Low Strain Levels Research Articles

Laboratory and Field Evaluation of Asphalt Concrete Modulus &Critical Strain Inputs for M-E Flexible Pavement Design in the State of Illinois

This study aims to update the current algorithm for modulus prediction of hot mix asphalt in the state of Illinois-USA. Numerically, laboratory, and field-obtained modulus and strain levels were connected to advances in asphalt materials and current design criteria. Four mix designs were selected and combined with seven different binders for modulus measurements. The reference experimental results were compared to: the current Illinois Department of Transportation (IDOT) modulus algorithm, traditional regression models, a Bayesian Neural Network (BNN) model, and field measurements obtained using the Traffic Speed Deflectometer. Results showed that the current IDOT algorithm under-predicts modulus and BNN (840 data points, R^2 = 0.986) outperformed the Witczak and Hirsch models. Field modulus and critical strains were sensitive to temperature and showed considerable variability, but confirmed that HMA in perpetual pavement sections performs under low strain levels. These findings guided considerations for an updated design method: realistic modulus prediction can be achieved using data-driven methods and less conservative strain criterion might be considered.

Analysis of the Ni-5%at.W Alloy Substrate Texture Evolution at Different Strain Levels Using the EBSD Technique

In this paper, the texture evolution of the Ni-5%W alloy baseband with different strain variables (εvM = 3.9, 4.9, and 5.1) during rolling and annealing was studied using the electron back scattering diffraction (EBSD) technique. The results indicate that after high-temperature annealing at 1150 °C, all three strain levels of the alloy substrates can achieve a strong cubic texture, with a content exceeding 99% (<10°). However, the texture evolution trajectory is significantly influenced by the strain level. When the content of cubic texture in the alloy substrates under strain levels of 3.9 and 5.1 is the same, significant temperature differences exist. Additionally, the different strain levels result in varying nucleation rates and growth rates of cubic texture in the Ni-5%W alloy substrates. The study reveals that in the alloy substrates under strain levels of 3.9 and 4.9, recrystallized cubic grain nuclei grow within a layered structure, resulting in larger grain sizes and lower nucleation rates. In contrast, in the alloy substrates under a strain level of 5.1, recrystallized cubic grain nuclei form from small equiaxed grains, leading to higher nucleation rates but smaller grain sizes, competing with random orientations. In the later stages of nucleation, recrystallized grains in the alloy substrates under a strain level of 5.1 exhibit a significant size advantage, rapidly growing by engulfing randomly oriented grains. Compared to the alloy substrates with lower strain levels, the recrystallized cubic grains in the alloy substrates under a strain level of 5.1 have higher nucleation rates and faster growth rates.

Are Ratings of Perceived Exertion during Endurance Tasks of Predictive Value? Findings in Trunk Muscles Require Special Attention.

Background: Subjective rating scales of perceived exertion are often used to quantify effort levels during various endurance exercises, particularly submaximal tasks. The aim of the current study was to determine whether predictive conclusions can be drawn from perceived exertion levels surveyed at the start of defined submaximal endurance tasks. Methods: In this study, healthy participants performed a 10-min endurance task at 50% of their upper body weight, targeting either the back muscles (n = 47, 24 women) or abdominal muscles (n = 32, 17 women). At the end of each minute, participants were asked to rate their perceived exertion (RPE) using the 14-points Borg Scale. Based on their initial and final RPE levels, and for each muscle group separately, participants were divided into subgroups reflecting low (good start/good end) and high (bad start/bad end) strain levels. These values were then compared over the duration of the exercise. Comparisons of RPE levels between subgroups were made using the Mann-Whitney U-test for independent samples, with Bonferroni-Holm correction to account for multiple comparisons. Results: Overall, strain levels increased throughout the duration of the exercise. For the abdominal muscles, the difference between the two RPE groups remained constant over time: participants with good start/end ratings consistently showed different strain levels from those with bad start/end ratings, regardless of whether the grouping was based on initial or final exertion levels. In contrast, for the back muscles, the initial grouping showed a crossover in strain values: by the end of the task, participants in the good start group tended to report higher strain than those in the bad start group. No differences were found in initial RPE values when the grouping was based on final exertion levels. Conclusions: For endurance tasks involving the abdominal muscles, initial strain levels have strong predictive value, whereas this is not the case for the back muscles. Because back muscles are frequently loaded, continuous monitoring of RPE levels is necessary to prevent unexpected task failure, as initial RPE values are not predictive. In contrast, RPE values of 11 or higher on the 14-points Borg scale predict complete exhaustion or even premature task failure with high certainty for abdominal muscle exercises, while lower RPE levels indicate that exercise intensity can be increased.

