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Purpose: Non‐contrast‐enhanced time of flight (TOF) is a standard method for magnetic resonance angiography used to depict vessel morphology. TOF is commonly performed with a 3D steady‐state acquisition, employing a short repetition time to support high resolution imaging. At 7 T, TOF exhibits substantial increase in SNR and contrast, improving its clinical value. However, one of the remaining challenges, exacerbated at 7 T, is the presence of artifacts due to pulsatile blood flow, especially near major blood vessels. In this study we examine a method to significantly reduce these artifacts. Methods: We recently introduced a new "local‐scrambling" approach that semi‐randomizes the acquisition order of the phase encodes, to achieve a controllable cutoff frequency above which the artifacts are drastically reduced. With this approach, artifacts resulting from fast local fluctuations such as cardiac pulsation are significantly reduced. In this study, we explore the ability of this local‐scrambling approach to reduce pulsatile blood flow artifacts in a 3D TOF acquisition. Cartesian line‐by‐line and center‐out ordering, with and without local‐scrambling, were compared in simulations and in human brain imaging at 3 and 7 T scanners. Results: In the simulations the artifact intensity showed a 10‐fold reduction using local‐scrambling compared to line‐by‐line and 4‐fold compared to center‐out ordering. In vivo results show that artifacts are much more pronounced at 7 T compared to 3 T, and in both cases they are effectively reduced by local‐scrambling. Conclusion: Local‐scrambling improves image quality for both line‐by‐line and center‐out ordering. This approach can easily be implemented in the scanner without any changes to the reconstruction. [ABSTRACT FROM AUTHOR]

Background Methods Results Conclusion This study evaluated the hemodynamic performance of arterial and venous cannulae in a compliant pediatric extracorporeal membrane oxygenation (ECMO) mock circuit in pulsatile and non‐pulsatile flow conditions.The ECMO setup consisted of an oxygenator, diagonal pump, and standardized‐length arterial/venous tubing with pressure transducers. A validated left‐heart mock loop was adapted to simulate pediatric conditions. The pulsatile flow was driven by a computer‐controlled piston pump set at 120 bpm. A roller pump was used for non‐pulsatile conditions. The circuit was primed with 40% glycerol‐based solution. The cardiac output was set to 1 L/min and the aortic pressure to 40–50 mmHg. Four arterial cannulae (8Fr, 10Fr, 12Fr, 14Fr) and five venous cannulae (12Fr, 14Fr, 16Fr, 18Fr, 20Fr) (Medtronic, Inc., Minneapolis, MN, USA) were tested at increasing flow rate in 12 combinations.The pulsatile condition required lower ECMO pump speeds for all cannulae combinations at a given flow rate, inducing a significantly smaller increase of flow in the mock loop. Under non‐pulsatile conditions, the aortic and arterial pressures in the cannulae were higher (p < 0.01) while no significant differences in pressure drop and pressure‐flow characteristics (M‐number) were observed. The total hemodynamic energy was higher in case of non‐pulsatile flow (p < 0.01).Under non‐pulsatile conditions, the system was characterized by overall higher pressures, resulting in higher support to the patient. The consequent increase of potential energy compensates for increases of kinetic energy, leading to a higher total hemodynamic energy. Pressure gradients and M number are independent of the testing conditions. Pulsatile testing conditions led to more physiological testing conditions, and it is recommended for ECMO testing. [ABSTRACT FROM AUTHOR]

As the main prerequisite for flow in microfluidic chips, micropumps have always been the core component of microfluidic systems. With the continuous development trend of the three dimensions and high integration for microfluidic systems in recent years, combining the characteristics of micro and drivable fluid flowing in 3D space is the current mainstream research goal in the functions of the micropumps. Here, based on the continuous electrowetting effect in a confined space of the Ga‐based liquid metal (LM), an LM driving micropump structure is proposed that enables fluid to be pumped up to 200 mm in height, which meets the major demands of microfluidic system working environments. The pumping mechanism is experimentally analyzed and demonstrated, as well as the working performance of the micropump under different output modes (continuous flow and pulsatile flow). The feasibility of this micropump is also verified through a fluid pumping experiment in complex shaped channels and a temperature management experiment in 3D space. This work is envisaged to expand the function and application area of the electric actuators driven by the Ga‐based LM and provide new support for micropumps in the 3D microfluidic chip system. [ABSTRACT FROM AUTHOR]

In this paper, an improved zeroing neural network (ZNN) model is proposed to obtain the positive definite solutions of the continuous coupled Lyapunov matrix equations (CLMEs) associated with continuous‐time Markovian jump (CMJ) systems. To achieve this, a general ZNN model is established by constructing a matrix‐valued error function. Then, to accelerate the convergence rate of the proposed ZNN model, the latest estimation is introduced to obtain an improved ZNN model. Some convergence conditions have been derived for the presented improved ZNN model through Lyapunov theory. Comparisons among the improved ZNN model and the existing results are conducted to illustrate the advantages of the proposed improved ZNN model in numerical examples. [ABSTRACT FROM AUTHOR]

Purpose: The delay alternating with nutation for tailored excitation (DANTE)–sampling perfection with application‐optimized contrasts (SPACE) sequence facilitates 3D intracranial vessel wall imaging with simultaneous suppression of blood and CSF. However, the achieved image contrast depends closely on the selected sequence parameters, and the clinical use of the sequence is limited in vivo by observed signal variations in the vessel wall, CSF, and blood. This paper introduces a comprehensive DANTE‐SPACE simulation framework, with the aim of providing a better understanding of the underlying contrast mechanisms and facilitating improved parameter selection and contrast optimization. Methods: An extended phase graph formalism was developed for efficient spin ensemble simulation of the DANTE‐SPACE sequence. Physiological processes such as pulsatile flow velocity variation, varying flow directions, intravoxel velocity variation, diffusion, and B1+$$ {\mathrm{B}}_1^{+} $$ effects were included in the framework to represent the mechanisms behind the achieved signal levels accurately. Results: Intravoxel velocity variation improved temporal stability and robustness against small velocity changes. Time‐varying pulsatile velocity variation affected CSF simulations, introducing periods of near‐zero velocity and partial rephasing. Inclusion of diffusion effects was found to substantially reduce the CSF signal. Blood flow trajectory variations had minor effects, but B1+$$ {\mathrm{B}}_1^{+} $$ differences along the trajectory reduced DANTE efficiency in low‐B1+$$ {\mathrm{B}}_1^{+} $$ areas. Introducing low‐velocity pulsatility of both CSF and vessel wall helped explain the in vivo observed signal heterogeneity in both tissue types. Conclusion: The presented simulation framework facilitates a more comprehensive optimization of DANTE‐SPACE sequence parameters. Furthermore, the simulation framework helps to explain observed contrasts in acquired data. [ABSTRACT FROM AUTHOR]

As living standards rise, more and more people are paying attention to their own health, especially issues such as cerebral thrombosis, cerebral infarction, and other cerebral blood flow problems. An accurate simulation of blood flow within cerebral vessels has emerged as a crucial area of research. In this study, we focus on microcirculatory blood flow in ischemic brain tissue and employ a 0D‐1D geometric multi‐scale coupled model to characterize this process. Given the intricate nature of human cerebral vessels, we apply a numerical method combining the finite element method and the third‐order Runge–Kutta method to resolve the coupled model. To enhance computational efficiency, we introduce a fast method based on the reduced‐order extrapolation algorithm. Our numerical example underscores the stability of the method and convergence accuracy to Oh3+τ3, while significantly improving the accuracy and efficiency of blood flow simulation, making the mechanism analysis more accurate. Additionally, we present examples detailing variations and distribution of intracranial pressure and blood flow in ischemic brain tissue throughout a cardiac cycle. Both reduced vascular compliance and vascular stenosis can have adverse effects on intracranial cerebral pressure and blood flow, leading to insufficient local oxygen supply and negative effects on brain function. Meanwhile, there will also be corresponding changes in volume flow and pulsatile blood pressure. [ABSTRACT FROM AUTHOR]

The emergence of computational fluid dynamics (CFD) enabled the simulation of intricate transport processes, including flow in physiological structures, such as blood vessels. While these so‐called hemodynamic simulations offer groundbreaking opportunities to solve problems at the clinical forefront, a successful translation of CFD to clinical decision‐making is challenging. Hemodynamic simulations are intrinsically complex, time‐consuming, and resource‐intensive, which conflicts with the time‐sensitive nature of clinical workflows and the fact that hospitals usually do not have the necessary resources or infrastructure to support CFD simulations. To address these transfer challenges, we propose a novel visualization system which enables instant flow exploration without performing on‐site simulation. To gain insights into the viability of the approach, we focus on hemodynamic simulations of the carotid bifurcation, which is a highly relevant arterial subtree in stroke diagnostics and prevention. We created an initial database of 120 high‐resolution carotid bifurcation flow models and developed a set of similarity metrics used to place a new carotid surface model into a neighborhood of simulated cases with the highest geometric similarity. The neighborhood can be immediately explored and the flow fields analyzed. We found that if the artery models are similar enough in the regions of interest, a new simulation leads to coinciding results, allowing the user to circumvent individual flow simulations. We conclude that similarity‐based visual analysis is a promising approach toward the usability of CFD in medical practice. [ABSTRACT FROM AUTHOR]

