Mass Density Distribution Research Articles

Flow inspection of micropolar nanofluids with motile gyrotactic microorganisms across symmetric channel in porous medium by quasi-linearization technique

The current article investigates the influence of radiation as well as gyrotactic microbes in the flow of micropolar nanoliquids through a channel. Flow is assumed to be symmetric across a channel having permeable walls. The work also focuses on the change in mass transport rate and density distribution of motile microbes across flow regimes in a porous channel. The governing nonlinear partial differential equations of the present problem are transformed into ODEs through dimensionless variables. The coupled nonlinear ODEs are numerically addressed by utilizing the quasi-linearization technique. Impacts of the pertinent parameters on the fluid flow are analyzed and demonstrated through tables as well as figures by using the powerful tool MATLAB. The velocity profiles escalate near both walls with an enhancement in Reynolds number. Moreover, an enhancement in values of heat radiation parameter causes declination in the fluid temperature. An evaluation of the comparison with existing results reveals an excellent harmony. The nanofluids possess marvelous characteristics subject to heat transport as compared to other ordinary fluids. We intend to elaborate the interaction of micropolar nanofluids with the microbes in a symmetric channel flow.

Theoretical study on the influence of different solvents on the growth morphology of 3,4-bis(3-nitrofurazan-4-yl)furoxan (DNTF).

3,4-bis(3-nitrofurazan-4-yl)furoxan(DNTF) is a new energetic compound with high energy and high density, and it is an important component of propellant and melt cast explosive. In order to study the effect of solvent on the growth morphology of DNTF, the growth plane of DNTF in vacuum is predicted by attachment energy(AE) model, and then the modified attachment energy of each growth plane in different solvents is calculated by molecular dynamics simulation. The morphology of crystal in solvent is predicted by modified attachment energy (MAE) model. The factors affecting crystal growth in solvent environment are analyzed by mass density distribution, radial distribution function and diffusion coefficient. The results show that the growth morphology of crystal in solvent is not only related to the adsorption strength of solvent to crystal plane, but affected by the attraction of crystal plane to solute. The hydrogen bond plays an important role in the adsorption strength between solvent and crystal plane. The polarity of solvent has a great influence on the crystal morphology, and the interaction between the solvent with stronger polarity and the crystal plane is stronger. The morphology of DNTF in n-butanol solvent is closer to spherical, which can effectively reduce the sensitivity of DNTF. The molecular dynamics simulation is carried out under the COMPASS force field of Materials Studio software. Gaussian software is used to calculate the electrostatic potential of DNTF at B3LYP-D3/6-311 + G (d, p) theoretical level.

Experimental study of the mechanism of prepulse current on Z-pinch plasma using Faraday rotation diagnosis.

The prepulse current is an effective way to optimize the load structure and improve the implosion quality of the Z-pinch plasma. Investigating the strong coupling between the preconditioned plasma and pulsed magnetic field is essential for the design and improvement of prepulse current. In this study, the mechanism of the prepulse current on the Z-pinch plasma was revealed by determining the two-dimensional magnetic field distribution of preconditioned and nonpreconditioned single-wire Z-pinch plasma with a high-sensitivity Faraday rotation diagnosis. When the wire was nonpreconditioned, the current path was consistent with the plasma boundary. When the wire was preconditioned, the distributions of current and mass density presented good imploding axial uniformity, and the imploding speed of the current shell was higher than that of the mass shell. In addition, the mechanism of the prepulse current suppressing the magneto-Rayleigh-Taylor instability was revealed, which formed a sharp density profile of the imploding plasma and slowed the shock wave driven by the magnetic pressure. This discovery is essential and instructive for the design of preconditioned wire-array Z-pinch experiments.

