Oxidation Ratio Research Articles

Controlling tin oxysulfide thin film compositions and electronic band structures using atomic layer deposition and vacuum annealing process

In this work, we investigated anion-mixed tin oxysulfide thin films in order to search for stable p-type semiconductor materials that can be deposited through atomic layer deposition (ALD). Tin oxysulfide thin films were fabricated through super-cycle repetition of tin sulfide and tin oxide thin films including vacuum annealing process and were analyzed via grazing-incidence X-ray diffraction (GI-XRD), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV–vis.) spectroscopy, and ultraviolet photoelectron spectroscopy (UPS) to investigate the crystallinity, grain size, atomic composition, and electrical and optical properties of the materials according to their ratio of tin sulfide and tin oxide. AES analysis showed that the composition of the thin films changed corresponding to the ratio between sulfur and oxygen. Orthorhombic SnS and rutile SnO2 phase were mixed in the tin oxysulfide thin films. Oxygen from the tin oxides diffused into tin sulfides to produce sulfur vacancies, which changed to p-type characteristics by increasing the oxygen ratio. Through this work, anion-mixed p-type semiconductors with good phase stability can be synthesized and are expected to be applicable to various fields such as p-type material-based transistors, thin film transistors (TFT) and photodetection, biochemical sensors, and photovoltaic energy devices.

Preparation of Monolayer Dispersed Fe/Attapulgite Desulfurizer and Its Desulfurization Performance at Low Temperature

AbstractFe/ATP (attapulgite) desulfurizers with different loads were prepared by precipitation method. XRD profiles revealed that the loading threshold of monolayer dispersion was 28.75 %. The desulfurizers were characterized by UV‐vis, FT‐IR, TPR, BET, and SEM. The performances of desulfurizers with different loads were compared. When the loading reached the threshold, both the sulfur capacity of the desulfurizer and the availability ratio of iron oxides were the highest. Beyond the threshold, the amount of Fe3+ bound to the skeleton of ATP increased to form skeleton iron, and some iron oxides gathered together, causing decreases in the sulfur capacity. The dissolution amount of Fe3+ showed the bonding strength between active components and ATP by acid dissolution experiments, which became stronger with increases of skeleton iron. Processes of deactivation were fitted by the deactivation model, which revealed that the changes in loadings would impact the deactivation of desulfurizers.

Oxy-methane combustion characteristics in a vertical porous plate reactor

Among the carbon capture technologies, oxy-fuel combustion is more competitive in terms of efficiency and cost. However, pure oxygen is required for oxy-combustion, and the oxygen separation from the air by conventional methods is costly and energy-intensive. Ion transport membranes (ITMs) have shown considerable improvement in energy efficiency. The current ITMs suffer from low O2 permeation flux required for practical fuel conversion rates. The experimental and numerical methodologies are not much developed in studying the ITM integrated reactors. Therefore, using a porous medium can give much insight into the technology. Understanding the flow dynamics and combustion properties inside an oxygen transport membranes reactor (OTMR) is of utmost importance to developing efficient systems. Most studies have focused on analyzing face-to-face horizontal porous plate reactor designs. A horizontal reactor’s flame structure and buoyancy effect are substantially different from that of a vertical reactor. Hence, the current study aims to investigate oxy-methane combustion in a vertical face-to-face porous plate reactor to mimic the performance of an OTMR using computational fluid dynamics (CFD). Axial and transverse temperature profiles and species concentration profiles are analyzed concerning the feed inlet flow rates, inlet temperature, and oxidizer ratio in this work. The outlet and maximum temperatures vary from 1,587 K to 1,621 K and 1,751 K to 2,341 K upon increasing the oxidizer ratio from 0.20 to 0.35; correspondingly, it shows that the maximum temperature within the reactor is significantly affected by the oxidizer ratio. In the vertical OTMR, the maximum and outlet temperatures are lowered by 82 K and 53 K, respectively, compared to the horizontal one because of the uniform temperature distribution in the former case. This research will help to improve reactor design for OTMR applications. Further investigations on the flame structure and static flame stability are required for a better understanding and insight into the reactor design.

