Changes In Mechanical Behavior Research Articles

Effect of matrix microstructure on micro- and macro- mechanical properties of 2.5D woven oxide fiber reinforced oxide matrix composites

A comprehensive learning of the mechanical behavior change mechanism of oxide/oxide composites is of great significance as a guide for their industrial applications. This study focused on examining how matrix microstructure impacted the micro- and macro- mechanical properties of the composites mainly by nanoindentation tests, macro-mechanical tests and x-ray computed tomography. The results showed that the sintering phenomenon of matrix sintered at 1200 ºC was more obvious, and there were visible transverse and longitudinal cracks. The in-situ modulus of matrix and interfacial shear modulus of the composite increased by 61.1% and 36.4%, respectively, with the increase of matrix sintering densification. Combined with these micro-mechanical parameters of the composites, the He-Hutchinson model predicted the same crack propagation modes as those obtained from fracture toughness tests. Moreover, more matrix cracks directly led to a 45.4% reduction in the flexural strength of the composites sintered at 1200 ºC compared to that sintered at 1100 ºC. In addition, a comparison analysis was conducted on the evolution of microstructure, micro- and macro- mechanical properties of 2.5D and 2D composites with the same preparation parameters.

Stiffness Hardening Effect of Wire Rope Isolators under Small Cyclic Loads for Vibration Isolation

Wire rope isolator (WRI) devices are widely used in vibration reduction industrial equipment, and stiffness is the key parameter that determines isolation effectiveness. WRI devices show slight nonlinearity under small loads, and the manufacturers generally only provide the initial parameters. To investigate the mechanical behavior changes in the WRI devices under repeated loads, five types of WRI specimens were tested under various amplitudes, loading speeds, and preloads. The test results of large symmetrical compression and tension loads showed that the WRI devices demonstrated stable hysteresis curves under repeated loads, while the hysteresis curves were independent of the loading speed. The test results of small cyclic loads with large preloads show that the stiffness of the WRI specimen follows the logarithmic law, with the cycle number under various loading conditions. Particularly, the stiffness of the specimen increases by about 10–30% after 50 cycles. The initial stiffness Ka decreases linearly with the preloads, while the decrease is quadratic in relation to the cyclic load. The hardening coefficient Ca shows a positive correlation with the loading capacity of the WRI devices, while it shows a negative correlation with the preload and cyclic load amplitudes. It is recommended to consider the stiffness increase in the WRI devices during the evaluation of isolation effectiveness.

Toward understanding the brain tissue behavior due to preconditioning: an experimental study and RVE approach.

Brain tissue under preconditioning, as a complex issue, refers to repeated loading-unloading cycles applied in mechanical testing protocols. In previous studies, only the mechanical behavior of the tissue under preconditioning was investigated; However, the link between macrostructural mechanical behavior and microstructural changes in brain tissue remains underexplored. This study aims to bridge this gap by investigating bovine brain tissue responses both before and after preconditioning. We employed a dual approach: experimental mechanical testing and computational modeling. Experimental tests were conducted to observe microstructural changes in mechanical behavior due to preconditioning, with a focus on axonal damage. Concurrently, we developed multiscale models using statistically representative volume elements (RVE) to simulate the tissue's microstructural response. These RVEs, featuring randomly distributed axonal fibers within the extracellular matrix, provide a realistic depiction of the white matter microstructure. Our findings show that preconditioning induces significant changes in the mechanical properties of brain tissue and affects axonal integrity. The RVE models successfully captured localized stresses and facilitated the microscopic analysis of axonal injury mechanisms. These results underscore the importance of considering both macro and micro scales in understanding brain tissue behavior under mechanical loading. This comprehensive approach offers valuable insights into mechanotransduction processes and improves the analysis of microstructural phenomena in brain tissue.

Investigating the influence of stress on UV-induced degradation in cellulose acetate: A comprehensive experimental characterization

Renewable and degradable polymers have emerged in everyday applications ranging from mundane eating utensils to high-tech medical devices. However, the current literature lacks a thorough experimental characterization of the mechanical behavior change due to degradation. In this work, we characterize the microscopic chemical changes due to photo-degradation and resulting stress effects on the mechanical behavior of cellulose acetate, a renewable and degradable polymer that is used in various consumer products. Specifically, we photo-degrade this polymer under (i) traction-free conditions and (ii) under applied stress. A key finding of this work is that upon photo-degradation, this material undergoes chain scission, which affects its mechanical properties and may be further affected by the applied stress.

