Artículos (Física Aplicada II)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/10854

Examinar

Mostrando 1 - 20 de 303

Accuracy of Machine Learning algorithms for HPGe detector efficiency determination
(Elsevier, 2026) González González, Beatriz; Abascal Ruiz, Unai; Villa Alfageme, María; Hurtado Bermúdez, Santiago José; Física Aplicada II
The accurate determination of full-energy peak efficiency (FEPE) in High-Purity Germanium (HPGe) detectors is critical for gamma-ray spectrometry, especially when source-detector geometries vary. In this study, we investigate the application of six supervised machine learning (ML) algorithms—Polynomial Regression, Random Forest, XGBoost, LightGBM, Sparse Gaussian Process, and Multi-Layer Perceptron—for predicting FEPE of a Low Energy HPGe (LEGe) detector across a broad energy range (40–1600 keV) and diverse source types (point and volumetric). Datasets used for training, validation and testing the ML models were generated using Monte Carlo simulations (GESPECOR). Model performance was evaluated using cross-validation and standard error metrics (R2, RMSE, MRE). Among the tested models, Polynomial Regression and LightGBM demonstrated superior predictive accuracy and interpretability, achieving R2 values above 0.9999. SHAP values were used for explainability, demonstrating that the models successfully capture the key physical mechanisms influencing FEPE. These results position ML models as reliable and generalizable alternative to conventional FEPE calibration methods.
Evaluation of different parameters affecting the liquid scintillation spectrometry measurement of gross alpha and beta index in water samples
(Elsevier, 2011) Palomo, Marta; Villa Alfageme, María; Casacuberta, Nuria; Peñalver Hernando, Alejandra; Borrull Ballarín, Francesc; Aguilar Anguera, Carme; Física Aplicada II
Liquid scintillation spectrometry is a fast competitive technique for the simultaneous evaluation of gross alpha and beta indexes. However, the implementation of this technique should not be considered as straightforward, and the pre-concentration methods to decrease the detection limit together with quenching and alpha, and beta crossover corrections should be carefully chosen according to the needs of the laboratory. Both aspects are being approached in this work as to find an easy and robust method for alpha/beta measurement in water samples, taking into account the quenching and alpha/beta crossover interferences effects. Results showed that most of the pre-concentration methods increased the quenching in the measurement, although HNO3 0.05 M points to be the best solution for preconcentration and redissolution of the sample as converges into low quenching and maximum recovery. Subsequently, in the measurement of water samples with different conductivities, the analysis of the raw counts to obtain gross alpha and beta indexes was carried out using different approaches to implement quenching and interference corrections. If quenching and salt content in the sample are relatively low, interference and quenching-efficiency corrections do not improve the accuracy of the results within the usual precision assumed for a result of gross alpha and beta index (25%). Special attention must be paid when corrections are applied to high quenched or saline samples and when alpha and beta activities values are different in several orders of magnitude.
Reducing Global Warming Potential in Cement Production: A Comparative Study of Slate and Marble Waste as Sustainable
(IOP Publishing, 2025) Silva Calderón-Morales, Bianca Rafaela; Costal, Glauber Zerbini; García Martínez, Antonio; Pineda Palomo, Paloma; García-Tenorio García-Balmaseda, Rafael; Estructuras de Edificación e Ingeniería del Terreno; Física Aplicada II; Construcciones Arquitectónicas I (ETSA)
This study evaluates the reduction of Global Warming Potential (GWP) in Portland cement production through the incorporation of industrial waste from marble and slate as supplementary cementitious materials. Partial clinker substitutions between 5% and 20% were analyzed, assessing mechanical performance through compressive strength tests and environmental impact using the Life Cycle Assessment (LCA) methodology. The results demonstrated that replacing 20% of clinker with waste led to significant reductions in CO2 emissions: 16.44% for marble and 15.72% for slate. Formulations with 10% and 15% substitution showed the best balance between mechanical performance and environmental impact, meeting regulatory resistance requirements. Transportation logistics proved crucial, with longer distances negatively impacting GWP. The study concludes that reusing these residues represents a viable strategy to mitigate the environmental impacts of the cement industry, aligning with the principles of the circular economy and promoting more sustainable construction practices.