This study introduces a mathematical model that describes the Magnetohydrodynamics (MHD) flow of blood in a porous stenosis artery, incorporating a new hybrid nanofluid (HNF) model known as 'Quadruple' or the tetra‐(HNF) model. An innovative aspect of this study lies in the unexplored combination of tetra‐hybrid nanoparticles with the Sisko rheological model. The conventional Tiwari and Das (HNF) model has been expanded to accommodate the tetra‐(HNFs) case. To transform the governing partial differential equations into ordinary differential equations, a series of variable similarity transformations are employed. The resulting highly nonlinear simultaneous equations are efficiently solved using the shooting method. Numerical computations are conducted to investigate various parametric conditions, and graphs are utilized to visualize notable aspects of flow velocity and temperature. A comprehensive analysis is provided to illustrate the influence of flow parameters on wall shear stress and local Nusselt number, which are depicted through figures and tables. The study shows that the novel tetra‐HNF exhibits enhancements in blood flow when compared to nanofluids with a lower number of hybrids. Increasing the flow power index of non‐Newtonian Sisko model leads to improve convective heat transfer. Furthermore, parameters such as porosity, thermal radiation, and magnetic effects exhibit noticeable impacts on blood flow, temperature, and associated risks in constricted arteries. [ABSTRACT FROM AUTHOR]

The current investigation is purported on viscous heating dissipation and Hall consequences on mixed convection magneto-hydrodynamic heat captivating fluid transmitting from an impulsively starting vertical porous plate with ramp surface temperature and concentration in the existence of chemical reaction and radiation. The dimensional flow dominating partial differential equations is translated into a non-dimensional partial differential form by adopting appropriate variables and parameters. A finite element approach is driven to simplify the resulting dimensionless nonlinear linked partial differential equations with initial and boundary stipulates. The after-effects of flow commanding parameters on the velocity components, temperature and concentration are broadly analysed graphically, whereas both primary and secondary shear stresses, heat and mass transferral rates close to the surface area of the plate are discussed in tables. The ultimate results of this research revealed that viscous heating dissipation, Hall current, and thermal and mass buoyancy responses intensify both velocity components, whereas the efficacy of magnetic fields and radiation degrade both velocity components. The temperature distribution devalues with increasing heat absorption and Prandtl number, but a contrary impulse was noted with viscous heating dissipation. Likewise, concentration distribution expands with time progress but decays with chemical reaction parameters. A comparative analysis among the current results and certain research studies in the literature manifests the results’ precision and correctness. [ABSTRACT FROM AUTHOR]

We tested whether the brain and kidney respond differently to cardiopulmonary bypass (CPB) and to changes in perfusion conditions during CPB. Therefore, in ovine CPB, we assessed regional cerebral oxygen saturation (rSO2) by near‐infrared spectroscopy and renal cortical and medullary tissue oxygen tension (PO2), and, in some protocols, brain tissue PO2, by phosphorescence lifetime oximetry. During CPB, rSO2 correlated with mixed venous SO2 (r = 0.78) and brain tissue PO2 (r = 0.49) when arterial PO2 was varied. During the first 30 min of CPB, brain tissue PO2, rSO2 and renal cortical tissue PO2 did not fall, but renal medullary tissue PO2 did. Nevertheless, compared with stable anaesthesia, during stable CPB, rSO2 (66.8 decreasing to 61.3%) and both renal cortical (90.8 decreasing to 43.5 mm Hg) and medullary (44.3 decreasing to 19.2 mm Hg) tissue PO2 were lower. Both rSO2 and renal PO2 increased when pump flow was increased from 60 to 100 mL kg−1 min−1 at a target arterial pressure of 70 mm Hg. They also both increased when pump flow and arterial pressure were increased simultaneously. Neither was significantly altered by partially pulsatile flow. The vasopressor, metaraminol, dose‐dependently decreased rSO2, but increased renal cortical and medullary PO2. Increasing blood haemoglobin concentration increased rSO2, but not renal PO2. We conclude that both the brain and kidney are susceptible to hypoxia during CPB, which can be alleviated by increasing pump flow, even without increasing arterial pressure. However, increasing blood haemoglobin concentration increases brain, but not kidney oxygenation, whereas vasopressor support with metaraminol increases kidney, but not brain oxygenation. [ABSTRACT FROM AUTHOR]

The present research article delves into the application of machine learning techniques in the study of entropy generation arising from the electro‐MHD Casson nanofluid flow in a symmetric microchannel. The inertial effect on fluid flow through a non‐Darcy porous medium is considered where we have taken into account the velocity, thermal, and concentration slips at boundaries. The resulting system of PDEs is converted to system of ODEs using appropriate wave frame transformations. The metamorphosed system is solved using bvp4c routine of MATLAB. The impact of several factors represented by respective parameters on velocity, nanofluid temperature, fraction of nanoparticles, entropy generation, and Bejan number are shown through graphs. This study also employs a machine learning technique in which Particle Swarm Optimization (PSO) algorithm has been used in conjunction with an Artificial Neural Network (ANN) to develop a predictive model capable of optimizing entropy generation within this specific fluidic context. Such an analysis could be useful in determining the optimum entropy generation in pulsatile transport of physiological fluid through intestine. With the use of above mentioned machine learning technique, the considered model offers the minimum entropy generation for specific values of the electroosmotic parameter, dimensionless temperature difference, and velocity slip parameter. It is observed that the flow with minimum electroosmosis effect and maintained at a specific velocity slip gives the optimal entropy generation. [ABSTRACT FROM AUTHOR]

Background: Currently, determining procedural endpoints and treatment efficacy of vascular interventions is largely qualitative and relies on subjective visual assessment of digital subtraction angiography (DSA) images leading to large interobserver variabilities and poor reproducibility. Quantitative metrics such as the residual blood velocity in embolized vessel branches could help establish objective and reproducible endpoints. Recently, velocity quantification techniques based on a contrast enhanced X‐ray sequence such as qDSA and 4D DSA have been proposed. These techniques must be robust, and, to avoid radiation dose concerns, they should be compatible with low dose per frame image acquisition. Purpose: To develop and evaluate a technique for robust blood velocity quantification from low dose contrast enhanced X‐ray image sequences that leverages the oscillating signal created by pulsatile blood flow. Methods: The proposed spatiotemporal frequency domain (STF) approach quantifies velocities from time attenuation maps (TAMs) representing the oscillating signal over time for all points along a vessel centerline. Due to the time it takes a contrast bolus to travel along the vessel centerline, the resulting TAM resembles a sheared sine wave. The shear angle is related to the velocity and can be determined in the spatiotemporal frequency domain after applying the 2D Fourier transform to the TAM. The approach was evaluated in a straight tube phantom using three different radiation dose levels and compared to ultrasound transit‐time‐based measurements. The STF velocity results were also compared to previously published approaches for the measurement of blood velocity from contrast enhanced X‐ray sequences including shifted least squared (SLS) and phase shift (PHS). Additionally, an in vivo porcine study (n = 8) was performed where increasing amounts of embolic particles were injected into a hepatic or splenic artery with intermittent velocity measurements after each injection to monitor the resulting reduction in velocity. Results: At the lowest evaluated dose level (average air kerma rate 1.3 mGy/s at the interventional reference point), the Pearson correlation between ultrasound and STF velocity measurements was 99%$99\%$. This was significantly higher (p<0.0001$p < 0.0001$) than corresponding correlation results between ultrasound and the previously published SLS and PHS approaches (91$\hskip.001pt 91$ and 93%$93\%$, respectively). In the in vivo study, a reduction in velocity was observed in 85.7%$85.7\%$ of cases after injection of 1 mL, 96.4%$96.4\%$ after 3 mL, and 100.0%$100.0\%$ after 4 mL of embolic particles. Conclusions: The results show good agreement of the spatiotemporal frequency domain approach with ultrasound even in low dose per frame image sequences. Additionally, the in vivo study demonstrates the ability to monitor the physiological changes due to embolization. This could provide quantitative metrics during vascular procedures to establish objective and reproducible endpoints. [ABSTRACT FROM AUTHOR]

