Inflow Velocity Research Articles

A meso–micro atmospheric perturbation model for wind farm blockage

As wind farms continue to grow in size, mesoscale effects such as blockage and gravity waves become increasingly important. Allaerts & Meyers (J. Fluid Mech., vol. 862, 2019, pp. 990–1028) proposed an atmospheric perturbation model (APM) that can simulate the interaction of wind farms and the atmospheric boundary layer while keeping computational costs low. The model resolves the mesoscale flow, and couples to a wake model to estimate the turbine inflow velocities at the microscale. This study presents a new way of coupling the mesoscale APM to a wake model, based on matching the velocity between the models throughout the farm. This method performs well, but requires good estimates of the turbine-level velocity fields by the wake model. Additionally, we investigate the mesoscale effects of a large wind farm, and find that aside from the turbine forces and increased turbulence levels, the dispersive stresses due to subgrid flow heterogeneity also play an important role at the entrance of the farm, and contribute to the global blockage effect. By using the wake model coupling, we can explicitly incorporate these stresses in the model. The resulting APM is validated using 27 prior large-eddy simulations of a large wind farm under different atmospheric conditions. The APM and large-eddy simulation results are compared on both mesoscale and turbine scale, and on turbine power output. The APM captures the overall effects that gravity waves have on wind farm power production, and significantly outperforms standard wake models.

Design and Optimization of Microfluidic Vortex Diode

The performed research presents modeling results for designing microfluidic vortex diodes. These devices rectify fluid flow and can be used in many applications on micro and macro scales. The modeling, utilizing computational fluid dynamics (CFD) with the turbulence model RANS k-ε in COMSOL Multiphysics, has led to optimizing diodicity—the reversed-to-forward flow pressure drop ratio. The goal was to find the best flow-rectifying geometry within the 2D vortex-type design by changing the wall geometry, diode shape, and inflow velocities, identifying significant parameters and dependencies. Improving diodicity can be achieved by increasing the radius r1 of the central channel, increasing the entire diode radius r2, decreasing the width w of the rectangular channel, and reducing its length L. Additionally, changing the circular shape of the diode to an elliptical one can improve diodicity. The significance of this research is evident in the potential applications of these devices in microfluidic setups where fixed-geometry unidirectional flow is required, e.g., mixing, filtration, cell separation, and drug delivery, or on industrial scales, e.g., energy harvesting, wastewater treatment, and water sterilization.

Interaction between right atrial function reserve and liver stiffness after complete repair of tetralogy of fallot: a pilot study

Abstract Background Impaired right atrial mechanics is reported in patients with repaired tetralogy of Fallot (TOF) and is associated with liver stiffness. However, whether right atrial functional reserve correlates with liver stiffness is unknown. Purpose This study tested the hypothesis that right atrial reserve capacity is limited in patients with repaired TOF and explore its relationships with right ventricular function and liver stiffness. Methods 10 patients (45% male) aged 19.04 ± 3.76 at 16.70 ± 4.30 years after repair and 15 controls (60% male, aged 20.31 ± 1.25 years) were studied. RA mechanics was assessed by speckle-tracking echocardiography (STE) at rest and during bicycle exercise, with quantification of positive, negative, and total strain, and strain rates at ventricular systole (aSRs), early diastole (aSRed), and atrial contraction (aSRac). Right atrial function reserve (RAFR) is calculated as (∆RA total strain x [1-1/ RA total strain at baseline]). RV systolic and diastolic function was quantified using Doppler interrogation and STE. Hepatic shear wave velocity (c) and tissue elasticity (E) were measured using two-dimensional shear wave elastography. Results At rest, patients had significantly lower RA positive, negative and total strain, aSRs and aSRed than control subjects (all P<0.02). Shear wave velocity and hepatic E value were significantly higher in patients than controls (both P<0.02). Compared with controls, patients had significantly lower RA positive, negative and total strain, aSRs, aSRed, and aSRac at exercise (all P<0.05). No significant difference in hepatic shear wave velocity and tissue elasticity were found between patients and control subjects at exercise (all P>0.05). Both baseline liver stiffness indices correlated negatively with RAFR, RA positive and total strain and aSRed at exercise (p<0.05 for all). RV function parameters, including baseline trans-tricuspid early and late diastolic inflow velocity (E, A), systolic, early and late diastolic tricuspid annular velocity (s, e, a), isovolumetric acceleration (IVA), RV systolic and diastolic reserve correlated significantly with RA positive and total strain at exercise (P<0.05 for all). Conclusions In young adults with repaired TOF, right atrial function reserve is impaired, and is associated with increased liver stiffness and RV dysfunction.RA mechanics from rest to exerciseStress RA mechanics and liver stiffness