Hybrid compton-PET imaging for ion-range verification: a preclinical study for proton, helium, and carbon therapy at HIT
(Springer Nature, 2025-08-26) Balibrea-Correa, Javier; Lerendegui-Marco, Jorge; Lerendegui Marco, Jorge; Morell, Sergio; Guerrero Sánchez, Carlos; Rodríguez González, María Teresa; Jiménez Ramos, María del Carmen; Quesada Molina, José Manuel; Bauer, Julia; Brons, Stephan; Domingo-Pardo, César; Física Aplicada II; Física Atómica, Molecular y Nuclear; European Union (UE); Ministerio de Ciencia e Innovación (MICIN). España; Generalitat Valenciana; Generalitat Valenciana; Universidad de Sevilla
Enhanced-accuracy ion-range verification in real time shall enable a significant step forward in the use of therapeutic ion beams. Positron-emission tomography (PET) and prompt-gamma imaging (PGI) are two of the most promising and researched methodologies, both of them with their own advantages and challenges. Thus far, both of them have been explored for ion-range verification in an independent way. However, the simultaneous combination of PET and PGI within the same imaging framework may open-up the possibility to exploit more efficiently all radiative emissions excited in the tissue by the ion beam. Here, we report on the first preclinical implementation of an hybrid PET-PGI imaging system, hereby exploring its performance over several ion beam species (H, He and C), energies (55–275 MeV) and intensities (- ions/spot), which are representative of clinical conditions. The measurements were carried out using the pencil-beam scanning technique at the synchrotron accelerator of the heavy ion therapy center in Heidelberg utilizing an array of four Compton cameras in a twofold front-to-front configuration. The results demonstrate that the hybrid PET-PGI technique can be well suited for relatively low energies (55–155 MeV) and beams of protons. On the other hand, for heavier beams of helium and carbon ions at higher energies (155–275 MeV), range monitoring becomes more challenging owing to large backgrounds from additional nuclear processes. The experimental results are well understood on the basis of realistic Monte Carlo calculations, which show a satisfactory agreement with the measured data. This work can guide further upgrades of the hybrid PET-PGI system toward a clinical implementation of this innovative technique.
Analysis of corrosion by speckle polarimetry
(MDPI, 2025-08-10) Gascón Latasa, Francisco; Rodríguez Ordóñez, Jorge; Bayón Rojo, Ana Isabel; Nieves Pavón, Francisco José; Salazar Bloise, Félix José; Física Aplicada II; Universidad Politécnica de Madrid (UPM); TEP130: Arquitectura, Patrimonio y Sostenibilidad: Acústica, Iluminación, Óptica y Energía
One of the most common problems in material engineering is the appearance of corrosion. For this reason, numerous efforts are underway to design materials that are resistant to this damage. In the same context, the diagnosis of corrosion is also of great interest since its detection reveals the real state of a structure. This article is focused on the latter. The purpose of the presented study is to provide a simple optical methodology to analyze the corrosion process and its evolution by means of a non-destructive method based on changes in the polarization state of the speckle patterns. To carry this out, two experimental arrangements with different wavelengths are proposed: one in the far field and another in the near field. The samples are first subjected to accelerated acid corrosion in the laboratory, and then, the degree of corrosion is quantitatively analyzed using the proposed technique. Moreover, in order to ensure that the acid attack on the samples is uniform (generalized corrosion), a detailed study is performed on the specimen surfaces via Raman spectroscopy. The results obtained show the ranges of applicability of both setups and their limits for studying corrosion.
