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Both straight and curved carbon fibers are widely used in various commercial gas diffusion layer (GDL) fabrications. The effect of the different carbon fiber curvatures on two-phase flow dynamics within the cathode GDLs of proton exchange membrane fuel cells remains unclear. In this study, we investigate liquid transport in three types of GDLs with varying fiber curvatures using the two-phase volume of fluid simulations in OpenFOAM. For the first time, a rod periodic surface model is combined with a layer-by-layer fiber stacking strategy, to stochastically reconstruct GDL structures while incorporating crucial parameters from physical (experimental) GDLs. A grid independence study and model validation are conducted. Following pore network analysis of pore size distribution and connectivity, we study the time-varying GDL total and local water saturation and capillary pressure. Despite maintaining similar layer and bulk porosity, increased fiber curvature enhances pore connectivity but raises water saturation and capillary pressure, increasing the risk of flooding. Additionally, droplets in gas channels with straight-fiber GDLs are larger and have slower movement than those in curved-fiber GDLs. Fiber curvature inversely affects drainage capacity in GDLs and connected channels. With comparable water saturation and capillary pressure, curved-fiber GDLs exhibit lower discrepancies, suggesting improved uniformity in water distribution. [Display omitted] • Curved and straight fiber GDLs are reconstructed with similar bulk and layer porosity. • Increasing fiber curvature enhances pore connectivity and pore quantity. • GDL water saturation and capillary pressure increase with an increased fiber curvature. • Increasing the amount of small pores results in stronger water spreading within GDLs. • Detached droplets in GCs have smaller sizes and longer liquid bridge when using curved-fiber GDLs. [ABSTRACT FROM AUTHOR]

• Bubble cluster behaviour in froth characterised by dynamic X-ray radiographic setup. • Particle reattachment, dropback, and accumulation were visualised. • X-ray radiography is a valuable tool for investigating froth dynamics. X-ray radiography presents a non-invasive and dynamic approach for examining multiphase flows, particularly in complex systems like flotation froths. While this technique has been applied successfully in various multiphase studies, such as granular flows and fluidised beds, its utilisation in understanding flotation froths is novel. This study aimed to investigate the behaviour of particles and bubbles within the froth phase using a unique flotation rig combined with an X-ray radiographic setup. Specifically, it sought to understand how the pulp-froth interface influences the entry of bubble clusters into the froth phase and to observe the journey of particles within the froth. The results provided tangible evidence supporting previously inferred phenomena. It was found that the interface between the pulp and froth acted as a barrier, impeding the entry of bubble clusters into the froth phase. However, what was particularly noteworthy about the study was its revelation of extraordinary dynamics in particle movement within the froth phase. These dynamics included the occurrence of reattachment and dropback at critical solid fractions, phenomena that were visually observed for the first time. [ABSTRACT FROM AUTHOR]

Every living organism involves biological membranes one way or another, which are important in most biological processes and cellular functions. All of these are dramatically manipulated by not only the sizes and numbers of domains (lipid rafts) but also their lateral organization and phase dynamics in biomembranes. In this article, we discuss the recent findings on domain formation and phase transition behaviors in phospholipid mixtures containing cholesterol and relate to membrane lateral heterogeneity. Thermodynamic forces and considerations regulating in-plane as well as out-of-plane domain structures and interactions in lipid monolayers and bilayers are described. Compositional symmetry and asymmetry between inner and outer leaflets in biomembranes are also considered. [ABSTRACT FROM AUTHOR]

We consider networks of coupled phase oscillators of different complexity: Kuramoto–Daido-type networks, generalized Winfree networks, and hypernetworks with triple interactions. For these setups an inverse problem of reconstruction of the network connections and of the coupling function from the observations of the phase dynamics is addressed. We show how a reconstruction based on the minimization of the squared error can be implemented in all these cases. Examples include random networks with full disorder both in the connections and in the coupling functions, as well as networks where the coupling functions are taken from experimental data of electrochemical oscillators. The method can be directly applied to asynchronous dynamics of units, while in the case of synchrony, additional phase resettings are necessary for reconstruction. [ABSTRACT FROM AUTHOR]

