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While cosmic rays (E ≳ 1 GeV) are well coupled to a galaxy's interstellar medium (ISM) at scales of L > 100 pc, adjusting stratification and driving outflows, their impact on small scales is less clear. Based on calculations of the cosmic-ray diffusion coefficient from observations of the grammage in the Milky Way, cosmic rays have little time to dynamically impact the ISM on those small scales. Using numerical simulations, we explore how more complex cosmic-ray transport could allow cosmic rays to couple to the ISM on small scales. We create a two-zone model of cosmic-ray transport, with the cosmic-ray diffusion coefficient set at the estimated Milky Way value in cold gas but smaller in warm gas. We compare this model to simulations with a constant diffusion coefficient. Quicker diffusion through cold gas allows more cold gas to form compared to a simulation with a constant, small diffusion coefficient. However, slower diffusion in warm gas allows cosmic rays to take energy from the turbulent cascade anisotropically. This cosmic-ray energization comes at the expense of turbulent energy which would otherwise be lost during radiative cooling. Finally, we show our two-zone model is capable of matching observational estimates of the grammage for some transport paths through the simulation. [ABSTRACT FROM AUTHOR]

We studied positive streamers with a 5 mm gap under 20–101 kPa pressure and 1%–31% O2 concentrations conditions using a 2D axisymmetric fluid model based on local field approximation. As the pressure decreases from 101 kPa to 20 kPa, the axial reduced electric field, the mean electron energy and the electron diffusion coefficient increase, which leads to the acceleration of the streamer propagation velocity and the increase of the streamer channel radius. The opposite change of ionization cross section and gas molecular density caused by the decrease of pressure leads to the non-monotonic change of the peak of net ionization rate. At medium-low pressure, there is a wider ionization region at the streamer head. As the O2 concentration decreases from 31% to 1% in N2/O2, the streamer propagation velocity decreases. When the O2 concentration drops to 1%, the streamer velocity decreases with a descent gradient of nearly 4 times, compared to 11% O2. Based on the space charge effect and chemical reaction rate, a possible mechanism is proposed to explain the abrupt change in the streamer velocity. [ABSTRACT FROM AUTHOR]

In recent years, spatial atomic layer deposition (SALD) has gained significant attention for its remarkable capability to accelerate ALD growth by several orders of magnitude compared to conventional ALD, all while operating at atmospheric pressure. Nevertheless, the persistent challenge of inadvertent contributions from chemical vapor deposition (CVD) in SALD processes continues to impede control over film homogeneity, and properties. This research underscores the often-overlooked influence of diffusion coefficients and important geometric parameters on the close-proximity SALD growth patterns. We introduce comprehensive physical models complemented by finite element method simulations for fluid dynamics to elucidate SALD growth kinetics across diverse scenarios. Our experimental findings, in alignment with theoretical models, reveal distinctive growth rate trends in ZnO and SnO2 films as a function of the deposition gap. These trends are ascribed to precursor diffusion effects within the SALD system. Notably, a reduced deposition gap proves advantageous for both diffusive and low-volatility bulky precursors, minimizing CVD contributions while enhancing precursor chemisorption kinetics. However, in cases involving highly diffusive precursors, a deposition gap of less than 100 μ m becomes imperative, posing technical challenges for large-scale applications. This can be ameliorated by strategically adjusting the separation distance between reactive gas outlets to mitigate CVD contributions, which in turn leads to a longer deposition time. Furthermore, we discuss the consequential impact on material properties and propose a strategy to optimize the injection head to control the ALD/CVD growth mode. [ABSTRACT FROM AUTHOR]

We present a method to model the gas permeation through silicon-oxide thin film coatings that are afflicted with nanoscale defects. With it, we are able to give an estimation of the diffusion coefficient in bulk by subtracting the influence of the defects. The model is based on data obtained from positron annihilation spectroscopy, which is processed to yield possible defect allocation patterns of the coatings. For a systematic evaluation of these patterns, a path through the coating is calculated and then subjected to in-depth analysis to evaluate the used approach as well as to interpret the results for insights on the permeation mechanisms. The model appears to function as intended and no unexpected behaviour is observed. The defect volume share is overestimated, which can be retraced to the underlying algorithm, and a correction method is applied to the resulting bulk diffusion coefficient. The model gives reasonable results both for oxygen and water vapor permeation. These results can be used in following works that build on the presented model. [ABSTRACT FROM AUTHOR]

A novel impurity transport model that approximates SOL turbulence as a fluctuating poloidal electric field is shown to be an acceptable replacement for the traditional approach of assigning an arbitrary radial diffusion coefficient to the impurity ions. The model is implemented in the DIVIMP impurity transport code and applied to an L-Mode tungsten divertor experiment on DIII-D. The poloidal electric field is represented as fluctuating between ±1000 V m−1 based on previous measurements. The resulting intermittent vr = E θ × BT transport causes ions to transport both into the core as well as into the far-SOL. Simultaneous agreement with estimates of the W density just inside the separatrix as well as in the far-SOL is obtained (nW ∼ 1014 m−3 and nW ∼ 1012 m−3, respectively). Prompt re-deposition of the W ions was necessary to obtain agreement (fredep ∼ 99%). We conclude that simulating impurity transport using a physics-based approximation for turbulence in the SOL, versus arbitrarily assigning diffusion coefficients, may enable better reactor scale predictions of core impurity contamination. [ABSTRACT FROM AUTHOR]

Behind the nice unification provided by the notion of the level 2.5 in the field of large deviations for time-averages over a long Markov trajectory, there are nevertheless very important qualitative differences between the meaning of the level 2.5 for diffusion processes on one hand, and the meaning of the level 2.5 for Markov chains either in discrete-time or in continuous-time on the other hand. In order to analyze these differences in detail, it is thus useful to consider two types of random walks converging towards a given diffusion process in dimension d involving arbitrary space-dependent forces and diffusion coefficients, namely (i) continuous-time random walks on the regular lattice of spacing b ; (ii) discrete-time random walks in continuous space with a small time-step τ. One can then analyze how the large deviations at level 2.5 for these two types of random walks behave in the limits b → 0 and τ → 0 respectively, in order to describe how the fluctuations of some empirical observables of the random walks are suppressed in the limit of diffusion processes. One can then also study the limits b → 0 and τ → 0 for any trajectory observable of the random walks that can be decomposed on its empirical density and its empirical flows in order to see how it is projected on the appropriate trajectory observable of the diffusion process involving its empirical density and its empirical current. [ABSTRACT FROM AUTHOR]

