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Reliable short-term wind-power forecasting is crucial for the safe operation of power systems that accommodate large amount of wind power. With the development of large-scale wind power bases, wind power spatiotemporal correlations of multiple wind farms (WFs) can be used to improve short-term wind power prediction accuracy and efficiency. However, the time-varying and coupling characteristics of wind power spatiotemporal correlations present significant challenges for the accurate prediction of multi-WF power. In this paper, we propose an adaptive spatiotemporal fusion graph neural network for short-term power forecasting of multiple wind farms. Based on regional weather forecasts and historical wind power data, an adaptive directed graph is generated to model the dynamic spatial correlations between the WFs and the impact of regional weather factors on the wind power of different WFs. Graph convolution modules and temporal recursive modules are then alternately arranged to fuse the spatial and temporal features of wind power and to output the wind power prediction results for multiple WFs and time points. The case study results show that the proposed model outperforms the investigated baseline models in terms of prediction accuracy and that each model component has a unique contribution.

Atmospheric oxidizing capacity (AOC) is an essential driving force of troposphere chemistry and self-cleaning, but the definition of AOC and its quantitative representation remain uncertain. Driven by national demand for air pollution control in recent years, Chinese scholars have carried out studies on theories of atmospheric chemistry and have made considerable progress in AOC research. This paper will give a brief review of these developments. First, AOC indexes were established that represent apparent atmospheric oxidizing ability (AOIe) and potential atmospheric oxidizing ability (AOIp) based on aspects of macrothermodynamics and microdynamics, respectively. A closed study refined the quantitative contributions of heterogeneous chemistry to AOC in Beijing, and these AOC methods were further applied in Beijing-Tianjin-Hebei and key areas across the country. In addition, the detection of ground or vertical profiles for atmospheric OH·, HO

We introduce a new efficient framework, the Unified Context Network (UniCon), for robust active speaker detection (ASD). Traditional methods for ASD usually operate on each candidate's pre-cropped face track separately and do not sufficiently consider the relationships among the candidates. This potentially limits performance, especially in challenging scenarios with low-resolution faces, multiple candidates, etc. Our solution is a novel, unified framework that focuses on jointly modeling multiple types of contextual information: spatial context to indicate the position and scale of each candidate's face, relational context to capture the visual relationships among the candidates and contrast audio-visual affinities with each other, and temporal context to aggregate long-term information and smooth out local uncertainties. Based on such information, our model optimizes all candidates in a unified process for robust and reliable ASD. A thorough ablation study is performed on several challenging ASD benchmarks under different settings. In particular, our method outperforms the state-of-the-art by a large margin of about 15% mean Average Precision (mAP) absolute on two challenging subsets: one with three candidate speakers, and the other with faces smaller than 64 pixels. Together, our UniCon achieves 92.0% mAP on the AVA-ActiveSpeaker validation set, surpassing 90% for the first time on this challenging dataset at the time of submission. Project website: https://unicon-asd.github.io/., Comment: 10 pages, 6 figures; to appear at ACM Multimedia 2021

The atmospheric oxidizing capacity (AOC), reflecting the self-cleansing capacity of the atmosphere, plays an important role in the chemical evolution of secondary fine particulate matter (PM

Time-of-flight measurements are key to study distributed mode coupling and differential mode group delay (DMDG) in multimode fibers (MMFs). However, current approaches using regular photodetectors with limited sensitivity preclude the detection of weak modal interactions in such fibers masking interesting physical effects. Here we demonstrate the use of high-sensitivity superconducting nanowire single-photon detectors (SNSPDs) to measure the mode transfer matrix of a commercial graded-index multimode fiber. Two high performance 45-mode multi-plane light conversion (MPLC) devices served as the mode multiplexer/demultiplexer. Distributed mode coupling and DMDG among different mode groups are accurately quantified from the impulse response measurement. We also observed cladding modes of the MMF as a pedestal of the pulse in the measurement. This work paves way for applications such as quantum communications using many spatial modes of the fiber., 10 pages, journal paper

The coastal eco-city of Fuzhou in Southeastern China has experienced severe ozone (O

A comprehensive understanding of the effects of meteorology, emission and chemistry on severe haze is critical in the mitigation of air pollution. However, such understanding is largely hindered by the nonlinearity of atmospheric chemistry systems. Here, we developed a novel quantitative decoupling analysis (QDA) method to quantify the effects of emission, meteorology, chemical reaction, and their nonlinear interactions on the fine particulate matter (PM2.5) pollution based on the accompanying simulations for different atmospheric processes. Via embedding the QDA method into the Weather Research and Forecasting-Nested Air Quality Prediction Modeling System (WRF-NAQPMS) model, we first employed this method into a typical heavy haze episode in Beijing. Different from the previously sensitive simulation method, which usually linked to a certain period, the QDA achieves the fully decomposing analysis of PM2.5 concentration during any pollution event into seven different parts, including meteorological contribution (M), emission contribution (E), chemical contribution (C), and interactions among these drivers (i.e., ME, MC, EC and MCE). The results show that the meteorology contribution varied significantly at different stages of episode, from 0.21 µg·m−3·h−1 during accumulation period to −11.82 µg·m−3·h−1 during the removal period, dominating the hourly changes of PM2.5 concentrations. The chemical contributions were shown to increase with the level of haze, which become largest (0.37 µg·m−3·h−1) at the maintenance period, 25 % higher than that during the clean period. The contribution of primary emission is relatively stable in all stages due to the use of fixed emission during the simulation. Besides, the QDA method highlights that there exist nonnegligible coupling effects of meteorology, emission and chemistry on PM2.5 concentrations (−1.83 to 2.44 µg·m−3·h−1), which were commonly ignored in previous studies and the development of heavy-pollution control strategies. These results indicate that the QDA method can not only provide researchers and policy makers with valuable information for understanding of key factors to heavy pollution, but also help the modelers to find out the sources of uncertainties among numerical models.

