Search

The analysis of the impact of the star polymer topology on depletion interaction potentials, depletion forces, and monomer density profiles is carried out analytically using field theory methods and techniques as well as molecular dynamic simulations. The dimensionless depletion interaction potentials and the dimensionless depletion forces for a dilute solution of ideal star polymers with three and five legs (arms) in a Θ -solvent confined in a slit between two parallel walls with repulsive surfaces and for the case where one of the surfaces is repulsive and the other inert are obtained. Furthermore, the dimensionless layer monomer density profiles for ideal star polymers with an odd number ( f ˜ = 3, 5) of arms immersed in a dilute solution of big colloidal particles with different adsorbing or repelling properties in respect of polymers are calculated, bearing in mind the Derjaguin approximation. Molecular dynamic simulations of a dilute solution of star-shaped polymers in a good solvent with N = 901 (3 × 300 + 1 -star polymer with three arms) and 1501 (5 × 300 + 1 -star polymer with five arms) beads accordingly confined in a slit with different boundary conditions are performed, and the results of the monomer density profiles for the above-mentioned cases are obtained. The numerical calculation of the radius of gyration for star polymers with f ˜ = 3, 5 arms and the ratio of the perpendicular to parallel components of the radius of gyration with respect to the wall orientation for the above-mentioned cases is performed. The obtained analytical and numerical results for star polymers with an odd number ( f ˜ = 3, 5) of arms are compared with our previous results for linear polymers in confined geometries. The acquired results show that a dilute solution of star polymer chains can be applied in the production of new functional materials, because the behavior of these solutions is strictly correlated with the topology of polymers and also with the nature and geometry of confined surfaces. The above-mentioned properties can find extensive practical application in materials engineering, as well as in biotechnology and medicine for drug and gene transmission. [ABSTRACT FROM AUTHOR]

NiO nanoparticles have garnered significant interest due to their diverse applications and unique properties, which differ markedly from their bulk counterparts. NiO nanoparticles are p-type semiconductors with a wide bandgap, high discharge capacity, and high carrier density, making them ideal for use in batteries, sensors, and catalysts. Their ability to generate reactive oxygen species also imparts disinfectant and antibiotic properties. Additionally, the higher Néel temperature of NiO compared with other antiferromagnetic materials makes it suitable for high-temperature applications in spintronic devices and industrial settings. This review focuses on the critical role of structure and composition in determining the magnetic properties of NiO nanoparticles. It examines how finite-size surface effects, morphology, crystallinity, and nickel distribution influence these properties. Fundamental physical properties and characterization techniques are discussed first. Various synthesis methods and their impact on NiO nanoparticle properties are then explored. Their magnetic phenomenology is examined in detail, highlighting the effects of finite size, particle composition and surface, and crystal quality. The review concludes with a summary of key insights and future research directions for optimizing NiO nanoparticles in technological applications. [ABSTRACT FROM AUTHOR]

The fundamental properties of indium phosphide (InP) doped with tellurium and, subsequently, compensated with copper are considered. Data are presented on the existence of four qualitative patterns of the empirical photoconductivity (PC) spectra of InP:Cu in its own region. Works with semiempirical approximation of the PC of sensitive InP:Cu samples are indicated. It is noted that the PC of IP(α()) was analytically approximated as a function of the experimentally obtained spectral dependence of the absorption coefficient of InP. Five approximating functions are proposed in order to obtain an analytical dependence of the absorption coefficient of InP α(). Five dependencies with different values of the standard deviation are obtained. Based on the analytical dependencies, the complete analytical dependence of IP(α()) is modeled. Similarly, five dependencies are obtained, characterized by the corresponding value of the standard deviation. Five nonstationary PC surfaces of IP (as a function of two variables: absorption coefficient, as a function of photon energy, and sample exposure time under normal conditions) are constructed. A conclusion is made about the choice of the most mathematically accurate and physically meaningful approximating function α(). Accordingly, it is shown that this dependence is optimal for obtaining based on it (including this dependence in the structure of IP = f(α) and α = f()) a complete analytical description of the PC process. It is shown that subsequent studies can be aimed at explaining the physical bases of PC in the short-wave region of the fundamental transitions of InP and studying methods of influencing the surface layer of InP:Cu, with the aim of sensitizing and stabilizing it. [ABSTRACT FROM AUTHOR]

In the current paper, hygro-thermo-magnetically induced vibrations of small-scale viscoelastic tubes containing flow with a spin motion under gravity and tangential loads are analyzed by including surface effects. The dynamic equations are derived in the framework of the modified nonlocal elasticity theory (NET) and Rayleigh beam model. The Galerkin method and Laplace transformation are implemented to solve model equations. Vibration frequencies, stability boundaries, and Campbell diagrams of the system are acquired. Impacts of influential parameters such as scale rotary inertia factor, scale parameter, viscoelastic materials, gravity and tangential loads, flow and spin velocities, geometrical properties, and environmental conditions on the stability of the structure are examined. Also, the obtained results are compared for the Rayleigh and Euler-Bernoulli (EB) beam models. The golden results of this work are that by fine-adjusting the scale parameter and magnetic intensity in the system, destructive effects of hygro-thermal loads can be dampened. Besides, the increment of the rotary inertia factor and nanotube thickness induces destabilizing effect on the system. [ABSTRACT FROM AUTHOR]

In the current paper, size‐dependent mechanical analysis of functionally graded porous (FGP) nanobeams resting on Pasternak foundation in thermal environment is presented based on nonlocal strain gradient theory and Gurtin‐Murdoch surface elasticity theory. The nanobeam is modeled based on Euler‐Bernoulli beam theory, Timoshenko beam theory and Reddy's third‐order shear deformation theory and the set of the governing equations are solved for a clamped‐clamped FGP nanobeam using generalized differential quadrature method. Numerical results show that as porosity parameter increases, static deflection increases and critical buckling load decreases, but its effect on the fundamental frequency strongly depends on the porosity distribution pattern. It was revealed that among all studied porosity distribution patterns, the minimum value of the static deflection and maximum values of critical buckling load and fundamental frequency can be achieved using symmetric distribution pattern of pores. It is concluded that tensional residual stress reduces static deflection and increases both critical buckling load and fundamental frequency and temperature rise has reverse effects. [ABSTRACT FROM AUTHOR]

