Since the advent of transcatheter aortic valve replacement(TAVR)in 2002,it has now become the default interventional strategy for symptomatic patients presenting with severe aortic stenosis,particularly in intermediat...Since the advent of transcatheter aortic valve replacement(TAVR)in 2002,it has now become the default interventional strategy for symptomatic patients presenting with severe aortic stenosis,particularly in intermediate to highsurgical risk patients.In 2019,the United States Food and Drug Administration approved TAVR in low-risk patients based on two randomized trials.However,these breakthrough trials excluded patients with certain unfavorable anatomies and odd profiles.While currently there is no randomized study of TAVR in young patients,it may be preferred by the young population given the benefits of early discharge,shorter hospital stay,and expedite recovery.Nonetheless,it is important to ruminate various factors including lifetime expectancy,risk of pacemaker implantation,and the need for future valve or coronary interventions in young cohorts before considering TAVR in these patients.Furthermore,the data on long-term durability(>10 years)of TAVR is still unknown given most of the procedures were initially performed in the high or prohibitive surgical risk population.Thus,this editorial aims to highlight the importance of considering an individualized approach in young patients with consideration of various factors including lifetime expectancy while choosing TAVR against surgical aortic valve replacement.展开更多
The liquid-cooled battery energy sto rage system(LCBESS) has gained significant attention due to its superior thermal management capacity.However,liquid-cooled battery pack(LCBP) usually has a high sealing level above...The liquid-cooled battery energy sto rage system(LCBESS) has gained significant attention due to its superior thermal management capacity.However,liquid-cooled battery pack(LCBP) usually has a high sealing level above IP65,which can trap flammable and explosive gases from battery thermal runaway and cause explosions.This poses serious safety risks and challenges for LCBESS.In this study,we tested overcharged battery inside a commercial LCBP and found that the conventionally mechanical pressure relief valve(PRV) on the LCBP had a delayed response and low-pressure relief efficiency.A realistic 20-foot model of an energy storage cabin was constructed using the Flacs finite element simulation software.Comparative studies were conducted to evaluate the pressure relief efficiency and the influence on neighboring battery packs in case of internal explosions,considering different sizes and installation positions of the PRV.Here,a newly developed electric-controlled PRV integrated with battery fault detection is introduced,capable of starting within 50 ms of the battery safety valve opening.Furthermore,the PRV was integrated with the battery management system and changed the battery charging and discharging strategy after the PRV was opened.Experimental tests confirmed the efficacy of this method in preventing explosions.This paper addresses the safety concerns associated with LCBPs and proposes an effective solution for explosion relief.展开更多
The safety valve is an important component to ensure the safe operation of lithium-ion batteries(LIBs).However,the effect of safety valve type on the thermal runaway(TR)and gas venting behavior of LIBs,as well as the ...The safety valve is an important component to ensure the safe operation of lithium-ion batteries(LIBs).However,the effect of safety valve type on the thermal runaway(TR)and gas venting behavior of LIBs,as well as the TR hazard severity of LIBs,are not known.In this paper,the TR and gas venting behavior of three 100 A h lithium iron phosphate(LFP)batteries with different safety valves are investigated under overheating.Compared to previous studies,the main contribution of this work is in studying and evaluating the effect of gas venting behavior and TR hazard severity of LFP batteries with three safety valve types.Two significant results are obtained:(Ⅰ)the safety valve type dominates over gas venting pressure of battery during safety venting,the maximum gas venting pressure of LFP batteries with a round safety valve is 3320 Pa,which is one order of magnitude higher than other batteries with oval or cavity safety valve;(Ⅱ)the LFP battery with oval safety valve has the lowest TR hazard as shown by the TR hazard assessment model based on gray-fuzzy analytic hierarchy process.This study reveals the effect of safety valve type on TR and gas venting,providing a clear direction for the safety valve design.展开更多
This study explores the implementation of computed tomography(CT)reconstruction and simulation techniques for patient-specific valves,aiming to dissect the mechanical attributes of calcified valves within transcathete...This study explores the implementation of computed tomography(CT)reconstruction and simulation techniques for patient-specific valves,aiming to dissect the mechanical attributes of calcified valves within transcatheter heart valve replacement(TAVR)procedures.In order to facilitate this exploration,it derives pertinent formulas for 3D multi-material isogeometric hyperelastic analysis based on Hounsfield unit(HU)values,thereby unlocking foundational capabilities for isogeometric analysis in calcified aortic valves.A series of uniaxial and biaxial tensile tests is executed to obtain an accurate constitutive model for calcified active valves.To mitigate discretization errors,methodologies for reconstructing volumetric parametric models,integrating both geometric and material attributes,are introduced.Applying these analytical formulas,constitutive models,and precise analytical models to isogeometric analyses of calcified valves,the research ascertains their close alignment with experimental results through the close fit in displacement-stress curves,compellingly validating the accuracy and reliability of the method.This study presents a step-by-step approach to analyzing themechanical characteristics of patient-specific valves obtained fromCT images,holding significant clinical implications and assisting in the selection of treatment strategies and surgical intervention approaches in TAVR procedures.展开更多
Transcatheter aortic valve replacement(TAVR)has emerged as a formidable treatment option for severe symptomatic aortic stenosis ahead of surgical aortic valve replacement.The encouraging results from large randomized ...Transcatheter aortic valve replacement(TAVR)has emerged as a formidable treatment option for severe symptomatic aortic stenosis ahead of surgical aortic valve replacement.The encouraging results from large randomized controlled trials has resulted in an exponential rise in the use of TAVR even in the low-risk patients.However,this is not without challenges.Need for permanent pacemaker(PPM)post-TAVR remains the most frequent and clinically relevant challenge.Naturally,identifying risk factors which predispose an individual to develop high grade conduction block post-TAVR is important.Various demographic factors,electrocardiographic features,anatomic factors and procedural characteristics have all been linked to the development of advanced conduction block and need for PPM following TAVR.Amongst these electrophysiological variables,most notably a prolonged QRS>120 ms regardless of the type of conduction block seems to be one of the strongest predictors on logistic regression models.The index study by Nwaedozie et al highlights that patients requiring PPM post-TAVR had higher odds of having a baseline QRS>120 ms and were more likely to be having diabetes mellitus that those who did not require PPM.展开更多
