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Copper -doped Strontium Titanate (STO) with Copper filler percentages of 5% and 10% was prepared through a solid-state reaction method at high temperatures. The structural study of the materials was characterized by the X-ray diffraction technique and confirmed to be in the Cubic phase. Also, the surface morphology of the samples was studied by scanning electron microscopy. The impedance study of the samples was characterized by an LCR meter between the frequencies ranges 102-106 Hz. The exponential dependence of ac conductivity on frequency was confirmed where the value of ac conductivity increases with the rise in filler concentration from 5% to 10%. [ABSTRACT FROM AUTHOR]

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Many glasses exhibit the so-called indentation size effect (ISE), where the indentation hardness decreases with the maximum applied force. Here, we seek to uncover the connection between the ISE and strain rate in soda-lime silica (SLS) glass using micro-indentation. Two different loading protocols: constant loading rate (CLR), resulting in a nonlinear strain rate through the depth of indent, and a non-linear loading rate that gives a constant strain rate (CSR) with depth, are used to determine Hardness for six different strain rates and seven peak forces. A modified Bernhardt size effect law is then used to determine the extent of the ISE and load-independent hardness. We show that a small increase in micro-ductility, which can be achieved by either switching from a CLR to CSR protocol or by increasing the applied rates, can greatly reduce the extent of the ISE and slightly reduce the load-independent hardness. [ABSTRACT FROM AUTHOR]

Polycaprolactone (PCL) nanofibers are a promising material for biomedical applications due to their biocompatibility, slow degradation rate, and thermal stability. We electrospun PCL fibers onto a striated substrate with 12 μm wide ridges and grooves and determined their mechanical properties in an aqueous solution with a combined atomic force/inverted optical microscopy technique. Fiber diameters, D , ranged from 27 to 280 nm. The hydrated PCL fibers had an extensibility (breaking strain), ε max , of 137%. The Young's modulus, E , and tensile strength, σ T , showed a strong dependence on fiber diameter, D ; decreasing steeply with increasing diameter, following empirical equations E (D) = (4.3 ∙ 10 3 ∙ e − D 51 n m + 1.1 ∙ 10 2) MPa and σ T (D) = (2.6 ∙ 10 3 ∙ e − D 55 n m + 0.6 ∙ 10 2) MPa. Incremental stress-strain measurements were employed to investigate the viscoelastic behavior of these fibers. The fibers exhibited stress relaxation with a fast and slow relaxation time of 3.7 ± 1.2 s and 23 ± 8 s and these experiments also allowed the determination of the elastic and viscous moduli. Cyclic stress-strain curves were used to determine that the elastic limit of the fibers, ε elastic , is between 19% and 36%. These curves were also used to determine that these fibers showed small energy losses (<20%) at small strains (ε < 10%), and over 50% energy loss at large strains (ε > 50%), asymptotically approaching 61%, as E l o s s = 61 % · (1 − e − 0.04 * ε ). Our work is the first mechanical characterization of hydrated electrospun PCL nanofibers; all previous experiments were performed on dry PCL fibers, to which we will compare our data. [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.

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.

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.

