The clean-off reaction of AgO added rows by CO on Ag(110) and Au/Ag(110) bimetallic surfaces was studied by scanning tunneling microscopy (STM) and compared with density functional theory (DFT). This combined study of a model system illustrated the complexity of catalytic enhancement in bimetallic systems. By analyzing in situ time-lapsed STM image series, we found that CO oxidation on a Au-enriched Ag(110) surface leads to an exponential depletion of oxygen with time and a reaction rate that is synergistically enhanced by the presence of Au. First principles calculations indicate that the local atomic configuration around the active reaction sites at the chain ends and the preference of An atom substitution into the subsurface second Ag layer are of critical importance. By calculating CO adsorption energies and reaction barriers for plausible reaction pathways, a detailed description of the CO oxidation reaction emerges, For the optimal reaction pathway, a large (similar to 0.09 eV) barrier reduction and a small barrier of similar to 0.01 eV were found for the Eley-Rideal (ER) mechanism. In contrast, a small (similar to 0.03 eV) barrier reduction and a moderate barrier of similar to 0.23 eV were obtained for the Langmuir-Hinshelwood (LH) mechanism. The ER transitional state was also found to be lower in energy. We conclude that, irrespective of whether the ER mechanism is actually rate dominating, it is definitively enhanced.

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A handheld device based on fluorescence of 3,6-bis(1-methyl-4-vinylpyridinium) carbazole diiodide (BMVC) staining was established for the rapid, point-of-care screening of cancer cells (see Chang and co-workers, Analyst, 2007, 132, 745). Offering instant screening of cancer at low cost, here we apply this simple assay in clinical tests on fine needle aspirates of neck masses from 114 outpatients (115 specimens). The diagnostic accuracy of this simple method alone is ca. 80% (80/99). The combination of the BMVC test and the fine needle aspiration (FNA) cytology reduced the non-diagnosis from 17 cases in FNA cytology to 6 cases in the combined method. Moreover, an algorithm is proposed to improve the diagnostic accuracy of malignant neck lumps up to nearly 100%.

Carbazole derivatives that stabilized G-quadruplex DNA structure formed by human telomeric sequence have been designed and synthesized. Among them, 3,6-bis(1-methyl-4-vinylpyridinium)carbazole diiodide (BMVC) showed an increase in G-quadruplex melting temperature by 13 degrees C and has a potent inhibitory effect on telomerase activity. Treatment of H1299 cancer cells with 0.5 mu mol/L BMVC did not cause acute toxicity and affect DNA replication; however, the BMVC-treated cells ceased to divide after a lag period. Hallmarks of senescence, including morphologic changes, detection of senescence-associated beta-galactosidase activity, and decreased bromodeoxyuridine incorporation, were detected in BMVC-treated cancer cells. The BMVC-induced senescence phenotype is accompanied by progressive telomere shortening and detection of the DNA damage foci, indicating that BMVC caused telomere uncapping after long-term treatments. Unlike other telomerase inhibitors, the BMVC-treated cancer cells showed a fast telomere shortening rate and a lag period of growth before entering senescence. Interestingly, BMVC also suppressed the tumor-related properties of cancer cells, including cell migration, colony-forming ability, and anchorage-independent growth, indicating that the cellular effects of BMVC were not limited to telomeres. Consistent with the observations from cellular experiments, the tumorigenic potential of cancer cells was also reduced in mouse xenografts after BMVC treatments. Thus, BMVC repressed tumor progression through both telomere-dependent and telomere-independent pathways.

Earlier work from our laboratory has indicated that a hemerythrin-like protein was over-produced together with the particulate methane monooxygenase (pMMO) when Methylococcus capsulatus (Bath) was grown under high copper concentrations. A homologue of hemerythrin had not previously been found in any prokaryote. To confirm its identity as a hemerythrin, we have isolated and purified this protein by ion-exchange, gel-filtration and hydrophobic interaction chromatography, and characterized it by mass spectrometry, UV-visible, CD, EPR and resonance Raman spectroscopy. On the basis of biophysical and multiple sequence alignment analysis, the protein isolated from M. capsulatus (Bath) is in accord with hemerythrins previously reported from higher organisms. Determination of the Fe content in conjunction with molecular-weight estimation and mass analysis indicates that the native hemerythrin in M. capsulatus (Bath) is a monomer with molecular mass 14.8 kDa, in contrast to hemerythrins from other eukaryotic organisms, where they typically exist as a tetramer or higher oligomers. (c) 2008 Elsevier Inc. All rights reserved.

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We have investigated the effect of weakly coupled hot plasmas on the dipole polarizabilities of positronium negative ion and hydrogen negative ion. The plasma effect is taken care of by employing a screened Coulomb (Yukawa) potential of Debye type, and highly correlated exponential wave functions are used. Dipole polarizabilities for various screening parameters are reported.

The Van der Waals two-body dispersion coefficients for interactions between the positronium (Ps) atom and light atoms have been investigated using highly correlated exponential basis functions in the framework of both pure Coulomb and screened Coulomb potentials. The C6, \{C8\} and \{C10\} coefficients for Ps–Ps and Ps–H interactions, and the \{C6\} coefficients for Ps–He interactions for both the screened and unscreened cases, are reported.