Ordering of [alpha]-FeCo phase in the nanocrystalline Fe83-xCoxNb3B13Cu1 (x = 6, 25 or 41.5) alloys

The microstructure and ordering of α-FeCo phase of the nanocrystalline Fe83−xCoxNb3B13Cu1 (x = 6, 25 or 41.5) alloys were investigated. We have stated that α-FeCo phase is atomically ordered in the Fe83−xCoxNb3B13Cu1 (x = 25 or 41.5) samples crystallized by the heat treatment in a furnace. However, after flash annealing (by current or laser) that phase is disordered. Moreover, we have found that Co concentration in the crystalline α-FeCo phase strongly depends on Co content in the as-quenched ribbons. The annealing conditions influence also the grain diameter of the crystalline phase. In the nanocrystalline alloys obtained by a flash annealing of the amorphous ribbons finer grains are present

Nanocrystallization studies of rapidly quenched Fe85.4-xCoxZr6.8-yNbyB6.8Cu1 (x=0 or 42.7, y=0 or 1) alloys

The microstructure of amorphous and nanocrystalline Fe42.7Co42.7Zr6.8−xNbxB6.8Cu1 (x = 0 or 1) alloys was investigated. We have stated that the nanocrystalline samples consist of the crystalline α-FeCo grains about 8 nm in diameter embedded in an amorphous matrix which is rich in cobalt. From Mössbauer spectroscopy studies we have found that the crystalline α-FeCo phase in the nanocrystalline samples obtained by the conventional annealing is atomically ordered. Moreover, the order degree depends on the annealing time. As for the samples partially crystallized during rapid quenching, the crystalline α-FeCo phase is atomically disordered

Mechanical thrombectomy in acute stroke – Five years of experience in Poland

Objectives Mechanical thrombectomy (MT) is not reimbursed by the Polish public health system. We present a description of 5 years of experience with MT in acute stroke in Comprehensive Stroke Centers (CSCs) in Poland. Methods and results We retrospectively analyzed the results of a structured questionnaire from 23 out of 25 identified CSCs and 22 data sets that include 61 clinical, radiological and outcome measures. Results Most of the CSCs (74%) were founded at University Hospitals and most (65.2%) work round the clock. In 78.3% of them, the working teams are composed of neurologists and neuro-radiologists. All CSCs perform CT and angio-CT before MT. In total 586 patients were subjected to MT and data from 531 of them were analyzed. Mean time laps from stroke onset to groin puncture was 250±99min. 90.3% of the studied patients had MT within 6h from stroke onset; 59.3% of them were treated with IV rt-PA prior to MT; 15.1% had IA rt-PA during MT and 4.7% – emergent stenting of a large vessel. M1 of MCA was occluded in 47.8% of cases. The Solitaire device was used in 53% of cases. Successful recanalization (TICI2b–TICI3) was achieved in 64.6% of cases and 53.4% of patients did not experience hemorrhagic transformation. Clinical improvement on discharge was noticed in 53.7% of cases, futile recanalization – in 30.7%, mRS of 0–2 – in 31.4% and mRS of 6 in 22% of cases. Conclusion Our results can help harmonize standards for MT in Poland according to international guidelines

Microstructure and Some Magnetic Properties of Nanocrystalline Fe73.5−x{{_{73.5-x}}}Cox{_x}Cu1\mathsf{_1}Nb3\mathsf{_3}Si13.5\mathsf{_{13.5}}B9\mathsf{_9} Alloys

The microstructure and magnetic properties, i.e. the initial susceptibility, coercivity and saturation magnetic polarization of nanocrystalline Fe$_{73.5-x}$Co$_x$Cu$_1$Nb$_3$Si$_{13.5}$B$_9$ ($x = 0$ or 7) alloys with different volume fractions of crystalline and amorphous phases, are investigated. The crystalline phase in both conventionally annealed alloys (823 K for 1 h) has DO$_3$ ordered structure. However, after the accumulative annealing of the samples (823 K for 5 s and then 10 and 60 min) only short range order in the crystalline phase is observed. The replacing of 7% Fe atoms by Co atoms in the Fe$_{73.5}$Cu$_1$Nb$_3$Si$_{13.5}$B$_9$ alloy leads to the slight enhancement of the magnetic saturation polarization for both as-quenched and nanocrystalline samples. Moreover, the initial susceptibility distinctly increases and disaccommodation as well as coercivity decrease with annealing time for both investigated alloys. This behaviour is attributed to the annealing out of free volumes in the amorphous matrix and the increase of the volume fraction of the crystalline phase. Furthermore, the results reported in this paper indicate that processes occurring in the amorphous matrix are the main source of the magnetic after-effect in these alloys