Pollution Characteristics and Sources of Water-soluble Ions in PM2.5 in Zhengzhou City

In order to explore the pollution characteristics, seasonal variations, and sources of water-soluble inorganic ions (WSIIs) in PM2.5 in Zhengzhou, PM2.5 samples were seasonally collected from December 2020 to October 2021; then, combining gaseous pollutants (SO2, NO2, and O3) and meteorological parameters (temperature and relative humidity), nine WSIIs (NO3-, NH4+, SO42-, Ca2+, K+, Na+, Mg2+, F-, and Cl-) were analyzed. The results showed that the annual average concentration of the total water-soluble ions (TWSIIs) was (39.34±21.56) μg·m-3for the four seasons, showing obvious seasonal variations with the maximum value in winter and the minimum value in summer. Annual PM2.5 was slightly alkaline in Zhengzhou, and NH4+ most likely existed in the form of NH4NO3 and (NH4)2SO4. The average sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) were 0.35 and 0.19, respectively, indicating that SO42- and NO3- mainly derived from secondary formation. The main potential source regions of WSIIs obtained by the concentration weight trajectory (CWT) model showed temporal and spatial variations. The significant sources of WSIIs based on principal component analysis (PCA) were dust, secondary generation, combustion, and industrial activities, which were obviously influenced by wind direction and speed in Zhengzhou.

Structural and Improper Ferroelectric Properties of TbInO3 Single Crystal Grown by Laser Floating Zone

The honeycomb TbInO3 has attracted wide research attention due to its fascinating physical properties. However, TbInO3 single crystal was difficult to grow owing to the high melting point and serious volatilization of indium during the crystal growth. In this study, the volatilization of the indium element was effectively suppressed by controlling the growth atmosphere and pressure. The excess ratio of indium oxide was determined, and pure hexagonal TbInO3 crystal was obtained by the laser floating zone method. Systematic studies on the crystal structure and optical and ferroelectric properties were carried out. The structure distortion resulted in the improper geometric ferroelectric revealed by single crystal diffraction and Raman spectrum measurements. The topological vortex domains and P-E hysteresis loop demonstrated the presence of ferroelectricity. TbInO3 crystal has great potential application in vortex memory.

On-board measurements using two successive vehicles to assess in-cabin concentrations of on-road pollutants

Gaseous and particulate pollutants are produced in large quantities from road vehicles. These traffic-related air pollutants can infiltrate the car-cabins exposing drivers and passengers to toxic substances with serious adverse health effects. The infiltration process depends on many parameters, those from outside of the vehicle (e.g. traffic intensity, meteorology, road type) and those depending on the vehicle itself such as the ventilation and/or the vehicle speed/age. In the present study, we undertook on-road measurements to assess the impact of ventilation and vehicles spacing (proximity effect) on in-cabin to on-road (I/O) concentration ratios of nitrogen oxides (NOx) and ultrafine particles (UFP). The novelty of the present work is that two successive vehicles have been used to circumvent the influence of the emissions of the upstream vehicle on the downstream test vehicle. We show that the distance to the upstream vehicle influences significantly the (I/O) ratios. Overall, the results show that car cabin is less polluted when the ventilation is set to recirculation mode and keeping a distance to the upstream car corresponding to twice its height in non-idle conditions.

Hydration activity and expansibility of different divalent metal oxide solution compositions in steel slag

Steel slag (SS) accounts for 15–20% of steelmaking output; its application in cement concrete has been limited because of poor stability. In this study, the divalent metal oxide solid solution (RO phase) in SS was analogue synthesised to study its hydration activity and expansibility. The results showed that the hydration activity and expansibility of magnesium oxide (MgO) in the analogue-RO phase is affected by the content of ferrous oxide (FeO); with the increase of molar ratio (x) of iron oxide to magnesium oxide in the analogue-RO phase, the autoclave expansion rate and hydration activity of the cement paste decreased. When x ≤ 0.5, the RO phase had high hydration activity and could cause poor soundness of SS. When x = 1, the RO phase had low hydration activity and could cause slight expansion of SS. When x ≥ 2, the RO phase had no hydration activity and could not cause any expansion of SS. The control of different analogue-RO phase compositions induced different hydration and expansibility, which provided a theoretical basis for the influence of the RO phase on the soundness of SS and enabled measures to be proposed to reduce the expansion of SS, thereby promoting high-volume utilisation of SS in cement and concrete.

