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Phosphorus (P) deficiency in agricultural soil is a worldwide concern. P modification of biochar, a common soil conditioner produced by pyrolysis of wastes and residues, can increase P availability and improve soil quality. This study aims to investigate the effects of P-modified biochar as a soil amendment on the growth and quality of a medicinal plant ( Pseudostellaria heterophylla ). P. heterophylla were grown for 4 months in lateritic soil amended with P-modified and unmodified biochar (peanut shell) at dosages of 0, 3% and 5% (by mass). Compared with unmodified biochar, P-modified biochar reduced available heavy metal Cd in soil by up to 73.0% and osmotic suction in the root zone by up to 49.3%. P-modified biochar application at 3% and 5% promoted the tuber yield of P. heterophylla significantly by 68.6% and 136.0% respectively. This was different from that in unmodified biochar treatment, where tuber yield was stimulated at 3% dosage but inhibited at 5% dosage. The concentrations of active ingredients (i.e., polysaccharides, saponins) in tuber were increased by 2.9–78.8% under P-modified biochar amendment compared with control, indicating the better tuber quality. This study recommended the application of 5% P-modified biochar for promoting the yield and quality of P. heterophylla .

Understanding the interaction between complex geophysical flows and barriers remains a critical challenge for protecting infrastructure in mountainous regions. The scientific challenge lies in understanding how grain stresses in complex geophysical flows become manifested in the dynamic response of a rigid barrier. A series of physical flume tests were conducted to investigate the influence of varying the particle diameter of mono-dispersed flows on the impact kinematics of a model rigid barrier. Particle sizes of 3, 10, 23 and 38 mm were investigated. Physical tests results were then used to calibrate a discrete element model for carrying out numerical back-analyses. Results reveal that aside from considering bulk characteristics of the flow, such as the average velocity and bulk density, the impact load strongly depends on the particle size. The particle size influences the degree of grain inertial stresses which become manifested as sharp impulses in the dynamic response of a rigid barrier. Impact models that only consider a single impulse using the equation of elastic collision warrant caution as a cluster of coarse grains induce numerous impulses that can exceed current design recommendations by several orders of magnitude. Although these impulses are transient, they may induce local strucutral damage. Furthermore, the equation of elastic collision should be adopted when the normalized particle size with the flow depth, δ/h, is larger than 0.9 for Froude numbers less than 3.5.

A common practice for disposing of municipal waste is to dump it in landfills, where it is then protected by a cover system. The main purpose of this cover system is to minimise the amount of water percolating into the waste and, hence, to reduce the excessive formation of leachate. To achieve this objective, conventional landfill covers employ low permeability materials, such as composite liners, to meet the permeability design criterion. However, their long-term hydraulic behaviour, cost and shear resistance are not entirely satisfactory. Increasingly, covers with capillary barrier effects (CCBEs) have been considered as an alternative cover system in semi-arid and arid regions. It is questionable, however, whether CCBEs can be successfully applied in humid climate conditions where the annual rainfall often exceeds 2000 mm. In this paper, an alternative three-layer capillary barrier cover system for use in humid climates is proposed, and its feasibility is investigated by a numerical parametric study. This alternative system consists of a fine-grained soil layer overlaying a coarse-grained layer, which in turn overlies a fine-grained soil, such as clay, to minimise water percolation in humid climates. This bottom clay layer is protected by the upper two coarser soil layers. The factors considered in the numerical parametric finite element analyses include the thickness of this additional clay layer, rainfall conditions and degrees of saturation of the municipal waste. It was verified that the middle sand layer serves as a capillary break when the rainfall intensity is light or the duration is short. After the upper two layers are permeated, the bottom clay layer serves as an impeding layer, whereas the sand layer shifts to serve as a lateral drainage layer. It was also found that the amount of percolation increases with an increase in rainfall duration but decreases with saturation of the waste. Based on the six simulated durations of rainfall, the most severe rainfall duration is 1 day, irrespective of the return period.

Baffles and check-dam systems are often used as granular flow (rock avalanches, debris flows, etc.) control structures in regions prone to dangerous geological hazards leading to massive landslides. This paper explores the use of numerical modelling to simulate large volume granular flow and the effect of the presence of baffles and check dam systems on granular flow. In particular, the paper offers a solution based on the smoothed particle hydrodynamics numerical method, combined with a modified Bingham model with Mohr–Coulomb yield stress for granular flows. This method is parallelised at a large scale to perform high-resolution simulations of sand flowing down an inclined flume, obstructed by rigid control structures. We found that to maximise the flow deceleration ability of baffle arrays, the design of baffle height ought to reach a minimum critical value, which can be quantified from the flow depth without baffles (e.g. 2.7 times for frictional flows with friction angle of 27.5°). Also, the check-dam system was found to minimise run-out distances more effectively but experiences substantially higher forces compared to baffles. Finally, flow-control structures that resulted in lower run-out distances were associated with lower total energy dissipation, but faster kinetic energy dissipation in the granular flows; as well as lower downstream peak flow rates.

