Electron Energy-Loss Spectroscopy Study of the Change in the Free-Electron Density in Thin Superconducting NbN Films under Ion-Beam Irradiation

The change in the free-electron density in ultrathin (5 nm) superconducting NbN films in the initial state and after irradiation by O⁺ ions to doses of (0.1–0.9) × 10¹⁷ cm^–2 has been studied by electron energy-loss spectroscopy (EELS). The analysis has been performed on cross section samples prepared by the focused ion beam method, using plasmon oscillations with energies up to 50 eV. The radiation-induced replacement of nitrogen atoms with oxygen atoms in niobium nitride is found to change the electrical properties of the material, which leads to a decrease in the free-electron density with an increase in the irradiation dose.     

New advancements in SERS dye detection using interfaced SEM and Raman spectromicroscopy (μRS)

In the past decade Surface Enhanced Raman Scattering (SERS) has emerged as a powerful technique for the analysis of artistic, historical and archaeological material culture. However, the identification of organic compounds in complex samples using SERS can be challenging owing to the complexity in optimizing the adsorption of target analytes onto the plasmonic substrate and the difficulty to identify proper areas on the sample for robust SERS analysis using optical systems. Scanning electron microscopy (SEM) interfaced with Raman spectromicroscopy (μRS) provides an ideal hyphenated system to overcome the last challenge by: (1) evaluating the nanoparticles coverage/distribution on the sample and (2) locating suitable areas for successful and reproducible SERS analysis. In this paper we demonstrate the potential of a system interfacing SEM and μRS for single fiber, extractionless analysis in the characterization of dyes from reference collections and archaeological textiles. Copyright © 2015 John Wiley & Sons, Ltd.     

“On water” ultrasound-assisted one pot efficient synthesis of functionalized 2-oxo-benzo[1,4]oxazines: First application to the synthesis of anticancer indole alkaloid,Cephalandole A

For the first time, an efficient, simple, synthetic green protocol for the one-pot synthesis of functionalized 2-oxo-benzo[1,4]oxazines 24–29 in water under ultrasound irradiation is presented. As compared to conventional methods, the present protocol avoids traditional chromatography and purification steps and furnished the target molecules in excellent yields (upto 98%) with no side products. The methodology was also demonstrated on gram scale synthesis. Moreover, functionalized 2-oxo-quinoxaline analogues 31–33, another class of bio-active heterocyclic scaffolds, were also prepared using this method. For the first time, this protocol was successfully applied in the synthesis of the anticancer indole alkaloid, Cephalandole A 35.     

Structure and phase composition of thin a-C:H films modified by Ag and Ti

The structure and phase composition of thin a-C:H and a-C:H〈M〉 films (M = Ag, Ti, or Ag + Ti) have been studied by Raman and X-ray photoelectron spectroscopy. The a-C:H〈M〉 films were prepared by ion-plasma magnetron sputtering of a combined target of graphite and metal in an Ar–CH₄ gas mixture. The Raman spectra of these films indicate that their structure is amorphous. The a-C:H〈Ag + Ti〉 films have a more graphitized structure in comparison with pure a-C:H films and films containing only one metal. It is established that carbon in the a-C:H〈Ag + Ti〉 films is in the sp ², sp ³, and C=O states, which are characteristic of the a-C:H, a-C:H〈Ag〉, and a-C:H〈Ti〉 films. In addition, there are also ether (–C–O–C–) or epoxy (?C?O–) carbon groups in the a-C:H〈Ag + Ti〉 films. It has been revealed that silver atoms in the a-C:H〈Ag〉 and a-C:H〈Ag + Ti〉 films form no chemical bonds with carbon, oxygen, and titanium. Titanium in the a-C:H〈Ti〉 and a-C:H〈Ag + Ti〉 films exists in the form of titanium IV oxide (TiO₂).     

Heterocyclization of o-(arylethynyl)arylhydrazines as a new procedure for the synthesis of substituted 1H- and 2H-indazoles and indoles

Procedures for the preparation of 3-substituted 1H- and 2H-indazoles and 2-substituted indoles were developed based on cross-coupling of o-iodoarylhydrazines with copper acetylenides in pyridine or dimethylformamide. An alternative procedure for the synthesis of 3-substituted 1H-indazoles involves cyclocondensation of (2-chloroaryl)acetylenes with hydrazine hydrate in butanol.     

Phase equilibria modeling by the quasilattice equation of state for binary and ternary systems composed of carbon dioxide, water and some organic components

The hole lattice quasichemical group-contribution model (HM) has been applied to described liquid-liquid, liquid-liquid-vapour and vapour-liquid equilibria at elevated and high pressures in binary and ternary mixtures containing CO₂, water, alkanols, paraffinic and aromatic hydrocarbons. An estimation of the concentration of alkanol monomers in the binaries with CO₂ has been performed. The results of modeling by the HM EOS and the Associated Perturbed Anisotropic Chain Theory (APACT) are compared. In most cases both EOS give satisfactory agreement with experimental data.     

Interfacial friction and mass transfer at gas flow into vacuum through a nozzle with a near-wall liquid film

The cycle of experiments on interaction between the co-current gas flow and the near-wall liquid film were carried out at high gas flow velocities, including the supersonic ones. The local parameters of the near-wall film were measured by the capacitance probes. It is shown that the co-current gas flow affects the near-wall film significantly, causing intensive wave formation, droplet detachment from the film surface, and their entrainment by the gas flow. It is determined that a relative amount of liquid entrained by the co-current flow is generalized by the Weber number of this gas flow.     

Imitational modeling of residual stresses in materials employed for the repair of structural steels

Results of the calculations of residual stresses of composites based on polymer binder and glass fiber, which are used in the repair of metal structures of machines, by imitational modeling have been considered. Imitational modeling has been carried out using a special program that enables one to calculate required parameters with a very high rate after choosing initial data from preformed number sets. It has been determined that the modulus of glass plastics has the most sizeable effect on residual stresses.