NiO nanoparticles have garnered significant interest due to their diverse applications and unique properties, which differ markedly from their bulk counterparts. NiO nanoparticles are p-type semiconductors with a wide bandgap, high discharge capacity, and high carrier density, making them ideal for use in batteries, sensors, and catalysts. Their ability to generate reactive oxygen species also imparts disinfectant and antibiotic properties. Additionally, the higher Néel temperature of NiO compared with other antiferromagnetic materials makes it suitable for high-temperature applications in spintronic devices and industrial settings. This review focuses on the critical role of structure and composition in determining the magnetic properties of NiO nanoparticles. It examines how finite-size surface effects, morphology, crystallinity, and nickel distribution influence these properties. Fundamental physical properties and characterization techniques are discussed first. Various synthesis methods and their impact on NiO nanoparticle properties are then explored. Their magnetic phenomenology is examined in detail, highlighting the effects of finite size, particle composition and surface, and crystal quality. The review concludes with a summary of key insights and future research directions for optimizing NiO nanoparticles in technological applications.

1D organic metal halide hybrids (OMHHs) exhibit strongly anisotropic optical properties, highly efficient light emission, and large Stokes shift, holding promise for novel photodetection and lighting applications. However, the fundamental mechanisms governing their unique optical properties and in particular the impacts of surface effects are not understood. Herein, 1D C4N2H14PbBr4 by polarization-dependent time-averaged and time-resolved photoluminescence (TRPL) spectroscopy, as a function of photoexcitation energy, is investigated. Surprisingly, it is found that the emission under photoexcitation polarized parallel to the 1D metal halide chains can be either stronger or weaker than that under perpendicular polarization, depending on the excitation energy. The excitation-energy-dependent anisotropic emission is attributed to fast surface recombination, supported by first-principles calculations of optical absorption in this material. The fast surface recombination is directly confirmed by TRPL measurements, when the excitation is polarized parallel to the chains. The comprehensive studies provide a more complete picture for a deeper understanding of the optical anisotropy in 1D OMHHs.

Based on the surface elasticity theory combined with the theories of Kirchhoff plate and Mindlin plate, the influences of surface effects on the buckling and post-buckling behaviors of nano-laminates are studied. Analytical solutions for critical buckling loads under uniaxial and biaxial compressions are obtained. Furthermore, approximate solutions for critical post-buckling loads under moveable and immoveable edge conditions are provided by using the Galerkin's method. Numerical examples are given to study the influences of thickness, number of layers, surface parameters and the length of the nano-laminates on buckling and post-buckling critical loads. Results obtained indicate that the surface/interface energy is connected with the number of layers. In addition, the effects of the surface/interface energy on the critical loads enhance through increasing the length of the laminates but reduce by increasing the thickness. Mechanical model, analytical method and conclusions of this work are helpful for designing and examining the stability of the nano-laminates and nanoscale devices. [ABSTRACT FROM AUTHOR]

Abstract Nano-switch structures are important control elements in nanoelectromechanical systems and have potential applications in future nanodevices. This paper analyzes the effects of surface effects, geometric nonlinearity, electrostatic forces, and intermolecular forces on the nonlinear bending behavior and adhesion stability of nano-switches. Based on the Von Karman geometric nonlinearity theory, four types of boundary conditions for the nano-switch structure were specifically calculated. The results show that surface effects have a significant impact on the nonlinear bending and adhesion stability of nano-switches. Surface effects increase the adhesion voltage of the nano-switch and decrease its adhesion displacement, and as the size of the nano-switch structure increases, the impact of surface effects decreases. A comparative analysis of the linear theory and the nonlinear theory results shows that the adhesion voltage predicted by the linear theory is smaller than that predicted by the nonlinear theory. The effect of geometric nonlinearity increases as the size of the nano-switch structure increases, as the distance between the electrodes increases, and as the aspect ratio of the nano-switch structure increases. These findings provide theoretical support and reference for the design and use of future nanodevices and nanoelectromechanical systems.

Nanotubes could be fabricated in different shapes for various applications, as they have the possibility of changing curvature. Vibration and stability of a curved nanotube conveying fluid and nanoparticle are investigated considering surface and non-local effects. The surface effects are considered in the nanotube inner and outer layers. The obtained equation is discretized using the Galerkin method. The main parameter effects on the stability and the first two modes are illustrated, including the total opening angle, the nanoparticle mass-ratio, the non-local parameter, the surface-effects parameter, and the nanoparticle position. They show significant effects on the dynamic behavior of the nanostructure. [ABSTRACT FROM AUTHOR]

Within the context of Gurtin–Murdoch surface elasticity theory, closed-form analytical solutions are derived for an isotropic elastic half-plane subjected to a concentrated/uniform surface load. Both the effects of residual surface stress and surface elasticity are included. Airy stress function method and Fourier integral transform technique are used. The solutions are provided in a compact manner that can easily reduce to special situations that take into account either one surface effect or none at all. Numerical results indicate that surface effects generally lower the stress levels and smooth the deformation profiles in the half-plane. Surface elasticity plays a dominant role in the in-plane elastic fields for a tangentially loaded half-plane, while the effect of residual surface stress is fundamentally crucial for the out-of-plane stress and displacement when the half-plane is normally loaded. In the remaining situations, combined effects of surface elasticity and residual surface stress should be considered. The results for a concentrated surface force serve essentially as fundamental solutions of the Flamant and the half-plane Cerruti problems with surface effects. The solutions presented in this work may be helpful for understanding the contact behaviors between solids at the nanoscale. [ABSTRACT FROM AUTHOR]

