Different Levels Of Strain Research Articles

Synergistic Effects of Pea Protein on the Viscoelastic Properties of Sodium Alginate Gels: Findings from Fourier Transform Infrared and Large-Amplitude Oscillatory Shear Analysis

The rheological characteristics of pea protein (PP100%) and alginate (AG100%) as pure and mixed gels with different levels of pea protein (AP90:10, AP80:20, and AP70:30) were investigated via large-amplitude oscillatory shear (LAOS) and Fourier transform infrared (FTIR). Small-angle oscillatory shear (SAOS) was carried out for the samples, and a slight frequency dependence of the storage modulus (G′) and the loss modulus (G″) was observed for the pastes and gels, indicating the formation of a weak network, which is crucial for understanding the gel’s mechanical stability under small levels of deformation. Elastic and viscous Lissajous curves from the LAOS measurement at different levels of strain (1 to 1000%) elucidated that the mixed gels formed a strong network, which showed breakdown at high deformation (>100% strain). The synergistic strengthening of the network of the mixture was noticeable in the Fourier transform and Chevyshev harmonic analyses. This analysis indicated that the nonlinearity of e3/e1 and v3/v1 started at higher levels of strain for the mixed gels. The FTIR spectra revealed that there was no strong interconnection by crosslinking between pea protein and sodium alginate, indicating that the synergistic effect mainly came from electrostatic interactions. These findings suggest that combining alginate with pea protein can enhance the mechanical properties of gels, making them suitable for various food applications.

High-precision and high-accuracy stereophotogrammetric image analysis for small to large strain deformation measurement in triaxial apparatus

A deformation measurement system for laboratory soil testing based on stereophotogrammetric image analysis was developed with a purpose of characterising soil behaviour continuously from small to large strains. The system is applicable to triaxial tests with pressure chamber and confining fluid by correcting the refraction-induced distortion of images by ray tracing. In comparison to similar existing studies, the present study put priority in precision and accuracy in relative displacement tracking, which is the key feature in resolving small strain in soil specimen and characterising its stiffness. The displacement tracking is performed with a hybrid algorithm combining Particle Tracking Velocimetry (PTV) for primary target matching and subpixel Digital Image Correlation (DIC) for more precise image matching. The deformation of clay samples with and without end lubrication was compared by visualising the deformation at different levels of strain. This paper is basically a summary of Nishimura (2022). Another example of application in laboratory testing involving fine particle suffusion is also shown. Some notes on implementation of the technique for good practice and on future development are additionally described.

Insight to motor clutch model for sensing of ECM residual strain

The mechanical microenvironment strongly affects cell state and decisions. Cell mechanosensing has been described by a molecular clutch which gets progressively engaged depending upon the stiffness of the extracellular material. Through the actuation of pulling forces exerted by actin fibres on the mechanosensitive talin-integrin molecular complex, cells sense and react to the stiffness of their surroundings. However, whether the truly cell mechanosensing is regulated by the pure elastic stiffness or by the strain energy density of the ECM is still debated. Here we report that the cell response to change of strain energy density out of loading induced deformation (purely elastic) can be accounted for by including, within the same frame of the molecular clutch model, the residual strain/stress to which the ECM could be subjected before establishing any interaction with the molecular clutches. To include the contribution of residual stresses, an additional spring orthogonal to the ones already present in the original clutch model has been introduced; this spring takes memory of the ECM strain energy when axially deformed before any interaction with cell molecular clutches can occur. To evaluate the influence of strain on the optimum number of clutches, the model has been implemented with different levels of strain. Results suggest that cells undergo a reinforcement process, stiffening the cytoskeleton in response to the ECM stress/strain energy.

