Architecting Ni3Se4-NiSe2-Co3O4 Triple-Interface Heterostructure on MXene Nanosheets for Boosting Water Splitting by Electronic Modulation and Interface Effects.

Strategically engineering electrocatalysts with optimized interfacial electronic architectures and accelerated reaction dynamics is pivotal for augmenting hydrogen generation via alkaline water electrolysis on an industrial scale. Herein, a novel triple-interface heterostructure Ni3Se4-NiSe2-Co3O4 nanoarrays are designed anchored on Ti3C2Tx MXene (Ni3Se4-NiSe2-Co3O4/MXene) with significant work function difference (ΔΦ) as bifunctional electrocatalysts for water electrolysis. Theoretical calculations combined with experiments uncover the pivotal role of the interface-induced electric field in steering charge redistribution, which in turn modulates the adsorption and desorption kinetics of reaction intermediates. Furthermore, the synergistic interaction between Ni3Se4-NiSe2-Co3O4 and Ti3C2Tx MXene nanosheets endows the hybrids with a large electrochemical surface area, abundantly active sites, and high conductivity. Thus, Ni3Se4-NiSe2-Co3O4/MXene manifests exceptional catalytic prowess for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In addition, the Ni3Se4-NiSe2-Co3O4/MXene electrocatalyst in the water electrolyzer delivers excellent performance and maintains commendable stability beyond 100 h of electrocatalytic operation.

Microneedles loaded with glutathione-scavenging composites for nitric oxide enhanced photodynamic therapy of melanoma.

Photodynamic therapy (PDT) represents an attractive promising route for melanoma treatment. However, its therapeutic efficacy is compromised by inefficient drug delivery and high glutathione (GSH) levels in cancer cells. To overcome these challenges, microneedles (MNs) system loaded with GSH-scavenging nanocomposites was presented for nitric oxide (NO) enhanced PDT. The nanocomposites consisted of S-nitroso-N-acrylate penicillamine (SNAP; a NO donor) grafted fourth-generation polyamide amine dendrimer (G4) and chlorin e6 (Ce6). Upon local insertion of polyvinylpyrrolidone MNs, G4-SNAP/Ce6 composites were fast delivered and significantly amplified the therapeutic effects during PDT, via GSH depletion and reactive nitrogen species generation. Even with a single administration and low power light exposure, MNs with G4-SNAP/Ce6 effectively halt the tumor progression. The system demonstrated better cancer ablation efficacy than Ce6 alone toward melanoma. The strategy may inspire new ideas for future PDT-related therapy for skin tumors.

Enhanced Transcutaneous Chemodynamic Therapy for Melanoma Treatment through Cascaded Fenton-like Reactions and Nitric Oxide Delivery.

Chemodynamic therapy (CDT) has emerged as a promising strategy for cancer treatment. However, its effectiveness has been hindered by insufficient hydrogen peroxide (H2O2) and high reductive glutathione (GSH) within tumors, which are the two main reasons for the inefficiency of Fenton/Fenton-like reaction-based CDT. Herein, we present a H2O2 boost-GSH depletion strategy for enhanced CDT to fight against melanoma through a microneedle (MN)-based transcutaneous delivery method. The MN system is composed of dissolvable polyvinylpyrrolidone integrated with stimuli-responsive prodrugs. Under an intracellular acidic environment, the smart release of H2O2 boosting components is triggered, subsequently initiating nitric oxide (NO) release and enhancing the Fenton-like reaction in a cascade manner. The generation of hydroxyl radicals (•OH), along with the depletion of GSH by NO, amplifies the oxidative stress within tumor cells, promoting apoptosis and ferroptosis. The antitumor efficacy of the MN patch is validated in an A375 mouse melanoma model. This "H2O2 boost-GSH depletion-Fenton killing" strategy expands the options for superficial tumor treatment through MN-mediated enhanced CDT.

Evaluation of fused multisource data of air temperature based on dropsonde and satellite observation.

