Heat generation by an alternating magnetic field of low frequency in a ferrofluid: the dependence of energy dissipation on temperature

2008 ◽  
Vol 44 (1) ◽  
pp. 27-32 ◽  
Author(s):  
M.M. Maiorov ◽  
E. Blums ◽  
G. Kroņkalns
Nanoscale ◽  
2016 ◽  
Vol 8 (6) ◽  
pp. 3259-3263 ◽  
Author(s):  
Jie Fang ◽  
Yong Yang ◽  
Wen Xiao ◽  
Bingwen Zheng ◽  
Yun-Bo Lv ◽  
...  

An extremely low frequency alternating magnetic field of 20 Hz was proved to be able to remarkably accelerate the drug release from optimized ZIF-90 nanospheres with incorporated Fe3O4 nanoparticles acting as actuator.


2021 ◽  
Vol 12 ◽  
pp. 1404-1412
Author(s):  
Elizaveta M Gubanova ◽  
Nikolai A Usov ◽  
Vladimir A Oleinikov

Low-frequency hysteresis loops and specific absorption rate (SAR) of various assemblies of elongated spheroidal magnetite nanoparticles have been calculated for a range of particle semiaxis ratios a/b = 1.0–3.0. The SAR of a dilute randomly oriented assembly of magnetite nanoparticles in an alternating magnetic field of moderate frequency, f = 300 kHz, and amplitude H0 = 100–200 Oe is shown to decrease significantly with an increase in the aspect ratio of nanoparticles. In addition, there is a narrowing and shift of the intervals of optimal particle diameters towards smaller particle sizes. However, the orientation of a dilute assembly of elongated nanoparticles in a magnetic field leads to an almost twofold increase in SAR at the same frequency and amplitude of the alternating magnetic field, the range of optimal particle diameters remaining unchanged. The effect of the magneto-dipole interaction on the SAR of a dilute assembly of oriented clusters of elongated magnetite nanoparticles has also been investigated depending on the volume fraction of nanoparticles in a cluster. It has been found that the SAR of the assembly of oriented clusters decreases by approximately an order of magnitude with an increase in the volume fraction of nanoparticles in a cluster in the range of 0.04–0.2.


2020 ◽  
Vol 12 (1) ◽  
pp. 168781401990072
Author(s):  
Jinzhong Wu ◽  
Shaohui Yin ◽  
Shengjie Yang ◽  
Yuanfan Guo

With the development of electronics and optical industry, the high-efficiency ultra-precision polishing technologies of flat and curved surfaces are in high demand. The traditional magnetorheological polishing technology, using flexible polishing head, has the disadvantages of low polishing efficiency and small processing area. In this study, a novel tray-type magnetorheological polishing process using low-frequency alternating magnetic field excitation was developed to improve the efficiency of magnetorheological polishing for large surfaces and to make polishing magnetorheological cluster generate a cyclical fluctuation up and down, and then improve the cross-cutting effects of abrasives. With the developed excitation system, a large bowl-shaped varying magnetic field was generated in the working area, and the effects of current frequency, working gap, trough rotation speed, and workpiece rotation speed on the improvement rate of surface roughness and material removal rate were systematically investigated. A series of experiments were conducted on K9 glass specimens to verify the polishing performance. Experimental results show that the surface roughness of K9 glass was improved from 567.08 to 9.63 nm in 120 min.


2019 ◽  
Vol 281 ◽  
pp. 315-323 ◽  
Author(s):  
Vinodha Ganesan ◽  
B.B. Lahiri ◽  
Cindrella Louis ◽  
John Philip ◽  
Shima P. Damodaran

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