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The development of photocatalysts for efficient tetracycline (TC) degradation under visible light is urgently needed yet remains a great challenge. Most semiconductor photocatalysts with low specific surface area are easy to agglomerate in solution and unfavorable for enriching pollutants. Herein, we present the preparation of pomegranate-shaped zinc oxide@zeolitic imidazolate framework (ZnO@ZIF-8) by in situ growth of ZIF-8 on a petal-shaped ZnO template that enhances the adsorption and photocatalytic degradation of TC. ZnO@ZIF-8 exhibits an excellent photostability and a TC photodegradation efficiency of 91% under visible light (λ420 nm) in 50 min at room temperature, which can be recycled over five times without any loss of activity. Moreover, the plausible photocatalysis reaction mechanism and the degradation intermediates are elucidated with the aid of three-dimensional excitation-emission matrix spectra and liquid chromatography-mass spectrometry system. This study offers new insights into the design of antibiotic degradation photocatalysts and the development of photocatalysts with broad-spectrum responses for efficient TC elimination.

Terrestrial ecosystems in China receive the world’s largest amount of reactive nitrogen (N) deposition. Recent controls on nitrogen oxides (NOx = NO + NO2) emissions in China to tackle air pollution are expected to decrease N deposition, yet the observed N deposition fluxes remain almost stagnant. Here we show that the effectiveness of NOx emission controls for reducing oxidized N (NOy = NOx + its oxidation products) deposition is unforeseen in Eastern China, with one-unit reduction in NOx emission leading to only 55‒76% reductions in NOy-N deposition, as opposed to the high effectiveness (around 100%) in both Southern China and the United States. Using an atmospheric chemical transport model, we demonstrate that this unexpected weakened response of N deposition is attributable to the enhanced atmospheric oxidizing capacity by NOx emissions reductions. The decline in N deposition could bear a penalty on terrestrial carbon sinks and should be taken into account when developing pathways for China’s carbon neutrality.

Temperature inversion tends to inhibit the transfer of momentum, heat and moisture in the atmospheric boundary layer, which is often accompanied by severe air pollution. Recently, severe haze pollution has frequently occurred in North China. In this study, the characteristics of temperature inversion on severe polluted days (SPDs) in Beijing were investigated by using radiosonde data with standard pressure levels from 2011 to 2016. Both surface-based inversion (SI) and elevated inversion (EI) were analyzed. 93% of the SPDs were accompanied by temperature inversion, most of which occurred in wintertime. Annual frequency of SI (FSI) and EI (FEI) showed slight fluctuations with mean value of 0.18 and 0.67, respectively. Overall, the annual SI was stronger and deeper than annual EI. Seasonally, the SI was most frequent (0.39) in autumn, in contrast to EI that occurred most frequently (0.95) in summer. Both SI and EI were weakest in summer and strongest in winter. Average monthly SI strength was about 0.38 °C in summer and 2.40 °C in winter, average monthly EI strength was about 0.64 °C in summer and 2.20 °C in winter. The average monthly SI and EI were deepest in winter and shallowest in summer. SI depth were 778 m and 221 m in winter and summer, EI were 630 m and 336 m in winter and summer. The substantially strong liner relationship was found between seasonal inversion strength and PM2.5 concentration, and the inversion strength was found to be better compared with the inversion depth at predicting the PM2.5 concentration during SPDs. Obvious lower air outflow and turbulent kinetic energy were found in SPDs compared to non-SPDs, which indicated weaker turbulence in SPDs. Future efforts should focus on accurate model simulations of temperature inversions in SPDs.

Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn’s disease (CD), are chronic autoimmune diseases with a high recurrence rate. Epidemiological data have shown that the incidence of IBD increases annually because of improved sanitary conditions and reduced parasitic infection rates. In this experiment, experimental colitis was induced in mice by administering 2,4,6-trinitrobenzene sulfonic acid (TNBS) 28 days after they were infected with Trichinella spiralis to confirm that T. spiralis infection could alleviate the severity of TNBS-induced colitis. Thirty-six male BALB/c mice aged 6–8 weeks were randomly divided into four groups: control group (with 50% ethanol, Control), T. spiralis-infected group (TS-Control), TNBS-induced colitis model group (Colitis), and T. spiralis-pre-infected and TNBS-induced colitis group (TS-Colitis). The mice were sacrificed 3, 7, and 14 days after the model was established. Changes in various colitis indicators to investigate the effect of T. spiralis infection on TNBS-induced murine CD model. Results showed that the weight, DAI score, and macroscopic and microscopic colon damage in the TS-Colitis significantly decreased compared with those in the Colitis. ELISA revealed that the IFN-γ expression decreased and the IL-4 expression increased in the TS-Colitis compared with those in the Colitis. Western Blotting results revealed that the NF-κB expression increased in the Colitis and higher than those in the TS-Colitis. And Flow cytometry results revealed that the percentage of CD4+CD25+Foxp3+ Treg cells significantly increased in the TS-Colitis. T. spiralis-infected mice induced Th2 immune responses and balanced Th1 immune responses stimulated by TNBS to ameliorate intestinal inflammation.

The double revolving fiber positioning technology is one of the key technologies for the success of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). The accuracy of fiber positioning will directly affect the observation efficiency of LAMOST. To achieve higher fiber positioning accuracy, the original open-loop controlled fiber positioning system urgently needs to be upgraded into a closed-loop control system. The fiber detection is the most important part of the closed-loop controlled fiber positioning system. The back-illuminated detection method is usually used to detect the fiber position by directly detecting the light spot generated at the fiber end in the multi-fiber spectral surveys. In this paper, we introduce a new method to measure the fiber position based on the image of the front-illuminated LAMOST focal plane. The front-illuminated image does not require lighting devices inside the spectrograph, and it could reduce the instability and light pollution in the spectrograph end. Our method measures the fiber position by fitting the profile of the fiber pinhole with a 2D Gaussian function. A series of tests show that the relative position measurement precision of the front-illuminated method is about 0.″12, and the method could have the same accuracy as the back-illuminated method once the system bias is calibrated by a simple radial correction function. The required fiber positioning accuracy of LAMOST is 0.″4, and the new method satisfies the requirement of LAMOST fiber detection accuracy and could be used in the closed-loop fiber control system.

