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This study presents the effects of the particle shape on soil arching by simulating the trapdoor problem using the discrete element method (DEM). A new method for preparing the samples with irregular particle in the DEM is proposed to obtain a similar and reasonable initial stress state. Simple monitoring of the strain field is demonstrated. The results indicate that as the trapdoor moves downward, the critical height at which the measurable differential settlement vanishes increases then remains steady. The final critical height increases with decreasing sphericity or increasing roundness, in which the sphericity is the main influencing factor. Two types of shear bands propagate from the edge of the trapdoor into the specimens. As the interlocking between the irregular particles increases, the shear strain decreases, but the dilation increases inside the shear band. The particle shape affects the development rate of soil arching, but has a limited effect on the ultimate soil arching behaviour. The rotation of the major principal directions of anisotropy and the decrease in the anisotropy intensity are microcosmic reason of soil arching. Both of the rotation and decrease mainly occur in a relatively small trapdoor displacement, restricted by the increase in the interlocking between irregular particles.

Molecular dynamics (MD) simulation was carried out to investigate the stress distribution and the macro tensile stress for the α-iron single crystal and twin crystal. The results show that there was a maximum tensile stress located at the matrix near the interface between the porous layer and the matrix for the two crystals. It has been found that a steep drop of stress generated at the twin boundary of the twin crystal. The deflection and the macro tensile stress of the single crystal and the twin crystal increased with an increase of the relative depth of the porous layer. The value of the deflection and the macro tensile stress of the single crystal were larger than that for the twin crystal, because there is a steep drop of stress generated at the twin boundary due to the effect of twin interface.

The oxidation behavior of Fe-Cr-Ni-Mo-Ti maraging steel was investigated within an intermediate temperature range of 450-600°C. Analysis of oxidation kinetics demonstrated excellent oxidation resistance after exposure in air for 100 h; the oxide layer formed was protective and can resist further oxidation. Surface morphology evolution and oxidized surface hardness were characterized by scanning electron microscope and nanoindentation test. The surface oxidation film was rather smooth with Cr enriched at 450°C, appeared a needle-like structure at 500°C together with a few nodule protrusions enriched in O but absent in Fe and Cr; and then transformed to a smooth and compact oxide surface with some protrusion emerged on the original grain boundaries of austenite at 550°C; finally a Fe2O3 phase particle structure appeared at 600°C. The oxidation layer formed on substrate of Fe-Cr-Ni-Co-MoTi was harder than the substrate when oxidation temperature was lower than 550°C.

Prediction of subsurface ground deformation during bedrock faulting is important for structures located at potential seismic areas. In this paper, a theoretical approach was developed based on error function. Settlement profiles are found to be well represented using error function. Normalization issues of settlement profiles are discussed and it is found that the vertical displacements can be normalized with vertical displacement of the bedrock hanging wall h.

Pipeline steel in soil containing water could induce a macro tensile stress, leading to stress corrosion cracking (SCC). Anisotropic corrosion-induced stress of Fe single crystal is studied by molecular dynamics (MD) in this paper. The surface perpendicular to the z direction is subjected to the corrosion, and the process of corrosion along three crystallographic directions is simulated using MD approach. When the surface with one specific orientation is corroded, two cases are considered: one is that the periodic boundary condition is applied along the x direction, while free boundary condition along the y direction; and the other is that the periodic boundary condition along the y direction, while free boundary condition along the x direction. The results show that both the deflection of the free end and the macro tensile stress of the crystal for the corrosion in three crystallographic orientations are increasing with the increase of the relative depth of the porous layer. The values of the deflection and the macro tensile stress for the two cases depend on the orientation with the free boundary condition when the surface with one specific orientation is corroded. Moreover, the smaller the interplanar spacing along the orientation with the free boundary condition is, the larger the deflection and the macro tensile stress are.

Ordered nanoporous carbon (ONC) was synthesized by adopting sucrose as precursor and SBA-15 as template. The thermal stability of sucrose and its SBA-15 composite were detected by thermogravimertic analysis. Transmission Electron Microscope, X-ray diffraction and nitrogen adsorption technology were used to characterize the morphology, microstructure and specific surface area of resultant ONC. The effects of carbonization temperature and pre-carbonization on the microstructure of ONC were investigated. The results have shown that SBA-15 is a kind of ideal template for preparing ONC, from which ONC with the diameter around 8 nm was obtained. When carbonized at 700 °C, the specific surface area of ONC derived is 2884.05 m2/g.

We have developed a theoretical method to obtain a single-walled carbon nanotube (SWCNT) with a high density of topological defects. Carbon nanotubes (CNTs) sustain elastic elongation up to 15-30% at low temperature because of the sufficiently high barrier of bond rotations. A large number of topological defects are activated simultaneously and widely distributed over the entire tube wall after heating the stretched tube to an elevated temperature. This is driven by the internal energy of the strained carbon nanotubes. The manner in which topological defects are distributed is affected by the initial strain and the heating temperature. Nanotubes with a large number of topological defects achieve the elongation without breaking.

Cucurbitacin B is an anti-cancer drug candidate and its efficacy has been demonstrated in hepatocellular carcinoma (HCC). To explore its mechanism against HCC, BEL-7402 cells were treated with cucurbitacin B in vitro. Treatment with cucurbitacin B induced S phase arrest and apoptosis. The growth inhibition effect was associated with cyclin D1 and cdc-2 down regulations. Western blotting analysis of cell signaling molecules indicated that cucurbitacin B inhibited c-Raf activation without affecting STAT3 phosphorylation. Moreover, in vivo study demonstrated that cucurbitacin B is effective against BEL-7402 xenograft when administrated orally.

Hybrid carbon membranes were prepared by adopting phenolic resin (PR) and poly(vinyl alcohol) (PVA) blended polymer as precursor, and zeolite 5A as additives through pyrolysis. Thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscope and gas permeation technique were used to characterize the precursor and carbon membranes. The results have shown that the thermal stability of hybrid polymeric membranes is enhanced by incorporating with 5A and defect-free hybrid carbon membranes were successfully prepared. The H2 permeability of 2125.40 Barrer and the H2/N2 selectivity of 55.9 are achieved when hybrid carbon membranes were fabricated at 700 oC.

A convenient approach to 3-sec-alkyl substituted indoles was developed via palladium-catalyzed addition of arylboronic acids to vinylogous imines generated in situ from sulfonylindoles under mild conditions.

Purpose. This study describes the antibacterial effect of extracts and compounds isolated from the aerial part of Chelidonium majus Linn. (Papaveraceae) acting against clinical strains of methicillin-resistant Staphylococcus aureus (MRSA). Methods. The activities were evaluated by using the macrobroth dilution method and reported as the MICs/MBCs. Results. Bioassay-guided fractionation of the most active extract from the aerial parts (EtOAc) led to the isolation of benzo[c]phenanthridine-type alkaloids 8-hydroxydihydrosanguinarine (hhS), 8-hydroxydihydrochelerythrine (hhC), which were potently active against MRSA strains. Conclusions. The selective antibacterial activity reported in this paper for 8-hydroxylated benzo[c]phenanthridine-type alkaloids isolated from C.majus opens the possibility that they could be helpful for the developing of new antibacterial agents for treating the infection of MRSA which has created nosocomial problem worldwide.