Wall Motion Research Articles

Preoperative Echocardiographic Assessment in Elective Surgery Patients: A Cross-Sectional Study From Duhok, Iraqi Kurdistan.

Background and aim Echocardiography plays a pivotal role in the preoperative risk assessment of patients undergoing various surgical procedures. Therefore, we conducted this study to detect various cardiac abnormalities through a preoperative echocardiographic study for cases undergoing elective surgeries in Duhok, Iraqi Kurdistan. Methods This cross-sectional study assessed echocardiographic findings in preoperative patients at Azadi Teaching Hospital, Duhok, Kurdistan Region of Iraq, from 2023 to 2024. The study encompasses 468 adult patients. We gathered clinicodemographic characteristics, indications of referral to a preoperative echo study, and the echocardiographic findings, particularly regional wall motion abnormalities, valvular heart diseases, and heart failure (systolic or diastolic/left ventricular hypertrophy). Results In a cohort of 468 patients, 205 (43.80%) were aged 35-54 years, and 269 (57.48%) were female. Most patients (366; 78.21%) resided in Duhok. Nearly only half of the cases 219 (46.79%) had clear preoperative echostudy indications. A total of 289 (61.74%) had no remarkable echocardiographic findings. Diastolic heart failure was most prevalent at 65 (13.89%). Older cases had more prevalent echo findings in terms of valve dysfunctions and heart failure. Notable associations were found between echocardiographic abnormalities and surgical types, particularly higher regional wall motion abnormalities in genito-urinary system operations (4; 8.16%) and valvular heart disease in orthopedic surgeries (13; 15.85%). Conclusions Echocardiographic abnormalities were remarkably observed in patients aged 65 and older. Many cases had no clear indications for preoperative echo study and hence unremarkable echo findings. More scrutiny is indicated during referral, and focusing on older adults' preoperative cardiac screening is recommended.

Stoichiometric and non-stoichiometric Mn modification on high-power properties in PYN-PZT piezoelectric ceramics

The types of dopants lead to distinctive microstructural evolution behavior and physical properties in materials. In this study, the effect of stoichiometric and non-stoichiometric Mn modification, namely Pb(Mn1/3Nb2/3)O3 (PMnN) and MnO2, on the microstructure and properties of Pb(Yb1/2Nb1/2)O3-PbZrO3-PbTiO3 (PYN-PZT) piezoelectric ceramics are systematically investigated. It was found that stoichiometric PMnN modification inhibits the grain growth while non-stoichiometric MnO2 modification promotes it, and thus the former yields stronger high-power characteristics (higher internal bias field Ei and larger mechanical quality factor Qm) than the latter. Specifically, with an equivalent amount of Mn modification (2 mol%), PMnN and MnO2 modification PYN-PZT ceramics exhibit significantly different values for average grain size (1.21 μm vs. 14.12 μm), Ei (8.5 kV/cm vs. 5 kV/cm), and Qm (2376 vs.1134). To further evaluate high-power performance, the vibration velocity v of these two modified PYN-PZT under high driving conditions was measured. Under an AC electric field of 3.5 V/mm, the PYN-PZT+6PMnN ceramics exhibit a v of up to 0.95 m s−1, larger than both MnO2-doped PYN-PZT (0.72 m s−1) and unmodified PYN-PZT ceramics (0.1 m s−1), and far outperformance than both PZT-4 and PZT-8 ceramics. Furthermore, to elucidate the origin of the exceptional high-power performance of PMnN-modified PYN-PZT, we performed phase-field simulations revealing a pinning effect of the grain boundary on domain wall motion. Consequently, the small grain size (high grain boundary density) in PMnN-modified PYN-PZT exhibits a strong pinning effect, resulting in a large Qm and outstanding high-power performance.

