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With sufficient high cooling rates, a variety of liquids, including metallic melts, will cross a glass transition temperature and solidify into glass accompanying a marked increase of the shear viscosity in approximately 17 orders of magnitude. Because of the intricate atomic structure and dynamic behaviours of liquid, it is yet difficult to capture the underlying structural mechanism responsible for the marked slowing down during glass transition, which impedes deep understanding of the formation and nature of glasses. Here, we report that a universal structural indicator, the average degree of five-fold local symmetry, can well describe the slowdown dynamics during glass transition. A straightforward relationship between structural parameter and viscosity (or α-relaxation time) is introduced to connect the dynamic arrest and the underlying structural evolution. This finding would be helpful in understanding the long-standing challenges of glass transition mechanism in the structural perspective. The structural origin of the dynamic slow down during glass transition remains an open question because of the lack of atomic-scale elucidation. Here, Hu et al. propose a parameter to link the structural evolution of the average degree of five-fold local symmetry to dynamic arrest in metallic liquids.

Emerging evidence suggests the potential involvement of altered regulation of miRNAs in the pathogenesis of cancers, and these miRNAs are thought to be functional as tumor suppressors or oncogenes. Using miRNA arrays, we identified an miRNA differentially expressed between the MDA-MB-231 cell line and its highly metastatic variant. A bioinformatics search revealed a potential target site for miR-193b within the 3′UTR of uPA. Ectopic expression of miR-193b repressed the expression of sensor constructs harboring the 3′UTR of uPA in breast cancer cell lines. Anti-miR-193b treatment led to an increase of uPA protein and increased cell invasion in MDA-MB-231 cells. In contrast, overexpression of miR-193b significantly reduced uPA protein amounts and inhibited cell invasion in MDA-MB-231 and MDA-MB-435 cells. In an immunodeficient mouse model, miR-193b significantly inhibited the growth and dissemination of xenograft tumors. Immunohistochemical staining and real-time PCR assays showed that miR-193b was a negative regulator of the uPA gene in primary breast tumors. Our research reveals that miR-193b is closely associated with clinical metastasis and identifies miR-193b potentially targets uPA transcripts. Perturbation of the miRNA–mRNA pairing may have important roles in the initiation and development of breast cancer.

Thermal barrier coatings (TBCs) applied to turbine blades in aviation engines and gas turbines often experience erosion damage from small solid particles. This damage is directly linked to the microscale pores randomly distributed within the TBCs, impacting their erosion resistance. The effects of pore-related parameters, such as radius, porosity, and distribution pattern, on the particle impact resistance of Air Plasma-Sprayed Thermal Barrier Coatings (APS-TBCs) using finite element simulations under high-temperature conditions, taking into account the particle initial velocity and incidence angle in this study. The results reveal that changes in pore structure and porosity significantly affect the erosion damage of coatings. In general, the relationship between crack propagation length and particle erosion velocity satisfies an exponential function. In addition, the material loss (Δm) of the coatings exhibits significant fluctuations with the increasing pore radius (0–1 μm), and the optimal pore radius is 0.3 μm for superior erosion resistance; The Δm is achieved around 4% porosity, after which the Δm tends to stabilize with increasing porosity. Additionally, the obtained results show that more pores in the upper layer or near the impact zone lead to more severe erosion, while the erosion quality of the coating increases with the increase of the erosion angle.

The relaxation of amorphous materials, i.e., aging, would largely endanger their performances in service. Here we report a mechanical relaxation-to-rejuvenation transition of a Zr 35 Ti 30 Be 27.5 Cu 7.5 bulk metallic glass (BMG) in elastostatic compression at ambient temperature, thus provide an accessible way to tailor the mechanical properties of amorphous materials. To unravel the structural evolution underlying the observed transition, atomistic simulations parallel with the experimental tests on a typical model glass system Zr 60 Cu 40 were performed, which successfully reproduced and thus upheld the experimentally observed mechanical relaxation-to-rejuvenation transition. The variations of coordination number and atomic volume during the transition are evaluated to indicate a de-mixing tendency of the constituent atoms in the rejuvenation stage. This de-mixing tendency largely explains the difference between mechanical rejuvenation and thermal rejuvenation and reveals a competitive relationship between activation enthalpy and activation entropy in the stress-driven temperature-assisted atomic dynamics of BMG, such as diffusion and plastic deformation etc.

The aerodynamic drag of a cyclist in time trial (TT) position is strongly influenced by the torso angle. While decreasing the torso angle reduces the drag, it limits the physiological functioning of the cyclist. Therefore the aims of this study were to predict the optimal TT cycling position as function of the cycling speed and to determine at which speed the aerodynamic power losses start to dominate. Two models were developed to determine the optimal torso angle: a ‘Metabolic Energy Model’ and a ‘Power Output Model’. The Metabolic Energy Model minimised the required cycling energy expenditure, while the Power Output Model maximised the cyclists׳ power output. The input parameters were experimentally collected from 19 TT cyclists at different torso angle positions (0–24°). The results showed that for both models, the optimal torso angle depends strongly on the cycling speed, with decreasing torso angles at increasing speeds. The aerodynamic losses outweigh the power losses at cycling speeds above 46km/h. However, a fully horizontal torso is not optimal. For speeds below 30km/h, it is beneficial to ride in a more upright TT position. The two model outputs were not completely similar, due to the different model approaches. The Metabolic Energy Model could be applied for endurance events, while the Power Output Model is more suitable in sprinting or in variable conditions (wind, undulating course, etc.). It is suggested that despite some limitations, the models give valuable information about improving the cycling performance by optimising the TT cycling position.