DIURNAL VARIATIONS OF ATMOSPHERIC PRESSURE IN SIEDLCE IN 2001–2022

Aim of the study: Rising and falling atmospheric pressure usually heralds changes in weather conditions such as temperature, air humidity, cloud cover, precipitation, and wind speed. The work presents variation in atmospheric pressure in Siedlce from 2001 to 2022. The objective of the present work is to analyse the diurnal variation in atmospheric pressure, as well as the amplitude of fluctuations and trends. Material and methods: Daily atmospheric pressure values were obtained from a meteorological station of the Institute of Meteorology and Water Management (IMGW). Diurnal changes in atmospheric pressure causing different levels of strain on the human body, ranging from weak to very strong, were identified. For each month, the number of days with specific diurnal pressure changes was calculated. The trend in monthly pressure changes was determined based on linear regression equations. Results and conclusions: The average annual atmospheric pressure at sea level in Siedlce was 1016 hPa, the lowest and highest recorded pressure values being, respectively, 928 hPa on 25th March, 2016, and 1051 hPa on 23rd January 2006. The difference between the highest and lowest pressure values in a given month was the greatest in January and February (40 hPa), it being the lowest in August (17 hPa). The summer months of July and August, classified as weak stimulus days, exhibited the greatest diurnal variation in atmospheric pressure, while December and January were very strong stimulus days, showed the highest variation. Monthly atmospheric pressure values in Siedlce displayed no substantial tendency for changes during the study period.

A novel active continuous-wave FLRD strain sensor based on frequency-shifted interferometry

ABSTRACT An active continuous-wave fiber loop ringdown strain sensor based on frequency-shifted interferometry is presented and experimentally investigated. By measuring the decay rate of the continuous light in the ringdown loop (RDL), the sensor achieves strain measurement without optical pulsation and rapid detection. A bidirectional erbium-doped fiber amplifier is embedded in the loop to form an active fiber RDL, to compensate the inherent loop loss. The strain sensor head was built by splicing a segment of normal graded index multimode fiber (MMF) into the RDL composed of single-mode fiber. In this configuration, the core-cladding mode conservation and insertion loss of the MMF changes with the strain applied, making it possible to detect different levels of strains. The proposed device was tested with the strains in the range from 0 to 2.25 mϵ, which exhibits a linear response with a sensitivity of 0.29 km-1·mϵ-1, with a measurement resolution of 22 mϵ.

Insight into B S ratio model and surface atom interactions of co-doping diamond: First-principles studies

The complex co-doping structure of boron and sulfur is investigated using the density functional theory approach. Different ratio models show significant differences in electronic properties. More importantly, the interactions of boron, sulfur, and carbon atoms are studied on intrinsic/B-doped (001), (111), and (110) diamond surfaces. The most stable adsorption site, adsorption structure, and charge transfer are discussed. B atom induces a larger adsorption energy (intrinsic: −4.57 eV, −4.56 eV, and −4.00 eV; B-doped: −4.70 eV, −4.72 eV, and −4.86 eV). And a larger charge transfer between diamond and S radicals is also found. Therefore, the phenomenon that the sulfur contents in diamond increases after the introduction of boron in the experiment can be explained. Considering different crystal surfaces, larger adsorption strength is obtained from (111) and (110) surface. And different levels of strain are introduced into three different surfaces. The migration barrier of S atom is also considered. The lowest migration barrier is 0.06 eV on (111) surface, whereas the highest value is found on (001) surface (1.96 eV). B atom also benefits for the HxS radical adsorption. It can be concluded that B doping can help with S and HxS adsorption. This study can provide an explanation for the increased solubility of S on B-doped diamond.

AP-HTPB propellant combustion under strain conditions with laser absorption spectroscopy.

Understanding the combustion behaviors of solid propellant with different levels of strains is of practical interest. In this work, an experimental study of the effects of static and dynamic strains on the burning rate, temperature, CO, and C O 2 formation of aluminized ammonium perchlorate (AP)-hydroxyl terminated poly-butadiene (HTPB) propellant combustion was presented at initial pressures of 0.1MPa, 0.2MPa, and 0.5MPa. The strains were being applied onto solid propellant by exerting static and cyclic loadings. The propellant burning rate was acquired by a 4kHz high-speed photography system, and the combustion temperature, CO, and C O 2 column densities were measured at 10kHz through laser absorption spectroscopy (LAS). At atmospheric pressure, it was demonstrated that the propellant burning rate increased with tensile stress and decreased with compressive stress. The measured flame temperature showed a similar correlation with strains as compared to the propellant burning rate. At elevated pressures, the increase of the propellant burning rate due to tensile stress was more evident, while the difference in combustion temperatures was less significant. For the cyclic strain condition, the variations of the measured C O 2 and CO column densities were consistent with the static strain condition.