In this editorial,we comprehensively summarized the preoperative risk factors of early permanent pacemaker implantation after transcatheter aortic valve replacement(TAVR)among patients with severe aortic stenosis from...In this editorial,we comprehensively summarized the preoperative risk factors of early permanent pacemaker implantation after transcatheter aortic valve replacement(TAVR)among patients with severe aortic stenosis from several renowned clinical studies and focused on the primary prevention of managing the modifiable factors,e.g.,paroxysmal atrial fibrillation before the TAVR.展开更多
Pacemaker post-transcatheter aortic valve replacement is related to multifactorial risk.Nwaedozie et al brought to the body of evidence electrocardiogram and clinical findings.However,procedural characteristics have a...Pacemaker post-transcatheter aortic valve replacement is related to multifactorial risk.Nwaedozie et al brought to the body of evidence electrocardiogram and clinical findings.However,procedural characteristics have at least as much impact on the final need for a permanent pacemaker and potentially on the pacing rate.In this regard,long-term follow-up and understanding of the impact of long-term stimulation is of utmost importance.展开更多
Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resista...Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resistance and low-temperature resistance,respectively.In order to develop type 120 emergency valverubber diaphragms with long-life and high-performance,low-temperatureresistant CR and NR were processed.Design/methodology/approach–The physical properties of the low-temperature-resistant CR and NRwere tested by low-temperature stretching,dynamic mechanical analysis,differential scanning calorimetryand thermogravimetric analysis.Single-valve and single-vehicle tests of type 120 emergency valves werecarried out for emergency diaphragms consisting of NR and CR.Findings–The low-temperature-resistant CR and NR exhibited excellent physical properties.The elasticityand low-temperature resistance of NR were superior to those of CR,whereas the mechanical properties of thetwo rubbers were similar in the temperature range of 0℃–150℃.The NR and CR emergency diaphragms metthe requirements of the single-valve test.In the low-temperature single-vehicle test,only the low-temperaturesensitivity test of the NR emergency diaphragm met the requirements.Originality/value–The innovation of this study is that it provides valuable data and experience for futuredevelopment of type 120 valve rubber diaphragms.展开更多
Aortic valve calcification disease (CAVD) is the most prevalent degenerative valve disease in humans, leading to significant morbidity and mortality. Despite its common occurrence, our understanding of the underlying ...Aortic valve calcification disease (CAVD) is the most prevalent degenerative valve disease in humans, leading to significant morbidity and mortality. Despite its common occurrence, our understanding of the underlying mechanisms remains incomplete, and available treatment options are limited and risky. A more comprehensive understanding of the biology of CAVD is essential to identify new therapeutic strategies. Animal models have played a crucial role in advancing our knowledge of CAVD and exploring potential treatments. However, these models have inherent limitations as they cannot fully replicate the complex physiological mechanisms of human CAVD. In this review, we examine various CAVD models ranging from pigs to mice, highlighting the unique characteristics of each model to enhance our understanding of CAVD. While these models offer valuable insights, they also have limitations and shortcomings. We propose that the guide wire model shows promise for future CAVD research, and streamlining the methodology could enhance our understanding and expand the research scope in this field.展开更多
Background: Tuberculous endocarditis is a rare but serious complication of heart valve replacement surgery. We report the case of a 24-year-old patient, who presented with tuberculous endocarditis after mechanical mit...Background: Tuberculous endocarditis is a rare but serious complication of heart valve replacement surgery. We report the case of a 24-year-old patient, who presented with tuberculous endocarditis after mechanical mitral valve replacement, with a favorable clinical course following anti-tuberculosis treatment. Case Presentation: We report a 24-year-old male patient, admitted to the cardiac surgery department of the Fann Hospital (Dakar, Senegal), for the management of severe mixed (rheumatic and endocarditic) mitral insufficiency with associated tricuspid insufficiency. He had a history of recurrent angina and polyarthralgia in childhood, was hospitalized several times for refractory global cardiac decompensation, and for a suspected infective endocarditis a month before his admission. On admission, the clinical examination revealed signs suggestive of mitral and tricuspid insufficiency. Transthoracic echocardiography revealed severe post-endocarditic mitral insufficiency with A3 amputation, highly mobile 15 mm vegetations on the free edge of the large valve, moderate tricuspid insufficiency, and severe pulmonary artery hypertension. Mechanical mitral valve replacement and tricuspid valve annuloplasty using autologous pericardial strip were performed via median sternotomy. After ten days, the patient presented with global cardiac decompensation associated with a clinico-biological infectious syndrome, and tans-oesophageal echography revealed an abscess at the sinotubular junction, communicating with the aorta. A thoraco-abdomino-pelvic CT scan was done, which revealed a bilateral alveolar-interstitial syndrome with mediastinal lymphadenopathy. Anti-tuberculosis treatment with RHZE was initiated for 06 months. The clinical course was favorable. Conclusion: Tuberculous endocarditis in prostheses is a serious complication of heart valve replacement surgery, which may evolve favorably under medical treatment.展开更多
The mathematical model of the solenoid valve under varying temperatures is constructed to investigate its performance and enhance heat dissipation balance.The relationship between temperature and electromagnetic force...The mathematical model of the solenoid valve under varying temperatures is constructed to investigate its performance and enhance heat dissipation balance.The relationship between temperature and electromagnetic force is determined.Electrothermal coupling simulation using COMSOL is conducted,optimizing the outer diameter and length structure parameters of the coil.It is established that the heat dissipation of the coil is influenced by its outer diameter.Subsequently,based on optimized coil structure parameters,an orthogonal experimental design method combined with Ansys Maxwell is employed for simulation solution analysis to study the impact of structural parameters such as length,position,front and rear angles of the magnetic barrier ring in the iron core,armature length,and through-hole size on electromagnetic force.Optimal structural parameters are identified.Results indicate a decrease in steady-state electromagnet temperature by 3-4℃,an increase in the initial electromagnetic force by 32.63%,and a rise in the maximum electromagnetic force by 27.10%.展开更多
