Surface Dynamics Research Articles

Patterns of surface water dynamics and storage changes in a basin of Bundelkhand Region, India: Implications for water management

AbstractSurface water is essential for agricultural, domestic and industrial production worldwide. Monitoring surface dynamics is crucial for sustainable ecosystems and global water resources. Importance of monitoring surface water dynamics is even more pronounced in the semi‐arid regions worldwide. An analysis of surface water extent and volume change patterns has been conducted, comparing these dynamics with alterations in precipitation patterns within a basin in Central Bundelkhand, a semi‐arid region in the Central India prone to droughts. To map the waterbodies, we leveraged Sentinel‐1 SAR data using an automated mapping framework and utilised DEM dataset to extract bathymetry using interpolation with modifications using water persistence. Analysis revealed a lag in surface water peak water level with respect to accumulated rainfall by 2–3 months. Furthermore, we have categorised the water bodies into small, medium and large by surface area and found that smaller water bodies show a higher intra‐annual variance, while medium and large water bodies show a lower intra‐annual variance. The findings suggest that smaller communities reliant on smaller water bodies are at a higher risk from climate variability in the region and a delay in attaining peak surface storage across the basin causes further challenges to water management.

The Phase Structure of Wave Disturbances Excited by a Pulsating Source at the Interface of a Liquid Flow of Finite Depth and an Ice Sheet

The floating ice sheet determines the dynamic interaction between the ocean and the atmosphere, affects the dynamics of the sea surface and subsurface waters, since the ice sheet and the entire mass of liquid under it participate in the general vertical movement. The paper investigates the phase structure of wave fields arising at the interface between ice and a flow of homogeneous liquid of finite thickness when flowing around a localized pulsating source of disturbances. The ice sheet is modeled by a thin elastic plate, the deformations of which are small, and the plate is physically linear. An integral representation of the solution is obtained, and the results of calculations of dispersion dependencies and phase patterns for various parameters of wave generation are presented. It is shown that the main parameters determining the characteristics of the amplitude-phase structure of wave disturbances of the ice sheet surface are ice thickness, flow velocity, and pulsation frequency. Numerical calculations demonstrate that when the flow velocities, ice thickness, and frequency change, there is a noticeable qualitative restructuring of the phase patterns of the excited long-range wave fields at the ice-liquid interface.

Formation of giant copper deposits driven by rapid uplift and sudden depressurization

Abstract Porphyry Cu deposits (PCDs) in collisional orogens are new targets for modern mineral exploration. A series of post-collisional (Miocene; 22-12Ma) porphyry copper deposit (PCDs) with Cu reserve over 45 Mt have been discovered in the Gangdese magmatic belt, southern Tibet. These magmas derived from partial melting of sulfide-bearing Tibetan juvenile lower crust are fertile for porphyry Cu in many aspects, such as high oxidation state, and rich volatiles such as water, S, and Cl, but some of individual plutons ended up with economic concentrations. The fundamental question remains what accounts for the significant Cu endowments. We measured the igneous zircon water contents of ore-related and barren high Sr/Y magmas in the Gangdese belt, southern Tibet and found that magmas that produce giant PCDs have lower zircon water contents than barren and small-deposit related magmas. Combined with previous fluid inclusions, magmatic breccias, apatite geochemistry, and thermal histories, which demonstrated higher initial water content in causative porphyries such as giant deposits of Qulong and Jiama, we believe that the lower zircon water content may be attributed to these magmas experiencing of faster cooling and sudden depressurization of a large, primed, volatile-saturated or supersaturated mid-upper crustal magma chamber, which could lead to rapid and voluminous volatile exsolution and fluid discharge. These processes caused intense hydrothermal alteration and large ore deposition. In contrast, magmas that experienced slow cooling and deep emplacement would undergo steady state degassing and weak alteration. The variable intrusive and thermal histories across Gangdese reflects interplay between surface and lithospheric dynamics within the Himalaya—Tibet orogen. Our findings suggest the difference of zircon water content reflects the emplacement rate and depth of granitic body, and therefore may serve as an indicator for tectonics and potential for mineralization.