Assessment of aging behaviour of reclaimed asphalt binders: multi-scale mechanical and microstructural characterisation

This study provides a comprehensive multi-scale characterization of the aging resistance of reclaimed asphalt pavement (RAP) binder blends. The analysed samples included different dosages of a RAP binder and a recycling agent (REC). At low strain levels (2.5% and 5%), the use of up to 40% RAP did not adversely affect the Nf value; however, the effect of RAP was clear at 10% strain in the macro scale. At the microscopic scale, the AFM analysis showed that among all samples, the 100% RAP binder was affected the least by laboratory aging. However, the aging susceptibility increased as the RAP content increased from 0 to 40%. A plausible explanation is that the effects of laboratory aging (temperature and/or pressure) became more concentrated on the base binder when its quantity decreased in the blends. The use of REC reduced the stiffness of the unaged blends, but its effect diminished upon further aging of the blends.

Effects of cutting temperature on the genes and fatigue properties of asphalt during its refining process

Asphalt binders performance is affected by refining process and crude oil. In this work, we investigated the effect of cutting temperature on the genes and fatigue properties of asphalt during asphalt refining. Five cutting temperatures (420 °C to 440 °C, interval of 5 °C) were set during the asphalt preparation, expanded the asphalt samples through ageing method. Fourier Transform Infrared (FTIR), Gel Permeation Chromatography (GPC), Nuclear Magnetic resonance Spectrum (1HNMR), Elemental analyzer, and improved Brown-Ladner method were used to characterize the asphalt genes. The fatigue performance of asphalt through Linear Amplitude Sweep (LAS) combined with the Simplified Viscoelastic Continuum Damage (S-VECD). Finally, the Pearson correlation method was used to analyze the correlation between genes and fatigue parameters of binders. The results showed that the cutting temperature and aging process changed the genes distribution of binders and these influence the fatigue properties of binders. In addition, the fatigue life of asphalt decreased at high strain levels and increased at low strain levels as the cutting temperature and the degree of ageing increased. The Pearson correlation results indicated a significant correlation between the genes and fatigue parameters of asphalt, however, the key genes affecting low-strain (2.5% and 5 %) and high-strain (10% and 20%) level fatigue in asphalt are significantly different. The outcomes of the paper provide insights about the influence of cutting temperature on the variation of asphalt genes and fatigue parameters, to allow more informed to promote of asphalt preparation.

Assessing correlations between two linear amplitude sweep (LAS) standards for evaluating the fatigue properties of aged bitumen

ABSTRACT Linear amplitude sweep (LAS) is an accelerated and well-established testing method to evaluate bitumen fatigue. However, there are different versions of LAS procedures employed. Significant differences in loading modes, damage failure criteria and calculations exist between existing standards, leading to the inconsistency in the performance characterisation of bitumen. This study investigated the fatigue performance of six different bitumen at various ageing levels using two versions of the LAS standards (TP101-14 and T391-20). The stress–strain curves, damage characteristic curves, prediction of fatigue life and cracking length were analysed and compared. It was seen that conclusions drawn from the old version of LAS standard (TP101-14) were unclear as no distinct trends related to change in fatigue life could be observed for binders with progressively increased ageing levels, regardless of the strain levels used for analysis. The new version of LAS (T391-20), however, showed acceptable consistency. The trends indicate that at low strain levels, the fatigue life increases with ageing levels, while opposite trend was observed at higher strain levels. Moreover, the cracking length as defined in the T391-20 standard increases with progressively increased ageing. The new version of LAS standard (T391-20) is recommended for characterising the fatigue performance of aged bitumen.

