Constituent Layers Research Articles

Hydrogen Sulfide Attenuates Aortic Remodeling in Aortic Dissection Associating with Moderated Inflammation and Oxidative Stress through a NO-Dependent Pathway.

Aortic dissection (AD) is a highly lethal vascular disease characterized by separation of the constituent layers of the aortic wall. An increasing body of research indicates that inflammatory response and oxidative stress are implicated in vascular remodeling, which plays a key role in the development of AD. Hydrogen sulfide (H2S) has been found to protect against various types of cardiovascular disease, including myocardial infarction, arthrosclerosis, and hypertension. However, research on the effect of H2S on AD is insufficient. This study therefore elucidated the effect of H2S on the development and progression of AD, and the potential mechanism involved. Using β-aminopropionitrile fumarate (BAPN) and angiotensin II (Ang-II)-induced AD animal models, the administration of NaHS (as H2S donor, 56 μmol/kg body weight/day) was found to retard the development of AD. Murine VSMCs (Movas) exposed to interleukin-6 (IL-6) (20 ng/mL) to induce phenotypic switch. Histological analyses indicated that H2S administration inhibited the accumulation of inflammatory cells in the aortic wall and the related expression of inflammatory genes. Additionally, H2S treatment elevated aortic superoxide dismutase (SOD) activity and ablated malonaldehyde (MDA) and nitric oxide (NO) levels. In mechanistic terms, H2S attenuated IL-6 induced a pathological VSMC phenotypical switch through NO modulation by N(G)-monomethyl-L-arginine acetate salt (L-NMMA) stimulation. H2S inhibits AD formation by decreasing the inflammatory response, and oxidative stress, and by positively participating in vascular remodeling. These findings suggest a role for H2S as a novel and promising therapeutic strategy to prevent AD development.

Naturally occurring layered mineral franckeite with anisotropic Raman scattering and third-harmonic generation responses

Vertically stacked van der Waals (vdW) heterostructures have introduced a unique way to engineer optical and electronic responses in multifunctional photonic and quantum devices. However, the technical challenges associated with the artificially fabricated vertical heterostructures have emerged as a bottleneck to restrict their proficient utilization, which emphasizes the necessity of exploring naturally occurring vdW heterostructures. As one type of naturally occurring vdW heterostructures, franckeite has recently attracted significant interest in optoelectronic applications, but the understanding of light–matter interactions in such layered mineral is still very limited especially in the nonlinear optical regime. Herein, the anisotropic Raman scattering and third-harmonic generation (THG) from mechanically exfoliated franckeite thin flakes are investigated. The observed highly anisotropic Raman modes and THG emission patterns originate from the low-symmetry crystal structure of franckeite induced by the lattice incommensurability between two constituent stacked layers. The thickness-dependent anisotropic THG response is further analyzed to retrieve the third-order nonlinear susceptibility for franckeite crystal. The results discussed herein not only provide new insights in engineering the nonlinear light–matter interactions in natural vdW heterostructures, but also develop a testbed for designing future miniaturized quantum photonics devices and circuits based on such heterostructures.

Effect of temperature on the deep drawing forming performance of Ti/Al laminates: experimental investigation and finite element analysis

In this study, Ti/Al laminates are deep-drawn at elevated temperatures to investigate the effect of temperature on forming performance using numerical and experimental methods. Equipment for warm deep drawing process in a vacuum atmosphere is developed. The corresponding deep drawing finite element model (FE model) is established and validated by thickness distribution along the drawn cups’ radial direction. Based on the developed FE model, the thickness strain in different temperature is compared. Following this, the process window is established to determine the optimum temperature. The ratio curve of plastic deformation to sliding (D/S curve) during warm deep drawing is established to characterize the sustainable formability of Ti/Al laminates. The results indicated that the maximum limit drawing ratio in 200°C is consistent with the minimum thickness reduction. The safe forming area narrows with the increase of the drawing ratio. The D/S curve is short and presented fluctuations in the middle-temperature section of 150–250°C, as revealed well sustainable formability. Furthermore, the thickness of constituent layers for Ti/Al laminates is measured from micromorphology diagrams and compared. It is observed that the thickness strain of outside layers has more possibility to decline in bottom radius and is higher in flange radius than inner layers.

