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The minimization of the commutator of the Fock and density matrices as the error matrix in the direct inversion of the iterative subspace (CDIIS) developed by Pulay is a powerful self-consistent field (SCF) acceleration technique for the construction of optimum Fock matrix, if initiated with a fair initial guess. In this work, we present an alternative minimized error matrix to the commutator in the CDIIS, namely the residual or the gradient of the energy-functional for a Slater determinant subject to the orthonormality constraints among orbitals, representing the search for a newly improved Fock matrix in the direction of the residual in the direct inversion of the iterative subspace (RDIIS). Implemented in the computational chemistry package GAMESS, the RDIIS is compared with the standard CDIIS and the second order SCF orbital optimization (SOSCF) for tested molecules started with a crude guess. As a result, the RDIIS stably and efficiently performs the SCF convergence acceleration. Furthermore, the RDIIS is considerably independent on the subspace size with the concentrated linear coefficients accounting proportionally for the Fock matrices close to the current iteration.
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Volatile organic compounds (VOCs) originating from diverse sources with complex compositions pose threats to both environmental safety and human health. Photocatalytic treatment of VOCs has garnered attention due to its high efficacy at room temperature. However, the intricate photochemical reaction generates ozone (O3), causing secondary pollution. Herein, our work developed a novel "synergistic effect" system for photocatalytic co-treatment of VOCs and O3 secondary pollution. Under the optimized reactor conditions simulated with computational fluid dynamics (CFD), MgO-loaded g-C3N4 composites (MgO/g-C3N4) were synthesized as efficient catalysts for the photocatalytic synergistic treatment process. Density functional theory (DFT) calculations, characterization, and electron paramagnetic resonance (EPR) tests revealed that the addition of MgO reduced the band gap of g-C3N4, and increased O3 molecule adsorption in the composites, efficiently harnessing the synergistic effect of O3 to generate a significant quantity of reactive oxygen radicals, thereby facilitating the removal of VOCs and O3. This study provides new insights for simultaneous elimination of VOCs and O3 secondary pollution by a photocatalytic process.
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Li-rich antiperovskite (LiRAP) hydroxyhalides are emerging as attractive solid electrolyte (SEs) for all-solid-state Li metal batteries (ASSLMBs) due to their low melting point, low cost, and ease of scaling-up. The incorporation of rotational polyanions can reduce the activation energy and thus improve the Li ion conductivity of SEs. Herein, we propose a ternary rotational polyanion coupling strategy to fasten the Li ion conduction in tetrafluoroborate (BF4 -) ion doped LiRAP Li2OHCl. Assisted by first-principles calculation, powder X-ray diffraction, solid-state magnetic resonance and electrochemical impedance spectra, it is confirmed that Li ion transport in BF4 - ion doped Li2OHCl is strongly associated with the rotational coupling among OH-, BF4 - and Li2-O-H octahedrons, which enhances the Li ion conductivity for more than 1.8â times with the activation energy lowering 0.03â eV. This work provides a new perspective to design high-performance superionic conductors with multi-polyanions.
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In order to study the pollution characteristics of volatile organic compounds ï¼VOCsï¼ï¼ continuous monitoring of VOCs in two pollution processes was conducted in June and December 2021 in Zhengzhou. Combined with meteorological conditionsï¼ the pollution characteristicsï¼ source contributionsï¼ and reactivity of VOCs in winter and summer were compared and analyzed. The results showed that the volume fraction of atmospheric VOCs in two episodes were ï¼27.92±12.68ï¼×10-9 and ï¼24.30±5.93ï¼×10-9ï¼ respectively. The volume fraction of atmospheric VOCs in the haze pollution process in winter was larger than that in the ozone pollution process in summer. The analysis results of winter sources were as followsï¼ industrial source ï¼27.0%ï¼ï¼ motor vehicle source ï¼22.5%ï¼ï¼ combustion source ï¼20.1%ï¼ï¼ solvent use source ï¼16.3%ï¼ï¼ and oil and gas volatilization source ï¼14.1%ï¼. The analysis results of summer sources were as followsï¼ motor vehicle source ï¼24.8%ï¼ï¼ industrial source ï¼24.1%ï¼ï¼ solvent source ï¼17.4%ï¼ï¼ oil and gas volatilization source ï¼14.2%ï¼ï¼ combustion source ï¼11.2%ï¼ï¼ and plant source ï¼8.4%ï¼. The results of the smog production model showed that the proportion of days in the synergistic control zone of VOCs during the two pollution processes in summer ï¼66.7%ï¼ was smaller than that in winter ï¼100.0%ï¼. The secondary reaction activity results showed that the average ·OH loss rate ï¼L·OHï¼ values in winter and summer were 4.12 s-1 and 4.75 s-1ï¼ respectively. The average ozone formation potential ï¼OFPï¼ values in summer were 108.36 µg·m-3. The olefins were dominant in the top ten species due to L·OH and OFP contributions in summer. The total SOAFP values in winter in Zhengzhou were 54.38 µg·m-3. Among the top ten species contributing to SOAFP in winterï¼ nine were aromatic hydrocarbons.
