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3. Influence of the external magnetic field on structural characteristics of granular Co-Cu thin film alloys

Author

Hrebynakha, V., Plecenik, T., Satrapinskyy, L., Ruban, A. I., Pak, V. Ya, Shkurdoda, Yu, Shvets, U., Nakonechna, I., Lyfar, S., Vorobiov, S., Komanicky, V., Kozlova, L., Kravets, Anatolii, Shpetnyy, I., Hrebynakha, V., Plecenik, T., Satrapinskyy, L., Ruban, A. I., Pak, V. Ya, Shkurdoda, Yu, Shvets, U., Nakonechna, I., Lyfar, S., Vorobiov, S., Komanicky, V., Kozlova, L., Kravets, Anatolii, and Shpetnyy, I.

Abstract

We present the results of experimental studies of the influence of an external magnetic field on the structural characteristics (surface roughness and structural entropy) of nanogranular thin-film system based on Co and Cu. The samples CoxCu100-x in a wide range of compositions (17 at. % ≤ x ≤ 69 at. %) with the thickness of d = 35 nm were obtained by electron-beam co-evaporation using two independent electron guns. After obtaining, the films were annealed in a vacuum at a temperature of 800 K for 30 min. The studies of magnetoresistive properties have shown that the maximum giant magnetoresistance (GMR) amplitude (1.7 % in the transverse and 1.6 % in the longitudinal measurement geometries) in a magnetic field of H = 4.5 kOe at room temperature was observed in the Co21Cu79 film alloy. Transmission electron microscopy showed that this sample contains hcp-Co granules with a size of L = 5 ÷ 12 nm in a matrix of metastable fcc-Cu(Co) solid solution. The influence of the external magnetic field on the structural characteristics and surface morphology of the Co21Cu79 thin-film alloy was investigated using atomic force microscopy (AFM). It was found that a first impact of application of external magnetic field with H = 0.5 kOe causes a decrease in the values of the arithmetic mean Ra, and quadratic mean Rq, of the film roughness and structural entropy S. A decreases in Ra by 8.5 %, Rq by 6.5 %, and structural entropy S by 6.5 % were observed. After application of a larger magnetic field with H = 1.0 kOe and during the subsequent relaxation of the structure within 15 h after the field is turned off, the values of the structural parameters of the film surface did not change significantly., QC 20240823

Published
2024
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41. Long-term assessment of clinical outcomes and disease progression in patients with corrected Tetralogy of Fallot

Author

Ali, L. A., Gentili, F., Festa, P., Perrone, M. A., Curione, D., Caputo, M., Wald, R., Secinaro, A., Carotti, A., Chinali, M., Marrone, C., Pak, V., Federici, D., Gagliardi, M. G., Bianco, Massimiliano, Galletti, L., Drago, F., and Leonardi, B.

Subjects
Adult, Male, Cardiac magnetic resonance, Adolescent, Ventricular Dysfunction, Right, Age Factors, Arrhythmias, Cardiac, Stroke Volume, Magnetic Resonance Imaging, Young Adult, Settore M-EDF/01 - METODI E DIDATTICHE DELLE ATTIVITÀ MOTORIE, Risk Factors, Repaired tetralogy of Fallot, Disease Progression, Tetralogy of Fallot, Ventricular Function, Right, Right ventricle, Humans, Female, Child, Follow-Up Studies
Abstract

Understanding changes of right ventricular (RV) geometry and function in repaired Tetralogy of Fallot (rToF) patients can improve decision-making for pulmonary valve replacement. Therefore, we aimed to assess the magnitude and clinical correlations of RV changes in rToF patients.Clinical and MRI data of rToF patients who underwent repeated cardiac magnetic resonance imaging (MRI) at two centers between December 2003 and September 2020 were analyzed together with anatomical factors, including RV outflow tract obstruction, pulmonary artery branch stenosis, and tricuspid regurgitation. Adverse cardiac events and/or NYHA class worsening were documented and correlated with MRI changes. QRS length was reported at each MRI.Two-hundred-and-nineteen rToF patients (53% males, aged 20.2 ± 10.1 years) were enrolled. An increase of ventricular dimensions, except LVEDVi, and worsening of right and left ejection fractions were found over an average period of 5 years of follow-up. These changes were statistically significant but within 10% of the initial value. No significant changes were reported on a year-to-year basis, except in a small group of patients (6%) in whom no predictive factors were identified. Despite similar RV dimensions at the first examination, younger patients had a higher RV ejection fraction and a different annual rate of change of ventricular dimensions compared to older ones. Patients with arrhythmias (20%) were more frequently older and had larger RV dimensions but showed no significant correlations with MRI changes/years. Changes in RV dimensions and function occur rarely and very slowly in rToF patients. A small percentage of patients experience a significant worsening in a short time interval without any recognized risk factors. Arrhythmias appear to occur in a small percentage of cases in the late follow-up.

Published
2021

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