Search

Filler content in dental composites is credited for affecting its physical and mechanical properties. This study evaluated the correlation between the filler percentage and strength, modulus, shrinkage stress, depth of cure, translucency and radiopacity of commercially available high- and low-viscosity dental composites. Filler weight percentage (wt%) was determined through the burned ash technique (800 °C for 15 min). Three-point bend flexural strength and modulus were measured according to ISO 4049 with 2 mm × 2 mm × 25 mm bars. Shrinkage stress was evaluated using a universal testing machine in which composite was polymerized through two transparent acrylic rods 2 mm apart. Shrinkage was measured from the maximum force following 500 s. The translucency parameter (TP) was measured as the difference in color (ΔE00) of 1 mm thick specimens against white and black tiles. The depth of cure was measured according to ISO 4049 in a cylindrical metal mold (4 mm diameter) with a 10 s cure. Radiopacity was measured by taking a digital X-ray (70 kVp for 0.32 s at 400 mm distance) of 1 mm thick specimens and comparing the radiopacity to an aluminum step wedge using image analysis software. The correlation between the filler wt% and properties was measured by Pearson's correlation coefficient using SPSS. There was a positive linear correlation between the filler wt% and modulus (r = 0.78, p < 0.01), flexural strength (r = 0.46, p < 0.01) and radiopacity (r = 0.36, p < 0.01) and negative correlation with translucency (r = −0.29, p < 0.01). Filler wt% best predicts the modulus and strength and, to a lesser extent, the radiopacity and translucency. All but two of the high- and low-viscosity composites from the same manufacturer had statistically equivalent strengths as each other; however, the high-viscosity materials almost always had a statistically higher modulus. For two of the flowable composites measured from the same manufacturer (3M and Dentsply), there was a lower shrinkage stress in the bulk-fill version of the material but not for the other two manufacturers (Ivoclar and Tokuyama). All flowable bulk-fill composites achieved a deeper depth of cure than the flowable composite from the same manufacturer other than Omnichroma Flow Bulk. [ABSTRACT FROM AUTHOR]

We look at a momentum map associated with the Heisenberg group. We show that the cocycle associated with its momentum mapping is the value of a modulus of an associated coadjoint orbit. [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]

This study introduces the development of a novel bio-nano composite via the dispersion of cellulose nanofibers (CNF) in epoxy. The surface of cellulose nanofibers was functionalized using a two-step chemical treatment to enhance dispersion. The interfacial characteristics of CNF were improved using alcohol/acetone treatments. The modified CNF (M-CNF) demonstrated enhanced compatibility and improved dispersion in the epoxy matrix as evidenced by scanning electron microscopy. Based on the analysis of X-ray diffraction patterns, M-CNF did not disturb the crystalline phases at the interface. The results of mechanical testing showed that M-CNF worked as a reinforcing agent in the bio-nano composite. The flexural modulus increased from 1.4 to 3.7 GPa when M-CNF was introduced. A similar trend was observed for tensile strength and impact resistance. The optimum performance characteristics were observed at M-CNF of 0.6%. At higher dosages, some agglomeration was observed, which weakened the interfacial properties. This study promotes sustainability and resource conservation while offering CNF as a sustainable reinforcing agent to develop bio-nano composites. [ABSTRACT FROM AUTHOR]

This study introduces an advanced finite element model for the light weight deflectometer (LWD), which integrates contact mechanics with fully coupled models. By simulating LWD tests on granular soils at various saturation levels, the model accurately reflects the dependence of the LWD modulus on dry density, water content, and effective stress. This model addresses and overcomes the limitations of previous finite element models for this specific problem. Simultaneously, this research presents the first experimentally validated fully coupled contact impact model. Furthermore, the research provides a comparative assessment of elastoplastic and nonlinear elastic models and contrasts an enriched node-to-segment method (developed in this study) with the more precise mortar technique for contact mechanics. These comparisons reveal unique advantages and challenges for each method. Moreover, the study underscores the importance of careful application of the LWD modulus, emphasising the need for sophisticated tools to interpret soil behaviour accurately.

