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The type-II Dirac fermions are characterized by a tilted Dirac cone and sustain exotic quantum transport phenomena. Here, we show the emergence of a type-II Dirac nodal loop in the SrVO 3 / SrTiO 3 quantum well structure by density functional theory calculations and symmetry arguments. When the spin–orbit coupling (SOC) is neglected, the unavoidable crossing between two t 2 g bands gives rise to a nodal loop in the Brillouin zone, which is protected by the mirror symmetry. Such a nodal loop is fully gapped by including SOC, which results in a large spin Hall effect due to large spin Berry curvatures. Our findings add the unexplored functionality to oxide quantum wells and offer a practical platform to explore the interplay between topological fermions and spin transport phenomena. [ABSTRACT FROM AUTHOR]

Motivated by the booming development of spintronics based on quantum dot systems, we employed the standard nonequilibrium Green's function theory to derive the transport formula and the heat generation formula of a quantum dot coupled to a substrate and study the relation between spin current and its accompanying heating or cooling. Our results demonstrate that (i) a thermal bias combined with Zeeman splitting can generate steady spin current in a limited dot level range, while a rotating magnetic field can generate time-average spin current in a global range and pure spin current can induce more heat generation than non-pure spin current; (ii) magnetic resonance of spin current can also effectively enhance heat generation; (iii) appropriate environmental temperature in conjunction with a thermal bias makes cooling, while increasing the frequency of the rotating magnetic can easily give rise to the transition from cooling to heating; and (iv) enhancing the coupling between quantum dots and substrates can effectively reduce heat generation while maintaining the fundamental properties of pure spin current. [ABSTRACT FROM AUTHOR]

The enhancement of thermoelectric properties in CoS b 3 through atom substitution and hydrostatic pressure application is a promising avenue. Herein, we conducted a comprehensive theoretical investigation into the structural, electronic, and thermoelectric characteristics of CoS b 3 − x A x (A = Ge, Se, Te; x = 0.125, 0.250) using density functional theory coupled with Boltzmann transport theory. By subjecting the system to pressures ranging from 0 to 20 GPa and substituting Sb atoms, we evaluated the enthalpy of formation to predict stability, with CoS b 2.875 T e 0.125 exhibiting superior stability under 20 GPa. The bandgap of doped compounds is direct, ranging from 0.33 to 0.56 eV along the Γ point, and was calculated to elucidate electronic properties. Additionally, employing the Slack model, we computed lattice thermal conductivity based on elastic constants to provide a comprehensive analysis of thermoelectric efficiency. Remarkably, our study not only highlights the effect of hydrostatic pressure on structural and electronic properties but also reveals a beneficial impact on increasing Z T values to 2.77 for CoS b 2.750 G e 0.250 at 800 K and 20 GPa, indicating predominantly p -type behavior. [ABSTRACT FROM AUTHOR]

2D Janus Rashba semiconductors, which break both the mirror symmetry in the crystal structure and the spin degeneracy in the energy band, provide a promising platform to optimize thermoelectric performance. Herein, we use first-principles and Boltzmann transport theory to investigate the electron and phonon transport properties for Janus semiconductors of monolayer Si2AsSb and Si2SbBi. The strong Rashba spin-splitting is found in both Janus monolayers especially for Si2SbBi, which decreases the bandgaps and makes the valence bands more dispersive, resulting in decreased p-type Seebeck coefficient and increased p-type electrical conductivity. The lattice thermal conductivities of both monolayers are not low due to the weak phonon anharmonicity, strong chemical bonding, and long phonon relaxation time. The low lattice thermal conductivity of Si2SbBi than Si2AsSb mainly originates from the low phonon group velocity. Both monolayers exhibit better thermoelectric performance in n-type than in p-type. The competition among Seebeck coefficient, electrical conductivity, and electronic thermal conductivity makes the difference of optimal thermoelectric figure of merits in n-type without and with Rashba spin–orbit coupling slight for Si2AsSb, but it is significant for Si2SbBi. Within Rashba spin–orbit coupling, the optimal figure of merits at 700 K reach 0.65 and 0.59 for Si2AsSb and Si2SbBi, respectively, which indicate the potential thermoelectric applications, and will stimulate the broad study on thermoelectric properties of 2D Janus Rashba semiconductors. [ABSTRACT FROM AUTHOR]

The surfaces of many minerals are covered by naturally occurring cations that become partially hydrated and can be replaced by hydronium or other cations when the surface is exposed to water or an aqueous solution. These ion exchange processes are relevant to various chemical and transport phenomena, yet elucidating their microscopic details is challenging for both experiments and simulations. In this work, we make a first step in this direction by investigating the behavior of the native K+ ions at the interface between neat water and the muscovite mica (001) surface with ab-initio-based machine learning molecular dynamics and enhanced sampling simulations. Our results show that the desorption of the surface K+ ions in pure ion-free water has a significant free energy barrier irrespective of their local surface arrangement. In contrast, facile K+ diffusion between mica's ditrigonal cavities characterized by different Al/Si orderings is observed. This behavior suggests that the K+ ions may favor a dynamic disordered surface arrangement rather than complete desorption when exposed to deionized water. [ABSTRACT FROM AUTHOR]

Clathrate hydrates are crystals formed by guest molecules that stabilize cages of hydrogen-bonded water molecules. Whereas thermodynamic equilibrium is well described via the van der Waals and Platteeuw approach, the increasing concerns with global warming and energy transition require extending the knowledge to non-equilibrium conditions in multiphase, sheared systems, in a multiscale framework. Potential macro-applications concern the storage of carbon dioxide in the form of clathrates, and the reduction of hydrate inhibition additives currently required in hydrocarbon production. We evidence porous mesomorphologies as key to bridging the molecular scales to macro-applications of low solubility guests. We discuss the coupling of molecular ordering with the mesoscales, including (i) the emergence of porous patterns as a combined factor from the walk over the free energy landscape and 3D competitive nucleation and growth and (ii) the role of molecular attachment rates in crystallization–diffusion models that allow predicting the timescale of pore sealing. This is a perspective study that discusses the use of discrete models (molecular dynamics) to build continuum models (phase field models, crystallization laws, and transport phenomena) to predict multiscale manifestations at a feasible computational cost. Several advances in correlated fields (ice, polymers, alloys, and nanoparticles) are discussed in the scenario of clathrate hydrates, as well as the challenges and necessary developments to push the field forward. [ABSTRACT FROM AUTHOR]

Among the numerous advantages of the high-power impulse magnetron sputtering (HiPIMS) technique, the most important is the enhanced ionization degree of sputtered species contributing to the film growth. Consequently, the quality of deposited thin films is highly improved. Still, the optimization process is challenging due to the complexity associated with the intricate transport of the sputtered species, ionized or neutrals. The scarce knowledge available on the spatial distribution of these species when operating a HiPIMS discharge makes the quantitative prediction of any deposition feature particularly difficult. In this paper, we discuss the influence of experimentally controllable quantities, such as gas pressure and target current density, on the transport of sputtered titanium in non-reactive (argon) HiPIMS, namely, on the behavior of metal atoms and metal ion fluxes intercepting the substrate. Systematic quantitative measurements were performed in a diameter normal plane on a circular planar target. Hence, the 2D spatial distribution of the ionized flux fraction (IFF) and the total flux of titanium sputtered particles (deposition rate) are evaluated by biasing a quartz crystal microbalance equipped with an electron magnetic filter. The wide range of parameters we examined allows us to predict and optimize the flux of sputtered species based on complete mapping of the IFF of sputtered particles. [ABSTRACT FROM AUTHOR]

