Pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy for activating water and urea oxidation

Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water electrolysis.Herein,we use the pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy activated by NiFe_(2)O_(4)(FeNi/NiFe_(2)O_(4)@NC)for efficiently increasing the performance of water and urea oxidation.Due to the tensile strain effect on FeNi/NiFe_(2)O_(4)@NC,it provides a favorable modulation on the electronic properties of the active center,thus enabling amazing OER(η_(100)=196 mV)and UOR(E_(10)=1.32 V)intrinsic activity.Besides,the carbon-coated layers can be used as armor to prevent FeNi alloy from being corroded by the electrolyte for enhancing the OER/UOR stability at large current density,showing high industrial practicability.This work thus provides a simple way to prepare high-efficiency catalyst for activating water and urea oxidation.

Tensile Strain Capacity Prediction of Engineered Cementitious Composites (ECC) Using Soft Computing Techniques

Plain concrete is strong in compression but brittle in tension,having a low tensile strain capacity that can significantly degrade the long-term performance of concrete structures,even when steel reinforcing is present.In order to address these challenges,short polymer fibers are randomly dispersed in a cement-based matrix to forma highly ductile engineered cementitious composite(ECC).Thismaterial exhibits high ductility under tensile forces,with its tensile strain being several hundred times greater than conventional concrete.Since concrete is inherently weak in tension,the tensile strain capacity(TSC)has become one of the most extensively researched properties.As a result,developing a model to predict the TSC of the ECC and to optimize the mixture proportions becomes challenging.Meanwhile,the effort required for laboratory trial batches to determine the TSC is reduced.To achieve the research objectives,five distinct models,artificial neural network(ANN),nonlinear model(NLR),linear relationship model(LR),multi-logistic model(MLR),and M5P-tree model(M5P),are investigated and employed to predict the TSCof ECCmixtures containing fly ash.Data from115 mixtures are gathered and analyzed to develop a new model.The input variables include mixture proportions,fiber length and diameter,and the time required for curing the various mixtures.The model’s effectiveness is evaluated and verified based on statistical parameters such as R2,mean absolute error(MAE),scatter index(SI),root mean squared error(RMSE),and objective function(OBJ)value.Consequently,the ANN model outperforms the others in predicting the TSC of the ECC,with RMSE,MAE,OBJ,SI,and R2 values of 0.42%,0.3%,0.33%,0.135%,and 0.98,respectively.

Study of valence intersubband absorption in tensile strained Si/SiGe quantum wells

The hole subband structures and effective masses of tensile strained Si/Sil-yGey quantum wells are calculated by using the 6 × 6 k·p method. The results show that when the tensile strain is induced in the quantum well, the light-hole state becomes the ground state, and the light hole effective masses in the growth direction are strongly reduced while the in-plane effective masses are considerable. Quantitative calculation of the valence intersubband transition between two light hole states in a 7nm tensile strained Si/Si0.55Ge0.45 quantum well grown on a relaxed Si0.5Ge0.5 （100） substrates shows a large absorption coefficient of 8400 cm^-1.

Valence band structure and density of states effective mass model of biaxial tensile strained silicon based on k·p theory

After constructing a stress and strain model, the valence bands of in-plane biaxial tensile strained Si is calculated by k·p method. In the paper we calculate the accurate anisotropy valance bands and the splitting energy between light and heavy hole bands. The results show that the valance bands are highly distorted, and the anisotropy is more obvious. To obtain the density of states （DOS） effective mass, which is a very important parameter for device modeling, a DOS effective mass model of biaxial tensile strained Si is constructed based on the valance band calculation. This model can be directly used in the device model of metal-oxide semiconductor field effect transistor （MOSFET）. It also a provides valuable reference for biaxial tensile strained silicon MOSFET design.

The role of strain in oxygen evolution reaction

The oxygen evolution reaction(OER)is a crucial step in metal-air batteries and water splitting technologies,playing a significant role in the efficiency and achievable heights of these two technologies.However,the OER is a four-step,four-electron reaction,and its slow kinetics result in high overpotentials,posing a challenge.To address this issue,numerous strategies involving modified catalysts have been proposed and proven to be highly efficient.In these strategies,the introduction of strain has been widely reported because it is generally believed to effectively regulate the electronic structure of metal sites and alter the adsorption energy of catalyst surfaces with reaction intermediates.However,strain has many other effects that are not well known,making it an important yet unexplored area.Based on this,this review provides a detailed introduction to the various roles of strain in OER.To better explain these roles,the review also presents the definition of strain and elucidates the potential mechanisms of strain in OER based on the d-band center theory and adsorption volcano plot.Additionally,the review showcases various ways of introducing strain in OER through examples reported in the latest literature,aiming to provide a comprehensive perspective for the development of strain engineering.Finally,the review analyzes the appropriate proportion of strain introduction,compares compressive and tensile strain,and examines the impact of strain on stability.And the review offers prospects for future research directions in this emerging field.