Dynamic cone penetrometer (DCP) has been commonly used for the evaluation and quality control/assurance of soils before, during, and after construction in civil engineering projects. This test equipment has been increasingly used for geotechnical engineering applications but not yet been used to evaluate lightweight cellular concrete (LCC) as a backfill material. This technical note reports laboratory and field DCP tests to evaluate the properties of LCC. To establish the relationship between DCP data and other material properties, unconfined compressive strength and California bearing ratio (CBR) tests were conducted on this material. The test results showed that the measured unconfined compressive strength and CBR of LCC increased as its density increased. The DCP indices (DCPI) for the LCC specimens at different densities were almost constant with the penetration depth. This technical note proposes the correlations between the DCPI and the unconfined compressive strength and CBR, which may be used for future applications. [ABSTRACT FROM AUTHOR]

Ca and Cs doped barium titanate lead-free ceramic with the formula Ba 0.75 Ca 0.2 Cs 0.05 TiO 3 has been prepared by the solid-state reaction method. X-ray diffraction (XRD) confirms the crystallization of the sample in a tetragonal structure with a P 4 mm space group. The phase purity and grain morphology were evaluated using X-ray diffraction and scanning electron microscopy (SEM). The material exhibits a primary phase of Ba0.75Ca0.2Cs0.05TiO3 with a minor secondary phase of BaO 2 , and the average grain size is determined to be 1.66 μm. Using non-destructive complex impedance spectroscopy (CIS), we extensively studied the electrical behavior, including complex impedance (Z*), complex modulus (M*), electrical conductivity, and relaxation mechanisms, of Ba 0.75 Ca 0.2 Cs 0.05 TiO 3 over a wide temperature (85 K–290 K) and frequency range. The ac conductivity analysis reveals that the dominant conduction mechanism is the non-overlapping small polaron tunneling (NSPT) model. The impedance analysis indicates a single semi-circle in the real and imaginary parts, suggesting a single relaxation mechanism. Additionally, the activation energy was calculated to be approximately 0.0489 eV. These findings contribute to the understanding of the structural and electrical properties of Ba 0.75 Ca 0.2 Cs 0.05 TiO 3 , highlighting its potential applications in electronic devices such as capacitors, thermistors, and ferroelectric random access memories (FRAMs). [ABSTRACT FROM AUTHOR]

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]

This study focuses on the preparation of lithium diphosphate compound LiCeP2O7 via conventional solid-state reaction. Analysis using the Rietveld refinement of the X-ray diffraction pattern reveals that the sample adopts a monoclinic structure at room temperature. Surface morphology is further examined through SEM. Additionally, complex impedance and electrical modulus spectroscopy analyses indicate the presence of non-Debye-type relaxation behavior. The direct current (dc) conductivity exhibits Arrhenius behavior, with activation energies of 0.94 eV in region I and 1.21 eV in region II, indicating thermally activated lithium-ion conduction. The thermal behavior of the exponent parameter "s" suggests a transition in the conduction mechanism from large polaron tunneling to small polaron tunneling that occurs at 533 K. Electric modulus studies confirm that the ionic conduction relaxation process is thermally activated and exhibits a spread of relaxation time. Understanding the ionic conduction mechanism will facilitate the design of efficient ionic conductors for battery applications. [ABSTRACT FROM AUTHOR]

The rheological characteristics of manganese zinc (Mn-Zn) ferrite magnetic nanofluid synthesized using co-precipitation technique were examined in the absence and presence of magnetic fields. The research formulates required conditions needed for the formation of a gelly-like structure. The impact of magnetic field and temperature on the rheological properties of Mn-Zn ferrite ferrofluid is investigated. When a magnetic field was applied, higher magnetoviscoelasticity and magnetoviscosity were formed. Other rheological parameters such as damping factor which is crucial for regulating and restricting vibrations in a system was also analyzed. A stiff, gel-like structure is produced when a magnetic field is applied, and the gel-like quality grows as the magnetic field increases; when the magnetic field is removed, the gel-like and rigidity of the structure is lost. At low temperatures, the liquid phase is dominated by solid-like particles, whereas at high temperatures, the liquid-like structure is dominant. This study reveals the conditions required for the creation of high viscous effect and the viscoelastic behavior induced by the field offers important insights for optimizing the Mn-Zn ferrite ferrofluid for a range of applications. Other criterial for gel-like structure formation such as low torque and deflection angle of the ferrofluid were also established. [ABSTRACT FROM AUTHOR]