Anthraquinone-based molecules are promising electroactive materials for use in aqueous organic flow batteries. At high concentrations in aqueous solutions, the well-known negolyte molecule anthraquinone disulfonic acid (AQDS) molecule has been observed to aggregate under near-neutral and acidic conditions. Aggregation has been hypothesized to be directly linked to observed concurrent capacity reduction. In this study, we investigated three different water-soluble anthraquinones in electrolytes of varying compositions and pH to gain further insight into the possible causes of capacity loss. We used low-field benchtop 1H-NMR and diffusion NMR measurements directly in non-deuterated aqueous flow-battery electrolytes to investigate molecular aggregation. Single-cell testing was performed under exhaustive electrolysis conditions to determine the number of electrons exchanged per molecule. We observed a decrease in the number of electrons exchanged per molecule in the presence of carbonate ions due to CO2 adduct formation. The aggregation constants were determined from both concentration-dependent chemical shifts and self-diffusion coefficients. We show that aggregation of the oxidized form of all three molecules studied here occurs under near-neutral and alkaline conditions and does not affect the number of accessible e−. [ABSTRACT FROM AUTHOR]

The transport of energetic charged particles through magnetized plasmas is ubiquitous in interplanetary space and astrophysics, and the important physical quantities are the parallel and perpendicular diffusion coefficients of energetic charged particles. In this paper, the influence of solar wind on particle transport is investigated. Using the focusing equation, we obtain parallel and perpendicular diffusion coefficients, accounting for the solar wind effect. For different conditions, the relative importance of the solar wind effect to diffusion is investigated. It is shown that, when energetic charged particles are close to the Sun, for parallel diffusion, the solar wind effect needs to be taken into account. These results are important for studying energetic charged particle transport processes in the vicinity of the Sun. [ABSTRACT FROM AUTHOR]

An upper bound on Lyapunov exponent of a thermal many body quantum system has been conjectured recently. It would be useful to develop a physical understanding of what prevents a system from violating this bound. In this article we suggest violation of this bound leads to instability. Our suggestion is based on careful scrutiny of the arguments that established the bound. We also present a physical system where this phenomenon is manifested. In the stable regime, along with incoherent metallic phase, the system exhibits another novel phase, where transport is controlled neither by quasi-particles nor by diffusion. At the phase transition, diffusion coefficient, butterfly velocity and Thouless time diverges. [ABSTRACT FROM AUTHOR]

The dimensionless isotope mass scaling experiment between pure Deuterium and pure Tritium plasmas with matched ρ ∗ , ν ∗ , β n , q and T e / T i has been achieved in JET L-mode with dominant electron heating (NBI+ohmic) conditions. 28% higher scaled energy confinement time B t τ E , t h / A is found in favour of the Tritium plasma. This can be cast in the form of the dimensionless energy confinement scaling law as Ω i τ E , t h ∼ A 0.48 ± 0.16 . This significant isotope mass scaling is consequently seen in the scaled one-fluid heat diffusion coefficient A χ e f f / B t which is around 50% lower in the Tritium plasma throughout the whole plasma radius. The isotope mass dependence in the particle transport channel is negligible, supported also by the perturbative particle transport analysis with gas puff modulation. The comparison of the edge particle fuelling or ionisation profiles from the EDGE2D-EIRENE simulations show that the absolute density differences that are necessary for the dimensionless match in the confined plasma dominate over any isotope mass dependencies of particle fuelling and ionization profiles at the plasma edge. Local GENE simulation results indicate a mild anti-gyroBohm effect at ρ t o r = 0.6 and thereby a small isotope mass dependence in favour of Tritium on heat transport and a negligible effect on particle transport. A significant fraction of the isotope scaling and reduced heat transport observed in the Tritium plasma is not captured in the GENE and ASTRA-TGLF-SAT2 simulations by simply changing the isotope mass for the same input profiles. [ABSTRACT FROM AUTHOR]

We report the extended GeV γ -ray emission around the high Galactic latitude supernova remnant DA 530 with the PASS 8 data recorded by the Fermi Large Area Telescope. The γ -ray spectrum in the energy range of 100 MeV–1 TeV follows a power-law model with an index of 2.23. The γ -ray emission, which is much more extended than the radio shell of DA 530, and the spatial coincidence with the molecular cloud suggest that the γ -ray emission could be originated from the hadronic process, where the high-energy protons accelerated in and escaped from the shock of DA 530. With a steady-state injection model of protons, the γ -ray spectrum can be well fitted with the typical Galactic value for the diffusion coefficient and the low-energy content of the total escaped protons. [ABSTRACT FROM AUTHOR]

In this article a nonlocal analogue of an inverse problem in diffuse optical tomography is considered. We show that whenever one has given two pairs of diffusion and absorption coefficients (γ j , q j) , j = 1 , 2 , such that there holds q 1 = q 2 in the measurement set W and they generate the same DN data, then they are necessarily equal in R n and Ω, respectively. Additionally, we show that the condition q 1 | W = q 2 | W is optimal in the sense that without this restriction one can construct two distinct pairs (γ j , q j) , j = 1 , 2 generating the same DN data. [ABSTRACT FROM AUTHOR]

In the overshoot mixing model with an exponentially decreasing diffusion coefficient, the initial value of the diffusion coefficient plays a crucial role. According to the turbulent convective mixing model, the characteristic length of convection in the convection zone differs from that in the overshoot region, resulting in a rapid decrease of the diffusion coefficient near the convective boundary. To investigate this quick decrease, we conducted an asteroseismic study on the intermediate-mass slowly pulsating B-type star KIC 10526294. We generated stellar models with varied input parameters, including the overshoot parameters, and compared the resulting stellar oscillation periods with observations. To mitigate the potential issue arising from large steps in the stellar parameters and stellar age, we employed a comprehensive interpolation scheme for the stellar oscillatory frequencies, considering all stellar parameters and stellar age. Our analysis revealed that the quick decreasing of the diffusion coefficient has discernible effects on the stellar oscillations, and a quick decrease with 4 orders of magnitude shows the best oscillatory frequencies compared with the observations. This provides weak evidence in support of the prediction made by the turbulent convective mixing model. Furthermore, we examined the residuals of the oscillation periods and discovered a potential association between abundance anomalies in the buoyancy frequency profile and the oscillation-like patterns observed in the residuals. [ABSTRACT FROM AUTHOR]

The adsorption and diffusion of hydrogen atoms on Cu(001) are studied using first-principles calculations. By taking into account the contribution of zero-point energy (ZPE), the originally identical barriers are shown to be different for H and D, which are respectively calculated to be ∼158 meV and ∼139 meV in height. Using the transfer matrix method (TMM), we are able to calculate the accurate probability of transmission across the barriers. The crucial role of quantum tunneling is clearly demonstrated at low-temperature region. By introducing a temperature-dependent attempting frequency prefactor, the rate constants and diffusion coefficients are calculated. The results are in agreement with the experimental measurements at temperatures from ∼50 K to 80 K. [ABSTRACT FROM AUTHOR]

