We report here on the genome sequence of Pasteurella multocida Razi 0002 of avian origin, isolated in Iran. The genome has a size of 2,289,036 bp, a GC content of 40.3%, and is predicted to contain 2,079 coding sequences.

We report the photoreactivity of H−Si(111) with dioxygen and terminally unsaturated hydrocarbons. Illumination of H−Si(111) in air with ultraviolet light of wavelength of 350 nm or shorter produces oxidized silicon; longer wavelengths cause no oxidation. When H−Si(111) is immersed in unsaturated hydrocarbons (1-octene, 1-octadecene, 1-octyne, styrene, and phenylacetylene) that have been deoxygenated, illumination with a Hg lamp results in densely packed hydrocarbon films of molecular thickness. Previous work and the results presented here suggest that the H−Si bond adds across the unsaturated bond in these reactions similar to hydrosilylation reactions known for small-molecule chemistry and produce adsorbates covalently bonded to the surface. We present spectroscopic evidence showing films resulting from terminal acetylenes consist of adsorbates linked to the surface by a vinyl group. We propose that all of these reactions occur through a radical-chain mechanism initiated by the wavelength-dependent photodesorption of surface hydrogen by UV light. We also present a method in the Appendix to quantify surface adsorbate coverage using XPS and ellipsometric data.

We report the surface chain reaction of styrene with hydrogen-terminated Si(111), H-Si(111) initiated at isolated surface dangling bonds. Electrons from a scanning tunneling microscope in ultrahigh vacuum are used to create surface isolated dangling bonds on H-Si(111) prepared by aqueous ammonium fluoride etch. Exposure of dangling bonds on an otherwise hydrogen terminated surface to as little as 5 langmuirs of styrene leads to the formation of compact islands containing multiple styrene adsorbates bonded to the surface through individual C-Si bonds. From this observation we conclude that these adsorbate islands are the result of a surface chain reaction of styrene with H-Si(111). This result suggests that the key radical-chain propagation step of hydrogen atom abstraction from the silicon surface for the proposed mechanism of reaction of liquid phase terminally unsaturated organic molecules with hydrogen-terminated silicon under free-radical conditions readily occurs.

No abstract

Optical nanostructures have enabled the creation of subdiffraction detection volumes for single-molecule fluorescence microscopy. Their applicability is extended by the ability to place molecules in the confined observation volume without interfering with their biological function. Here, we demonstrate that processive DNA synthesis thousands of bases in length was carried out by individual DNA polymerase molecules immobilized in the observation volumes of zero-mode waveguides (ZMWs) in high-density arrays. Selective immobilization of polymerase to the fused silica floor of the ZMW was achieved by passivation of the metal cladding surface using polyphosphonate chemistry, producing enzyme density contrasts of glass over aluminum in excess of 400:1. Yields of single-molecule occupancies of Ϸ30% were obtained for a range of ZMW diameters (70 -100 nm). Results presented here support the application of immobilized single DNA polymerases in ZMW arrays for long-read-length DNA sequencing.fluorescence ͉ metal passivation ͉ microscopy ͉ polyvinyl phosphonic acid ͉ single molecule N anofabrication techniques have enabled new approaches to interrogate individual biomolecules by fluorescence techniques (reviewed in refs. 1 and 2). The extremely small size scale of the associated devices results in a drastic illumination volume reduction, allowing single-molecule investigations to take place at fluorophore concentrations increased to biologically relevant levels. In addition to higher temporal resolution and higher signal-to-noise ratios, they also provide spatial resolution beyond diffraction-limited optics.The zero-mode waveguide (ZMW) is one such nanophotonic confinement structure often consisting of a circular hole in a metal cladding film on a solid transparent substrate (3). In conjunction with laser-excited fluorescence, they provide observation volumes on the order of zeptoliters (10 Ϫ21 l), three to four orders of magnitude smaller than far-field excitation volumes. Applications of circular ZMWs have included the detection of single-molecule DNA polymerase activity by using labeled nucleotides at micromolar concentrations (3), the study of -repressor oligomerization dynamics (4), two-color crosscorrelation to rapidly screen for DNA restriction enzyme activity (5), and diffusion analysis of labeled membrane proteins in lipid bilayers of model membranes and living cells (6-11). C-shaped apertures have been described to study DNA hybridization interactions (12).ZMW technology applications have been limited by the unavailability of selective immobilization methods to position molecules exclusively in the observation volume, immediately above the transparent ZMW floor. One approach to selective immobilization exploits a feature inherent in the ZMW architecture. The transparent substrate and metal cladding are made of different materials, opening the possibility for a selective derivatization that will direct protein adsorption to the floor and not to the nearby metal walls. The nanometer size scale and three-dimensional n...