807 research outputs found
Towards new multivalent supramolecular helical structures based on phthalocyanines for PDT applications
The self-assembly of α-D-glucose octafunctionalized Zn(II) phtalocyanine (ZnPc) in aqueous media has been investigated using different techniques such as UV, CD and diffusion-ordered 1H-NMR spectroscopy (DOSY). The formation of supramolecular columnar helical aggregates with a preferred handedness due to the presence of the sugar moiety has been confirmed by these techniques. Moreover, the stability of the supramolecular polymers formed has been assessed by using pyridine as a zinc ligand, disrupting the aggregates or inducing their formation by dilution of the system.M.G:I. acknowledges the MICINN for his Juan de la Cierva Fellowshi
Building initial models of rotating white dwarfs with SPH
A general procedure to build self-gravitational, rotating equilibrium structures with the Smoothed Particle Hydrodynamics (SPH) technique does not exist. In particular, obtaining
stable rotating configurations for white dwarf (WD) stars is
currently a major drawback of many astrophysical simulations.
Rotating WDs with low internal temperatures are connected with
both, explosive and implosive scenarios such as type Ia supernova
explosions or neutron stars formation. Simulations of these events
with SPH codes demand stable enough particle configurations as
initial models. In this work we have developed and tested a relaxation method to obtain equilibrium configurations of rotating
WDs. This method is straightforward and takes advantage of the
excellent mass and angular momentum conservation properties
of the SPH technique. Although we focus on rigid rotation and
its potential applications to several Type Ia supernova scenarios,
we also show that our proposal is also able to provide good initial
models in differential rotation, which has the potential to benefit
many other types of simulations where rotation plays a capital
role, like disk evolution and stellar formation.Peer ReviewedPostprint (published version
Computer-Aided Design of Active Packaging/Food System for extended shelf life
Common dynamic models of active packaging are focused on the mass transfer of the antimicrobial agents. Nevertheless, the interaction of the antimicrobial agent with the food microorganisms is usually neglected, despite being critical to optimise the food safety and quality. In this work, we propose a dynamic model simulating the dynamics of carvacrol and its inhibition by Listeria monocytogenes in an active packaging system. Carvacrol is an antimicrobial agent allowed as a food additive and Listeria monocy- togenes is the major psychrotrophic pathogen in food. The model can be exploited to study different
aspects of the food quality and safety, such for example the maximum load of Listeria before packaging and the concentration of carvacrol to guarantee food quality and safety standard
Diseño e implementación de una aplicación web para la gestión de información geográfica del departamento de desarrollo forestal de la CONAFOR Estado de México
El presente trabajo tiene como objetivo principal Generar una aplicación Web Mapping, que permita la gestión de información espacial de datos relacionados con los apoyos otorgados por los programas de desarrollo forestal de la CONAFOR, en el periodo que comprende los años 2008 al 2012 en el Estado de México. Fungiendo como sistema de visualización cartográfica, edición y consulta de información. El Departamento de Desarrollo Forestal de la Comisión Nacional Forestal (CONAFOR) del Estado de México ha creado y reunido un compendio de información geoespacial y alfanumérica a lo largo de la dirección de proyectos desde su surgimiento, con el potencial de servir a la toma de decisiones y de gestión de información.
Para el desarrollo se ha utilizado el modelo de cascada o también llamado lineal secuencial que hace referencia al ciclo de vida del software, ofreciendo métodos y técnicas para la creación de software y en este caso aplicaciones Web Mapping. Se plantea los requerimientos que el sistema debe cumplir, se recolectan los datos, se diseña la base de datos e interfaz de usuario, se implementa y evalúan los resultados.