Currently, there are no ex vivo systems that can model the motion of peripheral arteries and allow for the evaluation of pharmacokinetics (PK) of endovascular devices. The objective of this study was to develop a novel peripheral simulating bioreactor system to evaluate drug pharmacokinetics of stents. We utilized 3D-printed and off-the-shelf components to construct a peripheral-simulating bioreactor system capable of mimicking the motion of peripheral arteries. Servo motors were primarily used to shorten/elongate, twist, and bend explanted porcine carotid arteries. To evaluate the pharmacokinetics in the bioreactor, drug-eluting stents were deployed within explanted arteries and subjected to vascular motion along with pulsatile flow conditions. Following 30 min and 24 h, the arteries were removed, and paclitaxel levels were measured. Scanning electron microscopy was also performed to evaluate the stent surface. Arterial paclitaxel levels of the stent-treated arteries were found to be higher at 30 min than at 24 h following pulsatile and no vascular motion and even higher at 24 h following pulsatile flow and vascular motion. The residual drug on the stent significantly decreased from 30 min to 24 h. Scanning electron microscopy confirmed the loss of paclitaxel coating at 24 h and greater disturbance in stents under peripheral motion versus pulsatile only. This system represents the first ex vivo system to determine the PK of drug-eluting stents under physiological flow and vascular motion conditions. This work provides a novel system for a quick and inexpensive preclinical tool to study acute drug tissue concentration kinetics of drug-releasing interventional vascular devices designed for peripheral applications. [ABSTRACT FROM AUTHOR]

The issue of vascular stenosis has recently received significant innovative interest among researchers. Due to the buildup of adipocytes and other constituents of atherosclerotic, arteries can generate an abnormal condition called arterial stenosis. It optimizes blood circulation to prevent myocardial illness. In light of this, the current scientific report assembled a Casson fluid model to assess the MHD peristaltic transit of blood supply via a mildly stenotic artery when copper nanoparticles are added. A relevant simulation model is often used to outline the issue, acquiring non‐dimensional variables and approximations for the stenosis. Temperature has quantitative approaches, and the result for velocity is derived numerically in MATHEMATICA. The expressions for Nusselt number, wall shear stress, flow resistance distribution and stream function are attained. The under action of copper nanoparticles, the consequences of several new physiological measures on arterial blood circulation properties are visually displayed and explained briefly. A pictorial explanation of the trapping phenomena is also provided. In comparison to arteries devoid of stenosis, arteries with stenosis have a higher temperature distribution throughout the fluid flow and velocity. In addition, high temperature and velocity increase in the middle of the artery and decrease as one gets closer to the arterial wall. Further, the concentration, Grashof number and heat source and sink parameters of the nanoparticles reduce the wall shear stress of the blood in the arteries since the arterial wall contributes heat to the flow zone. The discovery could have medical applications as well as bioinformatics. Furthermore, the current work contributes to the cure of different cardiac illnesses. [ABSTRACT FROM AUTHOR]

In the current work, we analyzed the non‐Newtonian rheology of blood through a multi‐stenosed artery with a cross‐section of elliptical shape. The blood is regarded as Erying–Powell fluid, and flow is considered to have no slip at the stenotic wall. The mathematical model is processed to a non‐dimensional form, and conditions of mild stenosis are utilized to decrease its nonlinearity. The resulting equations are solved by applying the perturbation technique by considering the fluid characteristic parameter K$K$ as the perturbation parameter. The solution is completed by using the polynomial of degree four. The solutions of mathematical equations are deeply examined by graphical analysis. The non‐Newtonian impacts are predominant in the surrounding of the stenosed wall along the minor axis of the elliptical artery. The height of stenosis affects the pressure rise and flow resistance. The shear stress at the arterial wall is very high in the stenotic region and has more potent effects in the neighboring boundary point on the minor axis. Progressive stenosis causes a reduction in the blood flow velocity surrounding the arterial wall due to higher resistance to the flow. However, the velocity improves near the center line of the artery. Further, the fluid's velocity is very high in the constricted (stenotic zone) region. [ABSTRACT FROM AUTHOR]

In biomechanical devices, blood can be transfused through small, curved walls. Accordingly, this research highlights the study of blood flow in cases of stenosis of the elastic artery with curvature. The effects of bending on the shear and resistance through this elastic tube have been investigated. The moderate stenosis case has been used to simulate the governing equations for an incompressible and steady non‐Newtonian fluid, or "tangent hyperbolic fluid". A perturbation technique has been used to obtain an analytical solution. The Rubinow & Keller model [24] simulates the flexibility of the stenosis artery walls. The results showed that increasing the parameters linked to the walls' flexibility made it easier for blood to flow through the stenosis area, which emphasizes the need for a thorough investigation of non‐Newtonian fluid flow phenomena. One of the most important threats facing humanity is blood stenosis. In microvasculature, there are many conditions in which the blood vessels are curved or twisted, especially in the case of disease. [ABSTRACT FROM AUTHOR]

The quadratic matrix equation (QME) Q(X)=AX2+BX+C=0,$$\begin{equation*} Q(X)=AX^{2}+BX+C=0, \end{equation*}$$occurs in the branches such as the quadratic eigenvalue problems and quasi‐birth‐death processes. Also, the numerical solution of QMEs is an essential step in many computational methods for linear‐quadratic and robust control, filtering, controller order reduction, inner‐outer factorization, spectral factorization, and other applications. In this study, schemes are presented to solve the QME based on the Hermitian and skew‐Hermitian splitting (HSS). It is shown that the proposed schemes converge to the solutions of the QME. Finally, some examples are solved to discover the application of the schemes in comparison with Newton's method. [ABSTRACT FROM AUTHOR]

This article analyzes the impact of conjugated dissipative radiative heat transfer with heat source/sink, thermal slip, and the transverse magnetic field on the behavior of the magnetohydrodynamic (MHD) peristaltic thrust containing ferromagnetic gold nanoparticles (AuNPs) with different shape factors through the non‐Newtionian blood flow within compliant walls tube. Entropy generation (EG) plays a prominent role in all aspects connected to thermodynamics and heat transfer aiding in the identification and reduction of system irreversibilities. The sources of irreversibility stem from dissipative friction inherent in fluid flow, the presence of a magnetic field, and the heat transfer process. The ferromagnetic gold nanoparticles (AuNPs) exhibit diverse shapes (bricks, cylinders, and platelets) and possess both magnetic and thermal attributes thereby enhancing the efficiency of heat transfer process. The peristaltic thrust drives the dynamic behavior of the gold blood nanofluid through a compliant tube. The tube walls are flexible and exhibit a curvature effects that can alter the dynamics of fluid flow. The effective Hamilton‐Crosser model is selected to express the thermal conductivity of the nanofluid. Gold blood nanofluids can be treated as incompressible, non‐Newtonian, and MHD fluid flow. The governing equations of the system are solved using the perturbation approach under the assumptions of low Reynolds numbers and long wavelength. Hybrid interactions of magnetic field, radiative heating, thermal slip, elastic wall properties, and gold nanoparticles shapes and concentrations are investigated within the gold blood nanofluid flow. The resulting graphs include the profiles of velocity, temperature distributions, EG, and irreversibility parameters under the influence of the above parameters. The findings reveal that the overall EG rises with increasing values of heat source intensity, Brinkman number, temperature difference factor, compliant wall curvature coefficient, and gold nanoparticles concentrations. Additionally, it is observed that an increase in magnetic flux strength results in the emergence of reversal flow patterns near the walls. This arises due to the augmented magnetic flux obstructing the peristaltic nanofluid flow leading to reduce streamwise velocity. Moreover, heightened magnetic flux strength causes temperature reduction for both thermal slip and non‐slip conditions. Generally, the presence of a thermal slipping parameter further enhances the distribution of temperature. In essence, the rationale and significance of this study primarily revolve around comprehending the interplay of these diverse factors with MHD peristaltic motion of gold blood nanofluid and EG. This not only furthers our theoretical understanding of complex systems but also has practical implications that can improve new technologies, processes, and medical applications. For example, in medical treatments like photothermal therapy (PPT), insights gained from this research can help in developing more effective and precise treatment methods. By understanding the impact of these factors on EG, new ways can be identified to minimize or manage system inefficiencies leading to more sustainable and optimized treatment processes. This research holds promise for application in cancer detection and treatment by employing a combination of PPT and magnetic hyperthermia. This entails dispersing AuNPs into the blood circulation through arteries and blood vessels and subsequently applying photothermal radiation and a magnetic field. [ABSTRACT FROM AUTHOR]

The interest in flow batteries as energy storage devices is growing due to the rising share of intermittent renewable energy sources. In this work, the performance of a vanadium flow battery is improved, without altering the electrochemical cell, by applying a pulsating flow. This novel flow battery flow regime aims to enhance performance by improving its mass transfer properties. Both the pulse volume and frequency have an influence on the battery performance, and lead to a 38.7 % increase in accessible discharge capacity compared to the conventional steady flow regime at values of 0.40 cm3 and 2.4 Hz in this cell, respectively. Furthermore, at these parameter settings a reduction of the mass transfer resistance by 71.4 % is achieved at 0.2 cm3/min ⋅ cm2. These results show that a pulsating flow can be beneficial in certain conditions, opening new possibilities for boosting performance in flow batteries. [ABSTRACT FROM AUTHOR]