Introduction: Treatments for cardiovascular diseases have increasingly evolved with the tendency to offer minimally invasive or transcatheter procedures instead of conventional sternotomy surgery. In this context, we ...Introduction: Treatments for cardiovascular diseases have increasingly evolved with the tendency to offer minimally invasive or transcatheter procedures instead of conventional sternotomy surgery. In this context, we highlight minimally invasive mitral valve surgery (MIMVS), which has been shown to be an increasingly solid option with some superior results when compared to the conventional technique: better pain control, shorter hospital stays, shorter recovery time, shorter readmission rate in the first postoperative year, better aesthetic results, and lower overall cost. Aim: This study aims to evaluate the stages of MIMVS, by primary mitral valve consultation, in our service and compare these results with data from the literature. Methods: All electronic medical records of patients who underwent MIMVS for primary mitral valve injury in the Encore Hospital from January 2020 to February 2023 were analyzed. Tabulation and statistical analysis were performed using the Microsoft Excel<sup>®</sup> program. Quantitative variables were presented as means, standard deviations. Results: 46 patients were enrolled in our study (Age: 59.1 ± 12.4 years old;60.8% Female, BMI: 26 ± 4.4 Kg/m<sup>2</sup>, Low risk STS score: 82.6%). The observed 30-day mortality was 2.1%, plastic rate of 23.9%, blood transfusion rate of 41.3%, length of stay in an intensive care bed (ICB) of 3.3 ± 3.3 days and hospital stay of 6.4 ± 5.1 days. Conclusions: We noticed that the MIMVS results carried out in our service agree with data from national and international literature with approximately 1.3 days more hospitalization in ICB.展开更多
BACKGROUND Conduction and rhythm abnormalities requiring permanent pacemakers(PPM)are short-term complications following transcatheter aortic valve replacement(TAVR),and their clinical outcomes remain conflicting.Pote...BACKGROUND Conduction and rhythm abnormalities requiring permanent pacemakers(PPM)are short-term complications following transcatheter aortic valve replacement(TAVR),and their clinical outcomes remain conflicting.Potential novel predictors of post-TAVR PPM,like QRS duration,QTc prolongation,and supraventricular arrhythmias,have been poorly studied.AIM To evaluate the effects of baseline nonspecific interventricular conduction delay and supraventricular arrhythmia on post-TAVR PPM requirement and determine the impact of PPM implantation on clinical outcomes.METHODS RESULTS Out of the 357 patients that met inclusion criteria,the mean age was 80 years,188(52.7%)were male,and 57(16%)had a PPM implantation.Baseline demographics,valve type,and cardiovascular risk factors were similar except for type II diabetes mellitus(DM),which was more prevalent in the PPM cohort(59.6%vs 40.7%;P=0.009).The PPM cohort had a significantly higher rate of pre-procedure right bundle branch block,prolonged QRS>120 ms,prolonged QTc>470 ms,and supraventricular arrhythmias.There was a consistently significant increase in the odds ratio(OR)of PPM implantation for every 20 ms increase in the QRS duration above 100 ms:QRS 101-120[OR:2.44;confidence intervals(CI):1.14-5.25;P=0.022],QRS 121-140(OR:3.25;CI:1.32-7.98;P=0.010),QRS 141-160(OR:6.98;CI:3.10-15.61;P<0.001).After model adjustment for baseline risk factors,the OR remained significant for type II DM(aOR:2.16;CI:1.18-3.94;P=0.012),QRS>120(aOR:2.18;CI:1.02-4.66;P=0.045)and marginally significant for supraventricular arrhythmias(aOR:1.82;CI:0.97-3.42;P=0.062).The PPM cohort had a higher adjusted OR of heart failure(HF)hospitalization(aOR:2.2;CI:1.1-4.3;P=0.022)and nonfatal myocardial infarction(MI)(aOR:3.9;CI:1.1-14;P=0.031)without any difference in mortality(aOR:1.1;CI:0.5-2.7;P=0.796)at one year.CONCLUSION Pre-TAVR type II DM and QRS duration>120,regardless of the presence of bundle branch blocks,are predictors of post-TAVR PPM.At 1-year post-TAVR,patients with PPM have higher odds of HF hospitalization and MI.展开更多
The most common congenital heart defect is the bicuspid aortic valve (BAV) occurring with fusion of one of the three-valve commissures. A rarer valvular phenomenon is the unicuspid aortic valve (UAV) which has an esti...The most common congenital heart defect is the bicuspid aortic valve (BAV) occurring with fusion of one of the three-valve commissures. A rarer valvular phenomenon is the unicuspid aortic valve (UAV) which has an estimated prevalence of 0.02% in the adult population. Two morphologic subtypes of UAV exist: the earlier presenting, acommissural UAV and the later appearing unicommissural. To better characterize and manage patients with UAVs, a systematic review of this rare phenomenon was performed. The objective of our study was to conduct a systematic review of adequate case studies involving UAV patients to describe patient characteristics, clinical presentation, management, and common sequela featured there within. The mean age of presentation in this review was 35.6 years. When diagnosing UAV, TEE was the most utilized diagnostic modality (65%) followed by intraoperative diagnosis (17%) discovered with valve repair or incidentally during another procedure. TTE was utilized to diagnose only 7% of the cases reviewed likely owing to the difficulty and inaccuracies in identifying UAV with this method that were previously established by multiple series. Interventional options for UAV are balloon versus surgical valvotomy, aortic valve replacement, Ross procedure and aortic root replacement. They are performed on an individual basis and all cases ultimately require aortic valve replacement (AVR) or Ross procedure (to avoid anticoagulation). Aortic root replacement is additionally required if aortic root/ascending aorta diameter exceeds 4.5 cm. In this review, Aortic aneurysm (16%) cases resulted in surgical interventions. There may be a need to implant permanent pacemaker (in 3% - 8%) during AVR when calcified UAV has calcification extending into interventricular septum.展开更多