• the percentage of release signals typically ranged between 5 and 30% per decade; • release frequency per decade was over-dispersed compared to the random (Poisson) model; • cadences of increasing/decreasing tree growth lasted between 24 and 54 years (30 years on average); • stand-level fluctuations in tree growth were small compared to the total variation in tree increment; • a mixed-severity disturbance regime suggests unsteady gap-phase dynamics. Disturbances have been recognized as a key factor shaping the species composition, structure and dynamics of natural forest ecosystems. In Europe, where forests driven by spontaneous processes have survived in relic form, knowledge about natural disturbance regimes is still fragmentary. To expand this knowledge, we reconstructed stand-level growth and analyzed the spatio-temporal pattern of release signals in the increment chronologies of individual trees as indicators of disturbance events in the Western Carpathians (Central Europe). The study was carried out in five old-growth forests formed by Fagus sylvatica L., Abies alba Mill. and Picea abies (L.) H. Karst. Depending on the stand, the analyses included tree-ring series of 84–193 trees sampled over areas of 5.9–13.6 ha and aimed at determining (1) the spatio-temporal pattern of disturbance severity over the last two centuries, (2) whether disturbances have been synchronized in time across the study sites and (3) whether disturbances have induced pulsed dynamics of stand development manifested as fluctuations in radial tree increment at the level of entire stands. In the period 1850–2010, the percentage of decades with the proportion of released trees < 10, 10–20, 20–30 or more than 30% was 38, 41, 14 and 7%, respectively, and no instances of severe disturbances simultaneously impacting an extensive area and releasing the vast majority of trees were found. The release events were only weakly synchronized at the between-stand level. The spatial distribution of released trees varied over the decades, with a shift toward spatial independence for the most severe disturbances. At the stand level, the interchanging periods of increasing/decreasing tree growth lasted between 24 and 36 years, with the exception of one stand in which this period lasted 54 years. The revealed fluctuations in tree growth attributable to changes in stand density were relatively small and accounted on average for 7% of the total variation in annual tree increments. This suggests that local level disturbances introduce structural heterogeneity and strongly modify tree growth, but at the stand level, their effect is dispersed and causes only minor fluctuations. An over-dispersion of decadal release frequencies compared to the random model and spatial correlation of disturbing events on the one hand, and the lack of extensive disturbances, frequent occurrence of multiple releases in tree life histories, and small fluctuations in the reconstructed growth at the stand level on the other hand, suggest a disturbance regime which goes beyond random processes in a strict sense and is thus not entirely compatible with the classical model of gap-phase stand dynamics. [ABSTRACT FROM AUTHOR]

Abstract: The tear film is a dynamic multilayered structure. The interactions and the interfacial dynamics between the layers that occur during a blink cycle must be such that they allow for maintenance of a stable tear film. Attempts to understand these dynamics have been limited by the techniques and biomarkers used. Quantum dots (qdots) offer a new potential to monitor the dynamics of the tear film layers in vivo without the drawbacks of previously used methodologies. Indium phosphide–gallium qdots were used to differentially assess the dynamics of the lipid and aqueous layers of the tear film in real time. In the aqueous, qdots dispersed to form a stable local region that was swept away into the upper and lower menisci during a blink. They did not redisperse onto the ocular surface but were progressively removed from the menisci through the puncta. Some of these qdots adhered to the mucin layer on the ocular surface in a meshlike pattern and remained there for five to six blinks before they were removed. The organic qdots dispersed quickly but patchily over the whole outer surface of the tear film. They also strongly marked both eyelid margins and slowly dispersed onto the skin and eyelashes and not through the puncta. Some were trapped in the menisci as blobs that rolled along the meniscus. These data support the view of a distinct three-layered tear film: an inner mucin layer attached to the epithelial cells, a fluid aqueous layer, and an outer viscoelastic lipid layer. From the Clinical Editor: Indium galium posphide quantum qdots were used to differentially assess the tear film in real time. These data support the view of a distinct three layered tear film: an inner mucin layer attached to the epithelial cells; a fluid aqueous layer; and an outer viscoelastic lipid layer. [ABSTRACT FROM AUTHOR]