Evaluating the Let's Move It intervention programme theory for adolescents' physical activity: Theorized psychosocial mechanisms of behavioural changes.

Behaviour change theories have extensively been used in health behaviour change interventions and their programme theories. However, they are rarely evaluated in randomized field studies. The Let's Move It intervention targeted various psychosocial constructs to increase adolescents' physical activity. A theory-based process evaluation aiming to illuminate the trial findings as well as to test the programme theory used is conducted. Specifically, we investigate whether the intervention influenced the theorized determinants of change immediately post-intervention and after 1 year, and whether these determinants were associated with changes in physical activity. A cluster-randomized controlled trial (n = 1166). We measured theorized determinants with self-report, and physical activity (PA) with accelerometry and self-report. The effects are evaluated with repeated measures ANOVA and regression models. No changes were detected in most theorized determinants but intervention arm reported higher enactment of behaviour change techniques used during intervention immediately post-intervention and lower descriptive norms for PA throughout. Autonomous motivation was associated with PA immediately post-intervention. The lack of intervention effects may be due to many factors, for example insensitive measures, ceiling effects. However, reporting these null effects advances understanding of behaviour change processes. We introduce methodologic possibilities for future intervention programme theory evaluation efforts.

Integrated telehealth intervention to reduce chronic pain and unhealthy drinking among people living with HIV: protocol for a randomized controlled trial

BackgroundUnhealthy alcohol use represents a significant risk for morbidity and mortality among people living with HIV (PLWH), in part through its impact on HIV management. Chronic pain, a common comorbidity, exacerbates suboptimal engagement in the HIV care continuum and has reciprocal detrimental effects on alcohol outcomes. There are no integrated, accessible approaches that address these comorbid conditions among PLWH to date. This paper describes a research study protocol of an integrated telehealth intervention to reduce unhealthy drinking and chronic pain among PLWH (Motivational and Cognitive-Behavioral Management for Alcohol and Pain [INTV]).MethodsTwo-hundred and fifty PLWH with unhealthy drinking and chronic pain will be recruited nationally via online advertisement. Informed consent and baseline assessments occur remotely, followed by 15 days of ecological momentary assessment to assess alcohol use, chronic pain, functioning, and mechanisms of behavior change. Next, participants will be randomized to either the INTV or Control (CTL) condition. Individuals in both conditions will meet with a health counselor through videoconferencing following randomization, and those in the INTV condition will receive 6 additional sessions. At 3- and 6-months post-baseline, participants will complete outcome assessments. It is hypothesized that the INTV condition will result in reduced unhealthy alcohol use and pain ratings compared to the CTL condition.ConclusionThis protocol paper describes a randomized controlled trial which tests the efficacy of a novel, integrated telehealth approach to reduce unhealthy alcohol use and chronic pain for PLWH, two common comorbid conditions that influence the HIV treatment cascade.ClinicalTrials.gov identifierNCT05503173.

From alcohol and other drug treatment mediator to mechanism to implementation: A systematic review and the cases of self-efficacy, social support, and craving.

Research designed to establish alcohol and other drug (AOD) mechanisms of behavioral change (MOBC) has centered on what variables mediate the relation between AOD treatment and outcomes. The purpose of this paper was to review this research evidence to identify empirically supported mediators of alcohol and other drug use and related outcomes and then to evaluate their potential as being AOD treatment MOBC. The first phase was a systematic review of reviews (2008-2023) to identify the variables with the strongest empirical support as mediators of AOD treatment effects. Eligible reviews focused on AOD treatment modalities, included empirically tested mediators, and targeted adult samples. The second phase was a systematic review of empirical studies (1990-2023) testing the hypothesis that variables identified in phase one were AOD treatment mediators/mechanisms and then evaluating each eligible stage two study according to the Kazdin and Nock (Journal of Child Psychology and Psychiatry, 44, 1116) criteria. Eligible articles included empirical studies with adult samples attending AOD treatment and empirically tested one of the three treatment mechanisms as a mediator of an AOD-related outcome. Databases were searched in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. This systematic review was not preregistered. The first review of 11 eligible review articles identified self-efficacy, social support, and craving as having the strongest empirical support. The second review captured 48 individual studies. An evaluation of each of these studies by the Kazdin and Nock criteria suggested that they likely are MOBC and therefore are ready for implementation. The implementation of self-efficacy, social support, and craving into clinical practice and training is warranted. Six directions for future research to solidify and generalize empirical support for the case that self-efficacy, social support, and craving are MOBC are presented, as are five implications for clinical practice and training.