Atmospheric particles are important reaction vessels for multiphase chemistry. We conducted a meta-analysis of previous field observations in various environments (includes ocean, urban and rural regions), showing that particle hygroscopicity inhomogeneity (PHI) is ubiquitous for the continental atmospheric particles, in which a considerable part of the particulate matters is hydrophobic (10%–33% on average). However, the effects of PHI in quantifying the uptake process of reactive gases are still unclear. Here, taking N2O5 uptake as an example, we showed that using a laboratory-based parameterization scheme without considering the PHI might result in a misestimation of uptake rate coefficient, especially under low ambient relative humidity (RH). Such misestimation may be caused by the differences of the uptake coefficients, as well as the proportion of surface area concentration (SA) between hydrophilic and hydrophobic particles. We suggested that the PHI should be well-considered in establishing the reactive traces gases heterogeneous uptake parameterizations.

Formaldehyde (HCHO) can possibly be taken by atmospheric particles due to its moderate solubility. Although previous model studies have proposed that uptake by particles was a large sink for HCHO, direct observation of HCHO partitioning and estimation of HCHO uptake coefficient (γ) for tropospheric conditions are still limited. In this work, online measurements of gaseous HCHO (HCHO

Ozone (O

From 2013 to 2017, with the implementation of the toughest-ever clean air policy in China, significant declines in fine particle (PM 2.5 ) concentrations occurred nationwide. Here we estimate the drivers of the improved PM 2.5 air quality and the associated health benefits in China from 2013 to 2017 based on a measure-specific integrated evaluation approach, which combines a bottom-up emission inventory, a chemical transport model, and epidemiological exposure-response functions. The estimated national population–weighted annual mean PM 2.5 concentrations decreased from 61.8 (95%CI: 53.3–70.0) to 42.0 µg/m 3 (95% CI: 35.7–48.6) in 5 y, with dominant contributions from anthropogenic emission abatements. Although interannual meteorological variations could significantly alter PM 2.5 concentrations, the corresponding effects on the 5-y trends were relatively small. The measure-by-measure evaluation indicated that strengthening industrial emission standards (power plants and emission-intensive industrial sectors), upgrades on industrial boilers, phasing out outdated industrial capacities, and promoting clean fuels in the residential sector were major effective measures in reducing PM 2.5 pollution and health burdens. These measures were estimated to contribute to 6.6- (95% CI: 5.9–7.1), 4.4- (95% CI: 3.8–4.9), 2.8- (95% CI: 2.5–3.0), and 2.2- (95% CI: 2.0–2.5) µg/m 3 declines in the national PM 2.5 concentration in 2017, respectively, and further reduced PM 2.5 -attributable excess deaths by 0.37 million (95% CI: 0.35–0.39), or 92% of the total avoided deaths. Our study confirms the effectiveness of China’s recent clean air actions, and the measure-by-measure evaluation provides insights into future clean air policy making in China and in other developing and polluting countries.

A field campaign was conducted from November to December 2017 at the campus of Peking University (PKU) to investigate the formation mechanism of the winter air pollution in Beijing with the measurement of hydroxyl and hydroperoxyl radical (OH and HO2) with the support from comprehensive observation of trace gases compounds. The extent of air pollution depends on meteorological conditions. The daily maximum OH radical concentrations are on average 2.0 × 106 cm−3 and 1.5 × 106 cm−3 during the clean and polluted episodes, respectively. The daily maximum HO2 radical concentrations are on average 0.4 × 108 cm−3 and 0.3 × 108 cm−3 during the clean and polluted episodes, respectively (diurnal averaged for one hour bin). A box model based on RACM2-LIM1 mechanism can reproduce the OH concentrations but underestimate the HO2 concentrations by 50% during the clean episode. The OH and HO2 concentrations are underestimated by 50% and 12 folds during the polluted episode, respectively. Strong dependence on nitric oxide (NO) concentration is found for both observed and modeled HO2 concentrations, with the modeled HO2 decreasing more rapidly than observed HO2, leading to severe HO2 underestimation at higher NO concentrations. The OH reactivity is calculated from measured and modeled species and inorganic compounds (carbon monoxide (CO), NO, and nitrogen dioxide (NO2)) make up 69%–76% of the calculated OH reactivity. The photochemical oxidation rate denoted by the OH loss rate increases by 3 times from the clean to polluted episodes, indicating the strong oxidation capacity in polluted conditions. The comparison between measurements at PKU site and a suburban site from one previous study shows that chemical conditions are similar in both urban and suburban areas. Hence, the strong oxidation capacity and its potential contribution to the pollution bursts are relatively homogeneous over the whole Beijing city and its surrounding areas.