Short-term effects on sacubitril/valsartan therapy on right ventricle work and mechanics in patients with heart failure and reduced ejection fraction

Abstract Introduction In previous studies, sacubitril/valsartan (ARNI) therapy has been shown to have a positive effect on right ventricle (RV) function and on systolic pulmonary artery pressure in addition to improvement of left ventricle (LV) function in patients with heart failure and reduced ejection fraction (HFrEF). Recently, it was shown that a short-term ARNI therapy compared to valsartan-only therapy led to reduced systemic blood pressure and LV mechanical work, contributing to reduced LV myocardial perfusion and oxygen consumption. Purpose This paper aimed to study the effect of short-term ARNI therapy on RV mechanics and work and pulmonary and LV filling pressures compared to valsartan-only therapy in patients with HFrEF. Methods The study was a phase IV, prospective, randomized, double-blind, parallel-group study in patients with NYHA class II–III heart failure and LV ejection fraction (LVEF) <= 35 %. During a 6-week run-in period, all patients received valsartan therapy, which was up-titrated to the highest tolerated dose level (80 mg bid or 160 mg bid) and then randomized to either valsartan or sacubitril/valsartan. Myocardial oxygen consumption, energetic efficiency of cardiac work, and cardiac and systemic hemodynamics were quantified using echocardiography and 11C-acetate PET before and after 6 weeks of therapy (on stable dose) in 55 patients. The analyses were done with ANCOVA adjusting for pre-randomization values. Results The RV myocardial resting perfusion (mean difference of 0.056 (95% CI, 0.02 to 0.109) ml/g/min, p = 0.041) and RV myocardial oxygen consumption (0.005 (0.001 to 0.010) 1/min, p = 0.015) were significantly lower in the ARNI group compared with the valsartan-only group. The left atrial end-diastolic volume indexed to body surface area (geometric mean difference of 1.071 (95% CI, 0 to 1.148) ml/m2, p = 0.048) and the ratio of early mitral inflow velocity to medial mitral annular early diastolic velocity (mean difference of 2.467 (95% CI, 0.096 to 4.838), p = 0.042) were also significantly lower in the ARNI group compared with the control group. There was no difference between the groups in peak systolic right ventricle to right atrial pressure gradient. Still, the tricuspid annular plane systolic excursion was significantly higher in the valsartan-only group compared with the ARNI group (0.221 (0.039 to 0.404) cm, p = 0.018). There was no difference in RV free wall strain, fractional area change or systolic excursion velocity between the treatment arms (p> 0.262). Conclusions In addition to our earlier findings, sacubitril when added to valsartan appears to reduce also right ventricle myocardial perfusion and oxygen consumption. There was also a reduction in left atrial end-diastolic volume and in early mitral inflow to medial mitral annular early diastolic velocity in the sacubitril/valsartan group as compared to the valsartan-only group, which suggest decreased LV filling pressure.

Analysis of aerodynamic characteristics of drone wing based on CFD

In order to improve the aerodynamic characteristics of the drone wings, CFD method was used to simulate and calculate the lift coefficient, drag coefficient, and lift-drag ratio under different relative inflow velocities, as well as the velocity and pressure fields under different attack angles. Modal calculations were conducted on the wing to obtain the first four modal shapes, providing a basis for analyzing flutter characteristics. An iterative calculation method of incompressible potential flow-boundary layer based on surface element method was combined with the software XFOIL to optimize the airfoil at low wind speeds. The results indicate that the airfoil is susceptible to stall at high angles of attack, with the pressure of the separation flow being nearly equivalent to that at the separation point. Subsequent to separation, there is an increase in differential pressure resistance, resulting in a marked rise in the drag coefficient. At the optimized angle of attack, the lift-drag ratio of the optimized wing increases by 12.58 %, while there is a decrease of 0.084 % in lift coefficient and an increase of 11.21 % in drag coefficient.

