A study on microstructural, mechanical properties and optimization of wear behavior of friction stir processed AlCrCoFeNi High Entropy Alloy reinforced SS410 using response surface methodology

The equimolar High Entropy Alloy (HEA) is incorporated on the surface of SS410 steel to enhance the mechanical properties for the current industrial scenario. The objective of the present work is to make a first attempt at surface modification of SS410 steel with gas atomization synthesized AlCrCoFeNi HEA powder through Friction Stir Processing (FSP). The microhardness and ultimate tensile strength of the FSP-HEA sample are increased by 41.3 % and 39.1 % respectively due to the high degree of refined grains with 2.84 μm and evenly distributed HEA particles. The wear rate of FSP-HEA samples is optimized by response surface methodology with process parameters including applied load, sliding distance, and sliding velocity. The most influential factor and regression model are derived from experimental results that predict the wear rate by the analysis of variance technique. The worn surface of FSP-HEA samples is evaluated by morphological analysis with corresponding induced wear mechanisms. The minimum wear rate is achieved by optimum process parameters along with higher hardness through particle-stimulated nucleation mechanism, Hall-Petch relation, and dynamic recrystallization. The grain refinement, barrier effect, and grain growth hindrance of HEA particles lead to enhancement in the strength of processed HEA samples.

Assessment of biodegradation of lignocellulosic fiber-based composites - A systematic review

Lignocellulosic fiber-reinforced polymer composites are the most extensively used modern-day materials with low density and better specific strength specifically developed to render better physical, mechanical, and thermal properties. Synthetic fiber-reinforced composites face some serious issues like low biodegradability, non-environmentally friendly, and low disposability. Lignocellulosic or natural fiber-reinforced composites, which are developed from various plant-based fibers and animal-based fibers are considered potential substitutes for synthetic fiber composites because they are characterized by lightweight, better biodegradability, and are available at low cost. It is very much essential to study end-of-life (EoL) conditions like biodegradability for the biocomposites which occur commonly after their service life. During biodegradation, the physicochemical arrangement of the natural fibers, the environmental conditions, and the microbial populations, to which the natural fiber composites are exposed, play the most influential factors. The current review focuses on a comprehensive discussion of the standards and assessment methods of biodegradation in aerobic and anaerobic conditions on a laboratory scale. This review is expected to serve the materialists and technologists who work on the EoL behaviour of various materials, particularly in natural fiber-reinforced polymer composites to apply these standards and test methods to various classes of biocomposites for developing sustainable materials.

Synthesis and thermo-mechanical properties of bioplastics and biocomposites: A systematic review

Materials research relating to bio-based polymers and composites has become the order of the day and several researches are being undertaken on these materials. This is mainly due to the...

Sustainable and renewable nanobiocomposites for sensors and actuators: a review on preparation and performance

BACKGROUND:

Nano-materials derived from sustainable and biodegradable polymers, are the most attractive materials among the researchers. Polymeric nano-biocomposites (PNBCs) are a specific class of materials derived by combining nanosized fillers with polymer materials and the most commonly used nano-fillers were hydroxyapatite, organic or inorganic metal nanoparticles, clays and so on.

METHODS:

Many of the recent researches rendered its focus towards the utilization of biopolymer based hydrogel materials for the fabrication of analyte sensors and electrode modifiers owing to their high permeability nature and faster, mobilization of electrons. Such biopolymer hydrogelutilize newer printing methods in electrode prototyping, which renders portable, flexible, and advanced bioelectronics sensor with high performance characteristics. Few researchers have also stated the use of polyaniline reinforced biocomposites for the fabrication of electro-chemical sensors and actuators because of their advantageous properties, which makes them a potential material choice for electronics applications.

RESULTS:

Nano-particles of polyaniline were proved to improve the detection limit and sensitivity of the sensor even when used for recognizing a single molecules. Bionanocomposites possess excellent thermo-mechanical properties in the designed nanocomposite, even at low nanoparticle concentrations. In fact, these materials have high hardness and stability, giving rise to excellent mechanical characteristics. Furthermore, the incorporation of nanoparticles into a biopolymeric matrix enhanced its electrical conductivity, barrier properties, and consistency. Also, the powerful interaction between biopolymers and functional groups of nanoparticles increased the strength of bio-nanocomposites.

CONCLUSION:

Nanobiocomposites based biosensors were found to possess high specificity, sensitivity, and wider target spectrum. Current review deals with the use of sustainable and renewable biocomposites for the preparation of biosensors and actuators, their properties like sensitivity, limit of detection, advantages over the synthetic material and environmental hazards.

Psychometric evaluation of the Short-Form Vaping Consequences Questionnaire for use with high school adolescents who use and do not use e-cigarettes

BACKGROUND

Assessing youth vaping expectancies using a psychometrically sound measure can improve understanding of e-cigarette susceptibility and use.

METHODS

We evaluated the psychometric properties of the Short-Form Vaping Consequences Questionnaire (SF-VCQ), an expectancy measure previously validated with adults, within a sample of 1,753 high school adolescents who completed an online, school-based survey in Fall 2020 (51.6% female; 15.56[1.22] years old; 46.6% non-Hispanic white; 26.9% reported lifetime but no past-30-day vaping; 12.6% reported past-30-day vaping). Analyses included confirmatory factor analysis, internal consistency, measurement invariance, between-group differences, and test-criterion relationships.

