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Quasi-static compressive behaviors of three amorphous alloys (Cu50Zr50, Pd80Si20, and Ni67Zr33) are investigated via molecular dynamics simulations. Compared to the crystalline counterpart, when the strain is below 1%, significant fluctuations can be observed in the stress-strain curves. Further analysis of the simulated data indicates that the fluctuations are associated with the variations of Voronoi volume. A gradient reduction model is proposed to explain the process of the evolution of Voronoi volume at the initial stage of the deformation. [ABSTRACT FROM AUTHOR]

The varying degrees of configurational disorder in metallic glasses are investigated quantitatively by molecular dynamics studies. A parameter, the quasi-nearest atom, is used to characterize the configurational disorder in metallic glasses. Our observations suggest configurational disorder play a role in structural heterogeneity, plasticity and dynamic relaxations in metallic glasses. The broad configurational disorder regions distribution is the indicator of abundant potential deformation units and relaxations. Plastic flow, as well as relaxation, is believed to start at configurational disorder regions. The width of the shear bands and dynamic relaxations can then be regulated by the degree of configurational disorder regions in metallic glasses. [ABSTRACT FROM AUTHOR]

Structural evolution in nanoscale Cu50Zr50 metallic glasses during high-pressure torsion is investigated using molecular dynamics simulations. Results show that the strong cooperation of shear transformations can be realized by high-pressure torsion in nanoscale Cu50Zr50 metallic glasses at room temperature. It is further shown that high-pressure torsion could prompt atoms to possess lower five-fold symmetries and higher potential energies, making them more likely to participate in shear transformations. Meanwhile, a higher torsion period leads to a greater degree of forced cooperative flow. And the pronounced forced cooperative flow at room temperature under high-pressure torsion permits the study of the shear transformation, its activation and characteristics, and its relationship to the deformations behaviors. This research not only provides an important platform for probing the atomic-level understanding of the fundamental mechanisms of high-pressure torsion in metallic glasses, but also leads to higher stresses and homogeneous flow near lower temperatures which is impossible previously. [ABSTRACT FROM AUTHOR]

Aims/hypothesis: Our previous study showed there was a change of microRNA (miRNA) expression profile, and miR-21 was significantly down regulated in insulin-resistant adipocytes (IR-adipocytes). Phosphatase and tensin homologs deleted on chromosome 10 (PTEN), a negative regulator of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, was identified to be a target gene of miR-21, which suggested miR-21 might be associated with insulin resistance (IR) or diabetes. However, it is not known whether miR-21 play any role in the development of IR in 3T3-L1 adipocytes. Methods: Normal adipocytes and adipocytes transfected with pre-miR-21(pmiR-21) or negative control (pNeg) were treated with high glucose and high insulin for 24 h, insulin-stimulated glucose uptake was determined by 2-Deoxyglucose transport assay, miR-21 expression level was measured by using quantitative real-time RT-PCR (qRT-PCR). The protein expression levels of PTEN, Akt, phospho-Akt (Ser473), IRβ, GSK3β, phospho-GSK3β (Ser9) and GLUT4 were detected by western blotting assay. Results: We further confirmed that miR-21 was down regulated in IR-adipocytes by qRT-PCR. Over-expression of miR-21 significantly increased insulin-induced glucose uptake and decreased PTEN protein expression, while it had no significant effect on PTEN mRNA expression in IR-adipocytes. Moreover, over-expressing miR-21 significantly increased insulin-induced phosphorylation of AKT (Ser473), GSK3β (Ser9) and the translocation of glucose transporter 4 (GLUT4) in IR-adipocytes. Conclusions: In this study, our data demonstrate that miR-21 reverses high glucose and high insulin induced IR in 3T3-L1 adipocytes, possibly through modulating the PTEN-AKT pathway, and miR-21 may be a new therapeutic target for metabolic diseases such as T2DM and obesity. [ABSTRACT FROM AUTHOR]

The response of Arabidopsis thaliana plants to elevated sulfur dioxide could be related to their endogenous salicylic acid (SA) content and signaling. The wild type (WT, ecotype Columbia) and its mutant snc1 with high SA content, npr1-1 with a blockage in SA signaling, transgenic line nahG with low SA content and double mutant snc1nahG plants were exposed to 0.5 mm dm SO for 3 h d for 14 d in a growth chamber. Under unstressed conditions, total SA contents in snc1 and npr1-1 were 7- and 2-fold higher than those in WT, respectively, but in nahG SA content was only 28 % of that in WT. The expression of nahG in snc1 plants decreased SA content to the WT level. Increased SA contents were observed in snc1, npr1-1 and WT after 12-h SO exposure, whereas no major changes were detected in nahG and snc1nahG plants. The snc1 plants exhibited higher tolerance to SO exposure than snc1nahG plants and especially nahG and npr1-1 plants according to plant biomass, total chlorophyll content and photosynthetic rate. The SO exposure decreased net photosynthetic rate, maximum photochemical efficiency (F/F) and actual quantum efficiency of photosystem 2 (Φ). SO-induced oxidative damage in the tested plants was confirmed by increased malondialdehyde (MDA) content and electrolyte leakage. Increases in superoxide dismutase (SOD) and peroxidase (POD) activity, reduced glutathione (GSH) content and a ratio of reduced/oxidized glutathione (GSSG) might be responsible for the decreased contents of HO and alleviation of oxidative injury in snc1 plants compared with other lines exposed to SO. These observations implied that endogenous SA content and signaling may play an essential role in plant responses to SO stress. [ABSTRACT FROM AUTHOR]