Continuous vertical air temperature (AT) from in-situ observation is of crucial importance for understanding the atmospheric environment, but the satellite data that have complete spatial coverage lacked vertical in-situ observation data, and the vertical dropsonde data from in-situ observations only were single-point observations. Therefore, this article introduced machine learning algorithms for fusing in-situ observation and multi-satellite data to achieve spatial continuity of vertical data on a large scale. Specially, random forest (RF), support vector regression (SVR), artificial neural network (ANN) and recurrent neural network (RNN) were employed to capture the non-linear relationships between the variables and estimated AT. The pre-training process and fine-tuning process ensured the prediction of AT spatiotemporal distribution. The four models were implemented for three-dimensional AT estimating across China. Additionally, we used the radiosonde observation data to evaluate the accuracy of estimated AT data under conventional weather and typhoon conditions. Our results revealed that the RF model performed the best with the R of 0.9992, the MAE of 0.70 °C, and the RMSE of 1.04 °C at the national scale, followed by the SVR and ANN models. The RNN model exhibited promising results under typhoon conditions, which will be valuable insights for further research on the applicability of machine learning models under different weather conditions. Besides, having a larger sample size does not necessarily result in reduced errors. For instance, the MAE value for SVR in the pressure height range of 100-200 hPa was larger than that in the pressure height range of 300-400 hPa, but the former sample size was 16,324, which was 7433 higher than the latter.

Microneedle patch with "spongy coating" to co-load multiple drugs to treat multidrug-resistant melanoma.

Melanoma is the most aggressive skin malignancy that continues to increase in worldwide. The transferability and multidrug resistance lead to a high fatality rate. Synergistic administration of hydrophilic carboplatin (CBP) and hydrophobic vorinostat (SAHA) can be a reliable way to treat multidrug-resistant melanoma. However, the different physicochemical properties of multiple drugs make it difficult to achieve a convenient co-loading and an ideal synergistic treatment efficacy. To solve the problem, a microneedle patch with a porous "spongy coating" (PF-MNP) was fabricated. Firstly, (polyacrylic acid/polyethyleneimine)10 multilayers were fabricated on polymethyl methacrylate MNP. Then a "spongy coating" was achieved by acid treatment and freeze-drying. Due to the capillary effect, hydrophobic SAHA and hydrophilic CBP could be conveniently adsorbed step-by-step. The two drugs could distribute evenly on the surface, and the morphology of MNP remained good. The loading content of SAHA and CBP was easily regulated by adjusting the concentration of the adsorption solution, and MNP could quickly release most drugs within 30 min. The final in vivo experiments proved that CBP/SAHA co-loaded PF-MNP had the best therapeutic efficiency for multidrug-resistant melanoma. The MNP with a "spongy coating" showed potential to be a safe and efficient transdermal delivery platform for multiple drugs.

Dissolving microneedles with a biphasic release of antibacterial agent and growth factor to promote wound healing.

Infected wound healing is a complex and dynamic process affecting millions of people. Since wound healing contains multiple stages, it requires staged management to realize the early inhibition of infection and the subsequent promotion of wound healing. A key point is to design a biphasic release system with antibacterial agents and growth factors to promote wound regeneration. As a safe, efficient and painless transdermal drug delivery method, microneedles (MNs) have attracted widespread attention. Herein, we present dissolving MNs with the biphasic release of an antibacterial agent and a growth factor to promote wound healing. bFGF was first encapsulated in PLGA microspheres (bFGF@PLGA) and then co-loaded with free ofloxacin onto polyvinylpyrrolidone MNs. Owing to the fast dissolution of the substrate, ofloxacin was quickly released to rapidly inhibit infection, while the PLGA microspheres were left in the wound. Due to the slow degradation of PLGA, bFGF encapsulated in the PLGA microspheres was slowly released to further promote wound healing. In vivo studies demonstrated that the MNs with the biphasic release of antibacterial agent and growth factor exhibited a superior capability to promote wound healing. This biphasic release system combined with microneedles has a bright future in wound healing.

Build an implanted "arsenal": detachable microneedles for NIR-triggered cancer photothermo-chemotherapy.