Surface dynamics of small fast-rotating asteroids: Analysis of possible regolith on asteroid 2016 HO3

The Chinese Tianwen-2 mission is planned to explore and sample the near-Earth asteroid 2016 HO3, also named 469219 Kamo'oalewa. This paper intends to answer the question of whether 2016 HO3 has any regolith. A 3D model of an irregular shape was reconstructed from light curve data of 2016 HO3, with simulated impact craters embedded on its surface. We used numerical simulations to calculate the acceleration from gravity, fast rotation, and the van der Waals cohesive force. We found that the poles have a higher chance of hosting regolith, and the regolith may also rest on the walls of craters that face toward the rotation axis, making them potential sample collection sites. On the surface of 2016 HO3, the van der Waals force is strong enough to hold particles smaller than several centimeters against centrifugal force. Furthermore, we compare a pair of transient processes: thermal fatigue, which generates small particles, and micro-impacts, which remove the surface mass. Thermal fatigue is at least comparable to, and perhaps more efficient than, micro-impacts for 2016 HO3. Therefore, it is highly possible that regolith exists on the surface of 2016 HO3.

Improving subseasonal forecast skill in the Norwegian Climate Prediction Model using soil moisture data assimilation

AbstractThis study shows the importance of soil moisture (SM) in subseasonal-to-seasonal (S2S) predictions at mid-latitudes. We do this through introducing the Norwegian Climate Prediction Model Land (NorCPM-Land), a land reanalysis framework tailored for integration with the Norwegian Climate Prediction Model (NorCPM). NorCPM-Land assimilates blended SM data from the European Space Agency’s Climate Change Initiative into a 30-member offline simulation of the Community Land Model with fluxes from the coupled model. The assimilation of SM data reduces error in SM by 10.5 % when validated against independent SM observations. It also improves latent heat flux estimates, illustrating that the adjustment of underlying SM significantly augments the capacity to model land surface dynamics. We evaluate the added value of land initialisation for subseasonal predictions, by comparing the performance of hindcasts (retrospective prediction) using the standard NorCPM with a version where the land initial condition is taken from NorCPM-Land reanalysis. The hindcast covers the period 2000 to 2019 with four start dates per year. Land initialisation enhances SM predictions, reducing error by up to 2.5-month lead time. Likewise, the error for precipitation and temperature shows improvement up to a lead time of 1.5-month. The largest improvements are observed in regions with significant land-atmospheric coupling, such as the Central United States, the Sahel, and Central India. This method further enhances the prediction of extreme temperature variations, both high and low, with the most notable improvements seen in regions at mid and high latitudes, including parts of Europe, the United States, and Asia. Overall, our study provides further evidence for the significant role of SM content in enhancing the accuracy of subseasonal predictions. This study introduces a technique for improved land initialisation, utilising the same model employed in climate predictions.

Insights into Martian bedform migration: Results from Gale, Jezero and Pasteur craters

AbstractAn attempt is made in this study to advance the understanding of the sand movement on Mars by studying the bedform migration at Gale, Jezero and Pasteur craters. The study on the grain size distribution at Gale Crater using Curiosity rover (MAHLI and APXS) observations reveals that the grains with smaller diameters (~50–150 μ) are more prone to migration and vice‐versa, which gives an idea of the necessary requirements that initiate bedform migration. The chemical analysis of the surface materials at the Gale crater revealed elevated concentrations of P2O5, SO3, Cl and Zn in soil compared to sand and active transportation processes for sand but not soil. The comprehensive chemical makeup of the Martian soil (inactive bedforms) and sand (active bedforms) is characterized by its basaltic nature, with enriched volatile elements such as sulphur, chlorine and zinc, and the presence of minerals like plagioclase, pyroxene and olivine due to the cohesive nature of inactive bedforms. Physical weathering and wind flow velocity play a pivotal role in the formation of different sedimentary bodies, impacting grain size distribution and mineralogy. The effect of dust‐lifting on surface features is studied by analysing Perseverance‐MEDA observations at the Jezero crater to understand the short‐term changes in the bedform. These events are found to involve the redistribution of only a small amount of materials and, thereby, changing surface features on Mars over a short period. To detect the bedform migration in the Pasteur crater, several HiRISE images acquired over different time intervals were used. The changes in the ripple crest (~0.29–1.18 m/Earth year) and dune slip face suggest new grain flow events. In the Pasteur crater, extensive changes in sand deposits near the dunes signify a widespread bedform migration. The stronger north‐westerly and north‐easterly winds dominate these changes. Thus, the bedform migration in the three tropical craters exhibits significant variability driven by localized aeolian processes. This variability is crucial for understanding Mars' geological history, current surface dynamics and eventually, helps in planning future missions.