Nano-switch structures are important control elements in nanoelectromechanical systems and have potential applications in future nanodevices. This paper analyzes the effects of surface effects, geometric nonlinearity, electrostatic forces, and intermolecular forces on the nonlinear bending behavior and adhesion stability of nano-switches. Based on the Von Karman geometric nonlinearity theory, four types of boundary conditions for the nano-switch structure were specifically calculated. The results show that surface effects have a significant impact on the nonlinear bending and adhesion stability of nano-switches. Surface effects increase the adhesion voltage of the nano-switch and decrease its adhesion displacement, and as the size of the nano-switch structure increases, the impact of surface effects decreases. A comparative analysis of the linear theory and the nonlinear theory results shows that the adhesion voltage predicted by the linear theory is smaller than that predicted by the nonlinear theory. The effect of geometric nonlinearity increases as the size of the nano-switch structure increases, as the distance between the electrodes increases, and as the aspect ratio of the nano-switch structure increases. These findings provide theoretical support and reference for the design and use of future nanodevices and nanoelectromechanical systems. [ABSTRACT FROM AUTHOR]

AbstractThe present article deals with the application of refined plate theory and surface effects to investigate the nonlocal free vibration behavior of a functionally graded nano-plate composed of two piezoelectric face sheets resting on Orthotropic Visco-Pasternak. Surface and nonlocal effects are applied using the surface piezoelectricity and stress-strain gradient theories. Surface effects, refined quasi-3D higher-order theory, neutral surface position and in-plane mechanical preloads are considered to study piezoelectric sandwich nano-plate with a functionally graded core in this study for the first time, simultaneously. The size-dependent governing equations are derived based on 2D and 3D refined theory using Hamilton’s principle and different boundary conditions are studied and investigated according to the semi-analytical solution method. Comparing the results of the vibration behavior of 2D and quasi-3D models, local and non-local models, and also, examining different foundations simultaneously can be said as one of the innovations of the current research. Finally, a parametric study is presented to examine the effects of different parameters such as surface effects, small scale parameters, mechanical preloads, thickness stretching effects, neutral surface position, non-homogeneous coefficient, applied voltage, different foundation constants, boundary conditions, geometrical ratios and different theories in details. It is indicated that the inclusion of surface effects and thickness stretching effects leads to a significant influence on the vibration behavior of three-layered nano-scale plates. The presented results in this article may provide useful guidance for the design and development of the next generation of nano-devices. [ABSTRACT FROM AUTHOR]

Creating routes across open areas is challenging due to the absence of a defined routing network and the complexity of the environment, in which multiple criteria may affect route choice. In the context of urban environments, research has found Visibility and Spider-Grid subgraphs to be effective approaches that generate realistic routes. However, the case studies presented typically focus on plazas or parks with defined entry and exit points; little work has been carried out to date on creating routes across open areas in rural settings, which are complex environments with varying terrain and obstacles and undefined entry or exit points. To address this gap, this study proposes a method for routing across open areas based on a Spider-Grid subgraph using queen contiguity. The method leverages a Weighted Sum–Dijkstra's algorithm to allow multiple criteria such as surface condition, total time, and gradient to be considered when creating routes. The method is tested on the problem of routing across two areas of Dartmoor National Park, United Kingdom. The generated routes are compared with benchmark algorithms and real paths created by users of the Ordnance Survey's Maps App. The generated routes are found to be more realistic than those of the benchmark methods and closer to the real paths. Furthermore, the routes are able to bypass hazards and obstacles while still providing realistic and flexible routes to the user. [ABSTRACT FROM AUTHOR]

The interplay of diffusion with phenomena like stochastic adsorption–desorption, absorption, and reaction–diffusion is essential for life and manifests in diverse natural contexts. Many factors must be considered, including geometry, dimensionality, and the interplay of diffusion across bulk and surfaces. To address this complexity, we investigate the diffusion process in heterogeneous media, focusing on non-Markovian diffusion. This process is limited by a surface interaction with the bulk, described by a specific boundary condition relevant to systems such as living cells and biomaterials. The surface can adsorb and desorb particles, and the adsorbed particles may undergo lateral diffusion before returning to the bulk. Different behaviors of the system are identified through analytical and numerical approaches. [ABSTRACT FROM AUTHOR]

We report an unusual case of carcinoma ex pleomorphic adenoma (CXPA) in the submandibular gland. The mass had a unique calcification. Panoramic tomography revealed sponge-like calcification. The central portion displayed heterogeneous high signal intensity on T1-weighted image (T1WI) and T2-weighted image (T2WI), and heterogeneously moderate signal intensity on a short-TI inversion recovery (STIR) image. The ADC was low (0.78 × 10−3mm2/sec). After surgical excision, a pathological examination revealed that the mass contained CXPA as a minor component. Tumor cells with large hyperchromatic nuclei and eosinophilic or clear cytoplasm proliferated in irregular small tubule formations or cribriform or Roman-bridge structures in hyalinized or focally ossified stroma. The entire mass was calcified, particularly in the central region. Taken together, the reduced T1 relaxation times were related to the surface effects of diamagnetic particles, which were observed at calcium particle concentrations of up to 30%. We report a CXPA with unusual sponge-like calcification, which appeared unusually hyperintense on T1WI due to a surface effect. [ABSTRACT FROM AUTHOR]

Zinc oxide is a promising material for the creation of various types of sensors, in particular UV detectors. In this work, arrays of ordered nanorods were grown by chemical vapor deposition. The effect of environmental humidity on the sensing properties of zinc oxide nanorod arrays was investigated, and a prototype UV sensor using indium as an ohmic contact was developed. UV photoresponses were measured for the samples stored in dry and wet atmospheres. The increase in sensitivity and response of the ZnO nanorod arrays was observed after prolonged exposure to a wet atmosphere. A model was proposed to explain this effect. This is due to the formation of hydroxyl groups on the surface of zinc oxide nanorods, which is confirmed by FTIR spectroscopy data. For the first time, it has been shown that after storage in a wet atmosphere, the sensory properties of the structure remain stable regardless of the ambient humidity. [ABSTRACT FROM AUTHOR]