Se demuestra la importancia del uso de software de código abierto, los servidores de mapas y geotecnologías mediante la utilidad de un sistema de consulta y visualización que sirve al departamento de Desarrollo Forestal de la CONAFOR en el Estado de México para gestionar y explotar los datos almacenados. El sistema contiene una Base de Datos que guarda registros de los apoyos otorgados. Las aplicaciones utilizadas son un Gestor de Bases de Datos PostgreSQL, que trabaja en conjunto con la extensión espacial PostGIS, un servidor de mapas Map Server, un Framework para la representación espacial en la web y editores cartográficos ArcGIS y Quantum GIS.Consejo Mexiquense de Ciencia y Tecnología del Estado de Méxic
An Analysis of the Influence of Students´ Technological Culture on Their Technology
decade has raised the interest among the research community on the acceptance and use of these systems by both teachers and students. At first, the implementation of LMS was based on their technical design and the adaptation of the learning processes to the virtual environment, neglecting students’ characteristics when the systems were deployed, which led to expensive and failing implementations. The Unified Theory of Acceptance and Use of Technology (UTAUT) proposes a framework which allows the study of the acceptance and use of technology that takes into consideration the students’ characteristics and how they affect the acceptance and the degree of use of educational technology. This study questions the role of the user’s attitude towards use of LMS and uses the UTAUT to examine the moderating effect of technological culture in the adoption of LMS in Spain. The results from the comparison and analysis of three different models confirm the relevance of attitude towards use as an antecedent of intention to use the system, as well as the important moderating effect of gender and technological culture. The discussion of results suggests the need for a more in-depth analysis and interrelations of cultural dimensions in the adoption of educational technologies and learning management system
Design of Carvacrol-based active packaging for extending fresh fish shelf-life
Shelf life is the time-span where the product is in good conditions for consumption,
from either safety or quality points of view. Shelf life is defined to guarantee food safety
(“use-by” date), or to guarantee both safety and quality food standards (“best-before
date”).
The aim of active packaging systems is to extend shelf-life by releasing active
substances into the food product. The active packaging is composed of one or several
layers. Each layer may contain a given concentration of the active substance whose
release velocity will depend on the layer material. An adequate selection of the layer
composition and active substance initial concentration will have an impact on shelf life.
In this work, we use mathematical models in combination with optimization methods to
(i) design the optimal configuration of the smart packaging for both “use-by date” and
“best-before date” criteria; and (ii) assess and predict shelf life changes according to
variations on storage conditions. Two different types of models are used: (i) release of
the active substance into the food product [1]; and (ii) shelf-life evolution as a function
of storage conditions and active substance concentration in the food [2].
The growth of Listeria monocytogenes, which affects widely consumed products, is
used as the safety indicator. The KI-value, which is related to ATP-degradation
compounds, is used as the quality indicator. Carvacrol is a substance that inhibits
bacterial growth. In this work, it will be used as the active substance to limit the growth
of Listeria monocytogenes (food safety) and other spoilage bacteria responsible for
quality changes.
The optimal design allows for an increase in shelf-life of around 24% as compared with
the fish product without active packaging
Well-defined, persistent, chiral phthalocyanine nanoclusters: Via G-quadruplex assembly
Octameric near-IR dye nanoclusters are produced by complexation of potassium cations with a phthalocyanine-guanosine conjugate. The combination of hydrogen-bonding, K+ coordination, π-π stacking and steric interactions between the chiral side groups is responsible for defining a specific helical chromophore arrangement in the clusters, which display high stability and maintain their supramolecular identity onto substratesFinancial support from MINECO, Spain (CTQ‐2014‐52869‐P, T.T.; CTQ2014‐57729‐P, D. G.‐R.), the Comunidad de Madrid (S2013/MIT‐2841 FOTOCARBON, T.T.), and the European Research Council (ERC‐StG 279548, D. G.‐R.) is acknowledge
Model-based design of smart active packaging systems with antimicrobial activity
Smart active packaging is an innovative packaging system that combines the benefits of measuring, estimating or predicting different aspects of food quality or safety with the release of an active substance that extends product shelf life. Nevertheless, in its typical configuration, the active packaging and the smart packaging are not connected, and the information provided is not exploited to design the release of the active substance.
In this work, we demonstrate how smart active packaging systems using predictive mathematical models allow the automatic optimisation of food packaging design and the prediction of the expected shelf life along the food chain. On the one hand, the system calculates the best design of the active packaging and the concentration
of the active substance in the different layers that maximise food quality and safety. On the other hand, the model allows to calculate and update shelf life values along the food chain under unexpected changes in the storage conditions. Shelf life estimations and prediction will help distributors and sellers to adjust the product market prices. For example, prices can be lowered to avoid food losses when the product is close to its use-by
date.
