Superficial Dopants Allow Growth of Silicone Nanofilaments on Hydroxyl-Free Substrates

We report new types of silicone nanostructures by a gas-phase reaction of trichloromethylsilane: 1-D silicone nanofilaments with a raveled end and silicone nanoteeth. Filaments with a raveled end are obtained on poly­(vinyl chloride), which is superficially doped with the detergent Span 20. Silicone nanoteeth grow on sodium chloride using dibutyl phthalate as superficial dopant. Without dopants, no structures are observed. The dopants are identified by mass spectroscopy and the silicone nanostructures are analyzed by infrared spectroscopy and energy-dispersive analysis of X-rays. The growth of silicone nanostructures on a hydrophobic substrate (poly­(vinyl chloride)/Span 20) and a substrate free of hydroxyl groups (sodium chloride/dibutyl phthalate) questions the currently discussed mechanisms for the growth of 1-D silicone nanofilaments, which is discussed. We suggest superficial doping as an alternative pretreatment method to oxidizing activation and prove this principle by the successful coating of copper, which is superficially doped with Span 20

Peptide dry mass predicts a significant proportion of variation in peptide intensity determined by LC-MS.

<p>Overall, there was a significant correlation between peptide dry mass and rank abundance of peptide mass 1064. This relationship differed among treatments indicating a change in the relative abundance of the peptide components of skin secretions depending on microbial treatment. Transplant treated frogs had the highest relative abundance of peptide mass 1064 (lowest rank), and probiotic treated frogs the lowest relative abundance with controls intermediate. Probiotic treated frogs had significantly higher total quantity of peptides than transplant treated frogs (see text).</p

Statistical analysis of treatment differences in microbial communities described by T-RFLP using either Hae3 or Msp1 enzymes.

<p>Analysis of similarity (ANOSIM) and non-parametric multivariate analysis of variance (NPMANOVA) results are shown of the three <i>C. panamansis</i> treatments: P = probiotic treatment, C = control treatment, T = transplant treatment. Significant values identified by ANOSIM and NPMANOVA are indicated in bold.</p

Skin microbial communities of <i>Colostethus panamansis</i>.

<p>Communities before (circles, field samples) and after (crosses, day 48) treatments visualized by non-metric multidimensional scaling (nMDS) of T-RFLP analysis using enzymes HaeIII and MspI. Treatments are numbered to indicate probiotic bacterium <i>Lysinibacillus fusiformis</i> (1,2), control (3,4), and skin-wash transplant from the disease-resistant glass frog <i>Espadarana prosoblepon</i> (5,6). Microbial communities were not significantly different among treatments within each time-point represented by convex hulls. Distance between objects on the plot represents relative dissimilarity (axes are in arbitrary units). Stress <0.1 indicates strong community differences and stress >0.2 indicates that differences should be interpreted with caution. Statistical analyses are presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0087101#pone-0087101-t001" target="_blank">Table 1</a>.</p

Retention time (Rt), molecular weight (MW), prevalence, and mean relative area of each peptide based on HPLC-MS chromatograms.

<p>Area is relative to a consistently observed peak, MW 1064.0 for <i>C. panamansis</i> and MW 2681.2 for <i>E. prosoblepon</i>.</p

Representative chromatograms of skin defense peptides examined by HPLC-MS.

<p>(a) <i>Colostethus panamansis.</i> (b) <i>Espadarana prosoblepon</i>. Values of molecular weight and mean area for the detected peptides are reported in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0087101#pone-0087101-t002" target="_blank">Table 2</a>.</p

Ditechnetium Heptoxide Revisited: Solid-State, Gas-Phase, and Theoretical Studies

Ditechnetium heptoxide was synthesized from the oxidation of TcO₂ with O₂ at 450 °C and characterized by single-crystal X-ray diffraction, electron-impact mass spectrometry (EI-MS), and theoretical methods. Refinement of the structure at 100 K indicates that Tc₂O₇ crystallizes as a molecular solid in the orthorhombic space group <i>Pbca</i> [<i>a</i> = 7.312(3) Å, <i>b</i> = 5.562(2) Å, <i>c</i> = 13.707(5) Å, and <i>V</i> = 557.5(3) ų]. The Tc₂O₇ molecule can be described as corner-sharing TcO₄ tetrahedron [Tc---Tc = 3.698(1) Å and Tc–O_Bri–Tc = 180.0°]. The EI-MS spectrum of Tc₂O₇ consists of both mononuclear and dinuclear species. The main dinuclear species in the gas-phase are Tc₂O₇ (100%) and Tc₂O₅ (56%), while the main mononuclear species are TcO₃ (33.9%) and TcO₂ (42.8%). The difference in the relative intensities of the M₂O₅ (M = Tc, Re) fragments (1.7% for Re) indicates that these group 7 elements exhibit different gas-phase chemistry. The solid-state structure of Tc₂O₇ was investigated by density functional theory methods. The optimized structure of the Tc₂O₇ molecule is in good agreement with the experimental one. Simulations indicate that the more favorable geometry for the Tc₂O₇ molecule in the gas-phase is bent (Tc–O_Bri–Tc = 156.5°), while a linear geometry (Tc–O_Bri–Tc = 180.0°) is favored in the solid-state