The study was carried out to investigate the effect of the artery with different pulse values and stenosis rates on the pressure drop, the peristaltic pump outlet pressure, fractional flow reserve (FFR) and most importantly the amount of power consumed by the peristaltic pump. For this purpose, images taken from the clinical environment were produced as models (10 mm inlet diameter) with 0% and 70% percent areal stenosis rates (PSR) on a three‐dimensional (3D) printer. In the experimental system, pure water was used as the fluid at 54, 84, 114, 132, and 168 bpm pulse values. In addition, computational fluid dynamics (CFD) analyzes of the test region were performed using experimental boundary conditions with the help of ANSYS‐Fluent software. The findings showed that as PSR increases in the arteries, the pressure drop in the stenosis region increases and this amount increases dramatically with increasing effort. An increase of approximately 40% was observed in the pump outlet pressure value from 54 bpm to 168 bpm in the PSR 0% model and 51% increase in the PSR 70% model. It has been observed that the pump does more work to overcome the increased pressure difference due to increased pulse rate and PSR. With the effect of contraction, the power consumption of the pump increased from 9.2% for 54 bpm to 13.8% for 168 bpm. In both models, the Wall Shear Stress (WSS) increased significantly. WSS increased abruptly in the stenosis and arcuate regions, while sudden decreases were observed in the flow separation region. [ABSTRACT FROM AUTHOR]

Precise control on the droplet generation is an important issue for the application of droplet microfluidics. Passive formation of droplets depends on multiparameters. The droplet size and generation frequency highly correlate to each other, raising the control difficulty. In comparison, the active method through external perturbations is more flexible. In this work, the droplet generation governed by pulsatile continuous‐phase flow is numerically studied. The effects of the pulsation amplitude and frequency, as well as the velocity and viscosity of the discrete fluid are investigated. Different modes of droplet generation (viz., sub‐periodic, period‐1, and period‐n modes) are identified, the underlying mechanisms are interpreted. This method may be applied in various droplet microfluidic/microreactor systems to improve the droplets control and manipulations. [ABSTRACT FROM AUTHOR]

The article discusses the rising prevalence of heart failure, particularly in low- and middle-income countries (LMICs), and the limitations of current treatment options such as heart transplantation and ventricular assist devices (VADs). It introduces the concept of implantable cardiac soft robotic sleeves (ICRS) as a potential solution. The ICRS utilizes soft robotics and biomimicry to replicate the natural motion of the myocardium, offering advantages such as pulsatile flow, reduced need for anticoagulation therapy, potential for miniaturization, and synchronization with the natural heart. The article highlights the implications of this technology for LMICs, including cost-effectiveness, manufacturing efficiency, increased accessibility, and long-term sustainability. However, it acknowledges the challenges that need to be addressed, such as safety and efficacy trials, cost, healthcare infrastructure, and patient selection. Despite these challenges, the ICRS represents a promising technology that could significantly benefit end-stage heart failure patients in LMICs and contribute to global health equity. The authors emphasize the importance of collaboration among stakeholders to accelerate the development and deployment of this technology. Overall, the article presents the ICRS as an innovative solution to address the pressing health challenges of heart failure and bridge healthcare disparities. [Extracted from the article]

Background: Maintaining balanced left and right cardiac outputs in a total artificial heart (TAH) is challenging due to the need for continuous adaptation to changing hemodynamic conditions. Proper balance in ventricular outputs of the left and right ventricles requires a preload‐sensitive response and mechanisms to address the higher volumetric efficiency of the right ventricle. Methods: This review provides a comprehensive overview of various methods used to balance left and right ventricular outputs in pulsatile total artificial hearts, categorized based on their actuation mechanism. Results: Reported strategies include incorporating compliant materials and/or air cushions inside the ventricles, employing active control mechanisms to regulate ventricular filling state, and utilizing various shunts (such as hydraulic or intra‐atrial shunts). Furthermore, reducing right ventricular stroke volume compared to the left often serves to balance the ventricular outputs. Individually controlled actuation of both ventricles in a pulsatile TAH seems to be the simplest and most effective way to achieve proper preload sensitivity and left–right output balance. Pneumatically actuated TAHs have the advantage to respond passively to preload changes. Conclusion: Therefore, a pneumatic TAH that comprises two individually actuated ventricles appears to be a more desirable option—both in terms of simplicity and efficacy—to respond to changing hemodynamic conditions. [ABSTRACT FROM AUTHOR]

This article presents a comprehensive multiphase computational fluid dynamics model to simulate the arc heating process in the ladle. The results on temperature distribution, slag eye size, flow characteristics, and wall shear stress under three flow rate conditions are discussed. Validation of the results is carried out by comparing them with industrial measurements. The study highlights that when the flow rate increases by 100%, the temperature difference in the ladle decreases by 17.37%, while the slag eye‐opening and wall shear stress increase by 116.38% and 49.86%, respectively. The study emphasizes the details of model development and utilization of models to optimize the process. [ABSTRACT FROM AUTHOR]

Objectives: To compare the deposition patterns within the nasal cavity between the bi‐directional and unilateral nasal delivery systems. And to summarize the clinical application of the bi‐directional nasal drug delivery devices. Data source: PubMed, Cochrane Library, Embase, and Web of Science databases. Methods: A scoping review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analysis (PRISMA). We included studies exploring patterns and influencing factors of particle depositions within the nasal cavity among patients, healthy controls, and nose cast models using the bi‐directional and unilateral nasal delivery system. The clinical application of the bi‐directional delivery devices was also summarized. Results: A total of 24 studies were included in this review. Bi‐directional nasal delivery systems utilize forced exhalation to power the delivery of drugs to deeper areas of the nasal cavity and paranasal sinuses. Unilateral nasal delivery systems included traditional liquid spray pumps, the aerosol mask system, nebulization, and conventional nasal inhalation. Compared with unilateral delivery systems, the bi‐directional nasal delivery system provided a more extensive and efficient nasal deposition in the nasal cavity, especially in the olfactory cleft, without lung deposition. Several parameters, including particle size, pulsatile flow, and nasal geometry, could significantly influence nasal deposition. The bi‐directional nasal delivery system enables better delivery of steroids or sumatriptan to the sinonasal cavity's high and deep target sites. This bi‐directional delivery device demonstrated an effective and well‐tolerated treatment that produced high drug utilization, rapid absorption, and sustained symptom improvement among patients with chronic rhinosinusitis (CRS) or migraine. Conclusion: The bi‐directional nasal drug delivery systems demonstrated significantly higher drug deposition in superior and posterior regions of the nasal cavity than unilateral nasal delivery systems. Further studies should explore its potential role in delivering drugs to the olfactory cleft among patients with olfactory disorders and central nervous system diseases. Level of evidence: N/A. [ABSTRACT FROM AUTHOR]

Purpose: To ultimately make accurate and precise fetal noninvasive oxygen saturation (sO2) measurements by T2‐prepared bSSFP more widely available by systematically assessing error sources in order to potentially reduce perinatal mortality in cardiovascular malformations and fetal growth restriction. Methods: T2‐prepared bSSFP data were acquired in phantoms; in flowing blood in adults in the superior sagittal sinus, ascending and descending aorta, and main pulmonary artery; and in the fetal descending aorta and umbilical vein. T2 was assessed in relation to T2 two‐ or three‐parameter curve‐fitting techniques, SSFP readout, refocusing time delay (τ), constant and pulsatile blood flow, and impact of T1 recovery. Further, fetal T2 and sO2 variability were quantified in the descending aorta and umbilical vein in healthy fetuses and fetuses with cardiovascular malformation (gestational weeks 32–38). Results: In phantoms, three‐parameter fitting was accurate irrespective of phase FOV (<4 ms; i.e., <2%), and T2 was overestimated (up to 23 ms/10%; p = 0.001) beyond ±30 Hz off‐resonance. In the adult aorta, T2 was underestimated during higher blood flow velocities and pulsatility for τ = 16 ms (−41 ms/−17%; p = 0.008). In fetuses, two‐parameter fitting overestimated T2 compared with three‐parameter fitting (+33 ms/+18%; p = 0.03). T2 variability was 18 ms/15% in the fetal descending aorta and 28 ms/14% in the umbilical vein. The resulting estimated sO2 variability was ∼10% (15% of sO2 value) in the fetal descending aorta. Conclusions: Errors due to T2‐fitting techniques, off‐resonance, flow velocity, and insufficient T1 recovery between image acquisitions could be mitigated by using three‐parameter fitting with included saturation‐prepared images approximating infinite T2‐preparation time, adequate shimming covering the fetus and placenta, and by modifying acquisition parameters. Variability in fetal blood T2 and sO2, however, indicate that it is currently not feasible to use these methods for prediction of disease. [ABSTRACT FROM AUTHOR]