Rotor noise in non-axial inflow conditions

This paper presents an experimental study on characterising the aerodynamic and far-field acoustic performance of rotors operating in non-axial inflow conditions. The current experiments were carried out with a two-bladed rotor, operating with a tip Mach number of 0.56, approaching the practical tip Mach numbers expected of urban air mobility vehicles. Synchronous measurements of the aerodynamic force, far-field acoustics and blade phase angle were undertaken to provide insights on both the time-averaged and phase-averaged correlation between the rotor aerodynamic loading and the emitted noise. The far-field acoustic spectra are compared across a range of advance ratios (0.01≤μ≤0.04) and forward tilting angles (0°≤α≤30°). When the inflow velocity increases, both the tonal and broadband components increase. Moreover, higher harmonics of the blade passing frequency are observed to become more prominent at higher advance ratios. As the rotor tilts forward from edgewise flight conditions, the broadband noise component reduces significantly, with the tones at fundamental blade passing frequency and higher harmonics also reducing in magnitude, agreeing well with the steady and unsteady thrust coefficients measured. From the aerodynamic loading, acoustic spectra and the directivity results, a transition from near-edgewise to near-axial modes of operation can be discerned at a tilt angle of approximately 16°. More interestingly, the phase-averaged thrust and acoustic power results show notable variations of the blade loading and acoustic emission through one full rotor rotation. At higher advance ratios and shallow tilting angles, the phase location of peaks in the root-mean-square of the fluctuating thrust coefficient agrees very well with those from the acoustic power, suggesting a strong correlation between the flow unsteadiness and the noise at these non-axial conditions, contributing to higher overall sound pressure levels.

Subtle echocardiographic markers of CAD: looking beyond the LV ejection fraction in stable angina patients.

A routine echocardiogram aims at identifying only regional wall motion abnormality (RWMA) or left ventricle diastolic dysfunction (LVDD) for coronary artery disease (CAD). When absent, a study is often labeled "normal." This creates an unmet need to identify and add subtle markers of CAD to the routine echocardiogram to increase the diagnostic yield. Left ventricle (LV) systolic and diastolic parameters, along with left atrium (LA) strain parameters, were assessed using echocardiography in one hundred three patients of stable angina undergoing coronary angiography and compared with their SYNTAX score-II (SS-II). The left ventricle global longitudinal strain (LV-GLS) and LA Volume indexed (LAVi) did not correlate significantly with the SS-II. The LA filling pressures reflected by the ratio of early mitral inflow velocity with early mitral annular velocity (E/e`), however, increased significantly with SS-II, with a cut-off value >10.39 for significant CAD (pvalue <0.001). The LA reservoir function parameters, peak atrial longitudinal strain (PALS), and peak global systolic strain rate (LAsSR) decreased significantly with increasing SS-II (p values of 0.011 and 0.001, respectively). The values < 23.56 for PALS and less than 1.15 for LAsSR, showed a significant association with CAD. The LA conduit function parameter, peak global early diastolic strain rate (LAeSR), also increased significantly with increasing SS-II (p-value <0.001), with values > 1.09 having a good correlation with CAD. Besides RWMA and LV-GLS, the LV diastolic and LA strain parameters can be potential echocardiographic markers for CAD in stable angina patients.

Simulation of a Tidal Current-Powered Freshwater and Energy Supply System for Sustainable Island Development

Sustainable development of islands cannot be achieved without the use of renewable energy to address energy and freshwater supply issues. Utilizing the widely distributed tidal current energy in island regions can enhance local energy and water supply security. To achieve economic and operational efficiency, it is crucial to fully account for the unique periodicity and intermittency of tidal current energy. In this study, a tidal current-powered freshwater and energy supply system is proposed. The marine current turbine adopts a direct-drive configuration and will be able to directly transfer the power of the turbine rotation to the seawater pump to improve the energy efficiency. Additionally, the system incorporates batteries for short-term energy storage, aimed at increasing the capacity factor of the electrolyzer. A simulation is conducted using measured inflow velocity data from a full 12 h tidal cycle. The results show that the turbine’s average power coefficient reaches 0.434, the electrolyzer’s average energy efficiency is 60.9%, the capacity factor is 70.1%, and the desalination system’s average specific energy consumption is 6.175 kWh/m3. The feasibility of the system design has been validated.