Random field theory has been increasingly adopted to simulate spatially varying environmental properties and hydrogeological data in recent years. In a two-dimensional (2D) stochastic analysis, variation of the environmental properties or hydrogeological data along different directions can be similar (i.e., isotropic) or quite different (i.e., anisotropic). To model the spatially isotropic or anisotropic variability in a stochastic analysis, conventional random field generators generally require a vast amount of measurement data to identify the random field parameters (e.g., mean, variance, and correlation structure and correlation length in different directions). However, measurement data available in practice are usually sparse and limited. The random field parameters estimated from sparse measurements might be unreliable, and the subsequent random field modeling or stochastic analysis might be misleading. This underscores the significance and challenge of generating 2D isotropic or anisotropic random fields from sparse measurements. This paper develops a novel 2D random field generator, which does not require a parametric form of correlation function or estimation of correlation length and other random field parameters, and directly generates 2D isotropic or anisotropic random field samples from sparse measurements. The proposed generator is highly efficient because simulation of a 2D random field is achieved by generation of a short 1D random vector. The effectiveness and applicability of the proposed generator are illustrated using isotropic and anisotropic numerical examples.

T helper 17 (T H 17) lymphocytes protect mucosal barriers from infections, but also contribute to multiple chronic inflammatory diseases. Their differentiation is controlled by RORγt, a ligand-regulated nuclear receptor. Here we identify the RNA helicase DEAD-box protein 5 (DDX5) as a RORγt partner that coordinates transcription of selective T H 17 genes, and is required for T H 17-mediated inflammatory pathologies. Surprisingly, the ability of DDX5 to interact with RORγt and coactivate its targets depends on intrinsic RNA helicase activity and binding of a conserved nuclear long noncoding RNA (lncRNA), Rmrp , which is mutated in patients with cartilage-hair hypoplasia. A targeted Rmrp gene mutation in mice, corresponding to a gene mutation in cartilage-hair hypoplasia patients, altered lncRNA chromatin occupancy, and reduced the DDX5–RORγt interaction and RORγt target gene transcription. Elucidation of the link between Rmrp and the DDX5–RORγt complex reveals a role for RNA helicases and lncRNAs in tissue-specific transcriptional regulation, and provides new opportunities for therapeutic intervention in T H 17-dependent diseases. The ability of the DEAD-box RNA helicase DDX5 to interact with master transcription factor RORγt is dependent on binding of the long noncoding RNA Rmrp ; the DDX5–RORγt complex coordinates transcription of selective T H 17 genes and is required for the pathogenicity of T H 17 cells. Modifiers of T H 17 cell pathogenicity The ability of the DEAD-box RNA helicase DDX5 to interact with master transcription factor RORγt is shown to be dependent on binding of the long noncoding RNA Rmrp . The DDX5–RORγt complex coordinates transcription of selective T-helper 17 (T H 17) genes, and is required for the pathogenicity of T H 17 lymphocytes. The discovery of this relationship between an RNA helicase and a long noncoding RNA in complex provide new insight into the role of transcriptional regulation and suggests new avenues for research into T H 17-dependent diseases.

A full-scale field study was conducted to investigate the effects of rainfall infiltration on a natural grassed expansive soil slope in China. A 16 m wide × 28 m long area was selected for instrumentation. The instrumentation included jet-filled tensiometers, moisture probes, a tipping bucket rain gauge, and a vee-notch flow meter. One artificial rainfall event amounting to about 370 mm rain depth in total was applied to the slope. The monitored results suggested that there was about a 3 day delay in the response of surface runoff, pore-water pressure, and water content to the commencement of the simulated rainfall. The depth of influence of the rainfall, depending on the elevation along the slope, ranged from 2.8 to 3.5 m. Positive pore-water pressures were measured within the influence depth, and there existed significant subsurface downslope flow at the end of the simulated rainfall, particularly near the lower part of the slope. A comparison of infiltration rates between the grassed area and a bare area nearby indicated that the presence of grass significantly increased the infiltration rate and reduced surface runoff. The cracks and fissures developed in the unsaturated expansive soil played an important role in the hydrological process.Key words: expansive soil, slope instability, infiltration, vegetation cover, grass, soil suction, water content, unsaturated soil.

Tropical cyclones (TCs) are expected to produce more intense precipitation under global warming. However, substantial uncertainties exist in the projection of coarse-resolution global climate models. Here, we use deep learning to aid targeted cloud-resolving simulations of extreme TCs. Contrary to the Clausius-Clapeyron (CC) scaling, which indicates a 7% moisture increase per K warming, our simulations reveal more complex responses of TC rainfall. TCs will not intensify via strengthened updrafts but through the expansion of deep convective cores with suppression of shallow cumulus and congestus. Consequently, while localized hourly rainfall may adhere to the CC scaling, precipitation accumulation over city-sized areas could surge by 18%K -1 . This super-CC intensification due to changing TC structure has profound implications for floods and landslides. Estimations using Hong Kong’s slope data confirm this concern and suggest an up to 215% increase in landslide risks with 4-K warming, highlighting amplified threats from compound disasters under climate change.