The relatively low melting point of a traditional Si bonding layer limits the upper servicing temperature of environmental barrier coatings (EBC). To explore suitable high temperature bonding layers and expedite the development of EBC, first-principles calculation was used to evaluate the mechanical properties and thermal conductivity of HfSi2, HfSi, Hf5Si4, Hf3Si2, and Hf2Si with much higher melting points than that of Si. Among them, HfSi2 has the lowest modulus capable of good modulus matching with SiC substrate. In addition, these Hf-Si compounds have much lower high temperature thermal conductivity with Hf2Si being the lowest of 0.63 W m−1 K−1, which is only half of Si, capable of improved heat insulation. [ABSTRACT FROM AUTHOR]

Physical layer secret key generation is a novel research direction that has attracted many researchers in recent years due to its low computational capacity and ability to obtain information-theoretic security. In this paper, we propose two methods based on the modulus and the real and imaginary parts of the channel impulse response (CIR) matrix to generate a secret key between two legitimate devices in massive Multiple-Input Multiple-Output (MIMO) wireless communication systems. For these methods, the legitimate devices first estimate the channel by using a probing signal to find their CIRs. Next, the CIR matrices are transformed into single-row vectors. The first method uses a simple quantization algorithm to convert the modulus of the complex components of the vector into the final key bit sequence. The second method uses the same quantization algorithm to transform the highest points of the real and imaginary parts into two sequences. The XOR operation between these two sequences generates the final key sequence. The key samples with different lengths generated from the system can be assessed by the most crucial performance metric of randomness according to the National Institute of Standards and Technology (NIST) version 800-22REV1A. The numerical results show that the first method has a higher pass rate and more randomness than the second method. Moreover, our proposed methods are superior to existing methods.

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]

Copyright of South Architecture / Nanfang Jianzhu is the property of South Architecture Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Throughout all the countries in the world, including Vietnam, nations with well-established mining industries have undertaken extensive research on the stability of rock masses when constructing underground tunnels in varied geological conditions. The present study aims to provide a comprehensive overview of the risk assessment related to rock masses during the construction of pit lines in mining operations. Consequently, the standing time of unsupported tunnels is assessed based on different values of the strength index and deformation characteristics of the rock mass. The objective was to perform both experimental and theoretical investigations to analyse how the stand-up time of rock masses surrounding a tunnel affects the unsupported span. The analyses were based on considering the rock parameters, including strain modulus; geological strength index; and allowable displacement values, and consideration of hereditary creep properties. By examining tunnels excavated in rock strata, it was concluded that varying geological strength index values resulted in distinct creep behaviour in the surrounding rock masses. Thus, it was reasonable to compute the unsupported span and stand-up time of tunnels. The research revealed that permissible displacements are significantly influenced by the types of rock materials surrounding the tunnel structure. Recognising the significance of time, the authors introduce a more practical interpretation and evaluation of the stability of rock masses, thus enhancing the precision of commonly available models. [ABSTRACT FROM AUTHOR]

A series of laboratory and large-scale field model footing tests were conducted to assess the modulus and stress distribution behavior of a clayey soil foundation, both with/without geogrid reinforcement, deviating from the conventional approach of evaluating the strength performance, such as bearing capacity. The modulus was evaluated at three settlement ratios of s/B = 1, 3, and 5%, while the stress distribution angle α was estimated at three applied surface pressures of 234 kPa, 468 kPa, and 936 kPa. The results indicated a stiffer load-settlement response when geogrid reinforcement was included. The modulus of reinforced clayey soil remained nearly constant for test sections with the same reinforced ratio, with the modulus improvement increasing as the reinforced ratio (Rr) increased. The modulus improvement also increased with the settlement ratio (s/B). These results demonstrated that the stress distribution improvement decreased as the surface pressure increased. Generally, both the modulus and stress distribution improvement exhibited an increase with an increase in the tensile modulus of the geogrid. While laboratory model tests consistently provided a higher improvement in the modulus than large-scale field model tests in this study due to a higher reinforced ratio, the stress distribution improvement was similar for both. [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]