A qualitative investigation of tattooing as an adaptive appearance investment: positive body image and eating disorder recovery in a predominantly transgender and gender expansive sample

ABSTRACT Tattooed individuals often express the positive effects of wearing body art toward improved self-image and confidence. This research builds on prior data exploring the positive effects of tattooing and investigates how tattoos impact one’s relationship to eating disorder (ED) recovery and body image. We held three focus groups lasting 60 minutes each, recruiting participants via purposive snowball sampling (n = 15), with additional opportunities to respond to focus group prompts asynchronously. Eligible participants were individuals with lived experience of an ED, self-identified as being in recovery, had three or more tattoos, and spoke English. Participants predominantly held gender-expansive (n = 4 Non-Binary, n = 3 Genderqueer, n = 3 Cisgender Women, n = 3 Transgender, n = 2 Transmasculine, n = 2 Gender Non-Conforming, n = 2 Intersex, n = 1 Cisgender Man) and non-heterosexual identities. Focus groups were held between April 2021 and July 2023 and followed a semi-structured interview format. Primary analyses focused on participants’ responses to open-ended prompts regarding how they understood the relationships between tattooing, body image, and ED recovery. Thematic analysis identified four core themes: Tattooing allowing for embodiment, tattooing allowing for recovery-oriented behaviors, tattooing enabling positive body image, and tattooing facilitating empowerment. An overarching message was that tattooing is a therapeutic and transformative process, allowing for self-determination. Participants indicated that tattooing can be experienced as a powerful mechanism for behavioral change and shifts in relationship to one’s body. Participants expressed that tattooing can be an effective route towards both gender euphoria and body liberation, enhancing one’s ability to maintain ED recovery.

Effect of thermo-mechanical treatment on cryogenic mechanical properties of a medium-entropy Fe65Co12.5Ni12.5Cr9.5C0.5 alloy produced by the laser-based powder bed fusion

Microstructure and mechanical properties of the Fe65Co12.5Ni12.5Cr9.5C0.5 (in at.%) medium-entropy alloy obtained by the laser-based powder bed fusion (PBF-LB) was investigated in the as-produced condition and after (i) annealing in the interval 800–1100 °C or (ii) cold rolling followed by annealing at 800 °C. The as-produced microstructure was found to be surprisingly stable; noticeable recrystallization occurred only after annealing at 1100 °C. Cold rolling resulted in the formation of typical deformed microstructure, while further annealing led to the formation of a fine-grained recrystallized microstructure. A considerable improvement in cryogenic mechanical properties was obtained after some thermo-mechanical treatments due to the transformation-induced plasticity (TRIP) effect. The cold-rolled alloy had the best cryogenic strength characteristics; yield strength and ultimate tensile strength were found to be 1740 MPa and 2235 MPa, respectively. High strength was combined with a pronounced value of elongation to fracture of 24 %. Detailed analysis of microstructure and corresponding mechanical behavior changes caused by various processing of the as-produced alloy are presented.

Negative affect variability as a potential mechanism of behavior change in alcohol use disorder treatment.

Negative affect and affect variability figure prominently in models of addictive behaviors but are not without controversy. Negative affect variability may better capture a mechanism of behavior change in alcohol use disorder (AUD) treatment because it contains information about affect regulation, a common clinical target. The aims of this study are to examine the change in: (a) trajectory of negative affect variability, (b) association of negative affect variability and abstinence, and (c) association of negative affect variability and heavy drinking during AUD treatment. This article is a secondary analysis of data drawn from a randomized clinical trial. N = 181 participants diagnosed with Diagnostic and Statistical Manual of Mental Disorders, fifth edition AUD (Mage = 50.8, SDage = 10.6; 51.4% female) received 12 sessions of Cognitive Behavioral Coping Skills Therapy for AUD. Participants completed one daily diary prompt per day for 84 consecutive days. Each day, participants reported on negative affect and number of alcoholic drinks consumed the previous day. Time-varying effect models examined changes in negative affect variability and its associations with abstinence and heavy drinking. Negative affect variability decreased throughout treatment. The positive association between negative affect variability and heavy drinking became nonsignificant (decoupled) midway through treatment. The inverse association between negative affect variability and daily abstinence became nonsignificant (decoupled) at approximately day 75 of 84. When mean levels of NA were added as a covariate, the effects were in the same direction but no longer statistically significant. Reductions in negative affect variability may capture an important change mechanism of behavioral treatments for AUD because it contains information about affect regulation as compared with mean levels of negative affect. Negative affect variability warrants further consideration as a mechanism of behavior change. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Mechanical and physicochemical characteristics of sub-millimeter and macrobubbles: Insights from AFM analysis, zeta potential measurements and rise velocity

