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The transfer of large-area and clean graphene to arbitrary substrates, especially to those with raised nanostructures, represents a great challenge. Polymer-based supporting layers generally lead to organic residues, while graphene transfer using alternative supporting materials like paraffin suffers from breaking and thus limits the transfer area. We demonstrated an improved poly(methyl methacrylate) (PMMA)/paraffin double layer, enabling the large-area transfer of graphene with high cleanliness and high coverage (81%) onto gold nanopyramid (AuNP)-structured substrates. The impact of supporting layers including single PMMA or paraffin and mixed PMMA/paraffin was clarified. The properties of graphene on AuNPs were theoretically and experimentally examined in detail. Raman spectra show a polarization-dependent D peak due to the folding of large-curvature graphene. The graphene on AuNPs shows a slightly tensile strain and provides extra surface-enhanced Raman scattering (SERS) with an enhancement factor of ∼20 times. These findings open a pathway to extend the applications of transferred graphene on raised nanostructures in many fields, such as SERS detection, catalysis, biosensors, light-emitting diodes, solar cells, and advanced transparent conductors.

Elastic strains in metallic catalysts induce enhanced selectivity for carbon dioxide reduction (CO

With the ever-increasing interest in low-dimensional materials, it is urgent to understand the effect of strain on these kinds of structures. In this study, taking the CF2Si monolayer as an example, a computational study was carried out to investigate the effect of tensile shear strain on this compound. The structure was dynamically and thermodynamically stable under ambient conditions. By applying tensile shear, the structure showed a strain-driven transition from a semiconducting to a metallic behavior. This electronic transition’s nature was studied by means of the electron localization function index and an analysis of the noncovalent interactions. The result showed that the elongation of covalent bonds was not responsible for this metallization but rather noncovalent interactions governing the nonbonded bonds of the structure. This strain-tuned behavior might be capable of developing new devices with multiple properties involving the change in the nature of chemical bonding in low-dimensional structures.

Mechanical instabilities in soft materials have led to the formation of unique surface patterns such as wrinkles and cracks for a wide range of applications that are related to surface morphologies and their dynamic tuning. Here, we report a simple yet effective strategy to fabricate strain-tunable crack and wrinkle microvalves with dimensions responding to the applied tensile strain. The crack microvalves initially closed before stretching are opened as the tensile strain is applied, whereas the wrinkle microvalves exhibit the opposite trend. Next, the performance of crack and wrinkle microvalves is characterized. The design predictions on the bursting pressure of microvalves and others from the theory agree reasonably well with the experimental measurements. The microfluidic devices with strain-tunable crack and wrinkle microvalves have then been demonstrated for microsphere screening and programmable microfluidic logic devices. The demonstrated microfluidic devices complement the prior studies to open up opportunities in microparticle/cell manipulations, fluidic operations, and biomedicine.

We investigated the influence of horizontal and longitudinal strain on the electronic proprieties of Stone-Wales defected honeycomb graphene structure using the density functional theory. Tensile a...

Graphdiyne (GDY) membrane with intrinsic pore has potential for gas separation. Here we report a multistage gas separation of H2/CO2/N2/CH4 gas mixture through graphdiyne by applying tensile strain...

The existence of bio-accumulative lead hinders the commercialization of optoelectronic applications of Pb-based halide perovskites (PVKs). Therefore, researchers are seeking for comparative lead-free PVKs. Owing to the identical electronic configuration with Pb, Bi-based PVKs are proved to be one of the most promising candidates. Because strain is widely existed altering materials’ characteristics, it is crucial to study the influences of strain on the Bi-based PVKs. Our theoretical work investigates the strain influences on two kinds of Bi-based PVKs, i.e., Cs3Bi2Br9, and Cs2BiAgBr6. It is observed that both the tensile and compressive strains effectively change the crystal structures and the bandgaps, i.e., enlargement under tensile strain while shrinkage under compressive strain. Simultanously, the absorption spectra of these PVKs are also discussed. The strain study of Bi-based PVKs will offer guidance to the further development of lead-free PVKs.

Quantum dots that store large tensile strains represent an emerging research area. We combine experiments and computational modeling to investigate the self-assembly of Ge and GaAs tensile-strained...

