Mechanical recycling of CFRPs based on thermoplastic acrylic resin with the addition of carbon nanotubes.

Carbon fibre-reinforced polymers (CFRPs) are commonly used in aviation, automotive and renewable energy markets, which are constantly growing. Increasing the production of composite parts leads to increased waste production and a future increase in end-of-life components. To improve the recyclability of CFRPs, new materials that fit in with the idea of a circular economy should be used as a composite matrix. One such material is a commercially available thermoplastic liquid resin, Elium® (Arkema, France). In this work, the authors investigated how the mechanical recycling process affects the properties of thermoplastic-based carbon fibre composites. CFRPs with neat Elium® resin and resin modified with 0.02 wt.% single-walled carbon nanotubes or 0.02 wt.% multi-walled carbon nanotubes were manufactured using the resin infusion process. Afterwards, prepared laminates were mechanically ground, and a new set of composites was manufactured by thermopressing. The microstructure, mechanical, thermal and electrical properties were investigated for both sets of composites. The results showed that mechanical grinding and thermopressing processes lead to a significant increase in the electrical conductivity of composites. Additionally, a sharp decrease in all mechanical properties was observed.

How can care home activities facilitate social connection in residents? A qualitative study.

OBJECTIVES: Good social connection is associated with better physical and mental health but care home residents experience barriers to social connection. Activities present a potential avenue for improving social connection in care homes but residents often experience loneliness despite access to activity programmes. We therefore aimed to identify what aspects of activities facilitate social connection in care home residents. METHOD: Qualitative study using semi-structured interviews that were analysed using Thematic Analysis. A purposive sample of 35 participants, including 12 residents, 10 family caregivers, nine care home staff and four clinicians, recruited from UK care homes. RESULTS: We found four main themes describing features of activities important for facilitating social connection: (1) personalisation with respect to residents' interests, social preferences, and cognitive ability; (2) activities which foster a sense of community; (3) finding and emphasising things in common that residents share; and (4) facilitating a sense of involvement with others. CONCLUSION: We identified the key aspects of activities which facilitate social connection in care homes. These findings can be applied to a range of existing and newly designed activities in care homes and inform the development and testing of psychosocial interventions aiming to improve social connection.

Comparing accuracy in voice-based assessments of biological speaker traits across speech types.

Nonverbal acoustic parameters of the human voice provide cues to a vocaliser's sex, age, and body size that are relevant in human social and sexual communication, and also increasingly so for computer-based voice recognition and synthesis technologies. While studies have shown some capacity in human listeners to gauge these biological traits from unseen speakers, it remains unknown whether speech complexity improves accuracy. Here, in over 200 vocalisers and 1500 listeners of both sexes, we test whether voice-based assessments of sex, age, height and weight vary from isolated vowels and words, to sequences of vowels and words, to full sentences or paragraphs. We show that while listeners judge sex and especially age more accurately as speech complexity increases, accuracy remains high across speech types, even for a single vowel sound. In contrast, the actual heights and weights of vocalisers explain comparatively less variance in listener's assessments of body size, which do not vary systematically by speech type. Our results thus show that while more complex speech can improve listeners' biological assessments, the gain is ecologically small, as listeners already show an impressive capacity to gauge speaker traits from extremely short bouts of standardised speech, likely owing to within-speaker stability in underlying nonverbal vocal parameters such as voice pitch. We discuss the methodological, technological, and social implications of these results.

Typical diet and type of economy do not predict food-sharing behaviors in three Tanzanian societies.

Food sharing behavior is a widely observed phenomenon, and it draws attention of scholars interested in finding both proximate and ultimate explanations of such practices. In the current study, we focused on possible socio-economic and environmental food-sharing predictors: type of economy (i.e., immediate-return vs. delayed-return) and typical diet composition (i.e., proportion of proteins and carbohydrates in typical daily caloric intake). We investigated whether members of three societies from Tanzania (N = 177), namely hunter-gatherers (Hadza), pastoralists (Datoga), and agriculturalists (Iraqw) differ with regard to food-sharing patterns in the Dictator Game and reactions to violations of the food-sharing norms in the Ultimatum Game. We found that neither the type of economy nor the typical diet influenced our outcomes. The results indicated, however, that food sharing behavior was positively predicted by certain individual-level characteristics: people of higher strength and lower body fat shared more food, and women were more willing to share food than men.

Evil joy is hard to share: Negative affect attenuates interpersonal capitalizing on immoral deeds.