Zinc bioavailability to aquatic organisms varies greatly under different pH values. In the present study, five native species in China and four common international test species were selected to investigate the influence of changing pH on acute zinc toxicity. The results showed that the higher trophic levels exhibited increasing sensitivity to zinc as pH decreased. However, when the pH value was between 8 and 11, the acute toxicity of zinc was relatively constant. In addition, by using a species-sensitivity distribution (SSD) method, the short-term hazardous concentrations of zinc at different pH values (based on the 5th percentiles of the pH-specific SSDs) were determined to be 17.26 µg/L (pH 4), 48.31 µg/L (pH 5), 80.34 µg/L (pH 6) and 230.6 µg/L (pH 7), respectively. The present study provides useful information for deriving water quality criteria and assessing the risks of metals in the near future.

The phenomenon of poor cycle stability can be effectively solved by using metal–organic frameworks (MOFs) as precursor to obtain oxides. In this work, a layered NiO@NiCo 2 O 4 nanocomposite electrodes were designed from bimetallic (Ni/Co) based bimetallic metal–organic framework (Ni/Co-MOF) by simple hydrothermal method followed by subsequent controlled calcination under air atmosphere at various temperatures for the transition process. XRD and FE-SEM studies were substantiating the formation of MOF derived NiO@NiCo 2 O 4 nanocomposite with layered structure. Interestingly, electrochemical studies shows that MOF derived NiO@NiCo 2 O 4 nanocomposite achieved at the calcination temperature at 300 °C and 400 °C demonstrates high specific capacitance of 2461 F/g and 2180 F/g at the current density of 1 A/g, which keeps the precursor Ni/Co-MOF with high specific capacitance peculiarity of 2250 F/g at 2 A/g. In terms of cycle retention rate, the NiO@NiCo 2 O 4 nanocomposite obtained at 400 °C still has a high retention rate of 78% under the current density of 15 A/g for 4500 cycles. It significantly improved the precursor Ni/Co-MOF low cycle retention rate of only 56% after 1000 cycles. The results show that the metal oxide nanocomposites calcined with MOFs as sacrificial template not only retain the high specific capacitance characteristics of MOFs, but also improve its low cycle stability, which has great potential in electrochemical supercapacitor electrode materials and provides a certain useful reference for the direction of global energy demand.

The delamination of a circular thin film at micro/nanoscale is studied using the Kirchhoff plate theory incorporating surface effects in this paper. Bending of a clamped circular nanoplate subjected to a concentrated force at the center or a uniformly distributed force over a lateral surface is solved. The bending deflection is derived in closed form. The adhesion energy and its release rate for delamination are determined when surface effects are taken into account. The influences of surface residual stress and surface elasticity along with the film’s size on the energy release rate of debonding advance or interfacial adhesion of a thin film bonded to an elastic substrate are analyzed for applied loading or given displacements. Analytic results are compared with experimental data and satisfactory agreement is confirmed.

Electron beam polarization in the bubble regime of the interaction between a high-intensity laser and a longitudinally pre-polarized plasma is investigated by means of the Thomas–Bargmann–Michel–Telegdi equation. Using a test-particle model, the dependence of the accelerated electron polarization on the bubble geometry is analysed in detail. Tracking the polarization dynamics of individual electrons reveals that although the spin direction changes during both the self-injection process and acceleration phase, the former has the biggest impact. For nearly spherical bubbles, the polarization of electron beam persists after capture and acceleration in the bubble. By contrast, for aspherical bubble shapes, the electron beam becomes rapidly depolarized, and the net polarization direction can even reverse in the case of a oblate spheroidal bubble. These findings are confirmed via particle-in-cell simulations.

The temperature evolution of icosahedral medium-range order formed by interpenetrating icosahedra in CuZr metallic glassforming liquids was investigated via molecular dynamics simulations. Scaling analysis based on percolation theory was employed, and it is found that the size distribution of clusters formed by the central atoms of icosahedra at various temperatures follows a very good scaling law with the cluster number density scaled by S − τ and the cluster size S scaled by |1 −  T c / T | −1/ σ , respectively. Here T c is scaling crossover-temperature. τ and σ are scaling exponents. The critical scaling behaviour suggests that there would be a structural phase transition manifested by percolation of locally favoured structures underlying the glass transition, if the liquid could be cooled slowly enough but without crystallization intervening. Furthermore, it is revealed that when icosahedral short-range order (ISRO) extends to medium-range length scale by connection, the atomic configurations of ISROs will be optimized from distorted ones towards more regular ones gradually, which significantly lowers the energies of ISROs and introduces geometric frustration simultaneously. Both factors make key impacts on the drastic dynamic slow-down of supercooled liquids. Our findings provide direct structure-property relationship for understanding the nature of glass transition.