Abstract P444: Radial pulse wave velocity measurement method with dual ultrasound probe for low power wearables

Background: Wearables for continuous blood pressure monitoring hold the promise to drastically improve hypertension management, but current solutions still lack the required accuracy. Ultrasounds might be able to overcome this limitation because they can measure quantitative parameters highly correlated with blood pressure, such as artery diameter, its motion over the cardiac cycle (AWM) and local pulse wave velocity (PWV). Here we validate radial PWV measurement with an ultrasound method that can be integrated in low power wearables. Methods: The study was conducted on 8 healthy subjects at rest. The ultrasound scan was performed on the left arm with a research scanner and two linear probes held at a fixed distance and used to image two transversal sections of the radial artery at 11.5 kHz for 10 seconds. The first image of each section is segmented to identify the artery walls and AWM is reconstructed by tracking the phase of the wall echo. PWV is extracted from the delay of artery wall motion waveforms on the 2 sections. Reference values of carotid-radial PWV were acquired with Diatecne PulsePen ETT immediately after the ultrasound acquisition on the same arm. Results: The estimate and accuracy of the local radial PWV of proposed ultrasound method is in agreement with the reference carotid-radial PWV obtained with the tonometer. The accuracy of the methods is estimated from the beat-to-beat variability of the delays between the waves used for the estimates. Conclusions: The proposed method allows to measure the radial pulse wave within shorter distances compatible with integration in wearables. Leveraging TDK ultrasound MEMS platform, this paves the route for low power wearable for continuous cardio-vascular monitoring.

Fe4N soft magnetic composite with ultra-low eddy current loss and excess loss above megahertz

In this study, Fe4N particles were synthesized from pure iron by gas nitridation and then fabricated into soft magnetic composite through silica-polyurethane insulation combined with warm compaction. The composite exhibits excellent soft magnetic properties in the several-megahertz frequency range. The complex permeability spectra of Fe4N composite show a remarkable frequency stability, with the real part remaining nearly constant below 100 MHz. The resonance frequencies of domain wall motion mechanism and spin rotation mechanism are up to 481 MHz and 2.24 GHz, respectively, which are ten times higher than those of Fe composite. Due to the effective suppression of both eddy current loss and excess loss, the total core loss decreases to 725.6 kw/m3 at 3000 kHz and 10 mT, exhibiting almost a linear growth with frequency. These outstanding properties are mainly due to the relatively large magnetocrystalline anisotropy and high resistivity of Fe4N particles. In addition, Fe4N composite also exhibits an excellent DC bias performance, maintaining over 98 % permeability under a superimposed magnetic field of 100 Oe. This study presents an effective solution for suppressing eddy current and excess losses at high frequencies, offering potential for the application of power inductors in high-frequency scenarios.

Bioengineering Approaches and Novel Biomaterials to Enhance Sternal Wound Healing after Cardiac Surgery: A Crosstalk between Innovation and Surgical Practice.

Median sternotomy and steel wires for sternal closure are the standard approach for cardiac surgery. An incomplete repair associated with chest wall motion, especially in the presence of predisposing factors, can lead to life-threatening deep sternal wound infection, also known as mediastinitis, in 2-5% of cases. Despite current antibiotic and surgical treatments, mediastinitis is associated with a 10-40% mortality rate and a significant increase in morbidity and hospital stay. High mortality and difficult treatment appear to be due to bacterial biofilm, a self-produced extracellular polymeric product that incorporates host tissue and is responsible for the failure of immune defenses and standard antimicrobial therapies. Nanostructures are an effective strategy to enhance the healing process, as they establish a favorable environment for the neosynthesis of the extracellular matrix, supporting tissue development. Synthetic polymers have been proven to exhibit suitable biodegradable and mechanical properties, and their biofunctionalization to enhance cell attachment and interaction with the extracellular matrix is being widely investigated. The use of antibiotic treatments suspended in poly-D,L-lactide and polyethylene oxide and electrospun into nanofibers, or in sponges, has been shown to inhibit bacterial biofilm production. Additionally, growth factors can be incorporated into 3D bioresorbable scaffolds with the aim of constituting a structural and biological framework to organize and expedite the healing process. Therefore, these combined approaches may change the treatment of mediastinitis in the near future.