Purpose: The scale-dependent forced and free vibrational behaviors of a nanobeam located on variable elastic foundations subjected to a transverse moving load and an axial tensile force are analyzed based on the nonlocal Rayleigh beam theory. Meanwhile, a comprehensive parametric investigation is accomplished to elucidate the impacts of various system parameters, such as geometry, foundation coefficients, rotational inertia factor, surface energy, and hygro-thermo-magnetic fields on the dynamical response of the nanobeam. Methods: The dynamical equation of the system is derived by considering linear, parabolic, and sinusoidal distributions for the elastic foundation. Employing the Galerkin discretization technique and eigenvalue analysis, the vibrational frequencies of the system are determined numerically. The dynamical response of the system is also acquired analytically. Results: The critical velocity of the moving load and the dynamical amplification factor for the forced vibration of the system are computed. In addition, the conditions of the cancellation phenomenon and the maximum amplitude of free vibration are determined. The outcomes indicated that, in contrast to the effects of axial tensile force and elastic foundations, the critical velocity of the moving load decreases with increasing the nonlocal parameter and the rotational inertia factor. Moreover, it is inferred that the cancellation velocities of the moving load can be increased by exerting a magnetic field and increasing the length-to-thickness ratio of nanobeams. Conclusions: The findings reveal that considering the impacts of the surface energy, rotational inertia factor, and environmental conditions is essential to the dynamical analysis of small-scale structures under traveling loads. [ABSTRACT FROM AUTHOR]

Porous silicon (por-Si) is a complex multiphase material, the composition and functional properties of which greatly depend on the features of its formation. In this work, samples of porous silicon with porosity indices from 5 to 80% are obtained by electrochemical etching and their photoluminescence properties are studied. The porosity of the samples is varied by changing the current density of electrochemical anodization during the etching process. The porosity index is calculated according to the X-ray reflectometry method. The aim of our work is to establish correlations between the porosity index, composition, intensity, and mechanism of porous-silicon photoluminescence. The surface composition is controlled by ultrasoft X‑ray spectroscopy and infrared spectroscopy. An increase in the degree of oxidation of the surface of the samples with an increase in the porosity index is shown. Two well-known mechanisms of porous silicon photoluminescence associated with the composition and morphology of the surface are found, and it is established at which porosity values they prevail. It is shown that an increase in the porosity index leads to an increase in the intensity of photoluminescence. [ABSTRACT FROM AUTHOR]

The analysis of the impact of the star polymer topology on depletion interaction potentials, depletion forces, and monomer density profiles is carried out analytically using field theory methods and techniques as well as molecular dynamic simulations. The dimensionless depletion interaction potentials and the dimensionless depletion forces for a dilute solution of ideal star polymers with three and five legs (arms) in a Θ-solvent confined in a slit between two parallel walls with repulsive surfaces and for the case where one of the surfaces is repulsive and the other inert are obtained. Furthermore, the dimensionless layer monomer density profiles for ideal star polymers with an odd number (f˜ = 3, 5) of arms immersed in a dilute solution of big colloidal particles with different adsorbing or repelling properties in respect of polymers are calculated, bearing in mind the Derjaguin approximation. Molecular dynamic simulations of a dilute solution of star-shaped polymers in a good solvent with N = 901 (3 × 300 + 1 -star polymer with three arms) and 1501 (5 × 300 + 1 -star polymer with five arms) beads accordingly confined in a slit with different boundary conditions are performed, and the results of the monomer density profiles for the above-mentioned cases are obtained. The numerical calculation of the radius of gyration for star polymers with f˜ = 3, 5 arms and the ratio of the perpendicular to parallel components of the radius of gyration with respect to the wall orientation for the above-mentioned cases is performed. The obtained analytical and numerical results for star polymers with an odd number (f˜ = 3, 5) of arms are compared with our previous results for linear polymers in confined geometries. The acquired results show that a dilute solution of star polymer chains can be applied in the production of new functional materials, because the behavior of these solutions is strictly correlated with the topology of polymers and also with the nature and geometry of confined surfaces. The above-mentioned properties can find extensive practical application in materials engineering, as well as in biotechnology and medicine for drug and gene transmission.

The catalyst surface was processed in the high-voltage electrical discharge device in oxygen environment. Continuous active oxide centers formed on the surface and complete filling of the surface with oxygen occur, and its thermo-physical properties, thermo-luminescence curves, scanning electron microscope and ESR spectrometers were studied. It was determined that the activity of the catalyst at values of the absorbed dose D ≤ 2 1 kGy is many times higher than that of conventional catalysts. Thus, due to the sorption volume of the surface, the volume of the product formed in the liquid phase increases by 1.6 times. [ABSTRACT FROM AUTHOR]

In this paper, a piezoelectric phononic crystal beam at the nanoscale has been mechanically modeled by using the surface piezoelectric theory. The band gap has been calculated by the plane wave expansion method and the band gap structure picture has been analyzed. The influence of electromechanical coupling effects, surface effects and geometry on the band gap properties are discussed separately. This study contributes positively to the design and active control of nanoelectromechanical systems. [ABSTRACT FROM AUTHOR]

In this work, we propose a continuum theoretical model to describe the surface-modulated and size-dependent elastic properties of nanofilms. The influence of surface Young's modulus (surface biaxial modulus) decreases with increasing the distance from the film surface. The decrease law is assumed as exponential in this work. In core-surface and core-shell models, an imaginary interface between the surface area and bulk-like inner core appears. Since the influence of surface elasticity decreases with the distance from the surface layer continually, the interface is non-existent and non-physical. The present theoretical model eliminates the interface and is proved to be a veritable continuum theory. There is no concept of "bulk-like core area" and "surface area" in current theory. The existence of surface Young's modulus decrease introduces second and third surface modifications. When the influence of surface Young's modulus decreases rapidly, i.e. the decrease factor α → ∞, the influence of surface Young's modulus only works near the surface. And then, the current theory will degenerate into a core-surface one. The current theory is used to describe the size-dependent biaxial modulus of Si, diamond, Au and Cu nanofilms. The theoretical prediction gives good agreement with simulated results of these nanofilms. The present study in this paper is envisaged to provide useful insights for the design and application of nanofilm-based devices. [ABSTRACT FROM AUTHOR]

