Study of Ozone Sensitivity to Precursors at High Spatial Resolution Using the Modified CMAQ-ADJ Model

In this thesis, I apply the adjoint for the Community Multiscale Air Quality model (hereafter CMAQ-ADJ) in a high spatial resolution study of the sensitivity of ozone to several of its precursors in the regions surrounding the Great Lakes. CMAQ-ADJ was originally developed for low spatial resolution applications. In order to use it in high spatial resolution (12 km) studies, it was necessary to resolve a conflict between the pre-set fixed output time step interval in CMAQ-ADJ and the CMAQ-calculated irregular synchronization time-step and also to modify the meteorological interface for the backward model integrations. To increase computation efficiency, the chemistry time-step in the modified CMAQ-ADJ is checkpointed instead of being re-calculated in the backward part of the model as before. I used the modified model to analyze the sensitivity of ozone to precursor species for cases of assumed high ozone episode in two target locations in southwestern and east-central Ontario. The studies examined the influence of pre-existing ozone, NO, CO, anthropogenic volatile organic compounds (VOCs) and isoprene on ozone level changes for the 69 hours immediately preceding the assumed high ozone event. The results are dominated by the long-distance advection, local meteorology (lake breezes), air temperature, the underlying surface features, and emissions in the pollutant pathway. Both production and titration of ozone by NOx is evident at different times and locations in the simulations. The industrial Midwest U.S. and Ohio Valley have been shown to be an important source of anthropogenic emission of NO and most VOCs that contribute to high ozone events in southwestern and east-central Ontario. Isoprene from the northern forest suppresses ozone in both target regions, with a greater magnitude in east-central Ontario. The response of ozone level in the two selected receptor regions in Ontario to different VOCs depends on the type of VOC, the time and location they are emitted, and the air temperature. Increasing VOC emissions in urban areas such as Toronto and Ottawa in the morning can enhance the ozone level by late afternoon. Increasing VOCs except ethylene and formaldehyde in regions with large VOC/NOx ratio in the morning tends to suppress the ozone level by late afternoon. Among all the species examined, NO has the largest impact on the target ozone level changes. CO is very unlikely to significantly influence the ozone level changes in southwestern or east-central Ontario

Progress of Research on the Clinical Application of Radiation Protection Agents

With the advancement of nuclear technology, there is an increasing exposure of individuals to ionizing radiation. Incidents of radiation exposure occur occasionally, with the risk of radiation damage continuously rising. Radiation protectants are employed to prevent, alleviate, and treat ionizing radiation injuries. However, many current radiation protectants exhibit potent side effects, and there is currently no clinically established radiation protectant in routine use. Researchers have persistently endeavored to explore effective and low-toxicity radiation protectants. This article primarily focuses on internationally approved radiation protectants such as amifostine, dexrazoxane, phosphoramide mustard, polyethylene glycol-conjugated phosphoramide mustard, and sargramostim. Additionally, it discusses some natural antioxidants, resveratrol, and mesenchymal stem cells, which are currently undergoing clinical trials and promising to offer new avenues for the prevention and treatment of radiation injuries

The role of reactive oxygen species in screening anticancer agents

Development of anticancer agents with high efficacy and low toxicity has always been a challenge in cancer therapeutics. Reactive oxygen species (ROS) are one of the most important physiological stimuli and have been correlated with several cancer conditions. Cancer cells adapt to new higher ROS environment. Meanwhile, elevated ROS render cancer cells vulnerable to oxidative stress-induced cell death. Anticancer drugs are involved in inhibiting and suppressing cancer progression through ROS-mediated cell death. Thus, it is useful to study the level of ROS generated by anticancer agents in cancer cells, while sparing the normal cells, which is one of the target methods to study the pharmacological properties of anticancer agents. In this review, we discuss the relation between ROS and anticancer agents, as well as the application of ROS in anticancer agents' activity screening

Reduction kinetics of hematite powder in hydrogen atmosphere at moderate temperatures

Hydrogen has received much attention in the development of direct reduction of iron ores because hydrogen metallurgy is one of the effective methods to reduce CO2 emission in the iron and steel industry. In this study, the kinetic mechanism of reduction of hematite particles was studied in a hydrogen atmosphere. The phases and morphological transformation of hematite during the reduction were characterized using X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy. It was found that porous magnetite was formed, and the particles were degraded during the reduction. Finally, sintering of the reduced iron and wüstite retarded the reductive progress. The average activation energy was extracted to be 86.1 kJ/mol and 79.1 kJ/mol according to Flynn-Wall-Ozawa (FWO) and Starink methods, respectively. The reaction fraction dependent values of activation energy were suggested to be the result of multi-stage reactions during the reduction process. Furthermore, the variation of activation energy value was smoothed after heat treatment of hematite particles.(OLD) MSE-

Acute benzo[a]pyrene treatment causes different antioxidant response and DNA damage in liver, lung, brain, stomach and kidney

