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Leicester, United Kingdom

Yang H.,Shanghai Normal University | Zhuang Y.,Shanghai Normal University | Hu H.,Shanghai Normal University | Du X.,Shanghai Normal University | And 5 more authors.
Advanced Functional Materials

Monodisperse silica-coated manganese oxide nanoparticles (NPs) with a diameter of ∼35 nm are synthesized and are aminated through silanization. The amine-functionalized core-shell NPs enable the covalent conjugation of a fluorescent dye, Rhodamine B isothiocyanate (RBITC), and folate (FA) onto their surface. The formed Mn3O4@SiO2(RBITC)-FA core-shell nanocomposites are water-dispersible, stable, and biocompatible when the Mn concentration is below 50 μg mL-1 as confirmed by a cytotoxicity assay. Relaxivity measurements show that the core-shell NPs have a T1 relaxivity (r1) of 0.50 mm-1s-1 on the 0.5 T scanner and 0.47 mm-1S-1 on the 3.0 T scanner, suggesting the possibility of using the particles as a T1 contrast agent Combined flow cytometry, confocal microscopy, and magnetic resonance imaging studies show that the Mn3O4@SiO 2(RBITC)-FA nanocomposites can specifically target cancer cells overexpressing FA receptors (FARs). Findings from this study suggest that the silica-coated Mn3O4 core-shell NPs could be used as a platform for bimodal imaging (both magnetic resonance and fluorescence) in various biological systems. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Magnetic North | Date: 2013-10-07

A rotating vacuum heat treatment equipment, applicable for heat treatment of rare earth permanent magnetic devices, hydrogen pulverization of rare earth permanent magnetic alloy, and heat treatment of mechanical electronic components, mainly comprises: a vacuum unit, a gas cooling device, and a vacuum furnace, wherein an insulating layer is provided in the vacuum furnace, a heater is provided in the insulating layer, a rotating cylinder is provided in the heater, a nozzle, connected with pipelines of the gas cooling device, is provided on the insulating layer, and cooled gas is sprayed to the rotating cylinder via the nozzle.

In the method for producing a high-performance neodymium-iron-boron rare earth permanent magnetic material of the present invention, the degree of alignment of the magnet can be improved by preparing the pre-sintered alloy material, the particle size of the powder ground by the jet mill can be refined and the fine powder in the filter of the jet mill can be mixed with the powder collected by the cyclone collector by controlling the oxygen content of the jet mill and adding the nanoscale oxide fine powder. The present invention can significantly improve the utilization ratio of the material and the performance of the magnet, save the use of the rare earth, and especially the heavy rare earth, thereby protecting the scare resources.

A method for producing neodymium-iron-boron rare earth permanent magnetic materials comprises: controlling technological parameters of alloy smelting, coarsely pulverization, milling by jet mill, and compaction; and adding nano-sized micro powder of oxide, in such a manner that a particle size of milling by the jet mill is decreased, and fine powder collected by the powder filter and powder collected by a cyclone collector are mixed. Utilization rate of the materials and performance of magnets are significantly improved. Usage amount of rare earth is significantly saved, especially usage amount of heavy rare earth. Thus, the scarce resources are protected.

Kunjir N.C.,University of Iceland | Reginsson G.W.,University of Iceland | Reginsson G.W.,Magnetic North | Schiemann O.,Magnetic North | And 2 more authors.
Physical Chemistry Chemical Physics

Trityl based spin labels are emerging as a complement to nitroxides in nanometer distance measurements using EPR methods. The narrow spectral width of the trityl radicals prompts us to ask the question at which distance between these spin centers, the pseudo-secular part of the dipolar coupling and spin density delocalization have to be taken into account. For this, two trityl-trityl and one trityl-nitroxide model compounds were synthesized with well-defined interspin distances. Continuous wave (CW) EPR, double quantum coherence (DQC) and pulsed electron-electron double resonance (PELDOR) spectra were acquired from these compounds at commercial X-band frequencies. The data analysis shows that two of the compounds, with distances of up to 25 Å, fall into the strong coupling regime and that precise distances can only be obtained if both the spin density delocalization and the pseudo-secular part of the dipolar coupling are included in the analysis. © 2013 The Owner Societies. Source

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