Atmospheric oxidation capacity and O_(3) formation in a coastal city of southeast China:Results from simulation based on four-season observation

The pollution of atmospheric ozone in China shows an obvious upward trend in the past decade.However,the studies on the atmospheric oxidation capacity and O_(3)formation in four seasons in the southeastern coastal region of China with the rapid urbanization remain limited.Here,a four-season field observation was carried out in a coastal city of southeast China,using an observation-based model combining with the Master Chemical Mechanism,to explore the atmospheric oxidation capacity(AOC),radical chemistry,O_(3)formation pathways and sensitivity.The results showed that the average net O_(3)production rate(14.55 ppbv/hr)in summer was the strongest,but the average O_(3)concentrations in autumn was higher.The AOC and ROx levels presented an obvious seasonal pattern with the maximum value in summer,while the OH reactivity in winter was the highest with an average value of 22.75 sec^(-1).The OH reactivity was dominated by oxygenated VOCs(OVOCs)(30.6%-42.8%),CO(23.2%-26.8%),NO_(2)(13.6%-22.0%),and alkenes(8.4%-12.5%)in different seasons.HONO photolysis dominated OH primary source on daytime in winter,while in other seasons,HONO photolysis in the morning and ozone photolysis in the afternoon contributed mostly.Sensitivity analysis indicated that O_(3)production was controlled by VOCs in spring,autumn and winter,but a VOC-limited and NOx-limited regime in summer,and alkene and aromatic species were the major controlling factors to O_(3)formation.Overall,the study characterized the atmospheric oxidation capacity and elucidated the controlling factors for O_(3)production in the coastal area with the rapid urbanization in China.

Exploring the links between gut microbiome changes and irritable bowel syndrome in Han populations in the Tibetan Plateau

The gut microbiome shows changes under a plateau environment,while the disbalance of intestinal microbiota plays an important role in the pathogenesis of irritable bowel syndrome(IBS);however,the relationship between the two remains unexplored.In this work,we followed up a healthy cohort for up to a year before and after living in a plateau environment and performed 16S ribosomal RNA(rRNA)sequencing analysis of their fecal samples.Through evaluating the participants’clinical symptoms,combined with an IBS questionnaire,we screened the IBS sub-population in our cohort.The sequencing results showed that a high-altitude environment could lead to changes in the diversity and composition of gut flora.In addition,we found that the longer the time volunteers spent in the plateau environment,the more similar their gut microbiota composition and abundance became compared to those before entering the plateau,and IBS symptoms were significantly alleviated.Therefore,we speculated that the plateau may be a special environment that induces IBS.The taxonomic units g_Alistipes,g_Oscillospira,and s_Ruminococcus_torques,which had been proved to play important roles in IBS pathogenesis,were also abundant in the IBS cohort at high altitudes.Overall,the disbalance of gut microbiota induced by the plateau environment contributed to the high frequency of IBS and the psychosocial abnormalities associated with IBS.Our results prompt further research to elucidate the relevant mechanism.

Neurological manifestations of patients with COVID-19:potential routes of SARS-CoV-2 neuroinvasion from the periphery to the brain

Coronavirus disease 2019(COVID-19),caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),has caused a global pandemic in only 3 months.In addition to major respiratory distress,characteristic neurological manifestations are also described,indicating that SARS-CoV-2 may be an underestimated opportunistic pathogen of the brain.Based on previous studies of neuroinvasive human respiratory coronaviruses,it is proposed that after physical contact with the nasal mucosa,laryngopharynx,trachea,lower respiratory tract,alveoli epithelium,or gastrointestinal mucosa,SARS-CoV-2 can induce intrinsic and innate immune responses in the host involving increased cytokine release,tissue damage,and high neurosusceptibility to COVID-19,especially in the hypoxic conditions caused by lung injury.In some immunecompromised individuals,the virus may invade the brain through multiple routes,such as the vasculature and peripheral nerves.Therefore,in addition to drug treatments,such as pharmaceuticals and traditional Chinese medicine,non-pharmaceutical precautions,including facemasks and hand hygiene,are critically important.

Regional Metabolic Patterns of Abnormal Postoperative Behavioral Performance in Aged Mice Assessed by XH-NMR Dynamic Mapping Method

Abnormal postoperative neurobehavioral performance(APNP)is a common phenomenon in the early postoperative period.The disturbed homeostatic status of metabolites in the brain after anesthesia and surgery might make a significant contribution to APNP.The dynamic changes of metabolites in different brain regions after anesthesia and surgery,as well as their potential association with APNP are still not well understood.Here,we used a battery of behavioral tests to assess the effects of laparotomy under isoflurane anesthesia in aged mice,and investigated the metabolites in 12 different sub-regions of the brain at different time points using proton nuclear magnetic resonance('H-NMR)spectroscopy.The abnormal neurobehavioral performance occurred at 6 h and/or 9 h,and recovered at 24 h after anesthesia/surgery.Compared with the control group,the altered metabolite of the model group at 6 h was aspartate(Asp),and the difference was mainly displayed in the cortex;while significant changes at 9 h occurred predominantly in the cortex and hippocampus,and the corresponding metabolites were Asp and glutamate(Glu).All changes returned to baseline at 24 h.The altered metabolic changes could have occurred as a result of the acute APNP,and the metabolites Asp and Glu in the cortex and hippocampus could provide preliminary evidence for understanding the APNP process.

Global cavitation patterns and corresponding hydrodynamics of the hydrofoil with leading edge roughness

The objective of this paper is to experimentally investigate the cavitation patterns and corresponding hydrodynamics of the hydrofoil with leading edge roughness.The aims are to(1)understand the effect of the leading edge roughness on the hydrodynamic performance,and(2)have a good knowledge of the interaction between the leading edge roughness and the cavitation patterns.Experimental results are indicated for the NACA 66 hydrofoils with and without leading edge roughness at different incidence angles for sub and cavitation conditions.The experiments are conducted in the EPFL high-speed cavitation tunnel(Avellan 2015).The results showed that the leading edge roughness has a significant effect on the hydrodynamic performance at the sub cavitation,suppressing the formation of the incipient cavitation.The lift coefficient of the hydrofoil without leading edge roughness is larger than that of the hydrofoil with leading edge roughness,while for the drag coefficients,the results are contrary for the lift coefficient,and the maximum lift-to-drag ratio angle is delayed for the hydrofoil with leading edge roughness.The leading edge roughness modified the local pressure distribution at the leading edge region,which in turn significantly increased the minimum pressure coefficient,hence the incipient cavitation number of the hydrofoil with leading edge roughness.The formation and evolution of the transient cavity for the cloud cavitation is little affected by the leading edge roughness.

Mechanistic investigation of zwitterionic MOF-catalyzed enyne annulation using UNLPF-14-Mn^(Ⅲ) as catalyst

Hybrid quantum mechanics/molecular mechanics calculations were performed to elucidate how[Mn^(Ⅲ)porphyrin]^(+X−)-based metal-organic frameworks(MOFs)catalyze the[2+1]cycloisomerization of enynes and why zwitterionic MOFs exhibit strong activity in Lewis acid catalysis.The calculations showed that zwitterionic MOFs have a“pure cationic active center”leading to a concerted nucleophilic attack pathway with lower barriers.In contrast,metals with coordinating anions have reduced electrophilicity,resulting in a stepwise radical-type pathway with much higher barriers.Further calculations showed the nature of catalysis was strongly depended on the charge on the anion ligand.A good linear relationship between the NPA charge and barrier was found,and verified by 73 anions with small derivations,which presents a universal adaptive character for various coordinated anions.