Comparison of chromospheric diagnostics in a 3D model atmosphere

Context. The Hα line, one of the most studied chromospheric diagnostics, is a tracer of magnetic field structures, while the intensity of its line core provides an estimate of the mass density. The interpretation of Hα observations is complicated by deviations from local thermodynamic equilibrium (LTE) or instantaneous statistical equilibrium conditions. Meanwhile, millimetre (mm) continuum radiation is formed in LTE, and therefore the brightness temperatures from Atacama Large Millimetre-submillimetre Array (ALMA) observations provide a complementary view of the activity and the thermal structure of stellar atmospheres. These two diagnostics together can provide insights into the physical properties of stellar atmospheres, such as their temperature stratification, magnetic structures, and mass density distribution. Aims. In this paper, we present a comparative study between synthetic continuum brightness temperature maps at mm wavelengths (0.3 mm to 8.5 mm) and the width of the Hα 6565 Å line. Methods. We used the 3D radiative-transfer codes Multi3D and Advanced Radiative Transfer (ART) to calculate synthetic spectra for the Hα line and the mm continua, respectively, from an enhanced network atmosphere model with non-equilibrium hydrogen ionisation generated with the state-of-the-art 3D radiation magnetohydrodynamics (rMHD) code Bifrost. We use a Gaussian point spread function (PSF) to simulate the effect of ALMA’s limited spatial resolution and calculate the Hα versus mm continuum correlations and slopes of scatter plots for the original and degraded resolution of the whole box, quiet sun, and enhanced network patches separately. Results. The Hα linewidth and mm brightness temperatures are highly correlated and the correlation is highest at a wavelength of 0.8 mm, that is, in ALMA Band 7. The correlation systematically increases with decreasing resolution. On the other hand, the slopes decrease with increasing wavelength. The degradation of resolution does not have a significant impact on the calculated slopes. Conclusions. With decreasing spatial resolution, the standard deviations of the observables, Hα linewidth, and brightness temperatures decrease and the correlations between them increase, but the slopes do not change significantly. These relations may therefore prove useful in calibrating the mm continuum maps observed with ALMA.

Gravitational inversion for arbitrary surface mass distribution—application to earth's time-variable gravity with topography

SUMMARY The aim of this paper is gravitational inversion, that is, the determination of the mass density distribution of a central body when given the observed external gravitational field that is produced by the mass itself. This inversion for a 3-D mass distribution is known to be grossly non-unique; whereas that for a 2-D mass distribution on a spherical surface is known to be unique. The latter justifies the surface ‘mascon’, or equivalent-water-thickness, solutions when not considering any interior mass transports for the Earth's time-variable gravity as observed by the GRACE satellite. In this paper, using the gravitational multipole formalism cast in the framework of linear Hilbert space with the notion of inner product, we do two things further: (i) we prove mathematically that the 2-D gravitational inversion on an arbitrary surface is unique; and (ii) we derive the algorithm that leads to the unique exact 2-D mass distribution solution, up to a truncated finite spherical harmonic degree. This pertains directly to reaching refined GRACE mascon solutions that account for the actual Earth surface shape including the ellipsoidal figure and the topography. In the process, we also (re)formulate the exact equations, for spherical or arbitrary shape, unifying the formulae that have appeared in the GRACE-relevant literature.

Lifted particles from the fast spinning primary of the Near-Earth Asteroid (65803) Didymos

An increasing number of Near Earth Asteroids (NEAs) in the range of a few hundred metres to a few kilometres in size have relatively high spin rates, from less than 4 h, down to ∼2.2 h, depending on spectral type. For some of these bodies, local acceleration near the equator may be directed outwards so that lift off of near-equatorial material is possible. In particular, this may be the case for asteroid Didymos, the primary of the (65803) Didymos binary system, which is the target of the DART (NASA) and Hera (ESA) space missions. The study of the dynamics of particles in such an environment has been carried out – in the frame of the Hera mission and the EC-H2020 NEO-MAPP project – according to the available shape model, known physical parameters and orbital information available before the DART impact. The presence of orbiting particles in the system is likely for most of the estimated range of values for mass and volume. The spatial mass density of ejected material is calculated for different particle sizes and at different heliocentric orbit epochs, revealing that large particles dominate the mass density distribution and that small particle abundance depends on observation epoch. Estimates of take off and landing areas on Didymos are also reported. Available estimates of the system mass and primary extents, after the DART mission, confirm that the main conclusions of this study are valid in the context of current knowledge.

Photoproduction of e+e− in peripheral isobar collisions

We investigate the photoproduction of dielectrons in peripheral collisions of $_{44}^{96}\mathrm{Ru}+_{44}^{96}\mathrm{Ru}$ and $_{40}^{96}\mathrm{Zr}+_{40}^{96}\mathrm{Zr}$ at 200 GeV. With the charge and mass density distributions given by the calculation of the density functional theory, we calculate the spectra of transverse momentum, invariant mass, and azimuthal angle for dielectrons at 40--80% centrality. The ratios of these spectra in $\mathrm{Ru}+\mathrm{Ru}$ collisions over to $\mathrm{Zr}+\mathrm{Zr}$ collisions are shown to be smaller than $(44/40{)}^{4}$ (the ratio of ${Z}^{4}$ for Ru and Zr) at low transverse momentum. The deviation arises from the different mass and charge density distributions in Ru and Zr. So the photoproduction of dileptons in isobar collisions may provide a new way to probe the nuclear structure.