Noise and inflow velocity measurements of fixed pitch rotors in edgewise flight

A common design of many of the proposed generation of electric Vertical Takeoff and Landing (eVTOL) vehicles involves fixed pitch rotors in edgewise flight. These applications typically have significantly lower tip Mach numbers than conventional rotor-craft and involve distributed smaller rotors making them operate at lower Reynolds numbers and hence likely having a greater sensitivity to gusts and environmental turbulence. This work will present results of studies with fixed pitch rotors conducted in the UF Anechoic Wind Tunnel Facility. The studies involve radiated noise, thrust and stereoscopic Particle Image Velocimetry to measure the inflow velocity to the rotor plane. The measurements were taken for un-altered free stream conditions as well as ones subjected to three different turbulence generation grids. The results provided show that there can be effects at moderate levels of free stream to turbulence to the rotor efficiency and radiated noise.

Prevalence and characteristics of minimal pleural fluid on screening chest MRI

BackgroundMinimal pleural fluid is often seen incidentally on chest MRI. However, its prevalence and clinical characteristics remain unknown. MethodsThis retrospective observational study included 2726 participants who underwent comprehensive medical check-ups for screening, including chest CT and MRI, and transthoracic echocardiography between March 2018 and February 2019. Pleural fluid on MRI was manually measured for maximum thickness. Its distribution, change over time, and relevance to participant characteristics were analyzed. The pulmonary function data of 82 participants and their associations with fluid were also analyzed. ResultsOf the 2726 participants (mean age ± standard deviation, 59 ± 11 years), 2009 (73.7%) had minimal pleural fluid (thickness, 1–9 mm) on either side, with right-sided fluid being more frequent than left-sided fluid (P < 0.001). Negligible changes in fluid thickness were observed one year later. The following parameters were associated with less fluid: age, ≥65 years (P < 0.001); male sex (P = 0.006); current smoking (P < 0.001); body mass index, ≥25 kg/m2 (P < 0.001); and mean arterial pressure, ≥100 mmHg (P = 0.01), whereas a ratio between early mitral inflow velocity and mitral annular early diastolic velocity>14 was associated with more fluid (P = 0.01). The presence of fluid was an independent explanatory variable for a higher percentage of predicted vital capacity (P = 0.048). ConclusionsMRI was highly sensitive in detecting minimal pleural fluid. Pleural fluid found on MRI for health screening was assumed to be physiological and fluid thickness at the steady state might be variable among participants depending on age, sex, smoking habits, body shape, blood pressure, and cardiac diastolic capacity.

Wake-induced vibration of ultra-long suspenders adjacent to bridge tower

The tower wake usually induces large-amplitude vibrations in adjacent suspenders of a long-span suspension bridge. In order to interpret the underlying mechanism of the significant wake-induced vibrations of ultra-long suspenders, the wake-induced vibration characteristics of tandem suspenders beside the bridge tower are investigated using computational fluid dynamics based simulation. First, the computational model of the bridge tower and suspenders is established. Subsequently, the effect of tower wake on suspender vibration is analyzed considering the inflow velocity and relative position between the tower and suspenders. Based on the proper orthogonal decomposition (POD), the flow characteristics behind the tower and around the suspenders are investigated, and the governing mechanism of wake-induced vibrations of the suspenders is revealed ultimately. The results indicate that the wake-induced vibration of the suspender exhibits a lock-in phenomenon with large cross-wind amplitudes at specific incoming wind velocities. The wind loads on the suspender in both along-wind and cross-wind directions exhibit components with frequencies that are multiples of the vortex shedding frequency. The flow field can be accurately constructed using the first four POD modes with the largest energy. The symmetric POD modes are the primary components that contribute to the significant wake-induced vibrations of the suspenders.

Study on the maximum ceiling temperature and downstream temperature distribution in inclined tunnel fire

Constrained by various factors, including terrain, tunnels frequently exhibit slopes. While existing research on fires in inclined tunnels predominantly focuses on the characteristics of smoke flow in large slope tunnels, there is a notable lack of attention given to the study of micro-slope tunnels and important factors such as induced air inflow. Therefore, in this paper, the numerical simulation method is used to study the maximum ceiling temperature rise and downstream temperature distribution in inclined tunnel fire under the conditions of micro-slope and large slope. The results show that the main factors affecting the ceiling temperature rise are not only the tunnel slope, but also the HRR and the downstream length. These effects can be expressed by the stack effect intensity. When the inclined tunnel fire occurs, the maximum ceiling temperature and the downstream temperature distribution characteristics show two states. When the stack effect in the tunnel is diminished, there is no significant alteration in the maximum ceiling temperature and temperature distribution within the tunnel when compared to a horizontal tunnel. In a tunnel with a strong stack effect, the maximum temperature decreases as the stack effect increases, and the temperature distribution differs greatly from a horizontal tunnel. The theoretical analysis of this paper identifies the demarcation point of the two state changes as the dimensionless induced air inflow velocity of 0.1. On this basis, a piecewise prediction model for the maximum ceiling temperature of the inclined tunnel fire is established. Because the temperature distribution between the fire source and the maximum temperature position is not regular. Thus, using the maximum ceiling temperature as a reference point, an accurate segmented prediction model of temperature distribution is proposed for downstream Region 1. This study offers guidance for designing tunnel structures with high-temperature resistance and assessing safety conditions within the tunnel.

