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BACKGROUND: Post and core crowns are used in the clinic under some conditions, including root fractures, broken posts, and post-core detachment caused by large-scale dental caries and defects. Dentists mainly increase the retentive force by selecting a bonding material with stronger adhesion or by making a retentive groove parallel to the long axis on the surface of the core, but the effect is not obvious. OBJECTIVE: To investigate the effect of different types of retentive grooves and two different adhesives on the retentive force after the post-core crown restoration. METHODS: Sixty cobalt-chromium alloy metal crowns and post-core modules simulating the morphology of mandibular premolars were prepared. The axial cohesion angle of the cores was 8°. These crowns and post-core modules were randomly divided into six groups with 10 crowns/pieces per group. In the smooth group, there was no auxiliary retentive groove on the post-core surface. In the horizontal and vertical groups, there were retentive grooves with equal spacing parallel to(horizontal group) or perpendicular to(vertical group) the long axis of the post and core. In the oblique group, the retentive grooves were placed with an oblique angle of 45° with the long axis of the post-core. In the mesh group, the retentive grooves were at an oblique angle of 45° with the long axis of the post and core and crossed. In the point group, the retentive grooves were dot-shaped. In all six groups, glass ionomer cement and self-curing resin adhesive were used to bond post-and-core with crown. The retentive force in each group was tested by the tensile test, and the displacement change of three-dimensional finite element model during the same time was analyzed by the finite element analysis. RESULTS AND CONCLUSION: (1) Regardless of whether it was bonded with glass ionomer cement or self-curing resin adhesive, the retentive force was highest in the mesh group and lowest in the point group. There was no interaction between adhesives and retentive grooves used to increase retentive force(F=0.26, P=0.91). The effect of different adhesives on retentive force was not significant(F=1.04, P=0.31). The effect of different auxiliary retentive grooves on retentive force was significant(F=14.74, P < 0.05). (2) When the same force was applied at the same time, the displacement of three-dimensional finite element model was smallest in the mesh group. (3) These results suggest that preparation of retentive grooves on the post-core surface can enhance the retentive force. Mesh-shaped retentive grooves provide the greatest retentive force. Different types of adhesives do not provide obviously different effect on the retentive force between the crown and the post and core. [ABSTRACT FROM AUTHOR]

Lithium (Li) concentration-dependent mechanical properties are crucial to the performance and durability of lithium ion batteries. Here, we report an in situ measurement of the evolution of elastic modulus and partial molar volume of commercial graphite electrodes. A bending model is developed to analyze the relationship between large curvature changes and materials properties. The curvature changes of the electrode are captured using a CCD camera during electrochemical cycling. Composite graphite electrodes with different thickness ratios are chosen as the working electrode. The modulus and partial molar volume are extracted which are both associated with the stress evolution of electrodes. The results show that the elastic modulus increases during the second lithiation process, while the partial molar volume shows a stage change corresponding to the phase change of graphite materials. These results are important for the mechanical modeling and provide basic information for the commercial graphite electrodes. Image 1 • Lithium concentration-dependent mechanical properties were measured in situ. • A mechanics model was developed to analyze the curvature deformation of electrodes. • Elastic modulus and partial molar volume of the commercial graphite electrode were reported. [ABSTRACT FROM AUTHOR]

This work aims to develop smart stimuli responsive composites utilizing hydrogenated nitrile rubber (HNBR), fly ash (FA), and slag (SG) with white cement (WC). HNBR has been chosen by capitalizing its unique attributes of high temperature performance and high oil resistance as the matrix and coining the synergistic setting characteristics of FA and SG as industrial wastes with WC. The composites displayed synergism in mechanical and thermal properties. The calcium‐rich phases of FA and SG, entice the postpolymerization modification of the rubber matrix in conjunction with cement serving as reactive fillers. The changes of modulus (~50 MPa), mass (~7%), volume (~8%), and hardness were observed upon repeated wet‐dry cycles. These are attributed to the ionic interactions between the modified polymer matrix and cementitious phases as a result of postpolymerization conversion. These smart composite materials could be used for sealing and microfluidic valves for the downhole applications in oil field industries. [ABSTRACT FROM AUTHOR]

The contribution of the shear strains to the overall deformations of reinforced concrete (RC) elements is typically neglected. However, when RC cracks in shear, its shear modulus is significantly reduced, and the contribution of the shear strains to the overall deformations of the elements is increased. Experimental testing has shown that shear deformations can be significant. Under service conditions, RC can be cracked in shear and hence, a simple method for the calculation of the effective cracked shear modulus is desired. Research has shown that the part of the shear response after cracking and before yielding can be well modeled using a straight line. This paper uses existing experimental data and the equations of the modified compression field theory (MCFT) to examine this part of the response in RC membrane elements and to develop two simple equations that can be used to characterize the straight line. The proposed equations are evaluated by comparing their results with existing experimental data on the shear response of thin RC membrane elements. The comparison includes the post-cracking response and the shear strains at estimated service level loading. A very good agreement is obtained between the experimental and the calculated results. The simplicity of the proposed equations is illustrated using a numerical example. [ABSTRACT FROM AUTHOR]

Plate loading tests were conducted to investigate the effect of a bottom boundary condition on the pressure-settlement behavior of a footing on sand with a limited thickness involving geosynthetics. Seven boundary materials including geosynthetics were used to create different boundary conditions at the bottom of the sand. Interface direct shear tests were conducted first to determine the interface friction angles between these boundary materials and sand, followed by plate loading tests to determine their pressure-settlement curves. Test results show that the sand with a limited thickness by a rigid bottom boundary had a higher bearing capacity than that with a larger thickness. The ultimate bearing capacity of the footing on the sand with a limited thickness generally increased with the increase of the interface friction angle. Geosynthetics provided better lateral restraint than other materials. An equation was developed to describe the relationship of the bearing capacity ratio of the sand with a limited thickness to that with a large thickness versus the soil thickness and the interface interaction coefficient. The effect of the boundary material on the back-calculated modulus of the sand was also evaluated. [ABSTRACT FROM AUTHOR]

Molecular Dynamics (MD) was used to determine the accuracy of different force fields on predicting the elastic modulus of single crystal aluminum through nanoindentation tests. In this work, nanoindentation was performed using three different types of force fields (EAM, MEAM and ReaxFF) and the resulting elastic modulus was compared to the value obtained using elastic constants from standard small strain tensile simulations. When the predicted modulus of each force field was compared to the modulus via elastic constants, the ReaxFF resultant moduli were similar to that of nanoindentation, but for EAM and MEAM the two methods produced significantly different values. Therefore, even if a force field is parameterised for elastic modulus, it does not guarantee the force field will accurately predict the modulus from other procedures. As well, two different methods for calculating modulus from indentation curves were compared: The Hertz approximation and the Oliver and Pharr (O&P) method. For EAM and MEAM force fields, the Hertz method significantly under predicted modulus while the O&P method was in better agreement with the experimental modulus. [ABSTRACT FROM AUTHOR]

