Pressure Rise Research Articles

Shock compression of liquefied gases: Molecular dissociation and radiance change at the sample/LiF interface.

This study investigates the behavior of nitrogen and other liquefied gases under shock compression, with a focus on temperature variations and molecular dissociation. Through dynamic compression experiments on liquefied Ar, O2, CO, and N2, we aimed to understand shock-induced cooling and radiance changes at the sample/lithium fluoride (LiF) interface. The experiments were conducted using a setup involving a Doppler pin system and pyrometer to measure shock velocities, pressures, and temperatures across the interface between shocked liquids and LiF. Under the first-shock, molecular liquids experienced partial dissociation due to a rapid rise in pressure, density, and temperature within nanoseconds. Upon re-shocking at the sample/LiF interface, a radiance drop was observed for all liquids except Ar. Our data analysis suggests that the cooling effect is likely due to a chemical reaction occurring at the interface between reactive species, produced during the initial shock, and the layer of LiF at the surface under re-shock conditions. One probable interpretation is that this reaction formed a thin, partially transparent layer on the LiF, which absorbed a significant portion of the radiation emitted by the shocked fluid. Thus, the observed temperature drop in re-shocked liquid nitrogen is likely attributable to radiation reduction.

Elastic Anisotropy and Thermal Properties of Sr2ZrMoO6 Double Perovskite under Different Pressure

This study investigates the elastic and thermal properties of the double perovskite Sr2ZrMoO6 under different pressures from 0 to 80 GPa using first‐principles calculations within the generalized gradient approximation of density functional theory. The calculated second‐order elastic constants confirm the mechanical stability of the compound up to 80 GPa. The material exhibits significant elastic anisotropy, with elastic constants C11, C33, and C44 showing distinct pressure‐dependent behavior. The elastic properties, including bulk modulus, shear modulus, Young's modulus, and Poisson's ratio, all increase with a rise in pressure, which enhances the material's stiffness and rigidity, improving its resistance to deformation or fracture. The Pugh ratio greater than 0.57, a negative Cauchy constant, and a low Poisson's ratio suggest that the material remains brittle within the examined pressure range. The calculated tolerance factor and formation energy confirm its thermodynamic stability. The minimum thermal conductivity of the material increases slightly with pressure across all directions, maintaining the anisotropic order > > , indicating improved phonon transport under compression. The specific heat capacity increases with pressure at low temperatures and approaches the Dulong–Petit limit at higher temperatures. These findings suggest Sr2ZrMoO6 holds potential for high‐performance optical waveguides and optoelectronic applications.

Abstract TP397: Effect of Intracranial Pressure Spikes Modeling Subarachnoid Aneurysm Rupture on the Brain and Dura Barrier Immune System

Steep intracranial pressure (ICP) rise constitutes a hallmark of aneurysmal subarachnoid hemorrhage (SAH). While during aneurysm rupture there are multiple simultaneous triggers that can initiate an inflammatory response, in this study we isolate the impact of a single ICP spike on the brain and meningeal barriers and the resulting secondary injury. Using a rodent model, we induced an ICP spike through cisterna magna injection of artificial cerebrospinal fluid or autologous blood, with simultaneous ICP monitoring. We then assessed the innate immune response in the brain parenchyma and dura using immunohistochemistry and multiparameter flow cytometry. Glia limitans integrity was evaluated via intrathecal injection of the SR101 tracer, and microthrombi presence was assessed using intravenous fluorescent fibrin. Upregulated pathways were identified through bulk RNA sequencing. Our findings revealed that a single ICP spike exerts global effects on brain and meningeal barrier immunology, potentially leading to secondary injury. Histological analysis and flow cytometry of dura whole mounts showed extensive cell death of resident CD206+ macrophages, essential for steady-state immune surveillance, alongside infiltration of Ly6C+ pro-inflammatory monocytes and Ly6G+ neutrophils, indicating a robust acute response to the ICP spike. In the brain parenchyma, we observed minimal infiltration of circulating immune cells, consistent with the effects of aneurysm rupture. However, diffuse microglia clustering suggested multifocal parenchymal injury. Additionally, there was evidence of widespread glia limitans disruption and microthrombi formation in the brain parenchyma. Bulk RNA sequencing supported these findings, demonstrating upregulation of MyD88 and TNFα pathways in the dura, which were absent in the brain. In conclusion, this study demonstrates that a single ICP spike triggers significant meningeal inflammation, disrupts steady-state dura immune surveillance, and causes diffuse parenchymal injury with glia limitans disruption. These results highlight a novel blood-independent pathway of injury following aneurysm rupture, offering new insights into potential therapeutic targets.

