Increasing Jet Velocity Research Articles

Instability model of water–steam–liquid metal three-phase jet flow during steam generator tube rupture accident in a fast reactor

The steam generator tube rupture (SGTR) accident in a lead-cooled fast reactor (LFR) results in an injection of high-pressure subcooled water from the secondary circuit into the high-temperature liquid lead-bismuth eutectic (LBE) pool in the primary loop. Rapid depressurization and phase-change heat transfer generate the steam between the water jet and liquid LBE. Based on jet instability theory, this study develops a temporal instability model focusing on the water–steam–liquid LBE three-phase flow in a cylindrical coordinate to investigate the breakup characteristics of water jet. By introducing velocity and pressure disturbances and adopting a linear assumption to the hydrodynamic governing equations, a dispersion equation is developed, and jet characteristic parameters are then defined. The effects of various operating parameters and key dimensionless numbers are further studied. By solving the dispersion equation, it is found that smaller steam film thickness and higher steam velocity enhance jet instability. Increasing jet velocity and reducing jet radius accelerate jet breakup and promote droplet refinement, while at higher jet velocities, the influence of jet radius diminishes. Additionally, the co-flow of LBE with the jet and the viscosity effect of LBE both stabilize the water jet. This model enables quantitative prediction of the breakup behavior of water jets in liquid LBE during the initial stage of SGTR accident, aiming to reveal the fundamental mechanisms of the physical process and provide theoretical guidance for safety analysis of LFR.

Comparison of Particle Image Velocimetry and Planar Laser-Induced Fluorescence Experimental Measurements and Numerical Simulation of Underwater Thermal Jet Characteristics

During the underwater movement of a submarine, cooling water at a specific temperature is discharged into the surrounding water through nuclear reactor secondary loop circulation, creating a thermal jet. Thermal jets are characterized by initial velocity and temperature properties that allow for complete mixing with the surrounding water through a combination of mixing and heat transfer processes. This paper aims to investigate the movement and diffusion of underwater thermal jets, specifically examining the temperature stratification of the ambient water, the initial velocity of the jet, and the effect of temperature on the velocity field and temperature field of the underwater thermal jet. This study utilizes particle velocity measurements and the laser-induced fluorescence method to measure the velocity field and temperature field of the thermal jet, as well as simulation methods to validate conclusions. The experimental and simulation conditions in this paper are mainly categorized into two types: uniform water body and thermally-stratified water body. Upon analysis and comparison of the experimental and simulation results, it has been observed that an increase in jet velocity will hinder the upward diffusion of jet temperature, decrease the floating height of the jet, and slow down the rate at which the jet temperature decays. Furthermore, as the difference between the jet temperature and the ambient water temperature increases, the upward diffusion of the jet temperature becomes predominant, resulting in a 40–50% increase in its floating rate. It is evident that the stratification conditions of the background environment have a significant impact on the jet temperature diffusion. When the jet temperature diffuses to the thermally-stratified interface of water in the tank, it ceases to float due to density differences; consequently, its temperature cannot diffuse further towards or reach the water surface.

Effects of the jet obstacle on flame acceleration and deflagration-to-detonation transition: A numerical perspective

As a new type of the detonation-promoting technology, the jet obstacle has attracted wide attention of researchers, but there are still many deficiencies in the current studies. Based on means of numerical analysis, the effects of jet velocity and the non-uniformity of the velocity distribution on flame acceleration and DDT (deflagration-to-detonation transition) processes are investigated in detail using the unsteady Reynolds average simulation method. The findings indicate that, with regard to flame acceleration, an increase in jet velocity will initially impede the acceleration of the flame to a certain extent. Nevertheless, the interaction between the flame and the jet gives rise to a complex multiple acceleration mechanism (such as the intensification of flow field perturbations within the channel, an augmented accumulation of premixed gases, an amplified virtual blocking effect, and an enlarged recirculation zone). This increased jet velocity serves to accelerate both the propagation of the flame and the detonation initiation process. The jet non-uniformity of the velocity distribution is also a vital factor to improve the DDT process. With the increase in the trend of non-uniformity changes in the jet velocity distribution (the continuous enhanced jets are used in this paper), the time and distance required for the detonation initiation of premixed gases are shortened. Furthermore, depending on the state of the shock wave, the detonation initiation processes in this paper all belong to the shock to detonation transition, which can be further classified into two categories: (I) detonation that induced by shock reflection; and (II) detonation that induced by shock focusing.

