FORC-Diagram Analysis for a Step-like Magnetization Reversal in Nanopatterned Stripe Array

The fabrication approach of a magnonic crystal with a step-like hysteresis behavior based on a uniform non-monotonous iron layer made by shadow deposition on a preconfigured substrate is reported. The origin of the step-like hysteresis loop behavior is studied with local and integral magnetometry methods, including First-Order Reversal Curves (FORC) diagram analysis, accompanied with magnetic microstructure dynamics measurements. The results are validated with macroscopic magnetic properties and micromagnetic simulations using the intrinsic switching field distribution model. The proposed fabrication method can be used to produce magnonic structures with the controllable hysteresis plateau region’s field position and width that can be used to control the magnonic crystal’s band structure by changing of an external magnetic field.

Assessment of histological characteristics, imaging markers, and rt-PA susceptibility of ex vivo venous thrombi

Venous thromboembolism is a significant source of morbidity and mortality worldwide. Catheter-directed thrombolytics is the primary treatment used to relieve critical obstructions, though its efficacy varies based on the thrombus composition. Non-responsive portions of the specimen often remain in situ, which prohibits mechanistic investigation of lytic resistance or the development of diagnostic indicators for treatment outcomes. In this study, thrombus samples extracted from venous thromboembolism patients were analyzed ex vivo to determine their histological properties, susceptibility to lytic therapy, and imaging characteristics. A wide range of thrombus morphologies were observed, with a dependence on age and etymology of the specimen. Fibrinolytic inhibitors including PAI-1, alpha 2-antiplasmin, and TAFI were present in samples, which may contribute to the response venous thrombi to catheter-directed thrombolytics. Finally, a weak but significant correlation was observed between the response of the sample to lytic drug and its magnetic microstructure assessed with a quantitative MRI sequence. These findings highlight the myriad of changes in venous thrombi that may promote lytic resistance, and imaging metrics that correlate with treatment outcomes.

Composition and Thrombolytic Susceptibility of Ex Vivo Venous Thromboembolism

Venous thromboembolism is a significant source of morbidity and mortality worldwide. Catheter-directed thrombolytics is the primary treatment used to relieve critical obstructions, though its efficacy varies based on the thrombus composition. Non-responsive portions of the specimen often remain in situ, which prohibits mechanistic investigation of lytic resistance or the development of diagnostic indicators for treatment outcomes. In this study, thrombus samples extracted from venous thromboembolism patients were analyzed ex vivo to determine their histological structure, lytic susceptibility, and imaging characteristics. A wide range of thrombus morphologies were observed, with a dependence on age and etymology of the specimen. The lytic inhibitor PAI-1 was present in samples, and may contribute to the lytic resistance of venous thrombi. Finally, a correlation was observed between the lytic response of the sample and its magnetic microstructure assessed with a quantitative MRI sequence. These findings highlight the myriad of changes in venous thrombi that may promote lytic resistance, and imaging metrics that correlate with treatment outcomes.

Basics of Static Micromagnetism

Chapter 3 introduces the continuum expressions for the magnetic energy contributions, which are employed for describing the mesoscale magnetic microstructure of magnetic materials. It is then shown how the static equations of micromagnetics, the so-called Brown's equations, can be solved in the high-field regime and how the Fourier components of the magnetization are related to the magnetic SANS cross section.

Rapid Annealing Optimizing Magnetic Softness and Thermal Stability of Mn-Substituted Fe-Based Nanocrystalline Alloys

Good high-frequency magnetic softness and thermal stability are very important for the wide application of Fe-based nanocrystalline alloys. The present work reports the influence of Mn-doping and rapid annealing on the magnetic softness, nano-structure, and magnetic-microstructure of Fe76−xSi13B8Nb2Cu1Mnx (x = 0, 1, 2, 3, and 4) alloys. It was found that the Fe74Si13B8Nb2Cu1Mn2 alloy exhibits a superior magnetic softness with the high-saturation magnetic induction of 1.32 T and a large permeability at 100 kHz of over 15,000 at a large annealing-temperature region of 120 °C. The microstructure and magnetic domains characterization indicate that the good magnetic softness and thermal stabilization can be ascribed to the superb nano-structural stability caused by the Mn doping and rapid annealing at elongated temperatures, which can maintain a fine and high number density α-Fe(Si) nano-grains and facilitate the formation of regular and wide domains.