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Contralateral subdural effusion (CSE) after decompressive craniectomy (CSEDC) is occasionally observed. Cranioplasty is routinely performed for reconstruction and has recently been associated with improving contralateral subdural effusion. We sought to systematically review all available literature and evaluate the effectiveness of cranioplasty for CSE.A PubMed, Web of Science, and Google Scholar search was conducted for preferred reporting items following the guidelines of systematic review and meta-analysis, including studies reporting patients who underwent cranioplasty because of CSEDC.The search yielded 8 articles. A total of 56 patients ranging in age from 21 to 71 years developed CSEDC. Of them, 32 patients underwent cranioplasty. Eighteen cases with symptomatic CSE underwent cranioplasty alone, 2 cases received Ommaya drainage later because of a recurrence of CDC, and 1 case underwent a ventriculoperitoneal shunt because the CSE did not resolve completely and the ventricle was dilated again. The symptoms of 14 cases lessened without recurrence after simultaneous cranioplasty and drainage or a shunt. The total success rate (CSE disappeared without recurrence) was 90.6% for patients who underwent cranioplasty; however, the total incidence of hydrocephalus was 40.1%.This review suggests that cranioplasty is effective for the treatment of CSEDC, particularly intractable cases, but early cranioplasty may be more effective. In addition, hydrocephalus is fairly common after cranioplasty and requires further treatment.

Neuroimaging studies have shown that spinal cord injury (SCI) may lead to significant brain changes that are the key factors affecting functional recovery. However, little is known about the molecular and cellular biological mechanisms of these brain changes. The aim of this study was to investigate the molecular and cellular biological changes in the cerebellum after SCI.A total of 72 mice were randomly divided into 2 groups: sham group and SCI group. A mouse model of SCI was established by an aneurysm clip. Pathological examinations of the injured site were performed by hematoxylin and eosin staining and immunohistochemical. Western blot and immunohistochemical were used to determine the effect of SCI on the differentiation and maturation of NG2 cells.Compared with the sham group, the spinal cord tissue structure was disrupted and the motor function decreased significantly in the SCI group; the number of NG2 cells in the ansiform lobule crus Ⅰ increased on the 7th and 14th days, whereas the expression of oligodendrocyte transcription factor 2, myelin basic protein, and proteolipid protein decreased on the 7th and 14th days after SCI. These results showed that the differentiation and maturation of NG2 cells in the ansiform lobule crus Ⅰ were inhibited after SCI, resulting in the decrease of the formation of mature oligodendrocytes.These results indicate that SCI can lead to secondary changes in the cerebellum, which may affect the functional recovery. These findings may be used as biomarkers to evaluate the secondary changes in the brain after SCI.

Neuroinflammation is an important secondary aggravating factor in spinal cord injury (SCI). Inhibition of the inflammatory response is critical for SCI treatment. Glycyrrhizic acid (GA) is an anti-inflammatory drug, but its utility for SCI is unclear. This study aimed to evaluate the effects of GA on inflammation after SCI and the underlying mechanism.Cell counting kit-8 assays were performed to assess the viability of highly aggressively proliferating immortalized cells that had been treated with lipopolysaccharide (LPS) and/or GA. Reverse transcription quantitative polymerase chain reaction and Western blotting were performed to assess expression of high mobility group box-1 protein (HMGB1), ionized calcium binding adaptor molecule 1, and inflammatory factors in vitro and in vivo. GA (100 mg/kg) was intraperitoneally injected into rats. Anti-inflammatory effects of GA were analyzed in SCI tissues. p38/Jun N-terminal kinase signaling pathway proteins were analyzed by Western blotting.Cell counting kit-8 assay results showed that treatment with 100 ng/mL LPS for 12 hours was optimal. After LPS treatment, highly aggressively proliferating immortalized cells were activated; messenger RNA expression levels of HMGB1 and inflammatory factors were increased. GA significantly inhibited LPS-induced HMGB1 expression and inflammatory responses, as determined by reverse transcription quantitative polymerase chain reaction and Western blotting. Transfection with an HMGB1-overexpression plasmid reversed the anti-inflammatory effects of GA. In addition, intraperitoneal injection of GA (100 mg/kg) into rats for 3 days significantly reduced expression levels of HMGB1 and inflammatory factors after SCI in vivo. GA reduced phosphorylation, but not levels, of p38 and Jun N-terminal kinase proteins.GA attenuates the inflammatory response after SCI by inhibiting HMGB1 through the p38/JNK signaling pathway and thus has therapeutic potential for SCI.

At present, the types of pollutants in wastewater are more and more complicated, however, the multifunctional membrane materials are in short supply. To prepare a membrane with both high efficient oil-in-water emulsion separation performance and photocatalytic degradation performance of organic dyes, the bifunctional separation membrane was successfully prepared by electrostatic spinning technology of PVDF/PEMA and in situ deposition of anatase TiO2 nanoparticles containing Ti3+ and oxygen vacancies (Ov). The prepared composite membrane has excellent hydrophilic properties (WCA = 15.65), underwater oleophobic properties (UOCA = 156.69), and photocatalytic performance. These composite membranes have high separation efficiency and outstanding anti-fouling performance, the oil removal efficiency reaches 98.95%, and the flux recovery rate (FRR) reaches 99.19% for soybean oil-in-water emulsion. In addition, the composite membrane has outstanding photocatalytic degradation performance, with 97% and 90.2% degradation of RhB and AG-25 under UV conditions, respectively. Several oil-in-water separation and dye degradation experiments show that the PVDF composite membrane has excellent reuse performance. Based on these results, this study opens new avenues for the preparation of multifunctional reusable membranes for the water treatment field.

In order to enhance the hydrophilicity and anti-fouling property of polytetrafluoroethylene (PTFE) flat microfiltration membrane, the PTFE flat membrane was modified via cross-linking O-carboxymethyl chitosan (OCMCS) and polyethyleneimine (PEI) with glutaraldehyde (GA). Membrane performance was characterized by Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-ray Photoelectron Spectroscopy (XPS), Field Emission Scanning Electron Microscope (FESEM), water contact angle and pure water flux. Results from ATR-FTIR and XPS showed that PEI and OCMCS were introduced into the modified PTFE membranes successfully. The modified PTFE membrane was endowed with excellent hydrophilicity compared with the original membrane by the result of increased pure water flux. Bovine serum albumin (BSA) static adsorption test and dynamic cross-flow fouling experiment results showed that the modified membrane has good anti-fouling ability. The pure water flux and the contact angle of the modified membranes changed with a variation in the time, GA concentration, OCMCS concentration, and OCMCS:PEI (mass ratio). It seemed that the optimal time, the concentration of OCMCS, the mass ratio of OCMCS and PEI, and the concentration of GA were 12 h, 5 g/L, 4:1 and 5 g/L, respectively.