Construction over soft soil is a challenge as the ground can be too soft to work on it. To overcome this, a working platform has to be formed before any soil improvement work can be carried out. One of such methods was proposed by Broms (1987) which uses geotextile and sand berms. In this paper, a modified Broms' method is proposed to use geotextile tubes to confine the sand berms. A new analytical solution is also proposed to calculate the tensile strain and the profile of geotextile under the sand berms/tubes. Design charts for different design conditions are also developed. Parametric studies were conducted to identify the key parameters affecting the design. Finite element analyses (FEA) and a field trial were also carried out to verify the modified Broms' method and the proposed solution. The monitoring data agree reasonably well with the results obtained from proposed solution and FEA. A design procedure for modified Broms' method and Broms’ method is proposed using the analytical solution. Nanyang Technological University The field trial was carried out as a research project jointly with JTC Corporation, Singapore. The financial support from the JTC Corporation through the NTU-JTC Industrial Infrastructural Innovation Centre (I3C) is gratefully acknowledged. The first author is also grateful to the scholarship provided by NTU for his PhD.

Silicon has several technologically promising allotropes that are formed via high-pressure synthesis. One of these phases (hd) has been predicted to have a direct band gap under tensile strain, whereas other (r8 and bc8) phases are predicted to have narrow band gaps and good absorption across the solar spectrum. Pure volumes of these phases cannot be made using conventional nanowire growth techniques. In this work, Si nanowires were compressed up to ∼20 GPa and then decompressed using a diamond anvil cell in the temperature range of 25-165 °C. It was found that at intermediate temperatures, near-phase-pure bc8-Si nanowires were produced, whereas amorphous Si (a-Si) dominated at lower temperatures, and a direct transformation to the diamond cubic phase (dc-Si) occurred at higher temperatures under compression. Thus this study has opened up a new pressure-temperature pathway for the synthesis of novel Si nanowires consisting of designed phase components with transformative properties.

Hematite (α-Fe2O3) nanowhiskers (NWs) synthesized via oxidation of iron-based substrates are a promising photoanode material for photoelectrochemical water splitting. Such synthesized α-Fe2O3 NWs have been found to contain ordered axial structures. Herein, we reveal that the known (1$$\overline{1}$$ 1 ¯ 2)-related ordered structure actually exists in bicrystalline α-Fe2O3 NWs instead of single-crystalline α-Fe2O3 NWs and that it is associated with another known (3$$\overline{3}$$ 3 ¯ 0)-related ordered structure. Through a spherical aberration (CS)-corrected high-resolution transmission electron microscopy (HR-TEM) investigation, the microstructural characteristic of the (1$$\overline{1}$$ 1 ¯ 2)-related ordered structure is verified to be periodic atomic column displacements serving as tensile strain accommodation. The HR-TEM observation are also supported by a monochromated O K-edge EELS analysis, which indicates that α-Fe2O3 NWs hosting the (1$$\overline{1}$$ 1 ¯ 2)-related ordered structure are indeed associated with lattice expansion. In sum, our microstructural study elucidates the root cause of the long-asserted relationship between the (1$$\overline{1}$$ 1 ¯ 2)-related ordered structure and oxygen vacancy ordering.

Highly tensile-strained Ge quantum dots (TS-Ge-QDs) emitting structures with different size were successfully grown on InP substrates by molecular beam epitaxy. Defect-free samples with TS-Ge-QDs were confirmed by transmission electron microscopy. Finite element modeling indicates a maximum tensile strain of 4.5% in the Ge QDs, which is much larger than the required strain to achieve direct bandgap conversion of Ge based on theoretical prediction. Photoluminescence (PL) from a direct bandgap-like transition of TS-Ge-QDs with a peak energy of 0.796 eV was achieved and confirmed by the etch depth-dependent PL, temperature-dependent PL and power-dependent PL. In addition, a strong defect-related peak of 1 eV was observed at room temperature. The band structure of the TS-Ge-QDs emitting structures was calculated to support the experimental results of PL spectra. Achieving PL from direct bandgap-like transitions of TS-Ge-QDs provides encouraging evidence of this promising method for integrated light source on Si photonics platform. National Research Foundation (NRF) Accepted version The authors would like to thank the financial support from the National Research Foundation of Singapore under the Competitive Research Program (NRF–CRP19–2017–01)

Deeply-notched metallic glasses can achieve significantly enhanced nominal tensile strain and strength under tension, and show the characteristics of dimples and “cup-and-cone” morphology on the fractographs. It has been expected that this deep-notch enhancement effect is resulted from the suppressed shear banding. In this study, we provided another interpretation for this effect through stress/strain field analyses based on the ellipse criterion. The results revealed the existence of relatively low but highly dispersed stress/strain instead of highly enhanced and localized stress/strain in deeply-notched metallic glasses, and therefore the actual stress is much lower than the nominal value. Owing to the positive third principal stress condition, the failure angle predicted by the ellipse criterion shifted from 45° at the edge of the notch to 90° at the center of the specimen, which was consistent with the “cup-and-cone” fracture morphology. These findings clarify the very high nominal stress/strain and special fracture process in deeply-notched metallic glasses. Our work provides a useful method to predict the shear-to-tensile failure mode transition of metallic glasses under complex loading conditions.

