EPrints IMDEA Water Institute
Not a member yet
1133 research outputs found
Sort by
Evaluation of the surface free energy of plant surfaces: toward standardizing the procedure
No full textPlant surfaces have been found to have a major chemical and physical heterogeneity and play a key protecting role against multiple stress factors. During the last decade, there is a raising interest in examining plant surface properties for the development of biomimetic materials. Contact angle measurement of different liquids is a common tool for characterizing synthetic materials, which is just beginning to be applied to plant surfaces. However, some studies performed with polymers and other materials showed that for the same surface, different surface free energy values may be obtained depending on the number and nature of the test liquids analyzed, materials' properties, and surface free energy calculation methods employed. For 3 rough and 3 rather smooth plant materials, we calculated their surface free energy using 2 or 3 test liquids and 3 different calculation methods. Regardless of the degree of surface roughness, the methods based on 2 test liquids often led to the under- or over-estimation of surface free energies as compared to the results derived from the 3 Liquids method. Given the major chemical and structural diversity of plant surfaces, it is concluded that 3 different liquids must be considered for characterizing materials of unknown physico-chemical properties, which may significantly differ in terms of polar and dispersive interactions. Since there are just few surface free energy data of plant surfaces with the aim of standardizing the calculation procedure and interpretation of the results among for instance, different species, organs, or phenological states, we suggest the use of 3 liquids and the mean surface tension values provided in this study
Soil amendment using poplar woodchips: an effective strategy for the removal of wastewater-originated contaminants?
No full textVegetation filters, a nature based wastewater purification technology, have been reported as a feasible solution for small municipalities and scattered populations with limited access to sewage networks. However even when such a technology is properly planned, the leaching of contaminants through the unsaturated zone may occur. The amendment of soil with a readily-labile source of carbon is supposed to ameliorate the removal of contaminants by stimulating microbial activity and enhancing sorption processes. In this study, leaching column experiments were carried out to explore if the addition of woodchips to soil could be a feasible strategy to be integrated in a vegetation filter. The soil was collected from an operating vegetation filter treating wastewater that originates from an office building. The column influent solution was synthetized simulating the real wastewater. The infiltration through the column was monitored by tensiometers. Daily effluent samples were collected and analyzed for NT, PT, COD, EC, pH and redox potential. Preliminary results suggest that soil amendments with woodchips enhance the elimination of wastewater-originated contaminants. In particular, NT was highly removed in the column containing woodchips. Elution of organic carbon as a consequence of woodchips degradation may represent a concern when this material is used with high organic carbon wastewater
Draft Genome Sequence of Pseudomonas putida JLR11, a Facultative Anaerobic 2,4,6-Trinitrotoluene Biotransforming Bacterium
No full textWe report the draft genome sequence of Pseudomonas putida JLR11, a facultative anaerobic bacterium that has been studied in detail for its capacity to use the explosive 2,4,6-trinitrotoluene (TNT) as a nitrogen source. The sequence confirms the mechanisms used by this versatile strain to reduce and assimilate nitrogen from TNT
Antimicrobial electrospun silver-, copper- and zinc-doped polyvinylpyrrolidone nanofibers
No full textThe use of electrospun polyvinylpyrrolidone (PVP) nanofibers containing silver, copper, and zinc nanoparticles was studied to prepare antimicrobial mats using silver and copper nitrates and zinc acetate as precursors. Silver became reduced during electrospinning and formed nanoparticles of several tens of nanometers. Silver nanoparticles and the insoluble forms of copper and zinc were dispersed using low molecular weight PVP as capping agent. High molecular weight PVP formed uniform fibers with a narrow distribution of diameters around 500 nm. The fibers were converted into an insoluble network using ultraviolet irradiation crosslinking. The efficiency of metal-loaded mats against the bacteria Escherichia coli and Staphylococcus aureus was tested for different metal loadings by measuring the inhibition of colony forming units and the staining with fluorescent probes for metabolic viability and compromised membranes. The assays included the culture in contact with mats and the direct staining of surface attached microorganisms. The results indicated a strong inhibition for silver-loaded fibers and the absence of significant amounts of viable but non-culturable microorganisms. Copper and zinc-loaded mats also decreased the metabolic activity and cell viability, although in a lesser extent. Metal-loaded fibers allowed the slow release of the soluble forms of the three metals
Electrospun fibers containing metal-releasing particles for microbial growth control
No full textElectrospinning is the only general technique available for the production of nanofibers. It proved suitable to provide nonwovens with high surface to volume ratio, tunable porosity, plasticity to adapt to a variety of sizes and shapes and almost unlimited possibilities of chemical functionalization. The materials used to prepare electrospun fibers range from synthetic to natural polymers, also allowing the possibility of preparing ceramic nanofibers. There is also the possibility of creating hierarchical structures such as core/sheath and surface decorated fibers, which offer the possibility of electrospinning non-spinnable substances and surface complex functionalization. Electrospun fibers may contain a variety of organic or inorganic fillers offering physical reinforcement or the controlled delivery of chemicals included within fibers. The most common filler materials are inorganic nanoparticles that included in nanofibers of decorating their surface, benefit from a support to which they may impart different capacities. Many applications have been developed to take advantage of the unique features of nanofibers, among which the possibility of preparing composite