Alfvén velocity sudden increase as an indicator of the plasmapause

A radial distribution of ion mass density in the Earth’s magnetosphere may be different from an electron one when local narrow enhancement of heavy ions flux is presented, e.g. oxygen torus. This difference may be important for ultra-low-frequency (ULF) waves research that includes Alfvén waves whose eigenfrequency is dependent on Alfvén velocity and thus on mass density. One of consequences is a shift of the plasmapause location that is thought as a resonator and generation area for ULF waves. In the present study we found an Alfvén velocity increase by a factor of 1.65 or more within a radial distance of 0.5 RE to be a threshold that corresponds to the classic plasmapause definition that is the electron density drop by a factor of 5 or more within a radial distance of 0.5 RE. This result was obtained under all-proton plasma assumption to be confident that the Alfvén velocity may be used to detect the plasmapause with the same accuracy as by electron density. We wish to use this threshold to reveal the plasmapause location when heavier ions will be included and direct comparison with electron density is not possible.

Nonlinear Regge trajectories and saturation of the Hagedorn spectrum

We argue that two seemingly different phenomena, namely the well-known saturation of the Hagedorn exponential distribution and the less familiar saturation of Regge trajectories at resonance masses $m\approx$ 2-2.5 GeV are related and have the same origin: quark deconfinement. We show that the slope of the real part of non-linear Regge trajectories determines the prefactor $f(m)$ in Hagedorn's resonance mass density distribution $\rho(m)$. While the Hagedorn distribution comes from statistics, Regge trajectories contain dynamics.

Predicting chemoevasion potential of cancer cells from statistical chromatin packing behavior.

In malignancy, genetic, metabolic, or environmental insults may remodel chromatin structure, potentially increasing the plasticity of aberrant cell state transitions. Observed alterations to the epigenetic landscape of chromatin include gain-of-function mutations of Polycomb repressor EZH2 that block differentiation. Nucleosome remodeling and higher-order chromatin organization may also increase malignancy, with abnormalities ranging from prevalent mutations of ATP-dependent chromatin remodelers to mixing between transcriptionally active and inactive compartments. However, a universal relationship between chromatin structure and the disease state does not yet exist. Here, using the first principles of physics, we demonstrate that chromatin packing, or the statistical distribution of chromatin density in 4D, is a genome-wide regulator of phenotypic plasticity. The nucleus is a highly crowded, heterogeneous environment where DNA, RNA, proteins, and other macromolecules exert excluded volume effects, altering the kinetics and efficiency of transcription reactions. As chromatin is the major crowder in the nucleus, characterizing the chromatin mass density distribution facilitates a more complete understanding of transcription processes in a realistic nuclear environment. Combining high-resolution chromatin scanning transmission electron microscopy (ChromSTEM) and live-cell, label-free Partial Wave Spectroscopy (PWS) along with polymer physics-based analysis, we identified the existence of spatially separable packing domains, around 80 nm in radius. We then employed our understanding of fundamental chromatin packing to build a chromatin-mediated model of transcription that incorporates two pertinent aspects of phenotypic plasticity: transcriptional malleability, the ability of a cell to upregulate certain genes within a critical time frame, and transcriptional heterogeneity, a cell population's range of functional states. Finally, we extended our transcription model to predict how the average chromatin packing behavior of a cell population contributes directly to cancer cell survival upon chemotherapy treatment. Experimental observations confirmed model predictions, underlying the importance of chromatin packing in chemoevasion processes.