Direct-bandgap electroluminescence from tensile-strained Ge/SiGe multiple quantum wells at room temperature

Tensile-strained Ge/SiGe multiple quantum wells （MQWs） were grown on a Ge-on-Si virtual substrate using ultrahigh vacuum chemical vapor deposition on an n＋-Si （001） substrate. Direct-bandgap electroluminescence from the MQWs light emitting diode was observed at room temperature. The quantum confinement effect of the direct-bandgap transitions is in good agreement with the theoretical calculated results. The redshift mechanism of emission wavelength related to the thermal effect is discussed,

Cell membrane tensile strain under cyclic compression:A viscoelastic myoblast finite element model

Cyclic mechanical stimulation could lead to subsequent biomechanical and biological effects on cells.Viscoelastic cells could deform or show energy dissipation with hysteresis behavior in response to external cyclic compression.The aim of this study was to investigate the effect of cyclic compression on a single viscoelastic myoblast through a confocal–based cell–specific finite element model,including cell membrane tensile strain and damaged elements.Sinusoidal compression was applied to the apical surface of the myoblast(cell membrane)with compressive stress of 500
500 Pa(with stress offset at 500 Pa and amplitude of 500 Pa)at 0 Hz(static compression of 500 Pa),0.25 Hz,0.5 Hz,0.75 Hz,1 Hz,5 Hz,and 10 Hz.Results showed that the ratio of average tensile strain integral in all cell membrane elements over a certain period of time(T)to that duration(T)(MAS index)decreased under cyclic compression compared to that of static compression in the short term(within 4 s).Furthermore,compared to static compression,the percentage of damaged elements of cell membrane under cyclic compression decreased assuming a 3%cell membrane tensile strain damage threshold.The optimal cyclic compression frequency 0.25 Hz led to the largest difference of MAS index under cyclic compression and static compression.These results may provide support for the application of cyclic compressive stimulation in the prevention of cell damage.

ON THE TENSILE MECHANICAL PROPERTY OF Si-Mn TRIP STEELS AT HIGH STRAIN RATE

Tensile mechanical properties of 1.6Si-1.58Mn-0.195C TRIP (transformation-induced plasticity) steels under high strain rate and effects of DP (dual-phase) treatments were studied and compared to the quasi-static tensile behavior. The results show that the increasing of strain rate leads to increasing in their strengths and decreasing in the uniform elongation remarkably. Because the stable retained austenite in TRIP steel can transform to martensite during tensile testing and the material exhibits excellent characteristic of transformation induced plasticity, the plastic deformation behavior is evidently improved and the combination of strength and elongation is superior to that of dual-phase steel, although its strength is smaller than that of DP steel. However, DP treated steel shown lower elongation under dynamic tension in spite of higher strength. A model was proposed to explain the excellent elongation rate of TRIP steel compared with DP steel on the basis of SEM analysis and the strength of the components in microstructure.

Effects of Strain Rate and Texture on the Tensile Behavior of Pre-strained NiCr Microwires

The stress–strain behavior and strain rate sensitivity of pre-strained Ni80Cr20（Ni20Cr） were studied at strain rates from 4.8×10^（–4）s^（–1） to 1.1×10^（–1）s^（–1）. Specimens were prepared through cold drawing with abnormal plastic deformation. The texture of the specimen was characterized using electron backscatter diffraction. Results revealed that the ultimate tensile strength and ductility of the pre-strained Ni20Cr microwires simultaneously increased with increasing strain rate. Twinning-induced negative strain rate sensitivity was discovered. Positive strain rate sensitivity was present in fracture flow stress, whereas negative strain rate sensitivity was detected in flow stress values of σ_（0.5%） and σ_（1%）. Tensile test of the pre-strained Ni20Cr showed that twinning deformation predominated, whereas dislocation slip deformation dominated when twinning deformation reached saturation. The trends observed in the fractions of 2°-5°, 5°-15°, and 15°-180° grain boundaries confirmed that twinning deformation dominated the first stage.

Stress and strain analysis on the anastomosis site sutured with either epineurial or perineurial sutures after simulation of sciatic nerve injury

The magnitude of tensile stress and tensile strain at an anastomosis site under physiological stress is an important factor for the success of anastomosis following suturing in peripheral nerve injury treatment. Sciatic nerves from fresh adult cadavers were used to create models of sciatic nerve injury. The denervated specimens underwent epineurial and perineurial suturing. The elastic modulus （40.96 ＋ 2.59 MPa） and Poisson ratio （0.37 ＋ 0.02） of the normal sciatic nerve were measured by strain electrical measurement. A resistance strain gauge was pasted on the front, back left, and right of the edge of the anastomosis site after suturing. Strain electrical measurement results showed that the stress and strain values of the sciatic nerve following perineurial suturing were lower than those following epineurial suturing. Scanning electron microscopy revealed that the sciatic nerve fibers were disordered following epineurial compared with perineurial suturing. These results indicate that the effect of perineurial suturing in sciatic nerve injury repair is better than that of epineurial suturing.

