Alkaline gases such as NH3 and amines play important roles in neutralizing acidic particles in the atmosphere. Here, two common gaseous amines (dimethylamine (DMA) and trimethylamine (TMA)), NH3, and their corresponding ions in PM2.5 were measured semicontinuously using an ambient ion monitor-ion chromatography (AIM-IC) system in marine air during a round-trip cruise of approximately 4000 km along the coastline of eastern China. The concentrations of particulate DMA, detected as DMAH+, varied from <4 to 100 ng m–3 and generally decreased with increasing atmospheric NH3 concentrations. Combining observations with thermodynamic equilibrium calculations using the extended aerosol inorganics model (E-AIM) indicated that the competitive uptake of DMA against NH3 on acidic aerosols generally followed thermodynamic equilibria and appeared to be sensitive to DMA/NH3 molar ratios, resulting in molar ratios of DMAH+ to DMA + DMAH+ of 0.31 ± 0.16 (average ± standard deviation) at atmospheric NH3 concentrations over 1.8 μg m–3 (with a corresponding DMA/NH3 ratio of (1.8 ± 1.0) × 10–3), 0.80 ± 0.15 at atmospheric NH3 concentrations below 0.3 μg m–3 (with a corresponding DMA/NH3 ratio of (1.3 ± 0.6) × 10–2), and 0.56 ± 0.19 in the remaining cases. Particulate TMA concentrations, detected as TMAH+, ranged from <2 to 21 ng m–3 and decreased with increasing concentrations of atmospheric NH3. However, TMAH+ was depleted concurrently with the formation of NH4NO3 under low concentrations of atmospheric NH3, contradictory to the calculated increase in the equilibrated concentration of TMAH+ by the E-AIM.

CO 2 capture plants are a significant source of emission of monoethanolamine (MEA) in the atmosphere. As a potential MEA sink, the heterogeneous uptake of MEA by sulfuric acid (SA) particles can form particulate MEA sulfate (MEAS), changing the hygroscopicity of the particles. We determined the hygroscopicities of MEA salts, including MEAS, at different MEA:sulfate molar ratios over a wide range of relative humidity (RH) using an electrodynamic balance (EDB) and a water activity meter. Other salts, including MEA oxalate, nitrate, and chloride, were studied using the water activity meter. Empirical functions were fitted to the experimentally measured hygroscopicity data of MEA salts. We further investigated the reactive uptake of parts per million-level MEA by SA particles in an EDB. The relative mass change of the levitated particles was the combined result of MEA uptake and changes in particle hygroscopicity due to compositional changes. The measured hygroscopicity was used to analyze the particle composition change during MEA uptake and the uptake kinetics. The uptake coefficients (γ MEA ) were estimated to be (3.23 ± 0.64) × 10 −3 and (9.89 ± 2.62) × 10 −4 at 40% and 70% RH, respectively. MEA reactive uptake by acidic particles could be competitive with respect to MEA gas-phase oxidation under highparticle concentration conditions near power plants.

The detection of train obstacle intrusion is very important for the safe running of trains. In this paper, we design a multitask intrusion detection model to warn of the intrusion of detected target obstacles in railway scenes. In addition, we design a multiobjective optimization algorithm that performs with different task complexity. Through the shared structure reparameterized backbone network, our multitask learning model utilizes resources effectively. Our work achieves competitive results on both object detection and line detection, and achieves excellent inference time performance(50 FPS). Our work is the first to introduce a multitask approach to realize the assisted-driving function in a railway scene.

A novel experimental approach to study the hygroscopic properties of multi-component inorganic aerosols was demonstrated using a laser trapping technique. The efflorescence and deliquescence phase transitions of the equimolar mixture of NaCl and NaNO3 particles levitated in air were reversibly induced by controlling relative humidity. The two-stage phase transitions of the particles during the dehumidifying and humidifying processes were successfully observed in air. To our knowledge, this is the first experimental result to observe the reversible hygroscopic behavior of single optically-levitated multi-component inorganic aerosols in air. Furthermore, to elucidate the influence of solid substrates on the homogeneous and heterogeneous nucleation processes, the efflorescence relative humidity (ERH) and mutual efflorescence relative humidity (MERH) in air were compared with those observed on a hydrophobic glass substrate. The average ERH and MERH values of the NaCl–NaNO3 particles levitated in air were lower than those obtained for the particles deposited on the hydrophobic glass substrate.

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