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The measurement of high-pressure sound velocity in solid materials is crucial for developing constitutive equations and equations of state for materials in extreme stress–strain rate conditions. In this study, we propose a novel method for high-pressure sound velocity measurement using laser-induced micro-flyer technology. By optimizing laser driving conditions and target structure design, we measure high-pressure sound velocity using the “reverse-impact geometry” approach. The well-established Photon Doppler Velocimetry system allows for high-precision, single-shot measurements of both flyer velocity and particle velocity histories. A systematic error analysis shows that the longitudinal sound velocity of aluminum obtained in this experiment is consistent with data from traditional devices, such as gas guns, within the error margin. Finally, we analyze the potential application value of this method in laser technology as well as high-pressure dynamic responses of materials, and conclude the current shortcomings and possible improvements of this method.

The climate of the Tibetan Plateau (TP) has experienced substantial changes in recent decades as a result of the location's susceptibility to global climate change. The changes observed across the TP are closely associated with regional land–atmosphere interactions. Current models and satellites struggle to accurately depict the interactions; therefore, critical field observations on land–atmosphere interactions outlined here provide necessary independent validation data and fine-scale process insights for constraining reanalysis products, remote sensing retrievals, and land surface model parameterizations. Scientific data sharing is crucial for the TP since in situ observations are rarely available under these harsh conditions. However, field observations are currently dispersed among individuals or groups and have not yet been integrated for comprehensive analysis. This has prevented a better understanding of the interactions, the unprecedented changes they generate, and the substantial ecological and environmental consequences they bring about. In this study, we collaborated with different agencies and organizations to present a comprehensive dataset for hourly measurements of surface energy balance components, soil hydrothermal properties, and near-surface micrometeorological conditions spanning up to 17 years (2005–2021). This dataset, derived from 12 field stations covering a variety of typical TP landscapes, provides the most extensive in situ observation data available for studying land–atmosphere interactions on the TP to date in terms of both spatial coverage and duration. Three categories of observations are provided in this dataset: meteorological gradient data (met), soil hydrothermal data (soil), and turbulent flux data (flux). To assure data quality, a set of rigorous data-processing and quality control procedures are implemented for all observation elements (e.g., wind speed and direction at different height) in this dataset. The operational workflow and procedures are individually tailored to the varied types of elements at each station, including automated error screening, manual inspection, diagnostic checking, adjustments, and quality flagging. The hourly raw data series; the quality-assured data; and supplementary information, including data integrity and the percentage of correct data on a monthly scale, are provided via the National Tibetan Plateau Data Center (https://doi.org/10.11888/Atmos.tpdc.300977, Ma et al., 2023a). With the greatest number of stations covered, the fullest collection of meteorological elements, and the longest duration of observations and recordings to date, this dataset is the most extensive hourly land–atmosphere interaction observation dataset for the TP. It will serve as the benchmark for evaluating and refining land surface models, reanalysis products, and remote sensing retrievals, as well as for characterizing fine-scale land–atmosphere interaction processes of the TP and underlying influence mechanisms.

Solid solution effect of minor elements on mechanical and especially thermal properties of zirconium (Zr) alloys has been underexplored in previous studies. This research delves into the electronic structure, phonon, mechanics, and thermodynamics of binary solid solution Zr alloys (introduction of Sn, Cu, Al, Ge, O, N, H, and C) using density functional theory (DFT). Micro-mechanical properties are changed after doping elements, particularly for doping H as interstitials. The H-induced increase in Poisson's ratio and decrease in shear modulus, Young's modulus, and hardness should be due to H-induced enhancement in the ductility of adjacent Zr atoms. Addition-induced thermodynamic properties are discernible for substitutional and interstitial elements. High frequencies of phonons appear in the Zr alloys with interstitial solid solution, which decreases the heat capacity of the Zr alloys. Conversely, the alloys featuring a substitutional solid solution experience negligible changes in heat capacity. Grüneisen parameter associated with anharmonic interaction is a determining factor in the thermal expansion of the Zr alloys. In low phonon frequencies (≤2 THz), the more negative contribution of Grüneisen parameter leads to the lower thermal expansion of the Zr alloys with interstitial solid solution, with respect to substitutional solid solution. Deep investigation reveals that the mode of lattice vibration in the low frequency almost remains the original transverse mode of the pure Zr for interstitial solid solution. For substitutional solid solution, the atomic layer containing doping element vibrates from transversely to longitudinally. Our work helps purposefully tune the properties of novel Zr alloys through screening and adding alloying elements.

The occurrence of jadarite (LiNaSiB3O7OH) as a major ore mineral in the world-class lithium–boron deposit of the Miocene Jadar lacustrine basin (western Serbia) raises interesting questions about its formation conditions and potential associations for lithium mineralization in other sedimentary basins. This contribution reports on the first successful synthesis of jadarite in the Li2O–Na2O–B2O3–SiO2–NaCl–H2O system at temperatures from 180 to 230 ∘C and pH values from 6 to 12. Synthetic jadarite has been characterized by powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, laser Raman spectroscopy, and synchrotron Li and B K-edge X-ray absorption near-edge structure (XANES). First-principles theoretical calculations reproduce the measured FTIR and Raman spectra and allow definitive assignments of vibration modes. Similarly, the measured Li and B K-edge XANES spectra are reasonably reproduced by first-principles theoretical calculations. Our synthesis results, together with its association with searlesite in the Jadar basin, suggest jadarite forms in deep sediments derived from Li-rich alkaline brines under high-temperature diagenetic conditions.

A lightning location system consisting of multiple ground-based stations is an effective means of lightning observation. The dataset from CNLDN (China National Lightning Detection Network) in 2016–2022 is employed to analyze the temporal and spatial lightning distributions and the differences between +CG (positive cloud-to-ground lightning) and −CG (negative cloud-to-ground lightning) strokes in China. On the annual scale, lightning activity is most prevalent during the summer months (June, July, and August), accounting for 72.6 % of the year. Spring sees more lightning than autumn, and winter has only a small amount in southeastern coastal areas. During the day, the frequency of lightning peaks at 15:00–17:00 CST (China standard time) and is lowest at 8:00–10:00 CST. For the period with high CG stroke frequency (summer of a year or afternoon of a day), the proportion of +CG strokes and the discharge peak current are relatively small. Winter in a year and morning or midnight in a day correspond to a greater +CG stroke proportion and discharge current. Spatially, low latitudes, undulating terrain, the seaside, and humid surfaces are favorable factors for lightning occurrence. Thus, the southeast coastland has the largest lightning stroke density, while the northwest deserts and basins and the western and northern Tibetan Plateau, with altitudes over 6000 m, have almost no lightning. The proportion of +CG strokes and the peak current are low in the southern region with high density but diverse in other regions. The Tibetan Plateau causes the diversity of lightning activity in China and lays the foundation for studying the impact of surface elevation on lightning. Results indicate that the +CG stroke proportion on the eastern and southern Tibetan Plateau is up to 15 %, larger than the plain regions. The peak current of −CG strokes is positively correlated with altitude, but +CG strokes show a negative correlation, resulting in a large difference in peak current between +CG and −CG on the plain and a small difference on the plateau.

Anthropogenic water regulation activities, including reservoir interception, surface water withdrawal, and groundwater extraction, alter riverine hydrologic processes and affect dissolved organic carbon (DOC) export from land to rivers and oceans. In this study, schemes describing soil DOC leaching, riverine DOC transport, and anthropogenic water regulation were developed and incorporated into the Community Land Model 5.0 (CLM5.0) and the River Transport Model (RTM). Three simulations by the developed model were conducted on a global scale from 1981–2013 to investigate the impacts of anthropogenic water regulation on riverine DOC transport. The validation results showed that DOC exports simulated by the developed model were in good agreement with global river observations. The simulations showed that DOC transport in most rivers was mainly influenced by reservoir interception and surface water withdrawal, especially in central North America and eastern China. Four major rivers, including the Danube, Yangtze, Mississippi, and Ganges rivers, have experienced reduced riverine DOC flows due to intense water management, with the largest effect occurring in winter and early spring. In the Danube and Yangtze river basins, the impact in 2013 was 4 to 5 times greater than in 1981, with a retention efficiency of over 50 %. The Ob river basin was almost unaffected. The total impact of anthropogenic water regulation reduced global annual riverine DOC exports to the ocean by approximately 13.36 ± 2.45 Tg C yr−1, and this effect increased from 4.83 % to 6.20 % during 1981–2013, particularly in the Pacific and Atlantic oceans.