Immediate effects of upper limb exercises with and without deep breathing on lung function after cardiac surgery – a randomized crossover trial

BackgroundOpen heart surgery, involving median sternotomy, may cause diminished chest wall motion and restrictive pulmonary function in the early postoperative period. Thoracic and upper extremity range of motion (ROM) exercises are often recommended after surgery but have not been evaluated regarding effect on lung volumes and oxygenation. The objective of this study was to evaluate the immediate effect of upper limb elevations, with or without simultaneous deep breathing, on lung function after cardiac surgery.MethodsIn a randomized 2 × 2 crossover trial, 22 adult patients (> 18 years old) were assessed during one of the first days after surgery in the spring of 2022 at Örebro University Hospital, Sweden. Exercises involving five bilateral upper limb elevations, performed either with simultaneous deep breathing (ROM-DB) or without (ROM), while sitting in an upright position at the edge of the bed, were evaluated. Peripheral oxygen saturation (Rad-5v; Masimo, Irvine, USA) was the primary outcome. Tidal volume and respiratory rate were recorded continuously during the exercises (Spiropalm; Cosmed, Rome, Italy). Heart rate, pain, exertion and dyspnoea were evaluated before and after the exercises.ResultsBoth ROM-DB and ROM momentarily increased peripheral oxygen saturation (+ 1% ± 1, p = 0.004 and + 1% ± 1, p < 0.001, respectively), with no significant differences between these exercises (p = 0.525). ROM-DB significantly increased the VT compared with ROM (798 ± 316 vs. 602 mL ± 176, p = 0.004). However, ROM-DB induced more pronounced pain (p = 0.012), exertion (p = 0.035) and dyspnoea (p = 0.013) than ROM.ConclusionsUpper limb elevations improved oxygenation momentarily, both performed with and without simultaneous deep breathing, with no significant differences between these exercises. The additive deep breathing improved tidal volume compared with upper limb elevations alone, but induced more pain, exertion and dyspnoea during the performance of exercise.Trial registrationClinicalTrials.gov (NCT05278819).

Computational modeling of left ventricular flow using PC-CMR-derived four-dimensional wall motion.

Intracardiac hemodynamics plays a crucial role in the onset and development of cardiac and valvular diseases. Simulations of blood flow in the left ventricle (LV) have provided valuable insight into assessing LV hemodynamics. While fully coupled fluid-solid modelings of the LV remain challenging due to the complex passive-active behavior of the LV wall myocardium, the integration of imaging-driven quantification of structural motion with computational fluid dynamics (CFD) modeling in the LV holds the promise of feasible and clinically translatable characterization of patient-specific LV hemodynamics. In this study, we propose to integrate two magnetic resonance imaging (MRI) modalities with the moving-boundary CFD method to characterize intracardiac LV hemodynamics. Our method uses the standard cine cardiac magnetic resonance (CMR) images to estimate four-dimensional myocardial motion, eliminating the need for involved myocardial material modeling to capture LV wall behavior. In conjunction with CMR, phase contrast-MRI (PC-MRI) was used to measure temporal blood inflow rates at the mitral orifice, serving as an additional boundary condition. Flow patterns, including velocity streamlines, vortex rings, and kinetic energy, were characterized and compared to the available data. Moreover, relationships between LV wall kinematic markers and flow characteristics were determined without myocardial material modeling and using a non-rigid image registration (NRIR) method. The fidelity of the simulation was quantitatively evaluated by validating the flow rate at the aortic outflow tract against respective PC-MRI measures. The proposed methodology offers a novel and feasible toolset that works with standard PC-CMR protocols to improve the clinical assessment of LV characteristics in prognostic studies and surgical planning.

Left Ventricular Wall Motion as an Additional Valuable Parameter in Diabetic Patients with Normal Myocardial Perfusion Imaging.

