization of2D materials for advanced biodevices.展开更多
Bicuspid aortic valve (BAV) is a common congenital heart valve disease, often accompanied by aortic valve stenosis or regurgitation, infective endocarditis, and aortic diseases such as aortic dilation and dissection. ...Bicuspid aortic valve (BAV) is a common congenital heart valve disease, often accompanied by aortic valve stenosis or regurgitation, infective endocarditis, and aortic diseases such as aortic dilation and dissection. This article aims to review the definition, pathogenesis and genetic basis, classification methods, clinical features and current status of research and treatment and prognosis of BAV, and provide reference for the diagnosis and treatment of BAV. The content and structure of this article are as follows: The first part introduces the definition of BAV;The second part introduces the etiology and classification methods of BAV;The third part briefly describes the clinical manifestations and diagnosis of BAV;The fourth part discusses the treatment strategies and prognosis prediction of BAV;Finally, the article summarizes and looks forward to the future research directions.展开更多
A functional interlayer based on two-dimensional(2D)porous modified vermiculite nanosheets(PVS)was obtained by acid-etching vermiculite nanosheets.The as-obtained 2D porous nanosheets exhibited a high specific surface...A functional interlayer based on two-dimensional(2D)porous modified vermiculite nanosheets(PVS)was obtained by acid-etching vermiculite nanosheets.The as-obtained 2D porous nanosheets exhibited a high specific surface area of 427 m^(2)·g^(-1)and rich surface active sites,which help restrain polysulfides(LiPSs)through good physi-cal and chemical adsorption,while simultaneously accelerating the nucleation and dissolution kinetics of Li_(2)S,effec-tively suppressing the shuttle effect.The assembled lithium-sulfur batteries(LSBs)employing the PVS-based inter-layer delivered a high initial discharge capacity of 1386 mAh·g^(-1)at 0.1C(167.5 mAh·g^(-1)),long-term cycling stabil-ity,and good rate property.展开更多
This paper investigates ruin,capital injection,and dividends for a two-dimensional risk model.The model posits that surplus levels of insurance companies are governed by a perturbed composite Poisson risk model.This m...This paper investigates ruin,capital injection,and dividends for a two-dimensional risk model.The model posits that surplus levels of insurance companies are governed by a perturbed composite Poisson risk model.This model introduces a dependence between the two surplus levels,present in both the associated perturbations and the claims resulting from common shocks.Critical levels of capital injection and dividends are established for each of the two risks.The surplus levels are observed discretely at fixed intervals,guiding decisions on capital injection,dividends,and ruin at these junctures.This study employs a two-dimensional Fourier cosine series expansion method to approximate the finite time expected discounted operating cost until ruin.The ensuing approximation error is also quantified.The validity and accuracy of the method are corroborated through numerical examples.Furthermore,the research delves into the optimal capital allocation problem.展开更多
Pediatric heart valve replacement(PHVR)remains a challenging procedure due to the uniqueanatomical and physiological characteristics of children,including growth and development,as well asthe long-term need for durabl...Pediatric heart valve replacement(PHVR)remains a challenging procedure due to the uniqueanatomical and physiological characteristics of children,including growth and development,as well asthe long-term need for durable valve function.This review provides an overview of both surgical andtranscatheter options for aortic,mitral,pulmonary,and tricuspid valve replacements in pediatric patients,highlighting the indications,outcomes,and advancements in technology and technique.Surgical valvereplacement traditionally involves the implantation of biological or mechanical prosthetic valves,withbiologicalvalves beingpreferred in children to reduce the need for lifelong anticoagulation therapy.However,the limitation ofbiological prostheses,nanely their inability to grow with the child,necessitates the frequentneed for reoperations.Recent innovations in valve engineering,such as the development of tissue engineeredand expandable valves,aim to address these issues.Transcatheter valve replacement(TVR)has emergedas a promising alternative,particularly for patients with complex anatomy or those who are high-risk fortraditional surgery.While the use of transcatheter devices in children remains limited due to the smallervascular size and limited long-termn data,several studies have demonstrated the feasibility and safety ofthe procedure in certain patient populations.Despite these advancements,challenges related to valvesize,durability,and the need for individualized treatment planning persist.The future of pediatric heartvalve replacemnent will likely involve a multidisciplinary approach combining surgical,transcatheter,andregenerative medicine strategies,aimed at optimizing outcomes,reducing the need for reinterventions,andimproving long-term quality of life for pediatric patients with valvularheart disease.This article discussesall options availab le for patients with valvular dysfunction,making it easy for parents/patients to go to as areference source of information.展开更多
Objective: This study aims to investigate the drainage effect and clinical outcomes of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery, comparing the differences in postoperativ...Objective: This study aims to investigate the drainage effect and clinical outcomes of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery, comparing the differences in postoperative pain, hospital stay, and other factors between the negative pressure group and the control group. Methods: This study is a prospective controlled trial that selected patients undergoing two-port thoracoscopic valve surgery at a certain hospital from January 2019 to December 2024. Patients were randomly assigned to the control group and the negative pressure group using a random number table method. The control group consisted of 30 patients (20 males, 10 females, mean age 42.03 ± 12.89 years), and the negative pressure group consisted of 35 patients (26 males, 9 females, mean age 41.84 ± 11.83 years). The control group received traditional chest drainage, while the negative pressure group received negative pressure chest drainage. Postoperative pain scores, hospital stay, drainage time, number of tube blockages, and incidences of pneumothorax or subcutaneous emphysema were recorded and statistically analyzed. Results: The negative pressure group had a significantly shorter postoperative drainage time compared to the control group (49.09 ± 11.99 hours vs. 79.10 ± 7.32 hours, P < 0.001). The postoperative pain score was lower in the negative pressure group (4.49 ± 1.27 vs. 7.03 ± 0.85, P < 0.001), and the hospital stay was significantly shorter (9.83 ± 1.69 days vs. 14.73 ± 2.32 days, P < 0.001). The incidence of pneumothorax or subcutaneous emphysema was significantly lower in the negative pressure group than in the control group (14.29% vs. 56.67%, P = 0.0003). Conclusion: The application of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery can effectively reduce postoperative pain, shorten hospital stay, and lower the incidence of tube blockage and pneumothorax, demonstrating good clinical outcomes.展开更多
