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The objective of this study was to explain the physiological mechanisms through which Na2SeO3 mitigates the growth and developmental inhibition of pakchoi under HgCl2 stress. The results showed that treatment with HgCl2 (40 mg L−1 ) led to reduced biomass, dwarfing, root shortening, and root tip necrosis in pakchoi. Compared to control (CK), the activities of superoxide dismutase (SOD) and peroxidase (POD) in Hg treatment increased, and the content of malondialdehyde (MDA) also dramatically increased, which negatively impacted the growth of pakchoi. Low concentrations of Na2SeO3 (0.2 mg L−1 ) significantly increased the content of soluble sugars compared with control, while chlorophyll, soluble proteins, free amino acids, and vitamin C had no significant changes. The results of the mixed treatments with HgCl2 and Na2SeO3 suggested that selenium may be able to reduce the toxicity of mercury in pakchoi. The biomass, plant height, root length, chlorophyll content, soluble protein, other physiological indicators, and proline showed significant increases compared with the HgCl2 treatment. Additionally, the MDA content and mercury accumulation in pakchoi decreased. Our results revealed the antagonistic effects of selenium and mercury in pakchoi. Thus, a theoretical basis for studying pakchoi’s mercuryexcreted and selenium-rich cultivation technology was provided. [ABSTRACT FROM AUTHOR]

Isoprene has the largest global non-methane hydrocarbon emission, and the oxidation of isoprene plays a crucial role in the formation of secondary organic aerosols (SOA). Two primary processes are known to contribute to SOA formation from isoprene oxidation: (1) the reactive uptake of isoprene-derived epoxides on acidic or aqueous particle surfaces and (2) the absorptive gas-particle partitioning of low-volatility oxidation products. In this study, we developed a new multiphase condensed isoprene oxidation mechanism that include these processes with key molecular intermediates and products. The new mechanism was applied to simulate isoprene gas-phase oxidation products and SOA formation from previously published chamber experiments under a variety of conditions and atmospheric observations during the Southern Oxidant and Aerosol Studies (SOAS) field campaign. Our results show that SOA formation from most of the chamber experiments is reasonably reproduced using our mechanism except when the concentration ratios of initial nitric oxide to isoprene exceeds ~2. The SOAS simulations also reasonably agree with the measurements regarding the diurnal pattern and concentrations of different product categories. The molecular compositions of the modelled SOA indicate that multifunctional low-volatility products contribute to isoprene SOA more significantly than previously thought, with a median mass contribution of ~57% to the total modelled isoprene SOA. This contribution, however, may vary greatly, mainly dependent on the volatility estimation and treatment of particle-phase processes (i.e., photolysis and hydrolysis). Our findings emphasize that the various pathways to produce these low-volatility species should be considered in models to more accurately predict isoprene SOA formation. The new condensed isoprene chemical mechanism can be further incorporated into regional-scale air quality models, such as the Community Multiscale Air Quality Modelling System (CMAQ), to assess isoprene SOA formation on a larger scale. [ABSTRACT FROM AUTHOR]

To summarize the experience of identifying and caring for a stroke patient with ruptured internal iliac artery branch bleeding. The experience was summarized in 3 aspects, including how to recognize the presence of active bleeding in the patient, confirmation of the diagnosis and treatment of the bleeding point, prevention of postoperative complications, and rehabilitation care. After aggressive treatment and care, the patient was discharged after 30 days of hospitalization and improved. [ABSTRACT FROM AUTHOR]