Interfaces of glassy materials such as thin films, blends, and composites create strong unidirectional gradients to the local heterogeneous dynamics that can be used to elucidate the length scales and mechanisms associated with the dynamic heterogeneity of glasses. We focus on bilayer films of two different polymers with very different glass transition temperatures (Tg) where previous work has demonstrated a long-range (~200 nm) profile in local Tg(z) is established between immiscible glassy and rubbery polymer domains when the polymer-polymer interface is formed to equilibrium. Here, we demonstrate that an equally long-ranged gradient in local modulus ...(z) is established when the polymer-polymer interface (≈5 nm) is formed between domains of glassy polystyrene (PS) and rubbery poly(butadiene) (PB), consistent with previous reports of a broad Tg(z) profile in this system. A continuum physics model for the shear wave propagation caused by a quartz crystal microbalance across a PB/PS bilayer film is used to measure the viscoelastic properties of the bilayer during the evolution of the PB/PS interface showing the development of a broad gradient in local modulus ...(z) spanning ≈180 nm between the glassy and rubbery domains of PS and PB. We suggest these broad profiles in Tg(z) and ...(z) arise from a coupling of the spectrum of vibrational modes across the polymer-polymer interface as a result of acoustic impedance matching of sound waves with λ ~ 5 nm during interface broadening that can then trigger density fluctuations in the neighboring domain. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) has raised environmental concerns particularly for its depletion of fossil-fuels and contribution to climate change. To lower environmental impacts, PP can be combined with biobased fillers such as calcium carbonate (CaCO3). The mechanical and environmental properties of CaCO3 filled PP have not yet been explored in depth. Therefore, this study examines the aesthetic, tensile, flexural, impact, and environmental (via life cycle assessment) properties of injection moulded CaCO3 filled PP with filler content ranging from 0% to 40% at 5% increments. As filler percentage increased, yield strength decreased (0% CaCO3: 17.68 MPa, 40% CaCO3: 12.73 MPa), but young's modulus, flexural modulus, and impact strength increased (respectively 69%, 51%, and 35% greater than pure PP). Flexural strength increased initially at 5% CaCO3 but then declined as more filler was added. A yellowish hue was observed within all blends which growed stronger with more filler. The addition of CaCO3 reduced the environmental impact for all 11 impact categories. For every 5% of CaCO3 added, the material's global warming potential (GWP) decreased by 100g CO2 eq. per functional unit (1000 cm3) of composite. Abiotic depletion of fossil fuels declined by 32% when 40% CaCO3 was added. In addition to this study, it would be beneficial to explore other factors that affect the properties of CaCO3 filled PP such as particle size, particle distribution, and binding additives.

Magnetic nanocomposites were fabricated by attaching surface-modified magnetite nanoparticles to the surface of reduced graphene oxide (rGO) in this study. By applying an external magnetic field, the rGO were highly aligned in the cement paste. The orientation factor of aligned rGO was found to be 0.71 by analyzing the polarized Raman scattering spectra. The alignment of the rGO contributed to both the mechanical and dielectric properties of the cement paste. The flexural strength of the specimen with aligned rGO improved by 48% compared with that of the cement pastes with randomly distributed rGO. The dielectric constant at 100 Hz of the specimen with aligned rGO was increased by 271% compared with that of cement pastes with randomly distributed rGO. A modified rule of mixtures was proposed to predict their mechanical and dielectric properties. This study offers insight on the development of nanofiller-incorporated cement-based materials with enhanced mechanical and dielectric properties.

A series of laboratory and large-scale field model footing tests were conducted to assess the modulus and stress distribution behavior of a clayey soil foundation, both with/without geogrid reinforcement, deviating from the conventional approach of evaluating the strength performance, such as bearing capacity. The modulus was evaluated at three settlement ratios of s/B = 1, 3, and 5%, while the stress distribution angle α was estimated at three applied surface pressures of 234 kPa, 468 kPa, and 936 kPa. The results indicated a stiffer load-settlement response when geogrid reinforcement was included. The modulus of reinforced clayey soil remained nearly constant for test sections with the same reinforced ratio, with the modulus improvement increasing as the reinforced ratio (Rr) increased. The modulus improvement also increased with the settlement ratio (s/B). These results demonstrated that the stress distribution improvement decreased as the surface pressure increased. Generally, both the modulus and stress distribution improvement exhibited an increase with an increase in the tensile modulus of the geogrid. While laboratory model tests consistently provided a higher improvement in the modulus than large-scale field model tests in this study due to a higher reinforced ratio, the stress distribution improvement was similar for both.