Frozen minced meat samples having fat contents of 2%, 10% and 18% were thawed using different methods (refrigeration thawing at ambient temperature of +4 ℃, under running cold water (+4 ℃) thawing, ohmic thawing for 10, 13 and 16 V/cm). Viscoelastic properties were determined by using rheological tests (oscillation and creep/recovery tests). Storage modulus, loss modulus, complex modulus, loss tangent, dynamic viscosity and complex viscosity values of minced meat samples increased as fat content increased. As frequency value increased, the modulus values of meat samples increased but dynamic and complex viscosity values of the samples decreased. The minced meat samples thawed by different methods had recoverable compliance values. The compliance values of meat samples during creep region can be well characterized by Burgers model. Ohmic thawing can be used as an alternative thawing method since it resulted in similar rheological properties of minced meat samples compared to refrigeration thawing at ambient temperature of +4 ℃ and under running cold water (+4℃) thawing. [ABSTRACT FROM AUTHOR]

• Prostate elastic modulus, failure stress, and failure strain were tested using compression and probing protocols for both human and porcine specimens at multiple strain rates. • Elastic modulus was strain rate dependent but saturated at higher rates. • Failure properties were not found to be strain rate dependent. • Similar results were observed from the probing and compression testing methodologies. • Mathematical models were developed for the measured mechanical properties. Characterization of the mechanical properties of organs is important for determining their behavior under load and understanding and predicting their response. In order to appropriately understand behavior, including developing predictive models, the method used to measure the properties should match the application as different testing techniques can yield different results. One of the organs where little mechanical testing has been performed is the prostate. Therefore, the goal of this paper is to expand the knowledge of prostate gland mechanical behavior by using two different compressive testing methods under various loading rates. No differences were found between the elastic modulus measured using the compression and probing protocols for both human and porcine specimens. The elastic modulus ranged from 0.08 MPa at 1%/s to 0.24 MPa at 25%/s for human specimens and from 0.2 MPa at 1%/s to 0.4 MPa at 25%/s for porcine specimens. A strain rate dependency of the elastic modulus was observed for both testing methods. The dependency on strain rate started to saturate at higher rates and a material model was created to quantify this dependence as well as the stress-strain behavior. No strain rate dependency was observed for failure stress or failure strain. Overall, similar values of elastic modulus were found for both probing and compression protocols and the relationship developed between elastic modulus and strain rate could be implemented in models of the prostate gland to aid in understanding the response to dynamic loads. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the possible influence of poplar cultivar and soil on the mechanical properties of plywood produced from 10 cultivars having grown in different soils. For each cultivar, two trees were harvested per station; crosscut into bolts then peeled 1.4 mm thick for one tree and 3 mm thick for the other one: in total, 80 trees were sampled. The veneers were used to make 160 boards using 2 adhesives: polyvinyl acetate (PVAc) and melamine-urea-formaldehyde (MUF). These boards were then cut into standardized samples for non-destructive and destructive mechanical tests. The properties of plywood were characterized by measuring their density, modulus of elasticity and modulus of rupture. The results showed that poplar plywood properties could be influenced by adhesive and veneer thickness. The cultivar and soil effects were never relevant. A tight correlation was found between destructive and non-destructive modulus of elasticity tests. [ABSTRACT FROM AUTHOR]

• 18 compositionally-complex (medium- and high-entropy) pyrochlore oxides fabricated. • Mixing of cations at A- and/or B-sites leads to reduced thermal conductivity. • Thermal conductivity correlates well with a modified size disorder parameter. • A new descriptor proposed for designing low- k medium- and high-entropy ceramics. • Medium-entropy ceramics can outperform their high-entropy counterparts. High-entropy ceramics generally exhibit reduced thermal conductivity, but little is known about what controls this suppression and which descriptor can predict it. Herein, 22 single-phase pyrochlores were examined. Up to 35% reductions in thermal conductivity were achieved in medium- and high-entropy compositions with retained moduli, thereby attaining insulative yet stiff properties for thermal barrier coating applications. Notably, the measured thermal conductivity correlates well with a modified size disorder parameter δ S i z e * , thereby suggesting the importance of severe lattice distortion. Thus, this δ S i z e * is suggested as a useful descriptor for designing thermally-insulative compositionally-complex ceramics, where medium-entropy ceramics can outperform their high-entropy counterparts. Image, graphical abstract [ABSTRACT FROM AUTHOR]

A general model was developed to predict the temperature-dependent modulus and yield strength of different thermoplastic polymers. This model, which depends on only two parameters with clear and specific physical meanings, can describe the temperature-dependent modulus and yield strength of thermoplastic polymers over the full glass transition region. The temperature-dependent modulus and yield strength of three thermoplastic polymers were measured by uniaxial tension tests over a temperature range of 243–383 K. The predictions showed excellent agreement with the experimental data. Sensitivity analysis of model input parameters showed negligible effect on the present general model. The universality of the present general model was further validated, showing excellent agreement with published experimental data on other thermoplastic polymers and their composites. [ABSTRACT FROM AUTHOR]

As opposed to traditional laboratory testing, Molecular Dynamics (MD) offers an atomistic scale method to estimate the mechanical properties of metals. However, there is limited literature that shows the effect of interatomic potentials when determining mechanical properties. Hence, the present research was conducted to investigate the accuracy of various interatomic potentials in estimating mechanical properties of aluminium. Several types of potentials, including Embedded Atom Method (EAM), Modified EAM (MEAM) and Reactive Force Field (ReaxFF) were compared with available experimental data for pure aluminium to determine the most accurate interatomic potential. A uniaxial tensile test was performed at room temperature using MD simulations for nanoscale aluminium. Results demonstrated that those potentials parameterised with elastic constants at physically realisable temperatures were consistently more accurate. Overall, the Mishin et al. EAM potential was the most accurate when compared to single-crystal experimental values. Regardless of the potential type, the error was significantly higher for those potentials that did not consider elastic constants during development. In brief, the application of the interatomic potentials to estimate mechanical properties of a nanoscale aluminium was investigated. [ABSTRACT FROM AUTHOR]

Rheology is a powerful and versatile analytical tool for providing information about changes in the composition, structure, and interactions of food emulsions. Moreover, an understanding of emulsion rheology is essential for designing efficient food processing operations and emulsion‐based foods with the desired physicochemical, sensory, and nutritional attributes, such as appearance, texture, flavor, shelf life, and bioavailability. This article provides a brief overview of the current understanding of food emulsions, with a focus on how their viscosity is related to the properties of the emulsion droplets present. [ABSTRACT FROM AUTHOR]