Electro-hydraulic proportional valve is the core control valve in many hydraulic systems used in agricultural and engineering machinery.To address the problem related to the large throttling losses and poor stability ...Electro-hydraulic proportional valve is the core control valve in many hydraulic systems used in agricultural and engineering machinery.To address the problem related to the large throttling losses and poor stability typically associated with these valves,here,the beneficial effects of a triangular groove structure on the related hydraulic response are studied.A mathematical model of the pressure compensation system based on the power-bond graph method is introduced,and the AMESim software is used to simulate its response.The results show that the triangular groove structure increases the jet angle and effectively compensates for the hydrodynamic force.The steady-state differential pressure at the valve port of the new pressure compensation structure was 0.65 MPa.Furthermore,experimental results show that the pressure difference at the main valve port is 0.73 MPa,and that the response time is less than 0.2 s.It is concluded that the new compensation structure has good pressure compensation response characteristics.展开更多
Background:The Venus-P valve was the first self-expanding valve used world-wide for transcatheter pulmonary valve replacement(TPVR)in patients with severe pulmonary regurgitation(PR).We intended to report the extended...Background:The Venus-P valve was the first self-expanding valve used world-wide for transcatheter pulmonary valve replacement(TPVR)in patients with severe pulmonary regurgitation(PR).We intended to report the extended follow-up results from the prospective trial(No.NCT02590679).Methods:A total of 38 patients with severe PR(mean age 24.2±13.2)were included.Follow-up data were obtained after implanted at 1,6,and 12 months and yearly after.The frame geometry was assessed on post-implant computer tomography(CT)scanning by calculating the non-circularity[circularity ratio(minimum diameter/maximum diameter)<0.9]and under-expansion[expansion ratio(derived external valve area/nominal external valve area)<0.9).Adverse events(all-cause mortality,reintervention,valve dysfunction,stent fracture and endocarditis)were recorded.Results:All valves were implanted successfully with normal function at discharge.Geometric CT analysis showed underexpanded valve was detected in 22 patients(63%)and non-circular valve was seen in 16 patients(46%).During a median follow-up of 4.8 years(range 0.3-8.1),there were 1 death and 1 surgical explant,both resulting from endocarditis.Five-year freedom from valve dysfunction and stent fracture were 84.8%(95%CI 74.8-94.7)and 83.5%(95%CI 73.8-93.2).Endocarditis occurred in 3 patients at a median time of 7 months.Stent fracture was more common in patients with non-circularity stents.Conclusion:TPVR using Venus-P valve is associated with favorable outcomes at 5 years.Non-circular shapes in the valve level may have a higher risk of stent fracture.展开更多
Background: Isolated tricuspid valve disease remains a controversial indication for surgical intervention. Many patients referred for surgery already have a poor clinical condition and an advanced New York Heart Assoc...Background: Isolated tricuspid valve disease remains a controversial indication for surgical intervention. Many patients referred for surgery already have a poor clinical condition and an advanced New York Heart Association functional class. There is no consensus on the optimal surgical technique for this condition, including on whether to perform the procedure on a beating or an arrested heart and whether to perform valve repair or replacement. Methods: We analyzed four case series between 2015 and 2022 in which patients with secondary tricuspid regurgitation (TR) underwent valve repair on a beating heart and right atrial plication for a dilated right atrium. The TRI-SCORE was calculated for each patient. Results: All patients experienced a favorable postoperative course with significant improvements in heart failure symptoms. TR was markedly reduced;however, in one patient with concomitant mitral regurgitation (MR) and a high TRI-SCORE, MR worsened postoperatively. This patient later died from unknown causes due to multiple comorbidities in the late phase. Conclusions: Tricuspid valve repair on a beating heart was effective for improving the cardiac function, and the TRI-SCORE proved useful as a preoperative risk assessment tool. The underlying mechanism by which TR exacerbates MR requires further investigation.展开更多
The paper discusses minimizing the effect of external mechanical vibration on hydraulic valves in different military hydraulic drive systems.The current research work presents an analysis of the potential to reduce vi...The paper discusses minimizing the effect of external mechanical vibration on hydraulic valves in different military hydraulic drive systems.The current research work presents an analysis of the potential to reduce vibration on the valve casing by installing a valve flexibly on a vibrating surface,i.e.,by introducing a material with known stiffness and damping characteristics between the valve casing and the vibrating surface-a steel spring package or special cushions made of elastomer material or of oilresistant rubber.The article also demonstrates that elastomer cushions placed inside the valve casingbetween the casing and the centering springs-can be used as a supplementary or alternative solution in the analyzed method for mitigating the transfer of vibrations.By using materials with appropriately selected elastic and dissipative properties,the effectiveness of vibro-isolation can be increased.The presented theoretical analyzes by linear and non-linear mathematical models have been verified experimentally.展开更多
It has been hypothesized that leaflet substrates with a trilayer structure and anisotropicmechanical properties could be useful for the production of functional and long-lasting tissue-engineered leaflets.To investiga...It has been hypothesized that leaflet substrates with a trilayer structure and anisotropicmechanical properties could be useful for the production of functional and long-lasting tissue-engineered leaflets.To investigate the influence of the anisotropic structural and mechanical characteristics of a substrate on cells,in this study,we electrospun trilayer anisotropic fibrous substrates and randomly oriented isotropic fibrous substrates(used as controls)from polycaprolactone polymers.Consequently,the random substrates had higher radial and lower circumferential tensile properties than the trilayer substrates;however,they had similar flexural properties.Porcine valvular interstitial cells cultured on both substrates produced random and trilayer cell-cultured constructs,respectively.The trilayer cell-cultured constructs had more anisotropic mechanical properties,17%higher cellular proliferation,14%more extracellular matrix(i.e.,collagen and glycosaminoglycan)production,and superior gene and protein expression,suggesting that more cells were in a growth state in the trilayer constructs than in the random constructs.Furthermore,the random and radial layers of the trilayer constructs had more vimentin,collagen,transforming growth factor-beta 1(TGF-ß1),transforming growth factor-beta 3(TGF-ß3)gene expression than in the circumferential layer of the constructs.This study verifies that the differences in structural,tensile,and anisotropic properties of the trilayer and random substrates influence the characteristics of the cells and ECM in the constructs.展开更多
