Tecnai f20

Experiments were conducted using a FEI Tecnai F20 and a probe-side Cs-corrected JEOL JEM 2200FS microscopes, both operated at 200 kV acceleration voltage. Overview images were taken in conventional bright-field TEM mode while the high-angle annular dark-field STEM mode was used for the high-resolution micrographs. Samples were prepared by casting and evaporating a droplet of solution onto a carbon-coated copper grid (300 mesh). The average diameter of NPs was calculated from TEM images by analysis of about 1000 NPs for each sample using ImageJ software. EDX elemental mapping was carried out in the scanning mode utilizing an Oxford X-max detector.

The Co_65−xCr₁₃Mo₂₂Cu_x (x = 0, 0.5 and 1 at.%) alloys were prepared by arc-melting of Co, Cr, Mo and Cu of 99.99% purity under Ar atmosphere on a water-cooled Cu hearth. Cylindrical rods with 2 mm diameter and 50 mm length were fabricated using suction casting into a water-cooled Cu mold. Phase analysis was carried out by X-ray diffraction (XRD, Rigaku-D/MAX-2500/PC) with Cu Kα₁ radiation (λ = 1.5406 Å). Structural analysis was performed using scanning electron microscopy (SEM, JEOL JSM-6390) and transmission electron microscopy (TEM, Tecnai-F20). Thin foil samples for TEM analysis were prepared by conventional ion milling (Gatan, Model 600) and focused ion beam thinning (FIB, Helios D-456). The mechanical properties at room temperature were evaluated under uniaxial compression loading with an initial strain rate of 10⁻³/s. For compression testing, cylindrical specimens with a 2:1 aspect ratio were prepared from the as-cast rods. Indentation tests were performed in a load-control mode conducted with a different maximum loading condition from 10 mN to 200 mN using a Nanoindenter (CSM, NHT-X). The hardness and the elastic modulus were derived using the Oliver-Pharr method50 .

Samples for transmission electron microscopy (TEM) were prepared by the negative staining method using a 2% w/v solution of uranyl acetate (Electron Microscopy Sciences) in distilled water. Virus samples were diluted to approximately 20–100 μg/mL protein in Tris-buffered saline (10 mM Tris, 150 mM NaCl, pH = 7.5). Briefly, 3 μL of diluted virus sample was applied to glow discharged (PELCO easiGlow, TED PELLA) formvar/copper support film TEM grids (Electron Microscopy Sciences). Following a brief incubation of 30 s, the sample was blotted away from the grid using filter paper (Whatman). Sample-laden grids were washed twice by contact with two successive droplets of distilled water, and subsequently dabbed twice into droplets of uranyl acetate solution. Micrographs were obtained using a Hitachi 7,500 (Hitachi) TEM at the Icahn School of Medicine at Mount Sinai, and a Tecnai F20 (Field Electron and Ion company) and JEOL JEM-1230 (Gatan) TEMs at the New York Structural Biology Center.