Three-layer Structures Research Articles

Development of hybrid layered structures based on natural fabric reinforced composites and warp knitted spacer fabric for acoustic applications

This study deals with the development of hybrid layered structures combining natural fabric reinforced composite plates and warp knitted spacer fabric for acoustic applications, and the evaluation of the sound absorption performances. Vacuum infusion technique was used to produce the composite plates. Jute and linen woven fabrics were used as reinforcing materials, and they were impregnated with epoxy resin. The composite plates were combined with warp knitted spacer fabric in different stacking sequences in three-layer structures. All samples were subjected to the measurement of sound absorption property using impedance tube method. The combinations of a single layer and double layers of warp knitted spacer fabric with natural fabric reinforced composite in the appropriate sequences were found to provide superior sound absorption coefficients (SAC) compared to non-hybrid layered structures. Based on the overall evaluation regarding SAC, noise reduction coefficient (NRC), and weight of the structure, the sample with the best performance was regarded as the double layers of spacer fabric backed with a jute fabric reinforced composite plate. The integration of natural fabric reinforced composites with warp knitted spacer fabric had better sound absorption performance compared to the glass fabric reinforced composites, and they were considered to have the potential of being used in interior noise control mainly in vehicles and buildings.

A novel melanin complex displayed the affinity to HepG2 cell membrane and nucleus

Chitosan-melanin complex from Catharsius molossus L. has proven to possess superior pharmaceutical excipient performance and may be the new source of water-soluble protein-free natural melanin. Herein, it was enzymatically hydrolyzed into the chitooligosaccharide-melanin complex (CMC) whose main chemical units were composed of eumelanin and chitooligosaccharides and showed three-layer structures. Additionally, this biomacromolecule could self-assemble into 40 nm nanoparticles (CMC Nps) in a weakly acidic aqueous solution. Interestingly, CMC displayed strong affinity for cell membrane by binding the phosphatidylserine, glycoprotein, glycolipids and glycosaminoglycans accumulated on the surface of tumor cells, notably, CMC Nps could enter cells and mainly target the nucleus by interacting with DNA and/or RNA substrates located around the nucleus to disrupt the proliferation and apoptosis processes. The findings suggest CMC may be the novel material for subcellular organelle targeting of cancer cells.

Fano Approximation as a Fast and Effective Way for Estimating Resonance Characteristics of Surface Plasmon Structures

Developing efficient methods for evaluating resonance characteristics of resonance structures is of particular importance in sensing, spectroscopy, and optical filtration. In the past, the resonance characteristics were evaluated using exact approaches with time-consuming data post-processing algorithms. In this work, using the Fano approximation of the resonance line shapes appearing in spectra of planar plasmonic structures, we obtain analytical expressions for the surface field enhancement, resonance width and height, and sensitivity as functions of structural optical parameters. Approximate data for three-layer Au-, Ag-, Cu-, and Al-based structures in aqueous environment are compared with exact values to estimate the approximation error in the visible and infrared regions. We obtain overall good fits of the approximated estimations to the exact data over the wavelength regions considered, which ensure the validity of the Fano-based approach. Furthermore, by applying the Fano-based approach to gas sensing, we demonstrate that in the angular spectra of the three-layer structures, the excitation of propagating plasmons in the infrared region leads to narrower resonance line shapes due to the decrease in the plasmonic mode damping, resulting in higher sensitivities to changes in air environment. The Fano-based expressions tangibly increase the speed of calculations, provide an insight into fundamental aspects of resonance physics, and can be used for designing efficient sensing structures and characterizing optical changes in the environment.

In situ deformation characterization of density-graded foams in quasi-static and impact loading conditions

Digital image correlation is utilized to characterize deformation and strain fields developed within the layers of density-graded multilayered foam structures subjected to uniaxial quasi-static and dynamic compression. Three-layered graded structures fabricated from rigid polyurethane foams with nominal densities of 160, 240, and 320 kg/m3 are subjected to quasi-static and dynamic loading. The quasi-static measurements show that, irrespective of the loading direction, the densification is initiated in the lowest density layer and propagates into other layers later once the first layer is fully densified. The deformation mechanisms are different in the case of dynamic loading conditions than quasi-static loading. In the case of dynamic loading, the deformation mechanism depends on the sample orientation relative to the direction of the applied load. In cases where the higher density layers are impacted, the propagation of the elastic and compaction waves leads to partial deformation of the lowest density layer. Sample deformation continues in all layers upon the reflection of the stress waves from the distal end of the sample. A completely different deformation response is observed in cases where the lowest density layer is oriented towards the impact face. A detailed full-field analysis of strain and stress is performed. The mechanisms associated with the formation and propagation of stress waves from the impact end to the samples' distal end are discussed.