A model of piezoelectric phononic crystal (PC) double-layer nanobeam periodically attached by "spring-mass" resonators is proposed. As a comparison, two other simplified models are also proposed. In order to calculate the band structure, the plane wave expansion (PWE) method is improved by introducing the Euler beam and surface piezoelectricity theories. All the results and analysis demonstrate that the tunable advantage is displayed in double-layer nanobeam on account of the antisymmetric and symmetric vibrational modes controlled by adding additional springs between two different nanobeams. Moreover, the influencing rules of parameters related to additional spring and "spring-mas" resonator are also revealed. The bandgap properties can be applied to nano electro-mechanical system (NEMS) to realize active control of vibration. [ABSTRACT FROM AUTHOR]

Creating routes across open areas is challenging due to the absence of a defined routing network and the complexity of the environment, in which multiple criteria may affect route choice. In the context of urban environments, research has found Visibility and Spider-Grid subgraphs to be effective approaches that generate realistic routes. However, the case studies presented typically focus on plazas or parks with defined entry and exit points; little work has been carried out to date on creating routes across open areas in rural settings, which are complex environments with varying terrain and obstacles and undefined entry or exit points. To address this gap, this study proposes a method for routing across open areas based on a Spider-Grid subgraph using queen contiguity. The method leverages a Weighted Sum–Dijkstra’s algorithm to allow multiple criteria such as surface condition, total time, and gradient to be considered when creating routes. The method is tested on the problem of routing across two areas of Dartmoor National Park, United Kingdom. The generated routes are compared with benchmark algorithms and real paths created by users of the Ordnance Survey’s Maps App. The generated routes are found to be more realistic than those of the benchmark methods and closer to the real paths. Furthermore, the routes are able to bypass hazards and obstacles while still providing realistic and flexible routes to the user.

The interplay of diffusion with phenomena like stochastic adsorption–desorption, absorption, and reaction–diffusion is essential for life and manifests in diverse natural contexts. Many factors must be considered, including geometry, dimensionality, and the interplay of diffusion across bulk and surfaces. To address this complexity, we investigate the diffusion process in heterogeneous media, focusing on non-Markovian diffusion. This process is limited by a surface interaction with the bulk, described by a specific boundary condition relevant to systems such as living cells and biomaterials. The surface can adsorb and desorb particles, and the adsorbed particles may undergo lateral diffusion before returning to the bulk. Different behaviors of the system are identified through analytical and numerical approaches.

Zinc oxide is a promising material for the creation of various types of sensors, in particular UV detectors. In this work, arrays of ordered nanorods were grown by chemical vapor deposition. The effect of environmental humidity on the sensing properties of zinc oxide nanorod arrays was investigated, and a prototype UV sensor using indium as an ohmic contact was developed. UV photoresponses were measured for the samples stored in dry and wet atmospheres. The increase in sensitivity and response of the ZnO nanorod arrays was observed after prolonged exposure to a wet atmosphere. A model was proposed to explain this effect. This is due to the formation of hydroxyl groups on the surface of zinc oxide nanorods, which is confirmed by FTIR spectroscopy data. For the first time, it has been shown that after storage in a wet atmosphere, the sensory properties of the structure remain stable regardless of the ambient humidity.

1D organic metal halide hybrids (OMHHs) exhibit strongly anisotropic optical properties, highly efficient light emission, and large Stokes shift, holding promise for novel photodetection and lighting applications. However, the fundamental mechanisms governing their unique optical properties and in particular the impacts of surface effects are not understood. Herein, 1D C4N2H14PbBr4 by polarization‐dependent time‐averaged and time‐resolved photoluminescence (TRPL) spectroscopy, as a function of photoexcitation energy, is investigated. Surprisingly, it is found that the emission under photoexcitation polarized parallel to the 1D metal halide chains can be either stronger or weaker than that under perpendicular polarization, depending on the excitation energy. The excitation‐energy‐dependent anisotropic emission is attributed to fast surface recombination, supported by first‐principles calculations of optical absorption in this material. The fast surface recombination is directly confirmed by TRPL measurements, when the excitation is polarized parallel to the chains. The comprehensive studies provide a more complete picture for a deeper understanding of the optical anisotropy in 1D OMHHs.

• Bending edge wave is studied in a thin transversely isotropic viscoelastic plate supported by a viscoelastic foundation. • The nonlocal elasticity theory is used to extract the micro-scale effect on the travelling edge wave. • The Kirchhoff plate theory and the sinusoidal waveform are considered to obtain the closed-form solution. • It is observed that due to the present of viscosity in the foundation the speed of the wave is reduced. The analysis consists of the dynamic behaviour of a thin semi-infinite functionally graded plate under bending edge wave propagation. The plate is made of transversely isotropic materials supported by an elastic foundation. A quadratic variation of the properties of the materials is used to examine the behaviour of the FGM (Functionally Graded Materials) plate in the bending edge wave propagation. The Eringen differential form is employed to transition from non-local to local elasticity. The parameter entailed in the differential form is used to extrapolate the microstructure's impact on the bending edge wave propagation in the functionally graded plate. Additionally, the surface elasticity theory is included to investigate the surface effects on the dispersion of edge wave. The viscosity effect of the plate and the foundation are taken into consideration while formulating the problem. To develop the kinematics of FGM plates, the Kirchhoff plate theory is considered. The motion of the plate is taken along the transverse direction of the plate. The viscoelastic theory proposed by Kelvin-Voigt is used to formulate the mathematical theory of the proposed model. A coupled equation corresponding to the moments and shear forces has been obtained while formulating the plate equation of motion. The rotatory inertia effect is neglected due to the small deflection of the plate. The numerical simulation presented in the paper shows the influence of the viscosity of the elastic foundation, surface effects, non-local elasticity, and the density of the materials on the natural frequency of bending edge wave propagation. [ABSTRACT FROM AUTHOR]