Let 풫 and P ′ be 3-dimensional convex polytopes in R 3 and S ⊆ R 3 be a non-empty intersection of an open set with a sphere. As a consequence of a somewhat more general result it is proved that 풫 and P ′ coincide up to translation and/or reflection in a point if | ∫ P e - i ⁢ s ⋅ x ⁢ dx | = | ∫ P ′ e - i ⁢ s ⋅ x ⁢ dx | for all s ∈ S . This can be applied to the field of crystallography regarding the question whether a nanoparticle modelled as a convex polytope is uniquely determined by the intensities of its X-ray diffraction pattern on the Ewald sphere. [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 major problems disturbing the rheology of magnetic fluid are deformation of magnetic aggregate and destruction of field-induced structure, and this has caused major drawbacks to the rheological systems. The magnitude of the deformation is dependent on the percentage of the strain rate. To curtail the drawback and improve the rheology of the magnetic nanofluid, low strain rate application is required for fluid material testing. Henceforth, we examine the effect of strain rate and magnetic field on the rheological properties of zinc ferrite ferrofluid (FF) using oscillatory sweep test. The rheology of the fluid is examined in the absence and presence of magnetic field at strain amplitude 1%, 10%, 33%, and 100%. The magnitude of the deformation varied as the strain percentage is altered. Low deformation is formed at strain 1% and 10%, this results to the formation of improved and better rheological systemic function, and the rheological function is partially weakened at strain 33%, whereas structural deformation is higher at strain 100%. At strain 100%, the rheological system is largely weakened, but at strain 1%, the rheological system is enhanced. At low strain, high complex magnetoviscosity, low shear stress, low rotating magnetic field, and improved viscoelastic system are formed, but, at high strain application, low complex magnetoviscosity, high shear stress, speedy rotating magnetic field and poor viscoelastic system are formed. A steady-state flow is formed when low relaxation modulus is applied. At high strain, high rotation is formed, and this breaks the rotating magnetic field and destroys the magnetic structure, but at low strain, the rotation of the rotating magnetic field is low, and this protects the aggregates from destruction. The synthesized particles were ultra-sonicated and coated with oleic acid to curtail agglomeration of the particle. The storage modulus (G′) is largely greater than loss modulus, and this established the formation of dominant elastic structure. From TEM analysis, a spherically shaped nanoparticle is formed. The XRD analysis indicates the formation of cubic structure and Fe-phase in trivalent state. The hopping lengths in the tetrahedral site A and octahedral site B are 3.61 nm and 2.94 nm, while the lattice parameters a and c are 8.3298 Å and 13.7501 Å. [ABSTRACT FROM AUTHOR]

Various dimensional structured inorganic nanoparticles have different ways of improving mechanical properties of polymeric materials. However, there are limited studies on hybridization of different nanoparticles with different dimensional structures for optimal enhancement of mechanical properties of polymer matrix. Therefore, this study combined nanoparticles with 0D (barium titanate [BT]), 1D (carbon nanotubes [C]), and 2D (graphene [G] and boron nitride [BN]) to significantly promote the hardness, elastic modulus, tensile strength/modulus, heat deflection and Vicat softening temperature of polypropylene (PP) nanocomposites. The nanoparticles were surface functionalized to take care of good interfacial interaction with the PP matrix. The nanocomposites were fabricated via melt compounding techniques. Although all the developed nanocomposites showed enhanced mechanical and thermomechanical properties, the ones containing hybrid of carbon and ceramic nanoparticles with different dimensional structures showed superior responses. For instance, optimal hardness, elastic modulus, heat deflection and Vicat softening temperature of about 269.5 MPa, 2.9 GPa, 100.7 °C, and 160 °C were measured for the hybrid PP/3 wt%BNG/3 wt%BTC nanocomposite, which are about 239.4%, 77.7%, 19 °C, and 11 °C higher than that of the pure PP, respectively. The significant enhancement in the measured properties is attributed to effective mechanical interlocking and network structural hardening of the PP matrix. [ABSTRACT FROM AUTHOR]

The present paper describes an experimental investigation on mechanical properties of poly-lactic-acid (PLA) parts under compressive and flexural loading. The PLA parts are fabricated by fused deposition modelling (FDM) technique. In present work, effect of raster angle, raster width and infill density on strength and modulus of parts under compressive and flexural loading is studied. It is found that infill density affects compressive strength and modulus of parts significantly under compressive loading. Compressive properties increase with increase in infill density. Further, it is found that raster width and infill density significantly influence flexural strength and modulus. Flexural properties increase with increase in infill density, and decrease in decrease in raster width. Further, predictive models are developed for responses, and process parameters are optimized using genetic algorithm to maximize the responses. [ABSTRACT FROM AUTHOR]

