C58 on Au(111): a scanning tunneling microscopy study

C58 fullerenes were adsorbed onto room temperature Au(111) surface by low-energy (~6 eV) cluster ion beam deposition under ultrahigh vacuum conditions. The topographic and electronic properties of the deposits were monitored by means of scanning tunnelling microscopy (STM at 4.2 K). Topographic images reveal that at low coverages fullerene cages are pinned by point dislocation defects on the herringbone reconstructed gold terraces (as well as by step edges). At intermediate coverages, pinned monomers, act as nucleation centres for the formation of oligomeric C58 chains and 2D islands. At the largest coverages studied, the surface becomes covered by 3D interlinked C58 cages. STM topographic images of pinned single adsorbates are essentially featureless. The corresponding local densities of states are consistent with strong cage-substrate interactions. Topographic images of [C58]n oligomers show a stripe-like intensity pattern oriented perpendicular to the axis connecting the cage centers. This striped pattern becomes even more pronounced in maps of the local density of states. As supported by density functional theory, DFT calculations, and also by analogous STM images previously obtained for C60 polymers (M. Nakaya et al., J. Nanosci. Nanotechnol. 11, 2829 (2011)), we conclude that these striped orbital patterns are a fingerprint of covalent intercage bonds. For thick C58 films we have derived a band gap of 1.2 eV from scanning tunnelling spectroscopy data, STS, confirming that the outermost C58 layer behaves as a wide band semiconductor

TagF-mediated repression of bacterial type VI secretion systems involves a direct interaction with the cytoplasmic protein Fha

The bacterial type VI secretion system (T6SS) delivers effectors into eukaryotic host cells or toxins into bacterial competitor for survival and fitness. The T6SS is positively regulated by the threonine phosphorylation pathway (TPP) and negatively by the T6SS-accessory protein TagF. Here, we studied the mechanisms underlying TagF-mediated T6SS repression in two distinct bacterial pathogens, Agrobacterium tumefaciens and Pseudomonas aeruginosa. We found that in A. tumefaciens, T6SS toxin secretion and T6SS-dependent antibacterial activity are suppressed by a two-domain chimeric protein consisting of TagF and PppA, a putative phosphatase. Remarkably, this TagF domain is sufficient to post-translationally repress the T6SS, and this inhibition is independent of TPP. This repression requires interaction with a cytoplasmic protein, Fha, critical for activating T6SS assembly. In P. aeruginosa, PppA and TagF are two distinct proteins that repress T6SS in a TPP-dependent and -independent pathways, respectively. P. aeruginosa TagF interacts with Fha1, suggesting that formation of this complex represents a conserved TagF-mediated regulatory mechanism. Using TagF variants with substitutions of conserved amino acid residues at predicted protein-protein interaction interfaces, we uncovered evidence that the TagF-Fha interaction is critical for TagF-mediated T6SS repression in both bacteria. TagF inhibits T6SS without affecting T6SS protein abundance in A. tumefaciens, but TagF overexpression reduces the protein levels of all analyzed T6SS components in P. aeruginosa. Our results indicate that TagF interacts with Fha, which in turn could impact different stages of T6SS assembly in different bacteria, possibly reflecting an evolutionary divergence in T6SS control

On the isolation of TI-plasmid from Agrobacterium tumefaciens

An efficient lysis method for Agrobacterium cells was developed, which allows a reproducible isolation of the tumor inducing (TI)-plasmid. The lysis method is based on the sensitivity of this bacterium to incubation with lysozyme, n-dodecylamine,EDTA, followed by Sarkosyl, after growth in the presence of carbenicillin. We also present a procedure for the isolation of the TI-plasmid on a large scale, that might be used for the mass isolation of other large plasmids which like the TI-plasmid, can not be cleared with earlier described procedures. The purity of the plasmid preparations was determined with DNA renaturation kinetics, which method has the advantage that the plasmid need not to be in the supercoiled or open circular form

Dual Induction of New Microbial Secondary Metabolites by Fungal Bacterial Co-cultivation

We thank the College of Physical Sciences, University of Aberdeen, for provision of infrastructure and facilities in the Marine Biodiscovery Centre. We acknowledge the receipt of funding from the European Union’s Seventh Programme for Research, Technological Development and Demonstration under Grant Agreement No. 312184 (PharmaSea). MR thanks School of Science and Sport, University of the West of Scotland for providing the open-access fees required for the publication.Peer reviewedPublisher PD

2,6-Diiodo-4-nitrophenol, 2,6-diiodo-4-nitrophenyl acetate and 2,6-diiodo-4-nitroanisole: interplay of hydrogen bonds, iodo-nitro interactions and aromatic [pi]-[pi]-stacking interactions to give supramolecular structures in one, two and three dimensions

Peer reviewedPublisher PD

Single photon thermal ionization of C60

We report on experiments which show that C60 can ionize in an indirect, quasi-thermal boiloff process after absorption of a single photon. The process involves a large number of incoherently excited valence electrons and yields electron spectra with a Boltzmann distribution with temperatures exceeding 10^4 K. It is expected to be present for other molecules and clusters with a comparatively large number of valence electrons. The astrophysical consequences are briefly discussed

Establishing a Fair Playing Field for Payment by Results

The English government has encouraged private providers – known as Independent Sector Treatment Centres (ISTCs) – to treat publicly funded (NHS) patients. Providers are paid a fixed price per patient treated, adjusted to reflect geographical differences in input costs. But there may be other legitimate cost variations between providers. This report considers the regulatory and production-process constraints that could cause public and private providers costs to differ. Most of these exogenous cost differentials can be rectified by adjustments to the regulatory system or to the payment method. We find evidence that ISTCs are treating different types of patients than NHS hospitals. If these differences drive costs, payments for treatment might need to be differentiated by setting.

In Vivo screening and discovery of novel candidate thalidomide analogs in the zebrafish embryo and chicken embryo model systems

This study was supported by a Wellcome Trust-NIH PhD Studentship to SB, WDF and NV. Grant number 098252/Z/12/Z. SB, CHC and WDF are supported by the Intramural Research Program, NCI, NIH. NHG and WL are supported by the Intramural Research Program, NIA, NIH.Peer reviewedPublisher PD