Oxidized Phospholipids and Calcific Aortic Valvular Disease

BackgroundOxidized phospholipids (OxPLs) are carried by apolipoprotein B-100–containing lipoproteins (OxPL-apoB) including lipoprotein(a) (Lp[a]). Both OxPL-apoB and Lp(a) have been associated with calcific aortic valve disease (CAVD). ObjectivesThis study aimed to evaluate the associations between OxPL-apoB, Lp(a) and the prevalence, incidence, and progression of CAVD. MethodsOxPL-apoB and Lp(a) were evaluated in MESA (Multi-Ethnic Study of Atherosclerosis) and a participant-level meta-analysis of 4 randomized trials of participants with established aortic stenosis (AS). In MESA, the association of OxPL-apoB and Lp(a) with aortic valve calcium (AVC) at baseline and 9.5 years was evaluated using multivariable ordinal regression models. In the meta-analysis, the association between OxPL-apoB and Lp(a) with AS progression (annualized change in peak aortic valve jet velocity) was evaluated using multivariable linear regression models. ResultsIn MESA, both OxPL-apoB and Lp(a) were associated with prevalent AVC (OR per SD: 1.19 [95% CI: 1.07-1.32] and 1.13 [95% CI: 1.01-1.27], respectively) with a significant interaction between the two (P < 0.01). Both OxPL-apoB and Lp(a) were associated with incident AVC at 9.5 years when evaluated individually (interaction P < 0.01). The OxPL-apoB∗Lp(a) interaction demonstrated higher odds of prevalent and incident AVC for OxPL-apoB with increasing Lp(a) levels. In the meta-analysis, when analyzed separately, both OxPL-apoB and Lp(a) were associated with faster increase in peak aortic valve jet velocity, but when evaluated together, only OxPL-apoB remained significant (ß: 0.07; 95% CI: 0.01-0.12). ConclusionsOxPL-apoB is a predictor of the presence, incidence, and progression of AVC and established AS, particularly in the setting of elevated Lp(a) levels, and may represent a novel therapeutic target for CAVD.

Numerical Analysis of the Cell Droplet Loading Process in Cell Printing.

Cell printing is a promising technology in tissue engineering, with which the complex three-dimensional tissue constructs can be formed by sequentially printing the cells layer by layer. Though some cell printing experiments with commercial inkjet printers show the possibility of this idea, there are some problems, such as cell damage due the mechanical impact during cell direct writing, which include two processes of cell ejection and cell landing. Cell damage observed during the bioprinting process is often simply attributed to interactions between cells and substrate. However, in reality, cell damage can also arise from complex mechanical effects caused by collisions between cell droplets during continuous printing processes. The objective of this research is to numerically simulate the collision effects between continuously printed cell droplets within the bioprinting process, with a particular focus on analyzing the consequent cell droplet deformation and stress distribution. The influence of gravity force was ignored, cell droplet landing was divided into four phases, the first phase is cell droplet free falling at a certain velocity; the second phase is the collision between the descending cell droplet and the pre-existing cell droplets that have been previously printed onto the substrate. This collision results in significant deformation of the cell membranes of both cell droplets in contact; the third phase is the cell droplet hitting a rigid body substrate; the fourth phase is the cell droplet being bounced. We conducted a qualitative analysis of the stress and strain of cell droplets during the cell printing process to evaluate the influence of different parameters on the printing effect. The results indicate that an increase in jet velocity leads to an increase in stress on cell droplets, thereby increasing the probability of cell damage. Adding cell droplet layers on the substrate can effectively reduce the impact force caused by collisions. Smaller droplets are more susceptible to rupture at higher velocities. These findings provide a scientific basis for optimizing cell printing parameters.