This study presents the change in mechanical and physicochemical behaviour of macrobubbles and sub-millimeter bubbles with respect to pH. While macrobubbles conventionally range from 100 μm to 2 mm in diameter, this study focuses on the comparatively less-explored sub-millimeter bubble range, centered around a median diameter of 500 μm. The difference in sub-millimeter bubbles (500 μm) compared to their larger counterparts (1100 μm) within macrobubble size range were evidenced through atomic force microscopy (AFM) analysis, zeta potential measurements, and rise velocity experiments. The adhesion force and energy between bubbles and the silicon nitride cantilever tip showed a decreasing trend with increasing pH, notably diminishing by about 50% beyond pH 9. Although no significant differences were statistically revealed between the two bubble sizes at lower pH, the adhesion force and energy were consistently smaller for macrobubble compared to sub-millimeter bubble at higher pH beyond pH 9. This finding suggests that the electrical double layer (EDL) interactions are influenced by the specific surface area, particularly in the alkaline region. Zeta potential measurements exhibited a cubic trend, with an isoelectric point at pH 3.5 and a minimum zeta potential at pH 11. The study also depicted a similar trend in the rise velocity of bubbles, suggesting a direct relationship between bubble stiffness and its rise velocity. Therefore, changes in pH affected the bubbles' properties, while on the other hand, certain physicochemical properties are also influenced by bubble sizes.

ChatGPT for Automated Qualitative Research: Content Analysis.

Data analysis approaches such as qualitative content analysis are notoriously time and labor intensive because of the time to detect, assess, and code a large amount of data. Tools such as ChatGPT may have tremendous potential in automating at least some of the analysis. The aim of this study was to explore the utility of ChatGPT in conducting qualitative content analysis through the analysis of forum posts from people sharing their experiences on reducing their sugar consumption. Inductive and deductive content analysis were performed on 537 forum posts to detect mechanisms of behavior change. Thorough prompt engineering provided appropriate instructions for ChatGPT to execute data analysis tasks. Data identification involved extracting change mechanisms from a subset of forum posts. The precision of the extracted data was assessed through comparison with human coding. On the basis of the identified change mechanisms, coding schemes were developed with ChatGPT using data-driven (inductive) and theory-driven (deductive) content analysis approaches. The deductive approach was informed by the Theoretical Domains Framework using both an unconstrained coding scheme and a structured coding matrix. In total, 10 coding schemes were created from a subset of data and then applied to the full data set in 10 new conversations, resulting in 100 conversations each for inductive and unconstrained deductive analysis. A total of 10 further conversations coded the full data set into the structured coding matrix. Intercoder agreement was evaluated across and within coding schemes. ChatGPT output was also evaluated by the researchers to assess whether it reflected prompt instructions. The precision of detecting change mechanisms in the data subset ranged from 66% to 88%. Overall κ scores for intercoder agreement ranged from 0.72 to 0.82 across inductive coding schemes and from 0.58 to 0.73 across unconstrained coding schemes and structured coding matrix. Coding into the best-performing coding scheme resulted in category-specific κ scores ranging from 0.67 to 0.95 for the inductive approach and from 0.13 to 0.87 for the deductive approaches. ChatGPT largely followed prompt instructions in producing a description of each coding scheme, although the wording for the inductively developed coding schemes was lengthier than specified. ChatGPT appears fairly reliable in assisting with qualitative analysis. ChatGPT performed better in developing an inductive coding scheme that emerged from the data than adapting an existing framework into an unconstrained coding scheme or coding directly into a structured matrix. The potential for ChatGPT to act as a second coder also appears promising, with almost perfect agreement in at least 1 coding scheme. The findings suggest that ChatGPT could prove useful as a tool to assist in each phase of qualitative content analysis, but multiple iterations are required to determine the reliability of each stage of analysis.

