Nanoscale Parameters Research Articles

Chemically reactive stagnated third‐grade magnetized nanomaterial considering modern diffusion approaches

AbstractAn incompressible boundary‐layer third‐grade nanomaterial stagnated flow confined by stretchy regime is formulated. The laminar magnetized thermal and solutal flow features the aspects of Brownian diffusion, generalized thermal‐flux, thermophoresis, and generalized solutal‐flux. The dimensionalized third‐grade steady‐state model is obtained by implementing appropriate variables. The subsequent nonlinear mathematical model is analytically computed by utilizing homotopy algorithm. The graphics demonstration of nondimensional fields (i.e., velocity, concentration, and temperature) for distinct physical variables is exhibited. The outcomes for the skin‐friction coefficient are calculated and confirmed to be precise. The analysis reveals that augmented values of material parameters escalate nanomaterial velocity while the Hartman number exhibits lower velocity. The temperature field displays a decaying trend for Prandtl number and thermal relaxation variable while contrary effects for nanoscale parameters (i.e., thermophoresis diffusive and Brownian diffusive) are reported. Besides, the nanomaterial concentration shows a decreasing trend with respect to the Schmidt number, Brownian motion, and solutal‐relaxation variable while thermophoresis parameter exhibits opposite effects. Furthermore, this study could be valuable for the design of various lab‐on‐a‐chip and thermal microfluidic devices in the field of biomedicine. Besides contributing to the creation of new devices, they may also be advantageous for performing genetic testing and developing innovative tools.

Introducing a nano-scale surface morphology parameter affecting fracture properties of CNT nanocomposites

Carbon Nanotube (CNT) particles and membranes improve interlaminar fracture toughness of nanocomposites. The novelty of this study is to introduce the effect of a new nanoscale parameter - CNT network (bundle) size to interphase thickness ratio - on modes I and II interlaminar fracture toughness of CNT Polymer Nanocomposites (PNCs). This investigation includes the stochastic distribution function of CNT bundle size, interphase thickness, and modes I and II fracture toughness of PNCs based on an extensive experimental study at the nano- and macro-scales. The Atomic Force Microscopy PeakForce Quantitative Nanomechanics Mapping technique was used to collect 500 datasets for a low-weight percentage of CNT PNC and 180 datasets for a high-weight percentage of CNT PNC. Each dataset included CNT bundle size and interphase thickness at the nanoscale. Double cantilever beam and end-notched flexure experiments were conducted to collect 600 modes I and II fracture toughness data. Two-, three-, and four-parameter Weibull models were used to simulate the nano- and macro-scale material properties of CNT PNCs. Results indicate that (i) a lower CNT bundle size to interphase thickness ratio improves fracture toughness, and (ii) a four-parameter Weibull model is the most efficient model for simulated data.

Multiscale Modeling of Magnetoelectric Nanoparticles for the Analysis of Spatially Selective Neural Stimulation.

The growing field of nanoscale neural stimulators offers a potential alternative to larger scale electrodes for brain stimulation. Nanoelectrodes made of magnetoelectric nanoparticles (MENPs) can provide an alternative to invasive electrodes for brain stimulation via magnetic-to-electric signal transduction. However, the magnetoelectric effect is a complex phenomenon and challenging to probe experimentally. Consequently, quantifying the stimulation voltage provided by MENPs is difficult, hindering precise regulation and control of neural stimulation and limiting their practical implementation as wireless nanoelectrodes. The work herein develops an approach to determine the stimulation voltage for MENPs in a finite element analysis (FEA) model. This model is informed by atomistic material properties from ab initio Density Functional Theory (DFT) calculations and supplemented by experimentally obtainable nanoscale parameters. This process overcomes the need for experimentally inaccessible characteristics for magnetoelectricity, and offers insights into the effect of the more manageable variables, such as the driving magnetic field. The model's voltage is compared to in vivo experimental data to assess its validity. With this, a predictable and controllable stimulation is simulated by MENPs, computationally substantiating their spatial selectivity. This work proposes a generalizable and accessible method for evaluating the stimulation capability of magnetoelectric nanostructures, facilitating their realization as wireless neural stimulators in the future.

Investigating the dissipation of heat and quantum information from DNA-scaffolded chromophore networks.

