The Yellow River Delta has abundant land resources, but the land exhibits heavy degeneration because of long-term exposure to harsh natural conditions and improper human activities, and the soil ...quality is poor in some areas. All these factors have adversely affected agricultural development and ecological protection in the Yellow River Delta. This study selected multiple physical and chemical indicators and used principal component analysis (PCA) to construct a minimum data set (MDS) to determine a comprehensive set of indicators for assessing soil quality in the Yellow River Delta. Moreover, a fuzzy logic model was used to assess soil quality and analyze the spatial distribution of the primary land use types in different soil quality grades. The results indicate that the MDS includes six soil indicators: total nitrogen (TN), available phosphorus (AP), available potassium (AK), soil organic matter (SOM), soil salinity (SS) and pH. According to the spatial distribution maps of the indicators, SS gradually declined from the coast to the inland areas, while TN and AP had opposite characteristics. AK and pH were evenly distributed around the study area, and SOM was highest in the center and gradually declined toward the edge of the study area. The soil quality was higher in inland areas than in coastal areas, and most of the study area was classified as grade III. Most of the farmland, forest, and garden plots were distributed in high-grade soil levels, but some of these plots were distributed in areas classified as grades V or VI. Many areas with high soil quality were unused, which indicated that the land resources of the study area should be planned reasonably.
•A minimum data set (MDS) was established for soil quality assessment.•The soil quality values increased from coastal areas to inland areas.•A few of farmland and forest were distributed in low soil quality areas.•Many areas with high soil quality were sill unused.•The result was more detailed than that of other researches.
A ruthenium-catalyzed electrochemical dehydrogenative annulation reaction of aniline derivatives and alkynes has been developed for the synthesis of indoles. Electric current is used to recycle the ...active ruthenium-based catalyst and promote H2 evolution. The electrolysis reaction is operationally convenient as it employs a simple undivided cell, proceeds efficiently in an aqueous solution, and is insensitive to air.
We analyze a coordination game of regime change where the policy maker, who tries to increase the probability of the survival of the regime, commits ex ante to abandon the regime automatically when ...its fundamentals are below a certain threshold. This policy acts as an information transmission mechanism: agents, who decide whether to attack the regime or not, update positively about the fundamentals of the regime when they see that it has not been abandoned, and so they are less likely to attack. Using the commitment ability, the policy maker can thus increase the overall survival probability of the regime.
The microphase separation of polyurethane is the result of thermodynamic incompatibility between the hard and soft segments, which plays a significant role in its micro structure and performance. In ...recent years, many researches about the microphase separation of polyurethane have been reported. However, there is a gap in summarizing the recent advances in the characterization methods and applications about it. To fill in this gap, this paper carefully compared and analyzed the characterization methods of the microphase separation such as Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), Dynamic thermomechanical analyzer (DMA), Atomic force microscopy (AFM), Transmission electron microscopy (TEM), and Small-angle X-ray scattering (SAXS). Moreover, applicaitions of the microphase separated polyurethane in shape memory, water resistance, and gas separation are also discussed in detail.
•The paper systematically compared and analyzed the characterization methods of the polyurethane microphase separation.•Influences of the microphase separation on the physical properties are discussed in detail.•The relationship betwwen the microphase separation and hydrogen bond is summarized.
Soil moisture plays a fundamental role in eco-hydrological processes in the semi-arid Loess Plateau. Catchments on the Loess Plateau can be generally divided into the hillslope domain and gully ...domain. However, the soil moisture variations linked to topographic domains and land use types remain poorly understood. Therefore, in this study, differences in soil moisture among three typical land use types (forestland, native grassland, and farmland) were investigated and compared between the spatial domains of hillslope and gully in the Jiegou catchment on the semi-arid Loess Plateau of China. Additionally, the spatial variations in the soil moisture of the 0–100 cm layers were explored in both wet and dry periods to evaluate the seasonal effects of different spatial domains and land use types. The results showed that including gully soil moisture weakly increased the spatially averaged soil moisture in the catchment but obviously increased the variability during wet periods. In contrast, the spatial means decreased weakly while the variability obviously decreased during dry periods. Soil moisture in forestland was lower than that in native grassland and farmland at all spatial domains during both wet and dry periods. The results also indicated that surface soil moisture (0–10 cm) differs between spatial domains but not land use types, which mainly due to the differences of evapotranspiration on the two topographic domains. In contrast, deep soil moisture (80–100 cm) differs among land use types but not spatial domains, which because of the differences of root water uptake among land use types. In addition, slope aspect played a more important role than slope gradient and elevation in the distribution of soil moisture at the hillslope domain. This was because the slope aspect affected the ground temperature by receiving different solar radiation, and further affected the soil evaporation and vegetation transpiration. Therefore, the results of this study indicates that both topographic domains and land use types should be considered when attempting to characterize soil moisture variability or modelling surface hydrological processes at catchment scale in heavily gullied regions.
•The presence of gullies clearly changed soil moisture spatial variability, but had weak effects on spatial means.•Both spatial means and spatial variability of soil moisture related to spatial domains and land use types.•Variations in soil moisture were different between wet and dry periods in water-limited regions.•Slope aspect played a more important role than slope gradient and elevation in soil moisture distribution in gullied regions.