The Planetary boundary layer (PBL) plays an important role in energy exchange and pollutant dispersion. The height of the PBL (PBLH) usually exhibits distinct diurnal variation. In this study, we investigate the characteristics of PBLH variation of Beijing China based on 1-year observations from Micropulse LIDAR (MPL) data, and compared against the PBLH simulated by the Weather Research and Forecast (WRF) model using eight different schemes. The variation of daytime MPL PBLH has been classified into four representative types using k-means clustering technique. Through comparison against MPL, it is shown that the Mellor-Yamada Nakanishi and Niino Level 3 (MYNN3) scheme, a second-order closure scheme, performs the best in representing the PBLH variation in most of the cases. The non-local schemes also show advantages in convective situations, due to the stronger vertical mixing embedded in these schemes. Further analyses show that differences in PBLH definition is a major factor causing the divergence among different schemes, while the biases of the profiles play a minor role.

Photochemical regime for ozone (O

To improve hydrophility and antifouling property of Polytetrafluoroethylene flat microfiltration membrane, a novel and facile method was developed to modify the membrane via the polymer of Laccase-catalyzed self-polymerization of Gallic acid and cross-linked with Polyethylenimine, then the surface micro/nanostructures was treated by (2,3-epoxypropoxy)-propytrimethoxysilane. The surface chemical composition, surface morphology, hydrophilicity and antifouling property of the PTFE flat membrane were investigated by ATR-FTIR, XPS, FESEM, water contact angle, pure water flux measurements, respectively. After using this low-cost and simple modification method, PTFE flat membranes were endowed with excellent hydrophilicity, high pure water flux and antifouling property. Besides, the modified PTFE flat membrane could be applied to the separation of oil-in-water emulsion with an ultrahigh efficiency 98.2% and also shows durable oil resistance and antifouling performance, making the membrane easy to reuse. Finally, the surface stability of the modified membrane was studied and the mineralized membrane showed excellent acid resistant ability. Therefore, this facile strategy holds attractive potential practical application in water environmental remediation.

High performance concrete (HPC) has been applied in practical engineering for a wide range owing to its superior performances, including low permeability, high strength, high modulus, and other superior performance. However, with the high internal temperature and self-desiccation that induced by the low water-to-binder (w/b) ratio, HPC suffers high autogenous shrinkage, which leads to the premature cracking of HPC after peak stress at early age. For the purpose of increasing the cracking resistance of concrete effectively, Barchip fibers and the internal curing materials are used to improve the early-age properties of concrete. Although researches on the cracking resistance of HPC reinforced with different contents of Barchip fiber or internally cured with different kinds of internal curing materials have been conducted, studies on the effect of Barchip fiber length on the cracking resistance of internally cured HPC (ICHPC) with super absorbent polymers (SAPs) at early age are rather lacking. In present research, the effect of length of Barchip fibers (0, 42, 54, and 60 mm) on the early-age cracking resistance of ICHPC under the adiabatic condition was studied by Temperature Stress Test Machine. Results of the experimental research and related analysis indicated that (1) the splitting tensile strength and compressive strength of HPC increased as the Barchip fibers were applied; (2) the use of SAPs reduced autogenous shrinkage, restrained tensile stress rate, and tensile creep behavior, and increased temperature drop and the cracking resistance of HPC at early age; (3) the autogenous shrinkage decreased and the temperature drop, cracking age, cracking stress of ICHPC increased as the Barchip fiber length increased; (4) the tensile creep behavior of ICHPC increased as the Barchip fibers were applied, and decreased as the Barchip fiber length increased; (5) the cracking resistance of ICHPC increased first and then decreased as the Barchip fiber length increased, as obtained from the integrated criterion; (6) the poor dispersion of Barchip fibers may result in the decrease of the early age behavior and cracking resistance of ICHPC when the fiber length exceeded 54 mm.

To improve antifouling and antibacterial property of Polytetrafluoroethylene (PTFE) flat microfiltration (MF) membrane, a novel and facile method was developed to modify the membrane via the polymer of Laccase-catalyzed self-polymerization of Gallic acid (GAL) and cross-linked to Chitosan (CS) using Citric acid (CA) as a cross-linker, and then surface micro/nanostructures treated by 3-Triethoxysilylpropylamine (KH550). The surface chemical composition, surface morphology, hydrophilicity, antifouling and antibacterial property of the PTFE flat membrane were investigated by ATR-FTIR, XPS, FESEM, water contact angle (WCA), bovine serum albumin (BSA) filtration and antibacterial measurements, respectively. After using this low-cost and simple modification method, the PTFE flat membranes were endowed with excellent hydrophilicity, antifouling and antibacterial properties. Finally, the surface stability of the modified membranes were studied and the modified membrane showed excellent stability under pH = 3–12.

A reference height that often needs to be assumed in aerosol retrieval from Raman lidar tends to cause high uncertainty in retrieving the vertical distribution of aerosol optical properties. Here, a novel method is proposed to determine the height-revolved reference height, which is then used to retrieve aerosols from Raman lidar. This method can automatically avoid the atmospheric layers with the presence of aerosols, clouds and low signal to noise ratio (SNR). Based on elastic (at 355 nm) and inelastic (at 387 nm) signals collected during the period from 5 December 2016 to 5 March 2017 by a ground-based Raman lidar in Beijing, China, the aerosol optical properties, such as extinction coefficient, backscattering coefficient and lidar ratio have been successfully retrieved. Results show that the averaged nighttime aerosol optic depth (AOD) from Raman lidar is in good agreement with early morning AOD retrieved from a collocated sunphotometer. The AOD exhibits a strong diurnal variation with a peak at 1500 Beijing time. On average, the nighttime AOD at 355 nm is 0.32, whereas the daytime AOD is 0.72 over Beijing during the study period. The column averaged lidar ratio is 44 sr at 355 nm, roughly consistent with previous studies. Our findings shed light on the pathways towards improving the retrieval of vertical distribution of aerosols optical properties during nighttime.

Frequent occurrence of severe haze in Beijing indicates the importance of effective decisions and clear goals to reduce the concentration of particulate matter in the atmosphere. To achieve this goal, elucidation of the elements governing fine particulate matter concentrations should be considered as one of the priorities. In this paper, we proposed a statistical model based on physical understanding of the diffusion of air pollutants by wind to investigate the sensitivity of fine particulate matter and its precursor gases concentrations to wind speed and direction. By using our method, it is possible to determine the major wind directions that have large impact on air quality for a particular area. Our results showed that the influence of wind on the concentration of particulate matter and its precursor gases varies spatially over Beijing. Our method suggested that both local emission sources of fine particulate matter and its precursor gas (NO2) and transported SO2 from regional industries should be reduced for the remediation of severe air pollution scenarios, especially in the Beijing urban area. Our approach serves as a good complement for commonly used approaches for source apportionment analysis without exploiting complicated methods. The method shows its feasibility in identifying air pollutant emission sources based on wind patterns and can be used in other regions as an aid in air pollution controlling programs.