Lithium-sulfur(Li-S)batteries with high energy density and capacity have garnered significant research attention among various energy storage devices.However,the shuttle effect of polysulfides(LiPSs)remains a major ch...Lithium-sulfur(Li-S)batteries with high energy density and capacity have garnered significant research attention among various energy storage devices.However,the shuttle effect of polysulfides(LiPSs)remains a major challenge for their practical application.The design of battery separators has become a key aspect in addressing the challenge.MXenes,a promising two-dimensional(2D)material,offer exceptional conductivity,large surface area,high mechanical strength,and active sites for surface reactions.When assembled into layered films,MXenes form highly tunable two-dimensional channels ranging from a few angstroms to over 1 nm.These nanoconfined channels are instrumental in facilitating lithium-ion transport while effectively impeding the shuttle effect of LiPSs,which are essential for improving the specific capacity and cyclic stability of Li-S batteries.Substantial progress has been made in developing MXenes-based separators for Li-S batteries,yet there remains a research gap in summarizing advancements from the perspective of interlayer engineering.This entails maintaining the 2D nanochannels of layered MXenes-based separators while modulating the physicochemical environment within the MXenes interlayers through targeted modifications.This review highlights advancements in in situ modification of MXenes and their integration with 0D,1D,and 2D materials to construct laminated nanocomposite separators for Li-S batteries.The future development directions of MXenes-based materials in Li-S energy storage devices are also outlined,to drive further advancements in MXenes for Li-S battery separators.展开更多
Background Transcatheter Aortic Valve Implantation(TAVI)has changed the treatment paradigm of the aortic stenosis(AS).It has become the treatment of choice in patients with symptomatic AS and surgical high risk,and a ...Background Transcatheter Aortic Valve Implantation(TAVI)has changed the treatment paradigm of the aortic stenosis(AS).It has become the treatment of choice in patients with symptomatic AS and surgical high risk,and a valid alternative to surgical aortic valve replacement in patients with low and medium surgical risk.Despite numerous evidence on clinical results,indications and benefits,only a few studies analyse it from patient's perspective and the impact of TAVI on them.The objective of this study is to evaluate the experience of patients undergoing TAVI.Methods Cross-sectional,descriptive observational study in two Spanish hospitals,with a establish Nurse TAVI program,with100 patients undergoing TAVI.A specific questionnaire was designed(VALVEX questionnaire)and a pilot study was conducted by a multidisciplinary team of doctors,nurses and patients.The questionnaire was given to patients at 30 days after TAVI procedure during the follow up at the TAVI nurse clinic.Results The study demonstrated a mean satisfaction of 9 for the TAVI program,with 96%of patients that would recommend TAVI to other patients.Patients scored a high satisfaction on the information received prior to the procedure.During the procedure and admission,the satisfaction was high in relation to the care received.During the follow up,satisfaction was high in relation to the role of the TAVI nurse,for the information and continuation of care during the procedure,in reducing anxiety,organising their admission and understanding the process.However,questions with less scores were related to hospital catering,delay between diagnosed and treatment,and patient decision-making process.Conclusion The evaluation of patient experience allows us to improve the information given to the patient during their TAVI process and it can also allow patients to be more relax,aware and prepared for the procedure.Continuous follow up enables monitoring of patient recovery and helps to discuss any doubts improving patient's satisfaction.The use of PREMs and PROMs associated to TAVI pathway combined with an active participation of the patient on the design of the questionnaire is essential for keeping the patient in the centre of the TAVI pathway.展开更多
BACKGROUND The Perceval Sorin S(perceval valve)is a sutureless bioprosthetic designed for use in a high-risk cohort who may not be suitable for transcatheter aortic valve implantation or a conventional surgical aortic...BACKGROUND The Perceval Sorin S(perceval valve)is a sutureless bioprosthetic designed for use in a high-risk cohort who may not be suitable for transcatheter aortic valve implantation or a conventional surgical aortic valve replacement(AVR).AIM To compare five-year post-operative outcomes in a cohort undergoing isolated AVR with the perceval valve to a contemporary cohort undergoing surgical AVR with a sutured bioprosthesis.METHODS This study was a retrospective,cohort study at a single tertiary unit.Between 2017 and 2023,982 suitable patients were identified.174 Perceval valve replacements were matched to 174 sutured valve replacements.Cohort characteristics,intra-operative details,and post-operative outcomes were compared between the two groups.RESULTS Time under the aortic cross-clamp(P<0.001),time on the cardiopulmonary bypass(P<0.001)and total operative time(P<0.001)were significantly reduced in the Perceval group.Patients in the Perceval valve group were at a lower risk of postoperative pneumonia[odds ratio(OR)=0.53(0.29-0.94)]and atrial fibrillation[OR=0.58(0.36-0.93)].After propensity-matching,all-cause mortality did not significantly differ between the two groups in the five-year follow-up period.Larger valve sizes conferred an increased risk of mortality(P=0.020).CONCLUSION Sutureless surgical AVR(SAVR)is a safe and efficient alternative to SAVR with a sutured bioprosthesis,and may confer a reduced risk of post-operative atrial fibrillation.Clinician tendency towards‘oversizing’sutureless aortic valves translates into adverse clinical outcomes.Less time on the cardiopulmonary bypass circuit allows for the treatment of otherwise high-risk patients.展开更多
A bicuspid aortic valve,from autologous tissue,with growth potential can be constructed using the simple,and reproducible telescoping arterial trunk technique.
