Photoluminescence properties of non-tapered InN nanorods grown by plasma-assisted metalorganic chemical vapor phase deposition

We have successfully grown non-tapered InN nanorods on Si substrate using an RF plasma assisted metalorganic chemical vapor deposition technique. Employment of 50 W nitrogen plasma reduces the optimal growth temperature to 500 degrees C. In order to study the temperature dependent bandgap and thermal quenching mechanism in relation to the localized states, photoluminescence measurement over a temperature range from 7 to 160 K are conducted. The photoluminescence at 7 K shows a strong near-band-emission energy of 0.682 eV with a narrow band width of 0.027 eV, which reveals excellent optical and structural qualities of the InN nanorods.

Structural basis for recognition and repair of the endogenous mutagen 8-oxoguanine in DNA

Spontaneous oxidation of guanine residues in DNA generates 8-oxoguanine (oxoG). By mispairing with adenine during replication, oxoG gives rise to a G x C --> T x A transversion, a frequent somatic mutation in human cancers. The dedicated repair pathway for oxoG centres on 8-oxoguanine DNA glycosylase (hOGG1), an enzyme that recognizes oxoG x C base pairs, catalysing expulsion of the oxoG and cleavage of the DNA backbone. Here we report the X-ray structure of the catalytic core of hOGG1 bound to oxoG x C-containing DNA at 2.1 A resolution. The structure reveals the mechanistic basis for the recognition and catalytic excision of DNA damage by hOGG1 and by other members of the enzyme superfamily to which it belongs. The structure also provides a rationale for the biochemical effects of inactivating mutations and polymorphisms in hOGG1. One known mutation, R154H, converts hOGG1 to a promutator by relaxing the specificity of the enzyme for the base opposite oxoG.