Thermochemical storage is based on a reversible chemical reaction; energy can be stored when an endothermic chemical reaction occurs and then, energy is released when it is reversed in an exothermic ...reaction. According to literature and based on the energy storage density (esd), MgCl2·6H2O is a promising candidate material for thermochemical energy storage. Bischofite is an inorganic salt obtained as a by-product material from extraction processes of non-metallic minerals, from Salar de Atacama in Chile, containing approximately 95% of MgCl2·6H2O. Thus, the purpose of this study was to characterize the dehydration reaction of bischofite ore, studied as a low-cost thermochemical storage material. Thermogravimetric data for bischofite were obtained using a TGA instrument coupled to a DSC, at four different isotherms 70°C, 80°C, 90°C and 100°C. The results of conversion reaction (α-t) from the thermal dehydration experiments, demonstrated the first phase of dehydration with the loss of two water molecules. The study showed a typical sigmoid curve with a significant acceleration in the conversion at the beginning of the reaction until it reaches a maximum rate, where the curve keeps constant. The same behavior was observed for all the temperatures used. The kinetics of bischofite dehydration model was determined using the isothermal kinetics method. For this, the thermogravimetric data were fitted to the most used kinetic models (D, F, R, A) and then their respective correlation coefficients R were evaluated. The results indicated that the dehydration reaction of bischofite was described by the kinetics of chemical reaction of cylindrical particles R2. The rate of dehydration reaction and esd of bischofite are lower as compared to synthetic MgCl2·6H2O, at temperatures higher than 80°C. However, the cost of materials to store 1MJ of energy is three times lower for bischofite, which is an evident advantage to promote the reuse of this material left as waste by the non-metallic industry.
•Bischofite main component is MgCl2·6H2O, a typical TCS material for seasonal storage.•Bischofite dehydration and kinetic study are presented in this work.•The rate of dehydration reaction of bischofite is lower compared with synthetic MgCl2·6H2O.•The esd for bischofite are lower compared with synthetic MgCl2·6H2O.•The cost to store 1MJ of energy is three times lower for bischofite.
Recommender systems survey Bobadilla, J.; Ortega, F.; Hernando, A. ...
Knowledge-based systems,
July 2013, 2013-7-00, 20130701, Letnik:
46
Journal Article
Recenzirano
Recommender systems have developed in parallel with the web. They were initially based on demographic, content-based and collaborative filtering. Currently, these systems are incorporating social ...information. In the future, they will use implicit, local and personal information from the Internet of things. This article provides an overview of recommender systems as well as collaborative filtering methods and algorithms; it also explains their evolution, provides an original classification for these systems, identifies areas of future implementation and develops certain areas selected for past, present or future importance.
•Several HVAC system power consumption prediction systems are designed and implemented.•Long short-term memory neural networks to predict the next day of power consumption.•The systems implements low ...errors and optimal Pearson correlation coefficients between the predictions and the real consumption values.•Daily consumption predictions provide a powerful tool for Demand-Side Management techniques.
In this paper, the design and implementation process of an artificial neural network based predictor to forecast a day ahead of the power consumption of a building HVAC system is presented. The featured HVAC system is situated at MagicBox, a real self-sufficient solar house with a monitoring system. Day ahead prediction of HVAC power consumption will remarkably enhance the Demand Side Management techniques based on appliance scheduling to reach defined goals. Several multi step prediction models, based on LSTM neural networks, are proposed. In addition, suitable data preprocessing and arrangement techniques are set to adapt the raw dataset. Considering the targeted prediction horizon, the models provide outstanding results in terms of test errors (NRMSE of 0.13) and correlation, between the temporal behavior of the predictions and test time series to be forecasted, of 0.797. Moreover, these results are compared to the simplified one hour ahead prediction that reaches nearly optimal test NRMSE of 0.052 and Pearson correlation coefficient of 0.972. These results provide an encouraging perspective for real-time energy consumption prediction in buildings.