Dentin possesses a hierarchical porous structure with varying cross-scale morphology and characteristic lengths ranging from nanometers to micrometers. Nanoporous (NP) Copper is fabricated with nano-sized and micron-sized features that mimic dentin's morphology. NP Copper Young's modulus, hardness, and plastic Poisson's ratio are shown to be in the range characteristic of dentin. This correspondence in properties may allow use of NP metals to advance tooth restoration techniques by using them as model systems to study infiltration of dentin with resins. Moreover, the multi-scale porosity may inspire design of 3D catalysts with efficient reactant mass transport through the catalyst volume. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Tantalum thin films may be deposited in two phases. The stable bulk alpha phase is well known, but the metastable tetragonal beta phase is relatively poorly understood. We reported previously on a series of 100% β -Ta films deposited under varying sputter pressures in a low-oxygen environment, and discussed texture, stresses, and phase selection. Here, we discuss microstructure, morphology, and properties of these same β -Ta films. Grain size increases with sputter pressure, which can be explained by the energies of incident species at the growing film. Mechanical properties were measured by nanoindentation. Hardness decreases with grain size in accordance with the Hall-Petch relation while comparison of indentation modulus with biaxial modulus measurements indicates that the β phase is elastically anisotropic, and much stiffer in the [001] direction than in others. Finally, a canonical resistivity value for virtually oxygen-free, 100% β -Ta films of 169 ± 5 µΩcm is reported for the first time. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The influence of co-substitution of Co and W on structural and electrical properties of BaTiO 3 (i.e., Ba(Co 1/3 Ti 1/3 W 1/3)O 3) was investigated. This perovskite ceramic was synthesized using a conventional ceramic technology (i.e., high-temperature solid state reaction route, calcination temperature = 1100 °C and sintering temperature = 1200 °C). The compound crystallizes in the orthorhombic phase. The Nyquist plots exhibit the activation of grain boundary effect at 300 °C and the Non-Debye behavior in the sample. The relaxation distribution parameter for the sample at different temperatures is calculated from the depression angle of the semicircular arcs in the Nyquist plot. The activation energy of 0.69 eV estimated for the charge carriers in the grain is almost in good agreement with that of 0.66 eV calculated from the relaxation process of grains. The sample possesses a dielectric constant of 1140 and loss tangent of 0.27 at room temperature which can be exploited for some applications including memory devices, etc. The existence of room temperature hysteresis loop confirms the ferroelectric nature of the sample. On the basis of variation of the exponent in the Jonscher's power law with temperature, correlated barrier hopping is favored as the dominant conduction mechanism in the sample. [ABSTRACT FROM AUTHOR]

Ba(Fe 1/3 Ti 1/3 W 1/3)O 3 , was successfully prepared by the cost effective mixed oxide reaction method at 1000 °C. Analysis of X-ray diffraction (XRD) data indicates the crystallization of the compound in the orthorhombic crystal system. A dielectric anomaly observed at around 59 °C shifts to the higher temperature side with increase in frequency can be explained by Maxwell-Wagner polarization mechanism, whereas an another anomaly observed at 126 °C can be considered as the ferroelectric to paraelectric transition. The dielectric property was analyzed by modified Cole-Cole relation, and the impedance using Nyquist plot. The activation energy calculated from grain resistance and the relaxation parameters amounts to be 0.54 eV. Analysis of the conductivity curves using the Jonscher's power law suggests OLPT model and CBH model as the dominant conduction mechanism in the ferroelectric and paraelectric phase in the sample. The ferroelectricity of the sample was confirmed by the room temperature P ~ E loop. [ABSTRACT FROM AUTHOR]

Converter steel slag, currently underutilized crystalline metallurgical residue, was investigated for use as a precursor for alkali activation. Water glass solution with various moduli (0.5, 1.0, 1.5 and 2.0) was used at the same Na2O dosage of 4% in order to investigate effect of modulus on hydration. Pure cement paste with the same ratio of water to binder was selected as the control sample. Results show that modulus has a significant impact on the hydration and mechanical strength development of alkali-activated steel slag. Similar to pure cement paste, alkali-activated steel slag paste has C–S–H gel and Ca(OH)2 as its main hydration products. However, alkali-activated steel slag pastes have lower hydration heat and fewer amounts of hydration products. Additional silicate has a retarding effect on the hydration of steel slag. Hydration heat, Ca(OH)2 contents and non-evaporable water contents reduce with increasing modulus. In addition, high silicate modulus fines the pore structure and improves compressive strength of the hardened paste. [ABSTRACT FROM AUTHOR]

High temperature may cripple the properties of enamel coatings, even lead to the microcracking nucleation and spalling from substrates. Therefore, a comprehensive understanding of high temperature properties of enamel is vital for assessing its service life and reliability. In this paper, we investigate the high temperature mechanical properties of enamel coating by nanoindentation, such as the hardness, elastic modulus and creep. The results show that the hardness of enamel coatings decreases with the increase of temperature. However, the elastic modulus of enamel coatings exhibits anomalous increase with temperature. In addition, by analyzing the creep depth, the stress exponent and activation energy of creep can be obtained. The activity energies below and above the glass transition temperature are found to be different. • The mechanical properties of enamel coating are obtained by high temperature nanoindentation. • The elastic modulus of enamel coating exhibits an anomalous temperature dependence. • The stress exponent and activation energy of high temperature creep are analyzed [ABSTRACT FROM AUTHOR]

This study focused on rheological and mechanical properties of poly(vinylidene fluoride) nanocomposites incorporated with functionalized graphene nanoplatelets and hydroxylated titanium dioxide. Mechanical properties of the ternary composites were improved with a slight reduction in damping coefficient compared to the pure polymer and graphene binary composites. The storage modulus of the ternary composites significantly increased from about 67.5 Pa for the pure polymer to 3.24 × 105 Pa and 3.49 × 105 Pa at 0.1 rad/s for 6.67 wt% graphene composites containing 10 wt% and 20 wt% titania respectively. All ternary composites showed higher tensile strength and Young modulus compared to the pure polymer. Strong bonding between the polymer and co-fillers with a reduction in interfacial slipping in the ternary composites resulted in their lower damping factor and higher strength compared to their counterparts. The composite samples were prepared by solution and melt mixing methods. The scanning electron microscope was used to examine the samples' morphology and dispersion of the co-fillers in the matrix. Such composites can find applications in automobile and aerospace industries where materials with good strength and noise or vibration absorption capability are required. [ABSTRACT FROM AUTHOR]

In this paper, we present some new methods for the estimates below the modulus of some integrals of the unit circle in the complex plane. All these methods are the best connection between the real and complex case. The results of this paper could be applied in many other areas of mathematics and natural sciences. [ABSTRACT FROM AUTHOR]