Reinforced subgrade for railways (RSR) is a construction method in which reinforced subgrade is constructed first and a rigid facing wall later to minimize the residual settlement after the service of a roadbed. The RSR was designed and constructed at Osong railway test line in Korea. In this study, load sharing capacities from the reinforced subgrade to the rigid facing wall of it were evaluated through long-term measurement, extending 22 months from the start of roadbed construction to the completion of track construction. Under the condition of 0.4 m geogrid vertical spacing installation, the load sharing proportion of horizontal earth pressure of the rigid facing wall was 9%–22% in the lower part, and lesser in the upper part. The strain of geogrid during construction was 0.607%, which was relatively lower than the designed geogrid tensile strain of 5%. The change in geogrid strain after construction was closely correlated with temperature change in the soil.

Our work reveals a class of three-dimensional materials whose main features are dominated by d-orbital states. Their unique properties are derived from the low-energy states t2g. Without spin-orbital coupling (SOC), we find a triple degenerate point with a quadratic dispersion, demonstrated by an effective Hamiltonian. When SOC is included, the sign of SOC could determine the topological phases of materials: a negative SOC contributes a Dirac semimetal phase with a quadratic energy dispersion, whereas a positive SOC leads to a strong topological insulator phase. There exist clear surface states for the corresponding topological phases. Very interestingly, by application of a triaxial strain, the sequence of bands can be exchanged, as do the topological phases. In particular, there exists a 6-fold degenerate point under a critical strain. Furthermore, we use a uniaxial compressive/tensile strain, changing the quadratic Dirac point into a linear Dirac/strong topological insulator phase.

The basic pore unit model is extended to predict the strained pore size characteristics of woven slit-film geotextiles subjected to unequal biaxial tensile strains. The strained per cent open area (POA) and analytical pore size are expressed as functions of the weft strain and the warp strain to weft strain ratio. The influence of the biaxial tensile strain on pore size characteristics is evaluated in three woven slit-film polypropylene geotextile samples using image analysis under the warp strain to weft strain ratios of 1, 2, 3 and 4. It is shown that the experimental POA and O95 increased significantly with increasing strain at different warp strain to weft strain ratios, and the PSD curves moved toward the direction of large open sizes. The analytical models of POA and pore size can accurately predict the increasing trend of POA and O95. Moreover, unequal biaxial tensile strains can significantly change the shape of the pores, which may influence the results of the pore size obtained by indirect methods. A larger warp strain to weft strain ratio can lead to a larger change in the pore shape when the length to width ratios of initial pores are close to 1.

Spherical gold nanoseed (∼5–6 nm)-induced (but not seed-mediated) silver nanorods (Hy-Au@AgNRs) of variable lengths have been synthesized by a new methodology that shows enhancement in catalytic ac...

Geosynthetics have been widely applied in flexible pavements for decades. However, the mechanistic-empirical analytical approach for geosynthetic-stabilized flexible pavements based on the elastic solution derived from the layered elastic theory has not been established. In this study, the solution for a typical three-layer geosynthetic-stabilized flexible pavement was derived according to the layered elastic theory. In the derivation, lateral restraint and tensioned membrane effect of geosynthetics quantified in terms of layer permanent deformations were considered at the interface as a continuity condition. The derived solution was then incorporated into the mechanistic-empirical approach for the calculation of pavement rutting and fatigue cracking. The result indicates that the solution derived in this study is capable of analyzing the geosynthetic-stabilized three-layer flexible pavement. The pavement elastic responses calculated using the solution obtained in this study are in line with those by the previously established solutions in the literature. The rut depths estimated using the proposed solution reasonably match those measured in the previous study. For rut reduction, the geosynthetic placed underneath the base layer is more effective. For the tensile strain relief at the bottom of the asphalt layer, the geosynthetic placed at the bottom of the asphalt shows more benefit.

The effect of surface tensile strain on the photocatalysis is an open question. In this work, strain engineering has been demonstrated to promote the performance of photocatalysis by curved 2D mate...

