Table S1: Mass fraction of soluble cations for the mineral dust samples investigated in this work.Table S2: Mass fraction of soluble anions for the mineral dust samples investigated in this work.
Abstract. Haze pollution is a severe environmental problem, caused by elevation of fine particles (aerodynamic diameter < 2.5 μm, PM2.5), which is related to secondary aerosol formation, unfavourable synoptic conditions, regional transport, etc. The regional haze formation in basin areas, along with intensive emission of precursors, high relative humidity and poor dispersion conditions, is still limitedly understood.In this study, a field campaign was conducted to investigate the factors resulting in haze formation in Sichuan Basin (SCB) during winter in 2021. The fine aerosol chemical composition was characterised by using a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) with the aim of inorganic and organic aerosol characterisation and source apportionment. The average concentration of non-refractory fine particles (NR-PM2.5) was 98.5 ± 38.7 μg/m3, and organics aerosols (OA), nitrate, sulphate, ammonium, and chloride occupied 40.3, 28.8, 10.6, 15.3 and 5.1 % of PM2.5. Three factors, including a hydrocarbon-like OA (HOA), a biomass burning OA (BBOA), and an oxygenated OA (OOA), were identified by applying the positive matrix factorisation (PMF) analysis, and they constituted 24.2, 24.2 and 51.6 % of OA on average, respectively. Nitrate formation was promoted by gas-phase and aqueous-phase oxidation, while sulphate was mainly formed through aqueous-phase. OOA showed strong dependence on Ox, demonstrating the contribution of photooxidation to OOA formation. OOA concentration increased as aerosol liquid water content (ALWC) increased within 200 μg/m3 and kept relatively constant when ALWC > 200 μg/m3, suggesting the insignificant effect of aqueous-phase reactions on OOA formation. Among the three haze episodes identified during the whole campaign, the driving factors were different: the first haze episode (H1) was driven by nitrate formation through photochemical and aqueous-phase reactions, and the second haze episode (H2) was mainly driven by the intense emission of primary organic aerosols from biomass burning and vehicle exhaust, while the third haze episode (H3) was mainly driven by reactions involving nitrate formation and biomass burning emission. HOA and BBOA were scavenged, while OOA, nitrate, and sulphate formation were enhanced by aqueous-phase reactions during fog periods, which resulted in the increase of O:C from pre-fog to post-fog periods. This study revealed the factors driving severe haze formation in SCB, and implied the benefit of controlling nitrate as well as intense biomass burning and vehicle exhaust emission to the mitigation of heavy aerosol pollution in this region.
Abstract. Calcium- and magnesium-containing salts are important components for mineral dust and sea salt aerosols, but their physicochemical properties are not well understood yet. In this study, the hygroscopic properties of eight Ca- and Mg-containing salts, including Ca(NO3)2 · 4H2O, Mg(NO3)2 · 6H2O, MgCl2 · 6H2O, CaCl2 · 6H2O, Ca(HCOO)2, Mg(HCOO)2 · 2H2O, Ca(CH3COO)2 · H2O and Mg(CH3COO)2 · 4H2O, were systematically investigated using two complementary techniques. A vapor sorption analyzer was used to measure the change of sample mass with relative humidity (RH) under isotherm conditions, and the deliquescence relative humidities (DRH) for temperature in the range of 5–30 °C as well as water-to-solute ratios as a function of RH at 5 and 25 °C were reported for these eight compounds. DRH values showed a large variation for these compounds; for example, at 25 °C the DRH values were measured to be ~ 28.5 % for CaCl2 · 6H2O and > 95 % for Ca(HCOO)2 and Mg(HCOO)2 · 2H2O. In addition, a humidity-tandem differential analyzer was used to measure the change in mobility diameter with RH (up to 90 %) at room temperature, in order to determine the hygroscopic growth factors of aerosol particles generated by atomizing water solutions of these eight compounds. All the aerosol particles studied in this work, very likely to be amorphous, started to grow at very low RH (as low as 10 %) and showed continuous growth with RH. The hygroscopic growth factors at 90 % RH were found to range from 1.26 ± 0.04 for Ca(HCOO2)2 and 1.79 ± 0.03 for Ca(NO3)2, varying significantly for the eight types of aerosols considered herein. Overall, our work provides a systematical and comprehensive investigation of the hygroscopic properties of these Ca- and Mg-containing salts, largely improving our knowledge in the physicochemical properties of mineral dust and sea salt aerosols.