The North China Plain has been identified as a significant hotspot of ammonia (NH3) due to extensive agricultural activities. Satellite observations suggest a significant increase of about 30 % in tropospheric gas-phase NH3 concentrations in this area during 2008–2016. However, the estimated NH3 emissions decreased slightly by 7 % because of changes in Chinese agricultural practices, i.e., the transition in fertilizer types from ammonium carbonate fertilizer to urea, and in the livestock rearing system from free-range to intensive farming. We note that the emissions of sulfur dioxide (SO2) have rapidly declined by about 60 % over the recent few years. By integrating measurements from ground and satellite, a long-term anthropogenic NH3 emission inventory, and chemical transport model simulations, we find that this large SO2 emission reduction is responsible for the NH3 increase over the North China Plain. The simulations for the period 2008–2016 demonstrate that the annual average sulfate concentrations decreased by about 50 %, which significantly weakens the formation of ammonium sulfate and increases the average proportions of gas-phase NH3 within the total NH3 column concentrations from 26 % (2008) to 37 % (2016). By fixing SO2 emissions of 2008 in those multi-year simulations, the increasing trend of the tropospheric NH3 concentrations is not observed. Both the decreases in sulfate and increases in NH3 concentrations show highest values in summer, possibly because the formation of sulfate aerosols is more sensitive to SO2 emission reductions in summer than in other seasons. Besides, the changes in NOx emissions and meteorological conditions both decreased the NH3 column concentrations by about 3 % in the study period. Our simulations suggest that the moderate reduction in NOx emissions (16 %) favors the formation of particulate nitrate by elevating ozone concentrations in the lower troposphere.

Ag3VO4/Ag2VO2PO4 heterostructure with highly enhanced visible light photocatalytic activity were synthesized by using Ag2VO2PO4 as the sacrificed template in different concentration of ammonia solution. Their crystalline structure, morphology, optical, and electrochemical properties were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy, infrared spectroscopy, and electrochemical measurements. The photocatalytic degradation activities of as-prepared samples were evaluated by the photocatalytic of methylene blue (MB), methyl orange (MO) and imidacloprid in the aqueous phase. Compared with bare Ag2VO2PO4, the etched samples Ag3VO4/Ag2VO2PO4 exhibit the significantly enhanced photocatalytic activity under visible light irradiation. The Ag3VO4/Ag2VO2PO4 with 0.15 M etched sample exhibits the highest activity, which are nearly 3.8, 8.6 and 9 times higher than bare Ag2VO2PO4 for removal of MB, MO and imidacloprid, respectively. The improved photocatalytic performance of Ag3VO4/Ag2VO2PO4 can be attributed to the formation of Ag2VO2PO4/Ag3VO4 heterojunction, which suppresses the recombination of photoinduced charges and prolongs the lifetime of the charges. Moreover, the photostability and dominant active species were investigated.

Electroencephalography (EEG) decoding is an important part of Visual Evoked Potentials-based Brain-Computer Interfaces (BCIs), which directly determines the performance of BCIs. However, long-time attention to repetitive visual stimuli could cause physical and psychological fatigue, resulting in weaker reliable response and stronger noise interference, which exacerbates the difficulty of Visual Evoked Potentials EEG decoding. In this state, subjects’ attention could not be concentrated enough and the frequency response of their brains becomes less reliable. To solve these problems, we propose an attention-based parallel multiscale convolutional neural network (AMS-CNN). Specifically, the AMS-CNN first extract robust temporal representations via two parallel convolutional layers with small and large temporal filters respectively. Then, we employ two sequential convolution blocks for spatial fusion and temporal fusion to extract advanced feature representations. Further, we use attention mechanism to weight the features at different moments according to the output-related interest. Finally, we employ a full connected layer with softmax activation function for classification. Two fatigue datasets collected from our lab are implemented to validate the superior classification performance of the proposed method compared to the state-of-the-art methods. Analysis reveals the competitiveness of multiscale convolution and attention mechanism. These results suggest that the proposed framework is a promising solution to improving the decoding performance of Visual Evoked Potential BCIs.

Trichinella spiralisserpin-type serine protease inhibitors (TsSPIs) are expressed in adult worms (AW), newborn larvae (NBL) and muscle larvae (ML) ofT. spiralis, with the ML stage demonstrating the highest expression level. This study aims to determine TsSPI functions in larval viability and invasion of intestinal epithelial cells in vitro, as well as their development, survival, and fecundity in vivo via RNAi. TsSPI-specific siRNAs and dsRNA were transfected into ML by incubation. The silencing effect of TsSPI transcription and expression was determined using qPCR and western blot, respectively. After incubation in 60 ng/μL dsRNA–TsSPI for 3 days, larval TsSPI mRNA and protein expression levels were reduced by 68.7% and 68.4% (P 0.05). Our results revealed that RNAi-mediated silencing of TsSPI expression inT. spiralissignificantly reduced larval infectivity and survival in the host but had no effect on the survival rate and fecundity. Furthermore, TsSPIs have no effect on the growth and reproduction of parasites but may be directly involved in regulating the interaction ofT. spiralisand the host. Therefore, TsSPIs are crucial in the process ofT. spiralislarval invasion and parasite survival in the host.

