José M. Álvarez Gómez

Interfacial and foaming characteristics of protein—lipid systems

Abstract In this work, we studied interfacial properties (surface tension, σ , and critical micelle concentration, CMC), foaming properties (foam strength andfoam stability), and foam microscopical examination of aqueous solutions of Tween 20 and/or bovine serum albumin (BSA) and casein. Temperature, Tween 20 concentration in the aqueous phase, protein—lipid ratio and the aqueous phase composition (water, and NaCl solutions at 0.1 and 0.5 mol/dm 3 ) were the variables studied. The CMC of Tween 20 was determined by surface tension measurements using a Kruss tensiometer (Wilhelmy plate method). The foaming properties (foam strength and stability) were evaluated in an aeration column (bubbling method). Microscopicalfoam observation was performed in a specially designed cell. Tween 20 is able to form micelles in dilute aqueous solutions. The results show that the temperature dependence on CMC depends on the subphase composition, but the σ values do decrease as temperature increases. The CMC and the c values also depend on the solute in the aqueous solutions. The lipid—protein interactions at the interface depend on both the Tween 20 concentration (C) and the solute in bulk phase. In water and aqueous solutions of NaCl, the σ values decrease in the presence of protein at C CMC. Foam properties depend on the protein used, the protein—lipid ratio and the presence of NaCl in the aqueous phase. A direct relationship between foaming characteristics and the CMC of the Tween 20 was observed.

Indoor Position System Based on a Zigbee Network

TAIS group has developed an indoor position system prototype based on a fingerprint positioning algorithm. The prototype uses IEEE 802.15.4 mote and BitCloud Stack, a full-featured ZigBee Compliant, second generation embedded software stack from Atmel. The design requirements of the prototype were only to determine the actual position in a room of a user in a building, so the prototype accuracy is room accuracy. TAIS group decided to compete in the second edition of EvAAL Competition. This paper presents all the step made to adapt the prototype to the EvAAL environment, the found drawbacks and the obtained results. One of the most important drawback was that the Smart House Living Lab of the Polytechnic University of Madrid has only two rooms, the required accuracy was meters (error less than or equal to 0,5 meters the higher score, higher than 4 meters no score) and the room accuracy was substituted by areas of interest so the behavior of our prototype was going to work was an incognita.

Fingerprint indoor location simulator for AAL

In AAL environments, a key issue is to know the location of a user in order to provide the required services quickly and efficiently. A good location system is the one that is able to locate an individual in the shortest time, with acceptable accuracy and spending the least resources as possible. In this context, it seems interesting to analyze in depth the existing location systems in order to optimize both their location procedures and the cost due to deployment. There are many ways to locate an individual indoors. This research is focused on Fingerprint based location procedure, making a comprehensive analysis of it, generating a broad and diverse set of assumptions and issues related to all the elements of the location process based on it. A tool called PosSimulator has been developed to help designers and AAL system evaluators choose the best deployment for a specific environment, taking into account the economic and installation cost and the position accuracy. PosSimulator has been designed regardless the technology used to acquire the information required to locate. It has been used in a test environment. There has been carried out an extensive battery of tests to extract answers or approaches to all the issues raised and research hypotheses, looking for clear trends in the accuracy of the location and observable connections among the various parameters in which the fingerprint based localization process is divided. For the test environment, it has been determined the best combination of all parameters.