Abstract The Pixel Luminosity Telescope is a silicon pixel detector dedicated to luminosity measurement at the CMS experiment at the LHC. It is located approximately 1.75 m from the interaction point and arranged into 16 “telescopes”, with eight telescopes installed around the beam pipe at either end of the detector and each telescope composed of three individual silicon sensor planes. The per-bunch instantaneous luminosity is measured by counting events where all three planes in the telescope register a hit, using a special readout at the full LHC bunch-crossing rate of 40 MHz. The full pixel information is read out at a lower rate and can be used to determine calibrations, corrections, and systematic uncertainties for the online and offline measurements. This paper details the commissioning, operational history, and performance of the detector during Run 2 (2015–18) of the LHC, as well as preparations for Run 3, which will begin in 2022.

Even when successfully induced, immunological tolerance to solid organs remains vulnerable to inflammatory insults, which can trigger rejection. In a mouse model of cardiac allograft tolerance in which infection with Listeria monocytogenes (Lm) precipitates rejection of previously accepted grafts, we showed that recipient CD4+ TCR75 cells reactive to a donor MHC class I–derived peptide become hypofunctional if the allograft is accepted for more than 3 weeks. Paradoxically, infection-induced transplant rejection was not associated with transcriptional or functional reinvigoration of TCR75 cells. We hypothesized that there is heterogeneity in the level of dysfunction of different allospecific T cells, depending on duration of their cognate antigen expression. Unlike CD4+ TCR75 cells, CD4+ TEa cells specific for a peptide derived from donor MHC class II, an alloantigen whose expression declines after transplantation but remains inducible in settings of inflammation, retained function in tolerant mice and expanded during Lm-induced rejection. Repeated injections of alloantigens drove hypofunction in TEa cells and rendered grafts resistant to Lm-dependent rejection. Our results uncover a functional heterogeneity in allospecific T cells of distinct specificities after tolerance induction and reveal a strategy to defunctionalize a greater repertoire of allospecific T cells, thereby mitigating a critical vulnerability of tolerance.

The hygroscopic growth of atmospheric aerosols plays an important role in regional radiation, cloud formation, and hence climate. Aerosol hygroscopic growth is often characterized by hygroscopic tandem differential mobility analyzers (HTDMAs), and Xie et al. (2020) recently demonstrated that hygroscopic growth measurements of a single particle are possible using a surface plasmon resonance microscope-azimuthal rotation illumination (SPRM-ARI). The hygroscopic properties of ambient aerosols are not uniform and often exhibit large relative humidity (RH) and size variabilities due to different chemical compositions and mixing states. To better understand the contribution of different aerosol components and establish a link between the apparent hygroscopic properties of single particles and bulk aerosols, we conduct combined hygroscopic growth measurements using a SPRM-ARI and an HTDMA as a case study to prove the concept (experimental information: 100–200 nm, during noontime on 28 September 2021 and 22 March 2022 in Hefei, China). According to the distinct hygroscopic growth behavior from single-particle probing using a SPRM-ARI, the individual particles can be classified into three categories defined as non-hygroscopic (NH), less hygroscopic (LH), and more hygroscopic (MH). The mean growth factor (GF) of the three categories can be utilized to reproduce the GF distribution obtained from the HTDMA measurement. The chemical compositions of individual particles from the three categories are identified to be organic carbon (OC), soot (mainly elemental carbon), fly ash, and secondary aerosols (mainly OC and sulfate), using scanning electron microscopy (SEM) with an energy-dispersive spectrometer (EDS). The coupled SPRM–HTDMA measurement suggests a size-dependent variation of aerosol chemical components, i.e., an increase of OC fraction with increasing particle sizes, which agrees reasonably well with the chemical compositions from collected aerosol samples. This likely links the hygroscopic properties of individual particles to their bulk hygroscopic growth and chemical composition.

Preceding a core-collapse supernova (CCSN), various processes produce an increasing amount of neutrinos of all flavors characterized by mounting energies from the interior of massive stars. Among them, the electron antineutrinos are potentially detectable by terrestrial neutrino experiments such as KamLAND and Super-Kamiokande (SK) via inverse beta decay interactions. Once these pre-supernova (pre-SN) neutrinos are observed, an early warning of the upcoming CCSN can be provided. In light of this, KamLAND and SK, both located in the Kamioka mine in Japan, have been monitoring pre-SN neutrinos since 2015 and 2021, respectively. Recently, we performed a joint study between KamLAND and SK on pre-SN neutrino detection. A pre-SN alert system combining the KamLAND detector and the SK detector was developed and put into operation, which can provide a supernova alert to the astrophysics community. Fully leveraging the complementary properties of these two detectors, the combined alert is expected to resolve a pre-SN neutrino signal from a 15 M _⊙ star within 510 pc of the Earth at a significance level corresponding to a false alarm rate of no more than 1 per century. For a Betelgeuse-like model with optimistic parameters, it can provide early warnings up to 12 hr in advance.

Among multimessenger observations of the next Galactic core-collapse supernova, Super-Kamiokande (SK) plays a critical role in detecting the emitted supernova neutrinos, determining the direction to the supernova (SN), and notifying the astronomical community of these observations in advance of the optical signal. In 2022, SK has increased the gadolinium dissolved in its water target (SK-Gd) and has achieved a Gd concentration of 0.033%, resulting in enhanced neutron detection capability, which in turn enables more accurate determination of the supernova direction. Accordingly, SK-Gd’s real-time supernova monitoring system has been upgraded. SK_SN Notice, a warning system that works together with this monitoring system, was released on 2021 December 13, and is available through GCN Notices. When the monitoring system detects an SN-like burst of events, SK_SN Notice will automatically distribute an alarm with the reconstructed direction to the supernova candidate within a few minutes. In this paper, we present a systematic study of SK-Gd’s response to a simulated Galactic SN. Assuming a supernova situated at 10 kpc, neutrino fluxes from six supernova models are used to characterize SK-Gd’s pointing accuracy using the same tools as the online monitoring system. The pointing accuracy is found to vary from 3° to 7° depending on the models. However, if the supernova is closer than 10 kpc, SK_SN Notice can issue an alarm with three-degree accuracy, which will benefit follow-up observations by optical telescopes with large fields of view.

Photovoltaic (PV) technology, an efficient solution for mitigating the impacts of climate change, has been increasingly used across the world to replace fossil fuel power to minimize greenhouse gas emissions. With the world's highest cumulative and fastest built PV capacity, China needs to assess the environmental and social impacts of these established PV power plants. However, a comprehensive map regarding the PV power plants' locations and extent remains scarce on the country scale. This study developed a workflow, combining machine learning and visual interpretation methods with big satellite data, to map PV power plants across China. We applied a pixel-based random forest (RF) model to classify the PV power plants from composite images in 2020 with a 30 m spatial resolution on the Google Earth Engine (GEE). The resulting classification map was further improved by a visual interpretation approach. Eventually, we established a map of PV power plants in China by 2020, covering a total area of 2917 km2. We found that most PV power plants were situated on cropland, followed by barren land and grassland, based on the derived national PV map. In addition, the installation of PV power plants has generally decreased the vegetation cover. This new dataset is expected to be conducive to policy management, environmental assessment, and further classification of PV power plants. The dataset of photovoltaic power plant distribution in China by 2020 is available to the public at https://doi.org/10.5281/zenodo.6849477 (Zhang et al., 2022).