A severe haze episode occurred in winter in the North China Plain (NCP), and the phenomenon of an explosive growth and sharp decline in PM2.5 (particulate matter with an aerodynamic diameter equal to or less than 2.5 μm) concentration was observed. To study the systematic causes for this phenomenon, comprehensive observations were conducted in Beijing from November 26 to December 2, 2015; during this period, meteorological parameters, LIDAR data, and the chemical compositions of aerosols were determined. The haze episode was characterized by rapidly varying PM2.5 concentration, and the highest PM2.5 concentration reached 667 μg/m3. During the haze episode, the NCP was dominated by a weak high-pressure system and continuously low PBL (planetary boundary layer) heights, which are unfavorable conditions for the diffusion of pollutants. The large increases in the concentrations of SNA (SO42−, NO3− and NH4+) during the haze implied that the formation of SNA was the largest contribution. Water vapor also played a vital role in the formation of haze by promoting the chemical transformation of secondary pollutants, which led to higher PM2.5 concentrations. The spatial distributions of PM2.5 in Beijing at different times and the backward trajectories of the air masses also indicated that pollutants from surrounding provinces in particular, contributed to the higher PM2.5 concentration.

Accurate determination of the atmospheric particulate matter mass concentration and chemical composition is helpful in exploring the causes and sources of atmospheric enthalpy pollution and in evaluating the rationality of environmental air quality control strategies. Based on the sampling and chemical composition data of PM2.5 in different key regions of China in the CARE-China observation network, this research analyzes the environmental air quality data released by the China National Environmental Monitoring Centre during the studied period to determine the changes in the particulate matter mass concentration in key regions and the evolution of the corresponding chemical compositions during the implementation of the Action Plan for Prevention and Control of Air Pollution from 2013–2017. The results show the following. (1) The particulate matter mass concentration in China showed a significant downward trend; however, the PM2.5 annual mass concentration in 64% of cities exceeds the New Chinese Ambient Air Quality Standard (CAAQS) Grade II (GB3095-2012). The region to the east of the Taihang Mountains, the Fenhe and Weihe River Plain and the Urumqi-Changji regions in Xinjiang, all have PM2.5 concentration loading that is still high, and heavy haze pollution occurred frequently in the autumn and winter. (2) During the heavy pollution in the autumn and winter, the concentrations of sulfate and organic components decreased significantly. The mean $${\rm{SO}}_4^{2-}$$ concentration in PM2.5 decreased by 76%, 12%, 81% and 38% in Beijing-Tianjin-Hebei (BTH), the Pearl River Delta (PRD), the Sichuan-Chongqing region (SC) and the Fenhe and Weihe River Plain, respectively. The mean organic matter (OM) concentration decreased by 70%, 44%, 48% and 31%, respectively, and the mean concentration of $${\rm{NH}}_4^+$$ decreased by 68%, 1.6%, 38% and 25%, respectively. The mean elemental carbon (EC) concentration decreased by 84% and 20% in BTH and SC, respectively, and it increased by 61% and 11% in the PRD and Fenhe and Weihe River Plain, respectively. The mean concentration of mineral and unresolved chemical components (MI) dropped by 70%, 24% and 13% in BTH, the PRD and the Fenhe and Weihe River Plain, respectively. The change in the PM2.5 chemical composition is consistent with the decrease of the PM2.5 mass concentration. (3) In 2015, the mean OM concentration contributions to fine particles and coarse particles were 13–46% and 46–57%, respectively, and the mean MI concentration contributions to fine particles and coarse and particles were 31–60% and 39–73%, respectively; these values are lower than the 2013 values from the key regions, which is the most important factor behind the decrease of the particulate matter mass concentration. From 2013 to 2015, among the chemical components of different particle size fractions, the peak value of the coarse particle size fraction decreased significantly, and the fine particle size fractions of $${\rm{SO}}_4^{2-},{\rm{NO}}_4^-,\;{\rm{and}}\;{\rm{NH}}_4^+$$ decreased with the decrease of the particulate matter mass concentration in different particle size fractions. The fine-particle size peaks of $${\rm{SO}}_4^{2-},{\rm{NO}}_4^-,\;{\rm{and}}\;{\rm{NH}}_4^+$$ shifted from 0.65–1.1 μm to the finer size range of 0.43–0.65 μm during the same time frame.

