Beijing Normal University
Recent publications
Phosphorus (P) in sediments plays an important role in shallow lake ecosystems and has a major effect on the lake environment. The mobility and bioavailability of P primarily depend on the contents of different P forms, which in turn depend on the sedimentary environment. Here, sediment samples from Baiyangdian (BYD) lake were collected and measured by the Standards, Measurements, and Testing procedure and Phosphorus-31 nuclear magnetic resonance spectroscopy (31P NMR) to characterize different P forms and their relationships with sediment physicochemical properties. The P content in the sediments varied in different areas and had characteristics indicative of exogenous river input. Inorganic P (334–916 mg/kg) was the dominant form of P. The 31P NMR results demonstrated that orthophosphate monoesters (16–110 mg/kg), which may be a source of P when redox conditions change, was the dominant form of organic P (20–305 mg/kg). The distribution of P forms in each region varied greatly because of the effects of anthropogenic activities, and the regions affected by exogenous river input had a higher content of P and a higher risk of P release. Principal component analysis indicated that P bound to Fe, Al, and Mn oxides and hydroxides (NaOH-P) and organic P were mainly derived from industrial and agricultural pollution, respectively. Redundancy analysis indicated that increases in pH lead to the release of NaOH-P. Organic matter plays an important role in the organic P biogeochemical cycle, as it acts as a sink and source of organic P.
Background: In China, bereaved parents who have lost their only child are known as Shidu parents, and they tend to present high levels of prolonged grief reactions. To date, a widespread focus has been placed on positive social support, while potential negative experiences have been relatively neglected. Additionally, the role of social support from different sources (i.e. close family members [partner, siblings, grandchildren], peers, and others [relatives, friends, colleagues]) has not been examined thoroughly. Objective: The present study investigated whether social support from different sources has a differential impact on postloss adaptation (i.e. prolonged grief and growth). The loss-orientated and restoration-orientated coping strategies of the dual process model were also tested for their mediating roles. Methods: A total of 277 Chinese Shidu parents were recruited to complete a series of questionnaires including social support from different sources, prolonged grief symptoms, posttraumatic growth, and dual process coping strategies. Correlation analyses, paired sample t tests and structural equation modelling were conducted. Results: More positive support were related to less prolonged grief symptoms and more posttraumatic growth, while more negative support was only related to more prolonged grief. Positive support from close family members and others was significantly related to prolonged grief/growth, and negative support from these sources was significantly positively associated with prolonged grief. Positive or negative support from people who shared a similar experience was unrelated to prolonged grief/growth. Positive and negative support were related to prolonged grief and growth through loss-oriented coping strategies. Conclusion: Overall, the present study indicated that positive and negative support experiences from different sources functioned differently in the recovery of Chinese Shidu parents and that loss-oriented coping played a mediating role. These findings highlight the importance of differentiating social support by traits in coping with grief and the crucial mediating role of loss-oriented coping. Highlights: More positive support correlated with less prolonged grief and more growth, while more negative support correlated with more prolonged grief.Support from family members and friends was more potent than that from peers.Social Support correlated with prolonged grief/growth through loss-oriented coping.
Data provides a foundation for machine learning, which has accelerated data-driven materials design. The scientific literature contains a large amount of high-quality, reliable data, and automatically extracting data from the literature continues to be a challenge. We propose a natural language processing pipeline to capture both chemical composition and property data that allows analysis and prediction of superalloys. Within 3 h, 2531 records with both composition and property are extracted from 14,425 articles, covering γ ′ solvus temperature, density, solidus, and liquidus temperatures. A data-driven model for γ ′ solvus temperature is built to predict unexplored Co-based superalloys with high γ ′ solvus temperatures within a relative error of 0.81%. We test the predictions via synthesis and characterization of three alloys. A web-based toolkit as an online open-source platform is provided and expected to serve as the basis for a general method to search for targeted materials using data extracted from the literature.
Nanofiltration (NF) process has become one of the most promising technologies to remove micro-organic combined water pollution. Developing a NF membrane material with efficient separation for perfluorooctanoic acid (PFOA) combined pollution is highly desired, this manuscript targets this unmet need specifically. In this work, hydrophilic SiO2 nanoparticles with various contents blended with carboxylic multiwalled carbon nanotube were used to modify poly (m- phenylene isophthal amide) (SiO2/CMWCNT/PMIA) hollow fiber NF membrane. The modified membrane with 0.1 wt% SiO2 doping exhibits way better fouling resistance with irreversible fouling ratio decreased dramatically from 18.7% to 2.3%, and the recovery rate of water flux increases significantly from 81.2% to 97.7%. The separation experiment results had confirmed that the modified membrane could improve the rejection from 97.2% to 98.6% for perfluorooctanoic acid (PFOA) and its combined pollution with bovine serum albumin (BSA). It is clear that this reported SiO2/CMWCNT/PMIA hollow fiber NF membrane potentially could be applied in water treatment. This research also provides a theoretical basis for efficiently removal of PFOA and its combined pollution by NF membrane.