Preserving the utility of published datasets while simultaneously providing provable privacy guarantees is a well-known challenge. On the one hand, context-free privacy solutions, such as ...differential privacy, provide strong privacy guarantees, but often lead to a significant reduction in utility. On the other hand, context-aware privacy solutions, such as information theoretic privacy, achieve an improved privacy-utility tradeoff, but assume that the data holder has access to dataset statistics. We circumvent these limitations by introducing a novel context-aware privacy framework called generative adversarial privacy (GAP). GAP leverages recent advancements in generative adversarial networks (GANs) to allow the data holder to learn privatization schemes from the dataset itself. Under GAP, learning the privacy mechanism is formulated as a constrained minimax game between two players: a privatizer that sanitizes the dataset in a way that limits the risk of inference attacks on the individuals’ private variables, and an adversary that tries to infer the private variables from the sanitized dataset. To evaluate GAP’s performance, we investigate two simple (yet canonical) statistical dataset models: (a) the binary data model; and (b) the binary Gaussian mixture model. For both models, we derive game-theoretically optimal minimax privacy mechanisms, and show that the privacy mechanisms learned from data (in a generative adversarial fashion) match the theoretically optimal ones. This demonstrates that our framework can be easily applied in practice, even in the absence of dataset statistics.
Even though polyurethane (PU) has been widely applied, its hydrophobicity is inadequate for certain applications. As such, the development of superhydrophobic polyurethane (SHPU) has recently ...attracted significant attention, with numerous motivating reports in recent years. However, a comprehensive review that summarizes these state-of-the-art developments remains lacking. Thus, this review aims to fill this gap by reviewing the recent preparation methods for SHPU based on superhydrophobic theories and principles. Three main types of methods used in promoting the hydrophobicity of PU are emphasized in this review: (1) incorporation of silicide or fluoride to lower the surface energy; (2) creation of micro/nano-scale rough surfaces by electrospinning or grafting of nanoparticles; and (3) integrating the earlier two methods to develop a synergistic approach. Furthermore, this review also discussed the various applications of SHPU in oil spill treatment, protective coating, self-healing materials and sensors.
Display omitted
•The development of superhydrophobic polyurethane in recent years was reviewed.•The design idea of superhydrophobic polyurethane was divided into three parts: Incorporating low surface energy substance; Construction of rough surfaces on PU; Surface energy reduction and surface roughness generation approach.•The potential applications of superhydrophobic polyurethane were classified and illustrated.•The prospect of the development of superhydrophobic polyurethane was discussed.
In recent years, decreased runoff and sediment, intensified storm surge and seawater intrusion, urbanization, petroleum exploration, and production, and other factors have gradually deteriorated the ...unique wetland ecosystem in the Yellow River Delta (YRD). Although previous studies have analyzed the relationships between vegetation and soil properties at different scales, few studies have documented quasi-circular vegetation patches (QVPs) in the YRD, which appear to exhibit faster succession rates that make them ideal for studies on the relationships between vegetation and soil properties. Therefore, this study investigated differences in soil physicochemical properties at 0–20 cm depths between QVPs and inter-QVP bare soil areas, among QVPs, and among plant species communities. Additionally, spatial variations in soil physicochemical properties were explored in south-north and west-east transects across and within QVPs. The results showed that soils beneath QVPs had significant fertility island effects associated with soil organic matter (SOM) and total nitrogen (TN). Furthermore, these areas were richer in clay content, showed slightly higher pH values, and exhibited less available phosphorus (APH), available potassium (APO), total salt content, and silt content than those of bare soil areas. A multiple independent samples nonparametric Kruskal-Wallis H test detected significant differences in SOM, TN, APH, and pH among 18 QVPs, but no significant differences were found in APO, total salt content, sand, silt, and clay contents. Regardless of plant species, different plant species communities had significant effects on soil physicochemical properties. Particularly, soils underneath plant species communities with Tamarix chinensis were richer in SOM and TN, and they contained less APH, APO, and total salt content than those without T. chinensis. In each QVP, values of SOM and TN in soil samples along the patch perimeter were less than those of samples located midway toward the perimeter, and these values were less than those of samples centered in the patch. However, APO and total salt content values exhibited opposite changes from the perimeter to the center of the patch. The results also indicated significant differences in SOM, TN, APH, APO, and pH between south-north transect A and west-east transect B across QVPs, but no significant differences were found in total salt content, sand, silt, and clay contents. Therefore, the results of this study indicate that QVPs have significant effects on topsoil nutrients and salinity but little effects on soil texture. Furthermore, the occurrence and development of QVPs are associated with suitable soil conditions, including higher clay fractions and lower total salt content values.
•Properties of soils in quasi-circular vegetation patches (QVPs) were examined.•Soils lying beneath QVPs exhibited significant fertility island effects.•QVPs significantly affected topsoil nutrients and salinity.•Variations in soil properties were affected by QVPs and plant species communities.
C‐aryl glycosides are popular basic skeletons in biochemistry and pharmaceutical chemistry. Herein, ruthenium‐catalyzed highly stereo‐ and site‐selective ortho‐ and meta‐CAr−H glycosylation is ...described. A series of C‐aryl pyranosides and furanosides were synthesized by this method. The strategy showed good substrate scope, and various N‐heterocyclic directing groups were compatible with the reaction system. A mechanistic study suggested that the key pathway of ortho‐CAr−H glycosylation might involve oxidative addition/reduction elimination, whereas aryl meta‐C−H glycosylation was mediated by σ‐activation. Density functional theory calculations also showed that the high stereoselectivity of meta‐CAr−H glycosylation was due to steric hindrance.
A series of C‐aryl pyranosides and furanosides were synthesized by ruthenium‐catalyzed ortho‐ and meta‐CAr−H glycosylation. Mechanistic studies suggest that the key pathway of ortho‐CAr−H glycosylation involves an oxidative addition/reductive elimination process, while aryl meta‐C−H glycosylation is mediated by σ‐activation. DFT calculations showed that steric hindrance is responsible for the high stereoselectivity of meta‐CAr−H glycosylation.
PDF
