Developing highly efficient and low‐cost photocatalysts for overall water splitting has long been a pursuit for converting solar power into clean hydrogen energy. Herein, we demonstrate that a ...nonstoichiometric nickel–cobalt double hydroxide can achieve overall water splitting by itself upon solar light irradiation, avoiding the consumption of noble‐metal co‐catalysts. We employed an intensive laser to ablate a NiCo alloy target immersed in alkaline solution, and produced so‐called L‐NiCo nanosheets with a nonstoichiometric composition and O2−/Co3+ ions exposed on the surface. The nonstoichiometric composition broadens the band gap, while O2− and Co3+ ions boost hydrogen and oxygen evolution, respectively. As such, the photocatalyst achieves a H2 evolution rate of 1.7 μmol h−1 under AM 1.5G sunlight irradiation and an apparent quantum yield (AQE) of 1.38 % at 380 nm.
A single‐phase photocatalyst, a hydrogen‐deficient nickel–cobalt double hydroxide, was generated by laser ablation. This photocatalyst can drive overall water splitting under solar light irradiation in the absence of sacrificial agents and noble metal co‐catalysts because of its unique composition and structure, with partially removed hydrogen atoms as well as O2− and Co3+ ions exposed on the surface.
Water erosion is a time-varying processes controlled by both rainfall and overland flow. A better understanding of dynamic changes in the sediment load and size distribution with various erosive ...forces can help to develop and verify erosion models. Here, a total of 11 laboratory simulation experiments were conducted in a 1 m by 3 m flume with 3 storm rainfall intensities (60, 90, 120 mm h−1) and 2 inflow rates (5, 7.5 L min−1) on a silty clay red soil. Time-series measurements of the quantity and size distribution of eroded materials were made during 50 min rainfall/inflow time. The mean weight diameter of the effective sediment, sediment enrichment ratio, average stream power and rainfall power were measured and calculated. Fine sediment particles were associated with the short-lived initial stage, which was combined with sheet flow erosion and splash erosion, whereas coarse particles were associated with the rill development and rill stable stages, which were dominated by rill erosion and interrill erosion, respectively. The <0.05 mm aggregates were transported preferentially by the suspension/saltation mechanism, while 0.105–0.25 mm aggregates resisted transportation. Additionally, the sediment load rate showed a significant linear correlation with the stream power at the sheet flow (R2 = 0.84, p < 0.01) and rill development (R2 = 0.72, p < 0.01) stages as well as the rainfall power at the rill development (R2 = 0.76, p < 0.01) and rill stable stages (R2 = 0.78, p < 0.01). Sediment size increased with increasing stream power (p < 0.05) and rainfall power (p < 0.05) only at the rill development stage. The erosion processes play a major role in particle selection, and the erosion forms, aggregate breakdown and soil surface structure development should be considered for a more accurate prediction of size selectivity and the related sediment quality.
•Erosion processes were simulated under the combined effect of rainfall and overland flow.•The dynamic changes of sediment size distribution over time were affected by erosion forms.•Aggregates finer than 0.05 mm were transported preferentially by the suspension/saltation mechanism.•The relationships between erosion forces and sediment load changed with erosion process.
•The effects of plant roots on rill erosion were studied under contrasting textured soils.•Sand content significantly affected root biomass traits.•Erosion-reducing effects of root traits were less ...efficient in heavy-textured soils.•Plant with dense fibrous roots could be the optimal species mixtures to stable sandy slopes.
The effects of plant roots on water erosion are likely to vary according to the range of root traits and soil textures. However, little is known about the erosion-reducing potential of roots under different soil textures due to the lack of sufficient texture variations which come from a comparable system. In this study, we systematically investigate how root functional traits respond to soil sand contents and their combined effects on rill erosion. Seeding of Cynodon dactylon (L.) Pers. were grown in a greenhouse under varied proportions of sand mass (ranging from 14% to 83%) by mixing silty clay soil (Ultisols derived from quaternary red clay) and engineering sand. After six months growing, the root-soil composites were subjected to concentrated flow in a hydraulic flume to obtain soil detachment capacity (Dc), then roots were separated to measure their morphology and architecture traits. The results showed that sand content significantly affected root morphology traits (e.g., RD and RLD) (p < 0.01). In contrast, root architecture traits (e.g., root fractal dimension, topological index and radius frequency distribution function) showed no significant changes with soil texture (p > 0.05). Generally, root strongly promoted soil cohesion and they mitigated rill erodibility in a coordinated way. Rill erodibility was mostly determined by soil texture even in soils with dense roots, and the erosion-reducing effects of roots were less efficient in heavy-textured soils. Moreover, no significant correlations were found between critical flow shear stress (τc) and root traits, and soil with a loam texture displayed the lowest τc. Those relationships are likely to exist elsewhere, but its strength and direction could be changed according to the root trait variability and the varied root-soil feedbacks. The results of this study would be quite relevant for soil erosion modeling and imply the bare sandy soils are more urgent to be recovered during engineering constructions. Moreover, the inclusion of plant with dense fibrous roots could be the optimal species mixtures to stable sandy slopes.
