Equilibration of Concentrated Hard Sphere Fluids

We report a systematic molecular dynamics study of the isochoric equilibration of hard-sphere fluids in their metastable regime close to the glass transition. The thermalization process starts with the system prepared in a non-equilibrium state with the desired final volume fraction {\phi} but with a prescribed non-equilibrium static structure factor S_0(k; {\phi}). The evolution of the {\alpha}- relaxation time {\tau}{\alpha} (k) and long-time self-diffusion coefficient DL as a function of the evolution time tw is then monitored for an array of volume fractions. For a given waiting time the plot of {\tau}{\alpha} (k; {\phi}, tw) as a function of {\phi} exhibits two regimes corresponding to samples that have fully equilibrated within this waiting time ({\phi} \leq {\phi}(c) (tw)), and to samples for which equilibration is not yet complete ({\phi} \geq {\phi}(c) (tw)). The crossover volume fraction {\phi}(c) (tw) increases with tw but seems to saturate to a value {\phi}(a) \equiv {\phi}(c) (tw \rightarrow \infty) \approx 0.582. We also find that the waiting time t^(eq)_w({\phi}) required to equilibrate a system grows faster than the corresponding equilibrium relaxation time, t^(eq)({\phi}) \approx 0.27 \times [{\tau}{\alpha} (k; {\phi})]^1.43, and that both characteristic times increase strongly as {\phi} approaches {\phi}^(a), thus suggesting that the measurement of equilibrium properties at and above {\phi}(a) is experimentally impossible

Twilight Mesospheric Clouds in Jezero as Observed by MEDA Radiation and Dust Sensor (RDS)

The Mars Environmental Dynamics Analyzer instrument, on board NASA's Mars 2020 Perseverance rover, includes a number of sensors to characterize the Martian atmosphere. One of these sensors is the Radiation and Dust Sensor (RDS) that measures the solar irradiance at different wavelengths and geometries. We analyzed the RDS observations made during twilight for the period between sol 71 and 492 of the mission (Ls 39°–262°, Mars Year 36) to characterize the clouds over the Perseverance rover site. Using the ratio between the irradiance at zenith at 450 and 750 nm, we inferred that the main constituent of the detected high-altitude aerosol layers was ice from Ls = 39°–150° (cloudy period), and dust from Ls 150°–262°. A total of 161 twilights were analyzed in the cloudy period using a radiative transfer code and we found: (a) signatures of clouds/hazes in the signals in 58% of the twilights; (b) most of the clouds had altitudes between 40 and 50 km, suggesting water ice composition, and had particle sizes between 0.6 and 2 µm; (c) the cloud activity at sunrise is slightly higher that at sunset, likely due to the differences in temperature; (d) the time period with more cloud detections and with the greatest cloud opacities is during Ls 120°–150°; and (e) a notable decrease in the cloud activity around aphelion, along with lower cloud altitudes and opacities. This decrease in cloud activity indicates lower concentrations of water vapor or cloud condensation nuclei (dust) around this period in the Martian mesosphere.This work has been funded by the Spanish Ministry of Economy and Competitiveness, through the projects no. ESP2014-54256-C4-1-R (also ESP2014-54256-C4-2-R, ESP2014-54256-C4-3-R, and ESP2014-54256-C4-4-R), Spanish Ministry of Science, Innovation and Universities, projects no. ESP2016-79612-C3-1-R (also ESP2016-79612-C3-2-R and ESP2016-79612-C3-3-R), Spanish Ministry of Science and Innovation/State Agency of Research (10.13039/501100011033), projects no. PID2021-126719OB-C41, ESP2016-80320-C2-1-R, RTI2018-098728-B-C31 (also RTI2018-098728-B-C32 and RTI2018-098728-B-C33), RTI2018-099825-B-C31. RH and ASL were supported by the Spanish project PID2019-109467GB-I00 funded by MCIN/AEI/10.13039/50110001103 and by Grupos Gobierno Vasco IT1742-22. The US co-authors performed their work under sponsorship from NASA’s Mars 2020 project, from the Game Changing Development programme within the Space Technology Mission Directorate and from the Human Exploration and Operations Directorate. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). G.M. acknowledges JPL funding from USRA Contract Number 1638782. ML is supported by contract 15-712 from Arizona State University and 1607215 from Caltech-JPL. A. V-R. is supported by the Comunidad de Madrid Project S2018/NMT-4291 (TEC2SPACE-CM)