Liquid breakup and droplets behavior of free triple-impinging jets with different impinging distance

The breakup characteristics and droplet behavior of free triple-impinging jets (FTIJs) were investigated using a high-speed camera. The liquid sheet and droplets breakup mechanism, liquid sheet breakup length, width, droplet diameter and velocity, were studied under different jet velocity and horizontal impinging distance and perpendicular impinging distance. The results revealed that with increasing jet velocity from 1.42 m/s to 6.61 m/s, different breakup modes were observed: closed-rim mode, open-rim mode, rimless mode, and wave or ligament mode. At low jet velocities, increasing impinging distance delayed the development of breakup mode. Based on experimental observations, the sheet breakup mechanism is categorized into two main regimes with four subregimes. Droplet breakup occurs in two stages: growth and necking, however, at high jet velocities complete breakup was achieved. Increasing jet velocity led to an increase in liquid sheet breakup length, width, and droplet velocity but a decrease in droplet diameter. Conversely, increasing impinging distance resulted in a decrease in liquid sheet breakup width and droplet radial velocity but an increase in droplet diameter. The effect of perpendicular impinging distance on axial velocity and breakup length was found to be more significant than that of horizontal impinging distance due to the effect of perpendicular nozzle. The findings indicate that the perpendicular jet greatly enhances atomization. This study provides a theoretical basis for designing and optimizing FTIJs.

Prediction of interface morphology formed by the oblique gas jet impinging on a liquid surface

This study presents a theoretical analysis of the oblique gas jet impingement process on a liquid surface, elucidating the evolution of the flow field distribution and the influence of jet parameters on cavity shape dynamics. By integrating surface tension effects, the existing Blanks and Chandrasekhara model was refined to develop an advanced predictive model for cavity morphology. The theoretical framework was substantiated through numerical simulations and corroborated with experimental measurements of cavity dimensions, captured using state-of-the-art machine vision technology. The findings reveal a consistent trend in cavity dimension variations: an increase in the cavity surface width with the elevation of the impinging angle from the vertical and an escalation in gas jet velocity. Conversely, a reduction in the impinging angle coupled with an increase in jet velocity leads to a deeper cavity. To enhance the predictive accuracy, the model underwent iterative optimization, incorporating experimental data and accounting for jet parameters. The refined model demonstrated achieved a maximum error of 0.135 mm and a minimum error of 0.03 mm, providing reliable forecasts of cavity depth, which is pivotal for applications in fluid dynamics and related engineering fields.

Analysis of Surface Drag Reduction Characteristics of Non-Smooth Jet Coupled Structures

To enhance the service life of shipping equipment and minimize surface wear, this study employs biomimetic principles, integrating fitted structures with jet dynamics to model three configurations: non-smooth structures, single jet structures, and non-smooth jet-coupled structures. We utilized the SST k-ω turbulence model for numerical simulations to investigate the drag reduction characteristics of these structural models. By varying the jet angle and speed, we analyzed the changes in viscous resistance, pressure differential resistance, and drag reduction rates at the wall surface. Furthermore, the mechanisms of compressive stress, velocity fields, vortex structures, and shear stress on drag-reducing surfaces were elucidated, revealing how these factors contribute to drag reduction in non-smooth jet-coupled structures. The results indicate that the non-smooth jet-coupled structure exhibits superior drag reduction performance at a main flow field velocity of 20 m/s. As the jet velocity increases, the viscous drag on the surface of the non-smooth jet-coupled structure decreases, while the pressure differential drag increases. Conversely, variations in the jet angle have a minimal effect on viscous drag but lead to a reduction in pressure differential drag. Specifically, when the jet velocity is set at 1 m/s, and the jet angle is 60°, the drag reduction achieved by the non-smooth jet-coupled structure peaks at 7.48%. Additionally, the non-smooth jet-coupled structure features a larger area characterized by low shear stress, along with an increased boundary layer thickness at the bottom; this configuration effectively reduces surface velocity and consequent viscous drag.

