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Volatile organic chemicals are produced from reactions of ozone with squalene in human skin oil. Both primary and secondary reaction products, i.e., 6-methyl-5-hepten-2-one (6-MHO) and 4-oxopentanal (4-OPA), have been reported in indoor occupied spaces. However, the abundance of these products indoors is a function of many variables, including the amount of ozone and occupants present as well as indoor removal processes. In this study, we develop a time-dependent kinetic model describing the behavior of ozone/squalene reaction products indoors, including the reaction process and physical adsorption process of products on indoor surfaces. The key parameters in the model were obtained by fitting time-resolved concentrations of 6-MHO, 4-OPA, and ozone in a university classroom on 1 day with multiple class sessions. The model predictions were subsequently tested against observations from four additional measurement days in the same classroom. Model predictions and experimental data agreed well (R2 = 0.87-0.92) for all test days, including ∼7 class sessions covering a range of occupants (10-70) and ozone concentrations (0.09-32 ppb), demonstrating the effectiveness of the model. Accounting for surface uptake of 6-MHO and 4-OPA significantly improved model predictions (R2 = 0.52-0.76 without surface uptake), reflecting the importance of including surface interactions to quantitatively represent product behavior in indoor environments.

We investigate source characteristics and emission dynamics of volatile organic compounds (VOCs) in a single-family house in California utilizing time- and space-resolved measurements. About 200 VOC signals, corresponding to more than 200 species, were measured during 8 weeks in summer and five in winter. Spatially resolved measurements, along with tracer data, reveal that VOCs in the living space were mainly emitted directly into that space, with minor contributions from the crawlspace, attic, or outdoors. Time-resolved measurements in the living space exhibited baseline levels far above outdoor levels for most VOCs; many compounds also displayed patterns of intermittent short-term enhancements (spikes) well above the indoor baseline. Compounds were categorized as "high-baseline" or "spike-dominated" based on indoor-to-outdoor concentration ratio and indoor mean-to-median ratio. Short-term spikes were associated with occupants and their activities, especially cooking. High-baseline compounds indicate continuous indoor emissions from building materials and furnishings. Indoor emission rates for high-baseline species, quantified with 2-hour resolution, exhibited strong temperature dependence and were affected by air-change rates. Decomposition of wooden building materials is suggested as a major source for acetic acid, formic acid, and methanol, which together accounted for ~75% of the total continuous indoor emissions of high-baseline species.

The development of advanced unmanned robots is of great significance to promote scientific progress and innovation, expand application fields, and improve efficiency and safety. Complex perception, motion, and navigation systems consisting of numerous sensors and powerful processors enable robots to monitor various sophisticated environments. However, the available commercial batteries cannot satisfy the long endurance and safety requirements of robots. Herein, we propose the application of metal–air batteries to power robot devices considering their advantages of higher energy density, lower cost, and better safety compared to lithium-ion batteries. Furthermore, the technological development of metal–air batteries in terms of specific energy, cycle life, fast charging, environmental adaptability and flexibility has increased the possibility of their application in next-generation unmanned devices. Accordingly, we present an outlook on the application of metal–air batteries in all fields of robotics, including land, air and sea, embodying the temporal and spatial infinities of these batteries. It is expected that the application of metal–air batteries will promote the advancement of the robot industry. [ABSTRACT FROM AUTHOR]

Flexible zinc‐air batteries have received widespread attention due to their high specific energy and eco‐friendly environment. However, the water in the hydrogel is easily lost to the external environment because of the semi‐open structure zinc‐air batteries, leading to performance degradation of the batteries. Here a saline gel of NaCl‐KOH‐PAA (sodium chloride‐potassium hydroxide‐polyacrylic acid) without soaking in the alkaline solution before use is designed, refining the grid structure of the hydrogel and reducing water loss through NaCl doping. Meanwhile, the gel exhibits no significant decrease in ion conductivity before and after NaCl doping and can maintain stability of around 170 and 150 mS cm−1 at room temperature and −20 °C, respectively. The results demonstrate that the lifetime of flexible zinc‐air batteries with NaCl‐doped hydrogel can be extended by nearly 50%. The NaCl doping gel also displays superior flexibility under extreme physical deformation conditions. Moreover, the phenomenon of hydrogel delamination with NaCl doping is observed and the mechanism of gel water retention is uncovered. These findings will pave the way for developing flexible zinc‐air battery. [ABSTRACT FROM AUTHOR]