In this paper, the ZIF-8/ZnO mixture was sintered at high temperature to prepare C-ZnO composite nano-particles with excellent photocatalytic degradation ability under ultraviolet light, and then blended with PVDF to fabricate PVDF composite membrane with capabilities of photocatalytic degradation of methylene blue(MB) via solution phase conversion. The results show that the photocatalytic performance of the prepared C-ZnO composite particles was the best when the ZIF-8/ZnO mass ratio was 1:2, and the photocatalytic degradation efficiency of the PVDF composite film prepared was as high as 95.02% when the composite particle content was 15%. The photocatalytic activity of C-ZnO composite material benefits from the synergy between the two. Moreover, the efficiency of photodegradation of MB remained above 90% after the composite membrane was subjected to five cycles of experiments, which solved the problem that the traditional photocatalyst was difficult to recycle. In addition, it is found that O2- plays a major role in the photocatalytic degradation of MB through free radical capture experiments. All in all, the PVDF composite membrane containing C-ZnO composite particles has a foreseeable potential in the field of photocatalytic printing and dyeing wastewater in the future.

The Yangtze River Delta region is the most active of China's economic regions; however, industrialization and urbanization have seriously affected air quality in the region and air pollution is becoming increasingly serious. Based on the NCEP/NCAR FNL reanalysis data of sea level pressure (SLP) from 2013 to 2015, an objective quantitative method of synoptic circulation classification, T-mode principal component analysis (PCA), was used to analyze the influence of synoptic circulation pattern on air quality in East China. Circulation was divided into nine types: (1) Northwest High Pressure (NWH); (2) Front of Low Pressure (FL); (3) North High Pressure (NH); (4) Northeast High Pressure (NEH); (5) South Low pressure (SL); (6) Weak pressure (Unique); (7) Southwest Low Pressure (SWL); (8) Northeast Low Pressure (NEL); and (9) Low Pressure (L). The air quality in the Nanjing area is discussed in this paper, as well as the relationship between synoptic circulation patterns and local meteorological conditions. The results show that there is a close relationship between synoptic circulation patterns and local meteorological conditions that greatly affects the air quality of the Nanjing area. By the quantitative analysis of the concentrations of five air pollutants (PM2.5, CO, NO2, SO2 and O3) under different synoptic circulation types, it was found that circulation type 1 (CT 1, NWH), circulation type 3 (CT 3, NH) and circulation type 4 (CT 4, NEH) were associated with poor air quality; the mean PM2.5 concentrations during 2013, 2014 and 2015 were 83.8 μgm-3, 77.6 μgm-3 and 78.4 μgm-3, respectively. The local meteorological conditions corresponding to the three circulation types were low temperature and low wind speed. In contrast, circulation type 2 (CT 2, FL) and circulation type 8 (CT 8, NEL), which were associated with better air quality, had opposite local meteorological conditions; the mean PM2.5 concentrations were 53.2 μgm-3 and 57.7 μgm-3, respectively. This case study shows that the Nanjing region was mainly controlled by CT 1 and CT 3 during the major pollution event in January 2015. The regional transport paths associated with specific circulation types were identified by trajectory analysis in the haze episodes. It was found that two rainfall events played a positive role in improving air quality in the Nanjing area.

With the explosive economic development of China over the past few decades, air pollution has become a serious environmental problem and has attracted increasing global concern. Using satellite-based PM2.5 data from 2000 to 2015, we found that the temporal-spatial variation of PM2.5 in East China is characterized by high concentrations in the northern part and low concentrations in the southern part of East China, and by being seasonally high in autumn and winter but low in spring and summer. We also found that the regional average PM2.5 concentration shows an approximative peak pattern over the last 16 years, with the highest, 60.13 μg m− 3, and the lowest, 46.18 μg m− 3, occurring in 2007 and 2000, respectively. Despite obviously diminishing heavy polluted regions with a PM2.5 of > 80 μg m− 3 after 2011, those cells dominated by natural background have still not recovered back to the clean level of 2000. These characteristics are valuable information to analyze the relative contributions of anthropogenic emissions and atmospheric conditions to the temporal-spatial variation characteristics of PM2.5.

Aerosol liquid water content (ALWC) has significant effects on aerosol optical properties, radiative forcing, and the development of severe pollution events. In this study, the vertical distribution and temporal evolution of ALWC were determined through linear particle depolarization measured by a high spectral resolution lidar (HSRL) from December 9 to 12, 2020. Near-surface ALWC datasets retrieved by HSRL were validated by measurements from a three-wavelength humidified nephelometer. The ALWC datasets derived by two methods were highly correlated (R = 0.94, N = 192), illustrating the feasibility of retrieving the ALWC by HSRL. A positive correlation between the ALWC and the enhancement of aerosol scattering coefficient F calculated by the scattering coefficient at 525 nm measured in dry and ambient states proves the reliability of the ALWC obtained from HSRL. However, previous research has implied that fine mode particles dominating the total aerosol loading are required to precisely retrieve the ALWC, while the uncertainty of ALWC data will be large when the particle depolarization ratio is larger than 0.07. When it is less than 0.07, the ALWC derived from HSRL has high precision. By analyzing the aerosol property measurements (e.g., PM2.5, PM10, particle depolarization ratio, and scattering coefficient) near the surface, we found that ALWC contributes greatly to the deterioration of visibility. The variability of optical parameters in the vertical direction showed that ALWC significantly promotes the enhancement of aerosol extinction coefficients. Moreover, high ALWC significantly increases the scattering capacity of aerosols, leading to an enhanced cooling effect on the climate system.

The annual mean PM2.5 mass concentration has decreased because of the stringent emission controls implemented in Beijing, China in recent years, whereas the nitrate NO 3 – mass fraction in PM2.5 increases gradually. Low-visibility events occur frequently even though PM2.5 pollution has been mitigated significantly, with the daily mean PM2.5 mass concentration mostly less than 75 μg/m3. In this study, the non-linear relationship was analyzed between atmospheric visibility and PM2.5 based on chemical composition from a two-year field observation. Our results showed that NO 3 – became the main constituent of PM2.5, especially during the haze pollution episodes. A localized parameterization scheme was proposed between the atmospheric extinction coefficient ( σ ext ) and major chemical constituents of PM2.5 by multiple linear regression (MLR). The contribution of NO 3 – to σ ext increased with increasing air pollution, and NO 3 – became the most important contributor for PM2.5 above 75 μg/m3. The visibility decreased with increasing NO 3 – mass fraction for the same PM2.5 mass concentration when PM2.5 was above 20 μg/m3. The hygroscopicity of PM2.5 increased with increasing mass fraction of hygroscopic NO 3 – . These results stressed the importance of reducing particulate NO 3 – and its precursors (for instance, NH3) through effective emission control measures as well as the tightening of PM2.5 standards to further improve air quality and visibility in Beijing.