A system based on incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) has been developed for simultaneous measurement of nitrogen dioxide (NO2), glyoxal (GLY), and methylglyoxal (MGLY). In this system, the measured light absorption at around 460 nm is spectrally resolved. The concentration of absorbers is determined from a multicomponent fit. At an integration time of 100 s, the measurement sensitivity (2σ) for NO2, GLY, and MGLY is 18, 30, and 100 ppt, respectively. The measurement uncertainty, which mainly originates from path length calibration, sampling loss, and uncertainty of absorption cross sections is estimated to be 8 % for NO2, 8 % for GLY, and 16 % for MGLY. When deploying the instrument during field observations, we found significant influence of NO2 on the spectra fitting for retrieving GLY and MGLY concentrations, which is caused by the fact that NO2 has a higher absorption cross section and higher ambient concentration. In order to minimize such an effect, a NO2 photolytic convertor (NPC), which removes sampled NO2 at an efficiency of 76 %, was integrated on the IBBCEAS system. Since sampled GLY and MGLY are mostly (≥95 %) conserved after passing through the NPC, the quality of the spectra fitting and the measurement accuracy of ambient GLY and MGLY under NO2-rich environments could be improved.

In contrast to summer smog, the contribution of photochemistry to the formation of winter haze in northern mid-to-high latitude is generally assumed to be minor due to reduced solar UV and water vapor concentrations. Our comprehensive observations of atmospheric radicals and relevant parameters during several haze events in winter 2016 Beijing, however, reveal surprisingly high hydroxyl radical oxidation rates up to 15 ppbv/h, which is comparable to the high values reported in summer photochemical smog and is two to three times larger than those determined in previous observations during winter in Birmingham (Heard et al.

A 1 × 2 integrated four-mode power splitter based on multimode interference is proposed and experimentally demonstrated for the first time. A three-dimensional simulation is used to optimize the core/cladding refractive index difference and the input waveguide position for the TE00, TE01, TE10, and TE11 input waveguide modes. Minimum insertion loss (IL) and mode-dependent loss (MDL) of 0.1 and 0.2 dB are predicted, respectively. IL and MDL less than 1 dB can be maintained over a bandwidth of approximately 50 and 25 nm, respectively. The device was fabricated on SiO2 and experimentally characterized. The variation of the power splitting ratio for each mode is less than 0.4 dB over the full C-band, and the excess losses of the splitter for all four modes exceed the IL of a straight waveguide by less than 1.85 dB.

The recent paper by Shen et al. (2018) (referred to hereafter as SHEN) made a sweeping statement on the winter haze pollution in Beijing by claiming “Insignificant effect of climate change on winter haze in Beijing”. We argue that the paper contains three serious flaws. Either one of the three flaws can nullify the claim of SHEN.

The problem of synthesizing array patterns while reducing dynamic range ratio (DRR) of complex excitations is of great importance in practical applications since it enables active arrays to be more attractive by appropriately controlling the mutual coupling between the neighboring elements, as well as reducing the cost and complexity of the feeding network design. Unlike the commonly adopted DRR control technique, this paper focuses on minimizing the DRR of the excitations while synthesizing the anticipated array pattern, which results in a new nonconvex and nonlinear optimization problem because of its fractional objective function and nonconvex constraints. By introducing auxiliary variables, we derive an equivalent optimization problem that transforms the fractional objective function into a linear one, decompose the original optimization problem into several subproblems in each iteration, and simplify them as either single-variable quadratic unconstrained optimization or least-squares problems that are solved efficiently in each iteration. Numerical results with different radiation requirements are shown to demonstrate the effectiveness of the proposed scheme.

Numerous epidemiologic studies on adverse health effects of air pollution have been well documented; however, assessment on health benefits of air quality improvement from air pollution control measures has been limited in developing countries.We assessed the mortality benefits associated with air pollution improvement over 11 years in Guangzhou, China (2006–2016).A time series analysis with Generalized additive Poisson models was used to estimate mortality effects of ozone (O3) and nitrogen dioxide (NO2), adjusting for time trend, day of week, public holiday, temperature and relative humidity. We further estimated the changes in mortality burden of O3 and NO2, including attributable fraction (AF, in %) and attributable mortality (AM, in number of death) during study period. We lastly estimated mortality effects during the 2010 Asian Games (November 12 to December 18, 2010) compared to a baseline period consisting of 4-week before and 4-week after the game.During the study period, average annual concentrations of NO2 decreased from 42.3 μg/m3 in 2006 to 33.8 μg/m3 in 2016; while O3 levels remained stable over time. We observed significant increases in mortality of O3 and NO2, with approximately linear exposure-response relationships. In specific, each increase of 10 μg/m3 in O3 and NO2 at 2 prior days was associated with increases of 0.60% (95% confidence interval (CI): 0.47, 0.74) and 1.89% (95%CI: 1.49, 2.29) in total mortality, respectively. We further estimated that AF on total mortality attributed to NO2 decreased from 1.38% (95%CI: 1.09, 1.68) in 2006–2010 to 0.43% (95%CI: 0.34, 0.52) in 2011–2016, corresponding to AM on total mortality of 2496 deaths (95%CI: 1964, 3033) to 1073 deaths (95%CI: 846, 1301). During the 2010 Asian Games, we observed decrease in total mortality of 9.3% (95%CI: −15.0, −3.2) in comparison with that observed in the baseline period. Similar mortality benefits in cardiovascular diseases were also observed.Our results showed reduced mortality burden from air pollution improvement in Guangzhou in recent years, which provide strong rationale for continuing to reduce air pollution through comprehensive and rigorous air quality management in the area. Keywords: Air quality improvement, Mortality burden, Health benefit, Asian games, Time-series analysis