Scaffolded molecular networks are important building blocks in biological pigment-protein complexes, and DNA nanotechnology allows analogous systems to be designed and synthesized. System-environment interactions in these systems are responsible for important processes, such as the dissipation of heat and quantum information. This study investigates the role of nanoscale molecular parameters in tuning these vibronic system-environment dynamics. Here, genetic algorithm methods are used to obtain nanoscale parameters for a DNA-scaffolded chromophore network based on comparisons between its calculated and measured optical spectra. These parameters include the positions, orientations, and energy level characteristics within the network. This information is then used to compute the dynamics, including the vibronic population dynamics and system-environment heat currents, using the hierarchical equations of motion. The dissipation of quantum information is identified by the system's transient change in entropy, which is proportional to the heat currents according to the second law of thermodynamics. These results indicate that the dissipation of quantum information is highly dependent on the particular nanoscale characteristics of the molecular network, which is a necessary first step before gleaning the systematic optimization rules. Subsequently, the I-concurrence dynamics are calculated to understand the evolution of the vibronic system's quantum entanglement, which are found to be long-lived compared to these system-bath dissipation processes.

The Nanoscale Wetting Parameter and Its Role in Interfacial Phenomena: Phase Transitions in Nanopores.

Through analysis of the statistical mechanical equations for a thin adsorbed film (gas, liquid, or solid) on a solid substrate or confined within a pore, it is possible to express the equilibrium thermodynamic properties of the film as a function of just two dimensionless parameters: a nanoscale wetting parameter, αw, and pore width, H*. The wetting parameter, αw, is defined in terms of molecular parameters for the adsorbed film and substrate and so is applicable at the nanoscale and for films of any phase. The main assumptions in the treatment are that (a) the substrate structure is not significantly affected by the adsorbed layer and (b) the diameter of the adsorbate molecules is not very small compared to the spacing of atoms in the solid substrate. We show that different surface geometries of the substrate (e.g., slit, cylindrical, and spherical pores) and various models of wall heterogeneity can be accounted for through a well-defined correction to the wetting parameter; no new dimensionless variables are introduced. Experimental measurements are reported for contact angles for various liquids on several planar substrates and are shown to be closely correlated with the nanoscale wetting parameter. We apply this approach to phase separation in nanopores of various geometries. Molecular simulation results for the phase diagram in confinement, obtained by the flat histogram Monte Carlo method, are reported and are shown to be closely similar to experimental results for capillary condensation, melting, and the triple point. The value of the wetting parameter, αw, is shown to determine the qualitative behavior (e.g., increase vs decrease in the melting temperature, capillary condensation vs evaporation), whereas the pore width determines the magnitude of the confinement effect. The triple point temperature and pressure for the confined phase are always lower than those for the bulk phase for all cases studied.

Droplet navigation on metastable hydrophobic and superhydrophobic nonwoven materials

Rendering any surface non-wettable requires it to be clean and dry after the droplet is deposited or impacted. Leveraging and quantifying the non-periodic or random topology non-wettable is intricate as the Cassie-Baxter state competes with the Wenzel or impaled state, which becomes further challenging for irregular and heterogeneous nonwoven materials. Herein, we report the fundamental insights of the impalement dynamics of droplets on metastable nonwovens and self-similar nonwoven-titanate nanostructured materials (SS-Ti-NMs) using laser scanning confocal microscopy in three dimensions. Our results represent the first example of liquid imbibition in metastable nonwovens and SS-Ti-NMs involving a complex interplay between a triumvirate of factors – the number of fibres in the defined cross-sectional area (volume), pore features, and intrinsic wetting properties of the constituent entities. Predictive models of the apparent contact angle and breakthrough pressure for nonwovens and their SS-Ti-NMs have been proposed based on micro- and nano-scale structural parameters. Enabled by X-ray microcomputed tomography analysis, a key set of three-dimensional fibre and structural parameters of nonwovens has been unveiled, which played a vital role in validating the predictive models of apparent contact angles.

