Investigating tropospheric and surface ozone sensitivity from present day to future

Tropospheric ozone (O3) is an important reactive gas in the atmosphere influencing human health, ecosystems and climate. Since the mid-20th century, scientists started to explore the mechanism of tropospheric O3 formation after severe O3 air pollution in Los Angeles. They found that O3 is a photochemical pollutant as its formation involves energy from sunlight, as well as precursors nitrogen oxide (NOx), volatile organic compounds (VOCs) and carbon monoxide (CO). Nowadays, highly O3 polluted episodes can still occur in areas where emissions have been controlled strictly due to the non-linear chemical reactions of O3 formation. Therefore, it is important to implement suitable emission control strategies to mitigate O3 pollution, and to understand the impacts of emissions and climate on O3 changes in the future. Firstly, a chemistry scheme with more reactive VOC species is developed based on the Strat-Trop chemistry scheme in the United Kingdom Earth System Model, UKESM1. This permits a more realistic and photochemically active environment for O3 simulation in areas with high reactive VOC emissions. The effectiveness of emission controls in reducing surface O3 concentrations in the industrial regions of China in summer, 2016, is investi gated. The concentrations of surface O3 in those regions generally can be simulated accurately, and the diurnal variation of O3 can also be captured well by the model. O3 production in most regions is VOC-limited, suggesting that surface O3 concentrations will increase as NOx emissions decrease. In the VOC-limited regions, more than 70 % reductions in NOx emissions alone are required to reduce surface O3 concentrations. Reductions in 20 % VOC emissions alone lead to 11 % decreases in surface O3 concentrations, and are effective in offsetting increased O3 levels that would otherwise occur through decreased NOx emissions alone. Subsequently, the evolution of tropospheric O3 from the present day (2004- 2014) to the future (2045-2055) under the shared socio-economic pathways (SSPs) is investigated to demonstrate the impacts of different climate and emissions on O3 changes. In the context of climate change, changes in the tropospheric O3 burden in the future can be largely explained by changes in O3 precursor emissions. However, surface O3 changes vary substantially by season in high-emission regions due to different seasonal O3 sensitivity. VOC-limited areas are more extensive in winter (7 %) than in summer (3 %) across the globe. Reductions in NOx emissions are the key to transform O3 production from a VOC- to NOx-limited chemical environment, but will lead to increased O3 concentrations in high-emission regions, and hence emission controls on VOC and methane (CH4) are also necessary. Lastly, a deep learning model is developed to demonstrate the feasibility of correcting surface O3 biases in UKESM1, to identify key processes causing them, and to correct projections of future surface O3. Temperature and related geographic variables latitude and month show the strongest relationship with O3 biases. This indicates that O3 biases are sensitive to temperature and suggests weakness in representation of temperature-sensitive physical or chemical processes. Photolysis rates are also shown to be important for O3 biases likely due to uncertainties in cloud cover and insolation simulations. Chemical species such as the hydroxyl radical, nitric acid and peroxyacyl nitrates show a clear relationship to O3 biases, associated with uncertainties in emissions, chemical production and destruction, and deposition. Corrected seasonal O3 changes are generally smaller than those simulated with UKESM1 in high-emission regions. This demonstrates that O3 sensitivity to future emissions and climate in UKESM1 may be stronger than that in the real atmosphere. Given the uncertainty in simulating future ozone, we show that deep learning approaches can provide improved assessment of the impacts of climate and emission changes on future air quality, along with valuable information to guide future model development. The work presented here offers a valuable assessment of emission control strategies to resolve current O3 air pollution problems in China, and also quantifies the changes in the tropospheric O3 burden and global surface O3 sensitivity in the future under different emission and climate scenarios. Deep learning guides possible directions to improve model performance in surface O3 simulations for a global chemistry-climate model, and provides more accurate projections of O3 pollution in the future

The scale effects of organometal halide perovskites

Organometal halide perovskites have achieved great success in solution-processed photovoltaics. The explorations quickly expanded into other optoelectronic applications, including light-emitting diodes, lasers, and photodetectors. An in-depth analysis of the special scale effects is essential to understand the working mechanisms of devices and optimize the materials towards an enhanced performance. Generally speaking, organometal halide perovskites can be classified in two ways. By controlling the morphological dimensionality, 2D perovskite nanoplatelets, 1D perovskite nanowires, and 0D perovskite quantum dots have been studied. Using appropriate organic and inorganic components, low-dimensional organic–inorganic metal halide hybrids with 2D, quasi-2D, 1D, and 0D structures at the molecular level have been developed and studied. This provides opportunities to investigate the scale-dependent properties. Here, we present the progress on the characteristics of scale effects in organometal halide perovskites in these two classifications, with a focus on carrier diffusion, excitonic features, and defect properties

