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For their good randomness and long iteration periods, chaotic maps have been widely used in cryptography. Recently, we have revealed the correlation between Lyapunov exponent and sequence randomness of multidimensional chaotic maps based on modular operation. Since the modular operation can realize the boundedness of chaotic state points, it is important to further reveal the deterministic correlation between Lyapunov exponent and modulus. First, we constructed an n -dimensional nondegenerate hyperchaotic map model with the desired Lyapunov exponents. Then, we gave the existence and uniqueness proof of quadrature rectangle decomposition theorem and revealed the correlation between Lyapunov exponent and modulus. The novelty lies in that (1) in order to realize the irreversibility of the iterative processes of chaotic maps, we constructed a chaotic map based on modular exponentiation, and its inverse function is the discrete logarithm problem; and (2) we reveal for the first time the correlation between Lyapunov exponent and modulus, and give the lower bound of the modulus of the nondegenerate chaotic map. In addition, to verify the effectiveness of the scheme, we constructed four-dimensional and five-dimensional chaotic maps, respectively, and analyzed their dynamical behaviors, and the results revealed that there exist linear or nonlinear correlation between Lyapunov exponent and modulus. [ABSTRACT FROM AUTHOR]

Smart wearable sensors are increasingly integrated into everyday life, interfacing with the human body to enable real-time monitoring of biological signals. This study focuses on creating high-sensitivity capacitive-type sensors by impregnating polyester-based 3D spacer fabric with a Carbon Nanotube (CNT) dispersion. The unique properties of conductive particles lead to nonlinear variations in the dielectric constant when pressure is applied, consequently affecting the gauge factor. The results reveal that while the fabric without CNT particles had a gauge factor of 1.967, the inclusion of 0.04 wt% CNT increased it significantly to 5.210. As sensor sensitivity requirements vary according to the application, identifying the necessary CNT wt% is crucial. Artificial intelligence, particularly the Multilayer Perception (MLP) model, enables nonlinear regression analysis for this purpose. The MLP model created and validated in this research showed a high correlation coefficient of 0.99564 between the model predictions and actual target values, indicating its effectiveness and reliability. [ABSTRACT FROM AUTHOR]

Hydraulic asphalt concrete is known for its excellent seepage control performance and strong deformation resistance. This engineering material has widespread applications in the seepage control structures of hydraulic buildings. Recent projects have investigated the use of acidic aggregates to improve economic efficiency. However, they have also highlighted the weaker adhesion between acidic aggregates and asphalt, which necessitates stringent construction process control. This study investigates the impact of resting conditions on the tensile properties of acidic aggregate hydraulic asphalt concrete. The results of the tensile testing indicate that the storage time significantly affects the performance of asphalt concrete. The tensile strength of the specimens without anti-stripping agents decreased from 1.711 MPa to 0.914 MPa after resting periods of 0, 10, 20, and 30 days. The specimens treated with anti-stripping agents also showed a decrease in tensile strength over time, similar to the trend observed in the previous specimens. Digital specimen simulations indicated a decrease in cohesion between the asphalt and the aggregate from 5.375 MPa to 2.664 MPa after 30 days, representing a reduction of 50.44%. To counteract the effect of the storage time on the bonding between acidic aggregates and asphalt, this study recommends reducing the grading index and maximum size of aggregates, decreasing the coarse aggregate content, and selecting smooth aggregate shapes. [ABSTRACT FROM AUTHOR]

In this work, perovskite oxide SrCeO3 was synthesized using the solution combustion method (SCM). Synthesized samples have been characterized using X‐ray diffraction (XRD), Raman, ultra violet (UV)–visible spectroscopy, and scanning electron microscopy (SEM) techniques. The XRD and Rietveld refinement has confirmed the orthorhombic structure with space group Pnma. The average grain size of this ceramic sample is 1.2 µm. The dielectric constant, dissipation factor, modulus, impedance, and alternating current (AC) and direct current (DC) conductivities were analyzed in the temperature range RT to 600°C and frequency range 20 Hz–2 MHz. Further, it was observed that the role of grain boundaries in dielectric and electrical properties is significant, at low temperatures. The origin of the dielectric relaxation and conduction process is the same. The activation energy for DC conduction (Edc) was found to be.79 eV. Electrical conduction/relaxation is assigned to the diffusion of doubly ionized oxygen (Vo··). The value of DC conductivity (1.2 × 10−3 Ω−1 cm−1 at 600°C) and activation energy of.79 eV is very close to the values reported for doped CeO2‐based oxide ion conductors for SOFCs. This study has demonstrated that SrCeO3 can be an alternative candidate for the oxide ion conductor electrolyte application and the potential to be used as a thermally stable capacitor application for microwave dielectric applications. [ABSTRACT FROM AUTHOR]

To promote resourceful utilization of argon oxygen decarburization (AOD) slag, this research developed a new three-ash stabilized recycled aggregate with AOD slag, cement, fly ash (FA), and recycled aggregate (RA) as raw materials. The AOD slag was adopted as an equal mass replacement for fly ash. The application of this aggregate in a road base layer was investigated in terms of its mechanical properties and mechanistic analysis. First, based on a cement: FA ratio of 1:4, 20 sets of mixed proportion schemes were designed for four kinds of cement dosage and AOD slag replacement rates (R/%). Through compaction tests and the 7-day unconfined compressive strength test, it was found that a 3% cement dosage met the engineering requirements. Then, the unconfined compressive strength test, indirect tensile strength test, compressive rebound modulus test, and expansion rate test were carried out at different age thresholds. The results showed that the mixture's strength, modulus, and expansion rate increased initially and then stabilized with age, while the strength and modulus initially increased and then decreased with increasing R. Secondly, based on X-ray diffraction (XRD) and scanning electron microscopy (SEM) used to analyze the mechanism, it was found that the strength, modulus, and expansion rate of the new material can be promoted by blending AOD slag, due to its ability to fully stimulate the hydration reaction and pozzolanic reaction of the binder. Finally, based on the strength and modulus results, R = 3% was identified as the optimal ratio, which provides a reference point for the effective application of AOD slag and RA in road base materials. [ABSTRACT FROM AUTHOR]

