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Context.The quest for hot dust in the central region of debris disks requires high resolution and high dynamic range imaging. Near-infrared interferometry is a powerful means to directly detect faint emission from hot grains. more...

We present the results of long-baseline interferometric observations of the classical Cepheids Polaris and δCep in the near infrared K'band (1.9-2.3 μm), using the FLUOR instrument of the CHARA Array. Following our previous detection of a circumstellar envelope (CSE) around $\ell$Car (Kervella et al. 2006), we report similar detections around Polaris and δCep. Owing to the large data set acquired on Polaris, in both the first and second lobes of visibility function, we have detected the presence of a circum-stellar envelope (CSE), located at $2.4\pm0.1$stellar radii, accounting for $1.5\pm0.4$% of the stellar flux in the Kband. A similar model is applied to the δCep data, which shows improved agreement compared to a model without CSE. Finally, we find that the bias in estimating the angular diameter of δCep in the framework of the Baade-Wesselink method (Mérand et al 2005b) is of the order of $1\%$or less in the Kband. A complete study of the influence of the CSE is proposed in this context, showing that at the optimum baseline for angular diameter variation detection, the bias is of the order of the formal precision in the determination of the δCep pulsation amplitude ($1.6\%$). more...

Context.Only a handful of debris disks have been imaged up to now. Due to the need for high dynamic range and high angular resolution, very little is known about the inner planetary region, where small amounts of warm dust are expected to be found. more...

Cepheids play a key role in astronomy as standard candles for measuring intergalactic distances. Their distance is usually inferred from the period–luminosity relationship, calibrated using the semi-empirical Baade-Wesselink method. Using this method, the distance is known to a multiplicative factor, called the projection factor. Presently, this factor is computed using numerical models – it has hitherto never been measured directly. Based on our new interferometric measurements obtained with the CHARA Array and the already published parallax, we present a geometrical measurement of the projection factor of a Cepheid, δCep. The value we determined, $p=1.27$±0.06, confirms the generally adopted value of $p=1.36$within 1.5 sigmas. Our value is in line with recent theoretical predictions of Nardetto et al. (2004, A&A, 428, 131). more...

Aluminum films were deposited on poly(tetrafluoroethylene) and poly(chlorotrifluoroethylene) substrates pretreated with TiCl4 vapor at ambient temperature for 1 h and exposed to dimethylethylamine alane vapor for 8−72 h also at ambient temperature. The films were adherent, conducting, and polycrystalline with no preferred orientation. Scanning electron micrographs showed the surfaces to be rough and porous. X-ray photoelectron spectra contained evidence of oxidized and metallic Al, as well as F, O, C, and Cl. more...

A homologous series of carboxylic acid monolayers was deposited on glass and steel surfaces by the Langmuir-Blodgett technique, and the resulting films were characterized by infrared reflection-absorption spectroscopy, X-ray photoelectron spectroscopy, and contact angle measurements. The friction and durabilities of the well-ordered, close-packed monolayer films on both substrates were evaluated using a reciprocating sliding apparatus, and the results were related to carboxylic acid chain length and monolayer film density. For even-numbered, straight chain carboxylic acids with 12-26 carbon atoms, the friction was found to be independent of the acid chain length and the surface density of the monolayer, but the durabilities increased with each. Durabilities on glass were two orders of magnitude greater than those on steel. more...

Our earlier studies centered on understanding the incipient failure mechanism in polyethylene (PE) as an insulation material. The results simulated conditions not measured in routine manufacturing or electric utility test procedures. These findings indicated that detectable changes with pure PE can occur on the surface of cavities (artificially produced), as observed by X-ray photoelectron spectroscopy (XPS). Because the prior studies were done with pure PE and cavities that were made for easy XPS analysis, the question remained "would the findings from the earlier inquiry be relevant to materials used by the electrical utilities?" To answer this question PE insulation was analyzed from a series of commercial type cables that had undergone long-term testing. Occasionally oxygen was found by XPS on the interior surfaces of the more highly stressed PE cable samples. The estimated amount of oxygen was lower than that often found previously. The oxygenated carbon species were similar to those found previously, i.e., alcohols and/or ethers and carbonyls. Some outgassing, probably hydrocarbons, of the FE was observed. The role, if any, of these outgassing components on the failure of PE as an insulation material is unclear. more...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. more...