Large single-crystal growth of RBa2Cu3O7−x by the flux method (R=Y and rare earths)

Il Nuovo Cimento D - In this work the thermal conditions required for single-crystal growth in RBa2Cu3O7−x systems (R=Y or rare earths apart from Ce and Tb) have been systematically revised...     

Stoichiometric and oxygen deficient MoO3(010) surfaces

The (010) surface of single crystal MoO₃ has been prepared and examined using LEED, XPS, UPS, and ELS. Three methods yield the stoichiometric surface: scraping in UHV and annealing, ion etching followed by reoxidation (770 K, 10² Pa O₂), or oxygen treatment to remove carbon contamination. LEED shows the surface periodicity is the same as that of the bulk (010). The MoO₃ valence band is 7 eV wide with density of states maxima at 1.5, 3.6, and 5.6 eV below the top of the valence band. Heating MoO₃ in vacuum reduces the surface region. XPS indicates the O/Mo atomic ratio decreases to 2.85 ± 0.12 on heating to 600 K. Ar ion bombardment disorders the surface and reduces the surface O/Mo atomic ratio to 1.6. Annealing of reduced surfaces at > 770 K incompletely reoxidizes them by diffusion of oxygen from the bulk. UPS of reduced and annealed MoO₃ exhibits two new emission features in the bandgap at 0.9 and 2.0 eV above the top of the valence band. These features originate from Mo derived states of a defect involving two or more Mo atoms, such as crystallographic shear planes. Because of the insulating nature of MoO₃, surface charging and electron beam induced damage were substantial hindrances to electron spectroscopic examination.     

The nuclear magnetic resonance of heterocyclic compounds related to anthracene

The NMR spectra of a series of heterocyclic compounds analogous to anthracene have been investigated at 220 and 60 MHz. Correlations have been made with molecular geometry and parameters calculated from semi-empirical MO theory. For planar molecules, the chemical shift of the proton ortho to the heteroatom is linear with respect to the electron density on the heteroatom, but otherwise chemical shifts are independent of electron density. Planarity of the molecules is also a factor in some of the coupling constants.     

Infrared bands of the HCNO molecule

Several vibration rotation bands of the H¹²C¹⁴N¹⁶O molecule have been studied by using high resolution vacuum grating infrared spectrographs. A linear molecular model has been used in establishing the vibrational assignments and evaluating the molecular constants. A value of 224.101 cm^?1 has been determined for the band center of the ν₅ fundamental by application of the Ritz combination principle. Future efforts will be directed to arriving at a similar result for the ν₄ fundamental.     

First track-structure measurements of 20 MeV protons with the STARTRACK apparatus

The STARTRACK experimental set-up, mounted on the +50° beam line of the Tandem-Alpi particle accelerator of Legnaro National Laboratories, has been conceived to give an experimental basis to nanodosimetric calculations. STARTRACK is based on a detection system able to measure ionization cluster distributions in a 20 nm propane site with a resolution of one ionization. The experimental layout has been designed to minimize pile-up distortions. The background noise is filtered by off-line dedicated software. Electron cluster distribution of 20 MeV protons has been measured. Monte Carlo data and experimental data are pretty well consistent.     

A One-Pot Entry to a Novel 3-H-benzo[d]pyrazolo[1,5-b]isothiazole Ring System

Summary The phosphorus ylide obtained from the reaction between 2-aminobenzo[d]isothiazol-3-one and dimethyl acetylenedicarboxylate in the presence of triphenylphosphine undergoes a smooth intramolecular Wittig-type reaction to produce, in a one-pot reaction, 3-H-benzo[d]pyrazolo[1,5-b]isothiazole-2,3a-dicarboxylic acid dimethyl ester, a novel functionalized heterocyclic compound.     

CDS volatility: the key signal of credit quality

This paper investigates the role of CDS volatility in providing information concerning the credit quality of a company. In Castellano and D’Ecclesia (J. Financ. Decis. Mak. 2:27, 2011) a first analysis of how CDS quotes respond to rating announcements is provided and it showed that market participants do not rely much on Rating Agencies, especially during periods characterized by very high volatility, i.e. during a financial crisis. Here, a more accurate analysis of the CDS’s ability to provide timely information on the creditworthiness of reference entities is performed, estimating the volatility of CDS quotes by using Exponential GARCH(1,1) models. The event study methodology is applied to a sample of CDS quotes for US and European markets, over the period 2004–2009. Results provide an accurate understanding of market behavior in the presence of news released by Rating Agencies. Overall, market participants seem to provide timely reactions around the event date and we show that the key element of signaling is represented by the changing volatility in CDS quotes, before and after the rating event.