The feasibility of the detection of electromagnetic response in the upper ionosphere to ground large‐scale ultra‐low‐frequency (ULF) and extremely‐low‐frequency (ELF) transmitters by low‐Earth‐orbit (LEO) satellites is considered. As an example of such transmitters, we consider the ZEVS 82 Hz transmitter, FENICS installation driven by 0.5–150 Hz generator, and industrial 50 Hz unbalanced power transmission lines. We numerically model the ULF/ELF wave energy leakage into the upper ionosphere from an oscillating grounded linear power line of a finite length suspended above a ground with a finite resistivity. The numerical scheme is based on the theoretical formalism developed to describe the excitation of an electromagnetic field by a horizontal grounded dipole. A realistic altitudinal profile of the plasma parameters has been reconstructed with the use of the IRI ionospheric model. For the ZEVS transmitter powered by 200 A current the modeled amplitudes of electromagnetic response can reach in the upper nightside ionosphere up to 60 µV/m and 6 pT. The assumption of an infinite source scale overestimates the ionospheric response by a factor of ∼7 as compared with realistic scale 60 km of the ZEVS transmitter. Unbalanced 50 Hz current of 10 A in large‐scale (>100 km) power transmission lines can produce the electric response in the upper ionosphere that is sufficient to be detected by electric sensors at LEO satellite. The stimulation of artificial Pc1 pulsations (0.5 Hz) with amplitudes ∼1 pT and ∼10 µV/m by large‐scale (>100 km) power lines is possible with driving current >100 A. The use of decommissioned power lines can be a cheap and efficient tool to stimulate Pc1 pulsations in the ionosphere. Plain Language Summary: Our planet was found to exist in an electromagnetic environment, at least in some frequency bands, created by rather industrial activity than by natural processes. The electromagnetic response in the ionosphere to thunderstorms and radio transmitters has been well studied in the very‐low‐frequency range (>1 kHz), but much less attention has been paid to the extremely‐low‐frequency (ELF) (≪1 kHz) and ultra‐low‐frequency (ULF) (<1 Hz) bands. Any noticeable ULF/ELF emission efficiency may be expected only for extremely large‐scale emitting systems. Such man‐made transmitters do exist. Powerful ELF aerials for communication with submarines with a length of about several tens of km were constructed. Special experiments with controlled sources of electromagnetic fields of ULF/ELF bands were carried out using decommissioned power lines as a horizontal radiating antenna. Transportation systems can also be extended ULF antenna. Finally, unbalanced networks of electric power transmission 50/60 Hz lines become large‐scale emitters. Our numerical modeling has proved that manmade ULF/ELF electromagnetic activity near the ground can be monitored by low‐Earth‐orbit satellites. The large‐scale decommissioned power lines can be used to stimulate artificial Pc1 pulsations with frequency ≤1 Hz in the ionosphere‐magnetosphere system. These experiments open the possibility to stimulate a loss of relativistic electrons from the radiation belt. Key Points: New numerical model of ultra‐low‐frequency/extremely‐low‐frequency emission generation in the ionosphere by a near‐ground linear current of a finite length has been elaboratedThe model gives the possibility to estimate electromagnetic response of the ionosphere to current sources of different lengthsArtificial Pc1 pulsations can be generated in the upper ionosphere by a large‐scale power line system [ABSTRACT FROM AUTHOR]

Introduction: Our objective was to compare the in vitro efficacy of electrothermal bipolar [EB] vessel sealing and ultrasonic harmonic scalpel [HS] versus mechanical interruption, with conventional ties or surgical clips (SC), in sealing saphenous vein (SV) collaterals, during its eventual preparation for bypass surgery. Methods: Experimental in vitro study on 30 segments of SV. Each fragment included two collaterals at least 2 mm in diameter. One of them was sealed by ligation with 3/0 silk ties (control) and the other one with EB (n = 10), HS (n = 10) or medium-6 mm SC (n = 10). After incorporation in a closed circuit with pulsatile flow, the pressure was progressively increased until causing rupture. Collateral diameter, burst pressure, leak point, and histological study were recorded. Results: Burst pressure was higher for SC (1320.20 ± 373.847 mmHg) as compared with EB (942.2 ± 344.9 mmHg, p = 0.065), and especially with HS (637.00 ± 320.61 mmHg, p = 0.0001). No statistically significant difference between EB and HS was found, and bursting always happened at supraphysiological pressures. The leak point for HS was always detected in the sealing zone (10/10), while for EB and SC, it occurred in the sealing zone only in 6/10(60%) and 4/10(40%), respectively (p = 0.015). Conclusions: Energy delivery devices showed similar efficacy and safety in sealing of SV side branches. Although bursting pressure was lower than with tie ligature or SC, non-inferiority efficacy was shown at the range of physiological pressures in both, EB and HS. Due to their speed and easy handling, they may be useful in the preparation of the venous graft during revascularization surgery. However, remaining questions about healing process, potential spread of tissue damage and sealing durability, will require further analysis. [ABSTRACT FROM AUTHOR]

In this paper, we study how the magnetohydrodynamic (MHD) pulsatile flow of blood and heat transfer works through a constricted artery with a flexible wall. The human circulatory network consists of veins and arteries that sometimes contain constrictions, allowing the impact of the applied magnetic field on flow fields to be observed. The walls of the flowing medium are considered to be a function of time. The flowing blood is hypothesized as shear‐thinning fluid, emulating Yeleswarapu's viscosity replica. Additionally, we consider the energy equation to understand the impact of a magnetic field on heat transfer rates for such flows. The vorticity transport equation along with the stream function equation is obtained using the vorticity–stream function technique. Numerical solutions of the governing nonlinear MHD equations and energy equation in addition to physically pertinent flow conditions were achieved by adapting a finite difference scheme. Considerable attention has been paid to ensure an accurate comparison between the current and previous results. The two sets of numbers appear to match closely. For an even deeper understanding of the flow and heat transport process, the effects of height of stenosis and diverse physiological parameters on time‐averaged wall shear stress (TAWSS), rate of heat transport, and so on are explored in depth through their graphical depiction. In the vicinity of the constriction, it is observed that the separation becomes longer with increasing constriction height. Higher magnetic force strength leads to a reduction in separation length. Newtonian fluids transfer heat more rapidly in their narrowing regions and downstream than fluids with non‐Newtonian behavior. [ABSTRACT FROM AUTHOR]

Purpose: To estimate relative transvalvular pressure gradient (TVPG) noninvasively from 4D flow MRI. Methods: A novel deep learning–based approach is proposed to estimate pressure gradient across stenosis from four‐dimensional flow MRI (4D flow MRI) velocities. A deep neural network 4D flow Velocity‐to‐Presure Network (4Dflow‐VP‐Net) was trained to learn the spatiotemporal relationship between velocities and pressure in stenotic vessels. Training data were simulated by computational fluid dynamics (CFD) for different pulsatile flow conditions under an aortic flow waveform. The network was tested to predict pressure from CFD‐simulated velocity data, in vitro 4D flow MRI data, and in vivo 4D flow MRI data of patients with both moderate and severe aortic stenosis. TVPG derived from 4Dflow‐VP‐Net was compared to catheter‐based pressure measurements for available flow rates, in vitro and Doppler echocardiography–based pressure measurement, in vivo. Results: Relative pressures calculated by 4Dflow‐VP‐Net and in vitro pressure catheterization revealed strong correlation (r2 = 0.91). Correlations analysis of TVPG from reference CFD and 4Dflow‐VP‐Net for 450 simulated flow conditions showed strong correlation (r2 = 0.99). TVPG from in vitro MRI had a correlation coefficient of r2 = 0.98 with reference CFD. 4Dflow‐VP‐Net, applied to 4D flow MRI in 16 patients, showed comparable TVPG measurement with Doppler echocardiography (r2 = 0.85). Bland–Altman analysis of TVPG measurements showed mean bias and limits of agreement of −0.20 ± 2.07 mmHg and 0.19 ± 0.45 mmHg for CFD‐simulated velocities and in vitro 4D flow velocities. In patients, overestimation of Doppler echocardiography relative to TVPG from 4Dflow‐VP‐Net (10.99 ± 6.77 mmHg) was observed. Conclusion: The proposed approach can predict relative pressure in both in vitro and in vivo 4D flow MRI of aortic stenotic patients with high fidelity. [ABSTRACT FROM AUTHOR]

Patients had pulmonary nodules discovered on a variety of imaging modalities (77 via whole lung CT, 8 via partial lung CT and 15 via nuclear medicine studies). A thorough analysis of patient history, previous imaging studies and other investigations as well as clinical examination could negate the use of CT brain studies for all patients with first-episode psychosis at Nepean Blue Mountains Local Health District with imaging studies only performed for a subset of patients that require it for further evaluation. MRI may be more useful when imaging younger patients due to lower radiation exposure, and higher reported accuracy of MRI than CT in diagnosing diverticulitis in younger patients (4). The positive diagnosis rate of computed tomography scans performed for symptomatic Neutropaen... V Chang 1, E Liang 2 and P Schmidt 3 1 Griffith University, School of Medicine and Dentistry, Queensland, Australia, 2 Princess Al... B Purpose: b The use of computed tomography (CT) to locate the source of infection in patients with febrile neutropaenia has been documented as early as 1996. Junior doctors do not understand contrast phases in CT imaging - results from a single-centre... A Ajjikuttira 1, M Gandhi 1, C Hacking 1 and A Coulthard 1,2 1 Royal Brisbane and Women's Hospital, Herston, Queensland, Australia, 2 Department of Medici... B Purpose: b Cross sectional computed tomography (CT) is an important investigation in the clinician's arsenal. [Extracted from the article]

