This study theoretically investigated the dynamic responses of a multilayered half-space subjected to a spatially periodic harmonic moving load using the direct stiffness method. First, a periodic ...model of the multilayered half-space was established. Based on the generalised modal functions and Fourier transform, the direct stiffness matrices relating displacements and tractions along layer interfaces for both the interior layers and semi-infinite region were derived. A global direct stiffness matrix was established by assembling the direct stiffness matrix for each layer. Then, the accuracy and feasibility of the proposed direct stiffness method were verified by comparing the results in the homogeneous and multilayered half-spaces with the literature. Finally, parametric analyses were conducted to investigate the effects of wavenumber in one periodicity length, ground layering, load speed, and load frequency on the dynamic responses. It is concluded that the characteristics of the displacement responses in the horizontal direction differ from those in the vertical direction in both time and frequency domains. The increase in wavenumber, load speed, and load frequency decreased the response amplitudes, increased the characteristic frequencies, and broadened the critical frequency bandwidths. The increase in the layer number broadens the critical frequency bandwidths, but it has no impact on the characteristic frequencies. The moving and Doppler effects cause variations in the characteristic frequencies and critical frequency bandwidths. The results of the multilayered half-space under spatially periodic harmonic moving load can be utilised as fundamental solutions in the periodic boundary element formulations, which will be the focus of future work.
•Periodicity problem of a multilayered half-space was comprehensively investigated.•Direct stiffness matrix for the half-space under a spatially periodic load was derived.•Accuracy and feasibility were verified by comparing with the results from literature.•Response of half-space under a spatially periodic harmonic moving load is discussed.
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•1、Vinyl hybrid silica nanoparticles with average diameter of 30 nm was synthesized.•3、The adsorption capacity for MB can reach 1690 mg/g.•2、The adsorption equilibrium can be reached ...within 80 min.•4、The PAA-based NC hydrogel good reusability.
Adsorption treatment of dyes from industrial effluent by hydrogel adsorbent has been a research hotspot, but few high-performance hydrogel adsorbents with high adsorption capacity have been reported. Previously reported poly (acrylic acid) PAA-based hydrogel adsorbents show a low swelling ratio due to the unsatisfactory cross-linked structure, which causes a passive impact on the exhibit of adsorptive sites and the penetration of water inside the hydrogel. Herein, we prepared a novel super-adsorbent nanocomposite (NC) hydrogel adsorbent by employing vinyl hybrid silica nanoparticles (VSNPs) with average diameter of 30 nm as crosslinking agent. The introduction of an optimal content of VSNPs effectively forms a well three-dimensional network structure. The structure system of our NC hydrogel effectively promotes the active sites on the polymer chains to be exposed to dye molecules. Thus, the NC hydrogel adsorbent achieved a high adsorption capacity of 1690 mg/g for adsorbing methylene blue and obtain a high removal ratio of 90 % within 40 min. Furthermore, the hydrogel exhibits excellent reusability after 4 repeated cycles of adsorption and desorption. The work confirmed that the VSNPs can build a well covalent hybrid cross-linked system of a PAA-based hydrogel without other organic crosslinkers and further provided a new method to develop novel hydrogel adsorbent with enhanced adsorption capacity for removing organic dyes from industrial wastewater.
In this study, we propose a novel coupled periodic tunnel–soil analytical model for predicting ground-borne vibrations caused by vibration sources in tunnels. The problem of a multilayered soil ...overlying a semi-infinite half-space was solved using the transfer matrix method. To account for the interactions between the soil layer and tunnel structure, the transformation characteristics between cylindrical waves and plane waves were considered and used to convert the corresponding wave potentials into forms in terms of the Cartesian or cylindrical coordinate system. The induced ground-borne vibration was obtained analytically by applying a spatially periodic harmonic moving load to the tunnel invert. The accuracy and efficiency of the proposed model were verified by comparing the results under a moving constant and harmonic load with those from previous studies. Subsequently, the response characteristics under a spatially periodic harmonic moving load were identified, and the effects of a wide range of factors on the responses were systematically investigated. The numerical results showed that moving and Doppler effects can be caused by a spatially periodic harmonic moving load. The critical frequency and frequency bandwidth of the response are affected by the load type, frequency, velocity, and wavenumber in one periodicity length. Increasing the tunnel depth is an efficient way to reduce ground-borne vibrations. The effect of vibration amplification on the free surface should be considered to avoid excessive vibration levels that disturb residents.
