This work is about Maya Blue (MB), a pigment developed byMesoamerican civilizations between the 5th and 16th centuries from an aluminosilicate mineral (palygorskite) and an organic dye (indigo). Two different supramolecular quantum-mechanical models afford explanations for the unusual stability of MB based on the oxidation of the indigo molecule during the heating process and its interaction with palygorskite. A model considering indigo derivatives attached to several aluminates shows the principal features of the experimental visible spectrum of MB within the TD-DFT methodology. Another model of an indigo oxidized species confined within an inorganic supramolecular cavity system, that involves about 170 atoms, was calculated after a large configuration interaction of single excited determinants within the NDOL approximation (Montero-Cabrera et al., J Chem Phys, 2007, 127, 145102). It allows a correct reproduction and interpretation of the corresponding spectrum. This second methodology provides the most satisfactory results, being able to manage very big molecular systems at a QM level. Structural explanation for the unusual stability of MB is also provided.

La complejidad de factores que definen y relacionan la calidad del servicio y la satisfaccin del consumidor ha servido de base para el desarrollo de modelos multidimensionales que permiten evaluar esta relacin. Este artculo muestra los fundamentos bsicos de los dos principales modelos de medicin de la calidad del servicio, as mismo se plantea una discusin crtica en torno a los mismos, lo que sirve de marco para la futura propuesta de constructos tericos que sirvan base para desarrollar y fortalecer el conocimiento en el tema. DOI: 10.5585/remark.v10i2.2212

Intensive aquaculture is increasing worldwide and to know in real time the parameters of water quality that affect the growth and development of fish is essential, since the operators of aquatic farms require reliable information and timely environmental variables to plan and adjust the necessary controls and avoid economic losses. In general, the technology currently used is expensive and dependent on many TIC platforms; so it is necessary to know how to develop equipment with high benefits, simple to implement and low cost. An alternative to solve this problem is the IoT as it is increasingly common in all areas, thanks to the penetration of the Internet and WiFi platforms facilitate and lower the implementation of TIC solutions. This article proposes the development of a remote water quality monitoring system for aquaculture based on IoT. Built from the low cost NodeMCU embedded development kit, and operating in low power consumption mode, capable of taking, backing up in a micro-SD memory and transmitting via Wi-Fi (802.11 b / g / n.) to a station of supervision and monitoring the measurements of: pH, Dissolved Oxygen (DO), Water temperature, Water level, Solar radiation, Relative humidity and Air temperature. The system was tested in an aquaculture farm producing of cachamas (Colossoma macropomum) and tilapia (Oreochromis niloticus). The data was contrasted with standardized laboratory measurement methods resulting in a robust, reliable and simple to implement system at a low cost.

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