Velocity,temperature and conversion profiles in fixed bed catalytic reactors

Velocity and temperature profiles perpendicular to the flow direction were measured at the exit of a packed bed. The form of the profiles differed from that usually accepted in the literature. The temperature profiles showed two humps. They were simulated by means of a two-dimensional heat transfer model containing the local void fraction and velocity. The simulation of a reactor for a strongly exothermic process based upon a model accounting for radial void, velocity and temperature profiles is compared with the predictions based upon a less refined model which does not consider the effect of radial void and velocity profiles.     

Protecting biodegradable coatings releasing antimicrobial agents

This article describes the synthesis and in vitro analysis of poly(ester anhydride) antimicrobial protection coatings. Poly(ester anhydride)s composed of ricinoleic acid, sebacic acid, terephthalic acid, and isophthalic acid were used in this study. The polymers were compatible with various fillers commonly used in paint preparation. The in vitro experiments showed that the polymers are able to release diuron, an antimicrobial agent, for months. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Carbon activity measurement using a solid state potentiometric cell: Application to boron carbides

The interface between -alumina and carbonaceous materials has been studied from both thermodynamic and electrochemical viewpoints. Based on the results, a solid electrolyte potentiometric cell has been devised and the conditions enabling carbon activity to be measured have been determined. In spite of the chemical inertness of the materials involved, the measurements must be performed at low temperature (T<720 K). Carbon activity measurements in the boron-carbon system are presented.     

Flow profile measurement in microchannel using the optical feedback interferometry sensing technique

The need to accurately measure flow profiles in microfluidic channels is well recognised. In this work, we present a new optical feedback interferometry (OFI) flow sensor that accurately measures local velocity in fluids and enables reconstruction of a velocity profile inside a microchannel. OFI is a self-aligned interferometric technique that uses the laser as both the transmitter and the receiver thus offering high sensitivity, fast response, and a simple and compact optical design. The system described here is based on a commercial semiconductor laser and has been designed to achieve a micrometer-range spatial resolution. The sensor performance was validated by reconstructing the velocity profile inside a circular cross-section flow-channel with 320  $\upmu $ m internal diameter, with a relative error smaller than 1.8 %. The local flow velocity is directly measured, thus avoiding the need for model based profile calculation and uncertainties inherent to this approach. The system was validated by successfully extracting the flow profiles in both Newtonian and shear-thinning liquids.     

Stereoisomers composition of 4-[(1′-methylpropyl)-oxycarbonyl]-2-oxetanone and related compounds,as precursors of fuctional polyesters,determined by chiral gas chromatography

Summary The configurational analysis of racemic and optically active stereoisomers of 4-[(1-methylpropyl)oxycarbonyl]-2-oxetanone has been carried out by using chiral gas chromatography. This technique has been successful in the stereoisomers composition determination of these -substituted -lactones prepared by two different routes and used as monomers in the preparation of malic acid stereocopolymers. Result are in good agreement with those obtained from high resolution ¹H NMR, in the presence of an Europium salt, as chiral shift reagent. This method has been extended to 3-methyl-4-[(1,2,2-trimethyl propyl)oxycarbonyl]-2-oxetanone. The exact knowledge of precursors configurational structure is very important in regard to the obtention of the corresponding polystereoisomers with a strictly controlled enantiomeric or diastereoisomeric composition and consequently with predictable properties.     

Evaluation of in-air hand gestures interaction for older people

Universal Access in the Information Society - In-air gestural interfaces are gaining popularity due to the increasing availability and low cost of gesture recognition hardware. However, the current...