Abstract Objectives To compare the short-term outcomes of unilateral biportal endoscopic lumbar interbody fusion (BLIF) and uniportal endoscopic lumbar interbody fusion (ULIF). Methods Sixty patients diagnosed with L4/5 spinal stenosis who underwent BLIF and ULIF were included (30 in each group). Clinical evaluation was performed preoperatively and postoperatively in the 1st week, 1st month, and 1st year. Factors such as the visual analogue score (VAS), Oswestry Disability Index (ODI), operative time, surgical complications, and radiological outcomes (fusion rate, screw loosening, and cage subsidence) were compared between the two groups. Results All patients showed improved mean VAS and ODI at all three postoperative follow-ups, and no statistically significant differences were detected between the BLIF and ULIF groups. The mean operative time in the BLIF group was shorter than that in the ULIF group. Nerve root injury occurred in two patients in the BLIF group, while leakage of cerebrospinal fluid occurred in one patient in the ULIF group. All adverse events were treated adequately prior to discharge. The fusion rates with definite and probable grades were significantly higher in the BLIF group than that in the ULIF group. One case of cage subsidence with no screw loosening occurred in each group. Conclusion Both BLIF and ULIF are safe and effective surgical techniques. Compared with ULIF, BLIF has the advantages of shorter operative time and a higher fusion rate. Other merits of BLIF include a wider surgical field, greater maneuverability of instruments, visibility during cage implantation, and transverse orientation of the cage.

Robot ultrasound has great potential for reducing the workload of a sonographer, improving the access to nursing care, producing more accurate imaging, and avoiding direct contact with patients. However, in the process of ultrasonic scanning, the traditional manual control scheme of the ultrasonic machine cannot simultaneously consider the problems of instantaneous contact force overshoot and steady-state force-tracking error, which is very important to improve image quality and ensure patient safety. In this paper, we proposed a varying rate adaptive hybrid position–impedance control strategy, which is used for the ultrasonic robot operator to scan the abdomen transversely. In order to ensure the stability of ultrasonic robot in the position subspace with parameter uncertainty and external interference, an adaptive inverse position controller is designed. In the scanning process of force subspace, a variable adaptive impedance control scheme is carefully designed to avoid force overshoot and keep the accuracy of the force tracking. Different from the classical impedance realization, the dynamic update rate is to update the impedance characteristics through force sensor feedback, reduce overshoot, and keep the stability and accuracy of the robot system during the task. Through the comparative study of different adaptive control schemes, the effectiveness of the proposed variable rate adaptive impedance control strategy was discussed. The proposed control scheme was verified in the virtual robot experimental environment, V-rep. Simulation and experimental results show that the proposed variable rate adaptive position impedance hybrid control scheme is more promising and efficient in robot-assisted ultrasound imaging.

We introduce a newly developed global ice sheet model coupled to the Globally Resolved Energy Balance (GREB) climate model for the simulation of global ice sheet evolution on timescales of 100 kyr or longer (GREB-ISM v1.0). Ice sheets and ice shelves are simulated on a global grid, fully interacting with the climate simulation of surface temperature, precipitation, albedo, land–sea mask, topography and sea level. Thus, it is a fully coupled atmosphere, ocean, land and ice sheet model. We test the model in ice sheet stand-alone and fully coupled simulations. The ice sheet model dynamics behave similarly to other hybrid SIA (shallow ice approximation) and SSA (shallow shelf approximation) models, but the West Antarctic Ice Sheet accumulates too much ice using present-day boundary conditions. The coupled model simulations produce global equilibrium ice sheet volumes and calving rates like those observed for present-day boundary conditions. We designed a series of idealized experiments driven by oscillating solar radiation forcing on periods of 20, 50 and 100 kyr in the Northern Hemisphere. These simulations show clear interactions between the climate system and ice sheets, resulting in slow buildup and fast decay of ice-covered areas and global ice volume. The results also show that Northern Hemisphere ice sheets respond more strongly to timescales longer than 100 kyr. The coupling to the atmosphere and sea level leads to climate interactions between the Northern and Southern Hemispheres. The model can run global simulations of 100 kyr d−1 on a desktop computer, allowing the simulation of the whole Quaternary period (2.6 Myr) within 1 month.

Located in the mountainous area of southwest China, the Chengdu–Chongqing urban agglomeration (CCUA) has been rapidly urbanized in the last 4 decades, which has led to a 3-fold urban area expansion, thereby affecting the weather and climate. To investigate the urbanization effects on the thermal environment in the CCUA under complex terrain, we conducted simulations using the advanced Weather Research and Forecasting (WRF V4.1.5) model together with combined land use scenarios and terrain conditions. We observed that the WRF model reproduces the general synoptic summer weather pattern, particularly for the thermal environment. It was shown that the expansion of the urban area changed the underlying surface's thermal properties, leading to the urban heat island effect, enhanced further by the complex terrain. The simulation with the future scenario shows that the implementation of idealized measures including returning farmland to forests and expanding rivers and lakes can reduce the urban heat island effect and regulate the urban ecosystem. Therefore, urban planning policy has the potential to provide feasible suggestions to best manage the thermal environment of the future city toward improving the livelihood of the people in the environment.

Aim: We developed the Patient-Engaged Health Technology Assessment strategy for survey-based goal collection from patients to yield patient-important outcomes suitable for use in multi-criteria decision analysis. Methods: Rheumatoid arthritis patients were recruited from online patient networks for proofof- concept testing of goal collection and prioritization using a survey. A Project Steering Committee and Expert Panel rated the feasibility of scaling to larger samples. Results: Survey respondents (n = 47) completed the goal collection exercise. Finding effective treatments was rated by respondents as the most important goal, and reducing stiffness was rated as the least important. Feedback from our steering committee and expert panel support the approach’s feasibility for goal identification and ranking. Conclusion: Goals relevant for treatment evaluation can be identified and rated for importance by patients to permit wide input from patients with lived experience of disease.

We report the first search result for the flux of astrophysical electron antineutrinos for energies ${ \mathcal O }(10)\,\mathrm{MeV}$ in the gadolinium-loaded Super-Kamiokande (SK) detector. In 2020 June, gadolinium was introduced to the ultrapure water of the SK detector in order to detect neutrons more efficiently. In this new experimental phase, SK-Gd, we can search for electron antineutrinos via inverse beta decay with efficient background rejection thanks to the high efficiency of the neutron tagging technique. In this paper, we report the result for the initial stage of SK-Gd, during 2020 August 26, and 2022 June 1 with a 22.5 × 552 kton · day exposure at 0.01% Gd mass concentration. No significant excess over the expected background in the observed events is found for the neutrino energies below 31.3 MeV. Thus, the flux upper limits are placed at the 90% confidence level. The limits and sensitivities are already comparable with the previous SK result with pure water (22.5 × 2970 kton · day) owing to the enhanced neutron tagging. Operation with Gd increased to 0.03% started in 2022 June.

BackgroundThe lateral intersecting margin (dog-ear) was a weak spot of the double stapled technique (DST), We designed “dog-ear” invagination anastomosis (DAIA), which could eliminate the “dog-ear” in laparoscopic anterior resection.Patients and methodsA total of 202 patients underwent elective curative LLAR + DST (n = 143) or LLAR + DAIA (n = 59) were enrolled in the study. Propensity score matching (PSM) was used to minimize the adverse effects. The clinical data between LLAR + DST and LLAR + DAIA was compared, and the effect of factors on overall survival (OS) and disease-free survival (DFS) was analyzed.ResultsAfter PSM, 53 pairs of the LLRA + DST and LLRA + DAIA patients were enrolled in the study. The LLRA + DAIA group has a higher level (3.50 ± 1.03 vs. 2.87 ± 1.10, P = 0.01) of the anastomosis than that of the LLRA + DST group. Patients in LLAR + DAIA group have a lower incidence of protecting loop ileostomy compared to LLAR + DST group (20.75% vs. 5.66%, P 0.05).ConclusionLaparoscopic low anterior resection with “dog-ear” invagination anastomosis technique are well-established procedures for patients with low rectal cancer. “Dog-ear” invagination anastomosis technique may reduce the incidence of protecting loop ileostomy and significantly affect LARS score, and demonstrate a positive impact on the quality of life after surgery.