Developing high-safety separators is a promising strategy to prevent thermal runaway in lithium-ion batteries (LIBs), which stems from the low melting temperatures and inadequate modulus of commercial polyolefin separators. However, achieving high modulus and thermal stability, along with uniform nanopores in these separators, poses significant challenges. Herein, the study presents ultrathin nanoporous aramid nanofiber (ANF) separators with high modulus and excellent thermal stability, enhancing the safety of LIBs. These separators are produced using a microfluidic-based continuous printing strategy, where the flow thickness can be meticulously controlled at the micrometer scale. This method allows for the continuous fabrication of nanoporous ANF separators with thicknesses ranging from 1.6 ± 0.1 µm to 2.7 ± 0.1 µm. Thanks to the double-side solvent diffusion, the separators exhibit controllably uniform pore sizes with a narrow distribution, spanning from 40 ± 5 nm to 105 ± 9 nm, and a high modulus of 3.3 ± 0.5 GPa. These nanoporous ANF separators effectively inhibit lithium dendrite formation, resulting in a high-capacity retention rate for the LIBs (80% after 240 cycles). Most notably, their robust structural and mechanical stability at elevated temperatures significantly enhances LIB safety under transient thermal abuse conditions, thus addressing critical safety concerns associated with LIBs., (© 2024 Wiley‐VCH GmbH.)

Mechanical adaptation of tissue engineering scaffolds is critically important since natural tissue regeneration is highly regulated by mechanical signals. Herein, we report a facile and convenient strategy to tune the modulus of waterborne biodegradable polyurethanes (WBPU) via cross-linking manipulation of phase separation and water infiltration for constructing mechanically adaptable tissue engineering scaffolds. Amorphous aliphatic polycarbonate and trifunctional trimethylolpropane were introduced to polycaprolactone-based WBPUs to interrupt interchain hydrogen bonds in the polymer segments and suppress microphase separation, inhibiting the crystallization process and enhancing covalent cross-linking. Intriguingly, as the crosslinking density of WBPU increases and the extent of microphase separation decreases, the material exhibits a surprisingly soft modulus and enhanced water infiltration. Based on this strategy, we constructed WBPU scaffolds with a tunable modulus to adapt various cells for tissue regeneration and regulate the immune response. As a representative application of brain tissue regeneration model in vivo, it was demonstrated that the mechanically adaptable WBPU scaffolds can guide the migration and differentiation of endogenous neural progenitor cells into mature neurons and neuronal neurites and regulate immunostimulation with low inflammation. Therefore, the proposed strategy of tuning the modulus of WBPU can inspire the development of novel mechanically adaptable biomaterials, which has very broad application value., (© The Author(s) 2024. Published by Oxford University Press.)

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.

A simple method for determining the effective elastic modulus of wavy single-wall carbon nanotubes (SWCNTs) is presented in this paper. The effective modulus of curved SWCNTs is derived using Castigliano’s theorem. The effect of curvature on the effective modulus is studied. This method is verified by finite element analysis (FEA). The distributions of effective moduli are studied by Monte Carlo simulation. The effective modulus of a general wavy SWCNT is derived by considering the SWCNT as a number of curved SWCNT sections.

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.

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]