Acute effects of oxidative damage induced by benzo[a]pyrene (B[a]P) on various organs are still not clear. In this study, we investigated oxidative stress and DNA damage in liver, lung, stomach, brain and kidney of ICR male mice induced by acute B[a]P treatment. B[a]P treatment led to a significant decrease at the different doses in body weight. For the variations of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), glutathione (GSH) and GSH/GSSG, significant increases were observed at 24 h, then decreased till 72 h after B[a]P injection. The increase percent indicated in a dose- dependent decrease manner. However, glutathione peroxidase (GPx), GSSG and MDA were significantly increased in a time- and dose-dependent increase manner. DNA damage showed the significant and top levels at 24 h, and increased in proportion to the doses of B[a]P treatment. The total induction could be indicated by the variation of MDA at 24 h after B[a]P injection and showed the following order of predominance: lung > liver > kidney = stomach > brain. This was further certificated by histopathological changes in the examined organs. Additionally, the levels of serum glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), and blood urea nitrogen (UN), creatinine were also significantly increased at 24 h after B[a]P injection. These findings suggested the disturbance of antioxidant responses and aggravation of DNA damages, and the different responses on various organs induced by acute B[a]P treatment in organism

Effect of Fe on the Microstructure and Mechanical Properties of Fe/FeAl2O4 Cermet Prepared by Hot Press Sintering

The Fe/FeAl2O4 cermet was prepared with Fe-Fe2O3-Al2O3 powder by a hot press sintering method at 1400 °C. The raw materials for the powder particles were respectively 2 µm (Fe), 0.5 µm (Fe2O3), and 0.5 µm (Al2O3) in diameter, the sintering pressure was 30 MPa, and the holding time was 120 min. The effects of different Fe mass ratios on the microstructure and mechanical properties of Fe/FeAl2O4 cermet were studied. The results showed that a new ceramic phase FeAl2O4 could be formed by an in situ reaction during the hot press sintering. When the Fe mass ratio was increased, the microstructure and mechanical properties of the Fe/FeAl2O4 cermet showed a change law that initially became better and then became worse. The best microstructure and mechanical properties were obtained in the S2 sample, where the mass ratio of Fe-Fe2O3-Al2O3 was 6:1:2. In this Fe mass ratio, the relative density was about 94%, and the Vickers hardness and bending strength were 1.21 GPa and 210.0 MPa, respectively. The reaction mechanism of Fe in the preparation process was the in situ synthesis reaction of FeAl2O4 and the diffusion reaction of Fe to FeAl2O4 grains. The increase of the Fe mass ratio improved the wettability of Fe and FeAl2O4, which increased the diffusion rate of Fe to FeAl2O4 grains, which increased the influence on the structure of FeAl2O4

Template preparation of nanoscale CexFe1-xO2 solid solutions and their catalytic properties for ethanol steam reforming

High-surface-area CexFe1-xO2 solid solutions with about 5 nm in size have been successfully prepared by using ultrahigh surface area carbon material as template and cerium and iron nitrates as oxide precursor. The obtained materials were characterized by means of N2 physisorption, X-ray diffraction, Raman spectroscopy, electron paramagnetic resonance, transmission electron microscopy and energy dispersive X-ray spectroscopy. The redox and catalytic properties of the nanoscale CexFe1-xO2 solid solutions were also evaluated by temperature-programmed reduction and ethanol steam reforming. The results confirm the formation of the nanoscale CexFe1-xO2 solid solutions with cubic phase with fluorite structure, and the process of Ce4+ substitution by the Fe3+ gradually from surface to bulk of CeO2. A small addition of Fe into CeO2 resulted in a remarkable increase in the surface area and oxygen vacancy concentration, and decease the particle size of the solid solution, while further Fe addition decreases the surface area and vacancy concentration of the solid solution ,and increases the particle size of the solid solution. The results from temperature-programmed reduction show that addition of Fe into CeO2 does not only promote the reduction of CeO2, but also increase the oxygen vacancy concentration. The CexFe1-xO2 solid solutions show a significant catalytic activity toward ethanol steam reforming with above 64 % selectivity to hydrogen at 550 oC. The Ce0.90Fe0.10O2 sample presents the superior activity and selectivity to hydrogen compared to CeO2, Fe2O3 and the other solid solutions. The findings exhibit that the carbon template route may be of great potential in synthesis of other solid solutions, and the CexFe1-xO2 solid solutions are potential materials with oxygen storage and ethanol steam reforming

Energy storage economy research and sensitivity analysis applied to photovoltaic primary frequency modulation scenario

In practical engineering applications, the investment, income, subsidies and other costs of energy storage batteries have a certain impact on the overall economic benefits of primary frequency modulation. The larger the capacity of the configured battery energy storage system, the better the primary frequency modulation effect will be, but at the same time, the problem is that the cost of investment in the energy storage system will increase, which will offset the benefits of primary frequency modulation loss reduction of its auxiliary photovoltaic station from an economic perspective. Therefore, this paper will clarify the benefits and costs of the primary frequency modulation application environment of the energy storage system, and establish an economic analysis model from delaying the investment of photovoltaic station equipment, reducing the cost of light waste, environmental benefits, direct benefits, government subsidies, energy storage investment costs and other aspects. Finally, a photovoltaic station is taken as an example to simulate and analyse the sensitivity