Soil layers surrounding metro tunnels occasionally have varying characteristics in the longitudinal direction. In the existing vibration prediction model, the soil is usually simplified as a ...horizontally layered medium, which sometimes conflicts with the practical case mentioned above, thus potentially affecting the prediction accuracy. To address this problem, a novel model based on wave propagation analysis is proposed in this study. First, based on the wave propagation analysis, a tunnel-soil coupled model was presented where the dynamic stiffness matrix for the semi-infinite cell was derived. A useful feature for this matrix was mathematically proven, which can improve the calculation efficiency. Then, the vibration response due to the train operation was obtained by superposing the results under each point load. The accuracy was validated by comparing it with the literature and in-site measurement results. Finally, a case study was conducted to evaluate the effect of longitudinally varying characteristics of soils. In this case study, the inclined soil layers were modelled by two methods: horizontal layers and stepped varying layers. The result demonstrates that the dominant frequency, i.e., at 63 Hz, of the ground vibration is not affected by the variation in the longitudinal soil feature. The values of displacement and acceleration responses calculated by horizontally layered models are either greater or lower than those calculated by the stepped soil model. In addition, the results from the model with more soil layers are closer to those from the stepped soil model. The amplification and reduction of transfer loss due to the variation in longitudinal soil characteristics are observed at specific frequencies. Accordingly, for vibration prediction, more corresponding soil layers should be included in the simplification model. As the soil layer impacts the wave propagation characteristics, it should be modelled in detail to obtain a more accurate transfer loss function.
•A tunnel-soil coupled model based on wave propagation analysis is presented.•A useful feature for the dynamic stiffness matrix of the semi-infinite cell is mathematically proven.•The accuracy of the wave-based model is validated.•The effect of longitudinally varying characteristics of soils on ground-borne vibration is investigated.
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•Electrochemical test data indicate the order of inhibition efficiency: DPT > DDP > PDF.•The XPS results show that SCu bonds are generated in PDF, DDP and DPT, and NCu bonds are ...detected in DDP and DPT.•The DPT, DDP, and PDF adsorb on the Cu surface in accordance with the Langmuir model.•Quantum chemistry research and molecular dynamics simulation provide in-depth understanding of the experimental results.
Phenyl disulfide (PDF), 2,2′-dithiodipyridine (DDP), 5,5-dithiobis(1-phenyl-1H-tetrazole) (DPT) were studied as inhibitors for Cu in H2SO4 via electrochemical methods, surface morphology analysis and theoretical calculations. Electrochemical experiments show that PDF, DDP and DPT can exhibit excellent corrosion inhibition performance. Their order of corrosion inhibition is DPT > DDP > PDF. Surface morphology analysis supports the electrochemical results. The X-ray photoelectron spectroscopy (XPS) results show that SCu bonds are detected in PDF, DDP and DPT, and NCu bonds are detected in DDP and DPT. PDF, DDP and DPT adsorption on the Cu surface obey the Langmuir isotherm model. The results of quantum chemical calculations show that DPT has more active reaction sites than DDP and PDF. Molecular dynamics simulation results show that the order of binding energies of the three corrosion inhibitor molecules on the copper surface is DPT > DDP > PDF.
Soil fungi and oomycetes (syn. peronosporomycetes) are the most common causes of pea diseases, and these pathogens often occur in complexes involving several species. Information on the dynamics ...within this complex of pathogens, and also between the complex of pathogens and other fungi in the development of root disease is limited. In this study, next-generation sequencing of nuclear ribosomal internal transcribed spacer-1 was used to characterize fungal communities in agricultural soils from nine pea fields, in which pea roots showed different degrees of disease. Fungal species richness, diversity, and community composition were analyzed and compared among the different pea soils. After filtering for quality and excluding non-fungal sequences, 55,460 sequences clustering into 434 operational taxonomic units (OTUs), were obtained from the nine soil samples. These sequences were found to correspond to 145–200 OTUs in each soil. The fungal communities in the nine soils were strongly dominated by Ascomycota and Basidiomycota.
Phoma,
Podospora,
Pseudaleuria, and
Veronaea, at genus level, correlated to the disease severity index of pea roots;
Phoma was most abundant in soils with diseased plants, whereas
Podospora,
Pseudaleuria, and
Veronaea were most abundant in healthy soils. No correlation was found between the disease severity index and the abundance of some of the other fungi and oomycetes normally considered as root pathogens in pea.
► NGS revealed diverse fungal communities in soils with diseased and healthy pea. ►
P. medicaginis was the most abundant species and correlated to the DSI of pea roots. ►
Phoma,
Podospora,
Pseudaleuria, and
Veronaea all correlated to the DSI of pea roots.