Segmented filamentous bacteria drive the acquisition of the T H 17 phenotype in an antigen-specific manner; these findings begin to elucidate how gut-induced T H 17 cells can contribute to distal organ-specific autoimmune disease. T H 17 cell differentiation linked to intestinal bacteria Colonization of the small intestine by microbes such as segmented filamentous bacteria is known to enhance the induction of T-helper-17 (T H 17) cells, which are important factors in both mucosal defence and in autoimmune disease pathogenesis. Here Dan Littman and colleagues demonstrate that the vast majority of T H 17 cells in mice colonized with segmented filamentous bacteria are directed at antigens encoded by these bacteria, and identify specific bacterial epitopes that are recognized by T H 17 T-cell receptors. This work provides insights into how microbiota communicate with the host immune system, and suggests possible routes for developing novel mucosal vaccines. T-helper-17 (T H 17) cells have critical roles in mucosal defence and in autoimmune disease pathogenesis 1 , 2 , 3 . They are most abundant in the small intestine lamina propria, where their presence requires colonization of mice with microbiota 4 , 5 , 6 , 7 . Segmented filamentous bacteria (SFB) are sufficient to induce T H 17 cells and to promote T H 17-dependent autoimmune disease in animal models 8 , 9 , 10 , 11 , 12 , 13 , 14 . However, the specificity of T H 17 cells, the mechanism of their induction by distinct bacteria, and the means by which they foster tissue-specific inflammation remain unknown. Here we show that the T-cell antigen receptor (TCR) repertoire of intestinal T H 17 cells in SFB-colonized mice has minimal overlap with that of other intestinal CD4 + T cells and that most T H 17 cells, but not other T cells, recognize antigens encoded by SFB. T cells with antigen receptors specific for SFB-encoded peptides differentiated into RORγt-expressing T H 17 cells, even if SFB-colonized mice also harboured a strong T H 1 cell inducer, Listeria monocytogenes , in their intestine. The match of T-cell effector function with antigen specificity is thus determined by the type of bacteria that produce the antigen. These findings have significant implications for understanding how commensal microbiota contribute to organ-specific autoimmunity and for developing novel mucosal vaccines.

Purpose Biochar has long been proposed for amending agricultural soils to increase soil-water retention capacity and therefore promotes crop growth. Recent studies revealed the potential use of biochar-amended soil in landfill final covers to promote methane oxidation and odor reduction. However, the effects of biochar application ratio, compaction water content (CWC), and degree of compaction (DOC) on soil-water retention characteristics of biochar-amended clay (BAC) at high soil suction (dry condition) are not well understood. The present study aims to overcome this knowledge gap. Materials and methods Soil suction was induced using vapor equilibrium technique by a temperature- and humidity-controlled chamber, and the water desorption (drying) and adsorption (wetting) water retention curves (WRCs) of compacted pure kaolin clay and peanut shell BAC with different biochar application ratios (0, 5, and 20 %, w / w ), DOCs (80, 90, and 100 %), and CWCs (30 and 35 %) were measured. The correlations between these factors and the gravimetric water content were analyzed by three-way ANOVA followed by the Tukey HSD test. The soil micro-structure was studied by scanning electronic microscope with energy-dispersive X-ray spectroscopy. Results and discussion Measured WRCs of BAC suggest that the soil-water retention capacity at high suction range (48.49–124.56 MPa) was in general increased, upon biochar application. The BAC compacted with CWC of 35 % at low (80 %) and high (100 %) DOCs for the 5 % BAC were increased by 7.30 and 9.77 %, when compared with clay, while the increases of 20 % BAC were 39.89 and 59.20 %, respectively. This is attributed to the embedded effects of clay particles in biochar pores, which reduce the total pore space of BAC. The soil-water retention capacity of BAC was also increased with CWC and decreased with DOC. The results of three-way ANOVA analysis show that the effects of DOC and biochar ratio on soil gravimetric water content was significant ( p  < 0.05) only at 48.49 MPa on drying path. For other induced suctions, only effects of CWC were significant ( p  < 0.05). Conclusions Biochar application increases soil-water retention capacity of the BAC at high soil suction (48.49–124.56 MPa) (dry condition) at both low (80 %) and high DOC (100 %). The soil-water retention capacity of 20 % BAC was much higher than that of 5 % BAC. BAC is a potential alternative landfill final cover soil with a higher soil-water retention capacity to be used in dry areas or regions with a long period of evaporation event.