This paper presents a series of model tests on geosynthetic-reinforced soil (GRS) foundations across a normal fault. The aim was to evaluate the performance of reinforced foundations as a mitigation measure for surface faulting hazards. Experimental tests modeled a 3-m thick foundation in prototype subjected to a fault displacement up to 90 cm. Test variables included the number of reinforcement layers, reinforcement stiffness and location, and foundation height. Digital image analysis techniques were applied to determine the ground settlement profile, angular distortion, shear rupture propagation, and mobilized reinforcement tensile strain at various magnitudes of fault offset. Test results revealed that compared with the unreinforced foundation, reinforcement inclusion could effectively prevent the shear rupture propagating from the bedrock fault to the ground surface. It also spread the differential settlement to a wider influential zone, resulting in an average reduction of 60% in the fault-induced angular distortion at the ground surface. The maximum angular distortion decreased as the foundation height, number of reinforcement layers, and reinforcement stiffness increased. Relationships between the maximum angular distortion and maximum mobilized reinforcement tensile strain with fault displacement were therefore established. Based on the findings from this study, design suggestions and implications are discussed.

Solidification cracking can occur when neighbouring columnar grains are separated by tensile strain perpendicular to the grain boundary. In this study, a method to determine the tensile strain caus...

We report the first experimental measurement on the thermal conductivity of strained monolayer graphene using optothermal Raman method. Biaxial tensile strain was achieved by applying a pressure difference across suspended monolayer graphene membranes. Experimental results demonstrate that, under 0.12%–0.27% strains, the in-plane thermal conductivity of monolayer graphene is sensitive to the applied biaxial strains. Under a 0.12% biaxial tensile strain, the thermal conductivity of suspended monolayer graphene drops approximately by 20% near 350K and 12% at about 500K. This study confirms the previous theoretical prediction that the thermal conductivity of monolayer graphene can be modified by applying tensile strains.

The mechanism of mechanical twinning in the vicinity of a grain boundary, which has been considered as a twin nucleation site, was investigated using Fe-17.5Mn-0.58C-1.5Al twinning-induced plasticity steel. When tensile strain was 0.02, multiple slips occurred near grain boundaries. The interaction between dislocations on multiple slip planes resulted in stacking faults composed of Shockley and Frank partial dislocations at the locations slightly away from grain boundaries. When the strain reached 0.05, mechanical twins formed near grain boundaries to grow toward the interior of grains. This observation result matched well with twinning mechanism proposed by Miura, Takamura, and Narita.

Nowadays, virtual try-on is an irreplaceable technology in fashion industry, so it is very important to prove virtual try-on matching with the real garments. Therefore, the aim of this research was to compare garment fit using virtual try-on and scanning technologies. For this reason, garment visual appearance and distance ease between straight fit dress and mannequin in respect to fabrics properties were investigated. Women mannequins in different sizes were scanned by 3D scanner VITUS Smart XXL without and with the real straight fit dresses made from five different woven fabrics. Fabrics mechanical properties were defined by KES-F. Scanned mannequins were covered with the same size and fabric virtual dresses by Modaris 3D (CAD Lectra). Distance ease of virtual and scanned garments was compared in bust and waist cross-sections. It was defined that distance ease values at bust girth of real and virtual dresses differed till 29.9 % (1.16 cm), while at waist varied from 7.3 % (0.51 cm) to 47.3 % (4.30 cm) because of wrinkles in this area. Generally, appearance of the virtual dresses was similar to real dresses with some differences in garment shape fluency, however by increasing of the mannequin size, similarities decreased. It was assumed that very high shear rigidity G could not be very well reflected in 3D CAD system, therefore differences between virtual and real dresses appearance occurred. The general appearance and form of bust and waist cross-sections of virtual dresses with fabric 03 had less similarities comparing with real dresses due to high G value. So, comparative study showed that the accuracy of virtual try-on was quite useful comparing to real garments, if shear rigidity of fabrics was lower than 1.6 N/m*º and tensile strain in warp direction was higher than 1.80 %.

A highly stretchable, transparent ionic conductive cellulose/PVA hydrogel (CPH) was fabricated by a facile and environment-friendly strategy with zero wastage. CPH based sensors exhibited fast and stable sensitivity to temperature, compressive pressure and tensile strain. A CPH based triboelectric nanogenerator for energy harvesting exhibited resistance to temperature change, stretching, long time storage or even a large number of operation cycles.