Reinforcement corrosion is one of the main reasons for the deterioration of reinforced concrete (RC) structure. Corroded RC beam-column joint experiences large deformations under the earthquake, which results in the deterioration of the seismic behavior. Although researches on the uncorroded joints strengthened with fiber-reinforced polymer (FRP) sheets have been conducted, investigations on the corroded RC beam-column joints repaired with basalt FRP (BFRP) sheets are relatively limited. In present research, seven interior beam-column joints were tested under the cyclic loading, including one reference specimen, three specimens with different corrosion rates, and three corroded specimens repaired with BFRP sheets. The seismic behaviors in terms of crack pattern, failure mode, hysteretic curve, load bearing capacity, deformation capacity, energy dissipation, and stiffness degradation were discussed. Results obtained from the test showed that: (1) the seismic behaviors of corroded beam-column joints were effectively improved by the utilization of BFRP sheets; (2) the spalling, and crushing of concrete, as well as the buckling of stirrups were delayed by the utilization of BFRP sheets; (3) the load bearing capacity, ultimate displacement, and energy dissipation capacity of corroded beam-column joints were effectively increased, and the stiffness was fully recovered to that of uncorroded joint by repairing with BFRP sheets; (4) the bond behavior between corroded bars and concrete or strains of corroded bars in beam-column joints were improved or decreased after repairing with BFRP sheets.

Due to the limited spatial coverage of surface PM 2.5 monitoring sites, satellite AOD (aerosol optical depth) products have been widely used to estimate surface PM 2.5 in different parts of the world. A major difficulty as well as source of uncertainty in converting AOD to PM 2.5 is the determination of aerosol vertical distribution, usually represented by the boundary layer height (BLH). In this study, we evaluate the performance of different approaches of estimating aerosol vertical distributions in the AOD-PM 2.5 conversion process, using long-term and multi-source data acquired at a super station, Yuen Long, Hong Kong. The monthly climatology of aerosol vertical distribution and BLH products derived from lidar, radiosonde, and MERRA reanalysis data are respectively applied for converting AOD to surface aerosol extinction coefficients. Seasonal empirical hygroscopic growth functions are constructed to convert aerosol extinction to dry PM 2.5 mass concentration. Results indicate that different vertical distribution estimation approaches can have highly varying effect on the converted PM 2.5 concentration. Using lidar-derived BLHs shows the best agreement, with a correlation coefficient of 0.73 and a relative bias of 30.6% between retrievals and observations. Since continuous lidar measurements are not available for most regions, the climatology pattern of aerosol structure and radiosonde-derived BLHs are found to be suitable alternatives with a correlation coefficient of ∼0.6, and considerably outperform the results using BLHs derived from reanalysis data. Elevated aerosol layers appear to be the major source of uncertainty and result in an overestimate of satellite results, especially during the spring and summer seasons.

Aerosol optical properties are important indices for monitoring atmospheric aerosol pollution. In this study, we report the seasonal and diurnal variability of major aerosol optical parameters, including scattering coefficient (σs), absorbing coefficient (σa), single scattering albedo (SSA), together with PM2.5 (particulate matter with aerodynamic diameter ≤ 2.5 μm) and PM10 (particulate matter with aerodynamic diameter ≤ 10 μm) mass concentrations measured at an urban site in Beijing from September 2017 to August 2019. The relationships between these aerosol properties with meteorological conditions, in particular, the mixing layer height (MLH), wind speed, and wind direction, are further investigated. Results show that the annual average values of PM2.5 and PM10 mass concentrations, σs, and σa during the study period are 54 ± 54 μg/m3, 100 ± 72 μg/m3, 170 ± 180 Mm−1, 17 ± 15 Mm−1 respectively, which are much lower than those previously reported, indicating the effectiveness of strict pollution control strategies implemented in recent years. SSA is calculated with σs and σa, whose annual average value is 0.88 ± 0.07. Seasonally, σa exhibits dual peaks except in summer, PM2.5 and PM10 concentrations are the highest value in the spring, whereas σs has the highest value in the summer with a secondary peak in the spring. The diurnal cycle of σa is highly anti-correlated with that of the MLH. For σs, PM2.5 and PM10, their diurnal cycles often peak around noon and are in phase with the MLH in the spring and summer, which may be associated with the photochemical production of secondary aerosols. σs, σa, PM10, and PM2.5 concentrations are inversely related to wind speed, but PM10 starts to increase as wind speed exceeds 4 m/s, possibly caused by dust and catkins. The increase in wind speed also weakens the aerosol-MLH relationship. Back trajectory analysis indicates that high aerosol concentrations are mostly associated with southward and westward airmasses.

In this research, six reinforced concrete (RC) interior beam-column joints, including one reference specimen and five specimens strengthened with basalt fiber-reinforced polymer (BFRP) sheets in different ways, were tested under the cyclic load. Results obtained from the test showed that: (1) the seismic performance of joints were significantly improved after strengthening with BFRP sheets with proposed strengthening schemes; (2) no evident debonding of BFRP sheets was observed in the test indicating that a good interface behavior between the BFRP and concrete, as well as the limited influence of the practical RC slab on the strengthening scheme could be found; (3) the load bearing capacity and ductility of joints increased by strengthening with BFRP sheets, among which larger increasing degrees of specimens strengthened with three layers of BFRP sheets could be found; (4) the stiffness of joints increased after strengthening with BFRP sheets, while the initial stiffness of specimens strengthened with BFRP sheets in the core areas exhibited larger values than those of other strengthened specimens; (5) the energy dissipation capacity of joints improved by BFRP, and more effects by increasing the layers of FRP sheets or strengthening with FRP sheets in whole lengths could be obtained.