SUMMARY Cell death is a fundamental aspect of development, homeostasis, and disease; yet, our understanding of non-apoptotic forms of cell death is limited. One such form is phagoptosis, in which one cell utilizes phagocytosis machinery to kill another cell that would otherwise continue living. We have previously identified a non-autonomous requirement of phagocytosis machinery for the developmental programmed cell death of germline nurse cells in the Drosophila ovary; however, the precise mechanism of death remained elusive. Here, we show that lysosomal machinery acting in epithelial follicle cells is used to non-autonomously induce the death of nearby germline cells. Stretch follicle cells recruit V-ATPases and chloride channels to their plasma membrane to extracellularly acidify the germline and release cathepsins that destroy the nurse cells. Our results reveal a role for lysosomal machinery acting at the plasma membrane to cause the death of neighboring cells, providing insight into mechanisms driving non-autonomous cell death., Graphical Abstract, In Brief Mondragon et al. show that V-ATPase proton pumps localize to the plasma membrane of follicle cells and promote extracellular acidification to eliminate adjacent nurse cells in the Drosophila ovary. The follicle cells subsequently release cathepsins by exocytosis into the nurse cells to promote their final degradation.

Volatile organic compounds (VOCs) have an important influence on the formation of photochemical smog and secondary organic aerosols in the atmosphere. In this paper, we investigated 104 VOCs in Heshan from 22 October to 22 November 2014 to identify the sources and abatement mechanisms of VOCs in southern China. Weather conditions, species correlations, daytime and nighttime abatement mechanisms, secondary pollutant transformations, air-mass origins and source apportionments were studied. During the observation period, the average concentration of VOCs in the atmosphere of Heshan was 61.0 ± 35.5 ppbv, and the wind speed played a pivotal role in the diffusion and dilution of VOCs. The study on the rates of OH, O3 and NO3 radicals found that alkenes, aromatics, hydrocarbons and carbonyl compounds were the most active volatile organic compounds in Heshan. For alkanes, alkynes, and aromatics, removal is determined by their reactions with OH radicals. For highly reactive alkenes and styrene, nighttime removal via O3 and NO3 radicals was also significant. The backward-trajectory cluster analysis of air masses indicated that pollution mainly derived from the east-northeast. The paint solvent usage, paint solvent usage + liquefied petroleum gas (LPG) usage, biomass burning, coal burning + industrial combustion sources, gasoline vehicle exhaust, diesel vehicle exhaust, industrial sources, and fuel evaporation (gasoline) contributed 11%, 22%, 13%, 17%, 12%, 8%, 11%, and 6% to VOCs during the observation period, respectively.

As nitrous acid (HONO) photolysis is an important source of hydroxyl radical (OH), apportionment of the ambient HONO sources is necessary to better understand atmospheric oxidation. Based on the data HONO-related species and various parameters measured during the one-month campaign at Wangdu (a rural site in North China plain) in summer 2014, a box model was adopted with input of current literature parametrizations for various HONO sources (nitrogen dioxide heterogeneous conversion, photoenhanced conversion, photolysis of adsorbed nitric acid and particulate nitrate, acid displacement, and soil emission) to reveal the relative importance of each source at the rural site. The simulation results reproduced the observed HONO production rates during noontime in general but with large uncertainty from both the production and destruction terms. NO2 photoenhanced conversion and photolysis of particulate nitrate were found to be the two major mechanisms with large potential of HONO formation but the associated uncertainty may reduce their importance to be nearly negligible. Soil nitrite was found to be an important HONO source during fertilization periods, accounted for (80 ± 6)% of simulation HONO during noontime. For some episodes of the biomass burning, only the NO2 heterogeneous conversion to HONO was promoted significantly. In summary, the study of the HONO budget is still far from closed, which would require a significant effort on both the accurate measurement of HONO and the determination of related kinetic parameters for its production pathways.

