Artículos (Física Aplicada II)

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Design and implementation of an energy selector for laser-accelerated protons
(MDPI, 2024-06-29) Reija Vecino, Alicia; Esteban Blasco, David; Alejo Alonso, Aarón; Apiñaniz Aginako, Jon Imanol; Bembibre Fernández, Adrián; Benlliure Anaya, José; Ehret, Michael; García López, Francisco Javier; Jiménez Ramos, María del Carmen; Juan Morales, Jessica; Méndez Valverde, María Cruz; Pascual Álvarez, David; Rodríguez Frías, María Dolores; Rodríguez Ramos, Mauricio; Seimetz, Michael; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Universidad de Sevilla. Departamento de Física Aplicada II; Generalitat Valenciana; Junta de Castilla-León; Xunta de Galicia; Universidad de Sevilla. RNM138: Física Nuclear Aplicada
Highly intense bunches of protons and ions with energies of several MeV/u can be generated with ultra-short laser pulses focused on solid targets. In the most common interaction regime, target normal sheath acceleration, the spectra of these particles are spread over a wide range following a Maxwellian distribution. We report on the design and testing of a magnetic chicane for the selection of protons within a limited energy window. This consisted of two successive, anti-parallel dipole fields generated by cost-effective permanent C-magnets with customized configuration and longitudinal positions. The chicane was implemented into the target vessel of a petawatt laser facility with constraints on the direction of the incoming laser beam and guidance of the outgoing particles through a vacuum port. The separation of protons and carbon ions within distinct energy intervals was demonstrated and compared to a ray tracing code. Measurements with radiochromic film stacks indicated the selection of protons within [2.4, 6.9] MeV, [5.0, 8.4] MeV, or ≥6.9 MeV depending on the lateral dispersion. A narrow peak at 4.8 MeV was observed with a time-of-flight detector.
Role of particle size on the cohesive behavior of limestone powders at high temperature
(Elsevier, 2020) Espín Milla, Manuel Jesús; Durán Olivencia, Francisco José; Valverde Millán, José Manuel; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Universidad de Sevilla. Departamento de Física Aplicada II; Ministerio de Economía y Competitividad (MINECO). España
Thermal Energy Storage (TES) using granular solids is gaining momentum in the last years. With no degradation up to very high temperatures and very low price the use of some granular materials such as sand or SiC would be feasible for storing sensible heat at large scale. A further step beyond TES is thermochemical energy storage (TCES) wherein the granular solids undergo a highly endothermic reaction at high temperature. Energy can be in this way more efficiently stored in the long term and released on demand by means of the reverse exothermic reaction. The Calcium Looping process, based on the calcination/carbonation of CaCO3, is being actively investigated for this purpose. However, a caveat of using granular solids for energy storage is the possible increase of interparticle adhesive forces with temperature which would severely hamper the flowability of the solids in the process. The cohesiveness of granular materials is essentially determined by particle size. In this paper we investigate the dependence of the tensile yield strength and compressibility of CaCO3 powders on temperature and consolidation stress using samples of narrow particle size distribution in the relevant range between ∼30 and ∼80μm particle size and temperatures up to 500°C. Our experimental results show that powder cohesiveness is greatly increased with temperature especially in the case of the finest powders whose tensile yield strength can be increased by up 2 orders of magnitude. The increase of cohesiveness with temperature is further enhanced with a previously applied consolidation stress, which is particularly relevant for applications wherein large amounts of solids are to be stored at high temperature. Experimental data are consistent with the predictions by a contact mechanics model assuming that the solids deform plastically at interparticle contacts. A main conclusion from our work is that some mechanical properties of the solids, specially the mechanical hardness, and how they change with temperature, play a critical role on the flowability of the solids as affected by an increase of temperature.