The goal of this work was to study the mechanical behavior of concrete with recycled Polyethylene Therephtalate (PET), varying the water/cement ratio (0.50 and 0.60), PET content (10 and 20
vol%) and ...the particle size. Also, the influence of the thermal degradation of PET in the concrete was studied, when the blends were exposed to different temperatures (200, 400, 600
°C). Results indicate that PET-filled concrete, when volume proportion and particle size of PET increased, showed a decrease in compressive strength, splitting tensile strength, modulus of elasticity and ultrasonic pulse velocity; however, the water absorption increased. On the other hand, the flexural strength of concrete-PET when exposed to a heat source was strongly dependent on the temperature, water/cement ratio, as well as on the PET content and particle size. Moreover, the activation energy was affected by the temperature, PET particles location on the slabs and water/cement ratio.
The discovery of eukaryotic giant viruses has transformed our understanding of the limits of viral complexity, but the extent of their encoded metabolic diversity remains unclear. Here we generate ...501 metagenome-assembled genomes of Nucleo-Cytoplasmic Large DNA Viruses (NCLDV) from environments around the globe, and analyze their encoded functional capacity. We report a remarkable diversity of metabolic genes in widespread giant viruses, including many involved in nutrient uptake, light harvesting, and nitrogen metabolism. Surprisingly, numerous NCLDV encode the components of glycolysis and the TCA cycle, suggesting that they can re-program fundamental aspects of their host's central carbon metabolism. Our phylogenetic analysis of NCLDV metabolic genes and their cellular homologs reveals distinct clustering of viral sequences into divergent clades, indicating that these genes are virus-specific and were acquired in the distant past. Overall our findings reveal that giant viruses encode complex metabolic capabilities with evolutionary histories largely independent of cellular life, strongly implicating them as important drivers of global biogeochemical cycles.
The transformation of methane into methanol or higher alcohols at moderate temperature and pressure conditions is of great environmental interest and remains a challenge despite many efforts. ...Extended surfaces of metallic nickel are inactive for a direct CH4 → CH3OH conversion. This experimental and computational study provides clear evidence that low Ni loadings on a CeO2(111) support can perform a direct catalytic cycle for the generation of methanol at low temperature using oxygen and water as reactants, with a higher selectivity than ever reported for ceria-based catalysts. On the basis of ambient pressure X-ray photoemission spectroscopy and density functional theory calculations, we demonstrate that water plays a crucial role in blocking catalyst sites where methyl species could fully decompose, an essential factor for diminishing the production of CO and CO2, and in generating sites on which methoxy species and ultimately methanol can form. In addition to water-site blocking, one needs the effects of metal–support interactions to bind and activate methane and water. These findings should be considered when designing metal/oxide catalysts for converting methane to value-added chemicals and fuels.
The evolutionary forces that determine genome size in bacteria and archaea have been the subject of intense debate over the last few decades. Although the preferential loss of genes observed in ...prokaryotes is explained through the deletional bias, factors promoting and preventing the fixation of such gene losses often remain unclear. Importantly, statistical analyses on this topic typically do not consider the potential bias introduced by the shared ancestry of many lineages, which is critical when using species as data points because of the potential dependence on residuals. In this study, we investigated the genome size distributions across a broad diversity of bacteria and archaea to evaluate if this trait is phylogenetically conserved at broad phylogenetic scales. After model fit, Pagel's lambda indicated a strong phylogenetic signal in genome size data, suggesting that the diversification of this trait is influenced by shared evolutionary histories. We used a phylogenetic generalized least-squares analysis (PGLS) to test whether phylogeny influences the predictability of genome size from dN/dS ratios and 16S copy number, two variables that have been previously linked to genome size. These results confirm that failure to account for evolutionary history can lead to biased interpretations of genome size predictors. Overall, our results indicate that although bacteria and archaea can rapidly gain and lose genetic material through gene transfers and deletions, respectively, phylogenetic signal for genome size distributions can still be recovered at broad phylogenetic scales that should be taken into account when inferring the drivers of genome size evolution.