Ultrafine‐Grained Laminated Metal Composites: A New Material Class for Tailoring Cyclically Stressed Components

The service life of technical components is often limited by the fatigue strength of the deployed materials. The accumulative roll bonding (ARB) process, which has the ability to produce ultrafine‐grained (UFG) laminated metal composites with tailored properties, offers a unique method to significantly enhance the fatigue life of materials that are cyclically loaded in three‐point bending. Detailed microstructural investigations reveal the material‐ and load‐specific deformation and damage mechanisms. Composites that have a sufficiently high difference in strength between the different constituent layers exhibit a significantly impeded crack growth and therefore an extended fatigue life at high stress amplitudes compared with those laminates with a rather similar strength of the different constituents. In the former composites, the fatigue crack is deflected at the material interface as it propagates from the softer to the harder layer. At low stress amplitudes, a prolonged fatigue life of the composites is mainly because of a significantly increased resistance to crack initiation. On the one side, this is as a result of the introduction of an UFG microstructure. On the other side, a load transfer toward stiffer layers in the interior of the composites also accounts for the enhanced fatigue life, if elastically dissimilar materials are combined in the right manner.

Elastic wave characteristics in damped laminated composite nano-scaled shells with different panel shapes

Characteristics of elastic mechanical waves in cross/angle-ply laminated composite doubly-curved nanoshells resting on a viscoelastic foundation are examined here. A higher-order refined shear deformation shell theory enriched by general nonlocal strain gradient elasticity accounting both nonlocality as well as strain gradient size-dependency is developed through assumptions of Hamiltonian principle, and afterward, a harmonic solution producer is handled with equations of motion to find the responses. As a first endeavor, the influences of lay-up numbers and sequences, fiber orientations of constituent layers, elastic and viscoelastic foundation coefficients, as well as wave number on the elastic wave propagation characteristic of a laminated composite nanoshell including cylindrical, spherical, hyperbolic, and elliptical shell panels substantially are examined.

PEMETAAN SEBARAN MATA AIR PANAS DI DAERAH OBJEK WISATA DESA PAWAN MENGGUNAKAN METODE GEOLISTRIK TAHANAN JENIS KONFIGURASI WENNER

Geothermal is one of the many natural resources that provides benefits to human such as using hot spring as a natural tourism spot. Hot spring in Pawan Village need to be researched to explore the presence of Hydrotermal. In this study, the distribution of hydrotermal that occur based on the resistivity of subsurface rocks resulting from geophysical exploration using resistivity geolelectric method with Wenner configuration. The result of this exploration were processed using Res2Dinv software to view soil layer data based on resistivity and points containe hot water aquifers. The resistivity values on the underground layer srtucture model is ≤ 10 Ohm.meter on each trajectory. The constituent layers of each track consist of hot water, clay, sand interlocking with clay, gravel sand and gravel.

First-Principles Study of a MoS2-PbS van der Waals Heterostructure Inspired by Naturally Occurring Merelaniite.

Vertically stacked, layered van der Waals (vdW) heterostructures offer the possibility to design materials, within a range of chemistries and structures, to possess tailored properties. Inspired by the naturally occurring mineral merelaniite, this paper studies a vdW heterostructure composed of a MoS2 monolayer and a PbS bilayer, using density functional theory. A commensurate 2D heterostructure film and the corresponding 3D periodic bulk structure are compared. The results find such a heterostructure to be stable and possess p-type semiconducting characteristics. Due to the heterostructure’s weak interlayer bonding, its carrier mobility is essentially governed by the constituent layers; the hole mobility is governed by the PbS bilayer, whereas the electron mobility is governed by the MoS2 monolayer. Furthermore, we estimate the hole mobility to be relatively high (~106 cm2V−1s−1), which can be useful for ultra-fast devices at the nanoscale.