Background: Increased tissue stiffness (also termed modulus) has been shown to be a characteristic of potential tumor metastasis. Measured values of the stiffness of tumors and cancer cells are reported in the literature to increase compared to neighboring normal tissues. Yet the relationship between the mechanical properties of cells and the extracellular matrix has yet to be correlated with the histopathology of cancerous lesions. Materials and Methods: We have developed a technique to do virtual biopsies of skin lesions by combining images made using optical coherence tomography with stiffness measurements made simultaneously using vibrational analysis. The technique is termed vibrational optical coherence tomography (VOCT). Results: In this paper, we report that precancerous and cancerous lesions are characterized by changes in both the morphology and stiffness of the cellular components of the skin. The ratio of the peak heights that correspond to the epidermal (40‐60Hz) and dermal (140‐160 Hz) resonant frequencies appear to be different for benign and cancerous or precancerous lesions compared with normal skin and scar. Conclusions: Cell‐to‐cell and epidermal‐to‐dermal interactions may be very important in evaluating the potential of skin lesions to become malignant. These interactions can be evaluated using VOCT, a new technique for performing "virtual biopsies" of skin lesions. [ABSTRACT FROM AUTHOR]

I discuss three related problems about getting the last day of the month in a new variable. Commentary ranges from the specifics of date and other functions to some generalities on developing code. Modular arithmetic belongs in every Stata user's coding toolbox. [ABSTRACT FROM AUTHOR]

In this work, amorphous thin films in Mg-Si-O-N system typically containing >15 at.% Mg and 35 at.% N were prepared in order to investigate especially the dependence of optical and mechanical properties on Mg composition. Reactive RF magnetron co-sputtering from magnesium and silicon targets were used for the deposition of Mg-Si-O-N thin films. Films were deposited on float glass, silica wafers and sapphire substrates in an Ar, N 2 and O 2 gas mixture. X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, spectroscopic ellipsometry, and nanoindentation were employed to characterize the composition, surface morphology, and properties of the films. The films consist of N and Mg contents up to 40 at.% and 28 at.%, respectively and have good adhesion to substrates and are chemically inert. The thickness and roughness of the films increased with increasing content of Mg. Both hardness (16–21 GPa) and reduced elastic modulus (120–176 GPa) are strongly correlated with the amount of Mg content. The refractive index up to 2.01 and extinction coefficient up to 0.18 were found to increase with Mg content. The optical band gap (3.1–4.3) decreases with increasing the Mg content. Thin film deposited at substrate temperature of 100 °C shows a lower value of hardness (10 GPa), refractive index (1.75), and higher values of reduced elastic modulus (124 GPa) as compared to the thin film deposited at 310 °C and 510 °C respectively, under identical synthesis parameters. • Mg-Si-O-N thin films are X-ray amorphous. • The films contain a high amount of N up to 40 at.%, and Mg up to 28 at.%. • Mg-Si-O-N films are optically transparent in the visible range and chemically inert. • The Mg-Si-O-N films have enhanced mechanical and optical properties as compared to SiON films. [ABSTRACT FROM AUTHOR]

• Rutting Lab Test Comparisons – Practicality, Simplicity, and Repeatability. • Correlation of lab results with Field Rutting Performance. • Rutting Prediction Potential and Field Correlations. • HMA Screening Criteria using different Rutting Lab Test. Rutting or permanent deformation (PD) is one of the most critical distresses occurring in hot-mix asphalt (HMA) pavements. However, despite all of the recent efforts aimed at producing new test methods and better road materials, HMA rutting is still prevalent, particularly in hot regions and/or on highways with heavy truck-traffic loading. Laboratory testing to screen HMA mixes against rutting during the HMA mix-design stage thus constitute a vital step towards optimizing field performance. In this Texas case study, five laboratory test methods were comparatively evaluated for quantifying and screening four HMA mixes' rutting resistance potential relative to their field performance on in-service highway test sections under conventional traffic loading and climatic conditions. The five test methods included the dynamic modulus (DM), flow number (FN), repeated load permanent deformation (RLPD), simple punching shear test (SPST), and Hamburg wheel tracking tester (HWTT), respectively. The four HMA mixes evaluated included commonly used Texas fine-, coarse-, and porous-graded mixes. The data for the study, both laboratory and field performance including climate (temperatures) and traffic loading, were all extracted from Texas flexible pavements and overlays database, namely the Texas Data Storage System denoted as the DSS. Overall, all the laboratory test predictions correlated well with the actual measured field performance data, with the HWTT and SPST tests exhibiting superiority over the other test methods. As theoretically expected, the coarse-graded HMA mix out-performed the other mixes, with the fine- and porous-graded mixes being at the lower end of the spectrum. [ABSTRACT FROM AUTHOR]

• Clarify the effects of mixture gradation and polishing on nanoindentation results. • Characterize the age-hardening behavior of asphalt mixtures using nanoindentation. • Describe the vertical aging gradient in asphalt mixtures by nanoindentation. Understanding the aging behavior of asphalt mixtures is of great significance to the design, construction and maintenance of asphalt pavements. Numerous studies have been conducted on the aging phenomenon and its effects on mixture properties. However, conventional testing methods focus mainly on the global view or average value of the performance of aged mixtures, while the inner aging gradients are seldom addressed. The aging gradient, referring to the differences of aging effects in asphalt mixtures due to different accessibilities to aging conditions, represents the true aging behavior of asphalt mixtures. Hence, a micromechanical testing technique, nanoindentation, was used in this paper to investigate this issue. The effects of mixture gradation and polishing in sample preparation process on nanoindentation results were explored first. Then the vertical changes of modulus of asphalt mastic in asphalt mixture samples were characterized by nanoindentation to describe the aging gradient in different aged mixture samples. Dynamic modulus test was also performed for data supplement and comparison. Results show that gap-graded mixtures are suitable for nanoindentation test and a careful and standard polishing treatment will not affect the reliability of nanoindentation data. Nanoindentation can well characterize the age-hardening behavior of asphalt mastic and the aging gradient in long-term aged asphalt mixtures is approximately in a logarithmic curve form. Nanoindentation modulus results indicate that 8d of laboratory long-term aging in this paper can only affect the upper sections of dense asphalt mixtures. This paper suggests that nanoindentation can achieve a quantitative, mechanical and precise characterization of aging gradient in asphalt mixtures and is therefore promising in further research of asphalt materials. [ABSTRACT FROM AUTHOR]

This paper is devoted to the study of weakly quasisymmetric homeomorphisms. We investigate under what conditions a weakly H-quasisymmetric map is actually quasisymmetric. As a consequence, we deduce conditions under which the inverse and composition of weakly quasisymmetric homeomorphisms are also weakly quasisymmetric. [ABSTRACT FROM AUTHOR]