Influence of mesoscale eddies on wind retrieval from C-band synthetic aperture radar images

ABSTRACT Synthetic Aperture Radar (SAR) is an innovative technique for monitoring sea surface dynamics and has a large swath coverage (>200 km). In this paper, we investigate the characteristics of anticyclonic and cyclonic eddies on SAR and the influence of mesoscale eddies on SAR wind retrieval. Mesoscale eddies in the global oceans are identified from daily sea level anomaly (SLA) data in 2022–2023, which are integrated by the Haiyang-2B/2C/2D (HY-2B/2C/2D) altimeters. A total of 1000 Sentinel-1 (S-1) images acquired in interferometric-wide (IW) and extra-wide (EW) modes are available, and they cover the mesoscale eddies. In addition, swath wind products from HY-2 scatterometers and sea surface temperature (SST) data from Haiyang-1C (HY-1C) are collected. Co-polarized (vertical–vertical (VV) and horizontal–horizontal (HH)) Geophysical Model Function (GMF) C-SARMOD2 was applied to invert the wind speed with reference to the scatterometer-measured wind direction. The variation in the difference (SAR retrievals minus scatterometer measurements) indicates that the SST of below 11°C has a certain impact on the SAR wind retrieval. The influence is weak at higher SSTs, and the difference increases with increasing eddy kinetic energy (EKE). It is concluded that the shear current associated with mesoscale eddies is a significant factor that affects the accuracy of SAR-derived winds.

Early expression of osteopontin glycoprotein on the ocular surface and in tear fluid contributes to ocular surface diseases in type 2 diabetic mice.

Osteopontin (OPN) is a glycosylated, secreted phosphoprotein known to be elevated in both human and mouse retinas during various stages of diabetic retinopathy. However, its specific roles in modulating ocular surface dynamics and immune responses in diabetes remain unexplored. This study aims to investigate the role of OPN in the development of ocular surface disease (OSD) in type 2 diabetic (T2D) mice. Three- to four-week-old C57BL/6 wild-type (WT) and OPN-knockout (OPN-/-) mice were fed a high-fat diet (HFD) and were rendered diabetic by streptozotocin (STZ; 40 mg/kg body weight) in citrate buffer (vehicle); non-diabetic controls were injected with vehicle alone. Diabetes was confirmed if blood glucose levels were >200 mg/dL, measured 1-2 weeks post-STZ injection. Control, age- and sex-matched db/db diabetic mice fed a standard chow diet were also included in this study. Ocular surface inflammation was assessed using ELISA to quantify inflammatory cytokine proteins and wheat germ agglutinin (WGA) staining was utilized to highlight corneal surface irregularities. Clinical signs were evaluated by corneal fluorescein staining, tear production measurements, and tear sodium (Na+) concentration assessments. These evaluations were conducted 4, 6, 8 and 16-weeks post-diabetes onset in WT and OPN-/- mice and were compared to those obtained in non-diabetic controls. Statistical analysis was performed using a two-way ANOVA, with significance set at P < 0.05. Both WT and OPN-/- mice developed T2D within 4 and 8 weeks, respectively, following HFD + STZ treatment. Corneal OPN levels in WT diabetic mice increased ~2-fold at 2 weeks and ~4-fold at 16 weeks compared to non-diabetic controls, with similar elevations observed in their tear fluid. Diabetic db/db mice also exhibited elevated OPN levels in the blood and ocular surface, which persisted as diabetes progressed. Enhanced fluorescein staining, indicating corneal irregularities, appeared in WT mice at 8 weeks and in OPN-/- mice at 10 weeks post-T2D induction. Additionally, WGA staining showed a significant reduction in fluorescence intensity in WT mice treated with HFD and STZ, confirming corneal surface irregularities that were delayed in OPN-/- mice. Elevated tear sodium concentration was observed in both WT and OPN-/- diabetic mice without affecting tear production rates. Notably, OPN levels increased early, at week 2, following HFD and STZ treatment, preceding changes in interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and matrix metalloproteinase-9 (MMP-9). Upregulation of IL-6 became apparent at 6 weeks in WT mice and was delayed until 10 weeks in OPN-/- mice post-T2D induction. Elevated OPN levels were detected early post-T2D induction in diabetic WT and db/db mice corneas without initial subclinical changes. This early increase in OPN precedes other proinflammatory cytokines associated with eventual ocular surface inflammation as diabetes progresses. Persistence of OPN also correlated with clinical signs such as increased corneal surface irregularities and elevated tear Na+ concentration. Future research will explore OPN's role as a biomarker in ocular surface disease (OSD), including dry eye disease (DED), and investigate its impact on inflammatory processes and other mechanistic pathways in diabetic ocular complications.