Synovitis studies are the key to the treatment of most arthritis diseases in a human physique. So this study visualizes the effects of two dependent fluid viscosity models on magnet nano peristaltic transport of synovial fluid in nonuniform channel walls. Two fluid models are constructed, the first model considered that the Shear rate is dependent on fluid concentration (model‐I), and the exponentially dependent viscosity on the fluid concentration is proposed as a second model (model‐II). The fluid models are represented by a highly nonlinear system of partial differential equations. Joule heat, thermal radiation, and Arrhenius energy are studied as external effects. Those models are offered in a gradient mechanism, then simplified using droppings bars and using the fact of long wavelength, and low Reynolds. Pressure gradient and trapped bolus profiles and shear stress distribution as well as fluid temperature, velocity, and concentration performance are scrutinized. Analytical results are obtained in appropriate/chosen boundary conditions depending on the walls of the channel. Attracted/signified results are compared with the nearest trusted results by Khan et al. Solution intervals are sub‐divided and analytically treated at each of them by multi‐stage differential transform algorithms. Outcomes gratify that, joints are provided by more cushion and lubrication at high fluid temperatures. Magnetic effects are advised in rheumatoid arthritis treatments, increasing the synovial fluid temperature and allowing fluid particles to move freely inside joints. [ABSTRACT FROM AUTHOR]

A unified model is developed for the analysis of heat transfer (radiation and non‐Fourier conduction) in an axisymmetric participating medium. The proposed model includes three different variants of hyperbolic–parabolic heat conduction models, that is, the single phase lag model, dual phase lag model, and the Fourier (no phase lag) model. The radiating‐conducting medium is radiatively absorbing, emitting, and isotropically scattering. Significance of all the above mentioned models on the heat transfer characteristics is investigated in a two‐dimensional axisymmetric geometry. The equation of transfer and the coupled non‐Fourier conduction‐radiation equation are solved via finite volume method. A fully implicit scheme is used to resolve the transient terms in the energy equation. For spatial resolution of radiation information, the STEP scheme is applied. Tri‐diagonal‐matrix‐algorithm is used to solve the resulting set of linear discrete equations. Effects of two important influencing parameters: the scattering albedo and the radiation‐ conduction parameter are studied on the temporal evolution of temperature field in the radiatively participating medium. The non‐Fourier effect of heat transport captured well with the proposed unified model. A good agreement can be found between the proposed model predictions and those available in the literature. It is also found that when the phase lag of the temperature gradient and the heat flux are the same, it reduces to conventional Fourier conduction‐radiation and the wave behavior diminishes. However, the reduction to this Fourier model fails in the presence of constant blood perfusion and metabolic heat generation. [ABSTRACT FROM AUTHOR]

A 6‐month‐old male neutered Domestic Shorthair cat was assessed for a 24‐h history of anorexia, lethargy, depressed mentation, mild abdominal pain and persistent bradycardia. Abdominal ultrasound revealed marked thickening of the gastric wall, gastric distension, free abdominal fluid, distension and corrugation of the small intestine. Full‐thickness histopathological biopsy of the gastric wall demonstrated intralesional chitinous structures whose morphology (size and presence of obvious barbs) supports these structures being urticating hairs (setae). A processionary caterpillar is considered most likely as these are the most common urticating caterpillars in Australia. This is the first case of suspected severe gastroenteritis associated with the ingestion of caterpillar setae fragments in a cat. [ABSTRACT FROM AUTHOR]

Objective: To describe the acute cardiovascular adaptation of the fetus after connection to an artificial placenta (AP) in a sheep model, using ultrasound and invasive and non‐invasive hemodynamic assessment. Methods: This was an experimental study of 12 fetal sheep that were transferred to an AP system, consisting of a pumpless circuit with umbilical cord connection, at 109–117 days' gestation. The study was designed to collect in‐utero and postcannulation measurements in all the animals. The first six consecutive fetuses were fitted with intravascular catheters and perivascular probes to obtain invasive physiological data, including arterial and venous intravascular pressures and perivascular blood flows, with measurements taken in utero and at 5 and 30 min after cannulation. These experiments were designed with a survival goal of 1–3 h. The second set of six fetuses were not fitted with catheters, and experiments were aimed at 3–24 h of survival. Echocardiographic assessment of cardiac anatomy and function, as well as measurements of blood flow and pre‐ and postmembrane pressures recorded by circuit sensors in the AP system, were available for most of the fetuses. These data were acquired in utero and at 30 and 180 min after cannulation. Results: Compared with in‐utero conditions, the pulsatility index at 30 and 180 min after connection to the AP system was reduced in the umbilical artery (median, 1.36 (interquartile range (IQR), 1.06–1.50) vs 0.38 (IQR, 0.31–0.50) vs 0.36 (IQR, 0.29–0.41); P < 0.001 for extreme timepoints) and the ductus venosus (median, 0.50 (IQR, 0.41–0.67) vs 0.29 (IQR, 0.22–0.33) vs 0.36 (IQR, 0.22–0.41); P = 0.011 for extreme timepoints), whereas umbilical venous peak velocity increased (median, 20 cm/s (IQR, 18–22 cm/s) vs 39 cm/s (IQR, 31–43 cm/s) vs 43 cm/s (IQR, 34–54 cm/s); P < 0.001 for extreme timepoints) and flow became more pulsatile. Intravascular monitoring showed that arterial and venous pressures increased transiently after connection, with median values for mean arterial pressure at baseline, 5 min and 30 min of 43 mmHg (IQR, 35–54 mmHg), 72 mmHg (IQR, 61–77 mmHg) and 58 mmHg (IQR, 50–64 mmHg), respectively (P = 0.02 for baseline vs 5 min). Echocardiography showed a similar transient elevation of fetal heart rate at 30 and 180 min after connection compared with in utero (median, 145 bpm (IQR, 142–156 bpm) vs 188 bpm (IQR, 171–209 bpm) vs 175 bpm (IQR, 165–190 bpm); P = 0.001 for extreme timepoints). Fetal cardiac structure and function were mainly preserved; median values for right fractional area change were 36% (IQR, 34–41%) in utero, 38% (IQR, 30–40%) at 30 min and 37% (IQR, 33–40%) at 180 min (P = 0.807 for extreme timepoints). Conclusions: Connection to an AP system resulted in a transient fetal hemodynamic response that tended to normalize over hours. In this short‐term evaluation, cardiac structure and function were preserved. However, the system resulted in non‐physiologically elevated venous pressure and pulsatile flow, which should be corrected to avoid later impairment of cardiac function. © 2023 International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]

Objective: Pulsatile‐flow veno‐arterial extracorporeal membrane oxygenation (V‐A ECMO) has shown encouraging results for microcirculation resuscitation and left ventricle unloading in patients with refractory cardiogenic shock. We aimed to comprehensively assess different V‐A ECMO parameters and their contribution to hemodynamic energy production and transfer through the device circuit. Methods: We used the i‐cor® ECMO circuit, which composed of Deltastream DP3 diagonal pump and i‐cor® console (Xenios AG), the Hilite 7000 membrane oxygenator (Xenios AG), venous and arterial tubing and a 1 L soft venous pseudo‐patient reservoir. Four different arterial cannulae (Biomedicus 15 and 17 Fr, Maquet 15 and 17 Fr) were used. For each cannula, 192 different pulsatile modes were investigated by adjusting flow rate, systole/diastole ratio, pulsatile amplitudes and frequency, yielding 784 unique conditions. A dSpace data acquisition system was used to collect flow and pressure data. Results: Increasing flow rates and pulsatile amplitudes were associated with significantly higher hemodynamic energy production (both p < 0.001), while no significant associations were seen while adjusting systole‐to‐diastole ratio (p = 0.73) or pulsing frequency (p = 0.99). Arterial cannula represents the highest resistance to hemodynamic energy transfer with 32%–59% of total hemodynamic energy generated being lost within, depending on pulsatile flow settings used. Conclusions: Herein, we presented the first study to compare hemodynamic energy production with all pulsatile ECLS pump settings and their combinations and widely used yet previously unexamined four different arterial ECMO cannula. Only increased flow rate and amplitude increase hemodynamic energy production as single factors, whilst other factors are relevant when combined. [ABSTRACT FROM AUTHOR]