Third-degree burn injuries pose a significant health threat. Safer, easier-to-use, and more effective techniques are urgently needed for their treatment. We hypothesized that covalently bonded conjugates of fatty acids and tripeptides can form wound-compatible hydrogels that can accelerate healing. We first designed conjugated structures as fatty acid–aminoacid1–amonoacid2–aspartate amphiphiles (Cn acid–AA1–AA2–D), which were potentially capable of self-assembling into hydrogels according to the structure and properties of each moiety. We then generated 14 novel conjugates based on this design by using two Fmoc/tBu solid-phase peptide synthesis techniques; we verified their structures and purities through liquid chromatography with tandem mass spectrometry and nuclear magnetic resonance spectroscopy. Of them, 13 conjugates formed hydrogels at low concentrations (≥0.25% w/v), but C8 acid-ILD-NH2 showed the best hydrogelation and was investigated further. Scanning electron microscopy revealed that C8 acid-ILD-NH2 formed fibrous network structures and rapidly formed hydrogels that were stable in phosphate-buffered saline (pH 2–8, 37 °C), a typical pathophysiological condition. Injection and rheological studies revealed that the hydrogels manifested important wound treatment properties, including injectability, shear thinning, rapid re-gelation, and wound-compatible mechanics (e.g., moduli G″ and G′, ~0.5–15 kPa). The C8 acid-ILD-NH2(2) hydrogel markedly accelerated the healing of third-degree burn wounds on C57BL/6J mice. Taken together, our findings demonstrated the potential of the Cn fatty acid–AA1–AA2–D molecular template to form hydrogels capable of promoting the wound healing of third-degree burns. [ABSTRACT FROM AUTHOR]

Optimization of energy storage performance in dielectric ceramics has been a focus in recent decades due to the benefits of high energy storage density, efficiency, and exceptional temperature stability. In this work, we report huge dielectric constant in La0.55Li0.35TiO3‐δ and sharp decrease in its value with the substitution of Sr and Cu at Ti position. These samples La0.55Li0.35TiO3‐δ (LLTO), La0.55Li0.35Ti0.9Cu0.1O3‐δ (LLTCO) and La0.55Li0.35Sr0.1Ti0.9O3‐δ (LLSTO) were prepared by solid state reaction method. The interfacial polarization of lithium ion aggregation close to the grain boundaries and the dipoles of Li ions in the sample are suggested to be the source of the enormous dielectric values. Parent composition (LLTO) shows highest dielectric constant value (6.29 × 105 at frequency 10 Hz, 7.30×104 at 1 kHz) recorded at room temperature while the lowest dielectric loss value (0.124) was observed for LLSTO at frequency 1 kHz. Structural characterization has been done using X‐ray diffraction (XRD) technique to investigate the crystal structure of the prepared compositions. The XRD patterns show the similar crystal structure for all the compositions with the parent composition LLTO. The optical band gap is calculated by Kulbeka Munk function and Tauc plot using UV–visible diffuse reflectance spectroscopy technique. The maximum band gap value (3.32 eV) is obtained for parent composition while doping of Cu and Sr at Ti site in La0.55Li0.35TiO3‐δ decreases the band gap value. Optical microscopy shows the micron size grains in these samples. Doping of Sr and Cu in perovskite structure of LLTO brings tunability in dielectric and optical properties. [ABSTRACT FROM AUTHOR]

As wind turbine power requirements have evolved from the order of kilowatts (kWs) to the order of several megawatts (MWs), wind turbine components have been subjected to more demanding and critical operating conditions. The wind turbine must cope with higher wind loads due to larger blade sizes, which are also time-varying, and, ultimately, higher power levels. One of the challenges in the manufacture of high-power wind turbines lies in the gearbox and consists of achieving ever-greater power density without compromising efficiency, i.e., greater load capacity with lower weight (and production cost) and reduced power losses. Epicyclic geartrains are used to build the gearbox due to various advantages in relation to conventional gear systems, such as higher feasible gear ratios, higher efficiency, compactnesss, and lower weight. In this paper, several epicyclic geartrains with different structures will be analysed to reveal the influence that certain design parameters have on the size and weight of the gearbox components in the selected model and, therefore, of the gearbox itself. For this purpose, the theoretical model of the gearbox will be planned and the influence of the calculation parameters on the gearbox design will be analyzed following ISO 6336. Special emphasis is placed on the influence of the material used; the modulus and tooth width on the size and weight of the gearbox will be observed. Critical stresses are also calculated. The goal is to prepare the theoretical basis for an optimization process subject to geometric, kinematic, and dynamic constraints that will result in a gearbox as compact, energy-dense, and light as possible without compromising the service life of the components. [ABSTRACT FROM AUTHOR]

The effect of frequency and temperature on the permittivity and transport properties of calcium manganese was investigated. The sample was synthesized using a simple, an economic and a reproducible complex polymerizable route. Thereafter, it was characterized by the X-ray diffraction and complex impedance spectroscopy techniques. The obtained results showed that CaMnO3–δ exhibits a semiconducting behaviour between room temperature and 400°C. Beyond that temperature, the perovskite behaves as a metal. As for the activation energy, it showed a change around 400°C, which is attributed to the first-order transition from semiconducting to the metallic behaviour. Moreover, the dielectric constant and the loss exhibited a decreasing trend with increasing frequency, which is a characteristic of polar dielectrics. Between 25 and 400°C, the maximum barrier height increased from 0.1 to 0.32 eV. The low dissipation factor at high frequencies seems to be an interesting feature highlighting the promising use of CaMnO3–δ in high-frequency microwave device applications. [ABSTRACT FROM AUTHOR]

