Effects of Soil and Water Conservation Measures on Groundwater Levels and Recharge

Measures of soil and water conservation (SWC) could affect the hydrological process. The impacts of typical measures on groundwater recharge, levels and flow were analyzed based on simulated rainfall experiments and a groundwater model. The three-dimensional finite-difference groundwater flow model (MODFLOW) was calibrated and verified for bare slope, grassland and straw mulching scenarios based on the experiments. The results of the verification in groundwater balance, levels, runoff and flow field all showed that MODFLOW could be applied to study the impact of SWC measures on groundwater. Meanwhile, the results showed the recharge rate (α) and specific yield of the three soil layers (Sy1, Sy2 and Sy3) were the most sensitive parameters to the change in the underlying surface. Then, the impacts of the SWC measures’ construction and destruction on the groundwater regime were studied. The results indicated the measures could strengthen groundwater recharge. The amounts of groundwater recharge, runoff and level were on the order of straw mulching > grassland > bare slope. When the underlying surface was converted from grass and mulching to bare slope, the recharge decreased by 42.2% and 39.1%. It was concluded that SWC measure construction would increase groundwater recharge and the measure destruction would decrease recharge

Effect of Nitrogen on the Viscosity of the Erosive Sediment-Laden Flows

Viscosity is a fundamental hydrodynamic property of erosive flow, but except for the effect of sediment on viscosity, the effect of other erosive substances such as agricultural nitrogen on the characteristics of erosive flow has rarely been studied. This in turn is likely to be an important factor affecting the erosive transport mechanism. In this study, the effect of nitrogen on the viscosity of sediment-laden flow with different levels was investigated by using a self-made dual vertical tube rheometer. It was found that: (i) the viscosity coefficient (μ) of nitrogen-bearing erosive flow is affected by the nitrogen concentration, sediment content, and the physical and chemical properties of the sediment; (ii) the calculation model of the relative viscosity coefficient with the effects of nitrogen, concentration, sediment gradation, and temperature, was constructed, and the validation showed that the model not only has a clear physical meaning but also has a simple calculation method and good calculation accuracy. The results of the study are of great significance for the in-depth understanding of the erosion transport mechanism of erosive flow

Effect of Nitrogen on the Viscosity of the Erosive Sediment-Laden Flows

Viscosity is a fundamental hydrodynamic property of erosive flow, but except for the effect of sediment on viscosity, the effect of other erosive substances such as agricultural nitrogen on the characteristics of erosive flow has rarely been studied. This in turn is likely to be an important factor affecting the erosive transport mechanism. In this study, the effect of nitrogen on the viscosity of sediment-laden flow with different levels was investigated by using a self-made dual vertical tube rheometer. It was found that: (i) the viscosity coefficient (μ) of nitrogen-bearing erosive flow is affected by the nitrogen concentration, sediment content, and the physical and chemical properties of the sediment; (ii) the calculation model of the relative viscosity coefficient with the effects of nitrogen, concentration, sediment gradation, and temperature, was constructed, and the validation showed that the model not only has a clear physical meaning but also has a simple calculation method and good calculation accuracy. The results of the study are of great significance for the in-depth understanding of the erosion transport mechanism of erosive flow

Static Compressive Properties of Polypropylene Fiber Foam Concrete with Concave Hexagonal Unit Cell

For the purpose of studying the influence of fiber on the negative Poisson’s ratio effect of foam concrete, a concave hexagonal unit cell structure of polypropylene fiber foam concrete was proposed. The effects of different fiber volume contents on the structural mechanical parameters, Poisson’s ratio, and energy absorption capacity of the unit cells were studied by static compression of concave hexagonal unit cells and cube specimens. The results show that the compressive strength of foam concrete is reduced by adding polypropylene fiber, and the peak stress of concave hexagonal unit cells decreases less rapidly than that of cube specimens. The proper amount of polypropylene fiber can enhance the deformation ability of the unit cells in foam concrete, and the Poisson’s ratio of the unit cells in foam concrete with 1.5% fiber content is the lowest. In the process of failure of concave hexagonal unit cells, the failure phenomenon is mainly concentrated on the concave surfaces on both sides, and the cracks are distributed in the form of “upper left and lower right” or “lower left and upper right”. When the content of polypropylene fiber is 0.5%, the total energy absorbed by the concave hexagonal cells in the compression deformation process increases by 12.98%

Stability of Air Nucleus in Liquid Water and Cavitation Inception on Marine Engineering

The micro air nucleus widely distributed in the ocean is a necessary condition for the cavitation of hydraulic machinery in seawater. In order to study the stability of air nucleus in seawater and cavitation inception, the computational domain of water molecules with air nucleus was studied using the method of molecular dynamics simulation, and the transient characteristics of air nucleus in liquid water were obtained. The key factors influencing nuclei stability were analyzed. The results showed that air nucleus with a certain mass could maintain the dynamic equilibrium in liquid water. The internal density of air nuclei had a critical value that allowed the nuclei to stably exist in water. The air nuclei mass was the decisive factor in its equilibrium volume in water, and the two were positively correlated. The internal density of air nuclei was negatively correlated with the nuclei radius when the nuclei was stable in water. Liquid surface tension was an important factor affecting the stability of the air nuclei. The larger the initial radius of nuclei, the smaller the water pressure, and the more likely the cavitation occurs

Effects of Calcium Alginate Submicroparticles on Seed Germination and Seedling Growth of Wheat (Triticum aestivum L.)