The current trend in tumor research is shifting from monotherapy to multimodal therapy. However, how to achieve on-demand drug delivery and minimize the invasiveness of treatment are still big challenges. Herein, we present a detachable microneedles (MNs) system, which consists of polycaprolactone (PCL) needles and polyvinylpyrrolidone/poly (vinyl alcohol) substrate, to build an implanted drug depot for on-demand photothermo-chemotherapy. Owing to the dissolvability of the substrate, detachable MNs can intradermally implant PCL needles loaded with photothermal conversion agent Prussian blue nanocubes (PB NCs) and chemotherapeutics doxorubicin hydrochloride (Dox·HCl). Once near-infrared light irradiates, PB NCs could translate light to local regional hyperthermia, which not only ablates cancer cells but also meltPCL to accelerate the diffusion of Dox·HCl. These MNs displayed a stable and repeatable photothermal effect under NIR irradiation. The ex vivo experiments using isolated swine skin demonstrated the as needed Dox·HCl delivery triggered by NIR light. Moreover, the robust antitumor efficacy of the MN system was proved in KB tumor-bearing nude mice under three timed NIR irradiation. Therefore, the developed detachable MNs which could build implanted "arsenal" for on-demand photothermo-chemotherapy have a bright future in tumor suppression.

The influence of dusts on radiation and temperature over the eastern Asia with a regional climate model.

In order to investigate the climate effects of dusts, a regional climate model (RegCM 4.6) with the dust scheme was used to simulate the direct radiative forcing and air temperature response at 2 m near surface of dusts over the eastern Asia. Two sets of experiments were conducted, one with and one without dust aerosols. The experiment covered the main dust occurrence months from March to May for 8 years (2011-2018), and the simulation results were evaluated against ground station, reanalysis and satellite data. The model captured the spatiotemporal distribution of dust AOD and mass loading over the eastern Asia. However, it tended to underestimate the dust AOD and mass loading over the downwind of the dust source region and the Taklimakan Desert, and overestimate them over the north Xinjiang. The direct net radiative forcing including shortwave and longwave was up to -20 W·m-2 at the surface and -10 W·m-2 at the TOA over the dust source region due to the dominant negative shortwave forcing. The only exception of positive forcing at the TOA was observed along the western boundaries of the Tibetan Plateau due to the semi-persistent ice and snow cover. The dusts tended to warm the atmosphere more than 18 W·m-2 and cool the surface locally up to -0.7 °C. Among the 5 sub-areas, the largest averaged regional direct radiative forcing induced by dusts appeared over the central Inner Mongolia in May with the value of -3.0 ± 2.1, -12.2 ± 4.1 and 9.2 ± 4.4 W·m-2 at the TOA, surface and in the atmosphere, respectively. The results indicated that the model simulation for dusts should be further improved and the dust effects should be included in the estimates of climate change over the eastern Asia.

Anthropogenic emissions of atomic chlorine precursors in the Yangtze River Delta region, China.

Chlorine radical plays an important role in the formation of ozone and secondary aerosols in the troposphere. It is hence important to develop comprehensive emissions inventory of chlorine precursors in order to enhance our understanding of the role of chlorine chemistry in ozone and secondary pollution issues. Based on a bottom-up methodology, this study presents a comprehensive emission inventory for major atomic chlorine precursors in the Yangtze River Delta (YRD) region of China for the year 2017. Four primary chlorine precursors are considered in this study: hydrogen chloride (HCl), fine particulate chloride (Cl-) (Cl- in PM2.5), chlorine gas (Cl2), and hypochlorous acid (HClO) with emissions estimated for twelve source categories. The total emissions of these four species in the YRD region are estimated to be 20,424 t, 15,719 t, 1556 and 9331 t, respectively. The emissions of HCl are substantial, with major emissions from biomass burning and coal combustion, together accounting for 68% of the total HCl emissions. Fine particulate Cl- is mainly emitted from industrial processing, biomass burning and waste incineration. The emissions of Cl2 and HClO are mainly associated with usage of chlorine-containing disinfectants, for example, water treatment, wastewater treatment, and swimming pools. Emissions of each chlorine precursor are spatially allocated based on the characteristics of individual source category. This study provides important basic dataset for further studies with respect to the effects of chlorine chemistry on the formation of air pollution complex in the YRD region.