Purpose: Osteoporosis is a bone disease associated with enhanced bone loss, microstructural degeneration, and fracture‐risk. Finite element (FE) modeling is used to estimate trabecular bone (Tb) modulus from high‐resolution three‐dimensional (3‐D) imaging modalities including micro‐computed tomography (CT), magnetic resonance imaging (MRI), and high‐resolution peripheral quantitative CT (HR‐pQCT). This paper validates an application of voxel‐based continuum finite element analysis (FEA) to predict Tb modulus from clinical CT imaging under a condition similar to in vivo imaging by comparing with measures derived by micro‐CT and experimental approaches. Method: Voxel‐based continuum FEA methods for CT imaging were implemented using linear and nonlinear models and applied on distal tibial scans under a condition similar to in vivo imaging. First, tibial axis in a CT scan was aligned with the coordinate z‐axis at 150 μm isotropic voxels. FEA was applied on an upright cylindrical volume of interests (VOI) with its axis coinciding with the tibial bone axis. Voxel volume, edge, and vertex elements and their connectivity were defined as per the isotropic image grid. A calibration phantom was used to calibrate CT numbers in Hounsfield unit to bone mineral density (BMD) values, which was then converted into calcium hydroxyapatite (CHA) density. Mechanical properties at each voxel volume element was defined using its ash‐density defined on CT‐derived CHA density. For FEA, the bottom surface of the cylindrical VOI was fixed and a constant displacement was applied along the z‐direction at each vertex element on the top surface to simulate a physical axial compressive loading condition. Finally, a Poisson's ratio of 0.3 was applied, and Tb modulus (MPa) was computed as the ratio of average von Mises stress (MPa) of volume elements on the top surface and the applied displacement. FEA parameters including mesh element size, substep number, and different tolerance values were optimized. Results: CT‐derived Tb modulus values using continuum FEA showed high linear correlation with the micro‐CT‐derived reference values (r ∈ [0.87 0.90]) as well as experimentally measured values (r ∈ [0.80 0.87]). Linear correlation of computed modulus with their reference values using continuum FEA with linear modeling was comparable with that obtained by nonlinear modeling. Nonlinear continuum FEA‐based modulus values (mean of 1087.2 MPa) showed greater difference from their reference values (mean of 1498.9 MPa using micro‐CT‐based FEA) as compared with linear continuum methods. High repeat CT scan reproducibility (intra‐class correlation [ICC] = 0.98) was observed for computed modulus values using both linear and nonlinear continuum FEA. It was observed that high stress regions coincide with Tb microstructure as fuzzily characterized by BMD values. Distributions of von Mises stress over Tb microstructure and marrow regions were significantly different (p < 10–8). Conclusion: Voxel‐based continuum FEA offers surrogate measures of Tb modulus from CT imaging under a condition similar to in vivo imaging that alleviates the need for segmentation of Tb and marrow regions, while accounting for bone distribution at the microstructural level. This relaxation of binary segmentation will extend the scope of FEA application to assess mechanical properties of bone microstructure at relatively low‐resolution imaging. [ABSTRACT FROM AUTHOR]

This study aimed at searching the predictive values of testicular shear wave elastic modulus in testicular functions for varicocele patients. This was a prospective case–control study. We divided the participants into two groups: varicocele group and control group, the latter recruited men with normal physical examination, testicular ultrasound, semen and endocrine results. A total of 97 participants were enrolled: 67 patients in varicocele group, 30 participants in control group. There were statistical differences in left testicular shear wave elastic modulus, left testicular volume, testicular atrophy index, total sperm count, sperm concentration, sperm viability and testosterone between the two groups, between different grades in varicocele group, between different periods in varicocele group. Left testicular shear wave elastic modulus was inversely correlated with total sperm count, sperm concentration, sperm viability and testosterone. Left testicular shear wave elastic modulus cut‐off was calculated as 5.235, 5.130, 4.640 and 5.310 Kpa using ROC curve according to the abnormalities of total sperm count, sperm concentration, sperm viability and testosterone. When the left testicular shear wave elastic modulus was higher than these values, the corresponding parameter was more likely to be abnormal. Testicular shear wave elastic modulus has predictive values in testicular functions for varicocele patients. [ABSTRACT FROM AUTHOR]

In this paper, bio-based semi-aromatic high-temperature polyamide PA5T/56 was synthesized from bio-based monomer glutamine. The micro and macro physicochemical properties of PA5T/56 were studied by Materials Studio software, Universal Testing Machine and Impact Testing Machine and other software and instruments, and the effect of PA5T content on its properties was explored. The results showed that the Poisson's ratio and modulus of PA56 molecule were the largest, PA5T molecule was the smallest, and PA56T molecule was between the two, indicated that the addition of PA5T molecule enhances the overall mechanical properties; With the increase in PA5T content, the tensile strength and bending strength of PA5T/56 increases, while the elongation at break and impact strength decreases, the density of PA5T/56 increases first and then decreases, and the oil absorption rate and water absorption rate of PA5T/56 decrease gradually; Moreover, PA5T/56 has excellent solvent resistance, it is insoluble in conventional organic solvents and only soluble in concentrated sulfuric acid and trifluoroacetic acid; With the extension of soaking time, the tensile strength and bending strength of PA5T/56 decrease, while the impact strength of PA5T/56 increases first and then decreases. [ABSTRACT FROM AUTHOR]

