Stochastic computer experiments of the thermodynamic irreversibility of bulk nanobubbles in supersaturated and weak gas-liquid solutions.

Spontaneous gas-bubble nucleation in weak gas-liquid solutions has been a challenging topic in theory, experimentation, and computer simulations. In analogy with recent advances in crystallization and droplet formation studies, the diffusive-shielding stabilization and thermodynamic irreversibility of bulk nanobubble (bNB) mechanisms are revisited and deployed to characterize nucleation processes in a stochastic framework of computer experiments using the large-scale atomic/molecular massively parallel simulator code. Theoretical bases, assumptions, and limitations underlying the irreversibility hypothesis of bNBs, and their computational counterparts, are extensively described and illustrated. In essence, it is established that the irreversibility hypothesis can be numerically investigated by converging the system volume (due to the finiteness of interatomic forces) and the initial dissolved-gas concentration in the solution (due to the single-bNB limitation). Helium nucleation in liquid Pb17Li alloy is selected as a representative case study, where it exhibits typical characteristics of noble-gas/liquid-metal systems. The proposed framework lays down the bases on which the stability of gas-bNBs in weak and supersaturated gas-liquid solutions can be inferred and explained from a novel perspective. In essence, it stochastically marches toward a unique irreversible state along out-of-equilibrium nucleation/growth trajectories. Moreover, it does not attempt to characterize the interface or any interface-related properties, neither theoretically nor computationally. It was concluded that bNBs of a few tens of He-atoms are irreversible when dissolved-He concentrations in the weak gas-liquid solution are at least ∼50 and ∼105 mol m-3 at 600 and 1000 K (and ∼80 MPa), respectively, whereas classical molecular dynamics -estimated solubilities are at least two orders of magnitude smaller.

Anti-COVID-19 measures threaten our healthy body weight: Changes in sleep and external synchronizers of circadian clocks during confinement.

BACKGROUND & AIMS: Emergency measures in the face of the recent COVID-19 pandemic have been different among countries, although most have opted for confinement and restrictions on social contact. These measures have generated lifestyle changes with potential effects on individuals' health. The disturbances in daily routines due to confinement and remote work have impacted circadian rhythms and energy balance; however, the consequences of these disruptions have not been studied in depth. The objective was to evaluate the impact of 12-week confinement on body weight, considering changes in several external synchronizers of the biological clock. METHODS: The participants, 521 university students (16-35 years), responded to 52 questions oriented to determine light exposure, sleep patterns, sedentary lifestyle, and eating times. RESULTS: We found a reduction in sunlight exposure and sleep duration, an increment in sedentarism and screen exposure, and a delay in the timing of the main meals and sleep in the whole cohort. These behavioral changes were associated with a twofold increase in obesity. Subjects who increased their sedentary hours and shortened their sleep to a higher degree were those who gained more bodyweight. The most influential factors in body weight variation during confinement were sleep duration, physical activity (sedentarism), and light (timing of screen exposure). The mediation model explained 6% of the total body weight variation. CONCLUSIONS: Results support a significant impact of confinement on several external synchronizers of the biological clock and on body weight. Health-related recommendations during the pandemic must include behavioral recommendations to mitigate the adverse effects on the biological clock.

Valoración de la condición física mediante el senior fitness test y el índice de masa corporal en una muestra española de personas mayores de 80 años / Evaluation of physical fitness in spanish people over 80 years of age using the senior fitness test and the body mass index

La esperanza de vida se ha incrementado notablemente en las sociedades occidentales. El ejercicio físico adaptado a personas mayores es clave para conseguir un envejecimiento activo. Objetivos: El objetivo principal fue determinar los niveles de condición física con el Senior Fitness Test (SFT) en sujetos españoles, mayores de 80 años, activos e independientes, adscritos a un programa de Condición Física de Mayores (CFM) y compararlos con los valores estadounidenses de referencia del SFT. El objetivo secundario fue analizar los resultados de nuestra población distribuidos por sexo y edad. Material y método: Se realizó un estudio transversal en 162 participantes, (142 mujeres, 87%), a los que se les aplicó el SFT para evaluar su condición física y se les midió el Índice de Masa Corporal (IMC) para valorar su influencia sobre la condición física. Resultados: En el SFT, la muestra española presentó mejor desempeño en fuerza y agilidad y niveles más bajos en flexibilidad y resistencia que la población estadounidense de referencia. No se encontraron diferencias significativas entre sexos en la población española, excepto en la prueba de resistencia a favor de los hombres (p = 0,006). El grupo mayor de 85 años presentó resultados inferiores del IMC (p = 0,007), de la fuerza del tren superior (p = 0,01) y de la flexibilidad del tren inferior (p = 0,02). La media del IMC de la muestra estudiada fue superior a la media de la población estadounidense. Conclusiones: La muestra española es más fuerte y ágil, pero menos flexible y resistente que la población estadounidense de referencia. La capacidad funcional en nuestra población mayor de 80, es similar en ambos sexos

Life expectancy has increased significantly in western societies. Physical exercise adapted to the elderly is a key factor in achieving active ageing. Objectives: Main objective was to assess the functional fitness of active, independent, over 80 years of age, Spanish subjects enrolled in a Senior Physical Fitness program using the Senior Fitness Test (SFT), and to compare the results with the SFT reference intervals. The secondary objective was to analyse the sample’s results when distributed according to age and sex. Material and method: A transversal study was conducted in 162 participants (142 women, 87%). They were administered the SFT to determine their physical abilities and their BMI was calculated in order to find out its influence on their physical condition. Results: Our Spanish sample performed better in strength and agility but presented lower outcomes in endurance and flexibility when compared to the US target population. In the Spanish sample significant differences between the two sexes were only found in the resistance score, where men performed better than women, (p = 0.006). Participants over 85 presented lower results in BMI (p = 0,007), upper body strength (p = 0.01) and lower body flexibility (p = 0.02). The mean BMI of our sample was higher than that of the American population. Conclusions: The Spanish population is stronger and has more agility, but it’s also less flexible and has lower endurance when compared to the American population. The Fitness condition in our population > 80 is similar in men and women