Generally, the dynamic modulus and bending stiffness modulus are used to evaluate the mechanical properties of asphalt mixture, and they are also used as basic parameters for asphalt mixture design. Therefore, a study was conducted on changes in the dynamic modulus and bending stiffness modulus of hot-recycled asphalt mixture with high levels of reclaimed asphalt pavement (RAP) under the influence of different factors: dosage of regenerant, curing temperature, and curing time. The performance of reclaimed asphalt pavement (RAP) was first evaluated. Then, the hot-recycled asphalt mixture was adjusted and designed in order to conduct modulus experiments, composed of the dynamic modulus test and three-point bending test. Finally, the influencing factors were not only qualitatively but also quantitatively analyzed to clarify the change laws of the mechanical parameters of hot-recycled asphalt mixture. The results showed that the modulus of the recycled asphalt mixture first decreased, then increased, and then decreased with increasing dosage of regenerant. As the curing time or temperature increased, the modulus first decreased and then increased. In terms of the dynamic modulus of the hot-recycled asphalt mixture, the curing time had the greatest impact, followed by dosage of the regenerant and curing temperature. For bending stiffness modulus, the influence of dosage of the regenerant was the greatest, followed by curing time and curing temperature. For the bending stiffness modulus of hot-recycled asphalt mixture, the curing conditions had a greater influence compared with the dynamic modulus. [ABSTRACT FROM AUTHOR]

The current work is focused on numerical and experimental studies of woven fabric composites modified by hybridisation with biological (cellulosic) filler materials. The mechanical performance of the composites is characterized under tensile, bending and impact loads and the effect of hybridisation is observed with respect to pure and nonhybrid composites. Numerical models are developed using computational tools to predict mechanical performance under tensile loading. The computational prediction results are compared and validated with relevant experimental results. This research is aimed at understanding the mechanical performance of basalt–epoxy composites partially reinforced with micro-/nano-sized bio-fillers from cellulose and intended for various application areas. Different weave structures, e.g., plain, twill, matt, etc., were investigated with respect to the mechanical properties of the hybrid composites. The effects of hybridizing with cellulose particles and different weave patterns of the basalt fabric are studied. In general, the use of high-strength fibres such as basalt along with cellulosic fillers representing up to 3% of the total weight improves the mechanical performance of the hybrid structures. The thermomechanical performance of the hybrid composites improved significantly by using basalt fabric as well as by addition of 3% weight of cellulosic fillers. Results reveal the advantages of hybridisation and the inclusion of natural cellulosic fillers in the hybrid composite structures. The material developed is suitable for high-end applications in components for construction that demand advanced mechanical and thermomechanical performance. Furthermore, the inclusion of biodegradable fillers fulfills the objectives of sustainable and ecological construction materials. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles of NiFe2O4 were successfully prepared by utilizing the sol–gel techniques. The prepared samples were investigated through various techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), dielectric spectroscopy, DC magnetization and electrochemical measurements. XRD data analysed using Rietveld refinement procedure inferred that NiFe2O4 nanoparticles displayed a single-phase nature with face-centred cubic crystallinity with space group Fd-3m. Average crystallite size estimated using the XRD patterns was observed to be ~10 nm. The ring pattern observed in the selected area electron diffraction pattern (SAED) also confirmed the single-phase formation in NiFe2O4 nanoparticles. TEM micrographs confirmed the uniformly distributed nanoparticles with spherical shape and an average particle size of 9.7 nm. Raman spectroscopy showed characteristic bands corresponding to NiFe2O4 with a shift of the A1g mode, which may be due to possible development of oxygen vacancies. Dielectric constant, measured at different temperatures, increased with temperature and decreased with increase in frequency at all temperatures. The Havrilliak–Negami model used to study the dielectric spectroscopy indicated that a NiFe2O4 nanoparticles display non-Debye type relaxation. Jonscher's power law was utilized for the calculation of the exponent and DC conductivity. The exponent values clearly demonstrated the non-ohmic behaviour of NiFe2O4 nanoparticles. The dielectric constant of the nanoparticles was found to be >300, showing a normal dispersive behaviour. AC conductivity showed an increase with the rise in temperature with the highest value of 3.4 × 10−9 S/cm at 323 K. The M-H curves revealed the ferromagnetic behaviour of a NiFe2O4 nanoparticle. The ZFC and FC studies suggested a blocking temperature of ~64 K. The saturation of magnetization determined using the law of approach to saturation was ~61.4 emu/g at 10 K, corresponding to the magnetic anisotropy ~2.9 × 104 erg/cm3. Electrochemical studies showed that a specific capacitance of ~600 F g−1 was observed from the cyclic voltammetry and galvanostatic charge–discharge, which suggested its utilization as a potential electrode for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Coatings with tunable refractive index and high mechanical resilience are useful in optical systems. In this work, thin films of HfO2 doped with Al2O3 were deposited on silicon at 300 °C by using plasma-enhanced atomic layer deposition (PE-ALD). The mainly amorphous 60–80 nm thick films consisted Al in the range of 2 to 26 at.%. The refractive indexes varied from 1.69 to 2.08 at the wavelength of 632 nm, and they consistently depended on the composition. The differences were higher in the UV spectral region. At the same time, the hardness of the films was from 12–15 GPa; the modulus was in the range of 160–180 GPa; and the mechanical properties did not have a good correlation with the deposited compositions. The deposition conditions, element contents, and refractive indexes at respective wavelengths were correlated. The results indicated that it is possible to tune optical properties and retain mechanical properties of atomic layer-deposited thin films of HfO2 with Al2O3 as doping oxide. Such films could be used as mechanically resilient and optically tunable coatings in, for instance, micro- or nano-electromechanical systems or transparent displays. [ABSTRACT FROM AUTHOR]

Structural coloring of dental resin-based composites (RBC) is used to create universal chromatic materials designed to meet any aesthetic need, replacing the mixing and matching of multiple shades. The microstructural adjustments to create this desideratum involve nanoscale organic–inorganic core–shell structures with a particular arrangement. The generally higher polymer content associated with these structures compared to universal chromatic RBCs colored by pigments, which in their microstructure come close to regularly shaded RBCs, can influence the way the material ages. Accelerated and slow aging up to 1.2 years of immersion in artificial saliva at 37 °C were therefore compared in relation to their effects on the materials described above and in relation to the immersion conditions prescribed by standards. Quasi-static and viscoelastic parameters were assessed to quantify these effects by a depth-sensing indentation test equipped with a DMA module. The microstructure of the materials was characterized by scanning electron microscopy. The results convincingly show a differentiated influence of the aging protocol on the measured properties, which was more sensitively reflected in the viscoelastic behavior. Accelerated aging, previously associated with the clinical behavior of RBCs, shows a 2- to 10-fold greater effect compared to slow aging in artificial saliva of up to 1.2 years, highly dependent on the microstructure of the material. [ABSTRACT FROM AUTHOR]