Effects of diesel pilot-injection strategy on a methanol/diesel dual-direct injection engine

To verify the effectiveness of dual-direct injection technology in enhancing the performance of methanol/diesel dual-fuel engines and the positive impacts of multiple-injection strategy on the in-cylinder mixture formation and combustion process, an experiment was conducted on a modified methanol/diesel dual-direct engine test platform in this paper. The research aimed to explore the effects of the diesel pilot-injection strategy, especially from the two aspects of diesel pilot-injection timing and diesel pilot-injection duration, on the operating range, combustion characteristics, performance and emissions. Results indicate that the pilot-injection strategy reduces the maximum pressure and pressure rise rate of the engine, alleviating the rough combustion in the cylinder and broaden the operating range. As the diesel pilot-injection timing advances, the in-cylinder pressure curve during the combustion process shifts leftward as a whole, and the pressure rise rate curve gradually becomes an approximate single-peak shape. The ignition delay almost increases linearly and CA50 first decreases and then increases with the advance of pilot-injection timing. When the pilot-injection duration increases, the ignition delay shortens and CA50 advances. Additionally, the diesel pilot-injection strategy can optimize engine emissions. As the pilot-injection timing advances and the duration increases, the HC, CO and soot emissions decrease, while the NOx emission increases. Using the pilot-injection strategy, the highest indicated thermal efficiency of 42.94 % is obtained at the diesel ignition injection timing and duration of −28 °CA aTDC and 0.25 ms respectively, which is 7.54 % relatively higher than that under a single injection strategy. The research results show that the pilot-injection strategy better adjusts the distribution of high reactivity and low reactivity fuels in the cylinder, which is beneficial for improving the combustion and performance of the methanol/diesel dual-fuel engine.

Radar and profiler observations of the kinematic and thermodynamic structure of a shallow bore in a low-shear environment

Abstract Observations obtained from scanning radars, two profiling systems, surface, and radiosonde instruments are utilized to describe the weakening stages of a long-lived (>4 h), shallow bore that evolved within a low-shear environment on 23 August 2013 over northern Alabama. RHI scans from a scanning X-band radar provided details on the bore shape and surrounding mesoscale perturbations in airflow, while a Doppler lidar afforded high-resolution vertical motion profiles at a location 24 km away. During passage over both profiling sites, updrafts (~2 m s−1) were sampled over the lowest several hundred meters AGL, and aerosol backscatter showed upward displacements of 300-400 m near the 1.2 km AGL level. The surface pressure rise of ~0.3 hPa at multiple locations over the observational network corroborates the shallowness of both the bore and the surface-based inversion. Several other unique features were documented, including bore movement in the direction of the weak low-level flow; a gust front structure with a well-defined feeder flow trailing the bore gust front, both confined to the lowest 500 m AGL; the presence of waves preceding and following the bore disturbance, with a 12-21 min period within the 0.5-2.5 km layer above the bore at both profiler locations; and variations in horizontal flow in the form of a weak jet near 1.4 km AGL, with winds in the jet aligned in the same direction as bore movement, and located more than 10 km ahead of the bore gust front.

Intraocular pressure rise, hyphema and uveitis in chronic lymphocytic leukemia undergoing ibrutinib treatment

Intraocular pressure rise, hyphema and uveitis in chronic lymphocytic leukemia undergoing ibrutinib treatment

Application of biomanufacturing in polymer flooding

In China, the crude oil supply is highly dependent on overseas countries, and thus strengthening crude oil self-sufficiency has become an important issue of the national energy security. Tertiary oil recovery, especially polymer flooding, has been widely applied in large oil fields in China, which can increase the recovery rate by 15%-20% compared with water flooding. However, the widely used oil flooding polymers show poor thermal stability and salinity tolerance, complicated synthesis ways of monomers, and environmental unfriendliness. Moreover, the polymer flooding induces problems including pore plugging, heterogeneity intensification, high dispersion of remaining oil resources, pressure rise in injection wells, and low efficiency circulation of injection medium, which restrict the subsequent recovery of old oil fields. Here, we systematically review the developing and current situations of polymer flooding, introduce the innovative biomanufacturing of oil flooding polymers and their monomers or precursors as well as low-cost bio-based chemical raw materials for multiple compound flooding. The comprehensive study of the relationships between microbial fermentation metabolites and polymer flooding will reveal the green and low-carbon paths for polymer flooding. Such study will enable the application of enzymes produced by microorganisms in polymer production and polymer plugging removal after polymer flooding as well as the application of microbial metabolites such as biosurfactants, organic acids, alcohols, biogas, and amino acids in enhancing oil recovery. This review suggests that incorporating biomanufacturing into polymer flooding will ensure the high productivity and stability for crude oil production in China.