A novel functionally graded material (FGM) sandwich nanoplate model with surface effects is developed in this work. By using the Gurtin–Murdoch theory of surface elasticity, surface effects are taken into account. Governing equations for nonlinear vibrations are obtained though the balance of forces. The Galerkin method is employed to obtain the approximate solutions for nonlinear free and forced vibrations of the FGM laminates. Numerical results show that considering surface effects changes the equivalent Young's modulus and bending stiffness of FGM sandwich nanoplates. In addition, the influences of surface effects are related to the geometric size of the nanoplate. Numerical examples are proposed to verify the effectiveness of the present results. [ABSTRACT FROM AUTHOR]

The processes occurring in the case of the incidence of 2–8 keV C60 fullerene ions on the Si(100) surface at temperatures ranging from 0 to 700 K are examined using molecular-dynamics computer simulations (by means of the LAMMPS code). The Tersoff-ZBL (Ziegler–Biersack–Littmark) and AIREBO potentials are used, and fast-ion energy losses spent on electron processes are also taken into account. It is shown that the target temperature has no influence on displacement-cascade development but affects its thermalization and crater formation on the surface. As the C60 ion energy increases, carbon atoms penetrate deeper into the target, and both the formed crater volume and the size of the rim around it enlarge. An increase in the temperature to 700 K leads to a more effective formation of the crater and an increase in the rim compared to those discovered at temperatures of 0 and 300 K. A mechanism of this phenomenon is proposed. [ABSTRACT FROM AUTHOR]

Topological insulators have been shown to exhibit strong and long-lived surface photovoltages when excited by an infrared pump. The ability to generate long-lived potentials on these surfaces provides opportunities to manipulate the spin-momentum locked topological surface states. Moreover, the photo-induced nature of this effect allows for localized excitation of arbitrary geometries. Knowing precisely how these potentials form and evolve is critical in understanding how to manage the effect in applications. The uniqueness of the photoemission experimental geometry, in which the photoelectron must traverse the induced surface field in vacuum, provides an interesting probe of the electric dipole shape generated by the surface photovoltage. In this study, we are able to match the observed decay of the geometric effect on the photoelectron to an essential electrodynamics model of the light-induced dipole thereby tracking the fluence-dependent evolution of the dipole geometry. By utilizing a standard time-resolved angle-resolved photoemission experiment, we are able to determine real-space information of the dipole while simultaneously recovering time-resolved band structure.

The free and forced vibration of a graded geometrically nonlinear Timoshenko nanobeam supported by on a nonlinear foundation is considered in this paper. The main contribution of this study is to propose a new formulation for the dynamic response of this beam by combining nonlocal and surface elasticity in addition to employing the physical neutral axis method which eliminates the quadratic nonlinearity from the equation of motion. Using the principle of virtual work, a fourth-order nonlinear partial differential equation is formulated and Galerkin technique is employed to yield a fourth-order ordinary differential equation with cubic nonlinearity in the temporal domain. The method of multiple scales is employed to obtain the analytical expression of the nonlinear frequency of the beam and its frequency response curve from a primary resonance analysis. To assess the accuracy of this analytical solution, it is compared with a numerical solution obtained using the differential quadrature method. The obtained analytical results are successfully validated for particular cases of the considered problem with results published by other authors. The effects of surface elasticity, nonlocality, the physical neutral axis, the beam aspect ratio, the power-law index and the elastic foundation coefficients on the free and forced vibration response of the graded Timoshenko nanobeam are thoroughly investigated for different types of boundary conditions. [ABSTRACT FROM AUTHOR]

Understanding crystallization mechanisms in nano-sized metallic glasses (MGs) is important to the manufacturing and application of these new nanomaterials that possess a unique combination of structural and functional properties. Due to the two-dimensional projections and limited spatial and/or temporal resolutions in experiments, significant questions (e.g., whether nucleation takes place on the free surface or in a near-surface layer) regarding this subject remain under debate. Here, we address these outstanding questions using molecular dynamics simulations of crystallization in MG nanorods together with atomistic visualization and data analysis. We show that nucleation in the nano-sized MGs predominantly takes place on the surface by converting the high-energy liquid surface to a lower-energy crystal surface (the most close-packed atomic plane). This is true for all the nanorods with different diameters studied. On the other hand, the apparent growth mode (inward/radial, lateral or longitudinal) and the resulting grain structure are more dependent on the nanorod diameter. For a relatively big diameter of the nanorod, the overall growth rate does not differ much among the three directions and the resulting grains are approximately semispherical. For small diameters, grains appear to grow more in longitudinal direction and some grains may form relatively long single-crystal segments along the length of the nanorod. The reasons for the difference are discussed. The study provides direct atomistic insights into the crystallization mechanisms in nano-sized MGs, which can facilitate the manufacturing and application of these new advanced materials. [ABSTRACT FROM AUTHOR]

A continuum theoretical model for describing nanotube formation from a self-bending (self-curling) nanofilm driven by surface stress was established in this paper. Surface stress, surface elasticity and anisotropic deformation were considered. A nanofilm was cured along tangential direction to form a nanotube. The other in-plane direction (cylindrical direction) maintains straight state. Isotropic surface stress no longer induces an isotropic bent under this condition. Therefore, isotropic Stoney theory should be modified and the anisotropic deformation should be reckoned in. Curling structure affects radius as well as elongation strain of nanotubes obviously. Film stiffness instead of biaxial modulus in the curling equation means the difference between our theory and Stoney formula (as well as its modified form). If surface elasticity is balance, elongation strain holds isotropic despite the anisotropic curling structure of nanotubes. Since residual strain and stress influence the physical properties within nanotube wall, the residual strain and stress were also analyzed in this paper. [ABSTRACT FROM AUTHOR]

