Glucose Uptake by \u3ci\u3eListeria monocytogenes\u3c/i\u3e Scott A and Inhibition by Pediocin JD

Glucose uptake by Listeria monocytogenes Scott A was inhibited by the bacteriocin pediocin JD and by the protonophore carbonyl cyanide m-chlorophenyhydrazone. Experiments with monensin, nigericin, chlorhexidine diacetate, dinitrophenol, and gramicidin, however, showed that glucose uptake could occur in the absence of a proton motive force. L. monocytogenes cell extracts phosphorylated glucose when phosphoenolpyruvate (PEP) was present in the assay mixture, and whole cells incubated with 2-deoxyglucose accumulated 2-deoxyglucose-6-phosphate, indicating the presence of a PEP-dependent phosphotransferase system in this organism. Glucose phosphorylation also occurred when ATP was present, suggesting that a proton motive force-mediated glucose transport system may also be present. We conclude that L. monocytogenes Scott A accumulates glucose by phosphotransferase and proton motive force-mediated systems, both of which are sensitive to pediocin JD

Completely random nanoporous Cu4O3-CuO-C composite thin films for potential application as multiple channel photonic band gap based filter in the telecommunication wavelengths

In 2003, Babin et al. theoretically predicted (J. Appl. Phys. 94:4244, 2003) that fabrication of organic-inorganic hybrid materials would probably be required to implement structures with multiple photonic band gaps. In tune with their prediction, we report synthesis of such an inorganic-organic nanocomposite, comprising Cu4O3-CuO-C thin films that experimentally exhibit the highest (of any known material) number (as many as eleven) of photonic band gaps in the near infrared. On contrary to the report by Wang et al. (Appl. Phys. Lett. 84:1629, 2004) that photonic crystals with multiple stop gaps require highly correlated structural arrangement such as multilayers of variable thicknesses, we demonstrate experimental realization of multiple stop gaps in completely randomized structures comprising inorganic oxide nanocrystals (Cu4O3 and CuO) randomly embedded in a randomly porous carbonaceous matrix. We report one step synthesis of such nanostructured films through the metalorganic chemical vapor deposition technique using a single source metalorganic precursor, Cu-4(deaH)(dea)(oAc)(5) a <...aEuro parts per thousand(CH3)(2)CO. The films displaying multiple (4/9/11) photonic band gaps with equal transmission losses in the infrared are promising materials to find applications as multiple channel photonic band gap based filter for WDM technology

Assembly of sol-gel-grown Li(x)CoO2Li _{(x)} CoO_{2} nanocrystals through electromagnetic irradiation

We report the fabrication of assembled nanostructures from the pre-synthesized nanocrystals building blocks through optical means of exciton formation and dissociation. We demonstrate that Li (x) CoO2 nanocrystals assemble to an acicular architecture, upon prolonged exposure to ultraviolet-visible radiation emitted from a 125 W mercury vapor lamp, through intermediate excitation of excitons. The results obtained in the present study clearly show how nanocrystals of various materials with band gaps appropriate for excitations of excitons at given optical wavelengths can be assembled to unusual nanoarchitectures through illumination with incoherent light sources. The disappearance of exciton bands due to Li (x) CoO2 phase in the optical spectrum of the irradiated film comprising acicular structure is consistent with the proposed mechanism of exciton dissociation in the observed light-induced assembly process. The assembly process occurs through attractive Coulomb interactions between charged dots created upon exciton dissociation. Our work presents a new type of nanocrystal assembly process that is driven by light and exciton directed

Surface characterization of a low dielectric constant polymer-SiLK* polymer, and investigation of its interface with Cu

The integration of copper and new low dielectric constant materials is a fundamental challenge to be met for further miniaturization of high speed integrated circuits. In this preliminary work, core level x-ray photoelectron spectroscopy (XPS) has been used for the first characterization of the surface composition of Dow Chemical's SiLK* semiconductor dielectric (*trademark of the Dow Chemical Company), its behavior during annealing in vacuo, and its interface formation with thermally evaporated copper in situ. The fully conjugated SiLK* resin shows a C is spectrum with intense shake-up structures, quite similar to those of polystyrene; a small amount of oxygen is detected. Upon annealing in ultrahigh vacuum (7.10(-9) Pa) no significant outgassing is observed; no noticeable change in intensity, width, position of the C 1 s and O 1 s core level peaks or satellite structures is measured. After annealing, the interface formation between SiLK* dielectric and copper has been characterized as a function of incremental coverages from 0.5 to 10 Angstrom of Cu. While the XPS C is spectrum shows only a normal intensity decrease, the Cu 2p(3/2) levels shift from a high binding energy to a purely metallic value: this is interpreted as the formation of small Cu clusters, evolving to a more continuous layer for higher Cu coverage. Annealing in vacuo of the as-prepared Cu(10 Angstrom)-SiLK* interface at 400 degrees C for 1 h does induce an increase of the carbon signal, attributed to further coalescence of copper in metallic clusters. (C) 1999 American Vacuum Society. [S0734-211X(99)05205-1]