Immersive storytelling for pro-environmental behaviour change: The Green Planet augmented reality experience

Immersive media is becoming more mainstream but its role in challenging social norms and individuals’ behaviours is less understood. We implemented a survey at The Green Planet Augmented Reality Experience, one of the largest immersive experiences in the United Kingdom, investigating the potential of nature-themed augmented reality (AR) experiences to encourage sustainability beliefs and pro-environmental behaviours, with a one-month follow-up. A video condition group was also recruited to watch a 2D screen-capture video of the AR experience. Results suggest that the AR group had increased in sustainability attitudes and pro-environmental behaviours after (vs. before) the experience, and this persisted at follow-up one month later. When compared to the video group, the AR group scored higher in sustainability beliefs immediately after engaging with the media (but did not differ in pro-environmental behavioural intentions). At a one-month follow-up, both groups appeared to have declined in sustainability beliefs and behaviours in comparison to immediately after media exposure (but were still greater when compared to before exposure). While the two groups did not differ in sustainability beliefs, AR visitors reported to have performed more pro-environmental behaviours in the month following the experience and even increased significantly more since before attending the experience when compared to those in the video condition. Finally, we built a model of cognitive mechanisms of longitudinal pro-environmental behaviour change by media, identifying the sense of presence and connection with nature as mechanisms through which immersive media can promote greater behaviour change when compared to traditional video media. Limitations and industry implications are discussed.

The Recyclability of Fire-Retarded Biobased Polyamide 11 (PA11) Composites Reinforced with Basalt Fibers (BFs): The Influence of Reprocessing on Structure, Properties, and Fire Behavior.

The growing requirements regarding the safety of using polymers and their composites are related to the emergence of more effective, sustainable, and hazardous-limited fire retardants (FRs). Significant amounts of FRs are usually required to effectively affect a polymer's burning behavior, while the knowledge of their recycling potential is still insufficient. At the same time, concerns are related not only to the reduced effectiveness of flame retardancy but also, above all, to the potential deterioration of mechanical properties caused by the degradation of temperature-affected additives under processing conditions. This study describes the impact of the four-time reprocessing of bio-based polyamide 11 (PA11) modified with an intumescent flame-retardant (IFR) system composed of ammonium polyphosphate (APP), melamine cyanurate (MC), and pentaerythritol (PER) and its composites containing additional short basalt fibers (BFs). Composites manufactured via twin-screw extrusion were subjected to four reprocessing cycles using injection molding. A comprehensive analysis of their structural, mechanical, and fire behavior changes in each cycle was conducted. The obtained results confirmed the safety of using the proposed fire-retarded polyamide and its composites while reprocessing under the recommended process parameters without the risk of significant changes in the structure. The partial increase in flammability of reprocessed PA-based materials caused mainly by polymer degradation has been described.

Effects of Y2Zr2O7 particles and rolling deformation process on the mechanical properties and heat load behavior of W–Y2Zr2O7 plate

This paper addresses the significant requirements in China's fusion engineering and investigates the preparation technology and performance characterization of high-performance tungsten-based materials used as PFMs. The rolled W–Y2Zr2O7 plate were prepared through sintering and subsequent rolling, and steady-state heat load assessment was conducted under fusion device working conditions. Additionally, the change in mechanical behavior of the rolled plates was investigated across different surfaces. The results also revealed that the rolling plate exhibited a DBTT between RT and 200 °C, with more superior mechanical properties along the RD direction. The flat-plate W–Y2Zr2O7/Cu components demonstrated the ability to withstand 1000 heat load cycles at 10 MW/m2 without cracking, indicating favorable thermo-mechanical performance as PFMs. These findings serve as a valuable reference for the fabrication of tungsten-based materials in fusion engineering.

Applying Meaning and Self-Determination Theory to the Development of a Web-Based mHealth Physical Activity Intervention: Proof-of-Concept Pilot Study.