Attempting to Create a Pathway to 15-Deacetylcalonectrin with Limited Accumulation in Cultures of Fusarium Tri3 Mutants: Insight into Trichothecene Biosynthesis Machinery.

The compound 15-deacetylcalonectrin (15-deCAL) is a common pathway intermediate in the biosynthesis of Fusarium trichothecenes. This tricyclic intermediate is metabolized to calonectrin (CAL) by trichothecene 15-O-acetyltransferase encoded by Tri3. Unlike other trichothecene pathway Tri gene mutants, the Δtri3 mutant produces lower amounts of the knocked-out enzyme's substrate 15-deCAL, and instead, accumulates higher quantities of earlier bicyclic intermediate and shunt metabolites. Furthermore, evolutionary studies suggest that Tri3 may play a role in shaping the chemotypes of trichothecene-producing Fusarium strains. To better understand the functional role of Tri3p in biosynthesis and evolution, we aimed to develop a method to produce 15-deCAL by using transgenic Fusarium graminearum strains derived from a trichothecene overproducer. Unfortunately, introducing mutant Tri3, encoding a catalytically impaired but structurally intact acetylase, did not improve the low 15-deCAL production level of the ΔFgtri3 deletion strain, and the bicyclic products continued to accumulate as the major metabolites of the active-site mutant. These findings are discussed in light of the enzyme responsible for 15-deCAL production in trichothecene biosynthesis machinery. To efficiently produce 15-deCAL, we tested an alternative strategy of using a CAL-overproducing transformant. By feeding a crude CAL extract to a Fusarium commune strain that was isolated in this study and capable of specifically deacetylating C-15 acetyl, 15-deCAL was efficiently recovered. The substrate produced in this manner can be used for kinetic investigations of this enzyme and its possible role in chemotype diversification.

Texture Evolution and Plastic Deformation Mechanism of Cold-Drawn Co-Cr-Ni-Mo Alloy

The plastic deformation behavior and mechanisms of Co-Cr-Ni-Mo alloy were investigated. The wires were subjected to different reductions using a multi-pass drawing approach and the resulting microstructures were characterized by EBSD and TEM. It was found that the alloy cold-drawn from surface to center exhibited non-uniform radial strain, with decreasing strain from surface to center. As the strain increased, the transverse texture of the alloy evolved from the initial bimodal texture consisting of strong {100}<110> and weak {110}<001> components to bimodal texture with {110}<233> and {112}<111> components, with significant twinning and mirror orientation between twin and matrix. The longitudinal texture evolution of the alloy mainly occurred on the α-fiber line, and ultimately did not form a significant texture due to grain elongation and crystal rotation. The plastic deformation mechanism of the Co-Cr-Ni-Mo alloy was dominated by dislocation slip at lower strain levels, which gradually transitioned to a combination of dislocation slip and twinning at higher strain levels. The deformation twins were typically distributed in high-density dislocation regions, and the twin boundaries transformed into high-angle sub-grain boundaries, hindering the extension of dislocation slip and deformation twin. With the increase in strain, work hardening results in a significant increase in strength and microhardness.

In vivo measurement of strain in the periodontal space of pig (Sus scrofa) incisors using in-fiber Bragg sensors.