Combination therapy of intravitreal ranibizumab and sub-tenon triamcinolone for treatment of resistant diabetic macular edema: a clinical study in Egypt

BackgroundAmong those aged 20–74 in industrialized countries, diabetic retinopathy (DR) is the main cause of visual impairment. Diabetic macular edema (DME) is the leading cause of blindness in people with DR. DME that is resistant to therapy is now being treated with a number of different management strategies. This research was to examine the efficacy of sub-tenon steroid and anti- vascular endothelial growth factor (VEGF) injections as a combination therapy for the treatment of resistant DME, owing to the synergistic effect of this combination.MethodsThis is a two-arm, randomized, prospective clinical trial that included 100 eyes of patients with refractory DME divided into 2 equal groups: group 1 received posterior subtenon triamcinolone (STTA) and anti-VEGF injections (0.5 mg ranibizumab), and group 2 received anti-VEGF injections (0.5 mg ranibizumab) only, in the same session. The 2 groups were followed up for a period of 6 months.ResultsGroup 1 showed significant improvements in best corrected visual acuity (BCVA) (from 0.20 ± 0.11 to 0.32 ± 0.12, p = 0.04) and central macular thickness (CMT) (from 393.2 ± 35.29 to 260.2 ± 11.43 µm, p = 0.001), with fewer injections required compared to Group 2. Recurrence rates were significantly higher in Group 2 (42% vs. 12%, p = 0.026). After injections, there was a noticeable rise in intraocular pressure (IOP) (16.02 ± 1.56 Vs 16.26 ± 1.24 in both groups respectively). However, this elevation is usually just transitory lasting for short periods of time and is within the safe, insignificant rise ranges.ConclusionThe use of combined therapy with anti-VEGF treatment and STTA has been found to be an effective and safe approach to managing resistant DME. The lower number of injections needed help to reduce the economic burden, especially under constrained financial circumstances.

Damage and permeability of gassy coal in loading – Unloading path

To effectively prevent dynamic gas disasters, the adding vertical and unloading radial stress were investigated in laboratory and numerical simulation experiments. The objective about the research was to ascertain how various gas pressures and loading rates affected permeability and damage deformation. The results conclude that shear failure predominates in gassy coal, a rise in loading rate causes the permeability to mutate more slowly, and the plastic strain gradually decreases at the yield, peak, and post-peak stable points in gassy coal. As well, a rise in gas pressure causes an earlier transition from compression to expansion state of specimens, enhances permeability, and rises the plastic strain at specified points. Furthermore, the study focuses on the meso-scale failure and permeability characteristics. During failure, the seepage channel within the coal body gradually transitions from a vertical orientation to irregular deformation. In addition, a damage model is formulated centered around energy consumption, demonstrating that damage evolution curves exhibit an ‘ S’ shape with vertical strain. Meanwhile, higher axial loading rates delay the onset of unstable crack propagation, but raising gas pressure quickens the pace of damage to specimens. The conclusions of this research hold significant practical implications for mitigating coal-rock gas dynamic disasters.

Optimizing bioconvective heat transfer with MHD Eyring–Powell nanofluids containing motile microorganisms with viscosity variability and porous media in ciliated microchannels

Purpose This paper aims to optimize bioconvective heat transfer for magnetohydrodynamics Eyring–Powell nanofluids containing motile microorganisms with variable viscosity and porous media in ciliated microchannels. Design/methodology/approach The flow problem is first modeled in the two-dimensional frame and then simplified under low Reynolds number and long wavelength approximations. The numerical method is used to examine the impact of thermal radiation, temperature-dependent viscosity, mixed convection, magnetic fields, Ohmic heating and porous media for velocity, temperature, concentration and motile microorganisms. Graphical results are presented to observe the impact of physical parameters on pressure rise, pressure gradient and streamlines. Findings It is observed that the temperature of nanofluid decreases with higher values of the viscosity parameter. It is absolutely in accordance with the physical expectation as the radiation parameter increases, the heat transfer rate at the boundary decreases. Nanoparticle concentration increases by increasing the values of bioconvection Rayleigh number. The density of motile microorganisms decreases when bioconvection Peclet number is increased. The velocity of the nanofluid decreases with higher value of Darcy number. With increase in the value of bioconvection parameter, the flow of nanofluid is increased. Originality/value The bioconvective peristaltic movement of magnetohydrodynamic nanofluid in ciliated media is proposed. The non-Newtonian behavior of the fluid is described by using an Eyring–Powell fluid model.