Soil Organic Matter Composition in Urban Soils: A Study of Wrocław Agglomeration, SW Poland

In urban areas, because of anthropopressure, the transformation of the soil cover can lead to the complete destruction of the natural layout and properties of these soils. The object of this study was to determine the quantity and quality of soil organic matter (SOM) originating in the topsoil horizons of the central part of Wroclaw (SW of Poland). Fractional composition of SOM and humic substances (HS) analysis were performed. Elemental composition and CP MAS 13C NMR spectra for the humic acids (HA) were determined, and α (aromaticity) and ω (oxidation) ratios were calculated. Total organic carbon content ranged from 22.39 to 66.1 g kg–1, while that of total nitrogen ranged from 2.09 to 4.6 g kg1. In most analysed urban soils, the highest share in SOM was found for residual carbon (CR), while HA of low maturity was the predominant group over FA. CP MAS 13C NMR spectroscopy of HA molecules indicated the structure of the samples was dominated by compounds with low aromaticity cores and considerable contents of aliphatic components. In urban soils, efforts should be made to enhance organic matter transformation into more matured and stable forms via, e.g., compost application and chemical treatments, and lawn maintenance should be very strictly controlled and limited.

Oxide–Metal–Oxide Based Transparent Electrodes and Their Potential Application in Semitransparent Perovskite Solar Cells‐Optical Modeling Studies

Oxide–metal–oxide (OMO)‐based stacks are highly attractive by virtue of their favorable properties for being used as a top transparent electrode (TE) in semitransparent solar cells. Herein, getting the best trade‐off between performance and transparency is focused on by optimizing the OMO electrode and the device layers with the help of optical simulation. NiO/Ag/SnO2 as the OMO electrode integrated into a device having SnO2, Spiro‐OMeTAD, and MAPbI3 as the electron transport layer, hole transport layer, and photoactive layer, respectively, in n–i–p geometry is investigated. It is shown that an optimized OMO electrode in terms of average visible transparency (AVT) does not translate to the best device performance. It is found that for the overcoat to undercoat oxide layer ratio of 1.17, a maximum short‐circuit current density (JSC) of 4.34 mA cm−2 is achieved while a maximum AVT of 21.55% is obtained for a ratio of 0.78. On further optimization of the MAPbI3 thickness, for an oxide ratio of 1, a modeled device with 4.58 mA cm−2 with AVT of 31.55% is demonstrated. In addition, it is also found that by integrating an optical spacer layer after the OMO electrode, the JSC of the device shows a jump of >115% to 9.86 mA cm−2.

Heterogeneous Catalytic and Non-Catalytic Supercritical Water Oxidation of Organic Pollutants in Industrial Wastewaters Effect of Operational Parameters

This work reports supercritical water oxidation (SCWO) of organic pollutants in industrial wastewater in the absence and presence of catalysts. To increase the efficiency of the oxidation process, the SCWO of organic compounds in industrial wastewater was performed in the presence of various iron- and manganese-containing heterogeneous catalysts (Fe-Ac, Fe-OH, and Mn-Al). The catalytic and non-catalytic SCWO of organic compounds in wastewater from PJSC “Nizhnekamskneftekhim”, generated from the epoxidation of propylene with ethylbenzene hydroperoxide in the process of producing propylene oxide and styrene (PO/SM), was performed. The effect of operational parameters (temperature, pressure, residence time, type of catalysts, oxygen excess ratio, etc.) on the efficiency of the process of oxidation of organic compounds in the wastewater was studied. SCWO was studied in a flow reactor with induction heating under different temperatures (between 673.15 and 873.15 K) and at a pressure of 22.5 MPa. The reaction time ranged from 1.8 to 4.83 min. Compressed air was used as an oxidizing agent (oxidant) with an oxidant ratio of two to four. A pseudo-first-order model expressed the kinetics of the SCWO processes, and the rate constants were evaluated. In the present work, in order to optimize the operation parameters of the SCWO process, we used the thermodynamic properties of near- and supercritical water by taking into account the asymmetric behavior of the liquid–vapor coexistence curve.