The incisor teeth in pigs, Sus scrofa, function in association with a disc-shaped snout to explore the environment for potential food. Understanding how mechanical loading applied to the tooth deforms the periodontal ligament (PDL) is important to determining the role of periodontal mechanoreceptors during food exploration and feeding. The objective of this study was to use fiber Bragg (FBG) sensors to measure strain in vivo within the PDL space of pig incisors. The central mandibular incisors of pigs underwent spring loaded lingual tipping during FBG strain recording within the labial periodontal space. FBG sensors were placed within the periodontal space of the central mandibular incisors of ~2-3-month-old farm pigs. The magnitude and orientation of spring loads are expected to mimic incisor contact with food. During incisor tipping with load calibrated springs, FBG strains in vitro (N = 6) and in vivo (N = 6) recorded at comparable load levels overlapped in range (-10-20 με). Linear regressions between peak FBG strains, that is, the highest recorded strain value, and baseline strains, that is, strain without applied spring load, were significant across all in vivo experiments (peak strain at 200 g vs. baseline, p = .04; peak strain at 2000 g vs. baseline p = .03; peak strain at 2000 g vs. 200 g, p = .004). These linear relationships indicate that on a per experiment basis, the maximum measured strain at different spring loads showed predictable differences. A Friedman test of the absolute value of peak strain confirmed the significant increase in strain between baseline, 200 g, and 2000 g spring activation (p = .02). Mainly compressive strains were recorded in the labial PDL space and increases in spring load applied in vivo generated increases in FBG strain measurements. These results demonstrate the capacity for FBG sensors to be used in vivo to assess transmission of occlusal loads through the periodontium. PDL strain is associated with mechanoreceptor stimulation and is expected to affect the functional morphology of the incisors. The overall low levels of strain observed may correspond with the robust functional morphology of pig incisors and the tendency for pigs to encounter diverse foods and substrates during food exploration.

Cyclic performance study of Q460D steel and ER55-G welds after high temperature

Coupon test specimens with the gauge length part of Q460D high-strength steel or ER55-G weld respectively were heated up to high temperature of 900 °C and then cooled in water. Uniaxial tensile tests were conducted on those cooled specimens. The engineering stress-engineering strain curves were obtained. Meanwhile, twelve smooth round bar specimens made of Q460D high-strength steel and ER55-G welds were heated up to high temperature of 900 °C and then cooled naturally or cooled in water. Cyclic loading tests with two different loading protocols, namely constant amplitude and variable amplitude, were conducted on these specimens at different strain levels. The engineering stress-engineering strain curves of each specimen were obtained, enabling to compare and analyze the differences of the results in cyclic mechanical properties of each specimen in terms of damage morphology, hysteresis performance, and ductility characteristics. The test results show that the different cooling methods after the high temperature of 900 °C have a significant impact on the ultimate strength and elongation of Q460D high-strength steel and ER55-G welds. The ultimate strength of the specimens after water cooling was significantly higher than that of the specimens after natural cooling, while the elongation result was opposite. It was obvious from the test results that water cooling and natural cooling after high temperature led to a decrease in ductility and energy absorption capacity of the base metal and welds to various degrees, while their energy dissipation capacity was significantly improved at low strain level.

In Situ Study on the Structural Evolution of Flexible Ionic Gel Sensors

With the development of society, the demand for smart coatings is increasing. The development of flexible strain sensors using block copolymer self-assembled ionic gel materials provides a promising method for promoting the development of smart coatings. The ionic liquid in the ionic part of the material is crucial for the performance of the sensor. In this study, the structural changes within FDA/dEAN (self-assembly of acrylated Pluronic F127 (F127-DA) in partially deuterated ethylammonium nitrate (dEAN)) triblock copolymer ionic gel during uniaxial tensile flow were characterized using an in situ SAXS technique. The results revealed that the characteristics of the responses of the ionic gel to strain resistance were intricately linked to the evolution of its microstructure during the tensile process. At low levels of strain, the face-centered cubic lattice arrangement of the micelles tended to remain unchanged. However, when subjected to higher strains, the molecular chains aligned along the stretching direction, resulting in a more ordered structure with reduced entropy. This alignment led to significant disruption in bridging structures within the material. Furthermore, this research explored the impact of the stretching rate on the relaxation process. It was observed that higher stretching rates led to decreases in the average relaxation time, indicating rate dependence in the microstructure’s behavior. These findings provide valuable insights into the behavior and performance of flexible strain sensors based on ionic gel materials in smart coatings.