We investigated variations of PM2.5 and water-soluble inorganic ions chemical characteristics at nine urban and rural sites in China using ground-based observations. From 2015 to 2019, mean PM2.5 concentration across all sites decreased by 41.9 µg/m³ with a decline of 46% at urban sites and 28% at rural sites, where secondary inorganic aerosol (SIAs) contributed to 21% (urban sites) and 17% (rural sites) of the decreased PM2.5. SIAs concentrations underwent a decline at urban locations, while sulfate (SO42–), nitrate (NO3–), and ammonium (NH4⁺) decreased by 49.5%, 31.3% and 31.6%, respectively. However, only SO42– decreased at rural sites, NO3– increased by 21% and NH4⁺ decreased slightly. Those changes contributed to an overall SIAs increase in 2019. Higher molar ratios of NO3– to SO42– and NH4⁺ to SO42– were observed at urban sites than rural sites, being highest in the heavily polluted days. Mean molar ratios of NH3/NHx were higher in 2019 than 2015 at both urban and rural sites, implying increasing NHx remained as free NH3. Our observations indicated a slower transition from sulfate-driven to nitrate-driven aerosol pollution and less efficient control of NOx than SO2 related aerosol formation in rural regions than urban regions. Moreover, the common factor at urban and rural sites appears to be a combination of lower SO42– levels and an increasing fraction of NO3– to PM2.5 under NH4⁺-rich conditions. Our findings imply that synchronous reduction in NOx and NH3 emissions especially rural areas would be effective to mitigate NO3–-driven aerosol pollution.
It is unequivocal that human influence has warmed the planet, which is seriously affecting the planetary health including human health. Adapting climate change should not only be a slogan, but requires a united, holistic action and a paradigm shift from crisis response to an ambitious and integrated approach immediately. Recognizing the urgent needs to tackle the risk connection between climate change and One Health, the four key messages and recommendations that with the intent to guide further research and to promote international cooperation to achieve a more climate-resilient world are provided. Graphical Abstract
Background The accurate estimation of carbon-water flux is critical for understanding the carbon and water cycles of terrestrial ecosystems and further mitigating climate change. Model simulations and observations have been widely used to research water and carbon cycles of terrestrial ecosystems. Given the advantages and limitations of each method, combining simulations and observations through a data assimilation technique has been proven to be highly promising for improving carbon-water flux simulation. However, to the best of our knowledge, few studies have accomplished both parameter optimization and the updating of model state variables through data assimilation for carbon-water flux simulation in multiple vegetation types. And little is known about the variation of the performance of data assimilation for carbon-water flux simulation in different vegetation types. Methods In this study, we assimilated leaf area index (LAI) time-series observations into a biogeochemical model (Biome-BGC) using different assimilation algorithms (ensemble Kalman filter algorithm (EnKF) and unscented Kalman filter (UKF)) in different vegetation types (deciduous broad-leaved forest (DBF), evergreen broad-leaved forest (EBF) and grassland (GL)) to simulate carbon-water flux. Results The validation of the results against the eddy covariance measurements indicated that, overall, compared with the original simulation, assimilating the LAI into the Biome-BGC model improved the carbon-water flux simulations (R² increased by 35%, root mean square error decreased by 10%; the sum of the absolute error decreased by 8%) but more significantly, improved the water flux simulations (R² increased by 31%, root mean square error decreased by 18%; the sum of the absolute error decreased by 16%). Among the different forest types, the data assimilation techniques (both EnKF and UKF) achieved the best performance towards carbon-water flux in EBF (R² increased by 44%, root mean square error decreased by 24%; the sum of the absolute error decreased by 28%), and the performances of EnKF and UKF showed slightly different when simulating carbon fluxes. Conclusion We suggest that to reduce the uncertainty in global carbon-water flux quantification, forthcoming data assimilation treatment should consider the vegetation types where the data assimilation experiments are carried out, the simulated objectives and the assimilation algorithms.