Technical Overview of ISRO and NASA’s First Joint Mission: NASA-ISRO Synthetic Aperture Radar (NISAR) Satellite

The NASA-ISRO Synthetic Aperture Radar (NISAR) mission represents a groundbreaking collaboration aimed at comprehensively monitoring Earth's surface dynamics. Through the fusion of L-band and S-band radar frequencies, NISAR promises unprecedented precision in detecting subtle surface changes, ranging from ecosystem disruptions to ice sheet collapses and natural hazard occurrences. This paper explores the mission's objectives, technology, and significance in advancing our understanding of climate change impacts and hazard mitigation. The partnership between NASA and ISRO, culminating in the signing of agreements in 2014, underscores the international cooperation vital for addressing complex global challenges. With its targeted launch, NISAR heralds a new era in Earth observation, enabled by the fusion of cutting-edge technology and collaborative scientific endeavour.

Interferometric Synthetic Aperture Radar Phase Linking with Level 2 Coregistered Single Look Complexes: Enhancing Infrastructure Monitoring Accuracy at Algeciras Port

This paper presents an advanced workflow for processing radar imagery stacks using Persistent Scatterer and Distributed Scatterer Interferometry (PSDS) to enhance spatial coherence and improve displacement detection accuracy. The workflow leverages Level 2 Coregistered Single Look Complex (L2-CSLC) images generated by the open-source COMPASS (Coregistered Multi-temporal Sar SLC) framework in combination with the Combined eigenvalue maximum likelihood Phase Linking (CPL) approach implemented in MiaplPy. Starting the analysis directly from Level 2 products offers a significant advantage to end-users, as they simplify processing by being pre-geocoded and ready for immediate analysis. Additionally, the open-source nature of the workflow and the use of L2-CSLC products simplify the processing pipeline, making it easier to distribute directly to users for practical applications in monitoring infrastructure stability in dynamic environments. The ISCE3-MiaplPy workflow is compared against ISCE2-MiaplPy and the European Ground Motion Service (EGMS) to assess its performance in detecting infrastructure deformations in dynamic environments, such as the Algeciras port. The results indicate that ISCE3-MiaplPy delivers denser measurements, albeit with increased noise, compared to its counterparts. This higher resolution enables a more detailed understanding of infrastructure stability and surface dynamics, which is critical for environments with ongoing human activity or natural forces.

Parameters impact analysis on contact characteristics of intersected beveloid gear and involute cylindrical gear

According to gear geometry and tooth contact analysis (TCA) theory, the TCA model of intersected beveloid gear and involute cylindrical gear pair is built. The formulas for calculating curvature and contact ellipse at contact points are derived, and the shape and region of contact ellipse are determined. Then, the impacts of cone angle, helix angle and installation errors on contact characteristics are studied by numerical examples. The finite element model of gear pair is established to carry out the loaded tooth contact analysis (LTCA) and verify the accuracy of theoretical TCA model. The results show that gear pair with small cone angle or big helix angle has wide contact area, large carrying capacity and high transmission quality. The shaft angle error may cause the edge contact of gear pair, while the axial position error has limited effect. The research can provide input parameters for the study of tooth surface wear mechanism and dynamics in the future work.