We establish a simulation model based on the theory of air flow to analyze the accelerated release effect of the quick release valve inside the air brake control valve.In addition, the combined simulation system of tr...We establish a simulation model based on the theory of air flow to analyze the accelerated release effect of the quick release valve inside the air brake control valve.In addition, the combined simulation system of train air brake system and longitudinal train dynamics is used to analyze how the parameters of the quick release valve in the 120/120–1 brake control valve affect the propagation characteristics of the train brake pipe pressure wave, the release action range of the accelerated brake, and the longitudinal coupler force for a 20,000-ton heavy haul train on the section of the Datong–Qinhuangdao Railway. The results show that the quick release valve can effectively accelerate the rising speed of the train brake pipe pressure during the initial release, as the accelerated release effect is evident before the train brake pipe pressure reaches582 k Pa. The quick release valve can effectively accelerate the release of the rear cars, reducing the longitudinal coupler force impact due to time delay of the release process. The quick release valve can effectively reduce the tensile coupler force in the train by as much as 20% in certain cases.展开更多
文摘Since the advent of transcatheter aortic valve replacement(TAVR)in 2002,it has now become the default interventional strategy for symptomatic patients presenting with severe aortic stenosis,particularly in intermediate to highsurgical risk patients.In 2019,the United States Food and Drug Administration approved TAVR in low-risk patients based on two randomized trials.However,these breakthrough trials excluded patients with certain unfavorable anatomies and odd profiles.While currently there is no randomized study of TAVR in young patients,it may be preferred by the young population given the benefits of early discharge,shorter hospital stay,and expedite recovery.Nonetheless,it is important to ruminate various factors including lifetime expectancy,risk of pacemaker implantation,and the need for future valve or coronary interventions in young cohorts before considering TAVR in these patients.Furthermore,the data on long-term durability(>10 years)of TAVR is still unknown given most of the procedures were initially performed in the high or prohibitive surgical risk population.Thus,this editorial aims to highlight the importance of considering an individualized approach in young patients with consideration of various factors including lifetime expectancy while choosing TAVR against surgical aortic valve replacement.
基金sponsored by the Science and Technology Program of State Grid Corporation of China(4000-202355090A-1-1ZN)。
文摘The liquid-cooled battery energy sto rage system(LCBESS) has gained significant attention due to its superior thermal management capacity.However,liquid-cooled battery pack(LCBP) usually has a high sealing level above IP65,which can trap flammable and explosive gases from battery thermal runaway and cause explosions.This poses serious safety risks and challenges for LCBESS.In this study,we tested overcharged battery inside a commercial LCBP and found that the conventionally mechanical pressure relief valve(PRV) on the LCBP had a delayed response and low-pressure relief efficiency.A realistic 20-foot model of an energy storage cabin was constructed using the Flacs finite element simulation software.Comparative studies were conducted to evaluate the pressure relief efficiency and the influence on neighboring battery packs in case of internal explosions,considering different sizes and installation positions of the PRV.Here,a newly developed electric-controlled PRV integrated with battery fault detection is introduced,capable of starting within 50 ms of the battery safety valve opening.Furthermore,the PRV was integrated with the battery management system and changed the battery charging and discharging strategy after the PRV was opened.Experimental tests confirmed the efficacy of this method in preventing explosions.This paper addresses the safety concerns associated with LCBPs and proposes an effective solution for explosion relief.
基金supported by the National Key R&D Program of China(No.2021YFB2402001)the Postgraduate Innovation and Entrepreneurship Practice Project of Anhui Province(No.2022cxcysj013)+2 种基金the China Postdoctoral Science Foundation(No.2022T150615)the Fundamental Research Funds for the Central Universities(No.WK5290000002)supported by Youth Innovation Promotion Association CAS(No.Y201768)。
文摘The safety valve is an important component to ensure the safe operation of lithium-ion batteries(LIBs).However,the effect of safety valve type on the thermal runaway(TR)and gas venting behavior of LIBs,as well as the TR hazard severity of LIBs,are not known.In this paper,the TR and gas venting behavior of three 100 A h lithium iron phosphate(LFP)batteries with different safety valves are investigated under overheating.Compared to previous studies,the main contribution of this work is in studying and evaluating the effect of gas venting behavior and TR hazard severity of LFP batteries with three safety valve types.Two significant results are obtained:(Ⅰ)the safety valve type dominates over gas venting pressure of battery during safety venting,the maximum gas venting pressure of LFP batteries with a round safety valve is 3320 Pa,which is one order of magnitude higher than other batteries with oval or cavity safety valve;(Ⅱ)the LFP battery with oval safety valve has the lowest TR hazard as shown by the TR hazard assessment model based on gray-fuzzy analytic hierarchy process.This study reveals the effect of safety valve type on TR and gas venting,providing a clear direction for the safety valve design.
基金supported by the Natural Science Foundation of China(Project Nos.52075340 and 61972011)the Shanghai Special Research Project on Aging Population and Maternal and Child Health(Project No.2020YJZX0106).
文摘This study explores the implementation of computed tomography(CT)reconstruction and simulation techniques for patient-specific valves,aiming to dissect the mechanical attributes of calcified valves within transcatheter heart valve replacement(TAVR)procedures.In order to facilitate this exploration,it derives pertinent formulas for 3D multi-material isogeometric hyperelastic analysis based on Hounsfield unit(HU)values,thereby unlocking foundational capabilities for isogeometric analysis in calcified aortic valves.A series of uniaxial and biaxial tensile tests is executed to obtain an accurate constitutive model for calcified active valves.To mitigate discretization errors,methodologies for reconstructing volumetric parametric models,integrating both geometric and material attributes,are introduced.Applying these analytical formulas,constitutive models,and precise analytical models to isogeometric analyses of calcified valves,the research ascertains their close alignment with experimental results through the close fit in displacement-stress curves,compellingly validating the accuracy and reliability of the method.This study presents a step-by-step approach to analyzing themechanical characteristics of patient-specific valves obtained fromCT images,holding significant clinical implications and assisting in the selection of treatment strategies and surgical intervention approaches in TAVR procedures.
