205 research outputs found
Evaluation of EC Comparison on the Determination of 226Ra, 228Ra, 234U and 238U in Mineral Waters
This report describes all details of the comparison for the determination of 226Ra, 228Ra, 234U and 238U in mineral waters among 45 European laboratories monitoring radioactivity in food and the environment. Three commercially available mineral waters were provided as comparison samples. Reference values of the four radionuclides under study in this comparison were determined in collaborative work of IRMM and the Bundesamt für Strahlenschutz (BfS), using tracer techniques and standardised radionuclide solutions. The reference values are thus traceable to the SI units. The sample preparation and measurement processes applied in the participating laboratories are described and the results of the comparison are presented and discussed in detail. Whereas, in general, the measurement results for the uranium isotopes show a relatively favourable agreement with the reference value, the results of this comparison point at severe problems of 226Ra and 228Ra determination in about one fourth and more than one third of the laboratories, respectively. For radium, 19 results corresponding to 14 % of all are even off by a factor of two or more. By comparison, for uranium, this number amounts to 6 % (9 results out of 150). Nevertheless, also for the determination of uranium, 14 % to 23 % of the laboratories report results not compliant with the En evaluation criterion. The corresponding participants are urgently requested to investigate and revise their analytical methods.JRC.D.4-Nuclear physic
Magnetic phase transitions in Ta/CoFeB/MgO multilayers
We study thin films and magnetic tunnel junction nanopillars based on
Ta/CoFeB/MgO multilayers by electrical transport and
magnetometry measurements. These measurements suggest that an ultrathin
magnetic oxide layer forms at the CoFeB/MgO interface. At
approximately 160 K, the oxide undergoes a phase transition from an insulating
antiferromagnet at low temperatures to a conductive weak ferromagnet at high
temperatures. This interfacial magnetic oxide is expected to have significant
impact on the magnetic properties of CoFeB-based multilayers used in spin
torque memories
Preparation and properties of nanostructured magnetic hollow microspheres: experiment and simulation
Atypical work and unemployment protection in Europe
This paper evaluates the degree of income protection the tax-benefit system provides to atypical workers in the event of unemployment. Our approach relies on simulating transitions from employment to unemployment for the entire workforce in EU member states to compare household financial circumstances before and after the transition. Our results show that coverage rates of unemployment insurance are low among atypical workers, who are also more exposed to the risk of poverty, both while in work and in unemployment. Low work intensity employees are characterized by high net replacement rates. However, this is due to the major role played by market incomes of other household members. Finally, we show that in countries where self-employed workers are not eligible for unemployment insurance benefits, extending the eligibility to this group of workers would increase their replacement rates and make them less likely to fall into poverty in the event of unemployment
Enhanced biomedical heat-triggered carriers via nanomagnetism tuning in ferrite-based nanoparticles
Biomedical nanomagnetic carriers are getting a higher impact in therapy and
diagnosis schemes while their constraints and prerequisites are more and more
successfully confronted. Such particles should possess a well-defined size
with minimum agglomeration and they should be synthesized in a facile and
reproducible high-yield way together with a controllable response to an
applied static or dynamic field tailored for the specific application. Here,
we attempt to enhance the heating efficiency in magnetic particle hyperthermia
treatment through the proper adjustment of the core–shell morphology in
ferrite particles, by controlling exchange and dipolar magnetic interactions
at the nanoscale. Thus, core–shell nanoparticles with mutual coupling of
magnetically hard (CoFe2O4) and soft (MnFe2O4) components are synthesized with
facile synthetic controls resulting in uniform size and shell thickness as
evidenced by high resolution transmission electron microscopy imaging,
excellent crystallinity and size monodispersity. Such a magnetic coupling
enables the fine tuning of magnetic anisotropy and magnetic interactions
without sparing the good structural, chemical and colloidal stability.
Consequently, the magnetic heating efficiency of CoFe2O4 and MnFe2O4
core–shell nanoparticles is distinctively different from that of their
counterparts, even though all these nanocrystals were synthesized under
similar conditions. For better understanding of the AC magnetic hyperthermia
response and its correlation with magnetic-origin features we study the effect
of the volume ratio of magnetic hard and soft phases in the bimagnetic
core−shell nanocrystals. Eventually, such particles may be considered as novel
heating carriers that under further biomedical functionalization may become
adaptable multifunctional heat-triggered nanoplatforms
Magnetic hardening of Fe30Co70nanowires
3d transition metal-based magnetic nanowires (NWs) are currently considered as potential candidates for alternative rare-earth-free alloys as novel permanent magnets. Here, we report on the magnetic hardening of FeConanowires in anodic aluminium oxide templates with diameters of 20 nm and 40 nm (length 6 μm and 7.5 μm, respectively) by means of magnetic pinning at the tips of the NWs. We observe that a 3-4 nm naturally formed ferrimagnetic FeCo oxide layer covering the tip of the FeCo NW increases the coercive field by 20%, indicating that domain wall nucleation starts at the tip of the magnetic NW. Ferromagnetic resonance (FMR) measurements were used to quantify the magnetic uniaxial anisotropy energy of the samples. Micromagnetic simulations support our experimental findings, showing that the increase of the coercive field can be achieved by controlling domain wall nucleation using magnetic materials with antiferromagnetic exchange coupling, i.e. antiferromagnets or ferrimagnets, as a capping layer at the nanowire tips.We acknowledge funding from the European Community's Seventh Framework Programme (FP7-NMP) under grant agreement no. 280670 (REFREEPERMAG)
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