New understanding of the shape-memory response in thiol-epoxy click systems: towards controlling the recovery process

Our research group has recently found excellent shape-memory response in “thiol-epoxy” thermosets obtained with click-chemistry. In this study, we use their well-designed, homogeneous and tailorable network structures to investigate parameters for better control of the shape-recovery process. We present a new methodology to analyse the shape-recovery process, enabling easy and efficient comparison of shape-memory experiments on the programming conditions. Shape-memory experiments at different programming conditions have been carried out to that end. Additionally, the programming process has been extensively analysed in uniaxial tensile experiments at different shape-memory testing temperatures. The results showed that the shape-memory response for a specific operational design can be optimized by choosing the correct programming conditions and accurately designing the network structure. When programming at a high temperature (T » Tg), under high network mobility conditions, high shape-recovery ratios and homogeneous shape-recovery processes are obtained for the network structure and the programmed strain level (eD). However, considerably lower stress and strain levels can be achieved. Meanwhile, when programming at temperatures lower than Tg, considerably higher stress and strain levels are attained but under low network mobility conditions. The shape-recovery process heavily depends on both the network structure and eD. Network relaxation occurs during the loading stage, resulting in a noticeable decrease in the shape-recovery rate as eD increases. Moreover, at a certain level of strain, permanent and non-recoverable deformations may occur, impeding the completion and modifying the whole path of the shape-recovery process.Postprint (author's final draft

Phenomenological characterization of sequential dual-curing of off-stoichiometric "thiol-epoxy" systems: Towards applicability

An extensive characterization of a sequential dual-curing system based on off-stoichiometric “thiol-epoxy” mixtures was carried out using thiol compounds of different functionality. The intermediate and final materials obtained after each curing stages at different thiol-epoxy ratios were studied by means of thermomechanical and rheological experiments. The storage and loss modulus and the loss factor tan d were monitored during the curing process to analyse gelation and network structure build-up. The critical ratio for gelation was determined making use of the ideal Flory-Stockmayer theory and compared with experimental results. Intermediate materials obtained in the vicinity of the theoretical critical ratio did not have the mechanical consistency expected for partially crosslinked materials, did not retain their shape and even experienced undesired flow upon heating to activate the second curing reaction. The rheological results showed that the critical ratio is higher than the predicted value and that a softening during the second curing stage affects the shape-retention at this ratio. From the thermomechanical results, a wide range of intermediate and final materials with different properties and applicability can be obtained by properly choosing the thiol-epoxy ratio: from liquid-like to highly deformable intermediate materials and from moderately crosslinked (deformable) to highly crosslinked (brittle) final materials.Postprint (author's final draft

Ab initio thermal expansion and thermoelastic properties of ringwoodite (\u3b3-Mg2SiO4) at mantle transition zone conditions

Thermal convection in the Earth\u2019s mantle is driven by lateral variations in temperature and density which are substantially controlled by the local volume thermal expansion of the constituent mineral phases. Ringwoodite is a major component of the lower mantle transition zone, but its thermal expansivity and thermoelastic properties are still affected by large uncertainties. Ambient thermal expansion coefficient (\u3b1_V0), for instance, can vary as much as 100% according to different experimental investigations available from the literature. In this work, we perform ab initio density functional theory calculations of vibrational properties of spinel-structured Mg2SiO4 ringwoodite in order to provide reliable thermophysical data up to mantle transition zone conditions. Temperature- and pressure-dependent thermal expansivity has been obtained by phonon dispersion calculations in the framework of quasi-harmonic approximation (QHA) up to 25 GPa and 2000 K. Theoretical analysis of vibrational spectra reveals that accurate prediction of IR and silent modes, along with their relative mode Gr\ufcneisen parameters, is crucial to define thermal expansivity. A six-parameter analytical function is able to reproduce ab initio values fairly well in the whole investigated P-T range, i.e. \u3b1_V (P,T) = (1.6033\ub710-5 + 8.839\ub710-9 T + 11.586\ub710-3 T-1 \u2013 6.055 T-2 + 804.31 T-3)\ub7exp-(\u20132.52\ub710-2 P), with temperature in Kelvin and pressure in Gigapascal. Ab initio static and isothermal bulk moduli have been derived for ringwoodite along with their P, T and cross derivatives, i.e. K_0 = 184.3 GPa, K_(T,300K) = 176.6 GPa; K_0^' = 4.13, K_(T,300K)^' = 4.16; (\u3016 02K\u3017_T/ 02T)_P = -0.0233 GPa/K and (\u3016 02^2 K\u3017_T/ 02P 02T)_0= 1.0\ub710-4 K-1. Computed thermal expansivity and thermoelastic properties supports the evidence that QHA performs remarkably well for Mg2SiO4 ringwoodite up to mantle transition zone temperatures. Since volume thermal expansion of ringwoodite is strongly pressure-dependent and its pressure dependence becomes more marked with the increasing temperature, internally-consistent assessments and empirical extrapolation of thermoelastic data to deep mantle conditions should be taken with care to avoid inaccurate or spurious predictions in phase equilibrium and mantle convection numerical modelling