Capitalization is an interpersonal process in which individuals (capitalizers) communicate their accomplishments to others (responders). When these attempts to capitalize are met with enthusiastic responses, individuals reap greater personal and social benefits from the accomplishment. This research integrated the interpersonal model of capitalization with moral foundations theory to examine whether accomplishments achieved through immoral (vs. moral) means disrupt the interpersonal processes of capitalization. We hypothesized that an accomplishment achieved through immoral (vs. moral) means would suppress the positive affective response often reaped from capitalizing on good news. We conducted two, mixed-methods experiments in which individuals interacted with a stranger (Study 1) or with their romantic partner (Study 2). We found that responders exhibited greater self-reported negative emotions, avoidance motivation, and arousal when reacting to capitalizers' immoral (vs. moral) accomplishments. In turn, greater negative affect predicted less enthusiastic verbal responses to capitalization attempts. In Study 2 we found that immoral accomplishments increased avoidance motivation, which contrary to our expectations, increased expressions of happiness. These studies reveal that the moral means by which accomplishments are achieved can disrupt the interpersonal process of capitalization. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Electrically Conductive Adhesive Based on Thermoplastic Hot Melt Copolyamide and Multi-Walled Carbon Nanotubes.

For the bonding of the lightweight composite parts, it is desired to apply electrically conductive adhesive to maintain the ability to shield electromagnetic interference. Among various solvent-based adhesives, there is a new group of thermoplastic hot melt adhesives that are easy to use, solidify quickly, and are environment-friendly. To make them electrically conductive, a copolyamide-based hot melt adhesive was mixed with 5 and 10 wt% of carbon nanotubes using a melt-blending process. Well-dispersed nanotubes, observed by a high-resolution scanning microscope, led to the formation of a percolated network at both concentrations. It resulted in the electrical conductivity of 3.38 S/m achieved for 10 wt% with a bonding strength of 4.8 MPa examined by a lap shear test. Compared to neat copolyamide, Young's modulus increased up to 0.6 GPa and tensile strength up to 30.4 MPa. The carbon nanotubes improved the thermal stability of 20 °C and shifted the glass transition of 10 °C to a higher value. The very low viscosity of the neat adhesive increased about 5-6 orders of magnitude at both concentrations, even at elevated temperatures. With a simultaneous growth in storage and loss modulus this indicates the strong interactions between polymer and carbon nanotubes.

The Composites of Polyamide 12 and Metal Oxides with High Antimicrobial Activity.

The lack of resistance of plastic objects to various pathogens and their increasing activity in our daily life have made researchers develop polymeric materials with biocidal properties. Hence, this paper describes the thermoplastic composites of Polyamide 12 mixed with 1-5 wt % of the nanoparticles of zinc, copper, and titanium oxides prepared by a twin-screw extrusion process and injection moulding. A satisfactory biocidal activity of polyamide 12 nanocomposites was obtained thanks to homogenously dispersed metal oxides in the polymer matrix and the wettability of the metal oxides by PA12. At 4 wt % of the metal oxides, the contact angles were the lowest and it resulted in obtaining the highest reduction rate of the Escherichia coli (87%), Candida albicans (53%), and Herpes simplex 1 (90%). The interactions of the nanocomposites with the fibroblasts show early apoptosis (11.85-27.79%), late apoptosis (0.81-5.04%), and necrosis (0.18-0.31%), which confirms the lack of toxicity of used metal oxides. Moreover, the used oxides affect slightly the thermal and rheological properties of PA12, which was determined by oscillatory rheology, thermogravimetric analysis, and differential scanning calorimetry.

The Relationship between Dark Triad Personality Traits and Sexting Behaviors among Adolescents and Young Adults across 11 Countries.

BACKGROUND: Sexting is an increasingly common phenomenon among adolescents and young adults. Some studies have investigated the role of personality traits in different sexting behaviors within mainstream personality taxonomies like Big Five and HEXACO. However, very few studies have investigated the role of maladaptive personality factors in sexting. Therefore, the present study investigated the relationship between Dark Triad Personality Traits and experimental (i.e., sharing own sexts), risky (i.e., sexting under substance use and with strangers), and aggravated sexting (i.e., non-consensual sexting and sexting under pressure) across 11 countries. METHODS: An online survey was completed by 6093 participants (Mage = 20.35; SDage = 3.63) from 11 different countries which covered four continents (Europe, Asia, Africa, and America). Participants completed the Sexting Behaviors Questionnaire and the 12-item Dark Triad Dirty Dozen scale. RESULTS: Hierarchical regression analyses showed that sharing own sexts was positively predicted by Machiavellianism and Narcissism. Both risky and aggravated sexting were positively predicted by Machiavellianism and Psychopathy. CONCLUSIONS: The present study provided empirical evidence that different sexting behaviors were predicted by Dark Triad Personality Traits, showing a relevant role of Machiavellianism in all kinds of investigated sexting behaviors. Research, clinical, and education implications for prevention programs are discussed.

