FATIGUE STRENGTH PREDICTION OF RAILWAY AXLE SPECIMEN WITH SURFACE NOTCH BY TCD

This paper, based on theory of critical distance（TCD）, carried out a research on the fatigue strength prediction of axle specimens with surface notch. The fatigue limit of smooth specimens, specimens with V-shaped surface notch, and specimens with hole-shaped surface notch were tested by axial loading. Meanwhile, the crack growth threshold value when stress ratio R=-1 was tested. The fatigue limit of railway axle specimens with surface notch were predicted by the point method and line method of TCD with the aid of finite element calculation. Calculation results show that, when TCD is used to predict fatigue limit of axle specimens with surface notch, the relative error of point method is larger, and line method has higher prediction accuracy. Line method is able to meet engineering needs and has important guiding significance in predicting the fatigue strength of axles with surface notches

Graphene/Graphitized Polydopamine/Carbon Nanotube All-Carbon Ternary Composite Films with Improved Mechanical Properties and Through-Plane Thermal Conductivity

Graphene films (GFs) are promising ultrathin thermally conductive materials for portable electronic devices because of their excellent thermally conductive property, light weight, high flexibility, and low cost. However, the application of GFs is limited due to their poor mechanical properties and through-plane thermal conductivity. Here, a graphene-(graphitized polydopamine)-(carbon nanotube) (G-gPDA-CNT) all-carbon ternary composite film was fabricated by chemical reduction, carbonization, graphitization, and mechanical compaction of the evaporation-assembled (graphene oxide)-PDA@CNT film. The G-gPDA-CNT film exhibited a uniform all-carbon composite structure in which the components of the graphene, gPDA layers, and CNTs were cross-linked by strong covalent bonds. This unique structure promoted the load transfer and energy dissipation between the components by which the mechanical properties of the G-gPDA-CNT film were substantially improved. Furthermore, electron and phonon transfers were also promoted, greatly improving the electrical and thermal conductivities, especially the through-plane thermal conductivity of the G-gPDA-CNT film. The G-gPDA-CNT film showed a tensile strength of 67.5 MPa, 15.1% ultimate tensile strain, toughness of 6.07 MJ/m3, electrical conductivity of 6.7 × 105 S·m-1, in-plane thermal conductivity of 1597 W·m-1·K-1, and through-plane thermal conductivity of 2.65 W·m-1·K-1, which were 2.24, 1.44, 3.16, 1.46, 1.15, and 3.90 times that of the pure GFs, respectively.</p

The antifungal metabolites obtained from the rhizospheric <i>Aspergillus</i> sp. YIM PH30001 against pathogenic fungi of <i>Panax notoginseng</i>

<div><p>Eight anthraquinones (<b>1–8</b>), three xanthones (<b>11–13</b>) and two phenols (<b>9–10</b>) were isolated from <i>Aspergillus</i> sp. associated with <i>Panax notoginseng</i>, and their structures were determined as ziganein-1-methyl ether (<b>1</b>), 8-<i>O</i>-methylchrysophanol <b>(2</b>), averythrin (<b>3</b>), averufin (<b>4</b>), 8-<i>O</i>-methyl averufin (<b>5</b>), versicolorin B (<b>6</b>), averantin (<b>7</b>), methyl-averantin (<b>8</b>), arugosin C (<b>9</b>), diorcinol (<b>10</b>), sterigmatocystin (<b>11</b>), demethylsterigmatocystin (<b>12</b>) and dihydrosterigmatocystin (<b>13</b>) by spectroscopic analyses. Compounds <b>1</b>, <b>2</b> and<b> 5</b> were the novel isolates from genus <i>Aspergillus</i>. Compounds <b>3</b>, <b>6</b> and<b> 7</b> exhibited antifungal activity against <i>Fusarium</i><i>solani</i>, pathogenic fungus of <i>P. notoginseng</i>, with minimum inhibitory concentrations (MICs) of 16<b>–</b>32 μg/mL, and compounds <b>1</b>, <b>3</b>, <b>4</b>, <b>7</b> and <b>9</b> showed antibacterial activity against <i>Bacillus</i><i>subtilis</i> with MICs of 64–128 μg/mL, 16–32 μg/mL, 8–16 μg/mL, 16–32 μg/mL and 64–128 μg/mL, respectively. The metabolites showed the potential value in the research of antifungal agents, especially in searching for a biocontrol of diseases of <i>P. notoginseng</i>. The preliminary structure–activity relationships have been discussed for some of the compounds.</p></div