Effect of aerosols on the macro- and micro-physical properties of warm clouds in the Beijing-Tianjin-Hebei region.

The interaction between aerosols and clouds plays an important role in the climate system. There is still uncertainty about the influences of aerosols on the macro- and micro-physical properties of clouds in the Beijing-Tianjin-Hebei region. The relationships between aerosol optical depth (AOD) and the macro- and micro-physical properties of warm clouds in the Beijing-Tianjin-Hebei region were analyzed based on MODIS/Aqua data from 2007 to 2016. In addition, the ERA-Interim meteorological data was employed to investigate the relationship of AOD and cloud parameters under different meteorological conditions. The results showed that the variation of cloud droplet effective radius (CER) with AOD was in agreement with the Anti-Twomey effect, the main reason was that the increasing aerosol causes the water vapor competition effect among the cloud droplets, which makes the smaller cloud droplets evaporate. The multi-year average AOD was positively correlated with liquid water path (LWP). The relationship between AOD and cloud optical depth (COD) was quite different. When AOD was <0.4 or >0.8, COD increased with the increase of AOD, and when AOD was between 0.4 and 0.8, AOD and COD showed negative correlation. With the increment of AOD, cloud top pressure (CTP) also increased, which indicated that cloud top height decreased. When AOD was <0.3, cloud fraction (CF) was negatively correlated with AOD and conversely, positively correlated when AOD was >0.3. Furthermore, under most meteorological conditions, AOD was positively correlated with cloud macro- and micro-physical properties. Under the conditions of relative humidity ranged from 40% to 80%, there was a negative correlation between AOD and COD.

[Impact of Parameterization on the Estimation of Ammonia Emissions:A Case Study over the Yangtze River Delta].

Atmospheric ammonia plays an important role in the formation of secondary inorganic composition of PM2.5, which has attracted a high level of attention from researchers both in China and abroad. Quantifying ammonia emissions is of great scientific significance regarding research on the formation of secondary aerosol, realizing better model performance, and control of ammonia emissions. Previous studies have shown that agricultural activities are the dominant source of atmospheric ammonia, of which livestock and poultry farming contribute the most. Existing studies on estimating ammonia emissions from livestock and poultry farming activities are mostly based on emission factors and activities. However, the choice of different emission activities could lead to large differences in estimated ammonia emissions. This study makes a variety of assumptions from the selection of activity levels (volume vs. inventory) and emission coefficients (monthly vs. annual average temperature), and establishes eight scenarios from which to calculate atmospheric ammonia emissions from livestock and poultry farming in the Yangtze River Delta region in 2017. The results show that selection of different activity levels has the greatest impact on estimated ammonia emissions; estimation based on volume is higher than that based on inventory by 27.6%-34.1%. Calculation based on a more detailed monthly average temperature is higher than using average annual temperature by 3000 to 4000 tons per year. In addition, the spatial and temporal distributions of the ammonia emissions are also closely related to the choice of volume vs. inventory and the choice of monthly average temperature vs. annual average temperature. When using inventory as the emission activity, Zhoushan (Zhejiang Province) has the lowest ammonia emissions, while Huainan (Anhui Province) has the highest. In contrast, when volume is used, Lishui (Zhejiang Province) has the lowest ammonia emissions and Nanjing (Jiangsu Province) has the highest. Emissions calculations based on monthly average temperature are supposed to be more representative than those based on annual average temperature, with the highest emissions from May to September and the lowest in the winter (December, January, and February).

The accuracy improvement of clear-sky surface shortwave radiation derived from CERES SSF dataset with a simulation analysis.

