Composition assessment of ferric oxide by accurate peak fitting of the Fe 2p photoemission spectrum

A quantitative study of the surface composition of ferric oxide employing photoemission spectra is presented. It was possible to accurately reproduce the expected composition (Fe_2.00±0.05O₃) by modeling the background as a combination of Shirley‐type (Shirley–Vegh–Salvi–Castle) and slope backgrounds through the active approach. The line‐shape employed to fit apparent peak asymmetries was the double‐Lorentzian. It was possible to resolve a previously unreported satellite located at ~729 eV. Copyright © 2016 John Wiley & Sons, Ltd.     

Metastable flow in capillary tubes: An experimental evaluation

This work presents the results of an experimental study with pure refrigerants R-134a and R-600a and refrigerant–oil mixtures flowing through capillary tubes in order to analyse the metastable flow. A large number of experiments were carried out to verify the influence of several variables on the underpressure of vaporization, mainly the inlet subcooling, internal diameter and inlet pressure. Capillary tubes with internal diameter of 0.69 mm and 0.82 mm were tested for condensation temperatures between 40 °C and 50 °C and subcooling degrees between 3 °C and 12 °C. Measurements for oil concentrations of 1% and 3% were conducted and compared with those for pure refrigerant R-134a. The oil influence on the metastable flow was tested and the effect on the underpressure of vaporization is addressed for lower oil concentrations.     

Synthesis and optical nondestructive evaluation of GaN nanorods on silicon surfaces with gold catalyst

Nanometric gallium-nitride rods were grown on a silicon (1 1 1) substrate through a chemical vapor deposition process with gold particles as the catalyst. Randomly distributed gallium-nitride rods of 20–200 nm in diameter and of various densities and lengths were formed under different deposition conditions. Characterization analyses, such as scanning electron microscopy and optical reflection spectroscopy, have been carried out on samples containing gallium-nitride rods different in size, shape, length and density. While the scanning electron microscopy shows directly the images of the sample surfaces, the optical spectroscopy provides a nondestructive evaluation of the sample surfaces, especially helpful for checking the uniformity of the samples.     

Highly efficient quenching of nanoparticles for the detection of electron‐deficient nitroaromatics

Reported herein is the highly efficient quenching of fluorescent organic nanoparticles by 2,4‐dinitrotoluene and 2,4,6‐trinitrotoluene. These fluorescent nanoparticles are formed from the hydrophobic collapse of fluorescent polymer chains and display quenching efficiencies that are in line with the highest reported literature values. Moreover, the fluorescent quenching occurs only for the fluorescent nanoparticles, and not for the precursor polymer solutions, which display marked insensitivity to the presence of nitroaromatics. This aggregation‐dependent fluorescent quenching has numerous applications for the detection of small‐molecule electron‐deficient analytes. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4150–4155     

Discontinuous Galerkin methods for the Navier–Stokes equations using solenoidal approximations

An interior penalty method and a compact discontinuous Galerkin method are proposed and compared for the solution of the steady incompressible Navier–Stokes equations. Both compact formulations can be easily applied using high‐order piecewise divergence‐free approximations, leading to two uncoupled problems: one associated with velocity and hybrid pressure, and the other one only concerned with the computation of pressures in the elements interior. Numerical examples compare the efficiency and the accuracy of both proposed methods. Copyright © 2009 John Wiley & Sons, Ltd.     

Photoluminescent energy transfer from poly(phenyleneethynylene)s to near‐infrared emitting fluorophores

Photoluminescent energy transfer was investigated in conjugated polymer‐fluorophore blended thin films. A pentiptycene‐containing poly(phenyleneethynylene) was used as the energy donor, and 13 fluorophores were used as energy acceptors. The efficiency of energy transfer was measured by monitoring both the quenching of the polymer emission and the enhancement of the fluorophore emission. Near‐infrared emitting squaraines and terrylenes were identified as excellent energy acceptors. These results, where a new fluorescent signal occurs in the near‐infrared region on a completely dark background, offer substantial possibilities for designing highly sensitive turn‐on sensors. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3382–3391, 2010     

Elastic scattering of neutrons on natPb at forward angles

Angular distributions were measured for neutron elastically scattered by ^natPb at 2.9, 3.0, 3.1, 3.2 and 3.4MeV at very forward angles. The mono-energetic neutron flux was produced at the tandem accelerator facility of the National Institute of Nuclear Research (ININ), Mexico, using the Associated Particle Technique (APT) in the D(d, n)³He reaction. Optical model predictions with best potential systematic show a fairly good agreement with our data, and also the need for a better understanding of the neutron scattering process at very small angles from the theoretical point of view.