Filler content in dental composites is credited for affecting its physical and mechanical properties. This study evaluated the correlation between the filler percentage and strength, modulus, shrinkage stress, depth of cure, translucency and radiopacity of commercially available high- and low-viscosity dental composites. Filler weight percentage (wt%) was determined through the burned ash technique (800 °C for 15 min). Three-point bend flexural strength and modulus were measured according to ISO 4049 with 2 mm × 2 mm × 25 mm bars. Shrinkage stress was evaluated using a universal testing machine in which composite was polymerized through two transparent acrylic rods 2 mm apart. Shrinkage was measured from the maximum force following 500 s. The translucency parameter (TP) was measured as the difference in color (ΔE00) of 1 mm thick specimens against white and black tiles. The depth of cure was measured according to ISO 4049 in a cylindrical metal mold (4 mm diameter) with a 10 s cure. Radiopacity was measured by taking a digital X-ray (70 kVp for 0.32 s at 400 mm distance) of 1 mm thick specimens and comparing the radiopacity to an aluminum step wedge using image analysis software. The correlation between the filler wt% and properties was measured by Pearson’s correlation coefficient using SPSS. There was a positive linear correlation between the filler wt% and modulus (r = 0.78, p < 0.01), flexural strength (r = 0.46, p < 0.01) and radiopacity (r = 0.36, p < 0.01) and negative correlation with translucency (r = −0.29, p < 0.01). Filler wt% best predicts the modulus and strength and, to a lesser extent, the radiopacity and translucency. All but two of the high- and low-viscosity composites from the same manufacturer had statistically equivalent strengths as each other; however, the high-viscosity materials almost always had a statistically higher modulus. For two of the flowable composites measured from the same manufacturer (3M and Dentsply), there was a lower shrinkage stress in the bulk-fill version of the material but not for the other two manufacturers (Ivoclar and Tokuyama). All flowable bulk-fill composites achieved a deeper depth of cure than the flowable composite from the same manufacturer other than Omnichroma Flow Bulk.

We look at a momentum map associated with the Heisenberg group. We show that the cocycle associated with its momentum mapping is the value of a modulus of an associated coadjoint orbit.

This study introduces the development of a novel bio-nano composite via the dispersion of cellulose nanofibers (CNF) in epoxy. The surface of cellulose nanofibers was functionalized using a two-step chemical treatment to enhance dispersion. The interfacial characteristics of CNF were improved using alcohol/acetone treatments. The modified CNF (M-CNF) demonstrated enhanced compatibility and improved dispersion in the epoxy matrix as evidenced by scanning electron microscopy. Based on the analysis of X-ray diffraction patterns, M-CNF did not disturb the crystalline phases at the interface. The results of mechanical testing showed that M-CNF worked as a reinforcing agent in the bio-nano composite. The flexural modulus increased from 1.4 to 3.7 GPa when M-CNF was introduced. A similar trend was observed for tensile strength and impact resistance. The optimum performance characteristics were observed at M-CNF of 0.6%. At higher dosages, some agglomeration was observed, which weakened the interfacial properties. This study promotes sustainability and resource conservation while offering CNF as a sustainable reinforcing agent to develop bio-nano composites.

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]

Intrinsically present bioactive cues allow naturally derived materials to mimic important characteristics of cartilage while also facilitating cellular recruitment, infiltration, and differentiation. Such traits are often what tissue engineers desire when they fabricate scaffolds, and yet, literature from the past decade is replete with examples of how most natural constructs with native biomolecules have only offered sub-optimal results in the treatment of cartilage defects. This paper provides an in-depth investigation of the performance of such scaffolds through a review of a collection of natural materials that have been used so far in repairing/regenerating articular cartilage. Although in vivo and clinical studies are the best indicators of scaffold efficacy, it was, however, observed that a large number of natural constructs had very promising scaffold characteristics to begin with, and would often show good in vitro/in vivo results. Finally, an examination of the biochemistry and biomechanics of repair tissues in studies that reported positive outcomes showed that these attributes often approached target cartilage values. The paper concludes with an outline of current trends as well as future directions for the field. This review offers an exclusive focus on natural scaffold materials for cartilage repair and regeneration and provides a quantitative and qualitative analysis of their performance under a variety of in vitro and in vivo conditions. Readers can learn about environments where natural scaffolds have had the most success and tailor strategies to optimize their own work. Furthermore, given how the glycosaminoglycan (GAG) to hydroxyproline (HYP) ratio and moduli are fundamental attributes of hyaline cartilage, this paper adds to the body of knowledge by exploring how these characteristics reflect in preclinical outcomes. Such perspectives can greatly aid researchers better utilize natural materials for Cartilage Tissue Engineering (CTE). [Display omitted] [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]