Towards the Xiaotang region along the northern margin of the China's largest desert, a quantitative assessment of the precision of clear-sky satellite observations (the Single Scanner Footprint TOA/Surface Fluxes and Clouds downward surface shortwave radiation product of Clouds and the Earth's Radiant Energy System (CERES), DSSRCER) is conducted, the localized inversion mode of "absolutely clear-sky" downward surface shortwave radiation (DSSR) is established, and the "absolutely clear-sky" DSSR in Xiaotang during 2005-2018 is simulated by the Santa Barbara Discrete Atmospheric Radiative Transfer (SBDART) model. In general, under the "absolutely clear-sky" condition of Xiaotang region, there is a significant error in DSSRCER, and the simulated results of SBDART (DSSRSBD) with same input parameters as DSSRCER is better and more comparable. Single scattering albedo (SSA), asymmetry parameter (ASY) and aerosol optical depth (AOD) play crucial roles in deciding the accuracy of DSSR, and after parameter adjustment, the DSSRSBD is better than the initial, which is improved remarkably with all indexes of the fitting results greatly improved. The temporal variation of the DSSR during 2005-2018 indicates that the highest annual average value is found in 2008 (770.00 W·m-2), while the lowest appears in 2010 (600.97 W·m-2). Besides, the highest seasonal mean DSSR appears in summer, which between 860.6 and 935.07 W·m-2, while reaches the lowest in winter (403.79-587.53 W·m-2). Moreover, the monthly average DSSR changes as a curve with a single peak and is close to normal distribution, the highest appears in June (934.61 W·m-2), while the minimum with the value of 390.34 W·m-2 is found in December. All of the solar elevation angle, the characteristics of climate and aerosol particles in different seasons may contribute to the temporal variation.

[Regional Air Pollution Process in Winter over the Yangtze River Delta and Its Influence on Typical Northern Cities].

In this study, we analyzed several pollution episodes that occurred in the autumn and winter of 2018-2019 using multiple methods including the hierarchical clustering analysis, backward trajectory, and potential source contribution analysis based on monitored air quality and meteorological data. Bengbu, being a representative city to the north of the Yangtze River Delta (YRD) region and located in a heavily polluted area during these two pollution processes, is the focus of this work. The results indicated that the northern part of the YRD region is affected because of unfavorable meteorological conditions such as weak ground pressure, high humidity, low temperature, low wind speeds, and regional transport. The regional pollution processes over the YRD region in the autumn and winter seasons exhibit characteristics of wide influence and long duration with mainly two types of pollution:regional transport and intra-regional accumulation. During the two selected pollution episodes, the average PM2.5 concentration in the northern YRD region reached 131.6 µg·m-3 and 115.4 µg·m-3, respectively. The former type had a shorter duration but exhibited rapid accumulation of pollutants in a short period of time with greater pollution intensity, wider pollution range, and deeper pollution intrusion. Qualitative and quantitative analysis of the potential sources of PM2.5 based on PSCF and CWT showed that the PM2.5 concentration during EP1 was due to transport from cities such as Linyi, Xuzhou, Suqian, and Lianyungang to the pollution trajectory. The CWT value generally exceeded 80 with the highest value near 200. In contrast, EP2 was affected by the neighboring cities such as Suqian, Suzhou, and Xuzhou, and the CWT value was over 60 with the highest approaching 160, indicating that the interaction among cities in the study area is significant. This study shows that cross-regional air pollution control strategies are particularly important for alleviating the pollution situation in the northern part of the YRD region.

Effects of aerosols on the surface ozone generation via a study of the interaction of ozone and its precursors during the summer in Shanghai, China.

Previous studies have shown that heavy aerosol pollution can inhibit the surface ozone generation. More recent studies, however, have revealed that aerosol loading is positively correlated with ozone concentrations in large cities, such as Shanghai, particularly during the summer. Whether the correlation between aerosol pollution and ozone concentrations is positive or negative, it is an issue that needs to be considered by atmospheric scientists. Although the presence of ozone precursors, such as nitrogen oxide (NOx) and volatile organic compounds (VOCs), affect ozone concentrations, the roles of aerosols in the formation of ozone have rarely been investigated. Therefore, an analysis of the effect of aerosols on photochemical ozone generation via a study of the interaction of ozone and its precursors is important. In our research, we found that both aerosol and ozone concentrations were higher in Shanghai under polluted conditions than they were under clean conditions during the summer, but the ozone formation was controlled by VOCs, not by aerosol loading. The decrease in the AOD (SSA) increased (decreased) the surface UV radiation and promoted (inhibited) photochemical ozone production. We also found that the lower the concentration of photochemically active VOCs, the weaker the effect of the AOD on the ozone concentrations. The other results were shown as follows: (1) Aerosol pollution decreased the amount of UV radiation reaching the Earth's surface, but the surface UV radiation increased with increasing aerosol particle scattering; (2) Aerosol pollution inhibited the photolysis of nitrogen dioxide (NO2), while the scattering property of aerosols facilitated this phenomenon; (3) When both the concentration of ozone precursors and the SSA were constant, the ozone concentration decreased, but the attenuation rate increased significantly with an increase in AOD.