Advanced-Glycation Endproducts: How cross-linking properties affect the collagen fibril behavior

Advanced-Glycation-Endproducts (AGEs) are known to be a major cause of impaired tissue material properties. In collagen fibrils, which constitute a major building component of human tissue, these AGEs appear as fibrillar cross-links. It has been shown that when AGEs accumulate in collagen fibrils, a process often caused by diabetes and aging, the mechanical properties of the collagen fibril are altered. However, current knowledge about the mechanical properties of different types of AGEs, and their quantity in collagen fibrils is limited owing to the scarcity of available experimental data. Consequently, the precise relationship between the nano-scale cross-link properties, which differ from type to type, their density in collagen fibrils, and the mechanical properties of the collagen fibrils at larger scales remains poorly understood. In our study, we use coarse-grained molecular dynamics simulations and perform destructive tensile tests on collagen fibrils to evaluate the effect of different cross-link densities and their mechanical properties on collagen fibril deformation and fracture behavior. We observe that the collagen fibril stiffens at high strain levels when either the AGEs density or the loading energy capacity of AGEs are increased. Based on our results, we demonstrate that this stiffening is caused by a mechanism that favors energy absorption via stretching rather than inter-molecular sliding. Hence, in these cross-linked collagen fibrils, the absorbed energy is stored rather than dissipated through friction, resulting in brittle fracture upon fibrillar failure. Further, by varying multiple AGEs nano-scale parameters, we show that the AGEs loading energy capacity is, aside from their density in the fibril, the unique factor determining the effect of different types of AGEs on the mechanical behavior of collagen fibrils. Our results show that knowing AGEs properties is crucial for a better understanding of the nano-scale origin of impaired tissue behavior. We further suggest that future experimental investigations should focus on the quantification of the loading energy capacity of AGEs as a key property for their influence on collagen fibrils.

Molecular dynamics simulation on bulk bitumen systems and its potential connections to macroscale performance: Review and discussion

• The application cases of MD simulations on bulk bitumen systems were reviewed. • Bitumen model, Forcefield, validation and prediction parameter were summarized. • The effects of aging, modification, and rejuvenation on bitumen were overviewed. • The potential connections between nano-and-macroscales properties were discussed. Molecular dynamics (MD) simulation plays an effective role in predicting the critical properties and explaining the macroscale phenomenon at the nanoscale. This review summarized the application cases of MD simulations in various bitumen systems, considering aging, modification, and rejuvenation factors. Meanwhile, the potential relationships between the nanoscale parameters predicted from MD simulations and macroscale properties measured from experimental tests were discussed for the first time. Different molecular models of virgin bitumen, commonly-used Forcefields, and validation parameters for MD simulations on bituminous materials were summarized. Based on the reactive MD simulation outputs, the oxidative aging reaction path at the atomic scale of bitumen molecules was reviewed. Furthermore, the influence of aging (short-term and long-term), modification (polymers, fillers, and bio-bitumen), and rejuvenation (various rejuvenators) on the molecular-scale properties of virgin bitumen models would be evaluated through MD simulations. This review could help us further explore the main functions of MD simulations in different bulk bitumen systems and build an integral multi-scale research method from the molecular design and performance prediction to material optimization and synthesis of bituminous materials without lots of experimental attempts.

Magnetized supercritical third-grade nanofluid flow from a vertical cylinder using a Crank–Nicolson implicit scheme

The current study investigates the supercritical convective radiative buoyancy-driven flow and heat transfer in external coating flow of an electrically conducting viscoelastic third-grade nanofluid from hotmoving/stationary cylinder under constant radial magnetic field. A new computational thermodynamic model has been proposed to study the supercritical behavior of third-grade aqueous nanofluid in terms of supercritical water. The Redlich–Kwong equation of state (RK-EOS) has been deployed to calculate thermal expansion coefficient for free convective flow of supercritical nanofluid in terms of temperature, compressibility factor and pressure. A validation test has been conducted for RK-EOS with available experimental results. A well-tested unconditionally stable Crank–Nicolson scheme has been implemented to obtain numerical solutions. Graphical results for flow variables, heat transfer and skin-friction coefficient distributions are presented for variation of nanoscale, rheological, magnetic, radiative and thermodynamic parameters. Transient velocity is reduced whereas temperature is elevated with amplified values of third-grade fluid parameter, reduced pressure, reduced temperature, and decreased values of volume fraction of nanofluid for a stationary cylinder under supercritical conditions. Special cases of the current model validated against previously published results. Important applications of the current study include nuclear reactor vessels, deposition of smart (functional magnetic) nano-coatings and solar collector energy systems.