Hake (Merluccius merluccius) represents an example of a highly relevant and perishable food that can be conserved using natural antimicrobials. Therefore, the case study selected to illustrate the proposed methodology consists of the smart active packaging of hake using carvacrol as the active substance (antimicrobial). Besides, different polymers are considered as possible active packaging materials. The Matlab™ codes required to perform the simulations of the models described in this work as well as the optimisations for packaging design are available at https://doi.org/10.5281/zenodo.3244153C.V. acknowledges funding received from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 723575 (CoPro project). M.M.I. belongs to the Galician Competitive Research Group (ED431C 2017/029) and the CRETUS strategic partnership (AGRUP2017/01), co-funded by FEDER (EU). M.R.G. acknowledges financial support through the projects IMMICRO (201870E134) and ControlAR (RTI2018-093560-J-I00, MCIU/AEI/FEDER, UE)S
Concurrent Validity and Reliability of Two Portable Powermeters (Power2Max vs. PowerTap) to Measure Different Types of Efforts in Cycling
[EN] The purpose was to assess the concurrent validity and reliability of two portable powermeters
(PowerTap vs. Power2Max) in different types of cycling efforts. Ten cyclists performed
two submaximal, one incremental maximal and two supramaximal sprint tests on an ergometer,
while pedaling power and cadence were registered by both powermeters and a cadence sensor
(GarminGSC10). During the submaximal and incremental maximal tests, significant correlations
were found for power and cadence data (r = 0.992–0.997 and 0.996–0.998, respectively, p < 0.001),
with a slight power underestimation by PowerTap (0.7–1.8%, p < 0.01) and a high reliability of both
powermeters (p < 0.001) for measurement of power (ICC = 0.926 and 0.936, respectively) and cadence
(ICC = 0.969 and 0.970, respectively). However, during the supramaximal sprint test, their agreement
to measure power and cadence was weak (r = 0.850 and 0.253, p < 0.05) due to the low reliability of
the cadence measurements (ICC between 0.496 and 0.736, and 0.574 and 0.664, respectively; p < 0.05)
in contrast to the high reliability of the cadence sensor (ICC = 0.987–0.994). In conclusion, both
powermeters are valid and reliable for measuring power and cadence during continuous cycling
efforts (~100–450 W), but questionable during sprint efforts (>500 W), where they are affected by
the gear ratio used (PowerTap) and by their low accuracy in cadence recording (PowerTap and
Power2Max).S
Countering the Novelty Effect: A Tutorial for Immersive Virtual Reality Learning Environments
Immersive Virtual Reality (iVR) is a new technology, the novelty effect of which can reduce
the enjoyment of iVR experiences and, especially, learning achievements when presented in the
classroom; an effect that the interactive tutorial proposed in this research can help overcome. Its
increasingly complex levels are designed on the basis of Mayer’s Cognitive Theory of Multimedia
Learning, so that users can quickly gain familiarity with the iVR environment. The tutorial was
included in an iVR learning experience for its validation with 65 users. It was a success, according to
the user satisfaction and tutorial usability survey. First, it gained very high ratings for satisfaction,
engagement, and immersion. Second, high skill rates suggested that it helped users to gain familiarity
with controllers. Finally, a medium-high value for flow pointed to major concerns related to skill
and challenges with this sort of iVR experience. A few cases of cybersickness also arose. The survey
showed that only intense cybersickness levels significantly limited performance and enjoyment; low
levels had no influence on flow and immersion and little influence on skill, presence, and engagement,
greatly reducing the benefits of the tutorial, despite which it remained useful.This work was partially supported by the ACIS project (Reference Number INVESTUN/21/BU/0002) of the Consejeria de Empleo e Industria of the Junta de Castilla y León (Spain), the Erasmus+ RISKREAL Project (Reference Number 2020-1-ES01-KA204-081847) of the European Commission and the HumanAid Project (Reference Number TED2021-129485B-C43) of the Proyectos Estratégicos Orientados a la Transición Ecológica y a la Transición Digital of the Spanish Ministry of Science and Innovation
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