Decay characteristics and application predictions of far-field high-pressure water: Jet velocity and volume fraction

In the field of deep mining engineering, high-pressure water jets progress toward larger diameters and higher velocities to enhance their impact performance. Understanding the decay characteristics as well as their implications remains challenging. In this article, the jet spread coefficients (k and c) within the empirical model of jet diffusion are determined by series of lab experiments, while simulations using the Eulerian method are conducted by implementing the modified diffusion model as a subroutine. The effects of spread coefficient, jet velocity, and nozzle diameter on the degree of jet decay are studied. The results show that the jet spread coefficient increases logarithmically with increasing jet velocity. With the increase in nozzle diameter, the growth of spread coefficient k of the jet gradually decreases. Increasing the nozzle diameter and spread coefficient k can effectively reduce the decay degree of jet axial velocity and water volume fraction. Notably, although the increase in jet velocity does not impact the decay of axial velocity, it exacerbates the decay of water volume fraction. Similarly, the increase in spread coefficient c has no effect on the reduction of water volume fraction, but it intensifies the decay of jet axial velocity. The combined effects of increased jet velocity and jet spread coefficient weaken the degree of jet decay. The research presents a comprehensive and innovative study of jet diffusion and attenuation phenomena. These insights not only expand the application of jet diffusion models but also provide theoretical support for understanding and optimizing the application of jets.

A comparative study on the premixed ammonia/hydrogen/air combustion with spark ignition and turbulent jet ignition

Turbulent jet ignition (TJI) is an advanced ignition mode that can enhance ignition and combustion performance, and it is a potential ignition strategy for ammonia/hydrogen internal combustion engines. This study aims to investigate the ignition and combustion characteristics of lean ammonia/hydrogen/air ignited by TJI, and the different ignition modes were compared. The results indicate that active TJI with auxiliary hydrogen injection in the pre-chamber improves the ignition and combustion performance of ammonia/hydrogen/air, and the appropriate shift of the pre-chamber equivalence ratio towards the rich side is considered optimal. As the ammonia fraction increases, the ignition mechanism in the main chamber changes from flame ignition to jet ignition. The advantage of TJI is mainly shown in high ammonia fraction mixtures, which is reflected in significantly lower ignition delay and combustion duration. In addition, TJI reduces the sensitivity of combustion to ammonia fraction compared to SI, due to the high ignition energy, initial flame area and turbulence provided by the hot jet. In TJI mode, the increase in jet velocity seems to be detrimental to the radial development of flames near the orifice, which may result in an increase in the duration of the final stage of combustion.

Experimental and numerical study on the formation and detachment of bubbles at orifices under the impinging jet flow

Three detachment patterns, i.e. single bubble pattern, double bubble pattern, atomizing pattern, are observed as the jet velocity increases. The bubble formation and detachment model are established, and the intensification mechanisms of the impinging jet on the bubble formation and detachment is revealed: Instantaneous flow field fluctuations changes the direction of the pressure difference force, forcing the bubble to detach and shortening the bubble growth time. The fluctuations of the flow field cause the total force on the bubble in the radial direction to be non-zero and the displacement of the bubble in the radial direction appears, which reduces the axial drag and the resistance of bubble to leave the orifice. In summary, under the effect of the impinging jet, the growth time of the bubble is shortened and the detachment size is reduced, which provides the possibility of producing small bubbles through large-diameter holes.