Approach to Resource Management and Physical Strength Predict Differences in Helping: Evidence From Two Small-Scale Societies.

Helping behavior is likely to have evolved to increase chances of survival of an individual and their group. Nevertheless, populations differ significantly in their eagerness to help, and little is known about populational and inter-individual determinants of these differences. Previous studies indicated that economic and physiological factors might influence helping behavior. The aim of the present study was to investigate the effects of approach to resource management of a society (immediate-return economy vs. delayed-return economy), prenatal androgenization (based on second-to-fourth digit ratio), and physical strength (based on hand grip strength) on helping behavior toward others. Helping was assessed in terms of both general eagerness to help and differential helping toward: (1) kin, (2) other group members indiscriminately, (3) friends, and (4) those from whom help was obtained in the past. Based on data collected in two small-scale societies (n = 306), we found that people in the egalitarian immediate-return society (the Hadza hunter-gatherers of Tanzania) displayed helping behavior significantly more often than people in a more stratified delayed-return economy (Yali horticulturalists of Papua). Additionally, our results revealed that physical strength was a significant predictor of helping behavior in women but not in men. We discuss our findings in the light of the adaptive value of helping behavior.

Trolley Dilemma in Papua. Yali horticulturalists refuse to pull the lever.

Although many studies show cultural or ecological variability in moral judgments, cross-cultural responses to the trolley problem (kill one person to save five others) indicate that certain moral principles might be prevalent in human populations. We conducted a study in a traditional, indigenous, non-Western society inhabiting the remote Yalimo valley in Papua, Indonesia. We modified the original trolley dilemma to produce an ecologically valid "falling tree dilemma." Our experiment showed that the Yali are significantly less willing than Western people to sacrifice one person to save five others in this moral dilemma. The results indicate that utilitarian moral judgments to the trolley dilemma might be less widespread than previously supposed. On the contrary, they are likely to be mediated by sociocultural factors.

Digit ratio and hand grip strength are associated with male competition outcomes: A study among traditional populations of the Yali and Hadza.

OBJECTIVES: Indirect measures of physiological features, such as digit ratio and hand grip strength (HGS), are associated with the outcome of male competition activities. However, most of the studies were conducted in developed and industrialized societies. We tested the hypothesis that both digit ratio and HGS are associated with performance in male-specific activities in two traditional preindustrial societies: Yali and Hadza. METHODS: To measure masculine behavioral traits, we determined warriorship status (Yali; n = 49) and assessed hunting skills (Yali n = 47 and Hadza n = 49). We also assessed the digit ratio and HGS of each male. We conducted our analyses using the Bayesian approach. RESULTS: Bayesian regression models indicated that greater hand grip strength is associated with better hunting outcomes among Hadza males. We did not find a similar link for the Yali. We found anecdotal evidence for the link between left hand digit ratio and the number of birds hunted by Hadza. We found no evidence for the link between digit ratio and performance in male-male competition. CONCLUSIONS: Our results suggest that male-male competition outcomes are determined by upper body strength, but only in the Hadza population. We also found limited support for the hypothesis that digit ratio is associated with hunting success among the Hadza. We found no support for the hypothesis concerning the digit ratio or HGS among the Yali. Our research provides partial support for the evolutionary hypotheses based on studies conducted in industrialized populations.

Does the "incentive hope" hypothesis explain food-wasting behavior among humans? Yes and no.

In this commentary, we discuss how the "incentive hope" hypothesis explains differences in food-wasting behaviors among humans. We stress that the role of relevant ecological characteristics should be taken into consideration together with the incentive hope hypothesis: population mobility, animal domestication, and food-wasting visibility.

Sex Differences in Human Olfaction: A Meta-Analysis.

Although the view that women's olfactory abilities outperform men's is taken for granted, some studies involving large samples suggested that male and female olfactory abilities are actually similar. To address this discrepancy, we conducted a meta-analysis of existing studies on olfaction, targeting possible sex differences. The analyzed sample comprised n = 8 848 (5 065 women and 3 783 men) for olfactory threshold (as measured with the Sniffin Sticks Test; SST), n = 8 067 (4 496 women and 3 571 men) for discrimination (SST), n = 13 670 (7 501 women and 6 169 men) for identification (SST), and a total sample of n = 7 154 (3 866 women and 3 288 men) for works using University of Pennsylvania Smell Identification Test (UPSIT). We conducted separate meta-analyses for each aspect of olfaction: identification, discrimination and threshold. The results of our meta-analysis indicate that women generally outperform men in olfactory abilities. What is more, they do so in every aspect of olfaction analyzed in the current study. However, the effect sizes were weak and ranged between g = 0.08 and g = 0.30. We discuss our findings in the context of factors that potentially shape sex differences in olfaction. Nevertheless, although our findings seem to confirm the "common knowledge" on female olfactory superiority, it needs to be emphasized that the effect sizes we observed were notably small.