The Effects of High-Energy Carbon Co-Doping on IMB-CNM LGAD Fabrication and Performance
(MDPI, 2025-09-06) Villegas, Jairo; Dougados, Florent; Torres Muñoz, Carmen; Fernandez-Martinez, Pablo; Jiménez Ramos, María del Carmen; Hidalgo, Salvador; Física Aplicada II; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Union; Universidad de Sevilla; Junta de Andalucía
Over the past few years, Low-Gain Avalanche Detectors (LGADs) have demonstrated excellent timing performance, showing great potential for use in 4D tracking of high-energy charged particles. Carbon co-doping is a key factor for enhancing LGAD performance, which are detectors with intrinsic amplification, in harsh radiation environments. This work presents a broad pre-irradiation characterization of the latest carbon-co-implanted (or carbonated) LGADs fabricated at IMB-CNM. The results indicate that the addition of carbon reduces the nominal gain of the devices compared with non-carbonated detectors. Furthermore, a comprehensive study is presented on how carbon co-implantation can either enhance or suppress the diffusion of the multiplication layer during LGAD fabrication, depending on the device structure and fabrication parameters.
Microbial Remineralization Is a Depth-Varying Contributor to Particle Flux Attenuation in the Southern Ocean
(American Geophysical Union, 2025) Petiteau, Louis; Boyd, P. W.; Le Moigne, Frederic; Villa Alfageme, María; Vioque Romero, Ignacio; Laurenceau-Cornec, Emmanuel; Baker, Katherine B.; Lacour, L.; Rohr, Tyler; Strzepek, Robert F.; Bressac, Matthieu; Física Aplicada II; Gobierno de Australia; Australian Research Council; CSIRO Marine National Facility (MNF)
The biological carbon pump contributes to set the magnitude of carbon sequestration in the oceans' interior. Estimating the relative contribution of microbial versus zooplankton-mediated processes to particulate organic carbon (POC) flux attenuation provides insights into how this pump functions. Our study took place during the high productivity summer period in the Subantarctic and Polar Front Zone. In the upper mesopelagic (i.e., 180–300 m depth), we concurrently measured the downward POC flux, particle size and morphology, microbial remineralization rates and estimated size-specific sinking velocities. These concomitant measurements revealed two different export systems, dominated by fecal material in the Subantarctic, and phyto-aggregates in polar waters. These two systems were characterized by similar low particle sinking velocities (∼10 m d−1), while microbial remineralization rates differed by an order of magnitude. Higher microbial remineralization rates in the Subantarctic (0.11 d−1), compared to polar waters (0.04 d−1), were likely driven by the confounding effect of temperature and particle characteristics. Despite this difference in microbial remineralization rates, these two export systems were characterized by relatively similar transfer efficiencies, suggesting that microbes had differing influences. A comparison of microbially mediated (i.e., scaled using observed remineralization rates) with total POC flux attenuation (i.e., driven by the dual impact of microbes and flux-feeders) revealed a higher microbial contribution to the flux attenuation in the upper mesopelagic of the subantarctic compared to the polar region. This deconstruction of the flux attenuation revealed an increasing influence of microbes on POC degradation with depth to become the predominant actor in the lower mesopelagic.
Echo analysis in Iberian bullfighting arenas through objective parameters and acoustic simulation
(MDPI, 2025-07-12) Girón Borrero, Sara; Martín Castizo, Manuel; Galindo del Pozo, Miguel; Física Aplicada II; TEP130: Arquitectura, Patrimonio y Sostenibilidad: Acústica, Iluminación, Óptica y Energía
The existence of echoes in an acoustic event can ruin the capture of a spoken message and the perception of a piece of music. Likewise, in the performers’ area, clear hearing is essential for the coordination and execution of the ensemble. Bullrings are buildings with a circular plan in which echo-encouraging focalisations can occur. Since bullrings lack a roof, the density of reflections is lower than that in a closed area, and therefore strong isolated reflections perceived by the audience as an echo can be created. In this work, calculations of the echo parameter (Echo Criterion EK) and inspection of impulse responses and energy decay curves are obtained in an on-site measurement campaign in the audience zones and in arena areas where the EK parameter exceeds the thresholds. To this end, four bullrings very emblematic of the Iberian Peninsula together with a very prominent Roman amphitheatre in a relatively good state of conservation in the Roman province of Hispania comprise the study cases. Experimental results of the EK parameter and from acoustic simulation in two of the bullrings present good concordance and show that there is no echo for music in any of the venues in the spectator zones and that the most critical area is when source and receiver are both in the arena, where even double and triple echoes appear.
