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The article presents a new approach for imaging the various conformational changes that take place, when the biotinylated triamide molecules are covalently bonded to a carbon nanotube surface. The method is shown to be extremely accurate and efficient, as compared to the other conventional methods.

The article focuses on the study conducted in Japan regarding the evolution of nucleotide sequences and organization of genes for Carotovocin from Erwinia carotovora. The authors discuss the gene organization and deduced amino acid sequences of carotovoricins in the chromosome on Salmonella enterica. Moreover, they talk about the mosaic structure of CtvEr genes and Mu-like prophage genes.

We report an inelastic neutron-scattering investigation of the longitudinal acoustic modes of C60 chains confined inside single walled carbon nanotubes. We take advantage of the orientations of the chains within the plane of the pellet sample to isolate their scattering signatures in the (Q,ω) space, which we follow as a function of temperature from 260 K up to 1100 K. The results show the progressive evolution of the confined chain from a one-dimensional (ID) crystal to a linear liquid, the transition occurring within a temperature range of ∼150 K centered around 600K. The comparison of the data obtained on monomer and polymer peapods allows extracting the speed of sound in the monomer crystalline chains (vmono = 3.5 km s-1, vpoly/vmono= 1.7). We find that the sound velocity is further reduced by half in the liquid state which reveals that the melting is not only due to harmonic additive thermal fluctuations, but that anharmonic terms in the intermolecular potential play an important role at high temperatures. [ABSTRACT FROM AUTHOR]

Whereas a statistical average of molecular ensembles has been the conventional source of information on molecular structures, atomic resolution movies of single organic molecules obtained by single-molecule real-time transmission electron microscopy have recently emerged as a new tool to study the time evolution of the structures of individual molecules. The present work describes a proof-of-principle study of the determination of the conformation of each C-C bond in single perfluoroalkyl fullerene molecules encapsulated in a single-walled carbon nanotube (CNT) as well as those attached to the outer surface of a carbon nanohorn (CNH). Analysis of 82 individual molecules in CNTs under a 120 kV electron beam indicated that 6% of the CF2-CF2 bonds and about 20% of the CH2-CH2 bonds in the corresponding hydrocarbon analogue are in the gauche conformation. This comparison qualitatively matches the known conformational data based on time- and molecular-average as determined for ensembles. The transmission electron microscopy images also showed that the molecules entered the CNTs predominantly in one orientation. The molecules attached on a CNH surface moved more freely and exhibited more diverse conformation than those in a CNT, suggesting the potential applicability of this method for the determination of the dynamic shape of flexible molecules and of detailed conformations. We observed little sign of any decomposition of the specimen molecules, at least up to 10(7) e·nm(-2) (electrons/nm(2)) at 120 kV acceleration voltage. Decomposition of CNHs under irradiation with a 300 kV electron beam was suppressed by cooling to 77 K, suggesting that the decomposition is a chemical process. Several lines of evidence suggest that the graphitic substrate and the attached molecules are very cold.

Identification of individual atoms and examination of their electronic properties in materials are the ultimate goal of all microscopy-based analytical techniques. Here, we demonstrate successful single-atom imaging and spectroscopy in low-dimensional materials using (scanning) transmission electron microscopy together with electron energy-loss spectroscopy (EELS). Edges and point defects in single-layered materials such as graphene, hexagonal boron nitride and WS(2) nanoribbons are investigated by annular dark-field imaging and EELS fine-structure analysis. Individual dopant atoms are unambiguously identified in nano-peapods. It is noteworthy that irradiation damage and specimen contamination even at the single-atom level are crucial issues in these experiments.