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1.
Phys Chem Chem Phys ; 25(3): 1612-1615, 2023 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-36597985

RESUMO

First-principles calculations show a self-isomerization process of the nearly planar superatom, in which the maximum energy difference between different extreme points is below 0.1 eV and a crossing between singlet and triplet states is also involved. Further UV-Vis spectra reveal a correlation between the spectra and structures caused by self-isomerization.

2.
Phys Chem Chem Phys ; 2023 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-36688899

RESUMO

Optimizing reaction conditions to improve the yield is fundamental for chemical synthesis and industrial processes. Experiments can only be performed under a small portion of reaction conditions for a system, so a strategy of experimental design is required. Bayesian optimization, a global optimization algorithm, was found to outperform human decision-making in reaction optimization. Similarly, heuristic algorithms also have the potential to solve optimization problems. In this work, we optimize these reaction conditions for Buchwald-Hartwig and Suzuki systems by predicting reaction yields with three heuristic algorithms and three encoding methods. Our results demonstrate that particle swarm optimization with numerical encoding is better than the genetic algorithm or simulated annealing. Moreover, its performance is comparable to Bayesian optimization without the computational costs of descriptors. Particle swarm optimization is simple and easy to perform, and it can be implemented into laboratory practice to promote chemical synthesis.

3.
Huan Jing Ke Xue ; 44(1): 11-19, 2023 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-36635790

RESUMO

In recent years, the Beijing-Tianjin-Hebei region and its surrounding areas have experienced multiple haze pollution processes. Owing to the limitation of observational instruments, there has not been a comparative study of haze pollution between urban and rural areas in northern Henan province. A series of high-time-resolution instruments were used during a regional heavy pollution process (January 12-25, 2018) at two urban sites and three rural sites. The results showed that SO42-, NO-3, and NH+4 (SNA) were the components with the highest proportion in PM2.5 at the five sites during the haze event with a range of 53%-63%, of which nitrate was the most important, accounting for 24%-32%, followed by sulfate, ranging from 13%-17%. Compared with urban sites, rural sites were more affected by organic matter, especially at night. With the aggravation of pollution, the proportion of SNA increased, reaching 67% during periods of heavy pollution. When the area was affected by the air mass transported from the south, the proportion of NO-3 in PM2.5 increased, and when the area was affected by the air transport in the north, the proportions of SO42- and organic matter increased. Ammonium nitrate was the most important component that led to the decrease in atmospheric visibility during the haze process. Moreover, the contributions of ammonium nitrate and ammonium sulfate at the urban sites were higher than those at the rural sites. To summarize, there were significant differences in PM2.5 components between the urban and rural sites. Urban areas need to continue to strengthen the reduction in gaseous precursors, and rural areas need to pay attention to the sources of carbonaceous aerosol.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Material Particulado/análise , Estações do Ano , Monitoramento Ambiental/métodos , Aerossóis/análise , China
4.
Artigo em Inglês | MEDLINE | ID: mdl-36645602

RESUMO

Industrial symbiosis (IS) is an important tool to achieve green development for industrial parks. It is necessary to evaluate the IS performance for monitoring and managing the development of IS system. This study proposed an integrated framework to assess the IS performance based on the energy-intensive industrial park. Firstly, we established a Conceptual model of symbiotic coupling of three industries (iron and steel, thermal power, and cement). Then, the conceptual model was applied to extend the existing IS system in the energy-intensive industrial park. Finally, the IS performance of the extended IS system was evaluated. We verified this framework in Red flag cannel park (RFCP). The IS performance assessment in RFCP found that the existing IS activities produced significant multiple benefits and environmental impact reduction. For example, the existing IS activities produced 970.20 kt of low-carbon benefits, which accounted for 19% of the CO2 emissions in RFCP. However, after extending the existing symbiotic system combined with the conceptual model proposed in this study, we found that there still was a large amount of symbiotic potential (the reuse of waste heat, BF slag, gypsum) waiting to be developed in RFCP. In addition, we also found that the resilience of existing IS network in RFCP was weak and need to be further perfected. In general, in the further development and perfection of IS system in RFCP, the manager should not only focus on the development of IS activities among energy-intensive enterprises but also strive to foster more influential enterprises to enhance the anti-risk ability of IS network. The result indicates the integrated framework can provide support for the development and perfection of IS system in energy-intensive industrial parks.