We present the implementation of a hybrid continuum-atomistic model for including the effects of surrounding electrolyte in large-scale density functional theory (DFT) calculations within the ONETEP linear-scaling DFT code, which allows the simulation of large complex systems such as electrochemical interfaces. The model represents the electrolyte ions as a scalar field and the solvent as a polarisable dielectric continuum, both surrounding the quantum solute. The overall energy expression is a grand canonical functional incorporating the electron kinetic and exchange correlation energies, the total electrostatic energy, entropy and chemical potentials of surrounding electrolyte, osmotic pressure, and the effects of cavitation, dispersion and repulsion. The DFT calculation is performed fully self-consistently in the electrolyte model, allowing the quantum mechanical system and the surrounding continuum environment to interact and mutually polarize. A bespoke parallel Poisson-Boltzmann solver library, DL_MG, deals with the electrostatic problem, solving a generalized Poisson-Boltzmann equation. Our model supports open boundary conditions, which allows the treatment of molecules, entire biomolecules or larger nanoparticle assemblies in electrolyte. We have also implemented the model for periodic boundary conditions, allowing the treatment of extended systems such as electrode surfaces in contact with electrolyte. A key feature of the model is the use of solute-size and solvation-shell-aware accessibility functions that prevent the unphysical accumulation of electrolyte charge near the quantum solute boundary. The model has a small number of parameters: here we demonstrate their calibration against experimental mean activity coefficients. We also present an exemplar simulation of a 1634-atom model of the interface between a graphite anode and LiPF<sub>6</sub> electrolyte in ethylene carbonate solvent. We compare the cases where Li atoms are intercalated at opposite edges of the graphite slab and in solution, demonstrating a potential application of the model in simulations of fundamental processes in Li-ion batteries.
Whereas traditional finite element methods use meshes to define domain geometry, weighted extended B-spline finite element methods rely on a weight function. A weight function is a smooth, strictly positive function which vanishes at the domain boundary at an appropriate rate. We describe a method for generating weight functions for a general class of domains based on A-splines. We demonstrate this approach and address the relationship between weight function quality and error in the resulting finite element solutions.
Recent studies have shown that circRNAs can act as oncogenic factors or tumor suppressors by sponging microRNAs (miRNAs). The upregulation of circ_0023984 was reported in esophageal squamous cell carcinoma (ESCC). However, its functional role in ESCC remain unclear. In the present study, circ_0023984 expression in ESCC cells and tissues were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting (WB). Subcellular fraction experiment was performed to determine relative nuclear-cytoplasmic localization. The loss-of-function effects of circ_0023984 in ESCC cell lines were investigated by shRNA-mediated knockdown. Functional assays including cell Counting Kit-8 (CCK-8), 5-Ethynyl-2'-deoxyuridine (EDU) incorporation, colony formation and Transwell migration assays were conducted to assess the malignant phenotype. The interaction between the two molecules was analyzed by RNA pull-down, luciferase reporter assay and RNA immunoprecipitation (RIP). The subcutaneous tumor model in nude mice was used to assess the role of circ-0023984 in tumorigenesis. We found that ESCC patients with high circ_0023984 expression was associated with a poor prognosis. The knockdown of circ_0023984 suppressed cell growth, invasion, and migration in ESCC cells. Circ_0023984 interacted with miR-134-5p and inhibited its activity, which promoted the expression of CST4 (Cystatin-S). Circ_0023984 also regulated tumorigenesis in a CST4-dependent manner. Together, our study indicates that the oncogenic role of Circ_0023984 is mediated by miR-134-5p/CST4 Axis in ESCC, which could serve as potential targets for future therapeutic strategies.