Ti, F Codoped Sodium Manganate of Layered P2-Na 0.7 MnO 2.05 Cathode for High Capacity and Long-Life Sodium-Ion Battery

Ti, F Codoped Sodium Manganate of Layered P2-Na _0.7 MnO _2.05 Cathode for High Capacity and Long-Life Sodium-Ion Battery

Effect of Oxygen on Water Vapor Oxidation of Fe by Oxygen Partial Pressure Control Using Gas Sensor

An oxygen pump sensor was installed in front of an oxidation furnace to supply and discharge oxygen to the Ar–H2O atmosphere and accurately control the oxygen partial pressure in the atmosphere. Furthermore, the oxidation rate was set after the oxidation furnace. It was measured by an oxygen sensor and a hydrogen sensor. Pure iron was used as the sample. The purpose of this study was to clarify the oxidation behavior of water vapor and oxygen. As a result, it was clarified that the amount of hydrogen generated by the oxidation of water vapor and Fe decreases when oxygen is supplied. In addition, when the oxygen supply amount increased, oxidation by the water vapor did not occur. On the other hand, it was clarified that when oxygen in the atmosphere is discharged, oxidation by oxygen is suppressed and only oxidation by the water vapor occurs. In the cross-sectional microstructure after oxidation, Fe3O4 was formed in the outer layer in the environment where the oxygen was discharged, but by supplying oxygen, the oxide layer became thicker and Fe2O3 was formed in the outer layer. The mass gain increased as the oxygen was supplied. Considering the ratio of oxidation by water vapor and oxidation by oxygen, it was clarified by this method that the mass gain is greater when the oxidation by oxygen is dominant.

Oxidized LDL and Risk of Coronary Heart Disease

Oxidized LDL cholesterol (ox-LDL) is considered to be a key factor of initiating and accelerating coronary heart disease CHD and diabetes Mellitus DM , is associated with several mechanisms one of them Oxidative stress. The aim of this study was to find the association between ox- LDL ,HDL-C , TG , LDL-C and arylesterase , with CHD risk in different age groups in males and females , the difference in these risk factors can explain the sex difference and how much the changes in the risk factors levels in CHD and CHD with DM patients between age groups.
 Methods: determination biochemical parameters of serum blood of ox-LDL , TG , TC , HDL-c , LDL-c , S. Glucose and arylesterase activity were measured in cases male and females were carried CHD and CHD with DM .The cases divided in different the age groups (40-49) , (50-59) and (60-69) years and compered the result with control groups .
 Results: mean Value of ox-LDL and oxidation ratio of LDL show significantly higher at (p<0.05) in CHD and (p<0.001) in CHD with DM patient for females in the age group (40-49) years but in the males show the results significant decrease and different significant in others groups ,beside to effect Sex and age some the studied biochemistry parameters levels and signification decrease in HDL-C and arylesterase levels as antioxidant enzymes in females and male patient selected compared with control groups.

A systematic review and meta-analysis of randomized controlled trials investigating the effects of probiotics on oxidative stress in healthy adults

The oxidative stress (OS) theory of disease stipulates that a chronic imbalance in the ratio of oxidants to antioxidants in the cellular environment leads to a variety of debilitating conditions, including type 2 diabetes, cardiovascular and liver diseases. Metabolites in the gut microbiome have been associated with increases in reactive oxygen species (ROS). Many randomized controlled trials (RCTs) have thus investigated the potential of probiotics as a nutraceutical intervention to improve parameters of OS. The objective of this paper is to review relevant human RCTs exploring the potential of probiotic supplementation to prevent OS in metabolically healthy individuals. This systematic review and meta-analysis was registered on PROSPERO (CRD42021297210). The PubMed database was searched using keywords related to probiotics and OS. In total, out of the 652 studies were screened, 9 respected the inclusion criteria. Total antioxidant capacity (TAC) (SMD: 0.83mmol/L, 95% CI: 0.25-1.40, p=0.005) and glutathione (GSH) (SMD: 0.45, 95% CI: 0.13-0.77, p=0.006) are improved with probiotic ingestion, although there are no alterations in superoxide dismutase (SOD) (SMD: 0.33, 95% CI:-0.27-0.93, p=0.28). Decreases in plasma concentrations of the OS biomarker malondialdehyde (MDA) (SMD:-0.55, 95% CI:-1.11-0.00, p=0.05) are also detected. Probiotics improve AS and OS in metabolically healthy individuals. However, more studies are needed to address the moderate to high degree of heterogeneity in methodology.