In the present work, an experimental investigation is performed to study the influence of process parameters on mechanical properties of tetra‐anti‐chiral auxetic structures manufactured by material extrusion (ME) technique of additive manufacturing (AM). Process parameters namely layer height, print speed, and print temperature are considered, while responses are compressive strength (σ), modulus (E), and specific energy absorption (SEA). Specimens of acrylonitrile‐butadiene‐styrene (ABS) polymer are fabricated and then tested under compressive loading. From the experimental results, it is observed that all process parameters significantly influence the mechanical properties of the structure. Scanning electron microscope (SEM) is used to study microstructural defects of the tested specimen. To maximize the responses, optimization of process parameter is performed using desirability function approach. Regressive models are developed to predict the mechanical properties. [ABSTRACT FROM AUTHOR]

In the current article, Kolarik model is progressed for the tensile modulus of a polymeric system containing dispersed halloysite nanotubes (HNT) and adjacent interphase section. The progressive model correlates the nanocomposite's modulus to HNT concentration (volume fraction and weight percentage), the extents of HNT and nearby interphase section in addition to the densities of polymer medium and HNT. The productions of the progressive model are linked to the tentative results and the influences of all variables on the modulus of system are justified. The modulus of system reduces as HNT radius increases, but HNT weight percentage directly controls the nanocomposite's modulus. The modulus of samples maximizes by 47% by the deepest interphase section of 20 nm establishing a straight link among nanocomposite's modulus and interphase thickness. The increment of polymer matrix density improves the modulus of samples, but there is an opposite relation between the modulus of system and HNT density. Furthermore, the calculations exactly match to the experimental facts of numerous examples representing the accurateness of the progressed model. [ABSTRACT FROM AUTHOR]

Filtration based processing of nanotube and polymer-nanotube dispersions is used to create polymer and nano-filler hybrid materials. The composite morphology consists of two layers: (1) a region where polymer chains have direct matrix interaction with the nano-fillers and (2) a nano-filler rich region excluded from matrix interactions. The experimental work here demonstrates the processing of this hybrid material using polyacrylonitrile (PAN) and single-wall carbon nanotubes (SWNT) at various PAN/SWNT weight concentrations. Mechanical analyses were performed to evaluate effective contributions from the SWNT in each of the defined layers. The region of high matrix-filler interactions exhibits blending behavior with material properties following suit. As a result, mechanical performance is consistent and begins to exceed theoretical predictions derived from Halpin–Tsai calculations. Tensile strength and modulus reached values as high as 60 MPa and 7.7 GPa, respectively, surpassing the performance of neat nano-filler (36 MPa, 3.9 GPa) and neat polymer matrix (44 MPa, 2.0 GPa) films. Additionally, the measurement of electrical properties shows that the blended polymer-SWNT region exhibits conductivity comparable to the filler. The results of this work suggest that blending polymers and nano-fillers is possible and may facilitate the production of materials with comparatively high mechanical performance and electrical conductivities. [ABSTRACT FROM AUTHOR]

This paper reported an investigation on the effect of sample thickness on tensile properties of polyethylene (PE). Through the analysis of tensile tests of PE samples with different thickness, the thickness could generate a great influence on the strength, strain and tensile modulus of PE. However, there was no effect on the yield absorption energy per unit area. In the current design of plastic products, there have been hidden dangers with the tensile properties of PE materials and the thickness of products as two independent parameters. [ABSTRACT FROM AUTHOR]