5.
J Biomol Struct Dyn ; : 1-9, 2022 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-36495307

RESUMO

F-type ATP synthase (F-ATPase) and vacuolar ATP hydrolase (V-ATPase) are well-known biomolecular motors, which play significant catalytic roles in ATP synthesis and ATP hydrolysis reactions. Their rotational torques are important factors involved in their rotational behavior that can be measured experimentally but with considerable difficulty. To overcome this difficulty and thereby provide an in-depth understanding of their operation mechanism, we herein carry out simple and fast computer modelling to study the two proteins, using our torque approach that relies on interatomic forces and coordinates of unequilibrated configurations taken from brief molecular dynamics (MD) simulations. As predicted by the torque approach, F-ATPase is demonstrated to be a random rotor, but it prefers to rotate in clockwise direction (as seen from the membrane toward the protein) for ATP synthesis, owing to the predominantly negative angle-averaged torques. By contrast, V-ATPase tends to rotate only in counterclockwise direction for ATP hydrolysis, due to the almost uniform averaged positive torques generated by the unidirectional rotation near the three catalytic sites. The rotational behaviors of both proteins are also affected by the surrounding solvent which can promote or hinder the internal rotation. By combining the torque approach with classic force-field MD simulations, the torques of two biomolecular motors can be calculated economically, and are found to agree with previous experiments and theoretical calculations. This work demonstrates that our torque approach can be extended to the field of biology and can help gain a deeper insight into the mechanistic rotation of biomolecular motors with modest computation time.Communicated by Ramaswamy H. Sarma.

6.
J Environ Radioact ; 256: 107054, 2022 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-36330871

RESUMO

Measurement of the four radioxenon isotopes, namely 131mXe, 133mXe, 133Xe, and 135Xe, play a key role in underground nuclear test monitoring for ensuring compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). To improve detection sensitivity, a ß-γ coincidence technique is commonly used. Due to the presence of the gas matrix, such as stable xenon, nitrogen, helium, the self-attenuation effects should be taken into account when measuring different types of sample. In order to improve the accuracy of the measurement, the detection efficiencies of X-rays and γ-rays were derived by using a simulation gas calibration source with low density of sponge matrix. The detection efficiencies of ß-particles and conversion electrons (CEs) were calibrated by measuring radioxenon sample. The self-attenuation correction factors of X-rays and γ-rays were determined by Geant4 simulation method. The self-attenuation correction factors of ß-particles and CEs were provided by measuring the radioxenon samples with different volumes of xenon, nitrogen and helium.

7.
Small ; 18(46): e2200510, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36209383

RESUMO

To improve the photoelectrochemical (PEC) performance of photocatalysts, the doping strategy through covalent functionalization is often adopted to adjust material electronic structures. By contrast, this work demonstrates that the noncovalent interaction in the case of iodinated graphitic carbon nitride (g-CN) film can also enhance the PEC performance. Through a facile synthesis method of rapid thermal vapor condensation (RTVC), the prepared iodinated g-CN film shows a significantly improved photocurrent density (38.9 µA cm-2 ), three times that of pure g-CN film (13.0 µA cm-2 ) at 1.23 V versus reversible hydrogen electrode. Computations reveal that the noncovalent attachment of iodine anion (I- ) on g-CN plays a crucial role in modulating the bandgap states and broadening of the visible-light absorption range as well as the charge carrier separation with the photo-induced hole confined to I- and electron to g-CN film. The fully filled valence orbitals (4d10 5s2 5p6 ) of I- determine its noncovalent attachment on the g-CN film and so do the iodine species of I3 - , I5 - , etc. This work offers a favorable synthesis method to achieve efficient doping through noncovalent charge transfer between thin film and certain dopants and provides a useful modification strategy for the establishment of multi-channel transportation of charge carriers in general photocatalysts.

