Molecular Beam Epitaxial Growth of Sb2Te3-Bi2Te3 Lateral Heterostructures

We report on heteroepitaxial growth of Sb2Te3-Bi2Te3 lateral heterostructures using molecular beam epitaxy. The lateral heterostructures were fabricated by growing Bi2Te3 islands of hexagonal or triangular nanostructures with a typical size of several hundred nm and thickness of ~ 15 nm on graphene substrates and Sb2Te3 laterally on the side facets of the nanostructures. Multiple-step processes with different growth temperatures were employed to grow the lateral heterostructures. Electron microscopy techniques indicate that the inner region is Bi2Te3 and the outer Sb2Te3 was formed laterally on the graphene in an epitaxial manner. The interface between Bi2Te3 and Sb2Te3 from planar and cross-sectional views was studied by the aberration-corrected (Cs-corrected) high-angle annular dark-field scanning TEM (HAADF-STEM) technique. The cross-sectional electron microscopy investigation shows no wetting layer of Sb2Te3 on Bi2Te3, corroborating perfect lateral heterostructure formation. In addition, we investigated the topological properties of Sb2Te3-Bi2Te3 lateral heterostructures using first-principles calculations.

In Situ Transmission Electron Microscopy Investigation of Melting/Evaporation Kinetics in Anisotropic Gold Nanoparticles

We report on thermal stability and phase transition behaviors of triangular Au nanoprisms through in situ heating transmission electron microscopy. With rising temperature, Au nanoprisms exhibit fluctuating surface reconstructions at the corner regions. When a quasi-melting state is reached at the temperature below bulk melting points, the evaporation is initiated commonly at a corner with low curvature and containing sharp intersection points. The subsequent annealing process leads to the gradual evaporation, which, in the absence of thick carbon coverages, is accompanied by marked shape reconstructions. The thermal stability and evaporation behaviors are not evidently regulated by nanoprism aggregations.

The effect of V on the morphology of TiB2 particles in as-cast aluminum composites

This study presents the modification effect of trace vanadium on the in-situ formed TiB2 particles in as-cast aluminum composites. With 0.2 wt.% V addition the morphology of TiB2 was modified from hexagonal platelet or irregular feather-like shape to hexagonal prism or rectangular prism with parallel growth steps along the c-axis. Meanwhile, V rich cores were detected in the center of TiB2 and the exposure of the high-index crystal plane (1101)TiB2 was detected in Al-0.2 wt.%V. Statistical analysis of the particle size and aspect distribution both in commercial Al and Al-0.2 wt.%V was conducted. The elemental distribution and scanning electron microscopy investigation revealed that VB2 may serve as the 2D-nucleus of TiB2 particles. The growth mechanism of TiB2 under the influence of V was explored.

Ultrasound-Assisted Transglutaminase Catalysis of the Cross-Linking and Microstructure of αs-Casein, β-Casein and κ-Casein

The effects of ultrasonic treatment (UT)-assisted transglutaminase (TGase) catalysis on the physicochemical properties of individual αs-casein (αs-CN), β-casein (β-CN), and κ-casein (κ-CN) were investigated. After 60 min of incubation at 30 °C, αs-CN, β-CN, and κ-CN were cross-linked with TGase (6.0 units/mL), and high molecular weight polymers (>200 kDa) were formed. The use of TGase in conjunction with UT (20 kHz, power of 400 W, and amplitude 20%) led to an increase in the rate of αs-CN, β-CN, and κ-CN polymerization compared to the individual casein that contained TGase but did not undergo UT. SDS-PAGE scrutiny showed that the intensities of αs-CN, β-CN, and κ-CN incubation with regard to TGase and UT at 30 °C for 60 min noticeably decreased to 5.66 ± 0.39, 3.97 ± 0.43, and 26.07 ± 1.18%, respectively (p < 0.05). Particle size analysis results indicated that the molecule size appropriation for the cross-linking of αs-CN, β-CN, and κ-CN ranged from 6000 to 10,000 nm after 60 min incubation with TGase and UT. Transmission electron microscopy investigation showed network structures of cross-linking αs-CN, β-CN, and κ-CN were formed from αs-CN, β-CN, and κ-CN, respectively. As our results show, the comprehensive utilization of TGase and UT will be a superior method for the polymerization of αs-CN, β-CN, and κ-CN.