The motion of a particle along a channel of finite width is known to be affected by either the presence of energy barriers or changes in the bias forces along the channel direction. By using the lateral equilibrium hypothesis, we have successfully derived the effective diffusion coefficient for soft-walled channels, and the diffusion is found to be influenced by the curvature profile of the potential. A typical phenomenon of diffusion enhancement is observed under the appropriate parameter conditions. We first discovered an anomalous phenomenon of quasi-periodic enhancement of oscillations, which cannot be captured by the one-dimensional effective potential, under the combination of sub-Ohmic damping with two-dimensional restricted channels. We innovatively develop the effective potential and the formation mechanism of velocity variance under super-Ohmic and ballistic damping, and meanwhile, ergodicity is of concern. The theoretical framework of a ballistic system can be reinterpreted through the folding acceleration theory. This comprehensive analysis significantly enhances our understanding of diffusion processes in constrained geometries. [ABSTRACT FROM AUTHOR]

The deviations of cryogenic collector current–voltage characteristics of SiGe heterojunction bipolar transistors (HBTs) from ideal drift-diffusion theory have been a topic of investigation for many years. Recent work indicates that direct tunneling across the base contributes to the non-ideal current in highly scaled devices. However, cryogenic discrepancies have been observed even in older-generation devices for which direct tunneling is negligible, suggesting that another mechanism may also contribute. Although similar non-ideal current–voltage characteristics have been observed in Schottky junctions and were attributed to a spatially inhomogeneous junction potential, this explanation has not been considered for SiGe HBTs. Here, we experimentally investigate this hypothesis by characterizing the collector current ideality factor and built-in potential of a SiGe HBT vs temperature using a cryogenic probe station. The temperature dependence of the ideality factor and the relation between the built-in potential as measured by capacitance–voltage and current–voltage characteristics are in good qualitative agreement with the predictions of a theory of electrical transport across a spatially inhomogeneous junction. These observations suggest that inhomogeneities in the base–emitter junction potential may contribute to the cryogenic non-idealities. This work helps to identify the physical mechanisms limiting the cryogenic microwave noise performance of SiGe HBTs. [ABSTRACT FROM AUTHOR]

We consider a binary mixture of chemically active particles that produce or consume solute molecules and that interact with each other through the long-range concentration fields they generate. We analytically calculate the effective phoretic mobility of these particles when the mixture is submitted to a constant, external concentration gradient, at leading order in the overall concentration. Relying on an analogy with the modeling of strong electrolytes, we show that the effective phoretic mobility decays with the square root of the concentration: our result is, therefore, a nonequilibrium counterpart to the celebrated Kohlrausch and Debye–Hückel–Onsager conductivity laws for electrolytes, which are extended here to particles with long-range nonreciprocal interactions. The effective mobility law we derive reveals the existence of a regime of maximal mobility and could find applications in the description of nanoscale transport phenomena in living cells. [ABSTRACT FROM AUTHOR]

The mesmerizing physical properties of two-dimensional (2D) nanomaterials have resulted in their enormous potential for high-power solar energy conversion and long-term stability devices. The present work systematically investigated the fundamental properties of monolayered 2D group-IV–V materials using a combined approach of first-principles calculations and Boltzmann transport theory, specifically the thermoelectric and optical properties, for the first time. The structural and lattice dynamics analysis disclosed the energetic, dynamical, and mechanical stabilities of 17 out of 25 considered materials. The electronic properties' calculation shows that all the stable materials exhibit a semiconducting nature. Additionally, the energy–momentum relation in a few systems reveals the quartic Mexican-hat-like dispersion in their valence band edges. Owing to the larger depth of Mexican-hat dispersion and the larger height of density step function modes, the hole carrier mobilities of SnN (761.43 m2/Vs), GeN (422.80 m2/Vs), and SiN (108.90 m2/Vs) materials were found to be significantly higher than their electron mobilities at room temperature. The achieved high Seebeck coefficient and electrical conductivity at room temperature result in excellent thermoelectric power factors for GeN (3190 mW/mK2), SiN (1473 mW/mK2), and CAs (774 mW/mK2) materials, manifesting their potential for thermoelectric devices. Further, the calculated optical and solar parameters demonstrate an exceptionally high value (27.25%) of theoretical limits of power conversion efficiency for the SnBi material, making it a suitable candidate as a light-absorbing material in solar cell devices. The present theoretical work filters out the potential 2D group-IV–V materials for solar and heat energy-harvesting devices. [ABSTRACT FROM AUTHOR]

In this work, we calculated the lattice thermal conductivity of monolayer InTe by means of phonon Boltzmann transport theory with first-principles calculated inter-atomic force constants. The higher-order phonon anharmonicity was found to play a strong impact on thermal transport in InTe. With the involvement of the phonon–phonon scattering process up to the fourth-order, the in-plane lattice thermal conductivity of monolayer InTe is 5.1 W m−1 K−1 at room temperature, which is 35% of that considering only third-order force constants. Furthermore, strain was found to be an effective way to manipulate the thermal transport in InTe, which reduces to one half when applying 5% in-plane tensile strain. The strain adjustment is due to the decreases in the phonon group velocity as well as the increase in the phonon scattering rates. These findings can enrich thermal transport properties of group-III monochalcogenides and benefit the material design of thermoelectrics and thermal management electronic devices. [ABSTRACT FROM AUTHOR]

In this series, we outline a strategy for analyzing electrons and muons in gases in crossed electric and magnetic fields using the straightforward transport equations of momentum-transfer theory, plus empirical arguments. The method, which can be carried through from first principles to provide numerical estimates of quantities of experimental interest, offers a straightforward, physically transparent alternative to "off-the-shelf" simulation packages, such as Magboltz and GEANT. In this first article, we show how swarm data for electrons in helium gas subject to an electric field only can be incorporated into the analysis to generate electron swarm properties in helium gas in crossed electric and magnetic fields and to estimate the Lorentz angle in particular. The subsequent articles in the series analyze muons in crossed fields using similar transport theory, though the absence of muon swarm data requires empiricism of quite a different nature. [ABSTRACT FROM AUTHOR]

A first-principles study on the thermoelectric properties of the copper-based ternary phosphide CaCuP is presented. Self-energy relaxation time approximation and unified theory for lattice transport provide an accurate description of electron–phonon and phonon–phonon scattering. Our work provides an atomistic insight into its high thermoelectric performance, highlighting that nano-structuring can increase the thermoelectric figure of merit ZT by reducing the lattice thermal conductivity. [ABSTRACT FROM AUTHOR]