8.
ACS Omega ; 7(39): 35159-35169, 2022 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-36211039

RESUMO

Driven by a high-speed rotating electric field (E-field), molecular motors with polar groups may perform a unidirectional, repetitive, and GHz frequency rotation and thus offer potential applications as nanostirrers. To drive the unidirectional rotation of molecular motors, it is crucial to consider factors of internal charge flow, thermal noise, molecular flexibility, and so forth before selecting an appropriate frequency of a rotating E-field. Herein, we studied two surface-mounted dipolar rotors of a "caltrop-like" molecule and a "sandwich" molecule by using quantum-mechanical computations in combination with torque analyses. We find that the rotational trend as indicated by the magnitude and the direction of torque vectors can sensitively change with the lag angle (α) between the dipolar arm and the E-field. The atomic charges timely flow within the molecule as the E-field rotates, so the lag angle α must be kept in particular intervals to maintain the rotor's unidirectional rotation. The thermal effect can substantially slow down the rotation of the dipolar rotor in the E-field. The flexible dipolar arm shows a more rigid geometry in the E-field with higher rotation speed. Our work would be useful for designing E-driven molecular rotors and for guiding their practical applications in future.

9.
J Phys Chem A ; 126(41): 7452-7459, 2022 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-36205704

RESUMO

Cycloparaphenylenes ([n]CPPs) and their derivatives are known for the unique size-dependent photophysical properties, which are largely attributed to the structural planarization-associated exciton localization, attracting substantial research attention. In this work, we show that the steric hindrance between neighboring structural units plays a key role in governing the photoinduced global/local structural planarization and electron-hole distribution features of [n]CPP materials, due to the tunable strength of H···H repulsion between neighboring units via structural modification or C-H distance variation as revealed by density functional theory (DFT) and time-dependent DFT calculations. According to our results, steric hindrance controls the manner and also the extent of excited-state structural planarization, where a weak (strong) steric hindrance favors (hinders) structural planarization upon relaxation in the first excited singlet (S1) state as compared to the ground (S0)-state structure. Depending on the molecular structures, steric hindrance leads to fully delocalized, partially separated, or more localized electron-hole distributions. For example, via H···H repulsion release by manually shortening the C-H distance or by chemical substitution of C-H with N atoms, the modified [10]CPP structures show fully planarized configurations (each dihedral angle can be less than 2°) and entirely delocalized electron-hole distribution upon photorelaxation. This work provides insights into the structural origin of the unusual photophysical properties of [n]CPPs and shows the promise of steric hindrance tuning in accessing diverse excited-state features in [n]CPP materials.

10.
Basic Clin Pharmacol Toxicol ; 131(6): 500-513, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36150451

RESUMO

Cancer-derived exosomes are involved in the development of cancer cachexia. Carnosol, which exhibited ameliorating effects on cancer cachexia of C26 tumour-bearing mice in our previous study, alleviated atrophy of C2C12 myotubes induced by exosomes of C26 tumour cells in the present study. MiR-183-5p was found to be rich in C26 cells and C26 exosomes, and miR-183-5p mimic could directly induce atrophy of C2C12 myotubes. Carnosol at 5 to 20 µM could dose-dependently ameliorate the myotube atrophy induced by miR-183-5p. Four and a half LIM domain protein 1 (FHL1) was shown to be the direct target of miR-183-5p. Increase in myostatin, p-Smad3, MuRF-1, Atrogin-1, HIF-1α and p-STAT3 and decrease in mitochondrial respiration were also induced by miR-183-5p mimic in C2C12 myotubes. Carnosol could not affect the decrease in FHL-1 and the activation of STAT3 pathway but could significantly alleviate the increase in myostatin, p-Smad3, MuRF-1, Atrogin-1 and the decrease in mitochondrial respiration induced by miR-183-5p. The protective effects of carnosol on myotubes against atrophy of C2C12 myotubes induced by miR-183-5p, based on both its inhibiting effects on MuRF-1 and Atrogin-1-mediated protein degradation and its ability of keeping the mitochondrial respiration, might contribute to its ameliorating effects on cancer cachexia.