Background Spatio-temporal variations of structural components of the POM–DOM fractions exhibit in urban rivers, which is valuable information to reveal dynamic migration and transformation within and between the organic matter pools, also provide important support for river water quality improvement and management measures. Second derivative UV–visible spectroscopy (SDUVS) was applied to simultaneously characterize structural components and spatial variations of dissolved (DOM: Diameter < 0.2 μm) and particulate (POM1: 0.2 < diameter < 0.7 μm; POM2: diameter > 0.7 μm) organic matters in an urbanized river of northeast China. Results Thirty-six water samples were collected from mainstream and tributaries along a human impact gradient, i.e., rural, town and urban regions. The DOM was a representative fraction for the natural organic matter pool, which was mostly derived from allochthonous and terrestrial sources. Four components C1 to C4 were identified from the POM–DOM fractions by the SDUVS. The C1 associated with phenolic groups and the C2 related to carboxylic groups were dominant for the organic matter pool. The C3 was composed of the primary humificated materials, and the %C3 was kept relatively consistent in the organic matter pool. The C4 presented deeply humificated organic matter with the increase of aromatic and alkyl structures. The average %C4 of the POM pool was higher than that of the DOM pool, indicating that the humification degree of the POM fractions was higher than that of the DOM fraction. Conclusions Moreover, the tributaries had a higher average %C4 within the DOM than the mainstream, and trends of the POM pool were similar to the DOM pool. The trophic level of the river water decreased in the order of urban region > town region > rural region, while the molecular sizes of the POM–DOM decreased in the order of rural region > town region > urban region. Graphical Abstract
Background As a multi-ethnic country, the US is increasingly concerned about ethnic minorities facing disproportionate health risks of the coronavirus disease 2019 (COVID-19) pandemic. This study attempted to provide a macro picture of the associations between population distribution by ethnicity and the vulnerability to COVID-19 in terms of infection risk and vaccination coverage in the US. Methods This study used multi-source data from New York Times, County Health Rankings & Roadmap Program (2020), and the Center for Disease Control and Prevention. Multiple linear regressions were performed at equidistant time points (May 2020-Jan 2021, with one-month interval between each time point) to reveal the association between population distribution by ethnicities and the infection risk and the dynamics over time. Besides, multiple linear regressions were also conducted at equidistant time points (Jan 2021-Aug 2021) to reveal whether health disparities between ethnicities would hold true for the COVID-19 vaccination coverage (in total population, and among those > 12, > 18, and > 65 years of age). Results Both the COVID-19 confirmed cases (population standardized) and the vaccination coverage (in total population, and among those > 12, > 18, and > 65 years of age) were significantly associated with the population distribution by ethnicity ( e.g., population percentage of ethnic minorities ). Above associations were statistically significant for non-Hispanic blacks and Hispanics, but not for Asian Americans. Conclusions A proportion of socioeconomically-disadvantageous population could be a key intuitive reflection of the risk level of this public health crisis. The policy focusing on the vulnerable population is important in this pandemic.
Background On the front lines of climate change, glacier termini play crucial roles in linking glaciers and downstream ecosystems during glacier retreat. However, we lack a clear understanding of biological processes that occur in surface and basal ice at glacier termini. Methods Here, we studied the bacterial communities in surface ice and basal ice (the bottom layer) of a glacier terminus in the Yangtze River Source, Qinghai–Tibet Plateau. Results Surface and basal ice harbored distinct bacterial communities but shared some core taxa. Surface ice communities had a higher α-diversity than those in basal ice and were dominated by Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, and Cyanobacteria while basal ice was dominated by Firmicutes and Proteobacteria. The bacterial communities were also substantially different in functional potential. Genes associated with functional categories of cellular processes and metabolism were significantly enriched in surface ice, while genes connected to environmental information processing were enriched in basal ice. In terms of biogeochemical cycles of carbon, nitrogen, phosphorus, and sulfur, bacterial communities in surface ice were enriched for genes connected to aerobic carbon fixation, aerobic respiration, denitrification, nitrogen assimilation, nitrogen mineralization, sulfur mineralization, alkaline phosphatase, and polyphosphate kinase. In contrast, bacterial communities in basal ice were enriched for genes involved in anaerobic carbon fixation, fermentation, nitrate reduction, 2-aminoethylphosphonic acid pathway, G3P transporter, glycerophosphodiester phosphodiesterase, and exopolyphosphatase. Structural equation modeling showed that total nitrogen and environmental carbon:phosphorus were positively while environmental nitrogen:phosphorus was negatively associated with taxonomic β-diversity which itself was strongly associated with functional β-diversity of bacterial communities. Conclusions This study furthers our understanding of biogeochemical cycling of the mountain cryosphere by revealing the genetic potential of the bacterial communities in surface and basal ice at the glacier terminus, providing new insights into glacial ecology as well as the influences of glacier retreat on downstream systems.