Nanoscale physical parameters of source rocks identified by atomic force microscopy: A review

The refinement of nanoscale physical parameters of source rocks has benefitted from continuous innovations in technology and methods. Traditional methods for detecting reservoir physical properties are limited by the properties of the instruments. Atomic force microscopy (AFM) provides new methods and approaches for furthering our understanding and exploring the nanoscale world. Its wide range of applications and gradually developed multiscenario application modes make it an ideal tool for the characterization of nanoscale physical properties of source rocks (coal, shale, mudstone, sandstone, etc.). We highlight the advantages of AFM in regard to performing nondestructive 3D imaging and mechanical property measurements with nanoscale resolution in any desired environment (air, vacuum, liquid). The limitations of AFM applied to source rocks are also summarized. The process has great potential in micro/nanopore characterization, surface morphology characterization, in situ micromechanical property acquisition, wettability research, and so on. The gradual development and improvement of this new model will expand new methods, bring enlightenment to basic research on unconventional oil and gas resources, and provide a scientific basis for the exploration and development of unconventional oil and gas resources.

Plasma-affected photo-thermoelastic wave propagation in a semiconductor Love–Bishop nanorod using strain-gradient Moore–Gibson–Thompson theories

In this paper, the photo-thermoelastic wave propagation analysis in a semiconductor nanorod resonator under laser excitation employing the strain-gradient Moore–Gibson–Thompson (MGT) and Love–Bishop theories is presented, which is for the first time to the authors’ knowledge. The governing equations of the photo-thermoelastic wave propagation are derived using the proposed novel size-dependent MGT heat conduction model, strain-gradient and Love–Bishop theories. The size-dependent MGT coupled photo-thermoelasticity theory is developed by taking into account of five nano-scale parameters for the first time, which is employed to derive the governing equations. The governing equations are converted into the Laplace-transformed domain and then analytical solution is obtained for a semiconductor Love–Bishop nanorod resonator subjected to plasma and thermal shock loadings. To obtain the transient field variables in the time-domain, the Talbot Laplace-inversion technique is employed. The size-effects on the propagation of the photo-thermoelastic waves are studied in detail. The transient behaviors of the displacement, temperature and carrier density (plasma density) fields are also investigated with considering the nano-scale effects by performing the parametric studies. The effects of the carrier density, the relaxation time in the size-dependent MGT theory and the nano-scale parameters on the plasma-affected photo-thermoelastic wave propagation are revealed. Numerical examples demonstrate that the derived governing equations and also the proposed analytical solutions can be employed to determine the realistic behaviors of the field variables in a semiconductor Love–Bishop nanorod resonator under laser shock loading with considering the nano-scale effects.

Stress-driven nonlinear behavior of curved nanobeams

A nonlocal stress-driven model for geometrically nonlinear behavior of a shallow arch under radial pressure is presented. The analytical nonlinear equilibrium equation and also buckling equations by variational principles and virtual work are found. As it has been proven before, the strain-driven models encountered some contradictions with local equilibrium conditions, while stress-driven formulation has solved these difficulties. The simultaneous participation of the constitutive boundary conditions has led to this improvement. To obtain nonlocal strains, local nonlinear strains are incorporated in the nonlocal stress-based equations. In this way, nonlocal loads corresponding to the limit-load and bifurcation instabilities are exactly calculated by considering the effect of nanoscale and geometry parameters. In this article, the geometric limits which determine when and how the arch bifurcates, are found. The results in specific cases are compared with those available in the literature. These comparisons show the accuracy of the work. Finally, the 3D view of the equilibrium nonlinear paths, associated with the pinned curved nanobeam, are presented for different nanoscale and also geometry ratio parameters.

Critical electro-magneto-mechanical loads of a higher-order shear deformable cylindrical nano panel

This work studies electro-magneto-mechanical critical loads of a shear deformable cylindrical panel subjected to a combination of electric, magnetic, and mechanical loads. A higher-order shear deformation model is used to derive kinematic relations. The critical load equations are extracted using the virtual work’s principle. The buckling loads are obtained with calculation of external works due to electro-magneto-mechanical loads. Zero out of plane shear strains at the top and the bottom surfaces are satisfied using application of third-order shear deformation theory with some modifications. The analytical solution is presented to investigate impact of influencing parameters such as nano-scale length, length to radius ratio, span angle, and Pasternak’s foundation parameters on the electro-magneto-mechanical buckling loads. A large parametric analysis is presented to discuss the impact of influencing parameters such as nano-scale parameter, span angle, Pasternak’s foundation parameters, and length to radius ratio on the critical loads.