Recent increases in atmospheric carbon dioxide (CO2) and temperature relieve their limitations on terrestrial ecosystem productivity, while nutrient availability constrains the increasing plant photosynthesis more intensively. Nitrogen (N) and phosphorus (P) are critical for plant physiological activities and consequently regulate ecosystem productivity. Here, for the first time, we mapped N and P densities and concentrations of leaves, woody stems, roots, litter, and soil in forest, shrubland, and grassland ecosystems across China based on an intensive investigation at 4868 sites, covering species composition, biomass, and nutrient concentrations of different tissues of living plants, litter, and soil. Forest, shrubland, and grassland ecosystems in China stored 6803.6 Tg N, with 6635.2 Tg N (97.5 %) fixed in soil (to a depth of 1 m) and 27.7 (0.4 %), 57.8 (0.8 %), 71.2 (1 %), and 11.7 Tg N (0.2 %) in leaves, stems, roots, and litter, respectively. The forest, shrubland, and grassland ecosystems in China stored 2806.0 Tg P, with 2786.1 Tg P (99.3 %) fixed in soil (to a depth of 1 m) and 2.7 (0.1 %), 9.4 (0.3 %), 6.7 (0.2 %), and 1.0 Tg P (< 0.1 %) in leaves, stems, roots, and litter, respectively. Our estimation showed that N pools were low in northern China, except in the Changbai Mountains, Mount Tianshan, and Mount Alta, while relatively higher values existed in the eastern Qinghai–Tibetan Plateau and Yunnan. P densities in vegetation were higher towards the southern and north-eastern part of China, while soil P density was higher towards the northern and western part of China. The estimated N and P density and concentration datasets, “Patterns of nitrogen and phosphorus pools in terrestrial ecosystems in China” (https://doi.org/10.5061/dryad.6hdr7sqzx), are available from the Dryad digital repository (Zhang et al., 2021). These patterns of N and P densities could potentially improve existing earth system models and large-scale research on ecosystem nutrients.

Abstract The measurement of the luminosity recorded by the CMS detector installed at LHC interaction point 5, using proton–proton collisions at $$\sqrt{s}=13\,{\text {TeV}} $$ s = 13 TeV in 2015 and 2016, is reported. The absolute luminosity scale is measured for individual bunch crossings using beam-separation scans (the van der Meer method), with a relative precision of 1.3 and 1.0% in 2015 and 2016, respectively. The dominant sources of uncertainty are related to residual differences between the measured beam positions and the ones provided by the operational settings of the LHC magnets, the factorizability of the proton bunch spatial density functions in the coordinates transverse to the beam direction, and the modeling of the effect of electromagnetic interactions among protons in the colliding bunches. When applying the van der Meer calibration to the entire run periods, the integrated luminosities when CMS was fully operational are 2.27 and 36.3 $$\,\text {fb}^{-1}$$ fb - 1 in 2015 and 2016, with a relative precision of 1.6 and 1.2%, respectively. These are among the most precise luminosity measurements at bunched-beam hadron colliders.

Blowing snow processes are crucial in shaping the strongly heterogeneous spatiotemporal distribution of snow and in regulating subsequent snowpack evolution in mountainous terrain. Although empirical formulae and constant threshold wind speeds have been widely used to estimate the occurrence of blowing snow in regions with sparse observations, the scarcity of in situ observations in mountainous regions contrasts with the demands of models for reliable observations at high spatiotemporal resolution. Therefore, these methods struggle to accurately capture the high local variability of blowing snow. This study investigated the potential capability of the decision tree model (DTM) to detect blowing snow in the European Alps. The DTMs were constructed based on routine meteorological observations (mean wind speed, maximum wind speed, air temperature and relative humidity) and snow measurements (including in situ snow depth observations and satellite-derived products). Twenty repetitions of a random sub-sampling validation test with an optimal size ratio (0.8) between the training and validation subsets were applied to train and assess the DTMs. Results show that the maximum wind speed contributes most to the classification accuracy, and the inclusion of more predictor variables improves the overall accuracy. However, the spatiotemporal transferability of the DTM might be limited if the divergent distribution of wind speed exists between stations. Although both the site-specific DTMs and site-independent DTM show great ability in detecting blowing snow occurrence and are superior to commonly used empirical parameterizations, specific assessment indicators varied between stations and surface conditions. Events for which blowing snow and snowfall occurred simultaneously were detected the most reliably. Although models failed to fully reproduce the high frequency of local blowing snow events, they have been demonstrated to be a promising approach requiring limited meteorological variables and have the potential to scale to multiple stations across different regions.

Urban irrigation and road sprinkling are methods for mitigating high urban temperatures which are expected to enhance evapotranspiration and affect the urban weather, climate, and environment. Optimizing limited water supplies is necessary in regions with water shortages. In this study, we implemented urban water usage schemes, including urban irrigation and road sprinkling in the Weather Research and Forecasting (WRF) model, and assessed their effects with different amounts of water in city centers, suburbs, and rural areas by using the WRF model at a resolution of 1 km in Beijing, China. In addition, we developed an optimization scheme with a cooling effect as the optimal objective and the total water supply as the constraint condition. Nonlinear relationships were identified between the cooling effect and water consumption for both road sprinkling and urban irrigation, and the cooling effect due to urban irrigation was more effective than that attributed to road sprinkling. Based on the optimal water management scheme, and according to Beijing's 13th 5 Year Plan, about 90 % of the total water supply should be used for urban irrigation and 10 % for road sprinkling as the most effective approach for decreasing urban temperatures by about 1.9 ∘C.

Background:. Specialty exposure is most influential in a medical student’s decision to pursue plastic surgery training. We aimed to understand what opportunities exist for students through national plastic surgery organizations. Methods:. The American Board of Plastic Surgery, American Society of Plastic Surgeons, and The Aesthetic Society provide online lists of related organizations. Cross-referencing lists yielded 47 unique organizations. Screening for presence of annual meeting and relevance to student and resident education yielded 14 organizations. Bylaws/web-domains were reviewed for information related to the annual meeting, leadership opportunities, membership, grants, and travel scholarships. If available, previrtual/in-person and virtual meeting prices were collected. Lastly, discrepancies between webpage information and phone/email correspondence were noted. Results:. All (100%) organizations welcomed students at annual meetings. Eleven promoted student presentation/submission. Average student registration fee was $109.3 ± SD$136.5 compared with $181.20 ± SD$157.20 for residents. Of organizations providing previrtual and virtual pricing (n = 10, 71.4%), there was an average price reduction in student registration of $92 (range: $0–375). Average student membership was $31.70/year ± SD $45.50 compared with $38.80 per year ± SD $65.90 for residents. The percentages of organizations offering student research grants, travel scholarships, and national student leadership were 21.4% (n = 3), 35.8% (n = 5), and 28.6% (n = 4) respectively. No organizations had student chapters/committees. All organizations (100%) contained at least one discrepancy between webpage/bylaw and email/phone. Conclusions:. Our results suggest that although national opportunities seem to be limited, a role exists for further engagement, with interested students eager to take the initiative. Virtual conferences present a lower-cost alternative for students and residents.

