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AbstractThis article presents a novel automatic PSO-based back analysis method for mechanical parameters of block discrete element method. Incorporating particle swarm optimization (PSO) algorithm and recursive algorithm, a parameter back-analysis program is developed. Two cases, a laboratory test of columnar jointed rock mass and a typical landslide, are implemented for validation. The results show that the proposed method is feasible and accurate. As an automatic solution for parameter back analysis, this work has broad application prospects in geotechnical engineering.

The unloading relaxation caused by excavation for construction of high arch dams is an important factor influencing the foundation's integrity and strength. To evaluate the degree of unloading relaxation, the long-short term memory (LSTM) network was used to estimate the depth of unloading relaxation zones on the left bank foundation of the Baihetan Arch Dam. Principal component analysis indicates that rock characteristics, the structural plane, the protection layer, lithology, and time are the main factors. The LSTM network results demonstrate the unloading relaxation characteristics of the left bank, and the relationships with the factors were also analyzed. The structural plane has the most significant influence on the distribution of unloading relaxation zones. Compared with massive basalt, the columnar jointed basalt experiences a more significant unloading relaxation phenomenon with a clear time effect, with the average unloading relaxation period being 50 d. The protection layer can effectively reduce the unloading relaxation depth by approximately 20%.

MicroRNAs (miRNAs) play significant roles in both embryonic hematopoiesis and hematological malignancy. Zebrafish miR-462-731 cluster is orthologous of miR-191-425 in human which regulates proliferation and tumorigenesis. In our previous work, miR-462-731 was found highly and ubiquitously expressed during early embryogenesis. In this study, by loss-of-function analysis (morpholino knockdown combined with CRISRP/Cas9 knockout) and mRNA profiling, we suggest that miR-462-731 is required for normal embryonic development by regulating cell survival. We found that loss of miR-462/miR-731 caused a remarkable decrease in the number of erythroid cells as well as an ectopic myeloid cell expansion at 48 hpf, suggesting a skewing of myeloid-erythroid lineage differentiation. Mechanistically, miR-462-731 provides an instructive input for pu.1-dependent primitive myelopoiesis through regulating etsrp/sclsignaling combined with a novel pu.1/miR-462-731 feedback loop. On the other hand, morpholino (MO) knockdown of miR-462/miR-731 resulted in an expansion of posterior blood islands at 24 hpf, which is a mild ventralization phenotype resulted from elevation of BMP signaling. Rescue experiments with both BMP type I receptor inhibitor dorsomorphin and alk8MO indicate that miR-462-731 acts upstream of alk8within the BMP/Smad signaling pathway and functions as a novel endogenous BMP antagonist. Besides, an impairment of angiogenesis was observed in miR-462/miR-731 morphants. The specification of arteries and veins was also perturbed, as characterized by the irregular patterning of efnb2aand flt4expression. Our study unveils a previously unrecognized role of miR-462-731 in BMP/Smad signaling mediated hematopoietic specification of mesodermal progenitors and demonstrates a miR-462-731 mediated regulatory mechanism driving primitive myelopoiesis in the ALPM. We also show a requirement for miR-462-731 in regulating arterial-venous specification and definitive hematopoietic stem cell (HSC) production. The current findings might provide further insights into the molecular mechanistic basis of miRNA regulation of embryonic hematopoiesis and hematological malignancy.

In this study, we propose a digital image processing technology for estimating the macro permeability property of heterogeneous geomaterials. The technology is based on a connected-component labeling algorithm and provides a novel and effective method for geometry vectorization and microstructure identification. A color photo of a soil and rock mixture (SRM) is taken as an example. Information about the distribution of aggregate and a vectorgraph, which can be used in numerical analysis, are obtained automatically. A numerical permeability test is carried out to estimate the macro permeability coefficient of the heterogeneous medium. The effects on macro permeability of three parameters, scale dependency, material heterogeneity and the rock fraction, are discussed. The results indicate that the SRM has a scale dependent property and the representative element volume (REV) length is about six times the maximum major axis of the aggregate. The heterogeneity parameter has a major effect on macro permeability characteristics within a certain range. There is a weak tendency for the macro permeability to decrease as the rock fraction increases. Although the rock fraction is not the only factor, it does have an influence on the macro permeability. We conclude that the novel method developed in this study has good prospects for widespread application in macro parameter estimation and related research fields.

