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Low-cost and sustainable electrocatalytic approach for the direct synthesis of biodiesel from waste cooking oil
No full textBiodiesel is an environmentally friendly and biodegradable fuel that can be considered as one of the most promising alternatives to fossil fuels. In this study, the electro-assisted transesterification, by using a graphite pencil mine (PG) electrode, of Waste Cooking Oils (WCO) or frying oils was explored. A maximum Fatty Acid Methyl Esters (FAME) conversion of 96.8 % was obtained at room temperature, applied voltage of 30 V, an oil to methanol ratio of 1:25, and an electrolysis time of 150 min, without co-solvents or additional catalysts. When a nickel-coated PG (PG-Ni) electrode, prepared by cyclic voltammetry, the same yield was obtained in 120 min. The biodiesel quality was confirmed by Fourier Transform Infrared (FTIR), Nuclear Magnetic Resonance (1H NMR), and GAS Chromatography-Mass Spectroscopy (GC-MS), compiled with EN14214 specifications. The electrode retained over 95 % efficiency after 15 cycles, confirming its stability and reusability. The approach leverages waste valorization, reduces energy consumption, and avoids chemical waste, aligning with circular economy goals
Temperature Dependence of Resistivity and Noise in Electrodeposited Bismuth Samples for X-ray Transition-Edge Sensors
No full textA combination of gold and bismuth is commonly used as absorber for X-ray transition-edge sensors, due to high atomic numbers and, consequently large cross sections, and to their complementary thermal properties. Since Au conductivity dominates, especially at cryogenic temperatures, electrodeposited bismuth films have been grown over sputtered gold, so that bismuth forms a bridge on the gold fingers and, therefore, the conductivity contribution from the underlying Au layer can be removed. Resistance as a function of the temperature has been investigated for pristine and annealed samples, both with and without a dc magnetic field. A general behavior has been observed, thus evidencing three different zones. At high temperatures a metal regime, described in terms of a Fermi liquid model, is identified. In an intermediate temperature region, a hysteretic and irreversible insulating-type resistance is observed. While, at low temperatures a resistance plateau appears. To better understand the electrical conduction properties, noise measurements have been also performed. Two possible models have been considered to interpret experimental data in the intermediate temperature region: Fluctuation-Induced Tunneling and Quantum Interference Effects. The analysis here reported gives indication on the granular structure of the investigated films, which could be represented as random networks of tunneling junctions, where the nodes are the conducting pathways connecting different junctions. In these regions, temperature-induced intergranular processes could be effectively detected giving additional information on the prediction of the ultimate energy resolving capabilities of detectors with bismuth absorbers
OPNet: A deep-learning approach for estimating particulate matter’s oxidative potential from satellite imagery
No full textThe oxidative potential (OP) of particulate matter (PM) reflects its ability to trigger oxidative stress in the respiratory system and is increasingly recognised as a key metric for assessing PM toxicity. Concurrently, PM has gained importance as a health indicator, leading to its inclusion in European regulations. As OP is not routinely monitored at many sites, understanding exposure and related risks remains challenging. While satellite imagery is commonly used to estimate PM mass concentration, its application to OP has not yet been explored. We present a novel deep-learning-based approach employing satellite-based surface features for OP estimation, using both OPAA and OPDTT assays on 24-hour PM10 samples collected over five years in Grenoble (France). We propose OPNet, which consists of two parts: a deep backbone that extracts surface features from one satellite image, and a predictor estimating OPAA and OPDTT using the extracted features combined with contextual variables. The architecture is trained in two stages: in the domain-adaptive task, both are jointly trained to predict daily PM10 concentration, with the backbone initialised from weights from a general classification problem. In the domain-specific task, they are jointly updated to predict either OPAA or OPDTT, with the backbone initialised from the best weights obtained in the first stage. This approach explains up to 75% of the variance in OPAA and 58% in OPDTT when using both satellite imagery and auxiliary data. It offers a cost-effective solution to improve the estimation of OP, with implications for large-scale air quality monitoring and health impact assessments
Grazing-Incidence SEM Characterization of MoS2 Nanosheet Coatings Prepared by Liquid-Phase Exfoliation
No full textUltrathin two-dimensional (2D) coatings exhibit functional properties that are strongly defined by morphological features such as sheet edges, fracture sites, overlaps, folds, and local thickness variations, which are often difficult to resolve using conventional scanning electron microscopy (SEM) configurations. Here, we introduce a grazing-incidence SEM approach based on controlled sample tilting close to 90° for enhancing surface sensitivity and morphological feature detectability in ultrathin coatings. The method is proved on colloidal MoS2 nanosheet coatings prepared by liquid-phase exfoliation. Optical absorption spectroscopy confirms the presence of mono- and few-layer MoS2 nanosheets in the dispersion, confirming the ultrathin nature of the deposited coating. Compared to standard 0° imaging, grazing-incidence SEM reveals clearer boundaries and discontinuities. Quantitative Sobel-based image analysis supports these observations, showing an increase in edge density from 5.9% to 7.6% and in average gradient magnitude from 0.151 to 0.172 a.u. under grazing incidence, indicating a higher amount of retrievable morphological information. The proposed approach relies only on standard stage tilting and provides a broadly applicable framework for the surface-sensitive morphological characterization of ultrathin 2D coatings and thin films
Search for an eV-scale sterile neutrino with the first six detection units of KM3NeT/ORCA
No full textThe existence of an eV-scale sterile neutrino has been proposed to explain several
anomalous experimental results obtained over the course of the past 25 years. The first search
for such a sterile neutrino conducted with data from KM3NeT/ORCA — a water Cherenkov
neutrino telescope under construction at the bottom of the Mediterranean Sea — is reported
in this paper. GeV-scale atmospheric neutrino oscillations are measured by reconstructing the
energy and arrival direction of up-going neutrinos that have traversed the Earth. This study
is based on a data sample containing 5828 neutrino candidates collected with 6 detection
units (5% of the complete detector), corresponding to an exposure of 433 kton-years. From
the expected effect of an eV-scale sterile neutrino on the first νμ → ντ standard oscillation
maximum, simultaneous constraints are put on the magnitude of the Uμ4 and Uτ4 mixing
elements assuming Δm2
41 ≥ 1 eV2. The results are compatible with the absence of mixing
between active neutrinos and a sterile state, with |Uμ4|2 < 0.138 and |Uτ4|2 < 0.076 at a
90% confidence level. Such constraints are compatible with the results reported by other
long-baseline experiments, and indicate that with KM3NeT/ORCA it is possible to bring
crucial contributions to sterile neutrino searches in the coming years
Whipped and mixed warm clouds in the deep sea
No full textTurbulence is indispensable to redistribute nutrients for all life forms larger than microbial, on
land and in the ocean. Yet, the development of deep‐sea turbulence was not studied in three dimensions to date.