[Spatial-Temporal Distribution of Absorptive Aerosols in the Yangtze River Delta].

Based on the ozone monitoring instrument (OMI)/Aura L2 OMAERUV data from 2008 to 2017, the spatial-temporal distribution of absorptive aerosols during the past 10 years were studied. The results are as follows. ① In the temporal distribution, the inter-annual variation of absorptive aerosol optical depth (AAOD) first increased and then decreased, reaching the highest value of 0.056 in 2011; this is consistent with the aerosol optical depth (AOD) of 0.702 in the Yangtze River Delta. The inter-monthly variation shows that the high value of AAOD appeared mostly in January, March, and June and increased significantly from November to January. ② In the spatial distribution, the AAOD was higher in the north than in the south in the Yangtze River Delta, and the AOD was similar to the AAOD. High values of AAOD above 0.05 were concentrated mainly in northern Anhui and Jiangsu provinces and in Nanjing, Hangzhou, and Jinhua. The seasonal spatial distribution of AAOD and AOD was higher in spring and winter and lower in autumn, although the AOD was very high and the AAOD was low in summer. The contribution of black carbon in the Yangtze River Delta was consistent with the annual spatial distribution of the AAOD and AOD.

[Applicability of MODIS C006 Aerosol Products in a Typical Environmental Area of the Beijing-Tianjin-Hebei Region].

By fitting with the aerosol optical depth (AOD) from AERONET ground observations at sites in Beijing, Xianghe, and Xinglong with different environmental backgrounds, MODIS C051 Dark Target (DT C051), C006 Dark Target (DT C006), C006 Deep Blue (DB C006), and C006 Deep Blue/Dark Target merged AOD products were compared and evaluated to understand their applicability in the Beijing-Tianjin-Hebei region. The main conclusions are as follows:① The comparison of the C051 and C006 algorithms shows that the accuracy of the AOD at the Beijing and Xianghe sites notably improved, while an improvement was not observed at the Xinglong site; the DB C006 AOD is closest to the AERONET AOD at the Beijing site and the DT C006 AOD is closest to the AERONET AOD at the Xianghe site; the combined C006 AOD is closest to the AERONET AOD at the Xinglong site. ② The inversion error of the MODIS DT C006 at the Beijing site is caused by the improper selection of the aerosol model and surface reflectance; the inversion error of the MODIS DB C006 is mainly due to surface reflectance in spring and the aerosol model in winter. ③ Compared with the DT C051 AOD, the effective data coverage of the DT C006 is reduced, but that of DB C006 and the combined C006 increased; the combined C006 AOD data have the largest coverage. The results show that the application of the combined AOD product is best for the Beijing-Tianjin-Hebei region.

[Analysis of Aerosol Optical Depth Variation Characteristics for 10 years in Urumqi Based on MODIS_C006].

Based on the MYD04_L2_C006 dataset gained from Moderate resolution imaging spectroradiometer MODIS Level 2 at 10 km resolution of NASA's EOS (Earth Observing System) from 2006 to 2015, the aerosol optical depths (AODs) for 10 years under the condition of mild above atmospheric pollution (including mild) were analyzed for Urumqi City. The results showed that the average AODs in Urumqi were unimodally distribution over the 10 years. From January to April, the AODs gradually increased. During a year, the annual peak of 0.37±0.19 was in April, and the lowest value of 0.22±0.20 was in October. Owing to the frequent occurrence of dust weather conditions in spring, the largest seasonal variation of AOD was in spring, as the air pollution in the entire area was very serious, followed by summer and winter, with the smallest in autumn. In addition, the urban area was the high AOD value area in Urumqi, as its air pollution was more severe than that in the suburbs. The average value of AOD during the 10 years was 0.293. The highest value of AOD was 0.33 in 2006, and the lowest value of 0.24 was in 2008, which declined to 23.3% of that in 2007. The annual change in AOD in Urumqi over the 10 years rose steadily. Compared with previous studies, the lowest and highest values were both higher to different degrees. Despite the deduction trend in 2015, air pollution in Urumqi was serious in the studied decade, and thus control of such needs to be strengthened.