In an open and flexible context of Massive Open Online Courses (MOOCs), learners who take final assessments exhibit the motivation for performance goals. The learning trajectories of this group usually provide more clues for course design and teaching improvement in that this group tend to interact more fully with course learning activities and resources for better learning outcomes. This study focused on such learners to investigate their learning engagement, time organization, content visit sequences, and activity participation patterns by applying statistical analysis, lag sequence analysis, and other data mining methods. This study examined the data of 535 learners taking the assessment in a MOOC to detect the differences in learning engagement and the above learning patterns amongst three groups of learners with different achievement levels, labeled failed , satisfactory and excellent . We found differences in both learning engagement and learning patterns among the three groups. The results indicated that for the learners to be successful, they require a certain degree of task completion as a basic guarantee for passing the course, effective session workload organization, reasonable learning content arrangement, and more cognitive engagement (rather than investing more time and energy). Based on the outcomes, implications for personalized instructional design and intervention to promote academic achievement in MOOCs are discussed.
Carbon capture, utilization, and storage (CCUS), as a technology with large-scale emission reduction potential, has been widely developed all over the world. In China, CCUS development achieved fruitful outcomes. CCUS gained further broad attention from the announcement of the carbon neutrality target by 2060, as CCUS is an indispensable important technology to realize carbon neutrality. It helps not only to build zero-emission and more resilient energy and industry systems but also provides negative emission potential. This paper discusses the new demand for carbon capture, utilization, and storage development brought by the carbon neutrality target analyzes the development status. As there remain various challenges of CCUS development, this paper focuses on several key issues for CCUS development in China targeting carbon neutrality: 1) how to reposition the role of CCUS under the carbon neutral target? 2) how shall we understand the technology development status and the costs? 3) what role shall utilization and storage play in future? 4) potential strategy applied to solve challenges of source-sink mismatch and resources constraints; and 5) new business model that suits large scale deployment of CCUS. This paper puts forward several policy suggestions that should be focused on now in China, especially to raise awareness under the vision of carbon neutrality that the role and contribution of CCUS are different, to accelerate the establishment of a comprehensive and systematic enabling environment for CCUS.
Hash-based group-by and aggregation is a fundamental operator in database systems. Modern discrete GPUs (graphics processing units) have been considered to accelerate the performance. However, the data transfer through the PCIe (peripheral component interconnect express) bus would reduce gains. On recent architectures, the GPU and the CPU (central processing unit) are built into the same chip which removes the data transmission and offers new performance opportunities. Yet there has been no systematic analysis of grouping and aggregation algorithms on such architectures. In this paper, we study the behaviors of various hash-based grouping and aggregation methods on coupled architectures to provide meaningful guidelines. We conduct an extensive experimental study and analysis on the single CPU, the coupled GPU, and both processors. Six dimensions are considered in analyzing the hashing methods carefully: (1) hashing scheme, (2) hash function, (3) data size, (4) group cardinality, (5) load factor, and (6) data distribution. Two additional dimensions are also explored: (7) shared and independent hash tables and (8) running on single processors and co-processing. We hope the results in our study could help database researchers to choose the right direction in terms of algorithm design and system optimization.
Background This study is to investigate the interaction of family support, transport cost (ex-post), and disabilities on health service seeking behavior among older people from the perspective of social ecological model. Method We conduct a series of regressions including the Poisson model and Multiple logit model. The Heckman two-stage procedure is also conducted to check the robustness. Results Given that health care resources are generally concentrated in densely populated urban areas, access to services of higher-class health care facilities is found associated with higher transport cost (ex-post). Family support could also promote the access to higher-class health care facilities. Although disability may impede such access, this effect may be mitigated by paying higher transport cost (ex-post). Conclusions Alleviating transport deprivation and promoting family support are critical for access to better healthcare services among older people with disabilities.
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12,021 members
Linna Chai
  • Faculty of Geographical Science
Xi-Nian Zuo
  • State Key Laboratory of Cognitive Neuroscience and Learning
Baoshan Cui
  • School of Environment
Huiliang Wang
  • College of Chemistry
Xinjiekouwai Street, 100875, Beijing, China
Head of institution
Qi Dong