文摘Transcatheter aortic valve replacement(TAVR)has emerged as a formidable treatment option for severe symptomatic aortic stenosis ahead of surgical aortic valve replacement.The encouraging results from large randomized controlled trials has resulted in an exponential rise in the use of TAVR even in the low-risk patients.However,this is not without challenges.Need for permanent pacemaker(PPM)post-TAVR remains the most frequent and clinically relevant challenge.Naturally,identifying risk factors which predispose an individual to develop high grade conduction block post-TAVR is important.Various demographic factors,electrocardiographic features,anatomic factors and procedural characteristics have all been linked to the development of advanced conduction block and need for PPM following TAVR.Amongst these electrophysiological variables,most notably a prolonged QRS>120 ms regardless of the type of conduction block seems to be one of the strongest predictors on logistic regression models.The index study by Nwaedozie et al highlights that patients requiring PPM post-TAVR had higher odds of having a baseline QRS>120 ms and were more likely to be having diabetes mellitus that those who did not require PPM.
文摘In this editorial,we comprehensively summarized the preoperative risk factors of early permanent pacemaker implantation after transcatheter aortic valve replacement(TAVR)among patients with severe aortic stenosis from several renowned clinical studies and focused on the primary prevention of managing the modifiable factors,e.g.,paroxysmal atrial fibrillation before the TAVR.
文摘Pacemaker post-transcatheter aortic valve replacement is related to multifactorial risk.Nwaedozie et al brought to the body of evidence electrocardiogram and clinical findings.However,procedural characteristics have at least as much impact on the final need for a permanent pacemaker and potentially on the pacing rate.In this regard,long-term follow-up and understanding of the impact of long-term stimulation is of utmost importance.
基金funded by the Science and Technology Research and Development Plan of the China State Railway Group Company Limited(No.N2023J053).
文摘Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resistance and low-temperature resistance,respectively.In order to develop type 120 emergency valverubber diaphragms with long-life and high-performance,low-temperatureresistant CR and NR were processed.Design/methodology/approach–The physical properties of the low-temperature-resistant CR and NRwere tested by low-temperature stretching,dynamic mechanical analysis,differential scanning calorimetryand thermogravimetric analysis.Single-valve and single-vehicle tests of type 120 emergency valves werecarried out for emergency diaphragms consisting of NR and CR.Findings–The low-temperature-resistant CR and NR exhibited excellent physical properties.The elasticityand low-temperature resistance of NR were superior to those of CR,whereas the mechanical properties of thetwo rubbers were similar in the temperature range of 0℃–150℃.The NR and CR emergency diaphragms metthe requirements of the single-valve test.In the low-temperature single-vehicle test,only the low-temperaturesensitivity test of the NR emergency diaphragm met the requirements.Originality/value–The innovation of this study is that it provides valuable data and experience for futuredevelopment of type 120 valve rubber diaphragms.
文摘Aortic valve calcification disease (CAVD) is the most prevalent degenerative valve disease in humans, leading to significant morbidity and mortality. Despite its common occurrence, our understanding of the underlying mechanisms remains incomplete, and available treatment options are limited and risky. A more comprehensive understanding of the biology of CAVD is essential to identify new therapeutic strategies. Animal models have played a crucial role in advancing our knowledge of CAVD and exploring potential treatments. However, these models have inherent limitations as they cannot fully replicate the complex physiological mechanisms of human CAVD. In this review, we examine various CAVD models ranging from pigs to mice, highlighting the unique characteristics of each model to enhance our understanding of CAVD. While these models offer valuable insights, they also have limitations and shortcomings. We propose that the guide wire model shows promise for future CAVD research, and streamlining the methodology could enhance our understanding and expand the research scope in this field.
文摘Background: Tuberculous endocarditis is a rare but serious complication of heart valve replacement surgery. We report the case of a 24-year-old patient, who presented with tuberculous endocarditis after mechanical mitral valve replacement, with a favorable clinical course following anti-tuberculosis treatment. Case Presentation: We report a 24-year-old male patient, admitted to the cardiac surgery department of the Fann Hospital (Dakar, Senegal), for the management of severe mixed (rheumatic and endocarditic) mitral insufficiency with associated tricuspid insufficiency. He had a history of recurrent angina and polyarthralgia in childhood, was hospitalized several times for refractory global cardiac decompensation, and for a suspected infective endocarditis a month before his admission. On admission, the clinical examination revealed signs suggestive of mitral and tricuspid insufficiency. Transthoracic echocardiography revealed severe post-endocarditic mitral insufficiency with A3 amputation, highly mobile 15 mm vegetations on the free edge of the large valve, moderate tricuspid insufficiency, and severe pulmonary artery hypertension. Mechanical mitral valve replacement and tricuspid valve annuloplasty using autologous pericardial strip were performed via median sternotomy. After ten days, the patient presented with global cardiac decompensation associated with a clinico-biological infectious syndrome, and tans-oesophageal echography revealed an abscess at the sinotubular junction, communicating with the aorta. A thoraco-abdomino-pelvic CT scan was done, which revealed a bilateral alveolar-interstitial syndrome with mediastinal lymphadenopathy. Anti-tuberculosis treatment with RHZE was initiated for 06 months. The clinical course was favorable. Conclusion: Tuberculous endocarditis in prostheses is a serious complication of heart valve replacement surgery, which may evolve favorably under medical treatment.
文摘The mathematical model of the solenoid valve under varying temperatures is constructed to investigate its performance and enhance heat dissipation balance.The relationship between temperature and electromagnetic force is determined.Electrothermal coupling simulation using COMSOL is conducted,optimizing the outer diameter and length structure parameters of the coil.It is established that the heat dissipation of the coil is influenced by its outer diameter.Subsequently,based on optimized coil structure parameters,an orthogonal experimental design method combined with Ansys Maxwell is employed for simulation solution analysis to study the impact of structural parameters such as length,position,front and rear angles of the magnetic barrier ring in the iron core,armature length,and through-hole size on electromagnetic force.Optimal structural parameters are identified.Results indicate a decrease in steady-state electromagnet temperature by 3-4℃,an increase in the initial electromagnetic force by 32.63%,and a rise in the maximum electromagnetic force by 27.10%.