Equivalence between face nonsignaling correlations, full nonlocality, all-versus-nothing proofs, and pseudotelepathy
(American Physical Society, 2024) Liu, Yuan; Chung, Ho Yiu; Zambrini Cruzeiro, Emmanuel; Gonzales Ureta, Junior R.; Ramanathan, Ravishankar; Cabello Quintero, Adán; Universidad de Sevilla. Departamento de Física Aplicada II; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Fundação para a Ciência e a Tecnologia. Portugal; Universidad de Sevilla. FQM239: Fundamentos de Mecánica Cuántica
We show that a quantum correlation 𝑝 is in a face of the nonsignaling polytope with no local points if and only if 𝑝 has nonlocal content 1, if and only if 𝑝 allows for a Greenberger-Horne-Zeilinger-like proof, and if and only if 𝑝 provides a perfect strategy for a nonlocal game. That is, face nonsignaling (FNS) correlations, full nonlocality (FN), all-versus-nothing (AVN) proofs, and pseudotelepathy (PT) are equivalent. This shows that different resources behind a wide variety of fundamental results are in fact the same resource. We demonstrate that quantum correlations with FNS = FN = AVN = PT do not need to maximally violate a tight Bell inequality. We introduce a method for identifying quantum FNS = FN = AVN = PT correlations and use it to prove quantum mechanics does not allow for FNS = FN = AVN = PT neither in the (3,3;3,2) nor in the (3,2;3,4) Bell scenarios. This solves an open problem that, because of the FNS = FN = AVN = PT equivalence, has implications in several fields.
Study the twilight zone before it is too late: exploitation and degradation of the mysterious layer between the sunlit ocean surface and the abyss jeopardize fish stocks and the climate
(Springer, 2020-04) Martin, Adrian P.; Boyd, Philip; Buesseler, Ken O.; Cetinic, Ivona; Claustre, Hervé; Henson, Stephanie A.; Irigoien, Xabier; Kriest, Iris; Memery, Laurent; Robinson, Carol; Saba, Grace; Sanders, Richard; Siegel, David; Villa Alfageme, María; Guidi, Lionel; Universidad de Sevilla. Departamento de Física Aplicada II
Acoustics in Baroque Catholic church spaces
(MDPI, 2024-10-30) Alberdi Causse, Enedina; Galindo del Pozo, Miguel; León-Rodríguez, Ángel Luis; León Rodríguez, Jesús; Universidad de Sevilla. Departamento de Construcciones Arquitectónicas I (ETSA); Universidad de Sevilla. Departamento de Física Aplicada II; Universidad de Sevilla. TEP999: Habitae Habitabilidad, Acondicionamiento y Energía en Arquitectura; Universidad de Sevilla. TEP130: Arquitectura, Patrimonio y Sostenibilidad: Acústica, Iluminación, Óptica y Energía
After the Council of Trent (1545–1563), the Catholic Church undertook a profound renovation, which affected the spatial configuration of the churches to adjust to the spirit of the Counter-Reformation. The acoustic cultural heritage in these spaces have been studied by different researchers, proposing the joint analysis of 66 Catholic churches from the Baroque period. This study delves into the global characterisation of the sample and establishes correlations between geometric and acoustic parameters. From the acoustic analysis, it is clear that the central floor typology, as opposed to Latin cross churches, presents better average values of musical clarity in relation to their volume. The analysis of the relationship between acoustic and geometric parameters, when the sample of churches is discriminated by typology, allows for the establishment of appropriate correlations for Latin cross floor plans, single naves and basilicas, but not when the analysis is carried out for the entire sample. These correlations are a tool that allows us to evaluate acoustic parameters not measured in situ in Catholic churches of the Baroque period in a predictive way as a function of other measured acoustic or geometric parameters.