Solid‐state fermentation (SSF) has gained considerable attention due to its potential in the production of bioactive compounds from agroindustrial residues, aligning with circular economy targets. This review examines the core bases involved in SSF with a focus on bioreactor engineering. The review underlines the microorganisms metabolic activities under different operational conditions and focuses on engineering challenges encountered in designing packed‐bed bioreactors, including an analysis of the interaction between microbial growth kinetics and transport phenomena. Finally, given its essential role in the scaling‐up process, this review discusses mathematical modeling developed for SSF in packed‐bed bioreactors, establishing a foundation for the future development of more efficient, scalable, and sustainable SSF‐based applications. [ABSTRACT FROM AUTHOR]

In this article we present an overview of the SMASH hadronic transport approach that is applied for non-equilibrium dynamics of hadrons in heavy-ion collisions. We will give an overview about the ingredients of the approach and the applications for the dynamical description of heavy-ion collisions and for calculations of fundamental properties of the hadron gas. The main emphasis of the article will be the infrastructure for sustainable software development that we have developed over the last 10 years including extensive unit tests and continuous integration. We will also provide one section about the performance of the code and how it can be analyzed and improved in the future. [ABSTRACT FROM AUTHOR]

This report reviews recent progress in computing Kubo formulas for general interacting Hamiltonians. The aim is to calculate electric and thermal magneto-conductivities in strong scattering regimes where Boltzmann equation and Hall conductivity proxies exceed their validity. Three primary approaches are explained. 1. Degeneracy-projected polarization formulas for Hall-type conductivities, which substantially reduce the number of calculated current matrix elements. These expressions generalize the Berry curvature integral formulas to imperfect lattices. 2. Continued fraction representation of dynamical longitudinal conductivities. The calculations produce a set of thermodynamic averages, which can be controllably extrapolated using their mathematical relations to low and high frequency conductivity asymptotics. 3. Hall-type coefficients summation formulas, which are constructed from thermodynamic averages. The thermodynamic formulas are derived in the operator Hilbert space formalism, which avoids the opacity and high computational cost of the Hamiltonian eigenspectrum. The coefficients can be obtained by well established imaginary-time Monte Carlo sampling, high temperature expansion, traces of operator products, and variational wavefunctions at low temperatures. We demonstrate the power of approaches 1–3 by their application to well known models of lattice electrons and bosons. The calculations clarify the far-reaching influence of strong local interactions on the metallic transport near Mott insulators. Future directions for these approaches are discussed. [ABSTRACT FROM AUTHOR]

The present study examines the potential coupling between dipolar dynamics and ionic charge transport in metal‐organic framework (MOF) compounds. MOFs are known for their high porosity and customizable properties. By integrating freely rotating dipolar groups into the ligands, a novel structure, CFA‐25, akin to the known BUT‐2 framework, is synthesized. This facilitated the investigation of local and macroscopic effects, particularly the possible interplay between dipolar units and Cs cations. The research aimed to understand fundamental dipolar dynamics and ionic charge transport, employing Cs ions for their X‐ray diffraction characterizability. Experimental analysis using dielectric spectroscopy, complemented by theoretical simulations, explored questions regarding glassy freezing of re‐orientational dynamics, Cs cation motion within the network, and the influence of dipolar units on transport. Contrary to previous reports, this work finds that Cs transport exhibits substantial barriers, necessitating specialized simulation techniques for accurate characterization. This interdisciplinary approach sheds light on the intricate dynamics of MOFs and offers insights into their potential applications involving ion transport phenomena. [ABSTRACT FROM AUTHOR]

The holographic duality (also known as AdS/CFT correspondence or gauge/gravity duality) postulates that strongly coupled quantum field theories can be described in a dual way in asymptotically anti-de Sitter space. One of the cornerstones of this duality is the description of thermal states as black holes with asymptotically anti-de Sitter boundary conditions. This idea has led to valuable insights into fields such as transport theory and relativistic hydrodynamics. In this context, the quasinormal modes of such black holes play a decisive role, and therefore their stability properties are of utmost interest for the holographic duality. We review recent results using the method of pseudospectra. [ABSTRACT FROM AUTHOR]

Mg3Sb2-based materials, part of the Zintl compound family, are known for their low thermal conductivity but face challenges in thermoelectric applications due to their low energy conversion efficiency. This study addressed these limitations through first-principles calculations using the CASTEP module in Materials Studio 8.0, aiming to enhance the thermoelectric performance of Mg3Sb2 via strategic doping. Density functional theory (DFT) calculations were performed to analyze electronic properties, including band structure and density of states (D.O.S.), providing insights into the influence of various dopants. The semiclassical Boltzmann transport theory, implemented in BoltzTrap (version 1.2.5), was used to evaluate key thermoelectric properties such as the Seebeck coefficient, electrical conductivity, electronic thermal conductivity, and electronic figure of merit (eZT). The results indicate that doping significantly improved the thermoelectric properties of Mg3Sb2, facilitating a transition from p-type to n-type behavior. Bi doping reduced the band gap from 0.401 eV to 0.144 eV, increasing carrier concentration and mobility, resulting in an electrical conductivity of 1.66 × 106 S/m and an eZT of 0.757. Ge doping increased the Seebeck coefficient to −392.1 μV/K at 300 K and reduced the band gap to 0.09 eV, achieving an electronic ZT of 0.859 with low thermal conductivity (11 W/mK). Si doping enhanced stability and achieved an electrical conductivity of 1.627 × 106 S/m with an electronic thermal conductivity of 11.3 W/mK, improving thermoelectric performance. These findings established the potential of doped Mg3Sb2 as a highly efficient thermoelectric material, paving the way for future research and applications in sustainable energy solutions. [ABSTRACT FROM AUTHOR]

Nonlocal models have demonstrated their indispensability in numerical simulations across a spectrum of critical domains, ranging from analyzing crack and fracture behavior in structural engineering to modeling anomalous diffusion phenomena in materials science and simulating convection processes in heterogeneous environments. In this study, we present a novel framework for constructing nonlocal convection–diffusion models using Gaussian‐type kernels. Our framework uniquely formulates the diffusion term by correlating the constant diffusion coefficient with the variance of the Gaussian kernel. Simultaneously, the convection term is defined by integrating the variable velocity field into the kernel as the expectation of a multivariate Gaussian distribution, facilitating a comprehensive representation of convective transport phenomena. We rigorously establish the well‐posedness of the proposed nonlocal model and derive a maximum principle to ensure its stability and reliability in numerical simulations. Furthermore, we develop a meshfree discretization scheme tailored for numerically simulating our model, designed to uphold both the discrete maximum principle and asymptotic compatibility. Through extensive numerical experiments, we validate the efficacy and versatility of our framework, demonstrating its superior performance compared to existing approaches. [ABSTRACT FROM AUTHOR]

The impetus of this paper is to examine the natural convection of low-Prandtl-number fluid flow driven by buoyancy force in a differentially heated enclosure using the single-relaxation-time thermal lattice Boltzmann method owing to the broad range of applications of convective-based problems in industry, such as melting processes as well as energy storage systems. In this study, a proper force term incorporated in the collision operator has been utilized for computer code convergence (especially for Prandtl numbers less than 0.71). The side walls of the geometry are maintained by constant temperatures, Th and Tc, and the upper and lower walls are thermally insulated. The effects of Prandtl ( 0.05 ≤ Pr ≤ 0.71 ) and Rayleigh numbers ( 10 4 ≤ Ra ≤ 5 × 10 5 ) on the temperature fields, streamline functions, and average Nusselt number have been studied and found that at a given Prandtl number, the magnitude of vortices at the corner of the enclosure rises while those could disappear by Prandtl number increase. In addition, in the vicinity of hot and cold walls, the isotherms concentration increases due to rising temperature gradient and Prandtl number. The heat transfer coefficient grows with an increase in Ra and Pr numbers, experiencing a dramatic rise of 66.67% at the hot wall for Pr = 0.1. Similarly, the maximum velocity values near the cold wall rose by 185.71%. The suggested scheme has been validated by results shown in the literature, and excellent agreement has been found. [ABSTRACT FROM AUTHOR]