Hyperfine interaction and some thermomagnetic properties of amorphous and partially crystallized Fe70−xMxMo5Cr4Nb6B15 (M = Co or Ni, x = 0 or 10) alloys

As revealed by Mössbauer spectroscopy, replacement of 10 at.% of iron in the amorphous Fe70Mo5Cr4Nb6B15 alloy by cobalt or nickel has no effect on the magnetic structure in the vicinity of room temperature, although the Curie point moves from 190 K towards ambient one. In the early stages of crystallization, the paramagnetic crystalline Cr12Fe36Mo10 phase appears before α-Fe or α-FeCo are formed, as is confirmed by X-ray diffractometry and transmission electron microscopy. Creation of the crystalline Cr12Fe36Mo10 phase is accompanied by the amorphous ferromagnetic phase formation at the expense of amorphous paramagnetic one

Effects of Co, Ni, and Cr addition on microstructure and magnetic properties of amorphous and nanocrystalline Fe86−xMxZr7Nb2Cu1B4 (M = Co, Ni, CoCr, and Cr, x = 0 or 6) alloys

Mössbauer spectra and thermomagnetic curves for the Fe86−xMxZr7Nb2Cu1B4 (M = Co, Ni, CoCr, and Cr, x = 0 or 6) alloys in the as-quenched state and after the accumulative annealing in the temperature range 600–800 K for 10 min are investigated. The parent Fe86Zr7Nb2Cu1B4 amorphous alloy is paramagnetic at room temperature, and substitution of 6 at.% of Fe by Co, Ni, and CoCr changes the magnetic structure – the alloys become ferromagnetic, whereas replacing 6 at.% of Fe with Cr preserves the paramagnetic state. After the heat treatment at 600 K, the decrease of the average hyperfine field induction, as compared to the as-quenched state, is observed due to the invar effect. After this annealing, the Curie temperature for all investigated alloys decreases. The accumulative annealing up to 800 K leads to the partial crystallization; α-Fe or α-FeCo grains with diameters in the range of 12–30 nm in the residual amorphous matrix appear

Mechanical thrombectomy in acute stroke : five years of experience in Poland

Objectives: Mechanical thrombectomy (MT) is not reimbursed by the Polish public health system. We present a description of 5 years of experience with MT in acute stroke in Comprehensive Stroke Centers (CSCs) in Poland. Methods and results: We retrospectively analyzed the results of a structured questionnaire from 23 out of 25 identified CSCs and 22 data sets that include 61 clinical, radiological and outcome measures. Results: Most of the CSCs (74%) were founded at University Hospitals and most (65.2%) work round the clock. In 78.3% of them, the working teams are composed of neurologists and neuro-radiologists. All CSCs perform CT and angio-CT before MT. In total 586 patients were subjected to MT and data from 531 of them were analyzed. Mean time laps from stroke onset to groin puncture was 250 99 min. 90.3% of the studied patients had MT within 6 h from stroke onset; 59.3% of them were treated with IV rt-PA prior to MT; 15.1% had IA rt-PA during MT and 4.7% - emergent stenting of a large vessel. M1 of MCA was occluded in 47.8% of cases. The Solitaire device was used in 53% of cases. Successful recanalization (TICI2b–TICI3) was achieved in 64.6% of cases and 53.4% of patients did not experience hemorrhagic transformation. Clinical improvement on discharge was noticed in 53.7% of cases, futile recanalization - in 30.7%, mRS of 0–2 - in 31.4% and mRS of 6 in 22% of cases. Conclusion: Our results can help harmonize standards for MT in Poland according to international guideline