Kinetic Mechanism and Experimental Study of Initial Temperature and Blended Gas Addition on Combustion Characteristics of Coal Bed Methane-Air

ABSTRACT Coal bed methane (CBM) is a clean energy resource, CH4 and various blends of C2H6, C2H4, CO, and H2 in different proportions were chosen to formulate a surrogate fuel for coal bed methane. The objective was to study the explosion characteristics of coal bed methane while alleviating the computational complexity associated with intricate reaction mechanisms. The explosion properties (peak explosion pressure (P max) and the maximum pressure rise rate (dp/dt) max) of the mixtures were tested. The unstretched laminar burning velocity (U l ) of the surrogate components was determined under a range of initial temperatures (T u ) (298–373 K) and blended fuel concentrations (0.4–2.0%). Two simplified kinetics models for the surrogate fuel were developed using the GRI Mech 3.0 and USC Mech II mechanisms. These models were constructed through the application of a direct relation graph with error propagation (DRGEP) and full species sensitivity analysis (FSSA). To assess the accuracy of the models, simulations based on these simplified mechanisms were compared with both the detailed mechanism and experimental data. Additionally, sensitivity analyses, utilizing the simplified mechanism, were conducted in order to identify precisely the reactions that govern the interaction dynamics between blended fuel and methane. Within the range of the experimental conditions, the results indicated that P max decreased linearly and with increasing initial temperature. (dp/dt) max was only slightly sensitive to the variation in the initial temperature. However, U l increased with increasing initial temperature, as expected. When blended fuel was added to a 7% CH4-air mixture, P max, (dp/dt)max, and unstretched U l exhibited increasing trends. An equation was derived using the experimental data, to forecast changes in U l across elevated temperatures and blended gas concentrations. The simplified mechanism model successfully replicated the results of the detailed mechanism model and demonstrated good agreement with experimental data concerning species concentrations, ignition delay times, and the U l of the coal bed methane surrogate fuel. Compared to sample 2, the chemistry of sample 1 exhibits greater sensitivity toward intermediate temperature reactions, particularly at higher temperatures.

Advancement of the Dragon Heart 7-Series for Pediatric Patients With Heart Failure.

Safe and effective pediatric blood pumps continue to lag far behind those developed for adults. To address this growing unmet clinical need, we are developing a hybrid, continuous-flow, magnetically levitated, pediatric total artificial heart (TAH). Our hybrid TAH design, the Dragon Heart (DH), integrates both an axial flow and centrifugal flow blood pump within a single, compact housing. The axial pump is embedded in the central hub region of the centrifugal pump, and both pumps rotate around a common central axis, while maintaining separate fluid domains. In this work, we concentrated our design and development effort on the centrifugal blood pump by performing computational modeling. An iterative process was employed to improve the DH design. The pressure generation, scalar stress levels, and fluid forces exerted on the magnetically levitated impellers were computationally estimated. A shaft driven centrifugal prototype was also manufactured and tested using a hydraulic flow loop circulating a water-glycerol blood analog. Pressure and flow performance of the pump prototype was measured for a given rotational speed for comparison to computational predictions. Our design achieved the target pump pressures of 60-140 mm Hg for flow rates of 1-5 L/min, and strong agreement in pressure rise was demonstrated between the experimental data and simulation results (less than 10% deviation on average). Fluid stress levels were, however, found to exceed thresholds in the outflow region of the pump, and fluid residence times were less than 600 ms. The findings of this work demonstrate that the more compact, next-gen DH's centrifugal pump design is able to achieve pressure-capacity requirements. Next steps will require a focused strategy to reduce hemolytic potential and to integrate magnetic suspension components for full rotor levitation.

Diuretics in patients with chronic kidney disease.