Winds at the Mars 2020 Landing Site. 2. Wind Variability and Turbulence

Wind speeds measured by the Mars 2020 Perseverance rover in Jezero crater were fitted as a Weibull distribution. InSight wind data acquired in Elysium Planitia were also used to contextualize observations. Jezero winds were found to be much calmer on average than in previous landing sites, despite the intense aeolian activity observed. However, a great influence of turbulence and wave activity was observed in the wind speed variations, thus driving the probability of reaching the highest wind speeds at Jezero, instead of sustained winds driven by local, regional, or large-scale circulation. The power spectral density of wind speed fluctuations follows a power-law, whose slope deviates depending on the time of day from that predicted considering homogeneous and isotropic turbulence. Daytime wave activity is related to convection cells and smaller eddies in the boundary layer, advected over the crater. The signature of convection cells was also found during dust storm conditions, when prevailing winds were consistent with a tidal drive. Nighttime fluctuations were also intense, suggesting strong mechanical turbulence. Convective vortices were usually involved in rapid wind fluctuations and extreme winds, with variations peaking at 9.2 times the background winds. Transient high wind events by vortex-passages, turbulence, and wave activity could be driving aeolian activity at Jezero. We report the detection of a strong dust cloud of 0.75–1.5 km in length passing over the rover. The observed aeolian activity had major implications for instrumentation, with the wind sensor suffering damage throughout the mission, probably due to flying debris advected by winds.The authors acknowledge and thank the Mars 2020 team. The authors would like to thank Editors and two anonymous reviewers for their constructive reviews, which greatly improved this manuscript. This work is supported by the Spanish Ministry of Science and Innovation, under project RTI2018-098728-B-C31. The derived data presented in this work were processed in the DPS24PA system, which is supported by project no. DV2020-ATM-A01. Part of the research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). The UPV/EHU team is supported by Grant PID2019-109467GB-I00 funded by 1042 MCIN/AEI/10.13039/501100011033/ and by Grupos Gobierno Vasco IT1742-22

Near Surface Atmospheric Temperatures at Jezero From Mars 2020 MEDA Measurements

The Mars Environmental Dynamics Analyzer instrument on Mars 2020 has five Atmospheric Temperature Sensors at two altitudes (0.84 and 1.45 m) plus a Thermal InfraRed Sensor that measures temperatures on the surface and at ∼40 m. We analyze the measurements from these sensors to describe the evolution of temperatures in Jezero up to mission sol 400 (solar longitude LS = 13°–203°). The diurnal thermal cycle is characterized by a daytime convective period and a nocturnal stable atmosphere with a variable thermal inversion. We find a linear relationship between the daytime temperature fluctuations and the vertical thermal gradient with temperature fluctuations that peak at noon with typical values of 2.5 K at 1.45 m. In the late afternoon (∼17:00 Local True Solar Time), the atmosphere becomes vertically isothermal with vanishing fluctuations. We observe very small seasonal changes in air temperatures during the period analyzed. This is related to small changes in solar irradiation and dust opacity. However, we find significant changes in surface temperatures that are related to the variety of thermal inertias of the terrains explored along the traverse of Perseverance. These changes strongly influence the vertical thermal gradient, breaking the nighttime thermal inversion over terrains of high thermal inertia. We explore possible detections of atmospheric tides on near-surface temperatures and we examine variations in temperatures over timescales of a few sols that could be indicative of atmospheric waves affecting near-surface temperatures. We also discuss temperatures during a regional dust storm at LS = 153°–156° that simultaneously warmed the near surface atmosphere while cooling the surface.We are very grateful to the entire Mars 2020 science operations team. We would like to thank two anonymous reviewers for comments and suggestions that helped us to improve the quality of the manuscript. A. Munguira is supported by the grant PRE2020-092562 funded by MCIN/AEI/10.13039/501100011033 and by “ESF Investing in your future.” R. Hueso and A. Sánchez-Lavega are supported by Grant PID2019-109467GB-I00 funded by MCIN/AEI/10.13039/501100011033/and by Grupos Gobierno Vasco IT1742-22. US coauthors have been funded by NASA's STMD, HEOMD, and SMD. Part of the research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). B. Chide is supported by the Director's Postdoctoral Fellowship from the Los Alamos National Laboratory. M. Lemmon is supported by contract 15-712 from Arizona State University and 1607215 from Caltech-JPL. R. Lorenz was supported by JPL contract 1655893. G. Martínez acknowledges JPL funding from USRA Contract Number 1638782. A. Vicente-Retortillo is supported by the Spanish State Research Agency (AEI) Project No. MDM-2017-0737 Unidad de Excelencia “María de Maeztu”- Centro de Astrobiología (INTA-CSIC), and by the Comunidad de Madrid Project S2018/NMT-4291 (TEC2SPACE-CM). Researchers based in France acknowledge support from CNES for their work on Perseverance