Effectively harvesting light to generate long-lived charge carriers to suppress the recombination of electrons and holes is crucial for photocatalytic reactions. Exposing the highly active facets has been regarded as a powerful approach to high-performance photocatalysts. Herein, a hybrid comprised of {001} facets of TiO2 nanosheets and layered Ti3C2, an emerging 2D material, was synthesized by a facile hydrothermal partial oxidation of Ti3C2. The in situ growth of TiO2 nanosheets on Ti3C2 allows for the interface with minimized defects, which was demonstrated by high-resolution transmission electron microscopy and density functional theory calculations. The highly active {001} facets of TiO2 afford high-efficiency photogeneration of electron–hole pairs, meanwhile the carrier separation is substantially promoted by the hole trapping effect by the interfacial Schottky junction with 2D Ti3C2 acting as a reservoir of holes. The improved charge separation and exposed active facets dramatically boost the photocatalytic degradation of methyl orange dye, showing the promise of 2D transition metal carbide for fabricating functional catalytic materials.
The International Conference on Software Maintenance and Evolution is the premier international forum for researchers and practitioners from academia, industry, and government to present, discuss, and debate the most recent ideas, experiences, and challenges in software maintenance and evolution.
Abstract. Haze pollution is a severe environmental problem, caused by elevation of fine particles (aerodynamic diameter < 2.5 μm, PM2.5), which is related to secondary aerosol formation, unfavourable synoptic conditions, regional transport, etc. The regional haze formation in basin areas, along with intensive emission of precursors, high relative humidity and poor dispersion conditions, is still limitedly understood.In this study, a field campaign was conducted to investigate the factors resulting in haze formation in Sichuan Basin (SCB) during winter in 2021. The fine aerosol chemical composition was characterised by using a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) with the aim of inorganic and organic aerosol characterisation and source apportionment. The average concentration of non-refractory fine particles (NR-PM2.5) was 98.5 ± 38.7 μg/m3, and organics aerosols (OA), nitrate, sulphate, ammonium, and chloride occupied 40.3, 28.8, 10.6, 15.3 and 5.1 % of PM2.5. Three factors, including a hydrocarbon-like OA (HOA), a biomass burning OA (BBOA), and an oxygenated OA (OOA), were identified by applying the positive matrix factorisation (PMF) analysis, and they constituted 24.2, 24.2 and 51.6 % of OA on average, respectively. Nitrate formation was promoted by gas-phase and aqueous-phase oxidation, while sulphate was mainly formed through aqueous-phase. OOA showed strong dependence on Ox, demonstrating the contribution of photooxidation to OOA formation. OOA concentration increased as aerosol liquid water content (ALWC) increased within 200 μg/m3 and kept relatively constant when ALWC > 200 μg/m3, suggesting the insignificant effect of aqueous-phase reactions on OOA formation. Among the three haze episodes identified during the whole campaign, the driving factors were different: the first haze episode (H1) was driven by nitrate formation through photochemical and aqueous-phase reactions, and the second haze episode (H2) was mainly driven by the intense emission of primary organic aerosols from biomass burning and vehicle exhaust, while the third haze episode (H3) was mainly driven by reactions involving nitrate formation and biomass burning emission. HOA and BBOA were scavenged, while OOA, nitrate, and sulphate formation were enhanced by aqueous-phase reactions during fog periods, which resulted in the increase of O:C from pre-fog to post-fog periods. This study revealed the factors driving severe haze formation in SCB, and implied the benefit of controlling nitrate as well as intense biomass burning and vehicle exhaust emission to the mitigation of heavy aerosol pollution in this region.
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