Multimodule Deep Learning Scheme for Elastic Wave Inversion of Inhomogeneous Objects With High Contrasts

In elastic wave inverse scattering problems, the material-property reconstruction, e.g. distributions of mass density, compressional wave speed, and shear wave speed from a limited set of measurement data, has attracted considerable research interest. However, simultaneous inversion of multiple parameters endures high computation costs, and reconstructed compressional and shear speeds may become unrealistic if no physical constraint is imposed. Meanwhile, because large objects with high contrasts over the background medium tend to induce high nonlinearity during the inversion process, it is difficult to obtain high-quality high-contrast material properties. To overcome such difficulties, we have developed a multi-module deep learning scheme with physical constraint for multi-parameter elastic wave inversion of high-contrast objects in inhomogeneous media. This scheme consists of (1) a preliminary imaging module (PIM), in which a deep residual network (ResNet) is employed to convert the scattered field data into the preliminary inversion images, (2) an image-enhancement module (IEM), in which a U-Net is employed to further enhance the image quality, and (3) a convolutional neural network (CNN) that is employed as the physical constraint module (PCM) to allow elastic wave parameters to satisfy actual physical constraint. Numerical examples have demonstrated that the proposed scheme not only accurately achieves multi-parameter elastic wave inversion, but also has good generalizability. Finally, the scheme can be applied to complex objects with high contrasts in both noise-free and noisy environments.

The uniformity and stability of cellular mass density in mammalian cell culture.

Cell dry mass is principally determined by the sum of biosynthesis and degradation. Measurable change in dry mass occurs on a time scale of hours. By contrast, cell volume can change in minutes by altering the osmotic conditions. How changes in dry mass and volume are coupled is a fundamental question in cell size control. If cell volume were proportional to cell dry mass during growth, the cell would always maintain the same cellular mass density, defined as cell dry mass dividing by cell volume. The accuracy and stability against perturbation of this proportionality has never been stringently tested. Normalized Raman Imaging (NoRI), can measure both protein and lipid dry mass density directly. Using this new technique, we have been able to investigate the stability of mass density in response to pharmaceutical and physiological perturbations in three cultured mammalian cell lines. We find a remarkably narrow mass density distribution within cells, that is, significantly tighter than the variability of mass or volume distribution. The measured mass density is independent of the cell cycle. We find that mass density can be modulated directly by extracellular osmolytes or by disruptions of the cytoskeleton. Yet, mass density is surprisingly resistant to pharmacological perturbations of protein synthesis or protein degradation, suggesting there must be some form of feedback control to maintain the homeostasis of mass density when mass is altered. By contrast, physiological perturbations such as starvation or senescence induce significant shifts in mass density. We have begun to shed light on how and why cell mass density remains fixed against some perturbations and yet is sensitive during transitions in physiological state.

Boiling heat transfer of nanofluids on the graphene membrane: A molecular dynamics simulation

The molecular dynamics method was used to study the boiling heat transfer of the base fluid (consisting only of water molecules) and nanofluid film on the graphene membrane. The nanofluid consists of water molecules and Cu nanoparticles of three sizes (0.8 nm, 1.2 nm, and 2 nm). Compared with the boiling heat transfer of the base fluid on the graphene membrane at high superheat, the influence of nanofluids with different particle sizes on boiling heat transfer was studied. The effects of the particle size, the water temperature at the radial distance of the particle surface, the molecular mass density distribution, the evaporation rate, and the heat flux on the boiling are analyzed. The heat transfer at the interface between nanoparticles and graphene mainly relies on phonons. The results show that the nanoparticles act as an indirect heat source to heat the surrounding water molecules and strengthen the boiling heat transfer at the solid-liquid interface, and the thermal conductivity at the interface increases with the increase of particle size. The atomic vibration frequencies between the graphene membrane and nanoparticles are well coupled in the low-frequency region, which enhances the boiling heat transfer.

Biomass conversion into recyclable strong materials

We review the conversion of waste biomass into recyclable materials using different methods of materials treatment such as thermal, mechanical and chemical processes. Renewable and sustainable biomaterials are increasingly becoming alternatives for synthetic strong materials, e.g. composites. The type of treatment of biomaterial will determine the form to which the biomass is converted and its subsequent applications. It is anticipated that the transformation will produce materials that have superior qualities, properties and characteristics. These include biopolymer materials such as cellulose and hemicellulose, which have all been obtained as products of treatment and extraction from plant materials such as lignocellulose. The main reason for inefficient biomass conversion has been found to be poor manipulation of composite properties during biomass treatment process. The treatment processes are expected to facilitate dehydration, dehydrogenation, deoxygenation and decarboxylation of the bulk biomass materials to target the formation of new compounds that may be used to make strong materials. Significance: This work demonstrates that plant material, as a solid-state biomass material for strong structural applications such as in biocomposites, is affected by factors that include the alignment of fibres, orientation of fibres, and mass density distribution. However, biocomposite materials have been found to be non-toxic, corrosionresistant, low-cost, and renewable. They are preferred because the materials possess high thermal stability, are biodegradable and recyclable, and have high biocompatibility, performance, strength, water-resistance, specific surface area and aspect ratio to qualify them for applications including biobricks for construction, slabs for paving, vehicle internal components, ultra-high temperature aerospace ceramics, and energy storage devices.

