Search

Abstract Current and future trends in the aerospace industry leverage on the potential benefits provided by lightweight materials that can be tailored to realize desired mechanical characteristics when loaded. For aircraft design, the deployment of aeroelastic tailoring is hindered by the need to re-compute, for any possible modification of the structure, the dependence of the aerodynamic field on the underlying structural properties. To make progress in this direction, the work presents a rapid computational fluid dynamics based aeroelastic tool which is built around a reduced order model for the aerodynamics that is updated for any modification of the structure by using the structural dynamics reanalysis method. The aeroelastic tailoring tool is demonstrated in transonic flow for the AGARD 445.6 wing, suitably modified with composite materials. It was found that the proposed method provides accurate engineering predictions for the aeroelastic response and stability when the structure is modified from the baseline model. [ABSTRACT FROM AUTHOR]

Transonic aeroelastic analysis is an important aspect of modern aircraft design. When the modeshapes changed for the structural stiffness or/and mass matrix variation, the structural model and aerodynamic model could be reconstructed to maintain accuracy. However, these reconstruction procedures have to be repeated every time when there is a change in the aircraft structure design, where each of these reconstructions takes a considerable time. In this paper, an automated procedure for transonic aeroelastic analysis method was proposed when the structural model parameters changed at global level. To manage thousands of calculations and makes more efficient and reliable calculations, the structural dynamic reanalysis method was employed to set up an automated procedure to link the aeroelastic solvers and structural design parameters without changing structural modal coordinates. The proposed automated procedure was illustrated and verified by the AGARD 445.6 wing aeroelastic model with different global level structural parameter variations. The results show that the automated procedure can accurately produce pulse responses corresponding to the mode excitations and the flutter characteristics of AGARD 445.6 wing in a very large modification range. The whole automated procedure is efficient and reliable in managing transonic aeroelastic analysis when structural parameters changed at global level. [ABSTRACT FROM AUTHOR]

The construction of an engineered cover layer over landfills is a common method applied to reduce the emission of hazardous gases into the atmosphere. Landfill gas pressures can reach 50 kPa or even higher in some cases, thus posing a serious threat to nearby properties and human safety. As such, the evaluation of gas breakthrough pressure and gas permeability in a landfill cover layer is of great necessity. In this study, the loess soil that is often applied as a cover layer in landfills in northwestern China was used to conduct gas breakthrough, gas permeability, and mercury intrusion porosimetry (MIP) tests. Resultantly, the smaller the capillary tube diameter, the higher the capillary force, and the more significant the capillary effect. Gas breakthrough could be attained with no difficulty, provided that the capillary effect was minimal or approached zero. A good fit between the experimental gas breakthrough pressure–intrinsic permeability relationship and a logarithmic equation was found. The mechanical effect blew up the gas flow channel. In the worst-case scenario, the mechanical effect could lead to the overall failure of a loess cover layer in a landfill. A new gas flow channel was formed between the rubber membrane and the loess specimen as a result of the interfacial effect. Although both the mechanical and interfacial effects can elevate the gas emission rate, the latter did not play a role in the improvement of the gas permeability; therefore, misleading interference took place in the evaluation of the gas permeability, and an overall failure of the loess cover layer. To tackle this problem, the point at which the large- and small-effective stress asymptotes cross on the volumetric deformation– P eff diagram may be applied to give early warning signals of the potential overall failure of the loess cover layer in landfills in northwestern China. • The capillary effect is a crucial factor affecting the gas breakthrough pressure. • Both the mechanical and interfacial effects gear up the gas emission rate. • The interfacial effect can mislead the assessment of the failure of a cover layer. • The volumetric deformation goes up with decrease in P eff in an exponential manner. • Such exponential relationship gives early warning of the failure of a cover layer. [ABSTRACT FROM AUTHOR]