In this study, we develop a novel method for determining electron transport coefficients from electron swarm maps measured by a scanning drift-tube experiment. In our method, two types of electron continuity equations that describe either the spatial or the temporal evolution of an electron swarm are discovered in the electron swarm map. The electron transport coefficients can be determined from the coefficients in the discovered equations. Therefore, we can determine the Townsend ionization coefficient, ionization rate coefficient, center-of-mass drift velocity, mean arrival-time drift velocity, longitudinal diffusion coefficient, and longitudinal third-order transport coefficient. These transport coefficients in argon are determined over a wide range of reduced electric fields, E / N, from 29.7 to 1351.6 Td (1 Td = 10−21 Vm2) using our method. We establish that the consideration of high-order transport coefficients, which have been systematically ignored so far, is important for the proper determination of low-order transport coefficients, specifically the electron drift velocity and longitudinal diffusion coefficient, in the presence of ionization growth. [ABSTRACT FROM AUTHOR]

The d -dimensional Ornstein–Uhlenbeck process (OUP) describes the trajectory of a particle in a d -dimensional, spherically symmetric, quadratic potential. The OUP is composed of a drift term weighted by a constant θ ⩾ 0 and a diffusion coefficient weighted by σ > 0. In the absence of drift (i.e. θ = 0), the OUP simply becomes a standard Brownian motion (BM). This paper is concerned with estimating the mean first-exit time (MFET) of the OUP from a ball of finite radius L for large d ≫ 0. We prove that, asymptotically for d → ∞ , the OUP takes (on average) no longer to exit than BM. In other words, the mean-reverting drift of the OUP (scaled by θ ⩾ 0) has asymptotically no effect on its MFET. This finding might be surprising because, for small d ∈ N , the OUP exit time is significantly larger than BM by a margin that depends on θ. As it allows for the drift to be ignored, it might simplify the analysis of high-dimensional exit-time problems in numerous areas. Finally, our short proof for the non-asymptotic MFET of OUP, using the Andronov–Vitt–Pontryagin formula, might be of independent interest. [ABSTRACT FROM AUTHOR]

We present an analysis of γ -ray emission in the direction of supernova remnant (SNR) G15.4+0.1 with 13 yr Fermi Large Area Telescope data. There are three point-like GeV sources in this region: one is spatially coincident with the TeV source HESS J1818-154 and is interpreted as the counterpart of HESS J1818-154. Its γ -ray spectrum can be well fitted by a single power law with an index of 2.3. The other two sources with log-parabola spectra are spatially coincident with dense regions of surrounding molecular clouds revealed by CO observations. Their γ -ray emission originates from hadronic π 0 decay due to inelastic collisions between nuclei in the clouds and cosmic rays accelerated in and escaping from SNR G15.4+0.1. The total energy of the escaping protons is about 1048 erg, assuming a point-like instantaneous injection. However, the inferred diffusion coefficients are lower than the typical Galactic value. [ABSTRACT FROM AUTHOR]

In this work, the porous CoS2/N-doped carbon polyhedra (P-CoS2/CP) has been developed by employing ZIF-67 as the template for durable lithium-ion battery anode. The as-prepared P-CoS2/CP exhibits the novel dodecahedron structure filling with nanopores and CoS2 nanoparticles. As compared to CoS2/CP (122 m2 gâˆ'1), the P-CoS2/CP possesses the higher specific surface area of 367 m2 gâˆ'1, which benefits to enlarge the electrode-electrolyte contact area and promote the Li+ diffusion dynamics at high current density. On the other hand, the CoS2 nanoparticles are firmly wrapped by the carbon skeleton which can effectively suppresses the volume expansion of CoS2 during the charging/discharging process. Besides, the N-doping enable to improve the conductivity of CP. As a result, the initial discharge capacity of P-CoS2/CP at 0.1 A gâˆ'1 is 1484.7 mAh gâˆ'1 with the coulombic efficiency of 48.9%. After 100 cycles, the reversible capacity stabilized at 726.2 mAh gâˆ'1. Even the current density increases to 2.0 A gâˆ'1, a high reversible capacity of 353.7 mAh gâˆ'1 can still be achieved, realizing the good rate capability. The superior Li+ performance of P-CoS2/CP is attributed to the synergistic effect of the unique multi-space structure and the high chemical activity of CoS2. Moreover, the Li+ diffusion coefficient of P-CoS2/CP is 4.52 × 10âˆ'6 to 1.98 × 10âˆ'11 cm2 sâˆ'1, which is higher than that of CoS2/CP (1.45 × 10âˆ'9 to 5.23 × 10âˆ'11 cm2 sâˆ'1), highlighting the significance of porous engineering. [ABSTRACT FROM AUTHOR]

While the electrical models of the membrane-based solid-state nanopores have been well established, silicon-based pyramidal nanopores cannot apply these models due to two distinctive features. One is its 35.3° half cone angle, which brings additional resistance to the moving ions inside the nanopore. The other is its rectangular entrance, which makes calculating the access conductance challenging. Here, we proposed and validated an effective transport model (ETM) for silicon-based pyramidal nanopores by introducing effective conductivity. The impact of half cone angle can be described equivalently using a reduced diffusion coefficient (effective diffusion coefficient). Because the decrease of diffusion coefficient results in a smaller conductivity, effective conductivity is used for the calculation of bulk conductance in ETM. In the classical model, intrinsic conductivity is used. We used the top-down fabrication method for generating the pyramidal silicon nanopores to test the proposed model. Compared with the large error (≥25% in most cases) when using the classical model, the error of ETM in predicting conductance is less than 15%. We also found that the ETM is applicable when the ratio of excess ion concentration and bulk ion concentration is smaller than 0.2. At last, it is proved that ETM can estimate the tip size of pyramidal silicon nanopore. We believe the ETM would provide an improved method for evaluating the pyramidal silicon nanopores. [ABSTRACT FROM AUTHOR]

Objective. Multi-parametric magnetic resonance imaging (MP-MRI) has played an important role in prostate cancer diagnosis. Nevertheless, in the clinical routine, these sequences are principally analyzed from expert observations, which introduces an intrinsic variability in the diagnosis. Even worse, the isolated study of these MRI sequences trends to false positive detection due to other diseases that share similar radiological findings. Hence, the main objective of this study was to design, propose and validate a deep multimodal learning framework to support MRI-based prostate cancer diagnosis using cross-correlation modules that fuse MRI regions, coded from independent MRI parameter branches. Approach. This work introduces a multimodal scheme that integrates MP-MRI sequences and allows to characterize prostate lesions related to cancer disease. For doing so, potential 3D regions were extracted around expert annotations over different prostate zones. Then, a convolutional representation was obtained from each evaluated sequence, allowing a rich and hierarchical deep representation. Each convolutional branch representation was integrated following a special inception-like module. This module allows a redundant non-linear integration that preserves textural spatial lesion features and could obtain higher levels of representation. Main results. This strategy enhances micro-circulation, morphological, and cellular density features, which thereafter are integrated according to an inception late fusion strategy, leading to a better differentiation of prostate cancer lesions. The proposed strategy achieved a ROC-AUC of 0.82 over the PROSTATEx dataset by fusing regions of K trans and apparent diffusion coefficient (ADC) maps coded from DWI-MRI. Significance. This study conducted an evaluation about how MP-MRI parameters can be fused, through a deep learning representation, exploiting spatial correlations among multiple lesion observations. The strategy, from a multimodal representation, learns branches representations to exploit radio-logical findings from ADC and K trans. Besides, the proposed strategy is very compact (151 630 trainable parameters). Hence, the methodology is very fast in training (3 s for an epoch of 320 samples), being potentially applicable in clinical scenarios. [ABSTRACT FROM AUTHOR]