文摘Introduction: Treatments for cardiovascular diseases have increasingly evolved with the tendency to offer minimally invasive or transcatheter procedures instead of conventional sternotomy surgery. In this context, we highlight minimally invasive mitral valve surgery (MIMVS), which has been shown to be an increasingly solid option with some superior results when compared to the conventional technique: better pain control, shorter hospital stays, shorter recovery time, shorter readmission rate in the first postoperative year, better aesthetic results, and lower overall cost. Aim: This study aims to evaluate the stages of MIMVS, by primary mitral valve consultation, in our service and compare these results with data from the literature. Methods: All electronic medical records of patients who underwent MIMVS for primary mitral valve injury in the Encore Hospital from January 2020 to February 2023 were analyzed. Tabulation and statistical analysis were performed using the Microsoft Excel<sup>®</sup> program. Quantitative variables were presented as means, standard deviations. Results: 46 patients were enrolled in our study (Age: 59.1 ± 12.4 years old;60.8% Female, BMI: 26 ± 4.4 Kg/m<sup>2</sup>, Low risk STS score: 82.6%). The observed 30-day mortality was 2.1%, plastic rate of 23.9%, blood transfusion rate of 41.3%, length of stay in an intensive care bed (ICB) of 3.3 ± 3.3 days and hospital stay of 6.4 ± 5.1 days. Conclusions: We noticed that the MIMVS results carried out in our service agree with data from national and international literature with approximately 1.3 days more hospitalization in ICB.
文摘BACKGROUND Conduction and rhythm abnormalities requiring permanent pacemakers(PPM)are short-term complications following transcatheter aortic valve replacement(TAVR),and their clinical outcomes remain conflicting.Potential novel predictors of post-TAVR PPM,like QRS duration,QTc prolongation,and supraventricular arrhythmias,have been poorly studied.AIM To evaluate the effects of baseline nonspecific interventricular conduction delay and supraventricular arrhythmia on post-TAVR PPM requirement and determine the impact of PPM implantation on clinical outcomes.METHODS RESULTS Out of the 357 patients that met inclusion criteria,the mean age was 80 years,188(52.7%)were male,and 57(16%)had a PPM implantation.Baseline demographics,valve type,and cardiovascular risk factors were similar except for type II diabetes mellitus(DM),which was more prevalent in the PPM cohort(59.6%vs 40.7%;P=0.009).The PPM cohort had a significantly higher rate of pre-procedure right bundle branch block,prolonged QRS>120 ms,prolonged QTc>470 ms,and supraventricular arrhythmias.There was a consistently significant increase in the odds ratio(OR)of PPM implantation for every 20 ms increase in the QRS duration above 100 ms:QRS 101-120[OR:2.44;confidence intervals(CI):1.14-5.25;P=0.022],QRS 121-140(OR:3.25;CI:1.32-7.98;P=0.010),QRS 141-160(OR:6.98;CI:3.10-15.61;P<0.001).After model adjustment for baseline risk factors,the OR remained significant for type II DM(aOR:2.16;CI:1.18-3.94;P=0.012),QRS>120(aOR:2.18;CI:1.02-4.66;P=0.045)and marginally significant for supraventricular arrhythmias(aOR:1.82;CI:0.97-3.42;P=0.062).The PPM cohort had a higher adjusted OR of heart failure(HF)hospitalization(aOR:2.2;CI:1.1-4.3;P=0.022)and nonfatal myocardial infarction(MI)(aOR:3.9;CI:1.1-14;P=0.031)without any difference in mortality(aOR:1.1;CI:0.5-2.7;P=0.796)at one year.CONCLUSION Pre-TAVR type II DM and QRS duration>120,regardless of the presence of bundle branch blocks,are predictors of post-TAVR PPM.At 1-year post-TAVR,patients with PPM have higher odds of HF hospitalization and MI.
文摘The most common congenital heart defect is the bicuspid aortic valve (BAV) occurring with fusion of one of the three-valve commissures. A rarer valvular phenomenon is the unicuspid aortic valve (UAV) which has an estimated prevalence of 0.02% in the adult population. Two morphologic subtypes of UAV exist: the earlier presenting, acommissural UAV and the later appearing unicommissural. To better characterize and manage patients with UAVs, a systematic review of this rare phenomenon was performed. The objective of our study was to conduct a systematic review of adequate case studies involving UAV patients to describe patient characteristics, clinical presentation, management, and common sequela featured there within. The mean age of presentation in this review was 35.6 years. When diagnosing UAV, TEE was the most utilized diagnostic modality (65%) followed by intraoperative diagnosis (17%) discovered with valve repair or incidentally during another procedure. TTE was utilized to diagnose only 7% of the cases reviewed likely owing to the difficulty and inaccuracies in identifying UAV with this method that were previously established by multiple series. Interventional options for UAV are balloon versus surgical valvotomy, aortic valve replacement, Ross procedure and aortic root replacement. They are performed on an individual basis and all cases ultimately require aortic valve replacement (AVR) or Ross procedure (to avoid anticoagulation). Aortic root replacement is additionally required if aortic root/ascending aorta diameter exceeds 4.5 cm. In this review, Aortic aneurysm (16%) cases resulted in surgical interventions. There may be a need to implant permanent pacemaker (in 3% - 8%) during AVR when calcified UAV has calcification extending into interventricular septum.
基金This research was funded by the 2020 Shandong Province Key Research and Development Programs(Major Technological Innovation Projects):Construction Machinery Integration Research and Application of Key Technologies for Intelligent Integration and Matching of Vehicle Assembly(2020CXGC011005)Large Tractor Hydraulic CVT Intelligent Continuously Variable Transmission Integration Research and Application(2020CXGC010806)Development and Application of High-Horsepower High-Efficiency Intelligent Tractors(2021CXGC010812).