129I in sediment cores from the Celtic Sea by AMS through a microwave digestion process
(Elsevier, 2022) Lérida Toro, Victoria; Abascal Ruíz, Unai; Villa Alfageme, María; Klar, Jessica K.; Hicks, Natalie; López Gutiérrez, José María; Universidad de Sevilla. Departamento de Física Aplicada II; Universidad de Sevilla. Departamento de Física Aplicada I
Radiochemical methods before measurement are indispensable to determine Iodine-129 by Accelerator Mass Spectrometry (AMS) in environmental samples. In particular, in sediments, iodine is associated with both inorganic and organic matter, and it presents in several chemical forms. Therefore, the radiochemical procedure must be designed to extract all the different iodine species from the matrix, whilst being as robust and time effective as possible. In this work, different microwave digestion methods, together with the processing of the iodine species to be measured by AMS, were tested and their performances are presented here. Two sediment cores, one with muddy sediment (core A) and one with permeable sandy sediment (core I), collected in the Celtic Sea, were used and the results were evaluated to determine an optimized iodine extraction. The method consisted of a microwave digestion with concentrated nitric acid followed by a double liquid–liquid extraction and the final precipitation of silver iodide (AgI), required to measure iodine by AMS. Back extraction of iodine in a reducing solution during purification was carried out with hydrazine (NH2-NH2). Subsequent additional steps were added to optimize all iodine species extraction. First, hydrochloric hydroxylamine (NH2OH⋅HCl) and so dium bisulfite (Na2S2O5) were used to homogenize all iodine species before extraction through a redox process. Second, sodium hypochlorite (NaOCl) was added to remove any final organic matter after digestion. The final method incorporated sodium hydroxide (NaOH) combined with NaOCl to facilitate reduction of iodine in so lution and enhance the NaOCl effect. The different methods were validated against an internal standard and the last method was chosen, as it showed the most reproducible and accurate results. As practical application, Iodine129 concentration from both cores were compared, showing concentrations between 0.19 × 1012 at/kg and 7.16 × 1012 at/kg for core A and between 0.28 × 1012 at/kg and 2.40 × 1012 at/kg for core I. Despite the 129I diffusion detected in the deeper layers, depth profiles accurately reproduced Sellafield discharges, which is the nuclear fuel reprocessing plant closest to the cores.
Comparison and validation of methods for the determination of 90Sr by Cerenkov counting in biological and sediment samples, including green chemistry metrics
(Springer, 2019) Rivera Silva, Jorge; Hurtado Bermúdez, Santiago José; Villa Alfageme, María; Manjón Collado, Guillermo; Universidad de Sevilla. Departamento de Física Aplicada II
In this work, a comparative study of two popular radiochemical procedures for 90Sr determination in biological and sediment samples via Cerenkov counting was performed. Comparative tests were carried out with a Liquid Scintillation Counter (LSC) and several key factors related to green analytical chemistry were considered. Chemical yields, time of analysis, cost per sample, hazardous reagents used (H-factor), wastes generated (E-factor) and energy consumed (Q-factor) were calculated. The separation methods are based on two contrasted extraction mechanisms: chromatographic extraction (using Sr resin, a crown-ether diluted in octanol) and liquid–liquid solvent extraction (using HDEHP, an organophosphorus compound), where the chromatographic extraction method was optimized. The developed analytical procedure based on HDEHP was cheaper and faster than the analytical procedure based on Sr resin, according to the green chemistry. On the other hand, the Sr resin method provided a minimum detectable activity (MDA) of 1.1 Bq kg−1, lower than 1.5 Bq kg−1 corresponding to HDEHP method, due to the higher capacity of sample that can be loaded into the resin. The accuracy and reproducibility of both methods was confrmed in the analysis of certifed reference materials provided by the International Atomic Energy Agency (IAEA)
Correlation of phytoplankton satellite observations and 210Po radiological doses in molluscs
(Elsevier, 2021) Hurtado Bermúdez, Santiago José; Expósito Gálvez, Juan Carlos; Villa Alfageme, María; Universidad de Sevilla. Departamento de Física Aplicada II
Po is strongly accumulated by marine organisms, thus the contribution of 210Po from sea-food is crucial to evaluate population radiological doses by food ingestion. Consequently, 210Po constitutes the primary source of natural radiation to radiological doses in humans through the consumption of food and contributes significantly to the total radiation dose. Most of the national regulations on radiological doses include coastal measurements of 210Po, for this reason fast, robust techniques to evaluate 210Po concentrations and doses in molluscs are required. Data of salinity, temperature, suspended particulate matter (SPM), chlorophyll-a, and phytoplankton concentration in the Gibraltar Strait coast, in the confluence of the Mediterranean Sean and the Atlantic Ocean, during the period of May 2014–June 2015 were analyzed together with 210Po, 40K, 210Pb and 234Th activity concentration in different types of bivalve mollusks in the same time-period. The physicochemical parameters were evaluated using the Copernicus Marine Environment Monitoring Service (CMEMS) products based on satellite observations. This tool provides biogeochemical data of the ocean on a global and regional scale. A multivariate statistical analysis, including contrasted natural radioactivity contents, allowed the discrimination of bivalve mollusks from Atlantic and Mediterranean coasts. A cluster analysis determined which physicochemical parameters influence the radioisotopes concentrations in molluscs. A highly significant negative correlation 210Po concentration in molluscs and phytoplankton concentration suggested that phytoplankton concentration in the water column is a determinant factor to regulate 210Po concentration in those animals. In this work it is presented a first approach to use this relationship to estimate radiological doses by mollusks ingestion from phytoplankton concentrations. These results introduce a useful tool to calculate the radiological doses in seafood from chlorophyll satellite image (e.g. using CMEMS tools).