Although biogenic aerosols play important roles in atmospheric processes and climate change, their contributions to atmospheric particulate matter mass have not received much attention, partly due to the difficulty in identifying key aerosol components and due to the often dominant role of anthropogenic emissions. In order to estimate contributions of biogenic and biomass burning organic aerosols to atmospheric particles, fine particulate matter (PM2.5) samples were collected simultaneously at an urban and a rural site in the North China Plain (NCP), a region with extensive anthropogenic emissions, during summer 2014. Saccharides, including anhydrosugars, monosaccharides, and sugar alcohols, were quantified. Profiles of saccharides in PM2.5 collected at urban and rural sites during the daytime and nighttime, nearby biomass burning, and without significant influence of biomass burning were investigated and compared. Contributions of biomass burning, biogenic aerosol associated with primary biological aerosol particles, and isoprene-derived secondary organic carbon (SOC) to total organic carbon were then estimated based on source-specific saccharide tracers. The results showed that concentrations of nearly all saccharides were higher at the rural site than at the urban site. Levoglucosan was the most abundant saccharide, followed by glycerol and glucose. Mass concentrations of source specific tracers and associated source contribution estimates indicated that the absolute and relative contributions of biomass burning were both much higher compared to fungal spore derived OC and isoprene SOC, with greater contributions observed at the rural site especially during nighttime. Our findings reveal that biogenic and biomass burning sources are non-negligible summertime contributors to atmospheric PM2.5 OC mass both at the rural site (up to 50%) and at the urban site (~20%) in the NCP.

Here we report the spectral-timing results of the black hole X-ray binary 4U 1630–47 during its 2021 outburst using observations from the Hard X-ray Modulation Telescope (Insight-HXMT). Type C quasi-periodic oscillations (QPOs) in ∼1.6–4.2 Hz and quasi-regular modulation (QRM) near 60 mHz are detected during the outburst. The mHz QRM has a fractional rms of ∼10%–16% in the 8–35 keV energy band with a Q factor (frequency/width) of ∼2–4. Benefiting from the broad energy band of Insight-HXMT, we study the energy dependence of the ∼60 mHz QRM in 1–100 keV for the first time. We find that the fractional rms of the mHz QRM increases with photon energy, while the time lags of the mHz QRM are soft and decrease with photon energy. Fast recurrence of the mHz QRM, in a timescale of less than 1 hr, has been observed during the outburst. During this period, the corresponding energy spectra moderately change when the source transitions from the QRM state to the non-QRM state. The QRM phenomenon also shows a dependence with the accretion rate. We suggest that the QRM could be caused by an unknown accretion instability aroused from the corona.

Volatile organic compounds (VOCs) play an important role in air pollution. In this study, we conducted comprehensive field observations to investigate wintertime air pollution in Beijing, Wangdu, and Dezhou in the Beijing-Tianjin-Hebei region during 2017 and 2018. The average VOC concentrations of the three sites were 35.6 ± 26.6, 70.9 ± 56.3, and 50.5 ± 40.0 ppbv, respectively. The species with the highest concentration were similar in all three sites and included ethane, ethylene, acetylene, acetone, and toluene. The VOC mixing ratios of the three sites showed synchronous growth during pollution episodes and were 1.2-2 times higher than those during clean periods. Moreover, the OH loss rates (LOH) during pollution episodes were 1.2-1.7 times that during clean periods. The crucial reactive species in the three sites were ethylene, propylene, and acetaldehyde, contributing approximately 70% to the total LOH during pollution periods. According to the source apportionment analysis, vehicle exhausts were the largest source of VOCs in Beijing, accounting for more than 50% of the total emissions. During the pollution episodes, Beijing's industrial emissions decreased, but the secondary and background sources increased. Coal combustion was significant (approximately 40%) in Wangdu and should therefore be prioritized in emission reduction policies. In Dezhou, industrial emissions had a considerable impact on the VOC mixing ratio during pollution periods and should therefore be prioritized. The backward trajectory analysis showed that VOCs from the southern region likely contribute to Beijing's VOC pollution, highlighting the importance of regional integration for air quality management.

The continuous phase plate (CPP) is the vital diffractive optical element involved in laser beam shaping and smoothing in high-power laser systems. The high gradients, small spatial periods, and complex features make it difficult to achieve high accuracy when manufacturing such systems. A high-accuracy and high-efficiency surface topography manufacturing method for CPP is presented in this paper. The atmospheric pressure plasma jet (APPJ) system is presented and the removal characteristics are studied to obtain the optimal processing parameters. An optimized iterative algorithm based on the dwell point matrix and a fast Fourier transform (FFT) is proposed to improve the accuracy and efficiency in the dwell time calculation process. A 120 mm × 120 mm CPP surface topography with a 1326.2 nm peak-to-valley (PV) value is fabricated with four iteration steps after approximately 1.6 h of plasma processing. The residual figure error between the prescribed surface topography and plasma-processed surface topography is 28.08 nm root mean square (RMS). The far-field distribution characteristic of the plasma-fabricated surface is analyzed, for which the energy radius deviation is 11 μm at 90% encircled energy. The experimental results demonstrates the potential of the APPJ approach for the manufacturing of complex surface topographies.

Sulfate is one of the main components of the haze particles and the formation mechanism remains controversial. Lacking of detailed and comprehensive field data hindes the accurate evaluation of relative roles of prevailing sulphate formation pathways. Here, we analyzed the sulfate production rates using a state-of-art multiphase model constrained to the observed concentrations of transition metal ions (TMI), nitrogen dioxide, ozone, hydrogen peroxide, and other important parameters in winter and summer in the North China Plain. Our results showed that aqueous TMI-catalyzed oxidation was the most important pathway followed by the surface oxidation of Mn in both winter and summer, while the hydroxyl and criegee radicals oxidations contribute significantly in summer. In addition, we also modeled the published cases for the fog and cloud conditions. It is found that nitrogen dioxide oxidation is the dominant pathway for the fog in a higher pH range while hydroperoxide and ozone oxidations dominated for the cloud.