Localization by a broken particleâ€"hole (PH) symmetry in a random system of non-interacting quantum particles is studied on a d -dimensional lattice. Our approach is based on a chiral symmetry argument and the corresponding invariant measure, where the latter is described by a Grassmann functional integral. Within a loop expansion we find for small loops diffusion in the case of PH symmetry. Breaking the PH symmetry results in the creation of random dimers, which suppress diffusion and lead to localization on the scale D / | ÎĽ | , where D is the effective diffusion coefficient at PH symmetry and ÎĽ is the parameter related to PH symmetry breaking. [ABSTRACT FROM AUTHOR]

We study the dynamics of a Brownian motion with a diffusion coefficient which evolves stochastically. We first study this process in arbitrary dimensions and find the scaling form and the corresponding scaling function of the position distribution. We find that the tails of the distribution have exponential tails with a ballistic scaling. We then introduce the resetting dynamics where, at a constant rate, both the position and the diffusion coefficient are reset to zero. This eventually leads to a nonequilibrium stationary state, which we study in arbitrary dimensions. In stark contrast to ordinary Brownian motion under resetting, the stationary position distribution in one dimension has a logarithmic divergence at the origin. For higher dimensions, however, the divergence disappears and the distribution attains a dimension-dependent constant value at the origin, which we compute exactly. The distribution has a generic stretched exponential tail in all dimensions. We also study the approach to the stationary state and find that, as time increases, an inner core region around the origin attains the stationary state, while the outside region still has a transient distributionâ€"this inner stationary region grows ∼ t 2, i.e., with a constant acceleration, much faster than ordinary Brownian motion. [ABSTRACT FROM AUTHOR]

We consider the problem of diffusion with stochastic resetting in a population of random walks where the diffusion coefficient is not constant, but behaves as a power-law of the average resetting rate of the population. Resetting occurs only beyond a threshold distance from the origin. This problem is motivated by physical realizations like soft matter under shear, where diffusion of a walk is induced by resetting events of other walks. We first reformulate in the broader context of diffusion with stochastic resetting the so-called HĂ©braudâ€"Lequeux model for plasticity in dense soft matter, in which diffusivity is proportional to the average resetting rate. Depending on parameter values, the response to a weak external field may be either linear, or non-linear with a non-zero average position for a vanishing applied field, and the transition between these two regimes may be interpreted as a continuous phase transition. Extending the model by considering a general power-law relation between diffusivity and average resetting rate, we notably find a discontinuous phase transition between a finite diffusivity and a vanishing diffusivity in the small field limit. [ABSTRACT FROM AUTHOR]

In this work, a compact model of the diffusive memristor is proposed from the perspective of the transition of electronic transmission mechanisms induced by the dynamics of the filament. First, a new physical model is established based on tunneling mechanisms that are used to fit the experimental data, and the results indicate that it is versatile enough for various diffusive memristors. In addition, the threshold voltage (V th) of the diffusive memristor negatively correlates with the ratio of ionic migration and the diffusion coefficient (u i /Ds), and the hold voltage (V h) positively correlates with the ratio of ionic diffusion and the migration coefficient (Ds/u i), which is useful for the selection of materials to achieve target electrical properties. Furthermore, the different parameters that influence the simulated switching curve are explored. The results indicate that the desired electrical characteristics can be obtained by adjusting these parameters. A compact electrical module model is then built and tested in LTspice to carry out bio-neuron and bio-synaptic performances completely. These simulations demonstrate that the model is reliable for exploring diffusive memristor applications. [ABSTRACT FROM AUTHOR]

In this paper, the thermal diffusion behavior of Fe/Cu/Ni multilayer coatings was investigated by molecular dynamics. The results show that the Fe, Cu, and Ni elements can diffuse each other at 1250 K. Meanwhile, the intrinsic diffusion coefficients and interdiffusion coefficients of the Fe, Cu, and Ni were calculated. Besides, the diffusion mechanism for high melting-point elements of Fe and Ni at 1250 K was analyzed in the paper. According to the simulation result, the Fe and Ni lattices were disturbed by the active Cu particles. Fe and Ni particles at higher energies may move out of their original positions and migrate into the Cu lattice randomly. Thus, the Fe and Ni elements were involved in the thermal diffusion. This can be confirmed by the decrease of the peak and the disappearance of the secondary peak in the radial distribution function curves. However, the position of the curve peaks did not change. Thus, the lattice structure was still maintained during the whole diffusion process. The thermal diffusion of the three elements was carried out by particle substitution at the lattice positions. It was a solid phase diffusion process. Furthermore, there was a clear particle diffusion asymmetry at the original interface of the element. It was consistent with the diffusion asymmetry of diffusion-couple experiments. The primary reason for this diffusion asymmetry was the difference in the interaction potential of the three elements. This asymmetry was ultimately reflected in the intrinsic diffusion coefficient and the interdiffusion coefficient of each element. For the Feâ€"Cuâ€"Ni ternary system, the largest diffusion coefficient was copper and the smallest was iron at 1250 K. [ABSTRACT FROM AUTHOR]

Self-propelled particulate systems manifest certain collective behavior of living matter, which have been the subject of intense research over the past decades. One of the elegant methods for realizing such active motions is by means of custom synthesized Janus particles suspended in a catalytic medium that can be triggered upon illumination by ultraviolet light. In this work, the evolution of the particle dynamics from passive diffusive to active ballistic behavior upon light illumination was probed by multispeckle x-ray photon correlation spectroscopy (XPCS). This technique enables not only studying the emergence of active motions in three dimensions (3D) but also deciphering different contributions to the overall dynamics. Using a combination of homodyne and heterodyne analysis, the ensemble averaged mean velocity, velocity fluctuations and diffusion coefficient of particles were determined in the thermodynamic limit. Results revealed a gradual transition from diffusive to ballistic dynamics with systematic increase of the catalytic activity. At the intermediate region, the dynamics is dominated by Gaussian velocity fluctuations and an enhanced relaxation rate with a weaker wave vector dependence similar to superdiffusive behavior. For the highest activity, the dynamics became purely ballistic with Lorentzian-like distribution of velocity fluctuations. Presented results demonstrate that different aspects of active dynamics can be investigated in 3D over a broad range of PĂ©clet numbers and other control parameters by means of multispeckle XPCS. [ABSTRACT FROM AUTHOR]

