Modulus Measurements Research Articles

The interdependence of thermodynamic, mechanical, and structural properties in saturated phospholipid membranes.

Lipid membranes undergo conformational and structural changes when they transition from the gel phase to the fluid phase. These phase transitions are accompanied by changes in the lipid packing and the membrane mechanical properties, as previously reported in experimental studies and molecular dynamics simulations. Here, we report a simple direct approach for calculating the mechanical properties of single-component lipid membranes using size-dependent calorimetry measurements, performed on lipid vesicles with different mean diameters. Using differential scanning calorimetry (DSC), we find that the melting temperature, associated with the gel-to-fluid phase transition, increases with the vesicle diameter until it approaches an asymptotic value representative of uncurved membranes. More importantly, fits of the transition temperature as a function of vesicle size show a clear dependence on the structural and mechanical properties of the membranes, i.e., the area-per-lipid and the area compressibility modulus. Our method is validated by comparing the obtained parameters against results from small-angle X-ray scattering measurements and Langmuir monolayer compression studies. The findings indicate that the thermodynamic properties of vesicular lipid membranes depend on their nanoscale curvature and corresponding energetic contributions for membrane stretching and bending. When combined with measurements of the bending rigidity modulus by neutron spin-echo spectroscopy, our approach yields the interleaflet coupling constant, a sought-after quantity describing the extent of interactions between the two membrane leaflets. The application of this approach to saturated phospholipid membranes with molecular additives (e.g., cholesterol) provides a platform to assess the resultant effects on interleaflet interactions.

New Tsallis holographic dark energy with apparent horizon as IR-cutoff in non-flat Universe

In this work, new Tsallis holographic dark energy with apparent horizon as IR-cutoff is constructed in a non-flat Friedmann–Lemaitre–Robertson–Walker Universe. The accelerating expansion phase of the Universe is described by using deceleration parameter, equation of state parameter and density parameter by using different values of new Tsallis holographic dark energy (NTHDE) parameter “[Formula: see text]”. The NTHDE Universe’s transition from a decelerated to an accelerated expanding phase is described by the smooth graph of deceleration parameter. Depending on distinct values of Tsallis parameter “[Formula: see text]”, we have explored the quintessence behavior of the equation of state parameter. We used Hubble data sets obtained using Cosmic Chronometric methods and distance modulus measurement of Type Ia Supernova to fit the NTHDE parameters. Stability of our model by analyzing the squared speed of sound is investigated as well.

Comparison of the Effectiveness of Fluoride versus Grape Seed Extract in Biomimetic Remineralization of Dentin

This study aims to compare the remineralization efficiency of grape seed extract versus fluoride in artificial carious dentin lesions in the biomimetic remineralization procedure. One hundred and twelve extracted impacted human teeth were demineralized for 10 days and divided into 4 groups. Demineralization group (DM), remineralization group (RM group), remineralization fluoride group (RM F), remineralization grape seed extract group (RM GSE). Demineralization (DM) group were stored in physiological saline after demineralization. RM F was kept in 1000 ppm fluorine solution and RM GSE was kept in 6.5% grape seed extract for 10 min. RM, RM F, RM GSE groups were stored in simulated body fluid (SBF) with biomimetic analogues and Portland cement discs for 6 weeks. The specimens were evaluated by microhardness test, elasticity modulus measurement, and scanning electron microscope (SEM) analysis. Kruskal–Wallis H test with Bonferroni correction was used for between-group comparisons. Microhardness and elasticity modulus values differed significantly among the groups, with the highest values in the RM-GSE group, followed by the RM-F group, RM group, and DM group. SEM images showed granular structure formations in the RM-GSE and RM-F groups. It is concluded that although remineralization can occur by mineral precipitation in structures with high organic matrix density such as dentin, the collagen structure must be supported to increase the degree of remineralization.