Pericardial tamponade: a new perspective on echocardiographic features and application of a prediction score.

Few clinical decision rules have been used to guide clinical management and predict outcomes in patients with pericardial tamponade. The objectivesof this study are to identify the echocardiographic features associated with adverse outcomes in patients with pericardial effusions requiring pericardiocentesis and to apply a previously described four-point clinical and echocardiographic score to predict clinical outcomes over 24-hr, 30-day, and 1-year intervals. We performed a retrospective cohort review of patients who had transthoracic echocardiogram (TTE) performed and underwent pericardiocentesis within 48h of emergency department presentation at two large tertiary care institutions. We constructed different stepwise logistic regression models and examined the associations of TTE characteristics and clinical features with ICU admission, hospital length of stay (h-LOS), and survival. The data set was then employed against a previously proposed scoring system to predict factors associated with clinical outcomes over 24hr, 30days, and 1year. Two hundred thirty-nine patients were included in the final analysis. Echocardiographic characteristics of patients with pericardial tamponade who underwent pericardiocentesis are as follows: 69.1% right ventricular (RV) diastolic collapse, 62.3% exaggerated mitral valve (MV) inflow velocities, 56.4% inferior vena cava (IVC) plethora, and 53.4% right atrial (RA) systolic collapse. Increase in systolic blood pressure and increased variation in MV inflow velocity were associated with reduced ICU admission [OR: 0.94 (CI 0.90, 0.99), 0.28 (CI 0.09, 0.89), respectively]. In addition, a history of malignancy increased the length of hospital stay by about 3.89days (CI 1.43-6.35, p < 0.01) and prior pericardiocentesis history was associated with 4.82-day increase in hospital stay (CI 1.19-8.45, p = 0.01). In utilizing the previously published prediction score, we found no statistically significant correlation in predicting survival. RV diastolic collapse and exaggerated MV inflow velocity were the most common echocardiographic findings in patients requiring pericardiocentesis. Contrary to prior studies, exaggerated MV inflow velocity was associated with reduced ICU admission. In addition, a previously described prediction score did not correlate with decreased survival in this cohort.

Diastolic Stress Echocardiography in Patients With Hypertrophy Cardiomyopathy: Association With Exercise Capacity

Diastolic dysfunction plays a major role in precipitating congestive heart failure (CHF) in hypertrophic cardiomyopathy (HCM) patients. In many such patients, symptoms are unmasked only during exercise, as left ventricular (LV) filling pressure is normal at rest but increase with exercise. We sought to establish if abnormal post-exercise diastolic parameters are associated with reduced exercise capacity in patients with HCM. We examined 590 asymptomatic/minimally symptomatic HCM patients (54±14 years, 57% men, body mass index 30±6 kg/m2, 84% on betablockers) with HCM by two-dimensional and Doppler echocardiography at rest and following maximal treadmill exercise echocardiography (TSE). A complete echocardiogram (including LV ejection fraction, LV thickness, LV outflow tract [LVOT] gradient, degree of mitral regurgitation [MR]) was recorded. Diastolic parameters (septal and lateral [e’] velocities of the mitral annulus, peak early [E] and late [A] mitral inflow velocity, E/A ratio, E/e’, right ventricular systolic pressure [RVSP] and left atrial volume index [LAVI]) were recorded at rest and post-TSE. Exercise functional capacity was recorded and divided into <85% or >85% of age-gender predicted metabolic equivalents (AGP-METs). Following maximal exercise, 32% patients had at least moderate MR, mean LVOT gradient was 61±59 mmHg, E/A ratio was 1.2± 1.0, average E/e’ ratio 12.9±1.0 and peak RVSP was 36±15 mm Hg. Only 42% patients achieved >85% of AGP-METs; mean Mets were 7±3. On multivariable logistic regression analysis, higher body mass index (odds ratio [OR] 1.05), betablocker use (OR 2.58), higher LAVI (OR 1.02), higher peak-stress LVOTG (OR 1.06), peak-stress E/e’ (OR 1.04) and higher RVSP (OR 1.03) were independently associated with <85% AGP-METs achieved (all p<0.05). In conclusion, in asymptomatic/minimally symptomatic patients with HCM undergoing TSE, there is a significant and independent association between abnormal diastolic response to exercise and reduced exercise capacity in HCM. Incorporating diastolic parameters during stress echocardiography could provide incremental diagnostic utility in deciphering the exact etiology of dyspnea in such patients.