Experimental and model investigation of spreading characteristics of the liquid sheet formed by jet impinging on a circular plane

The focus of this paper is on the spreading characteristics of the liquid sheet formed by jet impinging on a circular plane. The liquid sheet is studied in two parts: the liquid film that spreads radially on the circular plane, and the free liquid sheet after leaving the circular plane, the former determines the initial thickness and velocity of the latter. Experimental results show that, for the liquid film on the circular plane part, as the jet velocity increases, the liquid film thickness increases due to the film velocity loss caused by the inelastic collision. The liquid film thickness is positively correlated with the jet radius and negatively correlated with the circular plane radius. Liquid viscosity slows the spreading of liquid film, forms the boundary layer, and thickens the liquid film. The surface tension inhibits the velocity loss due to the inelastic collision. For the free liquid sheet part, surface tension and gravity promote the bending of the liquid sheet. The larger the initial momentum of the liquid sheet leaving the circular plane, the larger the maximum spreading range of free liquid sheet reaching the equator. As for the theoretical model, a film velocity correction coefficient reflecting collision loss is introduced to improve the radial spreading theory of the liquid film on a solid surface, and a streamline function is assumed to solve the momentum integral equation of free liquid sheet. The predicted streamline agrees well with the experimental data.

Modelling the dynamics of microbubble undergoing stable and inertial cavitation: Delineating the effects of ultrasound and microbubble parameters on sonothrombolysis

Sonothrombolysis induces clot breakdown using ultrasound waves to excite microbubbles. Despite the great potential, selecting optimal ultrasound (frequency and pressure) and microbubble (radius) parameters remains a challenge. To address this, a computational model was developed to investigate the bubble behaviour during sonothrombolysis. The blood and clot were assumed to be non-Newtonian and porous, respectively. The effects of ultrasound and microbubble parameters on flow-induced shear stress on the clot surface during stable and inertial cavitation were investigated. It was found that microbubble translation towards the clot and the shear stress on the clot surface during stable cavitation were significant when the bubble was about to undergo inertial cavitation. While insonation of large microbubble (radius of 1.65μm) at low frequency (0.50 MHz) produced the highest shear stress during stable cavitation, selection of these parameters is not as intuitive for inertial cavitation due to the strong competing effect between jet velocity and translational distance. An increase in jet velocity is always accompanied by a decrease in the translational distance and vice versa. Therefore, a right balance between the jet velocity and the translational distance is critical to maximise the shear stress on the clot surface. A jet velocity of 303 m/s and a distance travelled of 5.12μm at an initial bubble-clot separation of 10μm produced the greatest clot surface shear stress. This is achievable by insonating a 0.55μm microbubble using 0.50 MHz and 600 kPa ultrasound.

Prediction of the Individual Aortic Stenosis Progression Rate and its Association With Clinical Outcomes

BackgroundThe progression rate of aortic stenosis differs between patients, complicating clinical follow-up and management. ObjectivesThis study aimed to identify predictors associated with the progression rate of aortic stenosis. MethodsIn this retrospective longitudinal single-center cohort study, all patients with moderate aortic stenosis who presented between December 2011 and December 2022 and had echocardiograms available were included. The individual aortic stenosis progression rate was calculated based on aortic valve area (AVA) from at least 2 echocardiograms performed at least 6 months apart. Baseline factors associated with the progression rate of AVA were determined using linear mixed-effects models, and the association of progression rate with clinical outcomes was evaluated using Cox regression. ResultsThe study included 540 patients (median age 69 years and 38% female) with 2,937 echocardiograms (median 5 per patient). Patients had a linear progression with a median AVA decrease of 0.09 cm2/y and a median peak jet velocity increase of 0.17 m/s/y. Rapid progression was independently associated with all-cause mortality (HR: 1.77, 95% CI: 1.26-2.48) and aortic valve replacement (HR: 3.44, 95% CI: 2.55-4.64). Older age, greater left ventricular mass index, atrial fibrillation, and chronic kidney disease were associated with a faster decline of AVA. ConclusionsAVA decreases linearly in individual patients, and faster progression is independently associated with higher mortality. Routine clinical and echocardiographic variables accurately predict the individual progression rate and may aid clinicians in determining the optimal follow-up interval for patients with aortic stenosis.

