Hydrogen termination hydrophobicity

There wiU be an electrostatic attraction between the positive space charge in the diamond and the excess solvated anions in the water film. These solvated anions provide a mechanism for binding the water film to the hydrogen-terminated, hydrophobic diamond surface. 

An as-grown BDD film is typically hydrogen-terminated and its surface is hydrophobic anodic polarization at lOmAcm during 30 min results in the transformation of the BDD surface from hydrophobic to hydrophilic. Alternatively, a quite hydrophilic surface can be obtained by thermally treating the BDD support at 400 °C for 30 min under oxygen. 

The surface of silicon can be hydrophilic or hydrophobic depending on the surface condition. It has been reported that a hydrophilic surface is characterized by OH groups and a hydrophobic surface is covered with Si-H, Si-CH , or Si-F groups. Thus, a hydrogen-terminated surface is hydrophobic whereas an oxide- or hydroxide-covered surface, which tends to be terminated by OH, is, in general, hydrophilic. A surface covered with a substantial amount of carbon bonded to oxygen is hydrophobic. 

Finally, when the BDD is removed from the CVD diamond reactor, it is hydrogen (H-) terminated, which also confers hydrophobic properties on the surface. Contact angles of 90 have been measured using water [34]. The question of how long the hydrogen termination lasts, especially after oxidative electrochemical treatment [4,17], is an important one to consider therefore at the minimum, simple contact angle verification before and after experiment is a necessary and important measurement to make. 

For example, a mild HF etch (1 100) is used in cleaning glass for flat panel display production. Hydrofluoric acid solution is a common etchant for sihcon and can leave a sihcon surface either hydrogen- or hydroxyl-terminated. The silicon surface is hydrophobic ( wata--hating ) if hydrogen-terminated, and hydrophilic ( water-loving ) if hydroxyl-terminated. 

Rieske proteins from complexes contain an insertion of 11 residues between strands (31 and (32 compared to mitochondrial Rieske proteins as well as an extension of 16 residues at the C-terminus. In the N-terminal part, there is an additional short (3 strand (/31 ), as well as a short helix that has no counterpart in the mitochondrial Rieske protein or in NDO. The N-terminus of (3 strand /31 is hydrogen-bonded to strand (310 in (3 sheet 1 as it is in the other Rieske proteins, but the end of strand (31 connects to strand (32 in (3 sheet 2 thus, the sandwich structure of the (3 sheets 1 and 2 is perturbed and a barrellike structure is formed. The core of this barrel is less hydrophobic than the core of the sandwich formed by /3 sheets 1 and 2 in the ISF. 

While loops lack apparent stmcmral regularity, they exist in a specific conformation stabilized through hydrogen bonding, salt bridges, and hydrophobic interactions with other portions of the protein. However, not all portions of proteins are necessarily ordered. Proteins may contain disordered regions, often at the extreme amino or carboxyl terminal, characterized by high conformational flexibility. In many instances, these disor-... 

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