Тунелювання електромагнітних хвиль через несиметричну тришарову структуру, що містить провідний шар з негативною діелектричною проникністю

Subject and Purpose. In the context of growing anticipation of fundamentally new optical and radiophysical devices, the present study is concerned with the total electromagnetic wave tunneling through an asymmetric three-layer structure such that contains a conductive negative-permittivity layer. The aim of this work is to recognize how the asymmetry property of this three-layer structure acts on the effect of total wave tunneling with the frequency dispersion of the conductive negative-permittivity layer taken into account. Methods and Methodology. The frequency-dependent conditions of the total electromagnetic wave tunneling through an asymmetric three-layer structure are sought by numerical simulations. A universal approach based on the introduction of dimensionless frequencies and dimensionless layer thicknesses allows us to numerically investigate conditions of the total electromagnetic wave tunneling for any desired frequencies and geometric parameters of the asymmetric three-layer structure. Results. It has been shown that the asymmetry property of the three-layer structure can significantly change the total electromagnetic wave tunneling conditions. It has been demonstrated that parameters of the asymmetric three-layer structure can be selected in such a way as to modify the total electromagnetic wave tunneling conditions toward a desired practical application of the structure. It has been found that a proper choice of the parameters can minimize the action of the three-layer structure asymmetry on the electromagnetic wave tunneling effect. Conclusion. Asymmetric three-layer structures can be of use to effectively change conditions of the total electromagnetic wave tunneling in an effort to provide devices under development with desired characteristics.

Imaging features of microwave-ablated lesions of the VX2 tumors in rabbit lungs on computed tomography and magnetic resonance images and their correlations with pathological examination

Purpose This study aimed to explore the accuracy of different imaging methods for lesion volume estimation pre- and post-microwave ablation (MWA) as compared with that of pathological examination. Methods We used the VX2 cell line to establish the VX2 lung tumor model in rabbits, followed by MWA of the tumor. The imaging features of the VX2 tumors were documented. The volume of the tumors and the ablated lesions were measured and compared across imaging methods, using the pathological examination as reference. Results Tumors were successfully developed in 11 rabbits (age, 13.91 ± 1.38 weeks; weight, 2.15 ± 0.56 kg). The mean volume of the tumors was 2.05 ± 1.88 cm3. CT showed the strongest correlation with the pathologic examination results (r = 0.998, p<.001). MWA created three-layered structures that were delineated on MRI. The mean volume of the post-ablation lesion was 10.39 ± 8.93 cm3, and the measurement of the post-ablation volume on 3D-VIBE-T1WI showed the strongest correlation with the pathologic examination results (r = 0.991, p<.001). Conclusion Both CT and MRI are capable of depicting lung tumors. In terms of post-ablation evaluation, MR images could provide more versatile information. The 3D-VIBE-T1WI sequence provides more precise lesion volume evaluation after ablation compared with other methods.

Axisymmetric bending of a circular three-layer plate taking into account creep

The article discusses a method for calculating three-layer plates, in which a lightweight viscoelastic material acts as a middle layer. The technical theory of three-layer structures is used. The derivation of the resolving equation, the numerical and analytical solution of the problem, as well as comparison with the solution in the LIRA software package are presented.

Evaluation of the Response Analysis Approach Used in the Mechanistic-Empirical Pavement Design Guide

Asphalt concrete (AC) is a typical viscoelastic material exhibiting rate-dependent behavior. The rate-dependency of AC should be properly taken into consideration in pavement response analysis to accurately evaluate pavement performance and life. In the Mechanistic-Empirical Pavement Design Guide (MEPDG), the dynamic modulus master curve is used to account for the rate-dependency of the dynamic modulus of AC. However, the rate-dependent phase angle is ignored and a constant phase angle of 0 is assumed. The partial characterization of rate-dependent properties of AC in the MEPDG may lead to inaccurate results. This study compares the pavement responses computed using the MEPDG approach and the layered viscoelastic theory (LVET) which utilizes the complex modulus master curve to fully characterize the rate-dependent properties of AC. Typical three-layer pavement structures were analyzed at three temperatures (−10°C, 20°C and 50°C) and four speeds (10, 40, 80 and 120 km/h). The results show that the horizontal tensile stresses at the bottom of cement-treated base layer obtained from the two approaches are almost the same, and for other responses analyzed, the results obtained from the MEPDG approach are larger than those from the LVET approach, especially for the responses in the AC layer. The normalized difference of the vertical compressive strain at the mid-depth of the AC layer between the two approaches can be up to 100% and that for the horizontal tensile strain at the bottom of the AC layer can be more than 50%.

