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A linear combination of spherically symmetric heat sources is shown to provide optimal stationary thermal distribution in magnetic hyperthermia. Furthermore, such spatial location of heat sources produces suitable temperature distribution in biological medium even for assemblies of magnetic nanoparticles with a moderate value of specific absorption rate (SAR), of the order of 100–150 W/g. We also demonstrate the advantage of using assemblies of spherical magnetic nanocapsules consisting of metallic iron nanoparticles covered with non magnetic shells of sufficient thickness in magnetic hyperthermia. Based on numerical simulation we optimize the size and geometric structure of biocompatible spherical capsules in order to minimize the influence of strong magneto-dipole interaction between closely spaced nanoparticles. It is shown that assembly of capsules can provide sufficiently high SAR values of the order of 250–400 W/g at moderate amplitudes H 0  = 50–100 Oe and frequencies f  = 100–200 kHz of alternating magnetic field, being appropriate for application in clinics.

Detailed calculations of the specific absorption rate (SAR) of a dilute assembly of iron oxide nanoparticles with effective uniaxial anisotropy dispersed in a liquid are performed depending on the particle diameters, the alternating (ac) magnetic field amplitude H 0 and the liquid viscosity. For small and moderate H 0 values with respect to particle anisotropy field H k the SAR of the assembly as a function of the particle diameter passes through a characteristic maximum and then reaches a plateau, whereas for sufficiently large amplitudes, H 0  ~  H k , the SAR increases monotonically as a function of diameter. The realization of viscous and magnetic oscillation modes for particle unit magnetization vector and director for moderate and sufficiently large H 0 values, respectively, explains this behavior. It is found that the SAR of the assembly changes inversely with the viscosity only in a viscous mode, for nanoparticles of sufficiently large diameters. In the magnetic mode the SAR of the assembly is practically independent of the viscosity, since in this case the nanoparticle director only weakly oscillates around the ac magnetic field direction. The conditions for the validity of the linear response theory have been clarified by comparison with the numerical simulation data.

A bstract Thermal light dark matter (LDM) with particle masses in the 1 MeV–1 GeV range could successfully explain the observed dark matter abundance as a relic from the primordial Universe. In this picture, a new feeble interaction acts as a “portal” between the Standard Model and LDM particles, allowing for the exploration of this paradigm at accelerator experiments. In the last years, the “missing energy” experiment NA64 e at CERN SPS (Super Proton Synchrotron) has set world-leading constraints in the vector-mediated LDM parameter space, by exploiting a 100 GeV electron beam impinging on an electromagnetic calorimeter, acting as an active target. In this paper, we report a detailed description of the analysis of a preliminary measurement with a 70 GeV/c positron beam at NA64 e , performed during summer 2023 with an accumulated statistics of 1 . 596 × 10 10 positrons on target (hereafter referred to as e + OT). This data set was analyzed with the primary aim of evaluating the performance of the NA64 e detector with a lower energy positron beam, towards the realization of the post-LS3 program. The analysis results, other than additionally probing unexplored regions in the LDM parameter space, provide valuable information towards the future NA64 e positron campaign.

Glass-coated Co-rich amorphous microwires are very promising for the development of tiny magnetic sensors that can be used in portable electronic devises. In this study, a substantial decrease in the residual quenching stress in Co-rich microwires is achieved by reducing the thickness of the glass coating by means of precise etching of the wire in a specially designed gel. This effect is confirmed experimentally by means of the small-angle magnetization rotation method as well as by direct measurement of the off-diagonal component of the giant magnetoimpedance (GMI) tensor of wires with different thicknesses of glass coating as a function of the applied magnetic field. A reduction in the thickness of the glass coating to the range of 0.5 – 2.0  µ m resulted in a nearly twofold increase in the steepness of the off-diagonal GMI component of the studied Co-rich microwires. Therefore, this method can be used to improve the sensitivity of miniature magnetic sensors to weak external magnetic fields.