Fatigue Performance Evaluation of Fiber-Reinforced Asphalt Mixtures with Four-Point Bending Beam and Uniaxial Fatigue Tests

This study aimed to evaluate the fatigue cracking potential of aramid fiber–reinforced asphalt mixtures. Three fiber-reinforced asphalt mixtures (FRAMs) were prepared employing a singular aggregate type (diabase stone), one binder type (PG76-22), and two distinct combinations of aramid fibers at varying dosages. Two types of fiber were used at different dosages by weight of mix: polyolefin/aramid (PFA) fibers at a dosage 0.05% and sasobit-coated aramid (SCA) fibers at dosages of 0.01% and 0.02%. Additionally, an unreinforced (control) mix was also produced for comparison purposes. Each of the mixtures was produced at a batch plant, adhering to the fiber manufacturer’s recommended mixing methods, while maintaining a constant binder content of 5.5% based on the total mix weight. Four-point beam (4PB) fatigue, uniaxial fatigue (UF), and Texas overlay tests (OT) were performed to characterize the fatigue and reflective cracking behavior of FRAM. The 4PB test results suggest that FRAM improved the fatigue life at lower strain levels (400 µε and 600 µε); however, at higher microstrain (800 µε) level, FRAM exhibited lower fatigue life than the control mix. Damage characteristic curves obtained from the UF tests showed better fatigue tolerance for reinforced mixtures, regardless of microstrain level. For cycles to failure under tensile loading, UF and OT test results indicated lower fatigue life of reinforced mixtures compared with the control mix. Therefore, under flexural loading the fiber-reinforced asphalt mixtures tend to improve the fatigue life. However, for direct tension load, reinforced mixtures tend to deteriorate the fatigue life when comparing cycles to failure at constant strain amplitude.

Laboratory and Field Performance Evaluation of Cracking of Airfield Warm Mix Asphalt with Reclaimed Asphalt Pavement at the National Airport Pavement and Materials Research Center

The U.S. Federal Aviation Administration is exploring initiatives to decrease transportation greenhouse gas emissions by developing carbon reduction strategies, including using low-embodied carbon materials, such as reclaimed asphalt pavement (RAP), in airport pavement construction. However, verifying RAP’s viability for airfield pavements with laboratory and field performance measures is essential. This study compared the cracking susceptibility of a P-401 hot mix asphalt and warm mix asphalt (WMA)+RAP airfield mixes using laboratory performance tests and conducted a preliminary evaluation of pavement responses from accelerated pavement testing (APT) fatigue tests. The observations and outcomes presented in this paper found that adding 20% of recycled materials with WMA additives had a decreasing impact in mix performance but did not overly affect the asphalt mix properties, as cracking properties from the different test procedures were found with comparable outcomes. Additional observations from strain gauges and temperature probes in the National Airport Pavement and Materials Research Center test cycle 2 APT fatigue test sections showed that the maximum tensile strains in the WMA surface lane 5 south section were consistently higher than those in the WMA+RAP lane 6 south section, which may be because of the higher load level that it was exposed. Additionally, the hardened or aged RAP binder in the entire lane 6 south section may have increased its stiffness, resulting in lower strain levels than in the lane 5 south section. Notably, both sections showed an increase in tensile strains with an increase in asphalt concrete temperature, which confirmed the temperature dependency behavior of asphalt concrete.

Hot isostatic pressing as an alternative thermo-mechanical treatment for metallic full-arch implant-supported frameworks obtained by additive and subtractive manufacturing technology: Vertical and horizontal fit, screw removal torque, and stress analysis.

To assess vertical and horizontal fit, screw removal torque, and stress analysis (considered biomechanical aspects) of full-arch implant frameworks manufactured in Ti-6Al-4V through milling, and additive manufacturing Direct Metal Laser Sintering (DMLS) and Electron Beam Melting (EBM), and the effect of the thermo-mechanical treatment Hot Isostatic Pressing (HIP) as a post-treatment after manufacturing. Maxillary full-arch implant frameworks were made by milling, DMLS, and EBM. The biomechanical assessments were screw removal torque, strain-gauge analyses, and vertical and horizontal marginal fits. The vertical fit was assessed by the single-screw test and with all screws tightened. All frameworks were submitted to a standardized HIP cycle (920°C, 1000bar pressure, 2h), and the tests were repeated (α = 0.05). At the initial time, milled frameworks presented higher screw removal torque values, and DMLS and EBM frameworks presented lower levels of strain. Using the single-screw test, milled and DMLS frameworks presented higher vertical fit values, and with all screws tightened and horizontally, higher fit values were found for milled frameworks, followed by DMLS and EBM. After HIP, milling and EBM frameworks presented higher screw removal torque values; the lowest strain values were found for EBM. Using the single-screw test, milled and DMLS frameworks presented higher vertical fit values, and with all screws tightened and horizontally no differences were found. DMLS and EBM full-arch frameworks presented adequate values of screw removal torque, strain, and marginal fit, although the worst values of marginal fit were found for EBM frameworks. The HIP cycle enhanced the screw removal torque of milled and EBM frameworks and reduced the strain values of milled frameworks. The HIP represents a reliable post-treatment for Ti-6Al-4V dental prostheses produced by milling and EBM technologies.