NOD-like receptor-mediated plant immunity: from structure to cell death.

Animal and plant immune systems use intracellular nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) to detect pathogens, resulting in the activation of immune responses that are often associated with localized host cell death. Whereas vertebrate NLRs detect evolutionarily conserved molecular patterns and have undergone comparatively little copy number expansion, plant NLRs detect virulence factors that have often diversified in plant pathogen populations, and thus plant NLRs have been subject to parallel diversification. Plant NLRs sense the presence of virulence factors with enzymatic virulence activity often indirectly through their modification of host target proteins. By contrast, phytopathogenic virulence factors without enzymatic activity are usually recognized by NLRs directly by their structure. Structural and biochemical analyses have shown that both indirect and direct recognition of plant pathogens trigger the oligomerization of plant NLRs into active complexes. Assembly into three-layered ring-like structures has emerged as a common principle of NLR activation in plants and animals, but with distinct amino-terminal domains initiating different signalling pathways. Collectively, these analyses point to host cell membranes as a convergence point for activated plant NLRs and the disruption of cellular ion homeostasis as a possible major factor in NLR-triggered cell death signalling.

Numerical modeling of a double-walled spherical reservoir

Extensive and important class of multilayer shell structures is three-layer structures. In a three-layer structure, a rigid filler plays an important role, due to which the bearing layers are spaced that gives the layer stack high rigidity and durability with a relatively low weight. By combining the thicknesses of the bearing layers and the filler, the desired properties of a three-layer shell structure can be achieved. Compared with traditional single-walled, three-layer construction has increased rigidity and durability, which allows reducing the thickness and weight of the shells.&#x0D; In order to reduce the metal content of the spherical reservoir for storing liquefied gases, this work considers the design of a double-walled reservoir, in which the inter-wall space is filled with reinforced polyurethane. Numerical modeling made it possible to determine the parameters of the stress-strain state of the structure with an error of no more than 5 %. It has been established on the example of a reservoir with a volume of 4000 m3 that the spatial structure of the spherical reservoir wall can reduce the metal content up to 19 %. Field of application for the research results is the assessment of the stress-strain state of spherical reservoirs at their designing.&#x0D; Method for building the structure of a double-walled spherical reservoir in the SCAD software has been developed, which allows calculating the stress-strain state (SSS) by the finite element method.&#x0D; Numerical model of a double-walled spherical reservoir has been developed. It was found that to obtain calculation results with an error of P ≤ 5 % the size of the final element should not exceed 300×300×δ mm.&#x0D; Design of a double-walled spherical reservoir was investigated. Design parameters have been established to ensure the operational reliability of the structure with a decrease in metal content in comparison with a single-wall reservoir by 19 %.

Influence of approach of layers of a three-layer structure on its stress-strain state

A refined method for calculating three-layer structures (TLS) in the zones of edge effects is considered, taking into account the influence of the approach of load-bearing layers on the stress-strain state (SSS) of the TLS. To determine the SSS of TLS, approximating strain distribution functions in the filler are used, which should correspond to the actual work of three-dimensional structures. Keywords: three-layer structure, load-bearing layer, approach of layers, approximating function, filler. hairulla213@mail.ru

Combustion of Lean Methane–air Flames in Mesoscale Reactor with Opposite Gas Flows

ABSTRACT In this work, we study a countercurrent premixed rich-lean coaxial reactor to realize an overall lean combustion of hydrocarbon fuels. Flame topology and stability of the axially symmetric reaction fronts of methane-air mixtures are investigated both numerically and experimentally. These studies show that depending on the equivalence ratio of the mixture fed into the inner tube, playing the role of supporting a pilot burner, there can occur two or three-layered stable flame structures. It is demonstrated that flames can be stabilized over a wide range of mixture compositions and flow rates. In particular, it is possible to stabilize methane-air flames with the overall equivalence ratio below the lean flammability limit for this mixture due to the existence of the weak supporting flame and combined effect of the flame stretch and heat recirculation realized in the examined configuration. The diverse unsteady combustion modes, including flame oscillations and flame periodic extinction and ignition, are also found. The prospects of further investigations are discussed.

