Reverse osmosis membrane composition, structure and performance modification by bisulphite, iron(III), bromide and chlorite exposure

Reverse osmosis (RO) membrane exposure to bisulphite, chlorite, bromide and iron(III) was assessed in terms of membrane composition, structure and performance. Membrane composition was determined by Rutherford backscattering spectrometry (RBS) and membrane performance was assessed by water and chloride permeation, using a modified version of the solution-diffusion model. Iron(III) dosage in presence of bisulphite led to an autooxidation of the latter, probably generating free radicals which damaged the membrane. It comprised a significant raise in chloride passage (chloride permeation coefficient increased 5.3–5.1 fold compared to the virgin membrane under the conditions studied) rapidly. No major differences in terms of water permeability and membrane composition were observed. Nevertheless, an increase in the size of the network pores, and a raise in the fraction of aggregate pores of the polyamide (PA) layer were identified, but no amide bond cleavage was observed. These structural changes were therefore, in accordance with the transport properties observed.Peer ReviewedPostprint (author's final draft

Primordial Black Holes from the QCD axion

We propose a mechanism to generate Primordial Black Holes (PBHs) which is independent of cosmological inflation and occurs slightly below the QCD phase transition. Our setup relies on the collapse of long-lived string-domain wall networks and is naturally realized in QCD axion models with domain wall number $N_{DW}>1$ and Peccei-Quinn symmetry broken after inflation. In our framework, dark matter is mostly composed of axions in the meV mass range along with a small fraction, $\Omega_{\text{PBH}} \gtrsim 10^{-6} \Omega_{\text{CDM}}$ of heavy $M \sim 10^4-10^7 M_\odot$ PBHs. The latter could play a role in alleviating some of the shortcomings of the $\Lambda$CDM model on sub-galactic scales. The scenario has distinct signatures in ongoing axion searches as well as gravitational wave observatories.Comment: 7 pages, 2 figures. v2: version accepted for publication in PR

Geology of the Eastern Prebetic Zone at the Jumilla region (SE Iberia)

This article presents a geological map and cross-sections at 1:50,000 scale covering an area of 609 km2 of the Eastern Prebetic Zone (SE Iberia). The structure of the studied area is characterized by an NW-directed fold-and-thrust belt and inactive salt diapirs that are parallel to the ENE- to NE-regional trend of the eastern Betic Cordillera. This regional trend is locally disrupted by the NW-trending Matamoros Basin, which is flanked by the active Jumilla and La Rosa diapirs. The geological map, the cross-sections and the outcrop observations support the hypothesis that the major Mesozoic rifting phase affecting the Eastern Prebetic Zone occurred during the Upper Jurassic to Santonian times coeval to the development of extensional basins in the Western Tethyan area. The proximal part of this passive margin was subsequently incorporated into the external part of the Betic thin-skinned fold-and-thrust belt. The Upper Cretaceous to Cenozoic tectonic evolution of the study area encompassed the following stages: a Campanian to Aquitanian NW-directed contraction; a Burdigalian to upper Miocene extensional reactivation of the main subsalt faults; and a Serravallian NWdirected contractional reactivation. In this scenario, the combined effect of the previous contractional reactivation of pre-existing salt structures together with the Miocene subsalt extension triggered passive salt extrusion of the La Rosa and Jumilla diapirs

Short-term fire front spread prediction using inverse modelling and airborne infrared images

A wildfire forecasting tool capable of estimating the fire perimeter position sufficiently in advance of the actual fire arrival will assist firefighting operations and optimise available resources. However, owing to limited knowledge of fire event characteristics (e.g. fuel distribution and characteristics, weather variability) and the short time available to deliver a forecast, most of the current models only provide a rough approximation of the forthcoming fire positions and dynamics. The problem can be tackled by coupling data assimilation and inverse modelling techniques. We present an inverse modelling-based algorithm that uses infrared airborne images to forecast short-term wildfire dynamics with a positive lead time. The algorithm is applied to two real-scale mallee-heath shrubland fire experiments, of 9 and 25 ha, successfully forecasting the fire perimeter shape and position in the short term. Forecast dependency on the assimilation windows is explored to prepare the system to meet real scenario constraints. It is envisaged the system will be applied at larger time and space scales.Peer ReviewedPostprint (author's final draft

Structural control of inherited salt structures during inversion of a domino basement-fault system from an analogue modelling approach