Anthropogenic emissions in China play an important role in altering global radiation budget. Over the recent decade, the clean-air options in China result in substantial reductions in anthropogenic emissions, especially sulfur dioxide (SO2), and improved air quality. However, the associated changes in aerosol climate effects are poorly understood. In this study, we use an advanced global climate model integrated with latest anthropogenic emission inventory to estimate the changes in the aerosol radiative forcings by the emission variation in China between 2008 and 2016. First, our simulations exhibit decreases of 46 % and 25 % for the annual mean surface-level sulfate and black carbon (BC) mass concentrations in East China, respectively, which is the key region subject to stringent emission control options. The decreasing tendency of aerosol optical depth and aerosol absorption optical depth retrieved by satellites is also captured by the model for the period. We find that the resultant net radiative forcing by the changes in the BC and SO2 emissions is −0.04 W m−2 in East China. The substantial reductions in SO2 emissions diminish the scattering effects of sulfate and lead to an overall change of +0.17 W m−2 for the annual mean all-sky shortwave aerosol direct radiative forcing at the top of the atmosphere and +0.13 W m−2 for aerosol-induced cloud radiative forcing. In the meantime, the reduction in BC emissions induces a negative BC radiative forcing of −0.34 W m−2. By accounting for the joint effect of BC and SO2 emissions, our results demonstrate that the positive radiative forcing by the SO2 emission reductions is counteracted by the decrease of BC in China over the recent decade. While the local radiative forcing is small due to the counteracted effects of SO2 and BC emissions, it is relatively larger (+0.16 W m−2) over the north Pacific remote regions for this period, primarily contributed by the reductions in sulfate particles and their effects on cloud properties. With a comprehensive future emission scenario for 2030 and 2050 developed by the recent study, we predict that the strictest environmental policies will induce the change of aerosol radiative forcings of +0.55 and +1.23 W m−2 over East China between 2016–2030 and 2016–2050, respectively. Targeted emission control policies are desirable to improve air quality and mitigate climate change in the future.

Biogenic emission models are developed on the foundation of leaf physiological processes and driven by a set of physical and biological factors. To estimate emissions online, many studies used weat...

China is one of the largest agricultural countries in the world. The NH3 emissions from agricultural activities in China significantly affect regional air quality and horizontal visibility. To reliably estimate the influence of NH3 on agriculture, a high-resolution agricultural NH3 emissions inventory, compiled with a 1 km × 1 km horizontal resolution, was applied to calculate the NH3 mass burden in China. The key emission factors of this inventory were enhanced by considering the results of many native experiments, and the activity data of spatial and temporal information were updated using statistical data from 2015. Fertilizer and husbandry, as well as farmland ecosystems, livestock waste, crop residue burning, fuel wood combustion, and other NH3 emission sources were included in the inventory. Furthermore, a source apportionment tool, ISAM (Integrated Source Apportionment Method), coupled with the air quality modeling system RAMS-CMAQ (Regional Atmospheric Modeling System and Community Multiscale Air Quality), was applied to capture the contribution of NH3 emitted from total agriculture (Tagr) in China. The aerosol mass concentration in 2015 was simulated, and the results showed that a high mass concentration of NH3, which exceeded 10 μg m−3, appeared mainly in the North China Plain (NCP), Central China (CNC), the Yangtz River Delta (YRD), and the Sichan Basin (SCB), and the annual average contribution of Tagr NH3 to PM2.5 mass burden in China was 14–18 %. Specific to the PM2.5 components, Tagr NH3 provided a major contribution to ammonium formation (87.6 %) but a tiny contribution to sulfate (2.2 %). In addition, several brute-force sensitivity tests were conducted to estimate the impact of Tagr NH3 emissions reduction on the PM2.5 mass burden. Compared with the results of ISAM, it was found that even though the Tagr NH3 only contributed 10.1 % of nitrate under current emissions scenarios, the reduction of nitrate could reach 98.8 % upon removal of the Tagr NH3 emissions. The main reason for this deviation could be that the NH3 contribution to nitrate is small under rich NH3 conditions and large in poor NH3 environments. Thus, the influence of NH3 on nitrate formation could be enhanced with the decrease of ambient NH3 mass concentration.

Biogenic volatile organic compounds (BVOCs) emitted by terrestrial vegetation significantly influence the atmospheric chemistry and global climate. Previous studies calculated BVOC emissions outside the comprehensive terrestrial ecosystem processes and oversimplified the representation of canopy environments which exert substantial impacts on BVOC emissions. The sophisticated land surface model CLM (Community Land Model) reproduces essential ground and canopy characteristics and can calculate BVOC emissions as a step of integrated biogeochemical processes. In this study, the land surface scheme CLM version4 (CLM4) of WRF (Weather Research and Forecasting model) was used to estimate BVOC emissions in China. Based on highly-resolved meteorological outputs derived from WRF, CLM4 computed real-time physical and biological variables to drive MEGAN (Model of Emissions of Gases and Aerosols from Nature), a BVOC estimation algorithm embedded within biogeochemistry component of CLM4, to calculate plant emission flux. MODIS (Moderate Resolution Imaging Spectroradiometer) land-use data with high resolutions was introduced in WRF to replace the outdated land surface parameters. An emission inventory of isoprene and monoterpenes (including α-pinene, β-pinene, 3-carene, t-β-ocimene, limonene, sabinene and myrcene) with high spatiotemporal resolution (12 × 12 km, hourly) was established for the year 2018. The annual BVOC emission in China was 14.7 Tg C, in which isoprene contributes about 78.3 % (11.5 Tg C), followed by α-pinene (1.2 Tg C) and β-pinene (0.7 Tg C). Due to the strong emission capacity and large areas, broadleaf forests contribute to 76.8 % of total isoprene emission and 72.1 % of monoterpenes emission, respectively. BVOC emissions showed marked seasonal and diurnal patterns with the peak emission occurring in summer and midday. Spatially, high emissions of BVOC were mainly concentrated in southern and northeastern China, as well as the Qinling Mountains in central China, accounting for 91.4 % of national emission. Guangxi, Yunnan and Hunan provinces are significant emitters due to large area of vegetation with high emission rate and favored environmental conditions. The emission estimates are compared to past modeling results, field measurements and further evaluated against top-down isoprene emission estimates. Generally, the coupled mode produced a reasonable simulation in both emission amounts and the spatiotemporal distribution of BVOCs. The WRF–CLM–MEGAN coupling framework could be further integrated with atmospheric chemistry model to investigate BVOC chemistry and their effects on regional pollution and climate.