Apolipoprotein D synthesis progressively increases in frontal cortex during human lifespan

Apolipoprotein D (apo D) is a lipocalin present in the nervous system that may be related to processes of reinnervation, regeneration and neuronal cell protection. In the other way, apo D expression has been correlated, in some brain regions, with normal aging and neurodegenerative diseases. To elucidate the regional and cellular expression of apo D in normal human brain during aging, we performed a detailed and extensive study in samples of post-mortem human cerebral cortices. To achieve this study, slot blot techniques, for protein and mRNA, as well as immunohistochemistry and hybridohistochemistry methods were used. A positive correlation for apo D expression with aging was found; furthermore, mRNA levels, as well as the protein ones, were higher in the white than in the grey matter. Immunohistochemistry and non-isotopic HIS showed that apo D is synthesized in both neurons and glial cells. Apo D expression is notorious in oligodendrocytes but with aging the number of neurons that synthesize apo D is increased. Our results indicate that apo D could play a fundamental role in central nervous system aging and in the reduction of products derivated from lipid peroxidation. The increment in the expression of apo D with aging can be included in a global mechanism of cellular protection to prevent the deleterious effects caused by aging

Primary care randomized clinical trial: manual therapy effectiveness in comparison with TENS in patients with neck pain

This study investigated effectiveness of manual therapy (MT) with transcutaneous electrical nerve stimulation (TENS) to reduce pain intensity in patients with mechanical neck disorder (MND). A randomized multi-centered controlled clinical trial was performed in 12 Primary Care Physiotherapy Units in Madrid Region. Ninety patients were included with diagnoses of subacute or chronic MND without neurological damage, 47 patients received MT and 43 TENS. The primary outcome was pain intensity measured in millimeters using the Visual Analogue Scale (VAS). Also disability, quality of life, adverse effects and sociodemographic and prognosis variables were measured. Three evaluations were performed (before, when the procedure ?nished and six months after). Seventy-one patients (79%) completed the follow-up measurement at six months. In more than half of the treated patients the procedure had a clinically relevant ?short term? result after having ended the intervention, when either MT or TENS was used. The success rate decreased to one-third of the patients 6 months after the intervention. No differences can be found in the reduction of pain, in the decrease of disability nor in the quality of life between both therapies. Both analyzed physiotherapy techniques produce a short-term pain reduction that is clinically relevant.Ministerio de SanidadInstituto de Salud Carlos II

Study of the properties of thermoset materials derived from epoxidized soybean oil and protein fillers

[EN] Novel bio-based thermoset formulations were prepared by using epoxidized soybean oil (ESBO), nadic methyl anhydride as a hardener and with different types of proteins as fillers. In the first part of the study, the effect of the protein-type (wheat gluten, soy protein, casein and ovalbumin) on cured ESBO materials was investigated. Thermal and mechanical properties were characterized by flexural tests, Shore D hardness, Charpy impact tests, Vicat softening temperature and heat deflection temperature. In addition, a study of the morphology of fractured surfaces by scanning electron microscopy was carried out. In general, the addition of protein-based fillers improved the mechanical and thermal properties. It was found that the highest increase of thermal and mechanical properties was achieved by ovalbumin. In the second part of the work, the effect of the total amount of ovalbumin filler was studied. Bio-based thermoset materials from ESBO and 15 wt % ovalbumin improved flexural modulus more than 150 % when compared to the unfilled material. Similar evolution was observed for other mechanical properties. Moreover, the brittleness of this composition was the minimum from the studied systems. A direct relationship between energy absorption capacity and morphologies of the failure surface was evidenced by SEM.This work is a part of the project IPT-310000-2010-037,"ECOTEXCOMP: Research and development of textile structures useful as reinforcement of composite materials with marked ecological character" funded by the "Ministerio de Ciencia e Innovacion", with an aid of 189540.20 euros, within the "Plan Nacional de Investigacion Cientifica, Desarrollo e Innovacion Tecnologica 2008-2011" and funded by the European Union through FEDER funds, Technology Fund 2007-2013, "Operational Programme on R+D+I for and on behalf of the companies". Also, Generalitat Valenciana ACOMP/2012/087 is acknowledged for financial support.Fombuena Borrás, V.; Sánchez Nacher, L.; Samper Madrigal, MD.; Juárez Varón, D.; Balart Gimeno, RA. (2013). Study of the properties of thermoset materials derived from epoxidized soybean oil and protein fillers. Journal of the American Oil Chemists' Society. 90(3):449-457. https://doi.org/10.1007/s11746-012-2171-2S449457903Alonso MV, Oliet M, Garcia J, Rodriguez F, Echeverria J (2006) Gelation and isoconversional kinetic analysis of lignin-phenol-formaldehyde resol resins cure. Chem Eng J 122:159–166Altuna FI, Esposito LH, Ruseckaite RA, Stefani PM (2011) Thermal and mechanical properties of anhydride-cured epoxy resins with different contents of bio-based epoxidized soybean oil. J Appl Polym Sci 120:789–798Boquillon N, Fringant C (2000) Polymer networks derived from curing of epoxidised linseed oil: influence of different catalysts and anhydride hardeners. 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The sound of a Martian dust devil