RESULTS

The 4-factor structure was confirmed and was scalar invariant by lifetime and past-month vaping status, sex, and race. All subscales were internally reliable (mean α=0.94). The subscales were sensitive to differences based on sex, race, vaping susceptibility among never users, and lifetime and past-month vaping status. For example, students who vaped in the past-month held weaker expectancies for negative consequences but stronger expectancies for positive reinforcement, negative reinforcement, and appetite/weight control compared to lifetime vapers. Unadjusted relationships within the subsamples of lifetime and past-month vapers provided evidence of convergent validity. Evidence for concurrent validity was observed for all samples after accounting for covariates. For example, expectancies for positive reinforcement, negative reinforcement, and appetite/weight control remained significantly associated with past-month vaping frequency.

CONCLUSIONS

The SF-VCQ evidenced excellent internal reliability, scalar measurement invariance, and construct, convergent, and concurrent validity in samples of never, lifetime, and past-month adolescent e-cigarette users. Findings support using the SF-VCQ for assessing youths' vaping-related expectancies.

IMPLICATIONS

The current study established the psychometric properties of the SF-VCQ for use among adolescents with and without vaping experience, including measurement invariance that permits direct comparisons of expectancies across these two groups. When considered in concert with previously published research in adults, the SF-VCQ provides researchers with a measure that can be used with both youth and adult samples. Observed relationships between positive expectancies and vaping susceptibility in vaping naïve youth and indices of vaping frequency in youth with vaping experience suggest that challenging positive expectancies may be a valuable addition to prevention and intervention efforts to reduce youth vaping.

Demographic and substance use-related differences among high school adolescents who vape cannabis versus use other cannabis modalities

BACKGROUND

Vaping is the second most common modality of using cannabis following smoking. We examined differences in demographics and substance use behaviors between adolescent cannabis vapers and those exclusively using other cannabis modalities.

METHODS

In 2019, 4875 students from six Connecticut high schools completed school-wide, online surveys. Past-month cannabis users (n = 931; 52.8% female, 16.38(1.27) years old, 44.9% non-Hispanic White) reported on cannabis modalities used (e.g., combustible, vaporizable, edible) and were classified as cannabis vapers or non-vapers. Cannabis vapers reported on device type used to vape cannabis: a cannabis-specific device or modified/hacked e-cigarette. Unadjusted and adjusted relationships were examined to identify demographic and substance-related differences between cannabis vapers and non-vapers.

RESULTS

56.3% of past-month cannabis users reported vaping cannabis. Cannabis vapers reported using both cannabis-specific vaporizers (91.9%) and modifying/hacking e-cigarettes (23.7%). Cannabis vapers, relative to other cannabis users, were more likely to be male, White, initiate cannabis use at a younger age; endorse past-month use of all cannabis modalities, alcohol, and e-cigarettes; and report smoking and dabbing cannabis more frequently; consuming more drinks per drinking day; and using e-cigarettes at a younger age and more frequently.

CONCLUSIONS

Relative to other cannabis modalities, vaping was associated with increased use of several cannabis products and other substances. Adolescent past-month cannabis users reported modifying e-cigarettes to vape cannabis. Findings suggest that regulations should be implemented to prevent e-cigarettes from being modifiable for use with cannabis and highlight the importance of assessing different cannabis use modalities, as vaping was associated with distinct substance-related risks.

Advanced spatial knowledge of target location eliminates age-related differences in early sensorimotor learning

Motor learning has been shown to decline in healthy aging, particularly in the early stages of acquisition. There is now ample evidence that motor learning relies on multiple interacting learning processes that operate on different timescales, but the specific cognitive mechanisms that contribute to motor learning remain unclear. Working memory resources appear to be particularly important during the early stages of motor learning, and declines in early motor learning have been associated with working memory performance in older adults. We examined whether age differences in the early stages of motor learning could be reduced or eliminated by reducing the spatial working memory demands during a force-field adaptation task. Groups of younger and older adults made center-out reaching movements to spatial targets either in a repeating four-element sequence, or in a random order. Participants also performed a battery of cognitive tests to further investigate the potential involvement of associative memory, spatial working memory, and procedural learning mechanisms in the early stage of motor learning. Although all groups adapted their movements equally well by the end of the learning phase, older adults only adapted as quickly as younger adults in the sequence condition, with the older adults in the random group exhibiting slower learning in the earliest stage of motor learning. Across all participants, early motor learning performance was correlated with recognition memory performance on an associative memory test. Within the younger random group, who were able to adapt as quickly as the sequence groups, early motor learning performance was also correlated with performance on a test of procedural learning. These findings suggest that age differences in early stages of motor learning can be eliminated if the spatial working memory demands involved in a motor learning task are limited. Moreover, the results suggest that multiple cognitive resources may be utilized during the early stage of learning, and younger adults may be more flexible than older adults in the recruitment of additional cognitive resources to support learning when spatial working memory demands are high.