Background: Hemolysis testing of new devices to treat heart failure is a regulatory requirement. The ASTM F1841–97 standard for hemolysis testing was developed for continuous flow pumps and does not specify test rig design. When research groups use different methodologies, results are difficult to compare. Pulsatile flow pump rigs require compliance chambers, and thus, the Aachen rig (Gräf et al) was developed for the pulsatile Reinheart TAH. The study objective was to use this rig to test the early Realheart TAH prototype V11C hemolysis performance compared to literature. Methods: The experimental control was the continuous flow pump BPX‐80 (Medtronic) and pooled heparinized porcine blood was used. Results: The mgNIH of BPX‐80 and V11C was 5.42 ± 1.47 and 25.20 ± 5.46 mg/100 L, respectively. The NIH ratio of V11C over BPX‐80 was 5.5. Conclusion: The absolute and the relative hemolysis of the V11C are lower compared to both the large and small Reinheart TAH devices published values. Pulsatile pumps create more hemolysis in the Aachen rig, and it is not known if this is because how the rig handles pulsatile flow or due to the devices. Future studies will, therefore, use a pulsatile pump such as the SynCardia as clinical comparator and human blood to test the performance of future Realheart TAH prototypes. [ABSTRACT FROM AUTHOR]

In this work, impacts of dispersing nonspherical shaped cobalt nanoparticles in the blood are analyzed for magnetohydrodynamic radiative transport of blood inside a vertical porous channel. An Oldroyd‐B model is used to feature flow characteristics of blood along with Fourier's principle of heat transmission for the mathematical modeling of the problem. A fractional system is constructed by employing the idea of the Caputo–Fabrizio derivative on subsequent differential equations. The Laplace transform method is adopted to solve the fractional flow and energy equations subject to generalized boundary conditions, which involve time‐dependent functions h(τ) $h(\tau)$ and g(τ) $g(\tau)$, respectively. Instead of promoting the analytic velocity and energy expressions, Zakian's numerical algorithm is operated to achieve the reverse transformation purpose of Laplace domain functions. To certify the obtained solutions, two additional numerical algorithms named Stehfest's algorithm and Durbin's algorithm are inculcated in this study, and comparative illustrations are drawn. For the extensive investigation of shear stress and heat transfer phenomenon, numerical simulations for the coefficient of skin friction and Nusselt number are performed, and outcomes are communicated through various tables. The impacts of shape‐dependent viscosity and other significant parameters on flow patterns are investigated through graphs for multiple motion types of the left channel wall. Meanwhile, the thermal performance of nanofluid is examined for platelet, brick, cylinder, and blade shape nanoparticles, along with other thermal parameters. In addition, some recently reported results and flow profiles for Maxwell, second‐grade, and viscous fluids are deduced graphically as special cases of the current study. [ABSTRACT FROM AUTHOR]

Extracorporeal membrane oxygenation (ECMO) is a life support system used in the treatment of severe respiratory and circulatory failure. High shear stress caused by the high rotational speed of centrifugal blood pumps can cause hemolysis and platelet activation, which are among the major factors leading to the complications of the ECMO system. In this study, a novel blood pump named rotary displacement blood pump (RDBP), which can considerably reduce rotational speed and shear stress while ensuring the normal pressure flow relationship, was proposed. We employed computational fluid dynamics (CFD) analysis to investigate the performance of RDBP under adult ECMO support operating conditions (5 L/min with 350 mmHg). The efficiency and H‐Q curves of the RDBP were calculated to evaluate its hydraulic performance, and pressure, flow patterns, and shear stress distribution were analyzed to estimate the hemodynamic characteristics in the pump. In addition, the modified index of hemolysis (MIH) was calculated for the RDBP based on a Eulerian approach. The hydraulic efficiency of the RDBP was 47.28%. The velocity distribution of flow field in the pump was relatively uniform. Most of the liquid (more than 75%) in the pump was exposed to low scale shear stress (<1 Pa), which was close to normal physiological conditions. The gap area was the main distribution location of high scale shear stress. The high wall shear stress (>9 Pa) volume fraction of the RDBP was small and located in the boundary areas between the rotor's edge and the housing. The MIH value of the RDBP was 9.87 ± 0.93 (mean ± SD). The RDBP can achieve better hydraulic efficiency and hemodynamic performance at lower rotational speed. The design of this novel pump is expected to provide a new direction for developing a blood pump for ECMO. [ABSTRACT FROM AUTHOR]

Background: The effect of pulmonary hypertension (PH) on right ventricular (RV) afterload is commonly defined by elevation of pulmonary artery (PA) pressure or pulmonary vascular resistance (PVR). In humans however, one‐third to half of the hydraulic power in the PA is contained in pulsatile components of flow. Pulmonary impedance (Zc) expresses opposition of the PA to pulsatile blood flow. We evaluate pulmonary Zc relationships according to PH classification using a cardiac magnetic resonance (CMR)/right heart catheterization (RHC) method. Methods: Prospective study of 70 clinically indicated patients referred for same‐day CMR and RHC [60 ± 16 years; 77% females, 16 mPAP <25 mmHg (PVR <240 dynes.s.cm−5/mPCWP <15 mmHg), 24 pre‐capillary (PrecPH), 15 isolated post‐capillary (IpcPH), 15 combined pre‐capillary/post‐capillary (CpcPH)]. CMR provided assessment of PA flow, and RHC, central PA pressure. Pulmonary Zc was expressed as the relationship of PA pressure to flow in the frequency domain (dynes.s.cm−5). Results: Baseline demographic characteristics were well matched. There was a significant difference in mPAP (P < 0.001), PVR (P = 0.001), and pulmonary Zc between mPAP<25 mmHg patients and those with PH (mPAP <25 mmHg: 47 ± 19 dynes.s.cm−5; PrecPH 86 ± 20 dynes.s.cm−5; IpcPH 66 ± 30 dynes.s.cm−5; CpcPH 86 ± 39 dynes.s.cm−5; P = 0.05). For all patients with PH, elevated mPAP was found to be associated with raised PVR (P < 0.001) but not with pulmonary Zc (P = 0.87), except for those with PrecPH (P < 0.001). Elevated pulmonary Zc was associated with reduced RVSWI, RVEF, and CO (all P < 0.05), whereas PVR and mPAP were not. Conclusions: Raised pulmonary Zc was independent of elevated mPAP in patients with PH and more strongly predictive of maladaptive RV remodelling than PVR and mPAP. Use of this straightforward method to determine pulmonary Zc may help to better characterize pulsatile components of RV afterload in patients with PH than mPAP or PVR alone. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a numerical and analytical study of the HIV‐1 infection of CD4+ T‐cells conformable fractional mathematical model. This model is studied analytically by Kudryashov and modified Kudryashov methods and numerically by finite difference method. A comparison between the results of the analytical and numerical methods is investigated. We also give some figures that show how accurate the solutions will be obtained from analytical and numerical methods. [ABSTRACT FROM AUTHOR]

Low‐dimensional (1D or 0D) models can describe the whole human blood circulation, for example, 1D distributed parameter model for the arterial network and 0D concentrated models for the heart or other organs. This paper presents a combined 1D‐0D solver, called first_blood, that solves the governing equations of fluid dynamics to model low‐dimensional hemodynamic effects. An extended method of characteristics is applied here to solve the momentum, and mass conservation equations and the viscoelastic wall model equation, mimicking the material properties of arterial walls. The heart and the peripheral lumped models are solved with a general zero‐dimensional (0D) nonlinear solver. The model topology can be modular, that is, first_blood can solve any 1D‐0D hemodynamic model. To demonstrate the applicability of first_blood, the human arterial system, the heart and the peripherals are modelled using the solver. The simulation time of a heartbeat takes around 2 s, that is, first_blood requires only twice the real‐time for the simulation using an average PC, which highlights the computational efficiency. The source code is available on GitHub, that is, it is open source. The model parameters are based on the literature suggestions and on the validation of output data to obtain physiologically relevant results. [ABSTRACT FROM AUTHOR]

Numerical simulations of pulsatile blood flow in an aortic coarctation require the use of turbulence modeling. This paper considers three models from the class of large eddy simulation (LES) models (Smagorinsky, Vreman, σ‐model) and one model from the class of variational multiscale models (residual‐based) within a finite element framework. The influence of these models on the estimation of clinically relevant biomarkers used to assess the degree of severity of the pathological condition (pressure difference, secondary flow degree, normalized flow displacement, wall shear stress) is investigated in detail. The simulations show that most methods are consistent in terms of severity indicators such as pressure difference and stenotic velocity. Moreover, using second‐order velocity finite elements, different turbulence models might lead to considerably different results concerning other clinically relevant quantities such as wall shear stresses. These differences may be attributed to differences in numerical dissipation introduced by the turbulence models. [ABSTRACT FROM AUTHOR]

