Nanosized and crystalline sp 3-bonded carbon materials were prepared over large surface areas up to ~33x51 m 2 from the exposure of few-layer graphene (FLG) to H radicals produced by the hotfilament process at low temperature (below 325 C) and pressure (50 Torr). Hybrid materials were also obtained from the partial conversion of FLG. sp 3-C related peaks from diamond and/or lonsdaleite and/or hybrids of both were detected in UV and visible Raman spectra. C-H bonding was directly detected by Fourier Transform Infrared (FTIR) microscopy over an area of ~150 m 2 and one single component attributed to sp 3-C-H mode was detected in the C-H stretching band showing that carbon is bonded to one single hydrogen and strongly suggesting that the sp 3-C materials obtained are ultrathin films with basal planes hydrogenated. The experimental results are compared to computational predictions and comprehensively discussed. Those materials constitute new synthetic carbon nanoforms after fullerenes, nanodiamonds, carbon nanotubes and graphene. This opens the door to new research in multiple areas for the development of new potential applications and may have wide scientific impact, including for the understanding of extraterrestrial diamond-related structures and polytype formation mechanism(s).

The conformational/configurational dependence of the frequencies of the deuterium-isolated C–H stretching modes of the gas-phase alkanes C1, C2, n-C3, n-C4(t and g), n-C5(tt and gt), cyclo-C6, iso-C4, and neo-C5 are reported. Most of the isolated C–H frequencies were obtained from Raman spectra of specifically and randomly protonated deuterohydrocarbons. An extraordinarily precise correlation is found between the observed isolated C–H frequencies and the corresponding ab initio calculated C–H bond lengths. In the case of the n-alkanes, the observed C–H frequencies tend to fall in clusters that are regularly spaced with an average separation of about 14.5±1 cm−1. The clustering occurs because the isolated C–H stretching frequencies are determined by the structure of the n-alkane in the immediate vicinity of the C–H bond. The relation between frequency and local structure can be expressed in a simple way and used to predict the effect of conformational change.

No abstract

Plaques composed of the Abeta peptide are the main pathological feature of Alzheimer's disease. Dense-core plaques are fibrillar deposits of Abeta, showing all the classical properties of amyloid including beta-sheet secondary structure, while diffuse plaques are amorphous deposits. We studied both plaque types, using synchrotron infrared (IR) microspectroscopy, a technique that allows the chemical composition and average protein secondary structure to be investigated in situ. We examined plaques in hippocampal, cortical and caudal tissue from 5- to 21-month-old TgCRND8 mice, a transgenic model expressing doubly mutant amyloid precursor protein, and displaying impaired hippocampal function and robust pathology from an early age. Spectral analysis confirmed that the congophilic plaque cores were composed of protein in a beta-sheet conformation. The amide I maximum of plaque cores was at 1623 cm(-1), and unlike for in vitro Abeta fibrils, the high-frequency (1680-1690 cm(-1)) component attributed to antiparallel beta-sheet was not observed. A significant elevation in phospholipids was found around dense-core plaques in TgCRND8 mice ranging in age from 5 to 21 months. In contrast, diffuse plaques were not associated with IR detectable changes in protein secondary structure or relative concentrations of any other tissue components.

No abstract