Data for JGR-A submission 2019JD031301R

Satellite observations show a global maximum in ammonia (NH3) over the Indo-Gangetic Plain (IGP), with a peak in summer. However, it has never been explained explicitly. In this study, we investigated the causes of high NH3 loading over the IGP in summer using WRF-Chem (Weather Research and Forecasting model coupled to chemistry). IGP has relatively high NH3 emission fluxes (0.4 t km−2 month−1) due to intensive agricultural activities and high air temperature in summer. Additionally, low sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions and high air temperature limit the gas-to-particle conversion of NH3, particularly for ammonium nitrate formation. Moreover, the barrier effects of the Himalayas in combination with the surface convergence weaken the horizontal diffusion of NH3. The high NH3 loading over the IGP mainly results from the low gas-to-particle partitioning of NH3 caused by low SO2 and NOx emissions. It contrasts to those in the North China Plain, where high SO2 and NOx emissions promote the conversion of gaseous NH3 into particulate ammonium.

Trichinella spiralis (T. spiralis) is widely distributed throughout the world and can cause serious zoonotic parasitic diseases. Serine protease inhibitors (SPIs) have unique enzyme inhibitory activity and occupy an important position in the interaction between parasites and hosts. In order to further understand the immunoprotective effect of SPIs on T. spiralis invasion in vivo, the Kazal and Serpin type SPI of T. spiralis (TsKaSPI and TsAdSPI) were mixed with Freund’s adjuvant in equal volume to immunize mice. The results showed that the expression of IgG1 and IgG2a in serum, the proliferation of spleen cells, and the expression level of cytokines were all increased. The results of flow cytometry showed that the expression of CD4+CD25+Foxp3+ Tregs, CD8+CD28− T cells, CD19+CD5+CD1dhi Bregs in spleen were also increased. Therefore, both TsKaSPI and TsAdSPI could induce strong humoral and cellular immune responses. And the results of adult reduction rate and pathological changes of intestine after adult invasion also indicated that both TsKaSPI and TsAdSPI could prevent T. spiralis from invading intestine. To explore the regulatory effects of TsKaSPI and TsAdSPI on the immune function of macrophage, the results of ELISA showed that the expression of cytokines in cell supernatant were increased. And the results of Western blot showed that both TsKaSPI and TsAdSPI could induce phosphorylation of JAK2 and STAT3 receptors, thereby affecting the signal transduction of macrophages. This experiment demonstrated that SPIs could act as effector molecules affecting the immune function of host when infected with T. spiralis.

SiC ceramic has been successfully joined to Zr4 alloy using TiZrNiCu filler within the temperature range 1173 K–1263 K and 15 min holding time. The morphology of the SiC/Zr4 joints was investigated by SEM, and the phases in the joints were characterized by XRD and TEM. The results indicated that part of the Zr4 substrate dissolved into the molten filler during the brazing process, contributed to the increasing Zr content and the formation of Zr[Ti] solid solution in the joints. In addition, β-Ti phase was discovered in the brazing seam. This might be attributed to the existence of β-Ti stable elements, Cu and Ni. The interface characterization showed that SiC reacted with filler alloy during the brazing process, formed a (Zr, Ti)C reaction layer on SiC surface and Zr 2 Si compound near SiC substrate. Finally, the mechanical properties of the joints, evaluated by a shear strength test, reached a maximum of 95 MPa at the brazing temperature of 1203 K.

AlON was successfully brazed to BN-Si3N4 using a Ag-Cu-Ti filler alloy. SEM, TEM and XRD studies revealed that a TiN + TiB2 + Ti5Si3 reaction layer formed adjacent to the BN-Si3N4 while a (Cu,Al)3Ti3O layer formed adjacent to the AlON. In addition, Ag-Cu eutectic, Cu(s,s) and AlCu2Ti were observed in the brazing filler. The effect of brazing temperature on the microstructure and mechanical properties of the joints was investigated. As the brazing temperature increased, the reaction layers became thicker, while the thickness of the brazing seam decreased. Meanwhile, the amount and the size of AlCu2Ti intermetallic compounds decreased. The shear strength of the joints first increased and then dropped with increasing the brazing temperature. A joint with a maximum strength of 94 MPa was obtained when it was brazed at 850 °C for 15 min.

Delineation of agricultural fields is desirable for operational monitoring of agricultural production and is essential to support food security. Due to large within-class variance of pixel values and small inter-class difference, automated field delineation remains to be a challenging task. In this study, a strategy is proposed to effectively address this issue. Firstly, a framework was developed using the Canny operator connected with the Watershed segmentation algorithm (CW) to quickly label the training dataset, which minimizes the workload of dataset generation in comparison with the commonly used manual vectorization. Secondly, a CW-trained deep semantic segmentation network, recurrent residual U-Net, was selected to mine the low level and deep semantic features. Finally, a boundary connecting method (to integrate fragmented boundaries) was used to generate the agricultural field boundary. The proposed methods are tested over smallholder agricultural landscape in Heilongjiang province, China, using Sentinel-2 imagery. Compared with the U-Net (overall accuracy (OA) 82.18%), the residual U-Net (ResU-Net, with OA 85.78%), traditional object-based image analysis (OBIA, with OA about 82%), and the existing 10-m resolution global land cover map (FROM-GLC10), the proposed method shows an improved performance (OA 89.28%, and Kappa 0.85). The successful application of the proposed method suggests that the recurrent residual U-Net model has great universality in agricultural field boundary extraction, and the automated technique has the potential of being applied to other regions.