Dust devils (convective vortices loaded with dust) are common at the surface of Mars, particularly at Jezero crater, the landing site of the Perseverance rover. They are indicators of atmospheric turbulence and are an important lifting mechanism for the Martian dust cycle. Improving our understanding of dust lifting and atmospheric transport is key for accurate simulation of the dust cycle and for the prediction of dust storms, in addition to being important for future space exploration as grain impacts are implicated in the degradation of hardware on the surface of Mars. Here we describe the sound of a Martian dust devil as recorded by the SuperCam instrument on the Perseverance rover. The dust devil encounter was also simultaneously imaged by the Perseverance rover's Navigation Camera and observed by several sensors in the Mars Environmental Dynamics Analyzer instrument. Combining these unique multi-sensorial data with modelling, we show that the dust devil was around 25m large, at least 118m tall, and passed directly over the rover travelling at approximately 5ms-1. Acoustic signals of grain impacts recorded during the vortex encounter provide quantitative information about the number density of particles in the vortex. The sound of a Martian dust devil was inaccessible until SuperCam microphone recordings. This chance dust devil encounter demonstrates the potential of acoustic data for resolving the rapid wind structure of the Martian atmosphere and for directly quantifying wind-blown grain fluxes on Mars.We are most grateful for the support of the Mars 2020 project team, including hardware and operation teams. This project was supported in the US by the NASA Mars Exploration Program, and in France by CNES. It is based on observations with SuperCam embarked on Perseverance (Mars2020). The research carried out at the Jet Propulsion Laboratory, California Institute of Technology, is under a contract with the National Aeronautics and Space Administration (80NM0018D0004). The JPL co-author (M.T.) acknowledges funding from NASA’s Space Technology Mission Directorate and the Science Mission Directorate. A. V-R is supported by the Spanish State Research Agency (AEI) Project No. MDM-2017-0737 Unidad de Excelencia “María de Maeztu”- Centro de Astrobiología (INTA-CSIC), and by the Comunidad de Madrid Project S2018/NMT-4291 (TEC2SPACE-CM). R.H. and A.S-L. were supported by Grant PID2019-109467GB-I00 funded by MCIN/AEI/10.13039/501100011033/ and by Grupos Gobierno Vasco IT1742-22. A.M. was supported by Grant PRE2020-092562 funded by MCIN/AEI/10.13039/501100011033 and by “ESF Investing in your future”. R.L. acknowledges InSight PSP Grant 80NSSC18K1626 as well as the Mars 2020 project. B.C. is supported by the Director’s Postdoctoral Fellowship from the Los Alamos National Laboratory, grant 20210960PRD3. JA.RM., M.M, J.T and J.G-E were supported by MCIN/AEI’s Grant RTI2018-098728-B-C31

Second-generation lignocellulosic supportive material improves atomic ratios of C:O and H:O and thermomechanical behavior of hybrid non-woody pellets.

Abstract: Pellets refer to solid biofuels for heating and power. The pellet's integrity is of great relevant to ensure safe and effective transportation and storage, and comfort to stakeholders. Several materials that are supportive, whether organic and inorganic, to pellets exist. However, no work in the literature is linking making hybrid non-wood pellets with addition of residual biomass from distillation of cellulosic bioethanol, and this requires further investigations. Figuring out how effective this challenging agro-industrial residue could be for reinforcing non-wood pellets is accordingly the scientific point of this study focusing on management of waste and valorization of biomass. The pilot-scale manufacturing of hybrid pellets consisted of systematically pressing sugarcane bagasse with the lignocellulosic reinforcement at the mass ratios of 3:1, 1:1, and 1:3 on an automatic pelletizer machine at 200 MPa and 125 °C. Elemental contents of C and H, durability, and energy density all increased significantly from 50.05 to 53.50%, 5.95 to 7.80%, 95.90 to 99.55%, and 28.20 to 31.20 MJ kg-1, respectively, with blending the starting material with the reinforcement at 1:3. Preliminary evidence of residual biomass from distillation of second-generation bioethanol capable of highly improving molecular flammable/combustible properties, mechanical stability, and fuel power of composite non-wood pellets exist