Modelado computacional del comportamiento hidrodinámico de elementos combustibles nucleares

La capacidad de generación de potencia de una central nuclear está limitada por el mecanismo de refrigeración del núcleo. El fenómeno termohidráulico denominado "Flujo Crítico de Calor" disminuye la capacidad de extracción de calor del sistema de refrigeración modificando abruptamente la transferencia térmica entre el elemento combustible y el refrigerante. En este trabajo se modela el comportamiento hidrodinámico de elementos combustibles nucleares con el objetivo de analizar lospatrones de turbulencia y mezclado entre subcanales. El modelado se centra alrededor de los separadoresde vainas combustibles y el efecto que estos tienen sobre el flujo. Para realizar estas simulaciones seutiliza la herramienta computacional denominada OpenFOAM.Publicado en: Mecánica Computacional vol. XXXV no.32Facultad de Ingenierí

RICORS2040 : The need for collaborative research in chronic kidney disease

Chronic kidney disease (CKD) is a silent and poorly known killer. The current concept of CKD is relatively young and uptake by the public, physicians and health authorities is not widespread. Physicians still confuse CKD with chronic kidney insufficiency or failure. For the wider public and health authorities, CKD evokes kidney replacement therapy (KRT). In Spain, the prevalence of KRT is 0.13%. Thus health authorities may consider CKD a non-issue: very few persons eventually need KRT and, for those in whom kidneys fail, the problem is 'solved' by dialysis or kidney transplantation. However, KRT is the tip of the iceberg in the burden of CKD. The main burden of CKD is accelerated ageing and premature death. The cut-off points for kidney function and kidney damage indexes that define CKD also mark an increased risk for all-cause premature death. CKD is the most prevalent risk factor for lethal coronavirus disease 2019 (COVID-19) and the factor that most increases the risk of death in COVID-19, after old age. Men and women undergoing KRT still have an annual mortality that is 10- to 100-fold higher than similar-age peers, and life expectancy is shortened by ~40 years for young persons on dialysis and by 15 years for young persons with a functioning kidney graft. CKD is expected to become the fifth greatest global cause of death by 2040 and the second greatest cause of death in Spain before the end of the century, a time when one in four Spaniards will have CKD. However, by 2022, CKD will become the only top-15 global predicted cause of death that is not supported by a dedicated well-funded Centres for Biomedical Research (CIBER) network structure in Spain. Realizing the underestimation of the CKD burden of disease by health authorities, the Decade of the Kidney initiative for 2020-2030 was launched by the American Association of Kidney Patients and the European Kidney Health Alliance. Leading Spanish kidney researchers grouped in the kidney collaborative research network Red de Investigación Renal have now applied for the Redes de Investigación Cooperativa Orientadas a Resultados en Salud (RICORS) call for collaborative research in Spain with the support of the Spanish Society of Nephrology, Federación Nacional de Asociaciones para la Lucha Contra las Enfermedades del Riñón and ONT: RICORS2040 aims to prevent the dire predictions for the global 2040 burden of CKD from becoming true

Atmospheric Degradation of CH₂C(CH₃)C(O)OCH₃ Initiated by OH Radicals: Mechanistic Study and Quantification of CH₃C(O)C(O)OCH₃ in NO_<i>x</i> Free Air

The product distribution of the gas-phase reaction of OH radicals with methyl methacrylate (CH₂C­(CH₃)­C­(O)­OCH₃, MMA) in the absence of NO_<i>x</i> was studied at 298 K and atmospheric pressure of air. The experiments were performed in a Teflon chamber using solid-phase microextraction (SPME) with GC–MS and GC–FID for product identification and quantification, respectively. In the absence of NO<i>_x</i>, methyl pyruvate (CH₃C­(O)­C­(O)­OCH₃) was identified with a yield of 76 ± 13% in accordance with the decomposition of the 1,2-hydroxyalkoxy radicals formed. In addition, a detailed quantum chemical study of the degradation of MMA was performed by density functional theory (DFT) methods using the MPWB1K functional. This calculation suggests that formation of methyl pyruvate, from C1–C2 scission of 1,2-hydroxyalkoxy radical, is kinetically and thermodynamically the most favorable reaction path taking into account the electronic properties of reaction intermediates and transition states. The difference observed on the degradation mechanism of MMA in the presence and absence of NO<i>_x</i> was explained in terms of the associated thermochemistry. Furthermore, this study propose that reaction between peroxy radical (RO₂^•) and hydroxyl radical (OH) became relevant at NO<i>_x</i>-free environments. This statement is in agreement with recent studies concerning small peroxy radicals such as CH₃OO^•