Nitrate (NO3) radical is an important oxidant in the atmosphere as it regulates the NOx budget and impacts secondary pollutant formation. Here, a long-term observational dataset of NO3-related species at an urban site in Beijing was used to investigate changes in the NO3 budget and their atmospheric impacts during 2013–2019, in this period the Clean Air Actions Plan was carried out in China. We found that (1) changes in NO3 precursors (NO2 and O3) led to a significant increase in NO3 formation in the surface layer in winter but a decrease in summer; (2) a reduction in NOx promoted thermal equilibrium, favoring the formation of NO3 rather than dinitrogen pentoxide (N2O5). The simultaneous decrease in PM2.5, during these years, further weakened the N2O5 heterogeneous uptake; (3) a box model simulation revealed that both the reactions of NO3 with volatile organic compounds (VOC) and N2O5 uptake were weakened in summer, implying that the policy actions implemented help to moderate secondary aerosol formation caused by NO3 and N2O5 chemistry in summer; and (4) during winter, both NO3 + VOC and N2O5 uptake were enhanced. Specifically, for the N2O5 uptake, the rapid increase in NO3 production, or to some extent, NO3 oxidation capacity, far outweighed the negative shift effect, leading to a net enhancement of N2O5 uptake in winter, which indicates that the action policy implemented led to an adverse effect on particulate nitrate formation via N2O5 uptake in winter. This may explain the persistent winter particulate nitrate pollution in recent years. Our results highlight the systematic changes in the NO3 budget between 2013 and 2019 in Beijing, which subsequently affect secondary aerosol formation in different seasons.

The Pearl River Delta (PRD) region in South China is faced with severe ambient tropospheric ozone (O 3 ) pollution in autumn and summer, which mostly coincides with the occurrence of typhoons above the Northwest Pacific. With increasingly severe O 3 pollution in the PRD under the influence of typhoons, it is necessary to gain a comprehensive understanding of the impact of typhoons on O 3 transport, production and accumulation for efficient O 3 reduction. In this study, we analysed the general influence of typhoons on O 3 pollution in the PRD via systematic comparisons of meteorological conditions, O 3 processes and sources on O 3 pollution days with and without typhoon occurrence (denoted as the typhoon-induced and no-typhoon scenarios, respectively) and also examined the differences in these influences in autumn and summer. The results show that the approach of typhoons was accompanied by higher wind speeds and strengthened downdraughts in autumn, as well as the inflows of more polluted air masses in summer, suggesting favourable O 3 transport conditions in the typhoon-induced scenario in both seasons. However, the effect of typhoons on the production and accumulation of O 3 were distinct. Typhoons led to reduced cloud cover, and thus stronger solar radiation in autumn, which accelerated O 3 production, but the shorter residence time of local air masses was unfavourable for the accumulation of O 3 within the PRD. In contrast, in summer, typhoons increased cloud cover, and weakened solar radiation, thus restraining O 3 formation, but the growing residence time of local air masses favoured O 3 accumulation. The modelling results using the Community Multiscale Air Quality (CMAQ) model for the typical O 3 pollution days suggest increasing contributions from the transport processes and sources outside the PRD for O 3 pollution, confirming enhanced O 3 transport under typhoon influence in both seasons. The results of the process analysis in CMAQ suggest that the chemical process contributed more in autumn but less in summer in the PRD. Since O 3 production and accumulation cannot be enhanced at the same time, the proportion of O 3 contributed by emissions within the PRD was likely to decrease in both seasons. The difference in the typhoon influence on O 3 processes in autumn and summer can be attributed to the seasonal variation of the East Asian monsoon. From the meteorology–process–source perspective, this study revealed the complex influence of typhoons on O 3 pollution in the PRD and their seasonal differences. To alleviate O 3 pollution under typhoon influence, emission control is needed on a larger scale, rather than only within the PRD.