The thermoelectric properties of monolayered MnBi2Te4 are investigated using first‐principles calculations based on density functional theory (DFT) and Boltzmann transport theory. Our research indicates significant thermoelectric performance in monolayered MnBi2Te4, with a maximum figure of merit (zT$zT$) and power factor (PF${\mathrm{PF}}$) ranging from approximately 3.58 to 9.267 and 0.012 W/K2m${\mathrm{W}}/{\mathrm{K}}^2{\mathrm{\ m}}$ to 0.021 W/K2m${\mathrm{W}}/{\mathrm{K}}^2{\mathrm{\ m}}$ across a temperature range of 300–700 K. The exceptional thermoelectric performance of monolayered MnBi2Te4 can be attributed to its unique structural and electronic properties, which lead to ultralow lattice thermal conductivity and high electrical transport properties. Ultralow lattice thermal conductivity as low as 0.32W/mK$0.32\ {\mathrm{W}}/{\mathrm{m\ K}}$ at 300 K is found in the monolayered MnBi2Te4, which is mainly contributed from the anharmonic scatterings of low‐frequency phonons. And high electronic conductivity and a notable Seebeck coefficient are also observed in our system, which has close relationship with its distinctive electronic band structure. Besides, the two‐dimensional structure makes it a great candidate to holding greater PF by enhancing the quantum confinement. Our findings may lay a strong theoretical groundwork for future experimental inquiries. Subsequent experimental investigations will be crucial to confirm these findings, refine synthesis methods, and explore the practical applications of monolayered MnBi2Te4 in thermoelectric devices. [ABSTRACT FROM AUTHOR]

The research focused on the quaternary Heusler alloys CoFeXGe (with X being Hf or Ta) using a first principles approach via density functional theory and the Wien2k code. The alloys demonstrated a stable ferromagnetic ground state and exhibited negative formation energies, suggesting their experimental synthesis feasibility. Investigation of the electronic properties revealed that both materials are half‐metallic ferromagnets. The calculated indirect band gaps of CoFeHfGe and CoFeTaGe are 1.46 and 0.77 eV, respectively. The mechanical stability of the materials was confirmed through elastic constants analysis. To gain insights into the materials optical behavior and their potential applications in photonics and related fields, correlation of interband optical transitions with electronic band structure was carried out. Finally, Boltzmann transport theory was utilized to evaluate the thermoelectric potential of these alloys over a temperature range extending from 100 to 1000 K. [ABSTRACT FROM AUTHOR]

Developing emerging technologies in Internet of Things and artificial intelligence requires high-speed, low-power, high-sensitivity, and switchable-functionality strain sensors capable of sensing subtle mechanical stimuli in complex ambience. Resonant tunneling diodes (RTDs) are the good candidate for such sensing applications due to the ultrafast transport process, lower tunneling current, and negative differential resistance. However, notably enhancing sensing sensitivity remains one of the greatest challenges for RTD-related strain sensors. Here, we use piezotronic effect to improve sensing performance of strain sensors in double-barrier ZnO nanowire RTDs. This strain sensor not only possesses an ultrahigh gauge factor (GF) 390 GPa−1, two orders of magnitude higher than these reported RTD-based strain sensors, but also can switch the sensitivity with a GF ratio of 160 by adjusting bias voltage in a small range of 0.2 V. By employing Landauer–Büttiker quantum transport theory, we uncover two primary factors governing piezotronic modulation of resonant tunneling transport, i.e., the strain-mediated polarization field for manipulation of quantized subband levels, and the interfacial polarization charges for adjustment of space charge region. These two mechanisms enable strain to induce the negative differential resistance, amplify the peak-valley current ratio, and diminish the resonant bias voltage. These performances can be engineered by the regulation of bias voltage, temperature, and device architectures. Moreover, a strain sensor capable of electrically switching sensing performance within sensitive and insensitive regimes is proposed. This study not only offers a deep insight into piezotronic modulation of resonant tunneling physics, but also advances the RTD towards highly sensitive and multifunctional sensor applications. [ABSTRACT FROM AUTHOR]

The thermoelectric properties of monolayered MnBi2Te4 are investigated using first‐principles calculations based on density functional theory (DFT) and Boltzmann transport theory. Our research indicates significant thermoelectric performance in monolayered MnBi2Te4, with a maximum figure of merit (zT$zT$) and power factor (PF${\mathrm{PF}}$) ranging from approximately 3.58 to 9.267 and 0.012 W/K2m${\mathrm{W}}/{\mathrm{K}}^2{\mathrm{\ m}}$ to 0.021 W/K2m${\mathrm{W}}/{\mathrm{K}}^2{\mathrm{\ m}}$ across a temperature range of 300–700 K. The exceptional thermoelectric performance of monolayered MnBi2Te4 can be attributed to its unique structural and electronic properties, which lead to ultralow lattice thermal conductivity and high electrical transport properties. Ultralow lattice thermal conductivity as low as 0.32W/mK$0.32\ {\mathrm{W}}/{\mathrm{m\ K}}$ at 300 K is found in the monolayered MnBi2Te4, which is mainly contributed from the anharmonic scatterings of low‐frequency phonons. And high electronic conductivity and a notable Seebeck coefficient are also observed in our system, which has close relationship with its distinctive electronic band structure. Besides, the two‐dimensional structure makes it a great candidate to holding greater PF by enhancing the quantum confinement. Our findings may lay a strong theoretical groundwork for future experimental inquiries. Subsequent experimental investigations will be crucial to confirm these findings, refine synthesis methods, and explore the practical applications of monolayered MnBi2Te4 in thermoelectric devices. [ABSTRACT FROM AUTHOR]

We employ advanced first principles methodology, merging self‐consistent phonon theory and the Boltzmann transport equation, to comprehensively explore the thermal transport and thermoelectric properties of KCdAs. Notably, the study accounts for the impact of quartic anharmonicity on phonon group velocities in the pursuit of lattice thermal conductivity and investigates 3ph and 4ph scattering processes on phonon lifetimes. Through various methodologies, including examining atomic vibrational modes and analyzing 3ph and 4ph scattering processes, the article unveils microphysical mechanisms contributing to the low κL within KCdAs. Key features include significant anisotropy in Cd atoms, pronounced anharmonicity in K atoms, and relative vibrations in non‐equivalent As atomic layers. Cd atoms, situated between As layers, exhibit rattling modes and strong lattice anharmonicity, contributing to the observed low κL. Remarkably flat bands near the valence band maximum translate into high PF, aligning with ultralow κL for exceptional thermoelectric performance. Under optimal temperature and carrier concentration doping, outstanding ZT values are achieved: 4.25 (a(b)‐axis, p‐type, 3 × 1019 cm−3, 500 K), 0.90 (c‐axis, p‐type, 5 × 1020 cm−3, 700 K), 1.61 (a(b)‐axis, n‐type, 2 × 1018 cm−3, 700 K), and 3.06 (c‐axis, n‐type, 9 × 1017 cm−3, 700 K). [ABSTRACT FROM AUTHOR]