Distribution of 1 236U in the U.S. GEOTRACES Eastern Pacific Zonal Transect and its use as a 2 water mass tracer
(Elsevier, 2019) Villa Alfageme, María; Chamizo Calvo, Elena; Kenna, Timothy C.; López Lora, Mercedes; Casacuberta, Nuria; Chang, Clara H.; Masqué, Pere; Christi, Marcus; Universidad de Sevilla. Departamento de Física Aplicada II; Universidad de Sevilla. Departamento de Física Aplicada I
We report dissolved concentrations of the long-lived radioisotope 236U measured in the water column along the 2013 US GEOTRACES Eastern Pacific Zonal Transect (GP16). This transect followed a 10–15°S line from Manta, Ecuador, to Papeete, Haiti, French Polynesia, crossing the southern East Pacific Rise, intercepting one of the largest hydrothermal plumes as well as a productivity gradient, which includes the upwelling zone and associated low oxygen waters offshore from Peru and the oligotrophic sub-tropical gyre. Accelerator Mass Spectrometry was used to measure dissolved seawater 236U concentrations as low as 1 × 103 atom kg−1, which are among the lowest levels reported to date. Differences in upper water column 236U distributions from east to west are a result of variable contributions from different surface and intermediate waters encountered along the transect. The distribution of 236U, both in depth and geographically, provides complementary information to that obtained from Δ14C and helium isotopes, demonstrating that 236U concentrations are diagnostic in the identification of and contributions from the different deep and bottom water masses encountered along the EPZT (Jenkins et al., 2017). For example, we observe minimum 236U concentrations along the EPZT between 2000 and 3000 m that are consistent with contributions attributed to Pacific Deep Water. We also observe increases in 236U below 3000 m at the eastern and western termini of the EPZT. This is consistent with contributions associated with Antarctic Bottom Water and Lower Circumpolar Deep Water. Our results indicate that 236U may be used in conjunction with Δ14C and 3He isotopes as an additional tool with which to identify and resolve contributions from different water masses in the Pacific Ocean.
