1,305 research outputs found
Funktionelle Herzklappen-Stent Designs fĂĽr zukĂĽnftige autologe, transkatheter Klappenprothesen in pulmonaler Position
Background Transcatheter pulmonary valve replacement (TPVR) has asserted its position as a cornerstone in cardiology and become a nonsurgical alternative for patients with a dysfunctional right ventricular outflow tract (RVOT), demonstrating excellent early and late clinical outcomes. Short- and long-term complications of TPVR include stent fracture and migration, coronary compression, and valve regurgitation.
Objective The purpose of this study is to describe methodology for developing Nitinol stents by conducting a computational design and finite element analysis in conjunction with 3D reconstruction of animal cardiac CT for TPVR.
Methods 3D cardiac CT reconstruction was achieved using 3D Slicer, from which the RVOT + pulmonary artery (PA) was exported for blood flow simulation and hoop force acquisition with the stents. Functional stents were designed using Autodesk Fusion 360 and divided into three morphological geometries: group 1–straight tubular stents, group 2–corollaceous stents, and group 3–corollaceous stents with an elliptic geometry. Stent simulations for stent life and radial force, and the hoop force of the stent during expansion with the RVOT+PA model were obtained in Ansys. The blood flow simulation of RVOT+PA was performed using Ansys with the velocity-based coupled solver.
Results 3D cardiac CT reconstructions were obtained in STL format, from which the right ventricle (RV) +PA model was performed for the blood flow simulation and the hoop force was obtained with the stents. Twelve functional stents were successfully designed and exported in SAT and STP formats for simulation. All stent life (Times)/radial force (N) were achieved: Group 1 comprised the stents DGS 3 (3219.2/1.88E+05), DGS 5 (16406/1.94E+05), DGS 7 (1.00E+06/1.89E+05), DGS 8B (0/3.74E+05), DGS-10B (8370.1/2.41E+05), DGS 12D (1.00E+06/2.41E+08); Group 2 comprised the stents DGS 8A (0/3.60E+05), DGS 9A (0/3.60E+05), DGS 10A (46093/2.28E+05), DGS 12C (2.50E+005/1.69E+05); Group 3 comprised the stents DGS 12A (1.00E+06/2.38E+08), DGS 12B (54509/2.20E+05). Hoop force (N) was obtained from the 12 stents: Group 1–DGS 5 (57802), DGS 7 (54647), DGS 8B (53248), DGS 10B (56650), DGS 12D (46297). Group 2–DGS 8A (50490), DGS 9A (60393), DGS 10A (23639), DGS 12C (29802). Group 3–DGS 12A (16368), DGS 12B (16368). The RV+PA blood flow simulation demonstrated that the anterior part of the PA wall had the largest shear force.
Conclusions DGS 12C, DGS 12D, DGS 10A, DGS 10B, DGS 7, and DGS 5 can be subsequently tested in vitro. Autologous pulmonary valves could be sutured onto the functional stents to maintain their original geometry prior to implantation. Pre-implantation 3D CT reconstruction and stent simulation can be performed for better evaluation and visualization. The RV+PA blood flow simulation may serve as a significant input for the design of stents and pulmonary valve to determine the shear force throughout the cardiac cycle.Hintergrund Der katheterbasierte Pulmonalklappenersatz ist ein Eckpfeiler der
Kardiologie und bietet zudem eine nicht-chirurgische Alternative fĂĽr die Behandlung
funktionsgestörter rechtsventrikulärer Ausflusstrakte oder bioprothetischer Klappen mit
hervorragenden frühen und späten klinischen Ergebnissen. Kurz- und langfristige
Komplikationen von TPVR umfassen Stentfraktur/-migration, Komprimierung der
Koronararterien und Klappeninsuffizienz.
Ziel Ziel dieser Studie ist es, die Methodik und das Konzept fĂĽr Nitinol-Stents mithilfe
rechnerischer EntwĂĽrfe und Finite-Elemente-Analysen anhand von 3D-Rekonstruktionen
kardialer CT-Untersuchungen in Tieren fĂĽr die Anwendung von TPVR zu beschreiben.
Methoden Die 3D-Rekonstruktion der CT-Untersuchungen erfolgte mit der Software
3D Slicer, aus der die RVOT und Pulmonalarterie (PA) in Verbindung mit den Stents fĂĽr
die Blutflusssimulation und die Umfangsspannung exportiert wurde. Die funktionellen
Stents wurden mit Fusion 360 entworfen und danach in die Formate SAT und STP
exportiert. Simulationen fĂĽr die Lebensdauer und Radialkraft sowie fĂĽr die
Umfangsspannung der Stents bei der Freisetzung mit dem RVOT+PA-Modell wurden in
Ansys berechnet. Die Blutflusssimulation von RVOT+PA wurde in Ansys mit dem
geschwindigkeitsbasierten gekoppelten Solver durchgefĂĽhrt.