Transcatheter aortic valve replacement(TAVR)has emerged as an established standard of care for patients with severe aortic stenosis(AS),irrespective of their surgical risk.However,despite the continuous advancements o...Transcatheter aortic valve replacement(TAVR)has emerged as an established standard of care for patients with severe aortic stenosis(AS),irrespective of their surgical risk.However,despite the continuous advancements over last two decades,there are still significant challenges in field in terms of appropriate selection of patients as well as the valves.While there is no doubt that TAVR has now become the leading mode of treatment for severe AS patients,surgical aortic valve replacement(SAVR)still holds its value for the selective group of patients who are not ideal candidate for the minimally invasive procedure:TAVR.The dilemma is palpable in the clinical field that warrants best approach focusing on the lifetime management of these patients.In the recent metanalysis by Moradi et al,the authors provide a comprehensive insight into TAVR vs SAVR in terms of mortality,procedural complications,and post-procedure adverse events.In this editorial,we shed light on comparative analysis of both modalities to establish a middle ground.展开更多
BACKGROUND Aortic root dilation,linked to bicuspid aortic valve(BAV)or tricuspid aortic valve(TAV),risks aneurysm and dissection.Valve-sparing aortic root replacement(VSARR)preserves native valves,avoiding prosthetic ...BACKGROUND Aortic root dilation,linked to bicuspid aortic valve(BAV)or tricuspid aortic valve(TAV),risks aneurysm and dissection.Valve-sparing aortic root replacement(VSARR)preserves native valves,avoiding prosthetic valve complications.Longterm VSARR durability,especially in BAV patients,is debated.We hypothesize that VSARR outcomes differ between BAV and TAV patients in short-term and long-term settings.AIM To investigate short-term and long-term outcomes of VSARR in BAV vs TAV patients.METHODS This Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant meta-analysis included observational studies comparing VSARR in adult BAV vs TAV patients.PubMed,ScienceDirect,and EMBASE were searched from inception to June 2025.Outcomes included mortality,reintervention,and procedural times.Pooled relative risk(RR)and mean differences(MD)with 95%CI were calculated.Risk of bias was assessed using Risk of Bias in Non-randomized Studies of Interventions;evidence certainty via GRADE.RESULTS Thirteen observational studies involving 1419 BAV and 2349 TAV patients were included.In-hospital mortality(RR=0.34,95%CI:0.10-1.14,P=0.08)and reoperation(RR=1.04,95%CI:0.64-1.69,P=0.87)showed no significant differences.All-cause mortality risk was significantly lower in BAV patients(RR=0.34,95%CI:0.13-0.86,P=0.02).Overall reintervention risk was significantly greater in BAV patients(RR=2.64,95%CI:1.96-3.55,P<0.00001).Aortic cross-clamp(MD=3.35 minutes,95%CI:-5.06 to 11.76,P=0.43)and cardiopulmonary bypass times(MD=3.96 minutes,95%CI:-10.26 to 18.18,P=0.59)showed no significant differences but substantial heterogeneity.The certainty of evidence was moderate for reintervention,low for mortality risk and in-hospital reoperation,and very low for procedural times.CONCLUSION VSARR demonstrates comparable short-term safety between BAV and TAV patients.However,BAV patients face a significantly higher long-term reintervention risk,highlighting the need for tailored strategies and further research.展开更多
Magnetization convenience is crucial consideration for design of valve magnetic actuators.The existing repulsive-magnetic-coupling of 2D maglev valve is not oriented to the integral-magnetization-processes,resulting i...Magnetization convenience is crucial consideration for design of valve magnetic actuators.The existing repulsive-magnetic-coupling of 2D maglev valve is not oriented to the integral-magnetization-processes,resulting in the high assembly cost.This paper presents a novel tractive-magnetic-coupling(TMC)and its application on a 2D electro-hydraulic proportional flow valve(2D-EHPFV),whose configuration not only fulfill the requirements of 2D valve,but also oriented to integral-magnetization-process.To investigate the output torque of TMC,a detailed analytical model considering leakage flux,edge effect and tooth magnetic saturation is formulated based on the equivalent magnetic circuit method.To facilitate the magnetic saturation calculation,a special magnetic permeability database is established for tooth region of TMC using Ansoft/Maxwell software.Prototype of TMC is machined and an exclusive experimental platform is built.Torque-displacement characteristics under different working airgap and tooth number are measured.The experimental results are in good agreement with the analytical results,which verifies the correctness of the analytical model.Then the TMC is integrated into the 2D-EHPFV by replacing the repulsive-magnetic-coupling.Prototype of 2D-EHPFV is designed and manufactured to test the no-load flow characteristics,load flow characteristics,leakage characteristics,frequency characteristics and step response.Under working pressure of 15 MPa,the maximum no-load flow rate is 82.2 L/min with the hysteresis of 2.6%,and the amplitude and phase frequency width is 21.6 Hz,and 28.9 Hz.The detailed experimental results show that TMC can be applied to 2D valves to form 2D-EHPFV,which can reduce hysteresis and cost,and improve response speed.展开更多