Uneven deposition on the Al electrode under tension strain

Structural deformation and dendrite formation, which would impact the electrochemical processes of rechargeable metal batteries, are usually observed in the high-energy density metal electrodes. Herein,we design an in-situ optical mechano-electrochemical system to study Al deposition on the Al electrode in non-aqueous Al batteries under non-uniform strain. Inhomogeneous distribution of applied strain is realized by creating an oval hole in the Al electrode. The results of the in-situ experiments suggest that the dense Al deposition, which is related to the evolution of surface morphology and increasing reactive sites, is achieved in the regions of stress concentration. The evolution of surface morphology is monitored by the in-situ tension experiments using scanning electron microscope and atomic force microscope.Besides, a qualitative mathematical model is employed to analyze the changes of the local reaction rate owing to the changed surface morphology and the cracks of oxide film under tensile stress. The results are useful to understand the Al deposition when the mechanical force is applied to the metal electrode.

Strain-induced magnetism in ReS_2 monolayer with defects

We investigate the effects of strain on the electronic and magnetic properties of ReS2 monolayer with sulfur vacancies using density functional theory.Unstrained ReS2 monolayer with monosulfur vacancy（Vs） and disulfur vacancy（V（2S））both are nonmagnetic.However,as strain increases to 8%,VS-doped ReS2 monolayer appears a magnetic half-metal behavior with zero total magnetic moment.In particular,for V（2S）-doped ReS2 monolayer,the system becomes a magnetic semiconductor under 6%strain,in which Re atoms at vicinity of vacancy couple anti-ferromagnetically with each other,and continues to show a ferromagnetic metal characteristic with total magnetic moment of 1.60μb under 7%strain.Our results imply that the strain-manipulated ReS2 monolayer with VS and V（2S） can be a possible candidate for new spintronic applications.

Deformation behaviour in advanced heat resistant materials during slow strain rate testing at elevated temperature

In this study, slow strain rate tensile testing at elevated temperature is used to evaluate the influence of temperature and strain rate on deformation behaviour in two different austenitic alloys. One austenitic stainless steel （AISI 316L） and one nickel-base alloy （Alloy 617） have been investigated. Scanning electron microscopy related techniques as electron channelling contrast imaging and electron backscattering diffraction have been used to study the damage and fracture micromechanisms. For both alloys the dominante damage micromech- anisms are slip bands and planar slip interacting with grain bounderies or precipitates causing strain concentrations. The dominante fracture micromechanism when using a slow strain rate at elevated temperature, is microcracks at grain bounderies due to grain boundery embrittlement caused by precipitates. The decrease in strain rate seems to have a small influence on dynamic strain ageing at 650℃.

Self-healing of engineered cementitious composites at simulated summer conditions

Self-healing of engineered cementitious composites(ECC) subjected to a cyclic drying and wetting regime simulated summer outdoor environment was investigated in this paper.Uniaxial tension tests were used to generate multiple cracks in ECC specimens deformed to varying tensile strains.To quantify self-healing,resonant frequency measurements were conducted throughout drying-wetting cycles followed by tensile testing of self-healing ECC specimens.It was found that through self-healing the resonant frequency of ECC can recover 81% to 90% of initial values while showing a distinct rebound in stiffness of cracked ECC after self-healing.For specimens pre-loaded to high levels of strain between 2% and 3%,the tensile strain after self-healing can recover from 1.8% to 2.2%.Also,the effects of temperature during cyclic regime can lead to an increase in the ultimate strength of the material while slightly decreasing the strain-hardening capacity of ECC due to further hydration of unreacted cement and fly ash.

Effects of high temperature rapid thermal annealing on Ge films grown on Si(001) substrate

Tensile strain, crystal quality, and surface morphology of 500 nm thick Ge films were improved after rapid thermal annealing at 900 ℃ for a short period （〈 20 s）. The films were grown on Si（001） substrates by ultra-high vacuum chemical vapor deposition. These improvements are attributed to relaxation and defect annihilation in the Ge films. However, after prolonged （〉 20 s） rapid thermal annealing, tensile strain and crystal quality degenerated. This phenomenon results from intensive Si-Ge mixing at high temperature.

The Three-Stage Model Based on Strain Strength Distribution for the Tensile Failure Process of Rock and Concrete Materials

A three-stage model is introduced to describe the tensile failure process of rock and concrete materials.Failure of the material is defined to contain three stages in the model,which include elastic deformation stage,body damage stage and localization damage stage.The failure mode change from uniform body damage to localization damage is expressed.The heterogeneity of material is described with strain strength distribution.The fracture factor and intact factor,defined as the distribution function of strain strength,are used to express the fracture state in the failure process.And the distributive parameters can be determined through the experimental stress-strain curve.