Diuretic drugs act on electrolyte transporters in the kidney to induce diuresis and are often used in chronic kidney disease (CKD), given that nephron loss creates a deficit in the ability to excrete dietary sodium, which promotes an increase in plasma volume. This rise in plasma volume is exacerbated by CKD-induced systemic and intra-renal activation of the renin-angiotensin-aldosterone-system, which further limits urinary sodium excretion. In the absence of a compensatory decrease in systemic vascular resistance, increases in plasma volume induced by sodium retention can manifest as a rise in systemic arterial blood pressure. Management of sodium and volume overload in patients with CKD is therefore typically based on restriction of dietary sodium intake and the use of diuretic agents to enhance urinary sodium excretion. Thiazide and thiazide-type diuretics are foundational therapies for the management of hypertension, whereas loop diuretics are often needed for volume overload, which might also require combination therapies. Mineralocorticoid receptor antagonists have an important role in the management of diuretic-resistant volume overload or treatment-resistant hypertension. Additionally, diuretics can be used for the diagnosis of kidney diseases and in the management of hyperkalaemia or hypokalaemia, hyponatraemia, hypercalcaemia and hypomagnesaemia.

Minocycline prevents monocrotaline-induced pulmonary hypertension through the attenuation of endothelial dysfunction and vascular wall thickening.

Pulmonary hypertension (PH) is a progressive disease with a poor prognosis in which high pulmonary artery pressure leads to right heart failure, therefore, there is an urgent need to elucidate pathological mechanisms and to develop new treatment for PH. Minocycline has not only antibacterial effects but also anti-inflammatory effects in various tissues. We hypothesize that minocycline could prevent PH development in rats. PH was induced by a single intraperitoneal injection of monocrotaline (MCT, 60mg/kg), and minocycline (20mg/kg) was treated daily for 14 days from the day of MCT injection. Minocycline inhibited the rise in mean pulmonary arterial pressure of MCT-induced PH rats and improved the attenuation of acetylcholine-induced relaxation in isolated intrapulmonary artery from MCT-induced PH rats. Minocycline further inhibited vascular wall thickening of pulmonary arterioles and showed a tendency to inhibit the muscularization of pulmonary arterioles in MCT-induced PH rats. PH-preventing effect of minocycline does not seem to be mediated via the actions on matrix metalloproteinase, inflammatory cytokines, and mast cells migration in lung. In summary, we revealed for the first time that minocycline ameliorated the MCT-induced PH in rats, at least partly through preventing pulmonary artery endothelial dysfunction and wall thickening.

Predicting non-ideal effects from the diaphragm opening process in shock tubes

Shock tubes are instrumental in studying high-temperature kinetics and simulating high-speed flows. They rapidly increase the thermodynamic conditions of test gases, making them ideal for examining chemical reactions and generating high-enthalpy flows for aerodynamic research. However, non-ideal effects, stemming from factors like diaphragm opening processes and viscous effects, can significantly influence thermodynamic conditions behind the shock wave. This study investigates the impact of various diaphragm opening patterns on the shock parameters near the driven section's end wall. Experiments were conducted using helium and argon as driver and driven gases, respectively, at pressures ranging from 1.32 to 2.09 bar and temperatures from 1073 to 2126 K behind the reflected shock. High-speed imaging captured different diaphragm rupture profiles, classified into four distinct types based on their dynamics. Results indicate that the initial stages of diaphragm opening, including the rate and profile of opening, play crucial roles in the resulting incident shock Mach number and test time. A sigmoid function was employed to fit the diaphragm opening profiles, allowing for accurate categorization and analysis. New correlations were developed to predict the incident shock attenuation rate and post-shock pressure rise, incorporating parameters such as diaphragm opening time, rupture profile constants, and normalized experimental Mach number. The results emphasize the importance of considering diaphragm rupture dynamics in shock tube experiments to achieve accurate predictions of shock parameters.

Direct determination of permeability, diffusivity and solubility of gases in membrane based on simultaneous monitoring of pressure rise and decay in a single time-lag experiment

Direct determination of permeability, diffusivity and solubility of gases in membrane based on simultaneous monitoring of pressure rise and decay in a single time-lag experiment

The numerical calculations for the creeping flow of MHD Pseudoplastic nanofluid in a mixed uniform and non-uniform channel: physiological applications

Adaptive calculations for the creeping flow of MHD Pseudoplastic nanofluid proposed in a mixed uniform and non-uniform channel. The fluid viscosity is hypothetical to change with the temperature and concentration, and then all non-dimensional parameters that be contingent on fluid viscosity are deliberated as a variable. The systemised physical model of fluid considered by a nonlinear system of partial differential equations is a first view in modelling problems. The non-dimensional quantities are used to rearrange the system of the fluid model. The semi-analytical algorithm titled a multi-stage differential transform extracts the analytical results for a physical model. Multi-stage DTM are a good analytical method for solving highly nonlinear systems of differential equations. The adaptive calculations for the pressure rise and pressure gradient profiles are obtained. In addition, the sketches of the trapped bolus are extracted. Analytical comparisons are made with trust in existing published results and found to be good. The results show that the fluid pressure gradient grows with increasing values of Darcy number at the positive part of the channel (Upper part of the channel) and have a dual role phenomenon at the negative part of the channel (Lower Part of the channel).

