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Amorphous Fe- and Co-based alloys possess so-called soft magnetic properties. Due to the high sensitivity of the magnetisation vector to any inhomogeneities occurring in these alloys, it is possible to assess indirectly structural defects. This paper presents the results of research on the structure and magnetic properties of bulk amorphous alloys with a high content of Fe and Co. The magnetic properties of the produced alloys were tested using a Faraday magnetic balance and a vibrating sample magnetometer (VSM). Analysis of the magnetisation process in the region known as the approach to ferromagnetic saturation was carried out in accordance with Kronmüller's theorem. Magnetisation in magnetic fields of greater than the effective anisotropy field (Holstein-Primakoff para-process) was also studied. For the studied alloys, it was found that an increase in Fe content causesan increase in saturation magnetisation, and decreases in the values of the coercive field and thespin-wave stiffness parameter, Dspf. A relationship was observed between the width of the amorphous halo and the value of the coercive field. However, no significant links were found between either the presence of structural defects and the properties of these materials, or between the Co content and the value of the coercive field.

The paper presents the results of research on the structure and magnetic properties of Fe 61+x Co 10-x W 1 Y 8 B 20 alloys (where x = 0, 1 or 2). The alloys were produced using two production methods with similar cooling rates: Injection casting and suction casting. The alloy samples produced were subjected to isothermal annealing at 940 K for 10 min. The structure of the materials was examined using X-ray diffraction. Isothermal annealing has led to the formation of various crystallization products depending on the chemical composition of the alloy and the structure of the alloy in a solidified state. In two cases, the product of crystallization was the hard magnetic phase Y 2 Fe 14 B. However, the mechanism of this phase formation was different in both cases. The magnetic properties of alloys were tested using a vibrating sample magnetometer and a Faraday magnetic balance. It is found that the grain crystallite size of the crystalline phases have a decisive influence on the value of the coercive field (especially in the case of hard magnetic phases). It has been shown that privileged areas can already be created during the production process. Their presence determines the crystallization process., Competing Interests: The authors declare no conflict of interest.

Background: Premature ventricular beats (PVBs) and monomorphic ventricular tachycardia originating from the right ventricular outflow tract (RVOT) are the most frequent forms of idiopathic ventricular arrhythmias, but arrhythmia originating from the left ventricular outflow tract (LVOT) may be found in about 10% of these patients., Aim: To compare electrocardiographic (ECG) patterns and duration of repolarisation after PVBs originating from the left and right superior part of the interventricular septum which were successfully treated with radiofrequency catheter ablation., Methods: We studied 62 patients who did not receive antiarrhythmic drug treatment before ablation, including 50 patients with RVOT arrhythmia (21 males, mean age 42 ± 14 years, left ventricular ejection fraction [LVEF] 61 ± 6%) and 12 patients with LVOT arrhythmia (3 males, mean age 41 ± 17 years, LVEF 59 ± 9%). Pre-ablation 24-h Holter ECG recordings were analysed for the total number of PVBs. In addition, we evaluated ectopic beat QRS duration, prematurity index and duration of repolarisation (QT interval, JT interval and TpeakTend values uncorrected for the heart rate) based on ten random daytime PVBs during a period of stable sinus rhythm at a rate of 60-70 bpm., Results: The study groups did not differ by age, LVEF, heart rate and the number of PVBs. RVOT arrhythmia was characterised by a lower prematurity index (0.59 ± 0.11 vs. 0.72 ± 0.09, p = 0.001) and a lower R/S ratio in leads V1-V3 (p < 0.01 for each lead). QRS duration of right-sided PVBs was shorter compared to that of left-sided PVBs (147 ± 13 vs. 166 ± 13 ms, p = 0.002), QT and JT intervals were similar (QT: 422 ± 32 vs. 429 ± 27 ms, p = 0.35; JT: 272 ± 27 vs. 266 ± 27 ms, p = 0.31), and TpeakTend was shorter in RVOT arrhythmia (100 ± 10 vs. 110 ± 6 ms, p = 0.01). Combination of R > S in lead V3 and TpeakTend-PVB > 110 ms identified LVOT arrhythmia with a sensitivity of 75% and specificity of 96%., Conclusions: Ventricular arrhythmias originating from the left or right superior part of the interventricular septum are not only characterised by different ECG patterns of ventricular ectopic beats but also show significant differences in the repolarisation phase.