The accelerated evolution of the Internet of Things has brought new challenges to the gas sensors, which are required to work persistently under harsh conditions, like high humidity. However, currently, it is quite challenging to solve the hindrance of the trade-off between gas-sensing performance and anti-humidity ability of the chemiresistive gas sensors. Herein, hydrophobic inorganic CeO 2 /SnO 2 heterostructure films were prepared by depositing the CeO 2 layers with a thickness of a few nanometers onto the SnO 2 film via a magnetron sputtering method. The sensors based on the CeO 2 /SnO 2 heterostructure films demonstrated excellent gas-sensing performance toward trimethylamine (TEA) with high response, wide detection range (0.04− 500 ppm), low record detection limit (0.04 ppm), ideal reproducibility, and long-term stability, while concurrently possessing promising antihumidity ability. A portable, wireless TEA-sensing system containing the CeO 2 /SnO 2 sensor was constructed to realize the real-time monitoring of trace concentration of the volatiles released from a fish. This work provides a novel strategy to prepare advanced chemiresistive gas sensors for humidity-independent detection of harmful gases and vapors and will accelerate their commercialization process in the field of food safety and public health.

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Depending on the experimental conditions and plasmonic systems, the correlations between near-field surface enhanced Raman scattering (SERS) behaviors and far-field optical responses have sometimes been accepted directly, or argued, or explored. In this work, we have numerically demonstrated the anomalous spectral correlations between the near- and far-field properties for roughened Au mesoparticles. As a counterexample, it is witnessed that the dipole extinction peak of the mesoparticles may mislead us in seeking favorable SERS performance. The simple Rayleigh scattering spectra can also be misguided in the presence of dark modes. For roughened mesoparticles with a moderate size here, the huge near-field enhancement is a synergistic result of the overall dark quadrupole mode and the substructural bonding dipole coupling. The conclusions demonstrated here would be of general interest to the field of plasmonics, especially the optimization of single-particle SERS substrates.

To reduce the butanol fermentation wastewater (BFW) discharge and to address the difficulties in BFW treatment, a novel fermentation–pervaporation hybrid process was performed. After each batch of acetone–butanol–ethanol (ABE) fermentation, ABE in the fermentation broth was ex situ separated by pervaporation. The retentate was used as the buffer and the solution for the following batches of enzymatic hydrolysis and fermentation, respectively. Results showed that there were little negative influences of the phenols and acid inhibitors on the fermentation performances using the recycled BFW. Benefits from the process for BFW discharge reduction were obvious. After 4 cycles of BFW, ∼86% of the BFW was saved. Over 94% of ABE with concentrations of 42.5–50.2 g/L was recovered by pervaporation. Therefore, the novel process can effectively eliminate the disadvantage of large BFW discharge in the ABE fermentation processes.

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In view of the strong nonlinearity of the signals in the gestation period of milling chatter, and the problem that the traditional time-frequency analysis methods cannot reveal the weak characteristics of the gestation period of chatter well, a chaotic characteristic analysis method of milling vibration information is proposed. The milling force signals of stable milling, chatter gestation and chatter outbreak states are collected through variable working condition milling force measurement experiments, and the chaotic phase space reconstruction method is used to obtain the attractor images of milling force signals in different vibration states. The experiments show that the attractor features in the chatter gestation period are more significant than the traditional time-frequency features, and the chaotic attractor images can better reveal the weak features in the chatter gestation period.

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