Tensile damage self-monitoring of carbon fiber/epoxy 3D braided composites with electrical resistance method

Electrical resistance method (ERM) has great potential in self-monitoring structural health for carbon fiber composites due to carbon fiber conductivity. Here we report the correlation between tensile damages and electrical resistance changes of 3D braided composites subjected to monotonic and cyclic tensile loading. Experimental and finite element methods were utilized to reveal the electrical resistance variation and damage evolution under monotonic tensile loading. We found that the electrical resistance changes under monotonic tensile loading could be segmented into three regions, namely, linear growth region, transition region and exponential growth region, corresponding to different damage modes. Synchronous and reversible electrical resistance changes at a low strain level (12% of fracture strain) cyclic loading proved the stability and repeatability of self-monitoring capability. While, the abrupt electrical resistance changes at a high strain level (75% of fracture strain), indicated catastrophic failure of the composites. Such kind of correspondence between tensile damages and electrical resistance change under tensile loading enables ERM to achieve the in-situ structural health monitoring of 3D braided composites without relying on external sensors.

Assessing the validity of VR as a training tool for medical students

The advances in Virtual Reality technologies, increased availability and reducing hardware costs have diminished many of the early challenges in the adoption of VR. However, a commonly identified gap in immersive Virtual Reality-Head Mounded Display (VR-HMD) training for medical education is the confidence in the long-term validity of the applications, in particular, the acceleration of the learning curve efficacy of learning outcomes over time and actual skills translation into real environments. Research shows a wide range of ad hoc applications, with superficial evaluations often conducted by technology vendors, based on assumed environments and tasks, envisaged (as opposed to actual) users and effectiveness of learning outcomes underpinned with little or no research focusing on a requirements-driven validation approach. This presents decision-making challenges for those seeking to adopt, implement and embed such systems in teaching practice. The current paper aims to (i) determine whether medical VR training improves the skill acquisition of training candidates, (ii) determine the factors affecting the acquisition of skills and (iii) validate the VR-based training using requirement-driven approach. In this paper, we used within- and between-subject design approaches to assess the validity of VR-based surgical training platform developed by Vantari VR against requirements which have been identified to have impact on learning processes and outcomes in VR-based training. First, study and control groups were compared based on their level of skill acquisitions. Then, by tailoring a requirements framework, the system was validated against the appropriate requirements. In total, 74 out of 109 requirements were investigated and evaluated against survey, observer and stakeholder workshop data. The training scenario covered the topic of Arterial Blood Gas (ABG) collection for second-year university medical students. In total 44 students volunteered to participate in this study, having been randomly assigned to either the study or control group. Students exposed to VR training (the study group) outperformed the control group in practical clinical skills training tasks and also adhered to better safety and hygiene practices. The study group also had a greater procedural completion rate over the control group. Students showed increased self-efficacy and knowledge scores immediately post-VR training. Prior ABG training did not impact on VR training outcomes. Low levels of simulation sickness, physical strain and stress, coupled with high levels of enjoyability, engagement, presence and fidelity were identified as factors affecting the overall training experience. In terms of learning, high scores were recorded for active learning, cognitive benefit and reflective thinking. Lastly, by validating the system against 74 system requirements, the study found a user acceptance level of 75%. This enabled the identification of weaknesses of the current system and possible future directions.

