Among efforts to improve techniques for the chemical vapor deposition of large-area and high-quality graphene films on transition metal substrates, being able to reliably transfer these atomistic membranes onto the desired substrate is a critical step for various practical uses, such as graphene-based electronic and photonic devices. However, the most used approach, the wet etching transfer process based on the complete etching of metal substrates, remains a great challenge. This is mainly due to the inevitable damage to the graphene, unintentional contamination of the graphene layer, and increased production cost and time. Here, we report the systematic study of an H2 bubbling-assisted transfer technique for graphene films grown on Cu foils, which is nondestructive not only to the graphene film but also to the Cu substrate. Also, we demonstrate the origin of the graphene film tearing phenomenon induced by this H2 bubbling-assisted transfer process. This study reveals that inherent features are produced by rolling Cu foil, which cause a saw-like corrugation in the poly(methyl methacrylate) (PMMA)/graphene stack when it is transferred onto the target substrate after the Cu foil is dissolved. During the PMMA removal stage, the graphene tearing mainly appears at the apexes of the corrugated PMMA/graphene stack, due to weak adhesion to the target substrate. To address this, we have developed a modified heat-press-assisted transfer technique that has much better control of both tearing and the formation of residues in the transferred graphene films.

Recently, additive-free sweet potato has been commercialized as a healthier snack food. However, these products are producing by semi-dried form to extend shelf-life, hence the products also possesses hard texture during chewing. To produce crispy sweet potato snack, this study was attempted to dry the semi-dried sweet potato instantly by a hot-press (HP) process. Mashed sweet potato was reformed and semi-dried at 65°C for varying time to provide various final moisture contents. The semi-dried samples were subjected to HP at the process temperature of 175-180°C for 2 seconds. As quality parameters, moisture content, brix, color, texture and sensorial test of the products were evaluated. Based on the results, optimal quality of the product was obtained by the semi-dried sample with 15~18% moisture at which the products exhibited good crispiness with bright yellow color. When the moisture content of the sample before HP was lower than 15%, the final products were normally broken during the HP process. In addition, extreme browning appearance was generated in this condition. Conversely, the sample with more than 18% of moisture was not completely dried by HP and the final product did not possess the crispy texture, although this product showed bright yellow appearance. Consequently, this study demonstrated the potential application of HP in sweet potato processing and the best condition was greatly affected by moisture content of sample prior to HP process.

This study numerically investigates buckling behavior of press braked steel plates with a free edge. In order to improve structural stability during construction, the top flanges of press-braked U section girder are laterally braced by the installation of prefabricated half-deck. Thus, an unbraced length is taken as the longitudinal spacing of pockets on the half-deck, which are to make composite section. This study performed 3D finite element analyses to evaluate an equivalent effective width of cold-formed flange with a free edge. Through the parametric numerical analyses, the elastic buckling stresses of the cold-formed flanges with rounded corner in the cross-section were compared with those of general flat plates. Then, the equivalent effective width of the cold-formed (press-braked) flanges were numerically examined for some representative cases.