Micro-energy harvesters are attracting more and more attention due to the demand of the miniaturization and the self-power for the electrical devices. A three-layered porous piezoelectric (PE)/piezomagnetic (PM) energy harvester at the nanoscale is modeled in this paper. The layered PE/PM structure works in the magnetic field; the electrical power can be obtained from the PE layer due to the magnetostriction of the PM layers. Based on the surface elasticity and Boit's porous theory, the governing equations and the analytical expressions of the harvester with the thickness-shear mode are derived. The numerical analysis indicates that the electrical energy capture capability of the porous PE/PM energy harvester is much superior to its nonporous alternative. Then, the influences of the porous properties, the surface effects, and the constitution of the PE/PM materials on the energy capture performance are discussed. The results indicate that the nano PE/PM energy harvester with pores can be controlled and optimized by improving the porous, surface, and geometrical parameters. [ABSTRACT FROM AUTHOR]

In this paper, we study the impacts of an initial axial force and the surface effects on the dynamic characteristics of an embedded bioliquid filled microtubule (MT) under a walking motor protein. We model the microtubule using the orthotropic Timoshenko Beam (TB) model. The impact of the surrounding cytoplasm is considered by modelling it as a two parameters Pasternak model. We used the modified couple stress theory (MCST) in order to include small-scale effects to derive the motion equations by applying Hamilton's principle for the orthotropic TB model. The influence of motor protein motion, surrounding cytoplasm matrix, surface effects and the initial axial loading are examined for the deflection, rotation and coupled vibration frequency of the embedded microtubule simply supported on both ends. We found that the initial axial loading and the magnitude of the moving load due to motor protein motion renders the simply supported microtubule less stable. It is seen that surface parameters tend to increase the stability of the microtubule as they enhance the frequency of vibration and reduce the normalised dynamic deflection and rotation for all vibration modes. The Winkler and Pasternak parameters are found to greatly affect the dynamic behaviour of the liquid filled microtubules. [ABSTRACT FROM AUTHOR]

• The phase velocity equations for Shear Horizontal waves propagate in a layered piezoelectric nanostructures with surface effect are derived. • The influences of surface elasticity, surface density, and orthotropic piezoelectric constants on the waves' velocity have been studied qualitatively and quantitatively. • A comparable study is conducted to reveal the mechanism of the effect of surface elasticity and surface density on SH waves in a piezoelectric layer on an elastic semi-space. • The imperfect interface constants have negative or no effects on the waves' velocity when the wavenumber is relatively small or considerable. • The slope of linear function clarifying phase velocity versus wavenumber is critical to experimentally obtaining surface density. Nowadays, orthotropic piezomaterials have enormous potential in producing electronic devices owing to their inherent merits, e.g., intrinsically robust piezoelectricity. Nevertheless, the previous theoretical studies merely report surface effects on the physical properties of SH waves in a layered transversely isotropic piezoelectric structure. Filling such a blank is a special necessity for optimizing Surface Acoustic Wave (SAW) sensors. Thus, the present paper aims to determine how surface effects and interfacial imperfection affect the attributes of SH waves in a layered orthotropic piezoelectric semi-space by means of surface piezoelectricity theory and a linear spring model. The structure mainly consists of the piezoelectric film's bottom and top surface layers and the imperfect bonding between the piezoelectric film and elastic half-space. To explicitly figure out surface and imperfect interface effects on the mechanical behavior of SH waves in a layered piezoelectric half-space, we extensively derive the phase velocity equations of SH waves in an orthotropic piezoelectric plate and an orthotropic piezoelectric half-space. Then, a comparison study among SH waves in a layered piezoelectric semi-space, a piezoelectric plate, and a piezoelectric half-space is conducted. As a result, it is revealed that the attributes of SH waves dramatically vary as the piezoelectric films' thickness changes from microscale to nanoscale. In addition, phase velocity increases or decreases with an increasing surface elastic constant or surface density due to the enhancement of stiffness or density of the whole structure. When the ratio of piezoelectric film thickness to wavelength is small, imperfect parameters substantially reduce the phase velocity owing to a decreasing interface elastic stiffness. The comparison study shows that the imperfect parameter does not influence the waves' velocity, while the ratio of film thickness to wavelength is relatively considerable. Anisotropic piezoelectric constant essentially weakens surface effects on the waves' velocity. Intriguingly, a linear function is acquired and is used to measure surface density via the slope of the linear function. The summaries supply unique guidelines and instructions to open an avenue for designing and manipulating surface acoustic wave nanosensors in the future. [Display omitted] [ABSTRACT FROM AUTHOR]

• Constitutive equations of transverse isotropic fluid-saturated porous materials with channel-like compressible liquid inclusions are presented, with surface effects accounted for. • The influence of surface effects and fluid compressibility on effective transverse isotropic undrained moduli is quantified using the generalized self-consistent method. • Effective Biot coefficients of effective stress and Biot modulus, which describe fluid–solid coupling, are derived by their physical meaning. • Combining the top-down (constitutive equations) and bottom-down (micromechanical models) approaches, the estimated effective poroelastic parameters are applied to calculate pore pressure and displacement history using the classical solution of Mandel's problem. When surface energy is increased, it is demonstrated that the pore pressure and displacement first increase and then decrease. Porous media with fluid-saturated microchannels, prevalent in biomaterials, tissue engineering materials and flexible electronic devices, can be modelled as transverse isotropic materials. Surface effects can influence significantly the macro-mechanical responses of such materials, particularly for soft materials with micro- or nano-scale channels. In this study, we first develop constitutive laws for fluid saturated porous materials with microchannels by integrating the top-down (homogenization) approach with the bottom-up (micromechanics) approach. We then explicitly establish a connection between surface effects and macro-mechanical responses. Employing the generalized self-consistent model (GSCM), we estimate the effective parameters (i.e. , coefficients in constitutive equations governing macro-mechanical responses), with fluid compressibility and surface effects accounted for. Our findings reveal that, as surface energy increases, the effective transverse shear modulus is enlarged, the effective plane strain bulk modulus, the unit uniaxial straining modulus and the cross modulus are all reduced, but the axial shear modulus remains nearly unchanged. As an application, we characterize the mechanical behaviors of the transverse isotropic fluid-saturated porous material with surface effects by connecting the classic Mandel solution with the estimated effective parameters. The pore pressure exhibits the Mandel-Cryer effect. The insights gained from this study are valuable for comprehending and exploring the intricate ways in which surface effects influence the mechanical responses of transversely isotropic fluid-saturated porous materials featuring sufficiently small channels. [ABSTRACT FROM AUTHOR]