Tropospheric O3 pollution notably contributes to the deterioration of air quality in many metropolitan regions, resulting in detrimental effects on human health and ecosystem. Due to the moderate atmospheric lifetimes of O3, horizontal transport, exchange between atmospheric boundary layer (ABL) and free troposphere (FT), and chemical process within the ABL all potentially play important roles in regional O3 pollution. In this study, we developed a post-calculation tool to quantify the hourly contributions of these processes to the regional budget of O3 mass and concentration variations within the ABL based on the modelling results of the Community Multiscale Air Quality (CMAQ) model. The new features of this tool include: (1) the contributions of ABL-FT exchange on O3 pollution can be quantified; (2) horizontally, the targeted region can be freely defined by users and vertically, the volumes are non-fixed owing to the diurnal variations of ABL; and (3) the budgets of O3 mass and concentration variations are separately calculated and analysed. The Pearl River Delta (PRD) region, located in the South China and faced with severe O3 pollution, was selected as the target region in this study. Results show that the variations of total O3 mass within the ABL of the PRD were controlled by ABL-FT exchange, that is, the increase (decrease) of O3 mass in the morning (afternoon) was driven by O3 inflow (outflow) through ABL-FT exchange. By contrast, it was the chemical process that drove the variations of regional-mean O3 concentrations. Except that ABL-FT exchange contributed to the rise of O3 concentrations in several hours after sunrise, O3 transport did not lead to the notable variation of O3 concentration in the remaining hours of the day. Combining source apportionment methods, we found that outside O3 (including O3 produced by emissions within the East and Central China and background O3) entered the PRD mainly through ABL-FT exchange. For chemical process, local sources played a major part, but the contributions of outside emissions cannot be neglected, suggesting the contributions of precursor transport. The effects of typhoon periphery, the weather system most related to O3 pollution in the PRD, were also examined by comparing the budget results on O3 pollution days with and without the occurrence of typhoons. The usage of this tool will help to comprehensively understand the influence of transport and chemical process in O3 pollution on the regional scale, which is crucial for effective and strategic O3 control. Acknowledgement. This work is sponsored by the National Key Research and Development Program of China (Grant No. 2018YFC0213204, 2018YFC0213506) and the National Science and Technology Pillar Program of China (Grant No. 2014BAC21B01).

In recent decade the ambient fine particle (PM

We present a comprehensive field campaign conducted in Beijing, September 2016, to elucidate the photochemical smog pollution, i.e. Ozone (O3). The observed daily maximum hydroxyl radical (OH) and hydroperoxy radical (HO2) concentrations were up to 1 × 107 cm-3 and 6 × 108 cm-3, respectively, indicating the active photochemistry in autumn Beijing. Photolysis of nitrous acid (HONO) and O3 contributed 1-2 ppbv h-1 to OH primary production during daytime. OH termination were dominated by the reaction with nitric oxide (NO) and nitrogen dioxide (NO2), which were in general larger than primary production rates, indicating other primary radical sources maybe important. The measurement of radicals facilitates the direct determination of local ozone production rate P (Ox) (Ox = O3 + NO2). The integrated P(Ox) reached 75 ppbv in afternoon (for 4 h) when planetary boundary layer was well developed. At the same time period, the observed total oxidant concentrations Ox, increased significantly by 70 ppbv. In addition, the Ox measurement showed compact increase in 12 stations both temporally and spatially in Beijing, indicating that active photochemical production happened homogenously throughout the city. The back-trajectory analysis showed that Beijing was isolated from the other cities during the episode, which further proved that the fast ozone pollution was contributed by local photochemical production rather than regional advection.

The tumor microenvironment is a complex ecosystem formed by distinct and interacting cell populations, and its composition is related to cancer prognosis and response to clinical treatment. In this study, we have taken the advantage of two single‐cell RNA sequencing technologies (Smart‐seq2 and DNBelab C4) to generate an atlas of 15,115 immune and nonimmune cells from primary tumors and hepatic metastases of 18 colorectal cancer (CRC) patients. We observed extensive changes in the proportions and functional states of T cells and B cells in tumor tissues, compared to those of paired non‐tumor tissues. Importantly, we found that B cells from early CRC tumor were identified to be pre‐B like expressing tumor suppressors, whereas B cells from advanced CRC tumors tended to be developed into plasma cells. We also identified the association of IgA+IGLC2+ plasma cells with poor CRC prognosis, and demonstrated a significant interaction between B‐cell and myeloid‐cell signaling, and found CCL8 + cycling B cells/CCR5+ T‐cell interactions as a potential antitumoral mechanism in advanced CRC tumors. Our results provide deeper insights into the immune infiltration within CRC, and a new perspective for the future research in immunotherapies for CRC., Integrated single‐cell RNA sequencing technologies reveal a high‐resolution immune landscape of colorectal primary tumors and liver metastasis, identifying major immune cell types and distinct cell functional states of T and B cells as well as predictions of complex cell‐cell interactions.

Intensive agricultural activities in the North China Plain (NCP) lead to substantial emissions of nitrogen oxides (NOx) from soil, while the role of this source on local severe ozone pollution is unknown. Here we use a mechanistic parameterization of soil NOx emissions combined with two atmospheric chemistry models to investigate the issue. We find that the presence of soil NOx emissions in the NCP significantly reduces the sensitivity of ozone to anthropogenic emissions. The maximum ozone air quality improvements in July 2017, as can be achieved by controlling all domestic anthropogenic emissions of air pollutants, decrease by 30% due to the presence of soil NOx. This effect causes an emission control penalty such that large additional emission reductions are required to achieve ozone regulation targets. As NOx emissions from fuel combustion are being controlled, the soil emission penalty would become increasingly prominent and shall be considered in emission control strategies., Summertime ozone air pollution in North China remains severe. Here the authors find large biogenic emissions of nitrogen oxides in North China, mainly driven by fertilizer application, challenge the mitigation of ozone pollution by only reducing combustion induced ozone precursors’ emissions.