ABSTRACT
In order to explore the pollution characteristics and sources of atmospheric volatile organic compounds (VOCs) in winter in Kaifeng City, based on the atmospheric VOCs component data obtained from the online monitoring station of the Kaifeng Ecological and Environmental Bureau (Urban Area) from December 2021 to January 2022, the pollution characteristics of VOCs and secondary organic aerosol formation potential (SOAP) were discussed, and the sources of VOCs were analyzed by using the PMF model. The results showed that the average mass concentration of VOCs in winter in Kaifeng City was (104.71±48.56) µg·m-3, and alkanes (37.7%) had the highest proportion of mass concentrations, followed by that of halohydrocarbons (23.5%), aromatics (16.8%), OVOCs (12.6%), alkenes (6.9%), and alkynes (2.6%). The averaged total SOAP contributed by VOCs was 3.18 µg·m-3, of which aromatics contributed as much as 83.8%, followed by alkanes (11.5%). The largest anthropogenic source of VOCs in winter in Kaifeng City was solvent utilization (17.9%), followed by fuel combustion (15.9%), industrial halohydrocarbon emission (15.8%), motor vehicle emission (14.7%), organic chemical industry (14.5%), and LPG emission (13.3%); solvent utilization contributed 32.2% of the total SOAP, followed by motor vehicle emission (22.8%) and industrial halohydrocarbon emission (18.9%). It was found that reducing VOCs emissions from solvent utilization, motor vehicle emission, and industrial halohydrocarbon emission was important to control the formation of secondary organic aerosols in winter in Kaifeng City.
ABSTRACT
The light-driven micro/nanomotor (LMNM) is machinery that harvests photon energy and generates self-propulsion in varieties of liquid media. Though visions are made that these tiny swimming machines can serve future medicine for accurate drug delivery and noninvasive microsurgery, their biomedical application is still impeded by the insufficient propulsion efficiency. Here we provide a holistic model of LMNM by considering (i) photovoltaic, (ii) electrochemical, and (iii) electrokinetic processes therein. Such a quantitative model revealed the pivotal role of reaction kinetics and diffusion properties of shuttle ions in the propulsion efficiency of LMNM. With the guidance of this model, a group of ferrocene-based reversible redox shuttles, which generate slow-diffusion ions, was identified, showcasing a high locomotion velocity of â¼500 µm/s (â¼100 body length per second) at an ultralow concentration (70 µM). Owing to the in-depth understanding of the fundamental energy conversion processes in LMNM, we anticipate that the development of other high-performance supporting chemicals and LMNM systems will be greatly motivated, foreseeing the advent of LMNM systems with superior efficiency.