It is important and difficult to improve the tensile strength of backfill material to ensure the stability of goafs. In this study, rice straw (RS) in fiber form is used to improve the tensile properties of cemented paste backfill (CPB). An orthogonal experiment was designed, Brazilian indirect tensile strength tests were conducted to test the tensile performance of RS fiber-reinforced cemented paste backfill (RSCPB) under different fiber content (1, 2, 3 kg/m3) and fiber length (0.8~1, 1~3, 3~5 cm), and the microstructure of RSCPB was analyzed with scanning electron microscopy (SEM). The results showed that, compared with the conventional cemented paste backfill (CCPB), the increase in tensile strength of RSCPB ranged from 115.38% to 300.00% at 3 days curing age, 40.91% to 346.15% at 7 days, and −38.10% to 28.00% at 28 days, and the strain was slightly reduced during the curing period. The tensile strength, strain, and percentage increase of the RSCPB compared to the CCBP did not show a monotonic pattern of variation with the RS fiber content and length during the curing period. The RSCPB samples fractured under peak stress, showing obvious brittle failure. In addition, sulfate generated from S2− in the tailings inhibits the hydration reaction, and generates swelling products that form weak structural surfaces, which, in turn, lead to a 28-day tensile strength and strain of RSCPB lower than those at 7 days.

This study used a digital imaging technique (DIC) to obtain the strain distribution at various locations in undermatching X80 pipe girth-weld joints under uniaxial tensile loading. In addition, the microstructure characteristics and deformation patterns in different regions were analyzed by scanning electron microscopy (SEM). The results showed that there was strain heterogeneity between the various regions of the welded joint. Strain concentration existed only in the 12.8 mm base metal heat-affected zone (HAZ) and only in the elastic deformation stage. There was strain concentration in the weld metal (WM) and both sides of the HAZ close to the near-fracture stage, and the maximum deformation was in the WM. When εM = 12.2%, the KC was 6.27 and the KF was 1.73, and the KF was 113% and 152% of the KC and the KG, respectively. The large number of slip strips generated indicated serious damage in the WM near the fracture stage. In the elastic deformation stage, the strain concentration of the N1 HAZ was caused by the softened ferrite. The maximum deformation of the WM near the fracture stage was caused by the large grain size and the non-uniform martensite–austenite (M–A) islands, which may also lead to better local toughness of the cover weld and further affect the fracture mechanism of the welded joint.

In the present article, we investigate the effect of two interacting Stone–Wales defects on the deformation and fracture behaviour of 2D silica. For this purpose, we use molecular simulations based on a recently developed Yukawa-type potential function that allows for the description of silica in two dimensions. Our main objective is to address the impact of the spatial arrangement of defects on the deformation and fracture behaviour of 2D silica. To this end, we prepare various 2D silica configurations with one and two Stone–Wales defects, while varying the spatial arrangement of the two defects. The samples are subjected to athermal quasistatic tensile deformation until fracture occurs. We show that, by introducing Stone–Wales defects, both the tensile strength and tensile strain of 2D silica decreases. However, we report that not only the number of Stone–Wales defects but also the distance between them, their orientation and additionally the loading direction play an important role in the deformation and fracture behaviour of 2D silica. We discuss and explain the respective stress–strain relation by evaluating the non-affine displacement field of each configuration under tensile deformation. We observe that under certain orientations and distances 2D silica containing two Stone–Wales defects may exhibit a higher tensile strength than 2D silica with a single Stone–Wales defect.

The interfaces introduced in metals by heterostructural design play crucial roles in mechanical behaviors. Here the effect of gradient interfaces on mechanical behavior was investigated in a laminated Cu–30Zn sample composed of coarse-grained and ultrafine-grained layers. Tensile tests revealed a superior strength-ductility synergy with extraordinary strengthening and work hardening. By combining the measurements of height contour and strain distribution using digital image correlation, the development of strain gradient was detected in the near-interface zone during tension, which was caused by the mechanical incompatibilities across interfaces and the synergetic constraint between layers. The intensity of strain gradient in the near-interface zone increased with tensile strain, which was accommodated by the accumulation of geometrically necessary dislocations, thereby resulting in extra back stress and dislocation strengthening.

Transparent, highly stretchable and sensitive strain sensors have been successfully fabricated using carbon nanotube (CNT) networks with various densities as the sensing medium. Owing to the unique two-dimensional percolated structure, the CNT network-based sensors exhibit excellent sensing performance over a wide strain range from 0.5 to 100%. By decreasing the density of CNTs from 152 to 7.2/μm2, their gauge factor is remarkably increased from 0.4 to 50. It is found from the experimental results and theoretical analysis that the sensing mechanism of the CNT networks is transferred from percolation theory to tunneling effect with decreasing the density or increasing the tensile strain of the CNT networks. This study provides a facile technique to prepare high stretchable strain sensors and also fundamental principles for the structural design of the CNT network-based strain sensors.