Abstract: Objective: This study aimed to determine the underlying bases of single-trial electroencephalographic (EEG) activities of movement-related potential (MRP) and α-band event-related desynchronisation (α-ERD), both of which are cortical activities related to motor response execution because of their dependence on response time and laterality. Methods: We compared stimulus- and response-triggered EEG power and phase dynamics ipsilateral and contralateral to the response hand in Go trials during visual Go/NoGo reaction time tasks. Results: Two lateralised EEG power and phase dynamics were observed: transient power decreases in α-band EEG (corresponding to α-ERD) and consistent contralateral phase lags of θ-band EEG. Conclusions: α-ERD around the response onset is not substantially reflected in the MRP waveforms mainly because of phase inconsistency. Lateralised MRP waveforms around the response onset are mainly attributed to consistent contralateral phase lags in θ-band additive EEG deflections. Significance: Our results indicate that while both α-ERD and lateralised MRP are related to motor response execution, they reflect separate cortical activities. Analysis of EEG power and phase dynamics can help in elucidating the detailed underlying bases of cortical activities. [ABSTRACT FROM AUTHOR]

The authors consider a stochastic model based on the interaction and phase coupling amongst wave components that are modified envelope soliton solutions to the nonlinear Schrödinger equation. A probabilistic study is carried out and the resulting findings are compared with ocean wave field observations and laboratory experimental results. The wave height probability distribution obtained from the model is found to match well with prior data in the large wave height region. From the eigenvalue spectrum obtained through the Inverse Scattering Transform, it is revealed that the deep-water wave groups move at a speed different from the linear group speed, which justifies the inclusion of phase correction to the envelope solitary wave components. It is determined that phase synchronization amongst elementary solitary wave components can be critical for the formation of extreme waves in unidirectional sea states. [ABSTRACT FROM AUTHOR]

The CALPHAD system of fundamental phase-level databases, now known as the Materials Genome, has enabled a mature technology of computational materials design and qualification that has already met the acceleration goals of the national Materials Genome Initiative. As first commercialized by QuesTek Innovations, the methodology combines efficient genomic-level parametric design of new material composition and process specifications with multidisciplinary simulation-based forecasting of manufacturing variation, integrating efficient uncertainty management. Recent projects demonstrated under the multi-institutional CHiMaD Design Center notably include novel alloys designed specifically for additive manufacturing. With the proven success of the CALPHAD-based Materials Genome technology, current university research emphasizes new methodologies for affordable accelerated expansion of more accurate CALPHAD databases. Rapid adoption of these new capabilities by US apex corporations has compressed the materials design and development cycle to under 2 years, enabling a new "materials concurrency" integrated into a new level of concurrent engineering supporting an unprecedented level of manufacturing innovation. [ABSTRACT FROM AUTHOR]

Abstract: Understanding the coupled two-phase dynamics in the cathode gas diffusion layer (GDL) and gas channel (GC) is of vital importance to optimize water management and to improve performance of proton exchange membrane fuel cell (PEMFC). However, it is difficult to directly observe the two-phase flow in the cathode of PEMFC because the GDL is opaque and has complex structures. To circumvent this issue, a similarity experiment model is developed in the present study. Based on the soft lithography technology, we fabricate a microfluidic device composed of a duct representing the GC and a bundle of tubes representing the GDL. Emergence of liquid droplets from these tubes into the duct gas stream is conducted to mimic the two-phase dynamics in the GDL and the GC. With this similarity experiment, we explore the influences of the gas flow rate on the liquid water flow in the cathode of PEMFC as well as the effects of the GDL surface defects on the two-phase dynamics in the GC. The two-phase flows in the hydrophilic and hydrophobic systems are also compared to elucidate the effects of wettability on water management of PEMFCs. [Copyright &y& Elsevier]