Atmospheric benzo[a]pyrene in the Yangtze River Delta, China: pollution level and lung cancer risk in 2016 and future predictions.

The Yangtze River Delta (YRD) has undergone widespread polycyclic aromatic hydrocarbon (PAH) pollution. In this study, we simulated the spatial distribution of atmospheric benzo[a]pyrene (BaP, the most carcinogenic PAH) in the YRD in 2016 and 2030 under different emission scenarios using a 3-D atmospheric transport model and evaluated the lung cancer risks posed by BaP during the study years. The purpose of this study is to suggest targeted policy recommendations for policy-makers to mitigate BaP pollution through numerical simulation. Our results showed that the average BaP concentration in the YRD was 0.30 ng/m3 in 2016; however, a significant spatial variation was observed, with the highest BaP concentration in Shanghai (0.59 ng/m3). The population-weighted incremental lifetime lung cancer risk (PILCR) was 6.67 × 10-6 in 2016, whereas it ranged from 2.70 × 10-6 to 1.05 × 10-5 in 2030 under the five emission scenarios. A higher future population density in the YRD region could increase lung cancer risk. In all scenarios, Shanghai had the highest number of lung cancer cases (range: 208-476). The results suggest that BaP pollution could be effectively improved through the synergistic effect of reducing activity levels and improving technology. Finally, we provide specific suggested pollution control strategies (e.g., accelerating the use of clean energy in rural areas) for atmospheric BaP in the YRD.

Self-Aligned Ionic Doping of TiO2 Thin-Film Transistors for Enhanced Current Drivability via Postfabrication Superacid Treatment.

Oxide semiconductor thin-film transistors (TFTs) have shown great potential in emerging applications such as flexible displays, radio-frequency identification tags, sensors, and back-end-of-line compatible transistors for monolithic 3D integration beyond their well-established flat-plane display technology. To meet the requirements of these appealing applications, high current drivability is essential, necessitating exploration in materials science and device engineering. In this work, we report for the first time on a simple solution-based superacid (SA) treatment to enhance the current drivability of top-gate TiO2 TFTs with a gate-offset structure. The on-current of these transistors is limited by the relatively low mobility of TiO2 due to its d-orbital conduction nature. It is found that the on-current of TiO2 TFTs is nearly doubled via a quick dip in a SA solution at room temperature in ambient air. A series of experiments, including comparative I-V measurements of TFTs with different treatments and gate structures, C-V measurements, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and device simulation, were performed to uncover the underlying reason for the current enhancement. It is believed that the protons (H+) from SA are doped into the offset region of TiO2 TFTs, forming an electron double layer and thus boosting the on-current, with the top gate serving as a self-aligned mask for ionic doping. Furthermore, the ionic size and the proportion of the offset region to the channel play crucial roles in the effectiveness of ionic doping, while the position of the incorporated ions, whether in the channel or dielectric, may result in distinct shifts in the turn-on voltage (VON) and affect the functionality of ionic doping. This study provides a pathway for enhancing the current drivability of TiO2 TFTs via selective ionic doping enabled by SA treatment and deepens our understanding of ion incorporation in electronic devices. This approach could be applicable to other material systems and may also benefit TFTs with miniaturized dimensions, thus opening up unprecedented opportunities for TiO2 TFTs in future applications requiring high current drivability.

Improved ammonia emission inventory of fertilizer application for three major crops in China based on phenological data.

NH3 has an important impact on atmospheric chemistry, and its reduction has become a potential pathway to alleviate haze pollution. The existing NH3 emission inventories still have significant uncertainties in terms of their temporal distributions. In this study, we combined satellite remote-sensing phenological data with ground-station phenological data to develop a method for the temporal allocation of NH3 emissions from fertilizer application. A high-resolution dataset for fertilizer application in China was established. We developed NH3 emission inventories for the fertilization of three major crops in China, with a resolution of 1/12° × 1/12°. The results showed that there was a significant temporal variation in fertilizer application dates across the country, mainly concentrated in June (17.16 %), July (19.08 %), and August (18.77 %). The majority of fertilizer application for the three major crops occurred during the spring and summer months, with a particular emphasis on April (5.72 Tg), May (7.05 Tg), and June (4.29 Tg). The total NH3 emission from the three major crops in China in 2019 was 2.73 Tg. The North China Plain (762.23 Gg) and Middle and Lower Yangtze River Plain (606.85 Gg) were identified as the primary regions for high NH3 emissions from fertilizer application. The results also showed that NH3 emissions from the three major crops were predominantly observed during summer, with a peak value in July (606.99 Gg), mainly because of the high proportion of topdressing fertilizers. Areas with high fertilizer application generally coincided with areas of high NH3 emissions. This study may be the first to utilize remote-sensing phenological data to establish the NH3 emission inventory, which is of great significance for further improving the accuracy of the NH3 emission inventory.