By adopting the first-principles plane wave pseudopotential method based on density functional theory, the electronic structure properties of single-layer MoS2 (molybdenum disulfide) crystals under biaxial strain are studied. The calculation results in this paper show that when a small strain is applied to a single-layer MoS2, its band structure changes from a direct band gap to an indirect band gap. As the strain increases, the energy band still maintains the characteristics of the indirect band gap, and the band gap shows a linear downward trend. Through further analysis of the density of states, sub-orbital density of states, thermodynamic parameters and Raman spectroscopy, it revealed the variation of single-layer MoS2 with strain. This provides a theoretical basis for realizing the strain regulation of MoS2.

An asphalt-binder is one of the key constituent elements that significantly influences and controls the fracture behavior and cracking performance of hot-mix asphalt (HMA). In particular, t...

The objective of this paper is to to ascertain the reliable mechanical properties of cold-formed Q345 steel at elevated temperatures while considerting the effects of tensile strain rate an...

We investigated the production conditions and optoelectrical properties of thin film material consisting of regularly ordered core/shell Ge/Al and Ge/Si3N4/Al quantum dots (QDs) in an alumina matrix. The materials were produced by self–assembled growth achieved by means of multilayer magnetron sputtering deposition. We demonstrated the successful fabrication of well-ordered 3D lattices of Ge/Al and Ge/Si3N4/Al core/shell quantum dots with a body-centred tetragonal arrangement within the Al2O3 matrix. The addition of shells to the Ge core enables a strong tuning of the optical and electrical properties of the material. An Al shell induces a bandgap shift toward smaller energies, and, in addition, it prevents Ge oxidation. The addition of a thin Si3N4 shell induces huge changes in the material spectral response, i.e., in the number of extracted excitons produced by a single photon. It increases both the absolute value and the width of the spectral response. For the best sample, we achieved an enhancement of over 250% of the produced number of excitons in the measured energy range. The observed changes are, as it seems, the consequence of the large tensile strain in Ge QDs which is induced by the Si3N4 shell addition and which is measured to be about 3% for the most strained QDs. The tensile strain causes activation of the direct bandgap of germanium, which has a very strong effect on the spectral response of the material.

Electronic tattoos as an emerging epidermal electronic are alluring in the field of wearable electronics for their lightweight and noninvasive properties. However, the combination of flexibility, skin biocompatibility, adhesion, repairability, and erasability remains a challenge for fabricating electronic tattoos. Hence, a dynamic ionic liquid is prepared which is ideally suited for making an electronic tattoo with these challenging features at the same time. Such an intrinsically flexible electronic tattoo can be firmly attached to human skin with negligible irritation. More importantly, the existence of dynamic covalent chemistry provides the electronic tattoo with healing and erasable abilities under mild redox conditions. Owing to the high ionic conductivity of ionic liquids, the electronic tattoo exhibits excellent sensing performance in response to the temperature variation and tensile strain, which can intelligently monitor body temperature, pulse, and movement. As an extension of the application, a specially designed quadrilateral electronic tattoo can sense and distinguish multiple signals simultaneously. This concept of electronic tattoo based on the dynamic ionic liquid shows great potentials in the applications of intelligent wearable electronics.

This work presents the effect of stress-induced martensite aging (SIM-aging) on the functional properties of Ni53Mn25Ga22 (at.%) single crystals, oriented along the [001]L21-direction. The most effective regime of SIM-aging occurred under a compressive stress of 175 MPa along the [110]L21||[100]L10-direction at 423 K, for 2 h, which induced the high-temperature two-way shape memory effect with a reversible tensile strain of +9.0%, causing the jumping of the sample during cooling/heating in free state, and a rubber-like behavior with a giant reversible compression strain up to − 13.2% caused by L10-martensite variant reorientation.

We report polarized and resonant Raman study of InAs/GaAs quantum dot solar cell (QDSC) structures. Raman spectra obtained from the top surfaces of the samples suggested that the formation of InAs QDs induced tensile strain in the overgrown GaAs layers. Furthermore, a longitudinal optical phonon-plasmon (LPP) coupled modes were observed in the p-type GaAs layers. The tensile strain was increased with an increase in the QD size. The hole concentrations estimated by fitting the individual LPP coupled modes were in the range of 2.4–3.5 × 1018 cm−3. Resonant Raman spectra obtained from the cleaved sides, where the QDs were located, showed a 225 cm−1 mode in parallel polarization configurations. Based on accurate analysis, this mode was identified as the LA(X) phonon of GaAs.