Safety evaluation of toppling rock slopes developing in reservoir areas is crucial. To reduce the uncertainty of safety evaluation, this study developed a composite cloud model, which improved the combination weights of the decision-making trial and evaluation laboratory (DEMATEL) and criteria importance through intercriteria correlation (CRITIC) methods. A safety evaluation system was developed according to in situ monitoring data. The backward cloud generator was used to calculate the numerical characteristics of a cloud model of quantitative indices, and different virtual clouds were used to synthesize some clouds into a generalized one. The synthesized numerical characteristics were calculated to comprehensively evaluate the safety of toppling rock slopes. A case study of a toppling rock slope near the Huangdeng Hydropower Station in China was conducted using monitoring data collected since operation of the hydropower project began. The results indicated that the toppling rock slope was moderately safe with a low safety margin. The composite cloud model considers the fuzziness and randomness of safety evaluation and enables interchange between qualitative and quantitative knowledge. This study provides a new theoretical method for evaluating the safety of toppling rock slopes. It can aid in the predication, control, and even prevention of disasters.

With the help of an automatic servo-controlled triaxial rock creep system, typical whole process rheological curve is obtained through laboratory experiment on the surrounding diorite rock of a large underground water-sealed cavern project. Creep experiments show that diorite exhibits obvious creep behaviour under the high in situstress. Based on the experiment results, this article studies the creep behaviour under different stress levels, analyses the creep failure mode and mechanism, and obtains the triaxial creep properties of diorite. Using a three-dimensional nonlinear numerical method and the modified hydro-mechanical coupled Cvisc creep model, creep behaviour of the surrounding rock during the long-term operation is simulated and time-dependent stability is analysed. The results indicate that creep deformation is evident, and local stress concentration is relieved due to stress redistribution. After a period of time, the creep rate becomes stable and the deformation is stabilised. Because of its theoretical and practical significance, hydro-mechanical coupled creep analysis is important for the long-term stability and safety evaluation.

The pile-soil interaction under wave loads is an extremely complex and difficult issue in engineering. In this study, a physical model test is designed based on the principle of the gravity similarity to obtain time histories of wave forces of unsteady regular waves, and to measure the magnitude and the distribution of wave forces acting on the piles. A numerical model and relevant numerical methods for the pile-soil contact surface are adopted based on the principles of elastic dynamics. For a practical project, the time histories of wave forces on the piles are obtained through physical model tests. The deformations of the piles in the pile-soil interactions and the distribution of the bending moment on the piles are studied. It is shown that, with the increase of the period of wave pressures, the absolute value of the horizontal displacement of the piles increases, the embedment depth of the piles increases, and the scope of influence of soils increases. The change of the bending moment on the piles is consistent with that of its theoretical results, and the proposed numerical method can very well simulate the properties of the piles.

The pile-soil interaction under wave loads is an extremely complex and difficult issue in engineering. In this study, a physical model test is designed based on the principle of the gravity similarity to obtain time histories of wave forces of unsteady regular waves, and to measure the magnitude and the distribution of wave forces acting on the piles. A numerical model and relevant numerical methods for the pile-soil contact surface are adopted based on the principles of elastic dynamics. For a practical project, the time histories of wave forces on the piles are obtained through physical model tests. The deformations of the piles in the pile-soil interactions and the distribution of the bending moment on the piles are studied. It is shown that, with the increase of the period of wave pressures, the absolute value of the horizontal displacement of the piles increases, the embedment depth of the piles increases, and the scope of influence of soils increases. The change of the bending moment on the piles is consistent with that of its theoretical results, and the proposed numerical method can very well simulate the properties of the piles.