First Tests of an Opto-Electro-Mechanical System for 2D Dose Analysis in Low Energy Proton Irradiated Films
(IEEE, 2025) Mena, S.; Karkour, N.; Alaphilippe, V.; Crepin, D.; Jiménez Ramos, María del Carmen; García López, Francisco Javier; Espino Navas, José Manuel; Pascual-Álvarez, D.; Riera-Llobet, C.; Muñoz-Berbel, X.; Guirado, G.; Gibelin, L.; Linget, D.; Guardiola, C.; Física Aplicada II; Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla; Generalitat de Catalunya; European Union (UE)
This work presents a 2D dosimetry analysis with a new micro-opto-electro-mechanical system of radiochromic films irradiated with a low energy proton beam. The new system is based on a 5× 10 matrix of photodetectors controlled by both an in-house electronic circuit and a graphical user interface, which allows direct optical density measurements. We have investigated the performance of this 2D readout system using Gafchromic EBT3 films. The results were compared with those obtained using a standard analysis method based on a flat-bed scanner, and the results showed the feasibility of this system for 2D dose map evaluation. To the best of the authors’ knowledge, this is the first time that a two-dimensional micro-opto-electro-mechanical system has been used to analyze radiochromic films irradiated with low-energy protons. We intend to develop a portable 2D dosimetry tool that provides dose maps to speed up the reading of radiochromic films in radiotherapy.
Performance of SiC Diodes at Very High Doses of Low-Energy Proton Beams Under FLASH Conditions
(IEEE, 2025) Jiménez Ramos, María del Carmen; Torres-Muñoz, Carmen; García López, Francisco Javier; Barroso-Molina, Diego; Guardiola, Consuelo; Fleta, Celeste; Física Aplicada II; Física Atómica, Molecular y Nuclear; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE); Universidad de Sevilla; Fundación LaCaixa
FLASH therapy has emerged as a promising radiotherapy technique, minimizing damage to healthy tissues while maintaining effective tumor control. Achieving FLASH conditions requires dose rates exceeding 40 Gy/s, but conventional dosimetry systems fail under these conditions. Recently, IMB-CNM (CSIC) developed SiC p-n diodes with 30 μm diameter and 3 μm thickness, specifically designed for FLASH radiotherapy. This study investigates their response to low-energy UHDR proton beams after high and ultra-high accumulated doses for the first time. Experiments were performed in the 3 MV tandem accelerator at CNA using 1 MeV and 2 MeV protons with a pulsed beam system, achieving mean dose rates of 10 kGy/s, dose-per-pulse of 5.6 Gy, and dose rate within the pulse of 4.6 MGy/s. Ion pulses were characterized using a Faraday Cup and Rutherford Backscattering Spectrometry (RBS). Two SiC diodes were studied: one pre-irradiated with 3.6 MGy for extreme applications and another for early irradiation stages. The pre-irradiated diode showed a sensitivity decrease of -1.34 %/kGy up to 750 kGy, stabilizing within 7 % response variation up to 4.5 MGy. The response remained linear within 10 % at mean dose rate up to 5 kGy/s for 2 MeV protons, demonstrating the feasibility of this technology for FLASH applications.
Particle Export Fluxes in the Southern Ocean: Importance of Nonheterotrophic Processes in POC Flux Attenuation
(AGU, 2025-06-29) Le Moigne, Frédéric; Pabortsava, Katsiaryna; Villa Alfageme, María; Briggs, Nathan; Baker, Chelsy A.; Bourman, Heather A.; English, Chance J.; Blackbird, Sabena; Henson, Stephanie A.; Venables, Hugh; Carlson, Craig A.; Moore, C. Mark; Williams, Jack; Martin, Adrian P.; Física Aplicada II
The ocean contributes to regulating atmospheric CO2 levels via the biological carbon pump (BCP). One critical aspect of the BCP is the depth at which sinking particulate organic carbon (POC) remineralizes in the mesopelagic zone (200–1,000 m). In the Southern Ocean, the circulation is such that the products generated from POC remineralization may have drastically different fates depending on (a) the latitude at which sinking particulate material is produced and (b) the depth at which its remineralization occurs. Here, we assess latitudinal and depth variations of POC export marine aggregate abundance and composition in the Southeast Pacific sector of the Southern Ocean. We show changes in flux attenuation depth horizons in the upper mesopelagic in the subantarctic zone. These correspond to rapid particle accumulation below the depth of the euphotic zone followed by abrupt export. We believe that such rapid changes may be linked to diatom life cycles, including resting cell and spore formation and resulting changes in particle sinking velocities rather than attenuation due to heterotrophic degradation or solubilization in the upper mesopelagic zone. We further discuss the occurrence of such features in the Southern Ocean and at the global scale. Our results highlight the importance of alternative flux attenuation processes, such as sudden changes in particles sinking velocities, in explaining variability in organic carbon sequestration by the ocean's BCP.
