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The oxidation of water is essential to the sustainable production of fuels using sunlight or electricity, but designing active, stable and earth-abundant catalysts for the reaction is challenging. Now, a complex containing five iron atoms is shown to efficiently oxidize water by mimicking key features of the oxygen-evolving complex in green plants.

The chemical characteristics of mine tailings, organic amendments (doses), and plants are the critical factors that must be evaluated and monitored to ensure the sustainability of phytostabilization. The aim of this study was to evaluate the mobility of copper (Cu) in mine tailings (MT) of the Zone Central of Chile to which commercial humic substances were added, examining their effect on the uptake of Atriplex halimus. Two commercial humic substances (HS1 and HS2) extracted from leonardite (highly oxidized lignite), of different pH and total organic carbon, were evaluated by adsorption curve for Cu. In columns, soluble Cu, pH, and electrical conductivity in leachates were evaluated for MT, MT + HS1, and MT + HS2, and HS1 and HS2 in doses of 120 mg kg-1. In pot assay, seeds were germinated directly in MT and cultivated for 140 days with the addition of HS2 in 120 and 240 mg kg-1. Mine tailing presents high concentration of Cu (2016 ± 223 mg kg-1, pH 6.3 ± 0.1). The results of sequential extraction indicate that Cu is associated with the sulfide fraction of low risk of mobility. The amount of Cu sorbed by HS1 was higher than that sorbed by HS2, and both humic substances showing better fit to the Freundlich than Langmuir model. Lixiviation of Cu was significantly lower in MT + HS1 (0.166 ± 0.043 mg kg-1) and MT + HS2 (0.157 ± 0.018 mg kg-1) than in MT (0.251 ± 0.052 mg kg-1). Copper concentration in plants reached 185.8 ± 37.8 mg kg-1 in the roots and 32.6 ± 7.4 mg kg-1 in the aerial parts cultivated in MT without effect of the humic substance addition in Cu uptake nor growth. Copper concentrations in the aerial parts were adjusted to sufficient or normal levels in plant. A good management of mine tailings through phytostabilization could consider an adequate mixture of humic substances (to avoid leaching of metals) and an organic amendment that provides essential nutrients and increases biomass generation.

Nitric oxide (NO) mediated transmission in the dorsal raphe nucleus (DRN) has been shown to be involved in the modulation of anxiety-like behaviors. We investigated whether inhibition of nitric oxide synthase (NOS) in the DRN would prevent anxiety-like behavior induced by ethanol withdrawal. Male Wistar rats were treated with ethanol 2-6% (v/v) for a period of 21 days. Ethanol withdrawal was induced by abrupt discontinuation of the treatment. Experiments were performed 48 h after ethanol discontinuation. Rats with a guide cannula aimed at the DRN received intra-DRN injections of the non-selective NOS inhibitor NG-nitro-l-arginine methyl ester (l-NAME), selective neuronal NOS (nNOS) inhibitor N(ω)-propyl-l-arginine (NPLA), or selective inhibitor of inducible NOS (iNOS) N-([3-(aminomethyl)phenyl] methyl) ethanimidamidedihydrochloride (1400W). Five minutes later, the animals were tested in the elevated plus maze (EPM). Plasma ethanol levels were determined by gas chromatography. There was a reduction in plasma ethanol levels 48 h after ethanol withdrawal. Rats from the ethanol withdrawal group showed decreased exploration of the open arms of the EPM with no change in the exploration of enclosed arms. Intra-DRN treatment with l-NAME (100 nmoles/0.2 μL) and 1400W (1 nmol/0.2 μL), but not NPLA (10 nmoles/0.2 μL) in the DRN attenuated the decrease in the exploration of the open arms of the EPM induced by ethanol withdrawal. The major new finding of the present study is that iNOS in the DRN plays a role in the anxiety-like behavior induced by ethanol withdrawal.