Effect of Aromatic Petroleum Resin on Microstructure of SBS Modified Asphalt

In this paper, aromatic petroleum resin (APR) was used as raw material. The fluorescence microscopic photography of styrene-butadiene-styrene block copolymer (SBS) modified asphalt with different contents of APR was carried out, and the effect of APR on the dispersion of SBS modified asphalt was quantitatively studied. The nano-surface morphology of SBS modified asphalt with different APR contents was tested by atomic force microscope (AFM), and the effects of APR content on AFM nanoscale parameters such as roughness and maximum amplitude were analyzed. In addition, this paper also tested the basic technical indexes of SBS modified asphalt with different APR contents and revealed its improvement law on the pavement performance of SBS modified asphalt. The results show that the use of APR is beneficial to the shearing of SBS into smaller particles. The larger the amount of APR, the smaller the maximum particle size and average particle size of SBS in asphalt and the smaller the roughness and maximum amplitude of SBS modified asphalt. APR can improve the viscosity and low-temperature ductility of SBS asphalt to a certain extent. High-temperature storage stability is improved obviously; SBS modified asphalt mixed with APR has a more dense spatial cross-linking structure after thorough development. The research results are helpful to reveal the mechanism of APR improving the performance of SBS polymer asphalt.

Chemically reactive Maxwell nanoliquid flow by a stretching surface in the frames of Newtonian heating, nonlinear convection and radiative flux: Nanopolymer flow processing simulation

AbstractThe effects of a chemical reaction and radiative heat flux in a nonlinear mixed thermo-solutal convection flow of a viscoelastic nanoliquid from a stretchable surface are investigated theoretically. Newtonian heating is also considered. The upper-convected Maxwell (UCM) model is deployed to represent the non-Newtonian characteristics. The model also includes the influence of thermal radiation that is simulatedviaan algebraic flux model. Buongiorno’s two-component nanofluid model is implemented for thermophoretic and Brownian motion effects. Convective thermal and solutal boundary conditions are utilized to provide a more comprehensive evaluation of temperature and concentration distributions. Dimensionless equations are used to create the flow model by utilizing the appropriate parameters. The computed models are presented through a convergent homotopic analysis method (HAM) approach with the help of Mathematica-12 symbolic software. Authentication of HAM solutions with special cases from the literature is presented. The impact of various thermophysical, nanoscale and rheological parameters on transport characteristics is visualized graphically and interpreted in detail. Temperatures are strongly enhanced with Brownian motion and thermophoresis parameters. Velocity is boosted with the increment in the Deborah viscoelastic number and mixed convection parameter, and the hydrodynamic boundary layer thickness is reduced. A stronger generative chemical reaction enhances concentration magnitudes, whereas an increment in the destructive chemical reaction reduces them and also depletes the concentration boundary layer thickness. Temperature and concentration are also strongly modified by the conjugate thermal and solutal parameters. Greater radiative flux also enhances the thermal boundary layer thickness. Increasing the Schmidt number and the Brownian motion parameter diminish the concentration values, whereas they elevate the Sherwood number magnitudes,i.e.enhance the nanoparticle mass transfer rate to the wall.

Measurement of wood surface roughness in Dinizia excelsa Ducke using an atomic force microscope

Measurement techniques of nanoscale parameters have been vastly explored nowadays. In systems such as wood that possess anisotropic surfaces, these techniques provide reliable data on the surface morphology and related parameters. The atomic force microscope (AFM) and optical microscope were used to investigate the roughness and surface morphology of Dinizia excelsa. Cuts were made in different directions generating three distinct surfaces: radial, tangential and transverse. The samples went through a sanding process to reveal the original morphology of the steering. Both techniques show that the surface texture is different according to the analysed surface. The lowest roughness was observed on the transverse plane while the highest occurred on the radial. The comparison of the morphology evaluation by the two techniques allowed us to see that the AFM technique revealed the most sensitive images in smaller scales. These results confirmed that the AFM can provide satisfactory results for the surface parameters of Dinizia excelsa depending on the cut direction. This type of analysis can be useful in laboratory species identification processes and in deforestation inspection processes in the Amazon