Self-organized multicellular structures from simple cell signaling: a computational model

Recent synthetic biology experiments reveal that signaling modules designed to target cell–cell adhesion enable self-organization of multicellular structures Toda et al (2018 Science 361 156–162). Changes in homotypic adhesion that arise through contact-dependent signaling networks result in sorting of an aggregate into two- or three-layered structures. Here we investigate the formation, maintenance, and robustness of such self-organization in the context of a computational model. To do so, we use an established model for Notch/ligand signaling within cells to set up differential E-cadherin expression. This signaling model is integrated with the cellular Potts model to track state changes, adhesion, and cell sorting in a group of cells. The resulting multicellular structures are in accordance with those observed in the experimental reference. In addition to reproducing these experimental results, we track the dynamics of the evolving structures and cell states to understand how such morphologies are dynamically maintained. This appears to be an important developmental principle that was not emphasized in previous models. Our computational model facilitates more detailed understanding of the link between intra- and intercellular signaling, spatio-temporal rearrangement, and emergent behavior at the scale of hundred(s) of cells.

Plasmon modes in three-layer graphene with inhomogeneous background dielectric

The aim of this paper is to investigate collective excitations and the damping rate in a multilayer structure consisting of three monolayer graphene sheets with inhomogeneous background dielectric at zero temperature within random-phase approximation. Numerical results show that one optical branch and two acoustic ones exist in the system. The lowest frequency branch disappears as touching single-particle excitation area boundary while two higher frequency branches continue in this region. Calculations also illustrate that the frequency of optical (acoustic) mode(s) decreases (increase) as interlayer separation increases. The inhomogeneity of background dielectric and the imbalance in the carrier density in graphene sheets decline significantly plasmon frequencies in the system. Therefore, it is meaningful to take into account the effects of inhomogeneous background dielectric when calculating collective excitations in three-layer graphene structures.

Effects of windbreak Forest according to tree species and planting methods based on wind tunnel experiments

To provide a basis for the effective and efficient design of windbreak forests, wind tunnel tests were conducted to analyze the protection against wind afforded by the use of various species and various structures of planted trees. Various row-based planting structures were used in an attempt to find the most effective arrangement of a windbreak forest. Four types of structures were studied: a simple structure of coniferous trees (1, 2, or 3 rows of Pinus thunbergii), a simple structure of broadleaf trees (1, 2, or 3 rows of Quercus acutissima), mixed structure 1 (3 rows: P. thunbergii, Q. acutissima and P. thunbergii) and mixed structure 2 (3 rows: Q. acutissima, P. thunbergii and Q. acutissima). The testing materials were 3-year-old P. thunbergii and 8-year-old Q. acutissima. As the height of the testing part was 2.0 m, the height of trees was cut to make it 1.5 m based. The trees were fixed in a vase of 30 cm (Width) × 30 cm (Height). The experimental simulation model was designed 3meter (Width) × 2meter (Height) × 9 meter (Length). Putting porosity between trees aside, it was appropriate with the 7.5% of black ratio. All arrangements of P. thunbergii rows decreased the wind speed at every measurement point; especially, the 3-row structure of P. thunbergii showed a wind speed reduction of more than 15% greater than the two single-row structures studied. The wind speed reduction of P. thunbergii was maximized at a distance 1 m downwind from the last row, with wind speed increasing further downwind. Also, comparing the effect of decreasing wind speed according to the height in one-layered structure, middle-height marked the best decrease and lowered as it goes far from the middle-height. This can be explained with the cone-shaped water pipe. However, observing that the same phenomenon does not happen in three-layered structures, it was found that the difference due to different shapes of the water pipe can be offset by adding a row of plants. Therefore, using the alternating structure of coniferous, broadleaf, and coniferous rows would be a better choice, offering a similar effect with less risk of loss to disease and insects.

RESEARCHES OF THE POSSIBILITY OF ASSESSING DAMAGE TO THREE-LAYER STRUCTURES BY IMPACT DAMAGE BY METHOD OF COMPUTED X-RAY TOMOGRAPHY

This article describes the results of researches on the assessment of the applicability of the method of computer X-ray tomography for monitoring the internal structure of three-layer structures with carbon composite cladding and aluminum honeycomb, a general description of the method is given. It has been experimentally shown that the method of computed X-ray tomography allows one to evaluate the porosity of carbon composite plating, to identify stratifications resulting from impact. Comparative results of the non-destructive testing of a three-layer carbon composite sample made by autoclave molding from a unidirectional carbon tape and an adhesive epoxy matrix and aluminum honeycomb before and after impact are presented. It was revealed that for the upper lining of a carbon composite, the maximum number of macrodefects of the type stratification occurs directly in the impact zone and adjacent local areas, and leads to a change in the geometry of the skin and honeycomb aggregate, as well as a multiple increase in porosity in comparison with the results of the preimpact test. It should be noted that in the lower skin the porosity due to impact increases slightly, evenly distributed over the volume of the skin, which indicates the occurrence of cracking in the polymer matrix of the carbon composite.Thus, the method of computer x-ray tomography is an effective tool for controlling the damage of three-layer structures by impact.