Assuntos
Abietanos , MicroRNAs , Fibras Musculares Esqueléticas , Neoplasias , Animais , Camundongos , Atrofia , Caquexia/etiologia , Caquexia/prevenção & controle , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas com Domínio LIM/metabolismo , MicroRNAs/genética , MicroRNAs/metabolismo , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patologia , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Miostatina , Neoplasias/metabolismo , Abietanos/farmacologia , Linhagem Celular Tumoral
11.
Sci Adv ; 8(38): eabo0987, 2022 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-36129984

RESUMO

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease, and the molecular mechanisms remain poorly understood. Our findings demonstrated that pyruvate kinase M2 (PKM2) promoted fibrosis progression by directly interacting with Smad7 and reinforcing transforming growth factor-ß1 (TGF-ß1) signaling. Total PKM2 expression and the portion of the tetrameric form elevated in lungs and fibroblasts were derived from mice with bleomycin (BLM)-induced pulmonary fibrosis. Pkm2 deletion markedly alleviated BLM-induced fibrosis progression, myofibroblast differentiation, and TGF-ß1 signaling activation. Further study showed that PKM2 tetramer enhanced TGF-ß1 signaling by directly binding with Smad7 on its MH2 domain, and thus interfered with the interaction between Smad7 and TGF-ß type I receptor (TßR1), decreased TßR1 ubiquitination, and stabilized TßR1. Pharmacologically enhanced PKM2 tetramer by TEPP-46 promoted BLM-induced pulmonary fibrosis, while tetramer disruption by compound 3k alleviated fibrosis progression. Our results demonstrate how PKM2 regulates TGF-ß1 signaling and is a key factor in fibrosis progression.

12.
Artigo em Inglês | MEDLINE | ID: mdl-36085573

RESUMO

BACKGROUND: Atractylenolide I (AI) is a natural sesquiterpene lactone isolated from Atractylodes macrocephala Koidz, known as Baizhu in traditional Chinese medicine. AI has been found to ameliorate cancer cachexia in clinic cancer patients and in tumour-bearing mice. Here, we checked the influence of AI on biogenesis of IL-6 and extracellular vesicles (EVs) in cancer cachexia mice and then focused on studying mechanisms of AI in inhibiting the production of tumour-derived EVs, which contribute to the ameliorating effects of AI on cancer cachexia. METHODS: C26 tumour-bearing BALB/c mice were applied as animal model to examine the effects of AI (25 mg/kg) in attenuating cachexia symptoms, serum IL-6 and EVs levels. IL-6 and EVs secretion of C26 tumour cells treated with AI (0.31-5 µM) was further observed in vitro. The in vitro cultured C2C12 myotubes and 3T3-L1 mature adipocytes were used to check the potency of conditioned medium of C26 cells treated with AI (0.625-5 µM) in inducing muscle atrophy and lipolysis. The glycolysis potency of C26 cells under AI (0.31-5 µM) treatment was evaluated by measuring the extracellular acidification rate using Seahorse XFe96 Analyser. Levels of related signal proteins in both in vitro and in vivo experiments were examined using western blotting to study the possible mechanisms. STAT3 overexpression or knockout C26 cells were also used to confirm the effects of AI (5 µM). RESULTS: AI ameliorated cancer cachexia symptoms (P < 0.05), improved grip strength (P < 0.05) and decreased serum EVs (P < 0.05) and IL-6 (P < 0.05) levels of C26 tumour-bearing mice. AI directly inhibited EVs biogenesis (P < 0.001) and IL-6 secretion (P < 0.01) of cultured C26 cells. The potency of C26 medium in inducing C2C12 myotube atrophy (+59.54%, P < 0.001) and 3T3-L1 adipocyte lipolysis (+20.73%, P < 0.05) was significantly attenuated when C26 cells were treated with AI. AI treatment inhibited aerobic glycolysis and the pathway of STAT3/PKM2/SNAP23 in C26 cells. Furthermore, overexpression of STAT3 partly antagonized the effects of AI in suppressing STAT3/PKM2/SNAP23 pathway, EVs secretion, glycolysis and the potency of C26 medium in inducing muscle atrophy and lipolysis, whereas knockout of STAT3 enhanced the inhibitory effect of AI on these values. The inhibition of AI on STAT3/PKM2/SNAP23 pathway was also observed in C26 tumour tissues. CONCLUSIONS: AI ameliorates cancer cachexia by decreasing the production of IL-6 and EVs of tumour cells. The decreasing effects of AI on EVs biogenesis are based on its inhibition on STAT3/PKM2/SNAP23 pathway.

