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It has been decade-long and enduring efforts to decipher the structural mechanism of plasticity in metallic glasses; however, it still remains a challenge to directly reveal the structural change, if any, that precedes; and dominant plastics flow in them. Here, by using the dynamic atomic force microscope as an "imaging" as well as a "forcing" tool, we unfold a real-time sequence of structural evolution occurring on the surface of an Au-Si thin film metallic glass. In sharp contrast to the common notion that plasticity comes along with mechanical softening in bulk metallic glasses, our experimental results directly reveal three types of nano-sized surface regions, which undergo plasticity but exhibit different characters of structural evolution following the local plasticity events, including stochastic structural rearrangement, unusual local relaxation and rejuvenation. As such, yielding on the metallic-glass surface manifests as a dynamic equilibrium between local relaxation and rejuvenation as opposed to shear instability in bulk metallic-glasses. Our finding demonstrates that plasticity on the metallic glass surface of Au-Si metallic glass bears much resemblance to that of the colloidal gels, of which nonlinear rheology rather than shear instability governs the constitutive behavior of plasticity. [ABSTRACT FROM AUTHOR]

The near constant loss (NCL) in relaxation spectra is a crucial dynamic phenomenon for glassforming materials, while its underlying mechanism remains unclear and is hard to study due to the absence of characteristic time scale. We define a characteristic crossover point from both the dynamic mechanical measurements and the quasi-static tension experiments in the metallic glasses (MGs), to study the transition regime, where the NCL dynamics terminates and evolves to the initiation of the β-relaxation. It is found that such transition shows an apparent activation energy well below that of the β-relaxation. Our results also show the concomitant change of the crossover points and the NCL with aging and provide a cursory physical picture on how the NCL occurs, decays and evolves to the β- and a-relaxations in MGs. [ABSTRACT FROM AUTHOR]

It has been postulated that metallic glasses, in contrast to their crystalline counterparts, exhibit nano-scale structural heterogeneity which is crucial for understanding the long-standing issues of relaxations and deformation of glasses. We fabricate micrometer scale metallic glassy fibers (MGFs) with different diameters and structural configurations, and find that the thinner MGFs cooled down with faster cooling rates have smaller superconducting transition temperatures and wider transition widths. We show that the superconducting properties correlate with the heterogeneous microstructure of metallic glasses and can be used as a novel way to experimentally characterize the structural heterogeneity of metallic glasses. [ABSTRACT FROM AUTHOR]

OBJECTIVE: MicroRNA-361-5p (miR-361-5p) has been found to be involved in the pathogenesis of several human cancers. However, the specific role of miR-361-5p is still unclear in hepatocellular carcinoma (HCC). Therefore, this study was designed to elucidate the function of miR-361-5p in HCC. PATIENTS AND METHODS: The expression levels of miR-361-5p and Wilms' tumor-1 (WT1) were detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) assay. Moreover, the function of miR-361-5p was examined through Cell Counting Kit-8 (CCK-8) and transwell assays. The protein expressions were examined via Western blot analysis and immunocytochemical assay. Tumor growth of HCC was observed via xenograft tumor formation assay. The relationship between miR-361-5p and WT1 was verified by the Dual-Luciferase assay. RESULTS: Downregulation of miR-361-5p was identified in HCC, which predicted a worse prognosis in HCC patients. Furthermore, it was found that miR-361-5p suppressed cell proliferation, migration, and invasion in HCC by inhibiting WT1. MiR-361-5p also inhibited tumor growth of HCC. Besides that, miR-361-5p suppressed EMT and negatively activated the WNT/β-cadherin pathway in HCC. CONCLUSIONS: MiR-361-5p suppressed tumorigenesis of HCC by targeting WT1 and inactivating the WNT/β-cadherin pathway. [ABSTRACT FROM AUTHOR]

Bulk metallic glasses have excellent thermoforming ability in their wide supercooled liquid region. We show that large-size metallic glass grating (∼8 × 8 mm2) with fine periodicity and ultra smooth surface feature can be readily fabricated by hot embossing. The method for fabrication of gratings is proved to be much cheaper, and requires low pressure and short time (less than 30 s). The metallic glass gratings exhibit comparable optical properties such as rainbow-like spectrum when shone by fluorescent lamp light. [ABSTRACT FROM AUTHOR]

The microstructure and room temperature magnetic properties for (Nd0.8Ce0.2)1.6Fe12Co2BZrx (x = 0-5) nanocomposite alloys prepared by melt-spinning method and subsequent thermal annealing have been investigated. Zr addition has proved to result in relevant improvements in the microstructure and magnetic properties. The enhanced coercivity Hcj of 6.02 kOe and maximum energy products (BH)max of 15.2 MGOe have been obtained at the optimum temperature Ta with the Zr content at x = 2 and x = 3, respectively. The results of X-ray diffraction (XRD) and transmission electron microscope (TEM) indicate that a small amount of Zr addition can refine the grain size and cause a uniform distribution of soft magnetic α-Fe phase. A first-order-reversal curve (FORC) analysis is performed for the Zr-free (x = 0) sample and the Zr-doped (x = 3) sample. The FORC diagrams suggest the Zr-doped sample with a higher maximum ρ of the major peak and the flat surface is responsible for the better magnetic performance. The results of Kronmüller plot show that nucleation model is the dominating mechanism for the magnetization reversal in the Zr-free and Zr-doped alloys and give the evidence for the increase in microstructural parameter αex resulting in a drastic increase of coercivity in the Zr-doped alloy. [ABSTRACT FROM AUTHOR]

Studies the pressure dependence of ultrasonic attenuation in Zr[sub 41]Ti[sub 14]Cu[sub 12.5]Ni[sub 10-x]Be[sub 22.5]C[sub x] bulk metallic glasses by using a pulse echo overlap method. Glass forming ability; Effects of carbon addition on changes of the alpha[1] and alpha[sub s].

In contrast to most metallic glasses (MGs) which exhibit weak β-relaxation peak in their dynamic mechanical spectra, the LaGa-based MGs we report here show a distinct β-relaxation peak with the ratio of β/α-relaxation peaks up to 0.32 in the mechanical relaxation measurements. Moreover, the β-relaxation behavior can be tuned by modification of the chemical composition and the concentration of flow units. The effects of gallium and structural origin of the β-relaxation in the MGs have been discussed. The LaGa-based MGs with pronounced slow β-relaxation could provide a model system to investigate some underlying issues of the relaxation and plastic mechanism of MGs. [ABSTRACT FROM AUTHOR]