Gated SPECT is an established technique for assessment of left ventricular function in cardiovascular disease patients. However, there is little information about the influence of diabetes mellitus on gated SPECT parameters. This study was established to assess gated SPECT parameters in Diabetes Mellitus (DM) and non-diabetes mellitus (non-DM) patients with normal Myocardial Perfusion Imaging (MPI). In this analytical cross-sectional study, 314 patients (157 DM, 157 non-DM) with normal MPI were enrolled. Prevalence of risk factors for CAD like hypertension (HTN), and dyslipidemia were found to be significantly higher (p <0.01) in DM patients compared to non-DM. No statistically significant difference was observed among the TID, ESV, EDV, PFR, TTPF, and Wall Thickness (WT) parameters between DM and non-DM patients. Wall motion (Wm) in DM patients was significantly higher compared to non-DM patients. (3.9 ± 0.51 vs. 2.69 ± 0.48 for DM and non-DM patients, respectively, p-value:0.01). Also, there was no significant difference in Wm in the two groups with and without HTN. This shows the independent effect of DM on the Wm. This study believes that the Wm parameter should be noted for the early diagnosis or prevention of heart disease in DM patients. These findings can indicate the gradual changes in the movements of the left ventricle and the beginning of the progression of diabetic cardiomyopathy.

Sickle Cell Disease Revealed by Simultaneous Occurrence of Acute Coronary Syndrome and Pulmonary Embolism: A Case Report

The simultaneous occurrence of acute coronary syndrome (ACS) and pulmonary embolism (PE) in patients with sickle cell disease (SCD) presents notable diagnostic and management challenges. This case report describes a 25-year-old woman with SCD who, after an uncomplicated laparoscopic cholecystectomy, developed acute retrosternal chest pain, severe dyspnea, and tachycardia. Diagnostic workup included several key methods: thoracic CT angiography was performed, revealing massive bilateral pulmonary embolism and a pulmonary infarct. Echocardiography demonstrated myocardial abnormalities, such as wall motion defects and a mildly reduced ejection fraction. Electrocardiography showed ST-segment depression and T-wave inversions in the anteroseptal leads. To confirm the presence of coronary artery disease, coronary angiography identified significant thrombotic stenosis in the proximal left anterior descending artery. Sickle cell disease was confirmed through a positive sickle cell test, which identified the characteristic hemoglobin S. Despite aggressive treatment, the patient’s condition rapidly deteriorated, leading to death within 24 hours. This case underscores the critical role of a comprehensive diagnostic approach, including specific tests for SCD, in managing severe cardiovascular complications and highlights the need for tailored treatment strategies to improve patient outcomes.

Direction of Spontaneous Processes in Non-Equilibrium Systems with Movable/Permeable Internal Walls.

We consider three different systems in a heat flow: an ideal gas, a van der Waals gas, and a binary mixture of ideal gases. We divide each system internally into two subsystems by a movable wall. We show that the direction of the motion of the wall, after release, under constant boundary conditions, is determined by the same inequality as in equilibrium thermodynamics dU-đQ≤0. The only difference between the equilibrium and non-equilibrium laws is the dependence of the net heat change, đQ, on the state parameters of the system. We show that the same inequality is valid when introducing the gravitational field in the case of both the ideal gas and the van der Waals gas in the heat flow. It remains true when we consider a thick wall permeable to gas particles and derive Archimedes' principle in the heat flow. Finally, we consider the Couette (shear) flow of the ideal gas. In this system, the direction of the motion of the internal wall follows from the inequality dE-đQ-đWs≤0, where dE is the infinitesimal change in total energy (internal plus kinetic) and đWs is the infinitesimal work exchanged with the environment due to the shear force imposed on the flowing gas. Ultimately, we synthesize all these cases within a general framework of the second law of non-equilibrium thermodynamics.

Coronary Events Following Dobutamine Stress Cardiac Magnetic Resonance Imaging in Pediatric Patients.

