Characteristic and photocatalytic performance of magnetic photocatalyst β-Bi2O3/MnxZn1−xFe2O4 synthesized by hydrothermal and calcination method

A magnetic photocatalyst [Formula: see text]-Bi2O3/Mn[Formula: see text]Zn[Formula: see text]Fe2O4 (Bi2O3/MZF) was fabricated by hydrothermal and calcination method, and characterized by XRD, FTIR, XPS and SEM, BET and VSM. The photocatalytic efficiency was measured by the degradation experiment of Rhodamine B (RhB). The degradation rate of the optimum sample Bi2O3/MZF (10 wt.%) could reach 96.8% after 3 h under visible light, and was improved significantly compared with pure [Formula: see text]-Bi2O3 due to the larger pore size (11.76 nm) and specific surface area (17.87 m2 ⋅ g[Formula: see text]. Meanwhile, the Bi2O3/MZF (10 wt.%) could be recovered under the external magnetic field due to its high magnetization saturation (9.22 emu ⋅ g[Formula: see text]. After reusing three times, the Bi2O3/MZF could still maintain the excellent photocatalytic activity and structural stability.

Stabilizing Zero-Field Skyrmions at Room-Temperature in Perpendicularly Magnetized Multilayers

Magnetic skyrmions are twirling spin structures observed in bulk, thin films, and multilayers with several features for both fundamental physics understanding and spintronic applications, i.e., nanoscale size, efficient transport under electrical current, and topological protection against defects. However, most magnetic skyrmions have been observed under the assistance of an out-of-plane magnetic field, which may limit their use in magnetic memory technologies. In this chapter, we review and present two recent mechanisms to create zero-field skyrmions at room-temperature in ferromagnetic multilayers. First, by tuning the perpendicular magnetic anisotropy (PMA) and remnant magnetization (near magnetization saturation) in unpatterned symmetric multilayer systems, it was achieved a transition from worm-like domains to isolated skyrmions. Besides, we present how to find stable zero-field skyrmions in arrays of ferrimagnetic discs by tailoring their diameter. Both methods demonstrate a robust route to stabilize zero-field skyrmions at room temperature, thus providing an important contribution to possible applications of these textures in the next generation of skyrmionics devices.

Влияние нелинейности закона намагничивания феррожидкости на неустойчивость Кельвина--Гельмгольца

We study Kelvin-Helmholtz instability which develops when a homogenous gas flow is moving over a horizontal surface of a ferrofluid of given physical properties moving in the same direction, in presence of a homogeneous magnetic field parallel to this direction. Magnetic field intensity range includes the values that correspond to the interval where magnetization curve reaches magnetization saturation level. Stability area is constructed in the “magnetic field intensity – dimensionless relative velocity of fluids” parameter plane.

Effects of NaOH Concentration and Temperature on Microstructures and Magnetic Properties of Bismuth Ferrite (BiFeO3) Nanoparticles Synthesized by Coprecipitation Method

Bismuth ferrite (BiFeO3) nanoparticles has been synthesized by coprecipitation method with various NaOH concentration (4, 6, 8, and 10 M) and temperature (RT, 60, 80, and 100 C). X-ray diffraction patterns showed the emergence of Bi(OH)3 and Bi25FeO40 structures with crystallite size in the range of 15.1 nm to 35.6 nm. The particles sample was agglomerated. Hysterisis loop showed the linear M–H loops behaviour with no magnetization saturation in 15 kOe maximum field applied which indicates the antiferromagnetic properties. The coercivity field tends to increase by the increasing of the NaOH concentration and synthesis temperature. In addition, the annealing treatment could leads the increasing of coercivity fields while decreasing the magnetization of BFO sampel.

Characterization of Carbonic Anhydrase In Vivo Using Magnetic Resonance Spectroscopy

Carbonic anhydrase is a ubiquitous metalloenzyme that catalyzes the reversible interconversion of CO2/HCO3−. Equilibrium of these species is maintained by the action of carbonic anhydrase. Recent advances in magnetic resonance spectroscopy have allowed, for the first time, in vivo characterization of carbonic anhydrase in the human brain. In this article, we review the theories and techniques of in vivo 13C magnetization (saturation) transfer magnetic resonance spectroscopy as they are applied to measuring the rate of exchange between CO2 and HCO3− catalyzed by carbonic anhydrase. Inhibitors of carbonic anhydrase have a wide range of therapeutic applications. Role of carbonic anhydrases and their inhibitors in many diseases are also reviewed to illustrate future applications of in vivo carbonic anhydrase assessment by magnetic resonance spectroscopy.