Graphical abstract Dual positive temperature coefficient of resistance (PTCR) to negative temperature coefficient of resistance (NTCR) transitions of this system. Highlights • Positive temperature coefficient of resistance (PTCR). • Interface magnetoelectric (ME) effect in this system. • Small polaron hopping and over lapping large polaron tunneling at interface. Abstract Polycrystalline nano grain size Na 0.5 Bi 0.5 TiO 3 (NBT) system is synthesized by using modified sol–gel method. X-ray diffraction (XRD), Transmission electron microscopy (TEM) studies and Field emission scanning electron microscopy (FESEM) are employed for structural and morphological confirmation. Electrochemical transport properties of this nano system have been investigated systematically in the range of temperature (30 °C−450 °C) and frequency (100 Hz−1 MHz) with the help of complex impedance spectroscopic technique. From impedance and modulus results, two (one at low and another at high temperature regime) positive temperature coefficient of resistance (PTCR) to negative temperature coefficient of resistance (NTCR) transitions are observed which is useful for electrochemical temperature sensor application. From electric transport analysis it found that due to small polaron hopping of charge carriers at NBT-NBT interfaces system shown PTCR nature. However, the system has shown both −ve magnetoresistance [MR (%)] and magnetocapacitance [MC (%)] at RT due to overlapping of large polaron tunnelling (OLPT) at NBT-NBT interfaces (which is explored with the help of magnetic transport analysis). [ABSTRACT FROM AUTHOR]

The Korányi ellipsoidal ring ε = εB,A, 0 < B < A, is defined as the image of the Korányi spherical ring centred at the origin and of radii B and A via a linear contact quasiconformal map L in the Heisenberg group. If K ≥ 1 is the maximal distortion of L, then we prove that the modulus of ε is equal to mod(ε) = (3/8(K²+1/K²)+1/4)π²/(log(A/B))³. [ABSTRACT FROM AUTHOR]

Nano-indentation is an interesting tool for analyzing nano-scale mechanical properties. The analysis of nano-mechanical properties as a function of experimental conditions is very critical for designing engineering components. In this study, nano-indentation experiments were performed by considering different values of amplitude (1, 5, 10 nm), frequency (11.2, 22.5, 45 Hz), strain rate (0.02, 0.05, 0.1, 0.2, 1 s−1), peak load (10, 30, 100 mN) and hold time (1, 3, 5, 10, 20, 50, 100 sec) to analyze their effect on the mechanical properties of LDPE. The results showed that the effect of amplitude and frequency on the nano-mechanical properties of LDPE were negligible. Load-displacement curves displayed a shift towards higher indentation depths along with a decrease in peak load from 20.6 to 14.8 mN by having a decrease in strain rate from 1 to 0.02 s−1. Elastic modulus and hardness values exhibited a decrease with an increase in hold time. Logarithmic creep model was used to fit the experimental data of creep as a function of holding time which showed good agreement (r2 ≥ 0.97) with the experimental values. Recommended holding times are also suggested to eliminate the creep and nose problem in order to achieve high accuracy in measurements. [ABSTRACT FROM AUTHOR]

The incidence of diabetes mellitus and the associated complications are growing worldwide, affecting the patients' quality of life and exerting a considerable burden on health systems. Yet, the increase in fracture risk in type 1 diabetes (T1D) patients is not fully captured by bone mineral density (BMD), leading to the hypothesis that alterations in bone quality are responsible for the increased risk. Material/compositional properties are important aspects of bone quality, yet information on human bone material/compositional properties in T1D is rather sparse. The purpose of the present study is to measure both the intrinsic material behaviour by nanoindentation, and material compositional properties by Raman spectroscopy as a function of tissue age and microanatomical location (cement lines) in bone tissue from iliac crest biopsies from postmenopausal women diagnosed with long-term T1D (N = 8), and appropriate sex-, age-, BMD- and clinically-matched controls (postmenopausal women; N = 5). The results suggest elevation of advanced glycation endproducts (AGE) content in the T1D and show significant differences in mineral maturity / crystallinity (MMC) and glycosaminoglycan (GAG) content between the T1D and control groups. Furthermore, both hardness and modulus by nanoindentation are greater in T1D. These data suggest a significant deterioration of material strength properties (toughness) and compositional properties in T1D compared with controls. • Although both Type-1 and -2 diabetes are on the rise, the increase in fragility fractures is not understood. • These data present bone tissue material properties in post-menopausal women with and without T1D. • Increase AGEs along with hardness and modulus explains the greater fragility risks in Type-1 diabetics. [ABSTRACT FROM AUTHOR]

[Display omitted] • The interfaces of the CrN/Cr/316L co-ordinately bended, those of the CrN/Cr/TC4 did not. • The maximum tensile stress located at the Cr/CrN interfaces and the cracks initiated from there. • The metallic bonds took the responsibility to the interfacial adhesion between Cr/316L or TC4. • The large moduli differences between a coating/substrate revealed to be the failure mechanism. CrN multilayer coatings were deposited on 316L stainless steel, which has a high modulus, and TC4 titanium alloy, which exhibits the opposite properties, to reveal adhesion mechanisms and deformation behavior of the coating/substrate systems. Because of the different microstructures, the coatings' morphologies varied from single polygon on the 316L to polygon and rectangle-mixed shapes on the TC4. On 316L, the cracks initiated from the Cr/CrN interfaces and propagated into the CrN layer, which stopped within it. On TC4, the cracks propagated through the CrN layer. The coherent nanocrystal interfaces in CrN/Cr/316L exhibited orderly bending, revealing the presence of strong interfacial bonds. The undeformed interfaces in CrN/Cr/TC4 indicated incompatible deformation and weak bonds. This was consistent with the fact that on TC4, the Cr/CrN interface tensile stress was high, at 123.1 GPa, while it was lower on 316L, at 99.3 GPa. The W p /W e ratio of CrN/TC4, namely 1.94, was lower than that of CrN/316L, namely 2.61. This indicated that CrN/316L had a high energy-absorption ability because of compatible plastic deformation. The failure mechanism observed between the coating/TC4 was attributed to the differences in their moduli, which led to incompatible deformation, high interfacial tensile stress, and low absorption capability for external work. [ABSTRACT FROM AUTHOR]