Aortic stenosis(AS)is the most common valvular heart disease,with a prevalence of over 4%among octogenarians.[1]The prevalence of autopsy-confirmed wild-type transthyretin cardiac amyloidosis(ATTRwt-CA)increases with ...Aortic stenosis(AS)is the most common valvular heart disease,with a prevalence of over 4%among octogenarians.[1]The prevalence of autopsy-confirmed wild-type transthyretin cardiac amyloidosis(ATTRwt-CA)increases with age,accounting for 25%of patients aged 85 years and older in Europe and 12%of patients older than 80 years in Japan.[2,3]Recent studies have reported that ATTRwt-CA coexists in 11%-16%of older patients with AS undergoing transcatheter aortic valve replacement(TAVR).[1,4,5]In a metaanalysis by Ho et al.,[6]the prevalence rates of cardiac amyloidosis,predominantly ATTRwt-CA,in patients with AS and those referred for TAVR or surgical aortic valve replacement(SAVR)were 14.4%and 15.2%,respectively.Conversely,the prevalence of AS in patients with cardiac amyloidosis is 8.7%.Owing to the high surgical risk in patients with both AS and ATTRwt-CA,TAVR may be preferred over SAVR.展开更多
Hydraulic technology has the outstanding advantages of easy pressure compensation and high power density.It is an indispensable part of subsea equipment,such as deep-sea operations and submersible propulsion.There are...Hydraulic technology has the outstanding advantages of easy pressure compensation and high power density.It is an indispensable part of subsea equipment,such as deep-sea operations and submersible propulsion.There are few studies on electrohydraulic servo valves(EHSVs)in the deep sea.In this work,a novel electro-hydraulic servo rotary valve is designed,and its mathematical model is established.The analysis considers the variations in physical parameters such as temperature,ambient pressure,and oil viscosity resulting from changes in sea depth.This study focuses on the deformation of the rotary valve and the consequent alterations in leakage and friction torque.The findings indicate that at a depth of 12000 m,the fit clearance between the valve spool and the valve sleeve is 0.00413 mm,representing a 17%reduction compared with the clearance in a land environment.Then,the response of the rotary valve to depth is analyzed.The results indicate that the bandwidth of the rotary valve decreases with increasing depth.This study provides a reference for the use of the EHSV in the deep sea.展开更多
文摘Background The effective orifice area(EOA)is utilized to characterize the hemodynamic performance of the transcatheter heart valve(THV).However,there is no consensus on EOA measurement of self-expanding THV.We aimed to compare two echocardiographic methods for EOA measurement following transcatheter self-expanding aortic valve implantation.Methods EOA was calculated according to the continuity equation.Two methods were constructed.In Method 1 and Method 2,the left ventricular outflow tract diameter(LVOTd)was measured at the entry of the prosthesis(from trailing-to-leading edge)and proximal to the prosthetic valve leaflets(from trailing-toleading edge),respectively.The velocity-time integral(VTI)of the LVOT(VTILVOT)was recorded by pulsed-wave Doppler(PW)from apical windows.The region of the PW sampling should match that of the LVOTd measurement with precise localization.The mean transvalvular pressure gradient(MG)and VTI of THV was measured by Continuous wave Doppler.Results A total of 113 consecutive patients were recruited.The mean age was 77.2±5.5 years,and 72 patients(63.7%)were male.EOA1 with the use of Method 1 was larger than EOA2(1.56±0.39 cm2 vs.1.48±0.41 cm2,P=0.001).MG correlated better with the indexed EOA1(EOAI1)(r=-0.701,P<0.001)than EOAI2(r=-0.645,P<0.001).According to EOAI(EOAI≤0.65 cm2/m2,respectively),the proportion of sever prosthesis-patient mismatch with the use of EOA1 was lower than EOA2(12.4%vs.21.2%,P<0.05).Compared with EOA2,EOA1 had lower interobserver and intra-observer variability(intra:0.5%±17%vs.3.8%±22%,P<0.001;inter:1.0%±9%vs.3.5%±11%,P<0.001).Conclusions For transcatheter self-expanding valve EOA measurement,LVOTd should be measured in the entry of the prosthesis stent(from trailing-to-leading edge),and VTILVOT should match that of the LVOTd measurement with precise localization.
基金supported by the National Natural Science Foundation of China(No.52175067)the Zhejiang Key Research&Development Project(No.2021C01021)+1 种基金the Natural Science Foundation of Zhejiang Province(No.LY20E050016)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(CPSF)(No.GZC20241478)。
文摘A high-temperature and high-pressure valve is the key equipment of a wind tunnel system;it controls the generation of high-temperature and high-pressure gas.To reduce the adverse impact of high-temperature and high-pressure gas on the strength of the valve body,a cooling structure is set on the valve seat.This can significantly reduce the temperature of the valve body and valve seat.The effects of its structure on the cooling characteristics and stress of the valve seat are studied,and six main parameters that can completely describe the geometry of the cooling structure are proposed.The central composite design method is used to select sample points,and the multi-objective genetic algorithm(MOGA)method is used for optimal structural design.A modification method according to the main parameters for the valve seat is proposed.The results show that the cooling structure weakens the pressure-bearing capability of the valve seat.Among the six main parameters of the valve seat,the distance from the end face of the lower hole to the Z-axis and the distance from the axis of the lower hole to the origin of the coordinates have the most obvious effects on the average stress of the valve seat.An optimum design value is proposed.This work can provide a reference for the design of high-temperature and high-pressure valves.