Low cycle fatigue properties assessment and damage influence on DP 500/800 steel sheet

A dual phase (DP500/800) steel sheet (1.6 mm thickness) was evaluated by means of low cycle fatigue (LCF). The fatigue properties of the material were assessed by means of the cyclic elastic modulus determination at half-life as well as by the plastic strain amplitude measurements. Both methods show a good correlation and high reliability, however, the plastic strain amplitude approach tends to fit better to the experimental results. From a parametric analysis performed, it was observed that the plastic strain amplitude approximation could be more suitable to assess the fatigue properties for LCF of the material due to an improved correlation of the computed cyclic elastic modulus in comparison to the cyclic elastic modulus measurements at half-life. Both methods showed that, for strain amplitudes higher than εa = 0.004, the cyclic elastic modulus tends to be lower than 210 GPa, meanwhile for lower strain amplitudes, the cyclic elastic modulus tends to increase. An evaluation by X-ray Diffraction technique allowed to determine that the increment of residual equivalent strain contributes to the cyclic elastic modulus diminution.

In vivo assessment of the elastic properties of the external anal sphincter in term pregnant women using shear wave elastography.

The objective was to assess the intraobserver intersession and interobserver intrasession reliability of shear wave elastography applied to the external anal sphincter in term pregnant women. This prospective study involved nulliparous pregnant women at 37 weeks or more with two visits (V1: one observer; V2 two observers) planned within a 12-h to 7-day interval. Measurements were performed using an Aixplorer V12® device with an SL 18-5 linear probe using a transperineal approach, allowing a measurement of the shear modulus (SM) in kPa. Measures were performed at rest, Valsalva maneuver, and maximal contraction. Reliability was assessed using the intraclass correlation coefficient (ICC). The study was approved by an ethics committee (ID RCB: 2020-A00764-65). A total of 37 women were included. Intraobserver reliability was excellent at rest (ICC = 0.91 [0.84-0.95) and good during the Valsalva maneuver (ICC = 0.83 [0.72-0.90]) and contraction (ICC = 0.85 [0.75-0.91]). Interobserver reliability was good at rest (ICC = 0.79 [0.66-0.87]) and during Valsalva (ICC = 0.84 [0.73-0.90]), but moderate during contraction (ICC = 0.70 [0.53-0.82]). Shear wave elastography is a reliable tool for assessing the elastic properties of the external anal sphincter in term pregnant women.

Flow‐To‐Fracture Transition of Linear Maxwell‐Type Versus Yield Strength Fluids by Air Injection—Implications for Magma Fracturing

AbstractTo illuminate brittle and ductile fracturing of magma, we investigated bubble expansion and fracturing in two contrasting fluids: a Maxwell‐type viscoelastic fluid and a Bingham‐type yield‐strength fluid. Measurements of the complex shear modulus, G′ + iG″ (i is the imaginary unit), under small‐strain oscillation showed that both fluids are elastic (G′ > G″) with similar rigidity. Viscous behavior (G′ < G″) appeared at lower frequency in the Maxwell fluid but at larger strain in the Bingham fluid. When we injected air into the Maxwell fluid, bubbles expanded viscously at low flux, fractured in a brittle manner at high flux, and behaved transitionally at intermediate flux. In contrast, we observed no fracturing in the Bingham fluid. This demonstrates that the G′ > G″ condition is insufficient to infer that brittle fracturing can occur. Brittle fracturing of the Maxwell fluid occurred not at a critical strain rate but under decreasing strain rate and increasing stress.

Development and performance study of fiber Bragg grating flexible cable strain sensor

Strain is an important parameter in structural testing. How to accurately obtain the strain of low modulus (or flexible) and rigid structures is a hot issue in structural testing. This paper develops a fiber Bragg grating (FBG) flexible cable strain sensor protected by flexible armored tube. Firstly, the sensing and train transfer properties of the developed sensor are studied. And then, the developed sensors are installed on the surface of flexible Polyvinyl Chloride(PVC) pipe by welding and adhesive layout respectively. In comparison of the measuring strain and that obtained by the finite element analysis, the developed sensor can effectively measure the strain of PVC pipe under the two sensor layout, which proves it is a promising sensor for the strain measurement of low modulus and rigid structures simultaneously.