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Organic acids in atmospheric particulate matter are widely involved in various physical and chemical reactions in the atmosphere and contribute greatly to the formation of secondary organic aerosols and haze pollutions. Thereforeï¼ the concentration distribution characteristicsï¼ sourcesï¼ and secondary formation of organic acids in particulate matter are of great significance for further investigation of organic aerosols and their secondary transformation. Fine particulate matter ï¼PM2.5ï¼ samples were collected in Zhengzhouï¼ and three types of organic acidsï¼ including dicarboxylic acidsï¼ fatty acidsï¼ and resin acidsï¼ were analyzed to explore their species distributionï¼ seasonal variationsï¼ source contributionï¼ and secondary generation. Malonic acid ï¼di-C3ï¼ and succinate acid ï¼di-C4ï¼ were the most abundant in the identified dicarboxylic acidsï¼ which showed obvious seasonal variations in the order of summer > autumn > winter > spring. Fatty acids had the highest concentration in winter and the lowest concentration in springï¼ showing obvious bimodal advantagesï¼ with the most abundant compounds being palmitic acid and stearic acid ï¼C18ï¼. Principal component analysis and multiple linear regression ï¼MLRï¼ were used to analyze the source of organic acids in PM2.5 in Zhengzhouï¼ the results showed that 35% of the organic acids came from combustion and traffic sourcesï¼ 24% from cooking sourcesï¼ 23% from secondary formationï¼ and 17% from natural sources. The ratios of the selected marker species ï¼i.e.ï¼ di-C3 / di-C4ï¼ F/Mï¼ and C18ï¼1 / C18ï¼ were used as tracers for the secondary formation of the organic aerosol and its aging process. The results showed that the photochemical reaction was intense in summerï¼ and the proportion of organic aerosol aging or secondary production was highï¼ whereas the photochemical reaction was weak in winterï¼ and the aging degree of organic aerosol was low. Correlation analysis and MLR were used in combination to quantify the relative contribution of gas-phase oxidation and liquid-phase oxidation to dicarboxylic acid formationï¼ and the results showed that gas-phase oxidation played a dominant role in the sampling period ï¼accounting for 58%ï¼ï¼ especially in summer ï¼61%ï¼.
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Nitrate (NO3-), sulfate (SO42-), and ammonium (NH4+) are important components of PM2.5, and studying their characteristics and influencing factors is essential for the continuous improvement of air quality. A series of online instruments were used to analyze the chemical components of PM2.5 in Zhengzhou in the summer of 2020. The results showed that the average ρ(PM2.5) was (28 ±13) µg·m-3, showing a daily variation characteristic of high at night and low during the day. The main concentrations of NO3-, SO42-, and NH4+ were (7.8 ±6.7), (7.2 ±3.7), and (5.5 ±3.1) µg·m-3, accounting for 22%, 21%, and 16% in PM2.5, respectively. The proportions of NO3- (27%) and SO42- (23%) in PM2.5, respectively, increased with the increase in PM2.5 and O3 concentration. In addition, the proportions of NO3- and NH4+ increased under low wind speed, high humidity, low temperature, and rainfall conditions. Moreover, the proportion of NO3- showed a daily variation characteristic of high at night and low during the day, whereas the opposite was true for SO42-. The gas-particle partitioning process of NH4NO3 was the main factor affecting the concentrations of NO3- and NH4+ in PM2.5. Low temperature, high humidity, and high aerosol water content concentrations favored the partitioning of HNO3 and NH3 to the particulate phase. High pH also favored the partitioning of gas-phase HNO3 to NO3-; however, it was not conducive to the partition of NH3 to NH4+. These trends partially explained the increase in the concentration and proportion of NO3- in PM2.5 under different scenarios.