Meaning in life is positively associated with health, well-being, and longevity, which may be partially explained by engagement in healthier behaviors, including physical activity (PA). However, promoting awareness of meaning is a behavior change strategy that has not been tested in previous PA interventions. This study aims to develop, refine, and pilot-test the Meaningful Activity Program (MAP; MAP to Health), a web-based mobile health PA intervention, theoretically grounded in meaning and self-determination theory, for insufficiently active middle-aged adults. Following an iterative user-testing and refinement phase, we used a single-arm double baseline proof-of-concept pilot trial design. Participants included 35 insufficiently active adults in midlife (aged 40-64 years) interested in increasing their PA. After a 4-week baseline period, participants engaged in MAP to Health for 8 weeks. MAP to Health used a web-based assessment and just-in-time SMS text messaging to individualize the intervention; promote meaning salience; support the basic psychological needs of autonomy, competence, and relatedness; and increase PA. Participants completed measures of the hypothesized mechanisms of behavior change, including meaning salience, needs satisfaction, and autonomous motivation at pretest (-4 weeks), baseline (0 weeks), midpoint (4 weeks), and posttest (8 weeks) time points, and wore accelerometers for the study duration. At the end of the intervention, participants completed a qualitative interview. Mixed models compared changes in behavioral mechanisms during the intervention to changes before the intervention. Framework matrix analyses were used to analyze qualitative data. Participants were aged 50.8 (SD 8.2) years on average; predominantly female (27/35, 77%); and 20% (7/35) Asian, 9% (3/35) Black or African American, 66% (23/35) White, and 6% (2/35) other race. Most (32/35, 91%) used MAP to Health for ≥5 of 8 weeks. Participants rated the intervention as easy to use (mean 4.3, SD 0.8 [out of 5.0]) and useful (mean 4.3, SD 0.6). None of the hypothesized mechanisms changed significantly during the preintervention phase (Cohen d values <0.15). However, autonomy (P<.001; Cohen d=0.76), competence (P<.001; Cohen d=0.65), relatedness (P=.004; Cohen d=0.46), autonomous motivation (P<.001; Cohen d=0.37), and meaning salience (P<.001; Cohen d=0.40) increased significantly during the intervention. Comparison of slopes before the intervention versus during the intervention revealed that increases during the intervention were significantly greater for autonomy (P=.002), competence (P<.001), and meaning salience (P=.001); however, slopes were not significantly different for relatedness (P=.10) and autonomous motivation (P=.17). Qualitative themes offered suggestions for improvement. MAP to Health was acceptable to participants, feasible to deliver, and associated with increases in the target mechanisms of behavior change. This is the first intervention to use meaning as a behavior change strategy in a PA intervention. Future research will test the efficacy of the intervention in increasing PA compared to a control condition.

Comprehending Health Behavior Change and Maintenance: A Systematic Review and Meta-Synthesis of Behavior Theories

ABSTRACT Background Health behaviors exhibit diverse characteristics and types, leading to health behavior theories with varied focuses. However, an integrated framework elucidating the intrinsic mechanisms of different behavior types is notably absent. Purpose This study aimed to establish such a framework offering a comprehensive basis for explanations and behavior interventions. Methods A systematic review and meta-synthesis of qualitative research concerning health behavior change and maintenance were conducted. Results A total of 556 records were identified and screened, with 170 meeting the inclusion criteria. Thematic synthesis, a form of meta-synthesis, generated 23 themes, with the qualitative relationships between them presented in a conceptual model, forming an integrated framework. Discussion This framework provides a dynamic and hierarchical platform that enables the interpretation and analysis of various health behaviors within a unified structure. Furthermore, the recognition of the dynamicity of constructs and the multiplicity of behavior routes offers certain implications for intervention design, including behavior setting guidance, immediate benefits provision, and behavior interactions utilization. Translation to Health Education Practice The study provides an integrated framework for health educators/promoters. It offers a comprehensive view of health behavior change mechanisms from multiple perspectives and provides insights for the design, implementation and evaluation of behavior intervention practices.