Learning Bayesian Networks for Student Modeling

In the last decade, there has been a growing interest in using Bayesian Networks (BN) in the student modelling problem. This increased interest is probably due to the fact that BNs provide a sound methodology for this difficult task. In order to develop a Bayesian student model, it is necessary to define the structure (nodes and links) and the parameters. Usually the structure can be elicited with the help of human experts (teachers), but the difficulty of the problem of parameter specification is widely recognized in this and other domains. In the work presented here we have performed a set of experiments to compare the performance of two Bayesian Student Models, whose parameters have been specified by experts and learnt from data respectively. Results show that both models are able to provide reasonable estimations for knowledge variables in the student model, in spite of the small size of the dataset available for learning the parametersUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

La legislación del Patrimonio Histórico Español y de los museos andaluces. El caso del Museo Carmen Thyssen Málaga

El Museo Carmen Thyssen Málaga es una institución que goza de gran prestigio en la ciudad, con una proyección nacional e internacional. Como entidad museística poseedora de bienes integrantes del Patrimonio Histórico, está sometida a una serie de normas y leyes que pretenden garantizar altos estándares de calidad en el panorama cultural, así como proteger, salvaguardar, difundir y conservar dicho patrimonio. Nuestro estudio se ha dividido en dos bloques de diferente carácter, pero interrelacionados: el primero, dedicado al aparato legislativo que rodea los ámbitos del Patrimonio Histórico en España y Andalucía, y de los Museos andaluces, con especial hincapié en el Registro Andaluz de Museos); el segundo, sobre el Museo Carmen Thyssen Málaga, su proceso de creación y las historias de sus colecciones y del palacio que las alberga. En definitiva, el asunto medular de este trabajo ha sido entender el entramado legislativo para realizar un diagnóstico de la Realidad actual del Museo y de qué forma cumple con los requisitos, funciones y deberes previstos.The Museo Carmen Thyssen Málaga is a renowned institution, with a national and international projection. As a museum entity that owns assets that are part of the Historical Heritage, it is subject to a series of regulations and laws that seek to guarantee high quality standards in the cultural panorama, as well as to protect, safeguard, disseminate and preserve said heritage. Our study has been divided into two blocks of different but interrelated nature: the first one, dedicated to the legislative apparatus that surrounds the areas of Historical Heritage in Spain and Andalusia, and the Andalusian Museums (with special emphasis on the Andalusian Registry of Museums); the second one, on the Museo Carmen Thyssen Málaga (its creation process and the history of its collections and the palace that houses them). In short, the core issue of this work has been to understand the legislative framework to make a diagnosis of the current reality of the Museum and how it meets the requirements, functions and duties provided.Universidad de Sevilla. Grado en Historia del Art

Evolución de la comedia norteamericana: de ‘La fiera de mi niña’ a ‘¿Qué me pasa, doctor?’

El género definido como cómico ha evolucionado considerablemente desde su época de florecimiento asociada a los años 30 hasta su decadencia, que comenzó en los años 70. Este trabajo se centra en analizar la evolución del género cómico desde la screwball comedy (comedia alocada), característica de los años 30, hasta el inicio de otro tipo de comedia con trasfondo más romántico en los años 70. El objetivo principal consiste en analizar los cambios que se produjeron en el género a partir de unas características invariables en la comedia, y, de esta forma, determinar cuáles fueron las causas de su decadencia. A través del análisis de películas cómicas representativas de las décadas a estudiar se conseguirá proyectar el panorama de la comedia en el periodo más importante del género.Departamento de Historia Moderna, Contemporánea y de América, Periodismo y Comunicación Audiovisual y PublicidadGrado en Periodism

Variable threshold of trigeminal cold-thermosensitive neurons is determined by a balance between TRPM8 and Kv1 potassium channels

Molecular determinants of threshold differences among cold thermoreceptors are unknown. Here we show that such differences correlate with the relative expression of IKD, a current dependent on Shaker-like Kv1 channels that acts as an excitability brake, and ITRPM8, a cold-activated excitatory current. Neurons responding to small temperature changes have high functional expression of TRPM8 (transient receptor potential cation channel, subfamily M, member 8) and low expression of IKD. In contrast, neurons activated by lower temperatures have a lower expression of TRPM8 and a prominent IKD. Otherwise, both subpopulations have nearly identical membrane and firing properties, suggesting that they belong to the same neuronal pool. Blockade of IKD shins the threshold of cold-sensitive neurons to higher temperatures and augments cold-evoked nocifensive responses in mice. Similar behavioral effects of IKD blockade were observed in TRPA1-/- mice. Moreover, only a small percentage of trigeminal cold-sensitive neurons were activated by TRPA1 agonists, suggesting that TRPA1 does not play a major role in the detection of low temperatures by uninjured somatic cold-specific thermosensory neurons under physiological conditions. Collectively, these findings suggest that innocuous cooling sensations and cold discomfort are signaled by specific low- and high-threshold cold thermoreceptor neurons, differing primarily in their relative expression of two ion channels having antagonistic effects on neuronal excitability. Thus, although TRPM8 appears to function as a critical cold sensor in the majority of peripheral sensory neurons, the expression of Kv1 channels in the same terminals seem to play an important role in the peripheral gating of cold-evoked discomfort and pain. Copyright © 2009 Society for Neuroscience.This work was supported by funds from the Spanish Ministry of Education and Science: Projects BFU2007-61855 to F.V., and BFU2005-08741 and CONSOLIDER-INGENIO 2010 CSD2007-00023 to C.B., and the Spanish Fundación Marcelino BotínPeer Reviewe