13.
Huan Jing Ke Xue ; 43(8): 3953-3965, 2022 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-35971694

RESUMO

Air pollution in Henan province is serious and is significantly impacted by pollution transmission and interactions with surrounding areas. The emission sources in 18 cities in Henan province were labeled and applied to the WRF-CMAQ traceability model for simulation in January, April, July, and October of 2017. The pollutant distribution results showed that due to the combined influence of emissions and meteorology, the concentrations of PM2.5, NO2, and SO2 in Henan province were the highest in winter and the lowest in summer. The seasonal variation in O3-8h concentration was the highest in summer, followed by spring, and the lowest in winter. There was a large difference in pollutant concentrations between different seasons. The average concentrations of PM2.5, NO2, and SO2 in winter in Henan province were 4.17, 4.12, and 6.24 times those in summer, respectively, whereas the concentration of O3-8h in summer was 2.24 times that in winter. Since PM2.5, NO2, and SO2 are closely related to primary emissions and have a certain homology, the distributions of high values of these three pollutants were higher in the north and lower in the south, and the seasonal trends were more consistent. The seasonal distribution of O3-8h varied widely, with high O3-8h values mainly distributed in the northeastern region of Henan province in summer, when meteorological conditions contributed to O3 production; in winter, spring, and autumn, high O3-8h values were mainly distributed in the southern part of Henan province due to the suppression of meteorological conditions and NOx consumption. The results of the study on the transport of pollutants showed that extra-provincial transport and natural sources contributed the most to the concentrations of PM2.5, O3-8h, NO2, and SO2 in winter, with 36.20%-72.32%, 77.96%-96.08%, 49.45%-78.80%, and 59.05%-88.85%, respectively. When considering only local emissions and intra-provincial transmission, the contributions of emissions to local concentrations of the four pollutants in summer were the highest in all cities of Henan province. The contributions of intra-provincial transmission to PM2.5 and O3-8h in spring were the largest, with 25.63%-74.69% and 30.21%-80.01%, respectively, and the contributions of intra-provincial transmission to NO2 and SO2 in winter were larger, with 26.02%-76.96% and 20.30%-82.34%. The transmission paths of PM2.5, NO2, and SO2 were more similar in Henan province, with more transmission from north to south in winter, from west to east and southwest to northeast in spring, from southwest to northeast in summer, and from north to south in autumn; however, the transmission of PM2.5 was more complicated. The O3-8h transport path was more different from the others, especially in autumn when pollutants were mostly transported from north to south, but the O3-8h transport path from southwest to northeast was obvious.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Poluição do Ar/análise , China , Cidades , Monitoramento Ambiental/métodos , Dióxido de Nitrogênio , Material Particulado/análise , Estações do Ano
14.
Chemosphere ; 307(Pt 3): 136028, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35973498

RESUMO

Carbonaceous fractions throughout the normal period and lockdown period (LP) before and during COVID-19 outbreak were analyzed in a polluted city, Zhengzhou, China. During LP, fine particulate matters, elemental carbon (EC), and secondary organic aerosol (SOC) concentrations fell significantly (29%, 32% and 21%), whereas organic carbon (OC) only decreased by 4%. Furthermore, the mean OC/EC ratio increased (from 3.8 to 5.4) and the EC fractions declined dramatically, indicating a reduction in vehicle emission contribution. The fact that OC1-3, EC, and EC1 had good correlations suggested that OC1-3 emanated from primary emissions. OC4 was partly from secondary generation, and increased correlations of OC4 with OC1-3 during LP indicated a decrease in the share of SOC. SOC was more impacted by NO2 throughout the research phase, thereby the concentrations were lower during LP when NO2 levels were lower. SOC and relative humidity (RH) were found to be positively associated only when RH was below 80% and 60% during the normal period (NP) and LP, respectively. SOC, Coal combustion, gasoline vehicles, biomass burning, diesel vehicles were identified as major sources by the Positive Matrix Factorization (PMF) model. Contribution of SOC apportioned by PMF was 3.4 and 3.0 µg/m3, comparable to the calculated findings (3.8 and 3.0 µg/m3) during the two periods. During LP, contributions from gasoline vehicles dropped the most, from 47% to 37% and from 7.1 to 4.3 µg/m3, contribution of biomass burning and diesel vehicles fell by 3% (0.6 µg/m3) and 1% (0.4 µg/m3), and coal combustion concentrations remained nearly constant. The findings of this study highlight the immense importance of anthropogenic source reduction in carbonaceous component variations and SOC generation, and provide significant insight into the temporal variations and sources of carbonaceous fractions in polluted cities.