This paper investigates tensile performances of strain-hardening cement-based composites (SHCC) with different curing ages varying from 3d to 28d. Cracking properties of SHCC specimens like the evolution of the number of cracks and the crack opening under direct tension was monitored simultaneously by using the digital images correlation (DIC) technique. Results show that the ultimate tensile strain in specimens cured for 7d is higher than that in specimens cured for 3d and 28d. The strain-hardening process involves three stages such as the initial, the intermediate, and the final stage, which are determined in terms of their cracking properties. Cracking properties of specimens cured for 3d and 7d display different rules from those of specimens cured for 28d at the intermediate strain-hardening stage, leading to different shape of stress-strain curve. Curing age influences fiber bridging stress-crack opening relation ( σ ( δ ) ) and interfacial mechanical behavior between PVA fiber and the matrix. σ ( δ ) gained by the DIC technique is similar to that observed in the tensile testing on notched specimens. The energy-based index of specimens cured for 7d has greater margin than that of specimens cured for 3d and 28d. The interfacial bond between fiber and matrix in specimens cured for 28d is larger than that in specimens cured for 3d and 7d.

Uniaxial tensile and ratcheting tests were performed with a 3D DIC system to investigate the tensile strain evolution and heterogeneous ratcheting of each area in a gas tungsten arc welding (GTAW) welded joint. The results indicated that with increasing applied stress, the strain was initially concentrated in the base metal (BM) owing to its low yield stress, and then extended gradually to the heat affected zones (HAZ) and subsequently to the weld metal (WM) until the occurrence of quasi-shakedown. Furthermore, the most remarkable ratcheting strain and ratcheting rate were obtained in the BM but it manifested lower ratcheting deformation in the BM area of the GTAW welded joint as compared with the pure base metal.

In this paper, a refined engineering rule for the assessment of remaining fatigue life of concrete under compressive cyclic loading with varying amplitudes is proposed. The rule has been derived based on a combined numerical and experimental investigation of the loading sequence effect. The applied modeling approach is based on a damage model using the equivalent tensile strain rate to govern the fatigue damage evolution upon loading and reloading at subcritical load levels. A systematic calibration and validation procedure of the numerical model was performed based on the available experimental results. The prediction of the numerical model was compared with existing damage accumulation rules for the assessment of the concrete fatigue life exposed to varying loading ranges. Based on these studies, an enhancement of the Palmgren-Miner rule is proposed and validated for several loading sequence scenarios.

Recently, group-VA 2D materials have attracted intense attention due to excellent properties in various aspects. Particularly, the strong spin–orbital coupling effect is a remarkable virtue of group-VA 2D materials, which is more widely concerned by researchers. Here, based on first-principles calculations, we provide a systematical investigation on the electronic and topological properties of a novel series 2D compound VA2OX (VA = Bi, Sb, As, P; X = S, Se, Te). Combining with the nontrivial Z2-type topological invariants, it is confirmed that VA2OX 2D crystals possess topologically nontrivial characteristics. The 2D TIs VA2OX demonstrate large and tunable nontrivial energy gaps, from 0 to 592 meV, indicating that the tunable QSH effect can be realized at room temperature. Moreover, as an example of VA2OX systems, the band gap of Bi2OS 2D crystal almost remains unchanged when tensile strain not larger than 8%. Notably, under a large range of strain (±10%), Bi2OS keeps the inversion-asymmetric topological insulator phases, which emerges the robustness of nontrivial topology against mechanical deformation and makes it competent for realizing new topological phenomena. The above results are expected to promote further experimental investigation for fundamental exploration and practical application, which will significantly broaden the scientific and technological impact of the QSH effect.

The dispute over Ta2O5 atomic structure was recently resolved by the discovery of the λ -phase model (space group Pbam), but due to the widely scattered experimental band gaps, the energy band gap of Ta2O5 still remains questionable. This letter presents a complete first principle calculation of the λ phase Ta2O5 energy band gap and looks at how different conditions of strain can modify it. From the results, we conclude that the theoretical band gap of λ phase Ta2O5 is about 3.7 eV and show that the band gap difference of about 0.45 eV can be made by only 3% compressive or tensile strain.