Information on crop types derived from remotely sensed images provides valuable input for many applications such as crop growth modeling and yield forecasting. In this paper, a random forest (RF) classifier was used for crop classification using multispectral RapidEye imagery over two study sites, one in north-eastern China and one in eastern Ontario, Canada. Both vegetation indices (VIs) and textural features were derived from the RapidEye imagery and used for classification. A total of 20 VIs, categorized into two groups with and without the red edge (RE) band in an index, were calculated. A total of eight types of textural features were derived using four different window sizes from both the RE and the near-infrared bands. To reduce redundancies among the VIs and textural features, feature selection using the principal component analysis, correlation analysis, and stepwise discriminant analysis was performed. Results showed that the overall classification accuracy was improved by ∼7% when the RE indices were combined with the five spectral bands in classification, as compared with that using the five bands alone. When textural information was included, the overall classification accuracy increased by ∼6% compared with that using the band reflectance alone. Furthermore, when all the features (band reflectance, VIs, and texture) were used, the overall classification accuracy increased by ∼12% compared with that using only the band reflectance. The RF importance measures showed that the RE reflectance was important for classification, as indicated by the high importance for the triangular vegetation index, transformed chlorophyll absorption in reflectance index, and green-rededge normalized difference vegetation index. The gray-level co-occurrence matrix mean is the most useful for classification among the textural features. The study provides a means to feature extraction and selection for crop classification from remote sensing imagery.

Timely and accurate mapping crops is essential for agricultural management, policy making and food security. The smallholder agricultural systems lead to large number of fragmented and heterogeneous landscape, making fine crop mapping a huge challenge. Feature and classifier selection are two important influencing factors in crop classification. However, there are few systematic tests to determine the specific features and classifiers needed for heterogeneous agricultural landscapes. In this study, 24 candidate spectral features, 8 spatial texture features from the red-edge (RE) and near-infrared (NIR) bands, and 4 supervised classifiers (i.e. random forest (RF), support vector machine (SVM), artificial neural network (ANN), and maximum likelihood classifier (MLC)) were used for crop mapping. 60 spatially heterogeneous landscapes in Heilongjiang Province, northeastern China were selected as the study areas, evaluated by compositional heterogeneity (homogeneity index, HOI) and configurational heterogeneity (splitting index, SPLIT). The results summarized a look-up table for searching the optimum classification features and classifiers in different landscape, providing a reference for future crop classifications and preventing the consumption of computing time. The results revealed that (1) an optimal feature-subset (with reduced data volume by 65%) can achieve high-accuracy crop mapping in heterogeneous regions. (2) The optimum type and number of features and classifiers are landscape sensitive. When a specific accuracy was required, homogenous regions need a smaller number of features and a simple MLC could meet the requirement. (3) The impact of configurational heterogeneity on textural features is more significant, while compositional heterogeneity performs better on spectral Vegetation Indices (VIs). Findings from this study provide a general guideline for crop mapping in plains or fragmented landscape and areas with single or complex planting structure.

In this study, an object-based image analysis (OBIA) approach was developed to classify field crops using multi-temporal SPOT-5 images with a random forest (RF) classifier. A wide range of features, including the spectral reflectance, vegetation indices (VIs), textural features based on the grey-level co-occurrence matrix (GLCM) and textural features based on geostatistical semivariogram (GST) were extracted for classification, and their performance was evaluated with the RF variable importance measures. Results showed that the best segmentation quality was achieved using the SPOT image acquired in September, with a scale parameter of 40. The spectral reflectance and the GST had a stronger contribution to crop classification than the VIs and GLCM textures. A subset of 60 features was selected using the RF-based feature selection (FS) method, and in this subset, the near-infrared reflectance and the image acquired in August (jointing and heading stages) were found to be the best for crop classifica...

Aerosol acidity plays an important role in atmospheric chemistry. China emits large amounts of SO2, NOx, and NH3 into the atmosphere, but aerosol acidity is poorly characterized. In this study, simultaneous 1 h measurements of particulate and gaseous compositions along with the ISORROPIA-II thermodynamic equilibrium model were used to study aerosol acidity during severe haze episodes in northern China. The summed concentration of sulfate, nitrate, and ammonium was 135 ± 51 μg/m3 with a maximum of 250 μg/m3, and the gas-phase NH3 mixing ratio was 22 ± 9 ppb. Fine particles were moderately acidic, with a pH range of 3.0–4.9 and an average of 4.2, which was higher than those in the United States and Europe. Excess NH3 and high aerosol water content are responsible for the relatively lower aerosol acidity. These results suggest that the new pathways for sulfate production in China proposed by recent studies should be revisited.

East China experiences extensive crop residue burnings in fields during harvest season. The direct radiative effect (DRE) of carbonaceous aerosols from crop residue burning in June 2013 in East China was investigated using the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem). Absorption of organic aerosol (OA) in the presence of brown carbon was considered using the parameterization of Saleh et al. (2014), in which the imaginary part of the OA refractive index is a function of wavelength and the ratio of black carbon (BC) and OA. The carbonaceous emissions from crop fires were estimated using the Moderate Resolution Imaging Spectroradiometer (MODIS) fire radiative power (FRP) product with a localized crop-burning-sourced BC-to-organic carbon (OC) ratio emission ratio of 0.27. Evaluation of the model results with in situ measurements of particulate matter with aerodynamic diameter less than 2.5 µm (PM2. 5) chemical composition, MODIS aerosol optical depth (AOD) detections and meteorological observations showed that this model was able to reproduce the magnitude, spatial variation and optical characteristics of carbonaceous aerosol pollution. The observed BC and OC peak concentrations at the site in Suixi, Anhui province, during the 2013 wheat burning season reached 55.3 µg m−3 and 157.9 µg m−3. WRF-Chem simulations reproduced these trends with a correlation coefficient of 0.74, estimating that crop residue burning contributed 86 and 90 % of peak BC and OC, respectively. The simulated hourly DRE from crop residue burning at the top of atmosphere (TOA) reached a maximum of +22.66 W m−2 at the Suixi site. On average, the simulations showed that the crop residue burning introduced a net positive DRE of +0.14 W m−2 at TOA throughout East China, with BC from this source as the main heating contributor (+0.79 W m−2). The OA DRE from crop burning (−0.22 W m−2) was a combined effect of the positive DRE of absorption (+0.21 W m−2) and a stronger negative DRE of scattering (−0.43 W m−2). Sensitivity tests showed that the DRE of OA absorption strongly depended on the imaginary part of the OA refractive index, the BC-to-OA emission ratio from crop residue burning and the assumed mixing state of the aerosol, whereby the volume mixing treatment resulted in a higher positive DRE compared to the core–shell treatment. The BC mixing state and associated absorption enhancement during BC aging processes will be investigated in detail in future research.