The main objective of this work is to evaluate the mechanical and thermal strength of a recently developed composite made of Cissus quadrangularis fiber coupled with Polylacticacid (PLA) in comparison to other natural fibers. This study investigated three different fiber and PLA compositions—20%, 30%, and 40%, respectively used to produce a composite. In contrast, another composite with the same volume percentage was created using calcium hydroxide Ca(OH)2 to coat the fibers in order to alter their microcrystalline structure and enhance their mechanical properties. The composite was created using an injection molding procedure. Tests were performed to assess the improved properties. According to a preliminary study, the mechanical characteristics of PLA combined with treated Cissus quadrangularis fiber are increased when compared to PLA coupled with untreated Cissus quadrangularis fiber and neat PLA. Calcium hydroxide acted as a binding agent in fiber to enhance stress transmission in the matrix, increasing tensile and flexural modulus as well as toughness elongation. Further DSC analysis showed that the inclusion of the preceding components increased the glass transition temperature and melting temperature. The temperature at the beginning of deflection has risen as a result of showing how increasing HDT, fiber–matrix adhesion, and fiber content are related. The morphological analysis was performed on both untreated and chemical-treated fiber composites by using an optical microscope to see the interaction with the fiber matrix. [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 rheological characteristics of manganese zinc (Mn-Zn) ferrite magnetic nanofluid synthesized using co-precipitation technique were examined in the absence and presence of magnetic fields. The research formulates required conditions needed for the formation of a gelly-like structure. The impact of magnetic field and temperature on the rheological properties of Mn-Zn ferrite ferrofluid is investigated. When a magnetic field was applied, higher magnetoviscoelasticity and magnetoviscosity were formed. Analysis was also done on other rheological parameters, such as the damping factor, which is crucial for regulating and restricting vibrations in a system. A stiff, gel-like structure is produced when a magnetic field is applied, and the gel-like quality grows as the magnetic field increases; when the magnetic field is removed, the gel-like and rigidity of the structure is lost. At low temperatures, the liquid phase is dominated by solid-like particles, whereas at high temperatures, the liquid-like structure is dominant. This study reveals the conditions required for the creation of high viscous effect and the viscoelastic behavior induced by the field offers important insights for optimizing the Mn-Zn ferrite ferrofluid for a range of applications. Other criterial for gel-like structure formation such as low torque and deflection angle of the ferrofluid were also established.

In this paper, three sizes (5, 20 and 50 μm) SiC particles (SiCp) were selected, and the SiCp/Mg–6Zn–1Gd-0.3Ca (SiCp/ZG61X) composites with ∼50 vol.% were successfully prepared by squeeze casting. The effect of particle size on the properties of the composites was studied, while the wear resistance and the wear mechanism of composites were investigated. The results showed that compared with the matrix alloy, the addition of SiCp can significantly improve the properties of the composites, in which the strength increased from 175.2 to 326.5 MPa and the modulus increased from 45.0 to 159.6 GPa. At the same time, the coefficient of thermal expansion and friction were significantly reduced. In addition, the smaller the particle size, the higher the strength and modulus of the composite. However, for the coefficient of friction and thermal expansion, the larger particle size was conducive to the reduction of the two coefficients. The analysis of friction and wear behavior showed that the wear mechanism of the matrix alloy was mainly abrasive wear and adhesive wear, while the wear mechanism of the composites was abrasive wear and layered wear.

Laterally loaded piles gained its attention when structures like transform towers, offshore structures etc., met huge horizontal loads. Initially, to study the behaviour of laterally loaded piles, homogeneous soil is assumed; whereas in reality the soil stratum would be stratified/ multi-layer soil with various consistency and relative density. Considering this real field situation, an 1g experimental investigation is carried out on a single pile embedded in layered soil by varying the number of layers with respect to the length of the pile. With a sand layer on top and in-between, it increases the lateral capacity of the pile. The main soil-structure interaction parameters are modulus and stiffness factor, the modulus of the homogenous sand layer is very high when compared to the clay layer sandwiched between the sand layer.

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.

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.