Background: Pulsatile extracorporeal circulation (ECC) may improve perfusion of critical organs during cardiac surgery. This study analyzed the influence of the components of a minimal invasive ECC (MiECC) on the transfer of pulsatile energy into the pseudo‐patient of a mock circulation. Methods: An aortic model with human‐like geometry and compliance was perfused by a diagonal pump. Surplus hemodynamic energy (SHE) was determined from flow and pressure data. Five adult‐size oxygenator models and three sizes of cannulas were compared. Pulsatile pump settings were optimized, and parallel dual‐pump configurations were evaluated. Results: Oxygenator models showed up to twofold differences in pressure gradients and influenced SHE at flow rates up to 2.0 L min−1. Adjustments of frequency, systole duration, and rotational speed gain significantly improved SHE compared with empirical settings, with SHE above 21% of mean arterial pressure at flow rates of 1.0 L min−1 to 1.5 L min−1 and SHE above 5% at 3.5 L min−1. Small diameter cannula (15 Fr) limited SHE compared with larger cannula (21 Fr and 23 Fr). Two diagonal pumps did not provide higher SHE than a single pump, but permitted additional control over pulse pressure and SHE by varying the total fraction of pulsatile flow and the fraction of flow bypassing the oxygenator. Conclusions: Proper selection of components and optimizations of pump settings significantly improved pulse pressure and SHE of pulsatile MiECC. Surplus hemodynamic energy depended on flow rate with a maximum at 1.0 L min−1–1.5 L min−1. Pulsatile MiECC may specifically assist organ perfusion during phases of low flow. [ABSTRACT FROM AUTHOR]

The effect of a magnetic field on two‐dimensional pulsatile blood flow in tapered stenosis arteries was studied by employing the Yang transform homotopy perturbation method (YTHPM). The mathematical model which was solved by the researchers Liu and Liu, was successfully developed by adding the effect of a magnetic field for the blood flow in addition to the effect of mass and heat transfer on it. The impact of the angle of tapering, the Grashof number, the solutal Grashof number, and the magnetic field on the axial velocity, the wall shear stress, flow resistance, and the volumetric flow rate was investigated in two cases absence and presence of the magnetic field. The results prove that YTHPM is efficacious and highly accurate in finding the analytical approximate solution for pulsatile blood flow in tapered stenosis arteries under the influence of a magnetic field. The convergence of the new solutions is also discussed in the absence and presence of the magnetic field. Further, the graphs of these new solutions show the validity of, a necessity for, and utility of YTHPM, and are in line with results put forward by other studies. [ABSTRACT FROM AUTHOR]

A great need exists for the development of a more representative in‐vitro model to efficiently screen novel thrombolytic therapies. We herein report the design, validation, and characterization of a highly reproducible, physiological scale, flowing clot lysis platform with real‐time fibrinolysis monitoring to screen thrombolytic drugs utilizing a fluorescein isothiocyanate (FITC)‐labeled clot analog. Using this Real‐Time Fluorometric Flowing Fibrinolysis assay (RT‐FluFF assay), a tPa‐dependent degree of thrombolysis was observed both via clot mass loss as well as fluorometrically monitored release of FITC‐labeled fibrin degradation products. Percent clot mass loss ranged from 33.6% to 85.9% with fluorescence release rates of 0.53 to 1.17 RFU/min in 40 and 1000 ng/mL tPa conditions, respectively. The platform is easily adapted to produce pulsatile flows. Hemodynamics of human main pulmonary artery were mimicked through matching dimensionless flow parameters calculated using clinical data. Increasing pressure amplitude range (4–40 mmHg) results in a 20% increase of fibrinolysis at 1000 ng/mL tPA. Increasing shear flow rate (205–913 s−1) significantly increases fibrinolysis and mechanical digestion. These findings suggest pulsatile level affects thrombolytic drug activities and the proposed in‐vitro clot model offers a versatile testing platform for thrombolytic drug screening. [ABSTRACT FROM AUTHOR]

The motivation of current contribution is to signify the assessment of entropy generation in the flow of generalized Newtonian fluid generated under the influence of electro‐osmosis and peristalsis. The flow has been confined by a tapered channel with certain flow assumptions. The fundamental conservations laws of mass, momentum, energy and concentration along with the Poisson and Nernst‐Planck equations are used to identify the problem in given domain. The Poisson equation is solved analytically for potential function under the Debye‐Huckel linearization approximation while the expressions are attained with association of conservation concept under widely used assumptions of minor Reynolds number and long wavelength. The velocity in axial direction, temperature and nanoparticles profiles are numerically approximated using shooting method. The electric force parameter and radiative constant are being expressed against different flow, temperature and concentration features via various sketches. The results for Newtonian and Carreau fluid as particular case are also presented via numerous plots and tables. It is expected that the obtained theoretical results are very useful for the resilience of medical instatements. [ABSTRACT FROM AUTHOR]

Background: The purpose of this research is to address ongoing device shortfalls for pediatric patients by developing a novel pediatric hybrid total artificial heart (TAH). The valveless magnetically‐levitated MCS device (Dragon Heart) has only two moving parts, integrates an axial and centrifugal blood pump into a single device, and will occupy a compact footprint within the chest for the pediatric patient population. Methods: Prior work on the Dragon Heart focused on the development of pump designs to achieve hemodynamic requirements. The impeller of these pumps was shaft‐driven and thus could not be integrated for testing. The presented research leverages an existing magnetically levitated axial flow pump and focuses on centrifugal pump development. Using the axial pump diameter as a geometric constraint, a shaftless, magnetically supported centrifugal pump was designed for placement circumferentially around the axial pump domain. The new design process included the computational analysis of more than 50 potential centrifugal impeller geometries. The resulting centrifugal pump designs were prototyped and tested for levitation and no‐load rotation, followed by in vitro testing using a blood analog. To meet physiologic demands, target performance goals were pressure rises exceeding 90 mm Hg for flow rates of 1–5 L/min with operating speeds of less than 5000 RPM. Results: Three puck‐shaped, channel impellers for the centrifugal blood pump were selected based on achieving performance and space requirements for magnetic integration. A quasi‐steady flow analysis revealed that the impeller rotational position led to a pulsatile component in the pressure generation. After prototyping, the centrifugal prototypes (3, 4, and 5 channeled designs) demonstrated levitation and no‐load rotation. Hydraulic experiments established pressure generation capabilities beyond target requirements. The pressure‐flow performance of the prototypes followed expected trends with a dependence on rotational speed. Pulsatile blood flow was observed without pump‐speed modulation due to rotating channel passage frequency. Conclusion: The results are promising in the advancement of this pediatric TAH. The channeled impeller design creates pressure‐flow curves that are decoupled from the flow rate, a benefit that could reduce the required controller inputs and improve treatment of hypertensive patients. [ABSTRACT FROM AUTHOR]

Background: Patients on continuous flow ventricular assist devices (CF‐VADs) are at high risk for the development of Acquired von‐Willebrand Syndrome (AVWS) and non‐surgical bleeding. von Willebrand Factor (vWF) plays an essential role in maintaining hemostasis via platelet binding to the damaged endothelium to facilitate coagulation. In CF‐VAD patients, degradation of vWF into low MW multimers that are inefficient in facilitating coagulation occurs and has been primarily attributed to the supraphysiological shear stress associated with the CF‐VAD impeller. Methods: In this review, we evaluate information from the literature regarding the unraveling behavior of surface‐immobilized vWF under pulsatile and continuous flow pertaining to: (A) the process of arterial endothelial vWF production and release into circulation, (B) the critical shear stress required to unravel surface bound versus soluble vWF which leads to degradation, and (C) the role of pulsatility in on the production and degradation of vWF. Results and Conclusion: Taken together, these data suggests that the loss of pulsatility and its impact on arterial endothelial cells plays an important role in the production, release, unraveling, and proteolytic degradation of vWF into low MW multimers, contributing to the development of AVWS. Restoration of pulsatility can potentially mitigate this issue by preventing AVWS and minimizing the risk of non‐surgical bleeding. [ABSTRACT FROM AUTHOR]

This paper numerically investigates the effect of pulsating flow on the settling dynamics of rigid circular particles. This is an interdisciplinary subject and spans several areas ranging from mathematical and numerical modeling to fluid mechanics. For this purpose, pulsatile flow characteristics are embedded in the combination of the direct‐forcing immersed boundary method and the split‐forcing lattice Boltzmann method. Inter‐collision forces between the solid boundaries (particles and boundaries) and the added mass force due to acceleration are considered. Adequate verification tests are done to ensure the credibility of the findings. The critical parameters of pulsating flow, such as amplitude and frequency of pulsation, are investigated in detail. The paper especially puts emphasis on the interaction between particles and studies the well‐known drafting, kissing, and tumbling (DKT) phenomena. Two different scenarios are taken into account and also compared with the stationary flow. The first case is when the pulsating flow is in the direction of gravity (co‐flow), while in the latter, there is an opposing flow (counterflow). The sedimentation manners of 12 particles in a vertical channel are also presented. The findings shed light on the importance of pulsating flow and the extension of the proposed computational method for such problems. It is also revealed that pulsation and its variables can alter DKT by either postponing or speeding up the process. Also, in some cases, the cycle of DKT can be maintained incompletely, and particles would just stick together. The results can be useful for various engineering problems like filtration and particle sorting. [ABSTRACT FROM AUTHOR]