Oral candidiasis in patients with renal transplants

Objectives: Oral candidiasis (OC) is a frequent oral lesion in renal transplant patients (RTPs). Despite the in - creased prevalence of OC in RTPs, no study has examined related risk factors. The aims of this study were to analyze the prevalence of and risk factors for OC in RTPs compared with age- and gender-matched healthy control group (HC) as well as determine the incidence of OC after transplantation. Study D esing: We analyzed the prevalence and risk factors of OC in a group of 500 RTPs (307 men, 193 women, mean age 53.63 years) and 501 HC subjects (314 men, 187 women, mean age 52.25 years). Demographic and pharmacological data were recorded for all subjects. Incident cases of OC were ascertained retrospectively from outpatient clinical records only in the RTP group. Results: The prevalence of OC was 7.4% in RTPs compared with 4.19% in HC (P<0.03). The most frequent type of OC in the two groups was denture stomatitis. Statistical association was found between OC and age, mycophe - nolate mofetil dose and blood levels, dentures and tobacco. The multiple logistic regression model only chose for denture variable. According to the outpatient clinical records, 24 RTPs suffered OC during the first moth post- transplant. Severe lesions affecting the oral cavity and pharynx appeared in 79% of the OC cases. Conclusions: This study shows a lower prevalence of OC in RTPs than previous reports. Denture stomatitis was the most frequent OC prevalence form described in RTPs. Severe candidiasis is more frequent in the immediate posttransplant period. The presence of denture is an important risk factor of OC. These results emphasise the importance of adequate pre- and post-transplant oral health and denture cleaning and adjustment is recommended for these subjects to prevent this infection

Spontaneous spawning of Atlantic bluefin tuna Thunnus thynnus kept in captivity

Beginning 48-72 h after GnRHa treatment in 2009, massive spawning occurred for 17 days, with a daily maximum of 34 million eggs collected (SELFDOTT, 2010). On 17th June 2010 spontaneous spawning started in cage R2. From this day onwards and more or less daily viable eggs were obtained from both cages so no hormonal implants were used. Fish spawned intermittently for a period of 34 days in both cages, with a total of 58 million eggs collected. Cage R1 spawned for 26 days and produced 48 million eggs and cage R2 spawned for 28 days and produced 10 million eggs (Figure 1). As happened in 2009 (SELFDOTT, 2010), due to the almost non-existence of currents throughout the spawning period, almost all the eggs were collected at the surface, held by the plastic curtain. Only a small amount of eggs were captured by the egg collectors, which were designed to operate under current. Eggs were transported to the IEO facilities in Mazarrón (SE- Spain) where they were incubated. On average, the hatching rate was above 90%. No difference in hatching success was observed between 2009 (from hormonally treated cage) and 2010 (from spontaneously spawning fish).Commission of the European Communities, specific RTD program of Framework Program 7, SELFDOTT, “From capture based to self-sustained aquaculture and domestication of bluefin tuna, Thunnus thynnus” (GA 212797)

Motion control in free-standing shape-memory actuators

In this work, free-standing shape-memory thermally triggered actuators are developed by laminating 'thiol-epoxy'-based glassy thermoset (GT) and stretched liquid-crystalline network (LCN) films. A sequential curing process was used to obtain GTs with tailored thermomechanical properties and network relaxation dynamics, and also to assemble the final actuator. The actuation extent, rate and time were studied by varying the GT and the heating rate in thermo-actuation with an experimental approach. The results demonstrate that it is possible to tailor the actuation rate and time by designing GT materials with a glass transition temperature close to that of the liquid-crystalline-to-isotropic phase transition of the LCN, thus making it possible to couple the two processes. Such coupling is also possible in rapid heating processes even when the glass transition temperature of the GT is clearly lower than the isotropization temperature of the LCN, depending on the network relaxation dynamics of the GT and the presence of thermal gradients within the actuators. Interestingly, varying the GT network relaxation dynamics does not affect the actuation extent. As predicted by the analytical model developed in our previous work, the modulus of the GT layer is mainly responsible for the actuation extent. Finally, to demonstrate the enhanced control of the actuation, specifically designed actuators were assembled in a three-dimensional actuating device able to make complex motions (including 'S-type' bending). This approach makes it possible to engineer advanced functional materials for application in self-adaptable structures and soft robotics.Postprint (author's final draft