Numerical study on transport and deposition characteristics of particles associated with heat setting process in opposed jet flow field

The transport and deposition of particles accompanying the heat setting process in the opposed jet air supply system have a significant impact on the equipment safety. This paper used the Realizable k–ε model to simulate the flow field distribution of the impinging jet and the Lagrange method to track the trajectory of particles, by considering factors, such as jet velocity (7–13 m/s), oven temperature (413–473 K), and particle size (1–30 μ m ) changes, the instantaneous force process of particles was analyzed and their deposition mechanism was revealed. The numerical results have been well validated, with the root mean square error of within 10%. The results indicate that the flow field form of the opposed jet significantly affects particle placement on the surface of the air duct, the maximum turbulent vortex structure appears at the inlet of the air duct on both sides of the protruding nozzle, enhancing the capture of particles. Under the influence of gravity, the lower surface of the air duct becomes the main deposition surface, this phenomenon becomes more pronounced as the particle size increases and the maximum deposition rate difference between the upper and lower layers is 37%. The number of particles deposited on the rear end of the air duct is greater than that on the front end, and the deposition rate decreases with the increase in jet velocity. In the initial stage, a temperature gradient appeared in the machine room, which provided upward lift for the particles, resulting in more small diameter particles ( d p < 10 μ m ) depositing on the upper surface of the air duct. The results can provide theoretical support for the fire prevention and pollutant purification of equipment, such as heat setting machines.

Numerical investigation of the instability of dry granular bed induced by water leakage

AbstractUnderground pipe defects or cracks under transport infrastructure can cause water leakage to upper soil layers (e.g. subgrade and capping), inducing local cavities or even failure of overlying road/railway formation. Although numerous studies on the instability of granular beds induced by injected water have been conducted, most of them focused on the behaviour of saturated granular beds, while research on dry granular beds is still limited. This paper aims to address this gap using a numerical model coupling volume of fluid method with discrete element method. We observed that dry granular beds go through three distinct regimes as water jet velocity increases including stationary, stable deformation with heave and fluidisation. However, the flow velocities required to deform and fluidise dry granular beds are significantly higher than those required for saturated beds. Increasing granular bed thickness can alter its failure mechanism from full depth to localised erosion, leading to cavity formation around pipe cracks prior to the bed fluidisation. The gravitational and frictional components of granular mass are identified as two main resisting forces of dry granular beds against water jet force, evidenced by the increase of critical jet velocities as particle density and friction coefficient increase. Nevertheless, the moblised zone of granular mass is practically independent of both the buried depth of dry granular beds.

On the concrete breakage by pulsed water jet impact: Fracture characteristic, stress and damage evolution laws

To reveal the dynamic response characteristic and damage-fracture evolution laws of concrete under pulse water jet impact, the numerical simulations on pulse water jets impinging concrete for different operating parameters were established based on SPH-FEM coupling algorithm and verified in this paper. The concrete-breaking effects of pulse water jet and continuous water jet were compared, and the effects of key jet parameters and concrete strength on the damage-fracture characteristics of concrete were investigated. And the damage and stress evolution laws inner concrete were revealed. The results show that there is a better concrete-breaking effect for pulse water jet by repeatedly utilizing the extremely high water-hammer pressure and effectively weakening the water-cushion effect, compared with continuous water jet. The broken pit area and the total length of main cracks decrease with the increase of pulse length, and there is an optimal pulse spacing for pulse water jet to improve the concrete-breaking effect. The broken pit area and the total length of main cracks both linearly increase with the increasing jet velocity and exponentially increase with the increasing jet diameter. As the concrete strength increases, the broken pit area shows an S-shaped curve decreasing trend and the total length of main cracks exponentially decreases. The broken pit width first rapidly increases and tends to stabilize with the increase of jet velocity and concrete strength, and changes linearly with jet diameter and is less affected by pulse length and spacing. The farther away from the jet impact center, the longer the damage cumulative period of concrete due to the jet impact energy attenuation. In horizontal direction, concrete breakage range is approximately 4–5 times of jet diameter; in vertical direction, the previous pulses will cause concrete to be destroyed or damaged, and the subsequent pulses will make the damaged concrete suffer greater stress, causing more serve damage. And the induced stress peak decreases in form of Power function with the increasing distance. The research results could provide theoretical guidance for the parameters selection of pulse water jet efficiently breaking concrete.