The breakdown of soil aggregates under rainfall and their abrasion in overland flow are important processes in water erosion due to the production of more fine and transportable particles and, the ...subsequent significant effect on the erosion intensity. Currently, little is known about the effects of sediment load on the soil aggregate abrasion and the relationship of this abrasion with some related hydraulic parameters. Here, the potential effects of sediment load on soil aggregate abrasion and hydraulic parameters in overland flow were investigated through a series of experiments in a 3.8-m-long hydraulic flume at the slope gradients of 8.7 and 26.8%, unit flow discharges from 2×10−3 to 6×10−3 m2 s−1, and the sediment concentration from 0 to 110 kg m−3. All the aggregates from Ultisols developed Quaternary red clay, Central China. The results indicated that discharge had the most significant (P>0.01) effect on the aggregates abrasion with the contributions of 58.76 and 60.34%, followed by sediment feed rate, with contributions of 39.66 and 34.12% at the slope gradients of 8.7 and 26.8%, respectively. The abrasion degree of aggregates was found to increase as a power function of the sediment concentration. Meanwhile, the flow depth, friction factor, and shear stress increased as a power function along with the increase of sediment concentration at different slope gradients and discharges. Reynolds number was obviously affected by sediment concentration and it decreased as sediment concentration increased. The ratio of the residual weight to the initial weight of soil aggregates (Wr/Wi) was found to increase as the linear function with an increasing flow depth (P=0.008) or Reynolds number (P=0.002) in the sediment-laden flow. The Wr/Wi values followed a power function decrease with increasing friction factor or shear stress in the sediment-laden flow, indicating that friction factor is the best hydraulic parameter for prediction of soil aggregate abrasion under different sediment load conditions. The information regarding the soil aggregate abrasion under various sediment load conditions can facilitate soil process-based erosion modeling.
•A linear source infiltrability measurement system was applied to capture the complete infiltration processes.•Grasses promote soil physical properties and infiltrability better than shrubs in ...heavy-textured soil.•The effects of plant roots on soil infiltrability are mediated via soil aggregate stability and soil porosity.•Species mixtures require inclusion of high fine root length density grasses to mitigate overland flow and erosion.
Soil degradation impairs ecosystem functions, and vegetation restoration is a major eco-engineering method that is used to restore soils globally. Despite the fundamental role that plants play in enhancing soil functions and ecosystem services, little is known about the relationships among root traits, soil physical properties, and water infiltration. The objectives of this study were to therefore evaluate changes in soil infiltrability due to different vegetation types and identify soil properties and root trait predictors of variation in soil infiltrability. The influences of four plant species (two gramineous grasses and two leguminous shrubs) on physical properties of soil and water infiltration in heavy-textured soils with 43 % clay content following five years of restoration after surface soil removal were investigated. These data were subsequently incorporated into a conceptual path model to quantify the direct and indirect effects of root traits and root-induced soil properties on infiltration. Soil organic matter, aggregate stability, soil total porosity, and non-capillary porosity were significantly higher in planted soil than in bare soil (p < 0.05), following the order of grass-planted > shrub-planted > bare soils. The infiltration rates during the initial and steady states were 63 % and 38 % higher in grass-planted soils than in shrub-planted soils, respectively. Among all evaluated root traits, fine root length density was the best predictor of these changes. Furthermore, the conceptual path model explained 82 % of the variance in water infiltration and confirmed the important role of roots in soil infiltration. Modeling indicated that this might not be a direct effect, but is rather mediated via soil physical properties like soil aggregate stability and soil porosity. These observations have important implications for designing efficient strategies in restoration of human-induced disturbed soils to mitigate overland flows and erosion.
