科研成果

Coprecipitation of selenium oxyanions with barite is a facile way to sequester Se in the environments. However, the chemical composition of Se-barite coprecipitates usually deviates from that predicted from thermodynamic calculations. This discrepancy was resolved by considering variations in nucleation and growth rates controlled by ion–mineral interactions, solubility, and interfacial energy. For homogeneous precipitation, ∼10% of sulfate, higher than thermodynamic predictions (<0.3%), was substituted by Se(IV) or Se(VI) oxyanion, which was attributed to adsorption-induced entrapment during crystal growth. For heterogeneous precipitation, thiol- and carboxylic-based organic films, utilized as model interfaces to mimic the natural organic-abundant environments, further enhanced the sequestration of Se(VI) oxyanions (up to 41–92%) with barite. Such enhancement was kinetically driven by increased nucleation rates of selenate-rich barite having a lower interfacial energy than pure barite. In contrast, only small amounts of Se(IV) oxyanions (∼1%) were detected in heterogeneous coprecipitates mainly due to a lower saturation index of BaSeO3 and deprotonation degree of Se(IV) oxyanion at pH 5.6. These roles of nanoscale mineralization mechanisms observed during composition selection of Se-barite could mark important steps toward the remediation of contaminants through coprecipitation.

Purpose Although the use of online technology has generated excitement over its potential to increase access to education, most existing research has focused on comparing online and in-person student performance. This study provides empirical evidence that semiprivate space at the family level affects students' access to online education. Design/methodology/approach Students from 1,565 low-income households in China were surveyed, and a multivariate logistic regression analysis was conducted on the hypothesized factors that affect access to online education at home. Findings The results show that the absence of computers, smartphones and broadband networks at home severely hinders children's access to online education, and even leads to their exclusion from it. Children with their fathers or paternal grandfathers as guardians have a lower probability of receiving online education at home. It was also found that the higher the education level of the head of the household, the more likely it is that children will receive online education at home. Originality/value This study is one of the first to examine online accessibility at the family level. It also demonstrates that the semiprivate space at the family level may limit opportunities for students who would otherwise pursue online education at home.

The development of the sharing economy offers opportunities to reduce urban carbon emissions. Unfortunately, few studies have examined the impact of the sharing economy on urban carbon emissions from a holistic view based on the integration of local and neighborhood hierarchies. This paper examines the impact of the sharing economy on urban carbon emissions from 2011 to 2017 using a sample of 275 prefecture-level cities in China. The results show that the development of personal credit information services and digital finance both contribute to curbing urban carbon emissions. Technological innovation is not only beneficial to urban carbon emission reduction, but also has a negative moderating effect on the relationship between economic development and carbon emissions. Spatial spillover effects of the sharing economy help curb carbon emissions in neighboring cities. Finally, policy recommendations are presented to promote the collaborative economy and reduce urban carbon emissions.

This paper provides a new explanation for birth-order effects by considering the genetic similarity between siblings. We develop a quantity--quality trade-off model in which parents form their expectations of possible future children's endowments by observing the performance of their existing children. Our model shows that having a talented first child may weaken parents' incentive to have additional children due to the substitution effect. However, it also may encourage a second birth due to the signaling effect. Without assuming that children of a specific birth order have a biological advantage or more parental attention, this model predicts a birth-order gap in parents' human capital investment, the magnitude of which depends on the endowments of the first child and its predictive power as a signal of the potential endowment of a possible second child.

With the advancement of water ecological protection and water control standard, it is the general trend to upgrade the wastewater treatment plants (WWTPs). The simultaneous removal of nitrogen and phosphorus is the key to improve the water quality of secondary effluent of WWTPs to prevent the eutrophication. Therefore, it is urgent to develop the applicable technologies for simultaneous biological removal of nitrogen and phosphorus from secondary effluent. In this review, the composition of secondary effluent from municipal WWTPs were briefly introduced firstly, then the three main treatment processes for simultaneous nitrogen and phosphorus removal, i.e., the enhanced denitrifying phosphorus removal filter, the pyrite-based autotrophic denitrification and the microalgae biological treatment system were summarized, their performances and mechanisms were analyzed. The influencing factors and microbial community structure were discussed. The advanced removal of nitrogen and phosphorus by different technologies were also compared and summarized in terms of performance, operational characteristics, disadvantage and cost. Finally, the challenges and future prospects of simultaneous removal of nitrogen and phosphorus technologies for secondary effluent were proposed. This review will deepen to understand the principles and applications of the advanced removal of nitrogen and phosphorus and provide some valuable information for upgrading the treatment process of WWTPs.

In this study, a biofilter was developed with a ZVI/PHBV/sawdust (ZPS) composite for treating simulative secondary effluent from wastewater treatment plants. Results showed that effluent concentrations of NO3–N and TP in the ZPS biofilter were stable below 2.0 mg/L and 0.1 mg/L, corresponding to 95% NO3–N removal and 99% TP removal, respectively. Microbial community analysis revealed that the transformation of dominant taxa from Dechloromonas to Clostridium sensu stricto\_7 from 30 d to 120 d suggested that the ZVI-induced succession of dominant fermentation bacteria ensured the stable carbon supply for denitrification. Co-occurrence network analysis showed that the ZVI directly enhanced the interaction of microbial community. Fe-related bacteria occupied a key position in the rare species, which might maintain the function of iron-mediated organic matter decomposition and denitrification. These findings provide an alternative for advanced removal of nitrogen and phosphorus in biofilters packed with ZPS composites.

