7 research outputs found
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 polyÂ(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 (polyÂ(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 TcO<sub>2</sub> with O<sub>2</sub> 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 Tc<sub>2</sub>O<sub>7</sub> crystallizes as a molecular solid in the orthorhombic
space group <i>Pbca</i> [<i>a</i> = 7.312(3) Ã…, <i>b</i> = 5.562(2) Ã…, <i>c</i> = 13.707(5) Ã…,
and <i>V</i> = 557.5(3) Ã…<sup>3</sup>]. The Tc<sub>2</sub>O<sub>7</sub> molecule can be described as corner-sharing
TcO<sub>4</sub> tetrahedron [Tc---Tc = 3.698(1) Å and Tc–O<sub>Bri</sub>–Tc = 180.0°]. The EI-MS spectrum of Tc<sub>2</sub>O<sub>7</sub> consists of both mononuclear and dinuclear species.
The main dinuclear species in the gas-phase are Tc<sub>2</sub>O<sub>7</sub> (100%) and Tc<sub>2</sub>O<sub>5</sub> (56%), while the main
mononuclear species are TcO<sub>3</sub> (33.9%) and TcO<sub>2</sub> (42.8%). The difference in the relative intensities of the M<sub>2</sub>O<sub>5</sub> (M = Tc, Re) fragments (1.7% for Re) indicates
that these group 7 elements exhibit different gas-phase chemistry.
The solid-state structure of Tc<sub>2</sub>O<sub>7</sub> was investigated
by density functional theory methods. The optimized structure of the
Tc<sub>2</sub>O<sub>7</sub> molecule is in good agreement with the
experimental one. Simulations indicate that the more favorable geometry
for the Tc<sub>2</sub>O<sub>7</sub> molecule in the gas-phase is bent
(Tc–O<sub>Bri</sub>–Tc = 156.5°), while a linear
geometry (Tc–O<sub>Bri</sub>–Tc = 180.0°) is favored
in the solid-state