• Surface effects on rectangular nano laminates are reported. • Analytical solution of bending of rectangular nano laminates is obtained. • Analytical solution of vibration of rectangular nano laminates is presented. • Effects of boundary conditions on bending and natural frequency are examined. • Effects of geometric parameters on bending and natural frequency are examined. In this paper, a novel continuum mechanics model is developed to investigate the influence of surface effects on the bending and free vibration behaviors of Kirchhoff rectangular nano laminates. The governing equations are established based on the Gurtin–Murdoch theory and the analysis of the equilibrium of forces. Analytical solutions for bending deflections and natural frequencies are presented for selected boundary conditions. Numerical results show that the influences of surface effects on bending deflections and natural frequencies are related to the aspect ratio of the nano laminates and the value of residual surface stress. Moreover, the influence of surface effects can be ignored when the thickness of the nano laminate is large enough. [ABSTRACT FROM AUTHOR]

Monte Carlo simulations are used to investigate the main effects related to the hysteresis loops of magnetite and maghemite spinel nanoparticles. In particular, the influence of the finite size of the nanoparticles, the measurement temperature, the roughness of the surface, and the anisotropy are examined. The classical spin model with Heisenberg-type interactions was used with the dominant term of super-exchange interaction in spinel structure. The simulated hysteresis loops are carried out on nanoparticles with perfect or disordered surface and dilution of octahedral sublattice. The simulated hysteresis loops change significantly due to the competition between magnetic anisotropy mainly at the surface of the nanoparticle and the presence of super-exchange interaction. We show the existence of a net magnetization at the surface which is at the origin for the variation of the hysteresis loops shape. [ABSTRACT FROM AUTHOR]

Nanocomposites based on iron oxide/titanium oxide nanoparticles were prepared by employing green synthesis, which involved phytochemical-mediated reduction using ginger extract. XRD confirmed the composite formation, while scanning electron microscopy (SEM), dynamic light scattering (DLS), and energy-dispersive X-ray spectroscopy (EDX) was employed to investigate the particle size, particle morphology, and elemental analysis. SEM indicated the formation of particles with non-uniform shape and size distribution, while EDX confirmed the presence of Fe, Ti and oxygen in their elemental state. The surface effects were investigated by Fourier transform infrared radiation (FTIR) and impedance spectroscopy (IS) at room temperature. IS confirmed the co-existence of grains and grain boundaries. Thus, FTIR and IS analysis helped establish a correlation between enhanced surface activity and the synthesis route adopted. It was established that the surface activity was sensitive to the synthesis route adopted. The sample density, variation in grain size, and electrical resistivity were linked with surface defects, and these defects were related to temperature. The disorder and defects created trap centers at the sample's surface, leading to adsorption of CO2 from the environment. [ABSTRACT FROM AUTHOR]

We invert infrasonic timeseries produced by a single buried chemical explosion detonated as part of the Source Physics Experiment phase II Dry Alluvium Geology (DAG). The key to our inversion is that we use a three dimensional, fully coupled, linear, elastic-to-acoustic forward model to predict the recorded acoustic wavefield. We assume that the fourth buried chemical explosion in the series, DAG-4, produces an atmospheric acoustic wavefield due to a combination of direct elastic-to-acoustic coupling at the air-earth interface and ground upheaval, or spall, at the Earth's surface. In our linear model we approximate these two phenomena with distinct source terms separated in space and time: (1) a buried point source consisting of six source time functions, each corresponding to a single component of a generalized moment tensor and (2) a vertically directed, time-variable force applied to the Earth's surface. Inverting the infrasonic data with this linear forward model results in estimated source parameters that accurately predict the observed infrasound signals. To test our estimated buried source, we use the Rayleigh integral (RI) to model the infrasound signal from the measured and predicted acceleration surfaces. First, we simulate the infrasound signal waveforms using vertical accelerometer data and find that these closely match the observed infrasound. Next, using the estimated buried seismic source model without spall, we estimate the acceleration of the Earth's surface using a linear approximation. When using the predicted surface acceleration in the RI, we simulate infrasound signals that reproduce pulse shape characteristics but not the amplitude of the observed infrasound, indicating our linear model does not completely account for nonlinear spall effects. Based on these results, we argue that for the scale of this experiment, purely linear models can estimate seismoacoustic source attributes and predict the far-field infrasonic signal, but the primary contribution to the infrasonic signal is the spall source. [ABSTRACT FROM AUTHOR]

The atomic and electronic structure of YFeO3 surfaces at the formation of oxygen vacancies are investigated by the methods of quantum-mechanical calculations. The (100), (001), and (010) surfaces are considered. The dependence of the formation energy of surface oxygen vacancy on its concentration and type of surface is shown. (100) surface oxygen vacancy has the lowest formation energy. During the formation of vacancies on the surface, the 3d states of Fe split into bulk, surface, and near-surface states.

We present the user‐friendly and freely available software package QUEELS (QUantitative analysis of Electron Energy Losses at Surfaces) that allows to calculate effective inelastic scattering cross sections within the dielectric response description, for swift electrons travelling nearby surfaces in several environments. We briefly describe the underlying theoretical models and illustrate its use to evaluate the distribution of energy losses taking place in electron spectroscopies like transmission electron energy loss spectroscopy (TEELS), X‐ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and reflection electron energy loss spectroscopy (REELS), which are widely used for material analysis. This includes the intrinsic excitations due to the core hole in XPS and AES. [ABSTRACT FROM AUTHOR]