Cement stabilization is one of the chemical stabilization techniques carried out to improve sabkha soil engineering properties. Cement can be mixed with sabkha at natural water content. However, there is a lack of information concerning the dynamic properties of cemented sabkha. Therefore, this study's primary purpose is to determine the dynamic properties of cemented sabkha, at cement content of 5% and 10%, which satisfied static requirements and compare it with untreated sabkha in literature. The tests were carried out using the cyclic triaxial test at several effective stresses and cyclic stress ratios (CSR). The averages of shear modulus of cemented sabkha of 5% cement are 38, 32, and 21 MPa for cyclic stress ratio of 0.15, 0.35, and 0.65, respectively; they are 85, 45, and 43 MPa for 10% cement. Furthermore, the averages of damping of 5% cement are 0.03, 0.016, and 0.014 for CSR of 0.15, 0.35, and 0.65, respectively; they are 0.027, 0.012, and 0.01 for 10% cement. The results indicate that the increasing cement content to sabkha from 5 to 10% decreases the shear strain ratio by 0.05, 0.04, and 0.22 for CSR of 0.15, 0.35, and 0.65, respectively. For CSR of 0.15, the change in cement content from 5 to 10% leads to increased shear modulus by 1.4 to 3 times of shear modulus of untreated sabkha; the shear modulus ratio of cemented sabkha to shear modulus to sabkha increases with the increasing number of cycles. The cement content of 5 and 10% leads to a decrease in the normalized damping ratio of cemented sabkha to damping ratio of sabkha with a range from 0.55 to 0.85. [ABSTRACT FROM AUTHOR]

Robotic Automated Fiber Placement (R-AFP) technology was developed to manufacture composite laminates by placing carbon fiber thermoset towpregs, obtained by impregnating 12 K high-strength grade carbon fibers in an epoxy resin system. In order to avoid placement induced defects, a thermographic scanning technique was implemented for on-line quality monitoring of the R-AFP process. The thermal analysis proved to be an effective and quick approach for the real-time detection of deposition defects generated during. The R-AFP process was performed by applying a constant pressure through the compaction roller; different pressure values were investigated. The effect of the resin weight fraction and compaction pressure on the mechanical properties applied by the deposition head during R-AFP of cross-ply laminates was studied. The reduction of the tensile strength and the increase of the elastic modulus with decreasing pressure of the compaction roller was observed. Furthermore, the values of ultimate tensile strength and elastic modulus decrease as the resin content increases. Finally, the three-dimensional topography of surface fracture of tensile samples was investigated by means of the optical and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

Elaborating an instrumented nanoindentation is to exercise non-destructive 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.

The incorporation of stiff nano-additives (such as graphene) into a relatively soft polymer material (such as epoxy) usually leads to an improvement in elastic properties (i.e., Young's modulus) at the expense of fracture properties (i.e., tensile strength and toughness). Despite over a decade of research in polymer nanocomposites, we still lack a clear understanding of their structure-property relationships, which limits us from enhancing both elastic and fracture properties concurrently. Here, we performed large-scale reactive molecular dynamics simulations to study the deformation and fracture of model graphene/epoxy systems under uniaxial tension. A computationally efficient reactive force field was developed for graphene-epoxy system, allowing covalent bond formation, and breaking, which is crucial to model cross-linking in model epoxy as well as fracture. It was found the mechanical properties of the nanocomposite are very sensitive to the strength of the graphene-epoxy interface. As expected, elastic modulus increases with the interfacial strength. However, there appears to be an optimal interfacial strength to enhance the tensile strength and toughness. This is due to stress concentration occurring near the graphene edges at high interfacial strength, which leads to premature fracture. We show that by appropriately selecting an intermediate interface strength, one can simultaneously improve the ultimate tensile strength, toughness and the Young's modulus of the nanocomposite epoxy at ultra-low (∼0.2 % by weight) loading fraction of graphene additives. Our findings highlight the critical importance of properly engineered additive-matrix interfacial strength to develop high-performing polymer nanocomposites that are concurrently stiff, strong as well as tough. [Display omitted] • We designed a computationally efficient, pair-wise, reactive potential to model a coarse-grained epoxy/graphene system. • Consistent with experiments, neat epoxy samples exhibit brittle fracture in our molecular dynamics simulations. • Advantageous mechanical properties are achieved not at the strongest graphene/epoxy interface but at moderate strengths. • We observed that overly strong interfaces led to a significant increase in edge cavitation and premature failure. • Interfacial strength must be carefully balanced to simultaneously enhance elastic and fracture properties in nanocomposites. [ABSTRACT FROM AUTHOR]