Molecular dynamics simulations of oil recovery from dolomite slit nanopores enhanced by CO2 and N2 injection

Shale oil reservoirs are dominated by micro-and nanopores, which greatly impede the oil recovery rates. CO2 and N2 injection have proven to be highly effective approaches to enhance oil recovery from low-permeability shale reservoirs, and also represent great potential for CO2 sequestration. Therefore, a better understanding of the mechanism of shale oil recovery enhanced by CO2 and N2 is of great importance to achieve maximum shale oil productivity. In this paper, the adsorption behavior of shale oil and the mechanism of enhancing shale oil recovery by CO2 and N2 flooding in dolomite slit pores are investigated by performing nonequilibrium molecular dynamics simulations. Considering the shale oil adsorption behavior, mass density distribution is analyzed and the results indicate that a symmetric density distribution of the oil regarding the center in the slit pore along the x-axis can be obtained. The maximum density of the adsorbed layer nearest to the slit wall is 1.310 g/cm3 for C8H18 , which is about 2.0 times of that for bulk oil density in the middle area of slit pore. The interaction energy and radial distribution functions (between oil and CO2 , and between oil and N2 ) are calculated to display the displacement behavior of CO2 and N2 flooding. It is found that CO2 and N2 play different roles: CO2 has strong solubility, diffusivity and a higher interaction energy with dolomite wall, and the oil displacement efficiency of CO2 reaches 100% after 1 ns of flooding; however, during N2 flooding, the oil displacement efficiency is 87.3% after 4 ns of flooding due to the lower interaction energy between N2 and dolomite and that between N2 and oil. Cited as: Guo, H., Wang, Z., Wang, B., Zhang, Y., Meng, H., Sui, H. Molecular dynamics simulations of oil recovery from dolomite slit nanopores enhanced by CO2 and N2 injection. Advances in Geo-Energy Research, 2022, 6(4): 306-313. https://doi.org/10.46690/ager.2022.04.05

The Numerical Solution of Poisson Equations using Wavelet based Multigrid Method

The potential energy field produced by a given charge or mass density distribution is described using the Poisson equation. This study presents a numerical solution to the Poisson equation using a wavelet-based multi-grid approach. The proposed method is superior to the existing method in terms of fast convergence and reduced processing time. Some of the problems are used to show the method's applicability and validity.

Improved strong lensing modelling of galaxy clusters using the Fundamental Plane: Detailed mapping of the baryonic and dark matter mass distribution of Abell S1063

Aims. From accurate photometric and spectroscopic information, we build the Fundamental Plane (FP) relation for the early-type galaxies of the cluster Abell S1063. We use this relation to develop an improved strong lensing model of the cluster, and we decompose the cluster’s cumulative projected total mass profile into its stellar, hot gas, and dark matter mass components. We compare our results with the predictions of cosmological simulations. Methods. We calibrate the FP using Hubble Frontier Fields photometry and data from the Multi Unit Spectroscopic Explorer on the Very Large Telescope. The FP allows us to determine the velocity dispersions of all 222 cluster members included in the model from their measured structural parameters. As for their truncation radii, we test a proportionality relation with the observed half-light radii. Fixing the mass contribution of the hot gas component from X-ray data, the mass density distributions of the diffuse dark matter haloes are optimised by comparing the observed and model-predicted positions of 55 multiple images of 20 background sources distributed over the redshift range 0.73 − 6.11. We determine the uncertainties on the model parameters with Monte Carlo Markov chains. Results. We find that the most accurate predictions of the positions of the multiple images are obtained when the truncation radii of the member galaxies are approximately 2.3 times their effective radii. Compared to earlier work on the same cluster, our model allows for the inclusion of some scatter on the relation between the total mass and the velocity dispersion of the cluster members. We notice a lower statistical uncertainty on the value of some model parameters. For instance, the main dark matter halo of the cluster has a core radius of 86 ± 2 kpc: the uncertainty on this value decreases by more than 30% with respect to previous work. Taking advantage of a new estimate of the stellar mass of all cluster members from the HST multi-band data, we measure the cumulative two-dimensional mass profiles out to a radius of 350 kpc for all baryonic and dark matter components of the cluster. At the outermost radius of 350 kpc, we obtain a baryon fraction of 0.147 ± 0.002. We study the stellar-to-total mass fraction of the high-mass cluster members in our model, finding good agreement with the observations of wide galaxy surveys and some disagreement with the predictions of halo occupation distribution studies based on N-body simulations. Finally, we compare the features of the sub-haloes as described by our model with those predicted by high-resolution hydrodynamical simulations. We obtain compatible results in terms of the stellar over total mass fraction. On the other hand, we report some discrepancies both in terms of the maximum circular velocity, which is an indication of the halo compactness, and the sub-halo total mass function in the central cluster regions.