An affordable operational oil spill monitoring system in action: A diachronic multiplatform analysis of recent incidents in the southern Gulf of Mexico

The coexistence of marine sensitive areas with the oil industry requires robust preparedness and rapid response capabilities for monitoring and mitigating oil spill events. Scientifically proven satellite-based methods for the visual detection of oil spills are widely recognized as effective, low-cost, transferable, scalable, and operational solutions, particularly in developing economies. Following meticulous design and implementation, we adopted and executed a relatively low-cost operational monitoring and alert system for oil spill detection over the ocean surface and alert issuance. We analyzed over 1500 satellite images, issuing over 70 warning reports on oil slicks and spills in the southern Gulf of Mexico. To assess the system’s efficiency and performance, we leveraged data from three major oil spill incidents in the study region during June and July of 2023 in the study region, covering a maximum area of 669 km2 and tracked for 12 to 24 days. We documented the evolution of these oil spills by integrating satellite sensing data with on-site Lagrangian drifting buoys, a network of high-frequency radars, and citizen reports to validate the outcomes of this system. We generated timely technical information on the spill’s evolution, informing decision-makers and local community leaders to strengthen their mitigation response capabilities. Additionally, we developed a robust database with spectral and spatiotemporal features of satellite-detected oil, thereby contributing to advancing the scientific understanding of sea surface dynamics related to natural and anthropogenic oil sources. This study also highlights immediate-, medium-, and long-term research agendas and establishes a reference for a sustained, transferable, and operational oil spill monitoring system.

Bi2O2.33/Bi4O5I2-heterojunction photocatalysts for adsorption and visible light-driven degradation of pharmaceutical pollutants

This study introduces the innovative Bi4O5I2/Bi2O2.33 heterojunction for diclofenac (DF) degradation. Pharmaceutical pollutants, especially DF, pose significant threats to water sources, necessitating efficient treatment methods. Bi2O2.33, renowned for its unique ferromagnetic properties, emerges as a promising photocatalyst for pollutant degradation. Bi4O5I2, known for strong visible light absorption and stability, holds potential for environmental applications. Interestingly, the inclusion of titanium dioxide (TiO2) in the composite catalysts significantly influences their observed ferromagnetic properties, as revealed by Electron Paramagnetic Resonance (EPR) spectroscopy, by influencing the interactions within the Bi4O5I2/Bi2O2.33 heterojunction and influencing its structure, morphology, and spin behavior. This interaction results in enhanced EPR and Ferromagnetic Resonance (FMR) signals, indicating intriguing spin interactions, polarization effects, charge transfers, surface dynamics, and stabilized magnetic domains. While the enhanced ferromagnetism holds promise for efficient charge separation and potential applications in environmental remediation, the expected boost in visible light-driven activity was not fully realized. This limitation is attributed to TiO2 inherent inability to directly absorb visible light, hindering its utilization for enhanced photocatalysis within the heterojunction. Nevertheless, these findings elucidate the multifaceted role of TiO2 in modulating the magnetic properties of these catalysts, offering valuable insights for future advancements in the design of advanced photocatalysts for effective environmental remediation.

Numerical investigation on steady turning motion of a generic submarine near the free surface

This study investigated the steady turning motion of a generic submarine near the free surface using computational fluid dynamics (CFD) methods. The Joubert BB2 submarine and Marine 7371R propeller models were employed as the subjects of this research. The analysis utilized the Reynolds-averaged Navier-Stokes (RANS) equations with the SST k-ω turbulence model to capture turbulent flows, and the volume of fluid (VOF) method to capture the free surface dynamics. A mesh convergence study was conducted with three different mesh resolutions to ensure the accuracy of the simulations. An overset mesh method was used to control the submarine and its four control surfaces, while a sliding mesh approach simulated the propeller rotation. The self-propulsion point of the submarine was determined at a fixed speed using a PI controller. Subsequently, rudder maneuvers were executed to replicate a steady 20-degree turning motion. The study examined the effects of submergence depth and speed on the flow field. Results indicated an approximate 15% variation in turning parameters between the maximum and minimum submergence depths at the same speed, with force and torque differences around 30%. Additionally, the study explored the impact of the free surface on hydrodynamic forces, pressure distribution, free surface wave patterns, and vortex structures during turning maneuvers.

Hydrothermal dynamics of darcy Forchheimer ternary hybrid nanofluid flow past bended surface with active—passive controls