Effect of Semaglutide on Cardiac Structure and Function in Patients With Obesity-Related Heart Failure

BackgroundObesity is associated with adverse cardiac remodeling and is a key driver for the development and progression of heart failure (HF). Once-weekly semaglutide (2.4 mg) has been shown to improve HF-related symptoms and physical limitations, body weight, and exercise function in patients with obesity-related heart failure with preserved ejection fraction (HFpEF), but the effects of semaglutide on cardiac structure and function in this population remain unknown. ObjectivesIn this echocardiography substudy of the STEP-HFpEF Program, we evaluated treatment effects of once-weekly semaglutide (2.4 mg) vs placebo on cardiac structure and function. MethodsEchocardiography at randomization and 52 weeks was performed in 491 of 1,145 participants (43%) in the STEP-HFpEF Program (pooled STEP-HFpEF [Semaglutide Treatment Effect in People with Obesity and HFpEF] and STEP-HFpEF DM [Semaglutide Treatment Effect in People with Obesity, HFpEF, and Type 2 Diabetes] trials). The prespecified primary outcome was change in left atrial (LA) volume, with changes in other echocardiography parameters evaluated as secondary outcomes. Treatment effects of semaglutide vs placebo were assessed using analysis of covariance stratified by trial and body mass index, with adjustment for baseline parameter values. ResultsOverall, baseline clinical and echocardiographic characteristics were balanced among those receiving semaglutide (n = 253) and placebo (n = 238). Between baseline and 52 weeks, semaglutide attenuated progression of LA remodeling (estimated mean difference [EMD] in LA volume, −6.13 mL; 95% CI: −9.85 to −2.41 mL; P = 0.0013) and right ventricular (RV) enlargement (EMD in RV end-diastolic area: −1.99 cm2; 95% CI: −3.60 to −0.38 cm2; P = 0.016; EMD in RV end-systolic area: −1.41 cm2; 95% CI: −2.42 to −0.40] cm2; P = 0.0064) compared with placebo. Semaglutide additionally improved E-wave velocity (EMD: −5.63 cm/s; 95% CI: −9.42 to −1.84 cm/s; P = 0.0037), E/A (early/late mitral inflow velocity) ratio (EMD: −0.14; 95% CI: −0.24 to −0.04; P = 0.0075), and E/e′ (early mitral inflow velocity/early diastolic mitral annular velocity) average (EMD: −0.79; 95% CI: −1.60 to 0.01; P = 0.05). These associations were not modified by diabetes or atrial fibrillation status. Semaglutide did not significantly affect left ventricular dimensions, mass, or systolic function. Greater weight loss with semaglutide was associated with greater reduction in LA volume (Pinteraction = 0.033) but not with changes in E-wave velocity, E/e′ average, or RV end-diastolic area. ConclusionsIn the STEP-HFpEF Program echocardiography substudy, semaglutide appeared to improve adverse cardiac remodeling compared with placebo, further suggesting that treatment with semaglutide may be disease modifying among patients with obesity-related HFpEF. (Research Study to Investigate How Well Semaglutide Works in People Living With Heart Failure and Obesity [STEP-HFpEF]; NCT04788511; Research Study to Look at How Well Semaglutide Works in People Living With Heart Failure, Obesity and Type 2 Diabetes [STEP-HFpEF DM]; NCT04916470)

Impaired left ventricular function in lean women with PCOS: Insights from speckle tracking echocardiography

