Ignition enhancement by addition of NO and NO2 from a N2/O2 plasma torch in a supersonic flow

The effects of NO and NO₂ produced by using a plasma jet (PJ) of a N₂/O₂ mixture on ignition of hydrogen, methane, and ethylene in a supersonic airflow were experimentally and numerically investigated. Numerical analysis of ignition delay time showed that the addition of a small amount of NO or NO₂ drastically reduced ignition delay times of hydrogen and hydrocarbon fuels at a relatively low initial temperature. In particular, NO and NO₂ were more effective than O radicals for ignition of a CH₄/air mixture at 1200 K or lower. These ignition enhancement effects were examined by including the low temperature chemistry. Ignition tests by a N₂/O₂ PJ in a supersonic flow (M = 1.7) for using hydrogen, methane, and ethylene injected downstream of the PJ were conducted. The results showed that the ignitability of the N₂/O₂ PJ is affected by the composition of the feedstock and that pure O₂ is not the optimum condition for downstream fuel injection. This result of ignition tests with downstream fuel injection demonstrated a significant difference in ignition characteristics of the PJ from the ignition tests with upstream fuel injection.     

Preparation of co‐polymethyl(alkoxy)siloxanes by acid‐catalyzed controlled hydrolytic copolycondensation of methyl(trialkoxy)silane and tetraalkoxysilane

Polymethyl(alkoxy)siloxane copolymers, poly(MTES‐co‐TEOS), and poly(MTMS‐co‐TMOS), are prepared by acid‐catalyzed controlled hydrolytic co‐polycondensation of methyl(trialkoxy)silane MeSi(OR)₃ (R = Et (MTES) and Me (MTMS)) and tetra‐alkoxysilane Si(OR)₄ (R = Et (TEOS) and Me (TMOS)), respectively. The products are purified by fractional precipitation to provide polymethyl(alkoxy)siloxane copolymers with molecular weight 1000–10,000 (poly(MTES‐co‐TEOS)) or 1700–100,000 (poly(MTMS‐co‐TMOS)) that are stable to self‐condensation. These polymers are soluble in common organic solvents except for hexane, and form flexible and transparent free‐standing films with a tensile strength of 4.0–10.0 MPa. The structure of the polymethyl(alkoxy)siloxane copolymers is thought to be a random or a block co‐polymer. They are found to provide coating films with an adhesive strength up to 10, a refractive index of 1.36–1.40, and a dielectric constant of 3.5–3.6. The products also show better weathering stability than polyethoxysiloxane due to the hydrolytic polycondensation of TEOS. Field emission‐scanning electron micrography analysis reveals that coating films are composed of a micro‐phase separated structure. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4732–4741     

Synthesis of a Hematoside Analog Containing Phytosphingosine and α-Hydroxyfatty Acid

Abstract

The hematoside analog 1 [NeuGcα(2→3)Galβ(1→4)Glcβ(1→1)Cer], which contains a phytosphingosine as a sphingoid base and an α-hydroxyfatty acid, has been synthesized. Coupling of the methyl (methyl 5-benzyloxyacetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero-α- and -β-D-galacto-2-nonulopyranosid)onate 5, prepared from the corresponding 5-acetamido derivative 2, with a lactose derivative 6 afforded sialolactoside 7, which was converted to the corresponding trichloroacetimidate 10. Glycosylation of 10 with the ceramide tribenzoate 12 gave the protected hematoside analog 13, which was deprotected to the hematoside analog 1.     

Photoconductive properties of titanium dioxide film modified by femtosecond laser irradiation

Titanium dioxide (TiO₂) films were irradiated with a femtosecond laser to alter their photoconductive properties. The laser wavelength and pulse duration were 775 nm and 150 fs, respectively. The TiO₂ films irradiated with the femtosecond laser were darkened without changing the topography of the TiO₂ film surface. The electrical resistances of the films as a function of time were measured under visible-light illumination. The transient electrical resistances decreased as time was increased after turning on the light. There were two stages in the reduction process of the electrical resistance.     

The Euler multiplicity and addition-deletion theorems for multiarrangements

The addition–deletion theorems for hyperplane arrangements,which were originally shown by Terao [J. Fac. Sci. Univ. TokyoSect. IA Math. 27 (1980) 293–320.], provide useful waysto construct examples of free arrangements. In this article,we prove addition–deletion theorems for multiarrangements.A key to the generalization is the definition of a new multiplicity,called the Euler multiplicity, of a restricted multiarrangement.We compute the Euler multiplicities in many cases. Then we applythe addition–deletion theorems to various arrangements,including supersolvable arrangements and the Coxeter arrangementof type A₃, to construct free and non-free multiarrangements.     

Quantitative Bestimmungen

Ohne Zusammenfassung     

Dynamical decay of nuclei at high temperature: Competition between particle emission and fission decay

A generalized diffusion equation is propounded to follow the time evolution of an excited nucleus towards fission including along the particle decay. This theoretical model is built in order to try to analyse the anomalous behaviour of particle emission observed in many experimental data for heavy-ion induced reactions. Some calculations for the systems¹⁹⁴Hg,¹⁷⁰Yb and²⁴⁸Cf are presented. A possible extension of this generalized formalism is suggested to deal more consistently with the experimental data.     

Preparation of indium sulfide thin films by spray pyrolysis using a new precursor indium nitrate

Indium nitrate and thiourea were used as the precursor solutions for preparing indium sulfide thin films using Chemical Spray Pyrolysis (CSP) technique. Films having various In/S ratios were characterized using X-Ray Diffraction (XRD), Energy Dispersive X-ray Analysis (EDX), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), optical absorption, transmission and photosensitivity measurements. Sample having In/S ratio 2/3 showed better crystallinity with band gap 2.66 eV. Depth profile of the sample also indicated the formation of indium sulfide. It was also observed that In/S ratio in the initial precursor solution determined the composition as well as electrical properties of the films. Maximum photosensitivity was observed for the sample prepared using solution having In/S ratio 2/4.