Assuntos
Poluentes Atmosféricos , COVID-19 , Poluentes Atmosféricos/análise , COVID-19/epidemiologia , Carbono/análise , China , Cidades , Carvão Mineral , Controle de Doenças Transmissíveis , Monitoramento Ambiental , Gasolina , Humanos , Dióxido de Nitrogênio , Material Particulado/análise , Aerossóis e Gotículas Respiratórios , Estações do Ano , Emissões de Veículos
15.
Environ Res ; 214(Pt 1): 113780, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-35779620

RESUMO

Iron-based catalysts have been demonstrated to activate peroxymonosulfate (PMS) to generate reactive radicals, which is however limited by their complex preparation process, high costs and inefficiency for practical applications. Herein we obtain spent LiFePO4 (SLFP), with powerful catalytic capacity by a simple one-step treatment of the retired LiFePO4 cathode material, for PMS activation to decontaminate organic pollutants. Lithium defects and oxygen vacancies in SLFP play critical roles for PMS utilization, further confirmed by density functional theory (DFT) calculations. SLFP materials rapidly adsorb PMS, and the surface PMS is activated by Fe(II) to generate radicals, with •OH playing a major role for the degradation of organics after multi-step reactions. The SLFP/PMS process is finally validated for ability to remove organic contaminants and potential environmental application.


Assuntos
Poluentes Ambientais , Compostos de Ferro/química , Compostos de Lítio/química , Fosfatos/química , Poluentes Químicos da Água , Oxirredução , Peróxidos , Água
16.
Sci Rep ; 12(1): 10439, 2022 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-35729205

RESUMO

P and N co-doped graphene (PNxCy-G with x = 1, 2, 3 and y = 0, 1, 2) is designed to enhance graphene reactivity with a synergistic effect of the P and N atoms for the CO oxidation reaction, focusing on the influence of the N dopant concentration on graphene. The calculated results indicate that increasing two or three coordinated N to P can facilitate charge transfer from the surface onto O2 molecules. However, the adsorbed O2 molecule breaks apart on PN3-G surface, affecting CO oxidation performance. Furthermore, PN2C1-G exhibits excellent catalytic activity towards the oxidation of CO via the ER mechanism, which catalyzes CO oxidation with the rate-determining step of only 0.26 eV for the first and 0.25 eV for the second oxidation at 0 K. Additionally, the catalytic oxidation of PN2C1-G via Eley-Rideal mechanism prefers to occur at room temperature (298.15 K), with a rate-determining step of 0.77 eV. The reaction rates at 298.15 K is calculated to be 5.36 × 1016 mol s-1. The rate constants are obtained according to harmonic transition state theory, which could be supportive for catalytic oxidation of CO on the experiment.

17.
Sci Total Environ ; 840: 156404, 2022 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-35662601

RESUMO

Secondary inorganic aerosol, including sulfate, nitrate, and ammonium (SNA), is a significant source of PM2.5 during haze episodes in Northern China. A series of high-time-resolution instruments were used in collecting PM2.5 chemical components and gaseous pollutants during a regional heavy pollution process from January 12-25, 2018, at urban and rural sites. SNA, accounting for >50% of PM2.5 at both sites, had greater importance on haze formation. Gas-phase and N2O5 hydrolysis reactions were the main formation pathways of nitrate during the daytime and nighttime, respectively. The OH radical was the primary factor for gas-phase reactions. HONO photolysis played a more critical role in OH radical formation when O3 concentration decreased during the haze episode. N2O5 hydrolysis reaction was mainly affected by O3 and aerosol water content. High relative humidity, aerosol water content, and N2O5 concentrations at the urban site enhanced the hydrolysis reactions more than those at the rural site. The aqueous-phase reactions dominated the sulfate formation with the highest rate of transition metal ion catalytic and H2O2 oxidation reactions at the urban and rural sites, respectively. Elevated relative humidity and particle acidity at the urban site resulted in a higher formation rate of aqueous-phase sulfate than at the rural site. The gas-particle partition coefficient of NH3 had a negative correlation with the particle pH, and the presence of NH3 could promote the increase of SNA concentration. Thus, more attention should be paid to the differences in SNA formation between urban and rural regions when formulating air quality policies.