AGING AND CARDIOVASCULAR DISEASES

According to the World Health Organization, the term “elderly” refers to people over the age of 65. Decreases in heart rate, heart function, oxygen consumption and stroke rate occur with aging. Many changes occur in the cardiovascular system with aging, and this predisposes to diseases. The aim of this review article is to examine the physiological relationship between aging and cardiovascular diseases. Depending on genetic differences and age, the heart's ability to pump blood decreases, the myocardium loses flexibility, and the heart valves thicken and increase in diameter. Aging is an inevitable part of life and constitutes the most important risk factor for cardiovascular diseases. Arteriosclerosis increases the thickness of blood vessels while decreasing their elasticity. Functional and structural changes in the cardiovascular system in older ages increase the risk of coronary artery disease, heart diseases, heart failure, venous thrombosis, and hypertension. Cardiac output and stroke volume decreases and the risk of postural hypotension increases. With advancing age, a continuous rise in systolic blood pressure occurs as a result of a hardening of the vessels and their diminished elasticity. After the age of 60, either a slight decrease or no change is seen in diastolic blood pressure.

A Refined Model to Predict Boundary of Instability of Axial Compressors

A quantitative model to predict the boundary of instability of axial compressors based on their maximum loading capability is proposed in this paper, which is an improved version of the classic method of stalling pressure rise. The original model correlates the maximum pressure rise of a compressor to a characteristic geometric parameter, which is an analogue of the normalized length of diffusion in two-dimensional diffusers. However, the influence of the aspect ratio of the passage is overlooked in this analogy, which leads to significant discrepancies in its predictions for compressors, especially those with varying blade aspect ratios. Our model contains two improvements to address this issue. The first involves refining in the definition of the normalized length of diffusion, whereas the second introduces a supplementary correction factor for the aspect ratio of the blades. Nearly 20 low-speed compressor configurations, with variations in solidity, aspect ratio, tip clearance, and axial spacing, were tested to develop the proposed model. It can reduce error in the predicted stalling static pressure rise from 10% to 5%. Experimental data robustly verify the accuracy of our model, making it a more reliable predictive tool of instability boundary in the preliminary design of axial compressors.

Prognostic Value and Safety of Serial Exercise Echocardiography in Asymptomatic Severe Aortic Stenosis.

The prognostic value of serial exercise echocardiography (EEC) in asymptomatic severe aortic stenosis is unknown. We sought to evaluate the safety and utility of monitoring patients with asymptomatic severe aortic stenosis by annual EECs to refer them to aortic valve replacement (AVR) or to keep them under follow-up. The cohort comprised 196 patients, with a normal screening EEC and a minimal follow-up of 18 months. Follow-up was planned until there was an indication for AVR, based on a resting transthoracic echocardiography at 6 months and then every year, and an EEC at 1 year and then every year (alternating resting transthoracic echocardiography and EEC every 6 months). During follow-up, patients were referred to AVR if they reported symptoms, if rest transthoracic echocardiography was positive (left ventricular dysfunction, aortic maximal velocity ≥5 m/s, or severe valve calcification with aortic maximal velocity progression ≥0.3 m/s per year) or if EEC was positive (occurrence during exercise of any aortic stenosis-related symptoms, significant ventricular arrhythmias, a drop or an insufficient rise (<20 mm Hg) in systolic blood pressure from baseline, or a left ventricular dysfunction). Among the 196 patients (76% men, aged 76.1±11.1 years), a mean 2.85±1.22 EECs were conducted. There were no serious complications during any of the EECs. Each serial transthoracic echocardiography at rest and each EEC yielded 0%-22% and 23.5%-50% of positive results, respectively, leading to AVR. We delayed AVR by a mean of 2.93±1.95 years after the screening EEC. No cardiac-related death or sudden death was reported during the study. Our findings demonstrate the safety and prognostic utility of serial EECs in the management of patients with asymptomatic severe aortic stenosis to guide timely AVR.