Measurement of Local Elastic Modulus of Thin Plates Using Lamb Wave Dual-Modal Resonance Motivated by Laser Ultrasound

Measurement of Local Elastic Modulus of Thin Plates Using Lamb Wave Dual-Modal Resonance Motivated by Laser Ultrasound

Characterizing rheological properties and microstructure of thioester networks during degradation.

Covalent adaptable networks are designed for applications including cell and drug delivery and tissue regeneration. These applications require network degradation at physiological conditions and on a physiological timescale with microstructures that can: (1) support, protect and deliver encapsulated cells or molecules and (2) provide structure to surrounding tissue. Due to this, the evolving microstructure and rheological properties during scaffold degradation must be characterized. In this work, we characterize degradation of covalent adaptable poly(ethylene glycol) (PEG)-thioester networks with different amounts of excess thiol. Networks are formed between PEG-thiol and PEG-thioester norbornene using photopolymerization. These networks are adaptable because of a thioester exchange reaction that takes place in the presence of excess thiol. We measure degradation of PEG-thioester networks with L-cysteine using multiple particle tracking microrheology (MPT). MPT measures the Brownian motion of fluorescent probe particles embedded in a material and relates this motion to rheological properties. Using time-cure superposition (TCS), we characterize the microstructure of these networks at the gel-sol phase transition by calculating the critical relaxation exponent, n, for each network with different amounts of excess thiol. Based on the measured n values, networks formed with 0% and 50% excess thiol are tightly cross-linked and elastic in nature. While networks formed with 100% excess are similar to ideal, percolated networks, which have equal viscous and elastic components. MPT measurements during degradation of these networks also measure a non-monotonic increase in probe motility. We hypothesize that this is network rearrangement near the phase transition. We then measure macroscopic material properties including the equilibrium modulus and stress relaxation. We measure a trend in bulk network properties that agrees with the values of n. Elastic modulus and stress relaxation measurements show that networks with 50% excess thiol are more elastic compared to the other two networks. As the amount of excess thiol is increased from 0% to 50%, the networks become more elastic. Further increasing excess thiol to 100% reduces the elastically effective cross-links. We hypothesize that these properties are due to network non-idealities, resulting in networks with 50% excess thiol that are more elastic. This work characterizes dynamic rheological properties during degradation, which mimics processes that could occur during implantation. This work provides information that can be used in the future design of implantable materials enabling both the rheological properties and timescale of degradation to be specified.

ATF Claddings after High-Temperature Steam Oxidation: WDS and Nanoindentation Studies to Characterize in-depth Material Changes

After the Fukushima accident in 2011 year, ATF nuclear fuel cladding concept was accelerated to achieve the reactor operation with the new accident tolerant structural materials. However, several designed solutions do not fulfil the accident tolerant concept but particularly increase the corrosion resistance of Zr-cladding tubes at normal operating conditions, so-called “Advaced Technology Fuel, EATF”. Cr-coated zirconium claddings following the first concept, have been the widely tested and the first full Cr-coated fuel rods have been planned to operate in LWR reactor conditions around the 2022 year. Our contribution describes the Cr-coated Zr-%1Nb cladding tube microstructure after high-temperature steam oxidation at 1200°C by means of Scanning Electron Microscopy and nanoindenta-tion methods. The article is focused on WDS line-profile studies of oxygen and chromium diffusion into the Zr-matrix. The increased Cr-diffusion with oxygen is evident causing a change in local me-chanical properties which is well-described by measurements of nanohardness and Young's modulus. In addition, the developed methodology of the WDS & nanoindentation line-analyses was also opti-mized to apply in hot-cell conditions to measure the effect of neutron-irradiation on the different coat-ings and coating/matrix interface.