Ecology shapes moral judgments towards food-wasting behavior: Evidence from the Yali of West Papua, the Ngorongoro Maasai, and Poles.

People judge food wasting as an immoral behavior. Although moral concerns vary widely across cultures, to this date, food wasting moral judgments were investigated only among rich and industrialized ones. This study reports first evidence of cultural variability on moral judgments of food wasting between modern and traditional cultures. We conducted our study among the Maasai - pastoralists of Ngorongoro, Yali - horticulturalists of West Papua, and among citizens of Poland. According to the results, Maasai judge food wasting as more immoral compared to Yali and Poles. What's more, Yali judge food wasting harsher than Poles. These results suggest that there are cultural differences in moral judgments of food wasting. These differences might reflect the impact of unstable ecology on food economy of a given society. We hypothesize that harsh moral judgment concerning food waste may serve as a cultural adaptation for food insecurity.

No sex difference in digit ratios (2D:4D) in the traditional Yali of Papua and its meaning for the previous hypotheses on the inter-populational variability in 2D:4D.

OBJECTIVES: The ratio between the 2nd and 4th digit (2D:4D) is considered to be a sexually dimorphic trait in humans, with males having on average lower 2D:4D values than females. However, significant inter- and intra-sexual differences in digit ratios across populations have been reported. In order to further explore factors influencing the variability of 2D:4D, we performed a study among the Yali, a traditional population from Papua. METHODS: We measured digit ratios of 79 adults (47 males) from the traditional Yali society, a polygamous group who inhabit a harsh high-mountain environment almost directly on the equator. RESULTS: Statistical analysis of the data show no significant inter-sexual difference in digit ratios in our sample. CONCLUSIONS: We discuss the results in light of various factors that putatively shape the differences in digit ratios. We conclude that the results of our study contribute to the existing evidence suggesting that digit ratio might not be universally sexually dimorphic in humans.

Free mate choice does not influence reproductive success in humans.

The effect of free mate choice on the relative magnitude of fitness benefits has been examined among various species. The majority of the data show significant fitness benefits of mating with partners of an individual's own choice, highlighting elevated behavioral compatibility between partners with free mate choice. Similarities between humans and other species that benefit from free mate choice led us to hypothesize that it also confers reproductive benefits in Homo sapiens. To test this hypothesis, we conducted a study among three indigenous societies-the Tsimane', Yali, and Bhotiya-who employ natural birth control. In all three samples, we compared the marriages arranged by parents with the non-arranged ones in terms of number of offspring. Here, we show that there were no significant relationships between type of marriage and the total number of alive children and number of dead children among the three sampled groups. The presented study is the first to date to examine the fitness benefits of free mate choice in humans. In discussion we present limitations of our research and discuss the possibility of love having a beneficial influence in terms of the number of offspring.

Breast shape (ptosis) as a marker of a woman's breast attractiveness and age: Evidence from Poland and Papua.

OBJECTIVES: A women's breast is a sex-specific and aesthetic bodily attribute. It is suggested that breast morphology signals maturity, health, and fecundity. The perception of a woman's attractiveness and age depends on various cues, such as breast size or areola pigmentation. Conducted in Poland and Papua, the current study investigated how breast attractiveness, and the further estimate of a woman's age based on her breast's appearance, is affected by the occurrence of breast ptosis (ie, sagginess, droopiness). METHODS: In the Polish sample, 57 women and 50 men (N = 107) were presented with sketches of breasts manipulated to represent different stages of ptosis based on two different breast ptosis classifications. The participants were asked to rate the breast attractiveness and age of the woman whose breasts were depicted in each sketch. In Papua, 45 men aged 20 to 75 years took part in the study, which was conducted using only one of the classifications of breast ptosis. RESULTS: Regardless of the classification used, the results showed that the assessed attractiveness of the breasts decreased as the estimated age increased with respect to the more ptotic breasts depicted in the sketches. The results for Papuan raters were the same as for the Polish sample. CONCLUSIONS: Breast ptosis may be yet another physical trait that affects the perception and preferences of a potential sexual partner. The consistency in ratings between Polish and Papuan raters suggests that the tendency to assess ptotic breasts with aging and a loss of attractiveness is cross-culturally universal.