Highly Sensitive, Stretchable, and Robust Strain Sensor Based on Crack Propagation and Opening.

Soft and stretchable strain sensors have been attracting significant attention. However, the trade-off between the sensitivity (gauge factor) and the sensing range has been a major challenge. In this work, we report a soft stretchable resistive strain sensor with an unusual combination of high sensitivity, large sensing range, and high robustness. The sensor is made of a silver nanowire network embedded below the surface of an elastomeric matrix (e.g., poly(dimethylsiloxane)). Periodic mechanical cuts are applied to the top surface of the sensor, changing the current flow from uniformly across the sensor to along the conducting path defined by the open cracks. Both experiment and finite element analysis are conducted to study the effect of the slit depth, slit length, and pitch between the slits. The stretchable strain sensor can be integrated into wearable systems for monitoring physiological functions and body motions associated with different levels of strain, such as blood pressure and lower back health. Finally, a soft three-dimensional (3D) touch sensor that tracks both normal and shear stresses is developed for human-machine interfaces and tactile sensing for robotics.

Mechanical strain modulates extracellular matrix degradation and byproducts in an isoform-specific manner

Many studies have shown that mechanical forces can alter collagen degradation by proteases, and this mechanochemical effect may potentially serve an important role in determining extracellular matrix content and organization in load-bearing tissues. However, it is not yet known whether mechano-sensitive degradation depends on particular protease isoforms, nor is it yet known whether particular degradation byproducts can be altered by mechanical loading. In this study, we tested the hypothesis that different types of proteases exhibit different sensitivities to mechanical loading both in degradation rates and byproducts. Decellularized porcine pericardium samples were treated with human recombinant matrix metalloproteinases-1, −8, −9, cathepsin K, or a protease-free control while subjected to different levels of strain in a planar, biaxial mechanical tester. Tissue degradation was monitored by tracking the decay in mechanical stresses during displacement control tests, and byproducts were assessed by mass spectrometry analysis of the sample supernatant after degradation. Our key finding shows that cathepsin K-mediated degradation of collagenous tissue was enhanced with increasing strain, while MMP1-, MMP8-, and MMP9-mediated degradation were first decreased and then increased by strain. Degradation induced changes in tissue mechanical properties, and proteomic analysis revealed strain-sensitive degradome signatures with different ECM byproducts released at low vs. high strains. This evidence suggests a potentially new type of mechanobiology wherein mechanical forces alter the degradation products that can provide important signaling feedback functions during tissue remodeling.

A comparative study on the effect of grid printing methods and camera hardware in automatic strain measurement through CGA

Strain analysis is an important step in sheet metal forming operations to identify the potential locations of failure. Circle grid analysis is a widely used method to evaluate the strains in sheet metal forming, where deformed circles on a formed component are measured to evaluate the strains at different locations. In this paper, two different USB cameras are used to capture the images of the deformed grids. The images are processed using the in-house software developed in MATLAB for strain measurement. The effect of image acquisition hardware and grid printing methods on strain measurement accuracy has been analyzed. For this, the sheets are printed with circular grids by screen printing, laser engraving, and electrochemical etching. The sheets are then deformed in incremental forming to produce different levels of strain in the formed components. The deformed grids on the formed components are captured using proposed USB cameras with appropriate attachments and processed by in-house strain measurement software. The strain measured using proposed hardware and software is also compared with the commercial strain measurement system. The mean absolute percentage error in strain measurement with the proposed USB cameras was found to be 0.671 and 0.761. The statistical results show that there is no evidence to support the hypothesis that the two hardware perform differently on average. Hence, the proposed hardware and software can be used in industry and research laboratories for strain analysis in sheet metal forming operations.

COVID-19 impact on New Zealand general practice: rural-urban differences.