Atmospheric Oxidation of Vinyl and Allyl Acetate: Product Distribution and Mechanisms of the OH-Initiated Degradation in the Presence and Absence of NO_<i>x</i>

The products formed from the reactions of OH radicals with vinyl acetate and allyl acetate have been studied in a 1080 L quartz-glass chamber in the presence and absence of NO_<i>x</i> using in situ FTIR spectroscopy to monitor the reactant decay and product formation. The yields of the primary products formed in the reaction of OH with vinyl acetate were: formic acetic anhydride (84 ± 11)%; acetic acid (18 ± 3)% and formaldehyde (99 ± 15)% in the presence of NO_<i>x</i> and formic acetic anhydride (28 ± 5)%; acetic acid (87 ± 12)% and formaldehyde (52 ± 8)% in the absence of NO_<i>x</i>. For the reaction of OH with allyl acetate the yields of the identified products were: acetoxyacetaldehyde (96 ± 15)% and formaldehyde (90 ± 12)% in the presence of NO_<i>x</i> and acetoxyacetaldehyde (26 ± 4)% and formaldehyde (12 ± 3)% in the absence of NO_<i>x</i>. The present results indicate that in the absence of NO_<i>x</i> the main fate of the 1,2-hydroxyalkoxy radicals formed after addition of OH to the double bond in the compounds is, in the case of vinyl acetate, an α-ester rearrangement to produce acetic acid and CH₂(OH)­CO^• radicals and in the case of allyl acetate reaction of the radical with O₂ to form acetic acid 3-hydroxy-2-oxo-propyl ester (CH₃C­(O)­OCH₂C­(O)­CH₂OH). In contrast, in the presence of NO_<i>x</i> the main reaction pathway for the 1,2-hydroxyalkoxy radicals is decomposition. The results are compared with the available literature data and implications for the atmospheric chemistry of vinyl and allyl acetate are assessed

Mechanism and Product Distribution of the O₃‑Initiated Degradation of (<i>E</i>)‑2-Heptenal, (<i>E</i>)‑2-Octenal, and (<i>E</i>)‑2-Nonenal

The O₃-molecule initiated degradation of three 2-alkenals (<i>E</i>)-2-heptenal, (<i>E</i>)-2-octenal, and (<i>E</i>)-2-nonenal has been investigated in a 1080 L quartz-glass environmental chamber at 298 ± 2 K and atmospheric pressure of synthetic air using <i>in situ</i> FTIR spectroscopy to monitor the reactants and products. The experiments were performed in the absence of an OH scavenger. The molar yields of the primary products formed were glyoxal (49 ± 4) % and pentanal (34 ± 3) % from the reaction of (<i>E</i>)-2-heptenal with O₃, glyoxal (41 ± 3) % and hexanal (39 ± 3) % from the reaction of (<i>E</i>)-2-octenal with O₃, and glyoxal (45 ± 3) % and heptanal (46 ± 3) % from the reaction of (<i>E</i>)-2-nonenal with O₃. The residual bands in the infrared product spectra for each of the studied reactions are attributed to 2-oxoaldehyde compounds. Based on the observed products, a general mechanism for the ozonolysis reaction of long chain unsaturated aldehydes is proposed, and the results are compared with the available literature data

Atmospheric Sink of (<i>E</i>)‑3-Hexen-1-ol, (<i>Z</i>)‑3-Hepten-1-ol, and (<i>Z</i>)‑3-Octen-1-ol: Rate Coefficients and Mechanisms of the OH-Radical Initiated Degradation