Growth of AgI semiconductors on tailored 3D porous Ti3C2 MXene/graphene oxide aerogel to develop sensitive and selective “signal-on” photoelectrochemical sensor for H2S determination

Long term exposure to hydrogen sulfide (H2S) even in low concentration poses a serious threat to human health and the ecosystem, pointing to the significance for its effective supervision. In this study, we report a sensitive and selective “signal-on” photoelectrochemical (PEC) sensor for the determination of toxic H2S in aqueous solution by in situ growth of AgI semiconductors on tailored three-dimensional (3D) porous Ti3C2 MXene/graphene oxide aerogel (MGA). Our research demonstrated that the resultant MGA with the starting feeding mass ratio of MXene and graphene oxide (GO) of 1:8 (MGA1:8) possessed the most excellent PEC performance after the growth of AgI semiconductors than their monomers (Ti3C2 MXene and GO) and the MGAs with other starting feeding mass ratio. Such designed PEC sensor based on MGA1:8/AgI heterojunction showed dramatically strengthened PEC responses with increasing concentrations of S2−. Correspondingly, a wide linear range of 5 nM–200 μM, a low limit of detection of 1.54 nM (S/N = 3), and exclusively unique selectivity have been achieved. Our research illustrates that the PEC sensor designed with tailored MGA constitutes is an effective pathway to enhance the overall sensing performance, which will envision to boost more efforts for advanced 3D porous aerogel using in PEC sensors.

Effect of Different Initial CaO/SiO2 Molar Ratios and Curing Times on the Preparation and Formation Mechanism of Calcium Silicate Hydrate.

To better understand the pozzolanic activity in fly ash used as a supplementary cementitious material in cement or concrete, calcium silicate hydrate (C-S-H) has been synthesized by adding silica fume to a supersaturated calcium hydroxide solution prepared by mixing calcium oxide and ultrapure water. Thermogravimetric analysis results have revealed the variation in the weight loss due to C-S-H in the samples and the conversion ratio of calcium oxide (the μCaO value), which represents the proportion of calcium oxide in the initial reaction mixture used to produce C-S-H, with curing time. The weight loss due to C-S-H and the μCaO value were both maximized (13.5% and 90.4%, respectively) when the initial C/S molar ratio was 1.0 and the curing time was 90 d. X-ray diffraction (XRD) analysis has indicated that C-S-H in the samples after curing for 7 d had the composition Ca1.5SiO3.5·xH2O. 29Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) analysis has revealed that the degree of polymerization of C-S-H increased with an increase in curing time for samples with an initial C/S molar ratio of 1.0. The ratio of internal to terminal tetrahedra (Q2/Q1) increased from 2.29 to 4.28 with the increase in curing time from 7 d to 90 d. At curing times ≥ 28 d, a leaf-like C-S-H structure was observed by scanning electron microscopy (SEM). An ectopic nucleation-polymerization reaction process is proposed for the formation mechanism of C-S-H.

Geochemical characteristics of the Rajmahal coals in Dhulia North Block, Eastern India: implication to their utilization and environment.

The borehole coal samples of Dhulia North Block from the Rajmahal Basin, Eastern India, were systematically analyzed based on the chemical composition and concentration of major and trace elements (including rare earth elements, REEs) to assess the distribution of REEs and their environmental implications with utilization potential. TheDhulia North Block coals are characterized by the predominant majoroxides of SiO2, Al2O3, and Fe2O3, accounting for 94% of the total ash composition, indicating the presence of quartz, clay-rich minerals, and pyrite. Compared with the average world coal ash, the total REE content in the analyzed samples ranged from 341.0 to 810.4ppm, which is substantially higher. Hot humid climate conditions with intermediate igneous source rocks of the basin were demonstrated by the major oxide ratios (Al2O3/TiO2 < 20) and plots of TiO2 with Al2O3 and Zr. The redox-sensitive elements such as V, Ni, Cr, and Co found in the Dhulia North Block coal indicate that an oxic sedimentary environment existed in the basin when coal was formed. The low sulfur content (1% in most samples) indicates freshwater conditions in the basin at the time of organic matter deposition. The outlook coefficient (Coutl) varies between0.7 and 1.6, indicating that the Dhulia North Block coals are a prospective source of REEs. The Dhulia North Block coals are characterized by low H/C and O/C atomic ratios ranging from 0.56 to 0.90 and 0.10 to 0.22, respectively, and contain type-III kerogens, indicating gas-prone source rock. Further, the basic-to-acid oxide ratio suggested that Dhulia North Block coals were suitable for utilization during combustion processes.