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The photoelectrochemical (PEC) performance of bismuth vanadate (BiVO4) suffers from sluggish charge mobility and substantial charge recombination losses due to its intrinsic defect. To rectify the problem, we developed a novel approach to prepare an n-n+ type II BVOac-BVOal homojunction with staggered band alignment. This architecture involves a built-in electric field that facilitating the electron-hole separation at the BVOac/BVOal interface. As a result, the BVOac-BVOal homojunction shows superior photocurrent density up to 3.6 mA/cm2 at 1.23 V vs. reversible hydrogen electrode (RHE) with 0.1 M sodium sulfite as the hole scavenger, which is 3 times higher than that of the single-layer BiVO4 photoanode. Unlike the previous efforts that modifying the PEC performance of BiVO4 photoanodes through incorporating heteroatoms, the highly-efficient BVOac-BVOal homojunction was achieved without incorporating any heteroatoms in this work. The remarkable PEC activity of the BVOac-BVOal homojunction highlights the tremendous importance of reducing the charge recombination rate at the interface by constructing the homojunction and offers an effective strategy to form the heteroatoms-free BiVO4 thin film as an efficient photoanode material for practical PEC applications.
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To investigate the change characteristics of secondary inorganic ions in PM2.5 at different pollution stages before and after COVID-19, the online monitoring of winter meteorological and atmospheric pollutant concentrations in Zhengzhou from December 15, 2019 to February 15, 2020 was conducted using a high-resolution (1 h) online instrument. This study analyzed the causes of the haze process of COVID-19, the diurnal variation characteristics of air pollutants, and the distribution characteristics of air pollutants at different stages of haze.The results showed that Zhengzhou was mainly controlled by the high-pressure ridge during the haze process, and the weather situation was stable, which was conducive to the accumulation of air pollutants. SNA was the main component of water-soluble ions, accounting for more than 90%. Home isolation measures during COVID-19 had different impacts on the distribution characteristics of air pollutants in different haze stages. After COVID-19, the concentration of PM2.5 in the clean, occurrence, and dissipation stages increased compared with that before COVID-19 but significantly decreased in the development stage. The home isolation policy significantly reduced the high value of PM2.5. The concentrations of NO2, SO2, NH3, and CO were the highest in the haze development stage, showing a trend of first increasing and then decreasing. The concentration of O3 was lowest in the pre-COVID-19 development stage but highest in the post-COVID-19 development stage. The linear correlation between[NH4+]/[SO42-] and[NO3-]/[SO42-] at different time periods before and after COVID-19 was strong, indicating that the home isolation policy of COVID-19 did not change the generation mode of NO3-, and the corresponding reaction was always the main generation mode of NO3-. The correlation between[excess-NH4+] and[NO3-] was high in different periods before COVID-19, and NO3- generation was related to the increase in NH3 or NH4+ in the process of PM2.5 pollution in Zhengzhou.
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Contaminantes Atmosféricos , Contaminación del Aire , COVID-19 , Humanos , Material Particulado/análisis , Monitoreo del Ambiente/métodos , COVID-19/epidemiología , Aerosoles y Gotitas Respiratorias , Contaminantes Atmosféricos/análisis , Contaminación del Aire/análisis , Iones/análisis , Estaciones del Año , China/epidemiologíaRESUMEN
In recent years, complex air pollution with the characteristic pollutant of PM2.5 has remained serious in China. Long term exposure to PM2.5 might harm residential health and can increase premature death from specific diseases. The annual average concentration of PM2.5 in Zhengzhou was much higher than the national secondary standard, which has an extremely negative impact on the health of residents. Based on the high spatial resolution grids of population density established through web-crawling and outdoor monitoring concentrations and urban residential emissions used to evaluate PM2.5 exposure concentration, the exposure concentration of PM2.5 for urban residents of Zhengzhou was assessed, considering both indoor and outdoor exposures. Relevant health risks were quantified with the integrated exposure-response model. Finally, the contributions of various reducing measures and different standards of air quality to the decreases in PM2.5 exposure concentration were analyzed. The results showed that in 2017 and 2019, the time weighted exposure concentrations of PM2.5 for Zhengzhou's urban residents were 74.06 µg·m-3 and 60.64 µg·m-3, respectively, which was decreased by 18.12%. In addition, the mass fractions of the indoor exposure concentrations in the time weighted exposure concentrations were 83.58% and 83.01%, and its contribution to the drop of the time weighted exposure concentrations was 84.06%. In 2017 and 2019, the numbers of premature deaths attributed to PM2.5 exposures for urban residents of Zhengzhou over the age of 25 were 13285 and 10323, respectively, showing a 22.30% decrease. By using these comprehensive measures, PM2.5 exposure concentration for Zhengzhou's urban residents could be reduced by 86.23% at most, and 8902 premature deaths could be avoided.