ABSTRACT: Subgroup J Avian leukosis virus (ALV-J) is an important pathogen of poultry tumor diseases. Since its discovery, it has caused significant economic losses to the poultry industry. Thus, the rapid detection of molecular level with strong specificity is particularly important whether poultry are infected with ALV-J. In this study, we designed primers and probe for real-time fluorescent reverse-transcription recombinase-aided amplification assay (RT-RAA) based on the ALV-J gp85 sequence. We had established a real-time fluorescent RT-RAA method and confirmed this system by verifying the specificity and sensitivity of the primers and probe. In addition, repeatability tests and clinical sample regression tests were used for preliminary evaluation of this detection method. The sensitivity of established method was about 101 copies/μL, and the repeatability of the CV of the CT value is 4%, indicating repeatability is good. Moreover, there was no cross-reactivity with NDV, IBV, IBDV, H9N2, MDV, and REV, and other avian leukosis virus subgroups, such as subgroups A, B, C, D, K and E. Importantly, the real-time fluorescent RT-RAA completed the test within 30 min at a constant temperature of 41°C. Forty-two clinical samples with known background were tested, and the test results were coincided with 100%. Overall, these results suggested that the real-time fluorescent RT-RAA developed in this study had strong specificity, high sensitivity, and good feasibility. The method is simple, easy, and portable, that is suitable for clinical and laboratory diagnosis, and provides technical support for the prevention and control of ALV-J.

Persistent wintertime heavy haze incidents caused by anthropogenic aerosols have repeatedly shrouded North China in recent years, while natural dust from the west and northwest of China also frequently affects air quality in this region. Through continuous observation by a multi-wavelength Raman lidar, here we found that wintertime aerosols in North China are typically characterized by a pronounced vertical stratification, where scattering nonspherical particles (dust or mixtures of dust and anthropogenic aerosols) dominated above the planetary boundary layer (PBL), and absorbing spherical particles (anthropogenic aerosols) prevailed within the PBL. This stratification is governed by meteorological conditions that strong northwesterly winds usually prevailed in the lower free troposphere, and southerly winds dominated in the PBL, producing persistent and intense haze pollution. With the increased contribution of elevated dust to the upper aerosols, the proportion of aerosol and trace gas at the surface in the whole column increased. Model results show that, besides directly deteriorating air quality, the key role of the elevated dust is to depress the development of PBL and weaken the turbulent exchange, mostly by lower level cooling and upper level heating, and it is more obvious during the dissipation stage, thus inhibiting the dissipation of heavy surface anthropogenic aerosols. The interactions of natural dust and anthropogenic aerosols under the unique topography of North China increase the surface anthropogenic aerosols and precursor gases, which may be one of the reasons why haze pollution in North China is heavier than that in other heavily polluted areas in China.

The local land–atmosphere coupling (LoCo) investigates the interactions between soil conditions, surface fluxes, planetary boundary layer (PBL) growth, and the formations of convective clouds and precipitation. Studying LoCo over the Tibetan Plateau (TP) is of great significance for understanding the TP's role in the Asian water tower. A series of real-case simulations, using the Weather Research and Forecasting (WRF) model with different combinations of land surface model (LSM) schemes and PBL schemes, has been carried out to investigate the LoCo characteristics over a typical underlying surface in the central TP in the rainy season. The LoCo characteristics in the study area are analyzed by applying a mixing diagram to the simulation results. The analysis indicates that the WRF simulations, using the Noah with BouLac, Mellor-Yamada Nakanishi and Niino Level-2.5 PBL (MYNN), and Yonsei University (YSU) produce closer results to the observation in terms of curves of Cp⋅θ and Lv⋅q, surface fluxes (Hsfc and LEsfc), entrainment fluxes (Hent, and LEent) at site BJ of Nagqu Station (BJ/Nagqu) than those using the Community Land Model (CLM) with BouLac, MYNN, and YSU. The frequency distributions of Hsfc, LEsfc, Hent, and LEent in the study area confirm this result. The spatial distributions of simulated Hsfc, LEsfc, Hent, and LEent, using WRF with Noah and BouLac, suggest that the spatial distributions of Hsfc and LEsfc in the study area are consistent with that of soil moisture, but the spatial distributions of Hent and LEent are quite different from that of soil moisture. A close examination of the relationship between entrainment fluxes and cloud water content (QCloud) reveals that the grids with small Hent and large LEent tend to have high QCloud and Hsfc, suggesting that high Hsfc is conducive to convective cloud formation, which leads to small Hent and large LEent. A sensitivity analysis of LoCo to the soil moisture at site BJ/Nagqu indicates that, on a sunny day, an increase in soil moisture leads to an increase in LEsfc but decreases in Hsfc, Hent, and LEent. The sensitivity of the relationship between simulated maximum daytime PBL height (PBLH) and mean daytime evapotranspiration (ET) in the study area to soil moisture indicates the rate at which the maximum daytime PBLH decreases with the mean ET increase as the initial soil moisture goes up. The analysis of simulated Hsfc, LEsfc, Hent, and LEent under different soil moisture conditions reveals that the frequency of Hent ranging from 80 to 240 W m−2 and the frequency of LEent ranging from −240 to −90 W m−2 both increase as the initial soil moisture increases. Coupled with the changes in QCloud, the changes in Hent and LEent as the initial soil moisture increases indicate that the rise in soil moisture leads to an increase in the cloud amount but a decrease in QCloud.

The Tibetan Plateau (TP) plays a critical role in influencing regional and global climate, via both thermal and dynamical mechanisms. Meanwhile, as the largest high-elevation part of the cryosphere outside the polar regions, with vast areas of mountain glaciers, permafrost and seasonally frozen ground, the TP is characterized as an area sensitive to global climate change. However, meteorological stations are biased and sparsely distributed over the TP, owing to the harsh environmental conditions, high elevations, complex topography and heterogeneous surfaces. Moreover, due to the weak representation of the stations, atmospheric conditions and the local land–atmosphere coupled system over the TP as well as its effects on surrounding regions are poorly quantified. This paper presents a long-term (2005–2016) in situ observational dataset of hourly land–atmosphere interaction observations from an integrated high-elevation and cold-region observation network, composed of six field stations on the TP. These in situ observations contain both meteorological and micrometeorological measurements including gradient meteorology, surface radiation, eddy covariance (EC), soil temperature and soil water content profiles. Meteorological data were monitored by automatic weather stations (AWSs) or planetary boundary layer (PBL) observation systems. Multilayer soil temperature and moisture were recorded to capture vertical hydrothermal variations and the soil freeze–thaw process. In addition, an EC system consisting of an ultrasonic anemometer and an infrared gas analyzer was installed at each station to capture the high-frequency vertical exchanges of energy, momentum, water vapor and carbon dioxide within the atmospheric boundary layer. The release of these continuous and long-term datasets with hourly resolution represents a leap forward in scientific data sharing across the TP, and it has been partially used in the past to assist in understanding key land surface processes. This dataset is described here comprehensively for facilitating a broader multidisciplinary community by enabling the evaluation and development of existing or new remote sensing algorithms as well as geophysical models for climate research and forecasting. The whole datasets are freely available at the Science Data Bank (https://doi.org/10.11922/sciencedb.00103; Ma et al., 2020) and additionally at the National Tibetan Plateau Data Center (https://doi.org/10.11888/Meteoro.tpdc.270910, Ma 2020).

Reduced-complexity climate models (RCMs) are critical in the policy and decision making space, and are directly used within multiple Intergovernmental Panel on Climate Change (IPCC) reports to complement the results of more comprehensive Earth system models. To date, evaluation of RCMs has been limited to a few independent studies. Here we introduce a systematic evaluation of RCMs in the form of the Reduced Complexity Model Intercomparison Project (RCMIP). We expect RCMIP will extend over multiple phases, with Phase 1 being the first. In Phase 1, we focus on the RCMs' global-mean temperature responses, comparing them to observations, exploring the extent to which they emulate more complex models and considering how the relationship between temperature and cumulative emissions of CO2 varies across the RCMs. Our work uses experiments which mirror those found in the Coupled Model Intercomparison Project (CMIP), which focuses on complex Earth system and atmosphere–ocean general circulation models. Using both scenario-based and idealised experiments, we examine RCMs' global-mean temperature response under a range of forcings. We find that the RCMs can all reproduce the approximately 1 ∘C of warming since pre-industrial times, with varying representations of natural variability, volcanic eruptions and aerosols. We also find that RCMs can emulate the global-mean temperature response of CMIP models to within a root-mean-square error of 0.2 ∘C over a range of experiments. Furthermore, we find that, for the Representative Concentration Pathway (RCP) and Shared Socioeconomic Pathway (SSP)-based scenario pairs that share the same IPCC Fifth Assessment Report (AR5)-consistent stratospheric-adjusted radiative forcing, the RCMs indicate higher effective radiative forcings for the SSP-based scenarios and correspondingly higher temperatures when run with the same climate settings. In our idealised setup of RCMs with a climate sensitivity of 3 ∘C, the difference for the ssp585–rcp85 pair by 2100 is around 0.23∘C(±0.12 ∘C) due to a difference in effective radiative forcings between the two scenarios. Phase 1 demonstrates the utility of RCMIP's open-source infrastructure, paving the way for further phases of RCMIP to build on the research presented here and deepen our understanding of RCMs.