Recently an improved nonlinear theory for the transport of energetic particles across a mean magnetic field has been developed. The latter theory is called the field lineâ€"particle decorrelation theory and is the first analytical theory that agrees with test-particle simulations without the need of a correction parameter, nor does the theory contain any other free parameter. In the current paper we derive analytical forms for the ratio of perpendicular and parallel spatial diffusion coefficients Îş ⊥/ Îş ∥ of low-energy particles. In the considered limit the latter ratio is constant meaning that it does not depend on particle energy or rigidity. It is shown that the ratio always has the form Îş ⊥ / Îş ∥ = a 2 δ B x 2 / B 0 2 if a two-dimensional turbulence model is employed. Furthermore, the parameter a 2 depends only on the shape of the turbulence spectrum but not on the magnetic fields. The obtained results can be important for a variety of applications such as studies of solar modulation and diffusive shock acceleration. [ABSTRACT FROM AUTHOR]

Nickel-rich layered oxides (Ni ⩾ 90%) have been recognized as a promising cathode material for Lithium-ion batteries (LIBs) owing to their high energy density and low cost. Herein, we prepared 20 LiNi0.90Co0.06Mn0.04O2 (Ni90) samples with various morphologies by regulating sintering temperature and the lithium to transition metal ratio. The correlation between the synthesis conditions, structural properties, and electrochemical performance of Ni90 materials was thoroughly investigated during the evolution from polycrystal to single crystal. A positive and linear relationship was found between sintering temperature and primary particle size (PPS), which affect the electrochemical performance profoundly. Polycrystals with small PPS show a high discharge capacity and low polarization, while single crystals with large PPS have low discharge capacity but excellent cycling stability. Moreover, the sluggish kinetic properties of Ni90 materials at the end of discharge (a sharp drop in lithium-ion diffusion coefficient at the end of discharge) lead the morphology factors to a critical feature that dominates the total discharge capacity. Taking discharge capacity and cycling stability into integrated consideration, the quasi-single crystal Ni90 materials with moderate PPS and the lowest cation disordering is the first choice. These findings contribute to a better understanding of polycrystalline and single-crystal Nickel-rich cathode materials for LIBs. [ABSTRACT FROM AUTHOR]

The particle diffusion coefficients of TeV pulsar halos observed so far are inferred to be significantly smaller than the typical value of the interstellar medium (ISM). The anisotropic diffusion model ascribes the slow diffusion to the cross-field diffusion, assuming sub-AlfvĂ©nic turbulence in the ISM around the pulsar if the viewing angle between the observer’s line-of-sight (LOS) to the pulsar and the local mean field direction is small. In general, the TeV halo’s morphology under this model highly depends on the viewing angle, and an elongated, asymmetric morphology is predicted if the LOS is not approximately aligned with the local mean field direction. While the specific requirement of a small viewing angle is supposedly established only for a small fraction of TeV halos, TeV halos with apparent asymmetric morphology have not been detected. In this paper, we will study the expectation of TeV halos measured by the TeVâ€"PeV gamma-ray detector LHAASO in the framework of anisotropic diffusion model, with a particular focus on the influence of the viewing angle on the detectability. We show that a TeV halo is more detectable with a smaller viewing angle, and this selection effect may explain why the morphologies of all three detected TeV halos so far are consistent with being spherical. We also demonstrate that LHAASO is capable of detecting asymmetric TeV halos after several years of operation with reasonable source parameters. This can serve as a critical test of the anisotropic diffusion model. [ABSTRACT FROM AUTHOR]

We present a complementary methodology to constrain the total neutrino mass, âˆ' m ν , based on the diffusion coefficient of the splashback mass function of dark matter halos. Analyzing the snapshot data from the Massive Neutrino Simulations, we numerically obtain the number densities of distinct halos identified via the SPARTA code as a function of their splashback masses at various redshifts for two different cases of âˆ' m ν = 0.0 and 0.1 eV. Then, we fit the numerical results to the recently developed analytic formula characterized by the diffusion coefficient that quantifies the degree of ambiguity in the identification of the splashback boundaries. Our analysis confirms that the analytic formula works excellently even in the presence of neutrinos and that the decrement of its diffusion coefficient with redshift is well described by a linear fit, B (z âˆ' z c ), in the redshift range of 0.2 ≤ z ≤ 2. It turns out that the massive neutrino case yields a significantly lower value of B and a substantially higher value of z c than the massless neutrino case, which indicates that the higher the masses that neutrinos have, the more severely the splashback boundaries become disturbed by the surroundings. Given our result, we conclude that the total neutrino mass can in principle be constrained by measuring how rapidly the diffusion coefficient of the splashback mass function diminishes with redshifts at z ≥ 0.2. We also discuss the anomalous behavior of the diffusion coefficient found at lower redshifts for both of the âˆ' m ν cases, and ascribe it to the fundamental limitation of the SPARTA code at z ≤ 0.13. [ABSTRACT FROM AUTHOR]

We explore analytically and numerically agglomeration driven by advection and localized source. The system is inhomogeneous in one dimension, viz along the direction of advection. It is characterized by the kinetic coefficientsâ€"the advection velocity, diffusion coefficient and the reaction kernel, quantifying the aggregation rates. We analyze a simplified model with mass-independent advection velocity, diffusion coefficient, and reaction rates. We also examine a model with mass-dependent coefficients arising in the context of aggregation with sedimentation. For the quasi-stationary case and simplified model, we obtain an exact solution for the spatially dependent agglomerate densities. For the case of mass-dependent coefficients we report a new conservation law and develop a scaling theory for the densities. For the numerical efficiency we exploit the low-rank approximation technique; this dramatically increases the computational speed and allows simulations of very large systems. The numerical results are in excellent agreement with the predictions of our theory. [ABSTRACT FROM AUTHOR]

Dendritic growth is a leading cause of degradation and catastrophic failure of lithium-metal batteries. Deep understanding of this phenomenon would facilitate the design of strategies to reduce, or completely suppress, the instabilities characterizing electrodeposition on the lithium anode. We present a linear-stability analysis, which utilizes the Poisson-Nernst-Planck equations to describe Li-ion transport and, crucially, accounts for the lack of electroneutrality. This allows us to investigate the impact of electric-field gradients near the electrode surface on both ion diffusion and its anisotropy. Our analysis indicates that the use of anisotropic electrolytes (i.e., electrolytes with anisotropic diffusion coefficients of the Li ions) and the control of the local electric field can suppress dendritic growth of lithium metal. Specifically, changes in the local electric field can be used to enhance the longitudinal (perpendicular to the electrode) component of the cation diffusion coefficient tensor, which decreases the maximum growth rate of the dendrites. Electrolytes with electric field-dependent diffusion coefficients would reduce dendritic growth in small batteries, while anisotropic electrolytes (or separators with anisotropic pore structures or columnized membranes) are appropriate for batteries of any size. [ABSTRACT FROM AUTHOR]