This dynamic study investigates hydrothermal and rheological properties of two-dimensional ternary nanofluid flow by using active passive control mechanisms on nanoparticles navigating a porous curved surface. The working fluid contains nanometer sized spherical shaped particles of three different metals [Formula: see text], which are homogenously and stably dispersed in liquid dihydrogen monoxide as host fluid. A strong magnetic force of strength [Formula: see text] acts along radial direction of curved surface. Thermal radiation term in heat equation suggests a strong heat source in the vicinity. This unique amalgamation, which has not been addressed so far by any researcher incorporates Brownian motion and thermophoresis to construct the hydrothermal framework. The passive control of nanoparticles on surface influenced by Brownian movement and thermophoresis, which is considered more realistic in comparison to constant concentration hypothesis (active control), have been taken into account. The nanoliquid flow is governed by system of Partial Differential Equations (PDEs) that cater thermophysical properties of nanoparticles. After simplifying the system to Ordinary Differential Equations (ODEs) using suitable transform, it is solved numerically using bvp4c in MATLAB 2023a. The obtained graphical and numerical results are discussed in detail to explain physics of observed thermo-rheological behaviour and mass diffusivity. The study reveals that curvature and porosity factors have opposite effects on velocity profile. All involved parameters augment temperature profile for both active and passive controls except curvature factors. In all the cases, active control assures higher temperature over passive control. Dual consequences have been noted for active and passive controls for concentration panels in most cases. Nusselt number is found increasing for increasing nanoparticles concentration with ternary nanofluid having maximum heat transfer rate. This study significantly contributes to the knowledge of ternary nanofluidic thermo-rheological analysis on curved stretching surface having numerous applications in mechanical, thermal and industrial domains. It also offers insights for developing advanced coatings and materials in industrial and engineering context.

Using hydrological modeling and satellite observations to elucidate subsurface and surface hydrological responses to the extreme drought

Climate change and anthropogenic activities have intensified extreme weather events globally. In the summer of 2022, the Yangtze River Basin (YRB) in China experienced an extreme drought, significantly impacting the ecosystems and society. However, the specific effects of this extreme drought on surface and subsurface hydrological dynamics remain unclear. Here we employed satellite-observed terrestrial water storage anomaly (TWSA) and a modified hydrological model with consideration of reservoir operation, human water consumption, and water diversion engineering to quantify how subsurface and surface water in YRB responded to such an extreme drought in 2022. Validation against a series of observations shows that the modified model has good performance in reproducing daily streamflow, reservoir water storage, lake water storage, and snow water equivalent. It achieved more precise GRACE TWSA estimates in the YRB with significant human intervention, and therefore it can fairly accurately quantify both surface and subsurface hydrological responses to the 2022 extreme drought. Compared to the same months (July-December) in 2015–2021, the drought in 2022 resulted in a decrease in precipitation and discharge of 373 km3 (36 %) and 324 km3 (50 %), respectively, while an increase in evapotranspiration of 156 km3 (29 %) in the YRB. In general, the surface water storage (SWS) is relatively low from July 2022, followed by subsurface water storage (SSWS) from August 2022, indicating an approximately one-month lag from the former to the latter. During the latter half year of 2022, the SWS and SSWS reduced by 48 km3 and 83 km3, respectively, suggesting the changes in the latter dominated the TWS variations. This study sheds light on the responses of surface and subsurface hydrology to extreme droughts, and the hydrological modeling framework with consideration of human activities proposed here holds applicability beyond the YRB.

A bulk-surface mechanobiochemical modelling approach for single cell migration in two-space dimensions

In this work, we present a mechanobiochemical model for two-dimensional cell migration which couples mechanical properties of the cell cytosol with biochemical processes taking place near or on the cell plasma membrane. The modelling approach is based on a recently developed mathematical formalism of evolving bulk-surface partial differential equations of reaction–diffusion type. We solve these equations using finite element methods within a moving-mesh framework derived from the weak formulation of the evolving bulk-surface PDEs. In the present work, the cell cytosol interior (bulk) dynamics are coupled to the cell membrane (surface) dynamics through non-homogeneous Dirichlet boundary conditions. The modelling approach exhibits both directed cell migration in response to chemical cues as well as spontaneous migration in the absence of such cues. As a by-product, the approach shows fundamental characteristics associated with single cell migration such as: (i) cytosolic and membrane polarisation, (ii) actin dependent protrusions, and (iii) continuous shape deformation of the cell during migration.Cell migration is an ubiquitous process in life that is mainly triggered by the dynamics of the actin cytoskeleton and therefore is driven by both mechanical and biochemical processes. It is a multistep process essential for mammalian organisms and is closely linked to a vast diversity of processes; from embryonic development to cancer invasion. Experimental, theoretical and computational studies have been key to elucidate the mechanisms underlying cell migration. On one hand, rapid advances in experimental techniques allow for detailed experimental measurements of cell migration pathways, while, on the other, computational approaches allow for the modelling, analysis and understanding of such observations. The bulk-surface mechanobiochemical modelling approach presented in this work, set premises to study single cell migration through complex non-isotropic environments in two- and three-space dimensions.

