Paper, as a flexible, low-cost, lightweight, tailorable, environmental-friendly, degradable, and renewable material, is emerging in electronic devices. Especially, many kinds of paper-based (PB) sensors have been reported for wearable applications in recent years. Among them, the PB gas, humidity, and strain sensors are widely studied for monitoring gas, humidity, and strain from the human body and the environment. However, gas, humidity, and strain often coexist and interact, and the paper itself is hydrophilic and flexible, resulting in that it is still challenging to develop high-performance PB sensors specialized for gas, humidity, and strain detections. Therefore, it is necessary to summarize and discuss them systematically. In this review, we focus on summarizing the state-of-art studies of the PB gas, humidity, and strain sensors. Specifically, the fabrications (electrodes and sensing materials) and applications of PB gas, humidity, and strain sensors are summarized and discussed. The current challenges and the potential trends of PB sensors for gas, humidity, and strain detections are also outlined. This review not only can help readers to understand the development status of the PB gas, humidity, and strain sensors but also is helpful for readers to find out and solve the problems in this field through comparative reading.

Amorphous transition metal oxides are recognized as leading candidates for electrochromic window coatings that can dynamically modulate solar irradiation and improve building energy efficiency. However, their thin films are normally prepared by energy-intensive sputtering techniques or high-temperature solution methods, which increase manufacturing cost and complexity. Here, we report on a room-temperature solution process to fabricate electrochromic films of niobium oxide glass (NbO) and 'nanocrystal-in-glass' composites (that is, tin-doped indium oxide (ITO) nanocrystals embedded in NbO glass) via acid-catalysed condensation of polyniobate clusters. A combination of X-ray scattering and spectroscopic characterization with complementary simulations reveals that this strategy leads to a unique one-dimensional chain-like NbO structure, which significantly enhances the electrochromic performance, compared to a typical three-dimensional NbO network obtained from conventional high-temperature thermal processing. In addition, we show how self-assembled ITO-in-NbO composite films can be successfully integrated into high-performance flexible electrochromic devices.

Trimetallic catalytic microrotors were fabricated by electrodeposition of cylindrical Au-Ru rods in the pores of anodic alumina membranes, dissolution of the template membrane, and then sequential vapor deposition of Cr, SiO(2), Cr, Au, and Pt on one side of each rod. This design provides two force vectors for the catalytic motor, including one perpendicular to the rod axis. The rods rotated rapidly (approximately 180 rpm) in 15% aqueous H(2)O(2) solution with minimal orbital or translational movement. The rotation was rapid enough to observe qualitatively different interactions between pairs of co- and counter-rotating rods. Counter-rotating rods were able to approach each other closely and underwent frequent tip-to-tip collisions. Co-rotating rods could approach each other only to a distance of approximately 0.9 microm. This difference is rationalized on the basis of shear forces generated by the catalytically driven rotation of the rods.

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The low friction of silicon carbide (SiC)/water systems is understood to be the result of a self-forming silica-based tribolayer that is produced by tribochemical reactions. Although several experimental studies have revealed that this silica-based tribolayer contains a considerable amount of carbon, the detailed structure of the tribolayer and its role in providing low friction remain unclear. Here, we conducted a reactive molecular dynamics sliding simulation of an amorphous SiC (a-SiC)/water system to elucidate the atomic-scale structure of the self-forming tribolayer and the mechanism underlying its formation. We found that the water selectively oxidized Si atoms at the surface of the a-SiC, resulting in their removal as SiO 2 wear particles. Some of these wear particles dissolved in the water, resulting in the formation of colloidal silica, whereas others were deposited on the a-SiC surface, where they formed a layer of silica hydrate. Meanwhile, carbon atoms remained at the a-SiC surface and formed a C-rich layer, which corresponds to the initial process of an amorphous carbon layer formation. Based on our findings, we propose that colloidal silica, silica hydrate, and amorphous carbon act as individual tribolayers to reduce friction in the low-, intermediate-, and high-contactpressure areas, respectively. In the low-contact-pressure area, water mainly separates the surfaces, and the silica hydrate holds the water at the sliding interface because of its high hydrophilicity, increasing the load-carrying capacity of the water. In the intermediate-contact-pressure area, the water cannot separate the surfaces, but the colloidal silica layer can because of its high viscosity. In the high-contact-pressure area, where the water and silica-based layers are broken, the amorphous carbon layer works as a solid lubricant. Thus, the three self-forming tribolayers together produce the low friction that characterizes SiC/water systems.

CoCrFeCuNi high-entropy alloys (HEAs) prepared by arc melting were irradiated with a 100 keV He+ ion beam. Volume swelling and hardening induced by irradiation were evaluated. When the dose reached 5.0 × 1017 ions/cm2, the Cu-rich phases exhibited more severe volume swelling compared with the matrix phases. This result indicated that the Cu-rich phases were favorable sites for the nucleation and gathering of He bubbles. X-ray diffraction indicated that all diffraction peak intensities decreased regularly. This reduction suggested loosening of the irradiated layer, thereby reducing crystallinity, under He+ ion irradiation. The Nix-Gao model was used to fit the measured hardness in order to obtain a hardness value H0 that excludes the indentation size effect. At ion doses of 2.5 × 1017 ions/cm2 and 5.0 × 1017 ions/cm2, the HEAs showed obvious hardening, which could be attributed to the formation of large amounts of irradiation defects. At the ion dose of 1.0 × 1018 ions/cm2, hardening was reduced, owing to the exfoliation of the original irradiation layer, combined with recovery induced by long-term thermal spike. This study is important to explore the potential uses of HEAs under extreme irradiation conditions.

Background A set of nozzle systems for proton therapy is now being developed at China Institute of Atomic Energy. To realize the measurement of beam dose, a set of charge measurement electronics is designed, which is used to measure the output charge signal of the ionization chamber integration plane. Also, the charge measurement device can be used to measure the position information of ion chamber strips just by changing certain parameters. Methods The device realizes the integration and amplification of charge by IVC102, a precise low-noise integrator, and the DSP controls the ADC to collect and process the data. Modbus communication protocol is used to realize communication with the host computer which makes it possible to read data and set the parameter. Results A fixed charge generator is designed to generate 20 pC to 2 nC charge, which is used to test the measuring accuracy of electronics. The results have shown that the accuracy is within 0.62% in the above charge range. Conclusion After experimental tests, the front-end electronics meet the design goal and play a certain pre-test and verification role in the dose and beam position monitoring in the proton therapy system.