Preferred sizes and ordering in surface nanobubble populations

Two types of homogeneous surface nanobubble populations, created by different means, are analyzed statistically on both their sizes and spatial positions. In the first type (created by droplet-deposition, case A) the bubble size R is found to be distributed according to a generalized gamma law with a preferred radius R*=20 nm. The radial distribution function shows a preferred spacing at ~5.5 R*. These characteristics do not show up in comparable Monte-Carlo simulations of random packings of hard disks with the same size distribution and the same density, suggesting a structuring effect in the nanobubble formation process. The nanobubble size distribution of the second population type (created by ethanol-water exchange, case B) is a mixture of two clearly separated distributions, hence, with two preferred radii. The local ordering is less significant, due to the looser packing of the nanobubbles.Comment: 5 pages, 5 figure

Superstability of Surface Nanobubbles

Shock wave induced cavitation experiments and atomic force microscopy measurements of flat polyamide and hydrophobized silicon surfaces immersed in water are performed. It is shown that surface nanobubbles, present on these surfaces, do not act as nucleation sites for cavitation bubbles, in contrast to the expectation. This implies that surface nanobubbles are not just stable under ambient conditions but also under enormous reduction of the liquid pressure down to −6MPa. We denote this feature as superstability.Comment: 5 pages, 2 figure

Nanoindentation in graphene reinforced polymers

Conferencia invitada. -- POLYCHAR 25, Kuala Lumpur, Malaysia on October 9 – 13, 2017. -- http://www.25polychar.org.my/Peer Reviewe

Internal integration as a pre-condition for external integration in global sourcing: A social capital perspective

The purpose of this study is to explore the link between integration and global sourcing success in international operations and by doing so, to clarify the ambiguous picture that prevails in the existing literature. Specifically, this quantitative study aims at identifying the role of the buying companies’ internal and external integration with suppliers using a social capital lens. Data were collected from the central purchasing department of a multinational automotive OEM located in Germany. A sample of 82 purchasers was surveyed about their assessment of global sourcing projects, focusing on internal cross-functional integration, external supplier integration and project success. The data were analyzed with structural equation modeling procedures, using SmartPLS. The findings indicate that internal integration is a precondition for external integration with suppliers, which accordingly has a strong positive influence on global sourcing success. Surprisingly, the direct relationship between internal and external integration was not significant, indicating a mediating role of social capital within this relationship. The theoretical originality lies in the use of the social capital theory and its three dimensions: cognitive, structural and relational capital for both internal and external integration, and in the connection between integration and global sourcing success. From a practical perspective, it can be recommended that managers distinguish between an internal and an external perspective. Internally, the focus should lie on the clear communication of common goals and norms, whereas externally, the definition of mutual contact points between organizations is of higher importanc