Cobalt sulphides, including CoS, CoS2, Co3S4 and Co9S8, have been studied as potential anode materials for Li- and Na-ion batteries. However, the mechanical properties of the cobalt sulphides have not been intensively investigated. In this work, density functional theory (DFT) calculation was employed to study the mechanical properties of the cobalt sulphides mentioned above. Besides, the mechanical properties of final products of lithiation/sodiation of Co9S8 have been calculated, including the bulk modulus, shear modulus, Young’s modulus and Poisson’s ratio. This work provides an insight into understanding the electrochemical performance of Co9S8 material as anode material for Li- and Na-storage during the cycling process. [ABSTRACT FROM AUTHOR]

Polymeric hydrogels have drawn considerable attention as a biomedical material for their unique mechanical and chemical properties, which are very similar to natural tissues. Among the conventional hydrogel materials, self-healing hydrogels (SHH) are showing their promise in biomedical applications in tissue engineering, wound healing, and drug delivery. Additionally, their responses can be controlled via external stimuli (e.g., pH, temperature, pressure, or radiation). Identifying a suitable combination of viscous and elastic materials, lipophilicity and biocompatibility are crucial challenges in the development of SHH. Furthermore, the trade-off relation between the healing performance and the mechanical toughness also limits their real-time applications. Additionally, short-term and long-term effects of many SHH in the in vivo model are yet to be reported. This review will discuss the mechanism of various SHH, their recent advancements, and their challenges in tissue engineering, wound healing, and drug delivery. [ABSTRACT FROM AUTHOR]

In this work, Gd2O3 bulks were sintered at temperatures ranging from 1400 °C to 1600 °C for times from 6 h to 24 h, and their microstructure and properties were studied for a wider application of materials in thermal barrier coatings. The densification of the Gd2O3 bulk reached 96.16% when it was sintered at 1600 °C for 24 h. The elastic modulus, hardness, fracture toughness and thermal conductivity of the bulks all increased with the rise in sintering temperature and extension of sintering time, while the coefficient of thermal expansion decreased. When the Gd2O3 bulk was sintered at 1600 °C for 24 h, it had the greatest elastic modulus, hardness, fracture toughness and thermal conductivity of 201.15 GPa, 9.13 GPa, 15.03 MPa·m0.5 and 2.75 W/(m·k) (at 1100 °C), respectively, as well as the smallest thermal expansion coefficients of 6.69 × 10−6/°C (at 1100 °C). [ABSTRACT FROM AUTHOR]

The melt-quenching technique was used to synthesize tellurite glasses of the chemical composition 80TeO2-(20-x) ZnO-xV2O5. X-ray diffraction (XRD) patterns indicate the amorphous nature of the prepared glasses. Raman and FTIR measurements demonstrate a progressive substitution of the Te-O-Te linkages by the Te-O-V bridges and the formation of VO4 and VO5 units by a change of the vanadium coordination due to the higher number of oxygens incorporated by further addition of V2O5. The AC conductivity was investigated in the frequency range of 40 Hz to 107 Hz between 473 K to 573 K. A good coherence of the AC conductivity was found using a model correlating the barrier hopping (CPH) and the dominant conduction process changes from ionic to polaronic with the addition of V2O5. The dielectric constant exhibits high values in the range of lower and medium frequencies. Both variations of the electric modulus and the dielectric loss parameters with frequency and temperature showed a relaxation character mainly assigned to the vanadate phases. The electric modulus displays a non-Debye dielectric dispersion and a relaxation process. The present results open the door to future zinc-tellurite glasses-doped vanadium exploitation as a potential electrolyte-based material for solid-state batteries. [ABSTRACT FROM AUTHOR]

Most commercially-available mechanical testing devices are bulky, expensive, and unable to evaluate changes in sample microstructure under load. This leaves a crucial gap in understanding between material structure and bulk mechanical properties. Our objective was to fabricate a mechanical testing device small enough to fit in most upright or inverted microscopy stages and able to position samples to allow for simultaneous mechanical and microstructural characterization. Parts were 3D printed using the hobbyist-friendly Fused Filament Fabrication technique, then assembled with commercial fasteners and translation components to create a mechanical testing device that utilized the deflection of plastic posts to determine sample reaction forces under applied strain. Video of sample deformation was analyzed using a custom processing script to calculate stress and strain behavior in an automated and high-throughput manner. This device was able to perform mechanical characterization with an accuracy comparable to commercial mechanical testing devices for a wide range of nonlinear and viscoelastic samples under dry and hydrated conditions. Additionally, the device showed compatibility with different upright and inverted microscopes and was able to demonstrate accurate mechanical testing results when used with these instruments. We successfully developed a device capable of accurately testing a majority of soft materials in the field of Biomedical Engineering with the ability to perform additional microstructural characterization using microscopy at a price point of $600. [ABSTRACT FROM AUTHOR]

In this paper, we present an extensive experimental study on the dynamic mechanical properties of composites with polymer matrices, as well as a quantification of the parameters that influence these properties. Polymer-composite matrices make it possible to form any reinforcement arrangement of fibres, particles, and layers, which makes it possible to form composite materials with certain dominant mechanical properties according to the internal arrangement for the application. In this study, we focused on the dynamic properties (i.e., damping parameters, such as the loss factor (tan d), logarithmic decrement (λ), storage modulus (E′), and loss modulus (E″)) of composites with polymer matrices, including parameters such as the fibre material, fabric weaving, fibre orientation, temperature, frequency, particle size, volume of short fibres, and epoxy resin type. If other articles focus on one type of composite and 1–2 parameters, then the benefit of this article lies in our analysis of 8 mentioned parameters in the experimental analysis of 27 different types of composites with polymer matrices. The tested fibre materials were glass, aramid, and carbon; the tested woven fabrics were twill, plain, unidirectional, and satin; the temperature range was from −50 to +230 °C; the frequency was 1 Hz and 10 Hz; the particle size was 0.1–16 mm; the volume percentages of the short fibres were 3, 6, and 12 vol.% of the hybrid polymer composites and the type of polymer matrix. We used the free-damped-vibration method with vibration dynamic signal analysis and the forced-damped vibration of dynamic mechanical thermal analysis for testing. We ranked the parameters that influence the dynamic vibration properties according to the effects. Among sets of results provided in the paper, considering the storage modulus, loss modulus, and loss factor, the best results of the fibre composites were for aramid-fibre-reinforced polymers, regardless of the weave type, with an advantage for unidirectional fabric. The best results of the particle composites were for those with fine filler sizes that incorporated the short fibres. [ABSTRACT FROM AUTHOR]