To improve hydrophilicity and anti-fouling property of the polytetrafluoroethylene (PTFE) flat microfiltration (MF) membrane, a facile method was developed to modify the membrane via the co-deposition of catechol (CA) and polyethyleneimine (PEI) followed by surface mineralization of γ-(2,3-epoxypropoxy) propytrimethoxysilane (KH560). The surface chemical composition, surface morphology, hydrophilicity and filtration performance of the PTFE flat membrane were investigated by ATR-FTIR, XPS, FESEM, WCA and pure water flux measurements, respectively. After using this low-cost and simple modification method, the PTFE flat membrane was endowed with excellent hydrophilicity, high water permeation flux and superior anti-fouling property. Then, the oil/water separation tests were conducted using the modified PTFE flat membranes. The size distribution of the oil droplets is between 0.12–1.44 µm and the mean pore size of pristine PTFE flat MF membrane is 0.22 µm. The as-prepared hydrophilized PTFE flat membranes possess an excellent oil resistant ability with oil rejection ratio near 99%. Finally, the surface stability of the modified membrane was studied and the mineralized membrane showed excellent acid resistant ability. Therefore, this facile strategy holds attractive potential practical application in water environmental remediation.

Himawari-8 (H8), the first of the new generation geostationary meteorological satellites, carries Advanced Himawari Imager (AHI) sensor with 16 spectral bands from visible to infrared bands. As the spectral bands of AHI in reflectance bands are similar with MODIS, the Dark Target (DT) aerosol retrieval algorithm could be used for obtaining AOD over land with high temporal resolution from AHI measurements. However, the normalized difference vegetation index (NDVI) which was used as a good indicator of surface spectral reflectance is obviously affected by the solar zenith angle and cannot be ignored for AOD retrieval with geostationary measurements. Collocated AHI Level 1b observations and AERONET AOD less than 0.2 have been input into Second Simulation of the Satellite Signal in the Solar Spectrum – Vector (6SV) to calculate the surface reflectance. It can be found that the regression relationships of surface reflectance between visible and shortwave infrared channel are obviously different over different observation sites, even the NDVI is the same. In this study, AHI/H8 AOD over land was retrieved through improving the estimation of surface reflectance relationship by taking into account the land cover, NDVI and scattering angle. This approach has been applied to the AHI/H8 observations in 2018; the global AErosol RObotic NETwork (AERONET) and China Aerosol Research Network (CARSNET) ground-based AOD observations were used to evaluate the quality of AOD retrievals. The comparison results have shown that H8 AODs have good agreement with the ground-based measurements with R larger than 0.8 (N > 1500), and it is even up to 0.95 at Xianghe site. Validation with CARSNET has shown that the performance of H8 AOD is better in the morning than that in the afternoon. The AOD retrieval deviations have been found at those sites located at barren and mixed pixels. When compared with JAXA H8 AOD, it is found that the performance of AOD of this work is better than JAXA H8 AOD at most ground observation sites. More importantly, the AOD product of this work can better depicts the diurnal variation, a unique feature that the new generation geostationary satellite measurements can provide.

A kind of PVDF composite membrane of good hydrophilic performance and antibacterial property was developed via an in-situ blending process. The PVDF-g-PGAL powder was prepared by degrading PVDF powder in alkaline condition, then oxidizing and grafting with Gallic acid (GAL). After mixing the original PVDF and PVDF-g-PGAL powder to prepare the PVDF composite membrane was soaked in NaHSO3 to further improve its hydrophilicity. The oil-in-water emulsion separation efficiency of the composite membrane was regulated by varying the contents of the modified PVDF powder. When the content arrives at 30%, the composite membrane has the pore sizes in the range of 130.2–263.3 nm, the permeation flux of 2419.9L⋅m−2⋅h−1⋅bar−1, the oil rejection rate of 97.39%, the flux recovery rate (FRR) of 94.59% and possesses the good anti-fouling performances during the cross-flow separation of the oil-in-water emulsion with the particle sizes within the scope of 10.1–396.1 nm. In addition, it has excellent antibacterial properties against E. coli and S. aureus, and effectively solves the blocking of membrane pores caused by the surface colonies in application. Therefore, the new composite PVDF membrane has the broad application prospects in the practical treatment of the complex oily wastewater media.

Hydrophilic Poly (vinyl butyral) (PVB) porous heddles were prepared via blending hydrophilic PVB and green diluent Polyethylene glycol (PEG) through liquid-liquid thermally induced phase separation (TIPS) process. To further investigate the effect of the molecular weight (MW) of polymer and diluent on phase diagram of PVB-PEG blending system and performance of hydrophilic PVB porous heddle, the cloud point (Tcloud), microstructure, overall porosity and mechanical property, i.e were mainly analyzed. The results highlighted that the Tcloud of the PVB-PEG blending shifted to lower temperature with increasing PEG MW and PVB MW. Overall porosity reached up to 82.3% and tensile strength was 9.88 MPa when polymer and diluent with lowest MW. To extend the application air, the fabrication conditions of prepared porous heddle were studied. Overall porosity increased and the tensile strength decreased with extrusion temperature increasing. In addition, the PVB-PEG porous heddles proved effective hydrophilic performance and demonstrate the potential application in water treatment.

The latest version of JAXA aerosol optical depth (AOD) product over China in 2018 from Himawari-8 Advanced Himawari Imager (AHI) was evaluated, including validation with global AErosol RObotic NETwork (AERONET) and China Aerosol Research Network (CARSNET) ground-based observations, and comparison against the Moderate Resolution Imaging Spectroradiometer (MODIS) AOD product. Considering both the quality and quantity of the AHI AOD product, the Quality Assurance Flags (QA_Flags) with “good” and “very good” are chosen for evaluation and analysis. AHI and MODIS AOD products are well correlated and the spatial distributions are similar, even though underestimation from AHI AOD in the morning and overestimation in the afternoon are found when compared with MODIS AOD. Validation with ground-based observations also indicates a good correlation (R > 0.75) when sparsely vegetated surfaces are excluded. It is found that 52.74% fall below the expected error (EE) at 10:30 BJT when compared with CARSNET which has more vegetation sites and 56.91% fall above the EE at 13:30 BJT when compared with AERONET which has more urban sites. The slope of the fit line is around 1.0 for all matched sites, while the scatter plots have divided into two parts as the performance of AHI AOD depends on the observation times and surface types. The temporal variations of AHI and AERONET AODs show that the overestimation from AHI AOD occurs in the afternoon for barren surface while the underestimation occurs in the morning for well-vegetation surface. For monthly variation, the overestimation of AHI AOD is found over Northern China in winter and those seasons when the plants are growing or disappearing rapidly. The assumption that the surface reflectance remains unchanged and the solar geometries are nearly identical within a month causes the underestimation of surface reflectance and thus contributes to the AHI AOD overestimation for low vegetation and bare surfaces in autumn and winter. While over the vegetated surfaces, neglecting the background aerosols causes overestimation of the surface reflectance, and thus leads to underestimation of AHI AOD. The difference between backward and forward scattering contributes to the larger JAXA AHI AOD error in the afternoon, which aggravates positive deviation for barren land sites and alleviates the underestimation for vegetation surface types in the afternoon. In addition, aerosol model selection and cloud contamination also affect the accuracy of aerosol products, especially when AOD is large. Overall, the JAXA AHI AOD provides a high temporal resolution and relative reliable aerosol product for environmental research. The analysis on characteristics and uncertainty sources in this study are to further enhance the understanding of the geostationary satellite aerosol products for applications, and provide useful information for improving the aerosol retrieval algorithm in future.