On-road information, including road boundaries, road markings, and road cracks, provides significant guidance or warning to all road users. Recently, the on-road information extraction from LiDAR data have been widely studied. However, for the LiDAR data with lower accuracy and higher noise, some detailed information, such as road boundary, is difficult to be extracted correctly. Furthermore, most of previous studies lack an exploration of efficiently extracting multiple on-road information from a single framework. In this paper, we propose a new framework that can simultaneously extract multiple on-road information from high accuracy LiDAR data and can also more robustly extract detailed road boundaries from low accuracy LiDAR data. First, we propose a Curb-Aware Ground Filter to extract ground points with rich curb structure features. Second, we transform the vertical density, elevation gradient and intensity features of the ground points into multiple feature maps and extract multiple on-road information from the feature maps by employing a semantic segmentation network. Experimental results on three datasets with different data accuracy demonstrate that our method outperforms other recent competitive methods.

The role of polar regions is increasing in terms of megatrends such as globalization, new transport routes, demography, and the use of natural resources with consequent effects on regional and transported pollutant concentrations. We set up the ERA-PLANET Strand 4 project “iCUPE – integrative and Comprehensive Understanding on Polar Environments” to provide novel insights and observational data on global grand challenges with an Arctic focus. We utilize an integrated approach combining in situ observations, satellite remote sensing Earth observations (EOs), and multi-scale modeling to synthesize data from comprehensive long-term measurements, intensive campaigns, and satellites to deliver data products, metrics, and indicators to stakeholders concerning the environmental status, availability, and extraction of natural resources in the polar areas. The iCUPE work consists of thematic state-of-the-art research and the provision of novel data in atmospheric pollution, local sources and transboundary transport, the characterization of arctic surfaces and their changes, an assessment of the concentrations and impacts of heavy metals and persistent organic pollutants and their cycling, the quantification of emissions from natural resource extraction, and the validation and optimization of satellite Earth observation (EO) data streams. In this paper we introduce the iCUPE project and summarize initial results arising out of the integration of comprehensive in situ observations, satellite remote sensing, and multi-scale modeling in the Arctic context.

Recent studies suggested significant impacts of boreal cryosphere changes on wintertime air stagnation and haze pollution extremes in China. However, the underlying mechanisms of such a teleconnection relationship remains unclear. Here we use the Whole Atmosphere Community Climate Model (WACCM) to investigate dynamic processes leading to atmospheric circulation and air stagnation responses to Arctic sea ice changes. We conduct four climate sensitivity experiments by perturbing sea ice concentrations (SIC) and corresponding sea surface temperature (SST) in autumn and early winter over the whole Arctic and three subregions in the climate model. The results indicate distinct responses in circulation patterns and regional ventilation to the region-specific Arctic changes, with the largest increase of both the probability (by 132 %) and the intensity (by 30 %) of monthly air stagnation extremes being found in the experiment driven by SIC and SST changes over the Pacific sector of the Arctic (the East Siberian and Chukchi seas). The increased air stagnation extremes are mainly driven by an amplified planetary-scale atmospheric teleconnection pattern that resembles the negative phase of the Eurasian (EU) pattern. Dynamical diagnostics suggest that convergence of transient eddy forcing in the vicinity of Scandinavia in winter is largely responsible for the amplification of the teleconnection pattern. Transient eddy vorticity fluxes dominate the transient eddy forcing and produce a barotropic anticyclonic anomaly near Scandinavia and wave train propagation across Eurasia to the downstream regions in East Asia. The piecewise potential vorticity inversion analysis reveals that this long-range atmospheric teleconnection of Arctic origin takes place primarily via the middle and upper troposphere. The anomalous ridge over East Asia in the middle and upper troposphere worsens regional ventilation conditions by weakening monsoon northwesterlies and enhancing temperature inversions near the surface, leading to more and stronger air stagnation and pollution extremes over eastern China in winter. Ensemble projections based on state-of-the-art climate models in the Coupled Model Intercomparison Project Phase 6 (CMIP6) corroborate this teleconnection relationship between high-latitude environmental changes and midlatitude weather extremes, though the tendency and magnitude vary considerably among each participating model.

In order to reduce the vibration of the double-sided meshing nutation drive with double circular arc spiral bevel gears, the dynamic modal of the nutation system is analyzed. The bending-torsional-axial coupling nonlinear dynamic model of the double-sided meshing nutation drive system with time-varying meshing stiffness, meshing damping, transmission error and tooth backlash is established, and the equation of motion of the system is derived. The natural frequencies and corresponding modal modes of the nutation system are calculated, and the effects of the average meshing stiffness of gears and the bearing support stiffness of nutation gears on the modal of the system are analyzed. The modal analysis of double circular arc spiral bevel gears is carried out, and the ten order natural frequencies and their corresponding modes are obtained. The results show that the nutation drive system and the double circular arc spiral bevel gears do not resonate during transmission.

Climate change, rising CO2 concentration, and land use and land cover change (LULCC) are primary driving forces for terrestrial gross primary productivity (GPP), but their impacts on the temporal changes in GPP are uncertain. In this study, the effects of the three main factors on the interannual variation (IAV) and seasonal cycle amplitude (SCA) of GPP in China were investigated using 12 terrestrial biosphere models from the Multi-scale Synthesis and Terrestrial Model Intercomparison Project. The simulated ensemble mean value of China's GPP between 1981 and 2010, driven by common climate forcing, LULCC and CO2 data, was found to be 7.4±1.8 Pg C yr−1. In general, climate was the dominant control factor of the annual trends, IAV and seasonality of China's GPP. The overall rising CO2 led to enhanced plant photosynthesis, thus increasing annual mean and IAV of China's total GPP, especially in northeastern and southern China, where vegetation is dense. LULCC decreased the IAV of China's total GPP by ∼7 %, whereas rising CO2 induced an increase of 8 %. Compared to climate change and elevated CO2, LULCC showed less contributions to GPP's temporal variation, and its impact acted locally, mainly in southwestern China. Furthermore, this study also examined subregional contributions to the temporal changes in China's total GPP. Southern and southeastern China showed higher contributions to China's annual GPP, whereas southwestern and central parts of China explained larger fractions of the IAV in China's GPP.

The feedback from the accretion of central supermassive black holes (SMBHs) is a hot topic in the coevolution of SMBHs and their host galaxies. By tracing the large-scale outflow using the line profile and bulk velocity shift of [O iii ] λ 5007, the evolutionary role of outflow is studied here on a large sample of 221 type 2 quasars (QSO2s) extracted from Reyes et al. By following our previous study on local Seyfert 2 galaxies, the current spectral analysis on the Sloan Digital Sky Survey spectroscopic database enables us to arrive at the following results: (1) by using the Lick indices, we confirm that QSO2s are, on average, more frequently associated with younger stellar populations than Seyfert galaxies; (2) QSO2s with a stronger outflow tend to be associated with a younger stellar population, which implies a coevolution between the feedback from SMBHs and the host in QSO2s; (3) although occupied at the high L _bol / L _Edd end, the QSO2s follow the L _bol / L _Edd - D _n (4000) sequence established from local, less-luminous Seyfert galaxies, which suggests a decrease of the accretion activity of SMBHs and also of feedback as the circumnuclear stellar population continuously ages.