Microscopy-based approach for measuring asphalt film thickness and its impact on hot-mix asphalt performance

The thickness of the asphalt binder’s film surrounding the aggregate particles in Hot-Mix Asphalt (HMA) plays a significant role in the durability of the pavement. This study introduces a new approach for determining the film thickness of the asphalt binder using a reflective digital stereo microscope. Image analysis was performed using the thresholding process to distinguish the aggregates, the voids, and the asphalt binder from each other using ImageJ software. Six different mixtures were investigated using this approach. The same materials were used to fabricate those mixtures but with different aggregate gradations. The thickness of the asphalt film was correlated to the dynamic modulus (E*) and rutting measured by flow number. The analysis showed that asphalt film thickness plays a major role in the dynamic modulus measurements at intermediate and high-temperature ranges. The correlation of asphalt film thickness with rutting showed a significant decrease in the flow number as the asphalt film thickness increased. This was more significant for gap-graded and Bailey’s gradation asphalt mixtures compared to the dense-graded asphalt mixtures. Finer dense gradations were slightly less affected by the asphalt film thickness increase compared to the coarser gradations.

Extracellular matrix stiffness mediates radiosensitivity in a 3D nasopharyngeal carcinoma model

PurposeRadiotherapy is one of the essential treatment modalities for nasopharyngeal carcinoma (NPC), however, radioresistance still poses challenges. Three-dimensional (3D) tumor culture models mimic the in vivo growth conditions of cells more accurately than 2D models. This study is to compare the tumor biological behaviors of NPC cells in 2D, On-Surface 3D and Embedded 3D systems, and to investigate the correlation between radioresistance and extracellular matrix (ECM) stiffness.MethodsThe morphology and radioresistance of the human NPC cell line CNE-1 were observed in 2D and 3D systems. The CCK-8 assay, wounding healing assays, flow cytometry, soft agar assays, and western blot analysis were used to evaluate differences in biological behaviors such as proliferation, migration, cell cycle distribution, and stem cell activity. Different ECM stiffness systems were established by co-blending collagen and alginate in varying proportions. ECM stiffness was evaluated by compressive elastic moduli measurement and colony formation assay was used to assess radioresistance of NPC cells in systems with different ECM stiffness after irradiation.ResultsCompared to 2D models, the morphology of NPC cells in 3D culture microenvironments has more in common with in vivo tumor cells and 3D cultured NPC cells exhibit stronger radioresistance. Integrin β1 but not the epithelial-to-mesenchymal transition pathway in 3D models boost migration ability. Cell proliferation was enhanced, the proportion of tumor stem cells was increased, and G1/S phase arrest occurred in 3D models. NPC cells cultured in softer ECM systems (with low alginate proportions) exhibit striking resistance to ionizing radiation.ConclusionThe tumor biological behaviors of NPC cells in 3D groups were obviously different from that of 2D. Radioresistance of NPC cells increased with the stiffness of ECM decreasing.

A rosette approach for the determination of the compliance matrix

The computation of the Young's moduli and Poisson's ratio using finite element analysis is comparatively straight forward in the case of systems with non-orthogonal lattice vectors. However, the corresponding calculation of the shear coupling coefficients and the shear modulus is more demanding and less readily attainable. Yet these are needed in order to determine the compliance matrix, which is essential in order to obtain a complete description of the mechanical properties of a structure in any direction. Based on these considerations, this work aims at providing a general methodology for the computation of the complete compliance matrix for systems with non-orthogonal lattice vectors from measurements of the Young's modulus and Poisson's ratio obtained using a suitable rosette of unit cells. The theoretical framework will be outlined and then applied on an accordion-like honeycomb that does not possess a rectangular unit cell and has potential applications in cellular scaffolding, particularly of heart muscle tissue. For the computation, the values of the Young's moduli and Poisson's ratio from three differently-orientated non-rectangular unit cells were obtained using finite element simulations allowing the determination of the complete compliance matrix. The results were validated by comparison with numerical simulations carried out on another unit cell having a different orientation from the other three.