Climate change is impacting on pavement infrastructure in China. To eliminate the issues of asphalt freeway pavement caused by climate change, this study evaluated the temperature change in China from 2020 to 2059. The related pavement issues include rutting, fatigue life, and thermal crack caused by climate change are assessed based on the prediction models incorporated with the predicted future climate. The potential future distresses were analyzed, quantified, and cataloged, then the effectiveness of optional adaptation measures included adjustment of structure thickness, dynamic modulus, and creep stiffness were analyzed. Finally, a method to select and quantify the adaptation measures was developed based on the effectiveness analysis of adaptation measures. The major findings of this study are listed below: (1) Temperature rise is the general trend, rutting and fatigue issue is typical issue caused by climate change. (2) Extreme low temperature issue would occur more severe for some area in future, up to 35% of pavement would have more severe thermal crack issue caused by climate change in 2050s. (3) Six quantified adaptation measures were suggested to solve these two types of issues caused by climate change. [Display omitted] • Global temperature rise would generally cause rutting and fatigue issue of pavements. • Extreme low temperature climate would cause more severe thermal crack issue of 35% pavements. • Six quantified adaptation measures were suggested to solve pavement issues caused by climate change. [ABSTRACT FROM AUTHOR]

The mechanical properties of a stem cell culture substrate significantly impact cell adhesion, survival, migration, proliferation, and differentiation in vitro. A major challenge in engineering artificial stem cell substrate is to properly identify the relevant physical features of native stem cell niches, which are likely different for each stem cell type. The behavior of tendon stem cells has potentially significant implications for tendon repair. Here, microfiber scaffolds with various modulus of elasticity are fabricated by near-field electrospinning, and their regulating effects on the in vitro behavior of tendon stem cells (TSCs) are discussed in this study. The number of pseudopodia shows a biphasic relationship with the modulus of scaffold. The proliferation, polarization ratio and alignment degree along the fibers of the TSCs increase with the increase of fiber modulus. TSCs cultured on the scaffold with moderate modulus (1429 MPa) show the upregulation of tendon-specific genes (Col-I, Tnmd, SCX and TNCF). These microfiber scaffolds provide great opportunities to modulate TSCs behavior at the micrometer scales. In conclusion, this study provides an instructive mechanical microenvironment for TSCs behaviors and may lead to the development of desirable engineered artificial stem cell substrate for tendon healing. [Display omitted] • The cross PA56 fiber scaffolds with various modulus were fabricated by NEFS. • The proliferation, number and cell polarization ratio of TSCs increased with the modulus. • The number of pseudopodia of TSCs showed a biphasic response to the modulus. • The arrangement of actin cytoskelenton tended to align toward the fiber with the increase of fiber modulus. • Microfiber scaffolds with moderate modulus (1429 MPa) demonstrated the potential to upregulate the tendon-specific genes. [ABSTRACT FROM AUTHOR]

A gel forming method with sections with different elastic modulus is developed. Gels with hardness distribution are formed from one base gel material by adjusting the crosslinking density of the polymer network using a 3D gel printer. It is confirmed that hardness is arranged as designed by using mixing rules of composite materials. Furthermore, as a prototype of a practical gel application, a gel finger model having a soft-fleshy part and a hard-bony part is printed. 3D printing of an organ model that reproduces a realistic feel that takes not only the shape of the organ but also the distribution of hardness into consideration may become possible. [ABSTRACT FROM AUTHOR]

In order to achieve a high-quality composite, a proper manufacturing technique should be used. Glass Fiber Reinforced Plastic (GFRP) structures are commonly manufactured using hand layup, vacuum bag and vacuum infusion process (VIP) which are cost effective techniques. This paper compares the tensile strength, modulus, inter-laminar bonding and surface macroscopy of GFRP composites made by hand layup, vacuum bag and VIP process. For this reason, at first GFRP sample were manufactured using these three methods and then tested for tensile properties. In the next step, these samples were modeled numerically and compared. The results show that the strength of the sample made by VIP process is 20 % higher than the hand layup and 11 % higher than vacuum bag sample. Also, the modulus of the sample achieved using VIP is 21 % higher that hand layup and 15% higher than vacuum bag technique. By comparing the failure mechanism of the samples, it was observed that the inter-laminar bonding is highest in VIP and then vacuum bag and lastly hand layup due to a smaller number of voids. Lastly the numerical results showed to have a good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

We call a finite set D ⊂ Zs a (self-affine) tile digit set with respect to an expanding integral matrix A if the self-affine set T(A,D) is a tile in Rs. It has been a widely open problem to characterize the tile digit sets for a given A. While there are substantial investigations on R, there is no result on Rs other than the case where | detA| = p with p a prime. In this paper, we make an initiation to study a basic case A = pI2 in R². We characterize the tile digit sets by making use of the zeros of the mask polynomial of D associated with a tile criterion of Kenyon [Self-replicating tilings, Contemp. Math., vol. 135, Amer. Math. Soc., Providence, RI, 1992, pp. 239–263], together with a recent result of Iosevich et al. on factorization of sets in Zp×Zp [Anal. PDE 10 (2017), no. 4, 757–764]. [ABSTRACT FROM AUTHOR]

The polycrystalline 0.7Bi(Fe 0.98 Ga 0.02)O 3 -0.30BaTiO 3 (BFG-BTO) ceramic was processed by high temperature reaction route. The room temperature X-ray spectra suggest a tetragonal symmetry. The structural refinement was also carried out. The high densification of sample formation is depicted from a scanning of the natural surface of the sample. The electrical properties were measured using a complex impedance method over a wide range of frequencies and temperatures. The overlapping large-polaron tunnelling model type of conduction mechanism is obtained from the frequency dependent ac conductivity plots. The relaxation mechanism is studied with the help of various spectroscopic tools (modulus and dielectric). The Nyquist plot indicates the non-Debye characteristics and the combined contribution of both grain and grain boundary towards the resistive property of the sample. Image 1062858 • The BFG-BTO is synthesized by cheap cost ceramic processing. • Dielectric properties with respect to temperature is investigated. • The complex impedance plots shows grain and grain boundary effects in the BFG-BTO. • A well defined relaxation mechanism was identified by modulus analysis. [ABSTRACT FROM AUTHOR]

The Sm and Nb substituted 90% of BaTiO 3 -10% of Li 0.5 Fe 2.5 O 4 are synthesized using solid state preparation method. The X-ray diffraction, the frequency dependent of impedance, complex impedance at different temperatures, Nyquist plots at different temperatures, the variation of modulus and conductivity with high frequency region between 1 MHz and 3.2 GHz at 30 °C of composites were studied. The impedance of composites decreases steeply beyond 100 kHz and impedance value of 90BLF increases with increase in the concentration of Sm and Nb in BLF. The real and complex impedance changes with frequency. As temperature increases the real part of impedance of composites decreases and beyond certain frequencies, the impedance decreases sharply and merge at 10 MHz. As temperature increases the complex impedance Z″ max peaks shifted towards higher frequency i.e peak frequency f max increases with increase in temperature. The impedance curve of composites identified by exhibits single semi circle represents type of relaxation described by Debye model. The relaxation time (τ) of composites decreases with the increase in temperature. Beyond frequency 3 GHz, the modulus of composites exhibits complex behavior and the complex modulus (M″) peaks exhibits jumping behavior could be explained by Debye-type relaxation. The conductivity peak of 90BLF composites are shifted towards higher frequency with the increase in concentration of Sm and Nb in it due to the substitution of Nb and Sm in 90BLF. • The complex impedance (Z″) peaks shifted towards higher frequency with increasing temperature. • The radius of the semicircles decreases with increasing temperature due to temperature dependence of relaxation. • The relaxation time (τ) of composites decreases with increase in temperature. • The activation energy of composites increases with increase Sm and Nb. • The complex modulus (M″) peaks of all the composites exhibits jumping behavior. [ABSTRACT FROM AUTHOR]