In countries such as New Zealand, where there has been little community spread of COVID-19, psychological distress has been experienced by the population and by health workers. COVID-19 has caused changes in the model of care that is delivered in New Zealand general practice. It is unknown, however, whether the changes wrought by COVID-19 have resulted in different levels of strain between rural and urban general practices. This study aims to explore these differences from the impact of COVID-19. This study is part of a four-country collaboration (Australia, New Zealand, Canada and the USA) involving repeated cross-sectional surveys of primary care practices in each respective country. Surveys were undertaken at regular intervals throughout 2020 of urban and rural general practices throughout New Zealand. Five core questions were asked at each survey, relating to experiences of strain, capacity for testing, stressors experienced, types of consultations being carried out and numbers of patients seen. Simple descriptive statistics were used to analyse the data. A total of 1516 responses were received with 20% from rural practices. A moderate degree of strain was experienced by general practices, although rural practices appeared to experience less strain compared to urban ones. Rural practices had fewer staff absent from work, were less likely to use alternative forms of consultations such as video consultations and telephone consultations, and had possibly lower reductions in patient volumes. These variations might be related to personal characteristics of rural as compared to urban practices or different models of care. New Zealand rural general practice appeared to have a different response to the COVID-19 pandemic compared to urban general practice, illustrating the significant strengths and resilience of rural practices. While different experiences from COVID-19 might reflect differences in the demographics of the rural and urban general practice workforce, another proposition is that this difference indicates a rural model of care that is more adaptive compared to the urban one. This is consistent with the literature that rural general practice has the capacity to manage conditions in a different way to urban. While other comparable countries have demonstrated a unique rural model of care, less is known about this in New Zealand, adding weight to an argument to further define New Zealand rural general practice.

The effect of different levels of pre-damage loading on the strength and structural behavior of CFRP strengthened R.C. beams: Experimental and analytical investigation.

In order to investigate the effect of pre-loading damage on the structural performance of Carbon Fiber Reinforced Polymer (CFRP) strengthened Reinforced Concrete (R.C.) beams, experimental and Finite Element Modelling (FEM) investigation was carried out on six R.C. beams. Five of the R.C. beams were damaged up to different levels of strain in the main steel bars before Flexure CFRP strengthening. One of the R.C. beams loaded up to failure and was kept as a control beam for comparison. The experimental results showed that the failure mode of the CFRP strengthened specimen was controlled by CFRP debonding followed by concrete crushing; however, the control beam failed in concrete crushing after yielding the steel bars, which is a ductile failure. The CFRP sheet increases the strength and initial stiffness of the R.C. beams and reduces ductility and toughness. Also, CFRP application increases the first crack and yielding steel bars load by 87.4% and 34.4%, respectively. Furthermore, the pre-damage level does not influence the strength and ductility of the strengthened R.C. beams except for the highest damage levels, which experienced a slight decrease in load capacity and ductility. However, the initial stiffness decreases with increasing pre-damage levels by 40%.Design guideline ACI 440.2R (2004) predicts the ultimate load capacity marvelously for externally bonded Fiber-Reinforced Polymer (FRP) beams compared to the experimental maximum load capacity. The excellent agreement between experimental and FEM results indicates that the constitutive models used for concrete and reinforcement and the cohesive interface model can well capture fracture behavior. However, The FEM analysis predicts the beam to be slightly stiffer and more robust, probably because of the assumed perfect bond between concrete and reinforcement. The developed FEM can be used for further parametric study.

Large eddy simulation of premixed turbulent combustion using a non-adiabatic, strain-sensitive flamelet approach

In this study, a novel strained, non-adiabatic flamelet generated manifold (FGM) model is developed based on a counterflow premixed flame. The different levels of strain and heat loss are introduced into the flamelets by varying the stagnation point strain rate and burnt temperature of the counterflow configuration. The strain rate response of these flamelets is found to exhibit different extinction patterns for different ranges of burnt temperature. A priori studies are performed to compare the phase-space flame structures of the strained and unstrained flamelets. It is found that the strained flamelet degenerates towards the unstrained flamelet with burnt temperature decreasing. A bifurcation burnt temperature is further defined that separates the two types of flamelet quenching that are driven by strain and heat loss. An appropriate set of tabulation parameters is chosen that preserves the uniqueness of mapping between the manifold and the populated flamelets. The external boundaries of the tabulations are defined, where the proposed model degenerates into the conventional unstrained/non-adiabatic FGM manifold. Internal tabulation boundaries are defined to distinguish different combustion modes among stable combustion, strain-induced quenching, and heat-loss-induced quenching. The model is validated using large eddy simulation (LES) of a confined turbulent premixed jet flame. The proposed FGM model vastly increases accuracy of predictions when both strain and heat loss effects are included. Without accounting for these effects, there are discrepancies in the prediction of flame height and temperature as compared with experimental data. An analysis of the dominant physical process (strain, heat loss) that contributes to the evolution of the turbulent flame is performed.