Abstract The present paper reports the construction of an experimental installation to measure local condensing two-phase flow heat transfer coefficient and frictional pressure drop within mini-channel tubes, the validation measurements developed with R134a and the experimental measurements of heat transfer coefficient and frictional pressure drop made with R32 and R410A. This experimental work is carried out in a test apparatus which allows determining the local heat flux extracted from the condensing fluid. For this purpose, the wall temperature is measured along the test section in several points. The saturation temperature is determined from the saturation pressure, which is measured at the inlet and the outlet of the test channel. Experimental data of R32 and R410A are also compared with some predicting models widely accepted in the literature.

Abstract Wave trends have been shown to be relevant to energy generation in various areas of the world. Accordingly, this article describes the impact of wave trends on the design of oscillating water column wave energy converters. First, wave trends across the North-East Atlantic Ocean are analysed based on the ERA5 reanalysis. In addition, an empirical model that provides the capture width of an oscillating water column is employed, identifying an approximately linear relationship between the average wavelength and the optimal width of the chamber. Thus, combining wave trends and the empirical model, the optimal size of the chamber is found to vary significantly between different geographical locations and over the four decades between 1979 and 2018. Differences between the original geometry and the geometry optimised considering wave trends, reach up to 15% in some locations. As a consequence, oscillating water column chambers designed based on past available resources rather than the resource corresponding to the time when the device is to be deployed are demonstrated to be inefficient, with a significant difference in the optimal width and absorbed energy of the chamber. Accounting for changes in resource availability over time may assist in cost optimisation of unconventional renewable energy technologies.

Abstract Solar energy, as main energy supply that sustains life on Earth, is also an unavoidable component of the complex strategy in achieving a clean and fair energy transition and goals for sustainable development by 2030. The present work studies the potential of installing Photovoltaic Distributed Generation at Universidad Politecnica de Madrid – Ciudad Universitaria campus. To this end, the study focuses on the electricity generation, carbon reduction and economic feasibility of solar photovoltaic systems installation using and comparing two different approaches based on data input with different time resolution, simulation software and level of details. Results show that the optimal photovoltaic power that maximizes emissions savings also ensures the best economic return, and in addition coincides with the maximum solar potential of the Campus, which is about 3.3 MW. At campus level, approximately 77% of the photovoltaic electricity production would be consumed locally, which would suppose a coverage of about 40% of the total electricity consumption. Emissions savings could reach 30% and an in-depth economic analysis indicates that the project is highly profitable. These results and methodology could be used to assess the feasibility of photovoltaic systems at other universities and help entities study the solar potential of their buildings.

Abstract This study evaluates the mechanical behaviour of a ceramic disk which makes up an innovative volumetric absorber design. The new receiver design is formed by a group of disks which are rotating inside a cavity, distributing the radiation absorbed in the aperture to the whole cavity. This research studies the stress fields due to thermal gradients and its effect in the crack propagation in the disks. The complete analysis has been carried out in three steps: the mechanical characterization of the material, in order to know its fracture properties, the computational fluid dynamics (CFD) analysis of the disk, in order to know the temperature distribution in the disk and the finite element model (FEM), which uses as inputs the results of the two previous steps and solves the stress fields in the disk and the fracture behaviour. Fracture and crack growing in the disk have been modelled by using a cohesive element, which, from the fracture properties of the material, allows simulating the crack growing in the disk. This investigation, by means of stress fields and crack propagation analysis, demonstrates the mechanical viability of the disks concept.

Abstract The development of robust and cost-effective hot gas filtration technologies is crucial to facilitate the implementation of advanced coal-based power systems. Understanding the structural characteristics of the dust cake, such as porosity, in relation to the pressure drop evolution is a subject of interest to improve the filtration process. This paper focuses on the study of dust cake compaction and its influence on cake porosity. A semi-empirical model based on Kozeny–Carman equation has been applied to experimental data from the operation of four types of commercial filters (two bag filters and two rigid filters) in a hot gas filtration experimental facility. The method proposed calculates the cake porosity from the specific dust cake resistance coefficient and dust properties. Cake porosity values obtained have been analysed to determine the effect of the operating parameters (filtration velocity, temperature and filtering media). Results show that filtration velocity is the variable that most affects the dust cake porosity. In addition, a correlation between filtration velocity and dust cake porosity has been established.