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Contaminantes Atmosféricos , Contaminación del Aire , Humanos , Contaminantes Atmosféricos/análisis , Material Particulado/análisis , Población Urbana , Contaminación del Aire/análisis , Mortalidad PrematuraRESUMEN
The incomplete understanding of electron correlation is still profound due to the lack of exact solutions of the Schrödinger equation of many electron systems. In this work, we present the correlation-induced changes in the calculated many-electron systems beyond the standard residual. To locate the minimum of the Rayleigh quotient, each iteration is to seek the lowest eigenpairs in a subspace spanned by the current wave function and its gradient of the Rayleigh-quotient as well as the upcoming higher-order residual. Consequently, as the upcoming errors can be introduced and circumvented with the search in the higher-order residual, a concomitant improved performance in terms of number of iterations, convergence rate, and total elapsed time is very significant. The correlation energy components obtained with the original residual are corrected with the higher-order residual application, satisfying the correlation virial theorem with much improved accuracy. The comparison with the original residual, the higher-order residual significantly improves the electron binding, favoring the localization of electrons' distribution, revealed with the increasing peak of the distribution and correlation function and the reduced interelectron distance and its angle.
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From July 2020 to June 2021, monthly offline sampling of atmospheric VOCs was carried out and analyzed at three urban sites and one suburban site in Zhengzhou. Then, the volume fraction levels, composition characteristics, reactivity, and source apportionment of atmospheric VOCs were discussed. The results showed that the volume fraction of atmospheric VOCs in Zhengzhou was (37.50±14.30)×10-9 during the sampling period, and the proportion of components was represented by alkanes (33%)>OVOCs (24%)>halogenated hydrocarbons (23%)>aromatic hydrocarbons (8%)>alkenes (7%)>alkynes (4%)>sulfides (1%). The seasonal variation characteristics were winter>autumn>summer>spring, and the monthly average value of VOCs had the highest value in January and the lowest value in May; the spatial variation characteristics were Zhengzhou University (ZD)>Jiancezhan (JCZ)>Jingkaiqu (JKQ)>Gangli Reservoir (GLR). The average·OH loss rate (L·OH) was 4.24 s-1, and the average ozone formation potential (OFP) was 172.27 µg·m-3; the top ten species of L·OH and OFP at each site and in each season were dominated by alkenes, OVOCs, and aromatic hydrocarbons. The results of positive matrix factorization (PMF) showed that the main sources of VOCs were vehicle emissions (28%), solvent utilization (24%), industrial emissions (24%), and oil and gas volatilization (19%) and plant emissions (5%).
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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.
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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.
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Contaminantes Atmosféricos , Contaminación del Aire , Contaminantes Atmosféricos/análisis , Contaminación del Aire/análisis , Material Particulado/análisis , Estaciones del Año , Monitoreo del Ambiente/métodos , Aerosoles/análisis , ChinaRESUMEN
Introduction: Carnosol exhibited ameliorating effects on muscle atrophy of mice developed cancer cachexia in our previous research. Method: Here, the ameliorating effects of carnosol on the C2C12 myotube atrophy result from simulated cancer cachexia injury, the conditioned medium of the C26 tumor cells or the LLC tumor cells, were observed. To clarify the mechanisms of carnosol, the possible direct target proteins of carnosol were searched using DARTS (drug affinity responsive target stability) assay and then confirmed using CETSA (cellular thermal shift assay). Furthermore, proteomic analysis was used to search its possible indirect target proteins by comparing the protein expression profiles of C2C12 myotubes under treatment of C26 medium, with or without the presence of carnosol. The signal network between the direct and indirect target proteins of carnosol was then constructed. Results: Our results showed that, Delta-1-pyrroline-5-carboxylate synthase (P5CS) might be the direct target protein of carnosol in myotubes. The influence of carnosol on amino acid metabolism downstream of P5CS was confirmed. Carnosol could upregulate the expression of proteins related to glutathione metabolism, anti-oxidant system, and heat shock response. Knockdown of P5CS could also ameliorate myotube atrophy and further enhance the ameliorating effects of carnosol. Discussion: These results suggested that carnosol might ameliorate cancer cachexia-associated myotube atrophy by targeting P5CS and its downstream pathways.
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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.
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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.
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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.
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Abietanos , MicroARNs , Fibras Musculares Esqueléticas , Neoplasias , Animales , Ratones , Atrofia , Caquexia/etiología , Caquexia/prevención & control , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Proteínas con Dominio LIM/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patología , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Miostatina , Neoplasias/metabolismo , Abietanos/farmacología , Línea Celular TumoralRESUMEN
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.
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Contaminantes Atmosféricos , Contaminación del Aire , Contaminantes Atmosféricos/análisis , Contaminación del Aire/análisis , China , Ciudades , Monitoreo del Ambiente/métodos , Dióxido de Nitrógeno , Material Particulado/análisis , Estaciones del AñoRESUMEN
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 â¢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.
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Contaminantes Ambientales , Compuestos de Hierro/química , Compuestos de Litio/química , Fosfatos/química , Contaminantes Químicos del Agua , Oxidación-Reducción , Peróxidos , AguaRESUMEN
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.