Dobutamine stress cardiac magnetic resonance (dsCMR) has demonstrated value in identifying patients at risk for adverse cardiovascular events in adults with coronary artery disease, but its prognostic value in younger patients is unknown. This study sought to evaluate the relationship between dsCMR results and the risk of subsequent cardiovascular events in children. Patients age < 23years who underwent dsCMR at Boston Children's Hospital were eligible for inclusion. Patients were excluded if no follow-up data were available after dsCMR or the dsCMR protocol was not completed. Data regarding the presence of inducible regional wall motion abnormalities and subsequent cardiovascular events during follow-up were analyzed. Cardiovascular events included myocardial infarction, surgical or catheter-based coronary artery intervention, and ischemic symptoms. Among 80 dsCMR studies in 64 patients with median age 5.3years (range 0.5-22.4years), 3 patients had a positive dsCMR with inducible regional wall motion abnormalities. Over a median follow-up of 7.4years (IQR 4.0-11.2), 2 of these patients underwent surgical intervention (coronary artery bypass grafting and unroofing of a myocardial bridge) and the third remained asymptomatic with no interventions. Among 61 patients with a negative dsCMR, none experienced myocardial infarction, death, or aborted sudden death. Four underwent cardiac interventions (cardiac transplantation, coronary artery bypass grafting, and unroofing) due to symptoms or catheterization findings. In pediatric patients undergoing dsCMR, wall motion abnormalities indicating inducible ischemia were uncommon. Those with a negative dsCMR were unlikely to experience an adverse cardiac event or undergo a cardiac intervention on medium-term follow-up.

Improvement on Qm in high-power piezoelectric ceramics through [111]c texture engineering

Improving mechanical quality factor Qm is of great significance for high-power applications. Here, a new strategy of the [111]c texture engineering was proposed to enhance the performances of high-power piezoelectric ceramics. The 5 vol% BaTiO3 (BT) templates with the [111]c preferred orientation were introduced into matrix powders of 0.03 Pb(Mn1/3Nb2/3)O3–0.33Pb(Ni1/3Nb2/3)O3–0.28 PbZrO3–0.36PbTiO3 (28PZ(R)) to form the [111]c textured ceramics (28PZ(T)), possessing a texture degree of 74 %. The multiple of uniform density in EBSD increased from 0.63 in randomly oriented 28 PZ(R) to 6.63 in 28PZ(T). The good lattice matching between BT templates and textured grains was observed using high-resolution transmission electron microscopy, confirming the microscopic origin of the [111]c texture. The maximum phase angle θmax of 88.2° was quite near 90° in 28PZ(T), ensuring the optimal Qm value of 1275 and the great figure of merit of 255,000 pC/N. The increased Qm in [111]c texture ceramics was confirmed due to the reduced intrinsic polarization directions rather than the pinning effect of the internal bias field. Larger grain sizes with larger domains restrained the movement of domain walls in 28 PZ(T), which was also favorable to higher Qm. This work may provide a new promising route for further high-power applications.

Allergy, infarction, and stress cardiomyopathy: in-depth analysis of a complex clinical case report

Abstract Background Diagnosis of Kounis syndrome, an acute coronary syndrome associated with anaphylactic reactions, is challenging owing to the overlapping symptoms of myocardial ischemia. Takotsubo syndrome (TTS), characterized by stress-induced cardiomyopathy, may share pathophysiological mechanisms with Kounis syndrome and potentially coexist in the same patient. Case Presentation We present a case of a 63-year-old patient who developed an allergic reaction to contrast medium administration, leading to dyspnea and chest pain. Electrocardiography revealed a new-onset left bundle-branch block, and echocardiography indicated wall motion abnormalities with apical ballooning, suggestive of TTS. Coronary angiography displayed a chronic total occlusion of the right coronary artery. Laboratory tests revealed elevated inflammatory markers, supporting the diagnosis of Kounis syndrome and TTS. Conclusion This case highlights the challenges of diagnosing and managing type II Kounis syndrome associated with concurrent TTS. This underscores the need for tailored therapeutic interventions and comprehensive guidelines to address these complex conditions effectively.

On-board synthetic 4D MRI generation from 4D CBCT for radiotherapy of abdominal tumors: A feasibility study.