The relatively low melting point of a traditional Si bonding layer limits the upper servicing temperature of environmental barrier coatings (EBC). To explore suitable high temperature bonding layers and expedite the development of EBC, first-principles calculation was used to evaluate the mechanical properties and thermal conductivity of HfSi2, HfSi, Hf5Si4, Hf3Si2, and Hf2Si with much higher melting points than that of Si. Among them, HfSi2 has the lowest modulus capable of good modulus matching with SiC substrate. In addition, these Hf-Si compounds have much lower high temperature thermal conductivity with Hf2Si being the lowest of 0.63 W m−1 K−1, which is only half of Si, capable of improved heat insulation.

An extensive experimental-mechanistic study was conducted to reveal the relationship between the light weight deflectometer (LWD) measured deflections and the degree of compaction of pavement base materials. Both laboratory experiments and test pits experiments were performed with different types of pavement base materials. The modulus based maximum allowable LWD deflections under different structural and compaction conditions were developed for the most commonly used pavement base aggregate in Indiana. The maximum allowable deflections are based on the equivalent subgrade modulus and the thickness of the layer to be compacted. It is emphasized that the LWD deflections must be measured as soon as the material is compacted or before the moisture content decreases beyond a specified range. Therefore, the maximum allowable deflections are specified in terms of the difference between the actual moisture content and the optimum moisture content. The maximum allowable deflection values provide a sound basis for compaction quality control using LWD devices.

A detail analysis on the structural, morphological, dielectric, conductivity, ferroelectric, magnetic and electrical behaviour of Gd doped GaFeO3 prepared by mixed oxide method is presented. XRD analysis, by using Rietveld refinement method, validates that all the samples have single phase orthorhombic structure. Decrement in the grain size with rise in Gd content is found from FESEM analysis. The dispersive characteristic of dielectric constant is described by the Maxwell-Wagner model and Koop's theory. The value of εr is found to increase with Gd content. The modified Debye formula is used to fit εr with frequency data, which indicates the existence of more than one relaxation processes. The frequency dependant ac conductivity curve is found to obey Jonscher's power law and the conduction mechanism for all the samples is explained by of small polaron hopping (SPH) transport model. The modulus and impedance spectra confirms the presence of non- Debye type of relaxation. The presence of semicircular curves of complex impedance plot suggests the effect of grain boundary contribution to the conduction process for all the samples at low temperatures. The value of remanent polarization is found to fall with Gd content. From M-H loop, magnetisation at M (30kOe) is found to rise while non-saturation is found to decrease with Gd content and analysed on the basis of Law of Approach.

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]

In this study, the formation of clay nanolayer clusters inside the high‐density polyethylene (HDPE) matrix was evaluated using a specific strategy based on energy equilibrium in the melt mixing stage. Furthermore, the formed interphase region around nanoparticle domains was precisely evaluated considering the molecular structure of the matrix and linear variation of the physical/mechanical characteristics. The obtained results were used in a developed analytical model to predict the tensile modulus of the nanocomposite system containing randomly oriented nanoparticle domains. The domains consisted of exfoliated, intercalated, or aggregated/agglomerated nanolayers placed in different excluded volumes as the components of an equivalent box model. Different comparative studies were performed using the obtained data from different tests, applied to the prepared HDPE/clay nanocomposite samples, and other data from the literature. It was found that the confrontation between the exerted dispersion energy, by the mixer, and interparticle cohesion energy defined the thickness and physical/mechanical characteristics of the final aggregates/agglomerates in a nanocomposite. Though, the size and content of aggregates/agglomerates increased with the content of initially added nanoparticles. Consequently, the random orientation of each nanoparticle domain and formation of the polymer/particle interphase were proved to have determinative impacts on the mechanical properties of the system. [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]

A359 aluminum alloy composite containing 20 vol. % silicon carbide particles was remelted, and 100-mm diameter foam ingots were prepared using 0.75 wt. % of titanium hydride (TiH2). Three identical experiments each were carried out at two foaming temperatures (640 and 660 °C) to check the reproducibility of the cell structure and foam properties. Foams made at 640 °C were reproducible in terms of foam expansion, cell size and cell size variation along the ingot height. The property scatter, evaluated in terms of relative standard deviation, is similar for density and modulus of the foam. For compressive plastic strength, the scatter is double than for density. The density and mechanical properties are reproducible within these scatters. Foams prepared at 660 °C, on the other hand, suffered from liquid foam collapse during solidification and hence couldn't be qualified for detailed study of reproducibility. The collapse resulted in distortion of the foam ingot and elongated cell structures in other parts. However, the cell size and mechanical properties in the un-distorted region are comparable with those foamed at 640 °C. Overall, good quality cell structure and consistent mechanical properties could be obtained in foams processed at 640 °C. [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]

