Thermal relaxation of magnetic clusters in amorphous Hf_{57}Fe_{43} alloy

The magnetization processes in binary magnetic/nonmagnetic amorphous alloy Hf_{57}Fe_{43} are investigated by the detailed measurements of magnetic hysteresis loops, temperature dependence of magnetization, relaxation of magnetization and magnetic ac susceptibility, including a nonlinear term. Blocking of magnetic moments at lower temperatures is accompanied with the slow relaxation of magnetization and magnetic hysteresis loops. All of the observed properties are explained with the superparamagnetic behaviour of the single domain magnetic clusters inside the nonmagnetic host, their blocking by the anisotropy barriers and thermal fluctuation over the barriers accompanied by relaxation of magnetization. From magnetic viscosity analysis based on thermal relaxation over the anisotropy barriers it is found out that magnetic clusters occupy the characteristic volume from 25 up to 200 nm3 . The validity of the superparamagnetic model of Hf_{57}Fe_{43} is based on the concentration of iron in the Hf_{100-x}Fe_{43} system that is just below the threshold for the long range magnetic ordering. This work throws more light on magnetic behaviour of other amorphous alloys, too

Superparamagnetic relaxation in Cu_{x}Fe_{3-x}O_{4} (x=0.5 and x=1) nanoparticles

The scope of this article is to report very detailed results of the measurements of magnetic relaxation phenomena in the new Cu$_{0.5}$Fe$_{2.5}$O$_{4}$ nanoparticles and known CuFe$_{2}$O$_{4}$ nanoparticles. The size of synthesized particles is (6.5$\pm$1.5)nm. Both samples show the superparamagnetic behaviour, with the well-defined phenomena of blocking of magnetic moment. This includes the splitting of zero-field-cooled and field-cooled magnetic moment curves, dynamical hysteresis, slow quasi-logarithmic relaxation of magnetic moment below blocking temperature. The scaling of the magnetic moment relaxation data at different temperatures confirms the applicability of the simple thermal relaxation model. The two copper-ferrites with similar structures show significantly different magnetic anisotropy density and other magnetic properties. Investigated systems exhibit the consistency of all obtained results.Comment: 18 pages, 8 figure

Enhancement of flux pinning in neutron irradiated MgB2 superconductor

m-H loops for virgin and neutron irradiated bulk and powder samples of MgB_2 were measured in the temperature range 5-30 K in magnetic field B £ 1 T. The irradiation at thermal neutron fluences 9·10^13 and 4.5·10^14 cm^-2 caused very small enhancement of m-H loops at lower temperatures (T < 20 K), whereas the effect at high temperatures was unclear due to the difficulty in achieving exactly the same measurement temperature prior and after irradiation. However, the irradiation at 4.5·10^15 cm^-2 produced clear enhancement of m-H loops (hence J_c) at all investigated temperatures, which provides the evidence for the enhancement of flux pinning in MgB_2 due to ion tracks resulting from n+^10B reaction. The potential of this technique for the enhancement of flux pinning in high temperature superconductors is briefly discussed

Pojačanje zapinjanja magnetskih vrtloga u neutronima ozračenom supravodiču MgB2

m − H loops for virgin and neutron irradiated bulk and powder samples of MgB2 were measured in the temperature range 5 − 30 K in magnetic field B ≤ 1 T. The irradiation at thermal neutron fluences 9 · 1013 and 4.5 · 1014 cm−2 caused very small enhancement of m − H loops at lower temperatures (T < 20 K), whereas the effect at high temperatures was unclear due to the difficulty in achieving exactly the same measurement temperature prior and after irradiation. However, the irradiation at 4.5 · 1015 cm−2 produced clear enhancement of m − H loops (hence Jc) at all investigated temperatures, which provides the evidence for the enhancement of flux pinning in MgB2 due to ion tracks resulting from n+10B reaction. The potential of this technique for the enhancement of flux pinning in high temperature superconductors is briefly discussed.Ozračivanje termičkim neutronima do 9 · 1013 i 4.5 · 1014 n/cm2 uzrokovalo je vrlo malo proširenje m−H krivulja na nižim temperaturama (T < 20 K), dok je učinak na višim temperaturama nejasan zbog poteškoće da se postigne točna jednakost mjerne temperature prije i poslije ozračivanja. Ozračivanje na 4.5 · 1015 n/cm2 uzrokovalo je jasno proširenje m − H krivulja na svim temperaturama, što ukazuje da ionski tragovi nastali n+10B reakcijom pojačavaju zapinjanje linija magnetskog toka u MgB2. Kratko se razmatra prikladnost tog postupka za pojačanje zapinjanja linija toka u visokotemperaturnim supravodičima