Magnetic resonance-guided radiotherapy with an MR-guided LINAC represents potential clinical benefits in abdominal treatments due to the superior soft-tissue contrast compared to kV-based images in conventional treatment units. However, due to the high cost associated with this technology, only a few centers have access to it. As an alternative, synthetic 4D MRI generation based on artificial intelligence methods could be implemented. Nevertheless, appropriate MRI texture generation from CT images might be challenging and prone to hallucinations, compromising motion accuracy. To evaluate the feasibility of on-board synthetic motion-resolved 4D MRI generation from prior 4D MRI, on-board 4D cone beam CT (CBCT) images, motion modeling information, and deep learning models using the digital anthropomorphic phantom XCAT. The synthetic 4D MRI corresponds to phases from on-board 4D CBCT. Each synthetic MRI volume in the 4D MRI was generated by warping a reference 3D MRI (MRIref, end of expiration phase from a prior 4D MRI) with a deformation field map (DFM) determined by (I) the eigenvectors from the principal component analysis (PCA) motion-modeling of the prior 4D MRI, and (II) the corresponding eigenvalues predicted by a convolutional neural network (CNN) model using the on-board 4D CBCT images as input. The CNN was trained with 1000 deformations of one reference CT (CTref, same conditions as MRIref) generated by applying 1000 DFMs computed by randomly sampling the original eigenvalues from the prior 4D MRI PCA model. The evaluation metrics for the CNN model were root-mean-square error (RMSE) and mean absolute error (MAE). Finally, different on-board 4D-MRI generation scenarios were assessed by changing the respiratory period, the amplitude of the diaphragm, and the chest wall motion of the 4D CBCT using normalized root-mean-square error (nRMSE) and structural similarity index measure (SSIM) for image-based evaluation, and volume dice coefficient (VDC), volume percent difference (VPD), and center-of-mass shift (COMS) for contour-based evaluation of liver and target volumes. The RMSE and MAE values of the CNN model reported 0.012±0.001 and 0.010±0.001, respectively for the first eigenvalue predictions. SSIM and nRMSE were 0.96±0.06 and 0.22±0.08, respectively. VDC, VPD, and COMS were 0.92±0.06, 3.08±3.73 %, and 2.3±2.1mm, respectively, for the target volume. The more challenging synthetic 4D-MRI generation scenario was for one 4D-CBCT with increased chest wall motion amplitude, reporting SSIM and nRMSE of 0.82 and 0.51, respectively. On-board synthetic 4D-MRI generation based on predicting actual treatment deformation from on-board 4D-CBCT represents a method that can potentially improve the treatment-setup localization in abdominal radiotherapy treatments with a conventional kV-based LINAC.

Feasibility of capturing vessel expansion with 4D-CTA: Phantom study to determine reproducibility, spatial and temporal resolution.

Dynamic Computed Tomography Angiography (4D CTA) has the potential of providing insight into the biomechanical properties of the vessel wall, by capturing motion of the vessel wall. For vascular pathologies, like intracranial aneurysms, this could potentially refine diagnosis, prognosis, and treatment decision-making. The objective of this research is to determine the feasibility of a 4D CTA scanner for accurately measuring harmonic diameter changes in an in-vitro simulated vessel. A silicon tube was exposed to a simulated heartbeat. Simulated heart rates between 40 and 100 beats-per-minute (bpm) were tested and the flow amplitude was varied, resulting in various changes of tube diameter. A 320-detector row CT system with ECG-gating captured three consecutive cycles of expansion. Image registration was used to calculate the diameter change. A vascular echography set-up was used as a reference, using a 9MHz linear array transducer. The reproducibility of 4D CTA was represented by the Pearson correlation (r) between the three consecutive diameter change patterns, captured by 4D CTA. The peak value similarity (pvs) was calculated between the 4D CTA and US measurements for increasing frequencies and was chosen as a measure of temporal resolution. Spatial resolution was represented by the Sum of the Relative Percentual Difference (SRPD) between 4D CTA and US diameter change patterns for increasing amplitudes. The reproducibility of 4D CTA measurements was good (r ≥ 0.9) if the diameter change was larger than 0.3mm, moderate (0.7 ≤ r<0.9) if the diameter change was between 0.1 and 0.3mm, and low (r<0.7) if the diameter change was smaller than 0.1mm. Regarding the temporal resolution, the amplitude of 4D CTA was similar to the US measurements (pvs ≥ 90%) for the frequencies of 40 and 50bpm. Frequencies between 60 and 80bpm result in a moderate similarity (70% ≤ pvs<90%). A low similarity (pvs<70%) is observed for 90 and 100bpm. Regarding the spatial resolution, diameter changes above 0.30mm result in SRPDs consistently below 50%. In a phantom setting, 4D CTA can be used to reliably capture reproducible tube diameter changes exceeding 0.30mm. Low pulsation frequencies (40 or 50bpm) provide an accurate measurement of the maximum tube diameter change.