This research explores the fabrication of mullite precursor powder utilizing the sol-gel process at low temperatures. Silicon tetraethoxide (Si(C 2 H 5 O) 4) and aluminum nitrate nonahydrate (Al(NO 3) 3.9H 2 O) were employed as the sources of SiO 2 and Al 2 O 3 oxides, respectively. Various analytical techniques, such as Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), dilatometry, differential thermal analysis (DTA), and X-ray powder diffractometer (XRD), were utilized to investigate the formation and crystallization of the amorphous powder. The microstructure of specimens sintered at 1600 °C for 1 h was examined utilizing scanning electron microscopy (SEM). Measurements of hardness (HV) and coefficient of thermal expansion (CTE) were conducted on mullite samples heated to 1600 °C and then cooled, revealing an increase in HV from 888 to 1000 HV as the sintering temperature rose from 1500 to 1600 °C. The CTE of mullite within the temperature range of 50–1300 °C was determined as 5.23 × 10−6/°C. Additionally, the dielectric and electrical characterization of mullite was analyzed utilizing complex impedance spectroscopy at a frequency of 0.1–106 Hz and conductivity measurements over a temperature range of 40–400 °C. The real and imaginary parts of the dielectric permittivity exhibited frequency-dependent and temperature-dependent behaviors. Significantly, the observed variations in the imaginary component of the modulus and impedance maximum frequency point to a relaxation process that is not Debye-type, with calculated activation energies (E a) consistent across different methods. • Synthesis and characterization of mullite ceramics via sol-gel method. • Thermal analysis reveals distinct breakdown processes. • Dilatometric analysis shows shrinkage and phase formation during heat treatment. • Increased bulk density and hardness with higher sintering temperatures. • Impedance spectroscopy and dielectric analysis show non-Debye relaxation and thermally activated conductivity. [ABSTRACT FROM AUTHOR]

The posterior face of the cornea consists of the corneal endothelium, a monolayer of cuboidal cells that secrete and attach to Descemet's membrane, an exaggerated basement membrane. Dysfunction of the endothelium compromises the barrier and pump functions of this layer that maintain corneal deturgesence. A large number of corneal endothelial dystrophies feature irregularities in Descemet's membrane, suggesting that cells create and respond to the biophysical signals offered by their underlying matrix. This review provides an overview of the bidirectional relationship between Descemet's membrane and the corneal endothelium. Several experimental methods have characterized a richly topographic and compliant biophysical microenvironment presented by the posterior surface of Descemet's membrane, as well as the ultrastructure and composition of the membrane as it builds during a lifetime. We highlight the signaling pathways involved in the mechanotransduction of biophysical cues that influence cell behavior. We present the specific example of Fuchs' corneal endothelial dystrophy as a condition in which a dysregulated Descemet's membrane may influence the progression of disease. Finally, we discuss some disease models and regenerative strategies that may facilitate improved treatments for corneal dystrophies.

We reveal the influence of non-magnetic Al3+ ion on magnetic, optical and electronic properties of KBiFe 2 O 5. Al doped KBiFe 2-x Al x O 5 (x = 0, 0.2, 0.4) are synthesized by citrate combustion method. All the samples are found to be crystalized in monoclinic structure with P 2/ c space group. With Al doping, the grain size of the samples is reduced however, Fe ions maintain its +3 state. A mere difference in the low temperature zero field cooling and field cooling curve discards the multiple magnetic phases at low temperature, however, with Al, an improved magnetic moment is detected in the magnetic isotherms. A schematic model is adopted to explain the enhanced magnetization. Furthermore, the magnetic anomaly around the dielectric transition (760–780 K) depicts an existence of magnetoelectric coupling in all the samples. The optical band gap is reduced from 1.73 eV to 1.69 eV with Al doping. Extensive dielectric and electric modulus analysis is carried out to explore the conduction as well as relaxation process in the parent and Al doped system. The activation energy estimated from the electric modulus is (0.412 ± 0.021) eV for x = 0 and (0.370 ± 0.025) eV for x = 0.2 respectively but surprisingly, Al doping with x = 0.4 shows a completely different relaxation mechanism. Moreover, the frequency dependent ac conductivity is also explained and agrees well with the electric modulus data. Magnetic characterization of Al doped KBiFe 2 O 5. [Display omitted] • We prepare the Al doped KBiFe 2 O 5 through citrate combustion method. • Low band gap of ∼1.73 eV–1.69 eV, is favorable for solar cell and photocatalyst. • Al improves the magnetic moment with an existence of magnetoelectric coupling. • Conduction process is mainly governed by CBH and polaron hopping model. [ABSTRACT FROM AUTHOR]

