Three-dimensional graphene foam (GF) is synthesized by CVD. When water flows through GF, electricity is induced. The direction of the induced current is dominated by the flow direction of water; the value of induced current is related to the flow velocity but has no relationship with the flow direction and external bias voltage.

In this work, the electrical conductance and induced current of three-dimensional graphene foam (GF) are investigated when the mixture of water and ethanol flows through it. When different mixing ratios of ethanol:water (ethanol:water = 25:75, 50:50, 75:25, and 100:0 by volume) flow through the GFs, their electrical conductance is almost the same as that of the original GF. Meanwhile, the induced current can be obtained when the mixture flows through the GF. The direction of induced current depends on that of the flow of the mixture, the value of induced current has no dependence on the flow direction of the mixture but is closely related to the flow velocity and polarity of the mixture. The mechanism of the induced electricity is discussed, which is attributed to the coupling of flowing solution molecules with the charge carriers of graphene at the solid/liquid interface. These results indicate that GFs have a bright potential application in realizing the self-powered function of nano/micro electromechanical systems (N/MEMS) in many special environments.

One case of epidermal granuloma of the right thumb was diagnosed by color Doppler ultrasonography and pathologic examination. Epidermal granuloma resection and reverse island skin flap transplantation were performed to determine the therapeutic effect of a reverse first dorsal metacarpal artery flap repair of an epidermal granuloma of the right thumb. After effective intravenous combined general anesthesia, the skin in the surgical field was disinfected and sterile drapes were placed. An oblique incision was made over the underlying epidermis granuloma. The right palm of the reverse first dorsal metacarpal artery flap was chosen. The pedicle was carefully protected, and the flap was transplanted to the defective skin area. The incision was sutured after hemostasis. A palpable mass with the dimension of the right thumb of the patient was measured by color Doppler ultrasonography and physical examination pre-operatively. The palpable mass was oval in shape and protruded from the skin surface. The palpable mass had an unclear boundary with the surrounding skin and therefore the skin should be removed. If the tendon is exposed after the resection, complications may occur after operation, such as skin necrosis and tendon exposure. Intra-operatively, the mass was 1.5×1.0 cm in size and multi-cystic. The boundary between the palpable mass and the surrounding skin could not be discerned. The skin area (1.5×1.0 cm in size) was completely invaded by the palpable mass, which was closely adhered to the surrounding tissue. The palpable mass was carefully dissected with appropriate protection to the finger nerves and arteries. The palpable mass and affected skin were completely removed, leaving a defect area of ~1.5 ×1.0 cm without skin. The reverse first dorsal metacarpal artery flap was used to repair the defect area. The repaired flap had a good blood supply and peripheral circulation. The operation was successful, and the anesthesia effect was satisfactory. Treatment of a thumb epidermis granuloma with reverse first dorsal metacarpal artery flap was shown to be a feasible strategy with a broad clinical application.

Resonant tunnelling diode photodetectors with a 600 nm In 0.53 Ga 0.47 As absorption layer were fabricated by molecular beam epitaxy. The current-voltage characteristics of devices with different mesa diameters were tested and the negative differential resistance was observed in all devices. The responsivity of the detector was measured to be 4.19 × 10 5 A/W at 77 K and 1.92 × 10 4 A/W at room temperature under incident light with a power of 3.1 nW.

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