The rock permeability is an important parameter in the studies of seepage and stress coupling. The micro-cracks and pores can initiate and grow on a small scale and coalesce to form large-scale fractures and faults under compressive stresses, which would change the hydraulic conductivity of the rock, and therefore, the rock permeability. The rock permeability is, therefore, closely related with the micro-cracking growing, coalescence, and macro new fracture formation. This article proposes a conceptual model of rock permeability evolution and a micro kinematics mechanism of micro-cracking on the basis of the basic theory of micromechanics. The applicability of the established model is verified through numerical simulations of in situtests and laboratory tests. The simulation results show that the model can accurately forecast the peak permeability evolution of brittle rock, and can well describe the macro-experimental phenomenon before the peak permeability evolution of brittle rock on a macro-scale.

Fly ash has become increasingly wide range of applications in expressway as a new environment friendlymaterial, its range of applications are fromthe CFG( Cement Fly-ash Gravel) pile of soft ground、pavement admixture to embankment materials et al. Fly ash used in expressway has many advantages, such as, it can save farmland, has a small settlement after construction and low cost as a light embankment filling. In this paper, based on an expressway in Jiangsu province, the fly ash used as a subgrade filling, a series of fly ash laboratory and field test have been conducted. The construction technology, important construction parameters, construction process control and compaction quality assessment on fly ash have been analyzed on the basis of the tests result, the road performance and construction control key methods of fly ash obtained, which can guide scientific construction.

A large number of studies have indicated that Astragalus Membranaceus(AM) possesses growth-promoting effects in animal husbandry. However, the function of AM in common carp growth performance has not meant fully evaluated. In this work, to investigate the potential effects of AM and Lactobacillus plantarum-fermented AM (FAM) on growth performance, intestinal function, and intestinal microenvironment of common carp, fish with an average weight of 10.10 ± 0.25g were divided into seven groups, and fed daily with an additive-free basal diet (BD); 0.1, 0.2, and 0.4% (w/w) of AM (L-AM, M-AM, and H-AM); 0.1, 0.2, and 0.4% (w/w) of FAM (L-FAM, M-FAM and H-FAM) for an eight-week period. The results showed that incorporating L-AM or L-FAM in the diet significantly increased (P < 0.05) the final weight, weight gain ratio, and specific growth rate compared with the BD group, but significantly decreased (P < 0.05) the feed conversion ratio. In L-AM and L-FAM groups, the villus height was considerably increased (P < 0.05), and crypt depth remained unaffected. L-AM and L-FAM both changed the abundance of intestinal microbiota with strikingly different dominant microbiota. Dietary L-FAM supplementation increased the abundance of Firmicutes, Verrucomicrobia, Cyanobacteria, TM7, WS3, Chlamydiae, TM6, Fusobacteria, Spirochaetes, Acidobacteria, Gemmatimonadetes, Actinobacteria, Chloroflexi, [Thermi], and Nitrospirae, whereas decreased Bacteroidetesand Proteobacteriaabundances. Intestinal metabolome analyses demonstrated that L-AM altered metabolic composition and function, which were linked to immunity and host metabolism. Furthermore, L-FAM showed superior beneficial metabolic effects than L-AM in fish. On growth performance improvement and intestinal microenvironment modulation, dietary L-FAM supplementation was superior to AM in common carp. We speculate that L-FAM may improve the intestinal morphology and microenvironment, which strengthens the growth of fish. In addition, FAM might be promising antibiotics’ alternatives for promoting fish growth and controlling pathogens that has immense economic value in aquaculture.

New Fréchet-type dendritic BINOL ligands bearing several BINOL units at the periphery have been successfully synthesized. The (dendritic BINOL) Ti(IV) complexes were proved to be efficient catalysts for the enantioselective addition of diethylzinc to aromatic aldehydes. Moreover, these ligands could be quantitatively recovered and reused at least five times without a loss of the yield and enantioselectivity.

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