Currently, finding the non-precious metal catalyst for hydrogen evolution reaction (HER) is significant and urgent. By performing the first-principles calculations, we studied the structural and electronic properties, as well as the catalytic activity of MXenes Mn+1CnO2 (n = 1, 2; M = Sc, Ti, V, Cr, Mn, Zr, Nb, Mo, Hf, Ta and W) toward HER. These 22 MXenes are metallic except for Sc2CO2, Ti2CO2, Mn2CO2, Zr2CO2 and Hf2CO2 which are semiconducting. By calculating the Gibbs free energy change (ΔGH) for H adsorption which is the simple but effective descriptor for HER catalytic activity, and analyzing the electrical conductivity, we find that Nb2CO2, W2CO2, Zr3C2O2 and W3C2O2 are catalytic active for HER at low H coverage. Particularly, Nb2CO2 and Zr3C2O2 maintain to be active for catalyzing HER under tensile strain less than 5%. And Nb3C2O2 shows enhanced catalytic activity for HER under 3–5% tensile strain. Additionally, the differential ΔGH and average ΔGH were used to evaluate the HER catalytic activity at high H coverage (1/8–6/8). Our calculations show that Nb2CO2 is active for HER at H coverage less than 3/8. Plus, V2CO2, Ti3C2O2 and Cr3C2O2 demonstrate the catalytic activity for HER at high H coverage.

An innovative approach for characterizing the fatigue character of high modulus asphalt concrete (HMAC) and matrix asphalt concrete was presented. Strain-life fatigue equations based on uniaxial tensile test are employed to extract parameters characteristic of the asphalt concrete's resistance to fatigue. The feasible test conditions including specimen size, failure criterion, control mode, loading frequency and test temperature are proposed. In addition, the effect of the mean stress on the fatigue life is analyzed that mean stress has minor influence on fatigue life evaluation. Fatigue strain threshold, limit strain and fatigue life equation are put forward based on the fatigue test results at different strain levels. Such fatigue equation as well as tensile strain threshold and limit value can guide the development of the two asphalt mixtures, which can estimate the lifetime of load-bearing structures. From the fatigue character comparison between the two asphalt mixtures, tensile strain threshold and limit tensile strain of HMAC are smaller than those of matrix asphalt concrete, and HMAC can better resist the fatigue damage than matrix asphalt concrete.

A method is developed for physicomechanical investigations in surface layer where the nonwoven material is strained under free and constrained performance conditions. The mechanism of nondestructive control of points of fixation of polyester fibres to the melt is proposed and validated and the bonds between the fibres are determined by analysis of photmicrographs of the nonwoven structure. The mathematical model is broadened for predicting compressive and tensile strain of nonwovens as a function of their pore size and size-wise pore distribution.

Lattice oxygen activity plays a dominant role in balancing discharge capacity and performance decay of lithium-rich layered oxide cathodes (LLOs). On the basis of density functional theory (DFT) and tight-binding theory, the activity of lattice oxygen can be improved by tensile strain and suppressed by compressive strain. To verify this conclusion, LLOs with large lattice parameters (L-LLOs) were synthesized taking advantage of the lattice expansion effect in nanomaterials. Compared with conventional LLOs with small lattice parameters (S-LLOs), particles in L-LLOs are imposed by tensile strain. L-LLOs show a larger initial discharge capacity and decay faster in the prolonged cycles than S-LLOs. Actually, most of the modified methods in LLOs can come down to strain-induced changes in lattice parameters. We believe this conclusion is a useful guideline to understand and tailor the lattice oxygen activity and may be generalized to other layered oxide cathodes involving anionic redox.

Ultrafine-grained materials with nanotwins are expected to produce a remarkable combination of strength and ductility. In the present study, ultrafine-grained CoCrNi medium-entropy alloy with nanotwins is fabricated by high-pressure torsion followed by annealing; and investigated for cryogenic tensile properties. The alloy exhibits superior cryogenic tensile properties with a tensile strength of ~2 GPa and tensile strain of ~27%. The cryogenic tensile strength of ultrafine-grained sample increased by 67% as compared to the cryogenic tensile strength of coarse-grained sample due to fine grain size, annealing nanotwins, residual dislocation density, and strong temperature dependence of yield strength.

Stress-induced martensite aging along the [110]B2||[100]L10-direction in compression was employed to enhance the functional properties of Ni51Fe18Ga27Co4 single crystals. Stress-induced martensite aging induces two effects. Firstly, a two-way shape memory effect with a reversible compressive strain of −4.3% along the [110]В2 direction and a reversible tensile strain of +9.0% along the normal [001]B2-direction. Secondly, rubber-like behavior with giant reversible compression strain up to −15.0% along the [100]B2-direction caused by L10-martensite variant reorientation was observed. This exceeds the maximum compressive transformation strain (−6.3%) during the B2-L10 martensitic transformation by a factor of two.