文摘BACKGROUND The management of severe symptomatic aortic stenosis has been revolutionized by transcatheter aortic valve replacement(TAVR),offering a minimally invasive alternative to surgical aortic valve replacement(SAVR).However,the compara-tive safety and efficacy of these interventions remain subjects of ongoing investigation.AIM To compare the clinical outcomes and safety of TAVR vs SAVR in patients with severe symptomatic aortic stenosis.METHODS A systematic review and meta-analysis were conducted according to PRISMA guidelines.Randomized controlled trials(RCTs)comparing TAVR and SAVR were identified from databases including PubMed,Scopus,and Web of Science up to May 31,2024.Data were extracted on clinical outcomes,including mortality,procedural compli-cations,and post-procedure adverse events.Risk ratios(RRs)with 95%CIs were calculated using a random-effects model.RESULTS A total of 10 RCTs were included.TAVR demonstrated a significantly lower risk of acute kidney injury(RR:0.33;95%CI:0.25–0.44),major bleeding(RR:0.37;95%CI:0.30–0.46),and new-onset atrial fibrillation(RR:0.44;95%CI:0.34–0.57)compared to SAVR.However,TAVR was associated with higher risks of new permanent pacemaker implantation(RR:3.49;95%CI:2.77–4.39),major vascular complications(RR:2.47;95%CI:1.91–3.21),and paraval-vular leaks(RR:4.15;95%CI:3.14–5.48).Mortality at 30 days was comparable(RR:0.95;95%CI:0.78–1.15),but long-term mortality was slightly higher with TAVR in some analyses(RR:1.23;95%CI:1.01–1.49).Rates of stroke(RR:0.97;95%CI:0.81–1.17)and myocardial infarction(RR:0.91;95%CI:0.67–1.24)were similar between the groups.CONCLUSION TAVR offers a less invasive option with significant benefits in reducing acute kidney injury,major bleeding,and new-onset atrial fibrillation,making it particularly advantageous for high-risk surgical candidates.However,higher risks of permanent pacemaker implantation,vascular complications,and paravalvular leaks highlight the need for individualized patient selection and shared decision-making to optimize outcomes.
文摘Background There is scarce data about comparisons between geriatric assessment tools in patients with aortic stenosis(AS).We aimed to describe the geriatric profile of patients with AS undergoing transcatheter aortic valve implantation(TAVI)and to analyze the ability of different tools for predicting clinical outcomes in this context.Methods This was a single center retrospective registry including patients with AS undergoing TAVI and surviving to hospital discharge.The primary endpoint was all-cause mortality or need for urgent readmission one year after TAVI.Results A total of 377 patients were included(mean age of 80.4 years).Most patients were independent or mildly dependent,with an optimal cognitive status.The proportion of frailty ranged from 17.6%to 49.8%.A total of 20 patients(5.3%)died and 110/377 patients(29.2%)died or were readmitted during follow up.Overall,most components of the geriatric assessment showed an association with clinical outcomes.Disability for instrumental activities showed a significant association with mortality and a strong association with the rate of mortality or readmission.The association between frailty and clinical outcomes was higher for short physical performance battery(SPPB),essential frailty toolset(EFT)and the frailty index based on comprehensive geriatric assessment(IF-VIG)and lower for Fried criteria and FRAIL scale.Conclusions AS patients from this series presented a good physical performance,optimal cognitive status and a reasonably low prevalence of frailty.The best predictive ability was observed for disability for instrumental activities and frailty as measured by the EFT,SPPB and the IF-VIG.
基金the support from the National Natural Science Foundation of China(22272004,62272041)the Fundamental Research Funds for the Central Universities(YWF-22-L-1256)+1 种基金the National Key R&D Program of China(2023YFC3402600)the Beijing Institute of Technology Research Fund Program for Young Scholars(No.1870011182126)。
文摘The proliferation of wearable biodevices has boosted the development of soft,innovative,and multifunctional materials for human health monitoring.The integration of wearable sensors with intelligent systems is an overwhelming tendency,providing powerful tools for remote health monitoring and personal health management.Among many candidates,two-dimensional(2D)materials stand out due to several exotic mechanical,electrical,optical,and chemical properties that can be efficiently integrated into atomic-thin films.While previous reviews on 2D materials for biodevices primarily focus on conventional configurations and materials like graphene,the rapid development of new 2D materials with exotic properties has opened up novel applications,particularly in smart interaction and integrated functionalities.This review aims to consolidate recent progress,highlight the unique advantages of 2D materials,and guide future research by discussing existing challenges and opportunities in applying 2D materials for smart wearable biodevices.We begin with an in-depth analysis of the advantages,sensing mechanisms,and potential applications of 2D materials in wearable biodevice fabrication.Following this,we systematically discuss state-of-the-art biodevices based on 2D materials for monitoring various physiological signals within the human body.Special attention is given to showcasing the integration of multi-functionality in 2D smart devices,mainly including self-power supply,integrated diagnosis/treatment,and human–machine interaction.Finally,the review concludes with a concise summary of existing challenges and prospective solutions concerning the utilization of2D materials for advanced biodevices.
文摘Bicuspid aortic valve (BAV) is a common congenital heart valve disease, often accompanied by aortic valve stenosis or regurgitation, infective endocarditis, and aortic diseases such as aortic dilation and dissection. This article aims to review the definition, pathogenesis and genetic basis, classification methods, clinical features and current status of research and treatment and prognosis of BAV, and provide reference for the diagnosis and treatment of BAV. The content and structure of this article are as follows: The first part introduces the definition of BAV;The second part introduces the etiology and classification methods of BAV;The third part briefly describes the clinical manifestations and diagnosis of BAV;The fourth part discusses the treatment strategies and prognosis prediction of BAV;Finally, the article summarizes and looks forward to the future research directions.