Takotsubo Syndrome: Differences between Peripartum Period and General Population.

Takotsubo syndrome (TTS) was first described in postmenopausal women with transient regional wall motion abnormalities. The trigger is usually an emotional or physical stress. The catecholamine hypothesis seems to be the most prevailing. The main difference between TTS and acute coronary syndromes is that there is no obstructive coronary disease to explain the regional abnormalities. In this form, the left ventricle resembles the fishing jar which is used to trap octopus in Japan. However, to date more atypical forms are recognized. Also, the syndrome is not limited to older women. Nowadays, TTS is presented even in pregnancy and postpartum females. Our experience revealed cases of patients during these periods and some of them suffered from reverse Takotsubo. Additionally, the initial diagnosis in some patients was other than TTS. Due to these findings, we suggest that this type of TTS is not very rare but underestimated. For this reason, further studies are needed to support and explain this condition.

Effect of airway wall motion on particle deposition and delivery in the neonatal trachea

Modeling pulmonary drug delivery in the airway using computational fluid dynamics (CFD) simulations tracks drug particles throughout the airway, providing valuable information on the deposition location of inhaled drugs. However, most studies simulate particle transport within static airway models that do not incorporate physiological airway motion; this choice limits accuracy since airway motion directly affects particle transport and deposition, notably in newborns with airway abnormalities such as tracheomalacia. The objective of this study is to determine the effect of airway motion on drug delivery in neonates with and without airway disease. For this study, two control subjects without any airway disease and three subjects with tracheomalacia (dynamic tracheal narrowing) were enrolled. Each subject was imaged at approximately 40-weeks post-menstrual age using magnetic resonance imaging (MRI). MRI data were retrospectively reconstructed to obtain static airway images gated to different time points of the breath (i.e., end expiration and end inspiration) and an image representing combined data from all timepoints (ungated). Virtual airway surfaces (pharynx to main bronchi) were made from each MR image. A moving airway surface was created from surface registration of these surfaces and used as the boundary for a CFD simulation of one inhalation, along with subject-specific inspiratory flow waveforms. To assess the effect of airway wall motion on particle deposition, static-walled simulations, based on the airway surfaces at end inspiration, end expiration, and the ungated airway surface, were also performed using the same flow boundary conditions. Particle transport (particles diameter range 0.5–15 μm) was compared between the simulations during the inhalation. Airway surface motion affected particle transport into the small airways by 65% on average (0.5–5 μm– 22%, 5-15 μm– 86%) compared to static-walled simulations, while comparison between static end expiration and other static-walled simulations using geometries acquired during different phases of breathing differed by more than 500% on average (0.5–5 μm– 45%, 5-15 μm– 741%). For particle deposition, airway surface motion affected by 43% on average (0.5–5 μm– 86%, 5-15 μm– 21%) compared to static-walled simulations and comparison between static end expiration and other static-walled simulations differed by 47% on average (0.5–5 μm– 58%, 5-15 μm– 41%). Differences between dynamic and static deposition results and between static simulations from different timepoints occurred in patients with and without airway disease. This study suggests the importance of using airway wall motion in CFD simulations to model aerosolized drug delivery in the airway. If a CFD simulation is limited to only a static airway image without physiological motion, particle deposition mapping may yield markedly inaccurate results, potentially resulting in higher or lower drug dosing than intended.