This study explores the impact of a graphene oxide (GO)/nano silica (NS) hybrid (GO/NS) filler on the diffusion characteristics of natural rubber (NR) composites when exposed to toluene, xylene, and hexane solvents. The lowest solvent uptake is observed for NR GO/NS 3 (3 phr), which is attributed to forming a robust filler network within the composite. The calculation of crosslink density using the Flory‐Rehner equation reveals significantly higher values for NR GO/NS 3, indicating good crosslinking density in the presence of the hybrid filler. Furthermore, molecular mass between crosslinks (Mc) is calculated, demonstrating a favorable fit with the Affine model. The investigation extends to theoretical modeling, where the Korsemeyer–Peppas and Peppas–Sahlin models are employed to predict solvent uptake behavior. Strikingly, the experimental values exhibit a strong alignment with the Peppas–Sahlin model. This comprehensive analysis provides valuable insights into the diffusion behavior of graphene oxide/nano silica (GO/NS) hybrid‐reinforced natural rubber latex in organic solvents, highlighting potential applications in areas such as solvent‐resistant coatings, barrier materials for chemical storage, and enhanced performance in protective gloves and seals used in harsh chemical environments. [ABSTRACT FROM AUTHOR]

The non-uniform suspended sediment flowing into the Yangtze River Estuary (YRE) has a substantial impact on riverbed evolution and the ecological environment. Conducting a numerical simulation can provide missing measurement data and act as an important support for river management. In this study, we developed a formula for determining the non-uniform suspended sediment-carrying capacity (SCC) based on the statistical theory of sediment transport. The formula was applied to a river network model domaining the tidal section of the lower reaches of the Yangtze River (LYR) to simulate the non-uniform suspended sediment flowing into the YRE. The verification results showed that the model accurately simulated fine-grained sediments with a high measurement accuracy. The simulation results for coarsegrained sediments were consistent with riverbed evolution thatmanifests as erosion. Owing to the sediment transport complexity in natural rivers, we propose a method for optimizing calculations of the SCC that providesmore accuratemodeling results and can be adapted when the observational measurement accuracy is improved in the future. These findings provide support for simulations and measurements of non-uniform suspended sediment transported in the LYR. [ABSTRACT FROM AUTHOR]

Environmental DNA (eDNA) offers a novel approach to supplement traditional surveys and provide increased spatial and temporal information on species detection, and it can be especially beneficial for detecting at risk or threatened species with minimal impact on the target species. The transport of eDNA in lotic environments is an important component in providing more informed descriptions of where and when a species is present, but eDNA transport phenomena are not well understood. In this study, we used species-specific assays to detect eDNA from two federally endangered mussels in two geographically distinct rivers. Using the eDNA concentrations measured from field samples, we developed a one-dimensional (1D) hydrodynamic transport model to predict the downstream fate and transport of eDNA. We detected eDNA from both federally endangered mussels across several seasons and flow rates and up to 3.5 km downstream from the source populations, but the detection rates and eDNA concentrations were highly variable across and within rivers and study reaches. Our 1D transport models successfully integrated the variability of the eDNA field samples into the model predictions and overall model results were generally within ±1 standard error of the eDNA field concentration values. Overall, the results of this study demonstrate the importance of optimizing the spatial locations from where eDNA is collected downstream from a source population, and it highlights the need to improve understanding on the shedding mechanisms and magnitude of eDNA from source populations and biogeomorphic processes that influence eDNA transport. [ABSTRACT FROM AUTHOR]

The peristaltic flow with applications of electro-osmotic phenomenon finds novel applications in microfluidic devices, biotechnology, environmental engineering, micro-reactor, and various medical devices. Owing to such motivations in mind, the objective of this analysis is to present the applications of electro-osmotic phenomenon in transport of Prandtl hybrid nanofluid due to non-uniform duct. The characteristics of hybrid nanofluid have been justified by using the single-walled carbon nanotubes (SWCNT) as well as multiple-walled carbon nanotubes (MWCNT) uniformly decomposed to engine oil base liquid. The novel aspects of viscous dissipation and Joule heating effects are attributed. The thermal problem is further influenced by electro-osmotic force. The electric field effects are attributed with the help of Poisson–Boltzmann and Nernst–Planck expressions. The simplification of electric field expressions is done via Debye–Heckle linearization. The problem is modeled under certain constraints of creeping transport and lubrication theory. The novel numerical treatment is performed with the help of Keller Box method. Physical visualization of results is performed for assisting as well as opposing electro-kinetic pumping constraints. It is claimed that the velocity profile increases in the central line of duct with variation of electro-osmotic coefficient. The heat transfer reduces due to potential ratio parameter electro-osmotic constant. Furthermore, the enhancement of Prandtl fluid parameter leads to decrement of axial pressure. [ABSTRACT FROM AUTHOR]

In this article, an extension of a conventional partial discharge (PD) approach called partial discharge echo (PDE), which is applied to different classes of electrical insulation systems of power devices, is presented. Currently, high-voltage (HV) electrical insulation is attributed not only to transmission and distribution grids but also to the industrial environment and emerging segments such as transportation electrification, i.e., electric vehicles, more-electric aircraft, and propulsion in maritime vehicles. This novel PDE methodology extends the conventional and established PD-based assessment, which is perceived to be one of the crucial indicators of HV electrical insulation integrity. PD echo may provide additional insight into the surface conditions and charge transport phenomena in a non-invasive way. It offers new diagnostic attributes that expand the evaluation of insulation conditions that are not possible by conventional PD measurements. The effects of partial discharge echo in various segments of insulation systems (such as cross-linked polyethylene [XLPE] power cable sections that contain defects and a twisted-pair helical coil that represents motor-winding insulation) are shown in this paper. The aim is to demonstrate the echo response on representative electrical insulating materials; for example, polyethylene, insulating paper, and Nomex. Comparisons of the PD echo decay times among various insulation systems are depicted, reflecting dielectric surface phenomena. The presented approach offers extended quantitative assessments of the conditions of HV electrical insulation, including its detection, measurement methodology, and interpretation. [ABSTRACT FROM AUTHOR]