Transverse vibration of an axially compressed bar with dry friction at its ends
(Elsevier, 2025-08) Nieves Pavón, Francisco José; Bayón Rojo, Ana Isabel; Salazar Bloise, Félix José; Gascón Latasa, Francisco; Física Aplicada II; TEP130: Arquitectura, Patrimonio y Sostenibilidad: Acústica, Iluminación, Óptica y Energía
The transverse vibration of a bar is studied by applying the Bernoulli-Euler beam theory. The bar is placed between the platens of a hydraulic press that applies compressive stress. When the bar vibrates, its ends slide over the platens with dry friction. Boundary conditions appropriate to the existence of friction are proposed. Once the homogeneous equation of motion is solved analytically, a particular solution is obtained through elementary trigonometric series. The sum of these solutions provides the general solution that shows the movement of all the bar points. The movement is divided into successive stages. The displacement of the bar points as a function of time is calculated numerically. It is demonstrated that there is a sudden change in the shape of vibrating when a specific number of semi-oscillations is reached, going from a behaviour of sliding ends to another of fixed ends. Criteria are proposed to estimate the circumstances in which the partial stop of the vibration occurs, as well as a change in the vibration mode and its frequency.
Monolithically-Integrated Bandpass Filters Using Capacitively-Loaded Intertwined Helical Resonators
(Institute of Electrical and Electronics Engineers, 2025) Medrán Del Rio, José Luis; Fernández Prieto, Armando; Martel Villagrán, Jesús; Elmiger, Christian; Psychogiou, Dimitra; Electrónica y Electromagnetismo; Física Aplicada II; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Science Foundation Ireland (SFI); Ministerio de Educación. España
This paper presents a novel compact 3D bandpass filter (BPF) concept based on new classes of intertwined helical resonators. The concept is demonstrated by three unique RF filter architectures: a second-order single-band BPF, a second-order dual-band BPF, and a differential single-band BPF. The filter designs are based on coupled-resonator theory, and their implementation is performed using stereolithography apparatus (SLA) 3D printing to create monolithic, screwless structures with ultra-low weight (20-65 gr) and minimal loss. The proposed intertwined helical resonator-based BPF concept, which enables designs with compact size and large fractional bandwidth (FBW) with transmission zeroes (TZ), has been experimentally validated. Manufactured prototypes have demonstrated the following RF performance: single-band BPF: center frequency of 1.08 GHz, 3 dB FBW of 15.5%, and insertion loss (IL) of 0.08 dB; dual-band BPF: passbands centered at 0.84 GHz and 1.53 GHz, with a 3 dB FBW of 19% and 6.5% and IL of 0.2 dB and 0.55 dB, respectively; differential single-band BPF: center frequency of 0.78 GHz, 3 dB FBW of 4%, and IL of 0.87 dB. To the best of the author's knowledge, this work is the first approach to 3D-printed differential BPFs.