文摘A functional interlayer based on two-dimensional(2D)porous modified vermiculite nanosheets(PVS)was obtained by acid-etching vermiculite nanosheets.The as-obtained 2D porous nanosheets exhibited a high specific surface area of 427 m^(2)·g^(-1)and rich surface active sites,which help restrain polysulfides(LiPSs)through good physi-cal and chemical adsorption,while simultaneously accelerating the nucleation and dissolution kinetics of Li_(2)S,effec-tively suppressing the shuttle effect.The assembled lithium-sulfur batteries(LSBs)employing the PVS-based inter-layer delivered a high initial discharge capacity of 1386 mAh·g^(-1)at 0.1C(167.5 mAh·g^(-1)),long-term cycling stabil-ity,and good rate property.
基金supported by the Shihezi University High-Level Talents Research Startup Project(Project No.RCZK202521)the National Natural Science Foundation of China(Grant Nos.12271066,11871121,12171405)+1 种基金the Chongqing Natural Science Foundation Joint Fund for Innovation and Development Project(Project No.CSTB2024NSCQLZX0085)the Chongqing Normal University Foundation(Grant No.23XLB018).
文摘This paper investigates ruin,capital injection,and dividends for a two-dimensional risk model.The model posits that surplus levels of insurance companies are governed by a perturbed composite Poisson risk model.This model introduces a dependence between the two surplus levels,present in both the associated perturbations and the claims resulting from common shocks.Critical levels of capital injection and dividends are established for each of the two risks.The surplus levels are observed discretely at fixed intervals,guiding decisions on capital injection,dividends,and ruin at these junctures.This study employs a two-dimensional Fourier cosine series expansion method to approximate the finite time expected discounted operating cost until ruin.The ensuing approximation error is also quantified.The validity and accuracy of the method are corroborated through numerical examples.Furthermore,the research delves into the optimal capital allocation problem.
文摘Pediatric heart valve replacement(PHVR)remains a challenging procedure due to the uniqueanatomical and physiological characteristics of children,including growth and development,as well asthe long-term need for durable valve function.This review provides an overview of both surgical andtranscatheter options for aortic,mitral,pulmonary,and tricuspid valve replacements in pediatric patients,highlighting the indications,outcomes,and advancements in technology and technique.Surgical valvereplacement traditionally involves the implantation of biological or mechanical prosthetic valves,withbiologicalvalves beingpreferred in children to reduce the need for lifelong anticoagulation therapy.However,the limitation ofbiological prostheses,nanely their inability to grow with the child,necessitates the frequentneed for reoperations.Recent innovations in valve engineering,such as the development of tissue engineeredand expandable valves,aim to address these issues.Transcatheter valve replacement(TVR)has emergedas a promising alternative,particularly for patients with complex anatomy or those who are high-risk fortraditional surgery.While the use of transcatheter devices in children remains limited due to the smallervascular size and limited long-termn data,several studies have demonstrated the feasibility and safety ofthe procedure in certain patient populations.Despite these advancements,challenges related to valvesize,durability,and the need for individualized treatment planning persist.The future of pediatric heartvalve replacemnent will likely involve a multidisciplinary approach combining surgical,transcatheter,andregenerative medicine strategies,aimed at optimizing outcomes,reducing the need for reinterventions,andimproving long-term quality of life for pediatric patients with valvularheart disease.This article discussesall options availab le for patients with valvular dysfunction,making it easy for parents/patients to go to as areference source of information.
文摘Objective: This study aims to investigate the drainage effect and clinical outcomes of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery, comparing the differences in postoperative pain, hospital stay, and other factors between the negative pressure group and the control group. Methods: This study is a prospective controlled trial that selected patients undergoing two-port thoracoscopic valve surgery at a certain hospital from January 2019 to December 2024. Patients were randomly assigned to the control group and the negative pressure group using a random number table method. The control group consisted of 30 patients (20 males, 10 females, mean age 42.03 ± 12.89 years), and the negative pressure group consisted of 35 patients (26 males, 9 females, mean age 41.84 ± 11.83 years). The control group received traditional chest drainage, while the negative pressure group received negative pressure chest drainage. Postoperative pain scores, hospital stay, drainage time, number of tube blockages, and incidences of pneumothorax or subcutaneous emphysema were recorded and statistically analyzed. Results: The negative pressure group had a significantly shorter postoperative drainage time compared to the control group (49.09 ± 11.99 hours vs. 79.10 ± 7.32 hours, P < 0.001). The postoperative pain score was lower in the negative pressure group (4.49 ± 1.27 vs. 7.03 ± 0.85, P < 0.001), and the hospital stay was significantly shorter (9.83 ± 1.69 days vs. 14.73 ± 2.32 days, P < 0.001). The incidence of pneumothorax or subcutaneous emphysema was significantly lower in the negative pressure group than in the control group (14.29% vs. 56.67%, P = 0.0003). Conclusion: The application of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery can effectively reduce postoperative pain, shorten hospital stay, and lower the incidence of tube blockage and pneumothorax, demonstrating good clinical outcomes.
基金supported by Beijing Natural Science Foundation(Nos.2232037 and 2242035)the National Natural Science Foundation of China(Nos.22005012,22105012 and 51803183)+1 种基金Chunhui Plan Cooperative Project of Ministry of Education(No.202201298)the China Postdoctoral Science Foundation Funded Project(No.2023M733520).