Calcium alginate (CaAlg) submicroparticles have a potential application in agricultural delivery systems. This study investigated the effects of CaAlg submicroparticles on seed germination and seedling growth of wheat. CaAlg submicroparticles with a Z-average diameter of around 250.4 nm and a measured zeta potential value of about -25.4 mV were prepared and characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDS). After this, the effects of the concentration of CaAlg submicroparticles (10-500 mu g/mL) on germination percentage, seedling length, the number of adventitious roots, chlorophyll content and soluble protein content were evaluated. The results demonstrated a significant increase in the level of germination percentage (9.0%), seedling index (50.3%), adventitious roots (27.5%), seedling length (17.0%), chlorophyll (8.7%) and soluble protein contents (4.5%) at a concentration of 100 mu g/mL. However, an inhibitory effect was observed at a concentration of 500 mu g/mL. The SEM examination showed that CaAlg submicroparticles could be successfully adsorbed onto the surface of the wheat seed. Further studies proved that CaAlg submicroparticles at a concentration of 100 mu g/mL promoted the expression of indole-3-acetic acid (IAA)-related genes (YUCCA9, AUX1, ARF and UGT) in wheat, which resulted in an increase of 69% and 21% in IAA concentration in wheat roots and shoots, respectively

Effects of chitosan nanoparticles on seed germination and seedling growth of wheat (Triticum aestivum L.)

To investigate the effect and mechanism of chitosan nanoparticles (CSNPs) on the germination and seedling growth of wheat (Triticum aestivum L.), we conducted systematic research on the impact of different concentrations (1-100 mu g/mL) of CSNPs and chitosan (CS). The result of energy-dispersive spectroscopy (EDS) and confocal laser scanning microscopy (CLSM) showed that adsorption of CSNPs on the surface of wheat seeds was higher than that of CS. CSNPs had growth promoting effect at a lower concentration (5 mu g/mL) compared with CS (50 mu g/mL). In addition, the application of 5 mu g/mL CSNPs induced the auxin-related gene expression, accelerated indole-3-acetic acid (IAA) biosynthesis and transport, and reduced IAA oxidase activity resulting in the increase of IAA concentration in wheat shoots and roots. The results suggest that CSNPs have positive effect on seed germination and seedling growth of wheat at a lower concentration than CS due to higher adsorption on the surface of wheat seeds. (C) 2018 Elsevier B.V. All rights reserved

Generation and characterization of PBMCs-derived human induced pluripotent stem cell (iPSC) line SDQLCHi051-A from an autism spectrum disorder patient with compound CHD8 gene mutations

CHD8 mutation is a case of genetic related autism spectrum disorder(ASD), In our research, We describe here the derivation of the iPSC line SDQLCHi051-A from a patient with autism spectrum disorder (ASD) due to two heterozygote mutations (c.6728G > A and c.3876 T > G) in the CHD8 gene. The resulting iPSC line has typical iPSCs characteristics, including pluripotency and trilineage differentiation hallmarks

Influence of Gully Land Consolidation on Phreatic Water Transformation in the Loess Hilly and Gully Region

Gully Land Consolidation (GLC) is a proven method to create farmlands and increase crop yields in the Loess Hilly and Gully Region, China. However, GLC influences phreatic water transformation and might cause the farmlands water disasters, such as salinization and swamping. For exploring the influence of GLC on phreatic water transformation and mitigating disasters, a series of indoor experiments were conducted in the artificial rainfall hall. Then, we simulated the phreatic water transformation patterns under more conditions with HYDRUS-3D. Finally, an engineering demonstration in the field was performed to validate our research. The indoor experiments indicated that GLC could increase phreatic water outflow rate 4.39 times and phreatic water coefficient (PWC) 2.86 times with a considerable delay. After calibration and validation with experimental data, the HYDRUS-3D was used to simulate phreatic water transformation under more soil thickness and rainfall intensities. Accordingly, we summarized the relationship among PWC, rainfall intensities, and soil thickness, and therefore suggested a blind ditch system to alleviate farmlands disasters. Field application showed that a blind ditch system could avoid disasters with 3.2 times the phreatic water transformation rate compared to loess. Our research provides implications for sustainable land uses and management in the region with thick soil covers