Passive mechanical properties differ between muscle groups within a species. Altered functional demands can also shift the passive force-length relationship. The extent that passive mechanical properties differ within a muscle group (e.g. spine extensors) or between homologous muscles of different species is unknown. It was hypothesized that multifidus, believed to specialize in spine stabilization, would generate greater passive tensile stresses under isometric conditions than erector spinae, which have more generalized functions of moving and stabilizing the spine; observing greater multifidus moduli in different species would strengthen this hypothesis. Permeabilized fibre bundles (n = 337) from the multifidus and erector spinae of mice, rats, and rabbits were mechanically tested. A novel logistic function was fit to the experimental data to fully characterize passive stress and modulus. Species had the greatest effect on passive muscle parameters with mice having the largest moduli at all lengths. Rats generated less passive stress than rabbits due to a shift of the passive force-length relationship towards longer muscle lengths. Rat multifidus generated slightly greater stresses than erector spinae, but no differences were observed between mouse muscles. The secondary objective was to determine the parameters required to simulate the passive force-length relationship. Experimental data were compared to the passive muscle model in OpenSim. The default OpenSim model, optimized for hindlimb muscles, did not fit any of the spine muscles tested; however, the model could accurately simulate experimental data after adjusting the input parameters. The optimal parameters for modelling the passive force-length relationships of spine muscles in OpenSim are presented. [ABSTRACT FROM AUTHOR]

Abstract Recently laterally pre-stretched pure shear deformation is considered as the most compatible and easier way of achieving higher actuation performances of dielectric elastomer actuator due to improvement of its dielectric strength and pull-in stability. However, an accurate experimental investigation and modelling criteria of dielectric elastomer under various lateral pre-stretches up to failure have still not been reported in details. In the present work, different pre-stretch levels are incorporated in commonly used material, VHB 4910 under pure shear loading at sufficiently slow strain rate to obtain stress-stretch curves up to failure. It has been also established that Ogden model parameters obtained by fitting pure shear test data are more accurate for pre-stretched pure shear modelling than those obtained from commonly used uniaxial pull test. Highlights • Laterally pre-stretched pure shear experiments are performed till failure. • Failure stretch keeps on decreasing with increasing lateral pre-stretch. • Reduction of stiffness in the transverse direction is obtained due to lateral pre-stretching. • Ogden model fitting parameters are obtained from pure shear experimental data. • Model using parameters from pure shear data provides better accuracy compared to that obtained from uniaxial data. [ABSTRACT FROM AUTHOR]

In this paper, various original properties of the Bessel and spherical Bessel functions are presented, based on which we prove a novel uniqueness result of an inverse acoustic obstacle scattering problem, that is, a sound-hard ball with a known center can be uniquely determined by the modulus of a single far-field datum corresponding to a single incident plane wave. [ABSTRACT FROM AUTHOR]

Abstract This paper presents results of studies characterizing the mechanical properties of irradiated U 10Mo fuel in support of low-enriched fuel conversion of several United States high-performance research reactors (USHPRR), specifically the monolithic base fuel qualification. Specimens were tested from ten test fuel plates irradiated at the Advanced Test Reactor (ATR) from the RERTR-12 and AFIP-6 Mk. II irradiation campaigns. Tests were conducted at Idaho National Laboratory (INL) in the Hot Fuel Examination Facility (HFEF) inert atmosphere Main Cell. The monolithic fuel plates consist of a U 10Mo fuel foil meat covered with a Zr diffusion barrier layer fabricated by co-rolling, and clad in 6061 Al using a hot isostatic press (HIP) bonding process. Initial unirradiated specimens exhibited nominal (fresh) fuel meat thickness ranging from 0.25 mm to 0.64 mm, and irradiated (as tested) fuel plate average burnup ranged from approximately 0.36 × 1021 to 6.2 × 1021 fissions/cm3. After sectioning individual specimens from the fuel plates, the 6061 Al cladding was removed by dissolution in concentrated NaOH. Pre-dissolution measurement of width and post-dissolution measurement of thickness were conducted on test specimens to facilitate accurate analysis of bend test results. The final thickness values varied from 0.3 to 0.8 mm. Four-point bend testing was conducted on the HFEF Remote Load Frame (RLF) using custom-designed test fixtures and calibrated force and displacement sensors. All specimens exhibited dominantly elastic behavior and failed in a brittle manner. Analysis of test results showed decreasing elastic modulus and bending failure strength with increasing fission density. The trend of modulus decrease intersected with unirradiated modulus at zero fission density. The trend of decreasing bending strength with increased fission density is apparent, but has significantly higher uncertainty levels than the modulus results over the fission density range evaluated. A linear trend fit of the calculated bend strengths versus fission density does not coincide with unirradiated tensile strength, which is significantly higher. Porosities measured on the test specimen material are used with several model equations to predict irradiated modulus values. Over the range of available porosity information, comparison to the experimental modulus values are favorable. Other factors and their potential influence on modulus and strength calculations are discussed. [ABSTRACT FROM AUTHOR]

Abstract The multiferroic ceramic (BiBa 0.5 Sr 0.5) 0.5 (Fe 0.5 Ti 0.5) O 3 (BFO-BST) is prepared in an economic way by conventional solid state reaction route and its different behaviours are studied and reported. The X-Ray diffraction (XRD) and Scanning Electron Microscope (SEM) investigations have confirmed single phase forming by the compound. Full proof reitveld analysis has been used for structural refinement. XRD pattern of the sample it is inferred that the observed peaks and calculated peaks are well matched with each other having minimum deviation. The density of the compound is quiet high as calculated by above analysis as well as from SEM image. Dielectric behaviour of the compound has been analyzed through the variation of dielectric constant with frequency while the electrical behaviour is studied through the complex impedance and modulus analysis. Additionally, verification of Jonscher's power law from ac conductivity study gives the detail findings about electrical behaviour of the material. Highlights • BFO-BST is a potential candidate for electronic devices. • BFO-BST is suitable for sensors, actuators or FeRAM. • BFO-BST can also be used for energy storage devices. • Low loss, high dielectric constant, high quality factors. [ABSTRACT FROM AUTHOR]

