Satellite lifetime routine user's manual

A FORTRAN coded computer program which determines secular variations in mean orbital elements of earth satellites and the lifetime of the orbit is described. The dynamical model treats a point mass satellite subject to solar and lunar disturbing gravitational fields, second, third and fourth harmonics of the earth's oblate potential, earth's atmospheric drag, and solar radiation pressure. Each of these disturbing functions may be selectively simulated. Data preparation instructions, a sample problem, and definitions of output quantities are included

Determination of band bending at the Si(113) surface from photovoltage-induced core-level shifts

The Si 2p core levels were measured by photoelectron spectroscopy with use of synchrotron radiation for the clean Si(113) 3×2 surface. The core levels exhibit shifts of several hundred meV during the change of sample temperature from 300 to 20 K. We interpret these shifts as due to a release of band bending by saturation surface photovoltage. Together with core-level spectroscopy, this turns out to be a new, highly accurate method in determining Fermi-level pinning. For the clean Si(113) 3×2 surface the pinning position coincides within 25 meV for n- and p-type doped samples. At 20 K, a strong reduction of the Si 2p linewidth is found for the p-type sample, which is only to a lesser degree due to band flattening. An intrinsic linewidth of the Si 2p core level of 205±30 meV is derived

Adatom-induced donor states during the early stages of Schottky-barrier formation: Ga, In, and Pb on Si(113)

We performed angle-resolved ultraviolet and soft-x-ray photoelectron spectroscopy for the early stages of Schottky-barrier formation of Ga, In, and Pb on Si(113) at room temperature. In the coverage region below 0.1 monolayer a band-bending behavior, typical for donor states, is found. The energies of the adatom-induced donor states in the band gap depend on the adatoms. The Schottky barrier reaches its final value at a coverage of about one monolayer. The values are 0.35 eV above the valence-band maximum for In and Ga and 0.425 eV for Pb. Measurements with Xe interlayers were made to verify that these interfaces are not reactive

Band bending in the initial stages of Schottky-barrier formation for gallium on Si(113)

We present angle-resolved ultraviolet and soft-x-ray photoelectron spectroscopy results for the Schottky-barrier formation of Ga on p-type Si(113). For the first 0.08 monolayer of Ga, the band bending increases. For higher coverages, it decreases monotonically until it reaches its final value at about 2 monolayers. This change of band bending is found for a Si surface for the first time and supports a recent model calculation. The final barrier height is 0.32±0.10 eV, in good agreement with the values found for low-index surfaces

Reactivity and structure of CF3I on Ru(001)

A variety of surface-sensitive techniques are used to elucidate the reaction pathways, as well as adsorbate structures, associated with thermal activation of CF3J following adsorption on Ru(001) at 100 K. XPS shows that the C-I bond of CF3I dissociates below 200 K to form CF3(ad) and I(ad); the subsequent reactions of CF2 are best viewed as being regulated by the availability of surface sites. CF3(ad) dissociates to CF2(ad) below 200 K. Further CF3 dissociation, some of which is activated by H(ad), occurs between 200 and 400 K until all available sites are filled. Desorption of the remaining CF3, peaking at 705 K, once again opens surface sites for decomposition. This is followed by recombination of the products to form CF3(g). No evidence for CF(ad) is ever observed. Hydrogen coadsorption studies explain interesting features associated with fluorine evolution. HREELS and ESDIAD results indicate that CF3 adopts a tilted configuration on Ru(001)

Ab-initio calculations of the optical properties of the Si(113)3x2ADI surface

We investigated the stable silicon (113) surface with a 3x2ADI reconstruction by ab-initio methods. The ground state properties have been obtained using the density-functional theory. We present the dispersion of the electronic band structure, where the surface bands have been distinguished from the projected bulk bands by calculating their localization in the slab. The optical spectra, here the reflectance anisotropy (RAS), have been obtained within the independent particle random phase approximation. We identified surface features in the spectra tracing them back to the responsible electronic states and, studied their localization in the slab. A comparison with available experimental data for the band structure and the RAS shows a good agreement.Comment: 10 pages, 10 figure

Broad-spectrum in vitro activity of macrophage infectivity potentiator inhibitors against Gram-negative bacteria and Leishmania major

Background The macrophage infectivity potentiator (Mip) protein, which belongs to the immunophilin superfamily, is a peptidyl-prolyl cis/trans isomerase (PPIase) enzyme. Mip has been shown to be important for virulence in a wide range of pathogenic microorganisms. It has previously been demonstrated that small-molecule compounds designed to target Mip from the Gram-negative bacterium Burkholderia pseudomallei bind at the site of enzymatic activity of the protein, inhibiting the in vitro activity of Mip. Objectives In this study, co-crystallography experiments with recombinant B. pseudomallei Mip (BpMip) protein and Mip inhibitors, biochemical analysis and computational modelling were used to predict the efficacy of lead compounds for broad-spectrum activity against other pathogens. Methods Binding activity of three lead compounds targeting BpMip was verified using surface plasmon resonance spectroscopy. The determination of crystal structures of BpMip in complex with these compounds, together with molecular modelling and in vitro assays, was used to determine whether the compounds have broad-spectrum antimicrobial activity against pathogens. Results Of the three lead small-molecule compounds, two were effective in inhibiting the PPIase activity of Mip proteins from Neisseria meningitidis, Klebsiella pneumoniae and Leishmania major. The compounds also reduced the intracellular burden of these pathogens using in vitro cell infection assays. Conclusions These results indicate that Mip is a novel antivirulence target that can be inhibited using small-molecule compounds that prove to be promising broad-spectrum drug candidates in vitro. Further optimization of compounds is required for in vivo evaluation and future clinical applications

ATG5 is essential for ATG8-dependent autophagy and mitochondrial homeostasis in Leishmania major

Macroautophagy has been shown to be important for the cellular remodelling required for Leishmania differentiation. We now demonstrate that L. major contains a functional ATG12-ATG5 conjugation system, which is required for ATG8-dependent autophagosome formation. Nascent autophagosomes were found commonly associated with the mitochondrion. L. major mutants lacking ATG5 (Δatg5) were viable as promastigotes but were unable to form autophagosomes, had morphological abnormalities including a much reduced flagellum, were less able to differentiate and had greatly reduced virulence to macrophages and mice. Analyses of the lipid metabolome of Δatg5 revealed marked elevation of phosphatidylethanolamines (PE) in comparison to wild type parasites. The Δatg5 mutants also had increased mitochondrial mass but reduced mitochondrial membrane potential and higher levels of reactive oxygen species. These findings indicate that the lack of ATG5 and autophagy leads to perturbation of the phospholipid balance in the mitochondrion, possibly through ablation of membrane use and conjugation of mitochondrial PE to ATG8 for autophagosome biogenesis, resulting in a dysfunctional mitochondrion with impaired oxidative ability and energy generation. The overall result of this is reduced virulence