mats with antimicrobial action stands out. The incorporation of antimicrobial compounds in electrospun fibers offers the possibility of developing new antibiotic surfaces that can be used as antibacterial scaffolds for biomedicine, biofouling resistant membranes for environmental uses and materials for active food packaging among many other uses. The aim of this work was to produce biocidal electrospun nanocomposite fibers by incorporating metal carriers to environmentally friendly polymers. For this purpose, the biopolymers polylactic acid and cellulose acetate and the water soluble polyvinylpyrrolidone were used to incorporate metal nanoparticles either free or in supported form. The carriers for metals were a modified sepiolite, mesoporous silica and hybrid organicinorganic materials belonging to the class of metal-organic frameworks. Electrospun fibers were physically characterized by scanning electron microscopy, transmission electron microscopy, X-Ray diffraction and energy dispersive X-Ray spectroscopy, among others. Special attention was paid to the release of metals, which was assessed by inductively coupled plasma mass-spectroscopy measurements. The organisms used for testing the biocidal behaviour of mats were the bacteria Pseudomonas putida, Staphylococcus aureus and Escherichia coli, the yeast Saccharomyces cerevisiae and the fungus Aspergillus niger. Confocal microscopy and microplate readings with fluorochromes measuring cell viability or integrity allowed determining the biocidal effect of composite fibres. For it, the cell-permeant esterase substrate fluorescein diacetate, the nucleic acid stains SYTO 9 and propidium iodide, a luciferin-based ATP determination system and the viability probe for yeasts and fungi FUN 1 were used. These methods were complemented by colony counting and the measurement of cell biomass. The results showed that nanometals, with or without carrier particles can be successfully included in all the polymeric matrixes tested using blended electrospinning. Fibres were produced in all cases as smooth nonwovens without beading and flaws and a fibre diameter of a few hundreds of nanometres. The rate of metal discharge showed an initial peak followed by a period or slower and relatively constant rate of release. Supported metals or structured frameworks resulted in slower metal release and more prolonged biocidal effect with respect to free nanometals. Silver-loaded fibres were particularly effective preventing bacterial colonization and biofilm formation, but copper and cobalt loaded membranes also displayed significant antibiocidal behaviour. The results generally showed a decrease in the number of microorganisms attached to the fibres, an increase in non-viable cells and a parallel decrease i
Diseño de un data logger de bajo coste usando Arduino. Aplicación para la monitorización de sistemas fotovoltaicos cumpliendo el estándar IEC. Parte II
No full textThe role of evapotranspiration in water resources management: local measurements and regional estimates - El papel de la evapotranspiración en la gestión de recursos hídricos: mediciones locales y estimaciones regionales
No full textThis study evaluates the role of evapotranspiration in water resources management at different scales, comprising both spatial and temporal aspects, over the same study area: the Henares river basin. While the spatial aspect is addressed by analyzing different methodologies for its estimation, from local field measurements to reginal remotely sensed estimations and hydrological modeling, the temporal aspect is focused on assesssing water resources availabitility under future climate scenarios. In this study it has also been evaluated how the water availability in the river vbasin would be affected by future changes in climate. Two physically-based distributed hydrological models have been compared: the SIMPA model and the MIKE SHE model
Screen-Printed Electrodes: New Tools for Developing Microbial Electrochemistry at Microscale Level
No full textMicrobial electrochemical technologies (METs) have a number of potential technological applications. In this work, we report the use of screen-printed electrodes (SPEs) as a tool to analyze the microbial electroactivity by using Geobacter sulfurreducens as a model microorganism. We took advantage of the small volume required for the assays (75 μL) and the disposable nature of the manufactured strips to explore short-term responses of microbial extracellular electron transfer to conductive materials under different scenarios. The system proved to be robust for identifying the bioelectrochemical response, while avoiding complex electrochemical setups, not available in standard biotechnology laboratories. We successfully validated the system for characterizing the response of Geobacter sulfurreducens in different physiological states (exponential phase, stationary phase, and steady state under continuous culture conditions) revealing different electron transfer responses. Moreover, a combination of SPE and G. sulfurreducens resulted to be a promising biosensor for quantifying the levels of acetate, as well as for performing studies in real wastewater. In addition, the potential of the technology for identifying electroactive consortia was tested, as an example, with a mixed population with nitrate-reducing capacity. We therefore present SPEs as a novel low-cost platform for assessing microbial electrochemical activity at the microscale level
Experimental CO2 injection: Study of physical changes in sandstone porous media using Hg porosimetry and 3D pore network models
No full textVariations in the pore system of sandstones from the so-called Utrillas Formation (Lower Cretaceous, Iberian Peninsula) after CO2 injection have been investigated in a laboratory on a micro scale. In this study, we present results regarding variations in the pore spaces of sandstones caused by the injection of CO2 and its permanence in supercritical conditions in contact with a rock sample for two months. The modifications produced in the porosity and pore size distribution have been evaluated on two geological samples, using a 3D modelling of the results obtained by Hg intrusion porosimetry. Reconstructions of the pore structure of the rock before and after CO2 injection from mercury intrusion–extrusion curves, generating virtual models of pores that reproduce the experimental porosity. By analysing the results, a drastic modification in the mesoporosity of the rock is confirmed, which may have a paramount influence not only on the total storage capacity but also on the percolation of fluid through the rock