With the increase in the use of high-density polyethylene (HDPE) products and the serious long-term hazard they pose to the environment, there has been an increasing need to decrease the release of these materials to the environment as waste. This study sets out to develop and optimize the mechanical properties of the GLP-HDPE composite, a sustainable material made from agro residues (ginger leaf particles (GLP)) and high-density polyethylene waste materials. The Taguchi robust technique, analysis of variance, and regression analysis were employed to optimize, analyze, and model the behavior of the composite materials with respect to the developmental factors of particle size and particle content. The optimum bending modulus of elasticity (MOE), modulus of rupture (MOR), and impact energy (IE) of the developed composites was 2490 MPa, 11.90 MPa, and 4.1 J at a particle size/particle content combination of 710 µm/35%, 520 µm/35%, and 710 µm/45%, respectively. Analysis of variance at 95% confidence level showed that the particle content had a significant effect on the MOE, MOR, and IE of the GLP-HDPE composite with a minimum percentage contribution of 71.61%. Equations for predicting the MOE, MOR, and IE of the composites were developed with good prediction accuracy. [ABSTRACT FROM AUTHOR]

To date, there have been a limited number of studies modeling the tensile modulus in the polymer halloysite nanotube (HNT) systems before or after percolation onset. In this paper, an equation for a composite's modulus post-percolation onset was developed for HNT-filled samples including the interphase and HNT network. The dispersed nanoparticles and adjoining interphase part were neglected, because they caused ineffective influences on the stiffness of the system after percolation onset. The developed model reflects the impacts of HNTs' size, interphase depth, percolation onset and the volume shares and moduli of the HNT network and its adjacent interphase on the modulus of HNT-based systems. The impacts of issues on the nanocomposite modulus are defendable, confirming the effectiveness of the developed model. HNT length, interphase depth, HNT concentration, net modulus and net portion directly influenced the stiffness, while the HNT radius and percolation onset had inverse effects. Results show that there was a 142% improvement in the modulus of samples at an interphase depth of 40 nm. Moreover, the stiffness improved by 60% at a net modulus of 200 GPa, but it later exhibited a 180% enhancement at a net modulus of 1000 GPa. In addition, the experimental data for the modulus of numerous composites display fine agreement to the predictions, confirming the validity of the developed model. [ABSTRACT FROM AUTHOR]

The objective was to evaluate new commercially available ion-releasing restorative materials and compare them to established anti-cariogenic materials. Four materials were tested: alkasite Cention (Ivoclar Vivadent) in self-cure or light-cure mode, giomer Beautifil II (Shofu), conventional glass-ionomer Fuji IX (GC), and resin composite Tetric EvoCeram (Ivoclar Vivadent) as a control. Flexural strength, flexural modulus, and Weibull modulus were measured one day, three months, and after three months with accelerated aging in ethanol. Water sorption and solubility were evaluated for up to one year. Degree of conversion was measured during 120 min for self-cured and light-cured Cention. In this study, Beautifil II was the ion-releasing material with the highest flexural strength and modulus and with the best resistance to aging. Alkasite Cention showed superior mechanical properties to Fuji IX. Weibull analysis showed that the glass-ionomer had the least reliable distribution of mechanical properties with the highest water sorption. The solubility of self-cured alkasite exceeded the permissible values according to ISO 4049. Degree of conversion of light-cured Cention was higher than in self-cure mode. The use of alkasite Cention is recommended only in the light-cure mode. [ABSTRACT FROM AUTHOR]

The performance degradation of fiber-reinforced polymer (FRP) is a typical sequential data with a highly non-linear evolution pattern. In this study, a Self-constructed strategy-based reinforcement LSTM approach (short for SCRLA) is proposed to self-accommodate the non-linear sequential data, reduce modeling burden, and improve generalization ability. SCRLA incorporates Bayesian algorithms introducing the uncertainty of hyperparameter optimization by a probabilistic distribution of implicit objectives and self-constructed a high-dimensional, reinforced machine model that can learn and predict non-linear representations. In the case study, the datasets with different properties (one consisting of finite element analysis (FEA) results and one of real experimental (EXP) data) are selected to verify the validity of the degradation performance predictions. It is shown that the reinforced LSTM based on SCRLA is more suitable for the non-linear degradation performance analysis of FRP, especially with higher prediction accuracy for EXP data. The establishment of the approach and model provides a feasible idea and framework for the prediction of composites' sequential performance. [Display omitted] [ABSTRACT FROM AUTHOR]

• A thermodynamic model is developed to predict the property of stochastic heterogeneous material. • Metal wires with various gauge length are tensile tested to verify the feasibility of the model. • With decreasing gauge length, the failure strain decreases and fracture stress almost unchanged. • The newly developed random field model can well demonstrate the origination of size effect. • Size effect originates from the intrinsic stochasticity and correlation of mechanical property. Materials are intrinsic stochastic heterogeneity regardless of their natural or artificial origin. Traditional models for predicting mechanical properties of materials typically involve homogenization, which exhibits certain limitations in practical applications, such as investigating the size effect in stress–strain relationships. In this study, a random field thermodynamic theory for predicting the mechanical properties of stochastic heterogeneous materials was proposed, and its applicability and reliability were verified by testing hard-drawn 304 stainless-steel wires with gauge lengths of 10–500 mm. In these wires composed of the lamellar martensite with a thickness of ∼47.1 nm, it is found that failure strains decreased significantly with increasing gauge length, whereas fracture stresses show little dependence on the gauge length leading to a great increase of the effective modulus. Digital image correlation investigations revealed a significant strain heterogeneity during the tensile process, even at the elastic deformation stage. Nanoindentation tests show the non-uniformly distributed reduced modulus and hardness, which can be attributed to the intrinsic stochastic heterogeneity of materials. Taking Young's modulus as a one-dimensional stationary random field along the longitudinal direction, our random field model can well demonstrate the variation of failure strain and effective modulus with changing gauge lengths. The size effect on the macroscopic mechanical properties mainly originated from the microscopic mechanical property correlation of different points within the materials. These findings could provide new insights into the size effect on the mechanical properties of materials. [ABSTRACT FROM AUTHOR]