Some features of Kaniadakis holographic dark energy model

In this study, the Kaniadakis holographic dark energy (KHDE) model is investigated within the framework of a flat FLRW universe by using an infrared cut-off as Hubble horizon. For the different values of the Kaniadakis parameter [Formula: see text] and [Formula: see text], we perform an analysis on the deceleration, the equation of state and the energy density parameters. The current phase shift of the Cosmos may be rationalized by the change in sign of the deceleration parameter in the KHDE model, which went from [Formula: see text] to [Formula: see text], signifying a move from a phase of deceleration to one of acceleration. In order to get an understanding of the geometrical behavior shown by the KHDE model, we compute and show the statefinder evolutionary trajectory for the pairs [Formula: see text] and [Formula: see text]. The evolutionary trajectory of [Formula: see text] reveals that the [Formula: see text] crosses the phantom divide line [Formula: see text] at a late period in the evolutionary process. It has also been determined, by examination of the KHDE models stability analysis, that the model has behaved in an unstable manner during the whole course of the history of the universe. In addition to this, we optimized the model parameters by making use of the distance modulus measurement that was taken from the most current Union 2.1 dataset of supernovae.

Measurement of the Elastic Modulus of Cornea, Sclera and Limbus: The Importance of the Corneal-Limbus-Scleral Biomechanical Unit

Energy storage, transmission and dissipation are important considerations of normal mechanical homeostasis. In this paper we present a new technique termed vibrational optical coherence tomography (VOCT) to study the anterior anatomic structures of the pig eye to better understand how energy applied to the cornea is dissipated without delamination occurring. VOCT uses infrared light and an applied sinusoidal audible sound wave to image and measure the resonant frequency and modulus of individual macromolecular components of tissue non-invasively. We have measured the resonant frequencies and calculated the moduli of tissues in the anterior portion of the pig eye using VOCT. While both pig and human eyes have similar resonant frequencies, they do differ in the peak amplitudes near the frequencies of 80, 120, 150 and 250 Hz. It is known that the stroma of pig cornea is much thicker than that of human corneas and these differences may explain the normalized peak height differences. The similarity of the resonant frequency peaks near 80, 120, 150 and 250 Hz of cornea, sclera and limbus suggest that the anatomically described layers in these tissues are connected into a single biomechanical unit that can store external mechanical energy and then transmit it for dissipation. Since the energy stored and dissipated is proportional to the modulus and the ability of the tissue to deform under stress, energy storage in these tissues is related to the stiffness. It is concluded that stored energy is transmitted to the posterior segment of the eye for dissipation through the attachment with the sclera. This mechanism of energy dissipation may protect the cornea from changes in shape, curvature, and refractive power. However, ultimately, energy dissipation through thinning of the sclera may cause globe elongation observed in subjects with myopia and glaucoma.

In-Situ Modulus Determination Using Dispersion Curves Developed From the Deflection-Time History Data

The advanced non-destructive tests (NDT) have become increasingly popular in the structural performance evaluation of transportation infrastructures including pavements. Among them, Falling Weight Deflectometer (FWD) and Spectral Analysis of Surface Waves (SASW) are the two most widely used methods in modulus measurement. Although popularly used, FWD methods base the analysis purely on the deflection characteristics of the pavement and the back-calculated modulus values are usually not unique for different data processing methods. SASW is based on fundamental spectral analysis of the Rayleigh waves but is practically limited in field operation due to its efficiency concern. On the other hand, the impact loading applied by the FWD will generate the Rayleigh wave, and the geophones used in FWD can capture Rayleigh wave fluctuation and measure the particle motion for phase velocity calculations. It is theoretically possible to use the deflection-time history collected by FWD to perform dispersion analysis based on the Rayleigh wave propagation theory, as used in the SASW method. Inspired from that, the main objective of this paper is to propose a new approach of using the deflection-time history collected by FWD to develop the dispersion curves and thus obtain the in-situ modulus of the layered asphalt pavement. This approach is referred as the FWD dispersion curve method. Two in-service semirigid base asphalt pavement segments were used as case studies to explain the new methodology. The results of layered modulus from the FWD dispersion curve method were compared with the traditional FWD and SASW method, as well as the laboratory Indirect Tensile (IDT) testing results using field cores. Findings demonstrated the feasibility of the FWD dispersion curve method in accurately capturing the layered modulus profile of the asphalt pavements.