Simplified Lateral Torsional Buckling (LTB) Analysis of Glass Fins with Continuous Lateral Restraints at the Tensioned Edge

Within multiple design challenges, the lateral torsional buckling (LTB) analysis and stability check of structural glass members is a well-known issue for design. Typical examples can be found not only in glass slabs with slender bracing members but also in facades and walls, where glass fins are used to brace the vertical panels against input pressures. Design loads such as wind suction give place to possible LTB of fins with LR at the tensioned edge and thus require dedicated tools. In the present investigation, the LTB analysis of structural glass fins that are intended to act as bracers for facade panels and restrained via continuous, flexible joints acting as lateral restraints (LRs) is addressed. Geometrically simplified but refined numerical models developed in Abaqus are used to perform a wide parametric study and validate the proposed analytical formulations. Special care is spent for the prediction of the elastic critical buckling moment with LRs, given that it represents the first fundamental parameter for buckling design. However, the LR stiffness and resistance on the one side and the geometrical/mechanical features of the LR glass members on the other side are mutually affected in the final LTB prediction. In the case of laminated glass (LG) members composed of two or more glass panels, moreover, further design challenges arise from the bonding level of the constituent layers. A simplified but rational analytical procedure is thus presented in this paper to support the development of a conservative and standardized LTB stability check for glass fins with LR at the tensioned edge.

Quantum geometric exciton drift velocity

We show that the dipole moment of an exciton is uniquely determined by the quantum geometry of its eigenstates, and demonstrate its intimate connection with a quantity we call the dipole curvature. The dipole curvature arises naturally in semiclassical dynamics of an exciton in an electric field, adding a term additional to the anomalous velocity coming from the Berry's curvature. In a uniform electric field this contributes a drift velocity akin to that expected for excitons in crossed electric and magnetic fields, even in the absence of a real magnetic field. We compute the quantities relevant to semiclassical exciton dynamics for several interesting examples of bilayer systems with weak interlayer tunneling and Fermi energy in a gap, where the exciton may be sensibly described as a two-body problem. These quantities include the exciton dispersion, its dipole curvature, and Berry's curvature. For two gapped-graphene layers in a vanishing magnetic field, we find the dipole curvature vanishes if the layers are identical, but may be non-zero when the layers differ. We further analyze examples in the presence of magnetic fields, allowing us to examine cases involving graphene, in which a gap is opened by Landau level splitting. Heterostructures involving TMDs are also considered. In each case the dipole and/or Berry's curvatures play out differently. In some cases, the lowest energy exciton state is found to reside at finite momentum, with interesting possibilities for Bose condensation. We also find situations in which the dipole curvature increases monotonically with exciton momentum, suggesting that the quantum geometry can be exploited to produce photocurrents from initially bound excitons with electric fields. We speculate on further possible effects of the semiclassical dynamics in geometries where the constituent layers are subject to the same or different electric fields.

WATT progresses production of residential SOFC unit components

The analytical technique DGT (Diffusive Gradients in Thin-films) is able to gain access to a wealth of information by carefully interpreting accumulation data from passive samplers with different configurations (i.e. different thicknesses of its constituent layers). A set of DGT devices were simultaneously deployed in solutions of Ni and nitrilotriacetic acid (NTA) of different concentrations to measure the availability of Ni in these solutions. Accumulations indicate that the availability of Ni depends on both the thickness of the resin and the thickness of the diffusive gel. In both cases, the lability degree increases as the thickness increases. As the formation of successive complexes (such as Ni(NTA)2) proceeds, the availability of the metal decreases, which is quantitatively explained by reducing the formulation to a case with only one complex, but with an effective dissociation rate constant that decreases as the concentration of NTA increases. Simple analytical expressions are reported to quantify the lability degree in the different DGT configurations. These results indicate that a set of different DGT devices can characterize the availability of a cation in a natural sample with uptake processes at different spatial or time scales. Alternatively, and from a more fundamental point of view, information on speciation, mobilities and labilities of the species present in natural samples can be obtained with a set of DGT configurations.