Nanoparticle (NP) stiffness has been shown to significantly impact circulation time and biodistribution in anticancer drug delivery. In particular, the relationship between particle stiffness and tumor accumulation and penetration in vivo is an important phenomenon to consider in optimizing NP-mediated tumor delivery. Layerby- layer (LbL) NPs represent a promising class of multifunctional nanoscale drug delivery carriers. However, there has been no demonstration of the versatility of LbL systems in coating systems with different stiffnesses, and little is known about the potential role of LbL NP stiffness in modulating in vivo particle trafficking, although NP modulus has been recently studied for its impact on pharmacokinetics. LbL nanotechnology enables NPs to be functionalized with uniform coatings possessing molecular tumor-targeting properties, independent of the NP core stiffness. Here, we report that the stiffness of LbL NPs is directly influenced by the mechanical properties of its underlying liposomal core, enabling the modulation and optimization of LbL NP stiffness while preserving LbL NP outer layer tumor-targeting and stealth properties. We demonstrate that the stiffness of LbL NPs has a direct impact on NP pharmacokinetics, organ and tumor accumulation, and tumor penetration--with compliant LbL NPs having longer elimination half-life, higher tumor accumulation, and higher tumor penetration. Our findings underscore the importance of NP stiffness as a design parameter in enhancing the delivery of LbL NP formulations. [ABSTRACT FROM AUTHOR]

Marginal hard asphalt possesses high stiffness and modulus; however, due to poor ductility at low temperature, it was seldom applied into road structures. Increasing asphalt content seemed to be an effective way to minimize the thermal cracking problem of hard hot-mix asphalt (HMA). Therefore, three types of methods (Groups 2–4) aiming to improve hard asphalt content were designed and compared with the traditional method (Group 1). Specifically, Groups 2 and 3 were designed with coarser gradation and lower gyration levels (Ndes), respectively, and Group 4 was designed following the enrobé à module élevé 2 (EME2) method. The high- and low- temperature, fatigue, modulus, and cracking performance were then conducted for each group. It can be seen that with the increase of asphalt content, the low-temperature strain increased in all three groups, of which Groups 2 and 3 improved more significantly. In addition, with the coarser gradation or lower Ndes , the high-temperature and cracking resistance of hard HMAs was lost to some degree; however, they can still compete with traditional neat HMAs. The hard HMAs designed with EME2 method performed excellent dynamic modulus and rutting resistance. Moreover, the hard HMAs designed with EME2 method and lower Ndes showed a surprising improvement in the fatigue life. These results may contribute to the better use of hard HMAs. [ABSTRACT FROM AUTHOR]

Macromolecular components of the vascular extracellular matrix (ECM), particularly elastic fibers and collagen fibers, are critical for the proper physiological function of arteries. When the unique biomechanical combination of these fibers is disrupted, or in the ultimate extreme where fibers are completely lost, arterial disease can emerge. Bioengineers in the realms of vascular tissue engineering and regenerative medicine must therefore ideally consider how to create tissue engineered vascular grafts containing the right balance of these fibers and how to develop regenerative treatments for situations such as an aneurysm where fibers have been lost. Previous work has demonstrated that the primary cells responsible for vascular ECM production during development, arterial smooth muscle cells (SMCs), can be induced to make new elastic fibers when exposed to secreted factors from adipose-derived stromal cells. To further dissect how this signal is transmitted, in this study, the factors were partitioned into extracellular vesicle (EV)-rich and EV-depleted fractions as well as unseparated controls. EVs were validated using electron microscopy, dynamic light scattering, and protein quantification before testing for biological effects on SMCs. In 2D culture, EVs promoted SMC proliferation and migration. After 30 days of 3D fibrin construct culture, EVs promoted SMC transcription of the elastic microfibril gene FBN1 as well as SMC deposition of insoluble elastin and collagen. Uniaxial biomechanical properties of strand fibrin constructs were no different after 30 days of EV treatment versus controls. In summary, it is apparent that some of the positive effects of adipose-derived stromal cells on SMC elastogenesis are mediated by EVs, indicating a potential use for these EVs in a regenerative therapy to restore the biomechanical function of vascular ECM in arterial disease. [ABSTRACT FROM AUTHOR]

Elaborating an instrumented nanoindentation is to exercise nondestructive tests to be applied to volumes of polymethylmetacrylate (PMMA) materials in miniature. This work focuses on factors that explain the trends variation of mechanical properties like Young's modulus (E), contact hardness (H) and indentation force (P). The evolution of E and H with depth (h) and P shows a 2.77 nm inflection point at low penetrations, separating two zones: the first increasing and the second decreasing. This is respectively explained by the surface hardening induced by preparing the material surface, and the existence of a surface hardness gradient denoted by an indentation size effect (ISE) observed at very low depths. Moreover, In addition, a critical penetration depth of 9.71 nm below which the surface effect dominates the variation of the penetrating load is detected. E and H results differences between dynamic and static modes are 8.46% and 6.44% inducing an overestimation of 35 MPa in E value, and an underestimation of 1.23 MPa in H value. This tends to affect the expected nanoscale precision of the indentation to determine the nanomechanical properties of PMMA. [ABSTRACT FROM AUTHOR]