Applying Low Levels of Strain to Model Nascent Phenomenon of Retinal Pathologies

Applying Low Levels of Strain to Model Nascent Phenomenon of Retinal Pathologies

Study of rotational dynamic recrystallization during warm compression of an Mg-Zn-Nd-Zr alloy

The dynamic recrystallized grains obtained by rotational dynamic recrystallization (RDRX) mechanism are finer and have fewer defects, which can effectively improve the performance of magnesium alloys. However, the impact of temperature and strain on RDRX is currently unclear. In this study, an extruded Mg-Zn-Nd-Zr alloy with trace amounts of rare earth elements and fine grain size was used as the raw material, and a warm deformation temperature interval was selected, which suppressed the large-angle migration, reduced the activity of twinning, and successfully ensured RDRX as the main recrystallization mechanism. The effects of temperature and strain on RDRX of magnesium alloys were systematically investigated, and it was found that the compression temperature and strain jointly affected the formation of RDRX. The RDRXed grains emerged during the dynamic softening stage and abundantly developed during the dynamic equilibrium stage. The percentage of the RDRXed grains increased with the increase of temperature for temperatures below 290 °C and decreased with the increase of temperature for temperatures above 290 °C at low strain levels (0.4). The percentage of RDRX monotonically increased with the increase of compression temperature at high strain (0.7). The size of the recrystallized grains increased with the increase of compression temperature. The formation of the RDRXed grains could effectively release the local strain and form a strain free region without distortion, resulting in strain softening.

PREPAREDNESS AND NEEDS AMONG YOUNG, MIDDLE-AGED, AND OLDER ADULT LATINX CAREGIVERS

Abstract Taking care of one’s family is a primary obligation among Latinx communities. According to CDC’s Behavioral Risk Factor Surveillance System, 22.9% of New Mexican adults reported providing care to a friend or family member in the past 30 days; 10.4 % provided care to an individual with dementia. The southern Border region of New Mexico is remote and desert, with high rates of poverty and inaccessibility to health care and services. Caregivers may feel unprepared for caregiving, lack the knowledge and skills required to provide care, but struggle through because of the importance of La Familia. Adverse physical and psychological consequences have been found; yet those who report greater preparedness exhibit lower levels of strain. Seventy-six primarily female and healthy Latinx caregivers (age range 20-76 years, 30% young, 40% middle-aged, and 30% older adults) were surveyed on caregiving they provide, administered the Preparedness for Caregiving Scale, and asked what types of services are needed in their role. Results indicated the top three provided aspects of caregiving were (in descending order): Food, emotional support, and transportation. Caregivers reported a high degree of preparedness in taking care of the recipient’s physical needs, handling emergencies, and proving overall care. Needed resources included emotional support, financial assistance, and respite. Greater caregiving provision was significantly associated with better health (r =. 53, p = .09) and greater resource needs (r = .35, p <.01). Thus, level of preparedness is an important caregiving dimension to address, especially with culturally diverse communities having strong cultural caregiving norms.

Study on the relationship between microstructure and properties of heavy-wall X70 pipeline steel with different processing directions

The neglect of microstructure and anisotropy in the design of subsea pipeline steel can seriously affect the pipe service life and lead to fracture failure. In this work, experimental and representative volume element (RVE) model results were used to analyze the effect of differences in the microstructural characteristics of heavy-wall ferritic/bainitic dual-phase (DP) ×70 pipeline steel in the transverse and rolling directions on the mechanical properties. The results showed that blocky bainite with an aspect ratio 1.9 in the transverse microstructure induced the ferrite to produce strain localization, decreasing the plasticity. Banded bainite with an aspect ratio of 4.4 in the rolling direction was more prone to activate the dislocation slip system, which enhanced deformation compatibility by limiting the ferrite deformation space through plastic deformation at low strain levels. The dislocation wall type of the rolling direction promoted the production of back stress (long-range internal stress) and reduced the strain gradient at the interface. The dislocation arrangement in the transverse direction was transformed from a mixed type to a dislocation wall type during cyclic loading, and the back stress was dynamically saturated by grain size. Higher forest hardening in the transverse direction increased strength and hardening rates, while higher back-stress hardening in the rolling direction promoted plasticity. The results reveal the relationship between microstructural characteristics difference and mechanical properties and back stress evolution to provide a theoretical basis for designing the heavy-wall ×70 pipeline steel.