Basalt Alteration in a CO2–SO2 Atmosphere: Implications for Surface Processes on Venus

AbstractVenus' surface and interior dynamics remain largely unconstrained, due in great part to the major obstacles to exploration imposed by its 470°C, 90 bar surface conditions and its thick, opaque atmosphere. Flyby and orbiter‐based thermal emission data provide opportunities to characterize the surface composition of Venus. However, robust interpretations of such data depend on understanding interactions between the planet's surface basaltic rocks and its caustic carbon dioxide (CO2)‐dominant atmosphere, containing trace amounts of sulfur dioxide (SO2). Several studies, using remote sensing, thermodynamic modeling, and laboratory experiments, have placed constraints on basaltic alteration mineralogy and rates. However, constraints on the effects of SO2‐bearing reactions on basalts with diverse compositions remain incomplete. Here, we present new data from a series of gas‐solid reaction experiments, in which samples of two basalt compositions were reacted in an SO2‐bearing CO2 atmosphere, at relevant Venus temperatures, pressure, and oxygen fugacity. Reacted specimens were analyzed by scanning electron microscopy and scanning transmission electron microscopy using sample cross‐sections produced with focused ion beam milling. Surface alteration products were characterized, and their abundances estimated; subsurface cation concentrations were mapped to show the depth of alteration. We demonstrate that the initial development of reaction products progresses rapidly over the course of 30‐day runs. Alkaline basalt samples are coated by Na‐sulfate (likely thenardite, Na2SO4) and amorphous calcium carbonate (CaCO3) alteration products, and tholeiitic basalt samples are primarily covered by anhydrite (CaSO4), Fe‐oxide (FexOy: likely magnetite, Fe3O4), and other minor phases. These mineralogies differ from previous experiments in CO2‐only atmospheres.

CFD simulations of the transition between non-aerated and aerated conditions in uncovered unbaffled stirred tanks

The transition between non-aerated and aerated regimes in uncovered unbaffled stirred tanks (UUSTs) was investigated using computational fluid dynamics (CFD). The Volume of Fluid (VOF) method was employed to model the free surface dynamics under various operational conditions. The simulations were able to predict the peculiar experimentally observed behavior of UUSTs and revealed that at velocities below a critical threshold (N_<_Ncrit), the system remains non-aerated, while exceeding this threshold (N_≥_Ncrit) induces bubble ingestion, leading to significant changes in power consumption and flow patterns. The CFD simulations accurately predicted the behaviour of the Power Number (Np) as well as the vortex shape inside the tank both in subcritical and supercritical regimes and showed good agreement with original experimental data and correlations from the literature. Additionally, the modeling of the aerated regime successfully predicted the vortex shape, the bubble dispersion within the tank, and the cavities formed behind the blades.

Insights into glass surface dynamics from fast scanning calorimetry studies of softening and vaporization of ultrathin molecular films.

Chemical and physical processes on the surfaces of amorphous solids have been the focus of many studies over the past decades. These studies have established that dynamics in a thin layer near a glass surface are often dramatically faster than those in the glass bulk. Nevertheless, recent advances also emphasize the need for new experimental techniques capable of characterizing the structure and dynamics of the near-surface regions in glassy materials at the molecular length scale. Using a quasi-adiabatic fast scanning calorimetry (FSC) technique, we have investigated softening and vaporization of pure amorphous methylbenzene films of moderately heightened kinetic stability with thicknesses ranging from 1 to 20nm. The analysis of the FSC thermograms reveals the existence of a high fictive temperature (liquid-like) layer on the surface of the solid glass with a thickness of 3.5 ± 0.5nm or seven molecular diameters. Furthermore, the width of the boundary between liquid-like and solid layers in the films is less than 1nm. These preliminary findings compliment and substantiate past determinations of the mobile surface layer thicknesses obtained by introduction of nanoparticles or spectroscopic molecular probes to near-surface regions of amorphous samples. The developed FSC methodology will advance the theoretical and computational research by providing calorimetric data on the enhanced interfacial dynamics phenomenon in a variety of low-molecular-weight amorphous materials.