Aims: We aimed to conduct a study examining left ventricular function (LVEF) in lean women PCOS patients with speckle tracking echocardiography. Methods: The study included 60 patients diagnosed with PCOS and 30 healthy controls matched for age and body mass index. Morning fasting blood samples were collected to measure levels of glucose, insulin, high-sensitivity C-reactive protein (hs-CRP), and lipids. Left ventricular function (LVF) was evaluated using two-dimensional speckle tracking echocardiography (2D-STE) and real-time three-dimensional echocardiography (3D-Echo). Global strain was assessed from three standard apical views using 2D-STE. Results: The hs-CRP levels in lean women with PCOS were significantly higher compared to the control group (2.34±1.07 vs. 1.13±0.54; p=0.01). The peak longitudinal strain values in the 2-chamber, 4-chamber, and long-axis views were lower in lean women with PCOS compared to the control group (15.9±1.2 vs. 19.4±1.2; p=0.01, 17.0±1.1 vs. 19.2±1.4; p=0.01, 16.3±1.3 vs. 19.2±1.5; respectively, p=0.01). According to the multiple regression model, global strain was independently associated with hs-CRP (β=0.31, p=0.04), the ratio of early diastolic mitral inflow velocity (E) to early diastolic annular velocity (E/E’ ratio) (β=0.33, p=0.01), and ejection fraction (EF) (β=0.35, p=0.01). Conclusion: Our findings reveal that lean women with PCOS exhibit significantly higher levels of high-sensitivity C-reactive protein (hs-CRP) compared to healthy controls. Furthermore, the peak longitudinal strain values across multiple cardiac views were notably lower in the PCOS group, suggesting impaired left ventricular function. These results highlight the importance of monitoring cardiovascular health in lean women with PCOS, as they are at an increased risk of developing left ventricular dysfunction despite their lean body mass index.

Experimental investigation on an innovative serpentine channel‐based nanofluid cooling technology for modular lithium‐ion battery thermal management

AbstractMany nations have committed to becoming carbon neutral by 2050 as a means of addressing the global warming challenge. To achieve carbon neutrality, transportation is one of the most essential and important tasks. Energy‐efficient pure electric vehicles (EVs) and hybrid electric vehicles (HEVs) with green energy power are being developed in response to the worldwide energy and environmental crises, as the potential replacements for the current generation of combustion‐engine automobiles. EVs require batteries more than ever before. In this perspective, lithium‐ion batteries (LIBs) stand out as remarkable energy storage technologies and have been widely used due to their numerous impressive benefits. Owing to LIBs sensitivity to temperature, EVs typically use the battery thermal management system (BTMS). The working temperature span of a lithium‐ion battery in an electric car is 15°C–35°C, which is achieved by the use of a BTMS. The production of internal heat during charging and discharging also affects how well lithium‐ion batteries work. A battery heat control system is therefore required. The temperature of the LIB pack might be efficiently controlled by liquid‐cooled systems in discharge and charge scenarios. Based on Al2O3 nanofluid (NF), the current experimental study suggests a novel active cooling technology for regulating the heat produced by the 18650‐format lithium‐ion batteries. A thorough analysis is conducted on the impact of charge/discharge C‐rates, Al2O3 nanoparticle (NP) volume fractions, inflow coolant velocity, and intake liquid temperature on the thermal efficiency of the LIB pack. By incorporating aluminum oxide NPs into the water at varying volume fractions of 0.3%, 0.5%, and 1%, the LIB pack's maximum temperature was significantly reduced by 7.9%, 18.09%, and 19.56%, respectively. With increase in mass flow rate of coolant from 0.0290 to 0.5810 kg/s, the maximum temperature has been substantially reduced by 3.7%–8.6%. Results show that using higher fluid inflow temperature significantly increased both the highest experienced temperature and temperature diversity throughout the discharge operation by about, 6°C and 5°C, respectively. The outcomes of the study indicate that NFs exhibit superior cooling performance compared to conventional coolants such as water and ethylene glycol.

Left atrial appendage emptying velocity and left ventricular function as predictors of inotropic support in patients undergoing elective off-pump coronary artery bypass grafting