Experimental and analytical study on homogeneous and layered Al matrix syntactic foams under impact

Al matrix syntactic foams have been widely studied as impact protection materials. The impact behaviour of syntactic foams, especially for non-homogeneous structures, however, is not well understood. The impact response of Al matrix syntactic foams with both homogeneous and layered structures were studied experimentally and theoretically. Layered structures composed of large- and small-particle layers provided lower impact peak stress and higher ductility than the average values of the large- and small-particle layers. The energy absorption capacity of the layered structures is the sum of the energy absorption capacities of the constituent layers. An analytical model for stress and strain evolutions in Al matrix syntactic foams during impact was developed. The contact stress, inertia stress and base as a function of time was calculated as a function of impact velocity. The analytical model captures the key characteristics of stress fluctuation during impact. The predictions of the base stress agreed reasonably well with the experimental results, showing stress fluctuation with similar time interval and amplitude.

Availability of metals to DGT devices with different configurations. The case of sequential Ni complexation.

The analytical technique DGT (Diffusive Gradients in Thin-films) is able to gain access to a wealth of information by carefully interpreting accumulation data from passive samplers with different configurations (i.e. different thicknesses of its constituent layers). A set of DGT devices were simultaneously deployed in solutions of Ni and nitrilotriacetic acid (NTA) of different concentrations to measure the availability of Ni in these solutions. Accumulations indicate that the availability of Ni depends on both the thickness of the resin and the thickness of the diffusive gel. In both cases, the lability degree increases as the thickness increases. As the formation of successive complexes (such as Ni(NTA)2) proceeds, the availability of the metal decreases, which is quantitatively explained by reducing the formulation to a case with only one complex, but with an effective dissociation rate constant that decreases as the concentration of NTA increases. Simple analytical expressions are reported to quantify the lability degree in the different DGT configurations. These results indicate that a set of different DGT devices can characterize the availability of a cation in a natural sample with uptake processes at different spatial or time scales. Alternatively, and from a more fundamental point of view, information on speciation, mobilities and labilities of the species present in natural samples can be obtained with a set of DGT configurations.

Quasi-static indentation characteristics of sandwich composites with hybrid facesheets: Experimental and numerical approach

The load response, energy absorption, different damage mechanisms and failure modes of sandwich panels subjected to complete perforation by quasi-static indentation and the insights gleaned are presented in this paper. The experimental campaign was carried out on samples made of different type of facesheets: Aluminium, glass fibre-reinforced plastic and metal-composite hybrid (combined aluminium and GFRP) with two different core heights. Reliable numerical models were developed with appropriate constitutive material and damage model for facesheets and honeycomb core to complement the experimental observations. Good agreement between experimental results and numerical predictions in terms of force-displacement response and perforation damage ensure the fidelity of the developed numerical model. Effects of facesheet type, core height, energy absorbed by the constituent layers, damage evolution history are briefly discussed. It was observed that the energy absorption of sandwich panels and peak indentation force resisted by the top and bottom facesheet are strongly dependent on its metal-volume fraction, whilst unaffected with the height of the core. Recommendations for developing computationally efficient numerical models were provided.

Strong interlayer excitons in PtSe2/ZrS2 van der Waals heterobilayer

Capturing interlayer excitons with large binding energy plays a pivotal role in exploring the quantum Bose gas and developing excitonic devices at high temperature. In this work, we combine first-principles Kohn–Sham density functional theory and many-body perturbation theory to investigate the electronic and excited-state properties of two-dimensional van der Waals heterobilayer PtSe2/ZrS2, with the consideration of spin–orbit coupling. We find that the PtSe2/ZrS2 heterobilayer possesses a strong interlayer interaction and exhibits a type-II band alignment. We obtain the optical absorption spectrum by solving the Bethe–Salpeter equation with the inclusion of electron-hole interaction and observe emerged absorption peaks in the low-energy region compared to their constituent monolayers. According to the layer-resolved band structure and the interband transition weights in reciprocal space, we further confirm that these excitons are spatially separated into different constituent layers, featuring the landscape of interlayer excitons. Importantly, the binding energy for the lowest-energy interlayer exciton is estimated as large as 350 (meV), establishing PtSe2/ZrS2 as a promising candidate toward the realization of room temperature coherent phenomena and for the development of signal processing devices based on excitons.