Background: The modulus and resonant frequency of cancer cells and extracellular matrix are increased in both basal cell and squamous cell carcinomas, and in addition, the collagen stiffness is increased. The organization of the extracellular matrix surrounding cancer cells is clearly different than the extracellular matrix that is seen in normal skin. Materials and Methods: We have used vibrational optical coherence tomography (VOCT) to measure the resonant frequency and stiffness of collagen, vascular, and reorganized fibrous extracellular matrix components. Measurements of vessels and fibrotic collagen content made on basal cell carcinomas (BCCs) are compared to similar measurements made on normal skin from different anatomical locations. Results: Lesions with basal cell carcinomas exhibit characteristic resonant frequencies and moduli of reorganized extracellular matrix characteristic of fibrotic tissue. Cancerous lesions are characterized by dermal collagen (100 Hz), vascular (150 Hz), and fibrotic peaks (200‐230 Hz). The fibrotic peak is not found in areas of normal skin. Conclusions: Based on this pilot study, it is hypothesized inflammation may promote precancerous lesion formation in the surrounding extracellular matrix. Measurement of the increases in vaculature and fibrotic content may be useful in early detection of BCCs. [ABSTRACT FROM AUTHOR]

The arterial blood supply and innervation of the inner ear especially the cochlea of the camel was examined both macroscopically and microscopically using different techniques. The aim of this study to observe any variation between the arterial blood supply and innervation of the camel and the other mammals. The results of this study show variation between the camel and the other domestic animals in the course of the main arterial blood vessel, which supply the inner ear, caudal cerebellar artery. Also, the angle of vestibulocochlear nerve and facial nerve at internal acoustic meatus is recorded. The cochlear artery and nerve show type of modification in the modulus of the cochlea, which influences in the morphology of the cochlea and consequently in physiological function. We conclude that, though both routes cleared the parasitaemia and the intravenous route was well tolerated, no summative comparative advantage was seen over the intramuscular routes in the parameters observed in this study. Further work is needed to examine if advantage can be observed in long term prevention of relapse by the intravenous route. [ABSTRACT FROM AUTHOR]

Epoxy-cashew nut shell liquid (E-CNSL) composites are prepared by open resin moulding method with varying CNSL content (16 to 30 vol. %.). The tensile properties, hardness and impact strength of E-CNSL composites were investigated as per ASTM standards. It is found that the addition of the CNSL in epoxy increases the elongation at break and tensile strength. The 16 vol. % CNSL addition showed maximum tensile strength, and further increased CNSL deteriorates the tensile properties of the resultant composites. Further, hybrid composites are prepared by reinforcing crumb rubber (CR), short banana fibre (BF) and friction dust (FD) in cashew nut shell liquid (CNSL) mixed epoxy. The samples were tested as per ASTM standards to investigate the basic mechanical properties. It is found that the hybrid composite made of 2.5 vol. % CR, 2.5 vol. % FD and 7.5 vol. % BF in epoxy with 16 vol. % of CNSL showed better properties. Further, the specific wear rate, coefficient of friction and rate of water intake is investigated for the hybrid composite and reported. [ABSTRACT FROM AUTHOR]

One of the major obstacles restricting the wide applications of Mg alloys is their low Young's modulus at ∼45 GPa, which is uncompetitive to Al alloy over 60 GPa. To resolve this issue, we proposed a new strategy of designing ultra-light Mg-Li alloys by employing the microscale compounds in both HCP and BCC grains to achieve high Young's modulus. HCP or BCC alone cannot achieve a high modulus due to the segregation of solutes at the grain boundaries and the formation of brittle intermetallics in the interdendritic region. We designed chemistry that is so perfect to arrest the excess solutes inside the BCC matrix during solidification and engulf pre-solidified rare earth particles by HCP primary grains which have such a lean chemical composition that has almost no segregation. During solution heat treatment, the dissolution of solutes pushes the BCC boundary towards HCP grains by Ostwald ripening (BCC structures are interconnected but the HCP structures are isolated). During low-temperature aging heat treatment, nucleation of HCP structure on the rare earth particles inside the BCC grain is found, degrading the strength. Therefore, a novel Mg-Li-Al-Zn-Y-Mn-Gd (LAZWMV) alloy with a very high modulus was designed which reaches Young's modulus as high as 61.4 GPa. Micro-compounds (AlLi and Al-X) with average equivalent diameters of 3.76 µm and 6.55 µm were quantified in 3D using X-ray computed tomography and nanoindentation tests for establishing the microstructure-modulus correlation. The influence of Li addition on Mg-Mg was calculated by DFT calculations and the mechanism of modulus improvements has been proposed. [Display omitted] • Ultra-light Mg-Li alloy was designed with high strength and high modulus. • Super-high Young's Modulus of 61.4 GPa was first reported for a novel Mg alloy. • Nanoindentation uncovers the principles of modulus increase in Mg-Li alloys. • Quantitative 3D characterization of high modulus phase using XCT prectict alloy properties. • DFT calculation of Mg-Mg bonds explores the effects of heat treatments. [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]

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]

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]

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]

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]

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]

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]

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]

Background: The need to quantitatively identify the composition and organization of the macromolecular components of skin, skin lesions, scars, tumors, extracellular matrices (ECMs), and wound tissue has been a goal of researchers for many decades. A variety of studies have been recently reported applying optical coherence tomography (OCT) to image skin and cutaneous lesions. Materials and Methods: This article describes the use of vibrational OCT to image and noninvasively characterize the macromolecular components of the ECM of skin. Results: We report that the major macromolecular components of skin and scar can be identified noninvasively by their characteristic moduli calculated from measurements of the resonant frequency and tissue thickness. Moduli for fat (0.03 MPa), elastic tissue (0.8 MPa), skin (2 MPa), and scar (7 MPa) can be differentiated using images and measurements of the resonant frequency and the sample thickness obtained from OCT. Conclusions: Using vibrational OCT, it is possible to identify and map the location of the macromolecular components in skin and skin lesions. [ABSTRACT FROM AUTHOR]