Abstract
Changes in fungal communities associated with healthy and diseased pea roots were investigated using deep amplicon pyrosequencing in three spatial compartments: roots, rhizosphere, and ...surrounding soil. Thirty root systems were collected from three fields, half of which showing clear symptoms of root rot. In total, 500 461 internal transcribed spacer-1 sequences were obtained that were clustered into 123 (roots), 271 (rhizosphere), and 440 (bulk soil) nonsingleton operational taxonomic units (OTUs). Species richness was highest in bulk soils and lowest in roots; however, no notable differences in richness were observed between samples associated with diseased and healthy roots. Health status and field both had significant effects on fungal community structures in roots, whereas only field had significant effects on communities in rhizosphere and bulk soils. Indicator species analysis across the three fields identified a number of OTUs that were more abundant in healthy roots. Pathogens such as Fusarium oxysporum were abundant in diseased roots in some fields. Patterns of disease and causal agents of root rot were different among the three fields, which were also reflected in fungal communities. In conclusion, health status of roots was only vaguely reflected in rhizosphere and bulk soil fungal communities, whereas health status was more important for shaping root communities.
The inter-blade passage vortex, the vortex rope of the draft tube, and the vortex in the guide apparatus are the characteristics of flow instability of the Francis turbine, which may lead to fatigue ...failure in serious cases. In the current study, in order to accurately capture the transient turbulent characteristics of flow under different conditions and fully understand the flow field and vortex structure, we conduct a simulation that adopts sliding grid technology and the large-eddy simulation (LES) method based on the wall-adapting local eddy viscosity (WALE) model. Using the pressure iso-surface method, the Q criterion, and the latest third-generation Liutex vortex identification method, this study analyzes and compares the inter-blade passage vortex, the vortex rope of the draft tube, and the outflow and vortex in the guide apparatus, focusing on the capture ability of flow field information by various vortex identification methods and the unique vortex structure under the condition of a small opening. The results indicate that the dependence of Liutex on the threshold is small, and the scale range of the flow direction vortex captured by Liutex is wider, but the ability of the spanwise vortex is relatively weak. The smaller the opening, the more disorderly the vortexes generated in each component and the more unstable the flow field. In the draft tube, the original shape of the vortex rope is destroyed due to the interaction between vortexes. Under the condition of a small opening, an inter-blade passage vortex is generated, affecting the efficient and stable operation of the turbine.
Gray leaf spot is a devastating disease caused by Stemphylium lycopersici that threatens tomato-growing areas worldwide. Typically, many pathogenesis-related and unrelated secreted proteins can be ...predicted in genomes using bioinformatics and computer-based prediction algorithms, which help to elucidate the molecular mechanisms of pathogen-plant interactions.
S. lycopersici-secreted proteins were predicted from 8997 proteins using a set of internet-based programs, including SignalP v4.1 TMHMM v2.0, big-PI Fungal Predictor, ProtComp V9.0 and TargetP v1.1. Analysis showed that 511 proteins are predicted to be secreted. These proteins vary from 51 to 600 residues in length, with signal peptides ranging from 14 to 30 residues in length. Functional analysis of differentially expressed proteins was performed using Blast2GO. Gene ontology analysis of 305 proteins classified them into 8 groups in biological process (BP), 6 groups in molecular function (MF), and 10 groups in cellular component (CC). Pathogen-host interaction (PHI) partners were predicted by performing BLASTp analysis of the predicted secreted proteins against the PHI database. In total, 159 secreted proteins in S. lycopersici might be involved in pathogenicity and virulence pathways. Scanning S. lycopersici-secreted proteins for the presence of carbohydrate-active enzyme (CAZyme)-coding gene homologs resulted in the prediction of 259 proteins. In addition, 12 of the 511 proteins predicted to be secreted are small cysteine-rich proteins (SCRPs).
S. lycopersici secretory proteins have not yet been studied. The study of S. lycopersici genes predicted to encode secreted proteins is highly significant for research aimed at understanding the hypothesized roles of these proteins in host penetration, tissue necrosis, immune subversion and the identification of new targets for fungicides.
The initial deposition amount, dissipation dynamics, retention rate, and field control efficacy of difenoconazole in pepper-soil system were studied with different application dosages, planting ...regions and patterns. The initial deposition amount of difenoconazole under the same application dosage showed the following order: fruits < cultivated soils < lower stems < upper stems < lower leaves < upper leaves, open field < greenhouse, and Changjiang < Cixi < Hefei < Langfang, respectively, which increased with increasing application dosage. The dissipation rates in leaves, stems, fruits and cultivated soils exhibited an initially fast and then slow trend, while the retention rates displayed a tendency of first increasing and then stabilizing with increasing application dosages. After 7 d of difenoconazole application, the retention rates at five concentrations were 10.3%− 39.1%, and the field efficacy mostly reached the minimum effective dose. These results suggested that difenoconazole could be reduced by 25% based on the minimum recommended dose meeting the requirements of field control efficacy for controlling pepper anthracnose.
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•Deposition distribution of difenoconazole was explored in the pepper-planting ecosystem.•Dissipation rate of difenoconazole differed in various plant parts and planting modes.•Dissipation of difenoconazole showed an initially fast and then slow trend.•Retention rate first rose and then stabilized with increasing application dosages.•Application dosages of difenoconazole could be reduced to control pepper anthracnose.
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