Synthesis of benzocycloalkene derivatives via Pd-catalyzed one-pot two-step reactions of benzocyclic ketones, tosylhydrazide with aryl bromides

A new method for the synthesis of benzocycloalkene derivatives is described, through the palladium-catalyzed one-pot two-step reactions of benzocyclic ketones, tosylhydrazide with aryl bromides. Palladium-carbene complex as an important intermediate undergoes migratory insertion to form benzylpalladium complex, followed by a fast β-hydride elimination to give substituted benzocycloalkenes. The advantages of this reaction include readily available starting materials, broad substrate scope, high efficiency, and gram scale synthesis. Keywords: Tosylhydrazone, Aryl bromides, Coupling reaction, Benzocycloalkene, Palladiu

Online Cyber-Attack Detection in the Industrial Control System: A Deep Reinforcement Learning Approach

In the open network environment, industrial control systems face huge security risks and are often subject to network attacks. The existing abnormal detection methods of industrial control networks have the problem of a low intelligence degree of adaptive detection and recognition. To overcome this problem, this article makes full use of the advantages of deep reinforcement learning in decision-making and builds a learning system with continuous learning ability. Specifically, industrial control network and deep reinforcement learning characteristics are applied to design a unique reward and learning mechanism. Moreover, an industrial control anomaly detection system based on deep reinforcement learning is constructed. Finally, we verify the algorithm on the gas pipeline industrial control dataset of Mississippi State University. The experimental results show that the convergence rate of this model is significantly higher than that of traditional deep learning methods. More importantly, this model can get a higher F1 score

Using Space Syntax in Close Interaction Analysis between the Elderly: Towards a Healthier Urban Environment

Population aging has become an issue that the world should to face together. Public spaces in urban areas play an important role in stimulating social interactions for the elderly, especially close social interactions. Although a volume of studies have focused on the health of the elderly and the shaping of urban space, they have neglected the need for close social behavior of the elderly group. This analysis addresses the question: What are the principles to improve public space qualities which facilitate age-friendly social interactions for the elderly? Blind-dating activities in Beijing City work as an example of close social interactions between the elderly. Methods include a case study in Beijing, field survey, and Space Syntax with related tools. The survey took place from 1 July to 30 September 2022. Around 102 elderly men and 84 women aging from 55 to 75 participated in the survey process. Results indicate that the close social interaction can positively comfort the elderly’s physical and psychological situations. It could be a path for the single elderly group meet a partner, make new friends, and establish new social networks. Consequently, three principles, including obtaining the safety of public space, keeping greenery in the social environment, and providing suitable space for close social interactions are proposed towards age-friendly urban areas. These support the regeneration of the elderly’s social life and stimulate a chasing of happy later lives

Numerical and Experimental Investigation of Novel Blended Bifurcated Stent Grafts with Taper to Improve Hemodynamic Performance

The typical helical flow within the human arterial system is widely used when designing cardiovascular devices, as this helical flow can be generated using the “crossed limbs” strategy of the bifurcated stent graft (BSG) and enhanced by the tapered structure of arteries. Here, we propose the use of a deflected blended bifurcated stent graft (BBSG) with various tapers, using conventional blended BSGs with the same degree of taper as a comparison. Hemodynamic performances, including helical strength and wall shear stress- (WSS-) based indicators, were assessed. Displacement forces that may induce stent-graft migration were assessed using numerical simulations and in vitro experiments. The results showed that as the taper increased, the displacement force, helicity strength, and time-averaged wall shear stress (TAWSS) within the iliac grafts increased, whereas the oscillating shear index (OSI) and relative residence time (RRT) gradually decreased for both types of BBSGs. With identical tapers, deflected BBSGs, compared to conventional BBSGs, exhibited a wider helical structure and lower RRT on the iliac graft and lower displacement force; however, there were no differences in hemodynamic indicators. In summary, the presence of tapering facilitated helical flow and produced better hemodynamic performance but posed a higher risk of graft migration. Conventional and deflected BBSGs with taper might be the two optimal configurations for endovascular aneurysm repair, given the helical flow. The deflected BBSG provides a better configuration, compared to the conventional BBSG, when considering the reduction of migration risk