Deletion of the Lsr2 gene in Streptomyces roseosporus up-regulated silent gene clusters and produced new secondary metabolites. An ultra-performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-QTOF-MS/MS) method was used to analyze metabolites of the mutant and wild-type strains, and recognize previously unreported sulfur-containing compounds based on their molecular formulas and fragmentation ions. The targeted isolation of unidentified compounds afforded six new sulfur-containing compounds, pyrismycins A–F (1–6), together with seven known analogues 7–13. Their cytotoxic effects were evaluated using four clinically relevant human cancer cell lines, gastric carcinoma SGC7901, breast carcinoma MDA-MB-231, lung carcinoma A549 and hepatocellular carcinoma HepG2. Compound 7 exhibited the most potent cytotoxicity with IC50 values of 1.7, 5.8 and 6.3 μM against the SGC7901, HepG2 and MDA-MB-231, respectively.

China has been experiencing fine particle (i.e., aerodynamic diameters ≤ 2.5 µm; PM(2.5)) pollution and acid rain in recent decades, which exert adverse impacts on human health and the ecosystem. Recently, ammonia (i.e., NH(3)) emission reduction has been proposed as a strategic option to mitigate haze pollution. However, atmospheric NH(3) is also closely bound to nitrogen deposition and acid rain, and comprehensive impacts of NH(3) emission control are still poorly understood in China. In this study, by integrating a chemical transport model with a high-resolution NH(3) emission inventory, we find that NH(3) emission abatement can mitigate PM(2.5) pollution and nitrogen deposition but would worsen acid rain in China. Quantitatively, a 50% reduction in NH(3) emissions achievable by improving agricultural management, along with a targeted emission reduction (15%) for sulfur dioxide and nitrogen oxides, can alleviate PM(2.5) pollution by 11−17% primarily by suppressing ammonium nitrate formation. Meanwhile, nitrogen deposition is estimated to decrease by 34%, with the area exceeding the critical load shrinking from 17% to 9% of China’s terrestrial land. Nevertheless, this NH(3) reduction would significantly aggravate precipitation acidification, with a decrease of as much as 1.0 unit in rainfall pH and a corresponding substantial increase in areas with heavy acid rain. An economic evaluation demonstrates that the worsened acid rain would partly offset the total economic benefit from improved air quality and less nitrogen deposition. After considering the costs of abatement options, we propose a region-specific strategy for multipollutant controls that will benefit human and ecosystem health.

A novel sesquiterpenoid, roseosporol A (1), together with 12 known compounds (2–13) were isolated from the ethyl acetate extract of Lsr2-deletion mutant strain of Streptomyces roseosporus. Their structures were determined by spectroscopic methods, including NMR, HRMS, UV, IR and ECD.

Biomass burning plays a significant role in air pollution and climate change. In this study, we used the method based on fire radiative energy (FRE) to develop a biomass burning emission inventory for China from 2003 to 2017. Daily fire radiative power (FRP) data in 1 km MODIS Thermal Anomalies/Fire products (MOD14/MYD14) were used to calculate FRE and combusted biomass. Available emission factors were assigned to four land-cover types: forest, cropland, grassland and shrubland. The farming system and crop types in different climate zones were taken into account in this research. Compared with traditional methods, the FRE method was found to provide a more reasonable estimates of emissions from small fires. The estimated average annual emission ranges, with a 90 % confidence interval, were 94.2 (78.7–117.6) Tg CO2 yr−1, 4.9 (2.5–8.3) Tg CO yr−1, 0.19 (0.05–0.51) Tg CH4 yr−1, 0.52 (0.18–0.81) Tg NMHC yr−1, 0.18 (0.04–0.39) Tg NOx yr−1, 0.07 (0.02–0.17) Tg NH3 yr−1, 0.03 (0.01–0.06) Tg SO2 yr−1, 0.04 (0.01–0.08) Tg BC yr−1, 0.3 (0.08–0.53) Tg OC yr−1, 0.49 (0.20–0.88) Tg PM2.5 yr−1, 0.56 (0.16–1.11) Tg PM10 yr−1. Forest fire was identified as the major source of the biomass burning emissions, and crop residue burning was the second highest contributor. In the 15-year study period, emissions from forest fires showed a significant downward trend. Crop residue emissions continued to rise until 2014, and then began to decline. Emissions from grassland and shrubland were little changed. Forest, grassland, and shrubland fires are mostly located in regions with high vegetation coverage, where the occurrence of fires is concentrated in arid seasons (spring and autumn). Plain areas with high crop yields, such as the North China Plain, experienced high agricultural fire emissions in harvest seasons. The resolution (daily, 1 km) of our inventory is much higher than previous inventories, such as GFED4s and GFASv1.0. It could be used in global and regional air quality modeling.