[Chemical Composition Characteristics of PM2.5 Emitted by Medium and Small Capacity Coal-fired Boilers in the Yangtze River Delta Region].

Seven small and medium coal-fired boilers were selected to analyze the emission factors and chemical composition characteristics of PM2.5, and the efficiency of the dust collection unit in removing PM2.5, OC, and EC of different particle sizes. At the outlet of the dust collection unit, PM2.5 mass emission factor was around 0.047-0.283 g·kg-1 with an average of (0.146±0.081) g·kg-1. SO42- was the most abundant ionic component, followed by NH4+ and Ca2+. S was the most abundant among all the elements, followed by Al, Ca, and Fe. The contents of OC and EC fluctuated greatly, and the ratio of OC and EC produced by each boiler was greater than one. In the range of the measured particle sizes, the mass concentration of PM2.5 showed a singlet or bimodal distribution, and the peak value appeared at 0.07-0.12 µm and greater than 1 µm in bimodal distribution. The mass concentration of OC showed a bimodal or trimodal distribution, and the peak value appeared at 0.04 µm, 0.20-0.31 µm, and greater than 1 µm in trimodal distribution. The efficiencies of the dust collection unit in removing PM2.5, OC, and EC were 66%, 53%, and 23%, respectively.

Simulations of the impacts of building height layout on air quality in natural-ventilated rooms around street canyons.

Numerical simulations were conducted to investigate the effects of building height ratio (i.e., HR, the height ratio of the upstream building to the downstream building) on the air quality in buildings beside street canyons, and both regular and staggered canyons were considered for the simulations. The results show that the building height ratio affects not only the ventilation fluxes of the rooms in the downstream building but also the pollutant concentrations around the building. The parameter, outdoor effective source intensity of a room, is then proposed to calculate the amount of vehicular pollutants that enters into building rooms. Smaller value of this parameter indicates less pollutant enters the room. The numerical results reveal that HRs from 2/7 to 7/2 are the favorable height ratios for the regular canyons, as they obtain smaller values than the other cases. While HR values of 5/7, 7/7, and 7/5 are appropriate for staggered canyons. In addition, in terms of improving indoor air quality by natural ventilation, the staggered canyons with favorable HR are better than those of the regular canyons.

[Correlations of Light-duty Gasoline Vehicle Emissions Based on VMAS and CVS Measurement Systems].

Gaseous emissions from 25 State 2-5 light-duty gasoline vehicles were tested by Vehicle Mass Analysis System (VMAS) and CVS (Constant Volume Sampling) system, respectively. The correlations of emission factors of tested vehicles measured by these 2 methods were analyzed. The results showed that emission factors of light-duty gasoline vehicle had a decreasing trend with the promotion of emission standard. There were some high-emitting vehicles in the fleet of tested State 2 and State 3 vehicles, but fewer in State 4 or Stated 5 vehicle fleet. The correlations of the emission factors measured by the 2 methods deteriorated with the promotion of emission standard. The relative bias of CO and HC+NOx emission factors measured by the 2 methods reached 197% and 177%, respectively. The correlation coefficient of emission factors of higher-emitting vehicles was 0.75-0.85, while that of lower-emitting vehicles was only 0.46. If tighter emission standard of in-use light-duty gasoline vehicle was adopted, the false positive rate of measurement results by VMAS would rise significantly. In summary, VMAS method is hard to be applied in the emission measurements of light-duty gasoline vehicles with stricter emissions standard. It is necessary to conduct more studies on sophisticated in-use vehicle measurement system.