Highlights: [•] AEG-1 expression in CRC cell lines and down-regulation or upregulation of AEG-1 in vitro. [•] Knockdown of AEG-1 inhibits cell proliferation, colony formation and invasion. [•] Upregulation of AEG-1 enhances proliferation, invasion and colony formation. [•] Knockdown of AEG-1 accumulates G0/G1-phase cells and promotes apoptosis in CRC cells. [•] AEG-1 knockdown increases 5-FU cytotoxicity. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) as an endocrine-disrupting chemical with weak estrogenic activity affects formation of primordial follicles. This study aimed to identify the potential effects and molecular mechanisms of BPA on meiosis and primordial follicle formation in chickens. The results suggest that the cortical layer was thickened and the number of germ cells that entered into meiosis was increased in BPA-treated ovaries. The percentage of γH2AX-positive cells increased significantly. In addition, up-regulated mRNA expression of meiotic genes, including stimulated by retinoic acid gene 8 ( Stra8 ), disrupted meiotic cDNA 1 homologue ( Dmc1 ) and synaptonemal complex protein 3 ( Scp3 ) were observed in BPA-treated ovaries. Therefore, progression to meiosis prophase I was accelerated by exposure to BPA. Furthermore, the results demonstrated that injection of BPA resulted in hypomethylation of Dazl (Deleted in A Zoospermia-Like gene) and Stra8 and up-regulation mRNA expression of Dazl and Stra8 during meiotic onset. Finally, the relationship between estrogen receptor (ER) expression and BPA-induced meiosis was revealed using an in vitro ovarian culture system. BPA enhanced ERβ expression at the levels of mRNA and protein, while BPA exerted no significant effect on ERα and membrane-bound estrogen receptor ( GPR30 ) expression. The inducing effects of BPA on meiosis were blocked by ER inhibitor. Collectively, these results demonstrate the dynamic ovarian response to BPA exposure, which indicate that BPA affects the formation of primordial follicles by promoting meiotic progression of oocytes via hypomethylation of Dazl and Stra8 and ERβ signaling pathways. [ABSTRACT FROM AUTHOR]

Landslide is a hazard that has drastic repercussions on population and the environment worldwide. Landslide susceptibility mapping (LSM) is vital for landslide disaster management and formulating mitigation strategies. In this study, with the support of geographic information system and remote sensing, a new LSM hybrid framework is developed based on random forest (RF) and cusp catastrophe model (CCM). Under the framework, 15 conditioning factors and 2082 historical landslides are selected to test and compare its performance in a landslide-prone area in Liangshan, Southwest China. The results depicted a better performance of the new LSM hybrid framework (RF-CCM) than those of RF or traditional application mode of catastrophe model (Catastrophe fuzzy membership functions, CFMFs) only. The RF-CCM achieved the highest accuracy (0.901), the narrowest confidence interval (0.895–0.907), and the smallest standard error (0.004) among all the models. Notably, RF-CCM successfully decreased the uncertainty of CFMFs in determining the relative importance of conditioning factors, overcame the dependence of the CFMFs on independence among the conditioning factors, and had a higher stability level than RF. Moreover, distance to human engineering activities and slope had the greatest impact on LSM in the modeling process. The study result can provide insights for developing reliable predictive models for other landslide-prone areas with similar geo-environmental conditions. • The spatial database of 15 conditioning factors is constructed. • A novel framework (RF-CCM) is developed for landslide susceptibility mapping. • The RF-CCM has the best performance in comparison to RF and CFMFs. • It reveals the importance of driving factors and their categories for landslides. [ABSTRACT FROM AUTHOR]

Abstract: A new metal-organic framework, [Zn5(trencba)2(OH)2Cl2·4H2O] (1) [H3trencba=N,N,N′,N′,N′′,N′′-tris[(4-carboxylate-2-yl)methyl]-tris(2-aminoethyl)amine], constructed from a flexible tripodal ligand based on C 3 symmetric tris(2-aminoethyl)amine, has been synthesized hydrothermally and characterized by elemental analysis, IR, TG, XRD and single-crystal X-ray diffraction analysis. Compound 1 contains an unprecedented linear penta-nuclear zinc cluster fragment. Each ligand links four penta-nuclear fragments, and every fragment links eight ligands to generate a three-dimensional non-interpenetrated porous framework. The uncoordinated water molecules were observed trapped in the void pores. Compound 1 represents the first example of (6,8)-connected 3D bi-nodal framework based on a single kind of organic ligand. The photoluminescence measurements showed that complex 1 exhibits relatively stronger blue emissions at room temperature than that of the ligand. [Copyright &y& Elsevier]