Evaluation of mechanical ductile damage in sheet metal based on low-field magnetic analysis

This study proposes the application of low-field magnetic analysis (LFMA) as an alternative non-destructive testing method based on magnetic flux density for the detection of mechanical ductile damage in sheet metal under uniaxial stress. Ductile damage is related to the development of micro-voids and pores due to large plastic strains. The samples were strained to different levels of strains up to 21% and studied with LFMA after unloading. Our approach is based on the assumption that as the plastic strain in steel increases, more damage is accumulated in the microstructure and therefore the magnetic properties are modified. Numerical simulation using finite element method, as well as experimental measurements such as tensile test, hardness, X-ray diffraction and electrical resistivity, were also applied to validate the proposed method in the detection of damage in tensile sample. It was found that the magnetic flux density indeed varies proportionally to the strain (72.3–63.4 mT (0–12.4% damage) for H = 243.2 Oe). These results demonstrate that the LFMA can be used to evaluate mechanical damages caused by plastic strain changes induced on steel. Furthermore, the LFMA presents accurate results for low magnetic fields with high sensitivity and reliability.

Influence of rolling temperature and strain on the microstructural evolution and mechanical properties in quench and partition (Q&P) steels

Three different compositions of C–Mn–Si–Al type Q&P steels, A, B and C, were subjected to thermo-mechanically controlled processing (TMCP) at two different rolling temperatures viz. 1075 °C and 1150 °C, using two different levels of strain 0.51 and 1.1, given in single pass, followed by direct quench and partitioning (DQP) to produce a martensite – austenite structure. It was observed that Si and Al significantly influenced the formation of prior austenite grains (PAGs) during TMCP and thereby the evolution of microstructure after the subsequent Q&P treatment. With the help of constitutive models, it was found that mainly dynamic recrystallization (DRX) along with/without meta-dynamic recrystallization (MRX) were likely to occur during TMCP and their effects would be retained by immediate quench from the high temperature of processing. Electron back-scattered diffraction (EBSD) results confirmed that the PAGs were essentially DRX grains. Rolling at the lower temperature produced finer PAGs, thereby favouring the formation of larger amount of retained austenite. Effect of strain, which enhanced the enrichment of carbon in the austenite, was more pronounced at the lower rolling temperature and at higher applied strain. More than the grain refinement, dislocation density was found to be the dominant strengthening mechanism in the martensite. A maximum dislocation density of 2.18 × 1015 m−2 was observed for the steel rolled with 1.1 strain at 1150 °C. Higher rolling temperature favoured higher dislocation density in the steels, owing to the attainment of higher martensite carbon content. Consequently, TMCP with a higher rolling temperature favoured higher strength properties. In fact, the maximum strength of 1593 MPa, with yield strength of 1042 MPa and total elongation of 13% were achieved in Steel-A rolled at 1150 °C with 1.1 strain (1.1-DQP-1150 °C Steel A). After evaluating the different strengthening mechanisms operating in these steels, it was concluded that the maximum strength achieved in Steel A was primarily due to its alloy composition.

Regulation of vertical and biaxial strain on electronic and optical properties of G-GaN-G sandwich heterostructure

Recently, the two-dimensional heterostructure is a research hot spot of semiconductor materials, and it has wide application prospects in electronic devices and photocatalysis. In this work, we constructed novel graphene-GaN-graphene (G-GaN-G) sandwich heterostructure, and the electronic and optical properties have been theoretically investigated based on the first principles calculations. The computation results indicate that the heterostructure is most stable when interlayer distance d0 is 3.189 A, and electronic and optical properties of intrinsic GaN and graphene are well preserved. In addition, the effect of vertical and biaxial strain on the G-GaN-G heterostructure is also investigated, we find that strain can effectively regulate the electronic and optical properties. Therefore, the electronic and optical properties of G-GaN-G can be tuned by applying different levels of strain to meet the needs of devices. This study results reveal that the G-GaN-G sandwich heterostructure can be hopefully applied to ultraviolet photodetectors and optoelectronic devices.