Inefficient transfer of diatoms through the subpolar Southern Ocean twilight zone
(Springer Nature, 2024) Williams, Jimmy R.; Giering, Sarah; Baker, Christopher A.; Pabortsava, Katsiaryna; Briggs, ‪Nathan; East, Holly; Espinola, Benoit; Blackbird, Sabena; Le Moigne, Frédéric; Villa Alfageme, María; Poulton, Alex J.; Carvalho, Filipa; Pebody, Corinne; Saw, Kevin; Moore, C. Mark; Henson, Stephanie A.; Sanders, Richard; Martin, Adrian P.; Universidad de Sevilla. Departamento de Física Aplicada II
The Southern Ocean, a region highly vulnerable to climate change, plays a vital role in regulating global nutrient cycles and atmospheric CO2 via the biological carbon pump. Diatoms, photosynthetically active plankton with dense opal skeletons, are key to this process as their exoskeletons are thought to enhance the transfer of particulate organic carbon to depth, positioning them as major vectors of carbon storage. Yet conficting observations obscure the mechanistic link between diatoms, opal and particulate organic carbon fuxes, especially in the twilight zone where greatest fux losses occur. Here we present direct springtime fux measurements from diferent sectors of the subpolar Southern Ocean, demonstrating that across large areas of the subpolar twilight zone, carbon is efciently transferred to depth, albeit not by diatoms. Rather, opal is retained near the surface ocean, indicating that processes such as diatom buoyancy regulation and grazer repackaging can negate ballast efects of diatoms’ skeletons. Our results highlight that the presence of diatoms in surface waters of the Southern Ocean’s largest biome does not guarantee their importance as vectors for efcient carbon transfer through the subpolar twilight zone. Climate change-driven shifts in phytoplankton community composition may afect biologically sequestered carbon pools less than currently predicted.
Seasonal variations of sinking velocities in Austral diatom blooms: lessons learned from COMICS
(Elsevier, 2024) Villa Alfageme, María; Briggs, ‪Nathan; Ceballos Romero, Elena; Soto Borrero, Feliciano Carlos de; Manno, Clara; Giering, Sarah; Universidad de Sevilla. Departamento de Física Aplicada II
The sinking velocity (SV) of organic particles is a critical driver of carbon transport to the deep sea. Accurate determination of marine particle SV and their influencing factors is therefore a key to better understanding of biological carbon storage in the ocean. We used two different approaches to estimate average SVs of particles during a Southern Ocean spring bloom (North of South Georgia): optical backscatter sensors on gliders (“large”, >50 μm diameter), and radioactive pairs ( 234Th–238U and 210Po-210Pb). Our results were complemented with time-of flight estimations of bulk SVs from deep sediment traps deployed at 1950 m. Bulk SVs increased consistently with depth from 15 ± 1 m d− 1 at 10 m to 50 ± 10 m d− 1 at the depth of export (Zp = 95 m) and from 96 ± 35 m d− 1 at 150 m to 119 ± m d− 1 at 450 m. Only the fastest particles, mainly comprised by faecal pellets (FPs) and diatom aggregates, survived remineralization and dominated carbon fluxes at deep depth. The SV variability at the base of the Euphotic Zone was studied in relation to the stage of the bloom by analysing three different moments of the spring diatom bloom in the region during the years 2012, 2013 and 2017. The export efficiency (ExpEff), defined as the ratio POC flux exported below the Euphotic Zone to the satellite derived surface NPP, was also evaluated. It was found from the temporal series that ExpEff and SV vary throughout the diatom bloom as the community structure progresses. A good correlation between both variables was observed (ExpEff = (0.023 ± 0.006) SV, r = 0.82, p = 0.04). Showing that the variability in how efficiently the carbon flux is exported out of the Euphotic Zone can be explained by the SV at which the particles sink. Further investigations are required to analyse if this is a specific model of the functioning of the BCP during the diatom bloom in North South Georgia or if it can be extrapolated to other scenarios.
Sequestration efficiency in the iron-limited North Atlantic: implications for iron supply mode to fertilized blooms
(American Geophysical Union, 2014) Le Moigne, Frederic; Moore, C. Mark; Sanders, Richard; Villa Alfageme, María; Steigenberger, Sebastian; Achterberg, Eric P.; Universidad de Sevilla. Departamento de Física Aplicada II
Estimates of the amount of carbon sequestered in the ocean interior per unit iron (Fe) supplied, as quantified by the sequestration efficiency (Ceffx), vary widely. Such variability in Ceffx has frequently been attributed to estimate uncertainty rather than intrinsic variability. Here we derive new estimates of Ceffx for the subpolar North Atlantic, where Fe stressed conditions have recently been demonstrated. Derived values of Ceffx from across the region, including areas subject to atypical external Fe fertilization events during the year of sample collection (2010), ranged from 17 to 19 kmol C (mol Fe 1). Comparing these estimates with values from other systems, considered in the context of variable bloom durations in the different oceanographic settings, we suggest that apparent variability in Ceffx may be related to the mode of Fe delivery.