As a disproportionate laboratory, an array of nearly 3,000 high‐resolution temperature sensors had been
installed for three years on the flat 2,500‐m deep bottom of the Mediterranean Sea. The time series from the half‐
cubic hectometer mooring‐array allows for the creation of unique movies of deep‐sea water motions. Although
temperature differences are typically 0.001°C, variable convection‐turbulence is observed as expected from
geothermal heating through the flat seafloor. During about 40% of the time, an additional turbulence, 3 times
stronger in magnitude, is observed from slantwise advected warmer waters to pass in turbulent clouds. Besides
turbulent clouds and seafloor heating, movies also reveal weakly turbulent interfacial‐wave breakdown that
commonly occurs in the open ocean far away from boundarie
“SENSIBILI AI PROBLEMI DEL MONDO”: I VALDESI DOPO IL 1945 TRA EUROPEISMO, ECUMENISMO E BIPOLARISMO
No full textVerso quali orizzonti volse, quindi, il proprio sguardo il mondo valdese
all’indomani della Seconda guerra mondiale? E in che modo, con
quali priorità esso si sforzò di stare nei profondi cambiamenti occorsi sul
piano nazionale in quel frangente? Lo scavo archivistico e, in generale,
lo stimolo alla ricerca fornito dall’iniziativa confluita nella pubblicazione
del quarto e ultimo volume, curato da Paolo Naso, della Storia dei valdesi,
hanno perlomeno in parte contribuito a chiarire o ad aggiornare tali
questioni. Per cui è possibile individuare tre macro-aspetti
rispetto ai quali si è articolata la “politica estera” valdese, a ridosso della
fine e dopo la guerra, e attraverso la cui analisi si può quindi trarre un
quadro certamente più chiaro di come gli stessi valdesi abbiano interpretato
il loro essere «minoranza significativa» in quella fase storica:
l’europeismo, l’ecumenismo e il bipolarismo
Magneto-optical Kerr effect in pump-probe setups
No full textWe develop a general theoretical framework for computing the time-resolved magneto-optical Kerr effect in ultrafast pump-probe setups, formulated within the dynamical projective operatorial approach (DPOA) and its application to the generalized linear-response theory for pumped systems. Furthermore, we exploit this formalism to express the postpump optical conductivity—and consequently the Kerr rotation—in terms of the time-evolved single-particle density matrix (SPDM), providing a transparent and computationally efficient description of photoexcited multiband systems. This extension, in addition to its lower computational cost, has the advantage of allowing the inclusion of phenomenological damping. We illustrate the formalism using both (1) a two-band tight-binding model, which captures the essential physics of ultrafast spin-charge dynamics and the Kerr rotation and (2) weakly spin-polarized germanium, as a realistic playground with a complex band struc- ture. The results demonstrate that, by exploiting DPOA and/or its SPDM extension, one can reliably reproduce both the short-time features under the pump-pulse envelope and the long-time dynamics after excitation, offering a versatile framework for analyzing time-resolved magneto-optical Kerr effect experiments in complex materials. Moreover, this analysis clearly shows that the Kerr rotation can be used to deduce experimentally the relevant n-photon resonances for a given specific material
On the dynamics of antigen receptors on the B-cell membrane through a two-dimensional stochastic process
No full textB cells are important components of the adaptive immune system, responsible for {antibody} production and working as antigen-presenting cells. B cells display protein receptors on their membrane, {which} bind with foreign antigens and process them before presenting them to T cells. In this work, we present a stochastic process modeling the dynamics of such receptors on the B cell. The model consists of a two-dimensional birth-death process having linear transition rates, where and represent the number of free and occupied receptors, respectively. After determining the partial differential equation for the probability generating function of the process, we compute the main moments of the process, including the covariance. The transient and asymptotic behavior of the means of and is also studied. Throughout the paper, we provide insights into the biological significance of each parameter on the system's dynamics. In addition, we conduct a sensitivity analysis to assess how variations in the model parameters affect the first-order moments. Such analysis shows that minimal variations of the parameters representing the binding frequency of antigens and {B-cell} receptors, when happening in the initial instants of the process, result in noticeable alterations of the number of occupied receptors