Assuntos
Poluentes Atmosféricos , Material Particulado , Aerossóis/análise , Poluentes Atmosféricos/análise , China , Monitoramento Ambiental/métodos , Gases/análise , Peróxido de Hidrogênio , Nitratos/análise , Óxidos de Nitrogênio/análise , Material Particulado/análise , Estações do Ano , Sulfatos/análise , Óxidos de Enxofre , Água/química
18.
19.
Huan Jing Ke Xue ; 43(6): 2840-2850, 2022 Jun 08.
Artigo em Chinês | MEDLINE | ID: mdl-35686753

RESUMO

The COVID-19 lockdown was a typical occurrence of extreme emission reduction, which presented an opportunity to study the influence of control measures on particulate matter. Observations were conducted from January 16 to 31, 2020 using online observation instruments to investigate the characteristics of PM2.5 concentration, particle size distribution, chemical composition, source, and transport before (January 16-23, 2020) and during (January 24-31, 2020) the COVID-19 lockdown in Zhengzhou. The results showed that the atmospheric PM2.5 concentration decreased by 4.8% during the control period compared with that before the control in Zhengzhou. The particle size distribution characteristics indicated that there was a significant decrease in the mass concentration and number concentration of particles in the size range of 0.06 to 1.6 µm during the control period. The chemical composition characteristics of PM2.5 showed that secondary inorganic ions (sulfate, nitrate, and ammonium) were the dominant component of PM2.5, and the significant increase in PM2.5 was mainly owing to the decrease in NO3- concentration during the control period. The main sources of PM2.5 identified by the positive matrix factorization (PMF) model were secondary sources, combustion sources, vehicle sources, industrial sources, and dust sources. The emissions from vehicle sources, industrial sources, and dust sources decreased significantly during the control period. The results of analyses using the backward trajectory method and potential source contribution factor method indicated that the effects of transport from surrounding areas on PM2.5 concentration decreased during the control period. In summary, vehicle and industrial sources should be continuously controlled, and regional combined prevention and control should be strengthened in the future in Zhengzhou.


Assuntos
Poluentes Atmosféricos , COVID-19 , Poluentes Atmosféricos/análise , COVID-19/epidemiologia , COVID-19/prevenção & controle , China , Controle de Doenças Transmissíveis , Poeira/análise , Monitoramento Ambiental/métodos , Humanos , Tamanho da Partícula , Material Particulado/análise , Emissões de Veículos/análise
20.
Huan Jing Ke Xue ; 43(6): 2947-2956, 2022 Jun 08.
Artigo em Chinês | MEDLINE | ID: mdl-35686764

RESUMO

Based on air quality station data and satellite remote sensing data, the interannual variation characteristics and seasonal variation trends of near-surface ozone (O3) in Henan province were studied, and the variation in O3 sensitivity was analyzed. The results showed that the O3 concentration near the surface of Henan province increased first and then decreased from 2015 to 2020. The highest O3 concentration was found in 2018, and the annual mean of the maximum daily 8 h moving mean (MDA8) of O3 was 110.70 µg·m-3. The difference in MDA8 values among different stations gradually decreased. From 2015 to 2020, the average monthly MDA8 in Henan province showed an upward trend, with a growth rate of 2.46 µg·(m3·a)-1. According to the MK trend test, except for in Luohe, Nanyang, and Pingdingshan, the rising trend in other cities was significant (P<0.05). The concentration of MDA8 in the four seasons also showed an increasing trend during the 6 years as follows:autumn (19.31%)>winter (17.09%)>spring (16.82%)>summer (7.24%). From 2015 to 2019, the high value of tropospheric NO2 was concentrated in the northwest of Henan province, and the concentration showed a decreasing trend with a decreasing rate of 0.34×1015 molecules·(cm2·a)-1, whereas the tropospheric HCHO showed a slow rising trend with an annual growth rate of 0.19×1015 molecules·(cm2·a)-1, with a higher concentration in the northern urban area. The O3 sensitivity control area from 2015 to 2019 showed that most of the eastern part of Henan province belonged to the VOCs limited category.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Ozônio , Poluentes Atmosféricos/análise , Poluição do Ar/análise , China , Cidades , Monitoramento Ambiental/métodos , Ozônio/análise , Estações do Ano
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