Editorial: Special Issue on Smart and Green Infrastructures with Optimum Life Cycle Solutions

Editorial: Special Issue on Smart and Green Infrastructures with Optimum Life Cycle Solutions

Scope of Wood Scanning Applications in India - A Review

This article describes the opportunities of major wood scanning technologies in the Indian forestry field. Researchers have developed various non-destructive technologies to better understand the inner properties of wood. In the wood industry, the correct identification of wood species and their physical (in furniture industries) and chemical (in paper and pulp industries) characteristics is critical for end-use applications. The measurements of wood properties (Elastic properties, Thermal properties, Electrical properties, Dielectric properties, and Ionization radiation properties) with the help of wood scanning technologies are used for locating and quantifying wood decay and knots in both standing trees and logs. These measurements have been employed in various perspectives on forestry applications. For instance, measurement of Modulus of Elasticity (MoE) is used to assess thinning effects and tree health assessments, and as a breeding criterion in tree improvement. This article aims to describe major wood scanning technologies that provide tomography of wood and the scope of wood scanning technologies, and their current status in the Indian forestry field. The major wood scanning technologies include Acoustic Tomography, Electrical Impedance Tomography, Magnetic Induction Tomography, Radiography Computed Tomography, and Microwave Tomography.

Constitutive parameter identification of transtibial residual limb soft tissue using ultrasound indentation and shear wave elastography

Finite element analysis (FEA) can be used to evaluate applied interface pressures and internal tissue strains for computational prosthetic socket design. This type of framework requires realistic patient-specific limb geometry and constitutive properties. In recent studies, indentations and inverse FEA with MRI-derived 3D patient geometries were used for constitutive parameter identification. However, long computational times and use of specialized equipment presents challenges for clinical, deployment. In this study, we present a novel approach for constitutive parameter identification using a combination of FEA, ultrasound indentation, and shear wave elastography. Local shear modulus measurement using elastography during an ultrasound indentation experiment has particular significance for biomechanical modeling of the residual limb since there are known regional dependencies of soft tissue properties such as varying levels of scarring and atrophy. Beyond prosthesis design, this work has broader implications to the fields of muscle health and monitoring of disease progression.

Influence of measurement errors of the complex coherence factor on reconstructed image quality of integrated optical interferometric imagers

Interferometric imagers need to measure the phase, modulus, and spatial frequency coordinates of the complex coherence factor to reconstruct images. However, these three measurement parameters are accompanied by certain measurement errors in the actual imaging process, thereby affecting the quality of the reconstructed image. Based on the checkerboard integrated optical imaging system, we simulate the influence of measurement errors of the complex coherence factor on the imaging performance of the integrated optical interferometric imager. The simulation results show that, on the premise that measurement errors follow the normal distribution, the modulus measurement error does not significantly reduce the quality of the reconstructed image, whereas the phase and spatial frequency coordinate measurement errors have a great impact. When the mean value of the phase measurement error is 0, the standard deviation must be <0.18π to ensure the high quality of the reconstructed image. For the measurement error of the spatial frequency coordinates, when the standard deviation of the lenslet position errors is <0.075 times the shortest baseline length, its influence on the quality of the reconstructed image is acceptable. The simulation results are of great help to the engineering, manufacturing, and application of integrated optical interferometric imaging technology.