Mobility of magnetic helicoid in holmium nano-layer

Spin valves with holmium layers and three-layer structures metal/Ho/metal were prepared by magnetron sputtering. A holmium layer in the spin valves is polycrystalline with weak axial <002> texture. The structural coherence length along the hexagonal c-axis is approximately 2/5 of the total thickness of the holmium layer. Field dependences of the spin valves magnetoresistance were measured at different temperatures. Correlation was revealed between magnetic state in holmium layer and the shape of magnetoresistive curve. Deviation of magnetic moments of the reference layer and the adjacent part of holmium from the applied magnetic field was investigated. The field induced mobility of the magnetic helicoid in holmium layers was revealed.

Magnetoelectric and magnetostriction characteristics of symmetric three layered structures of nickel - lead zirconate titanate – nickel and permendure – lead zirconate titanate – permendure

The magnetoelectric and magnetostriction characteristics of the symmetric three-layered structures are presented. The composite structures were formed like sandwich structures with a piezoelectric layer between two identical magnetostrictive layers using epoxy adhesive. An analytical expression for magnetoelectric voltage coefficient in terms of parameters for magnetostrictive and piezoelectric subsystems is presented. On the basis of this expression determination of magnetostriction characteristics via magnetoelectric response was offered. This procedure was tested for these three layered structures using the field dependences of the magnetoelectric response. The magnetostrictive characteristics obtained are in good agreement with results, obtained by other methods.

Melilite condensed from an 16O-poor gaseous reservoir: Evidence from a fine-grained Ca-Al-rich inclusion of Northwest Africa 8613

Fine-grained Ca-Al-rich inclusions (FGIs) in CV chondrites are suggested to be condensates from the solar nebular gas and thus captured O-isotopes from the gas. We conducted a combined study of petrographic observations and in situ O-isotope analysis using secondary ion mass spectrometry for an FGI, named HKD01, from the reduced CV chondrite Northwest Africa 8613. HKD01 has an irregular shape and petrographically three-layered structures: a hibonite-rich core, a spinel-rich core, and a mantle. Each petrographic domain contains melilite, hibonite, and spinel with variable proportions of those minerals. The O-isotopic compositions of the constituent minerals plotted along the slope-1 line on an O three-isotope diagram ranged between Δ17O ∼ −23‰ and 1‰. Hibonite and spinel are uniformly 16O-rich (Δ17O = −23‰) irrespective of their occurrences, while melilite crystals exhibit wide O-isotope variations ranging between Δ17O ∼ −23‰ and 1‰. The O-isotopic composition in a melilite crystal changes abruptly within ∼2 µm, indicating that disturbances of O-isotopes in melilite after condensation are less than ∼2 µm. Because the melilite in the FGI typically has grain sizes of 5–10 µm, the abrupt change of O-isotopic composition demonstrates that melilite crystals in the FGI preserve the O-isotopic composition of the nebular gas from which they condensed. In the mantle, aggregates of melilite crystals, having relatively large grain sizes (10–25 µm) and oscillatory chemical zoning, exhibit 16O-poor compositions with small variations ranging between Δ17O ∼ −4 and 1‰. Among them, a large melilite crystal (∼20 µm) with homogeneously 16O-poor composition (Δ17O ∼ 0‰) across the single crystal was found. The coexistence of 16O-poor and 16O-rich melilite crystals without O-isotope disturbances in the FGI reveals that 16O-poor (Δ17O ∼ 0‰) nebular gas existed in the formation region of the FGI HKD01 in addition to 16O-rich (Δ17O ∼ –23‰) nebular gas.

Magnetoelectric Effect in Three-Layer Asymmetric Structures in the Region of Bending Vibrational Modes

A theory of the magnetoelectric effect in three-layer asymmetric structures composed of a piezoelectric layer and two magnetostriction layers with opposite magnetostriction signs is presented. The thickness ratio of the layers is obtained, at which this effect is maximum. It is shown that the sign of the magnetoelectric coefficient changes to opposite (with respect to the initial two-layer structure) with an increase in the third-layer thickness. It is established that the magnetoelectric coefficients of the structures with different arrangements of the layers with positive and negative magnetostriction have opposite signs.