Optimized strain property in Sm3+ doped 0.67BiFeO3-0.33BaTiO3 ceramics by electric field induced lattice distortion and domain wall motion

BiFeO3-BaTiO3 based ceramics with good piezoelectric properties and high Curie temperature are potential candidates for high temperature piezoelectric actuators. In this study, a high strain value of about 0.376 % and the low strain hysteresis of 13.3 % achieved in 0.67Bi1-xSmxFeO3-0.33BaTiO3 (0.1 ≤ x ≤ 2.0) ceramics. The contribution from the E-induced nanodomains and/or PNRs wall motion by fine-tuning Sm3+ contributes the increased strain; The contribution from the converse piezoelectric effect and the electrostrictive effect enhanced with the increase of x, due to the enlarged lattice shrinkage by replacing Sm3+ with small ionic radius and subsequent lattice distortion under high electric field. The strategy to simultaneously enhance the E-induced lattice distortion and nanodomains and/or PNRs wall motion of strain and balance their fractions to reduce the strain hysteresis may provide new insights to meet the practical applications of high-precision displacement actuators.

Fast fabrication of a hierarchical nanostructured multifunctional ferromagnet.

Materials with multifunctionality affect society enormously. However, the inability to surmount multiple functionality trade-offs limits the discovery of next-generation multifunctional materials. Departing from conventional alloying design philosophy, we present a hierarchical nanostructure (HNS) strategy to simultaneously break multiple performance trade-offs in a material. Using a praseodymium-cobalt (PrCo5) ferromagnet as a proof of concept, the resulting HNS outperforms contemporary high-temperature ferromagnets with a 50 to 138% increase in electrical resistivity while achieving their highest energy density. Our strategy also enables an exceptional thermal stability of coercivity (-0.148%/°C)-a key characteristic for device accuracy and reliability-surpassing that of existing commercial rare-earth magnets. The multifunctionality stems from the deliberately introduced nanohierarchical structure, which activates multiple micromechanisms to resist domain wall movement and electron transport, offering an advanced design concept for multifunctional materials.

Effect of void geometry and magnetic anisotropy in controlling the vortex in sub-micron annular Permalloy disc

Ferromagnetic rings, particularly asymmetric Permalloy (Py) rings are recognized as promising configurations for spintronic devices, offering additional degrees of freedom for manipulating magnetic states, especially in vortex configurations. Through micromagnetic simulations, our study explores the impact on magnetization states and spin configuration concerning ring symmetry, aligning with the interest in controlling vortex states for information storage. We initially obtained zero-field spin configurations by varying ring thickness (t), observing a 360° domain wall in rings with t < 12 nm and bi-vortex wall in rings with t ∼36 nm during magnetization reversal. Notably, an extended stability of the global-vortex state was observed in rings with t > 36 nm, indicating the dominance of global-vortex nucleation in thick asymmetric rings during domain wall movement. We investigate the hysteresis loops and spin configurations by varying the in-plane and out-of-plane anisotropy values. Our findings reveal the presence of multiple vortex cores with different polarities and sense of rotations in the ring for the in-plane anisotropy ∼30 to ∼40 kJ m−3. Additionally, a global-vortex with two vortex cores was formed due to demagnetization energy. We analysed the energy profile of stable magnetization states for various t and anisotropy values. Interestingly, the shape of the hysteresis loop changes significantly for the disc containing different shapes of void. Circular and square-shaped geometries suggest that the bi-vortex state is a stable configuration during magnetization reversal in both cases. The study also indicates the stability of the vortex with a square-shaped void geometry up to a sufficiently large field. For the case of triangular-shaped voids, the global-vortex state was favored with even the small fields. The estimated spin canting angles are found to be correlated with the presence of vortex spin configurations. Overall, these results are important for the development of magnetization vortex-based spintronics devices.