Evaluation of the physical and mechanical behaviour of rammed earth by incorporation of recycled glass
(Elsevier, 2025) Canivell, Jacinto; Martín del Río, Juan Jesús; Solís Muñiz, Mario; Rodríguez Mariscal, José Daniel; Flores Alés, Vicente; Pontiga Romero, Francisco de Paula; Construcciones Arquitectónicas II (ETSIE); Mecánica de Medios Continuos y Teoría de Estructuras; Física Aplicada II; TEP211: Conservación Preventiva del Patrimonio Construido; TEP198: Materiales y Construcción; FQM253: Electrohidrodinámica y Medios Granulares Cohesivos
Compacted soil walls provide environmental benefits due to their low impact and embodied energy. Although their mechanical strength is lower than other materials, they meet safety requirements. Current trends promote circular economy solutions, such as waste reuse. This study assesses recycled glass in lime- and cement-stabilized rammed earth as a replacement for natural sand to enhance waste management and soil properties. Ultrasonic inspection confirms increased compressive strength and density, especially in cement-stabilized mixtures. Statistical analysis reveals a direct correlation between crushed glass content and improved properties. The optimal replacement rate is 75% for lime and 100% for cement. The superior performance in cement-stabilized samples is due to a pozzolanic reaction absent in lime mixtures. Both binders show significant reductions in thermal conductivity, improving energy efficiency without compromising structural integrity. Ultrasound proves reliable for predicting compressive strength and stiffness, supporting the viability of this approach. The incorporation of recycled glass in compacted soil offers a sustainable construction alternative, balancing environmental benefits with enhanced mechanical and thermal performance.
The acoustics of 16th-century Jesuit churches in Andalusia: Latin cross plans following the model of Il Gesù
(Elsevier, 2025-09-05) León Rodríguez, Jesús; Alberdi Causse, Enedina; Bustamante, Pedro; Galindo del Pozo, Miguel; Construcciones Arquitectónicas I (ETSA); Física Aplicada II; TEP999: HABITAE: Habitabilidad, Acondicionamiento y Energía en Arquitectura; TEP130: Arquitectura, Patrimonio y Sostenibilidad: Acústica, Iluminación, Óptica y Energía
Following the Council of Trent, profound changes were observed in ecclesiastical architectural space as a result of the new spirit infused into the Catholic Church by the Counter-Reformation. The Jesuit mother church, Il Gesù, contributed to the consolidation of the model of the single nave church, eliminating the aisles and reducing the size of the transept. This architectural model was disseminated in step with the expansion of the Society. The churches of Santa Catalina (Cordoba), La Anunciación (Seville), and La Encarnación (Marchena, Seville) provide emblematic examples of the model adopted by the Society of Jesus in the second half of the 16th century in Andalusia. The typological, geometric, and material similarities displayed by these churches enable a common analysis of the sound field, to be carried out through in-situ acoustic measurements and simulations. The study of different source positions in similar models enables the determination of the optimal source and receiver configurations. It was found that the position on the main altar, coinciding with the position of the priest in the Tridentine rite, does not facilitate the perception of the sound field, except in the positions in the high tribunes. When the source is under the dome of the transept, the sound field evaluation is more favourable. Conversely, a comparative analysis of churches considered to be ’twins’, St Catalina and La Anunciación, has shown the impact that the interior cladding of these spaces has on the perception of their sound field.
Test of the physical significance of Bell non-locality
(Nature Research, 2025) Vieira, Carlos; Ramanathan, Ravishankar; Cabello Quintero, Adán
Loophole-free violations of Bell inequalities imply that at least one of the assumptions behind local hidden-variable theories must fail. Here, we show that, if only one fails, then it has to fail completely, therefore excluding models that partially constrain freedom of choice or allow for partial retrocausal influences, or allow partial instantaneous actions at a distance. Specifically, we show that (i) any hidden-variable theory with outcome independence (OI) and arbitrary joint relaxation of measurement independence (MI) and parameter independence (PI) can be experimentally excluded in a Bell-like experiment with many settings on high-dimensional entangled states, and (ii) any hidden-variable theory with MI, PI and arbitrary relaxation of OI can be excluded in a Bell-like experiment with many settings on qubit-qubit entangled states.