文摘Electro-hydraulic proportional valve is the core control valve in many hydraulic systems used in agricultural and engineering machinery.To address the problem related to the large throttling losses and poor stability typically associated with these valves,here,the beneficial effects of a triangular groove structure on the related hydraulic response are studied.A mathematical model of the pressure compensation system based on the power-bond graph method is introduced,and the AMESim software is used to simulate its response.The results show that the triangular groove structure increases the jet angle and effectively compensates for the hydrodynamic force.The steady-state differential pressure at the valve port of the new pressure compensation structure was 0.65 MPa.Furthermore,experimental results show that the pressure difference at the main valve port is 0.73 MPa,and that the response time is less than 0.2 s.It is concluded that the new compensation structure has good pressure compensation response characteristics.
文摘Background:The Venus-P valve was the first self-expanding valve used world-wide for transcatheter pulmonary valve replacement(TPVR)in patients with severe pulmonary regurgitation(PR).We intended to report the extended follow-up results from the prospective trial(No.NCT02590679).Methods:A total of 38 patients with severe PR(mean age 24.2±13.2)were included.Follow-up data were obtained after implanted at 1,6,and 12 months and yearly after.The frame geometry was assessed on post-implant computer tomography(CT)scanning by calculating the non-circularity[circularity ratio(minimum diameter/maximum diameter)<0.9]and under-expansion[expansion ratio(derived external valve area/nominal external valve area)<0.9).Adverse events(all-cause mortality,reintervention,valve dysfunction,stent fracture and endocarditis)were recorded.Results:All valves were implanted successfully with normal function at discharge.Geometric CT analysis showed underexpanded valve was detected in 22 patients(63%)and non-circular valve was seen in 16 patients(46%).During a median follow-up of 4.8 years(range 0.3-8.1),there were 1 death and 1 surgical explant,both resulting from endocarditis.Five-year freedom from valve dysfunction and stent fracture were 84.8%(95%CI 74.8-94.7)and 83.5%(95%CI 73.8-93.2).Endocarditis occurred in 3 patients at a median time of 7 months.Stent fracture was more common in patients with non-circularity stents.Conclusion:TPVR using Venus-P valve is associated with favorable outcomes at 5 years.Non-circular shapes in the valve level may have a higher risk of stent fracture.
文摘Background: Isolated tricuspid valve disease remains a controversial indication for surgical intervention. Many patients referred for surgery already have a poor clinical condition and an advanced New York Heart Association functional class. There is no consensus on the optimal surgical technique for this condition, including on whether to perform the procedure on a beating or an arrested heart and whether to perform valve repair or replacement. Methods: We analyzed four case series between 2015 and 2022 in which patients with secondary tricuspid regurgitation (TR) underwent valve repair on a beating heart and right atrial plication for a dilated right atrium. The TRI-SCORE was calculated for each patient. Results: All patients experienced a favorable postoperative course with significant improvements in heart failure symptoms. TR was markedly reduced;however, in one patient with concomitant mitral regurgitation (MR) and a high TRI-SCORE, MR worsened postoperatively. This patient later died from unknown causes due to multiple comorbidities in the late phase. Conclusions: Tricuspid valve repair on a beating heart was effective for improving the cardiac function, and the TRI-SCORE proved useful as a preoperative risk assessment tool. The underlying mechanism by which TR exacerbates MR requires further investigation.
文摘The paper discusses minimizing the effect of external mechanical vibration on hydraulic valves in different military hydraulic drive systems.The current research work presents an analysis of the potential to reduce vibration on the valve casing by installing a valve flexibly on a vibrating surface,i.e.,by introducing a material with known stiffness and damping characteristics between the valve casing and the vibrating surface-a steel spring package or special cushions made of elastomer material or of oilresistant rubber.The article also demonstrates that elastomer cushions placed inside the valve casingbetween the casing and the centering springs-can be used as a supplementary or alternative solution in the analyzed method for mitigating the transfer of vibrations.By using materials with appropriately selected elastic and dissipative properties,the effectiveness of vibro-isolation can be increased.The presented theoretical analyzes by linear and non-linear mathematical models have been verified experimentally.
基金supported by the National Institute of Health(No.NIH R00HL134823).
文摘It has been hypothesized that leaflet substrates with a trilayer structure and anisotropicmechanical properties could be useful for the production of functional and long-lasting tissue-engineered leaflets.To investigate the influence of the anisotropic structural and mechanical characteristics of a substrate on cells,in this study,we electrospun trilayer anisotropic fibrous substrates and randomly oriented isotropic fibrous substrates(used as controls)from polycaprolactone polymers.Consequently,the random substrates had higher radial and lower circumferential tensile properties than the trilayer substrates;however,they had similar flexural properties.Porcine valvular interstitial cells cultured on both substrates produced random and trilayer cell-cultured constructs,respectively.The trilayer cell-cultured constructs had more anisotropic mechanical properties,17%higher cellular proliferation,14%more extracellular matrix(i.e.,collagen and glycosaminoglycan)production,and superior gene and protein expression,suggesting that more cells were in a growth state in the trilayer constructs than in the random constructs.Furthermore,the random and radial layers of the trilayer constructs had more vimentin,collagen,transforming growth factor-beta 1(TGF-ß1),transforming growth factor-beta 3(TGF-ß3)gene expression than in the circumferential layer of the constructs.This study verifies that the differences in structural,tensile,and anisotropic properties of the trilayer and random substrates influence the characteristics of the cells and ECM in the constructs.
基金China National Railway Group Co.,Ltd(N2020J037).
文摘We establish a simulation model based on the theory of air flow to analyze the accelerated release effect of the quick release valve inside the air brake control valve.In addition, the combined simulation system of train air brake system and longitudinal train dynamics is used to analyze how the parameters of the quick release valve in the 120/120–1 brake control valve affect the propagation characteristics of the train brake pipe pressure wave, the release action range of the accelerated brake, and the longitudinal coupler force for a 20,000-ton heavy haul train on the section of the Datong–Qinhuangdao Railway. The results show that the quick release valve can effectively accelerate the rising speed of the train brake pipe pressure during the initial release, as the accelerated release effect is evident before the train brake pipe pressure reaches582 k Pa. The quick release valve can effectively accelerate the release of the rear cars, reducing the longitudinal coupler force impact due to time delay of the release process. The quick release valve can effectively reduce the tensile coupler force in the train by as much as 20% in certain cases.