The geometries of inverted rift systems are different depending on a large variety of factors that include, among others, the presence of decoupling layers, the thickness of the pre- and syn-extension successions, or structural inheritances. Our study focuses on the inversion of an extensional domino-style basement-fault system with a pre-extension salt layer using analogue models to understand the role of pre-existing structural features during inversion. Models investigate how different overburden and salt thicknesses, inherited extensional structures, and salt distributions condition the evolution during inversion. The experimental results show that models with thick salt can partially or totally preserve the extensional ramp-syncline basin geometry independently of the overburden thickness. In contrast, models with a thin salt layer result in a total inversion of the ramp-syncline basins with the development of crestal collapse grabens and extensional faults affecting the overburden. Inversion also triggered the growth or reactivation of salt-related structures such as primary weld reopening and/or obliteration, diapir rejuvenation, salt thickening, or thrust emplacement. The use of analogue modelling allowed us to address the processes that controlled the growth and evolution of these structural elements during the inversion. Experimental results also provide a template of different structural styles resulting from the positive inversion of basins with a pre-extensional salt layer that can help subsurface interpretation in areas with poor seismic imaging

Role of inheritance during tectonic inversion of a rift system in basement-involved to salt-decoupled transition: Analogue modelling and application to the Pyrenean-Biscay system

The reactivation of former rift systems and passive margins during tectonic inversion and their incorporation into fold-and-thrust belts result in significant structural differences not only between internal and external domains, but also along-strike. The Basque-Cantabrian and Asturian systems are among the best examples to address the role of along-strike changes in rift inheritance since they show a transition from salt to basement-inherited structures divided by a transition zone separating thick- from thin-skinned structural domains. While both domains have been widely described in the literature, the transfer system separating the two has not been sufficiently investigated due to poor seismic imaging and the lack of large-scale outcrops. This contribution aims to address the linkage between basement-controlled (i.e. thick-skinned) and salt-decoupled (i.e. thin-skinned) domains and to describe how deformation is accommodated in the transitional zone between these domains. An experimental programme based on analogue models has been designed that was inspired by the transition from the thin-skinned Basque-Cantabrian Pyrenees to the east to the thick-skinned Asturian Massif to the west. As observed in nature, experimental results show that oblique structures (at low angle with the shortening direction) form in the transitional domain, and their location depends on the linkage of the active structures occurring in both surrounding thick- and thin-skinned domains at different positions. Nevertheless, their orientation and evolution are controlled by the underlying decoupling horizon (i.e. salt). The deformation in the thick-skinned domain produces significant topography over a narrow deformation area due to the lack of effective decoupling levels. On the contrary, deformation in the thin-skinned domain is more distributed due to decoupling, resulting in a wider deformation area of less topography. As a result, syn-contractional sedimentation occurs mainly in the foreland basin in front of the thick-skinned domain, whereas it is observed in the foreland but also in piggyback basins in the thin-skinned domain

Influence of fault geometries and mechanical anisotropies on the growth and inversion of hanging-wall synclinal basins: insights from sandbox models and natural examples

Salt is mechanically weaker than other sedimentary rocks in rift basins. It commonly acts as a strain localizer, and decouples supra- and sub-salt deformation. In the rift basins discussed in this paper, sub-salt faults commonly form wide and deep ramp synclines controlled by the thickness and strength of the overlying salt section, as well as by the shapes of the extensional faults, and the magnitudes and slip rates along the faults. Upon inversion of these rift basins, the inherited extensional architectures, and particularly the continuity of the salt section, significantly controls the later contractional deformation. This paper utilizes scaled sandbox models to analyse the interplay between sub-salt structures and supra-salt units during both extension and inversion. Series 1 experiments involved baseline models run using isotropic sand packs for simple and ramp-flat listric faults, as well as for simple planar and kinked planar faults. Series 2 experiments involved the same fault geometries but also included a pre-extension polymer layer to simulate salt in the stratigraphy. In these experiments, the polymer layer decoupled the extensional and contractional strains, and inhibited the upwards propagation of sub-polymer faults. In all Series 2 experiments, the extension produced a synclinal hanging-wall basin above the polymer layer as a result of polymer migration during the deformation. During inversion, the supra-polymer synclinal basin was uplifted, folded and detached above the polymer layer. Changes in thickness of the polymer layer during the inversion produced primary welds and these permitted the sub-polymer deformation to propagate upwards into the supra-salt layers. The experimental results are compared with examples from the Parentis Basin (Bay of Biscay), the Broad Fourteens Basin (southern North Sea), the Feda Graben (central North Sea) and the Cameros Basin (Iberian Range, Spain)