Effect of hydrogen on the stress corrosion cracking behavior of X80 pipeline steel in Ku'erle soil simulated solution

Hydrogen was a key factor resulting in stress corrosion cracking （SCC） of X80 pipeline steel in Ku＇erle soil simulated solution. In this article, the effect of hydrogen on the SCC susceptibility of X80 steel was investigated further by slow strain rate tensile test, the surface fractures were observed using scanning electron microscopy （SEM）, and the fracture mechanism of SCC was discussed. The results indicate that hydrogen increases the SCC susceptibility. The SEM micrographs of hydrogen precharged samples presents a brittle quasi-cleavage feature, and pits facilitate the transgranular crack initiation. In the electrochemical impedance spectroscopy （EIS） measurement, the decreased polarization resistance and the pitting resistance of samples with hydrogen indicate that hydrogen increases the dissolution rate and deteriorates the pitting corrosion resistance. The potentiodynamic polarization curves present that hydrogen also accelerates the dissolution rate of the crack tip.

Enhanced electroluminescence from a free-standing tensilely strained germanium nanomembrane light-emitting diode

Ge has become a promising material for Si-based optoelectronic integrated circuits （OEIC） due to its pseudo-direct bandgap. In this paper we achieved tensilely strained Ge free-standing nanomembrane （NM） light- emitting diode （LED）, using silicon nitride thin film with high stress. The tensile stress in the Ge layer can be controlled by adjustable process parameters. An expected redshift of electroluminescence （EL） in Ge NM LED is observed at room temperature, which has been attributed to the shrinking of its direct bandgap relative to its indirect bandgap. An EL with dramatically increased intensity was observed around 1876 nm at a tensile strain of 1.92%, which demonstrates the direct-band recombination in tensilely strained Ge NM.

N_(2)photofixation promoted by in situ photoinduced dynamic iodine vacancies at step edge in Bi_(5)O_(7)I nanotubes

Heterogeneous photosynthesis is a promising route for sustainable ammonia production,which can utilize renewable energy and water as the hydrogen source under ambient condition.In this study,a series of Bi_(5)O_(7)I(BOI)nanosheets and nanotubes are synthesized,the surface tensile strain is formed by curling the nanosheets into nanotubes to tune the concentration and location of dynamic vacancies.Scanning transmission electron microscopy(STEM)with spherical aberration correction confirms the presence of intrinsic areal defects on the surface of the BOI nanotube resulted from surface tensile strain.The presence of areal defects lowers the formation energy of I vacancies(IV)at step edge site,thus the IV with higher concentration would be favorably generated under visible light.Rapid scan in situ Fourier transform infrared(FT-IR)analysis in the aqueous media reveals that the IV promotes photocatalytic N_(2) activation and reduction,proceeds through an associative alternating mechanism.Specially,after turning off the light,the surface vacancy sites can be reoccupied by I−ions,which enables the protection and regeneration of photocatalyst surface in an aerobic and dark environment.This work provides an innovative strategy to tune concentration and location of dynamic surface vacancies on photocatalysts by building surface tensile strain for advancing sustainable ammonia production.

Anomalous enhancement oxidation of few-layer MoS_(2)and MoS_(2)/h-BN heterostructure

Because of profound applications of two-dimensional molybdenum disulfide(MoS_(2))and its heterostructures in electronics,its thermal stability has been spurred substantial interest.We employ a precision muffle furnace at a series of increasing temperatures up to 340℃to study the oxidation behavior of continuous MoS_(2)films by either directly growing mono-and fewlayer MoS_(2)on SiO_(2)/Si substrate,or by mechanically transferring monolayer MoS_(2)or hexagonal boron nitride(h-BN)onto monolayer MoS_(2)substrate.Results show that monolayer MoS_(2)can withstand high temperature at 340℃with less oxidation while the few-layer MoS_(2)films are completely oxidized just at 280℃,resulting from the growth-induced tensile strain in few-layer MoS_(2).When the tensile strain of films is released by transfer method,the stacked few-layer MoS_(2)films exhibit superior thermal stability and typical layer-by-layer oxidation behavior at similarly high temperature.Counterintuitively,for the MoS_(2)/h-BN heterostructure,the h-BN film itself stacked on top is not damaged and forms many bubbles at 340℃,whereas the underlying monolayer MoS_(2)film is oxidized completely.By comprehensively using various experimental characterization and molecular dynamics calculations,such anomalous oxidation behavior of MoS_(2)/h-BN heterostructure is mainly due to the increased tensile strain in MoS_(2)film at elevated temperature.