In Cu-zeolite based selective catalytic reduction of NO x with NH 3 (NH 3 -SCR), Cu species (in particular Cu I ) solvated by NH 3 molecules are predicted theoretically to be highly mobile with their mobility being decisive for the NH 3 -SCR reactivity at low temperatures (<250 °C). Direct experimental observation of the Cu mobility after NH 3 solvation, however, has not been achieved yet. Here we show that complex impedance-based modulus spectroscopy, performed by following the corresponding dielectric relaxation processes at high frequencies (10 4 to 10 6 Hz), can be applied to monitor directly the dynamic local movement of Cu ions in zeolite catalysts under NH 3 -SCR related reaction conditions. Simultaneous in situ impedance and infrared spectroscopy studies, assisted by periodic DFT calculations with reliable van der Waals dispersion corrections, allowed us to identify the key factors determining the local dynamics of Cu ions in two representative Cu-zeolites, i.e. Cu-ZSM-5 and Cu-SAPO-34. The co-adsorption and interaction of NO and NH 3 on Cu II sites led to the formation of highly mobile Cu I species and NH 4 + intermediates, and, consequently, significantly enhanced local dynamics of Cu ions in both zeolite catalysts. The re-oxidation of Cu I , which is the rate-determining step of NH 3 -SCR reaction, was more favorable in Cu-SAPO-34 than in Cu-ZSM-5, which can be attributed to the close coupling of NH 4 + intermediate and Cu site promoting the formation of Cu II -NO 2 /NH 4 + . As a result, the overall local dynamics of Cu, largely determined by Cu I species, is less dependent on the NH 4 + intermediate in Cu-SAPO-34 than in Cu-ZSM-5. [ABSTRACT FROM AUTHOR]

Introduction: Typical practitioners choose from among only two to three products when selecting liners for their patients. A lack of comparable objective information about similarities and differences among elastomeric liner products may be part of the reason. Methods: Commonly used, commercially available polyurethane, silicone, and thermoplastic elastomer (TPE) liners were tested for their compressive, shear, tensile, and volumetric elasticities as well as their coefficients of friction (CoFs) and thermal conductivities. Results: Polyurethane and silicone liners tended to be stiffer in compression and shear than TPE liners. Fabric backings contributed primarily to increased tensile elasticity (and thus reduced pistoning). Polyurethane liners demonstrated relatively low CoFs, whereas silicone and TPE liners had higher CoFs and wider ranges. All materials tested were essentially incompressible. Thermal conductivities of all materials were comparable and similar to that of leather. Conclusions: Polyurethane liners are softer and less sticky than 16 years ago, and TPE liners have higher tensile stiffness than previously. A stiff fabric backing can increase tensile stiffness by more than 200%. Compressive stiffness may be used to characterize a liner's ability to flow. Elastomeric liners move heat almost exclusively via conduction. [ABSTRACT FROM AUTHOR]

Abstract An ultra-stable instrumented nano-indentation tester (UNHT, Anton Paar) was used to study extremely long (30,000 s) indentation creep of polymers. Total drift rate, measured on fused silica and sapphire samples, was less than 0.2 pm/s for up to 10 h, enabling collection of valid, low-uncertainty, long-term creep data - orders of magnitude longer than previously possible. Fits of the popular N -element Kelvin model to indentation creep data gave values of instant elastic modulus E 0 ∗ and infinite modulus E ∞ ∗ strongly dependent on the time-span of data fitted. Comparison with the long-term experimental data showed that the model was unable to use short term data to predict creep at the much longer times required by industry. A new analysis method is proposed to obtain a better estimate of the true value of infinite modulus, E ∞ ∗ , which is the simplest indicator of maximum dimensional change of polymeric material components subject to long-term stress. Highlights • We have shown that the UNHT system provides extremely good stability when located in a well-controlled environment: displacement drift <0.2 p.m./second • The ultra-stable experimental setup enables the collection of valid, low-uncertainty, long-term creep data (up to 30,000 s) - orders of magnitude longer than previously possible, to investigate the viscoelastic behaviour of polymer • The results set clear limits to the validity of long-term indentation creep data collection • The results set important limits to the prediction of viscoelastic behaviour using Kelvin model • We have proposed and demonstrated a new model to overcome the analysis limitations identified as a pragmatic attempt to predict the future behaviour of a material such as PS-3 from shorter duration test data and to provide results that are more independent of the creep test duration. • We made a number of recommendations to improve indentation creep testing including the selection of indenter geometry and loading cycles [ABSTRACT FROM AUTHOR]

Present work describes the mechanical behaviour of three virtual alloy systems comprising of matrix phase and W grains with fcc-bcc interface. The properties are evaluated for a composite tungsten heavy alloy. The compositions of the matrix phase have been considered similar to different tungsten heavy alloys (WHAs). The energy of the alloy systems decreases with increase in W contents. The lattice parameters of the matrix phase of WHAs are good agreement with those of the matrix phase of the virtual systems. The values of lattice constant, strength parameters (0.2 and 9% strain) and modulus increase with increase in W content. The nature of theoretical stress – strain curves of systems are similar to typical experimental ones. The addition of W increases the strength values and also shifts flow behaviour with higher strengths as function of strain. The yielding starts in typical WHAs in matrix phase only. [ABSTRACT FROM AUTHOR]

A mechanically interlocked supramolecule polyrotaxane (PR) was utilized as a functional additive to modify the hydrogen bonding (H-bonding) and cross-linking network of polybenzoxazine (PBa). Epoxide and hydroxyl groups at the terminal end of polycaprolactone grafted on CDs were chosen to investigate how these functional groups influence H-bonding, morphology, and mechanical properties of PBa matrix. Fourier transform infrared spectroscopy and differential scanning calorimetry results show evidence of successful manipulation of H-bonding and curing kinetics of PBa in the presence of the functionalized PR. After curing, epoxide functionalized PR (EPR) shows a strong interaction with PBa, leading to molecular level dispersion in PBa compared to PR with the hydroxyl functional group. By introducing only 4 wt% of EPR in PBa, the ductility and fracture toughness of PBa are greatly improved without a noticeable drop in Young's Modulus, which is attractive for aerospace and microelectronic applications. [Display omitted] [ABSTRACT FROM AUTHOR]

We study several properties of the modulus of order bounded disjointness-preserving operators. We show that, if T is an order bounded disjointness-preserving operator, then T and jTj have the same compactness property for several types of compactness. Finally, we characterize Banach lattices having b-AM-compact (resp., AM-compact) operators defined between them as having a modulus that is b-AM-compact (resp., AM-compact). [ABSTRACT FROM AUTHOR]