This paper analyzes runoff and soil loss in relation to the rainfall regimes and land use changes in a small mountainous watershed in the Three Gorges Area (TGA) of China. Based on 10years of ...rainfall measurements and K-means clustering, 152 rainfall events were classified into three rainfall regimes. The mean statistical features of different rainfall regimes display a marked difference. Rainfall Regime I is events of medium amounts (31.8mm) and medium duration (1371min). Rainfall Regime II is events with high amounts (54.0mm), long duration (2548min), and an infrequent occurrence. Rainfall Regime III is events of low amount (22.2mm), short duration (494min) and high frequency. Each rainfall regime results in differing levels of runoff and erosion and Rainfall Regime I causes the greatest proportion of accumulated discharge (368.7mm) and soil loss (4283t). In the different rainfall regimes, the values of the mean runoff coefficient and the mean sediment load were ordered as follows: Rainfall Regime II>Rainfall Regime I>Rainfall Regime III. These results suggest that greater attention should be paid to Rainfall Regimes I and II because they had the most erosive effect. In the Wangjiaqiao watershed, the changes in land use primarily affected the paddy fields, where the cropland decreased significantly and the forest and orchards increased by 9.9% and 7.7%, respectively, during 1995–2004. The ANOVA shows land use changes caused significant decreasing trends in the runoff coefficients (P<0.01) and sediment loads (P<0.01). In order, the most sensitive response of runoff and erosion to land use was Rainfall Regime II>Rainfall Regime>Rainfall Regime III. Rainfall characteristics are decisive for the relative importance of different storm runoff generation mechanisms. The land use changes in the study watershed have considerably decreased runoff and soil loss.
► Rainfall events were classified into three rainfall regimes. ► Most of the sediment load was produced by a small number of runoff events. ► Rainfall depth was the most relevant factor controlling the hydrological response. ► Land use changes caused significant decreasing trends in runoff and sediment load.
A novel micelle based on heparosan and deoxycholic acid (DOCA) conjugate (HD) as drug carrier was reported here. As the surface was negatively charged, this micelle could resist serum adsorption, ...showing favorable stability. Moreover, fluorescence observation confirmed that it was able to deliver model hydrophobic drug doxorubicin (DOX) into HeLa cells efficiently. The DOX-loaded micelles showed sustained release behavior at pH 7.4, and accelerated release behavior at pH 5.0 or in the presence of β-glucuronidase, which over-expressed in tumor cells. In vitro cytotoxicity assay demonstrated that the half-maximal inhibitory concentration (IC50) of DOX-loaded micelles against HeLa cells was much lower than that of COS7 cells, showing significant therapeutic distinction between tumor cells and normal cells. Combining with the good biocompatibility and biodegradability of heparosan, this micelle may be promising in clinical application for targeted drug delivery.
This communication describes a new study of microstructures of double network (DN) gels, which were prepared in two steps: firstly, an across‐linked polymer (the first network) was prepared, and then ...the other compound (the second network) was synthesized in the first network. A novel micro/nanostructure has been found in the DN gels. Meanwhile, solid composites with micro/nanostructures have been obtained as well.
A novel micro/nanostructure has been found in a superabsorbent polymer with double networks for the first time. This study not only provides an effective way to study the microstructure of the superabsorbent polymers and gels with different networks, but also opens up new possibilities for making full use of them to fabricate functional materials with unique structures and special properties.
Developing highly efficient and low‐cost photocatalysts for overall water splitting has long been a pursuit for converting solar power into clean hydrogen energy. Herein, we demonstrate that a ...nonstoichiometric nickel–cobalt double hydroxide can achieve overall water splitting by itself upon solar light irradiation, avoiding the consumption of noble‐metal co‐catalysts. We employed an intensive laser to ablate a NiCo alloy target immersed in alkaline solution, and produced so‐called L‐NiCo nanosheets with a nonstoichiometric composition and O2−/Co3+ ions exposed on the surface. The nonstoichiometric composition broadens the band gap, while O2− and Co3+ ions boost hydrogen and oxygen evolution, respectively. As such, the photocatalyst achieves a H2 evolution rate of 1.7 μmol h−1 under AM 1.5G sunlight irradiation and an apparent quantum yield (AQE) of 1.38 % at 380 nm.
A single‐phase photocatalyst, a hydrogen‐deficient nickel–cobalt double hydroxide, was generated by laser ablation. This photocatalyst can drive overall water splitting under solar light irradiation in the absence of sacrificial agents and noble metal co‐catalysts because of its unique composition and structure, with partially removed hydrogen atoms as well as O2− and Co3+ ions exposed on the surface.
Two strains of Fusarium sinensis sp. nov. were isolated from the seeds and roots of wheat (Triticum aestivum L.) in Shandong Province, China. They are superficially similar to F. dlaminii in ...producing fusiform-to-reniform and napiform microconidia and chlamydospores in almost the same size range as F. dlaminii. However the colonies and chlamydospores of F. sinensis resemble those of species in sections Roseum, Gibbosum and Discolor. Phylogenetic analysis of partial translation elongation factor 1α (EF-1α) sequence data indicates that F. sinensis is closely related to but distinct from the F. avenaceum/F. tricinctum/F. acuminatum species complex.
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