The Li 4 FeSbO 6 compound was prepared by solid state route at high temperature. It crystallizes in the monoclinic system with space group C 2/ m and cell parameters a = 5.1711(2) Å, b = 8.9406(3) Å, c = 5.1687(2). The purity and morphology were investigated, the sample is formed of aggregates of different sizes and each aggregate consists of particles widely dispersed in size and shape. Ultraviolet–visible spectroscopy was used to determine information about electronic transitions. Three absorption bands were observed and attributed to spin-forbidden electronic transitions of Fe3+(d5) in an octahedral field. The band gap obtained from Ultraviolet–visible spectroscopy is about 2.01 eV. The dielectric properties were investigated in the frequency range of 10 Hz to 1 MHz at different temperatures from 303 K to 673 K. The impedance spectroscopy confirmed the grains and grain boundaries effects. The complex permittivity was found to have two contributions, one dipolar and the other conductive. The relaxation time of the dipolar contribution matches well with the Maxwell-Wagner relaxation time, indicating that the sample is electrically inhomogeneous. The ionic conductivity of Li+ ions was attributed to the bulk resistance of Li 4 FeSbO 6. The conduction mechanism in the bulk material Li 4 FeSbO 6 was studied with Jonscher's law which confirmed the presence of conductive pathways in the material. The hopping frequency was evaluated from the modulus, the activation energy obtained is E a = 0.57(3) eV, similar to that determined from the impedance analyzes. The conduction pathways of Li+ ions and the corresponding migration barrier energy values were calculated by the Bond Valence Path Analyzer. The results suggest that Li+ ions mainly diffuse along a 3D path with a migration barrier of 0.57 eV, which is in perfect agreement with the activation energy determined from the conductivity of bulk Li 4 FeSbO 6. [Display omitted] • Ionic conductivity is determined by combination of permittivity, impedance and modulus. • Permittivity analysis reveals both dipolar and conductive contributions. • Relaxation time of the dipolar component aligns with Maxwell-Wagner relaxation. • Grain and grain boundary effects are confirmed by impedance and modulus spectroscopy. • Bulk conductivity activation energy matches the migration barrier for Li ions along a 3D path. [ABSTRACT FROM AUTHOR]

[Display omitted] • Improved ε r and ac-conductivity of Sn-modified lead germanate. • Temperature-dependent dielectric and electrical properties. • Decreased E a and revealed conduction mechanism of PGSO at higher temperatures. • NTCR behavior of PGSO for high-sensitivity thermistors and sensors. • Thermistor constant (β) of 1662 K in 250 °C-300 °C. A solid-state reaction was used to synthesize the tin modified lead germanate: Pb 5 Ge 1.5 Sn 1.5 O 11 (PGSO). The composition was modified to enhance its dielectric and electrical properties. The PGSO sample was characterized by various analytical techniques, such as XRD for structural analysis and FTIR for additional structural information. The surface morphology and features of PGSO were examined by SEM, while its band gap was determined by UV–Visible-Diffuse Reflectance Spectroscopy absorbance spectra. The impedance, dielectric behaviour, AC conductivity, activation energy, and modulus of PGSO were also studied. The temperature dependence of the dielectric constant and AC conductivity showed an increase with increasing temperature. The electrical resistivity (R) decreased as the temperature increased from 100 °C to 300 °C, exhibiting a NTCR behaviour for PGSO sample, which could be applied as a high temperature thermistor and sensor, and could be used to fabricate a high sensitivity, low-cost thermistor. The circuit parameters such as bulk resistance (R b), frequency factor (n), and bulk capacitance (C b) were determined by fitting the Nyquist plot using an equivalent circuit (CQR)(CR). [ABSTRACT FROM AUTHOR]