Trackers built of straw drift tubes are a perfect solution for precise track measurements in High Energy and Neutrino Physics experiments operating at low and moderate event rate. Straw Trackers will play crucial roles in such future detectors as Near-Detector Complex of the DUNE experiment, Hidden Sector Detector of the SHiP experiment and the NICA SPD detector. Performance requirements on a Tracker and its readout electronics are defined by the Physics goals. Proper evaluation of the designed Tracker performance demands realistic simulation and studies with tracker prototypes. Preliminary results of the muon beam measurements done with straw tube chambers at the CERN SPS test beam line are compared to predictions obtained with GARFIELD simulation package interfaced to LTSpice program for electronics circuit modeling.

Zn is a commonly used alloying element for Mg alloys owing to its beneficial effects on mechanical properties. To improve the mechanical and corrosion properties of WE43B Mg alloys, the effects of 0–0.7wt% Zn addition on the microstructure and properties of sample alloys were investigated. Addition of Zn to as-cast WE43B alloy promoted the formation of the Mg 12 Nd phase; by contrast, after T6 heat treatment, the phase composition of WE43B alloys with and without Zn addition remained mostly the same. A long-period stacking ordered phase was predicted by CALPHAD calculation, but this phase was not observed in either the as-cast or heat-treated Zn-containing WE43B alloys. The optimum temperature and duration of T6 heat treatment were obtained using CALPHAD calculations and hardness measurements. Addition of Zn resulted in a slight reduction in the average grain size of the as-cast and T6 heat-treated WE43B alloys and endowed them with increased corrosion resistance with little effect on their mechanical properties.

A new method for magnetic nano- and submicron-scale particle fabrication is proposed. Magnetic particles of Fe 73 Co 27 alloy were produced by a cavitation process directly into three different liquids: distilled water, benzyl alcohol and methyl methacrylate. The dependency between liquid viscosity and average particle size and size distributions are illustrated. The average particle size is found to be 224 nm in benzyl alcohol and 475 nm in methyl methacrylate. Also, assembly with a size of 20–80 nm was successfully separated from the poly-dispersed mixture obtained in distilled water. Fe 73 Co 27 particles obtained by cavitation inherit the perfect crystal structure of the original macro-sample and possess a high value of the saturation magnetization, M s  = 242 emu/g. These particles can be applied for biomedical purposes and as a component of magneto–polymer composites.

This work studied the effects of adding Zr and Mn in amounts less than 1wt% on the microstructure, mechanical properties, casting properties, and corrosion resistance of Mg—Zn—Cu alloys containing 2.5wt% Cu and 2.5wt%—6.5wt% Zn. The hardness and electrical conductivity measurements were used to find an optimal heat treatment schedule with the best mechanical properties. It has been established that Zr significantly increases the yield strength of the alloys due to a strong grain refinement effect. However, the presence of Mn and Zr has a detrimental effect on alloy’s elongation at fracture. It was shown that the precipitation of the Mg 2 Cu cathodic phase in the alloy structure negatively affects the corrosion behavior. Nevertheless, the addition of Mn decreases the corrosion rate of the investigated alloys. The best combination of the mechanical, casting, and corrosion properties were achieved in the alloys containing 2.5wt% Cu and 5wt% Zn. However, the Mn or Zr addition can improve the properties of the alloys; for example, the addition of Mn or Zr increases the fluidity of the alloys.

Based on a critical analysis of literature data, new model concepts on the mechanism of microarc oxidation (MAO) are developed. The correctness of these model concepts is confirmed by experimental results on the average growth rate of oxide-ceramic coatings for different duration of the MAO process on AД31, MA2-1, and MЛ-5 alloys, the morphology of the surface structure of coatings of different thickness, the comparative electrical strength of dielectric coatings, which is assessed during self-quenching of the MAO process and in air. Equivalent electric circuits developed describe this process and are experimentally shown to be the “tool” which allows controlling MAO of aluminum and magnesium alloys.

The aim of this work is to describe method of modeling straw signal using Garfield++ interface to LTspice. Straw Tube Trackers will be use in the SPD experiment. When designing such large scale and complex detector it is of extreme importance to run precise simulations. The physical task of this research is to reliably predict drift time and shape signal, which is important for further modeling of electronics for SPD Straw Trackers