Self-Reported Health and Well-Being Across Heterogeneous Groups of Caregivers

Using the Caregiving Transitions Study (CTS) we compared the effects of caregiving on self-reported health and well-being in caregivers reporting providing dementia care, different levels of strain and amount of care provided. Caregivers (n-251) were 65% female, 36% African American and had a mean age of 71.8 years. A quarter of CGs reported being under a lot of strain and 47% provided care for persons with dementia. Dementia CGs (n=117) provided more hours of care per week (49.7 versus 37.7, p=0.001), more commonly reported high strain (36.8% versus 15.7%, p<0.03) and were more than twice as likely as non-dementia caregivers to report that caregiving interfered with taking care of their own health (33.9% versus 15.4%, p=0.003). Additional results will be reported on how these factors of dementia caregiving, level of strain, and hours of care affect well-being including perceived stress, treatment burden, depressive symptoms and health-related quality of life.

Characterization of material strain and thermal softening effects in the cutting process

Accurate descriptions of workpiece behaviors are indispensable for achieving reliable simulations of the cutting process. However, the material plastic constitutive models obtained through conventional material tests do not apply in the ranges of strain and strain rate encountered in the realistic machining processes. To address this issue, in this study, we attempt to develop a methodology to understand and identify the plastic deformation behaviors based on high-speed filming and induction preheating during the cutting tests. Different levels of strain, strain rate, and temperature are realized by varying the rake angle, cutting velocity, and initial workpiece temperature, respectively. The plastic deformation and temperature rise in the primary shear zone are characterized by the fine-scale digital image correlation technique and heat convection–conduction equation, respectively, thus rendering the machining test into a high-dynamic-material testing method. The material exhibits strain softening in the primary shear zone and a reduced thermal softening effect under rapid heating conditions. These initial findings can deepen the understanding of material behaviors during the cutting process and can be further developed for implementation in numerical machining models.

Efficient Hydrogen Oxidation Catalyzed by Strain‐Engineered Nickel Nanoparticles

AbstractThe hydroxide‐exchange membrane fuel cell (HEMFC) is a promising energy conversion device. However, the development of HEMFC is hampered by the lack of platinum‐group‐metal‐free (PGM‐free) electrocatalysts for the hydrogen oxidation reaction (HOR). Now, a Ni catalyst is reported that exhibits the highest mass activity in HOR for a PGM‐free catalyst as well as excellent activity in the hydrogen evolution reaction (HER). This catalyst, Ni‐H2‐2 %, was optimized through pyrolysis of a Ni‐containing metal‐organic framework precursor under a mixed N2/H2 atmosphere, which yielded carbon‐supported Ni nanoparticles with different levels of strains. The Ni‐H2‐2 % catalyst has an optimal level of strain, which leads to an optimal hydrogen binding energy and a high number of active sites.

Efficient Hydrogen Oxidation Catalyzed by Strain-Engineered Nickel Nanoparticles.

The hydroxide-exchange membrane fuel cell (HEMFC) is a promising energy conversion device. However, the development of HEMFC is hampered by the lack of platinum-group-metal-free (PGM-free) electrocatalysts for the hydrogen oxidation reaction (HOR). Now, a Ni catalyst is reported that exhibits the highest mass activity in HOR for a PGM-free catalyst as well as excellent activity in the hydrogen evolution reaction (HER). This catalyst, Ni-H2 -2 %, was optimized through pyrolysis of a Ni-containing metal-organic framework precursor under a mixed N2 /H2 atmosphere, which yielded carbon-supported Ni nanoparticles with different levels of strains. The Ni-H2 -2 % catalyst has an optimal level of strain, which leads to an optimal hydrogen binding energy and a high number of active sites.