The research of the dynamical flow behavior of gas-liquid two-phase flow remains a challenge of great importance. We first carry out the vertical upward gas-liquid two-phase flow experiment in a 50 mm inner-diameter pipe and capture flow information via four-sector distributed conductance sensor. Then, we develop multilayer limited penetrable visibility graph (MLPVG) to analyze multichannel measurements, aiming to characterize the complicated flow behavior. We calculate two projection networks of MLPVG from two different perspectives (i.e. the overlapping information and the whole information). The ratio between the global clustering coefficients of these two projection networks is calculated as a quantitative indicator to characterize the multilayer network. We find that the proposed multilayer network measure can effectively characterize the evolution of gas-liquid flow, from randomly dispersed bubbles to periodically arisen gas slugs. The results suggest that our method can effectively fuse multichannel measurements and reveal the evolution of the complicated flow behavior.

Ammonia (NH3) can interact in the atmosphere with other trace chemical species, which can lead to detrimental environmental consequences, such as the formation of fine particulates and ultimately global climate change. China is a major agricultural country, and livestock numbers and nitrogen fertilizer use have increased drastically since 1978, following the rapid economic and industrial development experienced by the country. In this study, comprehensive NH3 emissions inventories were compiled for China for 1980–2012. In a previous study, we parameterized emissions factors (EFs) considering ambient temperature, soil acidity, and the method and rate of fertilizer application. In this study, we refined these EFs by adding the effects of wind speed and new data from field experiments of NH3 flux in cropland in northern China. We found that total NH3 emissions in China increased from 5.9 to 11.1 Tg from 1980 to 1996, and then decreased to 9.7 Tg in 2012. The two major contributors were livestock manure and synthetic fertilizer application, which contributed 80–90 % of the total emissions. Emissions from livestock manure rose from 2.86 Tg (1980) to 6.16 Tg (2005), and then decreased to 5.0 Tg (2012); beef cattle were the largest source followed by laying hens and pigs. The remarkable downward trend in livestock emissions that occurred in 2007 was attributed to a decrease in the numbers of various livestock animals, including beef cattle, goats, and sheep. Meanwhile, emissions from synthetic fertilizer ranged from 2.1 Tg (1980) to 4.7 Tg (1996), and then declined to 2.8 Tg (2012). Urea and ammonium bicarbonate (ABC) dominated this category of emissions, and a decline in ABC application led to the decrease in emissions that took place from the mid-1990s onwards. High emissions were concentrated in eastern and southwestern China. Seasonally, peak NH3 emissions occurred in spring and summer. The inventories had a monthly temporal resolution and a spatial resolution of 1000 m, and thus are suitable for global and regional air-quality modeling.

Thermal circulations induced by urbanization could exert important effects on regional ozone (O 3 ) formation through regulating the chemical transformations and transport of O 3 and its precursors. In this study, the Weather Research and Forecasting/Chemistry (WRF/Chem) model combined with remote sensing are used to investigate the impacts of urbanization-induced circulations on O 3 formation in the Pearl River Delta (PRD) region, China. The urban heat island (UHI) effect in PRD significantly enhances turbulent mixing and modifies local circulations, i.e., initiates the UHI circulation and strengthens the sea breeze, which in turn cause a detectable decrease of daytime O 3 concentration (−1.3 ppb) and an increase of O 3 (+5.2 ppb) around the nocturnal rush-hours. The suppressed O 3 titration destruction due to NOx dilution into the deeper urban boundary layer (200–400 m) is the main reason for elevated nocturnal O 3 levels. In the daytime, however, the upward transport of O 3 precursors weakens near-surface O 3 photochemical production and conversely enhances upper-level O 3 generation. Furthermore, the surface UHI convergence flow and intensified sea breeze act to effectively trap O 3 at the suburban and coastal regions.

Characterizing nonlinear dynamic behaviors underlying multiphase flow has attracted considerable attention from the nonlinear research field. In this paper, the authors develop a novel multiple entropy-based multilayer network (MEMN) for exploring the complex gas-liquid two-phase flow. At first, we carry out the gas-liquid flow experiments to get the multichannel measurements. Then, MEMN is constructed based on the fusion of three nonlinear entropies, namely weighted permutation entropy (WPE), wavelet packet energy entropy (WPEE), and amplitude entropy (AE). For each derived projection network of MEMN, spectral radius and global clustering coefficient are both calculated and they allow effectively uncovering the nonlinear flow behaviors in the transition of different gas-liquid flow patterns. In addition, we perform wavelet time-frequency representation for the two typical flow patterns and the results support our findings well. All these demonstrate that our MEMN framework can effectively characterize the nonlinear evolution of gas-liquid flow from the perspective of complex network theory. And this also provides a novel idea for studying nonlinear complex systems from the observed multivariate time series.

Inflammatory bowel disease (IBD) is a chronic autoimmune disease with a high recurrence rate. Ulcerative colitis (UC) and Crohn's disease (CD) are two types of IBD. At present, parasite-derived cysteine protease inhibitors have received extensive attention from researchers, and experiments have confirmed that these protease have an effect on certain autoimmune diseases. So we conducted experiments to investigate the effect of Trichinella spiralis cysteine protease inhibitors on TNBS-induced mouse CD models. In this experiment, 72 male BALB/c mice aged 6–8 weeks were randomly divided into two groups: prevention group and therapy group. The mice were sacrificed and harvested on the 7th day after the model was established to measure the changes of various indicators of colitis. The comparison of the TsCystatin + TNBS group with the PBS + TNBS group showed that the DAI score, MPO activity, and colonic macroscopic and microscopic damage significantly reduced, IFN-γ significantly decreased, IL-4 expression increased, and NF-κB expression decreased. The percentage of CD4+CD25+Foxp3+ Treg and CD8+CD28− Treg in spleen, and the proportion of CD4+/CD8+ Treg cells decreased. In the therapy group, we found no significant difference between the TNBS+PBS group and TNBS + TsCystatin group. Treatment with TsCystatin exerted a good intervention effect on the TNBS-induced mouse CD model. TsCystatin possibly induced a Th2-type immune response in the body, which balanced the Th1-type immune response induced by TNBS administration, thereby relieving colitis.