The molecular compositions of polar organic compounds (POCs) in particles emitted from various vessels and excavators were characterized using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), and possible molecular structures of POCs were proposed. POCs were extracted with purified water and sorted by elemental composition into three groups: CHO, CHON, and S-containing compounds (CHONS and CHOS). The results show the following. (i) CHO (accounting for 49 % of total POCs in terms of peak response) was the most abundant group for all tested off-road engines, followed by CHON (33 %) and CHOS (35 %) for diesel and HFO (heavy-fuel-oil)-fueled off-road engines. (ii) The abundance and structure of the CHON group in water extracts were different in terms of engine type and load. The relative peak response of CHON was the highest for excavator emissions in working mode, compared to the idling and moving modes. Furthermore, dinitrophenol and methyl dinitrophenol were potentially the most abundant emission species for high-rated speed excavators, while nitronaphthol and methyl nitronaphthol were more important for low-rated speed vessels. (iii) The composition and structure of the S-containing compounds were directly influenced by fuel oil characteristics (sulfur content and aromatic ring), with more condensed aromatic rings in the S-containing compounds proposed in HFO-fueled vessel emissions. More abundant aliphatic chains were inferred in diesel equipment emissions. Overall, higher fractions of condensed hydrocarbons and aromatic rings in POCs emitted from vessels using HFO cause strong optical absorption capacity. Different structures in POCs could provide a direction for qualitative and quantitative analysis of organic compounds as tracers to distinguish these emissions from diesel or HFO-fueled off-road engines.

Climate change affects water availability for soil, and groundwater extraction influences water redistribution by altering water demand, both of which significantly affect soil moisture. Quantifying their relative contribution to the changes in soil moisture will further our understanding of the mechanisms underlying the global water cycle. In this study, two groups of simulations were conducted with and without groundwater (GW) extraction (estimated based on local water supply and demand) from 1979 to 2010 using the Chinese Academy of Sciences land surface model, CAS-LSM, with four global meteorological forcing datasets (GSWP3, PRINCETON, CRU-NCEP, and WFDEI). To investigate the contribution of climate change and GW extraction, a trajectory-based method was used. Comparing the simulated results with the in situ dataset of the International Soil Moisture Network (ISMN) and the satellite-based soil moisture product of the European Space Agency's Climate Change Initiative (ESA-CCI) indicated that the CAS-LSM reasonably reproduced the distribution of soil moisture and matched the temporal changes well. Globally, our results suggested a significant decreasing trend in surface soil moisture (0–10 cm, 0.98×10-4 mm3 mm−3 yr−1) over the 32-year period tested. The drying trends were mainly observed in arid regions such as the tropical desert regions in North Africa and the Arabian Peninsula, while the wetting trends were primarily in tropical forested areas in South America and northeastern Asia. Climate change contributed 101.2 % and 90.7 % to global drying and wetting trends of surface soil moisture, respectively, while GW extraction accounted for −1.2 % and 9.3 %, respectively. In deep soil, GW extraction contributed 1.37 % and −3.21 % to the drying and wetting trends, respectively. The weak influence of GW extraction may be because this activity occurs in limited areas. GW extraction contributed more than 35 % to the change in surface soil moisture in wetting areas where GW overexploitation occurs. GW is mainly extracted for irrigation to alleviate soil water stress in semiarid regions that receive limited precipitation, thereby slowing the drying trend and accelerating the wetting trend of surface soil. However, GW exploitation weakens the hydraulic connection between the soil and aquifer, leading to deeper soils drying up. Overall, climate change dominated the soil moisture trends, but the effect of GW extraction cannot be ignored.

Speciated atmospheric mercury including gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (PBM) were measured continuously for a 1-year period at a suburban site, representing a regional transport intersection zone, in east China. Annual mean concentrations of GEM, PBM, and GOM reached 2.77 ng m−3, 60.8 pg m−3, and 82.1 pg m−3, respectively. GEM concentrations were elevated in all the seasons except autumn. High mercury concentrations were related to winds from the south, southwest, and north of the measurement site. Combining analysis results from using various source apportionment methods, it was found that GEM concentration was higher when quasi-local sources dominated over long-range transport. Six source factors belonging to the anthropogenic sources of GEM were identified, including the common sectors previously identified (industrial and biomass burning, coal combustion, iron and steel production, cement production, and incineration), as well as an additional factor of shipping emissions (accounting for 19.5 % of the total), which was found to be important in east China where marine vessel shipping activities are intense. Emissions of GEM from natural surfaces were also found to be as important as those from anthropogenic sources for GEM observed at this site. Concurrences of high GOM concentrations with elevated O3 and temperature, along with the lagged variations in GEM and GOM during daytime demonstrated that the very high GOM concentrations were partially ascribed to intense in situ oxidation of GEM. Strong gas–particle partitioning was also identified when PM2.5 was above a threshold value, in which case GOM decreased with increasing PM2.5.

Air quality models have not been able to reproduce the magnitude of the observed concentrations of fine particulate matter (PM2.5) during wintertime Chinese haze events. The discrepancy has been at least partly attributed to low biases in modeled sulfate production rates, due to the lack of heterogeneous sulfate production on aerosols in the models. In this study, we explicitly implement four heterogeneous sulfate formation mechanisms into a regional chemical transport model, in addition to gas-phase and in-cloud sulfate production. We compare the model results with observations of sulfate concentrations and oxygen isotopes, Δ17O(SO42-), in the winter of 2014–2015, the latter of which is highly sensitive to the relative importance of different sulfate production mechanisms. Model results suggest that heterogeneous sulfate production on aerosols accounts for about 20 % of sulfate production in clean and polluted conditions, partially reducing the modeled low bias in sulfate concentrations. Model sensitivity studies in comparison with the Δ17O(SO42-) observations suggest that heterogeneous sulfate formation is dominated by transition metal ion-catalyzed oxidation of SO2.

Accompanied by unfavorable meteorological conditions with stable stratification in various haze regions of China, persistent heavy aerosol pollution episodes (HPEs) lasting more than 3 consecutive days frequently occur, particularly in winter. In the North China Plain (NCP), explosive growth of fine particulate matter smaller than 2.5 µm in diameter (PM2.5), which occurs during some HPES, is dominated by a two-way feedback mechanism between more unfavorable meteorological conditions and cumulative aerosol pollution. However, the existence of a two-way feedback mechanism such as this in other key haze regions in China is uncertain; these regions include the Guanzhong Plain (GZP), the Yangtze River Delta (YRD) region, the Two Lakes Basin (TLB; a large outflow basin connected to Hubei Province and Hunan Province), the Pearl River Delta (PRD) region, the Sichuan Basin (SB), and the Northeast China Plain (NeCP). In this study, using surface PM2.5 and radiation observations, radiosonde observations, and reanalysis data, we observed the existence of a two-way feedback mechanism in the six abovementioned regions. In the SB, this two-way feedback mechanism is weak due to the suppression of cloudy mid-upper layers. In the more polluted NCP, the GZP, and the NeCP, the feedback is more striking than that in the YRD, the TLB, and the PRD. In these regions, the feedback of worsened meteorological conditions on PM2.5 explains 60 %–70 % of the increase in PM2.5 during the cumulative stages (CSs). For each region, the low-level cooling bias becomes increasingly substantial with increasing aerosol pollution and a closer distance to the ground surface. With PM2.5 mass concentrations greater than 400 µg m−3, the near-ground bias exceeded −4 ∘C in Beijing and reached up to approximately −4 ∘C in Xi'an; this result was caused by accumulated aerosol mass to some extent. In addition to the increase in PM2.5 caused by the two-way feedback, these regions also suffer from the regional transport of pollutants, including inter-regional transport in the GZP, trans-regional transport from the NCP to the YRD and the TLB, and southwesterly transport in the NeCP.