The matrix modulus and critical porosity in rocks are two critical parameters to seismic rock physics models; however, the critical porosity is difficult to obtain. Based on the linear relation between the effective bulk modulus and porosity, we propose a fast method for calculating the matrix modulus and critical porosity by least square fitting of effective bulk modulus and porosity data measured in laboratory or field. The proposed method is well suited for samples with wide porosity range. The calculation results accurately reflect the differences in clay content, pressure, and saturation state. Samples with high clay content have low matrix modulus and critical porosity. The matrix modulus is independent of pressure, whereas the critical porosity increases with increasing pressure. The calculated matrix modulus for water-saturated samples is higher than that for dry rock samples. [ABSTRACT FROM AUTHOR]

Highlights • BOF slag has a great potential of recycling. • BOF slag is a heterogeneous and complex material. • Mechanical properties of the different phases were determined using a coupled SEM-microindentation system. • The macro-mechanical properties were estimated from mixing laws and compared to macroindentation results. • The BOF Slag recycling can be optimized based on the knowledge of their mechanical properties. Abstract Steel slags are industrial by-products of an integrated steel plant, characterized by their high calcium, siliceous and ferrous content. They prove useful in many fields, such as civil engineering and in the process of steelmaking for the iron-rich phases. For a better valuation, it is important to optimize the separation of its phases. To separate these phases, mineral processing technologies such as grinding followed by magnetic separation are used. The overall goal of this work is to determine the mechanical properties of each phase to improve grinding performance. The results show that all compounds have been clearly identified and mechanically characterized, which has led to a better understanding of BOF (Basic Oxygen Furnace) slag. Finally, a mixture law using the mechanical properties calculated from each phase made it possible to estimate the overall mechanical properties of the BOF slag. [ABSTRACT FROM AUTHOR]

Abstract Ba 0.9 Ca 0.1 Ti 0.95 Zr 0.05 O 3 BCZT (10%, 5%) ceramic was prepared via solid state route. BCZT (10%, 5%) presents a coexistence of orthorhombic and tetragonal structures. By Raman spectroscopy the ferroelectric-paraelectric phase transition (T C) is detected. So as to investigate the electrical transport, a complex impedance spectroscopy is highlighted. With the Debye theory-based analysis and a series of Arrhenius relations, the Nyquist diagrams (Z″ versus Z′) are well suitable to an equivalent circuit model. The relaxation was argued to be related with the hopping motions of charge carriers between Ca2+ and Zr4+ ions. At various temperatures, the dielectric datum was analyzed using complex electrical modulus M*. The plot of modulus versus frequency presents a peak of relaxation. Using the universal Jonscher's power law, the AC conductivity for grain contribution is interpreted. Activation energies, determined from conductivity (E a = 1.23eV) and complex modulus (E a = 1.06 eV) are different, which confirms that the transport is ensured by an ion hopping mechanism. However, a dispersion of the conductivity was observed at medium frequencies and was explained using the correlated barrier hopping (CBH) model. [ABSTRACT FROM AUTHOR]

Oral lubrication deals with one of the most intricate examples of biotribology, where surfaces under sliding conditions span from the hardest enamel to soft oral tissues in human physiology. Complexity further arises with surfaces being covered by an endogenous biolubricant saliva before exogenous food particles can wet, stick, or slip at the surfaces. In this review, we present a description of soft oral surfaces, comparing them with the recent approaches that have been used to study oral lubrication using in vitro to ex vivo setups. Specifically, lubrication behaviors of saliva and soft microgels are discussed highlighting instances of hydration lubrication. We have structured this information creating a strong link between theoretical concepts and oral lubrication, which has thus far remained elusive in literature. Finally, we highlighted some of the several challenges remaining in this field and discussing how emerging technologies in material science might help overcoming them. Image 1 • Oral surface roughness with respect to tongue papillae structure is discussed. • Modulus and wettability of tongue and recently used tribomaterials are compared. • Lubrication of saliva and soft microgels in in vitro / ex vivo setups are examined. • Theoretical approximations to oral lubrication phenomena are detailed. • Materials science opportunities to emulate oral surfaces are outlined. [ABSTRACT FROM AUTHOR]

Abstract The solid electrolytes of Ce 0.9-x Y x Ca 0.1 O 2-δ with x = 0 and 0.05 were prepared by mechanical milling technique and investigated its dielectric properties. The frequency dependent ac conductivity of this oxide-ion conductor showed an unusual behavior compared to that of the cation conductors. As temperature increases the oxygen vacancy concentration increases due to the dissociation of oxygen vacancies from the defect pairs. The co-doped sample exhibit slightly higher conductivity compared to the singly doped sample. Dielectric relaxation analysis exhibited two relaxation peaks as a result of the bulk and grain boundary ionic migration process. Temperature dependent resonance frequencies and tan δ maxima of the relaxation peaks are used to measure the migration energy E M supporting the O2− migration and dissociation energy E D for the creation of free oxygen vacancy from the defect associates. A single relaxation peak observed in the modulus analysis corresponds to the reorientation relaxation of the defect associates. Highlights • Dielectric relaxation analysis in Ce 0.9-x Y x Ca 0.1 O 2-δ solid electrolytes. • Ac conductivity at high temperature is different in oxide ion conductors. • Dielectric relaxation analysis exhibit two relaxation peaks. • Migration and dissociation energy estimated from the dielectric analysis. • Modulus spectra corresponds to the reorientation relaxation of the defect associates. [ABSTRACT FROM AUTHOR]

Highlights • A theoretical indentation model applicable to film/substrate systems with large modulus ratios (E f /E s = 102–105) is established. • A new convenient method for measuring the modulus of nanofilm with limited thickness by indentation on hard film/soft substrate system is proposed. • Compared with the free-standing indentation test or bulge test, this method is more convenient and cheaper. • The effectiveness of the model and method was verified by experiments and simulations. Abstract Two-dimensional (2D) materials have received extensive attention due to their excellent physical and chemical properties, whose mechanical properties play critical roles in their applications. In this paper, a new convenient method for measuring the modulus of nanofilm by indentation on hard film/soft substrate system is proposed. In order to verify the correctness of the new method, the graphene oxide (GO) nanofilm deposited on polydimethylsiloxane (PDMS) is tested. The modulus of the GO nanofilm is measured as 60.39 ± 7.82 GPa, which is consistent with the modulus measured by previous researches. Finally, the finite element method (FEM) is used to investigate the effectiveness of the new method and to evaluate its error sensitivity to the indenter size, film radius, and the surface roughness. The results show that this method can accurately measure the modulus of nanofilm through the indentation response of the hard film/soft substrate system. Compared with the free-standing indentation test, the method proposed by us eliminates the disadvantages of boundary adhesion and has the advantages of simple sample preparation, easy operation, and high success rate. [ABSTRACT FROM AUTHOR]