Ultra-strong and ductile Ta/Co nanolaminates strengthened via grain-boundary expanding and interfacial sliding

The deformation and strengthening behavior of body-centered cubic/hexagonal closed-pack Ta/Co nanolaminates with individual layer thickness h ranging from 5 nm to 100 nm were studied via nanoindentation and micropillar compression tests. The deformation behavior of the Ta/Co micropillars transitioned from dislocation-dominated co-deformation/deformation at columnar grain boundaries in constituent layers with partial/major shearing of the micropillars at larger h to homogeneous deformation with plastic barreling through expansion of grain boundaries and interfacial sliding of constituent layers at a few nanometers’ length-scale. Also, increased amorphous/intermixed interfaces of the Ta/Co micropillars with a few nanometers’ h may have worked as constraints and sinks for dislocation pileups. The 5 nm h Ta/Co micropillars showed ultrahigh strength with a proof strength (σ0.2%) of ~2.32 GPa, a flow strength (σmax) of ~2.54 GPa and a yield strength (σys) of ~2.67 GPa, respectively, with minimal deformation even at 30% strain. It is worth noting that the 5 nm h Ta/Co micropillar showed an extraordinarily high σys (~2.67 GPa), which is 1.2 times higher than the highest yield strength of nanolaminates with at least one hcp constituent reported in the literature, to date. The dislocation pileup–based Hall–Petch strengthening model operated well with h = 25–100 nm, while the strength at h = 10 nm followed the confined layer slip strengthening mechanism. Surprisingly, the strength of the Ta/Co micropillars at h = 5 nm followed none of the strengthening mechanisms; rather, it became independent of h and mostly followed the plasticity at the grain boundaries and interfaces. The exceptionally high flow strength and ductility of the Ta/Co micropillars at h = 5 nm suggests the development of ultra-strong, yet ductile Ta/Co nanolaminates.

Energy flux optimization in 1D multiperiodic four-component photonic crystals

The results of theoretical and numerical studies of finite one-dimensional (1D) three-periodic photonic crystals of the structure [(ab)3(cd)3]3, consisting of four different materials (dielectric oxides Al2O3, SiO 2, TiO 2, and ZrO 2) are presented. We study the transmittivity spectra and partial energy fluxes of the TE- and TM-modes in the range of 1–5 μm in the vicinity of the first photonic bandgap depending on the incidence angle and frequency of light. The obtained results can be used to create precise polarization-sensitive devices for an input–output of the radiation into an optical fiber. The optimization of the considered multiperiodic structures has been achieved at the telecommunication wavelength 1.55 μm both by changing incidence angle and adjusting the topology (i.e. thicknesses of the constituent layers). We discuss a principle of a new type of polarization splitter on the basis of three-periodic photonic crystal.

Thermomechanical and sequential stress performance of photovoltaic backsheets

Photovoltaic backsheet technology is utilized to protect the interior components of solar modules from environmental stress as well as provide electrical insulation to the module. The growing demand for solar energy and longer module service life requirements have brought backsheet performance into focus. Despite being a protective packaging material, many backsheets have exhibited failure in the field, limiting the performance and service life of entire modules. Most backsheets consist of multiple polymeric layers laminated together using adhesives. A new backsheet, with a high performance polyamide structure, has been developed as the solution to module failure. Primarily, it contains a unique polyamide-ionomer alloy targeted at improved weather resistance. In this research, several photovoltaic industry standard backsheets, and the novel polyamide compositions of multilayered backsheets fabricated from the coextrusion process, were examined using thermomechanical analysis (TMA). The coefficient of thermal expansion (CTE) for entire backsheets and their constituent layers was used to model the thermomechanical behavior of various backsheet constructions. Subsequently, thermal cycling was performed in the TMA to examine the intrinsic thermal behavior of the backsheets. Thermal cycling in the TMA indicates the resilience and dimensional stability in the coextruded structures as opposed to the laminated structures. Lastly, results from a Module Accelerated Sequential Testing (MAST), are included to show the mechanical integrity of these backsheets after sequential exposure to stressors including damp heat, ultra-violet (UV) light radiation, and thermal cycling. The laminate backsheets deteriorated extensively after sequential exposure to these stressors, while the novel coextruded structures retained their physical properties.