We investigated the effects of 0.025 or 0.05 mM methyl jasmonate (MeJA) on the growth characteristics, antioxidant enzyme activities, non-enzymatic antioxidant content, and carbon and nitrogen metabolizing enzyme activities in Glycyrrhiza uralensis exposed to 100 mM NaCl. Results showed that salt stress decreased the stem length and lateral root number and the treatment with 0.025 or 0.05 mM MeJA increased the root length of salt-stressed G. uralensis seedlings but decreased root diameter, stem length, and stem diameter. MeJA application modulated oxidative stress in salt-stressed G. uralensis seedlings. It decreased the catalase activity but enhanced peroxidase activity and ascorbate content. However, treatment with 0.05 mM MeJA significantly increased the malondialdehyde content of salt-stressed seedlings. Salt stress inhibited carbon and nitrogen metabolism. The application of MeJA enhanced the activities of sucrose synthase, and sucrose phosphate synthase, and nitrate reductase in salt-stressed seedlings.

Temperature variations in the girder at two cross-sections of a long-span prestressed concrete box girder bridge (PCBG) were analysed based on measured data. The results show that the temperature distribution in the concrete box girder (CBG) is strongly influenced by its size, and the temperature distribution in the girder changes along the longitudinal direction of the bridge. To clarify the temperature distribution in the long-span PCBG bridge, a two-dimensional (2D) temperature prediction model, validated by the measured data, was proposed, and the effect of the girder size on the temperature distribution of the CBG was studied using the model. Based on the results of the studies, simplified vertical and transverse temperature gradient models that could consider changes along the longitudinal direction of the bridge were proposed and validated by using the measured data and three-dimensional (3D) mechanical finite element model (FEM) of the bridge. Then, the deformations and stresses derived from the proposed temperature gradient models and the models according to different codes were studied and compared. Finally, conclusions and recommendations for future bridge design are provided.

The rapid mass increase of atmospheric nitrate is a critical driving force for the occurrence of fine-particle pollution (referred to as haze hereafter) in Beijing. However, the exact mechanisms for this rapid increase of nitrate mass have not been well constrained from field observations. Here we present the first observations of the oxygen-17 excess of atmospheric nitrate (Δ17O(NO3−)) collected in Beijing haze to reveal the relative importance of different nitrate formation pathways, and we also present the simultaneously observed δ15N(NO3−). During our sampling period, 12 h averaged mass concentrations of PM2.5 varied from 16 to 323 µg m−3 with a mean of (141±88(1SD)) µg m−3, with nitrate ranging from 0.3 to 106.7 µg m−3. The observed Δ17O(NO3−) ranged from 27.5 ‰ to 33.9 ‰ with a mean of (30.6±1.8) ‰, while δ15N(NO3−) ranged from −2.5 ‰ to 19.2 ‰ with a mean of (7.4±6.8) ‰. Δ17O(NO3−)-constrained calculations suggest nocturnal pathways (N2O5 + H2O∕Cl− and NO3 + HC) dominated nitrate production during polluted days (PM2.5 ≥ 75 µg m−3), with a mean possible fraction of 56–97 %. Our results illustrate the potentiality of Δ17O in tracing nitrate formation pathways; future modeling work with the constraint of isotope data reported here may further improve our understanding of the nitrogen cycle during haze.

Discerning mechanisms of sulfate formation during fine-particle pollution (referred to as haze hereafter) in Beijing is important for understanding the rapid evolution of haze and for developing cost-effective air pollution mitigation strategies. Here we present observations of the oxygen-17 excess of PM2.5 sulfate (Δ17O(SO42−)) collected in Beijing haze from October 2014 to January 2015 to constrain possible sulfate formation pathways. Throughout the sampling campaign, the 12-hourly averaged PM2.5 concentrations ranged from 16 to 323 µg m−3 with a mean of (141 ± 88 (1σ)) µg m−3, with SO42− representing 8–25 % of PM2.5 mass. The observed Δ17O(SO42−) varied from 0.1 to 1.6 ‰ with a mean of (0.9 ± 0.3) ‰. Δ17O(SO42−) increased with PM2.5 levels in October 2014 while the opposite trend was observed from November 2014 to January 2015. Our estimate suggested that in-cloud reactions dominated sulfate production on polluted days (PDs, PM2.5 ≥ 75 µg m−3) of Case II in October 2014 due to the relatively high cloud liquid water content, with a fractional contribution of up to 68 %. During PDs of Cases I and III–V, heterogeneous sulfate production (Phet) was estimated to contribute 41–54 % to total sulfate formation with a mean of (48 ± 5) %. For the specific mechanisms of heterogeneous oxidation of SO2, chemical reaction kinetics calculations suggested S(IV) ( = SO2 ⚫ H2O + HSO3− + SO32−) oxidation by H2O2 in aerosol water accounted for 5–13 % of Phet. The relative importance of heterogeneous sulfate production by other mechanisms was constrained by our observed Δ17O(SO42−). Heterogeneous sulfate production via S(IV) oxidation by O3 was estimated to contribute 21–22 % of Phet on average. Heterogeneous sulfate production pathways that result in zero-Δ17O(SO42−), such as S(IV) oxidation by NO2 in aerosol water and/or by O2 via a radical chain mechanism, contributed the remaining 66–73 % of Phet. The assumption about the thermodynamic state of aerosols (stable or metastable) was found to significantly influence the calculated aerosol pH (7.6 ± 0.1 or 4.7 ± 1.1, respectively), and thus influence the relative importance of heterogeneous sulfate production via S(IV) oxidation by NO2 and by O2. Our local atmospheric conditions-based calculations suggest sulfate formation via NO2 oxidation can be the dominant pathway in aerosols at high-pH conditions calculated assuming stable state while S(IV) oxidation by O2 can be the dominant pathway providing that highly acidic aerosols (pH ≤ 3) exist. Our local atmospheric-conditions-based calculations illustrate the utility of Δ17O(SO42−) for quantifying sulfate formation pathways, but this estimate may be further improved with future regional modeling work.

In this paper, we present ship-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements of tropospheric trace gases' distribution along the Yangtze River during winter 2015. The measurements were performed along the Yangtze River between Shanghai and Wuhan, covering major industrial areas in eastern China. Tropospheric vertical column densities (VCDs) of nitrogen dioxide (NO2), sulfur dioxide (SO2), and formaldehyde (HCHO) were retrieved using the air mass factor calculated by the radiative transfer model. Enhanced tropospheric NO2 and SO2 VCDs were detected over downwind areas of industrial zones over the Yangtze River. In addition, spatial distributions of atmospheric pollutants are strongly affected by meteorological conditions; i.e., positive correlations were found between concentration of pollutants and wind speed over these areas, indicating strong influence of transportation of pollutants from high-emission upwind areas along the Yangtze River. Comparison of tropospheric NO2 VCDs between ship-based MAX-DOAS and Ozone Monitoring Instrument (OMI) satellite observations shows good agreement with each other, with a Pearson correlation coefficient (R) of 0.82. In this study, the NO2 ∕ SO2 ratio was used to estimate the relative contributions of industrial sources and vehicle emissions to ambient NO2 levels. Analysis results of the NO2 ∕ SO2 ratio show a higher contribution of industrial NO2 emissions in Jiangsu Province, while NO2 levels in Jiangxi and Hubei provinces are mainly related to vehicle emissions. These results indicate that different pollution control strategies should be applied in different provinces. In addition, multiple linear regression analysis of ambient carbon monoxide (CO) and odd oxygen (Ox) indicated that the primary emission and secondary formation of HCHO contribute 54.4 ± 3.7 % and 39.3 ± 4.3 % to the ambient HCHO, respectively. The largest contribution from primary emissions in winter suggested that photochemically induced secondary formation of HCHO is reduced due to lower solar irradiance in winter. Our findings provide an improved understanding of major pollution sources along the eastern part of the Yangtze River which are useful for designing specific air pollution control policies.