Abstract Background: Patients undergoing elective off-pump coronary artery bypass grafting (CABG) are at risk of hemodynamic instability, ischemia, arrhythmia, and dysfunction. These events need to be managed by pharmacological supports or relieving of mechanical obstruction (octopus) of the heart to maintain the hemodynamic stability. There is a paucity of data on the effect of left ventricular (LV) dysfunction on left atrial appendage (LAA) emptying velocity. We evaluated the relationship between LV function and LAA emptying velocity and requirement of inotropic support perioperatively. Materials and Methods: In this prospective open-label all-comer study, fifty patients undergoing elective off-pump CABG under general anesthesia, we measured LAA emptying velocity by pulsed wave Doppler and evaluated if it could predict the need for inotropes perioperatively. It is a case series of 50 patients without a comparator arm. We measured pulsed wave Doppler across the mitral valve leaflet and early mitral inflow velocity (Evel) and late mitral inflow velocity, tissue Doppler at the lateral annulus of the mitral valve (e’) and also calculated the ratio of Evel and e’. Need for inotrope in the intraoperative and postoperative period was captured perioperatively. Vasoactive-inotropic score (VIS) was calculated for all the patients. Results: The VIS was significant (P &lt; 0.0001, with odds ratio of 131.6 and confidence interval of 95% (0.9–1). However, there was no significant correlation between ejection fraction (EF) and VIS (P = 0.87). In patients with the need of inotropes, LAA emptying velocity was significantly increased in the postgrafting period as compared to the pregrafting period (75.64 cm/s vs. 57.9 cm/s, P &lt; 0.001). Conclusion: The assessment of LAA emptying velocity value was a useful predictor of the need of inotropic support during off-pump surgery, especially during Obtuse marginal and Ramus grafting. This study paves the need of larger case–control studies to validate the findings.

Sodium-dependent glucose transporter 2 inhibitors effects on myocardial function in patients with type 2 diabetes and asymptomatic heart failure.

Sodium-dependent glucose transporter 2 inhibitors (SGLT2i) have shown efficacy in reducing heart failure (HF) burden in a very heterogeneous groups of patients, raising doubts about some contemporary assumptions of their mechanism of action. We previously published a prospective observational study that evaluated mechanisms of action of SGLT2i in patients with type 2 diabetes who were in HF stages A and B on dual hypoglycemic therapy. Two groups of patients were included in the study: the ones receiving SGLT2i as an add-on agent to metformin and the others on dipeptidyl peptidase-4 inhibitors as an add-on to metformin due to suboptimal glycemic control. To evaluate the outcomes regarding natriuretic peptide, oxidative stress, inflammation, blood pressure, heart rate, cardiac function, and body weight. The study outcomes were examined by dividing each treatment arm into two subgroups according to baseline parameters of global longitudinal strain (GLS), N-terminal pro-brain natriuretic peptide, myeloperoxidase (MPO), high-sensitivity C-reactive protein (hsCRP), and systolic and diastolic blood pressure. To evaluate the possible predictors of observed changes in the SGLT2i arm during follow-up, a rise in stroke volume index, body mass index (BMI) decrease, and lack of heart rate increase, linear regression analysis was performed. There was a greater reduction of MPO, hsCRP, GLS, and blood pressure in the groups with higher baseline values of mentioned parameters irrespective of the therapeutic arm after 6 months of follow-up. Significant independent predictors of heart rate decrease were a reduction in early mitral inflow velocity to early diastolic mitral annular velocity at the interventricular septal annulus ratio and BMI, while the predictor of stroke volume index increase was SGLT2i therapy itself. SGLT2i affect body composition, reduce cardiac load, improve diastolic/systolic function, and attenuate the sympathetic response. Glycemic control contributes to the improvement of heart function, blood pressure control, oxidative stress, and reduction in inflammation.

Experimental study and mathematical modeling of the pectinases production by Aspergillus flavipes FP-500 in an airlift bioreactor

Mathematical models are indispensable for designing, optimizing, and controlling large-scale bioprocesses. In the present work, the production of pectinases was studied experimentally using an internal loop airlift bioreactor, pectin as a substrate, and Aspergillus flavipes FP-500 as a biocatalyst. The N-tanks-in-series (NTIS) model was implemented to predict the behavior of fungal growth, pectin and dissolved oxygen consumption, pectinases production, and the oxygen mass transfer rate from gas phase to liquid culture medium. A double Monod-Logistic kinetic model was used to describe the biomass growth rate as a function of biomass, pectin, and dissolved oxygen concentrations. In contrast, a Luedeking-Piret kinetic model was used to describe the production rate of endo and exo pectinases. A hydrodynamic model was utilized to estimate gas hold-ups, volumetric mass transfer coefficients, and air inflow velocities. Good agreement was observed between the experimental data and the theoretical results, demonstrating the predictive capacity of the NTIS model to describe pectinase production, the oxygen consumption rate, and the oxygen evolution in the gas phase. The model highlighted its robust capability to capture the critical parameters of aerobic fermentation processes. Therefore, it could be used as a tool for the scalability of the airlift bioreactors.