Ergebnisse Zwölf funktionelle Stents wurden mithilfe von Fusion 360 generiert. SAT- und
STP-Dateien wurden zur Simulation in Ansys exportiert. 3D Kardio-CT-Rekonstruktionen
wurden mithilfe im STL-Format kreiert, aus dem das RVOT+PA-Modell des Prä-CT
ausgewählt wurde, um die Blutflusssimulation durchzuführen und die Ringkraft der Stents
zu erhalten. Die Lebensdauer (Anzahl) und Radialkraft (N) der Stents wurden wie folgt
berechnet: DGS-3 (3219.2/1.88E+05), DGS-5 (16406/1.94E+05), DGS-7
(1.00E+06/1.89E+05), DGS-8A (0/3.60E+05), DGS-8B (0/3.74E+05), DGS-9A
(0/3.60E+05), DGS-10A (46093/2.28E+05), DGS-10B (8370.1/2.41E+05), DGS-12A
(1.00E+06/2.38E+08), DGS-12B (54509/2.20E+05), DGS-12D (1.00E+06/2.41E+08),
DGS-12C (2.50E+005/1.69E+05). Die jeweilige Umspannungskraft (N) wurde wie folgt
berechnet: DGS-5 (57802), DGS-7 (54647), DGS-8A (50490), DGS-8B (53248), DGS-9A
(60393), DGS-10A (23639), DGS-10B (56650), DGS-12A (16368), DGS-12B (16368),
DGS-12C (29802), DGS-12D (46297). Die RV+PA-Blutflusssimulation zeigte, dass der
vordere Teil der PA-Wand die größte Scherkraft aufwies.
Schlussfolgerungen DGS-12C, DGS-12D, DGS-10A, DGS-10B, DGS-7 und DGS-5
können nachfolgend in vitro getestet werden. Autologe Pulmonalklappen können zur Erhaltung der ursprünglichen Geometrie vor der Implantation auf funktionelle Stents
aufgenäht werden. Vor der Implantation können Kardio-CT 3D-Rekonstruktion und
Stentsimulationen zur besseren Bewertung und Visualisierung durchgefĂĽhrt werden. Die
Blutflusssimulation von RVOT+PA kann einen bedeutsamen Beitrag zur Gestaltung von
Stents und Pulmonalklappen leisten, um die Scherkraft während des gesamten
Herzzyklus zu erhalten
Wireless Power Transfer: Survey and Roadmap
Wireless power transfer (WPT) technologies have been widely used in many areas, e.g., the charging of electric toothbrush, mobile phones, and electric vehicles. This paper introduces fundamental principles of three WPT technologies, i.e., inductive coupling-based WPT, magnetic resonant coupling-based WPT, and electromagnetic radiation-based WPT, together with discussions of their strengths and weaknesses. Main research themes are then presented, i.e., improving the transmission efficiency and distance, and designing multiple transmitters/receivers. The state-of-the-art techniques are reviewed and categorised. Several WPT applications are described. Open research challenges are then presented with a brief discussion of potential roadmap
Research on an alternative method of turbine motor signal
In the modern mortar radio fuze, the use of turbine generators as the power source for fuzes is very common. The ballistic air pressure during the flight of the projectiles is used as the driving force to drive the turbine motor. In this paper, the turbine motor signal is parameterized in combination with the actual situation, and the idea of using the hardware to simulate the turbine power generation is proposed. The generation of the turbine motor signal is simulated by means of simulation software. Design the circuit to verify the simulation results, and have a certain reference for how to easily detect the fuze in the mass production process
Oxidative stress alters cell morphology and cell death indices in immortalized astrocytes
Abstract only availableMenadione, usually known as vitamin K3, also serves as a trigger for oxidative stress, delivering reactive oxygen species (ROS) upon entering the cells. Astrocytes are glial cells that are found in the brain and are extremely important in providing nourishment to cells in the brain, especially neurons. Oxidative stress may cause damage to astrocytes and alter their function. Increase in oxidative stress is the underlying cause for many neurodegenerative diseases like Alzheimer's disease and stroke. In this study, we used menadione as an oxidant compound to study effects of oxidative stress on cell morphology and viability in an immortalized astrocyte cell line (DITNC). Menadione causes cytoskeletal rearrangement and stress fiber protrusions in astrocytes. This event is accomplished by an increase in LDH release and a decrease in MTT release, suggesting loss of cell viability. Resveratrol (enriched in grape) and curcumin (from turmeric), polyphenolic antioxidants, have been shown to inhibit damage caused by ROS. In this study, we also used these botanical compounds to demonstrate their inhibitory properties against menadione-mediated morphological changes and cell damage in DITNC cells.NSF-REU Biology & Biochemistr
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