MECHANOSYNTHESIS, CRYSTAL STRUCTURE, MAGNETIC AND ABSORPTION PROPERTIES OF Al SUBSTITUTED BaFe12O19

The Aluminums (Al) substituted on M-type barium ferrite (BaFe12O19) is one of the magnetic materials, which can be applied to the microwave band working at high frequencies. The purpose of this paper is to investigate the effect of Al substitution for Fe3+ ions on the structure, magnetic and absorption behavior of M-type barium ferrite. The sample was prepared by mechano-synthesis using high-energy milling (HEM). In this research, Fe ion in BaFe12O19 was substituted by Al ion to form BaFe12-xAlxO19 for x = 0.0,BaFe10Al2O19 for x = 2.0 and BaFe8Al4O19 for x = 4.0 which is called as BAl-0, BAl-2 and BAl-4 sample, respectively. The stainless steel balls were used for the milling with a ball-to-powder sample ratio of 5. The mixing and milling for each the sample was conducted for 5 hours in ethanol medium and dried at 100oC in oven for 24 hours and then followed by heat treatment at 1100°C during 1h in the atmosphere media. The sample was characterized using X-rays diffractometer (XRD), Scanning Electron Microscope (SEM), Vibrating Sample Magnetometer (VSM) and Vector Network Analyzer (VNA). The result indicates that the addition of Al ion lead to the change cell parameters, volume, and the particles size. The magnetic behavior such as magnetic coercivity (Hc), magnetization saturation (Ms) and remanent (Mr) changed significantly with the substitution of Al ions. The optimum reflection loss (RL) is found to be –35dB at 14GHz for BaFe10Al2O19 (BAl-2) sample. It is shown that Al substitutions change the particle size, ferromagnetic resonant frequency, and structural and magnetic behavior of M-type barium ferrite.

Effects of zinc contents and calcination temperature on the structure and magnetic properties of Co1-xZnxFe2O4 nanomaterials synthesized by co-precipitation

Nanomaterials of cobalt ferrite (CoFe2O4) doped with zinc have been synthesized by co-precipitation using KOH solution of 10-4 M as a precipitant. The effect of zinc contents and calcination temperature on the structure and magnetic properties of Co1-xZnxFe2O4 were studied. The parameters of the crystalline cubic lattice (a ~ 8.4 Å) and the crystalline size (d = 20–30 nm) increased with increasing the calcination temperature and zinc content in the samples. However, the remanent magnetization, saturation magnetization, coercive force and M at the maximum field decreased with increasing the zinc content. The nanomaterials of cobalt ferrite doped with zinc have Hc values in the range of 8.67–179.63 Oe, Mr values in the range of 1.33–16.90 emu/g, which are quite smaller than those of original CoFe2O4 material (Hc=497.89 Oe, Mr=36.29 emu/g); moreover, the nanomaterials prepared have Ms values in the range of 56.00 – 99.97 emu/g, which are similar to those of original CoFe2O4 material (Ms= 88.67 emu/g) and are quite higher than those of original ZnFe2O4 material (Ms ~ 1.2 emu/g).

Effect of Hydrogen on the Structure, Magnetic and Magnetocaloric Properties of Laves Phase Type-Compounds RE(Fe0.25Co0.75)2Hy with RE = Ho and Er, y = 0.0, 3.0, 3.5

The crystal structure and overall magnetic properties of RE(Fe0.25Co0.75)2Hywith RE = Ho and Er, were analyzed versus y, the hydrogen content. The single phase C15 type compounds, synthesized using cold crucible HF melting, were hydrogenated and controlled using a PCI apparatus. The impact of hydrogen insertion on the cell parameter, the Curie temperature TCand the magnetization saturation were determined. All compounds and hydrides were found to be ferrimagnets, the magnetic moment of RE and 3d elements being opposite since Ho and Er belong to the 2ndrow of rare earth elements. Depending on the formula, a typical compensation point was in evidence. The 2ndorder character of the ferri ↔ paramagnetic transition was established using the Arrott plot method. Magnetization isotherms vs. magnetic field gives quantified results for the magnetic entropy variation by application of the Maxwell relation. Control of y, the hydrogen content, shows it is interesting for improvement of the MCE of the starting compounds. However increasing y leads to decreased TCat the lowest temperatures, suggesting potential cryogenic uses.

High Strength High Ductility Low Alloyed Steel

Annealed Martensite Matrix (AMM) concept was studied on two steel grades with low alloyed base composition of Fe-C-Mn-Si and two levels of Nb. Conditions for the thermal treatments were selected based on the experimental dilatometry tests and thermodynamic calculations. Annealing trials with short austempering holding were performed in the laboratory salt pots. Mechanical properties of heat treated steels have been investigated by tensile tests. Associated microstructures have been analyzed using Scanning Electron Microscopy as well as magnetization saturation method for measuring retained austenite fractions. Excellent strength-ductility balance was obtained due to the ultra-fine multiphase structure and high amount of stable retained austenite.

The Influence of the Soaking Process on Magnetization Saturation and Coercivity Field of the Classic Amorphous Alloy Fe61Co10Y8Nb1B20.

This study presents the results of Mossbauer research and magnetic properties. The tests were carried out for amorphous Fe61Co10Y8Nb1B20 alloys produced in the form of strips with a thickness of approximately 35 mm. Mossbauer spectra were measured in transmission geometry for solid samples. Measurements were taken for samples in solidified state and after two heating processes. The first process was carried out at 700K and 60 minutes, the second at 720K and 210 minutes. For the samples prepared in this way, magnetization tests were performed as a function of the magnetic field strength. The values of saturation magnetization and the value of the coercive field were determined from these matrices. It was found that the performed thermal treatments had a negative effect on the value of saturation magnetization and change in the value of the coercive field.