Summary
The treatment environment for chronic hepatitis C has undergone a revolution, particularly in genotype 1. Gone are interferon‐based therapy and its associated tolerability challenges, ...inadequate response rates and numerous baseline factors that affect response to therapy. New and emerging treatment regimens employ all‐oral combinations of direct‐acting antiviral agents, and results of clinical trials suggest that these regimens routinely achieve cure rates >90%, even in patients who failed prior interferon‐based triple therapy. In 2015, three all‐oral FDA‐approved regiments will be available for genotype 1 (sofosbuvir /ledipasvir, sofosbuvir/simeprevir, and paritaprevir/r/ombitasvir/dasabuvir). Furthermore, new treatment combinations appear to be more tolerable and require shorter duration of therapy. We provide an overview of the classes of direct‐acting antiviral agents (DAAs), the clinical factors affecting their integration into combination therapies and recent findings from trials of such combination therapies in patients with genotype 1 HCV infection.
Luminescent nanomaterials have shown promise for thermal sensing in bio‐applications, yet little is known of the role of organic coatings such as supported lipid bilayers on the thermal conductivity ...between the nanomaterial and its environment. Additionally, since the supported lipid bilayer mimics the cell membrane, its thermal properties are fundamentally important to understand the spatial variations of temperature and heat transfer across membranes. Herein, a new approach is described that enables direct measurement of these thermal properties using a LiYF4:Er3+/Yb3+ upconverting nanoparticle encapsulated within a conformal supported lipid bilayer and dispersed in water as a temperature probe yielding the temperature gradient across the bilayer. The thermal conductivity of the lipid bilayer is measured as a function of the temperature, being 0.20 ± 0.02 W m−1 K−1 at 300 K. For the uncapped nanoparticles dispersed in water, the temperature dependence of the thermal conductivity is also measured in the 300–314 K range as 0.63–0.69 ± 0.11 W m−1 K−1. Using a lumped elements model, the directional heat transfer is calculated at each of the system interfaces, namely, nanoparticle–bilayer and bilayer–nanofluid, opening a new avenue to understand the membrane biophysical properties as well as the thermal properties of organic and polymer coatings.
The thermal properties of organic coatings on inorganic nanoparticles, for example biomimetic lipid bilayers, play a key role in their application as intracellular temperature probes. Measuring the core temperature using upconversion thermometry enables direct determination of the bilayer thermal conductivity, opening avenues for studying fundamental membrane biophysical and thermal properties of organic and polymer coatings for a multitude of nanomaterials.
Background and purpose: The present study evaluated the role of CB2 receptors in the regulation of depressive‐like behaviours. Transgenic mice overexpressing the CB2 receptor (CB2xP) were challenged ...with different types of acute and chronic experimental paradigms to evaluate their response in terms of depressive‐like behaviours.
Experimental approach: Tail suspension test (TST), novelty‐suppressed feeding test (NSFT) and unpredictable chronic mild stress tests (CMS) were carried out in CB2xP mice. Furthermore, acute and chronic antidepressant‐like effects of the CB2 receptor‐antagonist AM630 were evaluated by means of the forced swimming test (FST) and CMS, respectively, in wild‐type (WT) and CB2xP mice. CB2 gene expression, brain‐derived neurotrophic factor (BDNF) gene and protein expressions were studied in mice exposed to CMS by real‐time PCR and immunohistochemistry, respectively.
Key results: Overexpression of CB2 receptors resulted in decreased depressive‐like behaviours in the TST and NSFT. CMS failed to alter the TST and sucrose consumption in CB2xP mice. In addition, no changes in BDNF gene and protein expression were observed in stressed CB2xP mice. Interestingly, acute administration of AM630 (1 and 3 mg·kg−1, i.p.) exerted antidepressant‐like effects on the FST in WT, but not in CB2xP mice. Chronic administration of AM630 for 4 weeks (1 mg·kg−1; twice daily, i.p.) blocked the effects of CMS on TST, sucrose intake, CB2 receptor gene, BDNF gene and protein expression in WT mice.
Conclusion and implications: Taken together, these results suggest that increased CB2 receptor expression significantly reduced depressive‐related behaviours and that the CB2 receptor could be a new potential therapeutic target for depressive‐related disorders.
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