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The goal of this study is to determine the potential of Acidithiobacillus ferrooxidans strain Z1 in bioleaching of metal concentrates of waste printed circuit boards (PCBs). The influences of initial pH, initial Fe(II) concentration, metal concentrates dosage, inoculation quantity and particle size on the bioleaching process were investigated and optimum conditions were determined. The results showed that 92.57 % copper leaching efficiency was achieved within 78 h in a two-step process, and 85.24 % aluminum and 95.18 % zinc were leached out after 183 h under the optimum conditions of initial pH 2.25, initial Fe(II) 9 g/L, metal concentrates dosage 12 g/L, inoculation quantity 10 % and particle size 0.178-0.250 mm. It demonstrated that metals could be efficiently leached from metal concentrates by Acidithiobacillus ferrooxidans Z1 and the bioleaching period was reduced 81-78 h. Therefore, the strain Acidithiobacillus ferrooxidans Z1 could be suggested as a potential strain to bioleach metals from metal concentrates of waste PCBs.

As a universal interaction method, hand and finger gestures can express people's intention directly and clearly in daily life, and has been one of the hotspots in human-computer interaction community. In this paper, we present DMT, a device-free finger gesture tracking system that can track and recognize the finger motion accurately. To achieve this, we transform the mobile device, such as a smart phone, into an active sonar system by establishing inaudible audio links between the built-in speakers and microphone. The finger motion will have an effect (e.g., Doppler-shift) on the audio signals, which makes it possible to track the finger motion according to the received signal characteristics at the microphone side. Due to the small reflection energy and slow moving speed of the finger, the existing methods cannot detect the Dopplershift accurately. To this end, a Fourier fitting-based method is proposed in the DMT to accurately detect the Doppler-shift. With the detected Doppler-shift, the DMT can track the finger motion with high accuracy. The DMT supports all kinds of finger gestures interaction, including characters and shapes. Extensive experiments demonstrate the high accuracy and robustness of the DMT in dynamic environments.

The properties of anode material are crucial for high performances in microbial fuel cells (MFCs). Herein, we report a biocompatible, conductive, and electron transfer efficient cooperative processing anode, which is fabricated by electrodepositing polypyrrole/anthraquinone‐2, 6‐disulphonic disodium salt (PPy/AQDS) onto nitric acid‐soaked carbon felt. Results showed that the cooperative processing anode outperformed the pristine one in biomass, electrical conductivity, and exchange current density with better performance between 2.4 and 3.3 times. The maximum power density (1060.3 mW m−2) of the MFC equipped with the properties hybridized anode delivered a 2.2‐fold increase over that of the control and thus has great potential to be used as an anode for high‐power MFC. Further investigation revealed that the contributions of biocompatibility (BCB), electrical conductivity (EC), and electron transfer efficiency (ETE) to the performance of carbon felt anodes appeared as cumulative effect rather than summing effect. We propose combined treatment of BCB with EC and ETE to form a properties‐hybridized anode based on thoroughly analyzing the feasibility and effectiveness, and discussed future efforts to be made for realizing more extraordinary high‐performance cooperative processing anodes. This work may also provide a novel approach for the development of other types of anode for high‐performance MFC through combined treating the BCB with EC and ETE simultaneously.