This study investigated the mechanical and tribological properties of branched polyethyleneimine/polyacrylic acid (bPEI/PAA) coatings. (bPEI/PAA) coatings were prepared on Ti6Al4V substrate using layer-by-layer assembly technique. The coatings have good tribological behaviors with the rotating mode under the deionized water. In particular, (bPEI/PAA)40 has the lowest friction coefficient with the reciprocating mode, about 0.14. The cross-linked network structures were formed with the electrostatic attraction. The amorphous phase of coatings provides a crucial buffer during the loads applying on the surface. The (bPEI/PAA)n coatings have the swelling ability, and there are large decreases of storage modulus and loss modulus in deionized water compared with removing from the deionized water. The excellent tribological properties are ascribed to the cross-linked network structure, amorphous phase, and swelling ability. [ABSTRACT FROM AUTHOR]

A new ternary compound, Mg11-xZnxSr in the Mg-Zn-Sr system was observed and studied using Scanning Electron Microscopy (SEM), Energy-Dispersive Spectroscope (EDS), X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The XRD patterns were refined by the Rietveld refinement method and the results revealed that the crystallized Mg11-xZnxSr phase belonged to tetragonal I41/amd space group and had the Cd11Ba prototype. The Mg atoms were successfully doped into Zn11Sr crystal lattice by occupying Zn atomic sites. Moreover, the Rietveld refinement and computational results demonstrated a gradual decrease in the a-axis and c-axis lattice parameters with decreasing concentration levels of Mg coordination substitution in the lattice of Mg11-xZnxSr compound. The elastic constants and modulus of the Mg11-xZnxSr compounds calculated by first-principles calculations (FPC) indicated they were increased with the increasing of Zn content. The variation of hardness, d-band widths and the total density of states for Mg11-xZnxSr compounds with Zn content was discussed.

Abstract Background The strength of cotton fiber has been extensively studied and significantly improved through selective breeding, but fiber elongation has largely been ignored, even though elongation contributes to determining the energy needed to break fibers. Recent developments to calibrate the high volume instrument (HVI) for elongation has renewed interest in elongation. However, it is not understood how best to utilize yet another fiber property which has the potential to add to the complexity of fiber selection. To explore a practical approach to applying elongation, cotton samples were tested using single fiber methods, the Stelometer, and the HVI. Comparison of strength, elongation, and combined properties such as modulus were explored. Results HVI testing was shown to be sensitive enough to characterize elongation differences but unlike single fiber testing it was unable to capture within-sample variation. Fiber bundle testing, like Stelometer and HVI was shown to reduce bias due to fiber selection. Conclusion The use of secant modulus, an intrinsic material property, allowed for one value to represent both strength and elongation. Secant modulus was shown to contain more useful information than either elongation or work-to-break. Work-to-break was shown to be more influenced by a specific value of breaking force or elongation rather than the intrinsic behavior of the sample being tested. Exploring the influence of genetics and environment on elongation, and its interaction with other fiber properties, requires additional work. Secant modulus, by combining strength and elongation into one value, shows the potential to incorporate elongation values into fiber characterization without increasing the complexity of current fiber selection processes.

Throughout all the countries in the world, including Vietnam, nations with well-established mining industries have undertaken extensive research on the stability of rock masses when constructing underground tunnels in varied geological conditions. The present study aims to provide a comprehensive overview of the risk assessment related to rock masses during the construction of pit lines in mining operations. Consequently, the standing time of unsupported tunnels is assessed based on different values of the strength index and deformation characteristics of the rock mass. The objective was to perform both experimental and theoretical investigations to analyse how the stand-up time of rock masses surrounding a tunnel affects the unsupported span. The analyses were based on considering the rock parameters, including strain modulus; geological strength index; and allowable displacement values, and consideration of hereditary creep properties. By examining tunnels excavated in rock strata, it was concluded that varying geological strength index values resulted in distinct creep behaviour in the surrounding rock masses. Thus, it was reasonable to compute the unsupported span and stand-up time of tunnels. The research revealed that permissible displacements are significantly influenced by the types of rock materials surrounding the tunnel structure. Recognising the significance of time, the authors introduce a more practical interpretation and evaluation of the stability of rock masses, thus enhancing the precision of commonly available models.