Polypropylene as an absorbent layer for acoustic ceilings: Sound absorption and life cycle assessment
(Elsevier, 2024-11-01) Galindo del Pozo, Miguel; Alberdi Causse, Enedina; Sánchez Burgos, Marco Antonio; Nieves Pavón, Francisco José; Flores-Colen, Inês; Universidad de Sevilla. Departamento de Física Aplicada II; Universidad de Sevilla. Departamento de Construcciones Arquitectónicas I (ETSA); Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; Fundação para a Ciência e a Tecnologia. Portugal; Universidad de Sevilla. TEP130: Arquitectura, Patrimonio y Sostenibilidad: Acústica, Iluminación, Óptica y Energía; Universidad de Sevilla. TEP205: Análisis y Evaluación de Sistemas Constructivos y Estructurales en la Arquitectura
The substantial volume of polypropylene fabric waste generated because of its use in protective elements in hospital environments calls for the exploration of environmentally friendly solutions. This study characterises the acoustic absorption coefficient of surgical mask waste (polypropylene) to be used as absorbent layers in acoustic ceilings. Additionally, a life cycle assessment (LCA) has been carried out. Although values of absorption coefficients for polypropylene have been published, none include life cycle studies. This research is in keeping with the principles of circular economy, contributing to waste reduction while also exploring innovative applications for recycled materials. The starting point of this study is the replacement of the most common material layer on the market, mineral wool, with a polypropylene layer that has the same or better acoustic performance based on single number absorption indexes and ratings following international standards for the calculation of sound absorption coefficients and life cycles. Various waste processing methods and different densities and thicknesses have been evaluated. The results show that recycled polypropylene material exhibits suitable behaviour as an acoustic absorbent layer, particularly in acoustic ceilings. The LCA considered transport, shredding, washing, disinfection, and drying and confirms the eco-efficiency of this absorbent layer.
A benchmark for Monte Carlo simulation in gamma-ray spectrometry
(Elsevier, 2019-12) Lépy, M. C.; Thiam, C.; Anagnostakis, M.; Galea, R.; Gurau, D.; Hurtado Bermúdez, Santiago José; Karfopoulos, K.; Liang, J.; Liu, H.; Luca, A.; Mitsios, I.; Potiriadis, C.; Savva, M. I.; Thanh, T. T.; Thomas, V.; Townson, R. W.; Vasilopoulou, T.; Zhang, M.; Universidad de Sevilla. Departamento de Física Aplicada II; Universidad de Sevilla. RNM138: Física Nuclear Aplicada
Monte Carlo (MC) simulation is widely used in gamma-ray spectrometry, however, its implementation is not always easy and can provide erroneous results. The present action provides a benchmark for several MC software for selected cases. The examples are based on simple geometries, two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The action outputs (input files and efficiency calculation results, including practical recommendations for new users) are made available on a dedicated webpage.
Consistency test of coincidence-summing calculation methods for extended sources
(Elsevier, 2020-01) Sima, O.; De Vismes Ott, A.; Dias, M. S.; Dryak, P.; Ferreux, L.; Gurau, D.; Hurtado Bermúdez, Santiago José; Jodlowski, P.; Karfopoulos, K.; Koskinas, M. F.; Laubenstein, M.; Lee, Y. K.; Lépy, M. C.; Luca, A.; Menezes, M. O.; Moreira, D. S.; Nikolič, J.; Peyres, V.; Saganowski, P.; Savva, M. I.; Semmler, R.; Solc, J.; Thanh, T. T.; Tyminska, K.; Tyminski, Z.; Vidmar, T.; Vukanac, I.; Yucel, H.; Universidad de Sevilla. Departamento de Física Aplicada II; Universidad de Sevilla. RNM138: Física Nuclear Aplicada
An internal consistency test of the calculation of coincidence-summing correction factors FC for volume sources is presented. The test is based on exact equations relating the values of FC calculated for three ideal measurement configurations. The test is applied to a number of 33 sets of FC values sent by 21 teams. Most sets passed the test, but not the results obtained using the quasi-point source approximation; in the latter case the test qualitatively indicated the magnitude of the bias of FC.