Climate change is altering the timing and magnitude of snowmelt, which may either directly, or indirectly via global trade, affect agriculture and livelihoods dependent on snowmelt. Here we integrate sub-annual irrigation and snowmelt dynamics and a model of international trade to assess the global redistribution of snowmelt dependencies and risks under climate change. We estimate that 16% of snowmelt used for irrigation is for agricultural products traded globally, of which over 70% is from five countries. Globally, we observe a prodigious snowmelt dependence and risk diffusion, with particularly evident importing of products at-risk in western Europe. In Germany and U.K, respective local fraction of surface-water-irrigated agriculture supply exposed to snowmelt risks could increase from negligible to 16% and 10% under a 2°C warming. Our results reveal the trade-exposure of agricultural supplies, highlighting regions and crops whose consumption may be vulnerable to changing snowmelt even if their domestic production is not.

Objectives This study aimed to investigate the associations between individual-level SES, area-level SES, and their interaction with dementia in China. Methods This study used data from the Second China National Sample Survey on Disability and restricted our finalized analysis to 688,507 participants aged 50 years or older. Dementia was ascertained according to the International Statistical Classification of Diseases, Tenth Revision. Multilevel logistic regression models were fitted to examine the associations between individual-level SES, area-level SES, and their interaction with dementia. Results Participants with higher individual SES were less likely to develop dementia; the risk of dementia decreased by 18% for each standard deviation increase in individual SES (OR=0.82, 95% CI=0.77, 0.88). Advantaged areas were associated with an increased risk of dementia in Chinese adults by 1.52 (95% CI=1.43, 1.62). Analysis of the combination between individual-level SES and area-level SES revealed that as the level of area SES increased, the risk of dementia in lower SES people was significantly higher than in higher SES people (OR=1.09, 95% CI=1.04,1.14). Discussion This study found that people with lower SES living in high-SES areas had a higher risk of dementia than people with lower SES living in low-SES areas. Significant socioeconomic differences in the risk of dementia exist in China, and more attention should be given to low-SES populations living in high-SES areas.

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are membrane lipids of certain soil bacteria, and their relative distributions are used as a proxy for air temperature and soil pH. While temperature is recorded by the degree of methylation, soil pH is reflected by the amount of internal cyclization and the relative abundance of 6-methyl isomers. Since the exact producers of brGDGTs remain enigmatic, the mechanisms underlying their empirical relationships with temperature and soil pH, and thus the reliability of brGDGT-based paleorecords, are not well understood, especially in arid regions where mean annual precipitation (MAP) is less than 500 mm. Here, we evaluate the influence of soil pH and aridity on brGDGT distributions in grassland soils along an aridity transect (MAP = 173–415 mm) in Inner Mongolia. While the absolute and fractional abundance of 6-methyl brGDGTs increases with increasing soil pH and aridity, following the trend in the global surface soil calibration dataset, the degree of cyclization does not. This indicates that in arid regions, soil pH reconstructions based on the relative contribution of 6-methyl brGDGTs are likely more reliable than those based on the degree of cyclization. Furthermore, 5- and 6-methyl brGDGTs respond differently to aridity, supporting prior suggestions that the distribution of brGDGTs could be the result of changes in bacterial community composition instead of the direct physiological alteration of molecular structures by the source organisms. Analysis of the bacterial community composition in the same soil transect indicates that the relative abundance of Acidobacteria, the phylum hosting potential brGDGT source-organisms, shows a poor relationship with aridity. Instead, Verrucomicrobia (r2 = 0.70, p < 0.01), and its subclass Spartobacteria (r2 = 0.70, p < 0.01) in particular, show a significant negative correlation with aridity, resembling that of 5-methyl brGDGTs. Similarly, Actinobacteria are positively correlated with aridity (r2 = 0.59, p < 0.01), following the same trend as that of 6-methyl brGDGTs. The ability of certain cultures of Verrucomicrobia and Actinobacteria to produce iso-C15:0 fatty acids that could serve as building blocks for brGDGTs hints that Verrucomicrobia and Actinobacteria could possibly produce brGDGTs in arid soils.

Studies on academic patent commercialisation are well documented. However, spatial effects are seldom considered, which could lead to potentially misleading analytical results. This study addresses this concern by applying the spatial analysis method to investigate how university-level factors and commercialising academic patents are related. Using a comprehensive dataset of university patents from 1815 Chinese universities in 2016, we find that public research funding of universities, industrial research funding, the number of scientific research personnel, the number of monographs published, and the number of awarded achievements are positively related to the commercialisation of academic patents. However, the number of teaching and research personnel and the number of academic papers published are negatively related. There are positive spatial spillover effects in commercialising academic patents among neighbouring universities, but there will be negative spatial spillover effects in funding competition.