Although nitrogen oxide (NOx) emission controls have been implemented for several years in northern China, recent observations show particulate nitrate (NO3−) is becoming increasingly important during haze episodes. In this study, we find that particulate NO3− formation would easily become NH3-limited under severe haze conditions, enhancing its sensitivity to NH3 emission controls. Furthermore, improved manure management of livestock husbandry could reduce 40 % of NH3 emissions (currently 100 kiloton per a month) in winter of northern China. Under this emission reductions scenario, simulations from the thermodynamic equilibrium model (ISORROPIA-II) and the Weather Research and Forecast model coupled chemistry (WRF-Chem) all show that particulate NO3− could be reduced by approximately 40 % during a typical severe haze episode (averagely from 40.8 to 25.7 μg/m3). Our results indicate that reducing livestock NH3 emissions would be highly effective to reduce particulate NO3− during severe winter haze events.

An adaptive frame rate imager suitable for integration in a wireless IoT device is developed. Fine-grained power management working with adaptive frame functionality reduces power consumption proportional to the frame rate. An analog processing chain employing telescopic OTA with a common mode shift technique is developed to achieve a low power design while maintaining 9-bit accuracy noise and settling error. The OTA operates in a time-sharing DDR regime that halves the power consumption. A hierarchical column multiplexer and variable capacitance buffer are introduced to minimize the capacitive load of the OTA. The imager consumes 1.51 mW in 15-fps mode, reducing power by 33% compared with the maximum frame rate of 51 fps. A 372×316, 5-µm pixel array, readout circuit, ADC, and LDO are fully integrated into a 2.86 mm × 2.58 mm chip to reduce the dimensions of an image acquisition system.

Summary Inflammatory bowel disease (IBD), which includes ulcerative colitis and Crohn's disease (CD), is a chronic autoimmune disease. Parasitic infections and their products have been shown to have protective effects on autoimmune diseases, including IBD. In this experiment, 96 male BALB/c mice aged 6–8 weeks were divided randomly into two large groups: prevention and therapy. The changes in the various indicators of colitis were detected to demonstrate that Trichinella spiralis serine protease inhibitors can relieve the inflammatory severity of 2,4,6-trinitrobenzenesulphonic acid solution (TNBS)-induced colitis and to explore possible immunological mechanisms. Results showed that the disease activity index (DAI) score, myeloperoxidase (MPO) activity, macroscopic and microscopic damage degrees of colon all decreased significantly, interferon (IFN)-γ expression decreased, interleukin (IL)-4 expression increased, nuclear factor kappa B (NF)-κB expression decreased and the percentage of CD4+CD25+forkhead box protein 3 (FoxP3+) regulatory T cells (Treg) cells in the spleen. MLN increased significantly compared to the phosphate-buffered saline (PBS)/2,4,6-trinitrobenzenesulphonic acid solution (TNB) group. We found the same results with the T. spiralis Kazal-type serine protease inhibitors (TsKaSPI)+TNBS and TsAdSPI+TNBS groups in the large prevention group and the large therapy group, compared to the TNBS+PBS group with the TNBS+TsKaSPI and TNBS+TsAdSPI groups. Immunization with TsKaSPI and TsAdSPI on the CD models showed an intervention effect, possibly because TsKaSPI and TsAdSPI induced a T helper type 2 (Th2)-type immune response and balanced the TNBS-induced Th1-type immune response.

A novel sesquiterpenoid, roseosporol A (

Satellite retrievals of vertical column densities (VCDs) of tropospheric nitrogen dioxide (NO2) normally do not explicitly account for aerosol optical effects and surface reflectance anisotropy that vary with space and time. Here, we conduct an improved retrieval of NO2 VCDs over China, called the POMINO algorithm, based on measurements from the Ozone Monitoring Instrument (OMI), and we test the importance of a number of aerosol and surface reflectance treatments in this algorithm. POMINO uses a parallelized LIDORT-driven AMFv6 package to derive tropospheric air mass factors via pixel-specific radiative transfer calculations with no look-up tables, taking slant column densities from DOMINO v2. Prerequisite cloud optical properties are derived from a dedicated cloud retrieval process that is fully consistent with the main NO2 retrieval. Aerosol optical properties are taken from GEOS-Chem simulations constrained by MODIS aerosol optical depth (AOD) data. MODIS bi-directional reflectance distribution function (BRDF) data are used for surface reflectance over land. For the present analysis, POMINO level-2 data for 2012 are aggregated into monthly means on a 0.25° long. × 0.25° lat. grid. POMINO-retrieved annual mean NO2 VCDs vary from 15–25 × 1015 cm−2 over the polluted North China Plain (NCP) to below 1015 cm−2 over much of western China. Using POMINO to infer Chinese emissions of nitrogen oxides leads to annual anthropogenic emissions of 9.05 TgN yr−1, an increase from 2006 (Lin, 2012) by about 19 %. Replacing the MODIS BRDF data with the OMLER v1 monthly climatological albedo data affects NO2 VCDs by up to 40 % for certain locations and seasons. The effect on constrained NOx emissions is small. Excluding aerosol information from the retrieval process (this is the traditional "implicit" treatment) enhances annual mean NO2 VCDs by 15–40 % over much of eastern China. Seasonally, NO2 VCDs are reduced by 10–20 % over parts of the NCP in spring and over northern China in winter, despite the general enhancements in summer and fall. The effect on subsequently constrained annual emissions is between −5 and +30 % with large seasonal and spatial dependence. The implicit aerosol treatment also tends to exclude days with high pollution, since aerosols are interpreted as effective clouds and the respective OMI pixels are often excluded by cloud screening; this is a potentially important sampling bias. Therefore an explicit treatment of aerosols is important for space-based NO2 retrievals and emission constraints. A comprehensive independent measurement network with sufficient spatial and temporal representativeness is needed to further evaluate the different satellite retrieval approaches.