Geothermo‐mechanical alterations due to heat energy extraction in enhanced geothermal systems: Overview and prospective directions

AbstractGeothermal energy from deep underground (or geological) formations, with or without its combination with carbon capture and storage (CCS), can be a key technology to mitigate anthropogenic greenhouse gas emissions and meet the 2050 net‐zero carbon emission target. Geothermal resources in low‐permeability and medium‐ and high‐temperature reservoirs in sedimentary sequence require hydraulic stimulation for enhanced geothermal systems (EGS). However, fluid migration for geothermal energy in EGS or with potential CO2 storage in a CO2‐EGS are both dependent on the in situ flow pathway network created by induced fluid injection. These thermo‐mechanical interactions can be complex and induce varying alterations in the mechanical response when the working fluid is water (in EGS) or supercritical CO2 (in CO2‐EGS), which could impact the geothermal energy recovery from geological formations. Therefore, there is a need for a deeper understanding of the heat extraction process in EGS and CO2‐EGS. This study presents a systematic review of the effects of changes in mechanical properties and behavior of deep underground rocks on the induced flow pathway and heat recovery in EGS reservoirs with or without CO2 storage in CO2‐EGS. Further, we proposed waterless‐stimulated EGS as an alternative approach to improve heat energy extraction in EGS. Lastly, based on the results of our literature review and proposed ideas, we recommend promising areas of investigation that may provide more insights into understanding geothermo‐mechanics to further stimulate new research studies and accelerate the development of geothermal energy as a viable clean energy technology.

PEAK Mood, Mind, and Marks: a pilot study of an intervention to support university students' mental and cognitive health through physical exercise.

Regular exercise has the potential to enhance university students' mental and cognitive health. The PEAK Mood, Mind and Marks program (i.e., PEAK) is a neuroscience-informed intervention developed using the Behaviour Change Wheel to support students to exercise three or more times per week to benefit their mental and cognitive health. This pilot study assessed the impact of PEAK on exercise, mental and cognitive health, and implementation outcomes. PEAK was delivered to 115 undergraduate university students throughout a 12-week university semester. The primary outcome was weekly exercise frequency. Secondary outcomes were: time spent engaged in moderate-vigorous exercise, sedentary behaviour and perceived mental health and cognitive health. All were measured via online self-report questionnaires. Qualitative interviews with 15 students investigated influences on engagement, the acceptability and appropriateness of PEAK, and its mechanisms of behaviour change. Paired t-tests, Wilcoxon Signed-Rank tests and template analysis were used to analyse quantitative and qualitative data, respectively. On average, 48.4% of students engaged in the recommended frequency of three or more exercise sessions per week. This proportion decreased towards the end of PEAK. Sedentary behaviour significantly decreased from baseline to end-point, and moderate-vigorous exercise significantly increased among students' who were non-exercisers. Mental wellbeing, stress, loneliness, and sense of belonging to the university significantly improved. There were no significant changes in psychological distress. Concentration, memory, and productivity significantly improved. Sixty-eight percent of students remained engaged in one or more components of PEAK at end-point. Qualitative data indicated students found PEAK to be acceptable and appropriate, and that it improved aspects of their capability, opportunity, and motivation to exercise. Students are receptive to an exercise-based program to support their mental and cognitive health. Students exercise frequency decreased; however, these figures are likely a conservative estimate of students exercise engagement. Students valued the neuroscience-informed approach to motivational and educational content and that the program's goals aligned with their academic goals. Students identified numerous areas PEAK's content and implementation can be optimised, including use of a single digital delivery platform, more opportunities to connect with peers and to expand the content's cultural inclusivity.

Microstructure and Thermal Mechanical Behavior of Arc-Welded Aluminum Alloy 6061-T6

In this study, the welding thermal cycle, as well as the microstructural and mechanical properties of welded AA6061-T6 plates, were studied. The plates were prepared and bead-on-plate welded using gas metal arc welding (GMAW). Numerical simulations using SYSWELD® were performed to obtain the thermal distribution in the welded plates. The numerical heat source was calibrated using the temperatures obtained from the experimental work and the geometry of the melting pool. The mechanical properties were obtained through microhardness tests and were correlated with the welding thermal cycle. Moreover, the mechanical behavior and local deformation in the heat-affected zone (HAZ) were investigated using micro-flat tensile (MFT) tests with digital image correlation (DIC). The mechanical properties of the subzones in the HAZ were then correlated with the welding thermal cycle and with the microstructure of the HAZ. It was observed that the welding thermal cycle produced microstructural variations across the HAZ, which significantly affected the mechanical behavior of the HAZ subzones. The results revealed that MFT tests with the DIC technique are an excellent tool for studying the local mechanical behavior change in AA6061-T6 welded parts due to the welding heat.