High strength concrete (HSC) with high strength and low permeability has been widely utilized in the reinforced concrete structures recently. However, the water-to-cement ratio of HSC is low, marked self-desiccation will occur, and autogenous shrinkage is induced. The autogenous shrinkage causes tensile stress in the restrained concrete, and the tensile creep (TC) counteracts the autogenous shrinkage as a stress relaxation mechanism. Although the TC of internally cured HSC (ICHSC) with super absorbent polymers (SAPs) under fully restrained conditions has been studied, research on the early-age TC of ICHSC under constant tensile loading remains insufficient. Therefore, the effect of initial stress/strength (s/s) ratio (ranged from 20% to 35%, 50%, and 65%) on the TC behavior of ICHSC at early age was experimentally investigated by Temperature Stress Test Machine in this research. Experimental results and corresponding analysis showed that: (1) the early-age basic TC, basic TC coefficient, and specific basic TC of ICHSC at 7 days of loading was 37, 66, 95, and 148 μe, 2.26, 2.31, 2.30, and 2.76, and 52, 53, 53, and 72 μe/MPa, respectively, and increased as the initial s/s ratio increased; (2) the early-age basic TC rate of ICHSC at 1 day of loading was 0.57, 1.01, 1.70, and 3.04 μe/h and increased as the initial s/s ratio increased; (3) the nonlinear basic TC of ICHSC occurred when the initial s/s ratio ranged from 50% to 65%; (4) a prediction model for the TC of ICHSC considering initial s/s ratios was proposed based on Ostergaard model.

High strength concrete (HSC) containing silica fume (SF) is widely utilized in construction practices, and its cracking resistance attracts considerable attentions. Previous studies mostly focus on the single parameter of concrete, however, the evaluation of early-age cracking resistance of HSC containing different SF dosages considering different early-age parameters is limited. The present study investigated the effect of different SF dosages on the temperature process, autogenous shrinkage, restrained stress, and creep by utilizing Temperature Stress Test Machine to evaluate the cracking resistance of early-age HSC containing SF. Four concrete mixtures with a 0.33 water/binder ratio were prepared at different replacement levels of SF (0%, 5%, 10%, and 15% of cement by weight). The analysis and experimental results indicated that, when the SF dosage in the HSC increased, (1) the cracking resistance of HSC decreased at early age; (2) the temperature drop, cracking time, cracking stress, and ratio of cracking stress to axial tensile strength decreased; (3) the autogenous shrinkage as well as restrained stress rate increased; (4) the basic tensile creep, specific tensile creep, and creep-shrinkage ratio increased.

Concrete structures reinforced with fiber-reinforced polymer (FRP) bars are frequently subjected to cyclic loadings. The bond behavior between FRP bars and concrete under cyclic loading is important in evaluating the seismic and fatigue performance of concrete structures reinforced with FRP bars. Although the bond stress-slip relationship between basalt FRP (BFRP) bars and concrete under static loading has been investigated, investigations on the bond behavior between BFRP bars and concrete under cyclic loading remain lacking. The present study presented experimental investigations on the bond behavior between BFRP bars and concrete under cyclic loading using a pull-out test. Test results showed that: (1) the bond stress-slip relationship between BFRP bars and concrete revealed the behavior at different phases: the elastic phase, the cracking propagation phase, the cracking closure phase, and the friction phase; (2) the bond strength between BFRP bars and concrete under cyclic loading decreased with the increase of number of cycles; (3) the slip corresponding to bond strength between BFRP bars and concrete under cyclic loading increased with the increase of number of cycles; (4) the hysteretic curve area between BFRP bars and concrete under cyclic loading decreased with the increase of number of cycles; (5) several prediction models for bond strength, slip corresponding to bond strength and hysteretic curve area between BFRP bars and concrete under cyclic loading were proposed considering number of cycles; (6) the residual bond strength between BFRP bars and concrete decreased while the slip corresponding to residual bond strength increased after cyclic loading.

Due to a reliance on solar radiation, the aerosol optical depth (AOD) is observed only during the day by passive satellite-based instruments such as the MODerate resolution Imaging Spectroradiometer (MODIS). Research on urban air quality, atmospheric turbidity, and evolution of aerosols in the atmospheric boundary layer, however, requires 24-h measurement of aerosols. A lidar system is capable of detecting the vertical distribution of the aerosol extinction coefficient and calculating the AOD throughout the day, but routinely lidar observation is still quite limited and the results from MODIS and lidar sometimes are contradictory in China. In this study, long-term lidar observations from 2005 to 2009 over Hong Kong were analyzed with a focus on identification of the reasons for different seasonal variation in the AOD data obtained from MODIS and lidar. The lidar-retrieved AOD shows the lowest average level, but has the most significant diurnal variation during the summer. When considering only a 5-h period between 10:00 a.m. and 3:00 p.m. local time to match satellite passages, the average of the lidar-retrieved AOD doubles during the summer and exceeds that during the winter. This finding is consistent with the MODIS observation of a higher AOD during the summer and a lower AOD during the winter. The increase in the aerosol extinction coefficient in the upper level of the mixing layer makes the greatest contribution to the increase in the AOD at midday during the summer. These assessments suggest that large over-estimation may occur when long-term averages of AOD are estimated from passive satellite observations.

In this study, a vertical correction method based on a two-layer aerosol model is proposed to estimate the surface-level visibility from satellite measurements of aerosol optical depth (AOD). The meteorological parameters from the re-analysis data of the National Centers for Environmental Prediction (NCEP) are applied to estimate the aerosol layer height (ALH) of the two-layer aerosol model via an automatic workflow. The estimated extinction coefficients near the surface by AOD/ALH over the single point of a lidar site in Shanghai agree well with those of the ground measurements from a visibility sensor, with a correlation coefficient of 0.86 and root mean squared error (RMS) of 0.19 km − 1 for the data set from April 18, 2008 to April 30, 2014. The season-long spatial comparison demonstrates that most of the correlation coefficients (90%) are > 0.6, and more than half of the samples (68%) have coefficients higher than 0.7 for the data set from January 1 to April 30, 2014. Dust transportation and higher relative humidity (RH) have been confirmed to be important factors in reducing the accuracy of estimated visibility, as these situations fail to meet the assumptions of the two-layer model. Additionally, the less-rigorous cloud mask algorithm of the Moderate Resolution Imaging Spectroradiometer (MODIS)/AOD might lead to overestimates of AOD, and further underestimating of the surface-level visibility. The spatial variation of temporal correlation coefficients shows that most comparison sites (> 74%) of satellite estimations agree well with the surface-level visibility measurements, with correlation coefficients up to 0.6 during the study period. The northern area of Eastern China presented better agreement than the southern area. This may be related to the complex underlying surface characteristics and higher RH in the southern part. This work will significantly improve the quality of climate simulations and air quality forecasts in Eastern China.