In this work, a comprehensive characterization of microplastic samples collected from unique geographical locations, including the Mediterranean Sea, Strait of Gibraltar, Western Atlantic Ocean and Bay of Biscay utilizing advanced hyperspectral imaging (HSI) techniques working in the short-wave infrared range (1000–2500 nm) is presented. More in detail, an ad hoc hierarchical classification approach was developed and applied to optimize the identification of polymers. Morphological and morphometrical attributes of microplastic particles were simultaneously measured by digital image processing. Results showed that the collected microplastics are mainly composed, in decreasing order of abundance, by polyethylene (PE), polypropylene (PP), polystyrene (PS) and expanded polystyrene (EPS), in agreement with the literature data related to marine microplastics. The investigated microplastics belong to the fragments (86.8%), lines (9.2%) and films (4.0%) categories. Rigid (thick-walled) fragments were found at all sampling sites, while film-type microplastics and lines were absent in some samples from the Mediterranean Sea and the Western Atlantic Ocean. Rigid fragments and lines are mainly made of PE, whereas PP is the most common polymer for the film category. Average Feret diameter of microplastic fragments decreases from EPS (3–4 mm) to PE (2–3 mm) and PP (1–2 mm). The setup strategies illustrate that the HSI-based approach enables the classification of the polymers constituting microplastic particles and, at the same time, to measure and classify them by shape. Such multiple characterization of microplastic samples at the individual level is proposed as a useful tool to explore the environmental selection of microplastic features (i.e., composition, category, size, shape) and to advance the understanding of the role of weathering, hydrodynamic and other phenomena in their transport and fragmentation. [ABSTRACT FROM AUTHOR]

The engineering of biochars with desired morphologies and pore structures is a far-reaching objective towards sustainable pore-dependent environmental technologies, such as water and soil remediation or catalysis. We hereby report a series of experiments that allow the direct following of the shape and porosity of single biochar particles during pyrolysis. Particles ~ 1–2 mm in diameter of unwashed and water-washed raw walnut shells were continuously 3D imaged during pyrolysis to 575 ℃ at a 10 K min−1 in Ar to obtain time- and temperature-resolved x-ray micro computed tomographies to a 0.82 μm resolution. Results showed visual evidence of a 30% and 70% v/v particle shrinkage for unwashed and washed samples, respectively. Particle swelling between 200 and 300 ℃ in the unwashed sample provided evidence of the softening of native biopolymers associated with lignin in untreated biomass. A purpose-defined parameter Λ shows the temperature-dependence of pore re-distribution towards the center of the particle to be linear for both samples. Λ was found to be 3.2 × 10 - 4 K - 1 in the washed sample, approximately 3.5 times faster than in the unwashed one. Such linear dependence is significantly slower than an exponential Arrhenius-like trend thereby providing a qualitative measure of the heat and mass transport phenomena limiting the chemical reactions in the porous medium. This evidence is key to resolving the pathways to the thermochemical decomposition of biomass leading to preparation of precision-engineered biochars. Highlights: Evolution of morphology of single particle (1–2 mm) walnut shell was tracked in operando during pyrolysis via micro-CT (~ 812 nm resolution). Samples pre-washed in water didn't exhibit particle swelling observed in untreated samples in the 200–300 ℃ range. Porosity towards the center of the particle was developed 3.5 faster in washed samples than in unwashed ones. [ABSTRACT FROM AUTHOR]

The ability to solve complex tasks relies on the adaptive changes occurring in the spatio-temporal organization of brain activity under different conditions. Altered flexibility in these dynamics can lead to impaired cognitive performance, manifesting for instance as difficulties in attention regulation, distraction inhibition, and behavioral adaptation. Such impairments result in decreased efficiency and increased effort in accomplishing goal-directed tasks. Therefore, developing quantitative measures that can directly assess the effort involved in these transitions using neural data is of paramount importance. In this study, we propose a framework to associate cognitive effort during the performance of tasks with electroencephalography (EEG) activation patterns. The methodology relies on the identification of discrete dynamical states (EEG microstates) and optimal transport theory. To validate the effectiveness of this framework, we apply it to a dataset collected during a spatial version of the Stroop task, a cognitive test in which participants respond to one aspect of a stimulus while ignoring another, often conflicting, aspect. The Stroop task is a cognitive test where participants must respond to one aspect of a stimulus while ignoring another, often conflicting, aspect. Our findings reveal an increased cost linked to cognitive effort, thus confirming the framework's effectiveness in capturing and quantifying cognitive transitions. By utilizing a fully data-driven method, this research opens up fresh perspectives for physiologically describing cognitive effort within the brain. Author summary: In our daily lives, our brains manage various tasks with different mental demands. Yet, quantifying how much mental effort each task demands is not always straightforward. To tackle this challenge, we developed a way to measure how much cognitive effort our brains use during tasks directly from electroencephalography (EEG) data, which is one of the most used tools to non-invasively measure brain activity. Our approach involved the identification of distinct patterns of synchronized neural activity across the brain, named EEG microstates. By employing optimal transport theory, we established a framework to quantify the cost associated with cognitive transitions based on modifications in EEG microstates. This allowed us to link changes in brain activity patterns to the cognitive effort required for task performance. To validate our framework, we applied it to EEG data collected during a commonly employed cognitive task known as the Stroop task. This task is recognized for challenging us with varying levels of cognitive demand. Our analysis revealed that as the task became more demanding, there were discernible shifts in the EEG microstates. Importantly, these shifts in neural activity patterns corresponded to higher costs associated with cognitive transitions. Our approach offers a promising methodology to assess cognitive effort using neural data, contributing to our comprehension of how the brain manages and adapts to varying cognitive challenges. [ABSTRACT FROM AUTHOR]

Here we show a novel approach to characterize the gas transfer behavior of silicon-oxide (SiO x) coatings and explain the underlying dynamics. For this, we investigate the coating on a nm-scale both by measurement and simulation. Positron annihilation spectroscopy (PAS) and quantum mechanical electronic structure-based molecular dynamics simulations are combined to characterize the porous landscape of SiO x coatings. This approach analyses the influence of micropores smaller than 2 nm in diameter on gas permeation which are difficult to study with conventional methods. We lay out the main pore diameter ranges and their associated porosity estimates. An influence of layer growth on pore size and porosity was found, with an increased energy input during layer deposition leading to smaller pore sizes and a reduced porosity. The molecular dynamics simulations quantify the self-diffusion of oxygen and water vapor through those PAS deducted micropore ranges for hydrophilic and hydrophobic systems. The theoretical pore size ranges are fitting to our PAS results and complete them by giving diffusion coefficients. This approach enables detailed analysis of pore morphology on mass transport through thin film coatings and characterization of their barrier or membrane performance. This is a crucial prerequisite for the development of an exhaustive model of pore dominated mass transports in PECVD coatings. [ABSTRACT FROM AUTHOR]

By using the density functional theory (DFT) in combination with Boltzmann transport theory, the influence of Mg concentrations (x) doping on the thermoelectric properties of Hg 1 − x MgxSe ternary alloys was systematically investigated. The generalized gradient approximations of Perdew–Burke–Ernzerhof (GGA-PBE) have been used to illustrate the exchange correlation potential. The thermodynamic stability of the studied compounds was analyzed in terms of formation energy. Various thermoelectric transport parameters, such as the Seebeck coefficient (S), the thermal conductivity over relaxation time (k/ τ), the electrical conductivity over relaxation time (σ / τ), the power factor (PF) and the figure of merit (ZT) have been deduced and discussed. The obtained results of thermoelectric properties show that the studied materials can be useful for thermoelectric devices at room temperature. It can also be seen that Mg concentrations can increase the thermal efficiency of the HgSe alloy. [ABSTRACT FROM AUTHOR]