Environmentally friendly tailor-made oleo-dispersions of electrospun cellulose acetate propionate nanostructures in castor oil for lubricant applications
(Elsevier, 2025-02) Martín Alfonso, Manuel Antonio; Rubio Valle, José Fernando; Hinestroza, Juan Paulo; Martín Alfonso, José Enrique; Franco Gómez, José María; Física Aplicada II; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Junta de Andalucía
The aim of this work is to find an alternative lubricating grease formulation that can be produced from renewable and biodegradable sources with minimal risks to human health and the environment. We used a castor oil and electrospun cellulose acetate propionate (CAp) as raw materials. We hypothesized that the acetyl and propionyl groups could provide an adequate chemical compatibility with the castor oil and that the electrospun nanostructures could enable improved physical stability by creating a variety of morphologies allowing the tailoring of the rheological and tribological properties of the resulting greases. The experimental results show that the use of electrospun CAp nanostructures can indeed yield physically stable formulations, even when used at low concentrations (3 wt%). The resulting dispersions went through structural transitions due to changes in the thickener morphologies and/or concentration, as shown by oscillatory rheology, oil holding capacity, tackiness, and lubrication performance in metal–metal contact. We found that the formulations, containing smooth or porous CAp nanofibers, at 5 wt% as a thickener, possess suitable rheological and tribological properties with a performance comparable to that of traditional lithium lubricating greases.
Comparison of the performance of the Quantulus GCT 6220 and the Quantulus 1220 for the determination of 55Fe and 63Ni
(Elsevier, 2025-08) García León, José Luis; García León, Manuel; Manjón Collado, Guillermo; Física Atómica, Molecular y Nuclear; Física Aplicada II; Gobierno de España; Consejo de Seguridad Nuclear; RNM138: Física Nuclear Aplicada
An experimental study of the response of the newer Quantulus GTC 6220 liquid scintillation spectrometer has been conducted with the objective of determining the performance of this counter for the determination of 55Fe and 63Ni in the environment. Its response has been compared to that of the well-established Quantulus 1220. For this, Guard Compensation Technology (GCT) was used to reduce the Lower Limit of Detection (LLD in what follows). Two scintillation cocktails, Hidex ProSafe HC+ and Revvity OptiPhase HiSafe 3 were compared in this work. The parameters employed for this assessment were background count rate, counting efficiency, and LLD.
Experimental quantum advantage in the odd-cycle game
(American Physical Society, 2025-02-21) Drmota, Peter; Main, Dougal; Ainley, Ellis; Agrawal, Ayush; Araneda, Gabriel; Nadlinger, David P.; Nichol, B. C.; Srinivas, Raghavendra; Cabello Quintero, Adán; Lucas, D. M.; Física Aplicada II; FQM239: Fundamentos de Mecánica Cuántica
Wereport the first experimental demonstration of the odd-cycle game. We entangle two atoms separated by ∼2 m, and the players use them to win the odd-cycle game with a probability ∼26σ above that allowed by the best classical strategy. The experiment implements the optimal quantum strategy, is free of loopholes, and achieves 97.8(3)% of the theoretical limit to the quantum winning probability. We perform the associated Bell test and measure a nonlocal content of 0.54(2)—the largest value for physically separate devices, free of the detection loophole, ever observed.
Estimating and computing Kronecker coefficients: a vector partition function approach
(2024) Mishna, Marni; Trandafir, Stefan; Natural Sciences and Engineering Research Council of Canada (NSERC)
We study the Kronecker coefficients gλ,µ,ν via a formula that was described by Mishna, Rosas and Sundaram (2018), in which the coefficients are expressed as a signed sum of vector partition function evaluations. In particular, we use this formula to determine formulas to evaluate, bound, and estimate gλ,µ,ν in terms of the lengths of the partitions λ, µ and ν. We describe a computational tool to compute Kronecker coefficients gλ,µ,ν with ℓ(µ) ≤ 2, ℓ(ν) ≤ 4, ℓ(λ) ≤ 8. We present a set of new vanishing conditions for the Kronecker coefficients by relating to the vanishing of the related atomic Kronecker coefficients, themselves given by a single vector partition function evaluation. We give a stable face of the Kronecker polyhedron for any positive integers m, n. Finally, we give upper bounds on both the atomic Kronecker coefficients and Kronecker coefficients.

Examinar

Envíos recientes