The lack of long-term PM 2.5 measurements in developing countries makes it difficult to quantify the overall PM 2.5 pollution exposures and health impacts in these countries where the PM 2.5 concentrations are often very high. Moreover, it is also difficult for traditional fixed-site monitoring to capture the substantial spatial variability of PM 2.5 over dense urban areas or regions with significant topography. Hence, recent developments in satellite-based remote-sensing allowing the reconstruction of long-term, wide-area and high-resolution estimates of current and historical PM 2.5 concentration is an important step forward, allowing the quantification of the long-term pollution exposure of PM 2.5 in developing cities and in dense urban areas using the satellite-derived PM 2.5 data. In this study, instead of just looking at the spatial average PM 2.5 concentrations, we have studied the long-term population exposure of PM 2.5 by analyzing the population-weighted PM 2.5 concentrations at regional, city and district scales by combining 1 km × 1 km satellite-derived PM 2.5 and population density data sets. The variation of population exposure to PM 2.5 across the urban areas in the Pearl River Delta (PRD) region from 2000 to 2014 was studied. Our result shows that the PM 2.5 concentrations over the PRD increased steadily from 2000 to 2004, remained at quite a high level through 2008 and then started to decline after 2009. More importantly, our analysis also shows that, at regional, city and district levels, the population-weighted mean PM 2.5 concentrations from data with 1 km resolutions are typically the highest, followed by the population-weighted mean PM 2.5 concentrations from data with 10 km resolutions and then the simple spatial PM 2.5 averages. This suggests that the use of simple spatial concentrations can lead to systematic underestimation of the overall population exposure and the associated health impacts. This systematic difference is related to the positive correlation between PM 2.5 pollutant concentration and population density, and shows the usefulness of using high-resolution satellite-retrieved PM 2.5 concentrations to quantify the overall population exposure. The higher population-weighted mean PM 2.5 concentration in comparison with simple spatial average indicates that, for more effective reduction of overall population exposure and protection of public health, control efforts must be further targeted at high-population high-pollution areas, and land-use and city planning should also encourage population to redistribute away from the highly polluted areas.

The microstructures, interfaces, and physics properties of the devices with multifunctional barrier materials are investigated to achieve integration of perovskite oxide films with Cu film on Si for the application in nonvolatile Si-based ferroelectric random access memories (FeRAMs) with the on-chip copper metallization of advanced microelectronic devices. La 0.5 Sr 0.5 CoO 3 /Pb(Zr 0.4 Ti 0.6 )O 3 /La 0.5 Sr 0.5 CoO 3 (LSCO/PZT/LSCO) capacitors have been successfully fabricated on the Cu/Ni–Al/SiO 2 /Si stack structure for Cu interconnects using an amorphous Ni–Al (a-Ni–Al) film as the barrier layer for the Cu/SiO 2 interface and a mixed-phase nanocrystalline Ni–Al (n-Ni–Al)/a-Ni–Al ((n+a)-Ni–Al) bi-layer-like film as the oxygen diffusion barrier layer for the LSCO/Cu interface, respectively. The perfect structure compatibility and clear interfaces between thin films are achieved. Excellent physical properties of the capacitor, such as high remnant polarization (∼26 μC/cm 2 ), good reliability and dielectricity, powerfully confirm that Ni–Al film can be used as the barrier layer between Cu and SiO 2 or LSCO. The barrier properties of the (n+a)-Ni–Al can be understood as two aspects: n-Ni–Al component can level up the roughness of Cu/barrier/SiO 2 /Si surface and relax stresses in the multilayer stack heterostructure, and a-Ni–Al can inhibit oxygen penetration. Compared to the (n+a)-Ni–Al, only n-Ni–Al film without a-Ni–Al layer couldn't prevent Cu oxidation due to oxygen penetration leading to the failure of devices, whose failure mechanism can be ascribed to the reactions between Cu and complex oxides. The results fully illustrate the viability of the lead-based ferroelectric capacitors grown on Cu/Barrier/SiO 2 /Si stack structure with Ni–Al barrier for the future ferroelectric capacitor based devices with Cu metallization.

As the capital of China, Beijing is the subject of great concern regarding atmospheric pollution, especially that of fine particulate matter (PM2.5). In winter 2017 (i.e., November 2017 to February 2018), PM2.5 concentration in Beijing decreased to its lowest value in the past ten years. In this study, we sought to investigate the impacts of meteorology and emission control on this abnormally low pollution phenomenon. Weather Research and Forecasting coupled with Chemistry (WRF-Chem) simulations show that sensitivity to meteorological factors accounts for approximately 51% of the observed change between winters 2016 and 2017 in Beijing. We further compared the pollution dispersion condition of winters 2016 and 2017 in terms of large-scale circulation patterns and local mixing layer heights (MLHs). The meteorological condition in 2017 was characterized by stronger wind speed (WS) and higher MLH. We classified circulation patterns into two types using the obliquely rotated Principal Component Analysis in T-mode (T-PCA) method. Active weather was found to be associated with high MLH, high near-surface WS, and high ventilation coefficient (VC), which favors the dispersion of pollutants. In contrast, the changes of meteorological variables and pollution conditions are almost opposite for stable weather. Active weather amounted to 73 and 85 days for winters 2016 and 2017, respectively. Stable weather conditions prevailed on 46 days in winter 2016, and 32 days in 2017. Less stable weather during winter 2017 compared with that of winter 2016 possibly favored efficient ventilation of boundary-layer pollution. A lack of persistent stable weather also contributed to low PM2.5 concentration in 2017. This research is important for air-pollution assessment and regional environmental management.

To make use of laser-accelerated protons in real-world applications, specially-designed beamlines are required to control and improve the quality of the beam. At Peking University, the Compact LAser Plasma Accelerator (CLAPA) has been built, and is now coupled with an image-relaying beamline. The primary collection component of this beamline is an electromagnetic quadrupole triplet lens. As this lens is the first and the most crucial step for successful beam transport, we have systematically studied the focusing effect on the laser-driven protons, in terms of emittance , beam profile, and collection efficiency. We found that the normalized rms emittance of the protons can increase significantly, from the order of a fraction of mm ⋅ mrad to several mm ⋅ mrad, due to the dispersion of the phase space ellipse caused by the joint effect of the wide energy spread and the nonlinear field at the edge of the quadrupoles. The focusing profile and efficiency are also sensitive to the position and angular deviations of the injected proton beams . With fine adjustment, we found that the collection efficiency can be improved from lower than 10% up to 29%, for protons at the reference energy for CLAPA.