Fluxes of negatively charged ligand-coordinated iron, Fe(CN)63/4-, and chromium, CrPDTA1/2−, through two promising commercial cation-exchange membranes, Aquivion E87–05S and Fumasep E-620(K), were measured as functions of current density. The magnitude of the partial current density reached a maximum of∣− ∣ 43 μA cm−2 at the maximum applied current density magnitude of ∣− ∣ 43 mA cm−2 for Fe(CN)6 3/4− transport through Aquivion, or 0.1% of the total current density. Fumasep E-620(K) blocks practically all crossover of both compounds. Both membranes sorb more Fe(CN)6 3/4− and CrPDTA1/2− than predicted by Donnan equilibrium, and low crossover rates can be attributed mainly to slow diffusion, not charge-based rejection of co-ions. The magnitude of the diffusion coefficient appears to correlate with hydraulic permeability. Although Aquivion E87–05S and Fumasep E-620(K) have significant and observable differences in membrane crossover rates, cells built with the DI-soaked membranes offer similarly high coulombic efficiency, indicating the relatively small contribution that crossover makes to inefficiency over a single cycle. [ABSTRACT FROM AUTHOR]

An active bath, made of self-propelling units, is a nonequilibrium medium in which the Einstein relation D = ÎĽk B T between the mobility ÎĽ and the diffusivity D of a tracer particle cannot be expected to hold a priori. We consider here heavy tracers for which these coefficients can be related to correlation functions which we estimate. We show that, to a good approximation, an Einstein relation does hold in an active bath upon using a different temperature which is defined mechanically, through the pressure exerted on the tracer. [ABSTRACT FROM AUTHOR]

The hydroxide-exchange-membrane water electrolyzer (HEMWE) is a promising means to store intermittent renewable energy in the form of hydrogen chemical energy. The hydroxide-exchange ionomer (HEI) in the gas-evolving electrodes and the hydroxideexchange membrane (HEM) are key components of HEMWE. In this work, we simulate the cell and examine explicitly the impact of HEI and HEM properties with a focus on improving HEMWE performance when operated with distilled water (i.e., no supporting electrolyte). The tradeoff between the ionic conductivity gain and electrochemically active surface area (ECSA) loss is studied. For a constant catalyst loading, distributing more catalyst next to the HEM or making thinner but denser catalyst layer is beneficial for HEMWE performance. The results demonstrate that a higher water diffusion coefficient is desired for HEM to supply reactant water to the cathode. In contrast, a lower water diffusion coefficient is preferred for the cathode HEI to retain the water in the regions with high reaction rates. Overall, the findings provide important insights to optimizing HEI/HEM materials for improved HEMWE performance. [ABSTRACT FROM AUTHOR]

A simple and sensitive electrochemical sensor was developed to quantify ciprofloxacin by restricted electro-polymerization of aniline on GCE followed by drop coating functionalized MWCNTs. Electro-catalytic activity of modified electrodes was investigated by EIS and CV revealed decrease in electrode's charge transfer resistance and increase in electron transfer kinetics. Effect of pH and scan rate suggests a mixed adsorption-diffusion process. Tafel slope (plot of ln|ja| or ln|Ia| against E) with linear relationship of potential vs logarithm of current on the linear sweep voltammogram determined the electron transfer coefficient (a). Using the value of (a), number of electrons (n) involved in the rate determining step was obtained. Surface coverage of analyte molecules adsorbed, and diffusion coefficient of ciprofloxacin were estimated from the Laviron and Randles Sevcik equations respectively. Peak current obtained by LSV for various concentrations of ciprofloxacin exhibited two linear ranges, 0.1 µM to 1 µM and 1 µM to 20 µM, with limit of detection 0.08 µM (RSD = 2.4%, S/N = 3). Presence of species existing abundantly in the sample matrix do not affect the sensor signal. Proposed ciprofloxacin sensor demonstrated high reproducibility, long-term stability and fast reaction. The fabricated sensor successfully determined ciprofloxacin in pharmaceutical formulations with recoveries between 92 to 104%. [ABSTRACT FROM AUTHOR]

A new in situ optical microscopy set-up is introduced which allows direct observation of cross-sections of Li-ion full cells in combination with simultaneous recording of electrochemical data. The method is validated by comparison of electrochemical data from coin full cells. Color changes give insights into processes on the electrode and particle level, such as lithiation behavior and electrode thickness changes. Our observations allow the evaluation of (i) the speed of lithiation fronts for LiC12 and LiC6 through anode coatings, (ii) estimation of apparent diffusion coefficients from analysis of the color distribution in single graphite particles, as well as (iii) electrical de-contacting and re-contacting of single graphite particles in connection with (iv) electrode thickness changes. Furthermore, our direct observations from the inside of full cells give indirect insights into aging phenomena such as Li plating and SEI growth. [ABSTRACT FROM AUTHOR]

We consider a Brownian particle with diffusion coefficient D in a d -dimensional ball of radius R with reflecting boundaries. We study the maximum M x (t) of the trajectory of the particle along the x -direction at time t. In the long time limit, the maximum converges to the radius of the ball M x (t) â†' R for t â†' ∞. We investigate how this limit is approached and obtain an exact analytical expression for the distribution of the fluctuations Î"(t) = [ R âˆ' M x (t)]/ R in the limit of large t in all dimensions. We find that the distribution of Î"(t) exhibits a rich variety of behaviors depending on the dimension d. These results are obtained by establishing a connection between this problem and the narrow escape time problem. We apply our results in d = 2 to study the convex hull of the trajectory of the particle in a disk of radius R with reflecting boundaries. We find that the mean perimeter ⟨ L (t)âź© of the convex hull exhibits a slow convergence towards the perimeter of the circle 2 Ď€R with a stretched exponential decay 2 Ď€ R âˆ' ⟨ L (t) âź© ∝ R (D t) 1 / 4 e âˆ' 2 2 D t / R . Finally, we generalise our results to other confining geometries, such as the ellipse with reflecting boundaries. Our results are corroborated by thorough numerical simulations. [ABSTRACT FROM AUTHOR]

Novel insights into the behavior of the diffusion coefficients of charged particles in the inner heliosphere are of great importance to any study of the transport of these particles and are especially relevant with regard to the transport of low-energy electrons. The present study undertakes an exhaustive investigation into the diffusion parameters needed to reproduce low-energy electron intensities as observed at Earth, using a state-of-the-art 3D cosmic ray transport code. To this end, the transport of Jovian electrons is considered, as Jupiter represents the predominant source of these particles in the inner heliosphere, and because a careful comparison of model results with observations taken during periods of good and poor magnetic connectivity between Earth and Jupiter allows for conclusions to be drawn as to both parallel and perpendicular diffusion coefficients. This study then compares these results with the predictions made by various scattering theories. Best-fit parameters for parallel and perpendicular mean free paths at 1 au fall reasonably well within the span of observational values reported by previous studies, but best-fit radial and rigidity dependences vary widely. However, a large number of diffusion parameters lead to reasonable to-good fits to observations, and it is argued that considerable caution must be exercised when comparing theoretical results for diffusion coefficients with diffusion parameters calculated from particle transport studies. [ABSTRACT FROM AUTHOR]