Algorisme de control sensorless per a motors d’imants permanents sense ranures

En aquest treball s’ha implementat un algorisme de control de velocitat per a un motor sín- cron d’imants permanents de pols llisos amb debanat sense ranures sense utilitzar un sensor de posició, mitjançant l’entorn de Simulink. Tradicionalment, el control d’aquest tipus de motors es basa en la realimentació de la posició i velocitat del rotor obtinguda a través de sensors, com encoders o sensors d’efecte hall. Aquest tipus de motors són majoritàriament emprats en dispositius per al sector mèdic i aeroespacial, on l’espai i la lleugeresa del sistema són uns dels factors més importants. Al mateix temps poden ser sotmesos a condicions ambientals extremes que potencialment malmetin el sensor de posició. L’ús d’algorismes d’estimació de la posició implica l’eliminació del sensor i pot suposar un augment de la fiabilitat i robustesa del sistema, disminuir l’espai usat i reduir els costos associats. L’enfocament d’aquest treball es basa en la utilització d’una tècnica d’estimació de la posició i la velocitat del rotor mitjançant la mesura de les tensions i corrents del motor. Per aconseguir-ho, s’implementa un algorisme d’estimació de la posició del rotor basat en el model, concretament en l’estimació del flux del rotor. El sistema s’ha complementat amb el disseny del llaç de corrent i velocitat mitjançant tècniques de control de camp orientat. L’algorisme s’ha implementat en el programa de simulació Simulink, en temps continu. Els experiments realitzats han permès validar el mètode en tot el rang de velocitats, arrancant amb posició inicial desconeguda, i comprovar la seva robustesa enfront de la indeterminació dels paràmetres del moto

Càlcul de la difusió intraocular a partir de la MTF per diferents dimensions de la imatge de doble pas

Actualment existeix molta recerca pel què fa a l’estudi de la qualitat de la imatge retinal ja que, dels passos que intervenen en la visió, és l’únic de moment que podem millorar. Aquesta qualitat es veu afectada per les aberracions, difracció i difusió. En aquest treball ens centrem en l’estudi de la difusió. Una de les tècniques que ha agafat més protagonisme per a la mesura de la qualitat de la imatge retinal és la del doble pas. L’únic instrument clínic que utilitza aquesta tècnica és l’OQAS o HDA, el qual proporciona un paràmetre anomenat OSI (Objective Scatter Index) per a la quantificació de la difusió. Ho fa a través de l’estudi de les intensitats de la imatge de doble pas a diferents regions. En aquest treball, es valida un nou paràmetre anomenat FSI (Frequency Scatter Index) per a la quantificació de la difusió. Aquest es calcula en el domini de les freqüències, és a dir, tenint en compte la transformada de Fourier de la imatge de doble pas. L’objectiu del treball és trobar la configuració òptima pel què fa a eliminació de soroll, longitud d’ona i mida de la imatge per a l’estudi de la difusió en ulls amb cataractes nuclears.Actualmente hay mucha investigación respecto al estudio de la calidad de la imagen retiniana puesto que, de los pasos que intervienen en la visión, es el único mejorable por el momento. Dicha calidad está afectada por las aberraciones, difracción y difusión. En este trabajo nos centraremos en el estudio de la difusión. Una de las técnicas que ha cobrado protagonismo para la medida de la calidad de la imagen retiniana es la del doble paso. El único instrumento clínico que utiliza esta técnica es el OQAS o HDA, el cual proporciona un parámetro llamado OSI (Objective Scatter Index) para cuantificar la difusión. Lo hace mediante el estudio de las intensidades de la imagen de doble paso en diferentes zonas. En este trabajo, se pretende validar un nuevo parámetro llamado FSI (Frequency Scatter Index) para la cuantificación de la difusión. Éste se calcula en el dominio de frecuencias, es decir, teniendo en cuenta la transformada de Fourier de la imagen de doble paso. El objetivo del trabajo es encontrar la configuración óptima para la eliminación del ruido, longitud de onda y tamaño de la imagen para el estudio de la difusión en ojos con cataratas nucleares.Nowadays there is a lot of research in the field of retinal image quality as, from the steps involved in vision; it is the only one that we can improve. This quality is affected by aberrations, diffraction and scattering. This study is focused in the analysis of scattering. One of the techniques that have gained popularity for the retinal image quality analysis is the one known as double pas. There is only one clinical device which uses this technique, the OQAS or HAD, and it provides a parameter called OSI (Objective Scatter Index) in order to quantify the scattering. This parameter studies the intensity of the double pas image in different areas. This paper validates a new parameter called FSI (Frequency Scatter Index) for the quantification of scattering. It is calculated in the frequency domain, that is, it considers the Fourier transform of the double-pass image. The objective of this study is to find the optimal configuration with regard to noise removal, wavelength and image size for the scattering assessment in eyes with nuclear cataracts