Human exposure to PM2.5, represented by population-weighted mean PM2.5 concentration (cρ), declines under three conditions: (1) mean PM2.5 concentration declines, (2) PM2.5 concentration within urban areas goes through more of a decrease than within rural areas, or (3) city planning relocates people into cleaner areas. Decomposing these effects on human exposure is essential to guide future environmental policies. The lack of ground PM2.5 observations limits the assessment of human exposure to PM2.5 over China. This study proposed a novel diagnostic framework using satellite observations to decompose the variation in cρ resulting from change in the mean PM2.5 concentration, spatial difference in PM2.5 change, and demographic change. In this framework, we decomposed cρ into mean PM2.5 concentration (c0) and pollution-population-coincidence induced PM2.5 exposure (PPCE). We then used this framework to decompose the variation in cρ over China within three recent Five-Year Plans (FYPs) (2001–2015). The results showed that the decline in c0 reduced cρ in most provinces within the eleventh and twelfth FYPs. The spatial difference in PM2.5 change reduced the PPCE and cρ in most provinces within the tenth and twelfth FYPs, with the most substantial reduction rate of −3.64 μg m−3·yr−1 in Tianjin within the twelfth FYP. Rural-to-urban migration resulting from rapid urbanization, however, increased the PPCE and cρ (by as much as 0.22 μg m−3·yr−1) in all provinces except Taiwan within all three FYPs. The demographic change reduced cρ in Taiwan because of the migration of population into less polluted areas. To better reduce human exposure, it is recommended that control efforts further target populous residential areas and urbanization planning relocates people into less polluted areas. Our decomposition framework paves a new way to decompose the human exposure to other air pollutants in China and other regions.

Fiber-reinforced polymer (FRP) rebars are utilized extensively in reinforced concrete structures because of advantageous mechanical and physical properties. The bond behavior of concrete members reinforced with FRP rebars is essential to evaluate the load carrying capacity of concrete members. Although the bond behavior of concrete members reinforced with FRP rebars under static loading has been studied, research studies on the bond behavior of concrete members reinforced with basalt FRP (BFRP) rebars under dynamic loading are still lacking. The bond behaviors of concrete members reinforced with BFRP rebars under different strain rates were investigated. Test results and corresponding analysis showed that: (1) three bond failure modes of concrete members reinforced with BFRP rebars under dynamic loading were observed: crushing of concrete, bond failure at interface between resin and concrete, and bond failure at interface between fiber and resin; (2) the bond strength of concrete members reinforced with BFRP rebars increased as the strain rates increased and a model for bond strength was proposed considering strain rate; (3) the slip corresponding to bond strength decreased as the strain rates increased and a model for the slip corresponding to bond strength of concrete members reinforced with BFRP rebars was proposed considering strain rate; (4) a prediction model for bond stress-slip relationship of concrete members reinforced with BFRP rebars considering strain rate was proposed based on the BPE model which considers concrete cover, transverse confinement, steel rebar spacing and compressive strength of concrete, etc.. The proposed model showed good correlation with experimental results.

Although ground-level monitoring can provide accurate PM2.5 measurements, it has limited spatial coverage and resolution. In contrast, satellite-based monitoring can provide aerosol optical depth (AOD) products with higher spatial resolution and continuous spatial coverage, but it cannot directly measure ground-level PM2.5 concentration. Observation-based and simulation-based approaches have been actively developed to retrieve ground-level PM2.5 concentrations from satellite AOD and sparse ground-level observations. However, the effect of aerosol characteristics (e.g., aerosol composition and size distribution) on the AOD–PM2.5 relationship is seldom considered in observation-based methods. Although these characteristics are considered in simulation-based methods, the results still suffer from model uncertainties. In this study, we propose an observation-based algorithm that considers the effect of the main aerosol characteristics. Their related effects on hygroscopic growth, particle mass extinction efficiency, and size distribution are estimated and incorporated into the AOD–PM2.5 relationship. The method is applied to quantify the PM2.5 distribution in China. Good agreements between satellite-retrieved and ground-observed PM2.5 annual and monthly averages are identified, with significant spatial correlations of 0.90 and 0.76, respectively, at 565 stations in China. The results suggest that this approach can measure large scale PM distributions with verified results that are at least as good as those from simulation-based estimations. The results also show the method's capacity to identify PM2.5 spatial distribution with high-resolution at national, regional, and urban scales and to provide useful information for air pollution control strategies, health risk assessments, etc.

Large-scale α-Fe2O3 porous nanorod array precursors with high-orientation have been successfully prepared using one-pot hydrothermal method without any template. Upon calcination, α-Fe2O3 porous nanorod arrays have been fabricated. Synthesized samples were characterized by X-ray diffraction, field emission scanning electron microscopy, (High-resolution) transmission electron microscopy and Thermal-gravimetric analyses. The feature sizes of the porous nanorods are around 20–30 nm in lateral direction and 110–120 nm in length. The longer axis direction, which is the growth direction of α-Fe2O3 nanorod arrays was determined to be [ 1 ¯ 2 0 ] by transmission electron microscopy. The effects of the reaction time, reaction temperature, and acetic acid on the morphologies of porous nanorod arrays were systematically investigated. A possible formation mechanism was proposed by orientation attachment. The synthesized α-Fe2O3 porous nanorod arrays exhibited a high adsorption capacity for the model organic pollutant of Methyl orange. Therefore, α-Fe2O3 porous nanorod arrays have a potential application in waste water treatment.

MODIS derived aerosol optical depths (AODs) at 550 nm are compared with sunphotometer CE318 measurements at 7 sites located at Yangtze River Delta (YRD) in China from July to October, 2007. The evaluation result indicates that MODIS AODs (Collection 5, C005) are in good agreement with those from CE318 in dense vegetation regions, but show more differences in those regions with complex underlying surface (such as at lake water and urban surface sites). Reasons for these differences are discussed after removing cases with significant errors caused by validation scheme. The final validation result shows that MODIS AODs are in good agreement with CE318 with a correlation coefficient of 0.85 and RMS of 0.15. 90% of MODIS cases fall in the range of Δ τ = ± 0.05 ± 0.20 τ , indicating MODIS aerosol retrieval algorithm, aerosol models and surface reflectance estimate are generally suitably reasonable for aerosol retrieval in YRD. However, MODIS AODs show a systemic errors with fitted line of y = 0.75 x + 0.13, indicating underestimation of AOD when aerosol loadings are high. Aerosol models and surface reflectance estimations are dominant sources of MODIS aerosol retrieval errors.