Multiscale analysis for predicting elastic properties of 3D printed polymer-graphene nanocomposites

The use of graphene-based nanocomposite materials is increasing in additive manufacturing (or 3D printing) technology. This work focuses on evaluating the elastic properties of 3D printed components using PLA/graphene nanocomposite material. The filler morphology at the nanoscale and process parameters such as printing layer orientation at macroscale affect the final mechanical properties of printed parts. We used FE-RVE based numerical approach to estimate the elastic modulus of printed parts at two different scales. At the nanoscale, RVE is constructed using filler and matrix morphology. The modulus calculated is used as an input to the macroscale RVE which is built using the printing process parameters and deposited bead dimensions. The boundaries of the RVE domain are subjected to multi-nodal periodic boundary conditions, and homogenized properties were calculated. Experiments have been conducted to validate numerically calculated modulus values. Tensile test samples have been 3D printed according to ASTM D638 standard and tested at 1 mm/min. The numerically estimated modulus values are in close agreement with experimentally obtained values. Further, parametric studies have been carried out to investigate the effect of print layer thickness and orientation on the modulus of 3D printed parts. The two-scale numerical approach presented here can predict the elastic properties of 3D printed parts.

A nanoscale study of size scale, strain rate, temperature, and stress state effects on damage and fracture of polyethylene

The mechanical properties and damage behavior of amorphous polyethylene are investigated using Molecular Dynamics (MD) simulations. The influence of time, temperature, size scale, and stress state are extensively studied to gather insights into the complex nature of glassy polymers and the related damage process of void formation during dynamic loading conditions. The Modified Embedded Atom Method (MEAM) is employed to model interatomic interactions, balancing computational efficiency with a superior description of free surfaces and void formation to provide a detailed analysis of the progression of damage in the form of nucleation, growth, and coalescence of voids. The MD simulations capture the evolution of the number and size of voids and are shown to correlate to specific regimes of the stress-strain response. Particular attention is given to the quantification of void coalescence and the influence coalescence has on the growth and nucleation rates of voids. A nanoscale parameter, the critical Inter-void Ligament Distance (ILD), is defined for the initiation of void coalescence, and is found to be about 0.75 void diameters resulting in the enhancement of void growth and the restriction of void nucleation once the critical ILD is achieved. This study provides important insight into the damage progression of glassy polymers that cannot be defined through current experimental techniques.

Higher order electro-magneto-elastic free vibration analysis of piezomagnetic nano panel

Abstract This paper investigates electro-magneto-elastic free vibration responses of piezomagnetic cylindrical nano panel subjected to electro-magneto-mechanical loads based on third-order theory. Third-order shell theory is used for description of the displacement field. The zero transverse shear strains are obtained using the third-order displacement field. Hamilton’s principle is employed to obtain the governing equations of motion. The nano panel is subjected to a coupling of magnetic and electric loads, including a linear function along with the thickness direction and a 2D function along with the axial and circumferential directions. To account the effect of nanoscale in governing equations, the Eringen nonlocal elasticity theory is used. The numerical results are obtained to investigate the impact of significant parameters such as axial and circumferential mode numbers, the nanoscale parameter, applied electromagnetic potentials, and length-to-radius ratio. It is concluded that an increase in initial electric potential and a decrease in magnetic potential lead to an increase in natural frequencies of the nano panel.

Formation and stability of nanosized, undercooled propagating intermediate melt during β → δ phase transformation in HMX nanocrystal

The formation and stability of a nanosized propagating intermediate melt (IM) have been analyzed more than below the melting temperature between the solid-solid (SS) phase boundary during phase transformation (PT) in a HMX nanocrystal. The influence of the solid-melt barrier K 12 and two important nanoscale material parameters (ratios of SS and solid-melt SM interface energies, k E and width, ) on the barrierless nucleation and appearance of non-equilibrium IM has been studied. Numerical results reveal that the solution of IM can either be continuous reversible or jump-like first-order discontinuous transformation with hysteresis. Additionally, various parametric studies on the structure, energy, width, and mobility of IM have been explored to understand the mystifying PT behaviors of HMX.