Optimization of a new liquid scintillation spectrometer for the measurement of environmental levels of 3H in water samples
(Elsevier, 2024-07) García León, José Luis; García León, Manuel; Manjón Collado, Guillermo; Rivera Silva, Jorge; Universidad de Sevilla. Departamento de Física Aplicada II; Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear; Consejo de Seguridad Nuclear; Universidad de Sevilla. RNM138: Física Nuclear Aplicada
The activity concentration of 3H in water samples collected from places unaffected by nuclear activities or for human consumption can be very low. In these cases, determination procedures must achieve a Minimum Detectable Activity (MDA) low enough to ensure that 3H is accurately determined. In this paper, we present a method that uses a new Liquid Scintillation Spectrometer (LSC in what follows): the Quantulus GCT 6220. Furthermore, a new liquid scintillation cocktail, the ProSafe LT+, has been tested for 3H measurement, showing to be a good option for the determination of low levels of this radionuclide. The MDAs achieved are low enough to enable the measurement of very low levels of 3H in recent environmental water. The results obtained using a Quantulus GCT 6220 and Prosafe LT + are compared to those obtained with a Quantulus 1220 and Prosafe HC + as liquid scintillation cocktail.
Transfer of 129I to freshwater fish species within Fukushima and Chernobyl exclusion zones
(Elsevier, 2023) Teien, Hans Christian; Wada, Toshihiro; Kashparov, Valery; López Gutiérrez, José María; García-Tenorio García-Balmaseda, Rafael; Hinton, Thomas G.; Salbu, Brit; Universidad de Sevilla. Departamento de Física Aplicada II
Unique data is reported on the transfer of 129I iodine from freshwaters to fish as well as the internal distribution within fish from the Fukushima and Chernobyl exclusion zones (ChEZ). Samples of water, sediments and fish were collected in the contaminated ponds Inkyozaka and Suzuuchi, and in the less contaminated Abukuma river in Fukushima, as well as in the contaminated Glubokoye lake and in the less contaminated Starukha lake in ChEZ. In water, 129I was mainly present as low molecular mass (LMM) and negatively charged species, while a minor fraction was associated with colloidal fraction, most probably organic material in water. The sedimentwater 129I apparent distribution coefficients, Kd, ranged from 225 to 329 L/kg, equal that of stable iodine, but did not correlate with 129I/127I ratio or 129I/137Cs ratio as the environmental distribution of radioactive iodine was different from that of stable iodine and radioactive cesium. Concentration ratios (CR) of 129I in muscle of freshwater fish ranged from 85 to 544 across waterbodies with limited water exchange, similar in Fukushima and Chernobyl, but varied with respect to fish species. Thus, this is the first results on the transfer of 129I to freshwater fish, showing that the CR for freshwater fish is higher than CR reported for marine fish. Concentrations of 129I in fish muscle were, however, lower than in the intestinal content, indicating the influence of more contaminated dietary ingredients probably of terrestrial origin based due to δ13C signal on as well as of biodilution. The present results highlighted also that the radiation dose in fish was highly inhomogeneously distributed. Based on the present 129I/127I atomic ratio of 10− 5 in the most contaminated fish in the ponds in Fukushima and Glubokoye lake in Chernobyl, however, a radiation dose of 10 μSv/y would not pose any harm to the fish population.