文摘Lithium-sulfur(Li-S)batteries with high energy density and capacity have garnered significant research attention among various energy storage devices.However,the shuttle effect of polysulfides(LiPSs)remains a major challenge for their practical application.The design of battery separators has become a key aspect in addressing the challenge.MXenes,a promising two-dimensional(2D)material,offer exceptional conductivity,large surface area,high mechanical strength,and active sites for surface reactions.When assembled into layered films,MXenes form highly tunable two-dimensional channels ranging from a few angstroms to over 1 nm.These nanoconfined channels are instrumental in facilitating lithium-ion transport while effectively impeding the shuttle effect of LiPSs,which are essential for improving the specific capacity and cyclic stability of Li-S batteries.Substantial progress has been made in developing MXenes-based separators for Li-S batteries,yet there remains a research gap in summarizing advancements from the perspective of interlayer engineering.This entails maintaining the 2D nanochannels of layered MXenes-based separators while modulating the physicochemical environment within the MXenes interlayers through targeted modifications.This review highlights advancements in in situ modification of MXenes and their integration with 0D,1D,and 2D materials to construct laminated nanocomposite separators for Li-S batteries.The future development directions of MXenes-based materials in Li-S energy storage devices are also outlined,to drive further advancements in MXenes for Li-S battery separators.
基金funded by a IBYE23_0002 grant supported by Instituto de investigación biom-édica de Salamanca IBSAL,Castilla y León (Spain) and by a GRS 2860/A1/2023 by Gerencia Regional de Salud o f Castilla y León (Spain)。
文摘Background Transcatheter Aortic Valve Implantation(TAVI)has changed the treatment paradigm of the aortic stenosis(AS).It has become the treatment of choice in patients with symptomatic AS and surgical high risk,and a valid alternative to surgical aortic valve replacement in patients with low and medium surgical risk.Despite numerous evidence on clinical results,indications and benefits,only a few studies analyse it from patient's perspective and the impact of TAVI on them.The objective of this study is to evaluate the experience of patients undergoing TAVI.Methods Cross-sectional,descriptive observational study in two Spanish hospitals,with a establish Nurse TAVI program,with100 patients undergoing TAVI.A specific questionnaire was designed(VALVEX questionnaire)and a pilot study was conducted by a multidisciplinary team of doctors,nurses and patients.The questionnaire was given to patients at 30 days after TAVI procedure during the follow up at the TAVI nurse clinic.Results The study demonstrated a mean satisfaction of 9 for the TAVI program,with 96%of patients that would recommend TAVI to other patients.Patients scored a high satisfaction on the information received prior to the procedure.During the procedure and admission,the satisfaction was high in relation to the care received.During the follow up,satisfaction was high in relation to the role of the TAVI nurse,for the information and continuation of care during the procedure,in reducing anxiety,organising their admission and understanding the process.However,questions with less scores were related to hospital catering,delay between diagnosed and treatment,and patient decision-making process.Conclusion The evaluation of patient experience allows us to improve the information given to the patient during their TAVI process and it can also allow patients to be more relax,aware and prepared for the procedure.Continuous follow up enables monitoring of patient recovery and helps to discuss any doubts improving patient's satisfaction.The use of PREMs and PROMs associated to TAVI pathway combined with an active participation of the patient on the design of the questionnaire is essential for keeping the patient in the centre of the TAVI pathway.
文摘BACKGROUND The Perceval Sorin S(perceval valve)is a sutureless bioprosthetic designed for use in a high-risk cohort who may not be suitable for transcatheter aortic valve implantation or a conventional surgical aortic valve replacement(AVR).AIM To compare five-year post-operative outcomes in a cohort undergoing isolated AVR with the perceval valve to a contemporary cohort undergoing surgical AVR with a sutured bioprosthesis.METHODS This study was a retrospective,cohort study at a single tertiary unit.Between 2017 and 2023,982 suitable patients were identified.174 Perceval valve replacements were matched to 174 sutured valve replacements.Cohort characteristics,intra-operative details,and post-operative outcomes were compared between the two groups.RESULTS Time under the aortic cross-clamp(P<0.001),time on the cardiopulmonary bypass(P<0.001)and total operative time(P<0.001)were significantly reduced in the Perceval group.Patients in the Perceval valve group were at a lower risk of postoperative pneumonia[odds ratio(OR)=0.53(0.29-0.94)]and atrial fibrillation[OR=0.58(0.36-0.93)].After propensity-matching,all-cause mortality did not significantly differ between the two groups in the five-year follow-up period.Larger valve sizes conferred an increased risk of mortality(P=0.020).CONCLUSION Sutureless surgical AVR(SAVR)is a safe and efficient alternative to SAVR with a sutured bioprosthesis,and may confer a reduced risk of post-operative atrial fibrillation.Clinician tendency towards‘oversizing’sutureless aortic valves translates into adverse clinical outcomes.Less time on the cardiopulmonary bypass circuit allows for the treatment of otherwise high-risk patients.
基金funded by internal grants from the Ward Family Heart Center.
文摘A bicuspid aortic valve,from autologous tissue,with growth potential can be constructed using the simple,and reproducible telescoping arterial trunk technique.
文摘Transcatheter aortic valve replacement(TAVR)has emerged as an established standard of care for patients with severe aortic stenosis(AS),irrespective of their surgical risk.However,despite the continuous advancements over last two decades,there are still significant challenges in field in terms of appropriate selection of patients as well as the valves.While there is no doubt that TAVR has now become the leading mode of treatment for severe AS patients,surgical aortic valve replacement(SAVR)still holds its value for the selective group of patients who are not ideal candidate for the minimally invasive procedure:TAVR.The dilemma is palpable in the clinical field that warrants best approach focusing on the lifetime management of these patients.In the recent metanalysis by Moradi et al,the authors provide a comprehensive insight into TAVR vs SAVR in terms of mortality,procedural complications,and post-procedure adverse events.In this editorial,we shed light on comparative analysis of both modalities to establish a middle ground.