The possibility of silicon electrodeposition from the low-melting LiCl-KCl-CsCl-K2SiF6 electrolytes has been studied. The stability of a silicon-containing additive was studied by cyclic voltammetry, and the rate constant of the chemical reaction of SiF4 release at a temperature of 827 K was calculated. It is determined that the constants of velocity values in the melt based on eutectic composition are 2 orders of magnitude higher, which indicates a higher rate of formation of volatile compounds. Cyclic voltammetry was also used to study the electrochemical behavior of K2SiF6 in the melts under study. It was found that the silicon electroreduction at the cathode is not reversible and proceeds in one 4-electron reaction. The diffusion coefficient calculated by the Matsuda-Ayabe equation was 0.72·10-5 cm²·s-1 at temperature of 823 K. According to the obtained voltammograms, the parameters for the silicon electrodeposition were selected. At a potential of -0.4 V vs QRE, dendritic silicon deposits were obtained. [ABSTRACT FROM AUTHOR]

In nanocomposite electrodes, besides the synergistic effect that takes advantage of the merits of each component, phase interfaces between the components would contribute significantly to the overall electrochemical properties. However, the knowledge of such effects is far from being well developed up to now. The present work aims at a mechanistic understanding of the phase interface effect in C@TiO2 coreâ€"shell nanocomposite anode which is both scientifically and industrially important. Firstly, amorphous C, anatase TiO2 and C@anatse-TiO2 electrodes are compared. The C@anatase-TiO2 shows an obvious higher specific capacity (316.5 mAh gâˆ'1 at a current density of 37 mA gâˆ'1 after 100 cycles) and Li-ion diffusion coefficient (4.0 × 10â€"14 cm2 sâˆ'1) than the amorphous C (178 mAh gâˆ'1 and 2.9 × 10â€"15 cm2 sâˆ'1) and anatase TiO2 (120 mAh gâˆ'1 and 1.6 × 10â€"15 cm2 sâˆ'1) owing to the C/TiO2 phase interface effect. Then, C@anatase/rutile-TiO2 is obtained by a heat treatment of the C@anatase-TiO2. Due to an anatase-to-rutile phase transformation and diffusion of C along the anatase/rutile phase interface, additional abundant C/TiO2 phase interfaces are created. This endows the C@anatase/rutile-TiO2 with further boosted specific capacity (409.4 mAh gâˆ'1 at 37 mA gâˆ'1 after 100 cycles) and Li-ion diffusion coefficient (3.2 × 10â€"13 cm2 sâˆ'1), and excellent rate capability (368.6 mAh gâˆ'1 at 444 mA gâˆ'1). These greatly enhanced electrochemical properties explicitly reveal phase interface engineering as a feasible way to boost the electrochemical performance of nanocomposite anodes for Li-ion batteries. [ABSTRACT FROM AUTHOR]

Acoustofluidicly manipulated microbubbles (MBs) and echogenic liposomes (ELIPs) have been suggested as drug delivery systems for the ‘on demand’ release of drug in target tissue. This requires a clear understanding of their behaviour during ultrasonication and after ultrasonication stops. The main focus of this study is to investigate the behaviour of MBs and ELIPs clusters after ultrasonication stops and the underlaying cause of cluster diffusion considering electrostatic repulsion, steric repulsion and Brownian motion. It also examines the capability of existing models used to predict MBs’ attraction velocity due to secondary radiation force, on predicting ELIPs’ attraction velocity. Tunable resistive pulse sensing (TRPS) and phase analysis light scattering (PALS) techniques were used to measure zeta potentials of the agents and the size distributions were measured using TRPS. The zeta potentials were found to be âˆ'2.43 mV and âˆ'0.62 mV for Definity™ MBs, and âˆ'3.62 mV and âˆ'2.35 mV for ELIPs using TRPS and PALS, respectively. Both agents were shown to have significant cluster formation at pressures as low as 6 kPa. Clusters of both agents were shown to diffuse as sonication stops at a rate that approximately equals the sum of the diffusion coefficients of the agents forming them. The de-clustering behaviours are due to Brownian motion as no sign of electrostatic repulsion was observed and particles movements were observed to be faster for smaller diameters. These findings are important to design and optimise effective drug delivery systems using acoustofluidically manipulated MBs and ELIPs. [ABSTRACT FROM AUTHOR]

The accurate calculation of DC breakdown voltage thresholds solely from elementary electron-neutral interactions in complex gas mixtures using a multi-term Boltzmann equation (BE) kinetic model is demonstrated. SF6:N2 mixtures in the 100 Td < E / N < 400 Td field regime are explored to benchmark the model’s effectiveness. A ten-term BE model is found to yield DC breakdown voltages which, on average, agree within 3% of experimental measurements. A two-term BE model is also applied in order to characterize the error introduced in all calculations by the two-term approximation. These discrepancies are largest in pure N2 where error is greater than 10% for diffusion coefficients, within 6% for particular vibrational rate coefficients, and within 5% for breakdown voltages. However, this error falls to within 1% for most parameters and breakdown voltages in mixtures with large SF6 content. [ABSTRACT FROM AUTHOR]

Using a multi-term solution of the Boltzmann equation and Monte Carlo simulation technique we study behaviour of the third-order transport coefficients for electrons in model gases, including the ionisation model of Lucas and Saelee and modified Nessâ€"Robson model of electron attachment, and in real gases, including N2 and CF4. We observe negative values in the E / n 0-profiles of the longitudinal and transverse third-order transport coefficients for electrons in CF4 (where E is the electric field and n 0 is the gas number density). While negative values of the longitudinal third-order transport coefficients are caused by the presence of rapidly increasing cross sections for vibrational excitations of CF4, the transverse third-order transport coefficient becomes negative over the E / n 0-values after the occurrence of negative differential conductivity. The discrepancy between the two-term approximation and the full multi-term solution of the Boltzmann equation is investigated for electrons in N2 and CF4. While the accuracy of the two-term approximation is sufficient to investigate the behaviour of the third-order transport coefficients in N2, it produces large errors and is not even qualitatively correct for electrons in CF4. The influence of implicit and explicit effects of electron attachment and ionisation on the third-order transport tensor is investigated. In particular, we discuss the effects of attachment heating and attachment cooling on the third-order transport coefficients for electrons in the modified Nessâ€"Robson model, while the effects of ionisation are studied for electrons in the ionisation model of Lucas and Saelee, N2 and CF4. The concurrence between the third-order transport coefficients and the components of the diffusion tensor, and the contribution of the longitudinal component of the third-order transport tensor to the spatial profile of the swarm are also investigated. For electrons in CF4 and CH4, we found that the contribution of the component of the third-order transport tensor to the spatial profile of the swarm between approximately 50 Td and 700 Td, is almost identical to the corresponding contribution for electrons in N2. This suggests that the recent measurements of third-order transport coefficients for electrons in N2 may be extended and generalized to other gases, such as CF4 and CH4. [ABSTRACT FROM AUTHOR]