Impact of vegetable oil type on the rheological and tribological behavior of Montmorillonite-based oleogels
(MDPI, 2022-08-13) Martín Alfonso, Manuel Antonio; Rubio Valle, José Fernando; Hinestroza, Juan P.; Martín Alfonso, José Enrique; Universidad de Sevilla. Departamento de Física Aplicada II; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Junta de Andalucía
We formulated and characterized oleogels based on montmorillonite clay and vegetable oils that could serve as eco-friendly semi-solid lubricants. In particular, we studied the influence of the physical-chemical properties of olive, castor, soybean, linseed, and sunflower oils on the rheological, chemical, thermal, and tribological properties of the semi-solid lubricants. We prepared the oleogels via the highly intensive mixing of vegetable oils with clay at a concentration of 30 wt.%. The oleogels exhibited shear-thinning, thixotropy, structural recovery, and gel-like behavior commonly related to that of a three-dimensional network. The results were corroborated via XRD measurements showing the presence of intercalated nanoclay structures well-dispersed in the vegetable oil. Empirical correlations between the content of saturated (SFAs), unsaturated (UFAs), mono-unsaturated (MUFAs) and poly-unsaturated (PUFAs) fatty acids and the plateau modulus of the aerogels were found. From these experimental results, we can conclude that the fatty acid profile of the vegetable oils exerts an important influence on the rheological and tribological properties of resulting clay and vegetable oil oleogels.
Exploring cellulose triacetate nanofibers as sustainable structuring agent for castor oil: formulation design and rheological insights
(MDPI, 2024-03-25) Martín Alfonso, Manuel Antonio; Rubio Valle, José Fernando; Estrada Villegas, Gethzemani Mayeli; Sánchez Domínguez, Margarita; Martín Alfonso, José Enrique; Universidad de Sevilla. Departamento de Física Aplicada II; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Universidad de Huelva; Junta de Andalucía
Developing gelled environmentally friendly dispersions in oil media is a hot topic for many applications. This study aimed to investigate the production of electrospun cellulose triacetate (CTA) nanofibers and to explore their potential application as a thickening agent for castor oil. The key factors in the electrospinning process, including the intrinsic properties of CTA solutions in methylene chloride (DCM)/ethanol (EtOH), such us the shear viscosity, surface tension, and electrical conductivity, were systematically studied. The impact of the CTA fiber concentration and the ratio of DCM/EtOH on the rheological properties of the gel-like dispersions in castor oil was then investigated. It was found that dispersions with a non-Newtonian response and above a critical concentration (5 wt.%), corresponding to approximately 2–2.5 times the entanglement concentration, are required to produce defect-free nanofibers. The average fiber diameter increased with CTA concentration. Further, the morphology and texture of the electrospun nanofibers are influenced by the ratio of solvents used. The rheological properties of dispersions are strongly influenced by the concentration and surface properties of nanofibers, such as their smooth or porous textures, which allow their modulation. Compared to other commonly used thickeners, such as synthetic polymers and metal soaps, CTA electrospun nanofibers have a much higher oil structuring capacity. This work illustrated the potential of using CTA nanofibers as the foundation for fabricating gel-like dispersions in oil media, and thus exerting hierarchical control of rheological properties through the use of a nanoscale fabrication technique.
Experimental post-selection loophole-free time-bin and energy-time nonlocality with integrated photonics
(Optica Publishing Group, 2024-04-20) Santagiustina, Francesco B.L.; Agnesi, Costantino; Alarcón Cuevas, Álvaro; Cabello Quintero, Adán; Xavier, Guilherme B.; Villoresi, Paolo; Vallone, Giuseppe; Universidad de Sevilla. Departamento de Física Aplicada II; Linköpings Universitet; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Agencia Estatal de Investigación. España; Ministero dell’Istruzione, dell’Università e della Ricerca; Wallenberg Center for Quantum Technology
Time-bin (TB) and energy-time (ET) entanglements are crucial resources for long-distance quantum information processing. However, their standard implementations suffer from the so-called post-selection loophole that allows for classical simulation and thus prevents quantum advantage. The post-selection loophole has been addressed in proof-of-principle experiments. An open problem though is to close it in real-life applications based on integrated technologies. This is especially important since, so far, all integrated sources of TB and ET entanglements suffer from the post-selection loophole. Here, we report post-selection loophole-free certification of TB or ET entanglement in integrated technologies, by implementing in a silicon nitride chip the “hug” scheme [Phys. Rev. Lett. 102, 040401 (2009) [CrossRef] ] and certifying genuine TB entanglement through the violation of a Bell inequality.

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