Topological semimetals represent a novel class of quantum materials displaying non‐trivial topological states that host Dirac/Weyl fermions. The intersection of Dirac/Weyl points gives rise to essential properties in a wide range of innovative transport phenomena, including extreme magnetoresistance, high mobilities, weak antilocalization, electron hydrodynamics, and various electro‐optical phenomena. In this study, the electronic, transport, phonon scattering, and interrelationships are explored in single crystals of the topological semimetal HfAs2. It reveals a weak antilocalization effect at low temperatures with high carrier density, which is attributed to perfectly compensated topological bulk and surface states. The angle‐resolved photoemission spectroscopy (ARPES) results show anisotropic Fermi surfaces and surface states indicative of the topological semimetal, further confirmed by first‐principle density functional theory (DFT) calculations. Moreover, the lattice dynamics in HfAs2 are investigated both with the Raman scattering and density functional theory. The phonon dispersion, density of states, lattice thermal conductivity, and the phonon lifetimes are computed to support the experimental findings. The softening of phonons, the broadening of Raman modes, and the reduction of phonon lifetimes with temperature suggest the enhancement of phonon anharmonicity in this new topological material, which is crucial for boosting the thermoelectric performance of topological semimetals. [ABSTRACT FROM AUTHOR]

The electrode microstructure in solid oxide fuel cells plays a significant role in transport and reaction phenomena. It requires interconnected pores for gas diffusion and a percolating network for efficient charge transport. Yttria-stabilized zirconia is a commonly used material for electrode scaffolds since it can be structured at the meso/nanoscale for improved performance, besides its high ionic conductivity, stability, and cost-effectiveness balance. However, electrode degradation remains challenging when supplied with hydrocarbons and requires further optimization. This study focuses on developing mesoporous yttria-stabilized zirconia as a precursor for a highly porous scaffold, and its infiltration with copper and cerium solution to obtain the metal-oxide composite Cu–CeO2/YSZ. Two types of symmetrical cells were constructed and analyzed: thin anode cells and thick anode cells. Thin anode cells were useful for selecting the best temperature for heat treatment of the YSZ scaffold, considering its effect on the electrode/electrolyte interface, grain interconnection, and infiltrated phase distribution, as well as how these microstructural features influence electrochemical performance in a methane atmosphere. Cell processing was then optimized by switching to thick anode cells, reducing the electrode resistance by an order of magnitude. These results were compared with those of an electrode scaffold fabricated from commercial YSZ, concluding that the powder mesostructure was crucial in improving electrode microstructure, reducing polarization resistance, and enhancing temporal stability in a direct methane-fueled cell. [ABSTRACT FROM AUTHOR]

Utilizing DFT along with Boltzmann transport theory, the structural, elastic, electrical, optical, and thermoelectric properties of half‐Heusler compound RhTiP have been calculated in principle to examine the pressure effect in the range of 0–40 GPa. As pressure increases, the volume and normalized lattice parameter decreased. In addition to satisfying the Born stability criterion, which ensured the compound RhTiP "natural stability," the zero pressure elastic constants and the pressure‐dependent elastic constants are positive up to 40 GPa. The band structure computations guarantee the semiconductor nature of RhTiP, as demonstrated by the presence of electronic band gap of 1.035 eV at zero pressure. Using the Voigt‐Reuss‐Hill (VRH) averaging scheme under pressure, we have determined the values of this compound's bulk modulus B$$ B $$, shear modulus G$$ G $$, Young's modulus E$$ E $$, Pugh ratio B/G$$ B/G $$, Poisson's ratio v$$ v $$, and anisotropy factor A$$ A $$. Because the bulk modulus responds linearly to pressure, the material's hardness increases as pressure rises. Additionally, under pressures up to 40 GPa, the optical characteristics of RhTiP, including their reflectivity, absorptivity, conductivity, dielectric constant, refractive index, and loss function, were assessed and discussed. Furthermore, the thermoelectric properties are also studied for the materials and supports the tunning of pressure. This study provides a gateway to how the optoelectronic and transport properties of cubic RhTiP could be tuned by employing external pressure. [ABSTRACT FROM AUTHOR]

A key inequality which underpins the regularity theory of optimal transport for costs satisfying the Ma–Trudinger–Wang condition is the Pogorelov second-derivative bound. This translates to an apriori interior C 1 C^{1} estimate for smooth optimal maps. Here we give a new derivation of this estimate which relies in part on Kim, McCann and Warren’s observation that the graph of an optimal map becomes a volume maximizing spacelike submanifold when the product of the source and target domains is endowed with a suitable pseudo-Riemannian geometry that combines both the marginal densities and the cost. [ABSTRACT FROM AUTHOR]

Successive drops of coloured ink mixed with surfactant are deposited onto a thin film of water to create marbling patterns in the Japanese art technique of Suminagashi. To understand the physics behind this and other applications where surfactant transports adsorbed passive matter at gas–liquid interfaces, we investigate the Lagrangian trajectories of material particles on the surface of a thin film of a confined viscous liquid under Marangoni-driven spreading by an insoluble surfactant. We study a model problem in which several deposits of exogenous surfactant simultaneously spread on a bounded rectangular surface containing a pre-existing endogenous surfactant. We derive Eulerian and Lagrangian formulations of the equations governing the Marangoni-driven surface flow. Both descriptions show how confinement can induce drift and flow reversal during spreading. The Lagrangian formulation captures trajectories without the need to calculate surfactant concentrations; however, concentrations can still be inferred from the Jacobian of the map from initial to current particle position. We explore a link between thin-film surfactant dynamics and optimal transport theory to find the approximate equilibrium locations of material particles for any given initial condition by solving a Monge–Ampère equation. We find that as the endogenous surfactant concentration $\delta$ vanishes, the equilibrium shapes of deposits using the Monge–Ampère approximation approach polygons with corners curving in a self-similar manner over lengths scaling as $\delta ^{1/2}$. We explore how Suminagashi patterns may be produced by using computationally efficient successive solutions of the Monge–Ampère equation. [ABSTRACT FROM AUTHOR]

Spin texture in k -space is a consequence of spin splitting due to strong spin–orbit coupling and inversion symmetry breaking. It underlies fertile spin transport phenomena and is of crucial importance for spintronics. Here, we observe the spin texture in k -space of nominally centrosymmetric SrIrO3 grown on NdGaO3 (110) substrates, using non-linear magnetotransport measurements. We demonstrate that the spin texture is not only induced by the interface, which inherently breaks the inversion symmetry in strong spin–orbit coupled SrIrO3 films, but also originates from the film bulk. Structural analysis reveals that thicker SrIrO3 films exhibit a strain gradient, which could be considered as a continuous change in the lattice constant across different layers and breaks the inversion symmetry throughout the entire SrIrO3 films, giving rise to the spin texture in k -space. First-principles calculations reveal that the strain gradient creates large spin-splitting bands, inducing the spin texture with anisotropy, which is consistent with our experimental observations. Our results offer an efficient method for inducing the spin textures in k -space. [ABSTRACT FROM AUTHOR]