A kinetic study of the gas-phase reactions of OH radicals with three unsaturated biogenic alcohols, (<i>E</i>)-3-hexen-1-ol, (<i>Z</i>)-3-hepten-1-ol, and (<i>Z</i>)-3-octen-1-ol, has been performed. The rate coefficients obtained are (in units of 10^–10 cm³ molecule^–1 s^–1) <i>k</i>₁ (OH + (<i>E</i>)-CH₂(OH)­CH₂CHCHCH₂CH₃) = (1.14 ± 0.14), <i>k</i>₂ (OH + (<i>Z</i>)-CH₂(OH)­CH₂CHCHCH₂CH₂CH₃) = (1.28 ± 0.23), and <i>k</i>₃ (OH + (<i>Z</i>)-CH₂(OH)­CH₂CHCHCH₂CH₂CH₂CH₃) = (1.49 ± 0.35). In addition, a product study on the reactions of OH with (<i>E</i>)-3-hexen-1-ol and (<i>Z</i>)-3-hepten-1-ol is reported. All the experiments were performed at (298 ± 2) K and 1 atm of NO_<i>x</i>-free air in a 1080 L photoreactor with in situ FTIR detection of organics. This work constitutes the first kinetic study of the reactions of OH radicals with (<i>Z</i>)-3-hepten-1-ol and (<i>Z</i>)-3-octen-1-ol as well as the first determination of the fate of the hydroxy alkoxy radicals formed in the title reactions. An analysis of the available rates of addition of OH and Cl to the double bond of different unsaturated alcohols at 298 K has shown that they can be related by the expression log <i>k</i>_OH = (0.29 ± 0.04) log <i>k</i>_Cl – 10.8. The atmospheric lifetimes of the alcohols studies were estimated to be around 1 h for reaction with OH radicals. The products formed in the title reactions are mainly carbonylic compounds that can contribute to the formation of ozone and PANs-type compounds in the troposphere

Eye gaze as a biomarker in the recognition of autism spectrum disorder using virtual reality and machine learning: A proof of concept for diagnosis

[EN] The core symptoms of autism spectrum disorder (ASD) mainly relate to social communication and interactions. ASD assessment involves expert observations in neutral settings, which introduces limitations and biases related to lack of objectivity and does not capture performance in real-world settings. To overcome these limitations,advances in technologies (e.g., virtual reality) and sensors (e.g., eye-tracking tools) have been used to create realistic simulated environments and track eye movements, enriching assessments with more objective data than can be obtained via traditional measures. This study aimed to distinguish between autistic and typically developing children using visual attention behaviors through an eye-tracking paradigm in a virtual environment as a measure of attunement to and extraction of socially relevant information. The 55 children participated. Autistic children presented a higher number of frames, both overall and per scenario, and showed higher visual preferences for adults over children, as well as specific preferences for adults¿ rather than children¿s faces on which looked more at bodies. A set of multivariate supervised machine learning models were developed using recursive feature selection to recognize ASD based on extracted eye gaze features. The models achieved up to 86% accuracy (sensitivity = 91%) in recognizing autistic children. Our results should be taken as preliminary due to the relatively small sample size and the lack of an external replication dataset. However, to our knowledge, this constitutes a first proof of concept in the combined use of virtual reality, eye-tracking tools, and machine learning for ASD recognition.Spanish Ministry of Economy, Industry, and Competitiveness-funded project "Immersive Virtual Environment for the Evaluation and Training of Children with Autism Spectrum Disorder: T Room, Grant/Award Number: IDI20170912Alcañiz Raya, ML.; Chicchi-Giglioli, IA.; Carrasco-Ribelles, LA.; Marín-Morales, J.; Minissi, ME.; Teruel-Garcia, G.; Sirera, M.... (2022). Eye gaze as a biomarker in the recognition of autism spectrum disorder using virtual reality and machine learning: A proof of concept for diagnosis. Autism Research. 15(1):131-145. https://doi.org/10.1002/aur.2636S13114515