Spinel LiMn2O4 is a promising cathode material for lithium-ion batteries. However, bulk LiMn2O4 commonly suffers from capacity fading due to the dissolution of Mn into the electrolyte during cycling. Moreover, bulk LiMn2O4 exhibits a low Li+ diffusion coefficient that limits the volume available to Li+ storage. Herein, we report the synthesis of small hollow porous LiMn2O4 nanostructures with a mean size of 51 nm exhibiting exposed (111) planes, assembled by nanoparticles of about 6 nm in size. The morphological features of these nanostructures ensure a large contact area between the material and the electrolyte, shorten the pathways for Li+ diffusion and provide effective accommodation of the volume change during cycling. Therefore, these hollow nanostructures exhibit improved discharge capacity retention (nearly 82% after 200 cycles) and a greater Li+ diffusion coefficient (3.46 × 10−7 cm s−1) compared with that of bulk LiMn2O4. [ABSTRACT FROM AUTHOR]

It is critical to keep a low level of tungsten impurity concentration in the core plasma of the fusion reactor. Using the OEDGE code, the influence on the tungsten concentration due to the cross-field transport in the scrape-off layer is studied. Based on the design parameters of the China Fusion Engineering Test Reactor, the background plasma with the peak target electron temperature of 15 eV is generated using the onion-skin model. The neon impurity with the assumed concentration of 0.2% inside the separatrix is included for estimating the tungsten sputtering source. In a series of simulations of tungsten transport, the diffusion coefficient D⊥ is varied from 0.1 to 10 m2 s−1, and the hypothetical inward pinch velocity VIMP is in the range of 0–5 m s−1. The tungsten concentration inside the separatrix increases with decreasing diffusion coefficient and exceeds 10−5 for the diffusion coefficient lower than about 0.2 m2 s−1. When the hypothetical inward pinch is included, the tungsten concentration increases. The relation between the relative increase in tungsten concentration and VIMP/D⊥ is fitted. [ABSTRACT FROM AUTHOR]

Turbulent transport is widely considered to be the main driver for cross-field transport in the scrape-off layer (SOL) of toroidal magnetized plasmas. Here, reciprocating Langmuir probes are employed to measure both the plasma profiles and the turbulent particle transport in the SOL of the Wendelstein 7-X stellarator. The relation between turbulent radial particle flux Γr and the local pressure gradient is often approximately linear across the entire SOL width, indicating that radial turbulence spreading is absent. This observation holds across a wide range of magnetic configurations and different plasma heating and density scenarios. The magnitude of the turbulent transport for a given gradient reveals a dependence on the magnetic configuration and the position in the SOL, which we relate to the cross-spectral characteristics of multi-tip floating potential measurements. Magnetic islands can add further complexity due to non-monotonic SOL profiles and the breaking of the transport-gradient relation. Finally, anomalous diffusion coefficients are determined from the probe measurements. [ABSTRACT FROM AUTHOR]

Sintering is a fundamental technology for powder metallurgy, the ceramics industry, and additive manufacturing processes such as three-dimensional printing. Improvement of the properties of sintered materials requires prediction of their microstructure using numerical simulations. However, the physical values and material parameters used for such predictions are generally unknown. Data assimilation (DA) enables the estimation of unobserved states and unknown material parameters by integrating simulation results and observational data. In this paper, we develop a new model that couples an ensemble-based four-dimensional variational (En4DVar) DA with a phase-field model of solid-state sintering (En4DVar-PF model) to estimate the state of the sintered material and multiple unknown material parameters. The developed En4DVar-PF model is validated by numerical experiments called twin experiments, in which a priori assumed-true initial state and multiple material parameters are estimated. The results of the twin experiments demonstrate that, using only three-dimensional morphological data of the sintered microstructure, our developed En4DVar-PF model can simultaneously and accurately estimate the particle shape, distribution of grain boundaries, and material parameters, including diffusion coefficients and mobilities related to grain boundary migration. Furthermore, our work identifies criteria for determining appropriate DA conditions such as the observational time interval required to accurately estimate the material parameters using our developed model. The developed En4DVar-PF model provides a promising framework to obtain unobservable states and difficult-to-measure material parameters in sintering, which is crucial for the accurate prediction of sintering processes and for the development of superior materials. [ABSTRACT FROM AUTHOR]

We present an analytic model for the splashback mass function of dark matter halos, which is parameterized by a single coefficient and constructed in the framework of the generalized excursion set theory and the self-similar spherical infall model. The value of the single coefficient that quantifies the diffusive nature of the splashback boundary is determined at various redshifts by comparing the model with the numerical results from the Erebos N-body simulations for the Planck and the WMAP7 cosmologies. Showing that the analytic model with the best-fit coefficient provides excellent matches to the numerical results in the mass range of 5 ≤ M/(1012h−1M⊙) < 103, we employ the Bayesian and Akaike Information Criterion tests to confirm that our model is most preferred by the numerical results compared to previous models at redshifts of 0.3 ≤ z ≤ 3 for both of the cosmologies. We also found that the diffusion coefficient decreases almost linearly with redshift, converging to zero at a certain threshold redshift, zc, whose value significantly differs between the Planck and WMAP7 cosmologies. Our result implies that the splashback mass function of dark matter halos at z ≥ zc is well described by a parameter-free analytic formula and that zc may have the potential to independently constrain the initial conditions of the universe. [ABSTRACT FROM AUTHOR]

In the common spent fuels, actinides and fission products are generally in the form of oxide, so direct dealing with oxide will be the most convenient way for spent fuel reprocessing. In this work, the electrolytic reduction of Gd2O3 has been studied in LiCl-KCl-Li2O (1 wt%) melts at different conditions, and the effect of sintering temperature on the porosity of Gd2O3 powder and the electrochemical behavior of Li2O in LiCl-KCl molten salt were investigated, too. The diffusion coefficient of O2- was calculated to be 2.0 × 10-5 cm²·s-1 in LiCl-KCl melts on the Mo electrode at 923 K by cyclic voltammetry (CV). The electrode process of Gd2O3 powder was also analyzed in LiCl-KCl-Li2O (1 wt%) melts, and the formation process of composite oxide LiGdO2 was determined. By the analysis of XRD and oxygen content characterization, it was suggested that after 74 h electrolysis (923 K, 3.40 V), the oxygen content of Gd2O3 cathode decreased from 12.25 wt% to 1.41 wt%, indicating 88.5% Gd2O3 was reduced to metal. [ABSTRACT FROM AUTHOR]