In this paper, a kinetic Boltzmann model equation with internal degrees of freedom is established for thermodynamic non-equilibrium multi-component polyatomic gas mixture by using continuous energy levels to deal with rotational energy and vibrational energy. The normalization and conservativeness of the kinetic model are analyzed and proved. Then, numerical algorithm and wall boundary conditions for solving the model equation are given. Then, normal shock-wave structure flow problem and pressure/temperature gradient driven micro-channel flow problem for the two-component gas mixture are used to verify the reliability of the model. The simulation results are in good agreement with those obtained by other methods, which verifies the reliability of the model and algorithm in this paper. Finally, taking 25 N attitude control engine two-dimensional profile as the object, the study for two-dimensional profile nozzle internal and external mixed flow problem is carried out, and the influence of different inlet rarefaction levels on the molecular transports of mixed flow field and the molecular transport phenomena of mixed flow field with different number of components are discussed. [ABSTRACT FROM AUTHOR]

A theoretical analysis of the piezo-viscous dependence of micropolar fluid flow between parallel annular disks has been conducted. It is assumed that viscosity changes exponentially with pressure. Pressure is analytically approximated using a small perturbation method with the viscosity coefficient as the perturbation parameter. Squeeze film time, pressure, and load carrying capacity are calculated and graphically demonstrated across various viscosity–pressure characteristics. The study examines how an increase in cross-viscosity correlates with notable growth in pressure, response time, and bearing load. According to the results, micropolar fluid offers an increase in the load-bearing capacity and therefore lengthens the response time to prevent the contact of parallel annular disks. These observations are useful for bearings, seals, and lubrication systems, where controlling viscosity and pressure is crucial for smooth operation and productivity. As the limiting case of micro-polar fluid when the coupling number tends to zero or the couple stress parameter approaches infinity, without the annular ring, the present derivation agrees well with the Newtonian viscous case of parallel planar squeezing disks described by Bird et al. [Transport Phenomena (John Wiley & Sons, 2006)]. [ABSTRACT FROM AUTHOR]

Lyophobic heterogeneous systems, based on porous fluids made of ordered nanoporous particles immersed in a non-wetting liquid, constitute systems of interest for exploring wetting, drying, and coupled transport phenomena in nanometric confinement. To date, most experimental studies on the forced filling and spontaneous emptying of lyophobic nanometric pores, at pressures of several tens of MPa, have been conducted in a quasi-static regime. However, some studies have shown that dynamical measurements are essential to shed light on the rich physics of these phenomena. We describe here a dynamical calo-porosimeter that allows for the simultaneous mechanical and calorimetric characterization of filling and emptying cycles over four decades of timescales, ranging from a few milliseconds to 10 seconds. This thermally regulated instrument can be operated between −5 and 70°C. It also enables the study of a given porous material successively with different liquids by switching from one to another. The characterization of wetting dynamics, the study of slow kinetics due to changes in solute concentration, and the rapid measurement of the heat of wetting, among other thermal properties, are presented as examples of the possible applications of this apparatus. [ABSTRACT FROM AUTHOR]

An apparatus for explorations of ion transport in a medium and across an interface has been constructed. The ion soft-landing technique is used to deposit low-energy ions onto a pre-adsorbed medium layer on a metal substrate. The designed low-energy ion source can produce a mass-filtered ion beam with tens of nanoampere from solid sources such as bulk metals and salts. The kinetic energy of the ion beam can be lower than 1.0 eV, enabling the ions to be soft-landed onto the medium at the surface. A Kelvin probe with a resolution of less than 32 mV is incorporated to measure the surface potential (SP) variation of the ion-landed sample to monitor the ion transport process in the medium. Temperature-programmed SP measurements on an Ag+-adsorbed ice film prepared on Pt(111) reveal that the temperature threshold for the Ag+-induced SP change of the ice film is about 110 K. The apparatus performance demonstrates its potential in studies of ion transport and related phenomena at both macroscopic and microscopic levels. [ABSTRACT FROM AUTHOR]

The nanofluids provide various benefits over pure fluids in heat and mass transport applications; hence, their research is crucial. For instance, they can increase heat transfer rate by enhancing the fluid's thermal conductivity and may enhance mass transfer rate by changing the surface characteristics. Furthermore, nanofluids are being demonstrated to effectively diminish pressure drops in exchangers for heat, which can lower energy consumption and operating expenses. In the existing literature, the majority of the theoretical studies considered self-similar flows. However, there are certain actual flow situations that do not allow for a self-similar solution. The current study considers such of those situations where the non-similarity of the transport phenomena is unavoidable. The non-similarity of the present problem is caused by the consideration of thermophoretic diffusion or the contribution of viscous dissipation when the wall temperature follows a power-law form. For a pure fluid, the same problem admits a self-similar solution in the absence of viscous dissipation effects. In this problem, the non-similarity is caused by the nature of the thermal transport process and not because of the momentum transport. Therefore, the consideration of viscous dissipation in the boundary layer of nanofluid is an interesting aspect to explore the behavior of thermal and mass transport phenomena. Moreover, the current analysis intends to investigate the transport enhancement in a non-similar flow of a nanofluid by utilizing the Buongiorno model. In the current nonsimilar modeling, possibilities for the existence of a self-similar solution are also highlighted. An implicit finite-difference numerical scheme, the Keller-Box method, is utilized. The problem involves several physical parameters of interest, such as the Eckert number, Lewis number, Brownian motion parameter, and thermophoresis parameter, whose potential impact on the non-similar nature of the problem and on thermal enhancement is analyzed and quantified. [ABSTRACT FROM AUTHOR]

Monte Carlo (MC) simulations are the gold standard for describing various transport phenomena and have largely contributed to the understanding of these processes. However, while their implementation for classical transport governed by exponential step‐length distributions is well‐established, widely accepted approaches are still lacking for the more general class of anomalous transport phenomena. In this work, a set of rules for performing MC simulations in anomalous diffusion media is identified, which is also applicable in the case of finite‐size geometries and/or heterogeneous inclusions. The results are presented in the context of radiative transfer, however their implications extend to all types of anomalous transport. The proposed set of rules exhibits full compatibility with the pathlength invariance property for random trajectories, and with the important radiometric concept of fluence. Additionally, it reveals the counter‐intuitive possibility of introducing interfaces between independent subdomains with identical properties, which arise from the fact that non‐exponential step‐length distributions have a "memory" that can in principle be reset when traversing a boundary. These results have far‐reaching consequences not just for the physical interpretation of the corrections required to handle these discontinuities, but also for their experimental verification, due to their expected effects on the observable pathlength distributions. [ABSTRACT FROM AUTHOR]

The structural, electronic, and transport properties of CaAgAs, a recently predicted topological nodal line semimetal, are investigated using density‐functional theory with spin–orbit coupling (SOC) and Boltzmann transport theory. The material exhibits a topological phase transition from a nodal line semimetal to a topological insulator (TI) phase as a result of the SOC effect. The Voigt–Reuss–Hill approximation is used to compute various mechanical properties. The calculated Seebeck coefficient ≈153.19 μV K−1, power factor ≈5.9 × 1011 W m−1 K−2 s−1, and lattice thermal conductivity ≈6.20 W m−1 K−1 suggest that CaAgAs have superior thermoelectric performance compared to other well‐known predicted thermoelectric materials. The calculated value of figure of merit for without (NSOC) is 0.34, which increases to 0.43 with SOC at 500 K. In these findings, the potential of CaAgAs is reflected as a thermoelectric material, attributed to the topological phase transition induced by SOC. [ABSTRACT FROM AUTHOR]