Earthquake Prediction is Possible by Electro-Magnetic-Wave Precursor?

We may write the electro-magnetic equations of Clerk-Maxwell asFor plane waves, running with normal velocity vα= −μ−1, we havewhence at once[For the moment, we assume that φ and ψ are self-conjugate, so that a linear function of them is also self-conjugate. And we employ the method sketched in Tait's Quaternions, §§ 438–9.]

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Synthesis and Enhanced Electro-Magnetic Wave Absorbing Properties of Reduced Graphene Oxide-Fe3O4-Polyaniline Ternary Nano-Composites

Science of Advanced Materials ◽

10.1166/sam.2021.3931 ◽

2021 ◽

Vol 13 (3) ◽

pp. 473-480

Author(s):

Yihan Jin ◽

Xi Luo ◽

Jinglin Zhang ◽

Dongliang Zhao ◽

Kewei Gao

Keyword(s):

Graphene Oxide ◽

Reduced Graphene Oxide ◽

Nano Particles ◽

Magnetic Data ◽

Nano Composites ◽

Frequency Bandwidth ◽

Magnetic Wave ◽

Three Samples ◽

Reduced Graphene ◽

Electro Magnetic

Micro-emulsion method is adopted to synthesis rGO-Fe3O4-PANI (reduced graphene oxide-Fe3O4-polyaniline) ternary nano-composites. With the different contents of aniline (0.1 g, 0.2 g, 0.3 g) added in production, the corresponding final products are named as sample 1, sample 2, sample 3, respectively. The results of TEM indicate that the mean size of Fe3O4 nano-particles is 14 nm and they are anchored onto rGO slice. There are some PANI polymer wrinkles distributed on the rGO surface uniformly. The electro-magnetic data demonstrate that sample 1 possess a great enhancement of the electro-magnetic wave absorption abilities and frequency bandwidth among the three samples. The RLmin (minimum reflection loss) value of sample 1 is -44.16 dB at 4.29 GHz with 5 mm coating thickness and 1.77 GHz (3.72-4.94 GHz, 13.33-13.88 GHz) frequency bandwidth (RL <italic/> -10 dB). We can believe that this kind of nano-composites will have a promising application in the future.

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Electro-Magnetic Wave Absorbing Properties Study of Nano-Composites Based on Fe3O4

Science of Advanced Materials ◽

10.1166/sam.2021.3930 ◽

2021 ◽

Vol 13 (3) ◽

pp. 447-454

Author(s):

Yihan Jin ◽

Xi Luo ◽

Jinglin Zhang ◽

Yipeng Yu ◽

Jing An ◽

...

Keyword(s):

Graphene Oxide ◽

Reduced Graphene Oxide ◽

Nano Particles ◽

Magnetic Wave ◽

Transmission Electron ◽

Reduced Graphene ◽

Micro Emulsion ◽

Mean Size ◽

Electro Magnetic ◽

Magnetic Nano Particles

Chemical coprecipitation method, hydrothermal method and micro-emulsion method were adopted to prepare pure Fe3O4 (X1) magnetic nano-particles, reduced graphene oxide-Fe3O4 (X2) binary composites and reduced graphene oxide-Fe3O4-polyaniline (X3) ternary composites. The morphology, structure and magnetic performance were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM) and vibration sample magnetism (VSM). The result of TEM showed that Fe3O4 nano-particles distributed uniformly on the surface of graphene and PANI matrix and the mean size was bout 13~14 nm. The electromagnetic data was tested by vector network analyzer demonstrating that the minnimum reflection loss (RLmin) value of X3 was -53.94 dB at 16.1 GHz with 1.5 mm thickness and 3.82 GHz (14.18~18 GHz) absorbing bandwidth (RL<italic/>-10 dB). Compared with pure magnetic Fe3O4 powders and rGO-Fe3O4 binary composites, the rGO-Fe3O4-PANI ternary composites were conduced to a great reinforce of the electro-magnetic wave absorbing properties and absorbing bandwidth.

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