Designing the Bending Stiffness of 2D Material Heterostructures.

2D monolayers represent some of the most deformable inorganic materials, with bending stiffnesses approaching those of lipid bilayers. Achieving 2D heterostructures with similar properties would enable a new class of deformable devices orders of magnitude softer than conventional thin-film electronics. Here, by systematically introducing low-friction twisted or heterointerfaces, interfacial engineering is leveraged to tailor the bending stiffness of 2D heterostructures over several hundred percent. A bending model is developed and experimentally validated to predict and design the deformability of 2D heterostructures and how it evolves with the composition of the stack, the atomic arrangements at the interfaces, and the geometry of the structure. Notably, when each atomic layer is separated by heterointerfaces, the total bending stiffness reaches a theoretical minimum, equal to the sum of the constituent layers regardless of scale of deformation-lending the extreme deformability of 2D monolayers to device-compatiblemultilayers.

Shear behavior of human skull bones

A shear-punch test (SPT) experimental method was developed to address the lack of shear deformation and failure response data for the human skull as a function of local bone microarchitecture. Improved understanding of skull deformation and fracture under varying stress-states helps implement mechanism-based, multi-axial material models for finite element analysis for optimizing protection strategies. Shear-punch coupons (N = 47 specimens) were extracted from right-parietal and frontal bones of three fresh-frozen-thawed human skulls. The specimens were kept as full through-thickness or segmented into the three skull constituent layers: the inner and outer cortical tables and the middle porous diploë. Micro-computed x-ray tomography (μCT) before and after SPT provided the bone volume fraction (BVF) as a function of depth for correlation to shear mechanisms in the punched volumes. Digital image correlation was used to track displacement of the punch above the upper die to minimize compliance error. Five full-thickness specimens were subjected to partial indentation loading to investigate the process of damage development as a function of BVF and depth. It was determined that BVF dominates the shear yield and ultimate strength of human skull bone, but the imposed uniaxial loading rate (0.001 and 0.1 s−1) did not have as strong a contribution (p = 0.181–0.806 > 0.05) for the shear yield and ultimate strength of the skull bone layer specimens. Shear yield and ultimate strength data were highly correlated to power law relationships of BVF (R2 = 0.917–0.949). Full-thickness and partial loaded SPT experiments indicate the diploë primarily dictates the shear strength of the intact structure.

Evaluation of graded layer in ground granulated blast furnace slag based layered concrete

This paper reports on the generation, properties, and spatial variability of the graded layer in functionally graded concrete (FGC) made using 20, 35, and 50% ground granulated blast furnace slag (GGBFS) as partial replacement of ordinary Portland cement (OPC). Two different layers of concrete, one being OPC based normal concrete and the other being GGBFS blended concrete were used to prepare the FGC specimens. The control concrete specimens were made with a single layer OPC or GGBFS concrete. Excluding the control concrete samples, three types of double-layered cube samples of 150 mm thick were prepared in various combinations of the thickness of constituent layers. These double-layered combinations were 25 mm + 125 mm, 75 mm + 75 mm, and 125 mm + 25 mm thick containing OPC concrete and GGBFS blended concrete respectively. The properties like compressive strength, the interfacial bond between two constituent layers, modulus of elasticity, micro-structure, and graded layer were examined. The formation, thickness, and properties of the graded layer at the interface of constituent layers were evaluated using elastic equations and microstructural studies like scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The investigation was conducted by applying the load parallel and perpendicular to the interface plane between constituent layers. The results showed that the properties of concrete improved in FGC compared to control. Formation of graded layer added value to the FGC. Among the specimens of various thickness combinations, the samples with 75 mm OPC concrete and 75 mm GGBFS concrete showed the best results when the load was applied parallel to the graded layer. Finally, environmental benefit in terms of embodied CO2, energy and cost benefit of the different mix proportion concrete are analysed. Further the effectiveness of FGC is also reported which has huge potential to be used in concrete structure elements.