Quantitative imaging of Caenorhabditis elegans dauer larvae during cryptobiotic transition

Upon starvation or overcrowding, the nematode Caenorhabditis elegans enters diapause by forming a dauer larva, which can then further survive harsh desiccation in an anhydrobiotic state. We have previously identified the genetic and biochemical pathways essential for survival—but without detailed knowledge of their material properties, the mechanistic understanding of this intriguing phenomenon remains incomplete. Here we employed optical diffraction tomography (ODT) to quantitatively assess the internal mass density distribution of living larvae in the reproductive and diapause stages. ODT revealed that the properties of the dauer larvae undergo a dramatic transition upon harsh desiccation. Moreover, mutants that are sensitive to desiccation displayed structural abnormalities in the anhydrobiotic stage that could not be observed by conventional microscopy. Our advance opens a door to quantitatively assessing the transitions in material properties and structure necessary to fully understand an organism on the verge of life and death.

Estimating the Parameters of the Hybrid Palatini Gravity Model with the Schwarzschild Precession of S2, S38 and S55 Stars: Case of Bulk Mass Distribution

We estimate the parameters of the Hybrid Palatini gravity model with the Schwarzschild precession of S-stars, specifically of the S2, S38 and S55 stars. We also take into account the case of bulk mass distribution near the Galactic Center. We assume that the Schwarzschild orbital precession of mentioned S-stars is the same as in General Relativity (GR) in all studied cases. In 2020, the GRAVITY Collaboration detected the orbital precession of the S2 star around the supermassive black hole (SMBH) at the Galactic Center and showed that it is close to the GR prediction. The astronomical data analysis of S38 and S55 orbits showed that, also in these cases, the orbital precession is close to the GR prediction. Based on this observational fact, we evaluated the parameters of the Hybrid Palatini Gravity model with the Schwarzschild precession of the S2, S38 and S55 stars, and we estimated the range of parameters of the Hybrid Palatini gravity model for which the orbital precession is as in GR for all three stars. We also evaluated the parameters of the Hybrid Palatini Gravity model in the case of different values of bulk mass density distribution of extended matter. We believe that proposed method is a useful tool to evaluate parameters of the gravitational potential at the Galactic Center.

The Structure of the Near-Surface Layer of the AAAC Overhead Power Line Wires after Operation and Its Effect on Their Elastic, Microplastic, and Electroresistance Properties

Overhead power-transmission lines are one of the most important components of modern infrastructure. Their service life is determined by the state of the near-surface defect layers (NSDLs) of wires constituting these lines. Both the structure and microstructure of the NSDLs of wires of the AAAC type (All Aluminum Alloy Conductor), which were in operation during 0 (new) to 62 years, were investigated by methods of the X-ray (XRD) and electron back-scattering diffraction, optical microscopy, and resistivity measurements, as well as by means of densitometric and acoustic measurements with layer-by-layer removal of the near-surface material by etching. Two characteristic thicknesses of the NSDLs were obtained, different methods providing close results, namely, ~30–50 μm and ~56–140 μm. According to the mass-density distribution (XRD), these characteristic thicknesses correspond to the depths from the surface where they occur, respectively, ~70% and ~99% of the density drop in comparison with the bulk density value. The rate of increase in NSDL thickness is ~4 μm/year in the interval from 0 to 18 years. Results of investigation of elastic and microplastic properties of wires after removal of ~35 μm of the upper layer are also presented.