Twenty-species and 15-species chemical kinetic mechanisms for cyclohexane using the local self-similarity tabulation method

The 1081 species cyclohexane-oxidation elementary reaction mechanism of Silke et al. (DOI: 10.1021/jp067592d ) is reduced in the number of species by a factor using the local self-similarity tabulation (LS2T) method. Reduced-species mechanisms of both 20 (R20) and 15 (R15) species are created in the high-pressure combustion regime typical of diesel engines. To evaluate the performance of R20 and R15 against the elementary kinetics, simulations are performed for cyclohexane/air mixtures at initial temperatures of 1150, 900, 750, and 680 K and constant pressures of 20 and 40 bar for a variety of equivalence ratios (, 1.0, and 2 for 1150 and 900 K; for 750 K; for 680 K). Very good agreement between R20 and R15 with the elementary kinetics mechanism is demonstrated at 1150 and 900 K for which the self-similarity is very well obeyed; however, only fair agreement is obtained at 750 and 680 K, a fact which is traced to the less faithful adherence to the self-similarity due to the one order of magnitude increase in ignition time over the range 750-680 K. These results are found to be quasi-independent of the tabulation grid. Future work is proposed to improve the reduction in the cold-ignition, high-pressure regime.     

Poly(dicyclopentadiene) Submicron Fibers Produced by Electrospinning

Summary: We have used the process of electrospinning to produce fibers of poly(dicyclopentadiene) with diameters on the submicron scale. The material, formed from a monomer‐catalyst solution, polymerized in flight during the electrospinning process. Fibers were collected over trenches etched in silicon and the Young's moduli were measured using an atomic force microscope to measure force‐displacement curves. The resulting values of Young's moduli are larger than typical values for bulk polymer material.

SEM image of suspended PDCPD fiber.     

Reconstruction of cosmic and beam-halo muons with the CMS detector

The powerful muon and tracker systems of the CMS detector together with dedicated reconstruction software allow precise and efficient measurement of muon tracks originating from proton-proton collisions. The standard muon reconstruction algorithms, however, are inadequate to deal with muons that do not originate from collisions. This note discusses the design, implementation, and performance results of a dedicated cosmic muon track reconstruction algorithm, which features pattern recognition optimized for muons that are not coming from the interaction point, i.e., cosmic muons and beam-halo muons. To evaluate the performance of the new algorithm, data taken during Cosmic Challenge phases I and II were studied and compared with simulated cosmic data. In addition, a variety of more general topologies of cosmic muons and beam-halo muons were studied using simulated data to demonstrate some key features of the new algorithm.     

Transparent nano composite PVA–TiO2 and PMMA–TiO2 thin films: Optical and dielectric properties

Transparent nano composite PVA–TiO₂ and PMMA–TiO₂ thin films were prepared by an easy and cost effective dip coating method. Al/PVA–TiO₂/Al and Al/PMMA–TiO₂/Al sandwich structures were prepared to study the dielectric behavior. The presence of metal–oxide (Ti–O) bond in the prepared films was confirmed by Fourier transform infrared spectroscopy. X-ray diffraction pattern indicated that the prepared films were predominantly amorphous in nature. Scanning electron micrographs showed cluster of TiO₂ nanoparticles distributed over the film surface and also there were no cracks and pin holes on the surface. The transmittance of the films was above 80% in the visible region and the optical band gap was estimated to be about 3.77 eV and 3.78 eV respectively for PVA–TiO₂ and PMMA–TiO₂ films by using Tauc's plot. The determined refractive index (n) values were between 1.6 and 2.3. High value of dielectric constant (?′ = 24.6 and ?′ = 26.8) was obtained for the prepared composite films. The conduction in the composite films was found to be due to electrons. The observed amorphous structure, good optical properties and dielectric behavior of the prepared nano composite thin films indicated that these films could be used in opto-electronic devices and in thin film transistors.     

BIS- (N-ACY L-2-THIO-193,2-DIAZAPHOSPHO LINES), NOUVEAUX COMPLEXANTS PHOSPHORÉS D'IONS ALCALINO-TERREUX

Abstract

Nous décrivons la synthèse en quatre étapes de nouveaux 1,3-dihydrobenzodiazaphospholes 3 et 6a-c dont la particularité est de posséder un (3) ou deux (6a-c) motifs N-acyl-diazaphospholines. Seuls les ligands 6a-c présentent des propriétés complexantes vis-à-vis des ions alcalino-terreux. observables par spectrométrie IR et UV.

We describe a four step synthesis of new 1,3-dihydrobenzodiazaphospholes 3 and 6a-c which posses one (3) or two (6a-c) N-acyl diazaphospholine moieties. Only the formation of alkaline-earth cation complexes, with 6a-c has been observed by IR and UV spectroscopies.     

SYNTHESE DE NOUVEAUX MACROCYCLES DERIVES DE LA QUINOXALINE-2 3-DITHIONE SYNTHESIS OF NEW MACROCYCLES FROM QUINOXALINE-2, 3-DITHIONE DERIVATIVE

Abstract

Au cours de ce travail, nous décrivons la synthtse de nouveaux macrocycles renfermant une ou deux unités quinoxaliniques au sein dune chaìne poléthérée et thioétheérée, susceptibles de présenter des propriétés complexantes intéressantes, et dont le principe consiste à faire réagir la quinoxaline-2, 3- dithione avec les dichloropolyéthyléneglycols dans les conditions de la catalyse par transfert de phase     

2,4-Dioxo(dimercapto)-1,5-benzodiazepino-13-couronne-2, Nouveau Macrocycle Complexant de L'ion Ag +

We describe herein the synthesis of new macrocycles 5 et 6 derived from 1,5-benzodiazepine-2,4-dione in a heterogenous media using phase transfer catalysis conditions. A crystallographic study by x-ray of 5 was carried out to confirm the structure suggested; moreover the macrocycle 6 presents chelating properties with respect to the ion Ag + easily observed by IR and UV spectroscopies.     

Search for W' bosons decaying to an electron and a neutrino with the D0 detector

This Letter describes the search for a new heavy charged gauge boson W' decaying into an electron and a neutrino. The data were collected with the D0 detector at the Fermilab Tevatron pp[over] Collider at sqrt[s]=1.96 TeV, and correspond to an integrated luminosity of about 1 fb(-1). Lacking any significant excess in the data in comparison with known processes, an upper limit is set on sigma_(W') x B(W')-->e nu), and a W' boson with mass below 1.00 TeV can be excluded at the 95% C.L., assuming standard-model-like couplings to fermions. This result significantly improves upon previous limits and is the most stringent to date.     

Search for scalar neutrino superpartners in e+mu final states in pp collisions at sqrt[s]=1.96 TeV

We report a search for R-parity-violating production and decay of sneutrino particles in the emu final state with 1.04+/-0.06 fb-1 of data collected with the D0 detector at the Fermilab Tevatron Collider in 2002-2006. Good agreement between the data and the standard model prediction is observed. With no evidence for new physics, we set limits on the R-parity-violating couplings lambda'311 and lambda312 as a function of the sneutrino mass.