Elastic Scattering for the 11Be+64Zn System Close to the Coulomb Barrier

The quasi-elastic scattering angular distribution of the collision 11Be + 64Zn was measured and compared with the elastic scattering angular distribution for its core, the 10Be nucleus on the same target. Optical model and continuum-discretized coupled-channel calculations of the 11Be+64Zn reaction were performed in order to interpret the effect of coupling with the break-up channels on the measured cross-sections

Reference materials (RMs) for analysis of the human factor II (prothrombin) gene G20210A mutation

The Scientific Committee of Molecular Biology Techniques (C-MbT) in Clinical Chemistry of the IFCC has initiated a joint project in co-operation with the European Commission, Joint Research Centre, Institute of Reference Materials and Measurements to develop and produce plasmid-type reference materials (RMs), for the analysis of the human prothrombin gene G20210A mutation. Although DNA tests have a high impact on clinical decision-making and the number of tests performed in diagnostic laboratories is high, issues of quality and quality assurance exist, and currently only a few RMs for clinical genetic testing are available. A gene fragment chosen was produced that spans all primer annealing sites published to date. Both the wild-type and mutant alleles of this gene fragment were cloned into a pUC18 plasmid and two plasmid RMs were produced. In addition, a mixture of both plasmids was produced to mimic the heterozygous genotype. The present study describes the performance of these reference materials in a commutability study, in which they were tested by nine different methods in 13 expert laboratories.. This series of plasmid RMs are, to the best of our knowledge, the first plasmid-type clinical genetic RMs introduced worldwide

Developing a patient decision aid for Achilles tendon rupture management: a mixed-methods study

Objective To develop and user-test a patient decision aid portraying the benefits and harms of non-surgical management and surgery for Achilles tendon ruptures.Design Mixed methods.Setting A draft decision aid was developed using guidance from a multidisciplinary steering group and existing patient decision aids. Participants were recruited through social media.Participants People who have previously sustained an Achilles tendon rupture and health professionals who manage these patients.Primary and secondary outcomes Semi-structured interviews and questionnaires were used to gather feedback on the decision aid from health professionals and patients who had previously suffered an Achilles tendon rupture. The feedback was used to redraft the decision aid and assess acceptability. An iterative cycle of interviews, redrafting according to feedback and further interviews was used. Interviews were analysed using reflexive thematic analysis. Questionnaire data were analysed descriptively.Results We interviewed 18 health professionals (13 physiotherapists, 3 orthopaedic surgeons, 1 chiropractor, 1 sports medicine physician) and 15 patients who had suffered an Achilles tendon rupture (median time since rupture was 12 months). Most health professionals and patients rated the aid’s acceptability as good-excellent. Interviews showcased agreement among health professionals and patients on most aspects of the decision aid: introduction, treatment options, comparing benefits and harms, questions to ask health professionals and formatting. However, health professionals had differing views on details about Achilles tendon retraction distance, factors that modify the risk of harms, treatment protocols and evidence on benefits and harms.Conclusion Our patient decision aid is an acceptable tool to both patients and health professionals, and our study highlights the views of key stakeholders on important information to consider when developing a patient decision aid for Achilles tendon rupture management. A randomised controlled trial evaluating the impact of this tool on the decision-making of people considering Achilles tendon surgery is warranted