文摘BACKGROUND Aortic root dilation,linked to bicuspid aortic valve(BAV)or tricuspid aortic valve(TAV),risks aneurysm and dissection.Valve-sparing aortic root replacement(VSARR)preserves native valves,avoiding prosthetic valve complications.Longterm VSARR durability,especially in BAV patients,is debated.We hypothesize that VSARR outcomes differ between BAV and TAV patients in short-term and long-term settings.AIM To investigate short-term and long-term outcomes of VSARR in BAV vs TAV patients.METHODS This Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant meta-analysis included observational studies comparing VSARR in adult BAV vs TAV patients.PubMed,ScienceDirect,and EMBASE were searched from inception to June 2025.Outcomes included mortality,reintervention,and procedural times.Pooled relative risk(RR)and mean differences(MD)with 95%CI were calculated.Risk of bias was assessed using Risk of Bias in Non-randomized Studies of Interventions;evidence certainty via GRADE.RESULTS Thirteen observational studies involving 1419 BAV and 2349 TAV patients were included.In-hospital mortality(RR=0.34,95%CI:0.10-1.14,P=0.08)and reoperation(RR=1.04,95%CI:0.64-1.69,P=0.87)showed no significant differences.All-cause mortality risk was significantly lower in BAV patients(RR=0.34,95%CI:0.13-0.86,P=0.02).Overall reintervention risk was significantly greater in BAV patients(RR=2.64,95%CI:1.96-3.55,P<0.00001).Aortic cross-clamp(MD=3.35 minutes,95%CI:-5.06 to 11.76,P=0.43)and cardiopulmonary bypass times(MD=3.96 minutes,95%CI:-10.26 to 18.18,P=0.59)showed no significant differences but substantial heterogeneity.The certainty of evidence was moderate for reintervention,low for mortality risk and in-hospital reoperation,and very low for procedural times.CONCLUSION VSARR demonstrates comparable short-term safety between BAV and TAV patients.However,BAV patients face a significantly higher long-term reintervention risk,highlighting the need for tailored strategies and further research.
基金Supported by National Natural Science Foundation of China(Grant Nos.51975524,52375067)Zhejiang Provincial Natural Science Foundation of China(Grant No.Y23E050014).
文摘Magnetization convenience is crucial consideration for design of valve magnetic actuators.The existing repulsive-magnetic-coupling of 2D maglev valve is not oriented to the integral-magnetization-processes,resulting in the high assembly cost.This paper presents a novel tractive-magnetic-coupling(TMC)and its application on a 2D electro-hydraulic proportional flow valve(2D-EHPFV),whose configuration not only fulfill the requirements of 2D valve,but also oriented to integral-magnetization-process.To investigate the output torque of TMC,a detailed analytical model considering leakage flux,edge effect and tooth magnetic saturation is formulated based on the equivalent magnetic circuit method.To facilitate the magnetic saturation calculation,a special magnetic permeability database is established for tooth region of TMC using Ansoft/Maxwell software.Prototype of TMC is machined and an exclusive experimental platform is built.Torque-displacement characteristics under different working airgap and tooth number are measured.The experimental results are in good agreement with the analytical results,which verifies the correctness of the analytical model.Then the TMC is integrated into the 2D-EHPFV by replacing the repulsive-magnetic-coupling.Prototype of 2D-EHPFV is designed and manufactured to test the no-load flow characteristics,load flow characteristics,leakage characteristics,frequency characteristics and step response.Under working pressure of 15 MPa,the maximum no-load flow rate is 82.2 L/min with the hysteresis of 2.6%,and the amplitude and phase frequency width is 21.6 Hz,and 28.9 Hz.The detailed experimental results show that TMC can be applied to 2D valves to form 2D-EHPFV,which can reduce hysteresis and cost,and improve response speed.
文摘Aortic stenosis(AS)is the most common valvular heart disease,with a prevalence of over 4%among octogenarians.[1]The prevalence of autopsy-confirmed wild-type transthyretin cardiac amyloidosis(ATTRwt-CA)increases with age,accounting for 25%of patients aged 85 years and older in Europe and 12%of patients older than 80 years in Japan.[2,3]Recent studies have reported that ATTRwt-CA coexists in 11%-16%of older patients with AS undergoing transcatheter aortic valve replacement(TAVR).[1,4,5]In a metaanalysis by Ho et al.,[6]the prevalence rates of cardiac amyloidosis,predominantly ATTRwt-CA,in patients with AS and those referred for TAVR or surgical aortic valve replacement(SAVR)were 14.4%and 15.2%,respectively.Conversely,the prevalence of AS in patients with cardiac amyloidosis is 8.7%.Owing to the high surgical risk in patients with both AS and ATTRwt-CA,TAVR may be preferred over SAVR.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFC2805703)the Major Training Program of University Research and Innovation Platform of Gansu Provincial Department of Education(Grant No.2024CXPT-09).
文摘Hydraulic technology has the outstanding advantages of easy pressure compensation and high power density.It is an indispensable part of subsea equipment,such as deep-sea operations and submersible propulsion.There are few studies on electrohydraulic servo valves(EHSVs)in the deep sea.In this work,a novel electro-hydraulic servo rotary valve is designed,and its mathematical model is established.The analysis considers the variations in physical parameters such as temperature,ambient pressure,and oil viscosity resulting from changes in sea depth.This study focuses on the deformation of the rotary valve and the consequent alterations in leakage and friction torque.The findings indicate that at a depth of 12000 m,the fit clearance between the valve spool and the valve sleeve is 0.00413 mm,representing a 17%reduction compared with the clearance in a land environment.Then,the response of the rotary valve to depth is analyzed.The results indicate that the bandwidth of the rotary valve decreases with increasing depth.This study provides a reference for the use of the EHSV in the deep sea.
