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Throughout this investigation, experiments on laser ablation with silicon (Si) wafers have been performed using silicon nitride (Si 3 N 4 ) as a sacrificial layer to find the optimal fluence capable of removing the Si 3 N 4 , which allows the subsequent anisotropic etching in Si with potassium hydroxide. As a result, an alternative to the traditional micromachining techniques that require more steps and processing times has been introduced. The effect of the pulse numbers on Si wafers has been studied and it has been observed that when increasing the pulse numbers at the same fluence, the capacity of the pyramidal cavity formed was greater than using only one pulse at higher fluences. Microcavities were performed with a floating Si 3 N 4 layer. This happens to be very useful for the development of drug delivery systems and the manufacture of microarrays. Microcavities were also used as masters for the fabrication of microionizers in polydimethyl siloxane (PDMS).

Propulsion pellets of different metal/salt (Zn/CaCO 3 ) composition have been prepared. The impulse imparted to the pellet by the laser has been measured using two different methods: a torsion pendulum and a piezoelectric sensor. The dependence of the coupling coefficient, C m , on the composition of the solid binary propellants in ablative laser propulsion has been investigated under different experimental conditions: in vacuum and at atmospheric pressure as well as with two different wavelengths, IR and UV. The composition of the Zn/CaCO 3 propellant mixture that optimizes the coupling coefficient, C m , has been determined.

In this article a method to increase the capability of an electronic nose to discriminate between a priori similar odours is presented. Olive oil is analyzed because it is well known that the characteristics of its aroma impair in many cases the discrimination between different kinds of olive oils especially when they are from similar geographic regions. In the present work the improvement of the electronic nose performance for the above-mentioned discrimination by a non-destructive method of IR laser vaporization of the sample is studied. Laser vaporization has also been performed at two different IR wavelengths to analyze the effect of laser radiation absorption of the sample on the electronic nose selectivity.

The Riachuelo–Matanza basin area (2.240 km 2 ) is located in Buenos Aires province, Argentina. This area is affected by intensive and extensive agricultural activities, and bears almost 3,000,000 inhabitants and more than 10,000 industries, that release their effluents to the main collector of the basin, the Riachuelo River. It is a highly polluted area and the quality of water, soil and air is severely impaired causing chronic health problems. As part of an interdisciplinary study undertaken by local institutions to reach an environmental quality diagnosis and analysis of the pollutants dynamics in the basin system we have measured, with an electronic nose, the air immediately above the water in several points at the Riachuelo River mouth where the painteresque La Boca district is located. Water quality parameters simultaneously collected at the same sites were analyzed and correlated with the electronic nose response. This study is only exploratory and focuses on the viability of using an electronic nose to locate conflictive emissions throughout a given zone.

A prototype of an electronic nose (e-nose), based on an array of six undoped and doped SnO2 gas sensors made by the rheotaxial growth and thermal oxidation (RGTO) technique, is applied to the analysis of a basic ingredient of beer, the hop. We address two main requirements from the local brewing industry: to detect departures from the hop’s quality due to aging processes or lousy storage and to obtain a quick discrimination of the various similar types of pellets usually employed. Different methods for the extraction of the features of each sensor response have been studied. A comparison between discrimination obtained with a linear dimensional reduction via principal component analysis and a nonlinear reduction obtained with self-organized maps has also been made. © 2004 Elsevier B.V. All rights reserved.