Effect of Ribbed Target Plate on Impingement Cooling

This study experimentally investigates the heat transfer characteristics of an air jet impinging on smooth and ribbed target plates. Key variables examined include jet velocity, orifice diameter, and orifice-to-plate distance ratio (Z/D). Results show that the maximum heat transfer rate occurs at the stagnation point on the target plate. Increasing jet velocity significantly enhances heat transfer due to heightened turbulence, while larger orifice diameters yield higher heat transfer rates by covering a greater impact area. The optimal Z/D ratio for maximum heat transfer was determined to be 6 for all Reynolds numbers tested. However, introducing ribs to the target plate reduces heat transfer due to flow redirection and kinetic energy loss. These findings contribute to optimizing impingement cooling systems for various industrial applications.

Numerical simulation of jet impact process with different jet velocities in a negative pressure ambient

The effect of jet velocity on jet impingement process was of great importance. However, the process of jet impingement and fragmentation is highly complex and involves various physical and thermal phenomena. Therefore, our current work primarily focuses on using computational fluid dynamics (CFD) method to investigate the effect of jet velocity on the characteristics of jet impingement in a negative pressure ambient. The Realizable k-ε model is employed to simulate the turbulent flow process, and an improved Mixture model is used to describe the distribution behavior of the gas-liquid phases. The characteristics of flow field, pressure distribution, velocity distribution, turbulence kinetic energy distribution and vortex behavior were analyzed under different jet velocities at a negative pressure of 31.6 kPa. The results indicate that as the jet velocity increases, the core of jet impingement pressure also increases. The above situation resulted in fragment effect enhancement and an increased number of atomized droplets. These findings provide a theoretical basis for further research on the jet impingement-negative pressure deamination reactor (JI-NPDR).

Targeted Radiation Exposure Induces Accelerated Aortic Valve Remodeling in ApoE-/- Mice.

Thoracic radiation therapy may result in accelerated atherosclerosis and in late aortic valve stenosis (AS). In this study, we assessed the feasibility of inducing radiation-induced AS using a targeted aortic valve irradiation (10 or 20 Grays) in two groups of C57Bl6/J (WT) and ApoE-/- mice compared to a control (no irradiation). Peak aortic jet velocity was evaluated by echocardiography to characterize AS. T2*-weighted magnetic resonance imaging after injection of MPIO-αVCAM-1 was used to examine aortic inflammation resulting from irradiation. A T2* signal void on valve leaflets and aortic sinus was considered positive. Valve remodeling and mineralization were assessed using von Kossa staining. Finally, the impact of radiation on cell viability and cycle from aortic human valvular interstitial cells (hVICs) was also assessed. The targeted aortic valve irradiation in ApoE-/- mice resulted in an AS characterized by an increase in peak aortic jet velocity associated with valve leaflet and aortic sinus remodeling, including mineralization process, at the 3-month follow-up. There was a linear correlation between histological findings and peak aortic jet velocity (r = 0.57, p < 0.01). In addition, irradiation was associated with aortic root inflammation, evidenced by molecular MR imaging (p < 0.01). No significant effect of radiation exposure was detected on WT animals. Radiation exposure did not affect hVICs viability and cell cycle. We conclude that targeted radiation exposure of the aortic valve in mice results in ApoE-/-, but not in WT, mice in an aortic valve remodeling mimicking the human lesions. This preclinical model could be a useful tool for future assessment of therapeutic interventions.