Coupled cavitation and AOPs treatment of Primene-JMT containing wastewater

The application of various cavitational reactors as the novel approach to remove the emerging contaminant, Primene-JMT (PJMT), in an aqueous solution has been elucidated in this work. Ultrasonic step horn (US step horn), longitudinal horn based ultrasound (LHUS), hydrodynamic cavitation (HC) with single slit venturi (HCSV), and dual slit venturi (HCDV) are the specific reactors studied individually and in combination with Advanced Oxidation Processes (AOPs) involving H2O2, Fenton, O3, and NaClO. Different operating parameters such as oxidant loadings, oxidant ratios, treatment time, and the inlet pressure have been varied to elucidate the optimum conditions. The optimal conditions established in the study are H2O2 dosing of 0.8 g/L, H2O2/Fe2+ ratio of 4/1, O3 flow rate of 3LPH, and NaClO dosing of 0.8 g/L as applicable for the specific process. The US+NaClO and US+Fenton+CaO schemes were shown to be most effective at laboratory scale in achieving a maximum COD reduction of 98 % each at pH of 9 after 120 min and 130 min, respectively. Under the optimum conditions, LHUS+NaClO and HCDV+NaClO schemes were also successfully applied on pilot scale, showing the maximum COD reductions of 90 % and 96 % and cavitational yield of 0.89×10−3mg/J and 26.34×10−3mg/J, respectively. Comparison of different cavitating devices revealed that a dual slit venturi was nearly 30 % more efficient than a single slit venturi under similar conditions. It was clearly demonstrated that a combination strategy under optimum conditions was advantageous for attaining the highest COD reduction and cavitational yield at the lower operational cost.

Measurements of Hydroxyl Radical Concentrations during Indoor Cooking Events: Evidence of an Unmeasured Photolytic Source of Radicals.

The hydroxyl radical (OH) is the dominant oxidant in the outdoor environment, controlling the lifetimes of volatile organic compounds (VOCs) and contributing to the growth of secondary organic aerosols. Despite its importance outdoors, there have been relatively few measurements of the OH radical in indoor environments. During the House Observations of Microbial and Environmental Chemistry (HOMEChem) campaign, elevated concentrations of OH were observed near a window during cooking events, in addition to elevated mixing ratios of nitrous acid (HONO), VOCs, and nitrogen oxides (NOX). Particularly high concentrations were measured during the preparation of a traditional American Thanksgiving dinner, which required the use of a gas stove and oven almost continually for 6 h. A zero-dimensional chemical model underpredicted the measured OH concentrations even during periods when direct sunlight illuminated the area near the window, which increases the rate of OH production by photolysis of HONO. Interferences with measurements of nitrogen dioxide (NO2) and ozone (O3) suggest that unmeasured photolytic VOCs were emitted during cooking events. The addition of a VOC that photolyzes to produce peroxy radicals (RO2), similar to pyruvic acid, into the model results in better agreement with the OH measurements. These results highlight our incomplete understanding of the nature of oxidation in indoor environments.

Characteristics of PM2.5 and secondary inorganic pollution formation during the heating season of 2021 in Beijing

Water-soluble inorganic ions (WSIIs) were measured online in Beijing during the heating season of 2021, during which Beijing 2022 Olympic and Paralympic Winter Games were hosted. The characteristics of PM2.5 and water-soluble inorganic ions were investigated in general, as well as during the clean period, polluted period, and Olympic and Paralympic Winter Games periods. It was found that most of the polluted episodes occurred under conditions of low wind speed, temperature inversion, and high relative humidity. The total mass concentration of water-soluble inorganic ions during the polluted period and the clean period accounted for 38.2% and 61.4% of the PM2.5 mass concentration, respectively. Both the sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) showed a strong relationship with relative humidity. During the polluted period, the concentrations of secondary aerosols such as sulfate, nitrate, and ammonium (SNA) increased significantly. Secondary transformation was enhanced compared with that in the clean period. A polluted process after a snowfall event was selected to explore the mechanism of sulfate and nitrate formation under high relative humidity. The results would be beneficial to understanding the causes of pollution and helping the government to formulate effective measures to control air pollution in winter.